WO2001086040A1

WO2001086040A1 - Acrylonitrile-based fiber bundle for carbon fiber precursor and method for preparation thereof

Info

Publication number: WO2001086040A1
Application number: PCT/JP2000/002951
Authority: WO
Inventors: Yukio Kasabo; Katsuhiko Ikeda
Original assignee: Mitsubishi Rayon Co., Ltd.
Priority date: 1998-11-09
Filing date: 2000-05-09
Publication date: 2001-11-15
Also published as: JP2000144521A; JP3808643B2

Abstract

An acrylonitrile-based fiber bundle for carbon fiber precursor comprising an acrylonitrile-based polymer containing acrylonitrile units in an amount of 95 wt % or more of the monomer units thereof and having a total denier of 30,000 or more, characterized in that the single fiber constituting the fiber bundle has 2 to 15 wrinkles on its surface which have a height of 0.5 to 1.0 νm and substantially continue in the longitudinal direction of the fiber bundle, and the fiber bundle has an iodine absorption number of 0.5 to 1.5 wt % based on the weight of fiber. This fiber bundle is suitable for use as a precursor of a carbon fiber thread, since it has a great total fineness, is excellent in compactness and is reduced in drying load, and also is excellent in collectability.

Description

Specification

Acrylonitrile fiber bundle for carbon fiber precursor and method for producing the same

The present invention relates to an acrylonitrile-based fiber bundle suitable for producing carbon fiber yarns used for premium applications such as aircraft and sports, and general industrial applications.

Background art

The demand for carbon fiber yarns has been increasing for several years, and has been expanding into premium applications such as aircraft and sports, and general industrial applications such as civil engineering and construction. At present, an acrylonitrile fiber bundle having a filament count of 10,000 to 200,000 is wound by a filament winding method, a carbon fiber yarn is manufactured through a firing step, and a single carbon fiber is produced. After several yarns are aligned, they are formed.

However, in the above-mentioned method, since several carbon fiber yarns are aligned after obtaining the carbon fiber yarns through the firing step, a gap is easily generated between the aligned carbon fiber yarns, and the carbon fibers are easily removed. Defects occur during molding that lead to a decrease in the strength and elastic modulus of the molded body used. In addition, the process of aligning a plurality of carbon fiber yarns is a factor in the complexity and cost of manufacturing molded products.

In order to solve these problems, in recent years, attempts have been made to increase the number of filaments of an acrylonitrile fiber bundle, which is a precursor of carbon fiber yarn. However, unnecessarily increasing the number of filaments of the acrylonitrile-based fiber bundle leads to an increase in tow handlink and tow volume, and the spinning speed cannot be increased because the drying load increases in the existing equipment. In addition, there is a problem that merging between fiber bundles occurs due to an increase in the volume, so that the quality of the product is significantly reduced.

For this reason, acrylonitrile-based fiber bundles suitable for use as precursors of carbon fiber yarns are those having high total fineness, excellent denseness, low drying load, and excellent convergence. is necessary.

Accordingly, an object of the present invention is to provide a high total fineness, excellent denseness, and a high drying load. An object of the present invention is to provide an acrylonitrile-based fiber bundle suitable for use as a precursor of a carbon fiber yarn because of its small size and excellent bunching properties.

Further, an object of the present invention is to provide an acritic nitrile-based fiber bundle suitable for use as a precursor of a carbon fiber yarn because it is excellent in denseness, small in drying load, and excellent in convergence. Another object of the present invention is to provide a method for producing an acrylonitrile-based fiber bundle which can be obtained easily and accurately. Disclosure of the invention

The above problems are solved by the acrylonitrile-based fiber bundle of the present invention described below and a method for producing the same.

That is, the present invention relates to a fiber bundle having a total denier of 300,000 or more made of an acrylonitrile-based polymer containing 95% by weight or more of an acrylonitrile unit, and having a surface of a single fiber constituting the fiber bundle. The fiber bundle has a length substantially continuous in the longitudinal direction of the fiber bundle. 0.5 to: 1.0 m 2 to 5 wrinkles, and iodine adsorption per fiber weight of the fiber bundle 0.5 to 0.5% by weight of acrylonitrile fiber bundle for carbon fiber precursor.

In addition, the method for producing an acrylonitrile-based fiber bundle for a carbon fiber precursor of the present invention is a method comprising: spinning a acrylonitrile-based polymer containing 95% by weight or more of an acrylonitrile unit in a first organic solvent. The undiluted solution contains a second organic solvent capable of dissolving the atarilonitrile polymer at a concentration of 50 to 70% by weight, and is contained in a first coagulation bath comprising an aqueous solution of an organic solvent at a temperature of 30 to 50 ° C The coagulated yarn is taken out from the first coagulation bath at a take-up speed of 0.8 times or less the discharge linear speed of the stock spinning solution, and then the coagulated yarn is dissolved in the acrylonitrile-based polymer. A third organic solvent having a concentration of 50 to 70% by weight and stretching 1.1 to 3.0 times in a second coagulation bath composed of an organic solvent aqueous solution at a temperature of 30 to 50 ° C. Is performed.

