KR102672670B1 - Acrylonitrile based spinning solution and method for preparing acrylonitrile based spinning fiber using the same - Google Patents

Abstract

The present invention has a transmittance of 70% or more, a change rate of the storage modulus of 10 to 12 at 55 to 70 seconds after the phase transition of the spinning solution, and the storage modulus is 50 ° C., a frequency of 10 rad / s, and a strain sweep of 0.05. It relates to an acrylonitrile-based spinning solution, which is a log scale value of a graph derived from measurement under % conditions, and a method of manufacturing an acrylonitrile-based spinning fiber using the same.

Description

Acrylonitrile-based spinning solution and method for manufacturing acrylonitrile-based spinning fiber using the same {ACRYLONITRILE BASED SPINNING SOLUTION AND METHOD FOR PREPARING ACRYLONITRILE BASED SPINNING FIBER USING THE SAME}

The present invention relates to an acrylonitrile-based spinning solution and a method for manufacturing acrylonitrile-based spinning fibers using the same. It relates to an acrylonitrile-based spinning solution that satisfies a specific range of permeability and rate of change in storage modulus and a method for manufacturing the same. .

Carbon fiber is a fibrous carbon material containing more than 90% by weight of carbon element based on the total weight, and is a fibrous precursor made from acrylonitrile-based polymer, pitch or rayon, which is a residue of petroleum or coal-based hydrocarbons, in an inert atmosphere. refers to fiber obtained through thermal decomposition. Carbon fiber has excellent characteristics such as heat resistance, chemical stability, electrical thermal conductivity, dimensional stability due to low thermal expansion, low density, friction and wear characteristics, X-ray transparency, electromagnetic wave shielding, biocompatibility, and flexibility, and depending on activation conditions, Very good adsorption properties can also be imparted.

Meanwhile, carbon fiber is prepared by dissolving an acrylonitrile-based polymer in a good solvent for the acrylonitrile-based polymer to prepare a spinning solution, and then going through a fiberization process such as coagulation, washing, stretching, and drying to produce an acrylonitrile-based fiber precursor. After manufacturing, it is manufactured by oxidation stabilization and carbonization. Among the above-mentioned fiberization processes, coagulation is a technology that coagulates acrylonitrile-based polymer through solvent exchange to manufacture it into the required form. Solvent exchange is performed by preparing a spinning solution with an acrylonitrile-based polymer and then coating it to form a thin film or spinning it into a fiber form and immersing it in a coagulation solution. In the coagulating solution, the good solvent and non-solvent of the acrylonitrile-based polymer are exchanged by diffusion, and over time, the acrylonitrile-based polymer solidifies and is processed into the desired form. And, if coagulation proceeds properly, a uniform acrylonitrile-based coagulated yarn with a circular cross-section and no skin-core structure can be manufactured by uniform water-solvent exchange on the fiber surface. Acrylonitrile-based coagulated yarn with this structure can reduce defects in oxidation stabilization and carbonization processes and improve the mechanical properties of carbon fiber.

The quality of products manufactured by this water-solvent exchange is greatly affected by the degree of deterioration of the spinning solution and the coagulation phenomenon of the spinning solution. If an excessively modified spinning solution is used, low-quality carbon fiber may be produced even if the coagulation process proceeds smoothly. In addition, if the solidification rate is too fast throughout the entire coagulation process or only in a specific section, large voids may be created inside, or spun fibers with a skin-core structure may be manufactured. On the other hand, if the coagulation speed is too slow, post-processes such as stretching and drying are performed without proper coagulation, and the spun fiber may be damaged by rollers, etc. Therefore, it is very important to be able to check whether the spinning solution is deteriorated before the coagulation process and to select a spinning solution with an appropriate coagulation speed.

However, using conventional analysis techniques, there were time delays and technical limitations in predicting the mechanical properties of the final carbon fiber from the circularity and structure (skin-core structure) of the acrylonitrile-based coagulated yarn.

KR2013-0056730A

The object of the present invention is to provide an acrylonitrile-based spinning solution that does not deteriorate and has an appropriate coagulation rate, to produce an acrylonitrile-based fiber precursor with a small amount of residual solvent and running hair, and to produce carbon fiber with excellent mechanical properties. will be.

