JP4917991B2 - Oil agent composition for carbon fiber precursor acrylic fiber - Google Patents

Description

  The present invention is a carbon fiber used for the purpose of preventing fusion between single fibers in a flame resistance process in which carbon fiber precursor acrylic fibers (hereinafter also referred to as precursor fibers) are converted to flame resistant fibers in the production process of carbon fibers. The present invention relates to an oil composition for precursor acrylic fibers (hereinafter also referred to as an oil composition). In addition, the present invention relates to a carbon fiber precursor acrylic fiber bundle provided with the oil composition and a method for producing the same.

  Conventionally, as a method for producing a carbon fiber bundle, the acrylic fiber bundle is converted into a flame-resistant fiber bundle by heat treatment in an atmosphere containing 200 to 400 ° C. and subsequently carbonized in an inert atmosphere of 1000 ° C. or more. Thus, a method for obtaining a carbon fiber bundle is known. Carbon fiber bundles obtained by this method are widely used industrially as reinforcing fibers for composite materials because of their excellent mechanical properties.

  However, in the method for producing a carbon fiber bundle, fusion may occur between the single fibers in the flameproofing step of converting the precursor fiber bundle into the flameproofed fiber bundle. Further, in the flameproofing process and the subsequent carbonization process (hereinafter, the flameproofing process and the carbonization process are collectively referred to as a firing process), process failures such as fluff and bundle breakage may occur. In order to avoid this fusion, it is known that selection of the oil agent to be attached to the acrylic fiber bundle is important, and many oil agent compositions have been studied.

  However, silicone-based oils mainly composed of silicone having the effect of preventing fusion between these single fibers are increased in viscosity by a crosslinking reaction that proceeds by heating. Therefore, the adhesive material accumulates on the surface of the precursor fiber bundle manufacturing process and the fiber conveying roller and guide in the flameproofing process, and the fiber bundle is wound or caught and the operability is lowered. It can be a cause. In addition, the oil composition containing silicone produces silicon compounds such as silicon oxide, silicon carbide, and silicon nitride in the firing process, and these scales have the problem of reducing process stability and product quality. ing.

  For this reason, the oil agent composition which reduced the content rate of silicone is proposed for the purpose of reducing the silicon content of a precursor fiber bundle. For example, an oil agent composition containing 50 to 100 wt% of an emulsifier composed of a polycyclic aromatic compound to reduce the silicone content has been proposed (Patent Document 1). However, since the proposed oil agent has many emulsifiers, the stability of the emulsion is increased, but the bundle of precursor fiber bundles to which this oil agent composition is adhered is poor and not suitable for production with high production efficiency. There is a problem that a carbon fiber bundle excellent in mechanical properties cannot be obtained.

  An oil agent composition in which a heat-resisting resin having a residual rate of 80 wt% or more after heating at 250 ° C. in air for 2 hours and silicone is also proposed (Patent Document 2). This is a bisphenol A-based aromatic ester, which has extremely high heat resistance, but is not sufficiently effective in preventing fusion between single fibers, and can stably obtain a carbon fiber bundle excellent in mechanical properties. There was a problem that I could not.

  Furthermore, an oil agent composition containing a compound having a reactive functional group as a main component and not containing silicone has been proposed (Patent Document 3). This is a technique in which the adhesiveness of the oil agent is increased by increasing the viscosity of the oil agent composition at 100 to 145 ° C. However, because the viscosity is high, the fiber bundle is attached to the transport roller in the spinning process of the precursor fiber bundle. There is a problem that causes process trouble such as winding.

  As described above, according to the conventional oil agent composition with a reduced silicone content or an oil agent composition containing only a non-silicone component, an oil agent composition containing silicone as a main component in terms of process stability and mechanical properties of carbon fiber bundles. It tends to be inferior. Therefore, a high quality carbon fiber bundle cannot be obtained stably.

In other words, the problem of reduced operability due to the formation of silicon compounds in the firing process originated from the silicone oil-based oil composition and the problem of the mechanical properties of carbon fiber bundles caused by non-silicone oils are in a two-sided relationship. Yes, the prior art cannot solve both of these problems.
JP 2005-264384 A JP 2000-199183 A JP 2005-264361 A

  The object of the present invention is to improve the reduction in operability that occurs when using an oil composition containing silicone as a main component, and the deterioration in the physical properties of carbon fiber bundles that occurs when a non-silicone oil composition is used. It is in providing an oil agent composition. Furthermore, by attaching the oil agent composition, a carbon fiber precursor acrylic fiber bundle capable of improving process productivity in the firing step and enhancing industrial productivity of the carbon fiber bundle and a method for producing the same are provided. There is to do.

  As a means for solving the above problems, the present invention reduces the silicone content and uses pyromellitic acid ester as the non-silicone component as follows. Thereby, an oil composition for a carbon fiber precursor acrylic fiber that reduces obstacles in the firing process and expresses high mechanical properties of the carbon fiber bundle, and a precursor fiber bundle provided with the oil composition and a method for producing the same Is to provide.

The carbon fiber precursor acrylic fiber oil composition of the present invention has a structure represented by the following formula (1) having a kinematic viscosity of 150 to 8000 mm ² / s (25 ° C.) and an amino equivalent of 2000 to 6000 g / mol. 30 to 50 wt% of modified silicone and 30 to 50 wt% of pyromellitic acid ester having a structure represented by the following formula (2) are contained.

(In the formula (1), in the amino-modified silicone having the structure represented by the formula (1), “o, p” satisfies the above kinematic viscosity and amino equivalent, and “q” is 1 to 5.)
In the formula (1), “o” is preferably 10 to 800, and “p” is preferably 2 to 15.

(In the formula (2), R ^{1 to} R ⁴ are each independently a hydrocarbon group having 8 to 16 carbon atoms.)
The oil agent composition for a carbon fiber precursor acrylic fiber of the present invention has a preferable embodiment when any one or both of the following components are contained.

