JPS64486B2

JPS64486B2 -

Info

Publication number: JPS64486B2
Application number: JP60121589A
Authority: JP
Inventors: Hiroyasu Ogawa; Kenji Shimazaki; Fumito Morikawa
Original assignee: Toho Rayon Co Ltd
Current assignee: Teijin Ltd
Priority date: 1985-06-06
Filing date: 1985-06-06
Publication date: 1989-01-06
Also published as: JPS61282430A

Description

[Detailed description of the invention]

（産業上の利用分野）本発明は、比表面積1200m²／ｇ以上、細孔容積
0.6c.c.／ｇ以上、平均細孔直径25Å以上で、なお
かつ高強度を有する活性炭素繊維（繊維状活性炭
とも呼ばれる。以下ACFと略記する。）の製造法
に関するものである。ここに得られたACFは吸着材等の用途に供さ
れる。（従来技術及び問題点）活性炭は古くから広く使用されてきたが、最近
開発されたACFは、取扱性、吸着特性の点で従
来の粒状、粉状の活性炭に比較し多くの優れた面
を有し、その利用範囲も拡大しつつある。この
ACFは、レーヨン、フエノール系繊維、アクリ
ル系繊維などの有機繊維から製造されており、特
にアクリル系繊維を原料とした、いわゆるアクリ
ル系ACFは繊維強度が高く、加工性が優れてい
るためフエルト状、紙状のみならず、紡績糸、織
物に加工でき、その需要は拡大しつつある。このようなACFの吸着能力は、ガス成分の吸
着の場合、ACFの比表面積の大きさで吸着量が
決まることがある。ベンゼンやアセトンなどの蒸気の吸着がその例
である。一方、液相成分の吸着では、比表面積の大小だ
けでなく、ACFの細孔容積や平均細孔直径の大
きさが吸着量に少なからず影響を与える。例え
ば、モデル物質として用いられるメチレンブルー
やビタミンB₁₂のような分子量の高い物質のACF
への吸着は、その比表面積よりも細孔容積や平均
細孔直径の大小に強く影響される。このように多
方面にわたる用途に充分に対応するためには、比
表面積が大きく、なおかつ、細孔容積や平均細孔
直径も大きいようなACFが要求される。しかし
ながら、通常市場に出ているアクリル系ACFは、
比表面積700〜1100m²／ｇ、細孔容積0.25〜0.6
c.c.／ｇ、平均細孔直径18〜24Åであり、このもの
は優れた機械的特性に基ずく加工性を有するにも
かかわらず、高い分子量の物質を含む液相系での
処理などには不向きであつた。従来、アクリル系
ACFにおいても、比表面積1200〜200m²／ｇのも
のも造られているが、本発明者らの検討によれ
ば、それらは微粉末の発生等の問題があり、商品
価値の乏しいものであつた。また、ACFの細孔
容積、平均細孔直径を拡大するための方法とし
て、特定の構造特性を有するACFに水溶性塩類
などを添着してのち賦活ガスにて処理する方法
（特開昭58−18418号公報）が提案されている。し
かしながら、この方法で得られたACFは、細孔
容積や平均細孔直径が拡大するものの、添着賦活
後、ACFの繊維強度が著しく低下し、本来のア
クリル系ACFの優れた機械的特性が生かされに
くかつた。本発明者らは、これらの事情に鑑み、鋭意研究
の結果、比表面積、細孔容積、平均細孔直径いず
れもが大きな値をもち、しかも機械的強度の面で
も優れた活性炭素繊維を得る製造法を見出し、本
発明に到達した。（発明の構成及び効果）すなわち、本発明は、アクリル系繊維を酸化性
雰囲気中、200〜400℃で酸化処理した後、
H₂O／CO₂＝1.5以上（モル比）の賦活ガスを用
いて１次賦活をし、更にH₂O／CO₂＝1.4以下
（モル比）の賦活ガスを用いて２次賦活をするこ
とを特徴とする比表面積1200m²／ｇ以上、細孔容
積0.6c.c.／ｇ以上、平均細孔直径25Å以上のアク
リル系活性炭素繊維の製造法である。このような方法によつてアクリル系ACFを製
造すると、分子量の高い物質に対する吸着能に優
れ、液相系吸着に適した、しかも機械的強度の高
いACFを得ることができる。本発明において、活性炭素繊維の比表面積は、
相対圧0.3におけるN₂ガスの吸脱着からBET1点
法により測定した値であり、細孔容積も相対圧
0.96におけるN₂ガスの気体吸着法により測定し
た値である。また、平均細孔直径は細孔の形が円
筒形であると仮定し、比表面積と細孔容積の値か
ら次式によつて算出したものである。ｄ＝40000V／Ｓここで、ｄ：平均細孔直径（Å）Ｖ：細孔容積（c.c.／ｇ）Ｓ：比表面積（m²／ｇ）本発明においてアクリル系繊維とは、アクリロ
ニトリルを少なくとも60重量％以上、好ましくは
85〜98重量％を含む重合体又は共重合体より得た
繊維である。この場合、コモノマーとしてはアク
リル酸、メタクリル酸、アリルスルホン酸又はこ
れらの塩類、エステル類、酸クロライド、酸アミ
ド類、ビニルアミドのｎ−置換誘導体、塩化ビニ
ル、塩化ビニリデン、α−クロロアクリロニトリ
ル、ビニルピリジン類、ビニルベンゼンスルホン
酸、ビニルスルホン酸及びそのアルカリ土類金属
塩（Mg、Ca塩など）がある。また、アクリロニ
トリル重合体の変性重合体、アクリロニトリル重
合体及び共重合体の混合物から得られる繊維も使
用される。アクリロニトリル系繊維の繊度は特に制限され
ないが、0.5d〜15d、特に1d〜7dのものが好まし
い。0.5dより細い場合、繊維強力が低く繊維の切
断が起り易い。逆に、15dより太くなると酸化速
度が遅く、また活性炭素繊維としたときに、強
度、弾性率が低くなり賦活収率が低下する傾向が
ある。アクリル系繊維には、酸化速度を速め、なおか
つ酸化処理後の繊維の加工性を高めることを目的
として、ポリ塩化アルミニウムに代表される水溶
性塩基性アルミニウム複合塩を添着することもで
きる（特開昭58−106924号公報）。アクリロニトリル系繊維の酸化処理は、該繊維
を酸化性雰囲気中で200〜400℃にて熱処理するこ
とによつて行われる。酸化性雰囲気の媒体として
は、空気、酸素、塩化水素、亜硫酸ガス若しくは
これらの混合ガス又はこれらと不活性ガスとの混
合ガスが用いられるが、主として空気及び空気と
窒素の混合ガスが経済性、工程の安定性の点から
最適である。耐炎化処理すなわち酸化処理におけ
る酸化性雰囲気の酸素濃度は、0.2〜35.0容量％
の範囲が最も効果的である。酸化処理は２段に分
け、前段の酸化は酸素濃度20〜30容量％の媒体中
で、後段の酸化は酸素濃度0.5〜9.0％の媒体中で
行うのが好ましい。酸化処理に要する時間は0.5
〜30時間、好ましくは1.0〜10時間であり、酸素
結合量が８％以上になるまで行う。酸素結合量が
この値より低い場合、耐炎化度も低く、高温賦活
においてトウの切断が生じ、また、賦活収率も低
下する。酸素結合量は好ましくは10.0％以上であ
り、ほぼ23〜25％程度まで高めることができる。
酸化温度は200〜400℃で行われ、最適温度は酸化
媒体の種類及びリンの添着状況により多少異なる
が、225〜350℃の範囲である。酸化処理時におけ
る張力は、繊維の自由収縮率に対し40〜85％、特
