JP3716984B2

JP3716984B2 - Method for producing hygroscopic fiber

Info

Publication number: JP3716984B2
Application number: JP2002258051A
Authority: JP
Inventors: 正雄家野
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2002-09-03
Filing date: 2002-09-03
Publication date: 2005-11-16
Anticipated expiration: 2019-04-27
Also published as: JP2003129377A

Description

【０００１】
【発明の属する技術分野】
本発明は吸放湿性繊維に関する。さらに詳しくは、調湿材として実用性能上要求されるＲＨ５０％〜９５％の湿度範囲で水蒸気吸着等温線が急峻に立ち上がっていることにより、その湿度範囲において優れた調湿機能を有し、かつ抗菌性を有するともに、加工性も優れた吸放湿性繊維及びその製造方法に関する。
【０００２】
【従来の技術】
シリカゲル，ゼオライト，硫酸ナトリウム，活性アルミナ，活性炭等の吸湿剤は、吸湿量が少なく吸湿速度が遅く再生に高温を要するという欠点があり、いずれも種々の用途に実用化するには問題があった。またＢ型シリカゲルは高い吸湿率差を有するが、ヒステリシス現象があることや球状形態のために該吸湿剤が脱落し易いために不織布等に加工するには繁雑な工程を要する等の問題がある。
【０００３】
この問題点を解決する方法として、潮解性塩類を高吸水性繊維に含浸させた特許第２６２３７７１号公報の手段を提案したが、この手段により得られた繊維は、編物・織物・不織布等への加工が容易で吸放湿速度が速く、さらに吸湿剤の脱落もない実用性能を備えたものではあるが、繊維表面がヒドロゲルであるため、吸湿すると粘着性を帯び、特に壁紙やふとん綿への適用が困難であること、及び最近社会的ニーズとして高まりつつある抗菌性を満たすものではなかった。
【０００４】
東洋紡績（株）製の高吸湿性繊維（Ｎ−３８）は特開平９ー１５８０４０号公報の手段で提案され、吸湿性と放湿性を有し繰り返し使用に耐え、かつ抗菌性も兼ね備え、加工性が良好な高吸放湿性繊維である。しかしながらこの繊維は、調湿材の分野で実用性能上の要求はＲＨ５０％〜９５％の湿度範囲での吸湿率差が大きいことと言うのに対し、わずか吸湿率差が３５％しかないという問題点があった。
【０００５】
鐘紡（株）製のベルオアシスは高い吸湿率差を有するが、調湿材の一用途である畳表中敷き等では水をこぼすと繊維が膨潤して畳表が盛り上がる、また一度膨潤すると乾燥しない等の問題があり、かつ繊維物性が低く不織布等に加工するには繁雑な工程を要する等の問題がある。
【０００６】
【発明が解決しようとする課題】
本発明はこのような従来の調湿材が抱える課題を解消したものであり、低湿度と高湿度の環境間で従来品よりも非常に高い吸湿率差を示し、吸放湿速度が速く、しかも取扱が容易で、吸湿後の形態保持性に優れ、容易に再生し得る、さらに抗菌性も兼ね備えた改善された調湿材に適する吸放湿性繊維及びその製造方法を提供することである。
【０００７】
【課題を解決するための手段】
本発明者は高い繊維物性を有し、調湿材で実用性能上要求される吸湿率差の大きい吸放湿性繊維について鋭意研究を続けてきた。即ち本発明は、膨潤度が３．０ｇ／ｇ以下、減菌率が９０％以上で、且つ２０℃×５０％ＲＨ条件と２０℃×９５％ＲＨ条件との吸湿率差が５０重量％以上の架橋アクリル系繊維であることを特徴とする吸放湿性繊維である。
【０００８】
かかる吸放湿性繊維は、アクリロニトリル含有率が８５〜９５重量％であるアクリル系繊維にヒドラジン系化合物による架橋処理を行い、この架橋結合の導入による窒素含有量の増加が、１．０〜５．０重量％の範囲内となるように調整し、引き続き酸処理、次いでアルカリによる加水分解を行うことによって、残存しているニトリル基の一部を３．０〜６．０ｍｅｑ／ｇのアルカリ金属塩型カルボキシル基に変換すること、により製造することができる。
【０００９】
【発明の実施の形態】
以下、本発明を詳述する。本発明は架橋アクリル系繊維であるが、その出発アクリル系繊維としてはアクリロニトリル（以下、ＡＮという）を８５〜９５重量％含有するＡＮ系重合体により形成された繊維であり、短繊維、トウ、糸、編織物、不織布等いずれの形態のものでも良く、また、製造工程中途品、廃繊維などでも構わない。ＡＮ系重合体は、ＡＮ単独重合体、ＡＮと他の単量体との共重合体のいずれでも良く、他の単量体としては、ハロゲン化ビニル及びハロゲン化ビニリデン；（メタ）アクリル酸エステル；メタリルスルホン酸、ｐースチレンスルホン酸等のスルホン酸含有単量体及びその塩；（メタ）アクリル酸、イタコン酸等のカルボン酸含有単量体及びその塩；アクリルアミド、スチレン、酢酸ビニル等の単量体が挙げられるが、ＡＮと共重合可能な単量体であれば特に限定されない。
【００１０】
該アクリル系繊維に、ヒドラジン系化合物による架橋を導入する方法としては、窒素含有量の増加が１．０〜５．０重量％の範囲内に調整し得る手段である限り採用できるが、ヒドラジン系化合物の濃度５〜６０％，温度５０〜１２０℃で５時間以内で処理する手段が工業的に好ましい。ここで、窒素含有量の増加とは原料アクリル系繊維の窒素含有量とヒドラジン系化合物による架橋が導入されたアクリル系繊維の窒素含有量との差をいう。
【００１１】
なお、窒素含有量の増加が上記下限に満たない場合には、最終的に実用上満足し得る物性の繊維が得られず、上限を越えると繊維の膨潤率が低くなり、吸湿率差の大きい吸放湿性繊維が得られない。ここに使用するヒドラジン系化合物としては、水加ヒドラジン、硫酸ヒドラジン、塩酸ヒドラジン、臭素酸ヒドラジン、ヒドラジンカーボネート等、この他エチレンジアミン、硫酸グアニジン、塩酸グアニジン、リン酸グアニジン、メラミン等のアミノ基を複数含有する化合物が例示される。
【００１２】
本発明者は、ヒドラジン系化合物による架橋処理後の残存ニトリル基の一部を３．０〜６．０ｍｅｑ／ｇのアルカリ金属塩型カルボキシル基に変換する方法として、ヒドラジン系化合物処理による架橋結合導入の後、引き続き酸処理Ａ、次いでアルカリ化合物による加水分解を行うことによって上述の課題を達成するに到った。この方法によれば、架橋結合の導入後の酸処理Ａの酸濃度、次工程のアルカリ化合物濃度のいずれもを一段階でアルカリ加水分解するという従来の方法よりも低くすることができ、容易に多量のアルカリ金属塩型カルボキシル基に変換でき、加工に耐えうる強度を維持した吸放湿性繊維が与えられる。
