JP2004223385A

JP2004223385A - Humidifying material

Info

Publication number: JP2004223385A
Application number: JP2003013094A
Authority: JP
Inventors: Norio Ando; 則男安藤; Masao Kobayashi; 正男小林; Masahiro Shishido; 昌広宍戸; Tetsuya Otake; 哲也大竹
Original assignee: HYWOOD CO Ltd; R TEC KK
Current assignee: HYWOOD CO Ltd; R TEC KK
Priority date: 2003-01-22
Filing date: 2003-01-22
Publication date: 2004-08-12
Anticipated expiration: 2023-01-22
Also published as: JP3981022B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a humidifying material which can be manufactured at a low cost, can be applied for a wide usage, optionally exhibits a moisture absorbing/releasing function in responsive to variation in a relative humidity in air and is excellent in a keeping property of a humidifying effect. <P>SOLUTION: This humidifying material is formed by using a charcoal at calcination temperature of approximately 700°C as a humidifying base material and carrying a polyethylene glycol (PEG) as a humidifying agent on its surface. HCC (Humidity Control Capacity) value at the temperature of approximately 25°C of the humidifying material is high as 15-30% and a moisture absorbing/releasing speed is extremely quick. The moisture absorption is carried out when the relative humidity in air exceeds 70-80% RH (relative humidity) and the moisture release function is carried out at the RH of not less than 70-80%. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【産業上の利用分野】
本発明は、廃木材炭化木炭などの有機物を炭化した材料など、微細な細孔構造を有する基材にＰＥＧ等を膜状に担持させ、湿度をコントロールする性能を向上させた調湿材料に関するものである。
【０００２】
【従来技術】
空気中の湿気の状態によって吸湿や脱湿を行なう材料を調湿材（調湿材料）と呼んでいるが、これら調湿材の性能評価には調湿能力性能（ＨｕｍｉｄｉｔｙＣｏｎｔｒｏｌＣａｐａｃｉｔｙ、以後ＨＣＣと略記する。）が用いられている。これは環境湿度９０％ＲＨおよび５５％ＲＨにおける調湿材のそれぞれの平衡含水率の差をとったもので、この値が大きな素材ほど吸湿率が大きく、尚且つ脱湿率が大きく調湿能力に優れていると見なされている。
【０００３】
従来、液体もしくは固体による除湿剤や乾燥剤によって空気中から水分を化学的にもしくは物理的に吸着する吸湿剤（材）として、珪酸カルシウム水和物、水酸化カルシウム（ＣａＯＨ）、水酸化ナトリウム（ＮａＯＨ）、生石灰、ソーダ石灰、シリカゲル、クレイ（モリクロナイト）、ゼオライトなどの薬剤もしくはケイ酸化合物や活性炭などが使用されている。しかし、これらの除湿剤や乾燥剤は空気中の水分に反応して吸湿特性を示すが、放湿性が少ないなど吸放湿能力（ＨＣＣ）は、極めて低く調湿能力に優れているとはいえない。
【０００４】
この他、空気中から水分を物理的に吸着する吸湿剤として、カルボキシメチルセルロース、ポリビニルアルコール、ポリアリルアミン、水溶性酢酸セルロース、その他水溶性天然高分子系ポリマー類がある。しかし、これらの材料の大半は合成されたバージン状態では優れた吸湿特性を示すが乾燥固化した状態で空気中の水分を取込んだりするものは少ない。仮に可逆（もとに戻す、あるいは取り除く。）性がよく、乾燥後も水分を吸湿することが可能なものでもポリマーの水分許容に達すると潮解、もしくは吸湿しなくなり、材料単独で優れたＨＣＣ値を有している材料は少ない。
【０００５】
また、木材、木炭、活性炭、パーライト、石膏ボード、漆喰、木質繊維板、パルプ繊維、セメント、石膏、ゼオライト、珪素土等も多孔質構造による物理的吸放湿性を有しており優れた調湿材と言えるが、日常的な環境で木材や石膏ボード等が吸放湿によって平衡状態になるまでの吸放湿速度は、非常に遅く、木材の板材で５０〜１００時間、木材（厚物）や石膏・漆喰で１ケ月、モルタルやコンクリートは数年必要とするなど外気の変動にリアルタイムに追従する調湿性能は有していない。
【０００６】
以上、これらの除湿剤や乾燥剤、及び多孔質材料は、湿気の吸着（吸湿）には優れた性能を示すものの一度吸着した湿気を放湿（脱湿）しない物が多く、吸湿飽和に達すると潮解したり調湿機能をまったく発揮しないなど湿気の調整作用に適していないことが本発明者らの実験によっても確かめられた。
【０００７】
【発明が解決しようとする課題】
本発明は、空気中の相対湿度の変化に応じ任意に吸放湿作用を発揮し、調湿効果の持続性に優れ、かつ広範な用途に利用できる調湿材料を安価に提供することにある。
【０００８】
【課題を解決するための手段】
そこで本発明者らは、上記の課題を解決するため種々の検討を重ねた結果、調湿用木炭の吸放湿特性向上のため、木炭表面に親水性高分子であるポリエチレングリコール（ＰＥＧ）を担持させ、その調湿性能評価を行った。その結果、不担持の木炭に比べ調湿能力が２〜７倍向上することが確認できた。焼成温度が高い木炭ほどＰＥＧの担持量が大きく、また調湿能力の向上も大きく、さらにＰＥＧ木炭の吸湿量はＰＥＧおよび木炭単体による吸湿量の和から予測される値より大きくなることが明らかになった。これは相対湿度が高湿度の時は木炭表面のＰＥＧ膜に吸収された水分が木炭へ移動し貯蔵され、低湿度時には木炭に貯蔵された水分がＰＥＧ膜により吸収され大気中に放出されるという作用が働くためと考えられ、本発明はこれらの知見をもとに完成されたものである。