The present invention has a transmittance of 70% or more, a change rate of the storage modulus of 10 to 12 at 55 to 70 seconds after the phase transition of the spinning solution, and the storage modulus is 50 ° C., a frequency of 10 rad / s, and a strain sweep of 0.05. An acrylonitrile-based spinning solution is provided, which is the log scale value of the graph derived from measurement under % conditions.

In addition, the present invention has a permeability of 70% or more, a change rate of the storage modulus of 10 to 12 at 55 to 70 seconds after the phase transition of the spinning solution, and the storage modulus is 50 ℃, frequency 10 rad/s, deformation A method for producing an acrylonitrile-based spinning fiber is provided, including the step of spinning an acrylonitrile-based spinning solution, which is the log scale value of the graph derived from measurement under sweep 0.05% conditions.

Since the spinning solution according to the present invention does not deteriorate and has an appropriate coagulation speed, it can be manufactured from an acrylonitrile-based fiber precursor with a small amount of residual solvent and running hair, and can be manufactured from carbon fiber with excellent mechanical properties.

1 is a perspective view schematically showing a storage modulus measurement device according to an embodiment of the present invention.
Figure 2 is a main sectional view schematically showing the state in which the operating part is installed in the container part of Figure 1.
Figure 3 is a main sectional view schematically showing the state in which the coagulation solution is injected into the container part of Figure 2.

Hereinafter, the present invention will be described in more detail to facilitate understanding of the present invention.

Terms or words used in this specification and claims should not be construed as limited to their common or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it is.

In the present invention, the transmittance can be measured by ultraviolet and visible light spectrophotometry at 450 nm, and in detail, it can be measured by an ultraviolet-visible spectrophotometer (manufacturer: Agilent Technologies, product name: Cary100) at 450 nm.

In the present invention, the rate of change of storage modulus can be derived using equipment that combines a rheometer (manufacturer: TA instruments, product name: DHR-2) with a directly manufactured solidification rate measurement device.

In the present invention, the acrylonitrile-based polymer is an acrylonitrile-based homopolymer in which acrylonitrile-based monomers are independently polymerized; It may be an acrylonitrile-based copolymer copolymerized with an acrylonitrile-based monomer and one or more comonomers selected from the group consisting of carboxylic acid-based monomers and alkyl (meth)acrylate-based monomers.

In the present invention, a good solvent for an acrylonitrile-based polymer refers to a solvent that has affinity for an acrylonitrile-based polymer. The good solvent is not particularly limited as long as it can dissolve the acrylonitrile-based polymer. The good solvent may be selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, and dimethylacetamide, and among these, it is preferred to be selected from the group consisting of dimethyl sulfoxide and N,N-dimethylformamide.

In the present invention, the non-solvent of an acrylonitrile-based polymer refers to a solvent that is incompatible with an acrylonitrile-based polymer, in which the acrylonitrile-based polymer coagulates and precipitates when in contact with the acrylonitrile-based polymer. The non-solvent is not particularly limited as long as it can promote coagulation of the acrylonitrile-based polymer. The non-solvent may be water.

1. Acrylonitrile-based spinning solution

The acrylonitrile-based spinning solution according to an embodiment of the present invention has a transmittance of 70% or more, and the rate of change in storage elastic modulus at 55 to 70 seconds after the phase transition of the spinning solution is 10 to 12, and the storage elastic modulus is This is the log scale value of the graph derived from measurements under the conditions of 50 ℃, frequency 10 rad/s, and deformation sweep 0.05%.

The present inventors found that the mechanical properties of carbon fiber are influenced by the molecular structure of the acrylonitrile-based polymer and the morphology of the acrylonitrile-based spun fiber, and that in order to manufacture carbon fiber with excellent mechanical properties, the molecular structure of the acrylonitrile-based polymer And it was found that the morphology of the acrylonitrile-based spun fiber must be controlled. In addition, it was found that the permeability of the acrylonitrile-based spinning solution is an indicator of the degree of deterioration of the acrylonitrile-based spinning solution, and the rate of change of the storage modulus of the acrylonitrile-based spinning solution is an indicator of the solidification speed of the spinning solution. In addition, it was discovered that high-quality acrylonitrile-based fiber precursors and carbon fibers could be produced by using a spinning solution with an appropriate level of change in permeability and storage modulus, and thus the present invention was completed.

