JP2000199183A - Acrylonitrile fiber for producing carbon fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an acrylonitrile fiber capable of producing a high-quality carbon fiber while suppressing the generation of fluffs by spinning an acrylonitrile polymer solution, drawing the fiber in a bath, applying a specific textile oil to the drawn fiber, drying the oil and drawing the fiber in steam. SOLUTION: A fiber produced by spinning an acrylonitrile polymer solution and drawing in a bath is coated with an emulsion liquid of a textile oil containing (A) an aminosilicone oil, (B) a heat-resistant resin having a residual ratio of >=80% after the heat-treatment in air at 250 deg.C for 2 hr and <=10% after the heat-treatment at 500 deg.C for 5 min, such as an aromatic composite ester and (C) a moisture absorbent such as dioctyl sulfosuccinate. The applied liquid is dried and the fiber is drawn in steam to obtain the objective acrylonitrile fiber for the production of carbon fiber. Preferably, the application amount of the textile oil composed of the components A to C is 0.1-1 wt.% based on the fiber and the compounding ratio of B/A is 1-10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to acrylonitrile fibers used for producing carbon fibers and a method for producing the same.

More specifically, the acrylonitrile fiber for producing carbon fiber is improved in the convergence during oxidization and the processability in the sintering step, and is characterized in that the amount of Si compound generated as a by-product during the sintering step is small. The present invention relates to an excellent acrylonitrile fiber for producing carbon fiber.

[0003]

2. Description of the Related Art Conventionally, it has been widely known that acrylonitrile fibers are used for producing carbon fibers, and high-performance carbon fibers can be obtained through oxidization treatment and carbonization treatment.

[0004] In particular, in recent years, it has been applied to the aerospace field, particularly the primary structural material of aircraft, from sports and leisure goods. Furthermore, utilizing the high specific strength and specific elasticity properties of carbon fiber, it has become a material that has been noticed and studied in various industries to contribute to the reduction of CO ₂ emissions by energy saving. Along with this, high performance carbon fibers are required, and the carbon fibers are required to have good handleability.

In the production of such a high-performance carbon fiber, the characteristics of the acrylonitrile fiber, which is the raw material fiber, directly affect the performance of the target carbon fiber, and the high-performance and improved handleability of the carbon fiber The development of acrylonitrile for use is desired.

[0006] In particular, the surface rub resistance of the raw material acrylonitrile fiber is desired to be improved from the viewpoint of preventing the generation of so-called fluff due to breakage of a single fiber of the carbon fiber after firing. For this purpose, it is known to add a sizing agent (fiber oil agent) to raw acrylonitrile fibers. As a matter of course, the sizing agent is required to have heat resistance, and the use of a silicone oil agent as the sizing agent is known in many reports.

That is, it has long been known that an aminosilicone-based oil agent is applied to a fiber bundle to impart these properties to the acrylonitrile fiber because of heat resistance and abrasion resistance of the acrylonitrile fiber. (Japanese Patent Laid-Open No. 54-13 / 1979)
Nos. 4123 and 61-167024). These silicone oils are excellent in heat resistance, convergence, and abrasion resistance.

However, the disadvantages of the aminosilicone-based oil agent are that the oil agent attached to the acrylonitrile fiber during the firing of the carbon fiber is volatilized and decomposed, thereby contaminating the firing process. It has problems such as poor adhesion.

Generally, acrylic carbon fibers are obtained by oxidizing raw acrylonitrile fibers in an atmosphere at 200 to 300 ° C. and then carbonizing them in an inert atmosphere at 500 to 1800 ° C. Is
In the oxidation furnace and the carbonization furnace, there is a problem that granular silicon oxide, whisker-like and plate-like crystals of silicon nitride precipitate, and the fiber passages are closed or narrowed.

As a result, when the fiber to be treated passes, the fiber rubs against the wall of the furnace, causing fluff of the fiber to be treated. Further, when silicon nitride in the form of a plate is formed on the wall surface of the furnace, it is difficult to remove the silicon nitride easily, it is difficult to control the temperature distribution in the carbonization furnace, and the quality of carbon fibers is reduced. That is, the firing of carbon fiber is required to be performed in a carbonization furnace maintained at a constant temperature gradient according to the required performance, and therefore, when the above-mentioned plate-like silicon nitride is generated on the furnace wall surface, In order to control the temperature distribution in the carbonization furnace, the core replacement frequency of the carbonization furnace is increased, which causes a problem that productivity is reduced. Whisker-like crystals
Although removal from the carbonization furnace is easy, the dropped needle-like whiskers cause damage to the carbon fibers and are preferably reduced as much as possible.