【０００９】
すなわち本発明は、空気中の水分を物理的に取り込むＰＥＧ及び同類の吸湿剤を、木炭をはじめとする各種多孔質基材の表面に担持させ、担持した調湿膜と基材の吸脱湿機構により任意の環境湿度に対応して吸放湿作用を発現する調湿材を提供するものである。
【００１０】
この発明の好ましい態様によれば、該吸湿剤が分子構造に−ＯＨ基や−ＣＯＯＨ、−Ｎ＜（−ＮＨ_２、−ＮＨφ、−Ｎφ）、＞ＣＯ、−Ｏ−等の基を持っている各種脂肪酸塩などの無機・有機両性を持たせた化合物や化学剤やそれらの混合液、及び、カルボキシメチルセルロース、ポリビニルアルコール水溶性酢酸セルロース、ポリエチレングリコール、及び水溶性天然高分子ポリマー、デンプン−ポリアクリロニトリル加水分解物、デンプン−ポリアクリル酸塩架橋物、カルボキシルメチルセルロース系、酢酸ビニル−アクリル酸メチル共重合体のケン化物、ポリアクリル酸ソーダ架橋物等から選ばれる吸着剤であり、該基材が木炭、活性炭、紙、繊維、羊毛、パーライト、及び、有機物を炭化した材料、また、石膏ボード、漆喰、木材、セメント、石膏、珪酸カルシウム水和物、シリカゲル、ゼオライト、クレイ（モリクロナイト）、その他ケイ酸化合物等の一種又は複数種から選ばれ、並びに基材が薄膜状、板状、繊維状、粒状、或いは粉末状の形態である調湿材が提供される。
【０００１１】
【発明の実施の形態】
本発明の調湿材は、ＰＥＧ及び同類の空気中の水分吸着作用を有する吸湿剤と基材に微細孔を持つ多孔質材を使用することを特長としている。本明細書において調湿と言う用語は空気中の水分すなわち湿気の吸着（吸湿）及び湿気の放湿（脱湿）を制御することを意味しており、吸湿や脱湿を行なう材料を調湿材（調湿材料）、また、これらの調湿材の調湿能力性能（ＨｕｍｉｄｉｔｙＣｏｎｔｒｏｌＣａｐａｃｉｔｙ以後ＨＣＣと略記。）は、吸湿・脱湿による乾燥や加湿も含めて使用している。
【００１２】
木炭の吸脱湿は細孔内で起こるために、細孔のサイズによりその特性が変化する。また細孔径の大きさは焼成温度および焼成時に供給するガスの種類などに影響を受けるので、調湿用木炭の製造には最適な焼成条件の設定が必要となる。しかし、木炭のＨＣＣ値は通常２〜３％でしかなく、調湿能力に優れているとはいえないことを本発明者らは実験によって確かめた。そこで焼成条件以外で木炭のＨＣＣ値を向上させる試みとして、木炭表面に親水性高分子のポリエチレングリコール（ＰＥＧ）を担持させることにより吸放湿性能の向上を目指し、さらにその評価を行った。
【００１３】
木炭は建築廃木材の粒状炭化材（焼成温度５００℃、７５０℃、９００℃、アールテック製）を、またＰＥＧは三洋化成工業Ｋ．ＫのＰＥＧ１０００およびＰＥＧ４０００（数値は数平均分子量）を用いた。ＰＥＧはＨＯ（ＣＨ２ＣＨ２０）ｎＣＨ２ＣＨ２０Ｈの化学式で表され、分子鎖末端の−ＯＨ基により親水性を示す。低湿度時にはほとんど吸湿せず高湿度環境では急激に吸湿量が増加するという親水性高分子特有の吸湿特性を持つ。
【００１４】
木炭は恒温乾燥器にて９５℃で２４時間乾燥を行った。またＰＥＧの２０ｗｔ％水溶液に乾燥木炭を２４時間浸漬し、余分な水溶液をろ過したものを９５℃で７時間乾燥し、ＰＥＧ担持試料木炭とした。上記の処理を行った試料はデシケーター内に保管した。木炭のＰＥＧ担持処理結果について表１に示す。木炭の焼成温度が高くなるにつれＰＥＧの担持量が多くなることが確認できた。９００℃焼成木炭ではほぼ自重と同じ重さのＰＥＧが担持される。
【００１５】
【表１】

【００１６】
【木炭の調湿能力】
図１にＨＣＣ実験装置の概略を示す。湿度を調節したガスを吸湿装置下部から供給し、試料の重量変化をロードセルにより測定した。また装置内の温度、湿度をセンサーにより測定。以上の測定結果をコンピュータに記録した。装置へ供給するガスの湿度は、恒温水槽中のバブラーを用いて１００％ＲＨに調湿した空気をボンベの乾燥Ｎ_２ガスで希釈する方法により調節した。測定に用いる試料重量は約５ｇとした。実験装置内に試料をセットし９０％ＲＨに調湿した空気を通気し平衡含水率Ｗ１を求めた。その後供給空気の湿度を５５％ＲＨに切替え平衡含水率Ｗ２を求め、Ｗ１とＷ２の差をＨＣＣ値とした。
含水率の定義を数式１に示す。
【００１７】
【数式１】

【００１８】
図２ａ，ｂに木炭の焼成温度と比表面積および細孔容積の関係を、表２に乾燥木炭の調湿能力の測定結果を示す。焼成温度の増加にともない木炭の比表面積、細孔容積の値は低下するが、Ｗ１並びにＷ２の値は共に増加が見られた。
【００１９】
【表２】

【００２０】
焼成温度が高くなると木炭が収縮を起こし、細孔径が小さくなるために比表面積、細孔容積の減少を招いたものと思われる。しかし水の吸着量は焼成温度が高くなるに従い増加することから、水の分子径と木炭の細孔径の間で最適な吸着条件が存在するものと思われる。しかし一度細孔に吸着された水分は湿度が５５％ＲＨに低下したくらいでは脱着されない。脱着する２％程度の水分は細孔に取込まれた水分由来のものではなく、木炭表面にわずかに存在する親水性の部分に吸着しているものと推測される。そのために水分の吸着量が増えてもＨＣＣ値に大きな変化は現れない。乾燥のみを目的として木炭を用いるのならば吸着量さえ増えれば良いが、調湿用として使用する場合には吸脱着が繰返し継続することが求められるため、吸着性能と同じく脱着性能が重要となる。以上の結果から、焼成条件の制御だけでは木炭のＨＣＣ値の大幅な向上は困難であると考えられる。
【００２１】
【ＰＥＧ含浸木炭の調湿能力】
ＰＥＧ１０００、４０００担持木炭ともに木炭焼成温度が高くなるほどＨＣＣ値が増加することが確認された。焼成温度が高いほどＰＥＧ担持量が増加するためＰＥＧの吸湿特性の影響が大きくなり、そのことが９０％ＲＨ雰囲気での吸湿量の増加に現れている。さらに木炭で見られた吸湿量の増加に伴う未脱着水分量の増加といった現象は起らず、このことがＨＣＣ値の向上につながっている。
【００２２】
またＰＥＧ１０００担持木炭の方がＰＥＧ４０００担持木炭よりも大きなＨＣＣ値を示す。これは同程度の量が担持された場合、平均分子量がＰＥＧ１０００の方が小さいことから−ＯＨ基の数が多くなり、単位面積あたりの水分の収着座の数が増加するためと考えられる。結果として未処理の木炭に比べＰＥＧ１０００担持木炭は４？７倍、ＰＥＧ４０００担持木炭では２〜５倍のＨＣＣ値の向上が見られた。表３参照。
【００２３】
【表３】

【００２４】