Hereinafter, an acrylonitrile-based spinning solution according to an embodiment of the present invention will be described in detail.

The acrylonitrile-based spinning solution according to an embodiment of the present invention has a transmittance of 70% or more and a change rate of storage modulus of 10 to 12. The acrylonitrile-based spinning solution preferably has a transmittance of 75%, and the storage modulus change rate is preferably 11 to 12.

The acrylonitrile-based polymer contained in the acrylonitrile-based spinning solution may be affected by moisture and temperature and deteriorate over time. Specifically, the acrylonitrile-based monomer units of the acrylonitrile-based polymer are degenerated into amide-based monomer units, and these amide-based monomer units are lost during the oxidation stabilization process and carbonization process, which may act as defects in the carbon fiber. However, even if the acrylonitrile-based spinning solution is deteriorated, if the transmittance is 70% or more, defects derived from amide-based monomer units are minimized, and carbon fibers with excellent mechanical properties can be manufactured. In addition, an acrylonitrile-based fiber precursor with a small amount of residual solvent and a small amount of running hair can be produced, and as a result, carbon fiber with excellent mechanical properties can be produced. In addition, if the rate of change of the storage modulus described above is satisfied, the coagulation speed of the acrylonitrile-based spinning solution is maintained appropriately, the amount of residual solvent is small, and the acrylonitrile-based coagulated yarn is not damaged during the post-process, so the acrylonitrile-based coagulated yarn has less running hair. Ronitrile-based fiber precursors can be produced, and as a result, carbon fibers with excellent mechanical properties can be produced. However, if the change rate of the storage modulus is less than the above-mentioned range, the coagulation speed is too slow and post-processes such as stretching are performed before the acrylonitrile-based coagulated yarn takes the proper fiber form, resulting in a lot of damage from rollers, etc. . As a result, a lot of running hair is generated in the acrylonitrile-based fiber precursor, and carbon fiber with reduced mechanical properties can be manufactured. In addition, if the rate of change of the storage modulus is greater than the above-mentioned range, the solidification speed is so fast that only the surface is solidified and the inside is not solidified, resulting in the production of acrylonitrile-based coagulated yarn with a skin-core structure, and the inside of the acrylonitrile-based coagulated yarn Since the solvent is trapped, an acrylonitrile-based fiber precursor with an excessive amount of residual solvent may be manufactured. As a result, carbon fiber with reduced mechanical properties can be manufactured. In addition, acrylonitrile-based coagulated yarn with a skin-core structure does not stretch well, so it may break during the stretching process or be manufactured as carbon fiber with deteriorated mechanical properties.

The rate of change of the storage modulus is preferably derived from Equation 1 below.

<Equation 1>

Rate of change of storage modulus = [(Y ₁ - Y ₂ )/(X ₁ - X ₂ )] × 1,000

X ₁ : 55 to 70 seconds have passed since the phase transition of the spinning solution begins

X ₂ : The point at which the phase transition of the spinning solution begins

Y ₁ : Log scale (interval: 10) value of the storage modulus of the spinning solution at the time of X ₁

Y ₂ : Log scale (interval: 10) value of the storage modulus of the spinning solution at the time of X ₂

Here, the log scale may refer to the log scale (interval: 10) on the graph.

Meanwhile, the storage modulus of the acrylonitrile-based spinning solution can be measured using a storage modulus evaluation device including a rheometer.

Figure 1 is a perspective view schematically showing the storage elastic modulus measuring device, Figure 2 is a cross-sectional view of the main part schematically showing the operating part installed in the container part of Figure 1, and Figure 3 is a coagulating solution in the container part of Figure 2. This is a cross-sectional view of the main part schematically showing the injection state.

Referring to Figures 1 to 3, the storage modulus evaluation device 100 includes a main body 10 on which a lifting bar 20 that rises or falls is installed, and a coagulating solution 60 installed on the lifting bar 20. ) and the container portion 30 in which the receiving space 31 where the filter 50 is accommodated is formed, and is connected to the lifting bar 20, and is raised or lowered in the lower part of the receiving space 31 and placed on the spinning solution 40. It includes an operating unit 40 on which a positionable lifting plate 21 is installed, and a control unit 60 installed on the main body 10 to measure the storage modulus of the spinning solution 40.