[Nonionic emulsifier]
As the nonionic emulsifier, it is preferable to contain 10 to 40 wt% of a block copolymer type polyether composed of a propylene oxide (PO) unit and an ethylene oxide (EO) unit having a structure represented by the following formula (3) in the oil composition. . More preferably, R ⁵ and R ^{6 in} the following formula (3) are both hydrogen atoms.

(In the formula (3), R ⁵ and R ⁶ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms; , “Y” and “z” are each independently 1 to 500.)
[Antioxidant]
It is preferable to contain 1 to 5 wt% of an antioxidant in the oil composition.

  Moreover, as for the carbon fiber precursor acrylic fiber bundle of this invention, it is preferable that said oil agent composition adheres 0.1-2.0 wt% with respect to the dry fiber mass of a precursor fiber bundle.

  The method for producing a carbon fiber precursor acrylic fiber bundle according to the present invention comprises an aqueous emulsion solution (hereinafter also referred to as an emulsion) in which the oil agent composition forms micelles having an average particle diameter of 0.01 μm or more and 0.5 μm or less. And a step of imparting to the acrylic fiber bundle. Moreover, it can manufacture suitably by the manufacturing method of the carbon fiber precursor acrylic fiber bundle characterized by having the process of drying and densifying the acrylic fiber bundle to which the aqueous | water-based emulsification solution was provided.

  According to the present invention, it is possible to effectively suppress the fusion between single fibers in the carbon fiber bundle manufacturing process, and the operability is improved because the generation of silicon compounds that become a process hindrance is less than that in the past. . Furthermore, an oil composition for a carbon fiber precursor acrylic fiber capable of obtaining a carbon fiber bundle that exhibits better mechanical properties than conventional products, and a carbon fiber precursor acrylic fiber formed by applying the oil composition. A bundle and its manufacturing method are obtained.

  The present inventors have developed an oil agent composition in which a carbon fiber bundle obtained by firing a precursor fiber bundle having a silicone content reduced and a precursor fiber bundle having the acrylic fiber bundle adhered thereon exhibits excellent mechanical properties. I eagerly searched for things. As a result, it has been found that the use of pyromellitic acid ester can solve both the problems of reducing the silicone content and improving the strength of the carbon fiber bundle. That is, the carbon fiber precursor acrylic fiber oil composition of the present invention makes it possible to simultaneously improve the operability of the carbon fiber production process and the quality of the product.

  In this invention, the acrylic fiber bundle spun by the well-known technique can be used for the acrylic fiber bundle before making an oil agent composition adhere.

  An example of a preferred acrylic fiber bundle is an acrylic fiber bundle obtained by spinning an acrylonitrile polymer.

  The acrylonitrile-based polymer is a polymer obtained by polymerizing acrylonitrile as a main monomer. The acrylonitrile-based polymer is not limited to a homopolymer obtained only from acrylonitrile, but may be an acrylonitrile-based copolymer using other monomers in addition to the main component acrylonitrile.

  The content of the acrylonitrile unit in the acrylonitrile-based copolymer is 96.0 to 98.5 wt% to prevent heat fusion of the fiber in the firing step, heat resistance of the copolymer, stability of the spinning stock solution, and carbon It is more preferable from the viewpoint of quality when made into fibers. When the acrylonitrile unit is 96 wt% or more, it is preferable because excellent quality and performance of the carbon fiber can be maintained without inducing the thermal fusion of the fiber in the firing step when converting to the carbon fiber. In addition, the heat resistance of the copolymer itself is not lowered, and adhesion between single fibers can be avoided in spinning the precursor fiber or in a process such as fiber drying or drawing with a heating roller or pressurized steam. On the other hand, when the acrylonitrile unit is 98.5 wt% or less, the solubility in the solvent does not decrease, the stability of the spinning stock solution can be maintained, and the precipitation and solidification properties of the copolymer are not increased. This is preferable because stable production of fibers is possible.

  The monomer other than acrylonitrile in the case of using the copolymer can be appropriately selected from vinyl monomers copolymerizable with acrylonitrile. Specifically, acrylic acid, methacrylic acid, itaconic acid, or a monomer such as an alkali metal salt or ammonium salt thereof, acrylamide, or the like having an action of promoting the flameproofing reaction is preferable because the flameproofing can be promoted. As the vinyl monomer copolymerizable with acrylonitrile, carboxyl group-containing vinyl monomers such as acrylic acid, methacrylic acid and itaconic acid are more preferable. The content of the carboxyl group-containing vinyl monomer unit in the acrylonitrile copolymer is preferably 0.5 to 2.0 wt%. The other monomer may be one type or two or more types.

  At the time of spinning, the acrylonitrile polymer is dissolved in a solvent to form a spinning dope. As the solvent at this time, an organic solvent such as dimethylacetamide, dimethylsulfoxide, or dimethylformamide, or an inorganic compound aqueous solution such as zinc chloride or sodium thiocyanate can be appropriately selected and used. From the viewpoint of improving productivity, dimethylacetamide, dimethylsulfoxide and dimethylformamide having a high coagulation rate are preferable, and dimethylacetamide is more preferable.

  At this time, in order to obtain a dense coagulated yarn, it is preferable to prepare the spinning dope so that the polymer concentration of the spinning dope becomes a certain level or more. Specifically, the polymer concentration in the spinning dope is preferably 17 wt% or more, more preferably 19 wt% or more. Furthermore, the spinning dope requires proper viscosity and fluidity, and the polymer concentration is preferably within a range not exceeding 25 wt%.