【００１３】
ここに使用する酸としては、硝酸、硫酸、塩酸等の鉱酸の水溶液、有機酸等が挙げられるが特に限定されない。この処理の前に架橋処理で残留したヒドラジン系化合物は、十分に除去しておく。また、加水分解を行うのに使用するアルカリとしては、アルカリ金属水酸化物、アルカリ土類金属水酸化物、アンモニア等の塩基性水溶液等が挙げられるが、加水分解可能なアルカリであれば特に限定されない。使用する酸、アルカリの濃度についても特に限定されないが、ともに１〜１０重量％、温度５０〜１２０℃で２時間以内で処理する手段が工業的、繊維物性的にも好ましい。
【００１４】
加水分解によって生成するカルボキシル基をアルカリ金属塩型に変換する方法としては、大別して２つある。その１つは、アルカリ金属水酸化物による加水分解であり、直接アルカリ金属塩型カルボキシル基を生成させるものである。第２はアルカリ土類金属水酸化物やアンモニア等により加水分解して一旦目的とは異なる型のカルボキシル基を生成させ、次いで該基を目的のアルカリ金属塩型に置換するという方法である。
【００１５】
第２の方法におけるカルボキシル基の塩型の置換には、アルカリ金属の水酸化物や該金属の塩化合物により直ちにアルカリ金属塩型にする手段や、一旦酸処理（前述の酸処理Ａと区別して酸処理Ｂ）してカルボキシル基をＨ（酸）型にした後上記のアルカリ金属化合物によりアルカリ金属塩型にする手段がある。尚本願発明が必要とするアルカリ金属塩型カルボキシル基の量は３．０〜６．０ｍｅｑ／ｇであるので、この量が確保されれば、残余のカルボキシル基の「型」は問わない。
【００１６】
アルカリ金属塩型としては文字通りＬｉ，Ｎａ，Ｋであり、かかる塩型カルボキシル基が上述の量形成されていると、繊維は１．０〜３．０ｇ／ｇの膨潤度を有するものとなる。尚カルボキシル基の塩の種類はＬｉ，Ｎａ，Ｋであるが、この中のいずれか１種類に限定される訳ではなく、同一の製品繊維にこれらの２種以上が混在していても構わない。又、膨潤度の評価手段は後述する。かかるアルカリ金属塩型への変換処理の後は、被処理繊維は水洗，乾燥や必要に応じ油剤処理等を施す。
【００１７】
なお、アルカリ金属塩型カルボキシル基が３．０ｍｅｑ／ｇに満たない場合には吸放湿性が得られず、また６．０ｍｅｑ／ｇを越えると、実用上満足し得る繊維物性が得られない。架橋の導入が適正に行われ、ニトリル基の一部がアルカリ金属塩型カルボキシル基３．０〜６．０ｍｅｑ／ｇに変換された結果、発明の繊維の膨潤度は１．０〜３．０ｇ／ｇを示し、引張強度も０．７ｄＮ／ｔｅｘ以上，減菌率も９０％以上を有するものとなる。かかる繊維は従来技術である特開平９−１５８０４０号公報が開示する発明では得られなかった、２０℃×５０％ＲＨ条件と２０℃×９５％ＲＨ条件との吸湿率差が５０重量％以上１５０重量％以下という吸湿率差の大きい繊維であり、従来の繊維あるいは方法よりも実用性能上有効な吸湿率差が大幅に改善される。
【００１８】
本発明の繊維は製造工程中のアルカリ金属塩型カルボキシル基形成されたところで膨潤しているので、乾燥工程での負荷を軽減するためや、最終製品に向けての加工例えば不織布にするための加工性を向上する目的で油剤付着をするが、油剤としてアルキルアミド第４級カチオン油剤を１．０〜２．５％ｏｍｆの範囲で繊維に付着すると、前記した異なる条件間での吸湿率差は変わらないで繊維の膨潤度が１ｇ／ｇ低下することを見出した。
【００１９】
本知見は本発明繊維の工業的有利な製造方法を与える。油剤付着量が１．０％ｏｍｆ未満では膨潤度は低下しない。また油剤付着量が２．５％ｏｍｆ以上ではかえって不織布等への加工性が悪くなる等の問題点が発生する。かかるアルキルアミド第４級カチオン油剤として好ましい例はアルキルアミドプロピルジメチルβ−ヒドロキシエチルアンモニウム硝酸塩Ｒ＝（Ｃ１６〜Ｃ１８），ステアリルアミドエチルジメチルヒドロキシエチルアンモニウムクロライド，セチルアミドエチルジエチルメチルアンモニウムメチルサルフェート等が挙げられる。本発明により、引張強度が０．７ｄＮ／ｔｅｘ以上で、吸放湿速度が速く、吸湿率差が大きくて抗菌性を兼備する繊維を提供することが出来る。
【００２０】
本発明の出発繊維は前述の通り、アクリル系繊維製造工程途中のものであっても、繊維に紡績加工等を施した後のものでも良い。出発アクリル系繊維として、延伸後熱処理前の繊維（ＡＮ系重合体の紡糸原液を常法に従って紡糸し、延伸配向され、乾燥緻密化、湿熱緩和処理等の熱処理の施されていない繊維、中でも湿式又は乾／湿式紡糸、延伸後の水膨潤ゲル状繊維：水膨潤度３０〜１５０％）を使用することにより、反応液中への繊維の分散性、繊維中への反応液の浸透性などが改善され、以て架橋結合の導入や加水分解反応が均一かつ速やかに行われるので望ましい。
【００２１】
なお、これらの出発アクリル系繊維を、ポンプ循環系を備えた容器内に充填し、上記架橋結合の導入、酸処理Ａ、アルカリ処理、及びアルカリ金属塩型カルボキシル基の形成、水洗、油剤処理等の手段をとることが、装置上、安全性、均一反応性等の諸点から望ましい。かかる装置（ポンプ循環系を備えた容器）としては染色機が例示される。
【００２２】
このように大きな吸湿率差があることにより、本発明の繊維は、従来なかった用途、或いは、従来繊維では要求に応えられなかった用途に適用できる。例えば、結露する前の水蒸気を吸湿し、また吸水する作用による結露防止素材、水蒸気を吸収する事を利用した吸放湿素材（衣服、建材、壁紙、中綿等）、環境の調湿，調温素材等が挙げられる。また、高い吸湿率差性能を利用した、押入れ，地下室，床下，浴室等の乾燥，除湿素材や、水分を非常に嫌う電子材料等の被覆素材の一部として使う等の使用方法も例示できる。また、この繊維は親水性が高いので、水分を吸収，水蒸気を放出する様な用途にも適用できる。このような効果は、出発繊維を細デニール糸にする、中空糸にする、多孔繊維とする等で更に高めることができる。また、フィブリル化繊維形態、起毛或いは植毛した布や紙等にすることも有効である。
【００２３】
