JP2012102429A - Oil agent for acrylic fiber for producing carbon fiber, acrylic fiber for producing carbon fiber and method for producing carbon fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil agent for acrylic fiber for producing carbon fiber which has an excellent carbon fiber strength.SOLUTION: An oil agent for acrylic fiber for producing carbon fiber contains a modified silicone(A), and a siloxane(B) represented by the following general formula(1) or (2).

Description

  The present invention relates to an acrylic fiber oil agent for producing carbon fibers, an acrylic fiber for producing carbon fibers, and a method for producing carbon fibers for providing carbon fibers having excellent strength. More specifically, an acrylic fiber oil for carbon fiber production (hereinafter referred to as a precursor oil) that provides excellent strength when used in producing acrylic fibers for carbon fiber production (hereinafter sometimes referred to as a precursor). The present invention relates to an acrylic fiber for producing carbon fiber that has been produced by applying the oil, and a method for producing carbon fiber using the oil.

Carbon fibers are widely used for aerospace applications, sports applications, general industrial applications and the like as reinforcing fibers for composite materials with plastics called matrix resins, utilizing their excellent mechanical properties.
As a method for producing carbon fibers, first, a precursor is produced (this precursor production process may be referred to as a yarn production process). This precursor is converted to a flame-resistant fiber in an oxidizing atmosphere at 200 to 300 ° C. (this process may hereinafter be referred to as a flame resistance process), and then carbonized in an inert atmosphere at 300 to 2000 ° C. (This process may be hereinafter referred to as a carbonization process) is a common method (hereinafter, the flameproofing process and the carbonization process may be collectively referred to as a firing process). Since this precursor is subjected to a stretching process that is stretched at a high magnification even compared to ordinary acrylic fibers, fusion of single fibers is likely to occur. In order to prevent this fusion, silicone precursors with excellent heat resistance and excellent peelability due to smoothness between fibers and fibers, especially amino-modified silicone oils that can further improve heat resistance by crosslinking reaction, are given to precursors. Many techniques have been proposed (see Patent Documents 1 and 2) and are widely used industrially.

  These silicone oils are generally made into emulsions dispersed in water in order to adhere industrially safely and uniformly to the precursor. Therefore, when the silicone component used does not have self-emulsifying properties, various surfactants and the like are used together as an emulsifier component to be emulsified. However, even with the silicone-based oils described in the prior art, carbon fibers having sufficient strength may not be obtained.

JP-A-6-220722 JP 2004-149983 A

  In view of the conventional technical background, an object of the present invention is to provide an acrylic fiber oil agent for producing carbon fibers, an acrylic fiber for producing carbon fibers, and a method for producing carbon fibers, which can provide excellent carbon fiber strength.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have excellent strength if it is an acrylic fiber oil agent for carbon fiber production containing a modified silicone (A) and a specific low molecular weight siloxane (B). It has been found that carbon fibers can be produced.

  That is, the present invention provides at least one low molecular weight selected from a modified silicone (A) having a modifying group containing a nitrogen atom, a siloxane represented by the following general formula (1), and a siloxane represented by the following general formula (2). It is an acrylic fiber oil agent for carbon fiber production containing siloxane (B).

（式（１）中、ｍは１〜４の整数を示す。）

(In formula (1), m represents an integer of 1 to 4.)

（式（２）中、ｎは３〜６の整数を示す。）

(In formula (2), n represents an integer of 3 to 6)

  It is preferable that the weight percentage of the modified silicone (A) in the total pure content of the oil is 60 to 95% by weight, and the weight percentage of the low molecular weight siloxane (B) is 0.1 to 10% by weight.

  Moreover, the acrylic fiber oil agent for carbon fiber production further contains a surfactant (C), and it is preferable that the weight ratio of the surfactant (C) to the whole pure component of the oil agent is 5 to 40% by weight. .

The modified silicone is preferably a modified silicone having a modifying group containing a nitrogen atom.
Moreover, it is preferable that the acrylic fiber oil agent for carbon fiber manufacture concerning this invention becomes the emulsion disperse | distributed in water.

  The acrylic fiber for carbon fiber production (precursor) according to the present invention is produced by attaching the above-mentioned acrylic fiber oil agent for carbon fiber production to the raw acrylic fiber of the acrylic fiber for carbon fiber production.