In the method for producing an acrylonitrile-based fiber bundle of the present invention having the above-described structure, the swelling fiber bundle before drying after being stretched in a second coagulation bath by 1.1 to 3.0 times is used. It is preferable that the degree of swelling be 70% by weight or less. If the stretching ratio in the second coagulation bath is too large, the stretching ratio in the post-stretching will decrease. Further, another method for producing an acrylonitrile-based fiber bundle for a carbon fiber precursor according to the present invention is a spinning method comprising dissolving an acrylonitrile-based polymer containing 95% by weight or more of acrylonitrile units in a first organic solvent. The stock solution is discharged into a first coagulation bath containing an organic solvent aqueous solution at a temperature of 30 to 50 ° C containing a second organic solvent capable of dissolving the acrylonitrile polymer at a concentration of 50 to 70% by weight. The coagulated yarn is taken out from the first coagulation bath at a take-up speed of 0.8 times or less of the linear speed of discharge of the spinning solution, and then the coagulated yarn is treated with an acrylonitrile-based polymer. It contains a soluble third organic solvent at a concentration of 50 to 70% by weight and is 1.1 to 3.0 times in a second coagulation bath composed of an organic solvent aqueous solution at a temperature of 30 to 50 ° C. Stretching is performed, and thereafter, a further 4 times or more ripening stretching is performed.

In the method for producing an acrylonitrile-small fiber bundle of the present invention having the above-described structure, the swelling degree of the swollen fiber bundle after wet-stretching and before drying is 70% by weight or less. Is preferable.

In the acrylonitrile-based fiber bundle of the present invention and the method for producing the same, a polymer containing 95% by weight or more of acrylonitrile is used as the acrylonitrile-based polymer. As the acrylonitrile-based polymer, a homopolymer or copolymer of acrylonitrile or a mixture of these polymers can be used.

The acrylonitrile copolymer is a copolymerization product of a monomer copolymerizable with acrylonitrile and acrylonitrile. Examples of monomers copolymerizable with acrylonitrile include methyl (meth) acrylate and ethyl. (Meth) acrylic acid esters such as (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, vinyl chloride, vinyl chloride, and vinyl chloride Vinyl halides such as vinylidene, acids having polymerizable double bond such as (meth) acrylic acid, itaconic acid, crotonic acid and salts thereof, maleic imide, phenyl maleimide, (meth) acrylamide Styrene, α-methylstyrene, vinyl acetate, sodium styrenesulfonate, arylsulfone Soda, beta one sodium styrenesulfonate, including a polymerizable unsaturated monomer sulfone group such as main evening Arirusuruhon sodium, 2-vinylpyridine, 2-methyl-5-vinylpyridine Examples of the power include, but are not limited to, polymerizable unsaturated monomers containing a pyridine group.

Examples of the polymerization method include, but are not limited to, redox polymerization in an aqueous solution, suspension polymerization in a heterogeneous system, and emulsion polymerization using a dispersant.

The acrylonitrile-based fiber bundle for a carbon fiber precursor of the present invention is a fiber bundle having a total denier of more than 30,000 (33,000 dtex), and the surface of a single fiber forming the fiber bundle. The fiber bundle has 2 to 15 wrinkles having a height of 0.5 to 1.0 m which are substantially continuous in the longitudinal direction of the fiber bundle. In the present invention, a convex portion which is continuously observed in a longitudinal direction in a field of 10 u 10 m of a fiber surface selected unspecified is defined as "wrinkle" defined here, and the number thereof is counted. .

Due to the presence of the wrinkles, the acrylonitrile-based fiber bundle of the present invention has good binding properties, and the carbon fiber yarn using the fiber bundle as a precursor has a good spread when used for prepreg production. It shows the nature.

If the height of the wrinkles is too high, the surface area of the fiber bundle increases, so that static electricity is easily generated and the convergence of the fiber bundle is reduced. If the height of the wrinkles is too low, good convergence due to the presence of wrinkles and good spreadability when manufacturing a pre-predder using a carbon fiber yarn using the fiber bundle as a precursor can be obtained. Disappears.

Therefore, the height of the wrinkles is more preferably 0.6 to 0.8 μm. Also, the width of the wrinkles is about 0.5 to 1.0 m, preferably 0.6 to 0.8 mm.

If the number of the wrinkles is too large, the surface area of the fiber bundle increases and static electricity is easily generated, and the convergence of the fiber bundle is reduced. If the number of the wrinkles is too small, good convergence due to the presence of the wrinkles and good spreadability when producing a prepreg using a carbon fiber yarn using the fiber bundle as a precursor are obtained. Can not be.