以上の結果をふまえ、ＰＥＧ担持木炭の表面状態について検討を行った。まず比表面積をＢＥＴ（島津フローソーブ２（注：ローマ数字の２である。）２３００）により測定した結果０．９６６ｍ^２／ｇという値が得られた。通常、木炭の比表面積は３００〜４００ｍ^２／ｇであることからこれは非常に小さな値である。
【００２５】
次に走査型電子顕微鏡（ＪＥＯＬＴ−３３０）によりＰＥＧ担持木炭の表面観察を行った。結果を図−３ａ，ｂに示す。観察結果より木炭で見られる導管構造がＰＥＧ担持木炭ではＰＥＧにより被覆されていることが確認された。低い比表面積の値は、木炭の骨格構造および細孔がＰＥＧ膜により覆われた結果である。したがってＰＥＧ担持木炭の吸放湿機構は主にＰＥＧ膜の吸放湿特性に依存しているものと推測される。
【００２６】
【ＰＥＧ担持木炭の吸脱湿機構】
まずＰＥＧ１０００単体の吸湿曲線を図４に示す。ＰＥＧ１０００は低湿度時あまり吸湿しないが、相対湿度が８０％ＲＨを越えると指数関数的に含水率が増加する。ＰＥＧ１０００は通常、白色ロウ状の固体であるが高湿度時には潮解を起す。実験においても９０％ＲＨ吸湿実験時に潮解を起しＰＥＧ水溶液となった。
【００２７】
次に飽和湿度時のＰＥＧ担持木炭の吸湿特性を図５に示す。１００％ＲＨ雰囲気下では木炭の細孔に水が凝縮するため、含水率が４０％を越えても水分の吸着が止らない結果となった。しかしこの状態でも木炭表面での濡れは観察されない。このことからＰＥＧ担持木炭表面に形成されたＰＥＧ膜中の保持水分量はそれほど多くはなく、水分の大部分は木炭へ移動し貯蔵されていることが推察された。
【００２８】
次にＰＥＧ膜担持担体としての木炭の効果を確認するために、ＰＥＧ単独での平衡含水率と木炭単独での平衡含水率を用いて、ＰＥＧ担持木炭のＰＥＧおよび木炭それぞれが単体として機能した場合の含水率を算出した。比較した結果を図６に示す。５５％ＲＨ時にはＰＥＧ担持木炭は、ＰＥＧ単体と木炭単体それぞれの含水率を加えて算出した値とほぼ同じ値を示す。そして９０％ＲＨ時には、ＰＥＧ担持木炭が単独のものの合計値よりも高い平衡含水率を示した。
これらのことから、高湿度時にはＰＥＧ膜から木炭へ水分の移動が起こりＰＥＧ担持担体として木炭がＰＥＧ担体としてばかりではなく、水分のリザーバとしても有効に働いていることが確認された。
【００２９】
以上の結果をふまえて、ＰＥＧ担持木炭の吸放湿のメカニズムは図７になる。ＰＥＧ単独での水分の取込み（吸着・溶解）は（ＰＥＧ＋水）の示す蒸気圧と空気中の水蒸気圧が等しくなったところで平衡状態に達し水分の取込みは終了する。ＰＥＧを木炭に担持した場合はＰＥＧ膜の背面に木炭が存在することで、（ＰＥＧ＋水）の状態から水だけが細孔内に吸上げられる。このメカニズムは毛細管現象で水が吸上げられＰＥＧ膜の裏側から出てきて木炭細孔内で凝縮していることによる。これにより（ＰＥＧ＋水）の水濃度がある濃度以上にならないためにＰＥＧの潮解現象は起らず、さらにＰＥＧ単独の時に比べ吸湿量が多くなる。そして脱湿時には木炭細孔内に凝縮した水分がＰＥＧ膜に取込まれ、さらに大気中に放出されることにより低い含水率を示すことになる。
【００３０】
以上、発明者らの実験から、焼成温度約５００℃、７００℃、９００℃の木炭の場合、杉や桧等の木炭が適しており空気に接触する有効面積の比率が大きいことが効果的である。これらの木炭は、比表面積３００〜４００ｍ^２／ｇ、平均細孔径１．５ｎｍ、細孔容積０．１ｃｃ／ｇであることが知見され、ＰＥＧ１０００を担持した本発明のＰＥＧ担持木炭と他の材料との比較実験を重ねた結果、９０％ＲＨと５５％ＲＨの湿度変化時におけるＨＣＣ値は、未処理炭や珪藻土、パーライトに水酸化ナトリウム処理した材料が１．０〜３．０％と低く一度吸着した湿気は吐き出さないという結果であった。これに対して本発明のＰＥＧ担持木炭（ＰＥＧ１０００）は、気温２５℃のＨＣＣ値で１５〜３０．０％とＨＣＣ値が高く、吸放湿速度が極めて早いこと、かつ特定な湿度反応域を持ち７０％ＲＨ以上になるとに優れた吸湿性能を発揮しそれ以下では放湿することが発見され、すぐれた調湿材料であることが確認された。
【００３１】
本発明の調湿材の適用対象はＰＥＧと木炭に限定されず、吸湿剤が分子構造に−ＯＨ基や−ＣＯＯＨ、−Ｎ＜（−ＮＨ_２、−ＮＨφ、−Ｎφ）、＞ＣＯ、−Ｏ−等の基を持っている等の他、脂肪酸塩、グリセリン脂肪酸、ソルビタン脂肪酸、ショ糖脂肪酸、及び、カルボキシメチルセルロース、ポリビニルアルコール、ポリアリルアミン、水溶性酢酸セルロース、及び天然高分子の水溶性ポリマー、デンプン−ポリアクリロニトリル加水分解物、デンプン−ポリアクリル酸塩架橋物、カルボキシルメチルセルロース系、酢酸ビニル−アクリル酸メチル共重合体のケン化物、ポリアクリル酸ソーダ架橋物等から選ばれる上記吸着剤の一種又は複数種であり、基材が紙、綿花繊維、化学繊維、羊毛、活性炭、パーライト、及び、有機物を炭化した各種材料、また、石膏ボード、漆喰、木質繊維板、木材、パルプ繊維、セメント、石膏、珪酸カルシウム水和物、生石灰、ソーダ石灰、シリカゲル、ゼオライト、珪素土、クレイ（モリクロナイト）、その他ケイ酸化合物等、及び鉱物性繊維材、硬質ポリウレタンフォーム等の一種又は複数種から選ばれ、並びに基材が薄膜状、板状、繊維状、粒状、或いは粉末状の形態である上記調湿材が適している。以下、本発明の範囲は下記の実施例に限定されることはない。
【００３２】
【実施例】
例１：本発明の調湿材の製造
実験から杉や桧等の木炭の場合、比表面積３００〜４００ｍ^２／ｇ、平均細孔径１．５ｎｍ、細孔容積０．１ｃｃ／ｇであり焼成温度が高くなると木炭が収縮を起こし、細孔径が小さくなるために比表面積、細孔容積の減少を招くが水分の吸着量は焼成温度が高くなるに従い増加する。このことから、水の分子径と木炭の細孔径の間で最適な吸着条件が存在することが確かめられたが、一方で、一度細孔に吸着された水分は湿度が５５％ＲＨに低下したくらいでは脱着されず脱着する水分は２％程度であり細孔に取込まれた水分由来のものではなく、木炭表面にわずかに存在する親水性の部分に吸着しているものが離れたものと推測された。
そのために水分の吸着量が増えてもＨＣＣ値に大きな変化は現れず乾燥のみを目的として木炭を用いるのならば吸着量さえ増えれば良いが、調湿用として使用する場合には吸脱着が繰返し継続することが求められるため、吸着性能と同じく脱着性能が重要となる。
そこで調湿用木炭の吸放湿特性向上のため、粒状木炭表面に親水性高分子であるポリエチレングリコール（ＰＥＧ）１０〜２０ｗｔ％希釈液を加圧缶体により含浸処理し、粒状木炭の表面にＰＥＧ膜を持ったＰＥＧ担持木炭を製造した。
【００３２】
例２：本発明の調湿材の調湿性能評価
このＰＥＧ担持木炭の５５％ＲＨ〜９０％ＲＨ雰囲気での調湿性能（ＨＣＣ）は、ＰＥＧ１０００の場合平均分子量がＰＥＧ４０００より小さいことから−ＯＨ基の数が多くなり、単位面積あたりの水分の収着座の数が増加するためＨＣＣ値１５％〜２０％を記録し、未処理の木炭に比べＰＥＧ１０００担持木炭は４〜７倍のＨＣＣ値を示す結果が得られた。その際の吸湿と放湿速度も吸湿速度は約８〜１６時間で吸湿率２２％上限に達し、放湿速度は約６時間で吸湿率５〜８％に下がること、さらに１００％ＲＨ雰囲気での吸湿増加は３０時間で吸湿率４５％にまで達する結果を得た。