  Moreover, the carbon fiber manufacturing method according to the present invention comprises the above-mentioned acrylic fiber oil agent for carbon fiber production (precursor oil agent) attached to the raw acrylic fiber of the acrylic fiber for carbon fiber production, and the acrylic fiber for carbon fiber production (precursor). ), A flameproofing process for converting the acrylic fiber for carbon fiber production produced in the spinning process into a flameproof fiber in an oxidizing atmosphere at 200 to 300 ° C., and the flameproof fiber further And a carbonization treatment step of carbonizing in an inert atmosphere at 300 to 2000 ° C.

  The acrylic fiber oil agent for producing carbon fiber of the present invention suppresses defects in the firing process in the production of carbon fiber and improves the strength of the carbon fiber by being attached to the raw acrylic fiber of the acrylic fiber for producing carbon fiber and processing. Can be made. Moreover, in the carbon fiber manufacturing method of the present invention, since the acrylic fiber oil for carbon fiber manufacturing is adhered, a high-strength carbon fiber can be manufactured.

The acrylic fiber oil agent for carbon fiber production (precursor oil agent) of the present invention is a process for producing an acrylic fiber for carbon fiber production (precursor). In order to produce a uniform precursor fiber bundle, the precursor raw material acrylic before the stretching process is used. It is an oil whose primary purpose is to be imparted to fibers.
The present invention provides a carbon containing the modified silicone (A) and at least one low molecular weight siloxane (B) selected from the siloxane represented by the general formula (1) and the siloxane represented by the general formula (2). Acrylic fiber oil for fiber production. This will be described in detail below.

[Modified silicone (A)]
The precursor oil agent of this invention contains a modified silicone (A) essential. The modified silicone (A) is generally a reactive (functional) group or a non-functional group at least at one of the both ends, one end, side chain, and both side chains of a polysiloxane such as dimethyl silicone (polydimethylsiloxane). It has a structure in which at least one reactive (functional) group is bonded.
Examples of the modified silicone (A) include modified silicone having a modifying group containing a nitrogen atom, dimethyl silicone, epoxy modified silicone, alkylene oxide modified silicone (polyether modified silicone), carboxy modified silicone, carbinol modified silicone, alkyl modified silicone, Examples include phenol-modified silicone, methacrylate-modified silicone, alkoxy-modified silicone, and fluorine-modified silicone. One type of modified silicone may be used, or a plurality of modified silicones may be used in combination. Among these, a modified silicone having a modifying group containing a nitrogen atom is preferable.

  The weight ratio of the modified silicone (A) in the total pure content of the oil is preferably 60 to 95% by weight, more preferably 65 to 90% by weight, further preferably 70 to 85% by weight, particularly 70 to 80% by weight. preferable. When the weight ratio of the modified silicone (A) in the total pure content of the oil agent is less than 60% by weight, the anti-fusing effect in the firing step may be inferior and it may be difficult to obtain high-strength carbon fibers. In addition, when the weight ratio of the modified silicone (A) in the whole pure oil is more than 95% by weight, aqueous emulsification becomes difficult and a stable solution may not be obtained. In addition, in this invention, the pure part of an oil agent means the oil agent component except water.

(Modified silicone with modified groups containing nitrogen atoms)
In the modified silicone having a modifying group containing a nitrogen atom, the type of the modifying group is not particularly limited as long as it is a modifying group containing a nitrogen atom. Examples of the modifying group containing a nitrogen atom include a modifying group containing an amino bond or an imino bond (ie, an amino group), a modifying group containing an amide bond (ie, an amide group), and the like. A modified group having a plurality of different bonds may be used. The modifying group containing a nitrogen atom may be bonded to the side chain of silicone as the main chain, may be bonded to the terminal, or may be bonded to both. Moreover, you may have a polyoxyalkylene group (For example, a polyoxyethylene group, a polyoxypropylene group, a polyoxybutylene group etc.) in the molecule | numerator.