また、本発明の繊維は吸放湿性繊維であるが、吸湿したときの繊維の状態がべとつかずに、適度に湿り気があり、かつ適度な伸度も有している。このため、しっとりとしていてしなやかな繊維である。この性質を利用して、保湿素材、美容素材、高風合い素材等への適用もできる。また、親水性の薬品等をしみ込ませた布、紙等へ適用した場合にも、保湿性が高いため含浸量が高く、乾きにくい素材にできるといった効果がある。このような例としては、消毒液、化粧水、芳香剤、消臭剤、殺菌剤、防虫剤等を含浸させたものが例示できる。
【００２４】
本発明の繊維の吸放湿性は、主にアルカリ金属塩型カルボキシル基によって発現する。この量を制御する事によって吸放湿性を制御できる。例えば、加水分解により多量のカルボキシル基を導入し、アルカリ金属塩型カルボキシル基への変換量を制御して吸放湿性を制御する等の方法も行い得る。このような方法を採用する場合には、アルカリによる加水分解に次いで酸処理を行う等種々の方法があるが、アルカリ金属塩型カルボキシル基を３．０〜６．０ｍｅｑ／ｇ存在せしめられる方法であれば特に限定されない。しかし、工業的には前述の第２の方法である、アルカリによる加水分解に次いで、酸処理Ｂを行ってからアルカリ金属塩処理を行ってアルカリ金属塩型カルボキシル基の量を制御するという方法が好ましい。
【００２５】
本発明の繊維は吸放湿速度が速いが、この速度も繊維自体や繊維でなる成形体の密度などによって制御することができる。非常に速い吸放湿速度が要求される場合には、細い吸放湿性繊維を用いたり、フィブリル化した吸放湿性繊維を用いたり、繊維密度を低くしたり、起毛，植毛等を行い、吸放湿性繊維と湿分含有気体と接触する面積を大きくする等の方法を採用する事ができる。また、緩慢な吸放湿速度が要求される場合には、不織布、紙への加工の密度を高める或いは紡績時に高い撚り数にする等により繊維密度を高くしたり、太い吸放湿性繊維を用いたり、本発明の繊維を水蒸気を透過する事のできる他の物質で覆う等の方法が採用できる。
【００２６】
本発明の繊維は先に述べたように高い吸湿率差及び吸放湿性、抗菌性も有する。抗菌性とは、実施例に示すようなシェークフラスコ法で測定した時の減菌率で示すが、本発明繊維は９０％以上の減菌率を示す。
【００２７】
本発明の繊維は、これらの特性を有する為、非常に安全に取り扱うことができる。通常の繊維は水分を吸収すると菌の発生し易い環境になるため、衛生上、抗菌性を付与した繊維等の併用が必要になる事が多いが、特にこれを行う必要がないという優れた性能を持ち合わせているのである。また難燃性を有する為、再生等で高温を適用するような事を行っても、出火の心配は殆ど無く家庭で使用しても非常に安全な素材である。
【００２８】
本発明の素材は、耐薬品性に優れた架橋構造を有しているため、種々の薬品による処理を行っても繊維形態を保持することができる。よって、酸やアルカリ等を含む構造材料の構造保持材等としても適用できる。
【００２９】
【作用】
本発明に係る吸放湿性繊維並びに該製造方法が、抗菌性を有しつつ高い吸湿率差及び吸放湿性を兼ね備える理由は、十分に解明するに至っていないが、概ね次のように考えられる。
【００３０】
即ち、本発明に係る繊維は、ＡＮ系重合体から出発していながら、実質的にニトリル基が減少している所から、ポリマー鎖に結合している側鎖は、ヒドラジン系化合物との反応により生成した窒素を含有する架橋構造と、ニトリル基の加水分解反応により生成したアルカリ金属塩型カルボキシル基が大部分を占めていると考えられる。
【００３１】
一般にアルカリ金属塩型カルボキシル基は吸湿性を有するが、本発明はこの量が非常に多いことに加え、窒素の多い架橋構造を有するため吸湿性を更に高めていると考えている。また、カルボキシル基がアルカリ金属塩型であることと、適度な架橋構造があることにより、吸湿性に関与するはずの官能基同士が水素結合してしまい吸湿性に寄与しないといった機構が抑制され、非常に高い吸湿率差及び吸放湿性を持つと推定している。
【００３２】
本発明の繊維はアルカリ金属塩型カルボキシル基を多量に含んでいても、種々の加工に耐えうる繊維強度を持つ。このことについては次のように推定している。即ち、酸処理Ａ、アルカリ処理と二段階の加水分解を行うので、反応試薬の濃度が非常に低く且つ処理時間が短縮できる。このため苛酷な処理をうけず、アルカリ金属塩型カルボキシル基の量が多くても高い繊維強度を有すると推定している。当然、架橋構造を有していることにも起因していよう。
【００３３】
抗菌性は窒素を含有する架橋構造によりもたらされていると推定される。さらに、吸湿時でもべとつき感がないのは高度に架橋されていること並びに油剤の効果のためであろう。
【００３４】
【実施例】
以下実施例により本発明を具体的に説明する。実施例中の部及び百分率は、断りのない限り重量基準で示す。なお、繊維中のアルカリ金属塩型カルボキシル基量、吸湿率、膨潤度、油剤付着率及び抗菌性は以下の方法により求めた。
【００３５】
（１）アルカリ金属塩型カルボキシル基量（ｍｅｑ／ｇ）
十分乾燥した供試繊維約１ｇを精秤し（Ｘg ）、これに２００ｍｌの水を加えた後、５０℃に加温しながら１Ｎ塩酸水溶液を添加してｐＨ２にし、次いで０．１Ｎ苛性ソーダ水溶液で常法に従って滴定曲線を求めた。該滴定曲線から全カルボキシル基に消費された苛性ソーダ水溶液消費量（Ｙｃｃ）を求め、次式によって全カルボキシル基量（ｍｅｑ／ｇ）を算出した。
（全カルボキシル基量）＝０．１Ｙ／Ｘ
【００３６】
別途、上述の全カルボキシル基量測定操作中の１Ｎ塩酸水溶液の添加によるｐＨ２への調整をすることなく同様に滴定曲線を求め酸型カルボキシル基量（ｍｅｑ／ｇ）を求めた。これらの結果から次式によりアルカリ金属塩型カルボキシル基量を算出した。
（アルカリ金属塩型カルボキシル基量）＝（全カルボキシル基量）−（酸型カルボキシル基量）
【００３７】
（２）吸湿率（％）
試料繊維約５．０ｇを熱風乾燥機で１２０℃、５時間乾燥して重量を測定する（Ｗ１ｇ）。次に試料を温度２０℃で所定の恒湿槽（５０％ＲＨ及び９５％ＲＨ）に24時間入れておく。このようにして吸湿した試料の重量を測定する（Ｗ２ｇ）。以上の測定結果から、次式によって算出した。
（吸湿率）＝（Ｗ２−Ｗ１）／Ｗ１×１００吸湿率差とは、かくして得た２０℃における５０％ＲＨと９５％ＲＨの吸湿率の差を言う。
【００３８】
（３）膨潤度（ｇ／ｇ）
試料繊維約３ｇを熱風乾燥機で７０℃、３時間乾燥して重量を測定する（Ｗ１ｇ）。次に試料を水が３００ｍｌ入ったビーカーに３０分間浸漬した後、膨潤した試料を卓上遠心脱水機（１６０Ｇ×５分）で脱水した後の試料の重量を測定する（Ｗ２ｇ）。