【００３３】
例３：本発明の調湿材の吸放湿制御
また、ＰＥＧ１０００の場合、外気湿度による吸湿と放湿作用の切替えは、ＰＥＧ１０００の分子量特性として７０％ＲＨ〜８０％ＲＨを境にして、それ以下では放湿、以上では吸湿に転じることが確かめられた。
ＰＥＧ担持木炭の吸湿量はＰＥＧおよび木炭単体による吸湿量の和から予測される値よりさらに大きくなることが明らかになった。これは環境湿度が高湿度の時は木炭表面のＰＥＧ膜に吸収された水分が木炭へ移動し貯蔵され、低湿度時には木炭に貯蔵された水分がＰＥＧ膜により吸収され大気中に放出されるという機構が働くことが確認された結果である。
【００３４】
【発明の効果】
本発明の調湿材は、建物の取壊しにより多量に生じる建築廃木材など、従来産業廃棄物として焼却および埋立てにより処理されてきた原料から安価に製造可能であり、最終処分場の減少にともないリサイクル方法の確立が急務となっている廃木材や有機系廃棄物のリサイクル方法のひとつとして炭化した形で再利用するのが適している。木炭類の持つ吸放湿特性を利用し、これを調湿用資材として住宅等の床下などに敷設することで木造家屋床下の結露によるカビの発生や木材の腐朽を防ぐなど、調湿材として環境湿度の変化に応じて高い調湿効果を発揮する特長を有している。
【図面の簡単な説明】
【図１】ＨＣＣ実験装置の概略図。
【図２ａ】木炭の焼成温度と比表面積の関係をあらわした説明図。
【図２ｂ】木炭の焼成温度と細孔容積の関係をあらわした説明図。
【図３ａ】走査型電子顕微鏡で観察した未処理木炭の写真説明図
【図３ｂ】走査型電子顕微鏡で観察したＰＥＧ４０００担持木炭の写真説明図。
【図４】ＰＥＧ１０００の吸湿特性を表したグラフ。
【図５】ＰＥＧ１０００担持（７５０℃）木炭１００％ＲＨ雰囲気下での吸湿特性グラフ。
【図６】ＰＥＧ１０００担持木炭とＰＥＧのみ、炭のみの含水率の比較（７５０℃）図。
【図７】ＰＥＧ担持木炭の吸脱湿機構図。[0001]
[Industrial applications]
The present invention relates to a humidity control material in which PEG or the like is supported in a film form on a substrate having a fine pore structure, such as a material obtained by carbonizing an organic substance such as waste wood carbonized charcoal, and the humidity control performance is improved. It is.
[0002]
[Prior art]
Materials that absorb or dehumidify depending on the humidity in the air are called humidity control materials (humidity control materials). To evaluate the performance of these humidity control materials, Humidity Control Capacity (hereinafter referred to as HCC) is used. Abbreviated.) Is used. This is the difference between the equilibrium moisture contents of the humidity control materials at an environmental humidity of 90% RH and 55% RH. The larger the value, the higher the moisture absorption rate, the larger the dehumidification rate, and the larger the dehumidification rate. Is considered excellent.
[0003]
Conventionally, calcium silicate hydrate, calcium hydroxide (CaOH), sodium hydroxide (as a hygroscopic agent (material) that chemically or physically adsorbs moisture from the air by a liquid or solid dehumidifier or desiccant. NaOH), quick lime, soda lime, silica gel, clay (molycuronite), zeolite and other chemicals, silicate compounds, activated carbon, and the like are used. However, these dehumidifiers and desiccants exhibit moisture absorption properties in response to moisture in the air, but have a very low moisture absorption / desorption capacity (HCC) such as low moisture release properties, and are excellent in humidity control ability. Absent.
[0004]
In addition, humectants that physically adsorb moisture from the air include carboxymethylcellulose, polyvinyl alcohol, polyallylamine, water-soluble cellulose acetate, and other water-soluble natural polymer polymers. However, most of these materials exhibit excellent moisture absorption properties in a synthesized virgin state, but few of them take in moisture in the air in a dried and solidified state. If the polymer has good reversibility (return or remove) and can absorb moisture even after drying, it will not deliquesce or absorb moisture when it reaches the water tolerance of the polymer. Are few.