According to the study of the present inventors, in the carbon fiber production process, the characteristics required for the sizing agent differ depending on the temperature zone through which the carbon fiber is produced by optimizing the oil agent composition. In the temperature range where the properties of aminosilicone oils are required as sizing agents are small, and in the lower temperature range, the absolute application amount of aminosilicone oils is reduced by utilizing the properties of other sizing agents and firing The present invention has been found that the precipitation of silicon oxide, whisker-like and plate-like silicon nitride crystals in the furnace can be reduced, and the narrowing of the fiber passage can be delayed.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a high-quality carbon fiber without deteriorating the effect of imparting convergence and abrasion resistance by taking advantage of the application of an aminosilicone-based oil agent.

Another object of the present invention is to solve the above-mentioned problems in the firing step caused by the application of the aminosilicone oil agent sizing agent, and to ensure the stability of the step.

The present invention relates to a process for producing carbon fiber,
Due to the aminosilicone-based oil agent added to the raw material acrylonitrile fiber, it reduces the production of silicon compounds in the carbonization treatment step in an inert gas atmosphere, enables long-term stable continuous operation, and reduces fluff. An object is to obtain high-quality carbon fibers by suppressing generation thereof.

[0015]

The present invention for solving the above-mentioned problems has the following construction. (1) An acrylonitrile fiber for producing carbon fiber, wherein a fiber oil containing the following A component, B component and C component is adhered in an amount of 0.05 to 1% by weight based on the total fiber weight. A component: aminosilicone oil B component: heat-resistant resin whose heat treatment condition in air is 250 ° C. × 2 hours and residue is 80% or more and 500 ° C. × 5 minutes and residue is 10% or less C component: hygroscopic agent

(Claim 2) Component A and component B of the fiber oil component
The acrylonitrile fiber for producing carbon fiber according to claim 1, wherein the compounding ratio with the component is in a range represented by the following formula (1). B / A = 1 to 10 (1)

(Claim 3) The component B is an aromatic complex ester derivative having a residual heat content of 80% or more after heating at 250 ° C. in air and having a liquid film-forming ability on the fiber surface. The acrylonitrile fiber for producing carbon fiber according to claim 1 or 2, characterized in that:

(Claim 4) The acrylonitrile fiber for producing carbon fiber according to claim 3, wherein the component C is dioctyl sulfosuccinate.

(Claim 5) An emulsion liquid of a fiber oil containing the following components A, B and C is applied to a fiber obtained by spinning an acrylonitrile polymer solution and stretching in a bath, followed by drying. A method for producing acrylonitrile fiber for producing carbon fiber, further comprising drawing in steam. A component: Aminosilicone-based oil B component: Residual rate is 80% or more at 250 ° C. × 2 hours under heat treatment in air, and 10% at 500 ° C. × 5 minutes
The following heat-resistant resin C component: hygroscopic agent

(6) The carbon according to (5), wherein the component B is an aromatic complex ester having a heating residual rate of 10% or less after heat treatment at 500 ° C. in an inert gas atmosphere. A method for producing acrylonitrile fiber for producing fiber.

(7) The component (B) is an aromatic complex ester having a residual heat rate of 5% or less after heat treatment at 500 ° C. in an inert gas atmosphere. A method for producing acrylonitrile fiber for producing carbon fiber.

(8) The carbon fiber according to any one of the above (5) to (7), wherein the amount of the fiber oil comprising the components A, B and C is 0.1 to 1% by weight based on the fiber. A method for producing acrylonitrile fiber for production.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. In the present invention, the acrylonitrile fiber is a fiber from a homopolymer of acrylonitrile or a copolymer containing a small amount of a comonomer. Examples of the comonomer include acrylic acid, methacrylic acid, itaconic acid, and salts thereof. A copolymer obtained by copolymerizing 0.1 to 9.0% is preferably used.

In the present invention, as the aminosilicone oil agent of the component A, those widely known as sizing agents (oil agents) for acrylonitrile fibers for producing carbon fibers can be used.
In particular, those represented by the following structural formula (Formula 1) are more preferable than the focusing effect at the time of flame resistance.

[0025]

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[Component B] The component B has a residual ratio of 80% or more at 250 ° C. × 1 hour, and a residual ratio of 1 at 500 ° C. × 1 minute.
It is a heat-resistant resin of 0% by weight or less. Especially 250 ° C ~ 3
A resin that forms a film on the fiber surface at 00 ° C. Specifically, the resin satisfying such conditions is, for example, a high molecular weight composite ester. Particularly, an aromatic complex ester is preferable. Specifically, it is a compound mainly composed of an aromatic ester having the following structural formula (Formula 2). This is known from Japanese Patent Publication No. 9-809474.

[0027]

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In the present invention, the residual heating ratio is measured as follows. About 1 g of the resin is weighed and heat-treated at a predetermined temperature using a hot air circulation dryer or an electric furnace, and then weighed to obtain a residual ratio. However, the heating rate up to the predetermined temperature is 2
0 ° C./min. The heating residual amount of the component B used in the present invention by the above method is shown in Table 1 below.

