【発明の詳細な説明】[Detailed description of the invention]
本発明は抄紙用繊維状活性炭に関するものであ
る。詳しくは、抄紙時に水に対する分散性に優
れ、しかも叩解又は離解時に繊維の損傷のない抄
紙用繊維状活性炭を提供するものである。繊維状
活性炭を使用したパルプその他の繊維材料との混
抄紙は提案されているが、従来の繊維状活性炭は
水に対する分散性が悪く、水中で繊維が未開繊の
塊で凝集するため、パルプその他の繊維材料とは
均一に混合し難く、その結果、吸着性の斑、坪量
の斑、紙強度の不足等が生じ実用性の面で問題が
あつた。
この両者を均一に混合するためにはビーター、
リフアイナー等により叩解又は離解を十分行なう
必要があるが、繊維状活性炭は脆弱であるため、
叩解又は離解時に繊維が損傷を受け粉末化し易
く、抄紙時脱落し易い。このため、混抄紙におけ
る繊維状活性炭含有率が低下し、混抄率が変動し
易いという問題がある。
本発明者等は、上記の如き問題を解消するため
に、抄紙用に使用して最適な繊維状活性炭の特性
につき種々検討の結果本発明に至つたものであ
る。
すなわち、本発明は繊維長２〜15mmの一方向性
繊維束で、且つ水分率が飽和水分率（25℃、
RH80％）の1.5〜７倍に保持されてなる抄紙用繊
維状活性炭密封体である。
このような繊維状活性炭密封体は抄紙用として
優れ、開封後抄紙工程に供することによつて優れ
た分散性、他繊維との混合性が得られ、又このた
め繊維の損傷がなく、高強度且つ均一性の高い繊
維状活性炭混抄紙を得ることができる。ここで言
う繊維状活性炭は既知の方法で得られる比表面積
500〜1500m2／ｇのものであり、繊維強度20Kg／
mm2、伸度１％以上のものが特に好ましい。
本発明の繊維状活性炭としては、ポリアクリロ
ニトリル系繊維、セルロース系繊維、フエノール
樹脂系繊維、ピツチ系繊維を原料として作られる
ものは全て用いることができるが、強度、弾性率
とも高いものが得られるポリアクリロニトリル系
繊維を原料とするものが特に望ましい。繊維状活
性炭の繊維長はその分散性に影響し、２〜15mm、
好ましくは３〜10mmの範囲であることが必要であ
る。２mm未満の繊維長では抄紙時、他繊維との絡
みが不足して脱落し易い。一方、15mmを越えると
水に対する分散性が悪く、パルプその他の繊維と
の均一な混合が難しくなり好ましくない。
本発明の繊維状活性炭は更に一方向性繊維束で
なければならない。
ここで言う一方向性繊維束とは約500〜1000本
以上のフイラメントが実質的に一方向に引き揃え
られた短繊維の集合体を意味する。
切断繊維が一方向性繊維束とならず方向性の乱
れた開繊状態になると水に対する分散性が著しく
低下しパルプその他の繊維成分との混合時、繊維
が折れ、粉末化し易く、混抄紙中での含有率が低
下するとともに品質斑の多いものとなる。更に、
上記の如く特性を有する本発明の繊維状活性炭は
水分率が飽和水分率（25℃、RH80％）の1.5〜７
倍に保持されていることが必要である。ここで、
飽和水分率とは、絶乾した繊維状活性炭を25℃で
RH80％に保つたデシケーター中に放置して経時
的に繊維の増量を秤量し、増量が飽和に達した時
点での繊維に対する吸着水分量を言い、水分率と
は絶乾の繊維状活性炭あたりの水分量を言う。
水分率が飽和水分率の1.5倍未満では短繊維が
バラバラにほぐれて一方向性繊維束が得られず、
又水に対する分散が悪く、更に混合時繊維の損傷
が著しく好ましくない。一方７倍量を越えると繊
維状活性炭の水に対する分散性が逆に低下し、パ
ルプその他の繊維成分との均一な混合が難しくな
る。
繊維状活性炭の一方向性繊維束は、上記水分率
にて密閉保持されていることが必要で、一旦水分
率の低下した後再調湿したのでは抄紙時の分散
性、他繊維との混合性は改良されない。
本発明の繊維状活性炭密封体は次のようにして
得られる。
一方向性繊維束を得るためには、少なくとも
1000フイラメント以上の単繊維からなる繊維状活
性炭の束に予め水あるいは水性の媒体を付与して
一方向に引き揃えたのち、あるいは一方向に引き
揃えた後水性媒体を付与してカツターで所定の繊
維長に切断する。
乾燥した繊維状活性炭の束を切断すると切断繊
維は開繊し易く、繊維同志が絡み合つて一方向性
繊維束は得られ難い。
繊維束を所定長に切断後、乾燥あるいは加湿す
ることなくポリエチレン等の気密性フイルム製袋
又は気密性容器（缶、箱等）に入れて乾燥しない
ようなるべく空間のない状態で密閉する。繊維の
開繊を防止するために少量のバインダーを付与し
てもよい。
上記の如き、本発明の繊維状活性炭密封体を用
いる抄紙は通常の方法に従つて行なわれる。
すなわち、繊維状活性炭および他の繊維材料例
えば、木材パルプ、再生パルプ、羊毛、木綿等の
天然繊維、レーヨン、ビニロン、ポリエステル、
アクリル等の化学繊維、ポリエチレン、ポリプロ
ピレン等の合成パルプ等とビーター、パルパー、
リフアイナー等の叩解機又は離解機を用いて叩解
や離解を行ない、繊維状活性炭、他の繊維材料お
よび水性媒体からなる混合物とし、その濾水度を
調節後、更に水性媒体を加え、繊維状活性炭およ
び他の繊維材料の濃度が0.05〜1.5重量％となる
ように調節して、通常用いられる抄紙機により抄
紙する。
本発明の繊維状活性炭によれば、高度の吸着性
と強度とを有し、且つ均一性の高い混抄紙を得る
ことができる。
更に、本発明の繊維状活性炭を用いることによ
り、従来難しいとされていた坪量20ｇ／m2以下の
薄手の混抄紙や繊維状活性炭が10％以下の低混抄
率の紙を均一に製造することができる。以下本発
明を実施例によつて説明する。
実施例 １
アクリロニトリル系繊維を原料として製造され
た比表面積750m2／ｇ、飽和水分率28％の繊維状
活性炭を水に浸漬してローラーで絞り水分率を約
150％に調節後、切断機で５mmの長さに切断した。
切断後の繊維状活性炭は一方向性繊維束で、その
水分率は飽和水分率の５倍の140％であつた。こ
の繊維を直ちにポリエチレンの袋に密閉し、室内