[0005]
In addition, wood, charcoal, activated carbon, perlite, gypsum board, plaster, wood fiber board, pulp fiber, cement, gypsum, zeolite, silicon earth, etc. also have physical moisture absorption and release properties due to the porous structure, and have excellent humidity control. Although it can be said to be wood, the moisture absorption and desorption rate until the wood and the gypsum board become equilibrium by moisture absorption and desorption in a daily environment is very slow, 50 to 100 hours with wood board, wood (thick) Moisture and gypsum / plaster require one month, and mortar and concrete require several years.
[0006]
As described above, these dehumidifiers, desiccants, and porous materials exhibit excellent performance in adsorbing moisture (moisture absorption), but do not release (dehumidify) moisture once adsorbed, and reach moisture absorption saturation. Then, it was also confirmed by the experiments of the present inventors that they were not suitable for the action of adjusting humidity, such as deliquescent and not exhibiting any humidity control function.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide an inexpensive moisture-conditioning material which exhibits a moisture-absorbing / desorbing action arbitrarily in accordance with a change in relative humidity in the air, has excellent durability of a humidity-controlling effect, and can be used for a wide range of applications. .
[0008]
[Means for Solving the Problems]
Therefore, the present inventors have conducted various studies to solve the above-mentioned problems, and as a result, in order to improve the moisture absorption and desorption characteristics of the charcoal for humidity control, polyethylene glycol (PEG), which is a hydrophilic polymer, is provided on the charcoal surface. It was carried, and its humidity control performance was evaluated. As a result, it was confirmed that the humidity control ability was improved by 2 to 7 times as compared with unsupported charcoal. It is clear that the higher the firing temperature, the greater the amount of PEG supported and the greater the improvement in the humidity control ability of the charcoal, and that the amount of moisture absorbed by PEG charcoal is larger than the value predicted from the sum of the amount of moisture absorbed by PEG and charcoal alone. became. This means that when the relative humidity is high, the water absorbed by the PEG film on the charcoal surface moves to the charcoal and is stored, and when the relative humidity is low, the water stored in the charcoal is absorbed by the PEG film and released to the atmosphere. It is considered that the action works, and the present invention has been completed based on these findings.
