JPS61158806A - Formed article of impermeable carbon - Google Patents

Abstract

PURPOSE:To obtain a molded article having excellent gas impermeability and high oxidation-resistance and mechanical properties, by specifying the residual hydrogen content and the true specific gravity of a molded carbon article composed mainly of vitreous carbon and graphite. CONSTITUTION:The objective impermeable molded carbon article has hydrogen content of <= 0.02wt% and a true specific gravity adjusted to be <= 1.9, and is composed mainly of vitreous carbon and graphite. The molded article can be produced by forming a composition composed of thermosetting resin powder, graphite powder and liquid thermosetting resin to a desired form, drying and curing the composition, and carbonizing or partially graphitizing in a nonoxidizing atmosphere or in vacuum. Since the hydrogen content causing the lowering of oxidation resistance is suppressed to a low level and the upper limit of the graphite content to cause the lowering of the impermeability and the mechanical properties is restricted by the use of true specific gravity as an index, the obtained molded article has excellent oxidation resistance and mechanical properties as well as high impermeability.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、気体等の不透過性に優れると共に耐酸化性及
び機械的性質の良好な不透過性炭素成形体く関するもの
である。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an impermeable carbon molded body that is excellent in impermeability to gases, etc., and has good oxidation resistance and mechanical properties.

〔従来の技術〕[Conventional technology]