に７日間放置した。その後、密閉を解いて水分率
を測定したところ、140％であつた。この繊維状
活性炭を水に投入し、分散させたスラリーとし
た。その結果極めて良好な分散性を示した。一
方、予めパルパーによつて叩解された針葉樹晒パ
ルプのスラリーに上記繊維状活性炭分散液を繊維
状活性炭の混抄率が10重量％および55重量％にな
るようにリフアイナーを用いて混合し、更に水を
加えて繊維状活性炭とパルプの混合物の濃度が１
重量％になるよう調整後、長網式抄紙機で抄紙し
た。
比較のため、上記の繊維状活性炭の水分率が飽
和水分率の1.0倍（比較例(a)）および8.5倍（比較
例(b)）に調整したものについて同様に抄紙した。
更に、水分率140％の上記繊維状活性炭を水分
率28％まで静置乾燥したものを140％の水分率に
なるように再調湿して同様に抄紙した（比較例
(c)）。
この場合、繊維を切断後乾燥し、再び調湿した
ため、繊維状活性炭が一方向性繊維束でなくなつ
た。以上の結果を示すと第１表の通りである。こ
れによれば、本発明の繊維状活性炭を用いた混抄
紙は高度の吸着性および強度等の特性を有してお
り、品質斑も少ないことがわかる。
The present invention relates to fibrous activated carbon for paper making. Specifically, the present invention provides a fibrous activated carbon for paper making that has excellent dispersibility in water during paper making and does not damage fibers during beating or disintegration. Paper making in which fibrous activated carbon is mixed with pulp and other fibrous materials has been proposed, but conventional fibrous activated carbon has poor dispersibility in water and fibers aggregate in unopened clumps in water. It is difficult to mix uniformly with the fibrous materials, resulting in uneven adsorption, uneven basis weight, insufficient paper strength, etc., which poses problems in terms of practicality. In order to mix both of them uniformly, a beater,
It is necessary to thoroughly beat or disintegrate using a refiner, etc., but since fibrous activated carbon is fragile,
The fibers are easily damaged and powdered during beating or disintegration, and easily fall off during paper making. For this reason, there is a problem that the fibrous activated carbon content in the mixed paper decreases and the mixed paper ratio tends to fluctuate. In order to solve the above-mentioned problems, the present inventors have conducted various studies on the characteristics of fibrous activated carbon that is most suitable for use in paper making, and have arrived at the present invention. That is, the present invention is a unidirectional fiber bundle with a fiber length of 2 to 15 mm, and a moisture content of saturated moisture content (25°C,
This is a fibrous activated carbon sealed body for paper making that maintains a RH of 1.5 to 7 times (80%). Such fibrous activated carbon sealed bodies are excellent for paper making, and when used in the paper making process after opening, excellent dispersibility and mixability with other fibers can be obtained, and there is no damage to the fibers, resulting in high strength. In addition, a fibrous activated carbon mixed paper with high uniformity can be obtained. The fibrous activated carbon mentioned here has a specific surface area obtained by a known method.