  Examples of the modified silicone having a modified group containing a nitrogen atom include amino-modified silicone, amino polyether-modified silicone, amide-modified silicone, amide-polyether-modified silicone, and one kind of modified silicone may be used. A plurality of modified silicones may be used in combination. Moreover, it is preferable that content of the nitrogen atom in modified silicone is 0.1 to 3.5 weight%. When the content of nitrogen atoms is lower than 0.1% by weight, the crosslinkability is inferior and sufficient heat resistance may not be obtained. Moreover, when higher than 3.5 weight%, the adhesiveness of a modified silicone becomes high and may cause a gum-up.

  Among these modified silicones having a modifying group containing a nitrogen atom, amino-modified silicones and aminopolyether-modified silicones are preferred because they have excellent crosslinkability and better heat resistance in the firing step. Furthermore, amino-modified silicone is particularly preferred from the viewpoint of excellent stability over time.

(Amino-modified silicone)
When the modified silicone (A) is an amino-modified silicone, the structure of the amino-modified silicone is not particularly limited. That is, the amino group that is a modifying group may be bonded to the side chain of silicone that is the main chain, may be bonded to the terminal, or may be bonded to both. The amino group may be a monoamine type or a polyamine type, and both may be present in one molecule.
The amino group (NH ₂ ) content (hereinafter referred to as “amino weight%”) in the amino-modified silicone is preferably 0.1 to 4.0% by weight, more preferably 0.3 to 1.5% by weight, 0.4 to 0.8% is more preferable. When amino weight% is lower than 0.1 weight%, crosslinking property may be inferior and sufficient heat resistance may not be obtained. On the other hand, when the content is higher than 4.0% by weight, the tackiness of the amino-modified silicone increases, which may cause gum up.

The viscosity of the amino-modified silicone at 25 ° C. is not particularly limited. However, if the viscosity is too low, the problem is that fiber fusion cannot be prevented due to scattering of the oil agent or heat volatilization due to insufficient heat resistance in the baking process. It may become. On the other hand, if the viscosity is too high, gum-up due to adhesiveness may be a problem. From the standpoint of preventing these problems, the viscosity at 25 ° C. of an amino-modified silicone is preferably 100~15,000mm ² / s, more preferably 500~10,000mm ² / s, 1,000~5,000mm ² / s is particularly preferred.

[Low molecular weight siloxane (B)]
The precursor oil agent of the present invention essentially contains at least one low molecular weight siloxane (B) selected from the siloxane represented by the general formula (1) and the siloxane represented by the general formula (2). These low molecular weight siloxanes may be used alone or in combination of two or more.
The reason why the carbon fiber produced by attaching the precursor oil of the present invention containing the low molecular weight siloxane (B) in addition to the modified silicone (A) can exhibit high strength is not clear, but is estimated as follows. Is done. That is, generally in a precursor manufacturing process, a precursor oil agent is provided to the precursor of the water swelling state before dry densification. Therefore, oil agent molecules and the like are likely to penetrate into the fiber. In particular, components such as various surfactants often have a lower molecular weight than silicone compounds, so that they easily penetrate into the inside of the fiber, and these penetrated components are tarned during the heat treatment in the firing process and are contained in the carbon fiber. There is a risk of a drawback. However, by containing the low molecular weight siloxane (B) in the oil agent, the highly hydrophobic low molecular weight siloxane (B) preferentially penetrates into the fiber, and penetrates components that cause tarring of various surfactants and the like. It works to suppress some. On the other hand, the permeated low molecular weight siloxane (B) is excellent in volatility, so that it volatilizes in the drying process after applying the oil, and even if it remains inside the fiber, it volatilizes without causing tarring and fiber defects in the subsequent firing process. To do. As a result, the carbon fiber produced as a result is presumed to exhibit high strength.

  The weight percentage of the low molecular weight siloxane (B) in the total pure content of the oil agent is preferably 0.1 to 10% by weight, more preferably 0.5 to 7.5% by weight, still more preferably 1 to 5% by weight, 2.5-5% by weight is particularly preferred. When the weight ratio of the low molecular weight siloxane (B) is less than 0.1% by weight, it is difficult to obtain the fiber internal permeation suppressing effect of various surfactants of the present effect. On the other hand, when the content exceeds 10% by weight, the viscosity of the oil composition may be excessively lowered, resulting in insufficient convergence of the precursor, or significant baking furnace contamination due to excessive volatile components.