  Spinning methods are known, such as a wet spinning method in which the above-mentioned spinning solution is directly spun into a coagulation bath, a dry spinning method in which the solution is coagulated in the air, and a dry and wet spinning method in which the solution is once coagulated in the air and then coagulated in the bath. A spinning method can be appropriately employed. In order to obtain a carbon fiber bundle having higher performance, a wet spinning method or a dry wet spinning method is preferable.

  The spinning shaping by the wet spinning method or the dry-wet spinning method can be performed by spinning the above spinning solution into a coagulation bath from a nozzle having a circular cross-sectional hole. As the coagulation bath, it is preferable to use an aqueous solution containing a solvent used in the above-mentioned spinning dope from the viewpoint of easy solvent recovery.

  When an aqueous solution containing a solvent is used as the coagulation bath, the solvent concentration in the aqueous solution is such that there is no void and a dense structure can be formed to obtain a high-performance carbon fiber bundle, and stretchability can be ensured and productivity is excellent. From 50 to 85 wt%, the temperature of the coagulation bath is preferably 10 to 60 ° C.

  After the polymer or copolymer is dissolved in a solvent and discharged into a coagulation bath as a spinning solution to be fiberized, stretching in a bath in which the coagulated yarn is stretched in a coagulation bath or in a stretching bath can be performed. Alternatively, it may be partially stretched in the air and then stretched in a bath, and the fiber in a water-swollen state can be obtained by washing with water before or after stretching or simultaneously with stretching. Stretching in the bath is usually carried out in a water bath at 50 to 98 ° C. by dividing it into multiple stages of once or twice, and the total ratio of stretching in the air and stretching in the bath can be stretched to 2 to 10 times. It is preferable from the viewpoint of the performance of the carbon fiber bundle.

  Application of the oil composition to the acrylic fiber bundle can be performed by applying an emulsion of the oil composition to the acrylic fiber bundle in the water-swollen state after stretching in the bath. When washing is performed after stretching in the bath, an emulsion of the oil composition can also be applied to the fiber bundle in a water-swelled state obtained after stretching and washing in the bath.

The oil composition has a kinematic viscosity of 150 to 8000 mm ² / s (25 ° C.) and an amino-modified silicone having a structure represented by the following formula (1) having an amino equivalent of 2000 to 6000 g / mol: 30 to 50 wt% of pyromellitic acid ester having a structure represented by the formula (2) is contained.

  (In the formula (1), “o” is 10 to 800, “p” is 2 to 15, and “q” is 1 to 5.)

(In Formula (2), R ^{1 to} R ⁴ are each independently a hydrocarbon group having 8 to 16 carbon atoms.)
In the present invention, the oil composition is composed of 30 to 50 wt% of an amino-modified silicone having a structure represented by the above formula (1) having a kinematic viscosity of 150 to 8000 mm ² / s (25 ° C.) and an amino equivalent of 2000 to 6000 g / mol. It is preferable to contain. Moreover, it is more preferable to contain 40-50 wt%. When the content of amino-modified silicone is less than 30 wt%, fusion between single fibers in the firing process cannot be completely prevented. Moreover, when there is more content of amino modified silicone than 50 wt%, a silicon compound will produce | generate and disperse in a baking process, and there exists a possibility of causing the fall of operativity and the quality of the manufactured carbon fiber.

  The kinematic viscosity can be measured using a Ubbelohde viscometer based on “Liquid viscosity—measuring method” (ASTM D 445-46T is acceptable) defined in JIS-Z-8803.

In the present invention, the amino-modified silicone represented by the above formula (1) contained in the oil composition is effective in improving the affinity of the oil composition for the carbon fiber precursor acrylic fiber bundle and the heat resistance. The kinematic viscosity of the amino-modified silicone is preferably 150 to 8000 mm ² / s (25 ° C.), more preferably 1000 to 5000 mm ² / s (25 ° C.). When the kinematic viscosity is less than 150 mm ² / s (25 ° C.), it becomes easy to separate from the ester component, the adhesion state of the oil composition on the surface of the precursor fiber bundle becomes non-uniform, and the fusion between single fibers in the flameproofing process Can not be prevented. Moreover, when it exceeds 8000 mm < ² > / s (25 degreeC), preparation of an emulsion will become difficult, stability of an emulsion will also worsen, and it will become difficult to make an oil agent composition adhere uniformly to an acrylic fiber bundle.

  The amino equivalent of the amino-modified silicone is preferably 2000 to 6000 g / mol, more preferably 4000 to 6000 g / mol, from the viewpoint of good compatibility with the precursor fiber bundle and the thermal stability of the silicone. When the amino equivalent is less than 2000 g / mol, the number of amino groups in one silicone molecule is large, the thermal stability is lowered, and the process is hindered. On the other hand, if it is larger than 6000 g / mol, the number of amino groups is small, so that the compatibility with the acrylic fiber bundle is poor, and it becomes difficult to uniformly adhere the oil composition to the acrylic fiber bundle.

In view of the structure, preferred forms of amino-modified silicone are described below. “O, p, q” in the formula (1) may be used as long as the above viscosity and amino equivalent are satisfied. Preferably, the amino-modified part of the formula (1) is an aminopropyl group (—C ₃ H ₆ NH ₂ ), that is, “q” = 3 in the amino-modified part of the formula (1), and “o” is 10 to 10 800, “p” is 2-15. If “o, p” in the formula (1) is out of the above-mentioned range, it is not preferable because the performance development property and heat resistance of the carbon fiber bundle are deteriorated. If “o” is less than 10, the heat resistance is low and fusion between single fibers cannot be prevented. On the other hand, when “o” is larger than 800, it is very difficult to disperse in water, and it is impossible to uniformly adhere to the surface of the acrylic fiber bundle. When “p” is smaller than 2, the affinity with the acrylic fiber bundle is lowered, so that fusion between single fibers cannot be effectively prevented. On the other hand, if “p” is greater than 15, the heat resistance of the oil agent itself is lowered, so that fusion between single fibers cannot be prevented. More preferably, “o” is 300 to 800, and “p” is 5 to 15. The amino-modified silicone represented by the formula (1) may be a mixture of a plurality of compounds, and therefore “o”, “p”, and “q” may not be integers.

