JPS5936727A - Preparation of carbon fiber - Google Patents

Abstract

PURPOSE:To improve the operating stability in the calcination step and obtain carbon fibers having high quality, particularly improved mechanical characteristics, by applying a specific oiling agent for yarns to organic polymer fiber yarns, opening and interlacing the oiled fiber yarns, flameproofing the resultant yarns, and carbonizing the flameproofed yarns. CONSTITUTION:An oiling agent for yarn, consisting of (A) (i) a >=18C higher alcohol type oiling agent, e.g. stearyl alcohol (EO)n, and/or (ii) a higher fatty acid type oiling agent, e.g. stearic acid glyceride, and (B) an organic type antioxidant, e.g. di(nonylphenyl)dinonyl phenyl phosphite, and having >=200 deg.C heat resistance is applied to organic type polymer fiber yarns, e.g. acrylic fibers, by the dipping method, etc. The oiled organic polymer fiber yarns are then dried, opened, interlaced under tension by the air jetting method, flameproofed and carbonized to give the aimed carbon fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing carbon fibers.
Stabilization of operation during total firing of organic polymer fiber yarn L &
, L-sized, high quality! The present invention relates to a method for producing carbon fibers having extremely high mechanical properties.

Due to its excellent mechanical, chemical, and electrical properties, carbon fiber is widely used in a variety of applications, including aerospace structural materials such as aircraft and rockets, and sports equipment such as tennis rackets, golf shafts, and fishing rods. Furthermore, it is expected to be used in fields such as transportation machinery applications such as ships and automobiles.

The fiber materials that are the raw materials for manufacturing such carbon fibers, that is, precursors, include cellulose fibers, acrylic fibers,
Polyvinyl alcohol fibers are used, and these precursors are made into carbon fibers through a process of flameproofing in an oxidizing atmosphere of 200 to 400°C and then carbonization at a high temperature of at least 800°C in an inert atmosphere. It is well known that it can be converted.

The precursor, which has been made flame resistant under such severe conditions and then carbonized, is likely to generate heat during firing, especially in the case of 45 degrees of flame treatment on one side. Not only can this cause fusion between fibers, or the raw yarn oil applied to the precursor cools, causing fuzz and single yarn breakage, impairing stable operation, but also heat treatment in an inert atmosphere. Therefore, various attempts have been made to avoid this problem. It is said that flame-retardant treatment of an acrylic precursor impregnated with a silicone-based compound can prevent fusion of single filaments during flame-retardation and improve the mechanical properties of carbon fibers. It is highly water-based, and the precursor to which it has been applied tends to cause static electricity damage, and has poor convergence.In the flame-retardant process described above, poor convergence of the precursor can cause single yarns to be wrapped around guides, rollers, etc., fuzz, and single yarn breakage. was there.

The present inventors have previously developed a higher alcohol-based oil having at least 18 carbon atoms and/or a raw material oil for producing carbon fibers.
or consisting of a higher fatty acid oil and an organic antioxidant,
A raw yarn oil having a heat resistance of at least 200°C is particularly effective against fusion between single yarns, fuzz, yarn breakage, etc. (f-
It has been found and proposed that the mechanical properties of the carbon fibers can be improved while reducing the carbon fibers.

However, as a result of further studies on improving the quality of carbon fibers, especially on further improving their mechanical properties, we found that the focusing state of precursors, in other words, the opening state, is an important factor that affects the mechanical properties of carbon fibers. After discovering this, they conducted extensive research and came up with the present invention.

That is, an object of the present invention is to provide a method for producing carbon fiber of high quality, particularly excellent mechanical properties, and another object of the present invention is to improve the operational stability in the firing process of the precursor to which the raw fiber oil has been applied, The object of the present invention is to provide a method for manufacturing carbon fiber with high production efficiency.

Such an object of the present invention is to add a higher alcohol type having at least 18 carbon atoms and/or
Or, a raw yarn oil consisting of a higher fatty acid oil and an organic antioxidant and having a heat resistance of at least 200°C is given (=j),
This can be achieved by a method for producing carbon fiber, which is characterized in that the yarn is opened and entangled under tension by an air injection method, made flame resistant, and then carbonized.