The siloxane represented by the general formula (1) is a chain-like low molecular weight siloxane. In formula (1), m represents an integer of 1 to 4, and 2 to 4 are preferable from the viewpoint of volatility. When m exceeds 4, sufficient volatility may not be obtained.
The siloxane represented by the general formula (2) is a cyclic low molecular weight siloxane. In general, examples of the cyclic siloxane include cyclic siloxanes D _n having a siloxane bond (SiOR ¹ R ² : R ¹ , R ² represents an organic group) of 3 to 20 (n is an integer indicating the bond amount). However, in the treatment agent of the present invention, cyclic low molecular weight siloxane (D _{3 to} D ₆ ) which is a 3 to 6 mer of dimethylsiloxane (SiO (CH ₃ ) ₂ ) is used. Therefore, in Formula (2), n shows the integer of 3-6. From the viewpoint of volatility, n is preferably 4 to 5.

  As the low molecular weight siloxane (B), when the number of Si in the molecule is the same, the cyclic siloxane represented by the general formula (2) is more volatile than the siloxane represented by the general formula (1). For this reason, the siloxane represented by the general formula (2) is preferable.

The number average molecular weight of the low molecular weight siloxane (B) is preferably 500 or less, more preferably 200 to 400, and even more preferably 200 to 300. When the number average molecular weight exceeds 500, volatility may be reduced.
Viscosity of the low molecular weight siloxane (B) (25 ℃) is preferably 0.5~4.5mm ² / s, more preferably from 1 to 4 mm ² / s, more preferably 2-4 mm ² / s.

[Surfactant (C)]
It is preferable that the precursor oil agent of the present invention can be water-based emulsified, and for that purpose, it preferably contains a surfactant (C). The surfactant (C) may be a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant.

  Examples of the nonionic surfactant include polyoxyalkylene linear alkyl ethers such as polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, and polyoxyethylene cetyl ether; Polyoxyalkylene branched primary alkyl ethers such as polyoxyethylene 2-ethylhexyl ether, polyoxyethylene isocetyl ether, polyoxyethylene isostearyl ether; polyoxyethylene 1-hexyl hexyl ether, polyoxyethylene 1-octyl hexyl ether Polyoxyethylene 1-hexyl octyl ether, polyoxyethylene 1-pentyl heptyl ether, polyoxyethylene 1-heptylpentyl ether Polyoxyalkylene branched secondary alkyl ethers such as ter; polyoxyalkylene alkenyl ethers such as polyoxyethylene oleyl ether; polyoxys such as polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether Alkylene alkyl phenyl ether; polyoxyethylene tristyryl phenyl ether, polyoxyethylene distyryl phenyl ether, polyoxyethylene styryl phenyl ether, polyoxyethylene tribenzyl phenyl, polyoxyethylene dibenzyl phenyl ether, polyoxyethylene benzyl phenyl ether, etc. Polyoxyalkylene alkyl aryl phenyl ethers; polyoxyethylene monolaure Polyoxyethylene monooleate, polyoxyethylene monostearate, polyoxyethylene monomyristate, polyoxyethylene dilaurate, polyoxyethylene diolate, polyoxyethylene dimyristate, polyoxyethylene distearate, etc. Polyoxyalkylene fatty acid esters; sorbitan esters such as sorbitan monopalmitate and sorbitan monooleate; polyoxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate; glycerin monostearate and glycerin monolaur Glycerin fatty acid esters such as rate and glycerin monopalmitate; Polyoxyalkylene sorbitol fatty acid ester; Sucrose fatty acid ester Polyoxyalkylene castor oil ether such as polyoxyethylene castor oil ether; polyoxyalkylene hardened castor oil ether such as polyoxyethylene hydrogenated castor oil ether; polyoxyalkylene alkylamino such as polyoxyethylene lauryl amino ether and polyoxyethylene stearyl amino ether Ether; Oxyethylene-oxypropylene block or random copolymer; Oxyethylene-oxypropylene block or random copolymer terminal alkyl etherified product; Oxyethylene-oxypropylene block or random copolymer terminal sucrose etherified product; etc. Can be mentioned.

