JP2001279566A - Carbon fiber felt for electrode material and method for producing the same - Google Patents
Carbon fiber felt for electrode material and method for producing the sameInfo
- Publication number
- JP2001279566A JP2001279566A JP2000090261A JP2000090261A JP2001279566A JP 2001279566 A JP2001279566 A JP 2001279566A JP 2000090261 A JP2000090261 A JP 2000090261A JP 2000090261 A JP2000090261 A JP 2000090261A JP 2001279566 A JP2001279566 A JP 2001279566A
- Authority
- JP
- Japan
- Prior art keywords
- carbon fiber
- felt
- fiber
- thickness
- fiber felt
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229920000049 Carbon (fiber) Polymers 0.000 title claims abstract description 179
- 239000004917 carbon fiber Substances 0.000 title claims abstract description 179
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 172
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 11
- 239000007772 electrode material Substances 0.000 title claims description 40
- 229920002239 polyacrylonitrile Polymers 0.000 claims abstract description 35
- 230000006835 compression Effects 0.000 claims abstract description 34
- 238000007906 compression Methods 0.000 claims abstract description 34
- 238000011084 recovery Methods 0.000 claims abstract description 23
- 239000000835 fiber Substances 0.000 claims description 234
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 34
- 239000001301 oxygen Substances 0.000 claims description 34
- 229910052760 oxygen Inorganic materials 0.000 claims description 34
- 239000013078 crystal Substances 0.000 claims description 22
- 230000006837 decompression Effects 0.000 claims description 6
- 238000004080 punching Methods 0.000 claims description 3
- 238000002788 crimping Methods 0.000 claims description 2
- BNOODXBBXFZASF-UHFFFAOYSA-N [Na].[S] Chemical compound [Na].[S] BNOODXBBXFZASF-UHFFFAOYSA-N 0.000 abstract description 22
- 230000003647 oxidation Effects 0.000 abstract description 11
- 238000007254 oxidation reaction Methods 0.000 abstract description 11
- 239000000463 material Substances 0.000 abstract description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 54
- 238000012545 processing Methods 0.000 description 35
- 229910052757 nitrogen Inorganic materials 0.000 description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 27
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical compound COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 description 22
- 238000010304 firing Methods 0.000 description 21
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 19
- 230000007423 decrease Effects 0.000 description 17
- 230000005484 gravity Effects 0.000 description 17
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 13
- 238000007599 discharging Methods 0.000 description 13
- 239000007921 spray Substances 0.000 description 13
- 229910052717 sulfur Inorganic materials 0.000 description 13
- 239000011593 sulfur Substances 0.000 description 13
- 239000003792 electrolyte Substances 0.000 description 12
- 238000000034 method Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 230000035699 permeability Effects 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 238000003763 carbonization Methods 0.000 description 7
- 239000011261 inert gas Substances 0.000 description 7
- 239000000919 ceramic Substances 0.000 description 6
- 238000009950 felting Methods 0.000 description 5
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- 230000000877 morphologic effect Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 2
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000010000 carbonizing Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 101100321669 Fagopyrum esculentum FA02 gene Proteins 0.000 description 1
- 101001062854 Rattus norvegicus Fatty acid-binding protein 5 Proteins 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000012681 fiber drawing Methods 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- 238000004736 wide-angle X-ray diffraction Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical Or Physical Treatment Of Fibers (AREA)
- Inorganic Fibers (AREA)
- Nonwoven Fabrics (AREA)
- Secondary Cells (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は電極材用炭素繊維フ
ェルトに関し、更に詳述すれば、形態安定性に優れ、し
かも厚さ方向の通電抵抗及び液透過抵抗の低いポリアク
リロニトリル系炭素繊維フェルトに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber felt for an electrode material, and more particularly, to a polyacrylonitrile-based carbon fiber felt which is excellent in form stability and has low current-flow resistance and liquid permeation resistance in the thickness direction. .
【０００２】[0002]
【従来の技術】従来、ナトリウム−硫黄電池などの二次
電池の充放電効率の向上を図る目的で、電極材として炭
素繊維フェルトを用いることは知られている。2. Description of the Related Art Conventionally, it has been known to use carbon fiber felt as an electrode material for the purpose of improving the charge / discharge efficiency of a secondary battery such as a sodium-sulfur battery.
【０００３】この炭素繊維フェルト電極材は、ポリアク
リロニトリル系繊維、セルロ−ズ繊維、ピッチ繊維など
の有機繊維を用いて製造している。[0003] The carbon fiber felt electrode material is manufactured using organic fibers such as polyacrylonitrile fiber, cellulosic fiber and pitch fiber.
【０００４】炭素繊維は高い導電性を有し、繊維直径が
０．５〜３０μｍと微細であり、電気エネルギ−の伝達
効率に優れているので、今後各種分野、特に電極材分野
への応用が期待されている。[0004] Since carbon fibers have high conductivity, a fine fiber diameter of 0.5 to 30 µm, and excellent electric energy transmission efficiency, carbon fibers are expected to be applied to various fields, especially electrode materials in the future. Expected.
【０００５】特に炭素繊維フェルトを電極材へ適用する
ためには、下記の項目が重要な要件になる。 （１）通電方向の電気抵抗値（比抵抗値）が低いこと。 （２）電池への装着時および電池作動時の変形が少な
く、賦形性に優れていること。 （３）単電池内部壁面への密着性に優れていること。 （４）単電池内の他の材料に過度な応力が加わらない材
料であること。 （５）単電池作動時の電解質の流れが円滑であること。[0005] In particular, in order to apply carbon fiber felt to an electrode material, the following items are important requirements. (1) The electric resistance value (specific resistance value) in the direction of conduction is low. (2) Deformation during mounting on the battery and operation of the battery is small, and the shapeability is excellent. (3) Excellent adhesion to the inner wall surface of the cell. (4) Materials that do not apply excessive stress to other materials in the cell. (5) The flow of the electrolyte during the operation of the unit cell is smooth.
【０００６】上記要件のうち、（１）のフェルト構造体
としての比抵抗値を低下させるためには、焼成温度、繊
維表面酸化度、および繊維の配列度の適正化が必要であ
る。Of the above requirements, in order to lower the specific resistance of the felt structure of (1), it is necessary to optimize the firing temperature, the degree of fiber surface oxidation, and the degree of fiber arrangement.
【０００７】上記要件のうち、（２）の変形の少ない炭
素繊維フェルトを得る為には、用いる単繊維の剛直性を
向上させると共に、フェルト加工時の加工条件を適正化
することにより、繊維配列度を制御する必要がある。Of the above requirements, in order to obtain the carbon fiber felt with little deformation described in (2), the rigidity of the single fiber used is improved and the processing conditions at the time of felt processing are optimized to obtain a fiber arrangement. You need to control the degree.
【０００８】上記要件のうち、（５）の単電池作動時の
電解質の流れを円滑にさせるためには、単繊維の太さお
よび前述した繊維配列度を制御する必要がある。[0008] Of the above requirements, it is necessary to control the thickness of the single fiber and the degree of fiber arrangement described above in order to smooth the flow of the electrolyte during the operation of the single cell of (5).
【０００９】例えば、ナトリウム−硫黄電池用の電極材
用炭素繊維フェルトとしては、厚さ方向の配向度を高く
する事によって、電池の内部抵抗が低くなり、電池の出
力が向上することが、例えば特開平７−３２６３８４
号、同３−１４５０６９号、同３−１４５０６９号等に
おいて報告されている。For example, as a carbon fiber felt for an electrode material for a sodium-sulfur battery, increasing the degree of orientation in the thickness direction lowers the internal resistance of the battery and improves the output of the battery. JP-A-7-326384
And Nos. 3-145069 and 3-145069.
【００１０】これらの既知の発明において開示される電
極材は、有機繊維を円筒状に形成し、焼成工程を経て円
筒状の電極材用炭素繊維フェルトを製造している。In the electrode materials disclosed in these known inventions, organic fibers are formed into a cylindrical shape, and a cylindrical carbon fiber felt for an electrode material is manufactured through a firing step.
【００１１】このような工程による場合は、円筒状とい
う形態的特性に起因して自己支持性が高くなり、形態安
定性が優れる反面、有機繊維の焼成時の収縮によって炭
素繊維フェルトが緻密なものとなり、その結果フェルト
の通液抵抗が高くなる。According to such a process, the self-supporting property is enhanced due to the morphological characteristics of the cylindrical shape, and the morphological stability is excellent, but the carbon fiber felt is dense due to shrinkage during firing of the organic fibers. As a result, the flow resistance of the felt increases.
【００１２】また、焼成時の反応熱や熱分解物の除去、
及び加熱処理を均一に行う必要性があることから緩慢な
熱処理を行う必要があり、その結果焼成に長時間を要す
るという作業上の問題点がある。[0012] Further, removal of heat of reaction and pyrolysis products during firing,
In addition, since it is necessary to perform the heat treatment uniformly, it is necessary to perform a slow heat treatment, and as a result, there is a problem in that a long time is required for firing.
【００１３】一方、アクリロニトリル系繊維を耐炎化処
理(酸化処理）した後、フェルト加工し、その後更に炭
素化処理する方法も知られている（特開平２−１３９４
６４号、同１１−１５８７３７号公報）。On the other hand, a method is also known in which acrylonitrile-based fibers are subjected to a flame-resistant treatment (oxidation treatment), then felted, and then further subjected to a carbonization treatment (JP-A-2-1394).
No. 64 and No. 11-158737).
【００１４】特開平２−１３９４６４号公報において
は、酸化処理された後の所謂アクリロニトリル系酸化繊
維をフェルト加工し、更に不活性雰囲気中３００〜９０
０℃に５００℃／分以下、９００℃〜最高温度に１００
０℃／分以下の昇温条件で処理し後、更に不活性雰囲気
下で最高温度１８００℃以上で１分間以上処理する方法
が提案されている。In Japanese Patent Application Laid-Open No. 2-139464, a so-called acrylonitrile-based oxidized fiber which has been subjected to an oxidizing treatment is subjected to felt processing, and further subjected to a 300-90
500 ° C / min or less at 0 ° C, 100 ° C at the maximum temperature of 900 ° C
A method has been proposed in which a treatment is carried out at a temperature raising condition of 0 ° C./min or less, and then a treatment is carried out in an inert atmosphere at a maximum temperature of 1800 ° C. or more for 1 minute or more.
【００１５】しかし、この方法で製造された炭素繊維フ
ェルトは、寸法回復率で表示される形態安定性は高いも
のの、比抵抗値が０．４Ω・ｃｍ程度と高い。このよう
に、更に高性能の電池を製造するためには、より高い導
電性を有する電極材用炭素繊維フェルトを供給すること
が不可欠な要件になっている。However, the carbon fiber felt produced by this method has high morphological stability expressed by the dimensional recovery rate, but has a high specific resistance of about 0.4 Ω · cm. As described above, in order to manufacture a battery with higher performance, it is an essential requirement to supply a carbon fiber felt for an electrode material having higher conductivity.
【００１６】特開平１１−１５８７３７号公報には、ア
クリロニトリル系耐炎化繊維を含む前駆体フェルトを１
１００〜１５００℃の温度領域で炭素化処理する方法、
及びこのような方法によって比抵抗値を０．５Ω・ｃｍ
以下とする技術が記載されている。Japanese Patent Application Laid-Open No. 11-158737 discloses that a precursor felt containing an acrylonitrile-based oxidized fiber is made of one felt.
A method of carbonizing in a temperature range of 100 to 1500 ° C.,
And a specific resistance value of 0.5 Ω · cm by such a method.
The following technologies are described.
【００１７】しかしながら、この公報の実施例に記載さ
れた炭素繊維フェルトの比抵抗値は最小値で０．３８Ω
・ｃｍであり、この値は電極材用炭素繊維フェルトとし
て満足できるものではない。However, the specific resistance of the carbon fiber felt described in the examples of this publication is 0.38 Ω at the minimum.
Cm, which is not satisfactory as a carbon fiber felt for electrode materials.
【００１８】電極材用炭素繊維フェルトは、セラミック
等の電極用枠体に装着されて電池用電極材として使用す
るが、この際炭素繊維フェルトが形態安定性を備えてい
ることが重要である。即ち、電極用枠体に装着する際、
炭素繊維フェルトは加圧圧縮され、枠体に装着後圧力が
解除される事によって枠体内に安定に装着・固定される
形式を採っている。このため、圧縮圧解除後の復元性
と、枠内における形態維持性および流体の通過に起因す
る経時変化の安定性等が重要である。The carbon fiber felt for an electrode material is mounted on an electrode frame made of ceramic or the like and used as an electrode material for a battery. At this time, it is important that the carbon fiber felt has form stability. That is, when mounting on the electrode frame,
The carbon fiber felt is pressurized and compressed, and after being mounted on the frame, the pressure is released, so that the carbon fiber felt is stably mounted and fixed in the frame. For this reason, the resilience after the compression pressure is released, the shape retention in the frame, the stability of the temporal change due to the passage of the fluid, and the like are important.
【００１９】炭素繊維フェルトの形態が前記した先行文
献に記載してあるような、円筒状であれば、即ち電池構
造が同心円構造であれば、炭素繊維フェルトの形態は比
較的安定している。When the form of the carbon fiber felt is cylindrical as described in the above-mentioned prior art document, that is, when the battery structure is a concentric structure, the form of the carbon fiber felt is relatively stable.