Therefore, it is necessary that the number of fibers is 2 to 15 on the surface of the single fiber constituting the fiber bundle of the present invention, and preferably 12 to 15 fibers. The number of wrinkles specified in the present invention does not require that all the single fibers constituting the fiber bundle have such a number of wrinkles, and is 80% or more, preferably 90% or more. % Or more, more preferably 9 It is sufficient that 5% or more of the single fibers have such a number of wrinkles.

Further, the fiber bundle of the present invention is required to have an iodine adsorption amount per fiber weight of 0.5 to L. 5% by weight, preferably 0.5 to 1.0% by weight. The iodine adsorption amount is a measure of the compactness of the acrylonitrile fiber bundle, and is a value measured according to the following iodine adsorption method described in JP-A-63-85168.

[Measurement method of iodine adsorption amount]

The dried sample of about 0. 5 g of fiber length. 5 to 7 cm placed in a precisely weighed to 200 m 1 of stoppered Erlenmeyer flasks, to which iodine solution _{(1 2: 51 g, 2} , 4 Jikurorofu I Nord: 10 g, acetic acid: 90 g, 100 g of potassium iodide were weighed, transferred to a 1-liter volumetric flask, dissolved in water to make a fixed 1-liter iodine solution), 100 ml was added, and 60 ± 0.5 was added. After shaking at 50 ° C for 50 minutes to perform the adsorption treatment, the iodine-absorbed sample is washed with running water for 30 minutes, centrifugally dehydrated (2000 rp mx l minutes), and then quickly air-dried. It is determined from the weight increase obtained by precisely weighing this.

If the value of the amount of adsorbed iodine on the fiber bundle is too small, it indicates that the density of the fiber bundle is too high, that is, the density of the fiber surface is high and the morphology of the fiber surface is smooth. Is not preferred. On the other hand, if the value of the iodine adsorption amount of the fiber bundle is too large, it means that the denseness of the fiber surface is too low. Then, there is a problem that the spinning speed cannot be increased due to a large drying load when obtaining the atarilonitrile fiber bundle. In addition, the strength of the carbon fiber yarn obtained by firing this is greatly reduced.

The acrylonitrile-based fiber bundle of the present invention has good convergence even with a so-called large tow having a total denier of 30,000 (total fineness of 33,00 Od tex) or more due to the above configuration, and It is possible to perform high-density firing using the fiber bundle. Therefore, the effect of the present invention that high-density baking can be performed is most effectively exhibited when a fiber bundle having a total fineness of 55,000 dtex or more is obtained.

Further, in the fiber bundle of the present invention, the electrostatic charge measured by the measurement method described below is in the range of 11 kV to +1 kV, which enhances the convergence of the fiber bundle. Is preferred. In particular, when the electrostatic charge amount is in the range of 0.5 kV to +0.5 kV, the damage to the single fiber due to the dispersion of the fiber bundle is small, and the performance is not reduced and the stable high Quality can be maintained.

[Measurement method of electrostatic charge amount]

Two iron nipples with hard chrome plating on the surface are installed at a distance of 6 Om from each other, and the acrylonitrile fiber bundle to be measured is passed between these nip rollers. Place the TAT IRON IE sensor 10 cm in front of the nipploller on the winding side, 0.5 cm away from the acrylonitrile fiber bundle.

Next, the acrylonitrile-based fiber bundle is run for 5 Om, and the measurement of the charged voltage is started. The charged voltage value when the running of the acrylonitrile-based fiber bundle is stabilized and the charged voltage does not fluctuate is determined by the acrylonitrile-based fiber bundle. It is the amount of electrostatic charge of the fiber bundle.

Further, the acrylonitrile-based fiber bundle of the present invention may be provided with an oil agent in order to make the charged voltage value of the fiber bundle within an appropriate range to further enhance the convergence. Examples of the oil agent at this time include a silicone oil agent, an aromatic ester oil agent, and a sulfur-containing aliphatic ester oil agent. The silicon-based oil agent not only enhances the convergence of the acrylonitrile-based fiber bundle, but also enhances the strength and elasticity of the carbon fiber yarn obtained by firing the ata- lonitrile-based fiber bundle.

Next, a method for producing an acrylonitrile-based fiber bundle for a carbon fiber precursor of the present invention will be described.