The precursor used in the present invention is effective against organic precursors such as cellulose, acrylic, and polyvinyl alcohol fibers, which tend to accumulate heat and become brittle during the firing process, especially the flameproofing process, but acrylic fibers are preferably used.
．． & ill.

These precursors are usually single yarn Denny) with a thickness of 0,5~
2. Od, the number of single yarns used is within the range of 500 to 30,000.

The raw yarn for producing carbon fibers is exposed to a high-temperature heating atmosphere of at least 200° C. in the flaming process.

By heating at this high temperature, the yarn is converted into flame-resistant fiber through complex chemical reactions such as intermolecular crosslinking and intramolecular cyclization. It is unavoidable that partial melting and tar formation as the reaction progresses causes fusion between the single filaments and the formation of defects in the fibers. The occurrence of inter-fiber fusion caps and fiber defects during the initial high-temperature heating of the raw yarn varies markedly depending on the type of oil attached to the yarn. When it is decomposed, it cannot be expected to be effective in preventing the occurrence of such fusion and fiber defects, and on the contrary, it does not have any adverse effects.

In the oil agent of the present invention, when the number of carbon atoms in the higher alcohol-based and/or higher fatty acid-based oil agent, which is the main component of the oil agent, is less than 18, the oil agent penetrates into the yarn significantly.
The number of carbon atoms should be at least 18, preferably 18 to 25, since this may reduce the fusion prevention effect and cause deterioration of the physical properties of the carbon fibers, especially the generation of defects in the carbon fibers.

Examples of such oils of the present invention include higher alcohol-based oils such as stearyl alcohol phosphate ester salt and ethylene oxide [(EO)n].
Examples include stearyl alcohol (EO) n, oleyl alcohol (EO) n, behenyl alcohol (EO) n, inpentacosanyl alcohol (E'O) n, etc., in which the n number is about 20 to 40. However, stearyl alcohol (EO) n1 oleyl alcohol (EO)
'n', inopentacozanyl alcohol (EO) n, etc. are preferably used. Two or more of these oil agents may be used in combination. In addition, as a higher fatty acid oil,
For example, stearic acid chrycerite or polyethylene glycol (P E O) molecule J1;- is 400
-1000, such as PEG stearate, PEG olate, PEG sorbitan oleate, and PEG sorbitan stearate, and in particular, PEG stearate (PE, G stearate), 'PEG PE-t, etc. are preferably used. Note that two or more of these oil agents may be used in combination.

Furthermore, the heat resistance of typical higher alcohol-based oils and deferred fatty acid-based oils is shown in Table 1.

Table 1 Here, heat resistance refers to the weight of the oil agent (solid content) obtained from the weight loss curve obtained when 1 omp of the oil agent as solid content is taken into a thermobalance device and heated at a heating rate of 2.5°C/min. It refers to the temperature when the weight loss rate based on the weight loss rate is 5%.

Next, the organic antioxidant to be used in combination with the higher alcohol-based and higher fatty acid-based oils must be compatible with the higher alcohol-based and higher fatty acid-based oils, and reduce their heat resistance. By cooling both to 200°C, it is necessary to withstand the initial heating for making the yarn flame resistant, and at the same time, to make the yarn flame resistant, it must be easily thermally decomposed and volatilized and not remain in the yarn as a heating residue. be.

Examples of such antioxidants include 4,4'-butylidene bis(6-methyl-6-tert-butylphenol);
4,4'-thio-bis(3-methyl-6-tert-butylphe, nor), bis(2,2,6,6-tetramethyl-
4-piperidine) sebacate, tetrakis [methylene-
3(3゜57'iJrtriphthyl-4-]-idroxyphenyl)propionate]methane, di(nonylphenyl) dinonylphenyl phosphite are preferably used, and two or more types can also be used in combination.

The amount of antioxidant added to the higher alcohol-based and/or higher fatty acid-based oil is preferably within the range of 1 to 20% by weight per 80 to 99% by weight of the oil. If it is less than 1%, the heat resistance effect will not be sufficient;
If it exceeds 0, the antioxidant may remain as a heating residue on flameproofing or carbon fibers, which is undesirable. It is necessary that this raw fiber oil has a heat resistance of at least 200°C, and if it is insufficient to 200°C, it is inevitable that the physical properties of the flame-resistant fibers and carbonized fibers will deteriorate. The heat resistance of the yarn oil agent of the present invention is usually 200 to 300°C.