In these formulas (1), “o, p” is an estimated value from viscosity and amino equivalent, and “q” is a value determined by the synthetic raw material. The procedure for obtaining “o, p” is as follows. J. et al. The molecular weight is calculated according to the Barry equation (log η = 1.00 + 0.0123 M ^0.5 , η: viscosity at 25 ° C., M: molecular weight). Next, the average number of amino groups “p” per molecule is determined from this molecular weight and amino equivalent. The value of “o” can be determined by determining the molecular weight “p, q”.

  In the present invention, the oil composition preferably contains 30 to 50 wt%, more preferably 30 to 40 wt% of the pyromellitic acid ester represented by the above formula (2). Since pyromellitic acid ester is highly compatible with amino-modified silicone, it is preferable for uniformly attaching an oil agent composition to an acrylic fiber bundle, and a precursor fiber bundle for obtaining a carbon fiber bundle having good mechanical properties. It is effective for manufacturing. If the pyromellitic acid ester content is less than 30 wt%, the balance with the amino-modified silicone is lost and uniform adhesion to the acrylic fiber bundle becomes impossible, and the carbon fiber obtained by firing the precursor fiber bundle to which they are attached The bundle does not exhibit stable physical properties. Further, when the content of pyromellitic acid ester is more than 50 wt%, the content of amino-modified silicone is inevitably reduced, the convergence in the spinning process is deteriorated, and the precursor fiber bundle to which they are attached is used. Carbon fiber bundles obtained by firing are inferior in mechanical properties.

The structure forming R ¹ part to R ⁴ part of the above formula (2) is preferably a C _{8 to} C ₁₆ saturated hydrocarbon group, and more preferably C _{8 to} C _{14, which} makes it easy to obtain a uniform emulsion. Of saturated hydrocarbon groups. Alternatively, it is a C _{12 to} C ₁₆ saturated hydrocarbon group having high thermal stability in the presence of water vapor. Specific examples include octyl group, nonyl group, decyl group, undecyl group, lauryl group (dodecyl group), tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group and the like. When the carbon number is less than C ₈ , the thermal stability is deteriorated, and a sufficient anti-fusing effect cannot be obtained in the flameproofing process. The viscosity is increased becomes larger than C _16, it is difficult to obtain a homogeneous emulsion, it is impossible to uniformly adhere the oil agent composition to the acrylic fiber bundle. Note that R ^{1 to} R ⁴ may have the same structure, but may have independent structures.

  In the present invention, the oil agent composition preferably further contains 10 to 40 wt%, preferably 10 to 30 wt%, of a block copolymer type polyether composed of propylene oxide (PO) units and ethylene oxide (EO) units. It is more preferable. The block copolymer polyether preferably has a structure represented by the following formula (3).

(In the formula (3), R ⁵ and R ⁶ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms; “Y” and “z” are each independently 1 to 500.)
R ⁵ and R ⁶ are determined in consideration of the equilibrium with PO and EO and other oil agent compositions, but in this oil agent composition, a hydrogen atom or a straight or branched chain having 1 to 5 carbon atoms. A chain alkyl group is preferred, and a hydrogen atom is more preferred. The values of “x”, “y”, and “z” are preferably 20 to 300 each independently. More preferably, the ratio of “x + z” to “y” is 80-60: 20-40.

The block copolymer polyether preferably has a molecular weight of 3000 to 20000 and a kinematic viscosity at 100 ° C. of 300 to 15000 mm ² / s.

  In the present invention, the oil agent composition may further contain an antioxidant in the range of 1 to 5 wt% as necessary. This content is more preferably in the range of 1 to 3 wt%.

  Various known substances can be used as the antioxidant, but phenol-based and sulfur-based antioxidants are preferable. Specifically, 2,6-di-t-butyl-p-cresol, 4,4′-butylidenebis- (6-t-butyl-3-methylphenol), 2,2 ′ is used as a phenolic antioxidant. -Methylenebis- (4-methyl-6-tert-butylphenol), 2,2'-methylenebis- (4-ethyl-6-tert-butylphenol), 2,6-di-tert-butyl-4-ethylphenol, , 1,3-Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, n-octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tetrakis [ Methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5- Butylphenyl) propionate], tris (3,5-di -t- butyl-4-hydroxybenzyl) isocyanurate. Examples of sulfur-based antioxidants include dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate, and ditridecyl thiodipropionate. The above antioxidants may be used alone or as a mixture.

  Moreover, what melt | dissolves in a pyromellitic acid ester as an antioxidant is used more preferable. This is because the oil component that the antioxidant wants to act on is pyromellitic acid ester, and as a method of uniformly mixing the antioxidant in the oil, it is preliminarily dissolved in pyromellitic acid ester. The main reason is convenient.

  In the present invention, the above-mentioned amino-modified silicone, pyromellitic acid ester, and block copolymer polyether composed of PO and EO as necessary, an oil composition containing the antioxidant in the above-mentioned ratio is in a water-swollen state. It is made to adhere to the acrylic fiber bundle. Usually, the process which provides the aqueous | water-based emulsion solution in which the said oil agent composition was disperse | distributed in water to the acrylic fiber bundle of a water swelling state is performed.

  Preparation of the emulsion is, for example, mixing an amino-modified silicone with a block copolymer polyether and stirring, adding water to a mixture obtained by adding pyromellitic acid ester and stirring to obtain an emulsion in which the oil composition is dispersed in water. It is done. When an antioxidant and an antistatic agent are contained, it is preferable to dissolve them in pyromellitic acid ester in advance. Mixing of each component or dispersion in water can be performed using propeller stirring, a homomixer, a homogenizer, or the like. In particular, when a high viscosity amino-modified silicone is used, it is preferable to use an ultra-high pressure homogenizer that can pressurize to 150 MPa or more.