As described above, in the method for producing an acrylonitrile-based fiber bundle for a carbon fiber precursor according to the present invention, a spinning dope obtained by dissolving an acrylonitrile-based polymer containing 95% by weight or more of acrylonitrile units in a first organic solvent. Is discharged into a first coagulation bath comprising an organic solvent aqueous solution at a temperature of 30 to 50 ° C containing a second organic solvent capable of dissolving the atarilonitrile-based polymer at a concentration of 50 to 70% by weight. The coagulated yarn is taken out of the first coagulation bath at a take-up speed of 0.8 times or less of the linear spinning speed of the spinning dope, and then the coagulated yarn is dissolved in the third coagulating yarn which can dissolve the acrylonitrile-based polymer. In a second coagulation bath containing an organic solvent aqueous solution at a temperature of 30 to 50 ° C, the film is stretched 1.1 to 3.0 times. Furthermore, in another method for producing an acrylonitrile-based fiber bundle for a carbon fiber precursor according to the present invention, a spinning solution obtained by dissolving an acrylonitrile-based polymer containing 95% by weight or more of acrylonitrile units in a first organic solvent is used. And containing a second organic solvent capable of dissolving the etalilonitrile-based polymer at a concentration of 50 to 70% by weight and discharging into a first coagulation bath comprising an organic solvent aqueous solution at a temperature of 30 to 50 ° C. The coagulated yarn is drawn from the first coagulation bath at a drawing speed of 0.8 times or less of the linear speed of discharge of the spinning solution, and then the coagulated yarn is dissolved by dissolving an acrylonitrile-based polymer. Stretching 1.1 to 3.0 times in a second coagulation bath containing an organic solvent aqueous solution at a temperature of 30 to 50 ° C, containing the obtained third organic solvent at a concentration of 50 to 70% by weight. After that, wet heat stretching of 4 times or more is performed.

The first to third organic solvents used in the present invention are all organic solvents capable of dissolving the acrylonitrile-based polymer, and include, for example, dimethylacetamide, dimethylsulfoxide, dimethylformamide and the like.

As the spinning dope, an organic solvent solution obtained by dissolving an atarilonitrile-based polymer in a first organic solvent can be used. Dimethylacetamide is particularly preferred as the first organic solvent. Not only does the spinning dope have poor properties due to the hydrolysis of the solvent, but also a spinning dope having good spinnability can be obtained, and a carbon fiber yarn having stable performance can be obtained after firing the acrylonitrile fiber bundle.

The spinneret for extruding the undiluted spinning solution has a pore size for producing acrylyl single fibers of about 1.0 dtex, which is a typical thickness for spinning when obtaining an acrylonitrile fiber bundle, namely, 15 A spinneret having a nozzle hole with a diameter of ~ 100 m can be used. In particular, from the viewpoint of maintaining good spinnability by setting the “coagulated yarn take-up speed / discharge linear speed of the spinning dope from the nozzle” to 0.8 or less, a nozzle hole with a hole diameter of 15 to 50 m is required. It is particularly preferred to use a spinneret having Further, the conditions of the first and second coagulation baths and the drawing conditions in the second coagulation bath specified in the present invention are important for increasing the orientation of the obtained acrylonitrile fiber bundle.

Both the concentration of the second organic solvent in the first coagulation bath and the concentration of the third organic solvent in the second coagulation bath are 50 to 70% by weight as described above. Do For this purpose, it is preferable to make the organic solvent concentrations in the two coagulation baths substantially the same. Specifically, the difference between the concentrations of the organic solvents in the two coagulation baths is within 5% by weight, preferably within 3% by weight.

Further, it is also preferable to make the temperatures of the first coagulation bath and the second coagulation bath substantially the same in order to make the coagulation of the coagulated yarn uniform. The temperature difference between the first coagulation bath and the second coagulation bath is preferably within 5 ° C, particularly preferably within 3 ° C.

Further, it is preferable that the types of the organic solvents are the same, and it is particularly preferable that the types of the first to third organic solvents are the same. By doing so, the coagulation of the coagulated yarn can be made uniform and the solvent can be easily recovered.

Therefore, use dimethylacetamide for both the first organic solvent for the spinning dope, the second organic solvent in the first coagulation bath, and the third organic solvent in the second coagulation bath. Is most preferred.

Since the concentration of the organic solvent in the liquid contained in the coagulated yarn exceeds the concentration of the organic solvent in the first coagulated bath, only the surface of the coagulated yarn is removed from the coagulated yarn. It is in a solidified semi-solid state. In such a state, the stretchability in the next second coagulation bath is improved by removing the coagulated yarn from the first coagulation bath. Further, as described later, the take-up speed of the coagulated yarn from the first coagulation bath should be 0.8 times or less of the linear spinning speed of the undiluted spinning solution for uniform coagulation in the first coagulation bath. And is important. In particular, it is preferably 0.5 times or less, but if it is too small, uniform solidification cannot be formed, and therefore, it is generally 0.3 times or more.

The coagulated yarn in the swollen state containing the coagulation liquid can be drawn in the air, but by adopting the means for drawing the coagulated yarn in the second coagulation bath as described above, The coagulation of the coagulated yarn can be promoted, and the temperature control in the drawing step becomes easy.