  Among these nonionic surfactants, polyoxyalkylene branched primary alkyl ethers, polyoxyalkylene branched secondary alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyalkylene ethers, Oxyalkylene alkyl phenyl ethers, polyoxyalkylene fatty acid esters, oxyethylene-oxypropylene block copolymers, and terminal alkyl etherified products of oxyethylene-oxypropylene block copolymers are preferred.

  Examples of the anionic surfactant include fatty acids (salts) such as oleic acid, palmitic acid, sodium oleate, potassium palmitate, triethanolamine oleate; hydroxyacetic acid, potassium hydroxyacetate, lactic acid, lactic acid Hydroxyl group-containing carboxylic acid (salt) such as potassium salt; polyoxyalkylene alkyl ether acetic acid (salt) such as polyoxyethylene tridecyl ether acetic acid (sodium salt); and many carboxyl groups such as potassium trimellitic acid and potassium pyromellitic acid Substituted aromatic compound salts; alkylbenzene sulfonic acid (salt) such as dodecylbenzene sulfonic acid (sodium salt); polyoxyalkylene alkyl ether sulfonic acid (salt) such as polyoxyethylene 2-ethylhexyl ether sulfonic acid (potassium salt); Higher fatty acid amide sulfonic acid (salt) such as theaeroylmethyl taurine (sodium), lauroyl methyl taurine (sodium), myristoyl methyl taurine N (sodium), palmitoyl methyl taurine (sodium); N- such as lauroyl sarcosine acid (sodium) Acyl sarcosine acid (salt); alkyl phosphonic acid (salt) such as octyl phosphonate (potassium salt); aromatic phosphonic acid (salt) such as phenyl phosphonate (potassium salt); 2-ethylhexyl phosphonate mono 2-ethylhexyl ester (potassium salt) Alkylphosphonic acid ester (salt) such as aminophosphonic acid (diethanolamine salt), etc .; alkylsulfuric acid such as 2-ethylhexyl sulfate (sodium salt); Esters (salts); polyoxyalkylene sulfates (salts) such as polyoxyethylene 2-ethylhexyl ether sulfate (sodium salt); lauryl phosphate (potassium salt), cetyl phosphate (potassium salt), stearyl phosphate (diethanolamine salt), etc. Alkyl phosphate ester (salt); polyoxyethylene lauryl ether phosphate (potassium salt), polyoxyalkylene alkyl (alkenyl) ether phosphate ester (salt) such as polyoxyethylene oleyl ether phosphate (triethanolamine salt); polyoxyethylene nonyl Polyoxyalkylene alkyl phenyl ethers such as phenyl ether phosphate (potassium salt) and polyoxyethylene dodecyl phenyl ether phosphate (potassium salt) -Terphosphate (salt); long-chain sulfosuccinate such as sodium di-2-ethylhexyl sulfosuccinate and dioctyl sodium sulfosuccinate, monosodium N-lauroyl glutamate, long-chain N such as disodium N-stearoyl-L-glutamate -Acyl glutamate; and the like.

  Examples of the cationic surfactant include quaternary ammonium salts such as lauryltrimethylammonium chloride and oleylmethylethylammonium ethosulphate; (polyoxyethylene) laurylaminoether lactate, stearylaminoether lactate, (polyoxyethylene) ) (Polyoxyalkylene) alkylamino ether salts such as lauryl amino ether trimethyl phosphate salt;

  Examples of amphoteric surfactants include 2-undecyl-N, N- (hydroxyethylcarboxymethyl) -2-imidazoline sodium, 2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt, and the like. Imidazoline-based amphoteric surfactants; 2-heptadecyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine, lauryldimethylaminoacetic acid betaine, alkylbetaines, amide betaines, sulfobetaine, and other betaine-based amphoteric surfactants; N- Amino acid type amphoteric surfactants such as lauryl glycine, N-lauryl β-alanine, N-stearyl β-alanine and the like can be mentioned.

  Among these surfactants, ionic surfactants may change over time after emulsification, and may also affect the crosslinkability of silicone. For this reason, nonionic surfactants are preferred because they are excellent in stability over time, have little effect on silicone crosslinkability, and are excellent in emulsifying power of silicone.