500-1500m 2 /g, fiber strength 20Kg /
mm 2 and elongation of 1% or more are particularly preferred. As the fibrous activated carbon of the present invention, any carbon made from polyacrylonitrile fibers, cellulose fibers, phenol resin fibers, and pitz fibers can be used, but it is possible to obtain a carbon with high strength and elastic modulus. Particularly desirable are those made from polyacrylonitrile fibers. The fiber length of fibrous activated carbon affects its dispersibility, ranging from 2 to 15 mm,
It is preferably in the range of 3 to 10 mm. When the fiber length is less than 2 mm, the fibers tend to fall off due to insufficient entanglement with other fibers during paper making. On the other hand, if it exceeds 15 mm, the dispersibility in water will be poor, making it difficult to mix uniformly with pulp and other fibers, which is not preferable. The fibrous activated carbon of the present invention must also be a unidirectional fiber bundle. The unidirectional fiber bundle as used herein means an aggregate of short fibers in which approximately 500 to 1000 or more filaments are aligned substantially in one direction. If the cut fibers do not become unidirectional fiber bundles but become spread fibers with disordered directionality, the dispersibility in water will be significantly reduced, and when mixed with pulp and other fiber components, the fibers will easily break and become powder, and during mixed paper making. As the content rate decreases, the quality becomes more uneven. Furthermore,
The fibrous activated carbon of the present invention having the above characteristics has a moisture content of 1.5 to 7 of the saturated moisture content (25°C, RH80%).
It is necessary to hold twice as much. here,
Saturated moisture content refers to the temperature of bone-dried fibrous activated carbon at 25°C.
The weight gain of the fibers is measured over time by leaving them in a desiccator maintained at 80% RH, and the amount of moisture absorbed by the fibers is defined as the amount of moisture absorbed by the fibers when the weight gain reaches saturation. Say the amount of water. If the moisture content is less than 1.5 times the saturated moisture content, the short fibers will come apart and a unidirectional fiber bundle will not be obtained.
In addition, the dispersion in water is poor, and the fibers are significantly damaged during mixing, which is undesirable. On the other hand, if the amount exceeds 7 times, the dispersibility of the fibrous activated carbon in water will decrease, making it difficult to mix uniformly with pulp and other fiber components. The unidirectional fiber bundle of fibrous activated carbon needs to be kept hermetically sealed at the above moisture content, and if it is re-humidified once the moisture content has decreased, it may be difficult to disperse the fibers during paper making or mix with other fibers. gender is not improved. The fibrous activated carbon sealed body of the present invention can be obtained as follows. To obtain unidirectional fiber bundles, at least
A bundle of fibrous activated carbon consisting of single fibers of 1,000 or more filaments is coated with water or an aqueous medium in advance and drawn in one direction, or after being drawn in one direction, an aqueous medium is applied and cut into a predetermined shape with a cutter. Cut into fiber lengths. When a bundle of dried fibrous activated carbon is cut, the cut fibers tend to open, and the fibers become entangled with each other, making it difficult to obtain a unidirectional fiber bundle. After cutting the fiber bundle to a predetermined length, the fiber bundle is placed in an airtight film bag made of polyethylene or the like or an airtight container (can, box, etc.) without drying or humidifying, and sealed with as little space as possible to prevent drying. A small amount of binder may be added to prevent the fibers from opening. Paper making using the fibrous activated carbon sealed body of the present invention as described above is carried out according to a conventional method. That is, fibrous activated carbon and other fibrous materials such as wood pulp, recycled pulp, wool, natural fibers such as cotton, rayon, vinylon, polyester,
Chemical fibers such as acrylic, synthetic pulps such as polyethylene and polypropylene, beaters, pulpers, etc.