不透過性炭素成形体は気体及び液体の不透過性材料とし
て提供されたものであるが、加えて電気抵抗が小さく又
耐薬品性も優れているという利点があるところから、電
子、原子力、航空宇宙等の産業分野での幅広い活用が期
待されている。特えは近年注目を集めている燐酸型燃料
電池における分離板としての要求特性を満している為、
この方面での活用が期待されている。即ち燐酸型燃料電
池においては水素ガス等の気体燃料と酸素等の気体酸化
剤とが上記分離板を挾んでその両側に供給されておル、
分離板に気体透過性があったシ酸化剤や電解質等に侵さ
れたシするといった欠点があると上記気体が混合してし
まい、その結果燐酸型燃料電池としての機能が損なわれ
る。従って分離板には、気体不透過性に優れ且つ酸化剤
及び電解質に侵されにくい性質のものが要求される。又
同時に導電性の高いことや曲げ強度等の機械的性質が良
好であることも、装置部品である以上当然に必要である
。この様な背景を受けて特開昭５４−２０９９１号公報
や特開昭５７−７２２７３号公報等に開示された炭素成
形体が提案されているが、いずれも上述の如き要求特性
を完全に満足する迄には至っていない。まず特開昭５４
−２０９９１号公報には硬化フェノール系樹脂の微粉末
とフェノール類・アルデヒド初期縮合物とを混練し成形
硬化させた後、炭化焼成して実質的にガラス質炭素のみ
からなる不透過性炭素成形体を得る方法が開示されてい
るが、この様にして得られる成形体は、その焼成過程中
上記樹脂が著しく収縮し焼成割れが生じ易くなる。この
為肉厚の薄い小板を得ることは可能であっても、実際の
分離板として好ましい厚み０．４〜１．５胴を有するφ
大板を得ることは実用上殆んど不可能である。仮に一応
の成形体として製造することが可能であったとしても気
体不透過性が悪く機械的強度も劣っておシまたガラス状
炭素の特性として電気抵抗が高くなるといった欠点を有
している。一方後者の特開昭５７−７２２７３号公報に
は、黒鉛粉末にフェノール樹脂液（バインダー）を加え
て成形し高温で焼成して全体が実質的に黒鉛よりなる不
透過性炭素成形体を得る方法が開示されている。しかし
この方法においても上記と同様、成形体中の黒鉛とバイ
ンダーの熱収縮率の相異によシ焼成中における微細な割
れを防止することはできない。また全体が実質的に黒鉛
よりなる上述の如き成形体についてはこの他に数種のも
のが知られている。例えば炭化焼成によ）得た黒鉛より
なる成形体の空隙にピッチ、タール、樹脂等の含浸材を
含浸させ、再度焼成してこれら含浸剤を炭化させること
によって不透過性炭素成形体を得る方法があげられるが
、この方法によっても上記成形体と含浸剤の熱収縮率の
違いによシ生じる割れを防止することができない。又前
記特開昭５７−７２２７３号公報等の方法によル得られ
た炭素成形体は、実質的に黒鉛より構成されているので
気体等の不透過性が悪い上に曲げ強度等の機械的性質に
も劣っているといった欠点を有している。従って気体等
の不透過性に優れしかも機械的強度・耐薬品性等が良好
で成形に当たっても特別の不都合を伴わない不透過性炭
素成形体の登場が強く望まれているところである。Impermeable carbon molded bodies were provided as gas and liquid impermeable materials, but they also have the advantage of low electrical resistance and excellent chemical resistance, so they are used in electronic, nuclear, and aerospace applications. It is expected to be widely used in industrial fields such as space. The special feature is that it meets the required characteristics as a separator in phosphoric acid fuel cells, which have been attracting attention in recent years.
It is expected that it will be used in this direction. That is, in a phosphoric acid fuel cell, a gaseous fuel such as hydrogen gas and a gaseous oxidant such as oxygen are supplied to both sides of the separation plate, sandwiching the separation plate.
If the separation plate has gas permeability, or if it is attacked by an oxidizing agent, electrolyte, etc., the above gases will mix, and as a result, the function as a phosphoric acid fuel cell will be impaired. Therefore, the separator plate is required to have excellent gas impermeability and resistance to attack by oxidizing agents and electrolytes. At the same time, it is naturally necessary to have high electrical conductivity and good mechanical properties such as bending strength since it is a device component. Against this background, carbon molded bodies disclosed in JP-A-54-20991 and JP-A-57-72273 have been proposed, but none of them completely satisfies the required characteristics as described above. I haven't gotten to the point yet. First, JP-A-1989
-20991 publication discloses that a fine powder of a cured phenolic resin and a phenol/aldehyde initial condensate are kneaded, molded and hardened, and then carbonized and fired to form an impermeable carbon molded product made essentially only of vitreous carbon. However, in the molded article obtained in this way, the resin shrinks significantly during the firing process, and firing cracks are likely to occur. For this reason, even though it is possible to obtain small plates with a thin wall thickness, it is possible to obtain a φ body with a thickness of 0.4 to 1.5, which is preferable as an actual separating plate.
It is practically impossible to obtain large plates. Even if it were possible to manufacture it as a molded article, it would have disadvantages such as poor gas impermeability, poor mechanical strength, and high electrical resistance due to the characteristics of glassy carbon. On the other hand, the latter, JP-A No. 57-72273, describes a method of adding a phenol resin liquid (binder) to graphite powder, molding it, and firing it at a high temperature to obtain an impermeable carbon molded body made entirely of graphite. is disclosed. However, in this method as well, it is not possible to prevent minute cracks during firing due to the difference in thermal shrinkage rate between the graphite and the binder in the molded body, as described above. In addition, several other types of molded bodies as described above are known which are made entirely of graphite. A method of obtaining an impermeable carbon molded body by impregnating the voids of a graphite molded body obtained (for example, by carbonization firing) with an impregnating agent such as pitch, tar, or resin, and carbonizing the impregnating agent by firing again. However, even with this method, it is not possible to prevent cracks caused by the difference in heat shrinkage rate between the molded article and the impregnating agent. Furthermore, since the carbon molded body obtained by the method disclosed in JP-A-57-72273 is substantially composed of graphite, it has poor impermeability to gases and other mechanical properties such as bending strength. It also has the disadvantage of inferior properties. Therefore, there is a strong desire for an impermeable carbon molded product that is excellent in gas impermeability, has good mechanical strength, chemical resistance, etc., and does not cause any particular inconvenience when molded.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

本発明は上述の様な事情に着目してなされたものであっ
て、気体等の不透過性に優れると共に耐酸化性及び機械
的性質の良好な不透過性炭素成形体を提供することを目
的とするものである。The present invention was made in view of the above-mentioned circumstances, and it is an object of the present invention to provide an impermeable carbon molded article that is excellent in impermeability to gases, etc., and has good oxidation resistance and mechanical properties. That is.