に50〜60％の収縮条件下にて行うのが、ACFの
強度、弾性率を高く維持する上において好まし
い。以上の如くして得られた酸化繊維は次の２段階
の賦活工程に供される。賦活工程に供される繊維
形態は、トウ状、粗紡糸、精紡糸、フエルト、編
織物のいずれであつてもよい。１次賦活では、賦活雰囲気にスチーム（H₂O）
100％又はスチーム（H₂O）とCO₂を主成分とし
た混合ガスを用いる。この場合スチーム（H₂O）
とCO₂の組成比率はH₂O／CO₂＝1.5以上（モル
比）であることが必須条件である。この比が1.5
未満の場合、賦活速度が著しく低下するとともに
賦活時の熱履歴が大きくなり賦活収率の低下を招
き好ましくない。スチーム（CO₂）とCO₂以外に
混入可能なガスとしては、N₂、He、Ar、NH₃、
CO等の１種又は２種以上の混合ガスがあるが、
全成分に対するスチーム（H₂O）の容積％は30
％を下回わつてはならない。スチームの容量％が
これ以下の場合、賦活速度が遅れるとともに、炭
素化が進み易く、後述する２次賦活時に高比表面
積のACFが得にくくなる。賦活ガスの使用量
（重量）は、通常１次あるいは２次賦活ともに、
おのおの賦活すべき原料（重量）当り、10〜50倍
必要である。賦活ガス量が10倍未満の場合、賦活
速度が遅れ、逆に50倍を越すと、賦活収率の低下
を招き、いずれも好ましくない。賦活温度は500
〜1400℃が適当である。賦活温度が500℃未満で
は賦活速度の低下が著しく、逆に1400℃を越すと
賦活時にACFが灰化し易く、いずれも適当でな
い。好ましくは850〜1000℃である。賦活時間は
賦活温度により異なるが、５〜100分が好ましい。
また、比表面積は少くとも700m²／ｇまで賦活し
ておくことが、２次賦活を短時間にて効果的に行
うために有効である。２次賦活においても賦活雰囲気には主としてス
チームとCO₂を用いる。しかしながら、その組成
比は１次賦活の場合とは異なり、H₂O／CO₂＝
1.4以下（モル比）の賦活ガスを用いる。この場
合、組成比が1.4を越すと、２次賦活時にACFの
繊維強度の低下や灰化を招き好ましくない。混合
可能な他のガス成分は１次賦活の場合と同様であ
るが、CO₂の容積％は全成分の25％を下廻つては
ならない。CO₂容量％が25％を下廻わつた場合、
２次賦活時の賦活速度が著しく低下し好ましくな
い。賦活温度は800〜1500℃が適当である。賦活
温度がこの範囲外にある場合は、１次賦活時の場
合と同様な理由により適当でない。好ましくは
900〜1100℃である。賦活時間は賦活温度により
異なるが、１〜120分程度が好ましい。以上の条件において、１次賦活及び２次賦活を
行い、本発明の目的とする構造特性を有する
ACFを得る。このようにして得られたACFは、
下表に示す通り、低分子量の物質の気相での吸着
（例としベンゼン吸着を示す）のみならず、ビタ
ミンB₁₂のような比較的高い分子量を有する物質
の液相吸着においても優れた吸着能を示す。 (Industrial Application Field) The present invention applies to specific surface areas of 1200 m ² /g or more, pore volumes
The present invention relates to a method for producing activated carbon fiber (also called fibrous activated carbon, hereinafter abbreviated as ACF), which has an average pore diameter of 0.6 cc/g or more, an average pore diameter of 25 Å or more, and high strength. The ACF obtained here is used for uses such as adsorbents. (Prior art and problems) Activated carbon has been widely used for a long time, but the recently developed ACF has many advantages over conventional granular and powder activated carbon in terms of ease of handling and adsorption properties. The scope of its use is also expanding. this
ACF is manufactured from organic fibers such as rayon, phenolic fibers, and acrylic fibers.In particular, acrylic ACF made from acrylic fibers has high fiber strength and excellent processability, so it is shaped like felt. It can be processed into not only paper but also spun yarn and textiles, and the demand for it is increasing. When adsorbing gas components, the adsorption capacity of ACF may be determined by the specific surface area of ACF. An example is the adsorption of vapors such as benzene and acetone. On the other hand, in adsorption of liquid phase components, not only the specific surface area but also the pore volume and average pore diameter of the ACF have a considerable influence on the adsorption amount. For example, ACF of high molecular weight substances such as methylene blue and vitamin _B12 used as model substances.
Adsorption to is more strongly influenced by the pore volume and average pore diameter than by its specific surface area. In order to be fully applicable to such a wide variety of uses, ACFs that have a large specific surface area, as well as a large pore volume and average pore diameter are required. However, the acrylic ACF normally available on the market is