The storage modulus can be measured while the spinning solution 40 is loaded on one surface of the filter 50. This will be explained in detail below.

The main body 10 refers to a rheometer that measures the rheological properties of an acrylonitrile-based spinning solution, and the storage modulus can be measured with the acrylonitrile-based spinning solution 40 accommodated therein. In this main body 10, a measurement space can be formed in which the storage modulus can be measured while the acrylonitrile-based spinning solution 40 is accommodated, and in this measurement space 11, a lifting bar that is operated to raise or lower ( 20) can be installed.

The lifting bar 20 can be installed to be raised or lowered in the measurement space 11 by a driving unit (not shown) installed on the main body 10. A container portion 30 in which the coagulation solution 60 and the filter 50 are accommodated may be installed at the lower part of the lifting bar 20. The filter 50 may include a paper filter 51 and a glass filter 52 through which good solvents and non-solvents can easily pass, but through which acrylonitrile-based polymers have difficulty passing.

The operating unit 40 is connected to the lifting bar 20, and a lifting plate 41 that rises or lowers within the receiving space 31 may be installed at the lower part. The lifting plate 41 may be formed in a size corresponding to the filter 50. The lifting plate 41 may be lowered until the gap with the filter 50 is 100 ㎛ to 1 mm, or 200 to 500 ㎛, of which it is preferable to be lowered until the gap is 200 to 500 ㎛. This is because if the above-mentioned conditions are satisfied, a coagulated product having the same or similar thread width as the spun fiber produced in the coagulation process of the acrylonitrile-based spinning solution can be produced. In addition, since differences in the coagulation phenomenon resulting from differences in the diameter of the coagulant can be minimized, it is possible to more accurately predict the actual coagulation phenomenon.

The control unit 60 can measure the storage modulus of the acrylonitrile-based spinning solution and can also measure changes in the storage modulus of the acrylonitrile-based spinning solution over time.

The storage modulus of the acrylonitrile-based spinning solution can be measured under the conditions of a temperature of 5 to 80 ℃, a frequency of 0.01 to 500 rad/s, a strain sweep of 0.1 to 5%, and a shear rate of 0.01 to 500 ^-1 . , it is preferably measured under the conditions of a temperature of 10 to 60 ℃, a frequency of 0.01 to 20 rad/s, a strain sweep of 0.3 to 1%, and a shear rate of 0.01 to 0.1 ^-1 . If the above-mentioned conditions are satisfied, it is possible to more accurately predict the actual coagulation phenomenon.

Meanwhile, the acrylonitrile-based spinning solution may have a pH of 8.9 to 10.3, preferably 9 to 10. If the above-mentioned range is satisfied, an acrylonitrile-based fiber precursor with a small amount of residual solvent and a small amount of running hair can be manufactured, and carbon fiber with excellent mechanical properties can be manufactured. The acrylonitrile-based spinning solution may further include ammonia water in order to satisfy the above-mentioned pH.

The acrylonitrile-based spinning solution may include an acrylonitrile-based polymer and a good solvent for the acrylonitrile-based polymer.

2. Manufacturing method of acrylonitrile-based spun fiber

The method for producing an acrylonitrile-based spun fiber according to another embodiment of the present invention has a transmittance of 70% or more as measured based on ultraviolet and visible light spectroscopy, and 55 to 70 seconds have elapsed after the phase transition of the spinning solution. Spinning an acrylonitrile-based spinning solution in which the rate of change of the storage modulus is 10 to 12, and the storage modulus is the log scale value of the graph derived from measurements under the conditions of 50 ° C., frequency 10 rad / s, and strain sweep 0.05%. Includes.

The acrylonitrile-based spinning solution may be an acrylonitrile-based spinning solution according to an embodiment of the present invention, and the description thereof is ‘1. As described above in ‘Acrylonitrile-based spinning solution’.