【００２０】ところで、ナトリウムー硫黄電池等の二次
電池は、電極材面積が大きいほど大容量の充放電に適し
たものになる。A secondary battery such as a sodium-sulfur battery is suitable for large-capacity charging and discharging as the electrode material area is larger.
【００２１】しかしながら、面積が大きな平面構造の炭
素繊維フェルトを電極材として使用する場合、電解液の
液圧によってフェルトに歪みが生じやすいので、この場
合は円筒形の炭素繊維フェルトより高い形態安定性が必
要である。However, when a carbon fiber felt having a large area and a planar structure is used as an electrode material, the felt tends to be distorted due to the liquid pressure of the electrolytic solution. In this case, the form stability is higher than that of the cylindrical carbon fiber felt. is necessary.
【００２２】さらに、電極材の炭素繊維フェルトは前述
のとおり、高い導電性が要求される。高い導電性と高い
形態安定性を維持するためには、高密度で繊維を充填す
る方法がある。しかし、このようにすると炭素繊維フェ
ルトの厚さ方向の通液性が低下するという問題がある。
また、充填の密度が高くなると弾力性が減少し、電極材
を枠体に装着するのが難しくなる問題がある。Further, as described above, the carbon fiber felt as the electrode material is required to have high conductivity. In order to maintain high conductivity and high form stability, there is a method of filling fibers at high density. However, this causes a problem that the liquid permeability in the thickness direction of the carbon fiber felt is reduced.
In addition, when the filling density increases, the elasticity decreases, and there is a problem that it is difficult to mount the electrode material on the frame.
【００２３】前記公報においては、電極材用炭素繊維フ
ェルトは、電池装着前に他の不織布またはフェルトと一
体化するため、厚さ方向にニ−ドルパンチ等で二次加工
する。In the above publication, the carbon fiber felt for an electrode material is subjected to secondary processing in the thickness direction with a needle punch or the like in order to integrate it with another nonwoven fabric or felt before mounting the battery.
【００２４】また二次加工したフェルト等は、電池装着
前に圧縮した後、電池内の所定の空隙に装着し、その後
常温〜４００℃の作動温度において使用する。この時フ
ェルトの厚さは、元の厚さにできるだけ復元し、電池の
枠体空隙が無い状態に充填されている必要がある。The secondary processed felt or the like is compressed before mounting the battery, then mounted in a predetermined space in the battery, and then used at an operating temperature of room temperature to 400 ° C. At this time, the thickness of the felt must be restored to the original thickness as much as possible, and the battery must be filled without any voids in the battery frame.
【００２５】厚さ方向の圧縮復元率が低い場合、炭素繊
維フェルトが電池に装着される際、および長期の電池作
動中に空隙が生じ、重要な電池性能である充放電効率の
低下を生じさせる。When the compression / restoration rate in the thickness direction is low, voids are generated when the carbon fiber felt is mounted on the battery and during long-term operation of the battery, which causes a reduction in charge / discharge efficiency, which is an important battery performance. .
【００２６】また、同様に炭素繊維フェルトの圧縮時の
反発力が低いと、長期間の電池作動中に空隙が生じ易
い。但し、復元力が高すぎると、例えばナトリウムー硫
黄電池に装着した場合、炭素繊維フェルトより内層部に
配置されているナトリウム内蔵用セラミック管に過度の
応力が加えられてセラミック管損傷の原因になる。Similarly, if the repulsion of the carbon fiber felt during compression is low, voids are likely to be formed during long-term battery operation. However, if the restoring force is too high, for example, when the battery is mounted on a sodium-sulfur battery, excessive stress is applied to the sodium built-in ceramic tube disposed in the inner layer portion from the carbon fiber felt, causing damage to the ceramic tube.
【００２７】[0027]
【発明が解決しようとする課題】本発明者等は、上記の
課題を解決するために種々検討した結果、本発明ポリア
クリロニトリル系炭素繊維フェルトは、厚さ方向の比抵
抗値、形態安定性等に優れ、これを電池用電極材に使用
する場合、単電池内部壁面への密着性、単電池内の他の
材料に加わる応力の度合い、及び電池作動時の電解質の
流れの円滑性等に優れ、更に有機繊維から炭素繊維への
焼成時間が短い等の電極材の製造方法に要求される利点
を備えていることを知得し、本発明を完成するに至った
ものである。The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, the polyacrylonitrile-based carbon fiber felt of the present invention has a specific resistance value in the thickness direction, shape stability and the like. When this is used as a battery electrode material, it has excellent adhesion to the inner wall of the cell, the degree of stress applied to other materials in the cell, and the smooth flow of electrolyte during battery operation. Further, the present invention has been found to have advantages required for a method of manufacturing an electrode material, such as a short firing time from organic fibers to carbon fibers, and has completed the present invention.
【００２８】従って、本発明の目的とするところは、上
記の課題を解決し、電池の電極材等の用途に用いて有用
な炭素繊維フェルト及びその製造方法を提供することに
ある。Accordingly, it is an object of the present invention to solve the above-mentioned problems and to provide a carbon fiber felt useful for use as an electrode material of a battery and a method for producing the same.
【００２９】[0029]
【課題を解決するための手段】上記の目的を達成する本
発明は、以下に記載するものである。The present invention that achieves the above objects is as described below.
【００３０】〔１〕 ポリアクリロニトリル系炭素繊維
からなり、圧縮前の厚さに対して、厚さを５０％圧縮時
の反発力が２〜４ｋｇ／ｃｍ2で、除圧後の厚さ復元率
が９８％以上、かつ炭素繊維フェルト厚さ方向の比抵抗
値が０．１１Ω・ｃｍ以下であることを特徴とする電極
材用炭素繊維フェルト。[1] The polyacrylonitrile-based carbon fiber has a rebound of 2 to 4 kg / cm 2 when the thickness is compressed to 50% of the thickness before compression, and the thickness recovery rate after decompression. Is 98% or more and the specific resistance in the thickness direction of the carbon fiber felt is 0.11 Ω · cm or less.
【００３１】〔２〕 ポリアクリロニトリル系炭素繊維
の表面酸素濃度Ｏ／Ｃが０．０８以下である〔１〕に記
載の電極材用炭素繊維フェルト。[2] The carbon fiber felt for an electrode material according to [1], wherein the surface oxygen concentration O / C of the polyacrylonitrile-based carbon fiber is 0.08 or less.
【００３２】〔３〕 ポリアクリロニトリル系炭素繊維
のＸ線結晶サイズ（Ｌｃ）が１．３ｎｍ以上、繊維直径
が６〜２０μｍである〔１〕に記載の電極材用炭素繊維
フェルト。[3] The carbon fiber felt for an electrode material according to [1], wherein the polyacrylonitrile-based carbon fiber has an X-ray crystal size (Lc) of at least 1.3 nm and a fiber diameter of 6 to 20 μm.
【００３３】〔４〕 炭素繊維フェルトの厚さ方向の繊
維配列度が３０〜８０％である〔１〕に記載の電極材用
炭素繊維フェルト。[4] The carbon fiber felt for an electrode material according to [1], wherein the degree of fiber arrangement in the thickness direction of the carbon fiber felt is 30 to 80%.
【００３４】〔５〕 下記工程（１）、（２）、
（３）、 （１）０．５７〜３．４０デシテックス（ｄｔｅｘ）
で、且つ繊維断面の真円度が０．８０〜１のポリアクリ
ロニトリル系繊維を空気中で酸化処理して酸化繊維とす
る、（２）酸化繊維をクリンプ処理した後、厚さ方向の
繊維配列度が３０〜８０％にニードルパンチし、酸化繊
維フェルトを作製する、（３）酸化繊維フェルトを不活
性ガス中、６００〜１３００℃で１〜１０分間処理後、
更に１７００℃以上の温度で０．５〜１０分間処理す
る、を含むことを特徴とする〔１〕乃至〔４〕の何れか
に記載の電極材用炭素繊維フェルトの製造方法。[5] The following steps (1) and (2)
(3), (1) 0.57 to 3.40 decitex (dtex)
The polyacrylonitrile fiber having a roundness of the fiber cross section of 0.80 to 1 is oxidized in the air to be oxidized fiber. (2) Fiber arrangement in the thickness direction after crimping the oxidized fiber (3) Treating the oxidized fiber felt in an inert gas at 600 to 1300 ° C for 1 to 10 minutes,
The method for producing a carbon fiber felt for an electrode material according to any one of [1] to [4], further comprising treating at a temperature of 1700 ° C. or more for 0.5 to 10 minutes.
【００３５】[0035]
【発明の実施の形態】（炭素繊維フェルト）本発明の電
極材用炭素繊維フェルトは、上記のようにポリアクリロ
ニトリル系炭素繊維からなり、圧縮前の厚さに対して、
厚さを５０％圧縮時の反発力が２〜４ｋｇ／ｃｍ2で、
除圧後の厚さ復元率が９８％以上、かつ炭素繊維フェル
ト厚さ方向の比抵抗値が０．１１Ω・ｃｍ以下のもので
ある。BEST MODE FOR CARRYING OUT THE INVENTION (Carbon fiber felt) The carbon fiber felt for an electrode material of the present invention is made of polyacrylonitrile-based carbon fiber as described above.
The repulsion force when compressing the thickness by 50% is 2-4 kg / cm 2 ,
The thickness recovery rate after depressurization is 98% or more, and the specific resistance in the carbon fiber felt thickness direction is 0.11 Ω · cm or less.
【００３６】本発明において、厚さ方向５０％加圧圧縮
時の反発力とは、炭素繊維フェルトを厚さ方向に圧縮し
たときの反発力である。この反発力が強いことは、電極
材として枠体に装着した際、空隙なく装着できることを
意味する。しかしこの反発力が強すぎると、電極材とし
ての作動時において、反発力や液圧の影響で枠体、セラ
ミック内装材等が破損する危険性を有する。このため反
発力は、後に説明する測定方法によって求められる値
で、２ｋｇ／ｃｍ2〜 ４ｋｇ／ｃｍ2の範囲が必要であ
る。In the present invention, the repulsive force at 50% compression in the thickness direction is the repulsion force when the carbon fiber felt is compressed in the thickness direction. The strong repulsion means that when the electrode material is mounted on the frame, it can be mounted without gaps. However, if the repulsive force is too strong, there is a risk that the frame, the ceramic interior material, and the like may be damaged by the repulsive force and the influence of the liquid pressure during operation as an electrode material. For this reason, the repulsion force is a value obtained by a measurement method described later and needs to be in a range of 2 kg / cm 2 to 4 kg / cm 2 .
【００３７】炭素繊維フェルトの反発力が２ｋｇ／ｃｍ
2未満の場合、炭化繊維フェルトを電池に装着時及び充
放電繰り返し時に電池内に空隙を生じやすい。このよう
な空隙が生じた場合、電解液の炭素繊維電極への透過性
が不均一となり、単電池間の性能のバラツキ及び充放電
効率の低下を生ずるので好ましくない。The resilience of carbon fiber felt is 2 kg / cm
If it is less than 2 , voids are likely to occur in the battery when the carbonized fiber felt is attached to the battery and when charging and discharging are repeated. When such voids are formed, the permeability of the electrolyte to the carbon fiber electrode becomes non-uniform, which causes variations in performance between cells and a decrease in charge / discharge efficiency, which is not preferable.
【００３８】反発力が４ｋｇ／ｃｍ2を超える場合、電
池装着時の炭素繊維フェルトの圧縮操作が難しくなると
共に、装着後に炭素繊維の微粉末が発生し易くなり、電
池性能の低下の原因になる。更に、炭素繊維フェルトと
厚さ方向に内接又は外接する材料に過度の応力を与える
ことになり、これら材料の損傷や破壊を生じやすくな
る。When the resilience exceeds 4 kg / cm 2 , the operation of compressing the carbon fiber felt at the time of mounting the battery becomes difficult, and the fine powder of carbon fiber is easily generated after the mounting, which causes the deterioration of the battery performance. . In addition, excessive stress is applied to materials inscribed or circumscribed in the thickness direction with the carbon fiber felt, and these materials are easily damaged or broken.
【００３９】前述のように、ナトリウム−硫黄電池の場
合、円筒型炭素繊維フェルトの内側にナトリウムの充填
用セラミック管が配置してある。このため、炭素繊維フ
ェルトの過度な反発力は、セラミック管の破壊や損傷の
原因となる。従って、反発力が４ｋｇ／ｃｍ2を超える
ことは好ましくない。As described above, in the case of a sodium-sulfur battery, a ceramic tube for filling sodium is disposed inside a cylindrical carbon fiber felt. For this reason, excessive repulsion of the carbon fiber felt causes breakage and damage of the ceramic tube. Therefore, it is not preferable that the repulsion exceeds 4 kg / cm 2 .
【００４０】反発力の調整は、原料繊維の太さ、真円
度、フェルト加工時の厚さ方向の繊維配列度の調整によ
り行うことができる。The repulsion can be adjusted by adjusting the thickness and roundness of the raw fibers and the degree of fiber arrangement in the thickness direction during felting.