Specific surface area 700-1100m ² /g, pore volume 0.25-0.6
cc/g, average pore diameter of 18 to 24 Å, and although this material has processability based on its excellent mechanical properties, it is unsuitable for processing in liquid phase systems containing high molecular weight substances. It was hot. Conventionally, acrylic
ACFs with a specific surface area of 1200 to 200 m ² /g are also manufactured, but according to the inventors' studies, they have problems such as the generation of fine powder and have poor commercial value. Ta. In addition, as a method for expanding the pore volume and average pore diameter of ACF, a method of impregnating ACF with specific structural characteristics with water-soluble salts, etc., and then treating it with an activation gas (JP-A-58-1999) 18418) has been proposed. However, although the pore volume and average pore diameter of the ACF obtained by this method are expanded, the fiber strength of the ACF decreases significantly after impregnation activation, and the original excellent mechanical properties of acrylic ACF are not fully utilized. It was difficult to be ignored. In view of these circumstances, the present inventors have conducted extensive research to obtain activated carbon fibers that have large specific surface area, pore volume, and average pore diameter, and are also excellent in mechanical strength. We discovered a manufacturing method and arrived at the present invention. (Structure and effects of the invention) That is, the present invention provides acrylic fibers that are oxidized at 200 to 400°C in an oxidizing atmosphere, and then
Perform primary activation using an activation gas with H ₂ O / CO 2 = 1.5 or more (molar ratio), and then perform secondary activation using an activation gas with H ₂ _O / CO ₂ = 1.4 or less (molar ratio). This is a method for producing an acrylic activated carbon fiber having a specific surface area of 1200 m ² /g or more, a pore volume of 0.6 cc/g or more, and an average pore diameter of 25 Å or more. When acrylic ACF is produced by such a method, it is possible to obtain an ACF that has excellent adsorption ability for substances with high molecular weight, is suitable for liquid phase adsorption, and has high mechanical strength. In the present invention, the specific surface area of activated carbon fiber is
This is a value measured using the BET one-point method from adsorption and desorption of _N2 gas at a relative pressure of 0.3, and the pore volume also depends on the relative pressure.
This is a value measured by the gas adsorption method of N ₂ gas at 0.96. Further, the average pore diameter is calculated by the following formula from the values of specific surface area and pore volume, assuming that the pores are cylindrical in shape. d=40000V/S Here, d: Average pore diameter (Å) V: Pore volume (cc/g) S: Specific surface area (m ² /g) In the present invention, acrylic fibers are those containing at least 60% acrylonitrile. % by weight or more, preferably