The spinning can be done using the spinning equipment, and the spinning equipment is not particularly limited unless it can be manufactured into spun fiber by spinning a spinning solution. The spinning may mean including all coagulation, washing, stretching, and drying processes.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement it. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

Example 1 to Example 4 and Comparative example 1 to Comparative example 6

<Manufacture of spinning solution>

Acrylonitrile (AN) and itaconic acid (IA) were mixed according to the composition shown in the table below to prepare a monomer mixture. A reaction solution was prepared by uniformly dissolving 100 parts by weight of the monomer mixture in 318 parts by weight of dimethyl sulfoxide.

The reaction solution was put into a reactor equipped with a stirrer and purged with nitrogen, and then the internal temperature of the reactor was raised to 60°C at a rate of 1°C/min. 0.6 parts by weight of azobisisobutyronitrile (AIBN) was added as an initiator, and solution polymerization was performed for 8 hours. Then, the temperature inside the reactor was raised to 70 °C at a rate of 1 °C/min, and solution polymerization was carried out for 6 hours. carried out. Afterwards, the reaction was terminated, and an acrylonitrile-based copolymer solution was obtained.

Dimethyl sulfoxide was additionally added to the acrylonitrile-based polymer solution to prepare a polymer solution having an acrylonitrile-based polymer concentration of about 20% by weight.

Next, NH ₃ was added or not added to the polymer solution in an equivalent amount shown in the table below based on 1 equivalent of itaconic acid (IA) to prepare a spinning solution having a pH shown in the table below.

<Measurement of transmittance>

A two-sided transparent cell (12.5 mm × 12.5 mm × 45 mm, 2 mL) was filled with more than 2/3 of the acrylonitrile-based polymer solution. The two-sided transparent cell was centrifuged at a speed of 2,500 rpm for 10 minutes to remove air bubbles inside. The transmittance of the polymer solution was measured at a wavelength of 450 nm using an ultraviolet-visible spectrophotometer (manufacturer: Agilent Technologies, product name: Cary100).

<Measurement of storage modulus>

A storage modulus measurement device as shown in FIGS. 1 to 3 was prepared.

A glass filter 52 is placed in the container 30 of the storage modulus measurement device 100, a paper filter 51 is placed on the glass filter 52, and 0.06 g of spinning solution is placed on the paper filter 51. was loaded. Then, the lifting bar 20 was lowered so that the gap between the lifting plate 21 and the paper filter 51 of the storage modulus measuring device was 500 ㎛. Next, the coagulating solution 60 containing water and dimethyl sulfoxide in a 5:5 ratio is injected into the container part 30 so that it touches the boundary surface of the paper filter 51, and the coagulating solution (60) is added to the spinning solution 40. 60) The storage modulus of the spinning solution was measured while passing through one side.

Here, the storage modulus measurement conditions were 50°C, frequency 10 rad/s, and strain sweep 0.05%.

Subsequently, a graph showing the value of the storage modulus on a logarithmic scale on the y-axis and time on a linear scale on the x-axis was output using Trios Software equipment (manufacturer: TA instruments, product name: TRIOS).

_From the above _graph , the variables X _{1 ,} Meanwhile, the rate of change of the storage modulus was rounded off and reported to the first decimal place.

<Equation 1>

Rate of change of storage modulus = [(Y ₁ - Y ₂ )/(X ₁ - X ₂ )] × 1,000

X ₁ : 62 seconds have passed since the phase transition of the spinning solution began

X ₂ : The point at which the phase transition of the spinning solution begins

Y ₁ : Log scale (interval: 10) value of the storage modulus of the spinning solution at the time of X ₁

Y ₂ : Log scale (interval: 10) value of the storage modulus of the spinning solution at the time of X ₂

division Comparative Example 1 Comparative Example 2 Example 1 Example 2 polymer AN (mole%) 99 99 99 99 IA (mole%) One One One One spinning solution Equivalent of NH ₃ to 1 equivalent of IA One One One One Storage period (days) 5 2 One 0.25 (6 hours) pH 8.3 8.8 9 9 Transmittance (%) 42 65 70 78 Rate of change of storage modulus approx 12.4 approx 11.8 approx 11.5 approx 11.6 X ₁ 99 99 99 99 X ₂ 37 37 37 37 Y ₁ 3.73 3.69 3.67 3.66 Y ₂ 2.96 2.96 2.96 2.94