  In the precursor oil agent of the present invention, the weight ratio of the surfactant (C) to the whole pure component of the oil agent is 5 to 40 weights from the viewpoint of emulsion stability when used as an emulsifier and maintaining the heat resistance of the oil agent. 10 to 30% by weight, more preferably 15 to 20% by weight. When the weight ratio of the surfactant (C) in the whole pure component is less than 5% by weight, it is difficult to obtain good emulsification stability, and when it exceeds 40% by weight, the heat resistance of the oil agent is insufficient and firing is performed. It is difficult to obtain anti-fusing properties in the process.

[Precursor oil]
In addition to the above-described components, the precursor oil of the present invention is a monocarboxylic acid such as a straight chain fatty acid, a branched chain fatty acid, or a lower monocarboxylic acid, an antioxidant such as a phenol, amine, sulfur, phosphorus, or quinone. Agents: sulfates of higher alcohols / higher alcohol ethers, sulfonates, phosphate esters of higher alcohols / higher alcohol ethers, quaternary ammonium salt type cationic surfactants, amine salt type cationic surfactants, etc. Antistatic agents; smoothing agents such as higher alcohol alkyl esters, higher alcohol ethers and waxes; antibacterial agents; antiseptics; rust preventives; and hygroscopic agents may be contained within a range that does not impair the effects of the present invention. Good.

The precursor oil may be composed of the above-mentioned components, but from the viewpoint of uniform adhesion to the fiber and safety of the working environment, it contains a surfactant as an emulsifier, and is emulsified or dispersed in water. A state in which the emulsion is dispersed in water is preferable.
When the precursor oil of the present invention contains water, the weight ratio of water in the entire precursor oil, the weight ratio of the pure component is not particularly limited, for example, the transportation cost when transporting the precursor oil of the present invention, What is necessary is just to determine suitably considering the handleability etc. which depend on emulsion viscosity. The weight ratio of water in the entire precursor oil 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 the pure component in the entire precursor oil 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.

  The precursor oil of the present invention can be produced by mixing the modified silicone (A), the low molecular weight siloxane (B), and other components described above. The low molecular weight siloxane (B) may be used as a mixture with the modified silicone (A). Of course, a predetermined amount of low molecular weight siloxane (B) may be contained as an unreacted material unintentionally contained during the modified silicone polymerization. When the precursor oil is a composition in the state of being emulsified or dispersed in water, the method for emulsifying and dispersing the components described above is not particularly limited, and a known method can be adopted. As such a method, for example, a modified silicone (A), a low molecular weight siloxane (B), and other components are added in warm water under stirring in any order and emulsified and dispersed. A mixture containing the molecular weight siloxane (B), a method of emulsifying and dispersing other components in warm water under stirring in any order, a mixture containing the modified silicone (A) and the low molecular weight siloxane (B), and Examples of the method include mixing other components and gradually injecting water while applying mechanical shearing force using a homogenizer, a homomixer, a ball mill, or the like to phase-emulsify.

Moreover, a precursor and carbon fiber can be manufactured using the precursor oil agent of this invention. The method for producing a precursor and carbon fiber using the precursor oil of the present invention is not particularly limited, and examples thereof include the following production methods.
[Precursor and carbon fiber production method]
The method for producing carbon fiber of the present invention includes a yarn making process, a flameproofing process, and a carbonization process. The precursor of the present invention is obtained by this spinning process.
The yarn making process is a process of manufacturing a precursor by adhering the acrylic fiber oil agent for carbon fiber production (precursor oil agent) to the raw acrylic fiber for acrylic fiber for carbon fiber production (precursor), and includes an adhesion treatment process and a stretching process. Including.
The adhesion treatment process is a process of adhering the precursor oil agent after spinning the precursor raw acrylic fiber. That is, the precursor oil agent is adhered to the precursor raw acrylic fiber in the adhesion treatment step. The precursor raw acrylic fiber is stretched immediately after spinning, and the high-strength stretching after the adhesion treatment step is particularly called a “stretching step”. The stretching process may be a wet heat stretching method using high temperature steam or a dry heat stretching method using a hot roller.

  A precursor is comprised from the acrylic fiber which has as a main component the polyacrylonitrile obtained by copolymerizing at least 95 mol% or more of acrylonitrile and 5 mol% or less of a flame-resistant acceleration | stimulation component. As the flame resistance promoting component, a vinyl group-containing compound having copolymerizability with acrylonitrile can be suitably used. Although there is no limitation in particular about the single fiber fineness of a precursor, from the balance of a performance and manufacturing cost, Preferably it is 0.1-2.0 dTex. Further, the number of single fibers constituting the precursor fiber bundle is not particularly limited, but is preferably 1,000 to 96,000 from the balance between performance and production cost.