（膨潤度）＝（Ｗ２−Ｗ１）／Ｗ１
【００３９】
（４）油剤付着率（％ｏｍｆ）
試料繊維約３ｇを精秤（Ｗ１）してガラス円筒濾紙に入れ、これを抽出円筒に入れ予め溶剤（１級エチルアルコール）１００〜１２０ｍｌが入ったコルベンを接合する。更に、冷却菅を接合し、ウォーターバス上で９７℃以上で２時間抽出する。コルベンの中の溶剤を抽出円筒に充分上げた時点でコルベンを外し、溶剤をシャーレに入れ、これをウォーターバスで蒸発乾固する。シャーレに残留した油剤の重量（Ｗ２）を求め次式により算出する。
（油剤付着率）＝Ｗ２／（Ｗ１−Ｗ２）×１００
【００４０】
（５）抗菌性試験菌を肺炎桿菌とし、抗菌防臭加工製品の加工効果評価試験マニュアル・シェークフラスコ法（繊維製品衛生加工協議会，昭和６３年）により試験し、減菌率％で示した。
【００４１】
実施例１
ＡＮ９０％及びアクリル酸メチル（以下、ＭＡという）１０％からなるＡＮ系重合体（３０℃ジメチルホルムアミド中での極限粘度〔η〕：１．２）１０部を４８％のロダンソーダ水溶液９０部に溶解した紡糸原液を、常法に従って紡糸、延伸（全延伸倍率；１０倍）した後、乾球／湿球＝１２０℃／６０℃の雰囲気下で乾燥（工程収縮率１４％）して単繊維繊度１．５ｄの原料繊維Ｉを得た。
【００４２】
原料繊維Ｉを、表１に示した条件で架橋処理及びニトリル基のアルカリ金属塩型カルボキシル基への変換を行った後、脱水、水洗、乾燥を行い繊維Ｎｏ．１〜８を得た。得られた繊維の特性を調べ、その結果を表１に併記した。
【００４３】
【表１】

【００４４】
窒素増加量が１．０〜５．０重量％の範囲にあってＮａ型カルボキシル基が３．０〜６．０ｍｅｑ／ｇの範囲である本発明例の繊維Ｎｏ．１〜４は、膨潤度１．０〜３．０ｇ／ｇと高い吸湿率差を示し、高い引張強度と抗菌性も兼ね備えていることが判る。
【００４５】
これらに対して、繊維Ｎｏ．５は窒素増加量が１．０重量％未満のため、Ｎａ型カルボキシル基量は本願が推奨する範囲にあり吸湿率差も大きいが、引張強度が０．２ｄＮ／ｔｅｘと低い値である。このため繊維が脆く、カード掛け等の加工に耐える物性を有するものではなかった。また、同様にＮａ型カルボキシル基量は満たすものの窒素増加量が本発明の推奨量より過大である繊維Ｎｏ．６は、十分な引張強度を有するものの繊維の膨潤度、吸湿率差共に目的が達成されない。
【００４６】
一方、窒素増加量は満たすもののＮａ型カルボキシル基への変換が本発明の推奨量より少ない繊維Ｎｏ．７は、引張強度はあるが繊維の膨潤度、吸湿率差共に目的を達するものではない。また、同様に窒素増加量は適当であるもののＮａ型カルボキシル基への変換が本発明の推奨量より大きい繊維Ｎｏ．８は吸湿率差は十分であるが、繊維の膨潤度が高く、引張強度が０．４ｄＮ／ｔｅｘと低い値である。このため繊維が脆く、カード掛け等の加工に耐える物性を有するものではなかった。
【００４７】
実施例２
実施例１で得られたＮｏ．１の繊維５ｇを、表２に示したアルカリ金属化合物又はアルカリ土類金属化合物の５％水溶液１Ｌに温度４０℃で５時間浸漬した後水洗、乾燥し、塩型の異なる繊維Ｎｏ．９〜１１を得た。得られた繊維の特性を調べ、その結果を表２に併記した。
【００４８】
【表２】

【００４９】
本発明例繊維Ｎｏ．１のＮａ型に変換された繊維やＬｉ型であるＮｏ．９，Ｋ型であるＮｏ．１０の繊維と比較すると、繊維Ｎｏ．１１のＣａ型カルボキシル基を有する繊維は繊維の膨潤度が低くなり、引張強度は向上するが、吸湿率差が低くて目的を達せず、カルボキシル基の塩型としてはアルカリ金属が有効であることが判る。
【００５０】
実施例３
実施例１で得られたＮｏ．１の繊維５ｇを、アルキルアミド第４級カチオン油剤であるアルキルアミドプロピルジメチルβ−ヒドロキシエチルアンモニウム硝酸塩（Ｒ＝Ｃ１６〜Ｃ１８）の０．５％水溶液と１．５％水溶液に４０℃で１時間浸漬した後脱水、乾燥し、表３に示す油剤付着量の異なる繊維Ｎｏ．１２、１３を得た。得られた繊維の特性を調べ、その結果を表３に併記した。
【００５１】
【表３】

【００５２】
アルキルアミド第４級カチオン油剤付着量１．５％の繊維Ｎｏ．１２と同油剤付着量０．５％の繊維Ｎｏ．１３とを比較すると、吸湿率差は変わらないが、Ｎｏ．１２では繊維の膨潤度が低下することにより製造工程で繊維の乾燥負担が軽減されるため、工業的有利に製造し得ることが判る。一方油剤付着量０．５％では、繊維Ｎｏ．１と較べて膨潤度に差がなく、乾燥負担軽減の目的には１．０％以上の付着が必要であることが理解される。
【００５３】
【発明の効果】
加工上問題のない繊維物性を有し、調湿材で実用性能上必要とされる吸湿率差の大きい吸放湿性繊維を、工業的に有利に製造する手段を提供し得た点が本発明の特筆すべき効果である。このようにして得られた吸放湿性繊維は、吸放湿性が向上したばかりでなく吸湿率差が大幅に改善された為、従来適用できなかった用途にも展開できる。そして、抗菌性をも兼ね備えていること、再生温度が低いこと、さらに、繊維状であるために、不織布，編物，織物などさまざまな形態に加工でき、アルカリ金属塩型カルボキシル基量、繊維の太さ、密度等の制御により吸放湿速度も制御することができるため、吸放湿性、或いは吸湿による発熱性が求められる分野に広く展開することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to hygroscopic fibers. More specifically, the water vapor adsorption isotherm rises steeply in a humidity range of RH 50% to 95% required for practical performance as a humidity control material, and has an excellent humidity control function in the humidity range, and The present invention relates to a moisture absorbing / releasing fiber having antibacterial properties and excellent processability, and a method for producing the same.