division Comparative Example 3 Comparative Example 4 Example 3 Example 4 Comparative Example 5 Comparative Example 6 polymer AN (mole%) 99 99 99 99 99 99 IA (mole%) One One One One One One spinning solution Equivalent of NH ₃ to 1 equivalent of IA 2 1.7 1.4 1.1 0.8 - Storage period (days) One One One One One One pH 11.2 10.5 9.9 9.2 8.5 6.1 Transmittance (%) 72 71 72 70 75 85 Rate of change of storage modulus About 7.4 about 9.2 approx 10.2 approx 11.3 approx 13.1 approx 18.9 X ₁ 99 99 99 99 99 99 X ₂ 37 37 37 37 37 37 Y ₁ 2.98 3.19 3.57 3.64 3.75 4.5 Y ₂ 2.52 2.62 2.94 2.94 2.94 3.33

Referring to Example 1, Example 2, Comparative Example 1, and Comparative Example 2, it was confirmed that the longer the storage period of the spinning solution, the lower the transmittance of the spinning solution.

Referring to Comparative Example 3, Comparative Example 4, Example 3, Example 4, Comparative Example 5, and Comparative Example 6, it was confirmed that the rate of change in storage modulus increased as the pH of the spinning solution decreased.

Example 5 to Example 8, Comparative example 7 to Comparative example 12

<Manufacture of acrylonitrile-based fiber precursor>

After raising the temperature of the spinning solution shown in the table below to 50°C, 50% by weight of water and 50% by weight of dimethyl sulfoxide were added to a coagulation tank containing a circulating solvent using a spinneret (hole diameter: 65 ㎛, number of holes: 3,000). It was discharged at (temperature: 60°C) and coagulated to produce coagulated yarn.

Subsequently, the coagulated yarn was washed in the first washing tank (temperature: 60 °C), the second washing tank (temperature: 60 °C), the third washing tank (temperature: 70 °C), and the fourth washing tank (temperature: 70 °C). It was sequentially washed in the 5th water washing tank (temperature: 80°C) and the 6th water washing tank (temperature: 80°C). The water-washed coagulated yarn was hot-drawn in the first and second hot water baths (temperature: 95°C) using a roller to produce a first drawn yarn. Subsequently, the first drawn yarn was treated with an emulsion and dried at 110 to 140° C. to prepare a first dried yarn. The first dried yarn was drawn with steam to produce a second drawn yarn. Subsequently, the second drawn yarn was heat-set at 150 to 180° C. to prepare an acrylonitrile-based fiber precursor.

<Manufacture of acrylonitrile-based fiber>

The acrylonitrile-based fiber precursor was oxidized in a first oxidation furnace (temperature: 150 °C), a second oxidation furnace (temperature: 180 °C), a third oxidation furnace (temperature: 200 °C), and a fourth oxidation furnace (temperature: 230 °C). ), acrylonitrile-based fibers were manufactured by sequential oxidation stabilization.

<Manufacture of carbon fiber>

Acrylonitrile fibers were pre-carbonized at 300°C to 800°C in a first carbonization furnace in a nitrogen atmosphere. Additionally, it was carbonized at 800°C to 1,500°C in a second carbonization furnace in a nitrogen atmosphere.

Experiment example One

The physical properties of the acrylonitrile-based fiber precursors of Examples and Comparative Examples were measured by the method described below, and are listed in the table below.

① Residual solvent amount (ppm): 5 g of acrylonitrile-based fiber precursor was immersed in water at 90°C for 24 hours. After recovering the water, the content of dimethyl sulfoxide in the water was measured using liquid chromatography.

② Running hair (ea/min): Measurements were made on fibers that were running normally after the steam stretching process of the acrylonitrile-based fiber precursor. The running hair was measured by irradiating the light of a lantern to the running fiber for 2 minutes and observing it with the naked eye. Measurements were made a total of three times and the average value was recorded.

Experiment example 2

The physical properties of the carbon fibers of Examples and Comparative Examples were measured by the method described below, and are listed in the table below.