If the drawing of the coagulated yarn in the second coagulation bath is performed at a draw ratio of more than 3 times, breakage of single fibers and fluff are likely to occur in a wet heat drawing process such as boiling water drawing. If it is more than 4 times, single fiber breakage and fluff will occur in the second coagulation bath, making spinning impossible. When the stretching ratio is less than 1.1 times, it is difficult to obtain the effect of orienting the atarilononitrile fiber bundle by the stretching in the second coagulation bath. When a step of further performing wet heat stretching after the stretching in the second coagulation bath is employed, the stretching ratio in the second coagulation bath is preferably set to 2.0 times or less, whereby the wet heat Stretchability in the stretching step can be improved.

Next, the swollen fiber bundle that has been drawn in the second coagulation bath is washed with water and dried to obtain a target acrylonitrile fiber bundle.

Alternatively, the swollen fiber bundle that has been drawn in the second coagulation bath is subjected to wet heat drawing in order to further increase the fiber orientation, and then dried to obtain the desired acrylonitrile-based fiber bundle. The wet heat drawing method is to draw the swelled fiber bundle that has been drawn in the second coagulation bath while washing it with water, or to draw it in hot water or boiling water to improve productivity. And a method of stretching in the medium.

The fiber bundle in the swollen state after drawing in the second coagulation bath can be drawn after drying, but if the drawing step after drying is adopted, static electricity is easily generated and convergence is low. In order to obtain the acrylonitrile-based fiber bundle of the present invention for the acrylonitrile-based fiber bundle having a total fineness of 33, OOO dtex or more, the total fineness is more than 33, OOO dtex. The stretching is preferably performed by a wet heat stretching method. In other words, by performing wet heat stretching at least four times subsequent to the stretching in the second coagulation bath, a significant decrease in convergence caused by the stretching step does not occur, and a dense acrylonitrile fiber bundle is obtained. Can be The stretching ratio in this wet heat stretching can be determined as appropriate, and is, for example, 8 times or less.

Further, in the production method of the present invention, the swelling degree of the swollen fiber bundle after stretching and before drying is 70% by weight or less. It is preferable in terms of forming a high-performance carbon fiber yarn, and by lowering the "coagulation yarn take-off speed Z linear discharge speed of the spinning solution from the nozzle" when producing the coagulation yarn in the first coagulation bath, the first coagulation The coagulation of the coagulated yarn in the bath is made uniform, and the coagulated yarn is drawn in the second coagulation bath to make the yarn uniformly oriented to the inside. The degree of swelling of the swollen fiber bundle can be 70% by weight or less.

In other words, when the “coagulation yarn take-up speed / discharge linear velocity of the spinning stock solution from the nozzle” in the production of the coagulation yarn in the first coagulation bath is increased, the coagulation yarn in the first coagulation bath is produced. Since coagulation and drawing occur simultaneously, coagulation of the coagulated yarn in the first coagulation bath becomes uneven. Therefore, even if this is stretched in the second coagulation bath, the swollen fiber bundle after stretching and before drying has a low degree of swelling, that is, a yarn that is uniformly oriented to the inside cannot be formed.

The degree of swelling of the swelled fiber bundle before drying is determined by the weight w after removing the adhering liquid of the swelled fiber bundle using a centrifuge (300 rpm, 15 minutes), From the weight w ₀ after drying this with a hot air dryer at 110 ° C x 2 hours,

Swelling degree (%) = (w_w.) X 100 / wo

It is a numerical value obtained by:

In the production method of the present invention, the fiber bundle after drawing in the second coagulation bath or after drawing in the second coagulation bath and subsequent wet heat drawing is subjected to a known drying method. The acrylonitrile-based fiber bundle of the present invention is dense and high productivity can be obtained by drying the acrylonitrile-based fiber bundle of the present invention. In addition to being able to be used as a fiber, it can also be used as a chopped fiber for reinforcing fibers in industrial materials, taking advantage of the chemical resistance of acrylonitrile-based fibers.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the specific configuration of the acrylonitrile-based fiber bundle of the present invention and the method for producing the same will be described based on examples.

In the examples, wrinkles were observed by using a surface scanning electron microscope to observe the fiber surface morphology at a high magnification, and in the longitudinal direction within a range of 10 m x 10 m of the fiber surface selected unspecified. Continuously observed wrinkles were counted.

Example 1

Acrylonitrile, methyl acrylate, and methacrylic acid are copolymerized by aqueous suspension polymerization using ammonium persulfate, ammonium hydrogen sulfite, and iron sulfate, and acrylonitrile units Z methyl acrylate units Z methacrylic acid units = 95 / Atarilonitrile copolymer consisting of 4/1 (by weight) was obtained. The copolymer is treated with dimethyl acetate. The solution was dissolved in toamide to prepare a spinning solution having a concentration of 21% by weight.