[0002]
[Prior art]
Hygroscopic agents such as silica gel, zeolite, sodium sulfate, activated alumina, activated carbon, etc. have the disadvantage of low moisture absorption and slow moisture absorption rate, requiring high temperature for regeneration, and all have problems in putting them into practical use for various applications. . In addition, B type silica gel has a high moisture absorption difference, but there are problems such as a hysteretic phenomenon, and the hygroscopic agent is easy to drop off due to the spherical form, so that a complicated process is required to process it into a nonwoven fabric. .
[0003]
As a method for solving this problem, the means of Japanese Patent No. 2623771 in which a highly water-absorbing fiber is impregnated with deliquescent salts has been proposed, but the fiber obtained by this means can be applied to knitted fabrics, woven fabrics, nonwoven fabrics, etc. Although it is easy to process, has a high moisture absorption / release rate, and has practical performance that does not cause the hygroscopic agent to fall off, the fiber surface is hydrogel, so it becomes sticky when it absorbs moisture, especially for wallpaper and futon. It was difficult to apply and did not satisfy the antibacterial property that has been increasing as a social need recently.
[0004]
A highly hygroscopic fiber (N-38) manufactured by Toyobo Co., Ltd. has been proposed by means of Japanese Patent Laid-Open No. 9-158040, has hygroscopic and moisture releasing properties, can withstand repeated use, and has antibacterial properties. It is a highly hygroscopic fiber with good properties. However, this fiber has the problem that the difference in moisture absorption is only 35%, whereas the demand for practical performance in the humidity control field is that the difference in moisture absorption is large in the humidity range of RH 50% to 95%. There was a point.
[0005]
Bel Oasis, manufactured by Kanebo Co., Ltd., has a high difference in moisture absorption. However, in tatami mat insoles, which are one application of humidity control materials, if water is spilled, the fibers will swell and the tatami mat will rise. There is a problem that the fiber properties are low and a complicated process is required to process the nonwoven fabric.
[0006]
[Problems to be solved by the invention]
The present invention has solved the problems of such a conventional humidity control material, shows a very high moisture absorption difference between the low humidity and high humidity environment than the conventional product, the moisture absorption and desorption rate is fast, Furthermore, it is an object to provide a moisture absorbing / releasing fiber suitable for an improved humidity conditioning material that is easy to handle, has excellent shape retention after moisture absorption, can be easily regenerated, and also has antibacterial properties, and a method for producing the same.
[0007]
[Means for Solving the Problems]
The present inventor has conducted intensive research on moisture-absorbing and releasing fibers having high fiber properties and having a large difference in moisture absorption, which is required for practical performance as a humidity control material. That is, in the present invention, the degree of swelling is 3.0 g / g or less, the sterilization rate is 90% or more, and the difference in moisture absorption between the 20 ° C. × 50% RH condition and the 20 ° C. × 95% RH condition is 50% by weight or more. It is a moisture absorbing / releasing fiber characterized by being a cross-linked acrylic fiber.
[0008]
In this hygroscopic fiber, an acrylic fiber having an acrylonitrile content of 85 to 95% by weight is subjected to a crosslinking treatment with a hydrazine compound, and an increase in nitrogen content due to the introduction of the crosslinking bond is 1.0 to 5. An alkali metal salt of 3.0 to 6.0 meq / g of a part of the remaining nitrile group is prepared by adjusting the amount to be within the range of 0% by weight, followed by acid treatment and then hydrolysis with alkali. It can manufacture by converting into a type | mold carboxyl group.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below. Although the present invention is a cross-linked acrylic fiber, the starting acrylic fiber is a fiber formed of an AN polymer containing 85 to 95% by weight of acrylonitrile (hereinafter referred to as AN), short fiber, tow, Any form such as yarn, knitted fabric, and non-woven fabric may be used. The AN polymer may be either an AN homopolymer or a copolymer of AN and another monomer. Examples of the other monomer include vinyl halide and vinylidene halide; (meth) acrylic acid ester. Sulfonic acid-containing monomers such as methallyl sulfonic acid and p-styrene sulfonic acid and salts thereof; carboxylic acid-containing monomers such as (meth) acrylic acid and itaconic acid and salts thereof; acrylamide, styrene, vinyl acetate, etc. The monomer is not particularly limited as long as it is a monomer copolymerizable with AN.
[0010]
As a method for introducing crosslinking with a hydrazine compound into the acrylic fiber, it can be adopted as long as the increase in nitrogen content can be adjusted within a range of 1.0 to 5.0% by weight. Means for treating the compound at a concentration of 5 to 60% and a temperature of 50 to 120 ° C. within 5 hours are industrially preferred. Here, the increase in the nitrogen content refers to the difference between the nitrogen content of the raw acrylic fiber and the nitrogen content of the acrylic fiber into which crosslinking by the hydrazine compound has been introduced.
[0011]
If the increase in nitrogen content is less than the above lower limit, a fiber having physical properties that can be finally satisfied in practice cannot be obtained, and if the upper limit is exceeded, the swelling rate of the fiber is lowered and the difference in moisture absorption is large. Hygroscopic fibers cannot be obtained. The hydrazine-based compound used here contains a plurality of amino groups such as hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, hydrazine bromate, hydrazine carbonate, etc., ethylenediamine, guanidine sulfate, guanidine hydrochloride, guanidine phosphate, melamine, etc. The compound to be illustrated is illustrated.
[0012]
As a method for converting a part of the remaining nitrile group after the crosslinking treatment with the hydrazine compound into an alkali metal salt type carboxyl group of 3.0 to 6.0 meq / g, the present inventor introduced a crosslinking bond by the treatment with the hydrazine compound. Thereafter, the above-described problems were achieved by performing acid treatment A and then hydrolysis with an alkali compound. According to this method, both the acid concentration of the acid treatment A after the introduction of the cross-linking and the alkali compound concentration in the next step can be made lower than the conventional method of alkali hydrolysis in one step, and easily Hygroscopic fibers that can be converted into a large amount of alkali metal salt-type carboxyl groups and maintain strength enough to withstand processing are provided.