〔問題点を解決するための手段〕[Means for solving problems]

上記目的に適つ本発明の不透過性炭素成形体とは、主と
してガラス状炭素と黒鉛よりなるものであって残留水素
が０．０２’ｆｉ量チ以下であり且つ真比重が１．９以
下であることに要旨が存在するものである。The impermeable carbon molded article of the present invention suitable for the above purpose is mainly composed of glassy carbon and graphite, has residual hydrogen of 0.02'fi or less, and has a true specific gravity of 1.9 or less. There is a gist in that.

〔作用〕[Effect]

次に本発明を完成するに至る迄の研究経緯を辿シつつ本
発明の構成及び作用効果を説明していく。Next, the structure and effects of the present invention will be explained while tracing the research history that led to the completion of the present invention.

炭素成形体の気体に対する透過性は、該成形体のミクロ
構造に大きく影響されるものと考えられ、ミクロ構造上
の規則性が悪いときは気体の不透過性が上昇しミクロ構
造上の規則性が良いときは不透過性が低下するといり傾
向にある。本発明者等は該規則性が悪いものの代表例と
してガラス状炭素があること、又該規則性が良いものの
代表例として黒鉛があるととく注目し不透過性を向上さ
せる為には上記成形体におけるガラス状炭素の構成比率
を上ければよいのではないかとの指針を得た。It is thought that the gas permeability of a carbon molded body is greatly influenced by the microstructure of the molded body, and when the microstructure is not regular, the gas impermeability increases and the microstructure is not regular. When the opacity is good, the opacity tends to decrease. The present inventors have paid particular attention to the fact that glassy carbon is a typical example of a substance with poor regularity, and that graphite is a typical example of a substance with good regularity, and that in order to improve the impermeability, the above-mentioned molded body is We obtained a guideline that it would be better to increase the composition ratio of glassy carbon in .

ところでガラス状炭素の構成比率を上げていくと気体不
透過性・の向上だけでなく曲げ強度等の機械的強度も増
加することが分かったが、一方では成形体における耐酸
化性の低下を招くことも見出され、種々検討の結果上記
耐酸化性の低下原因はガラス状炭素のマトリックス中に
含まれる水素にあることが分かった。従って耐酸化性の
種度を知る指標としてはガラス状炭素中の水素含有量が
重要であ）・水素含有量をＺ値以下に押えることができ
１ば耐酸化性の低下を防止することが可能であることを
知ったが、ガラス状炭素中の該水素だけを選択的に調節
することははなはだ難しいので本発明の成形体において
社該成形体中の水素含有率を調節することによって耐酸
化性の調節を行なうこととした。By the way, it was found that increasing the composition ratio of glassy carbon not only improves gas impermeability but also increases mechanical strength such as bending strength, but on the other hand, it leads to a decrease in oxidation resistance in the molded product. As a result of various studies, it was found that the cause of the above-mentioned decrease in oxidation resistance was hydrogen contained in the matrix of glassy carbon. Therefore, the hydrogen content in glassy carbon is important as an indicator of the degree of oxidation resistance.) If the hydrogen content can be kept below the Z value, a decrease in oxidation resistance can be prevented. However, it is very difficult to selectively control only the hydrogen in the glassy carbon, so in the molded product of the present invention, oxidation resistance can be improved by adjusting the hydrogen content in the molded product. We decided to adjust the sex.

一方耐酸化性を向上させる目的で成形体におけるガラス
状炭素の含有比率を低下させて黒鉛の含有比率を上げて
いくと、前述の如く気体の不透過性が悪化すると共に機
械的強度も低下することになシ、黒鉛の比率を高くする
ことにも限界があるととを知った。そこでガラス状炭素
の含有率の下限を得る為の指標として本発明者等は成形
体の真比重を用いることとした。なんとなれば該真比重
は黒鉛とガラス状炭素との比率によって決定されるから
である。On the other hand, if the content ratio of glassy carbon is lowered and the content ratio of graphite is increased in the molded body for the purpose of improving oxidation resistance, the gas impermeability deteriorates and the mechanical strength also decreases, as mentioned above. In particular, I learned that there is a limit to increasing the proportion of graphite. Therefore, the present inventors decided to use the true specific gravity of the molded body as an index for obtaining the lower limit of the glassy carbon content. This is because the true specific gravity is determined by the ratio of graphite and glassy carbon.