[0009]
That is, the present invention provides PEG and similar moisture absorbents that physically take in moisture in the air on the surface of various porous substrates, such as charcoal, and carries the moisture control membrane and moisture absorption / desorption of the substrate. An object of the present invention is to provide a humidity control material that exhibits a moisture absorbing / releasing action in response to an arbitrary environmental humidity by a mechanism.
[0010]
According to a preferred embodiment of the invention, absorbing moisture agent molecular structure -OH group or _{-COOH, -N <(- NH 2} , -NHφ, -Nφ),> CO, have a group of -O-, etc. Compounds and chemical agents and their mixed solutions, such as various fatty acid salts, etc., and carboxymethylcellulose, polyvinyl alcohol water-soluble cellulose acetate, polyethylene glycol, and water-soluble natural high-molecular polymers, starch-poly Acrylonitrile hydrolyzate, starch-polyacrylate crosslinked product, carboxymethylcellulose, vinyl acetate-saponified vinyl acetate methyl acrylate copolymer, crosslinked sodium polyacrylate, etc. Charcoal, activated carbon, paper, fiber, wool, perlite, and carbonized materials of organic matter, gypsum board, plaster, wood, Selected from one or more of mentite, gypsum, calcium silicate hydrate, silica gel, zeolite, clay (molycuronite), and other silicate compounds, and the base material is thin film, plate, fiber, granule, or powder. A humidity control material is provided that is in the shape of a letter.
[00011]
BEST MODE FOR CARRYING OUT THE INVENTION
The humidity control material of the present invention is characterized by using a PEG and similar moisture absorbents having an action of adsorbing moisture in air and a porous material having fine pores in a substrate. In the present specification, the term “humidity control” means to control the absorption (absorption) of moisture in the air, that is, moisture, and the release (dehumidification) of moisture, and to control the material for moisture absorption or dehumidification. The materials (humidity control materials) and the humidity control performance (hereinafter abbreviated as HCC) of these humidity control materials are used including drying and humidification by moisture absorption / dehumidification.
[0012]
Since the moisture absorption and desorption of the charcoal occurs in the pores, the characteristics thereof change depending on the pore size. In addition, since the size of the pore diameter is affected by the firing temperature, the type of gas supplied at the time of firing, and the like, it is necessary to set optimal firing conditions for the production of charcoal for humidity control. However, the present inventors have confirmed through experiments that the HCC value of charcoal is usually only 2 to 3%, and it cannot be said that the humidity control ability is excellent. Therefore, as an attempt to improve the HCC value of charcoal under conditions other than the firing conditions, the aim was to improve the moisture absorption / release performance by supporting a hydrophilic polymer, polyethylene glycol (PEG), on the charcoal surface, and further evaluated the same.
[0013]
Charcoal is a granular carbonized material of construction waste wood (calcination temperature 500 ° C, 750 ° C, 900 ° C, manufactured by R-Tech), and PEG is Sanyo Chemical Industries K.K. K PEG1000 and PEG4000 (numerical values are number average molecular weight) were used. PEG is represented by a chemical formula of HO (CH2CH20) nCH2CH20H, and shows hydrophilicity due to an -OH group at a molecular chain terminal. It has a moisture absorption characteristic of a hydrophilic polymer, which hardly absorbs moisture at low humidity and rapidly increases in high humidity environment.
[0014]
The charcoal was dried at 95 ° C. for 24 hours in a thermostatic dryer. Dried charcoal was immersed in a 20 wt% aqueous solution of PEG for 24 hours, and the excess aqueous solution was filtered and dried at 95 ° C. for 7 hours to obtain a PEG-supported sample charcoal. The sample subjected to the above treatment was stored in a desiccator. Table 1 shows the results of the PEG loading treatment of charcoal. It was confirmed that the amount of PEG supported increased as the firing temperature of the charcoal increased. In baked charcoal at 900 ° C., PEG having almost the same weight as its own weight is supported.
[0015]
[Table 1]

[0016]
[Charcoal humidity control ability]
FIG. 1 shows an outline of the HCC experimental apparatus. The gas whose humidity was adjusted was supplied from the lower part of the moisture absorbing device, and the weight change of the sample was measured by a load cell. The temperature and humidity inside the device are measured by sensors. The above measurement results were recorded on a computer. The humidity of the gas supplied to the apparatus was adjusted by a method in which air adjusted to 100% RH was diluted with dry N ₂ gas in a cylinder using a bubbler in a thermostatic water bath. The sample weight used for the measurement was about 5 g. The sample was set in the experimental apparatus, and air humidified to 90% RH was passed therethrough to obtain an equilibrium water content W1. Thereafter, the humidity of the supply air was switched to 55% RH to determine the equilibrium water content W2, and the difference between W1 and W2 was taken as the HCC value.
Equation 1 shows the definition of the water content.
[0017]
[Formula 1]

[0018]
2a and 2b show the relationship between the firing temperature of the charcoal, the specific surface area and the pore volume, and Table 2 shows the measurement results of the humidity control ability of the dried charcoal. As the firing temperature increased, the values of the specific surface area and the pore volume of the charcoal decreased, but the values of W1 and W2 both increased.