【００４１】炭素繊維フェルト自体の特性としての除圧
後の厚さ復元率は、炭素繊維フェルトを枠体に装着時、
枠体への圧接状態、配設の安定状態に影響を与える。即
ち、炭素繊維フェルトは枠体に装着する際に圧縮され、
枠体挿入後除圧状態で装着されている。この時に炭素繊
維フェルトは枠体へ圧接され固定されている。しかし、
除圧後の復元率は高くても圧縮時の反発力が低いと、装
着安定性が悪くなる。このため、前述の反発力とこの除
圧後の復元力とは、両者相まって装着時及び電極材とし
ての作動時の安定性に重要な影響を与える。The thickness recovery rate after depressurization as a characteristic of the carbon fiber felt itself is as follows when the carbon fiber felt is mounted on the frame.
It affects the state of pressure contact with the frame and the stable state of installation. That is, the carbon fiber felt is compressed when mounted on the frame,
It is mounted in a decompressed state after the frame is inserted. At this time, the carbon fiber felt is pressed and fixed to the frame. But,
Even if the restoration rate after decompression is high, if the resilience during compression is low, the mounting stability will be poor. For this reason, the above-described repulsive force and the restoring force after decompression together have an important influence on the stability during mounting and operation as an electrode material.
【００４２】炭素繊維フェルトにおいて高い除圧後の厚
さ復元率が求められることは既に知られている(特開平
２−１５４０４７号公報参照）。It is already known that a high thickness restoration ratio after depressurization is required for carbon fiber felt (see Japanese Patent Application Laid-Open No. 2-15447).
【００４３】この炭素繊維フェルトの除圧後の復元率
は、後に説明する方法により測定するものであるが、こ
の測定値が９８％未満の場合は、炭素繊維フェルトを圧
縮して電池の隙間に装着後の復元性が悪い為隙間が生じ
る。このため、電池の作動時に炭素繊維フェルト内の電
解質の透過性が不均一になって短期及び長期の電池作動
特性に影響を及ぼし、その結果電池の充放電効率を低下
させる。The restoration rate of the carbon fiber felt after depressurization is measured by the method described later. If the measured value is less than 98%, the carbon fiber felt is compressed and inserted into the gap of the battery. There is a gap due to poor restorability after mounting. As a result, the permeability of the electrolyte in the carbon fiber felt during the operation of the battery becomes non-uniform, which affects the short-term and long-term battery operation characteristics, thereby lowering the charge / discharge efficiency of the battery.
【００４４】圧縮時の反発力、及び除圧後の厚さ復元率
は次の方法によって求めることができる。The repulsive force during compression and the thickness restoration rate after decompression can be determined by the following methods.
【００４５】圧縮時の反発力 直径１．０ｃｍの円板状に打ち抜いた炭素繊維フェルト
を厚さ方向に加圧して圧縮させる。圧縮前の厚さに対
し、５０％圧縮時の圧縮荷重（ｋｇ／ｃｍ2）を反発力
とする。 Repulsion Force During Compression A carbon fiber felt punched into a disk having a diameter of 1.0 cm is pressed in the thickness direction and compressed. The repulsive force is the compression load (kg / cm 2 ) at the time of 50% compression with respect to the thickness before compression.
【００４６】除圧後の厚さ復元率 上記と同じ形状の炭素繊維フェルトを圧縮前の厚さに対
し厚さ方向に５０％圧縮する。次いで、除圧１０分間後
の厚さを求め、下記式により復元率を求める。 Thickness restoration rate after pressure reduction A carbon fiber felt having the same shape as above is compressed by 50% in the thickness direction with respect to the thickness before compression. Next, the thickness after 10 minutes of depressurization is determined, and the restoration rate is determined by the following equation.
【００４７】復元率（％）＝［除圧１０分後の厚さ（ｍ
ｍ）／圧縮前の厚さ（ｍｍ）］×１００ 復元率の調整も反発力と同様、原料繊維の太さ、真円
度、及びフェルト加工時の厚さ方向の繊維配列度の調整
により行うことができる。Restoration rate (%) = [thickness (m
m) / thickness before compression (mm)] × 100 The restoration rate is also adjusted by adjusting the thickness, roundness, and the degree of fiber arrangement in the thickness direction at the time of felting, as in the case of the repulsive force. be able to.
【００４８】炭素繊維フェルトの比抵抗値は０．１１Ω
・ｃｍ以下である。炭素繊維フェルトの比抵抗値が０．
１１Ω・ｃｍを超える場合は、電池電極材として用いた
場合、電池の充放電効率が低下する。The specific resistance of the carbon fiber felt is 0.11Ω.
-Cm or less. The specific resistance value of the carbon fiber felt is 0.
If it exceeds 11 Ω · cm, the charge / discharge efficiency of the battery decreases when used as a battery electrode material.
【００４９】従来、電極材用炭素繊維フェルトの電気伝
導度を向上させる努力は図られているが、その値は、比
抵抗値で０．４Ω・ｃｍが精々であり、０．２Ω・ｃｍ
を下回ることは出来なかった。Conventionally, efforts have been made to improve the electrical conductivity of carbon fiber felt for electrode materials, but the specific value is 0.4 Ω · cm in specific resistance, and 0.2 Ω · cm.
Could not be less than.
【００５０】本発明者らは、炭素繊維フェルトの厚さ方
向の繊維配列度を高めると共に、最高焼成温度が１７０
０℃以上の不活性ガス雰囲気下で、炭素繊維表面の酸素
濃度Ｏ／Ｃを０．０８以下に制御することによって上記
比抵抗値を実現し得たものである。The present inventors increased the degree of fiber arrangement in the thickness direction of the carbon fiber felt and set the maximum firing temperature to 170.
The above specific resistance value can be realized by controlling the oxygen concentration O / C on the carbon fiber surface to 0.08 or less under an inert gas atmosphere of 0 ° C. or more.
【００５１】更に、炭素繊維フェルトを構成している炭
素繊維の結晶子サイズは、Ｘ線結晶サイズ（Ｌｃ）で
１．３ｎｍ以上が好ましい。より好ましくは２ｎｍ以上
である。Further, the crystallite size of the carbon fiber constituting the carbon fiber felt is preferably 1.3 nm or more in X-ray crystal size (Lc). More preferably, it is 2 nm or more.
【００５２】Ｘ線結晶サイズ（Ｌｃ）が１．３ｎｍ未満
の場合、炭素繊維自体の電気伝導性が低くなる。このた
め炭素繊維フェルトの厚さ方向の配列度を高めても、炭
素繊維フェルトの比抵抗値を０．１１Ω・ｃｍより低く
し難くなる。またこのようにＸ線結晶サイズ（Ｌｃ）を
高めることによって、炭素繊維ひいては炭素繊維フェル
トの耐酸化性を高めることが出来る。When the X-ray crystal size (Lc) is less than 1.3 nm, the electric conductivity of the carbon fiber itself becomes low. For this reason, even if the degree of arrangement in the thickness direction of the carbon fiber felt is increased, it is difficult to make the specific resistance value of the carbon fiber felt lower than 0.11 Ω · cm. In addition, by increasing the X-ray crystal size (Lc) in this manner, the oxidation resistance of the carbon fiber and thus the carbon fiber felt can be increased.
【００５３】一方、Ｘ線結晶サイズ（Ｌｃ）が４．０ｎ
ｍを超える場合は、炭素繊維の強度低下や伸度低下が生
じ易くなり、更に炭素繊維の微粉末が発生し易くなるの
で好ましくない。On the other hand, the X-ray crystal size (Lc) is 4.0 n
If it exceeds m, the strength and elongation of the carbon fiber tend to decrease, and fine powder of the carbon fiber tends to occur, which is not preferable.
【００５４】炭素繊維フェルトにおける炭素繊維の配列
度は３０％以上が好ましく、特に４０％以上が好まし
い。The degree of arrangement of the carbon fibers in the carbon fiber felt is preferably at least 30%, particularly preferably at least 40%.
【００５５】炭素繊維の配列度が３０％未満の場合は、
厚さ方向の反発力及び除圧後の厚さ復元率が低いものと
なると共に、電解質の透過性が悪くなり、電池としての
充放電効率の低下を招くので好ましくない。When the degree of arrangement of the carbon fibers is less than 30%,
The repulsion in the thickness direction and the thickness recovery rate after depressurization are low, and the permeability of the electrolyte is deteriorated, resulting in a decrease in the charge / discharge efficiency of the battery.
【００５６】一方、炭素繊維の配列度が８０％を超える
場合は、酸化繊維をフェルト加工する際に繊維切れが発
生し、炭素繊維フェルトの微粉末発生量が多くなり、炭
素繊維フェルトの強度が低下するので好ましくない。On the other hand, when the degree of arrangement of the carbon fibers exceeds 80%, fiber breakage occurs when the oxidized fibers are subjected to felt processing, the amount of fine powder of the carbon fiber felt increases, and the strength of the carbon fiber felt decreases. It is not preferable because it decreases.
【００５７】この炭素繊維フェルトにおける炭素繊維厚
さ方向の配列度は、次の方法によって求める。The degree of arrangement in the carbon fiber thickness direction of the carbon fiber felt is determined by the following method.
【００５８】炭素繊維の厚さ方向の繊維配列度（％） Ｘ線回折ピ−ク角度（２θ＝２６．０°付近）でのＺ−
Ｘ面及びＺ−Ｙ面で３６０°試料を回転させる。 Fiber arrangement degree (%) in the thickness direction of carbon fiber Z- axis at X-ray diffraction peak angle (around 2θ = 26.0 °)
Rotate the sample 360 ° in the X and ZY planes.
【００５９】この時得られるＸ線回折強度変化より結晶
子の配向ピークを得る。結晶子が繊維軸方向に高配向し
ていることを利用し、この配向ピーク面積を測定して下
式により繊維配列度を算出する。 厚さ方向（Ｚ）の繊維配列度（％）＝（Ｚ方向の配向ピ
ーク面積）÷（Ｘ＋Ｙ＋Ｚ）方向の配向ピーク面積 ここで、炭素繊維フェルトの厚さ方向をＺ、幅方向を
Ｘ、長さ方向をＹとする。The orientation peak of the crystallite is obtained from the change in the X-ray diffraction intensity obtained at this time. Utilizing the fact that crystallites are highly oriented in the fiber axis direction, the orientation peak area is measured, and the degree of fiber arrangement is calculated by the following equation. Degree of fiber arrangement in the thickness direction (Z) (%) = (Orientation peak area in the Z direction) ÷ (X + Y + Z) orientation peak area Here, the thickness direction of the carbon fiber felt is Z, the width direction is X, and the length is X. The vertical direction is Y.
【００６０】炭素繊維フェルトの厚さ方向の繊維配列度
は、炭素化前の原料である酸化繊維フェルトの厚さ方向
の繊維配列度によりコントロールされる。（炭素繊維フ
ェルトの製造）次に、上記構成の本発明の電極材用炭素
繊維フェルトの製造方法に付、説明する。本発明の炭素
繊維フェルトの製造方法の大筋は、先ずポリアクリロニ
トリル系繊維を空気中で酸化処理して酸化繊維を得、次
いで得られた酸化繊維を用いて酸化繊維フェルトを製造
し、最後に前記製造した酸化繊維フェルトを不活性ガス
中で炭素化処理をすることにより炭素繊維フェルトを得
るものである。The degree of fiber arrangement in the thickness direction of the carbon fiber felt is controlled by the degree of fiber arrangement in the thickness direction of the oxidized fiber felt which is a raw material before carbonization. (Production of carbon fiber felt) Next, a method for producing the carbon fiber felt for an electrode material of the present invention having the above-described structure will be described. The outline of the method for producing a carbon fiber felt according to the present invention is as follows. First, an oxidized fiber is obtained by oxidizing polyacrylonitrile-based fiber in air, and then an oxidized fiber felt is produced using the obtained oxidized fiber. The carbon fiber felt is obtained by subjecting the produced oxidized fiber felt to carbonization in an inert gas.
【００６１】ポリアクリロニトリル系繊維 出発原料のポリアクリロニトリル系繊維は、アクリロニ
トリル単量体を単独重合させたもの、またはアクリル
酸、イタコン酸、若しくはこれらのエステル類、塩類、
更にはアクリルアミド等のアクリロニトリル単量体と共
重合可能なその他の単量体とアクリロニトリル単量体と
を共重合させたものが使用出来る。その他の単量体の共
重合割合は、１２質量％以下が好ましい。 Polyacrylonitrile fiber The starting material polyacrylonitrile fiber is obtained by homopolymerizing acrylonitrile monomer, acrylic acid, itaconic acid, or esters or salts thereof.
Further, those obtained by copolymerizing an acrylonitrile monomer with another monomer copolymerizable with an acrylonitrile monomer such as acrylamide can be used. The copolymerization ratio of the other monomers is preferably 12% by mass or less.
【００６２】原料のポリアクリロニトリル系繊維は、
０．５７〜３．４０ｄｔｅｘのものが好ましい。また繊
維断面は円形に近く、真円度が０．８０以上の繊維が好
ましい。The raw material polyacrylonitrile fiber is
Those having a dtex of 0.57 to 3.40 dtex are preferred. Further, the fiber cross section is close to circular, and a fiber having a roundness of 0.80 or more is preferable.
【００６３】０．５7ｄｔｅｘより細い繊維を用いる場
合、本発明において規定する反発力及び圧縮復元率の炭
素繊維フェルトを得ることができない。また嵩密度が高
くなり電解質の透過性が低下する。When fibers smaller than 0.57 dtex are used, it is impossible to obtain a carbon fiber felt having a repulsion force and a compression recovery specified in the present invention. Also, the bulk density increases and the permeability of the electrolyte decreases.