③ Strength (㎬): A carbon fiber bundle was impregnated with resin, cut into 300 mm lengths, and tabs were attached to both ends using resin to produce a strand specimen. At this time, the amount of impregnation was adjusted so that the resin impregnation rate of the strand specimen was 40% by weight, and the measured length of the specimen was 150 mm. The specimen was measured using a tensile strength tester (manufacturer: INSTRON, product name: 5982). The measurement speed was set at 10 mm/min and measurements were performed 7 times. Tensile strength and tensile modulus were measured on seven specimens, and the average values were recorded.

division Comparative Example 7 Comparative Example 8 Example 5 Example 6 spinning solution type Comparative Example 1 Comparative Example 2 Example 1 Example 2 pH 8.3 8.8 9 9 Transmittance (%) 42 65 70 78 Rate of change of storage modulus 12.4 11.8 11.5 11.6 Acrylonitrile-based fiber precursor Residual solvent amount (ppm) 410 400 360 320 driving mode
Woo(ea/min) 25 7 One 0.5 carbon fiber Strength (㎬) 3.1 3.5 4.1 4.2

division Comparative Example 9 Comparative Example 10 Example 7 Example 8 Comparative Example 11 Comparative Example 12 spinning solution type Comparative Example 3 Comparative Example 4 Example 3 Example 4 Comparative Example 5 Comparative Example 6 pH 11.2 10.5 9.9 9.2 8.5 6.1 Transmittance (%) 72 71 72 70 75 77 Rate of change of storage modulus 7.4 9.2 10.2 11.3 13.1 18.9 Acrylonitrile-based fiber precursor Residual solvent amount (ppm) 1,300 850 410 370 1,200 3,100 driving mow
(ea/min) 21 11 3 2 13 12 carbon fiber Strength (㎬) 3.2 3.5 4.0 4.1 3.3 2.9

Referring to Comparative Example 7, Comparative Example 8, Example 5 and Example 6, when the rate of change of the storage modulus of the spinning solution satisfies 10 to 12, Examples 5 and 6, which have a transmittance of 70% or more, have a transmittance of It can be seen that the residual solvent amount and running hair of the acrylonitrile-based fiber precursor are small compared to Comparative Examples 7 and 8, which are less than 70%, and the strength of the carbon fiber is also excellent.

Referring to Comparative Example 9, Comparative Example 10, Example 7, Example 8, Comparative Example 11 and Comparative Example 12, when the spinning solution has a transmittance of 70% or more, Example 7 and Example 7 where the change rate of storage modulus is 10 to 12 It can be seen that Example 8 has a lower amount of residual solvent and less running hair than Comparative Examples 9 and 10, which have a storage modulus change rate of less than 10, and that the strength of the carbon fiber is also excellent. In addition, it was confirmed that Examples 7 and 8 had less residual solvent and less running hair than Comparative Examples 11 and 12, which had a change rate of storage modulus of more than 12, and that the strength of the carbon fiber was also excellent.

Claims (7)

The transmittance is 70% or more, the rate of change of the storage elastic modulus at 55 to 70 seconds after the phase transition of the spinning solution is 10 to 12, and the storage elastic modulus is 50 ℃, frequency 10 rad/s, and strain sweep 0.05%. Acrylonitrile-based spinning solution, which is the log scale value of the graph derived from the measurement of .
In claim 1,
An acrylonitrile-based spinning solution having a transmittance of 75% or more.
In claim 1,
An acrylonitrile-based spinning solution wherein the rate of change of the storage modulus is 11 to 12.
In claim 1,
The acrylonitrile-based spinning solution has a pH of 8.9 to 10.3.
In claim 1,
The acrylonitrile-based spinning solution has a pH of 9 to 10.
In claim 1,
The acrylonitrile-based spinning solution is an acrylonitrile-based spinning solution containing an acrylonitrile-based polymer and a good solvent for the acrylonitrile-based polymer.
The transmittance is 70% or more, the rate of change of the storage elastic modulus at 55 to 70 seconds after the phase transition of the spinning solution is 10 to 12, and the storage elastic modulus is 50 ℃, frequency 10 rad/s, and strain sweep 0.05%. A method of producing an acrylonitrile-based spinning fiber comprising the step of spinning an acrylonitrile-based spinning solution whose log scale value is the graph derived from the measurement of.