[0013]
Examples of the acid used here include, but are not particularly limited to, aqueous solutions of mineral acids such as nitric acid, sulfuric acid, and hydrochloric acid, and organic acids. Prior to this treatment, the hydrazine compound remaining in the crosslinking treatment is sufficiently removed. Examples of the alkali used for the hydrolysis include basic aqueous solutions such as alkali metal hydroxides, alkaline earth metal hydroxides, and ammonia, but are particularly limited as long as they can be hydrolyzed. Not. The concentration of the acid and alkali to be used is not particularly limited, but both means of treating at 1 to 10% by weight and a temperature of 50 to 120 ° C. within 2 hours are preferred from the industrial and fiber properties viewpoints.
[0014]
There are roughly two methods for converting a carboxyl group produced by hydrolysis into an alkali metal salt type. One of them is hydrolysis with an alkali metal hydroxide, which directly generates an alkali metal salt-type carboxyl group. The second is a method of hydrolyzing with an alkaline earth metal hydroxide, ammonia or the like to once generate a different type of carboxyl group, and then substituting the group with the desired alkali metal salt type.
[0015]
In the second method, the substitution of the carboxyl group in the salt form includes means for immediately converting to an alkali metal salt form with an alkali metal hydroxide or a salt compound of the metal, or once acid treatment (as distinguished from the acid treatment A described above). There is a means for converting the carboxyl group to the H (acid) type by acid treatment B) and then converting it to the alkali metal salt type with the alkali metal compound. Since the amount of the alkali metal salt type carboxyl group required by the present invention is 3.0 to 6.0 meq / g, the “type” of the remaining carboxyl group is not limited as long as this amount is secured.
[0016]
The alkali metal salt type is literally Li, Na, K, and the fiber has a degree of swelling of 1.0 to 3.0 g / g when such a salt type carboxyl group is formed in the above-mentioned amount. In addition, although the kind of salt of a carboxyl group is Li, Na, K, it is not necessarily limited to any one of these, and two or more of these may be mixed in the same product fiber. . The means for evaluating the degree of swelling will be described later. After the conversion treatment to the alkali metal salt type, the fiber to be treated is washed with water, dried, or treated with an oil agent as necessary.
[0017]
In addition, when the alkali metal salt type carboxyl group is less than 3.0 meq / g, moisture absorption / release is not obtained, and when it exceeds 6.0 meq / g, fiber properties that are practically satisfactory cannot be obtained. As a result of proper introduction of cross-linking and conversion of a part of the nitrile group to an alkali metal salt type carboxyl group of 3.0 to 6.0 meq / g, the swelling degree of the fiber of the invention is 1.0 to 3.0 g. / G, the tensile strength is 0.7 dN / tex or more, and the sterilization rate is 90% or more. Such a fiber has a moisture absorption difference of 50% by weight or more and 150% by weight between 20 ° C. × 50% RH condition and 20 ° C. × 95% RH condition, which was not obtained in the invention disclosed in Japanese Patent Application Laid-Open No. 9-158040. It is a fiber having a large difference in moisture absorption of less than% by weight, and the difference in moisture absorption effective in practical performance is greatly improved as compared with conventional fibers or methods.
[0018]
Since the fiber of the present invention swells when an alkali metal salt-type carboxyl group is formed during the production process, the process for the final product, for example, the process for forming a non-woven fabric is performed to reduce the load in the drying process. Although the oil agent is attached for the purpose of improving the property, when the alkylamide quaternary cationic oil agent is attached to the fiber in the range of 1.0 to 2.5% omf as the oil agent, the difference in moisture absorption between the different conditions described above is It was found that the degree of swelling of the fiber decreased by 1 g / g without change.
[0019]
This knowledge provides an industrially advantageous method for producing the fiber of the present invention. When the oil agent adhesion amount is less than 1.0% omf, the degree of swelling does not decrease. On the other hand, when the oil agent adhesion amount is 2.5% omf or more, problems such as poor processability to a nonwoven fabric occur. Preferred examples of such alkylamide quaternary cationic oils include alkylamidopropyldimethyl β-hydroxyethylammonium nitrate R = (C16 to C18), stearylamidoethyldimethylhydroxyethylammonium chloride, cetylamidoethyl diethylmethylammonium methyl sulfate, and the like. It is done. According to the present invention, it is possible to provide a fiber having a tensile strength of 0.7 dN / tex or more, a high moisture absorption / release rate, a large moisture absorption difference, and antibacterial properties.
[0020]
As described above, the starting fiber of the present invention may be in the middle of the acrylic fiber production process or may be one after the fiber has been subjected to spinning or the like. As the starting acrylic fiber, fiber after drawing and before heat treatment (AN polymer spinning solution is spun in accordance with a conventional method, drawn and oriented, and not subjected to heat treatment such as drying densification, wet heat relaxation treatment, especially wet Or by using dry / wet spinning, stretched water-swelling gel fiber: water swelling degree 30-150%), the dispersibility of the fiber in the reaction solution, the permeability of the reaction solution in the fiber, etc. This is desirable because the introduction of a cross-linking bond and the hydrolysis reaction are performed uniformly and rapidly.
[0021]
In addition, these starting acrylic fibers are filled in a container equipped with a pump circulation system, introduction of the above-mentioned cross-linking, acid treatment A, alkali treatment, formation of alkali metal salt type carboxyl group, water washing, oil agent treatment, etc. It is desirable to take this means from the viewpoints of the apparatus, such as safety and uniform reactivity. An example of such a device (a container equipped with a pump circulation system) is a dyeing machine.
[0022]
Due to such a large difference in moisture absorption rate, the fiber of the present invention can be applied to a use that has not been heretofore or a use that has not been able to meet the demands of a conventional fiber. For example, moisture-absorbing material that absorbs water vapor before dew condensation, moisture-preventing material by absorbing water, moisture-absorbing / releasing material that absorbs water vapor (clothing, building materials, wallpaper, padding, etc.), environmental humidity control, temperature control Examples include materials. Moreover, the usage method of using as a part of coating materials, such as drying of a closet, a basement, an underfloor, a bathroom, etc. using a high moisture absorption difference performance, a dehumidification material, and an electronic material which dislikes a water | moisture content very much can be illustrated. Moreover, since this fiber has high hydrophilicity, it can be applied to uses such as absorbing moisture and releasing water vapor. Such an effect can be further enhanced by making the starting fiber into a fine denier yarn, a hollow fiber, a porous fiber, or the like. It is also effective to use a fibrillated fiber form, a brushed or flocked cloth or paper.
[0023]
Further, the fiber of the present invention is a hygroscopic fiber, but the state of the fiber when absorbed is not sticky, is moderately moist, and has an appropriate elongation. For this reason, it is a moist and supple fiber. Utilizing this property, it can be applied to moisturizing materials, beauty materials, high texture materials, and the like. In addition, when applied to cloth, paper, etc. soaked with hydrophilic chemicals, etc., there is an effect that since the moisture retention is high, the amount of impregnation is high and the material is difficult to dry. As such examples, those impregnated with disinfecting liquid, lotion, fragrance, deodorant, disinfectant, insect repellent and the like can be exemplified.