【００６４】３．４０ｄｔｅｘより太いポリアクリロニ
トリル繊維を用いる場合、これを用いて製造した酸化繊
維をニードルパンチでフェルト加工する際、フェルトの
厚さ方向の繊維配列度及び嵩密度を高くすることが難し
く、このため炭素化後の比抵抗値を目標値に到達させる
ことが難しくなる。When a polyacrylonitrile fiber having a thickness of more than 3.40 dtex is used, it is difficult to increase the fiber arrangement degree and the bulk density in the thickness direction of the felt when the oxidized fiber produced using the fiber is subjected to felt processing by needle punching. Therefore, it is difficult to make the specific resistance value after carbonization reach the target value.
【００６５】原料のポリアクリロニトリル系繊維の真円
度が０．８未満の場合、得られる炭素繊維の剛直性が低
くなり、炭素繊維フェルトの厚さ方向の反発力及び圧縮
復元率が低下する。When the roundness of the raw material polyacrylonitrile fiber is less than 0.8, the rigidity of the obtained carbon fiber becomes low, and the resilience in the thickness direction of the carbon fiber felt and the compression recovery rate decrease.
【００６６】原料のポリアクリロニトリル系繊維の直径
は、ノズルの孔径、紡糸時の吐出量、吐出速度、及び延
伸条件により調整できる。また、真円度は、ノズル孔の
形状、洗浄速度、及び繊維の延伸条件により調整でき
る。ノズルの孔形状としては、真円が好ましい。The diameter of the raw material polyacrylonitrile fiber can be adjusted by the nozzle hole diameter, the discharge amount during spinning, the discharge speed, and the drawing conditions. In addition, the roundness can be adjusted by the shape of the nozzle hole, the cleaning speed, and the fiber drawing conditions. The hole shape of the nozzle is preferably a perfect circle.
【００６７】酸化処理 原料のポリアクリロニトリル系繊維の酸化処理は、上記
原料のポリアクリロニトリル系繊維を空気中で加熱する
ことにより行なう。酸化処理は、酸化処理条件を選択す
ることにより、得られる酸化繊維の比重を１．３３〜
１．４５にする。The oxidation treatment of the polyacrylonitrile-based fiber as the raw material for oxidation treatment is performed by heating the polyacrylonitrile-based fiber as the raw material in the air. In the oxidation treatment, the specific gravity of the oxidized fiber obtained is selected from 1.33 to 0.33 by selecting the oxidation treatment conditions.
Set to 1.45.
【００６８】酸化繊維の比重が１．３３未満の場合、酸
化繊維を用いて製造した酸化繊維フェルトを炭素化する
際、炭素繊維の収率の低下と炭素繊維の異常収縮を生
じ、得られる炭素繊維フェルトが硬くなると共に、フェ
ルト強度が低下する。酸化繊維の比重が１．４５を超え
る場合は、酸化繊維の引張り伸度が低下し、これを用い
て酸化繊維フェルトを製造する際の加工性が低下する。When the specific gravity of the oxidized fiber is less than 1.33, when carbonizing the oxidized fiber felt produced using the oxidized fiber, the yield of the carbon fiber is reduced and the carbon fiber is abnormally shrunk. As the fiber felt becomes harder, the felt strength decreases. When the specific gravity of the oxidized fiber exceeds 1.45, the tensile elongation of the oxidized fiber is reduced, and the processability when producing the oxidized fiber felt using the oxidized fiber is reduced.
【００６９】酸化繊維の比重の調整は酸化温度及び酸化
処理時間により調整する。The specific gravity of the oxidized fiber is adjusted by the oxidation temperature and the oxidation treatment time.
【００７０】酸化繊維の引張り強度は１５ｋｇｆ／ｍｍ
2以上、伸度は１０％以上が好ましい。酸化繊維の引張
り強度が１５ｋｇｆ／ｍｍ2未満の場合フェルトの加工
性が低下すると共に、フェルトの強度が低下する。酸化
繊維の伸度が１０％未満の場合、酸化繊維フェルトを製
造する際の加工性が低下する。The tensile strength of the oxidized fiber is 15 kgf / mm
The elongation is preferably 2 % or more and 10% or more. When the tensile strength of the oxidized fiber is less than 15 kgf / mm 2 , the workability of the felt is reduced and the strength of the felt is reduced. When the elongation of the oxidized fiber is less than 10%, the processability in producing the oxidized fiber felt is reduced.
【００７１】酸化繊維のクリンプ処理 上記のようにして製造した酸化繊維を、次いで、クリン
プ処理する。酸化繊維のクリンプ数は４〜２０ヶ／イン
チ、クリンプ率は５〜２５％が好ましい。 Crimp Treatment of Oxidized Fiber The oxidized fiber produced as described above is then crimped. The number of crimps of the oxidized fibers is preferably 4 to 20 / inch, and the crimp rate is preferably 5 to 25%.
【００７２】酸化繊維フェルト 次いで、上記クリンプ処理をした酸化繊維をニードルパ
ンチ処理して酸化繊維フェルトを製造する。 Oxidized fiber felt Next, the oxidized fiber subjected to the crimp treatment is needle-punched to produce an oxidized fiber felt.
【００７３】酸化繊維のフェルトに加工する加工方法に
おいては、フェルトの厚さ方向の流体の透過性を向上さ
せるため、フェルトの厚さ方向に繊維を高配列させ必要
がある。この目的には、ニードルパンチング法を採用す
ることが好ましい。In the processing method for processing oxidized fiber into felt, it is necessary to arrange fibers in a high direction in the thickness direction of the felt in order to improve fluid permeability in the thickness direction of the felt. For this purpose, it is preferable to adopt a needle punching method.
【００７４】用いる酸化繊維の好ましい繊維長は２０〜
１００ｍｍであり、更に好ましくは２５〜８０ｍｍであ
る。繊維長が２０ｍｍ未満の場合は、フェルト加工時に
フェルトの引張り強度が低下する為、焼成時に炭素繊維
フェルトが伸び、厚さ、及び幅が長さ方向にバラツキを
生ずる。繊維長が１００ｍｍを超える場合は、フェルト
の厚さ方向に繊維を高配列させることが難しい。The preferred fiber length of the oxidized fiber used is 20 to
It is 100 mm, more preferably 25 to 80 mm. If the fiber length is less than 20 mm, the tensile strength of the felt is reduced during felting, so that the carbon fiber felt is stretched during firing, and the thickness and width vary in the length direction. When the fiber length exceeds 100 mm, it is difficult to arrange the fibers in a high direction in the thickness direction of the felt.
【００７５】フェルト加工前の酸化繊維の水分率は１０
〜１８質量％に調整することが好ましい。１０質量％未
満の場合は、フェルトの嵩密度が低下すると共にフェル
トの強度が低下する。１８質量％を超える場合は、嵩密
度が高くなり、炭素繊維フェルトとして用いる場合、電
解質の透過性が低下する。The water content of the oxidized fiber before felting is 10
It is preferable to adjust to 18% by mass. If it is less than 10% by mass, the bulk density of the felt decreases and the strength of the felt decreases. When the content exceeds 18% by mass, the bulk density increases, and when used as a carbon fiber felt, the permeability of the electrolyte decreases.
【００７６】これら酸化繊維のフェルト加工において
は、ニードルの太さ及び打ち込み本数を調整し、酸化繊
維フェルトの厚さ方向に繊維を高配列させる。厚さ方向
の酸化繊維の繊維配列度は３０〜８０％が好ましく、特
に４０〜８０％がより好ましい。In the felt processing of these oxidized fibers, the thickness of the needles and the number of driving fibers are adjusted, and the fibers are arranged in a high direction in the thickness direction of the oxidized fiber felt. The fiber orientation degree of the oxidized fibers in the thickness direction is preferably from 30 to 80%, particularly preferably from 40 to 80%.
【００７７】酸化繊維の繊維配列度の測定は、溶融した
樹脂に酸化繊維フェルトを浸漬、冷却固化後、カットし
顕微鏡写真を画像解析することにより求める。酸化繊維フェルトの炭素化処理 以上のようにしてフェルト加工して製造した酸化繊維フ
ェルトを、不活性雰囲気中で焼成して炭素化処理する。The fiber arrangement degree of the oxidized fiber is measured by immersing the oxidized fiber felt in a molten resin, solidifying it by cooling, cutting, and image-analyzing a micrograph. Carbonization treatment of oxidized fiber felt The oxidized fiber felt produced by felting as described above is calcined in an inert atmosphere by firing.
【００７８】酸化繊維フェルトの炭素化は６００〜１３
００℃で１〜１０分間、好ましくは２〜１０分間焼成
し、その後更に１７００℃以上、特に好ましくは１８０
０〜２５００℃で一段で焼成することが望ましい。１７
００℃以上の焼成処理は、０．５〜１０分間が好まし
い。焼成時の不活性ガスとしては高純度の窒素、ヘリウ
ム、アルゴンガス等が例示できる。The carbonization of the oxidized fiber felt is from 600 to 13
Firing at 00 ° C. for 1 to 10 minutes, preferably 2 to 10 minutes, and then further at 1700 ° C. or more, particularly preferably 180 ° C.
It is desirable to bake in one step at 0 to 2500 ° C. 17
The baking treatment at a temperature of 00 ° C. or more is preferably performed for 0.5 to 10 minutes. Examples of the inert gas at the time of firing include high-purity nitrogen, helium, and argon gases.
【００７９】不活性ガス中の酸素濃度は２０ｐｐｍ以下
が望ましい。酸素濃度が２０ｐｐｍを超える場合、炭素
繊維の表面酸素濃度Ｏ／Ｃが高くなり、炭素繊維の酸化
に伴う強度低下及び電気伝導度低下を生じ、その結果こ
れを用いた電池は充放電特性が低下する。また高温電解
質中での耐熱性及び耐化学薬品性が低下する。The oxygen concentration in the inert gas is desirably 20 ppm or less. When the oxygen concentration exceeds 20 ppm, the surface oxygen concentration O / C of the carbon fiber becomes high, and the strength and electric conductivity of the carbon fiber decrease due to oxidation. As a result, the charge / discharge characteristics of the battery using this decrease. I do. In addition, heat resistance and chemical resistance in a high-temperature electrolyte are reduced.
【００８０】Ｏ／Ｃを０．０８以下にするには、基本的
には酸化性ガス及び酸化性の不純物（有機物及び金属）
の混入を避ける必要がある。これは、焼成前の原料への
不純物の混入防止及び焼成時の不活性ガスの種類、投入
量及び投入方法により調整できる。In order to reduce the O / C to 0.08 or less, basically, an oxidizing gas and oxidizing impurities (organic substances and metals) are used.
It is necessary to avoid contamination. This can be adjusted by preventing impurities from being mixed into the raw material before firing, and by adjusting the type, amount and method of inert gas used during firing.
【００８１】炭素繊維フェルトのＸ線結晶サイズ（Ｌ
ｃ）は１．３ｎｍ以上、好ましくは２．０ｎｍ以上であ
り、これは焼成時の焼成温度及び時間を調節することに
より調整する。The X-ray crystal size (L
c) is at least 1.3 nm, preferably at least 2.0 nm, which is adjusted by adjusting the firing temperature and time during firing.
【００８２】このようにして製造した炭素繊維フェルト
の炭素繊維の直径は、６〜２０μｍが好ましい。直径６
μｍ未満の炭素繊維フェルトを電極材に用いる場合は、
電池作動時の電解質の流れが悪くなるので好ましくな
い。一方、直径２０μｍを超える炭素繊維のフェルトを
電極に用いる場合は、炭素繊維フェルトの反発力が高く
なり過ぎ、電池への装着時に炭素繊維が折れ微粉末を発
生し易くなるので好ましくない。The diameter of the carbon fiber of the carbon fiber felt thus produced is preferably 6 to 20 μm. Diameter 6
When using carbon fiber felt of less than μm for the electrode material,
It is not preferable because the flow of the electrolyte during the operation of the battery is deteriorated. On the other hand, when a carbon fiber felt having a diameter of more than 20 μm is used for the electrode, the resilience of the carbon fiber felt becomes too high, and the carbon fiber is easily broken at the time of attachment to a battery, and thus it is not preferable.
【００８３】炭素繊維フェルトの厚さは、４０ｍｍ以下
が好ましい。４０ｍｍを超える場合は、焼成時不活性ガ
スの浸透性が低下し、厚さ方向に焼成ムラを生じ易くな
る。またフェルトの厚さ方向の繊維配列を高める為の加
工が難しくなり、ニードルパンチの針折れが生じ易い。The thickness of the carbon fiber felt is preferably 40 mm or less. If it exceeds 40 mm, the permeability of the inert gas during firing decreases, and firing unevenness tends to occur in the thickness direction. Further, processing for increasing the fiber arrangement in the thickness direction of the felt becomes difficult, and the needle punch is likely to be broken.
【００８４】更に好ましい炭素繊維フェルトの厚さは、
特に限定されないが８〜２５ｍｍである。原料の酸化繊
維フェルトの厚さは、炭素化時の収縮率を考慮に入れた
場合１０〜３０ｍｍの範囲が好ましい。Further preferred thickness of the carbon fiber felt is
Although not particularly limited, it is 8 to 25 mm. The thickness of the oxidized fiber felt as the raw material is preferably in the range of 10 to 30 mm in consideration of the shrinkage during carbonization.