[0019]
[Table 2]

[0020]
It is considered that when the firing temperature is increased, the charcoal shrinks, and the pore diameter is reduced, resulting in a decrease in specific surface area and pore volume. However, since the amount of adsorbed water increases as the calcination temperature increases, it is considered that there exists an optimal adsorption condition between the molecular diameter of water and the pore diameter of charcoal. However, moisture once adsorbed in the pores is not desorbed even when the humidity drops to 55% RH. It is presumed that about 2% of the water to be desorbed is not derived from the water taken into the pores, but is adsorbed on a slightly hydrophilic portion present on the charcoal surface. Therefore, even if the amount of adsorbed moisture increases, a large change does not appear in the HCC value. If only charcoal is used for the purpose of drying, the amount of adsorption only needs to be increased, but if it is used for humidity control, adsorption and desorption must be repeated repeatedly, so desorption performance is important as well as adsorption performance. . From the above results, it is considered that it is difficult to significantly improve the HCC value of charcoal only by controlling the firing conditions.
[0021]
[Moisture control ability of PEG impregnated charcoal]
It was confirmed that the HCC value increased as the charcoal firing temperature increased for both PEG1000 and 4000-supported charcoal. The higher the firing temperature, the greater the amount of PEG carried, the greater the effect of PEG's moisture absorption properties, which is manifested in an increase in the amount of moisture absorption in a 90% RH atmosphere. Further, a phenomenon such as an increase in the amount of undesorbed water due to an increase in the amount of moisture absorption observed in charcoal does not occur, which leads to an improvement in the HCC value.
[0022]
The charcoal supporting PEG1000 shows a larger HCC value than the charcoal supporting PEG4000. This is presumably because, when the same amount is supported, the average molecular weight of PEG1000 is smaller, so that the number of -OH groups increases, and the number of sorption sites of water per unit area increases. As a result, compared with untreated charcoal, the HCC value of PEG1000-supported charcoal was improved by 4 to 7 times, and that of PEG4000-supported charcoal was improved by 2 to 5 times. See Table 3.
[0023]
[Table 3]

[0024]
Based on the above results, the surface condition of PEG-supporting charcoal was examined. First, the specific surface area was measured by BET (Shimadzu Flowsorb 2 (Note: Roman numeral 2) 2300), and as a result, a value of 0.966 m ² / g was obtained. This is a very small value, since the specific surface area of charcoal is usually 300 to 400 m ² / g.
[0025]
Next, the surface of the PEG-supporting charcoal was observed with a scanning electron microscope (JEOL T-330). The results are shown in FIGS. From the observation results, it was confirmed that the conduit structure observed in charcoal was covered with PEG in the charcoal supporting PEG. The low specific surface area values are the result of the charcoal skeletal structure and pores being covered by the PEG membrane. Therefore, it is assumed that the moisture absorption / release mechanism of the PEG-supporting charcoal mainly depends on the moisture absorption / release properties of the PEG membrane.
[0026]
[Moisture absorption and desorption mechanism of PEG-supporting charcoal]
First, FIG. 4 shows a moisture absorption curve of PEG1000 alone. PEG 1000 does not absorb much moisture at low humidity, but when the relative humidity exceeds 80% RH, the water content increases exponentially. PEG 1000 is usually a white waxy solid, but deliquesces at high humidity. In the experiment, deliquescence occurred during the 90% RH moisture absorption experiment, and the solution became an aqueous PEG solution.
[0027]
Next, the moisture absorption characteristics of PEG-supporting charcoal at the time of saturation humidity are shown in FIG. Under a 100% RH atmosphere, water condenses in the pores of the charcoal, so that even when the water content exceeds 40%, the adsorption of water does not stop. However, even in this state, no wetting on the charcoal surface is observed. This suggests that the amount of water retained in the PEG film formed on the surface of the PEG-supporting charcoal is not so large, and that most of the water is transferred to the charcoal and stored.
[0028]
Next, in order to confirm the effect of charcoal as a PEG membrane-supported carrier, using the equilibrium water content of PEG alone and the equilibrium water content of charcoal alone, PEG and charcoal of PEG-supported charcoal each functioned as a single substance. Was calculated. FIG. 6 shows the result of the comparison. At 55% RH, the charcoal carrying PEG exhibits almost the same value as the value calculated by adding the water content of each of PEG alone and charcoal alone. At 90% RH, the equilibrium water content was higher than the total value of the PEG-supporting charcoal alone.
From these facts, it was confirmed that at the time of high humidity, the movement of water from the PEG membrane to the charcoal occurred, and the charcoal worked effectively not only as a PEG carrier but also as a water reservoir as a PEG-supporting carrier.
[0029]
Based on the above results, the mechanism of moisture absorption and desorption of PEG-loaded charcoal is shown in FIG. Water uptake (adsorption / dissolution) by PEG alone reaches an equilibrium state when the vapor pressure indicated by (PEG + water) and the water vapor pressure in the air become equal, and the water uptake ends. When PEG is carried on charcoal, the presence of charcoal on the back of the PEG membrane allows only water to be sucked into the pores from the state of (PEG + water). This mechanism is based on the fact that water is sucked up by capillary action, comes out from the back side of the PEG membrane, and is condensed in the charcoal pores. As a result, since the water concentration of (PEG + water) does not exceed a certain concentration, the deliquescent phenomenon of PEG does not occur, and the amount of moisture absorption is larger than that of PEG alone. Then, at the time of dehumidification, the water condensed in the charcoal pores is taken into the PEG film and released into the atmosphere, thereby exhibiting a low water content.