[0024]
The moisture absorption / release property of the fiber of the present invention is mainly expressed by an alkali metal salt type carboxyl group. By controlling this amount, moisture absorption and desorption can be controlled. For example, a method of introducing a large amount of carboxyl group by hydrolysis and controlling the amount of conversion to an alkali metal salt type carboxyl group to control moisture absorption and desorption can be performed. In the case of adopting such a method, there are various methods such as an acid treatment subsequent to hydrolysis with an alkali, but a method in which 3.0 to 6.0 meq / g of an alkali metal salt type carboxyl group can be present. If there is no particular limitation. However, industrially, there is a method of controlling the amount of the alkali metal salt-type carboxyl group by performing the acid treatment B and then the alkali metal salt treatment after the alkali hydrolysis, which is the second method described above. preferable.
[0025]
The fiber of the present invention has a high moisture absorption / release rate, and this rate can also be controlled by the fiber itself or the density of the molded body made of the fiber. When a very fast moisture absorption / release rate is required, use a thin moisture absorption / release fiber, use a fibrillated moisture absorption / release fiber, reduce the fiber density, raise the hair, and plant the hair. A method of increasing the area in contact with the moisture-releasing fiber and the moisture-containing gas can be employed. In addition, when a slow moisture absorption / release rate is required, the fiber density can be increased by increasing the density of processing into a nonwoven fabric or paper, or by using a high twist number during spinning, etc., or using thick moisture absorption / release fibers. Or the method of covering the fiber of this invention with the other substance which can permeate | transmit water vapor | steam, etc. can be employ | adopted.
[0026]
As described above, the fibers of the present invention also have a high difference in moisture absorption rate, moisture absorption / release properties, and antibacterial properties. The antibacterial property is indicated by the sterilization rate when measured by the shake flask method as shown in the examples, and the fiber of the present invention shows a sterilization rate of 90% or more.
[0027]
Since the fiber of the present invention has these characteristics, it can be handled very safely. Since normal fibers are susceptible to the generation of bacteria when they absorb moisture, hygiene often requires the use of fibers with antibacterial properties, etc., but there is no need to do this. It has. In addition, since it has flame retardancy, it is a very safe material to use at home, with little concern for fire, even if high temperature is applied during regeneration or the like.
[0028]
Since the material of the present invention has a cross-linked structure excellent in chemical resistance, the fiber form can be maintained even if it is treated with various chemicals. Therefore, the present invention can also be applied as a structure holding material for a structural material containing acid, alkali, or the like.
[0029]
[Action]
The reason why the moisture-absorbing / releasing fiber and the production method according to the present invention have a high moisture absorption difference and moisture-absorbing / releasing properties while having antibacterial properties has not been fully elucidated, but is generally considered as follows.
[0030]
That is, the fiber according to the present invention starts from an AN polymer, but the nitrile group is substantially reduced, so that the side chain bonded to the polymer chain is reacted with the hydrazine compound. The generated nitrogen-containing crosslinked structure and the alkali metal salt-type carboxyl group generated by the hydrolysis reaction of the nitrile group are considered to occupy most.
[0031]
In general, the alkali metal salt type carboxyl group has a hygroscopic property, but the present invention considers that the hygroscopic property is further enhanced because of its very large amount and a cross-linked structure with a lot of nitrogen. In addition, the mechanism that the carboxyl group is an alkali metal salt type and has an appropriate cross-linked structure, hydrogen functional bonds that should be involved in hygroscopicity do not contribute to hygroscopicity, is suppressed, It is estimated that it has a very high difference in moisture absorption and moisture absorption and desorption.
[0032]
Even if the fiber of the present invention contains a large amount of an alkali metal salt type carboxyl group, it has a fiber strength that can withstand various kinds of processing. This is estimated as follows. That is, since the acid treatment A and the alkali treatment are performed in two stages, the concentration of the reaction reagent is very low and the treatment time can be shortened. For this reason, it is estimated that it will not be subjected to a harsh treatment and has high fiber strength even if the amount of the alkali metal salt-type carboxyl group is large. Naturally, it may also be attributed to having a crosslinked structure.
[0033]
Antibacterial properties are presumed to be brought about by a nitrogen-containing cross-linked structure. Further, the absence of stickiness even when absorbing moisture may be due to the high cross-linking and the effect of the oil.
[0034]
【Example】
The present invention will be specifically described below with reference to examples. Parts and percentages in the examples are on a weight basis unless otherwise indicated. In addition, the amount of alkali metal salt-type carboxyl groups in the fiber, the moisture absorption rate, the degree of swelling, the oil agent adhesion rate, and the antibacterial properties were determined by the following methods.
[0035]
(1) Alkali metal salt type carboxyl group content (meq / g)
About 1 g of sufficiently dried test fiber is precisely weighed (Xg), 200 ml of water is added thereto, 1N hydrochloric acid aqueous solution is added to the solution while being heated to 50 ° C. to pH 2, and then 0.1N caustic soda aqueous solution is used. A titration curve was obtained according to a conventional method. The consumption amount (Ycc) of caustic soda solution consumed by all carboxyl groups was determined from the titration curve, and the total carboxyl group amount (meq / g) was calculated by the following formula.
(Total amount of carboxyl groups) = 0.1 Y / X
[0036]
Separately, a titration curve was similarly obtained without adjusting to pH 2 by addition of 1N aqueous hydrochloric acid during the above total carboxyl group amount measurement operation, and the acid type carboxyl group amount (meq / g) was obtained. From these results, the alkali metal salt type carboxyl group amount was calculated by the following formula.
(Amount of alkali metal salt type carboxyl group) = (Total amount of carboxyl group) − (Amount of acid type carboxyl group)
[0037]
(2) Moisture absorption rate (%)
About 5.0 g of sample fiber is dried at 120 ° C. for 5 hours with a hot air dryer, and the weight is measured (W1 g). Next, the sample is placed in a predetermined humidity chamber (50% RH and 95% RH) at a temperature of 20 ° C. for 24 hours. The weight of the sample thus absorbed is measured (W2g). From the above measurement results, calculation was performed according to the following equation.
(Hygroscopic rate) = (W2−W1) / W1 × 100 Moisture absorption difference refers to the difference between the 50% RH and 95% RH at 20 ° C. thus obtained.
[0038]
(3) Swelling degree (g / g)
About 3 g of sample fibers are dried with a hot air dryer at 70 ° C. for 3 hours, and the weight is measured (W1 g). Next, after immersing the sample in a beaker containing 300 ml of water for 30 minutes, the weight of the sample after the swollen sample was dehydrated with a desktop centrifugal dehydrator (160 G × 5 minutes) is measured (W2 g).