This spinning dope is discharged through a spinneret having a pore number of 50,000 and a pore diameter of 60 m into a first coagulation bath composed of a dimethylacetoamide aqueous solution having a temperature of 35 ° C and a concentration of 65% by weight. The coagulated yarn was taken out of the first coagulation bath at a take-up speed of 0.4 times the linear speed of discharge of the spinning stock solution. The coagulated yarn was subsequently led to a second coagulation bath consisting of an aqueous dimethylacetamide solution having a temperature of 35 t and a concentration of 65% by weight, and was stretched 1.2 times in the bath. Then, the film was stretched 2.0 times at the same time as washing with water, and further stretched 2.5 times in boiling water.

After the treatment with the oil agent and drying with a hot roll, the acrylonitrile fiber bundle having a single fiber fineness of 1.1 dtex was obtained by winding it up with a winder. The final spinning speed at this time was 80 minutes.

The dry state of the obtained atarilonitrile fiber bundle is good, and the surface of the single fiber of the acrylonitrile fiber bundle has wrinkles having a height of 1.0 m which is substantially continuous in the longitudinal direction of the fiber bundle. There were five.

The iodine adsorption of the acrylonitrile fiber bundle was measured and found to be 1.0% by weight per fiber weight. The degree of swelling of the acrylonitrile fiber bundle after wet heat stretching was 65% by weight. The strand strength of the carbon fiber yarn obtained by firing this acrylonitrile fiber bundle was 400 kgZmm ² .

Example 2

The spinning dope prepared in Example 1 was replaced with? Through a spinneret having a diameter of 50,000 and a pore diameter of 45 m, the mixture was discharged at a temperature of 35 into a first coagulation bath consisting of a 60% by weight aqueous solution of dimethylacetamide at a temperature of 35 to form a coagulated yarn. The coagulated yarn was taken out of the first coagulation bath at a take-up speed of 0.3 times the linear speed of discharging the spinning stock solution. Subsequently, it was led to a second coagulation bath composed of an aqueous solution of dimethylacetamide having a temperature of 40 ° C. and a concentration of 60% by weight, and was stretched 1.2 times in the bath. Then, the film was stretched 2.0 times at the same time as washing with water, and further stretched 2.5 times in boiling water.

After the oil treatment, the product was dried with a hot roll and wound up with a winder to obtain an acrylonitrile fiber bundle having a single fiber fineness of 1.1 dtex. The final spinning speed at this time was 80 mZ minutes. The obtained acrylonitrile-based fiber bundle has a good dry state, and the surface of the single fiber of the acrylonitrile-based fiber bundle has three wrinkles having a height of 0.8 m which are substantially continuous in the longitudinal direction of the fiber bundle. Existed.

The iodine adsorption amount of the Atari π-nitrile fiber bundle was 0.8% by weight per fiber weight. The swelling degree of the acrylonitrile fiber bundle after the wet heat stretching was 65% by weight. Furthermore, the strand strength of the carbon fiber yarn obtained by baking this atarilonitrile fiber bundle was 41 O kgZmm ² .

Example 3

Acrylonitrile, acrylic acid, and methacrylic acid are polymerized by aqueous suspension polymerization using ammonium persulfate, ammonium hydrogensulfite, and iron sulfate, and acrylonitrile units Z acrylic acid units Z methyl teraryl acid units = 96/2/2 ( Acrylonitrile-based copolymer consisting of The copolymer was dissolved in dimethylacetamide to prepare a spinning dope having a concentration of 21% by weight.

This spinning dope is used for 50, 000,? Through a spinneret having a diameter of 55 m, the mixture is discharged into a first coagulation bath composed of a dimethylacetamide aqueous solution having a temperature of 30 ° C and a concentration of 65% by weight to form a coagulated yarn. This coagulated yarn was taken out at a take-up speed 0.3 times the linear speed of discharge of the stock spinning solution. Bow I was followed by a second coagulation bath consisting of an aqueous solution of dimethylacetamide at a temperature of 35 ° C and a concentration of 65% by weight, and stretched 1.2 times in the bath. Then, the film was stretched 2.0 times at the same time as washing with water, and further stretched 2.5 times in boiling water.

After the oil treatment, the product was dried with a hot roll and wound up with a winder to obtain an atarilonitrile fiber bundle having a single fiber fineness of 1. ldtex. The final spinning speed at this time was 80 mZ minutes.

The dried state of the obtained acrylonitrile-based fiber bundle is good, and the surface of the single fiber of the acrylonitrile-based fiber bundle has four wrinkles having a height of 0.7 m which are substantially continuous in the longitudinal direction of the fiber bundle. Existed.

Further, the iodine adsorption amount of this acrylonitrile fiber bundle was measured and found to be 0.8% by weight per fiber weight. The degree of swelling of the atarilonitrile fiber bundle after the wet heat drawing was 61% by weight. Further baking this atarilonitrile fiber bundle The strand strength of the carbon fiber yarn obtained as described above was 420 kg / mm ² .