As a bath adjustment method for the raw yarn oil agent, a known oil agent bath adjustment method may be applied. The bath may be applied to the precursor by a dipping method, a method of applying with a roller, a method of spraying the bath, etc., but the dipping method is preferable from the viewpoint of uniform adhesion.

After the precursor is treated in an oil bath, it is dried by a known method. The amount of adhesion usually depends on the weight of the fiber.
High alcohol-based oils, which range from about 1 to 6%.
The present invention is not particularly limited by the type of higher fatty acid-based compound and the type of organic antioxidant.The present invention involves applying the raw fiber oil to the precursor, drying it, and then opening it by an air injection method. During the opening and entangling process, the substantially untwisted precursor paper to which the raw yarn oil has been adhered is continuously inserted into a long-shaped air nozzle having 3 to 10 blowing holes. It is preferable to run the vehicle in a consistent manner. At this time, the running precursor must be under tension, at least o, 1g/d.
It is preferable to apply a tension of 0.1 to 3 g/d. If the tension is not strong enough, uneven opening will occur and the single yarns will become entangled more than necessary.
This will cause thread breakage. In addition, if the tension is too strong, uneven opening will occur, and the interlacing of the single yarns will be insufficient. The total pressure used for the air injection process is 1
~2 Ky/cni is usually used, and each single yarn of the yarn subjected to such air treatment is completely opened and further intertwined and intertwined. As the single yarns are intertwined, the yarn has a cohesive property.

In the present invention, the oCF value, which indicates the degree of intertwining of the yarns, is usually preferably 20 to 40. , processing time, etc., and these conditions may be selected as appropriate to meet the purpose of the present invention. When the CF value is lower than 20, there is little entanglement and the cohesiveness is insufficient, and when it exceeds 40, filament defects such as single fiber breakage tend to occur and the fiber properties tend to deteriorate.

(Method for measuring CF value) One end of a fiber with a length of about 100 m is fixed at the upper end of the property damage in meters, and a weight of grams equal to 0.2 times the denier of the fiber is lowered to the lower end (however, the weight is 500 m). (If the denier exceeds 100t).0.5 to 1 below the fixed point
．． At least 1 of the total number of filaments on the property of 0 cm
Separate the yarn so that A is on one side and insert the hook. This hook should have a weight in grams equal to five times the single yarn denier. Let the hook fall until it is caught on the thread, and read the distance from the starting point of separation to the stationary point.

Repeat this test 100 times with different samples, omitting the upper and lower 20% of L, and use the remaining average value as the representative value M of the sample.

The CF value is the value obtained by dividing 100 by the value of M in units of m.

In the present invention, a raw yarn oil is applied to the precursor, then a live air injection treatment is applied, and then a heat treatment is performed, which is particularly effective against static electricity damage, fusion, fuzz, yarn breakage, etc. in the production of acrylic carbon fibers. Carbon fibers that exhibit excellent effects and have high mechanical properties can be obtained.

By using such air injection treatment, it is possible to further enhance the effect of reducing fusion, fuzz, yarn breakage, etc. in the firing process, which the raw fiber oil has, and to improve the mechanical properties of carbon fibers. The air injection treatment improves the opening properties between the single yarns of the precursor.

It is thought that by eliminating the cohesive fusion that occurs in the fibers, fusion can be prevented from occurring during the firing process, especially during the flame-retardant process, and the flame-resistance of each single yarn can proceed evenly.

In the present invention, fusion refers to a state in which a single yarn softens and adheres to an adjacent single yarn, and the bonded boundary part is planar or the bonded boundary disappears. This means that the single yarns are bonded together due to softening of the single yarns or due to solvents, oils, etc., and the bonded boundaries are dotted.

The precursor that has been subjected to the yarn oil adhesion treatment and the air injection treatment is then subjected to flameproofing treatment in an oxidizing atmosphere within the range of 200 to 400°C, and is further subjected to flameproofing treatment in an inert atmosphere at at least 800°C, for example in nitrogen gas. A known method is used for these flameproofing and carbonization treatments.

According to the present invention, it is possible to prevent troubles such as fusion, fuzz, and thread breakage during the flameproofing or carbonization process, and to manufacture carbon fibers with high productivity. It also has remarkable effects, such as the ability to obtain high-strength carbon fibers.