[0029]

[Table 1]

The mixing ratio of the component B is 1 to 10 with respect to the component A.
And more preferably 1 to 5.

[Component C] The aminosilicone-based oil agent which is the component A is water-repellent. Therefore, when acrylonitrile fiber is subjected to steam drawing, the moisture content of the fiber becomes non-uniform, and the drawing process becomes non-uniform. There are inconveniences. For this reason,
It is preferred to add a hygroscopic component.

Examples of the moisture absorbing component include dioctyl sulfosuccinate Na salt, POE alkyl ether, alkylamine oxide and the like. In particular, dioctyl sulfosuccinate Na salt is preferred from the viewpoint of excellent moisture absorbing ability.

The mixing ratio of the moisture-absorbing component is 0.1% with respect to the component A.
A ratio of 1 to 2.0 is preferred, more preferably 0.1
０．５0.5.

In the present invention, by optimizing the mixing ratio of the A / B / C components, a precursor that can produce high-quality CF without lowering the CF productivity has been produced.

The ratio of the oil agent to the fiber is 0.1%.
To 1%, more preferably 0.15 to 0.5
%. If the amount of the oil agent is less than 0.1%, the convergence in the flame-proofing step is inferior, and the passability of the step after the corresponding step is significantly impaired. The amount of silicon nitride generated significantly increases, and the quality of the carbon fiber is significantly impaired.

[Production Method] The means for applying these oils to acrylonitrile fiber is as follows: wet spinning or spinning stock solution is once discharged into a gas, then introduced into a coagulation bath, stretched in the bath, and then subjected to the gel-like acrylonitrile fiber. Of the present invention. Thereafter, drying and drawing are performed to obtain carbon fiber precursor fibers. The usual oil agent application method is applied by immersing the gel fiber in an emulsion of a mixed oil agent. In the case of the present invention, an amino silicone oil agent (component A)
Since the bath temperature is preferably 40 ° C. or less and the solution stability of the component B is preferably 10 ° C. or more from the characteristics of the above, the temperature at which the oil agent is applied is in the range of 10 to 40 ° C. When the temperature is lower than 10 ° C., layer separation and migration of the solution are apt to occur, causing non-uniform adhesion to the fiber. On the other hand, when the temperature exceeds 40 ° C., the micelles of the emulsion are broken, and scum tends to be generated in the solution. The physical properties of the precursor fiber obtained in this way satisfy the physical properties necessary for obtaining good carbon fibers as shown below.

Fineness: 0.3 to 1.5 d Strength: 7 g / d or more Elongation: 11% or more X-ray orientation degree: 90% or more

For the production of carbon fiber using the acrylonitrile fiber of the present invention, a commonly employed method can be employed. That is, after flame resistance at 200 to 300 ° C. in air,
After carbonization at 300 to 2000 ° C. in an inert gas and surface treatment, a sizing agent is applied to obtain carbon fibers. The obtained carbon fibers exhibit good physical properties and good handling properties, and can be manufactured to satisfy the object of the present invention.

[0039]

The present invention will be described below more specifically with reference to examples. In the examples, the amount of oils and fats adhered, the bundling property of the oxidized yarn, the amount of fluff of carbon fibers, and the amount of silicon nitride generated in the carbonization step were according to the following methods.

(1) Amount of attached fats and oils After extracting an oil agent from acrylonitrile fiber for producing carbon fiber with a mixed solution of ethanol and benzene, the solution containing the oil agent is dried, and the obtained solid is weighed. .

(2) Bundleability of Flame-Retardant Yarn After acrylonitrile fiber bundles (12,000 single fibers) for carbon fiber production were made to be flame-resistant at 250 ° C. in the air, the fiber bundle was cut into 3 mm and about 100 cc. Put in acetone,
After applying ultrasonic waves for 1 minute to disperse, the number of adhered monofilaments is measured using a microscope. The convergence is evaluated based on Table 2 below.

[0042]

[Table 2]

(3) Fuzz amount of carbon fiber A sized carbon fiber strand is coated with a urethane sponge (dimensions 32 mm x 64 mm x 10 mm, weight about 0.2
5g) sandwiched between the two pieces, put a weight of 125g over the entire surface of the urethane sponge, and let the weight of the fuzz adhering to the sponge when the carbon fiber strand pass at a speed of 15m / min for 2 minutes be the fluff quantity. did.

(4) Amount of Si Compound Generated in Carbonization Step The Si compounds generated in each of the flame-proofing step and the carbonization step were collected, and the weight of the Si compound generated per ton of acrylonitrile fiber was measured to determine the amount generated. .