Example 4

Acrylonitrile, acrylic acid, and methacrylic acid are polymerized by aqueous suspension polymerization using ammonium persulfate, ammonium hydrogensulfite, and iron sulfate, and acrylonitrile units / acrylic acid units Z methacrylic acid units 2 96/3/1 (weight ) Was obtained. The copolymer was dissolved in dimethylacetamide to prepare a spinning dope having a concentration of 21% by weight.

The spinning dope was used for 50, 000,? Through a 45 m spinneret into a first coagulation bath consisting of an aqueous solution of dimethylacetamide at a temperature of 35 ° C and a concentration of 60% by weight to form a coagulated yarn. This coagulated yarn was taken out at a take-up speed 0.3 times the linear speed of discharge of the stock spinning solution. Bow I was followed by a second coagulation bath consisting of an aqueous solution of dimethylacetamide at a temperature of 35 ° C. and a concentration of 60% by weight, and stretched 2.0 times in the bath. Then, the film was stretched 2.0 times at the same time as washing with water, and further stretched 2.5 times in boiling water.

After the oil treatment, the product was dried with a hot roll and wound up with a winder to obtain an acrylonitrile fiber bundle having a single fiber fineness of 1.1 ltex. The final spinning speed at this time was 80 mZ minutes.

The obtained acrylonitrile-based fiber bundle has a good dry state, and the surface of the single fiber of the acrylonitrile-based fiber bundle has a height of 0.7 μm which is substantially continuous in the longitudinal direction of the fiber bundle.

There were five wrinkles. '

The iodine adsorption amount of the acrylonitrile fiber bundle was 0.7% by weight per fiber weight. The swelling degree of the acrylonitrile fiber bundle after the wet heat stretching was 61% by weight. Further, the strand strength of the carbon fiber yarn obtained by baking this atarilonitrile fiber bundle was 420 kg / mm ² .

Comparative Example 1

After the coagulated yarn was taken out of the first coagulation bath in the same manner as in Example 1, the film was drawn 1.2 times in air without using the second coagulation bath. Further, at the same time as washing with water, stretching was performed by a factor of 2.0, followed by stretching by a factor of 2.5 in boiling water. Same as in Example 1 After the oil treatment, the product was dried with a hot roll and wound up with a winder to obtain an acrylonitrile fiber bundle having a single fiber fineness of 1.1 dtex. The final spinning speed at this time was 60 minutes.

Drying of the obtained atarilonitrile-based fiber bundle is insufficient, and wrinkles having a height of 0.4 are discontinuous in the longitudinal direction of the fiber bundle on the surface of the single fiber of the atarilonitrile-based fiber bundle. There was a book. Further, the strand strength of the carbon fibers obtained by firing after thoroughly drying the acrylonitrile fiber bundle, Atsuta at 3 8 ₀ kg / mm ² 0

Comparative Example 2

After the coagulated yarn was taken out of the first coagulation bath in the same manner as in Example 1, drawing was performed 1.7 times in the air without using the second coagulation bath. Further, the film was stretched 1.4 times at the same time as washing with water, and then stretched 2.5 times in boiling water. Further, in the same manner as in Example 1, after treatment with the oil agent, drying with a hot roll was performed, and the resultant was wound up with a winder to obtain an acrylonitrile-based fiber bundle having a single fiber fineness of 1.1 dtex. The final spinning speed at this time was 60 mZ.

On the surface of the single fiber of the obtained acrylonitrile-based fiber bundle, there were six wrinkles having a height of 0.4 μm that were actually continuous in the longitudinal direction of the fiber bundle. Further, the iodine adsorption amount of this acrylonitrile fiber bundle was measured to be 2.0% by weight per fiber weight.

The swelling degree of the acrylonitrile fiber bundle after wet heat drawing was 85% by weight. Further, the strand strength of the carbon fiber yarn obtained by firing this acrylonitrile fiber bundle was 390 kgZmm ² .

Comparative Example 3

After the coagulated yarn was taken out from the first coagulation bath in the same manner as in Example 1, it was subsequently placed in a second coagulation bath consisting of an aqueous dimethylacetoamide solution having a temperature of 35 ° C and a concentration of 60% by weight. The film was stretched 0 times. Further, the film was stretched 2.0 times at the same time as washing with water. Subsequently, when performing drawing at a ratio of 2.5 in boiling water, breakage of single fibers and fluff of the acrylonitrile fiber bundle occurred in the boiling water drawing process, and the spinning was interrupted.

Comparative Example 4 After the coagulated yarn was taken out of the first coagulation bath in the same manner as in Example 1, it was subsequently led into a second coagulation bath consisting of an aqueous dimethylacetoamide solution having a temperature of 35 ° C. and a concentration of 60% by weight. In the second coagulation bath, single fiber breakage and fluff occurred, and spinning was interrupted.