  The precursor oil may be attached to the precursor raw acrylic fiber at any stage of the yarn production process, but is preferably attached once before the drawing process. It may be attached at any stage before the stretching process, for example, immediately after spinning. Further, it may be reattached at any stage after the stretching process, for example, it may be reattached immediately after the stretching process, it may be reattached at the winding stage, or it may be reattached immediately before the flameproofing process. May be. Regarding the adhesion method, when the precursor oil consists only of pure components, it may be adhered using a roller or the like as a straight oil, or the precursor oil is emulsified or dispersed in a solvent such as water or an organic solvent. In the case of an emulsion, it may be attached by dipping or spraying.

  In the adhesion treatment process, the rate of applying the precursor oil is to obtain an anti-sticking effect and an anti-fusing effect between the fibers and fibers, and to prevent deterioration of the quality of the carbon fiber due to the tar product of the oil in the carbonization treatment process. From this balance, it is preferably 0.1 to 2% by weight, more preferably 0.3 to 1.5% by weight, based on the weight of the precursor. When the application rate of the precursor oil is less than 0.1% by weight, sticking and fusion between single fibers cannot be sufficiently prevented, and the strength of the obtained carbon fibers may be lowered. On the other hand, when the application rate of the precursor oil is more than 2% by weight, the precursor oil covers more than necessary between the single fibers, so that the supply of oxygen to the fibers is hindered in the flameproofing process, and the strength of the obtained carbon fiber May decrease. In addition, the provision rate of a precursor oil agent here is defined by the percentage of the pure part weight to which the precursor oil agent adhered with respect to the precursor weight.

  The flameproofing treatment step is a step of converting the precursor to which the precursor oil is adhered into flameproof fibers 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 flameproofing treatment step, the acrylic fiber after the adhesion treatment is applied for 20 to 100 minutes (preferably 30) while applying a tension ratio of 0.90 to 1.10 (preferably 0.95 to 1.05). Heat treatment is performed for ˜60 minutes. In this flameproofing treatment, a flameproof fiber having a flameproof structure is produced through intramolecular cyclization and oxygen addition to the ring.

  The carbonization treatment step is a step of carbonizing the flameproof fiber in an inert atmosphere of 300 to 2000 ° C. In the carbonization treatment step, 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 ratio of 0.95 to 1.15 is applied to the flameproof fiber. It is preferable to carry out a pre-carbonization treatment step (first carbonization treatment step) by applying heat treatment for several minutes while applying. Thereafter, in order to further promote carbonization and advance graphitization, a tension ratio of 0.95 to 1.05 is applied to the first carbonization treatment step in an inert atmosphere such as nitrogen or argon. While being applied, heat treatment is performed for several minutes to perform the second carbonization treatment step, and the flame resistant fiber is carbonized. About control of the heat processing temperature in a 2nd carbonization process process, it is good to make maximum temperature into 1000 degreeC or more (preferably 1000-2000 degreeC), 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.

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

  The carbon fiber thus obtained can be subjected to a surface treatment for increasing the adhesive strength with the matrix resin when made into a composite material, depending on the purpose. As the surface treatment method, gas phase or liquid phase treatment can be adopted, and from the viewpoint of productivity, liquid phase treatment with an electrolytic solution of acid, alkali or the like is preferable. Furthermore, various sizing agents having excellent compatibility with the matrix resin can be added to improve the processability and handleability of the carbon fiber.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, it is not limited to the Example described here. The percent (%) shown in the following examples represents “% by weight” unless otherwise specified.