  In the present invention, the oil composition may contain an antistatic agent as necessary in order to improve its properties. A known substance can be used as the antistatic agent. Antistatic agents are roughly classified into ionic types and nonionic types, and ionic types include anionic, cationic and amphoteric, and nonionic types include polyethylene glycol type and polyhydric alcohol type. From the viewpoint of antistatic, ionic type is preferable, among them aliphatic sulfonate, higher alcohol sulfate ester salt, higher alcohol ethylene oxide adduct sulfate ester, higher alcohol phosphate ester salt, higher alcohol ethylene oxide adduct sulfate phosphate ester salt, Quaternary ammonium salt type cationic surfactants, betaine type amphoteric surfactants, higher alcohol ethylene oxide adducts polyethylene glycol fatty acid esters, polyhydric alcohol fatty acid esters and the like are preferably used, and these may be used alone or in combination.

  Furthermore, in order to improve the stability of the process, the stability of the oil composition, and the adhesion characteristics depending on the equipment and usage environment for attaching the oil composition to the acrylic fiber bundle, an antifoaming agent, preservative, antibacterial agent, penetrating agent Such additives may be appropriately blended in the oil composition of the present invention.

  As a method for applying the oil agent composition of the present invention to a precursor fiber bundle in a water-swelled state, an oil agent treatment liquid is prepared by adding ion-exchanged water to an emulsion in which the oil agent composition is dispersed in water and diluting to a predetermined concentration. Then, a method of adhering to the precursor fiber bundle in the water swelling state is used.

  As a method of attaching the oil treatment liquid to the precursor fibers in the water-swollen state, the roller lowering method in which the lower part of the roller is immersed in the oil application liquid and the precursor fiber bundle is brought into contact with the upper part of the roller, a certain amount of the pump In the guide adhesion method of discharging the oil agent application liquid from the guide and bringing the precursor fiber bundle into contact with the guide surface, the spray adhesion method in which a predetermined amount of oil agent application liquid is sprayed onto the precursor fiber bundle from the nozzle, and the oil agent application liquid A known method such as a dip attachment method in which the precursor fiber is dipped and then squeezed with a roller or the like to remove an excess oil agent application liquid can be used.

  From the viewpoint of uniform adhesion, a dip adhesion method in which the oil agent treatment liquid is sufficiently infiltrated into the fiber bundle and excess treatment liquid is removed is preferable. In order to adhere more uniformly, it is also effective to apply the oil agent application step in two or more stages and repeatedly apply it.

  In the present invention, the amount of the oil composition attached to the acrylic fiber bundle is preferably 0.1 to 2.0 wt% with respect to the dry fiber mass of the acrylic fiber bundle after being dried and densified as described later. More preferably, it is 0.5 to 1.5 wt%. When the adhesion amount of the oil agent composition is lower than 0.1 wt%, it may be difficult to sufficiently develop the original function of the oil agent. On the other hand, when the adhesion amount of the oil composition is higher than 2.0 wt%, the excessively adhered oil composition may be polymerized in the firing step to cause adhesion between single fibers.

  In particular, when producing a precursor fiber bundle in which the oil agent composition adheres in an amount of 0.1 to 2.0 wt% with respect to the dry fiber mass of the carbon fiber precursor acrylic fiber bundle, the average particle size of the oil agent composition finely dispersed is 0.00. It is preferable to prepare an aqueous emulsified solution in which micelles of 01 μm or more and 0.5 μm or less are formed. By carrying out like this, it becomes possible to provide an oil agent uniformly to the surface of an acrylic fiber bundle. The average particle size of micelles present in the aqueous emulsion can be measured based on the Mie scattering theory using a laser diffraction / scattering particle size distribution measuring device (LA-910, manufactured by Horiba, Ltd.). it can.

  In the present invention, the precursor fiber bundle to which the oil composition is attached is dried and densified in a subsequent drying step. The temperature for drying and densification needs to be performed at a temperature exceeding the glass transition temperature of the fiber, but the water-containing state and the dry state may differ substantially, and a method using a heating roller at 100 to 200 ° C. is preferable. At this time, the number of heating rollers may be one or more.

  It is preferable to perform pressurized steam stretching after drying, whereby the denseness and orientation degree of the resulting fiber can be further increased. Pressurized steam stretching is a method of stretching in a pressurized steam atmosphere. Since high-strength stretching is possible, high-speed and stable spinning can be performed, and at the same time, the density and orientation of the resulting fiber can be increased. Contributes to improvement.

  In the present invention, in this pressurized steam stretching, it is important to control the temperature of the heating roller immediately before the pressurized steam stretching apparatus to 120 to 190 ° C. and the variation rate of the steam pressure in the pressurized steam stretching to 0.5% or less. By doing in this way, the fluctuation | variation of the draw ratio made into a fiber bundle and the fluctuation | variation of the tow | fineness degree to be generated by it can be suppressed. When the temperature of the heating roller is less than 120 ° C., the temperature of the precursor fiber bundle is not sufficiently increased and the drawability is lowered.

  The pressure of water vapor in the pressurized steam stretching is preferably 200 kPa · g (gauge pressure, the same shall apply hereinafter) or more so that the stretching by the heating roller and the characteristics of the pressurized steam stretching method appear clearly. The water vapor pressure is preferably adjusted as appropriate in consideration of the treatment time. However, if the pressure is high, leakage of water vapor may increase, so that it is preferably 600 kPa · g or less industrially.