本発明は、以上説明した様な基本的な知見に基づいて鋭
意研究を重ねた結果完成するに至ったものである。すな
わち水素含有率が０．０２重量−以下であり且つ真比重
が１，９以下になる様に調節された不透過性成形体は、
不透過性が優れることはもとよシ曲げ１度等の機械的性
質及び耐酸化性も粉末、黒鉛粉末並びに熱硬化性樹脂液
からなる組成物を所要形状に成形し、乾燥し、硬化させ
た後、非酸化性雰囲気下もしくは真空中に炭化焼成もし
くは一部黒鉛化することによって製造されるものである
が、ここＫいう熱硬化性樹脂とは、非酸化性雰囲気中で
の８００℃以上の温度における炭化焼成によってガラス
質炭素に変化し、２５００℃以上の高温でも黒鉛化しに
くい難黒鉛化性のものが好ましく、通常フェノール系樹
脂、フラン系樹脂、キシレン系樹脂、メラミン系樹脂、
アニリン系樹脂等の樹脂粉末が用いられるが、特にフェ
ノール系樹脂の粉末が好んで用いられる。また熱硬化性
樹脂液としては、例えばフェノール系樹脂。The present invention has been completed as a result of intensive research based on the basic knowledge as explained above. In other words, an impermeable molded article whose hydrogen content is adjusted to be 0.02 weight or less and true specific gravity 1.9 or less,
Not only does it have excellent impermeability, but it also has excellent mechanical properties such as 1 degree bending and oxidation resistance.A composition consisting of powder, graphite powder, and thermosetting resin liquid is molded into a desired shape, dried, and hardened. After that, it is produced by carbonization firing or partial graphitization in a non-oxidizing atmosphere or vacuum. Non-graphitizable materials that change into glassy carbon by carbonization firing at a temperature of 2,500°C or higher and are difficult to graphitize even at high temperatures of 2,500°C or higher are preferred, and are usually phenolic resins, furan resins, xylene resins, melamine resins,
Resin powders such as aniline resins are used, and phenol resin powders are particularly preferred. Further, as the thermosetting resin liquid, for example, phenolic resin is used.

キシレン系樹脂、メラミン系樹脂、尿素系樹脂。Xylene resin, melamine resin, urea resin.