[Example 1]
Amino-modified silicone KF-861 (manufactured by Shin-Etsu Chemical Co., Ltd., 25 ° C. viscosity: 3,500 mm ² / s, amino equivalent: 2,000 g / mol, containing about 1% by weight of D4) under a reduced pressure of 1.3 kPa, While stirring, the mixture was heated at 80 ° C. for 3 hours to prepare a D4 content of 0% by weight (referred to as KF-861M). This KF-861M blended with D5 and surfactant N-1 is water-based emulsified, and as a pure oil (component excluding water) composition, KF-861M / D5 / N-1 = 80/5/15 An oil emulsion (precursor oil) having a weight ratio of The pure content concentration of the oil was 3.0% by weight. This oil agent emulsion was attached to a precursor (single fiber fineness 0.8 dtex, 24,000 filaments) so that the application rate of pure component was 1.0%, and dried at 100 to 140 ° C. to remove moisture. The precursor after adhering the oil was flameproofed for 60 minutes in a 250 ° C flameproofing furnace, and then baked in a carbonization furnace having a temperature gradient of 300 to 1400 ° C in a nitrogen atmosphere to be converted into carbon fibers. The carbon fiber strength (GPa) of the obtained carbon fiber was measured according to the epoxy resin impregnated strand method defined in JIS-R-7601, and obtained as an average value of 10 measurements. The results are shown in Table 1.

[Examples 2 to 4, Comparative Examples 1 and 2]
In Example 1, the precursor and carbon fiber after oil agent adhesion were obtained in the same manner as in Example 1 except that the oil agent emulsion was prepared so as to have a pure oil component (components excluding water) shown in Table 1. . Table 1 shows the carbon fiber strength evaluation results of the obtained carbon fibers.

The contents of the ingredients listed in Table 1 are shown below.
Silicone KF-861M: amino-modified silicone KF-861 (manufactured by Shin-Etsu Chemical Co., Ltd., 25 ° C. viscosity: 3,500 mm ² / s, amino equivalent: 2,000 g / mol, containing about 1% by weight of D4) Silicone KF-880: amino-modified silicone KF-880 (manufactured by Shin-Etsu Chemical Co., Ltd., 25 ° C. viscosity: 650 mm ² / s, amino equivalent: 1,800 g / mol, D4 about 5) (Contains weight%)
D4: Cyclic siloxane tetramer, 2.4 mm ² / s
D5: Cyclic siloxane pentamer, 4.0 mm ² / s
Surfactant N-1: Polyoxyethylene alkyl ether (the alkyl group has C12 to C14) having 3 to 12 repeating units of oxyethylene in consideration of the hydrophilic-hydrophobic balance with the silicone component It selected suitably and used.

Claims (7)

Carbon fiber production containing modified silicone (A) and at least one low molecular weight siloxane (B) selected from siloxane represented by the following general formula (1) and siloxane represented by the following general formula (2) Acrylic fiber oil.

(In formula (1), m represents an integer of 1 to 4.)

(In formula (2), n represents an integer of 3 to 6)   The weight percentage of the modified silicone (A) occupying the entire pure content of the oil agent is 60 to 95% by weight, and the weight percentage of the low molecular weight siloxane (B) is 0.1 to 10% by weight. The acrylic fiber oil agent for carbon fiber manufacture of description.   The acrylic for carbon fiber production according to claim 1 or 2, further comprising a surfactant (C), wherein the weight ratio of the surfactant (C) to the whole pure component of the oil agent is 5 to 40% by weight. Textile oil agent.   The oil agent for acrylic fibers for carbon fiber manufacture according to any one of claims 1 to 3, wherein the modified silicone (A) is a modified silicone having a modifying group containing a nitrogen atom.   The acrylic fiber oil preparation for carbon fiber production according to any one of claims 1 to 4, which is an emulsion dispersed in water.   The acrylic fiber for carbon fiber manufacture which made acrylic fiber oil agent for carbon fiber manufacture in any one of Claims 1-5 adhere to the raw material acrylic fiber of the acrylic fiber for carbon fiber manufacture, and was made into a yarn.   A yarn production process for producing an acrylic fiber for carbon fiber production by attaching the acrylic fiber oil for carbon fiber production according to any one of claims 1 to 5 to a raw material acrylic fiber for acrylic fiber for carbon fiber production, and a yarn production process thereof A flameproofing step of converting the acrylic fiber for carbon fiber production produced in step 1 into a flameproofed fiber in an oxidizing atmosphere of 200 to 300 ° C, and further carbonizing the flameproofed fiber in an inert atmosphere of 300 to 2000 ° C. And a carbonization treatment step.