  The fiber bundle that has been dried and densified is passed through a roll at room temperature, cooled to room temperature, and wound around a bobbin with a winder. Alternatively, it is transferred to the can and stored, and then transferred to the firing step.

  The carbon fiber precursor acrylic fiber bundle of the present invention produced as described above can suppress the fusion in the spinning process and firing process, and can produce a carbon fiber bundle excellent in quality and physical properties. Moreover, since the amount of silicon decomposition products in the baking process and the amount of silicon compound produced are small, the operability and process passability are remarkably improved. A carbon fiber bundle obtained by such a carbon fiber precursor acrylic fiber bundle is suitable as a reinforcing fiber used for a fiber reinforced resin composite material used for various structural materials.

  EXAMPLES The present invention will be described in more detail with reference to the following examples. However, the carbon fiber precursor acrylic fiber oil agent composition of the present invention, the precursor fiber bundle provided with the oil agent composition, and the production method thereof are limited by these. Is not to be done. In addition, the amount of adhesion of oil agent to the precursor fiber bundle, evaluation of convergence, and the number of fusions between single fibers of the carbon fiber bundle obtained by firing the precursor fiber bundle, the strand strength, and the silicon-derived silicon compound scattering in the firing process Evaluation was carried out by the following method.

[Oil agent adhesion amount]
The precursor fiber bundle was dried at 105 ° C. for 1 hour, and then immersed in methyl ethyl ketone at 90 ° C. for 8 hours, and the oil agent composition adhered thereto was subjected to solvent extraction. The oil agent adhesion amount was determined from this difference by precisely weighing the mass of the carbon fiber precursor acrylic fiber bundle before and after this extraction.

[Evaluation of convergence]
The bundling property was evaluated according to the following criteria by observing the state of the precursor fiber bundle on the final roll in the spinning process of the precursor fiber bundle, that is, the roll immediately before winding the precursor fiber bundle on the bobbin.
○: Converged, constant tow width, and not in contact with adjacent fiber bundle.
Δ: Converged, but tow width is not constant or tow width is wide.
X: There is a space in the fiber bundle and it is not focused.

[Number of fusions between single fibers (number of fusions)]
The carbonized carbon fiber bundle is cut into 3 mm lengths, dispersed in acetone, and after stirring for 10 minutes, the total number of single fibers and the number of fusions are counted, and the number of fusions per 100 single fibers is calculated. evaluated. The evaluation criteria are as follows.
○: Number of fusions (pieces / 100 pieces) ≦ 1
×: Number of fusions (pieces / 100 pieces)> 1
[Carbon fiber bundle strand strength (CF strength)]
It measured according to the epoxy resin impregnation strand method prescribed | regulated to JIS-R-7601. The number of measurements was 10 times, and the average value was used as an evaluation target.

[Silicon-derived silicon compound scattering evaluation]
The amount of silicon-derived silicon compound scattered in the flameproofing process is determined by measuring the Si element content of the carbon fiber precursor acrylic fiber bundle and the flameproofed fiber bundle made flameproof with a fluorescent X-ray analyzer. Thus, the amount of Si scattered in the flameproofing process was calculated and used as an evaluation index.

(Si scattering amount) = Si content of precursor fiber bundle−Si content of flameproof fiber bundle [mg / kg]
For the X-ray fluorescence analyzer, ZSX100e manufactured by Rigaku Corporation was used. The measurement sample was set on the apparatus by uniformly winding a fiber bundle on an acrylic resin plate having a length of 20 mm, a width of 40 mm, and a width of 5 mm without any gaps. At this time, it is important that the winding length of the fiber bundle attached to the measurement is the same. Thereafter, the fluorescent X-ray intensity of Si was measured by a normal fluorescent X-ray analysis method. From the X-ray fluorescence X-ray intensity of Si of the obtained precursor fiber bundle and flameproof fiber bundle, a calibration curve was used to determine the Si content of each fiber bundle. The number of measurements was n = 10, and the average value was used for evaluation.

[Example 1]
An emulsion of the oil composition was prepared by the following method.
Amino-modified silico having a structure of the formula (1) having a kinematic viscosity of 150 mm ² / s (25 ° C.) and an amino equivalent of 2000 g / mol obtained by an alkali equilibrium method which is a general method for synthesizing amino-modified silicones (O = 120, p = 5, q = 3)
A pyromellitic acid ester in which R ^{1 to} R ⁴ are both octyl groups in formula (2) R ⁵ and R ⁶ are hydrogen atoms in formula (3), molecular weight is 8000, and kinematic viscosity is 400 mm ² / s ( 100 ° C) PO and EO block copolymer polyether (manufactured by Sanyo Chemical Industries, Ltd., trade name: New Pole PE-68)
Antioxidant {Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Methane and ditridecylthiodipropionate (1: 2 (mass ratio))}
When the compound is mixed at a mass ratio of 43: 35: 21: 1 (amino-modified silicone: pyromellitic ester: block copolymer polyether: antioxidant), the concentration of the oil composition becomes 30 wt%. As such, ion exchange water was added and emulsified with a homomixer. In this state, since the average micelle particle diameter is about 2 μm, it was further dispersed to a particle diameter of 0.2 μm or less by a high-pressure homogenizer. This emulsion was used as an oil agent stock solution in the following steps.

  The acrylic fiber bundle to which the oil agent composition was adhered was prepared by the following method. Acrylonitrile copolymer (composition ratio: acrylonitrile / acrylamide / methacrylic acid = 96/3/1 (mass ratio)) was dissolved in dimethylacetamide to prepare a spinning dope. Thereafter, the solidified yarn was discharged into a coagulation bath filled with an aqueous dimethylacetamide solution from a spinning nozzle having a pore diameter (diameter) of 75 μm and a number of holes of 6000. The coagulated yarn was desolvated in a water washing tank and stretched 5 times to obtain an acrylic fiber bundle in a water swollen state.