【００８５】炭素繊維フェルトの嵩密度は、０．０８〜
０．１５ｇ／ｃｍ3が好ましい。この炭素繊維フェルト
を電池用電極材に用いる場合、炭素繊維フェルトの嵩密
度が０．０８ｇ／ｃｍ3未満の場合は、炭素繊維フェル
トの比抵抗値が大きくなるので好ましくない。一方、炭
素繊維フェルトの嵩密度が０．１５ｇ／ｃｍ3を超える
場合は、電解質の流動性が低下するので好ましくない。The bulk density of the carbon fiber felt is 0.08 to
0.15 g / cm 3 is preferred. When this carbon fiber felt is used as an electrode material for a battery, if the bulk density of the carbon fiber felt is less than 0.08 g / cm 3 , the specific resistance value of the carbon fiber felt increases, which is not preferable. On the other hand, if the bulk density of the carbon fiber felt exceeds 0.15 g / cm 3 , the fluidity of the electrolyte decreases, which is not preferable.
【００８６】[0086]
【実施例】次に実施例を挙げて本発明を具体的に説明す
るが、本発明はこれら実施例により限定されるものでは
ない。なお、実施例１〜５及び比較例１〜８において、
「％」は特に断りのない限り「質量％」を示す。また、
各物性値は次のように定義される。Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In Examples 1 to 5 and Comparative Examples 1 to 8,
“%” Indicates “% by mass” unless otherwise specified. Also,
Each physical property value is defined as follows.
【００８７】Ｘ線結晶サイズ（ｎｍ） 広角Ｘ線回折測定での２θのピ−クの半値幅と下記のシ
ェラーの式より求めた。 Ｘ線結晶サイズＬｃ＝ （ｋ×λ）／β×ｃｏｓθ Ｋ：装置定数 ０．９０ λ：Ｘ線波長 ０．１５４０６ｎｍ β：２θ＝２６．０°付近の最大ピ−クの半値幅表面酸素濃度Ｏ／Ｃ Ｘ線光電子分析法（ＸＰＳ）により求めた。Ｃ1Sの結合
エネルギ−値を２８４．６ｅＶに合わせ、Ｃ1Sのピ−ク
面積を求める。更にＯ1Sのピ−ク面積を結合エネルギ−
５２８〜５４０ｅＶのＯ1Sピ−クより求め、このＯ1S／
Ｃ1S比を装置固有の感度補正値で補正した値を表面酸素
濃度Ｏ／Ｃとした。 X-ray crystal size (nm) The peak half width at 2θ in wide-angle X-ray diffraction measurement was determined from the following Scherrer's formula. X-ray crystal size Lc = (k × λ) / β × cos θ K: Equipment constant 0.90 λ: X-ray wavelength 0.15406 nm β: 2θ = half-peak width half-maximum surface oxygen concentration near 26.0 ° O / C Determined by X-ray photoelectron analysis (XPS). Binding energy of C 1S - combined value to 284.6 eV, peak of C 1S - Request click area. Further, the peak area of O 1S is changed to the binding energy.
Obtained from an O 1S peak of 528 to 540 eV, this O 1S /
The value obtained by correcting the C 1S ratio with the sensitivity correction value unique to the apparatus was defined as the surface oxygen concentration O / C.
【００８８】酸化繊維フェルトの厚さ方向の繊維配列度
（％） 酸化繊維フェルトを３ｃｍ角にカットし、断面（厚さ方
向と平行な断面）の顕微鏡写真を撮影した。この写真を
拡大し、厚さ方向の繊維数と、断面全体に観察される繊
維数を計測し、下記式を用いて厚さ方向の繊維配列度を
算出した。The degree of fiber arrangement in the thickness direction of oxidized fiber felt
(%) The oxidized fiber felt was cut into a 3 cm square, and a micrograph of a cross section (a cross section parallel to the thickness direction) was taken. This photograph was enlarged, the number of fibers in the thickness direction and the number of fibers observed in the entire cross section were measured, and the degree of fiber arrangement in the thickness direction was calculated using the following equation.
【００８９】酸化繊維フェルトの厚さ方向の繊維配列度
（％）＝１００×（厚さ方向の繊維数）／（断面全体に
観察される繊維数）炭素繊維フェルトの厚さ方向の繊維配列度（％） Ｘ線回折ピ−ク角度（２θ＝２６．０°付近）でのＺ−
Ｘ面及びＺ−Ｙ面で３６０°試料を回転させる。この時
得られるＸ線回折強度変化より結晶子の配向ピークを得
る。結晶子が繊維軸方向に高配向していることを利用
し、この配向ピーク面積を測定し下式により求めた。 厚さ方向（Ｚ）の繊維配列度（％）＝（Ｚ方向の配向ピ
ーク面積）÷（Ｘ＋Ｙ＋Ｚ）方向の配向ピーク面積 ここで、炭素繊維フェルトの厚さ方向をＺ、幅方向を
Ｘ、長さ方向をＹとする。The degree of fiber arrangement in the thickness direction of the oxidized fiber felt (%) = 100 × (the number of fibers in the thickness direction) / (the number of fibers observed in the entire cross section) The degree of fiber arrangement in the thickness direction of the carbon fiber felt (%) Z- at X-ray diffraction peak angle (around 2θ = 26.0 °)
Rotate the sample 360 ° in the X and ZY planes. The crystallite orientation peak is obtained from the change in X-ray diffraction intensity obtained at this time. Utilizing that crystallites are highly oriented in the fiber axis direction, the orientation peak area was measured and determined by the following equation. Degree of fiber arrangement in the thickness direction (Z) (%) = (Orientation peak area in the Z direction) ÷ (X + Y + Z) orientation peak area Here, the thickness direction of the carbon fiber felt is Z, the width direction is X, and the length is X. The vertical direction is Y.
【００９０】比抵抗値 直径５．０ｃｍに打ち抜いた円盤状の炭素繊維フェルト
を厚さ方向に１０％圧縮した厚さにおける電気抵抗値よ
り、下記式により計算した値を示す。比抵抗値（Ω・ｃ
ｍ）＝ＲＸＳ÷ＬＲ：１０％圧縮時の厚さ方向の電気抵
抗値（Ω） Ｓ：圧縮面積（２．５ｃｍ×２．５ｃｍ×π：ｃｍ2） Ｌ：圧縮時の厚さ（ｃｍ）充放電効率 電池の充放電サイクル３回目の充放電量を用いて下式に
より充放電効率（％）を算出し、実施例１の充放電効率
を１００（基準値）として、その他の実施例及び比較例
の充電効率を相対値で表示した。 充放電効率（％）＝［放電量（ｋＷｈ）／充電量（ｋＷ
ｈ）］ × １００繊維断面の真円度 繊維断面の電子顕微鏡写真より、繊維断面の最大直径
（Ａ：μｍ）と最小直径（Ｂ：μｍ）を測定し下式より
求めた。 真円度 ＝ Ｂ／Ａ （実施例１〜５）表１又は下記の条件で炭素繊維フェル
トを作製し、得られた炭素繊維フェルトについて、ナト
リウム−硫黄単電池の充放電試験を行い、これらの試験
結果を表１又は下記に示す。 Specific resistance value : A value calculated by the following equation from the electric resistance value at a thickness obtained by compressing a disk-shaped carbon fiber felt punched to a diameter of 5.0 cm by 10% in the thickness direction is shown. Specific resistance (Ω · c
m) = RXS ÷ LR: Electric resistance in the thickness direction at 10% compression (Ω) S: Compression area (2.5 cm × 2.5 cm × π: cm 2 ) L: Thickness at compression (cm) The charge / discharge efficiency (%) was calculated by the following equation using the charge / discharge amount of the third charge / discharge cycle of the battery, and the charge / discharge efficiency of Example 1 was set to 100 (reference value), and the values of other examples and The charging efficiency of the comparative example was indicated by a relative value. Charge / discharge efficiency (%) = [discharge amount (kWh) / charge amount (kW)
h)] × 100 Fiber cross section The maximum diameter (A: μm) and the minimum diameter (B: μm) of the fiber cross section were measured from the electron micrograph of the fiber cross section, and determined by the following formula. Circularity = B / A (Examples 1 to 5) Carbon fiber felts were prepared under Table 1 or the following conditions, and the obtained carbon fiber felts were subjected to a charge / discharge test of a sodium-sulfur unit cell. The test results are shown in Table 1 or below.
【００９１】（実施例１）１．７ｄｔｅｘ、真円度０．
９８のポリアクリロニトリル系繊維（アクリロニトリ
ル：アクリル酸メチル＝９６：４（質量比））を空気中
で２００〜３００℃で酸化処理した。得られた比重１．
４１、引張り強度２１ｋｇｆ／ｍｍ2、伸度２１％の酸
化繊維をクリンプ７ヶ／インチ、クリンプ率１３％でク
リンプ処理後、繊維長５１ｍｍにカットした。(Embodiment 1) 1.7 dtex, circularity of 0.
98 polyacrylonitrile fibers (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) were oxidized at 200 to 300 ° C. in air. Specific gravity obtained 1.
41. An oxidized fiber having a tensile strength of 21 kgf / mm 2 and an elongation of 21% was crimped at 7 crimps / inch and a crimp rate of 13%, and then cut into a fiber length of 51 mm.
【００９２】次いで水スプレーにより水分率を１６％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。（厚さ方向の繊
維配列が７０％） 得られた厚さ１４．５ｍｍ、嵩密度０．１７５ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で５分間窒素（酸素
含有１０ｐｐｍ）中で焼成し、更に１９００℃で３分間
窒素（酸素含有１０ｐｐｍ）雰囲気中で焼成した。その
結果、厚さ１２．８ｍｍ、嵩密度０．１１９／ｃｍ3、
繊維直径１１μｍ、Ｘ線結晶サイズ２．８ｎｍ、炭素繊
維断面の真円度０．９８、Ｏ／Ｃが０．０５、反発力
２．７ｋｇｆ／ｃｍ2、圧縮復元率９９％、厚さ方向の
繊維配列度が７０％、比抵抗値０．０７Ω・ｃｍの炭素
繊維フェルトが得られた。Next, the water content was adjusted to 16% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The fiber arrangement in the thickness direction is 70%.) The obtained thickness is 14.5 mm, and the bulk density is 0.175 g / cm.
The oxidized fiber felt of No. 3 was fired at 1000 ° C. for 5 minutes in nitrogen (10 ppm of oxygen), and further fired at 1900 ° C. for 3 minutes in a nitrogen (10 ppm of oxygen) atmosphere. As a result, the thickness was 12.8 mm, the bulk density was 0.119 / cm 3 ,
Fiber diameter 11 μm, X-ray crystal size 2.8 nm, roundness of carbon fiber cross section 0.98, O / C is 0.05, repulsive force 2.7 kgf / cm 2 , compression recovery rate 99%, thickness direction A carbon fiber felt having a fiber arrangement degree of 70% and a specific resistance value of 0.07 Ω · cm was obtained.
【００９３】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この電池の充放電
効率を測定し、この値を前述のように充放電効率の基準
値１００とした。The carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. The charge / discharge efficiency of this battery was measured, and this value was used as the reference value 100 of the charge / discharge efficiency as described above.
【００９４】（実施例２）１．７ｄｔｅｘ、真円度０．
９８のポリアクリロニトリル系繊維（アクリロニトリ
ル：アクリル酸メチル＝９６：４（質量比））を空気中
で２００〜３００℃で酸化処理した。得られた比重１．
４０、引張り強度２４ｋｇｆ／ｍｍ2 、伸度２１％の酸
化繊維をクリンプ７ヶ／インチ、クリンプ率１３％でク
リンプ処理後、繊維長を５１ｍｍにカットした。(Embodiment 2) 1.7 dtex, circularity of 0.
98 polyacrylonitrile fibers (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) were oxidized at 200 to 300 ° C. in air. Specific gravity obtained 1.
An oxidized fiber having a tensile strength of 24 kgf / mm 2 and an elongation of 21% was crimped at 7 crimps / inch and a crimp rate of 13%, and then cut to a fiber length of 51 mm.
【００９５】次いで水スプレーにより水分率を１６％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整してフェルト加工を行った。（厚さ方向の
繊維配列度７５％） 得られた厚さ１５．０ｍｍ、嵩密度０．１６５ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で５分間窒素（酸素
含有１０ｐｐｍ）中で焼成し、更に２２００℃で３分間
窒素（酸素含有１０ｐｐｍ）雰囲気中で焼成した。その
結果、厚さ１３．５ｍｍ、嵩密度０．１１７ｇ／ｃ
ｍ3、繊維直径１１μｍ、Ｘ線結晶サイズ３．４ｎｍ、
炭素繊維断面の真円度０．９８、Ｏ／Ｃが０．０４、反
発力２．８ｋｇｆ／ｃｍ2、圧縮復元率９９％、厚さ方
向の繊維配列度が７５％、電気抵抗値０．０６Ω・ｃｍ
の炭素繊維フェルトが得られた。Next, the water content was adjusted to 16% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The degree of fiber arrangement in the thickness direction is 75%) The obtained thickness is 15.0 mm and the bulk density is 0.165 g / cm.