(Swelling degree) = (W2-W1) / W1
[0039]
(4) Oil agent adhesion rate (% omf)
About 3 g of the sample fiber is precisely weighed (W1) and placed in a glass cylindrical filter paper. This is placed in an extraction cylinder and a Kolben containing 100 to 120 ml of a solvent (primary ethyl alcohol) in advance is joined. Furthermore, a cooling tub is joined and extracted on a water bath at 97 ° C. or higher for 2 hours. When the solvent in the Kolben is sufficiently raised to the extraction cylinder, the Kolben is removed, the solvent is put in a petri dish, and this is evaporated to dryness in a water bath. The weight (W2) of the oil remaining in the petri dish is obtained and calculated by the following formula.
(Oil agent adhesion rate) = W2 / (W1-W2) × 100
[0040]
(5) The antibacterial test bacteria were K. pneumoniae, and the antibacterial and deodorized processed products were tested according to the processing effect evaluation test manual and shake flask method (Textile Products Sanitation Processing Council, 1988), and the sterilization rate was shown as%.
[0041]
Example 1
10 parts of an AN polymer (intrinsic viscosity [η]: 1.2) in dimethylformamide at 30 ° C.) consisting of 90% AN and 10% methyl acrylate (hereinafter referred to as MA) is dissolved in 90 parts of a 48% aqueous rhodium soda solution. After spinning and drawing (total draw ratio: 10 times) according to a conventional method, the spinning dope was dried in an atmosphere of dry bulb / wet bulb = 120 ° C./60° C. (process shrinkage 14%) to obtain a single fiber fineness. 1.5d raw fiber I was obtained.
[0042]
The raw material fiber I was subjected to crosslinking treatment and conversion of nitrile group to alkali metal salt type carboxyl group under the conditions shown in Table 1, followed by dehydration, washing with water and drying to obtain fiber No. 1. 1-8 were obtained. The properties of the obtained fibers were examined, and the results are shown in Table 1.
[0043]
[Table 1]

[0044]
The fiber No. of the present invention example in which the amount of increase in nitrogen is in the range of 1.0 to 5.0% by weight and the Na-type carboxyl group is in the range of 3.0 to 6.0 meq / g. 1-4 show that the degree of swelling is as high as 1.0 to 3.0 g / g and a high difference in moisture absorption, and it has high tensile strength and antibacterial properties.
[0045]
In contrast, fiber No. No. 5 has an increase in nitrogen of less than 1.0% by weight, so the amount of Na-type carboxyl group is within the range recommended by the present application and the difference in moisture absorption is large, but the tensile strength is a low value of 0.2 dN / tex. For this reason, the fiber was brittle and did not have physical properties to withstand processing such as card hanging. Similarly, the fiber No. 1 in which the amount of increase in nitrogen is larger than the recommended amount of the present invention although the amount of Na-type carboxyl group is satisfied. No. 6 has a sufficient tensile strength, but the objectives of the fiber swelling and moisture absorption difference are not achieved.
[0046]
On the other hand, although the increase in nitrogen was satisfied, conversion to Na-type carboxyl group was less than the recommended amount of the present invention. No. 7 has tensile strength but does not achieve the purpose of both the degree of swelling and the difference in moisture absorption of the fiber. Similarly, although the amount of increase in nitrogen is appropriate, the conversion to Na-type carboxyl group is higher than the recommended amount of the present invention. No. 8 has a sufficient difference in moisture absorption, but has a high degree of fiber swelling and a low tensile strength of 0.4 dN / tex. For this reason, the fiber was brittle and did not have physical properties to withstand processing such as card hanging.
[0047]
Example 2
No. 1 obtained in Example 1. No. 1 fiber 5 g was immersed in 1 L of a 5% aqueous solution of an alkali metal compound or alkaline earth metal compound shown in Table 2 at a temperature of 40 ° C. for 5 hours, then washed with water, dried, and fiber No. 1 having a different salt type. 9 to 11 were obtained. The properties of the obtained fiber were examined, and the results are shown in Table 2.
[0048]
[Table 2]

[0049]
Invention Example Fiber No. No. 1 which is a fiber converted to Na type 1 and Li type. 9, K type No. Compared with the fiber No. 10, the fiber No. The fiber having 11 Ca-type carboxyl groups has low fiber swelling and improved tensile strength, but the difference in moisture absorption is low and the purpose is not achieved. Alkali metal is effective as the carboxyl group salt type. I understand.
[0050]
Example 3
No. 1 obtained in Example 1. 1 g of fiber 1 is added to 0.5% aqueous solution and 1.5% aqueous solution of alkylamide propyl dimethyl β-hydroxyethylammonium nitrate (R = C16 to C18) which is an alkylamide quaternary cationic oil agent at 40 ° C. for 1 hour. After soaking, it was dehydrated and dried. 12 and 13 were obtained. The properties of the obtained fiber were examined, and the results are also shown in Table 3.
[0051]
[Table 3]

[0052]
Fiber No. 4 having an adhesion amount of 1.5% of alkylamide quaternary cationic oil agent. No. 12 and fiber No. having the same oil agent adhesion amount of 0.5%. Compared with No. 13, the moisture absorption difference does not change. In No. 12, since the degree of fiber swelling decreases, the drying load of the fiber is reduced in the production process, and thus it can be seen that the fiber can be produced industrially advantageously. On the other hand, when the oil agent adhesion amount is 0.5%, the fiber No. It is understood that there is no difference in the degree of swelling compared to 1, and 1.0% or more of adhesion is necessary for the purpose of reducing the drying load.
[0053]
【The invention's effect】
The present invention was able to provide a means for industrially advantageously producing hygroscopic fibers having a fiber property having no processing problems and having a large difference in the hygroscopicity required for practical performance as a humidity control material. This is a remarkable effect. The moisture-absorbing / releasing fibers thus obtained not only have improved moisture-absorbing / releasing properties, but also greatly improved the difference in moisture absorption rate, so that they can be used in applications that could not be applied conventionally. It also has antibacterial properties, low regeneration temperature, and because it is fibrous, it can be processed into various forms such as non-woven fabrics, knitted fabrics, and woven fabrics. In addition, since the moisture absorption / release rate can be controlled by controlling the density and the like, it can be widely used in fields where moisture absorption / release or heat generation due to moisture absorption is required.

Claims

Acrylic fiber having an acrylonitrile content of 85 to 95% by weight is subjected to a crosslinking treatment with a hydrazine compound, and the increase in nitrogen content due to the introduction of this cross-linking is in the range of 1.0 to 5.0% by weight. adjusted to continue the acid treatment, and subsequently subjected to hydrolysis with alkali to convert a portion of the nitrile groups remaining in the alkali metal salt type carboxyl groups 3.0~6.0meq / g, the alkyl A method for producing hygroscopic fibers, characterized in that an amide quaternary cationic oil agent is deposited in the range of 1.0 to 2.5 omf .