Define and disintegrate using a refining machine such as a refiner or disintegrator to obtain a mixture consisting of fibrous activated carbon, other fibrous materials, and an aqueous medium. After adjusting the freeness of the mixture, an aqueous medium is further added to form the fibrous activated carbon. The concentration of other fiber materials is adjusted to 0.05 to 1.5% by weight, and paper is made using a commonly used paper machine. According to the fibrous activated carbon of the present invention, it is possible to obtain a mixed paper that has a high degree of adsorption and strength and is highly uniform. Furthermore, by using the fibrous activated carbon of the present invention, it is possible to uniformly produce thin mixed paper with a basis weight of 20 g/m 2 or less and paper with a low blend ratio of 10% or less of fibrous activated carbon, which was previously considered difficult. be able to. The present invention will be explained below with reference to Examples. Example 1 Fibrous activated carbon with a specific surface area of 750 m 2 /g and a saturated moisture content of 28%, manufactured using acrylonitrile fiber as a raw material, was immersed in water and squeezed with a roller to reduce the moisture content to approx.
After adjusting to 150%, it was cut into a length of 5 mm using a cutting machine.
The fibrous activated carbon after cutting was a unidirectional fiber bundle, and its moisture content was 140%, which was five times the saturated moisture content. The fibers were immediately sealed in a polyethylene bag and left indoors for 7 days. Afterwards, when the seal was broken and the moisture content was measured, it was 140%. This fibrous activated carbon was added to water to form a dispersed slurry. The results showed extremely good dispersibility. On the other hand, the above-mentioned fibrous activated carbon dispersion was mixed with a slurry of softwood bleached pulp that had been beaten by a pulper in advance using a refiner so that the mixing ratio of fibrous activated carbon was 10% by weight and 55% by weight, and further water was added. is added until the concentration of the mixture of fibrous activated carbon and pulp is 1.
After adjusting the weight percentage, paper was made using a fourdrinier paper machine. For comparison, paper was made in the same manner using the above fibrous activated carbon whose moisture content was adjusted to 1.0 times (Comparative Example (a)) and 8.5 times (Comparative Example (b)) the saturated moisture content. Furthermore, the above fibrous activated carbon with a moisture content of 140% was left to dry until the moisture content was 28%, and the humidity was reconditioned to a moisture content of 140%, and paper was made in the same manner (Comparative Example
(c)). In this case, the fibers were dried after being cut and the humidity was adjusted again, so that the fibrous activated carbon was no longer a unidirectional fiber bundle. The above results are shown in Table 1. According to this, it can be seen that the mixed paper using the fibrous activated carbon of the present invention has properties such as high adsorption and strength, and has few quality irregularities.
【表】
実施例 ２
実施例１の繊維状活性炭（繊維長６mm、水分
率／飽和水分率＝5.0）を同様な方法にて抄紙し
て薄手で且つ繊維状活性炭が低含有率の混抄紙を
得た。
比較のため、上記の繊維状活性炭の水分率が飽
和水分率の1.3倍で繊維長が１mm（比較例(d)）お
よび18mm（比較例(e)）のものについて同様に抄紙
した。
その結果を第２表に示す。[Table] Example 2 The fibrous activated carbon (fiber length 6 mm, moisture content/saturated moisture content = 5.0) of Example 1 was made into paper in the same manner as in Example 1 to produce a thin mixed paper with a low content of fibrous activated carbon. Obtained. For comparison, paper was made in the same manner using the above-mentioned fibrous activated carbon whose moisture content was 1.3 times the saturated moisture content and whose fiber length was 1 mm (Comparative Example (d)) and 18 mm (Comparative Example (e)). The results are shown in Table 2.
【表】【table】
【表】
本発明の繊維状活性炭によれば、品質の均一な
薄手で低含有率の混抄紙を得ることができる。[Table] According to the fibrous activated carbon of the present invention, it is possible to obtain thin mixed paper of uniform quality and low content.
【図面の簡単な説明】[Brief explanation of drawings]
本発明密封体を示すと第１図の通りである。第
１図は本発明密封体の一部切欠側面図である。
１：密封材、２：一方向性繊維束。
The sealed body of the present invention is shown in FIG. 1. FIG. 1 is a partially cutaway side view of the sealing body of the present invention. 1: Sealing material, 2: Unidirectional fiber bundle.