The oxidized fiber felt No. 3 was fired at 1000 ° C. for 5 minutes in nitrogen (10 ppm of oxygen), and further fired at 2200 ° C. for 3 minutes in a nitrogen (10 ppm of oxygen) atmosphere. As a result, the thickness was 13.5 mm, and the bulk density was 0.117 g / c.
m 3 , fiber diameter 11 μm, X-ray crystal size 3.4 nm,
Roundness of carbon fiber cross section is 0.98, O / C is 0.04, repulsive force is 2.8 kgf / cm 2 , compression recovery rate is 99%, fiber arrangement degree in the thickness direction is 75%, and electric resistance value is 0. 06Ω · cm
Was obtained.
【００９６】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この電池の充放電
効率を測定したところ、実施例１に対する相対値で１０
１の値が得られた。The carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this battery was measured, it was found to be 10 relative to Example 1.
A value of 1 was obtained.
【００９７】（実施例３）２．２６ｄｔｅｘ、真円度
０．９７のポリアクリロニトリル系繊維（アクリロニト
リル：イタコン酸＝９８：２（質量比））を空気中で２
００〜３００℃で酸化処理した。得られた比重１．４
１、引張り強度１８ｋｇｆ／ｍｍ2、伸度２１％の酸化
繊維をクリンプ７ヶ／インチ、クリンプ率１１％でクリ
ンプ処理後、繊維長を３８ｍｍにカットした。(Example 3) Polyacrylonitrile fiber (acrylonitrile: itaconic acid = 98: 2 (mass ratio)) having a roundness of 2.26 dtex and a roundness of 0.97 was air-mixed in air.
Oxidation treatment was performed at 00 to 300 ° C. Specific gravity 1.4 obtained
1. An oxidized fiber having a tensile strength of 18 kgf / mm 2 and an elongation of 21% was crimped at 7 crimps / inch and a crimp rate of 11%, and then the fiber length was cut to 38 mm.
【００９８】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整してフェルト加工を行った。（厚さ方向の
繊維配列度が５５％） 得られた厚さ１４．５ｍｍ、嵩密度０．１６０ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で５分間窒素（酸素
含有１０ｐｐｍ）中で焼成し、更に２０００℃で３分間
窒素（酸素含有１０ｐｐｍ）雰囲気中で焼成した。その
結果、厚さ１３．０ｍｍ、嵩密度０．１０ｇ／ｃｍ3、
繊維直径１３μｍ、Ｘ線結晶サイズ２．７ｎｍ、炭素繊
維断面の真円度０．９７、Ｏ／Ｃが０．０５、反発力
２．２ｋｇｆ／ｃｍ2、圧縮復元率９９％、厚さ方向の
繊維配列が５５％、比抵抗値０．０５Ω・ｃｍの炭素繊
維フェルトが得られた。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The degree of fiber arrangement in the thickness direction is 55%) The obtained thickness is 14.5 mm, and the bulk density is 0.160 g / cm.
The oxidized fiber felt of No. 3 was fired at 1000 ° C. for 5 minutes in nitrogen (10 ppm of oxygen), and further fired at 2000 ° C. for 3 minutes in a nitrogen (10 ppm of oxygen) atmosphere. As a result, the thickness was 13.0 mm, the bulk density was 0.10 g / cm 3 ,
Fiber diameter 13 μm, X-ray crystal size 2.7 nm, roundness of carbon fiber cross section 0.97, O / C 0.05, repulsion 2.2 kgf / cm 2 , compression recovery 99%, thickness direction A carbon fiber felt having a fiber arrangement of 55% and a specific resistance value of 0.05 Ω · cm was obtained.
【００９９】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この電池の充放電
効率を測定したところ、実施例１に対する相対値で１０
１の値が得られた。The carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this battery was measured, it was found to be 10 relative to Example 1.
A value of 1 was obtained.
【０１００】（実施例４）１．７ｄｔｅｘ、真円度０．
９０のポリアクリロニトリル系繊維（アクリロニトリ
ル：アクリル酸メチル＝９６：４（質量比））を空気中
で２００〜３００℃で酸化処理した。得られた比重１．
４１、引張り強度２０ｋｇｆ／ｍｍ2、伸度２３％の酸
化繊維をクリンプ９ヶ／インチ、クリンプ率１５％でク
リンプ処理後、繊維長３８ｍｍにカットした。(Embodiment 4) 1.7 dtex, roundness of 0.
90 polyacrylonitrile fibers (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) were oxidized at 200 to 300 ° C. in air. Specific gravity obtained 1.
41. An oxidized fiber having a tensile strength of 20 kgf / mm 2 and an elongation of 23% was crimped at 9 crimps / inch and a crimp rate of 15%, and then cut into a fiber length of 38 mm.
【０１０１】次いで水スプレーにより水分率を１６％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。（厚さ方向の繊
維配列度が７５％） 得られた厚さ１５．０ｍｍ、嵩密度０．１７０ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で３分間窒素（酸素
含有１０ｐｐｍ）中で焼成し、更に２０００℃で３分間
窒素（酸素含有１０ｐｐｍ）雰囲気中で焼成した。その
結果、厚さ１３．２ｍｍ、嵩密度０．１１３ｇ／ｃ
ｍ3、繊維直径１１μｍ、Ｘ線結晶サイズ２．７ｎｍ、
炭素繊維断面の真円度０．９、Ｏ／Ｃが０．０４、反発
力２．２ｋｇｆ／ｃｍ2、圧縮回復率９８％、厚さ方向
の繊維配列が７５％、電気抵抗値０．０８Ω・ｃｍの炭
素繊維フェルトが得られた。Next, the water content was adjusted to 16% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The degree of fiber arrangement in the thickness direction is 75%) The obtained thickness is 15.0 mm and the bulk density is 0.170 g / cm.
3 of oxidized fiber felt was calcined in 3 minutes with nitrogen (oxygen-containing 10 ppm) at 1000 ° C., and further calcined at 3 minutes with nitrogen (oxygen-containing 10 ppm) atmosphere at 2000 ° C.. As a result, the thickness was 13.2 mm, and the bulk density was 0.113 g / c.
m 3 , fiber diameter 11 μm, X-ray crystal size 2.7 nm,
Roundness of carbon fiber cross section is 0.9, O / C is 0.04, repulsion force is 2.2 kgf / cm 2 , compression recovery rate is 98%, fiber arrangement in thickness direction is 75%, electric resistance value is 0.08Ω Cm carbon fiber felt was obtained.
【０１０２】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この電池の充放電
効率を測定したところ、実施例１に対する相対値で１０
０の値が得られた。The carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this battery was measured, it was found to be 10 relative to Example 1.
A value of 0 was obtained.
【０１０３】（実施例５）１．７ｄｔｅｘ、真円度０．
９８のポリアクリロニトリル系繊維（アクリロニトリ
ル：アクリルアミド＝９８：２（質量比））を空気中で
２００〜３００℃で酸化処理した。得られた比重１．３
７、引張り強度２１ｋｇｆ／ｍｍ2、伸度２８％の酸化
繊維をクリンプ９ヶ／インチ、クリンプ率１５％でクリ
ンプ処理後、繊維長３８ｍｍにカットした。(Embodiment 5) 1.7 dtex, roundness of 0.
98 polyacrylonitrile fibers (acrylonitrile: acrylamide = 98: 2 (mass ratio)) were oxidized at 200 to 300 ° C. in air. Specific gravity 1.3 obtained
7. An oxidized fiber having a tensile strength of 21 kgf / mm 2 and an elongation of 28% was crimped at 9 crimps / inch and a crimp rate of 15%, and then cut into a fiber length of 38 mm.
【０１０４】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。（厚さ方向の繊
維配列度が７５％） 得られた厚さ１４．７ｍｍ、嵩密度０．１６５ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で１分間窒素（酸素
含有１０ｐｐｍ）中で焼成し、更に２０００℃で３分間
窒素（酸素含有１０ｐｐｍ）雰囲気中で焼成した。その
結果、厚さ１２．９ｍｍ、嵩密度０．１１５ｇ／ｃ
ｍ3、繊維直径１１μｍ、Ｘ線結晶サイズ２．６ｎｍ、
炭素繊維断面の真円度０．９８、Ｏ／Ｃが０．０４、反
発力２．９ｋｇｆ／ｃｍ2、圧縮復元率９９％、厚さ方
向の繊維配列が７８％、比抵抗値０．０４Ω・ｃｍの炭
素繊維フェルトが得られた。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The degree of fiber arrangement in the thickness direction is 75%) The obtained thickness is 14.7 mm, and the bulk density is 0.165 g / cm.
3 of oxidized fiber felt was calcined in 1 minute nitrogen (oxygen-containing 10 ppm) at 1000 ° C., and further calcined at 3 minutes with nitrogen (oxygen-containing 10 ppm) atmosphere at 2000 ° C.. As a result, the thickness was 12.9 mm and the bulk density was 0.115 g / c.
m 3 , fiber diameter 11 μm, X-ray crystal size 2.6 nm,
Roundness of carbon fiber cross section is 0.98, O / C is 0.04, repulsive force is 2.9 kgf / cm 2 , compression recovery rate is 99%, fiber arrangement in thickness direction is 78%, specific resistance value is 0.04Ω Cm carbon fiber felt was obtained.
【０１０５】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この電池の充放電
効率を測定したところ、実施例１に対する相対値で１０
０の値が得られた。The carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this battery was measured, it was 10 relative to Example 1.
A value of 0 was obtained.
【０１０６】[0106]
【表１】 [Table 1]
【０１０７】（比較例１〜８）表２又は下記の条件で炭
素繊維フェルトを作製し、得られた炭素繊維フェルトに
ついて、ナトリウム−硫黄単電池の充放電試験を行い、
これらの試験結果を表２又は下記に示す。(Comparative Examples 1 to 8) Carbon fiber felts were prepared under Table 2 or the following conditions, and the obtained carbon fiber felts were subjected to a charge / discharge test of a sodium-sulfur unit cell.
The test results are shown in Table 2 or below.
【０１０８】（比較例１）１．７ｄｔｅｘ、真円度０．
９８のポリアクリロニトリル系繊維（アクリロニトリ
ル：アクリル酸メチル＝９６：４（質量比））を空気中
で２００〜３００℃で酸化処理した。得られた比重１．
４１、引張り強度２３ｋｇｆ／ｍｍ2、伸度２２％の酸
化繊維をクリンプ８ヶ／インチ、クリンプ率１２％でク
リンプ処理後、繊維長３８ｍｍにカットした。(Comparative Example 1) 1.7 dtex, circularity of 0.
98 polyacrylonitrile fibers (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) were oxidized at 200 to 300 ° C. in air. Specific gravity obtained 1.
41. An oxidized fiber having a tensile strength of 23 kgf / mm 2 and an elongation of 22% was crimped at 8 crimps / inch and a crimp rate of 12%, and then cut into a fiber length of 38 mm.
【０１０９】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。（厚さ方向の繊
維配列が７５％） 得られた厚さ１４．７ｍｍ、嵩密度０．１７０ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で５分間窒素（酸素
含有率１０ｐｐｍ）中で焼成し、更に１６５０℃で１０
分間窒素（酸素含有率１０ｐｐｍ）雰囲気中で焼成し
た。その結果、厚さ１２．９ｍｍ、嵩密度０．１１５ｇ
／ｃｍ3、繊維直径１１μｍ、Ｘ線結晶サイズ１．８ｎ
ｍ、炭素繊維断面の真円度０．９８、Ｏ／Ｃが０．０
５、反発力２．７ｋｇｆ／ｃｍ2、圧縮回復率９９％、
厚さ方向の繊維配列度７５％、比抵抗値０．３５Ω・ｃ
ｍの炭素繊維フェルトが得られた。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The fiber arrangement in the thickness direction is 75%.) The obtained thickness is 14.7 mm and the bulk density is 0.170 g / cm.
The oxidized fiber felt of No. 3 was calcined at 1000 ° C. for 5 minutes in nitrogen (oxygen content: 10 ppm), and further fired at 1650 ° C. for 10 minutes.
It was fired in a nitrogen (oxygen content 10 ppm) atmosphere for minutes. As a result, the thickness was 12.9 mm and the bulk density was 0.115 g.
/ Cm 3 , fiber diameter 11 μm, X-ray crystal size 1.8 n
m, roundness of carbon fiber cross section 0.98, O / C is 0.0
5, repulsive force 2.7 kgf / cm 2 , compression recovery rate 99%,
75% fiber orientation in the thickness direction, 0.35Ω · c specific resistance
m of carbon fiber felt was obtained.
【０１１０】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造し、その電池の充放電効
率を測定したところ、実施例１に対する相対値で９１で
あった。The carbon fiber felt is impregnated with sulfur,
A sodium-sulfur single battery was manufactured, and the charge / discharge efficiency of the battery was measured. As a result, the relative value to that of Example 1 was 91.
【０１１１】（比較例２）１．７ｄｔｅｘ、真円度０．
９０のポリアクリロニトリル系繊維（アクリロニトリ
ル：アクリル酸メチル＝９６：４（質量比））を空気中
で２００〜３００℃で酸化処理した。得られた比重１．
４１、引張り強度２２ｋｇｆ／ｍｍ2、伸度２１％の酸
化繊維をクリンプ８ケ／インチ、クリンプ率１２％でク
リンプ処理後、繊維長３８ｍｍにカットした。(Comparative Example 2) 1.7 dtex, roundness of 0.
90 polyacrylonitrile fibers (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) were oxidized at 200 to 300 ° C. in air. Specific gravity obtained 1.