エポキシ系樹脂、フラン系樹脂等の水性又は有機性の接
着剤が用いられる。尚樹脂液には溶液のほか乳濁液や懸
濁液も含まれる。本発明においては乾燥の便宜上水性の
樹脂液が好んで用いられるが、特に制限がある訳ではな
い。上記熱硬化性樹脂粉末及び樹脂液は単独あるいは２
種以上の混合物として用いることができるが、熱硬化性
樹脂粉末と樹脂液中の樹脂成分とは同じ樹脂であること
が望ましく又黒鉛化を促進する不純物は可及的に少ない
ことが望まれる。該樹脂液は、熱硬化性樹脂粉末と黒鉛
との混線及び所要形状への成形を容易にするという役割
だけでなく加熱硬化後の焼成によって熱硬化性樹脂と同
様自から非晶質のガラス質炭素となるものでありマトリ
ツクスの一部を形成する。尚この様にして得られる成形
体について、その強度を一層高める為、成形体の炭素マ
トリックスに対しで良好な結合性を有する物質例えば炭
化はう素、炭化けい素、炭化チタン、炭化タングステン
等の金属酸化物、炭素繊維といった添加物過程について
説明したが、該過程における特に焼は、約６００℃に至
る進数１０　℃／ｈｒ程度の昇温速度で行なわれること
が望ましい。この後上記範囲又はこれよ勺大きい昇温速
度で所定の炭化焼成温度まで加熱し所定時間焼成するこ
とＫよって本発明の不透過性炭素成形体を得る。上記炭
化焼成温度は、熱硬化性樹脂粉末、樹脂液と黒鉛及び黒
鉛の各比率によって異なるが少なくと４１４００℃に昇
温されることを特徴とする特に１８００〜２４００℃の
範囲で焼成されることが好まし−が、７００℃以上の温
度で処理した後真空算囲気中で焼成し樹脂の一部を黒鉛
化することは更に好ましい方法である。焼成に必要な時
間については、基本的には成形体の形状や寸法等によっ
て決められるが、成形体中の水素量が０．０２重量％以
下とな）且つ真比重が１．９以下になるに足る時間であ
ればよく、通常数十〜百数十時間である。以上説明した
様な方法を用いると焼成時に割れを生じることなく所望
形状の不透過性炭素成形体を得ることができる。Aqueous or organic adhesives such as epoxy resins and furan resins are used. Note that the resin liquid includes not only solutions but also emulsions and suspensions. In the present invention, an aqueous resin liquid is preferably used for convenience of drying, but there is no particular limitation. The above thermosetting resin powder and resin liquid may be used alone or in combination.
Although it can be used as a mixture of more than one species, it is desirable that the thermosetting resin powder and the resin component in the resin liquid are the same resin, and it is desirable that the amount of impurities that promote graphitization be as small as possible. The resin liquid not only plays the role of making it easier to mix the thermosetting resin powder and graphite and molding it into the desired shape, but also to make it into an amorphous glassy substance like the thermosetting resin by baking after heating and curing. It becomes carbon and forms part of the matrix. In order to further increase the strength of the compact obtained in this manner, a substance having good bonding properties to the carbon matrix of the compact, such as boron carbide, silicon carbide, titanium carbide, tungsten carbide, etc. Although the process of adding metal oxides and carbon fibers has been described, it is desirable that the calcination in this process is carried out at a heating rate of about 10°C/hr up to about 600°C. Thereafter, the impermeable carbon molded body of the present invention is obtained by heating to a predetermined carbonization firing temperature within the above range or at a higher heating rate and firing for a predetermined time. The carbonization firing temperature varies depending on the thermosetting resin powder, resin liquid, graphite, and each ratio of graphite, but is characterized by being raised to at least 41,400°C. In particular, firing is performed in the range of 1,800 to 2,400°C. However, a more preferred method is to treat the resin at a temperature of 700° C. or higher and then sinter it in a vacuum atmosphere to graphitize a portion of the resin. The time required for firing is basically determined by the shape and dimensions of the molded body, but the amount of hydrogen in the molded body must be 0.02% by weight or less) and the true specific gravity must be 1.9 or less. It is sufficient as long as the time is sufficient, and is usually several tens to hundreds of hours. By using the method described above, an impermeable carbon molded body having a desired shape can be obtained without cracking during firing.

以下に実施例を挙けて本発明を説明するが、本発明はこ
れら実施例によプ何ら限定されるものではない。The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

〔実施例〕〔Example〕

実施例１ フェノールホルムアルデヒド樹脂粉末と固定炭素９９％
以上の黒鉛粉末とを重量比で８２：１８になる様に配合
しフェノール樹脂液（濃度５０チ）Ｋて均一に混練し薄
板状に成形した。これを４０℃の温度で３時間乾燥した
後、１１０℃の温度に６時間加熱して上記熱硬化性樹脂
を硬化させた。Example 1 Phenol formaldehyde resin powder and 99% fixed carbon
The above graphite powder was blended in a weight ratio of 82:18, kneaded uniformly with phenol resin liquid (concentration 50%), and formed into a thin plate. This was dried at a temperature of 40°C for 3 hours, and then heated at a temperature of 110°C for 6 hours to harden the thermosetting resin.

次いで一次焼成炉に装入し、窒素雰囲気下で７００℃ま
で２０℃／ｈｒ＊７００〜１０００℃では８０℃／ｈｒ
の加温速度加熱した後、該温度（ｔｏｏｏ℃）で２時間
保持し冷やして取出す。この後再度２次焼成炉に装入し
真空雰囲気下で第１表に示す温度まで７０℃／ｈｒの昇
温速度で加熱し夫々の温度に４時間保持して厚み約０．
９ｍｍ　？　１５０＋ｎｍ角の不透過性炭素成形体を得
た。Next, it is charged into a primary firing furnace and heated at 20°C/hr up to 700°C under a nitrogen atmosphere *80°C/hr from 700 to 1000°C.
After heating at a heating rate of , it is held at the temperature (too much degrees Celsius) for 2 hours, cooled, and taken out. Thereafter, it was charged into the secondary firing furnace again and heated under a vacuum atmosphere to the temperatures shown in Table 1 at a heating rate of 70°C/hr, and maintained at each temperature for 4 hours until the thickness was about 0.
9mm? A 150+ nm square impermeable carbon molded body was obtained.