The present invention will be specifically explained below with reference to Examples.0 Example 1, Comparative Example 1 Acrylonitrile 99.5 m01%, itaconic acid [
], 5 mo1%, was polymerized by a solution polymerization method using dimethyl sulfoxide as a solvent, and a spinning stock solution with a stock solution concentration of 22% was used, after which it was spun into a dimethyl sulfoxide aqueous solution, washed with water and stretched by a known method to obtain a 6000 denier, A raw yarn of 6,000 filaments was obtained. This drawn yarn was mixed with 95% by weight of stearyl alcohol (EO) and di(
nonylphenyl) sifnylphenyl phosphite 5
Raw yarn oil agent consisting of % by weight (heat resistance was 210°C)
8.5% aqueous solution and dried to a strength of 6.3f.
/d acrylic fiber filament was obtained. The amount of oil attached was 1.9% based on the weight of the raw yarn.

Next, this raw yarn, without twisting, was continuously passed through a 20 mm diameter live air injection nozzle. The yarn speed at this time was 3Tn/min.
The thread tension is 0.15y-/d, and the air pressure is still '-
2Kf/art was used.

Furthermore, this yarn is continued in 3. Flameproofing treatment was carried out at a temperature of 240 to 260° C. for 60 minutes at a yarn speed of Q m 7 minutes, and then carbonization treatment was performed at a temperature of 1500° C. in a nitrogen atmosphere to obtain a carbonized yarn.

A resin-impregnated strand was made from this carbonized yarn based on JIS R-7601 and its tensile strength was measured.

As a comparative example, the same procedure as in Example 1 was carried out except that the live air injection treatment was not performed.

The results are shown in Table 2.

Table 2 Examples 2 to 6, Comparative Example 2 The same treatment as in Example 1 was carried out except that the blending ratio or combination of the oil agent and the organic antioxidant was changed. The results are shown in Table 6.

Incidentally, in each of the Examples, no aggregated fusion of the flame-resistant yarn was observed, but in the Comparative Example, a considerable amount of aggregated fusion was observed.

Margin below Table 6 Examples 7 to 8, Comparative Examples 6 to 5 Processed in the same manner as in Example 1, except that the air pressure in air injection was changed as shown in Table 4 and the CF value was changed, and resin impregnation was performed. The strength of the strands was measured.

The results are shown in Table 4.

Table 4 Patent Applicant Toshi Co., Ltd. Company Procedures
Amendment (Method) Shoga Ro Momme
Date: Ij, l Kazuo Wakasugi, Commissioner of the Japan Patent Office 1 Indication of the matter 1987 Patent Application No. 148098 2 Name of the invention Relationship to the case of the person who amends the method for manufacturing carbon fiber 5 Patent application Person place
2-2-4 Muromachi, Nihonbashi, Chuo-ku, Tokyo Date of amendment order 1980 llJ:13o (shipment date) 5, Number of inventions increased by amendment None 6 Detailed explanation of one invention in the amended χJ specification Contents of the amendment In the column ``1-Table 1 on page 8'' in the details page 4 (1), as shown in the attached sheet, amend the contents of the amendment in the following table.

[ ” Quiet Humidity 1 ” Anzu 1 1 1 Page 17, Table 1, Table 2 has been corrected as shown in the following table.

3) Correct the [-Crow 53 Table] for elementary school students, 18 degrees, in the next table) 11.

Table 3 14) "Table 4" on page 19 is amended as shown in the following table.

[ Ship, 4 tables

Claims (1)

[Claims] (1) The number of carbon atoms in the organic polymer fiber yarn is at least 1
Contains 8 higher alcohol-based and/or higher fatty acid-based oils and an organic antioxidant, and has a heat resistance of at least 200
A method for producing carbon fibers, which comprises applying a raw yarn oil at a temperature of 0.degree. Here, the heat resistance of an oil agent is determined by the weight loss curve obtained when 10 g of the oil agent as solid content is sampled into a thermobalance device and heated at a heating rate of 2.5°C/min. This is the temperature when the weight loss rate is 5 Yu. (2. The method for producing carbon fibers according to claim 1, wherein the degree of entanglement of the threads by opening and entangling treatment is 20 to 40 as a CF value.