SEM (Surface Scanning Electron Microscope) photographs of Example 1 and Comparative Example 1 are shown in FIGS. 1 and 2, respectively.

Industrial applicability

The acrylonitrile-based fiber bundle for a carbon fiber precursor of the present invention is excellent in convergence, excellent in denseness, and small in drying load.

Therefore, even a fiber bundle having a total fineness of 33, OO Odtex or more can be efficiently produced without a decrease in spinning speed.

Further, according to the present invention, since the fiber bundle has a total fineness of 33,000 dtex or more, when a carbon fiber yarn having this as a precursor is subjected to molding, a plurality of carbon fiber yarns are used. This eliminates the need for a process of aligning books, and can solve the trouble and complexity of manufacturing molded articles.

Further, the acrylonitrile fiber bundle for a carbon fiber precursor of the present invention has an iodine adsorption amount per fiber weight in the range of 0.5 to 1.5% by weight. As described above, not only has excellent convergence but also good openability when manufacturing a pre-predder using a carbon fiber yarn using this as a precursor. It is.

Furthermore, according to the method for producing an acrylonitrile-based fiber bundle for a carbon fiber precursor of the present invention, the above-described excellent denseness, low drying load, and excellent bunching properties, as a carbon fiber yarn precursor, An acrylonitrile fiber bundle suitable for use can be easily and stably produced.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1: SEM photograph of the etalilonitrile fiber bundle for carbon fiber precursor of Example 1.

Figure 2: SEM photograph of the etalilonitrile fiber bundle for carbon fiber precursor of Comparative Example 1.

Claims

The scope of the claims

A fiber bundle of 3,000 or more total denier comprising an acrylonitrile-based polymer containing 1.9% by weight or more of acrylonitrile units, wherein the surface of a single fiber constituting the fiber bundle is a fiber bundle. 2 to 15 wrinkles having a height of 0.5 to 1.0 μm which are substantially continuous in the longitudinal direction of the fiber bundle, and the amount of iodine adsorbed per fiber weight of the fiber bundle is 0.5 to An acrylonitrile fiber bundle for a carbon fiber precursor, which is 1.5% by weight.

2.95 The spinning stock solution obtained by dissolving an acrylonitrile-based polymer containing 5% by weight or more of atarilonitrile units in a first organic solvent is concentrated in a second organic solvent capable of dissolving an acrylonitrile-based polymer. 50 to 70% by weight, and discharged into a first coagulation bath consisting of an organic solvent aqueous solution at a temperature of 30 to 50 ° C to form a coagulated yarn,

The coagulated yarn is taken out of the first coagulation bath at a drawing speed of 0.8 times or less of the linear speed of discharging the spinning stock solution,

Next, the coagulated yarn is contained in a second coagulation bath containing a third organic solvent capable of dissolving the acrylonitrile-based polymer at a concentration of 50 to 70% by weight and an aqueous solution of an organic solvent at a temperature of 30 to 50 ° C. Stretch 1.1 to 3.0 times

A method for producing an atarilonitrile-based fiber bundle for a carbon fiber precursor, comprising:

3.95 A spinning solution obtained by dissolving an acrylonitrile-based polymer containing 5% by weight or more of an acrylonitrile unit in a first organic solvent is mixed with a second organic solvent capable of dissolving an atarilonitrile-based polymer at a concentration of 50%. At a temperature of 30 to 50 ° C and discharged into a first coagulation bath made of an organic solvent aqueous solution to form a coagulated yarn,

The coagulated yarn is taken out of the first coagulation bath at a take-up speed of 0.8 times or less the discharge linear speed of the stock spinning solution,

Next, the coagulated yarn is contained in a second coagulation bath containing a third organic solvent capable of dissolving the acrylonitrile-based polymer at a concentration of 50 to 70% by weight and an aqueous solution of an organic solvent at a temperature of 30 to 50 ° C. Stretched 1.1 to 3.0 times at After that, perform wet heat stretching of 4 times or more

A method for producing an acrylonitrile-based fiber bundle for a carbon fiber precursor, comprising:

4. The method according to claim 2, wherein the swelling degree of the swollen fiber bundle after stretching and before drying is 70% by weight or less.

5. The method according to claim 3, wherein the swelling degree of the swollen fiber bundle after stretching and before drying is 70% by weight or less.

6. The production method according to claim 3, wherein the stretching ratio in the second coagulation bath is 1.1 to 2.0.

7. The method according to any one of claims 2 to 5, wherein the third organic solvent concentration in the second coagulation bath is substantially the same as the second organic solvent concentration in the first coagulation bath. The manufacturing method of the description.

8. The method according to any one of claims 2 to 5, wherein the first organic solvent, the second organic solvent, and the third organic solvent are the same.