41. An oxidized fiber having a tensile strength of 22 kgf / mm 2 and an elongation of 21% was crimped at 8 crimps / inch and a crimp rate of 12%, and then cut into a fiber length of 38 mm.
【０１１２】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。（厚さ方向の繊
維配列度が２５％） 得られた厚さ１４．９ｍｍ、嵩密度０．１８０ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で２分間窒素（酸素
含有率１０ｐｐｍ）中で焼成し、更に１６５０℃で１０
分間窒素（酸素含有率１０ｐｐｍ）雰囲気中で焼成し
た。その結果、厚さ１３．０ｍｍ、嵩密度０．１２１ｇ
／ｃｍ3、繊維直径１１μｍ、Ｘ線結晶サイズ１．８ｎ
ｍ、炭素繊維断面の真円度０．９０、Ｏ／Ｃが０．０
５、反発力２．２ｋｇｆ／ｃｍ2、圧縮復元率９５％、
厚さ方向の繊維配列が２５％、比抵抗値０．４０Ω・ｃ
ｍの炭素繊維フェルトが得られた。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The degree of fiber arrangement in the thickness direction is 25%) The obtained thickness is 14.9 mm, and the bulk density is 0.180 g / cm.
The oxidized fiber felt of Example 3 was calcined at 1000 ° C. for 2 minutes in nitrogen (oxygen content: 10 ppm), and further baked at 1650 ° C. for 10 minutes.
It was fired in a nitrogen (oxygen content 10 ppm) atmosphere for minutes. As a result, the thickness was 13.0 mm and the bulk density was 0.121 g.
/ Cm 3 , fiber diameter 11 μm, X-ray crystal size 1.8 n
m, roundness of carbon fiber cross section 0.90, O / C is 0.0
5. Rebound force 2.2 kgf / cm 2 , 95% compression recovery
Fiber arrangement in the thickness direction is 25%, specific resistance 0.40Ω · c
m of carbon fiber felt was obtained.
【０１１３】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この単電池の充放
電効率を測定したところ、実施例１に対する相対値で８
９であった。This carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this cell was measured, it was 8 relative to Example 1.
Nine.
【０１１４】（比較例３）１．７ｄｔｅｘ、真円度０．
９２のポリアクリロニトリル系繊維（アクリロニトリ
ル：アクリル酸メチル＝９６：４（質量比））を空気中
で２００〜３００℃で酸化処理した。得られた比重１．
３７、引張り強度２３ｋｇｆ／ｍｍ2、伸度２４％の酸
化繊維をクリンプ８ヶ／インチ、クリンプ率１２％でク
リンプ処理後、繊維長３８ｍｍにカットした。(Comparative Example 3) 1.7 dtex, circularity of 0.
Ninety-two polyacrylonitrile fibers (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) were oxidized at 200 to 300 ° C. in air. Specific gravity obtained 1.
An oxidized fiber having a tensile strength of 23 kgf / mm 2 and an elongation of 24% was crimped at 8 crimps / inch and a crimp rate of 12%, and then cut into a fiber length of 38 mm.
【０１１５】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。（厚さ方向の繊
維配列度が７５％） 得られた厚さ１５．２ｍｍ、嵩密度０．１７０ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で２分間窒素（酸素
含有率１０ｐｐｍ）中で焼成し、更に２０００℃で３分
間窒素（酸素含有率１０ｐｐｍ）雰囲気中で焼成した。
その結果、厚さ１３．３ｍｍ、嵩密度０．１１３ｇ／ｃ
ｍ3、繊維直径１１μｍ、Ｘ線結晶サイズ２．７ｎｍ、
炭素繊維断面の真円度０．９２、Ｏ／Ｃが０．０５、反
発力２．１ｋｇｆ／ｃｍ2、圧縮復元率９４％、厚さ方
向の繊維配列が７５％、電気抵抗値０．０９Ω・ｃｍの
炭素繊維フェルトが得られた。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The degree of fiber arrangement in the thickness direction is 75%) The obtained thickness is 15.2 mm, and the bulk density is 0.170 g / cm.
The oxidized fiber felt No. 3 was fired at 1000 ° C. for 2 minutes in nitrogen (oxygen content: 10 ppm), and further fired at 2000 ° C. for 3 minutes in a nitrogen (oxygen content: 10 ppm) atmosphere.
As a result, the thickness was 13.3 mm and the bulk density was 0.113 g / c.
m 3 , fiber diameter 11 μm, X-ray crystal size 2.7 nm,
Roundness of carbon fiber cross section is 0.92, O / C is 0.05, repulsion force is 2.1 kgf / cm 2 , compression recovery rate is 94%, fiber arrangement in thickness direction is 75%, electric resistance value is 0.09Ω Cm carbon fiber felt was obtained.
【０１１６】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この単電池の充放
電効率を測定したところ、実施例１に対する相対値で９
５であった。This carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this single cell was measured, it was 9 relative to Example 1.
It was 5.
【０１１７】（比較例４）１．０２ｄｔｅｘ、真円度
０．９８のポリアクリロニトリル系繊維（アクリロニト
リル：アクリル酸メチル＝９６：４（質量比））を空気
中で２００〜３００℃で酸化処理した。得られた比重
１．４１、引張り強度２４ｋｇｆ／ｍｍ2、伸度２５％
の酸化繊維をクリンプ９ヶ／インチ、クリンプ率１３％
でクリンプ処理後、繊維長３８ｍｍにカットした。Comparative Example 4 Polyacrylonitrile fibers (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) having a roundness of 1.02 dtex and a roundness of 0.98 were oxidized in air at 200 to 300 ° C. . Obtained specific gravity 1.41, tensile strength 24 kgf / mm 2 , elongation 25%
Oxidized fiber of 9 crimps / inch, crimp rate 13%
And then cut to a fiber length of 38 mm.
【０１１８】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。（厚さ方向の繊
維配列度が７５％） 得られた厚さ１５．５ｍｍ、嵩密度０．１４０ｇ／ｃｍ
3の酸化繊維フェルトを１０００℃で３分間窒素（酸素
含有率１０ｐｐｍ）中で焼成し、更に２０００℃で３分
間窒素（酸素含有率１０ｐｐｍ）雰囲気中で焼成した。
その結果、厚さ１３．８ｍｍ、嵩密度０．１１８ｇ／ｃ
ｍ3、Ｘ線結晶サイズ２．６ｎｍ、炭素繊維断面の真円
度０．９８、Ｏ／Ｃが０．０５、反発力１．４ｋｇｆ／
ｃｍ2、圧縮回復率９８％、厚さ方向の繊維配列が７５
％、電気抵抗値０．０９Ω・ｃｍの炭素繊維フェルトが
得られた。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction. (The degree of fiber arrangement in the thickness direction is 75%) The obtained thickness is 15.5 mm, and the bulk density is 0.140 g / cm.
3 of oxidized fiber felt was calcined in 3 minutes with nitrogen (oxygen content 10 ppm) at 1000 ° C., and further calcined at 3 minutes with nitrogen (oxygen content 10 ppm) atmosphere at 2000 ° C..
As a result, the thickness was 13.8 mm, and the bulk density was 0.118 g / c.
m 3 , X-ray crystal size 2.6 nm, roundness of carbon fiber cross section 0.98, O / C 0.05, repulsive force 1.4 kgf /
cm 2 , 98% compression recovery, 75 fibers in the thickness direction
%, And a carbon fiber felt having an electric resistance value of 0.09 Ω · cm was obtained.
【０１１９】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この単電池の充放
電効率を測定したところ、実施例１に対する相対値で９
４であった。This carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this single cell was measured, it was 9 relative to Example 1.
It was 4.
【０１２０】（比較例５）１.０２ｄｔｅｘ、真円度０.
７１のポリアクリロニトリル系繊維（アクリロニトリ
ル：アクリル酸メチル＝９６：４（質量比））を空気中
で２００〜３００℃で酸化処理した。得られた比重１.
４１、引張り強度２１ｋｇｆ／ｍｍ2、伸度１８％の酸
化繊維をクリンプ７ヶ／インチ、クリンプ率１０％でク
リンプ処理後、繊維長３８ｍｍにカットした。(Comparative Example 5) 1.02 dtex, roundness: 0.
Seventy-one polyacrylonitrile fibers (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) were oxidized at 200 to 300 ° C. in air. Specific gravity obtained 1.
41. An oxidized fiber having a tensile strength of 21 kgf / mm 2 and an elongation of 18% was crimped at 7 crimps / inch and a crimp rate of 10%, and then cut into a fiber length of 38 mm.
【０１２１】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction.
【０１２２】得られた厚さ１４．５ｍｍ、嵩密度０．１
５６ｇ／ｃｍ3の酸化繊維フェルトを１０００℃で３分
間窒素（酸素含有率１０ｐｐｍ）中で焼成し、更に２０
００℃で３分間窒素（酸素含有率１０ｐｐｍ）雰囲気中
で焼成した。その結果、厚さ１２．８ｍｍ、嵩密度０．
１１３ｇ／ｃｍ3、Ｘ線結晶サイズ２．６ｎｍ、炭素繊
維断面の真円度０．７１、Ｏ／Ｃが０．０６、反発力
０．９ｋｇｆ／ｃｍ2、圧縮復元率９１％、厚さ方向の
繊維配列４５％、電気抵抗値０．１０Ω・ｃｍの炭素繊
維フェルトが得られた。The obtained thickness was 14.5 mm and the bulk density was 0.1
56 g / cm 3 of oxidized fiber felt was fired at 1000 ° C. for 3 minutes in nitrogen (10 ppm oxygen content),
Firing was performed at 00 ° C. for 3 minutes in a nitrogen (oxygen content: 10 ppm) atmosphere. As a result, the thickness was 12.8 mm, and the bulk density was 0.
113 g / cm 3 , X-ray crystal size 2.6 nm, roundness of carbon fiber cross section 0.71, O / C 0.06, repulsive force 0.9 kgf / cm 2 , compression recovery 91%, thickness direction Of carbon fiber felt having a fiber arrangement of 45% and an electric resistance value of 0.10 Ω · cm.
【０１２３】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この単電池の充放
電効率を測定したところ、実施例１に対する相対値で９
４であった。The carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this single cell was measured, it was 9 relative to Example 1.
It was 4.
【０１２４】（比較例６）１．０２ｄｔｅｘ、真円度
０．７１の ポリアクリロニトリル系繊維（アクリロニ
トリル：アクリル酸メチル＝９６：４（質量比））を空
気中で２００〜３００℃で酸化処理した。得られた比重
１．４１、引張り強度２０ｋｇｆ／ｍｍ2、伸度１８％
の酸化繊維をクリンプ８ヶ／インチ、クリンプ率１２％
でクリンプ処理後、繊維長３８ｍｍにカットした。Comparative Example 6 A polyacrylonitrile fiber (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) having a roundness of 1.02 dtex and a roundness of 0.71 was oxidized in air at 200 to 300 ° C. . Obtained specific gravity 1.41, tensile strength 20kgf / mm 2 , elongation 18%
Oxidized fiber of 8 crimps / inch, crimp rate 12%
And then cut to a fiber length of 38 mm.
【０１２５】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction.
【０１２６】得られた厚さ１５．０ｍｍ、嵩密度０．１
５７ｇ／ｃｍ3の酸化繊維フェルトを１０００℃で３分
間窒素（酸素含有３５ｐｐｍ）中で焼成し、更に１２５
０℃で３分間窒素（酸素含有３５ｐｐｍ）雰囲気中で焼
成した。その結果、厚さ１３．５ｍｍ、嵩密度０．１１
１ｇ／ｃｍ3、Ｘ線結晶サイズ１．２ｎｍ、炭素繊維断
面の真円度０．７１、Ｏ／Ｃが０．１７、反発力０．７
ｋｇｆ／ｃｍ2、圧縮復元率８４％、厚さ方向の繊維配
列７５％、電気抵抗値０．３７Ω・ｃｍの炭素繊維フェ
ルトが得られた。The obtained thickness was 15.0 mm and the bulk density was 0.1
57 g / cm 3 of oxidized fiber felt was fired at 1000 ° C. for 3 minutes in nitrogen (35 ppm oxygen),
Calcination was carried out at 0 ° C. for 3 minutes in a nitrogen (oxygen-containing 35 ppm) atmosphere. As a result, the thickness was 13.5 mm and the bulk density was 0.11.
1 g / cm 3 , X-ray crystal size 1.2 nm, roundness of carbon fiber cross section 0.71, O / C 0.17, repulsion 0.7
A carbon fiber felt having a kgf / cm 2 , a compression recovery ratio of 84%, a fiber arrangement in the thickness direction of 75%, and an electric resistance value of 0.37 Ω · cm was obtained.
【０１２７】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この単電池の充放
電効率を測定したところ、実施例１に対する相対値で８
９であった。The carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this cell was measured, it was 8 relative to Example 1.
Nine.
【０１２８】（比較例７）１．０２ｄｔｅｘ、真円度
０．９８のポリアクリロニトリル系繊維（アクリロニト
リル：アクリル酸メチル＝９６：４（質量比））を空気
中で２００〜３００℃で酸化処理した。得られた比重
１．４１、引張り強度２５ｋｇｆ／ｍｍ2、伸度２３％
の酸化繊維をクリンプ９ヶ／インチ、クリンプ率１３％
でクリンプ処理後、繊維長３８ｍｍにカットした。Comparative Example 7 Polyacrylonitrile fiber (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) having a roundness of 1.02 dtex and a roundness of 0.98 was oxidized at 200 to 300 ° C. in air. . Obtained specific gravity 1.41, tensile strength 25 kgf / mm 2 , elongation 23%
Oxidized fiber of 9 crimps / inch, crimp rate 13%
And then cut to a fiber length of 38 mm.