  The acrylic fiber bundle in the water-swelled state is guided to an oil agent treatment tank containing a treatment liquid obtained by diluting the oil agent stock solution with ion-exchanged water. After the oil agent composition is adhered, the acrylic fiber bundle is placed on a roll having a surface temperature of 180 ° C. After drying, the film was stretched 3 times in water vapor at a pressure of 0.2 MPa. Table 1 shows the evaluation results of the convergence properties of the precursor fiber bundles obtained here. The tow width was slightly different but concentrated, and the spinning process was stable.

  This carbon fiber precursor acrylic fiber bundle is passed through a flameproofing furnace having a temperature gradient of 220 to 260 ° C., and further baked in a carbonization furnace having a temperature gradient of 400 to 1300 ° C. in a nitrogen atmosphere. did.

  Table 1 shows the number of fused carbon fiber bundles obtained, the carbon fiber bundle strand strength (hereinafter also referred to as CF strength), and the silicone-derived silicon compound scattering evaluation results in the flameproofing step. The evaluation results of the number of fusion and silicon compound scattering were both good, and the CF strength was also high.

[Examples 2 to 11]
Examples 2 to 11 were carried out in the same manner as in Example 1, except that the type and content of each component constituting the oil composition were changed. In addition, the same substance as Example 1 was used for block copolymerization type polyether and antioxidant. The ratio (mass percentage) of each component in the oil composition in each Example is shown in Table 1.

The physical properties of amino-modified silicones (1) to (3) in Table 1 are described below.
(1) Kinematic viscosity at 25 ° C. is 150 mm ² / s, amino equivalent is 2000 g / mol (o = 120, p = 5, q = 3).
(2) Kinematic viscosity at 25 ° C. is 4000 mm ² / s, amino equivalent is 6000 g / mol (o = 600, p = 7, q = 3).
(3) Kinematic viscosity at 25 ° C. is 8000 mm ² / s, amino equivalent is 4000 g / mol (o = 750, p = 14, q = 3).

The structures of pyromellitic acid esters (i) to (v) in Table 1 are shown below.
(I) A pyromellitic acid ester in which R ^{1 to} R ⁴ are all C ₈ octyl groups in the formula (2).
(Ii) A pyromellitic ester in which R ^{1 to} R ⁴ are all C ₁₀ decyl groups in the formula (2).
(Iii) A pyromellitic ester in which R ^{1 to} R ⁴ are all C ₁₂ dodecyl groups in the formula (2).
(Iv) A pyromellitic ester in which R ^{1 to} R ⁴ are all C ₁₄ tetradecyl groups in the formula (2).
(V) A pyromellitic acid ester in which R ^{1 to} R ⁴ are all C ₁₆ hexadecyl groups in the formula (2).

The evaluation results of Examples 2 to 11 are shown in Table 1. In all cases, the evaluation of convergence, evaluation of the number of fusions, and evaluation of scattering of silicon compounds were good. Example 1 using a relatively low kinematic viscosity amino-modified silicone, Example 6 and Example using a pyromellitic acid ester in which R ^{1 to} R ⁴ are both tetradecyl and hexadecyl groups in formula (2) In No. 7, the focusing property tended to be slightly inferior to the other examples. However, this was not a problem in the manufacturing process.

In the evaluation results of the strand strength, all were good, but there are differences due to differences in components and ratios of the oil composition. The amino-modified silicone having the best strength development has a kinematic viscosity of 4000 mm ² / s (25 ° C.) and an amino equivalent of 6000 g / mol. Further, pyromellitic acid esters having good strength development were pyromellitic acid ester in which R ^{1 to} R ⁴ are both decyl groups having 10 carbon atoms and pyromellitic acid ester having dodecyl groups having 12 carbon atoms. .

[Comparative Example 1]
An amino-modified silicone having a structure of the formula (1) having a kinematic viscosity of 80 mm ² / s (25 ° C.) and an amino equivalent of 4000 g / mol, prepared in the same manner as in Example 1 (o = 70, p = 1, q = 3)
・ Pyromellitic acid ester in which R ^{1 to} R ⁴ are both decyl groups having 10 carbon atoms in formula (2) ・ R ⁵ and R ⁶ are hydrogen atoms in formula (3), molecular weight is 8000, kinematic viscosity is 400 mm ² / s (100 ° C.) PO and EO block copolymer polyether (manufactured by Sanyo Chemical Industries, trade name: New Pole PE-68)
Antioxidant {Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Methane and ditridecylthiodipropionate (1: 2 (mass ratio)) }
The same method as in Example 1 using an oil composition in which the compound was mixed in a mass ratio of 43: 35: 21: 1 (amino-modified silicone: pyromellitic ester: block copolymerized polyether: antioxidant) A precursor fiber bundle was manufactured and fired to obtain a carbon fiber bundle. The results of each evaluation are shown in Table 2.

  Although the evaluation result of silicon compound scattering was good, it was judged that it was difficult to industrially produce continuously because the convergence was extremely poor and the number of fusions was large. Furthermore, the strand strength was low compared with any of Examples 1-11.

[Comparative Examples 2 to 13]
Comparative Examples 2 to 13 were carried out in the same manner as in Example 1, except that the type and content of each component constituting the oil composition were changed. In Comparative Examples 8 and 9, pentaerythritol tetraisostearate and hexyl benzoate were used as the ester component instead of pyromellitic acid ester. Further, the same materials as in Comparative Example 1 were used as the block copolymer type polyether and the antioxidant. The ratio (mass percentage) of each component in the oil agent composition in each comparative example is shown in Table 2.