It is a fiber obtained from a polymer or copolymer containing 85 to 98% by weight. In this case, comonomers include acrylic acid, methacrylic acid, allylsulfonic acid or their salts, esters, acid chlorides, acid amides, n-substituted derivatives of vinylamide, vinyl chloride, vinylidene chloride, α-chloroacrylonitrile, vinylpyridine. vinylbenzenesulfonic acid, vinylsulfonic acid and its alkaline earth metal salts (Mg, Ca salts, etc.). Also used are fibers obtained from modified polymers of acrylonitrile polymers, mixtures of acrylonitrile polymers and copolymers. The fineness of the acrylonitrile fiber is not particularly limited, but is preferably 0.5 d to 15 d, particularly 1 d to 7 d. If it is thinner than 0.5d, the fiber strength is low and fiber breakage is likely to occur. On the other hand, when the fiber is thicker than 15d, the oxidation rate is slow, and when it is made into activated carbon fiber, the strength and elastic modulus tend to be low and the activation yield tends to be low. Acrylic fibers can be impregnated with water-soluble basic aluminum complex salts, such as polyaluminum chloride, in order to speed up the oxidation rate and improve the processability of the fibers after oxidation treatment. Publication No. 58-106924). The oxidation treatment of acrylonitrile fibers is carried out by heat treating the fibers at 200 to 400°C in an oxidizing atmosphere. As the medium for the oxidizing atmosphere, air, oxygen, hydrogen chloride, sulfur dioxide gas, a mixture of these gases, or a mixture of these gases and an inert gas is used, but air and a mixture of air and nitrogen are mainly used because of their economic efficiency and It is optimal from the point of view of process stability. The oxygen concentration in the oxidizing atmosphere during flameproofing treatment, that is, oxidation treatment, is 0.2 to 35.0% by volume.
range is most effective. It is preferable that the oxidation treatment be carried out in two stages, with the first stage oxidation being carried out in a medium having an oxygen concentration of 20 to 30% by volume, and the second stage oxidation being carried out in a medium having an oxygen concentration of 0.5 to 9.0%. The time required for oxidation treatment is 0.5
It is carried out for ~30 hours, preferably 1.0 to 10 hours, until the amount of oxygen binding reaches 8% or more. When the amount of oxygen binding is lower than this value, the degree of flame resistance is also low, tow breakage occurs during high temperature activation, and the activation yield also decreases. The amount of oxygen bonding is preferably 10.0% or more, and can be increased to about 23 to 25%.
The oxidation temperature is 200 to 400°C, and the optimum temperature is in the range of 225 to 350°C, although it varies somewhat depending on the type of oxidation medium and the state of phosphorus impregnation. The tension during the oxidation treatment is preferably 40 to 85%, particularly 50 to 60%, of the free contraction rate of the fibers in order to maintain high strength and elastic modulus of the ACF. The oxidized fibers obtained as described above are subjected to the following two-stage activation process. The fiber form to be subjected to the activation step may be in the form of tow, roving, spun yarn, felt, or knitted fabric. In the primary activation, steam (H ₂ O) is added to the activation atmosphere.
Use 100% or a mixed gas containing steam (H ₂ O) and CO ₂ as main components. In this case steam (H ₂ O)