【０１２９】次いで水スプレーにより水分率を１５％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。Next, the water content was adjusted to 15% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction.
【０１３０】得られた厚さ１５．５ｍｍ、嵩密度０．１
６２ｇ／ｃｍ3の酸化繊維フェルトを１０００℃で３分
間窒素（酸素含有２５ｐｐｍ）中で焼成し、更に２００
０℃で３分間窒素（酸素含有２５ｐｐｍ）雰囲気中で焼
成した。その結果、厚さ１３．７ｍｍ、嵩密度０．１１
３ｇ／ｃｍ3、Ｘ線結晶サイズ２６ｎｍ、炭素繊維断面
の真円度０．９８、Ｏ／Ｃが０．１３、反発力１．７ｋ
ｇｆ／ｃｍ2、圧縮復元率９８％、厚さ方向の繊維配列
７５％、電気抵抗値０．１５Ω・ｃｍの炭素繊維フェル
トが得られた。The obtained thickness was 15.5 mm and the bulk density was 0.1
The oxidized fiber felt of 62 g / cm 3 was calcined at 1000 ° C. for 3 minutes in nitrogen (25 ppm of oxygen),
Firing was performed at 0 ° C. for 3 minutes in a nitrogen (oxygen-containing 25 ppm) atmosphere. As a result, the thickness was 13.7 mm and the bulk density was 0.11.
3 g / cm 3 , X-ray crystal size 26 nm, roundness of carbon fiber cross section 0.98, O / C 0.13, repulsive force 1.7 k
A carbon fiber felt having a gf / cm 2 , a compression recovery rate of 98%, a fiber arrangement in the thickness direction of 75%, and an electric resistance value of 0.15 Ω · cm was obtained.
【０１３１】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この単電池の充放
電効率を測定したところ、実施例１に対する相対値で９
５であった。This carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this single cell was measured, it was 9 relative to Example 1.
It was 5.
【０１３２】（比較例８）４．５２ｄｔｅｘ、真円度
０．９７のポリアクリロニトリル系繊維（アクリロニト
リル：アクリル酸メチル＝９６：４（質量比））を空気
中で２００〜３００℃で酸化処理した。得られた比重
１．４０、引張り強度１８ｋｇｆ／ｍｍ2、伸度１６％
の酸化繊維をクリンプ７ヶ／インチ、クリンプ率１０％
でクリンプ処理後、繊維長３８ｍｍにカットした。Comparative Example 8 Polyacrylonitrile fiber (acrylonitrile: methyl acrylate = 96: 4 (mass ratio)) having a roundness of 4.52 dtex and a roundness of 0.97 was oxidized at 200 to 300 ° C. in air. . Obtained specific gravity 1.40, tensile strength 18 kgf / mm 2 , elongation 16%
Oxidized fiber of 7 crimps / inch, crimp rate 10%
And then cut to a fiber length of 38 mm.
【０１３３】次いで水スプレーにより水分率を１６％に
調整した。この酸化繊維を、厚さ方向に繊維が高配列す
るようにフェルトの加工条件（針の打ち込み本数、針の
太さ）を調整しフェルト加工を行った。Next, the water content was adjusted to 16% by water spray. This oxidized fiber was subjected to felt processing by adjusting the felt processing conditions (the number of needles to be driven and the thickness of the needle) so that the fibers were arranged in a high direction in the thickness direction.
【０１３４】得られた厚さ１４．６ｍｍ、嵩密度０．１
４８ｇ／ｃｍ3の酸化繊維フェルトを１０００℃で３分
間窒素（酸素含有率１０ｐｐｍ）中で焼成し、更に２０
００℃で３分間窒素（酸素含有率１０ｐｐｍ）雰囲気中
で焼成した。その結果、厚さ１３．１ｍｍ、嵩密度０．
１０２ｇ／ｃｍ3、Ｘ線結晶サイズ２．５ｎｍ、炭素繊
維断面の真円度０．９７、Ｏ／Ｃが０．０６、反発力
４．３ｋｇｆ／ｃｍ2、圧縮復元率９８％、厚さ方向の
繊維配列６０％、電気抵抗値０．１０Ω・ｃｍの炭素繊
維フェルトが得られた。Obtained thickness 14.6 mm, bulk density 0.1
48 g / cm 3 of oxidized fiber felt was baked at 1000 ° C. for 3 minutes in nitrogen (oxygen content 10 ppm),
Firing was performed at 00 ° C. for 3 minutes in a nitrogen (oxygen content: 10 ppm) atmosphere. As a result, the thickness was 13.1 mm and the bulk density was 0.1.
102 g / cm 3 , X-ray crystal size 2.5 nm, roundness of carbon fiber cross section 0.97, O / C 0.06, repulsive force 4.3 kgf / cm 2 , compression recovery 98%, thickness direction A carbon fiber felt having a fiber arrangement of 60% and an electric resistance value of 0.10 Ω · cm was obtained.
【０１３５】この炭素繊維フェルトに硫黄を含浸させ、
ナトリウム−硫黄単電池を製造した。この単電池の充放
電効率を測定したところ、実施例１に対する相対値で９
４であった。This carbon fiber felt is impregnated with sulfur,
A sodium-sulfur cell was manufactured. When the charging / discharging efficiency of this single cell was measured, it was 9 relative to Example 1.
It was 4.
【０１３６】[0136]
【表２】 [Table 2]
【０１３７】なお、表２中、○は好ましいと思われる結
果を、×は好ましくないと思われる結果を表している。In Table 2, .largecircle. Indicates a result which seems to be preferable, and X indicates a result which is not preferable.
【０１３８】[0138]
【発明の効果】本発明の炭素繊維フェルトは、圧縮前の
厚さに対して厚さを５０％圧縮した時の反発力、除圧後
の厚さ復元率、及び炭素繊維フェルト厚さ方向の比抵抗
値を所定の範囲にしたので、通電方向の電気抵抗値、形
態安定性、単電池内部壁面への密着性、単電池内の他の
材料に加わる応力の度合い、及び作動時の電解質の流れ
の円滑性などの電池用電極材としての要求される要件を
十分満足させる炭素繊維フェルトである。The carbon fiber felt of the present invention has a repulsive force when the thickness is compressed by 50% of the thickness before compression, a thickness recovery rate after decompression, and a thickness in the carbon fiber felt thickness direction. Since the specific resistance value is within a predetermined range, the electric resistance value in the direction of conduction, the form stability, the adhesion to the inner wall surface of the unit cell, the degree of stress applied to other materials in the unit cell, and the electrolyte during operation It is a carbon fiber felt that sufficiently satisfies the requirements for a battery electrode material such as flow smoothness.
【０１３９】また、この炭素繊維フェルトを電極材とし
て用いたナトリウム−硫黄電池などの二次電池は、充放
電効率が極めて高いものである。A secondary battery such as a sodium-sulfur battery using the carbon fiber felt as an electrode material has a very high charge / discharge efficiency.
【０１４０】更に、本発明の炭素繊維フェルトの製造方
法によれば、酸化繊維から炭素繊維への焼成時間が短時
間で済むという利点も有するものである。Further, according to the method for producing a carbon fiber felt of the present invention, there is an advantage that the firing time from the oxidized fiber to the carbon fiber can be shortened.
フロントページの続き (72)発明者 小野 毅 静岡県駿東郡長泉町上土狩234 東邦レー ヨン株式会社研究所内 (72)発明者 川崎 紘二 兵庫県伊丹市西野７−３−１ Ａ−602 Ｆターム(参考） 4L031 AA27 AB01 AB26 BA08 CA02 DA11 4L037 CS03 FA02 FA03 FA05 FA17 FA19 PA54 PC03 PC05 PC11 PS02 UA04 UA20 4L047 AA03 BA03 CC12 5H029 AJ02 AK05 AL13 BJ16 CJ28 DJ07 DJ15 EJ04 HJ00 HJ04 HJ05 HJ13 HJ14 HJ15 HJ20Continuing from the front page (72) Inventor Takeshi Ono 234 Kamidogari, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture Inside of the laboratory of Toho Rayon Co., Ltd. (72) Inventor Koji Kawasaki 7-3-1 Nishino Nishino, Itami-shi, Hyogo A-602 F-term 4L031 AA27 AB01 AB26 BA08 CA02 DA11 4L037 CS03 FA02 FA03 FA05 FA17 FA19 PA54 PC03 PC05 PC11 PS02 UA04 UA20 4L047 AA03 BA03 CC12 5H029 AJ02 AK05 AL13 BJ16 CJ28 DJ07 DJ15 EJ04 HJ00 HJ04 HJH HJH
Claims (5)
り、圧縮前の厚さに対して、厚さを５０％圧縮時の反発
力が２〜４ｋｇ／ｃｍ2で、除圧後の厚さ復元率が９８
％以上、かつ炭素繊維フェルト厚さ方向の比抵抗値が
０．１１Ω・ｃｍ以下であることを特徴とする電極材用
炭素繊維フェルト。1. A polyacrylonitrile-based carbon fiber having a rebound force of 2 to 4 kg / cm 2 when the thickness is compressed to 50% of the thickness before compression, and a thickness recovery rate after decompression. 98
%, And a specific resistance value in a thickness direction of the carbon fiber felt is 0.11 Ω · cm or less.
酸素濃度Ｏ／Ｃが０．０８以下である請求項１に記載の
電極材用炭素繊維フェルト。2. The carbon fiber felt for an electrode material according to claim 1, wherein the surface oxygen concentration O / C of the polyacrylonitrile-based carbon fiber is 0.08 or less.
結晶サイズ（Ｌｃ）が１．３ｎｍ以上、繊維直径が６〜
２０μｍである請求項１に記載の電極材用炭素繊維フェ
ルト。3. The polyacrylonitrile-based carbon fiber has an X-ray crystal size (Lc) of at least 1.3 nm and a fiber diameter of 6 to 6.
The carbon fiber felt for an electrode material according to claim 1, which has a thickness of 20 µm.
度が３０〜８０％である請求項１に記載の電極材用炭素
繊維フェルト。4. The carbon fiber felt for an electrode material according to claim 1, wherein the degree of fiber arrangement in the thickness direction of the carbon fiber felt is 30 to 80%.
（１）０．５７〜３．４０デシテックス（ｄｔｅｘ)
で、かつ繊維断面の真円度が０．８〜１のポリアクリロ
ニトリル系繊維を空気中で酸化処理し酸化繊維とする、
（２）酸化繊維をクリンプ処理した後、厚さ方向の繊維
配列度が３０〜８０％にニ−ドルパンチし、酸化繊維フ
ェルトを作製する、（３）酸化繊維フェルトを不活性ガ
ス中、６００〜１３００℃で１〜１０分間処理後、更に
１７００℃以上の温度で０．５〜１０分間処理する、を
含むことを特徴とする請求項１乃至４の何れかに記載の
電極材用炭素繊維フェルトの製造方法。5. The following steps (1), (2), (3),
(1) 0.57 to 3.40 decitex (dtex)
And the polyacrylonitrile-based fiber having a roundness of the fiber cross section of 0.8 to 1 is oxidized in the air to be an oxidized fiber.
(2) After crimping the oxidized fiber, needle punching is performed so that the degree of fiber arrangement in the thickness direction is 30 to 80% to produce an oxidized fiber felt. The carbon fiber felt for an electrode material according to any one of claims 1 to 4, further comprising: treating at 1300 ° C for 1 to 10 minutes, and further treating at a temperature of 1700 ° C or more for 0.5 to 10 minutes. Manufacturing method.
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| JP2007031912A (en) * | 2005-07-29 | 2007-02-08 | Toho Tenax Co Ltd | Polyacrylonitrile-based oxidized fiber felt, carbon fiber felt and method for producing them |
| US20130295811A1 (en) * | 2010-10-13 | 2013-11-07 | Mitsubishi Rayon Co., Ltd. | Carbon-fiber-precursor fiber bundle, carbon fiber bundle, and uses thereof |
| WO2015146234A1 (en) * | 2014-03-27 | 2015-10-01 | 住友電気工業株式会社 | Carbon fiber felt, manufacturing method therefor, and liquid circulation-type electrolytic cell |
| JP2016000885A (en) * | 2014-05-23 | 2016-01-07 | 東レ株式会社 | Carbon fiber non-woven fabric, gas diffusion electrode for solid high molecular weight form fuel cell and solid high molecular weight form fuel cell |
| CN113789607A (en) * | 2021-09-22 | 2021-12-14 | 辽宁兴汇碳材料科技有限公司 | Polyacrylonitrile-based fibrofelt and preparation method and application thereof |
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| WO2015146234A1 (en) * | 2014-03-27 | 2015-10-01 | 住友電気工業株式会社 | Carbon fiber felt, manufacturing method therefor, and liquid circulation-type electrolytic cell |
| JP2016000885A (en) * | 2014-05-23 | 2016-01-07 | 東レ株式会社 | Carbon fiber non-woven fabric, gas diffusion electrode for solid high molecular weight form fuel cell and solid high molecular weight form fuel cell |
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