The physical properties of amino-modified silicones (4) to (7) in Table 2 are shown below.
(4) Kinematic viscosity at 25 ° C. is 80 mm ² / s, amino equivalent is 4000 g / mol (o = 70, p = 1, q = 3).
(5) Kinematic viscosity at 25 ° C. is 500 mm ² / s, amino equivalent is 1000 g / mol (o = 250, p = 19, q = 3).
(6) Kinematic viscosity at 25 ° C. is 12000 mm ² / s, amino equivalent is 10,000 g / mol (o = 840, p = 6, q = 3).
(7) Kinematic viscosity at 25 ° C. is 20000 mm ² / s, amino equivalent is 6000 g / mol (o = 970, p = 12, q = 3).

The pyromellitic acid ester (vi) to (vii) structures in Table 2 are shown below.
(Vi) A pyromellitic acid ester in which R ^{1 to} R ⁴ are all C ₁₈ stearyl groups (octadecyl groups) in the formula (2).
(Vii) A pyromellitic acid ester in which R ^{1 to} R ⁴ are both C ₂₀ eicosyl groups in the formula (2).

The evaluation results of Comparative Examples 2 to 13 are shown in Table 2. In all cases, the CF strength was low. When (4) having a kinematic viscosity of amino-modified silicone lower than 150 mm ² / s (25 ° C.) was used, the focusing property was poor and the number of fusions was large. When (6) or (7) is used, in which the kinematic viscosity of the amino-modified silicone is higher than 8000 mm ² / s (25 ° C.), the viscosity of the silicone deposited on the roll in the drying process of the precursor fiber bundle is reduced. As a result, there was a process hindrance in which the yarn was wound around the roll. In addition, when (5) having an amino equivalent of amino-modified silicone lower than 2000 g / mol is used, the thermal stability of the amino-modified silicone is remarkably poor, and due to this, gelation proceeds in the process, resulting in a process hindrance. Furthermore, the number of fusions increased due to the influence of gelation. In addition, the amino-modified silicone (6) has an amino equivalent higher than 6000 g / mol. In this case, it was difficult to emulsify, and it was not well-suited with the precursor fiber bundle, so that stable uniform adhesion was difficult, and the number of fusions was large. It was.

Also, the ester component, in the case of using stearyl exceeding C ₁₆ as R ¹ to R ⁴ of formula (2), a pyromellitic acid ester eicosyl, focusing was poor. Moreover, when other than pyromellitic acid esters such as pentaerythritol tetraisostearate and hexyl benzoate were used, the number of fusions was large.

  On the other hand, when the content of amino-modified silicone is as low as 20 wt%, the number of fusions is large, and as the content of amino-modified silicone increases as 60, 75, or 90 wt%, the amount of silica compound scattering increases and the process hindrance It became. In particular, in the case of an oil agent composition having an amino-modified silicone content of 90 wt%, about 2 to 3 times as many silica compounds were scattered as compared with any of the examples, and the operability was lowered.

  Occurs when using an oil agent prepared from the oil agent composition for a carbon fiber precursor acrylic fiber of the present invention, effectively suppressing adhesion between single fibers in the firing step, and using an oil agent using silicone as the main agent. The decline in operability can be suppressed. Furthermore, a carbon fiber bundle with high mechanical strength can be obtained. That is, it is possible to obtain a carbon fiber precursor acrylic fiber bundle that can improve both the performance enhancement and the operational stability of the carbon fiber.

  The carbon fiber bundle obtained from the carbon fiber precursor acrylic fiber bundle can be formed into a composite material after prepreg. The composite material using the carbon fiber bundle obtained in the present invention can be suitably used for sports applications such as golf shafts and fishing rods, as well as automobiles, aerospace applications, and various gas storage tank applications as a structural material. Is useful.

Claims (7)

30 to 50 wt% of an amino-modified silicone having a structure represented by the following formula (1) having a kinematic viscosity of 150 to 8000 mm ² / s (25 ° C.) and an amino equivalent of 2000 to 6000 g / mol, represented by the following formula (2) 30 to 50 wt% of pyromellitic acid ester having a structure as described above, an oil composition for acrylic fibers for carbon fiber precursors.

(In the formula (1), in the amino-modified silicone having the structure represented by the formula (1), “o, p” satisfies the above kinematic viscosity and amino equivalent, and “q” is 1 to 5.)

(In Formula (2), R ^{1 to} R ⁴ are each independently a hydrocarbon group having 8 to 16 carbon atoms.)   2. The oil composition for carbon fiber precursor acrylic fibers according to claim 1, wherein "o" in formula (1) is 10 to 800 and "p" is 2 to 15. The oil agent composition further contains 10 to 40 wt% of a block copolymer type polyether composed of a propylene oxide (PO) unit and an ethylene oxide (EO) unit having a structure represented by the following formula (3). The oil agent composition for acrylic fiber for carbon fiber precursor according to claim 1 or 2.

(In the formula (3), R ⁵ and R ⁶ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms; , “Y” and “z” are each independently 1 to 500.) The oil agent composition for carbon fiber precursor acrylic fiber according to any one of claims 1 to 3, wherein R ⁵ and R ⁶ in the formula (3) are both hydrogen atoms.   The said oil agent composition contains 1-5 wt% of antioxidant further, The oil agent composition for carbon fiber precursor acrylic fiber in any one of Claims 1-4 characterized by the above-mentioned.   The carbon fiber precursor according to any one of claims 1 to 5, wherein 0.1 to 2.0 wt% of the oil agent composition for acrylic fibers is attached to the dry fiber mass. Acrylic fiber bundle.   The method for producing a carbon fiber precursor acrylic fiber bundle according to claim 6, wherein the oil agent composition is finely dispersed in water to form micelles having an average particle diameter of 0.01 µm to 0.5 µm. A carbon fiber precursor acrylic fiber bundle comprising a step of applying an emulsified solution to an acrylic fiber bundle in a water-swelled state and a step of drying and densifying the acrylic fiber bundle to which an aqueous emulsion solution is applied. Production method.