[0045]

Example 1 After the acrylonitrile polymer was wet-spun, washed with water and stretched in a bath, the water-swelled fiber bundle was treated as A.
Ingredient (amino silicone Takemoto Yushi Co., Ltd. BS-
379), 7 g / l, C component (dioctyl sulfosuccinate) 3 g / l, B component (aromatic complex ester)
After immersion in an emulsion solution containing 10 g / l of Matsumoto Yushi Co., Ltd., 10 g / l, it was dried, densified, and steam-stretched to obtain a fiber having a water content of 38%. 250 of this fiber
After oxidization at 1400C, carbonization was performed in nitrogen at 1400C to obtain carbon fibers. Table 3 shows the evaluation of the obtained carbon fibers.

[0046]

Example 2 A carbon fiber was obtained in the same manner as in Example 1 except that the amount of oil applied was changed to 0.70. Table 3 shows the evaluation of the obtained carbon fibers.

[0047]

EXAMPLE 3 The oil component A of Example 1 was used in an amount of 7 g /
Carbon fibers were obtained in the same manner as in Example 1 except that the components 1 and C were 7 g / l and the component B was 6 g / l. Table 3 shows the evaluation of the obtained carbon fibers.

[0048]

Comparative Example A carbon fiber was obtained in the same manner as in Example 1 except that the composition of the oil and the amount of the oil applied were as shown in Table 1. Tables 3 and 4 show the evaluation of the obtained carbon fibers.

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

According to the present invention, it is possible to reduce the amount of the aminosilicone-based oil agent adhering to the fibers. As a result, it is possible to reduce the amount of silicon oxide and silicon nitride generated in the CF process, and to obtain high strength. And a carbon fiber excellent in handleability can be obtained. According to the present invention, in the flameproofing step of the carbon fiber manufacturing process, A
The fiber bundle is bundled by the interaction between the amino silicone oil agent of the component and the heat-resistant resin of the component B, smoothly passes through the process, and in the carbonization process in a higher temperature inert gas, the heat-resistant resin of the component B is The fibers in the process are rapidly decomposed and are bunched by the bunching action of only the aminosilicone-based oil agent.

As a result, even if the amount of the aminosilicone oil agent applied to the acrylonitrile fiber is smaller than that in the case where the acrylonitrile fiber is applied alone, the focusing effect of the carbonization step can be obtained, and as a result, the amount of the silicon compound generated can be reduced Thus, the carbonization process can be continuously operated for a long period of time.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L033 AA05 AB01 AC05 BA28 BA29 CA59 4L035 BB03 BB60 BB61 BB66 BB69 BB80 BB85 FF01 MB03 MB04 MB06 4L037 CS03 PA53 PA55 PA67 PA69 PA70 PC05 PF29 PF32 PF45 PF52 PS02 UA

Claims (8)

[Claims] An acrylonitrile fiber for producing carbon fiber, wherein a fiber oil containing the following components A, B and C is adhered in an amount of 0.05 to 1% by weight based on the total fiber weight. A component: aminosilicone oil B component: heat-resistant resin whose heat treatment condition in air is 250 ° C. × 2 hours and residue is 80% or more and 500 ° C. × 5 minutes and residue is 10% or less C component: hygroscopic agent 2. The acrylonitrile fiber for producing carbon fiber according to claim 1, wherein the compounding ratio of the component A and the component B of the fiber oil component is in a range represented by the following formula (1). B / A = 1 to 10 (1) 3. The component B is an aromatic complex ester derivative having a residual heat amount of 80% or more after heating at 250 ° C. in air and having a liquid film-forming ability on the fiber surface. The acrylonitrile fiber for producing carbon fiber according to claim 1 or claim 2. 4. The acrylonitrile fiber for producing carbon fiber according to claim 3, wherein the component C is dioctyl sulfosuccinate. 5. A fiber obtained by spinning an acrylonitrile polymer solution and drawing in a bath is provided with an emulsion of a fiber oil containing the following components A, B and C, dried, and then dried. And a method for producing acrylonitrile fiber for producing carbon fiber. A component: Aminosilicone-based oil B component: Residual rate is 80% or more at 250 ° C. × 2 hours under heat treatment in air, and 10% at 500 ° C. × 5 minutes
The following heat-resistant resin C component: hygroscopic agent 6. The carbon fiber production method according to claim 5, wherein the component B is an aromatic complex ester having a heating residual ratio of 10% or less after heat treatment at 500 ° C. in an inert gas atmosphere. A method for producing acrylonitrile fiber. 7. The carbon fiber production according to claim 5, wherein the component B is an aromatic complex ester having a residual heat rate of 5% or less after heat treatment at 500 ° C. in an inert gas atmosphere. Of producing acrylonitrile fiber for use. 8. The acrylonitrile for carbon fiber production according to claim 5, wherein the amount of the fiber oil agent comprising the components A, B and C is 0.1 to 1% by weight based on the fiber. Fiber manufacturing method.