It is essential that the composition ratio of CO ₂ and H ₂ O/CO ₂ is 1.5 or more (molar ratio). This ratio is 1.5
If it is less than 1, the activation rate will drop significantly and the thermal history during activation will increase, leading to a decrease in activation yield, which is not preferable. Gases that can be mixed with steam (CO ₂ ) and CO ₂ include N ₂ , He, Ar, NH ₃ ,
There is one type of gas such as CO or a mixture of two or more types,
The volume % of steam (H ₂ O) to all components is 30
% shall not be exceeded. When the steam volume percentage is less than this, the activation rate is delayed and carbonization tends to proceed, making it difficult to obtain an ACF with a high specific surface area during the secondary activation described below. The amount (weight) of activation gas used is usually for both primary and secondary activation.
It is necessary to use 10 to 50 times more per raw material (weight) to be activated. If the amount of activation gas is less than 10 times, the activation rate will be delayed, and if it exceeds 50 times, the activation yield will decrease, both of which are unfavorable. Activation temperature is 500
~1400℃ is suitable. If the activation temperature is less than 500°C, the activation rate will drop significantly, and if it exceeds 1400°C, ACF will easily ash during activation, so neither is suitable. Preferably it is 850-1000°C. The activation time varies depending on the activation temperature, but is preferably 5 to 100 minutes.
Further, it is effective to activate the specific surface area to at least 700 m ² /g in order to effectively perform the secondary activation in a short time. In the secondary activation, steam and CO ₂ are mainly used for the activation atmosphere. However, the composition ratio is different from that of the primary activation, H ₂ O / CO ₂ =
Use an activating gas with a molar ratio of 1.4 or less. In this case, if the composition ratio exceeds 1.4, it is not preferable because it causes a decrease in ACF fiber strength and ashing during secondary activation. The other gas components that can be mixed are the same as for the primary activation, but the volume percent of CO ₂ must not be less than 25% of the total components. If CO ₂ volume% falls below 25%,
This is not preferable because the activation rate during secondary activation is significantly reduced. A suitable activation temperature is 800 to 1500°C. If the activation temperature is outside this range, it is not suitable for the same reason as in the case of primary activation. Preferably
The temperature is 900-1100℃. The activation time varies depending on the activation temperature, but is preferably about 1 to 120 minutes. Under the above conditions, primary activation and secondary activation are performed, and the structure has the structural characteristics targeted by the present invention.
Get ACF. The ACF obtained in this way is
As shown in the table below, the adsorption is excellent not only in gas phase adsorption of low molecular weight substances (benzene adsorption is shown as an example), but also in liquid phase adsorption of relatively high molecular weight substances such as vitamin _B12 . Show ability.