この様にして得られた成形体の夫々について、水素透過
性、真比重（ＪＩＳＲ７２１２に示す方法による）、残
留水素量、成形体の縦方向の電気抵抗。For each of the molded bodies obtained in this way, hydrogen permeability, true specific gravity (according to the method shown in JISR7212), amount of residual hydrogen, and electrical resistance of the molded body in the longitudinal direction were measured.

曲げ強度を測定した。結果を第１表に示す。Bending strength was measured. The results are shown in Table 1.

また上記第１表における１３００°Ｃ，＋５００℃。Also, 1300°C and +500°C in Table 1 above.

２３００℃のサンプルについて縦２０　ａｍｘ　、　横
８０　ｍｍのサンプルを切シ出し、これの５００℃炉内
における５％酸化減耗時間、２５０℃炉内における２０
００時間酸化減耗率、縦方向の曲げ強度を測定した、そ
の結果を第２表匝示す。A 2300°C sample was cut out with a length of 20 amx and a width of 80 mm.
The 00 hour oxidation loss rate and longitudinal bending strength were measured, and the results are shown in Table 2.

実施例２ フェノールホルムアルデヒド樹脂粉末と固定炭素９９チ
以上の黒鉛粉末との比率を第３表に示す割合で配合し、
最高温度が夫々１８００℃となる様にして焼成すること
以外は実施例１と同様の条件にして不透過性炭素成形体
を得た。これら成形体の夫々について窒素透過率、真比
重、残留水素量、電気抵抗１曲げ強度を測定した。それ
らの結〔発明の効果〕 本発明は以上の様に構成されているので、気体等の不透
過性に優れると共に耐酸化性及び機械的性質の良好な不
透過性炭素成形体を得ることができる。Example 2 Phenol formaldehyde resin powder and graphite powder with fixed carbon of 99 or more were blended at the ratio shown in Table 3,
An impermeable carbon molded body was obtained under the same conditions as in Example 1 except that the firing was performed at a maximum temperature of 1800°C. The nitrogen permeability, true specific gravity, residual hydrogen amount, and electrical resistance 1 bending strength were measured for each of these molded bodies. Results [Effects of the Invention] Since the present invention is configured as described above, it is possible to obtain an impermeable carbon molded body that is excellent in impermeability to gases, etc., and has good oxidation resistance and mechanical properties. can.

手続補正書 昭和６０年１１月　７日 特許庁長官　宇　買　道　部　殿 ２、発明の名称 不透過性炭素成形体 ３　補正をする者 事件との関係　　特許出願人 神戸市中央区脇浜町１丁目３番１８号 （１１９）株式会社神戸製鋼所 代表者　　牧　　冬　彦 ４、代理人 ５、補正命令の日付 昭和　年　月　日　　（発送日） −−−へ、 別紙「正鎮表」の通り訂正します。Procedural amendment November 7, 1985 Director General of the Patent Office 2. Name of the invention Impermeable carbon molded body 3 Person making the amendment Relationship to the case Patent applicant 1-3-18 Wakihamacho, Chuo-ku, Kobe City (119) Kobe Steel, Ltd. Representative Fuyuhiko Maki 4. Agent 5. Date of amendment order Showa year month/day (shipment date) ---to, We will make the corrections as per the attached “Seijin table”.

正　　誤　　表errata

Claims (1)

【特許請求の範囲】[Claims] （１）主にガラス状炭素と黒鉛よりなる炭素成形体であ
つて、該炭素成形体の残留水素が０．０２重量％以下で
あり且つ真比重が１．９以下であることを特徴とする不
透過性炭素成形体。(1) A carbon molded body mainly composed of glassy carbon and graphite, characterized in that the residual hydrogen of the carbon molded body is 0.02% by weight or less, and the true specific gravity is 1.9 or less. Impermeable carbon molded body.