【表】（実施例）以下実施例により本発明を更に詳しく説明する
が、本発明は、かかる実施例によつて限定をうけ
るものではない。例中％は重量基準である。実施例１アクリロニトリル91.5％、メチルメタクリレー
ト7.5％、アクリルアミド1.0％よりなる共重合組
成の54万デニールのダル系（TiO₂、0.1％）トウ
（単糸繊度1.5d）を塩基性ポリ塩化アルミニウム
の水溶液にて連続的に処理し、Alとして0.13％含
有せしめた後、空気中で240℃、２時間、更に270
℃で0.5時間、自由収縮率の75〜80％になるよう
な張力で酸化処理し、酸素結合量18.0％の酸化繊
維を得た。更に、この処理繊維をリン酸アンモニ
ウム水溶液にて処理し、リン酸として0.45％含有
せしめた。この繊維を第１表に示したテストNo.１
〜９の諸条件で、１次、２次賦活を行い、第２表
に示す如き結果を得た。[Table] (Examples) The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited by these Examples. In the examples, percentages are by weight. Example 1 A 540,000 denier dull (TiO ₂ , 0.1%) tow (single yarn fineness 1.5d) with a copolymer composition consisting of 91.5% acrylonitrile, 7.5% methyl methacrylate, and 1.0% acrylamide was added to an aqueous solution of basic polyaluminum chloride. After continuous treatment at 240°C for 2 hours in air to contain 0.13% Al,
Oxidized fibers with an oxygen bond content of 18.0% were obtained by oxidation treatment at ℃ for 0.5 hours under tension such that the free shrinkage rate was 75 to 80%. Furthermore, this treated fiber was treated with an ammonium phosphate aqueous solution to contain 0.45% phosphoric acid. Test No. 1 for this fiber shown in Table 1
The primary and secondary activations were carried out under the conditions of ~9 to 9, and the results shown in Table 2 were obtained.

【表】【table】

【table】

Claims

[Claims]

1. Acrylic fibers in an oxidizing atmosphere at 200-400℃
_After oxidation _treatment with
Specific surface area characterized by performing secondary activation using an activation gas of H ₂ O / CO ₂ = 1.4 or less (molar ratio)
A method for producing acrylic activated carbon fiber having a particle size of 1200 m ² /g or more, a pore volume of 0.6 cc/g or more, and an average pore diameter of 25 Å or more.