[0030]
As described above, from experiments by the inventors, in the case of charcoal of about 500 ° C., 700 ° C., and 900 ° C., charcoal such as cedar and cypress is suitable, and it is effective that the ratio of the effective area in contact with air is large. is there. These charcoals were found to have a specific surface area of 300 to 400 m ² / g, an average pore diameter of 1.5 nm, and a pore volume of 0.1 cc / g. As a result of repeated experiments, the HCC values at the time of humidity changes of 90% RH and 55% RH were as low as 1.0 to 3.0% for untreated coal, diatomaceous earth, and perlite treated with sodium hydroxide. The result was that the moisture once adsorbed did not exhale. On the other hand, the PEG-supporting charcoal (PEG1000) of the present invention has a high HCC value of 15 to 30.0% as an HCC value at an air temperature of 25 ° C., has an extremely fast moisture absorption / desorption rate, and has a specific humidity reaction zone. It was found that the material exhibited excellent hygroscopicity when the durability was 70% RH or more, and released moisture when it was less than 70% RH, and was confirmed to be an excellent humidity control material.
[0031]
Application of humidity material of the present invention is not limited to PEG and charcoal, -OH group or -COOH desiccant in the molecular _{structure, -N <(- NH 2,} -NHφ, -Nφ),> CO, - In addition to having a group such as O-, a fatty acid salt, glycerin fatty acid, sorbitan fatty acid, sucrose fatty acid, and carboxymethyl cellulose, polyvinyl alcohol, polyallylamine, water-soluble cellulose acetate, and a water-soluble polymer of a natural polymer , Starch-polyacrylonitrile hydrolyzate, starch-polyacrylate cross-linked product, carboxymethylcellulose, saponified vinyl acetate-methyl acrylate copolymer, a kind of the above adsorbent selected from cross-linked sodium polyacrylate Or a plurality of types, the base material carbonized paper, cotton fiber, chemical fiber, wool, activated carbon, perlite, and organic matter Seed material, gypsum board, plaster, wood fiber board, wood, pulp fiber, cement, gypsum, calcium silicate hydrate, quicklime, soda lime, silica gel, zeolite, silicon earth, clay (molycuronite), other silicate compounds And the above-mentioned humidity control material in which the base material is in the form of a thin film, a plate, a fiber, a granule, or a powder is selected from one or more of a mineral fiber material, a rigid polyurethane foam, and the like. I have. Hereinafter, the scope of the present invention is not limited to the following Examples.
[0032]
【Example】
Example 1: From a production experiment of the humidity control material of the present invention, in the case of charcoal such as cedar and cypress, the specific surface area is 300 to 400 m ² / g, the average pore diameter is 1.5 nm, the pore volume is 0.1 cc / g, and the firing temperature is When the temperature increases, the charcoal shrinks and the pore diameter decreases, resulting in a decrease in specific surface area and pore volume. However, the amount of adsorbed water increases as the firing temperature increases. From this, it was confirmed that there was an optimal adsorption condition between the molecular diameter of water and the pore diameter of charcoal, but on the other hand, the moisture once adsorbed in the pores decreased the humidity to 55% RH. The amount of water desorbed without being desorbed by about 2% is not derived from the water taken into the pores, but the one adsorbed on the slightly hydrophilic part on the charcoal surface and the one separated Guessed.
Therefore, even if the amount of adsorbed moisture increases, the HCC value does not change significantly. If charcoal is used only for drying, the amount of adsorption may be increased, but when used for humidity control, adsorption and desorption are repeated. Since it is required to continue, desorption performance is important as well as adsorption performance.
Therefore, in order to improve the moisture absorption and desorption characteristics of the charcoal for humidity control, the surface of the granular charcoal is impregnated with a hydrophilic polymer, polyethylene glycol (PEG), in a 10-20% by weight diluent, using a pressure can. PEG-loaded charcoal with PEG membrane was produced.
[0032]
Example 2 Evaluation of Humidity Control Performance of Humidity Control Material of the Present Invention The humidity control performance (HCC) of this PEG-supporting charcoal in an atmosphere of 55% RH to 90% RH is -OH because PEG1000 has an average molecular weight smaller than PEG4000. Since the number of groups increases and the number of sorption sites for water per unit area increases, an HCC value of 15% to 20% is recorded, and the HCC value of PEG1000-loaded charcoal is 4 to 7 times that of untreated charcoal. The results shown were obtained. At this time, the moisture absorption rate reaches the upper limit of 22% in about 8 to 16 hours, and the moisture absorption rate drops to 5 to 8% in about 6 hours. The result obtained was that the moisture absorption increased to 45% in 30 hours.
[0033]
Example 3: Control of moisture absorption and desorption of the humidity control material of the present invention. In the case of PEG1000, switching between moisture absorption and dehumidification according to the outside air humidity is performed at 70% RH to 80% RH as a molecular weight characteristic of PEG1000. Below, it was confirmed that it turned to moisture release, and above it turned to moisture absorption.
It was found that the amount of moisture absorption of PEG-supported charcoal was larger than the value predicted from the sum of the amount of moisture absorption by PEG and charcoal alone. This means that when the environmental humidity is high, the water absorbed by the PEG film on the charcoal surface moves to the charcoal and is stored, and when the humidity is low, the water stored in the charcoal is absorbed by the PEG film and released to the atmosphere. This is the result of confirming that the mechanism works.
[0034]
【The invention's effect】
The humidity control material of the present invention can be manufactured at a low cost from raw materials that have been conventionally treated by incineration and landfill as industrial wastes, such as construction waste wood generated in large quantities by demolishing buildings, and as the number of final disposal sites decreases, As one of the recycling methods of waste wood and organic waste for which the establishment of a recycling method is urgently needed, it is suitable to reuse it in a carbonized form. Utilizing the moisture absorption and desorption properties of charcoal, it is used as a humidity control material by laying it under the floor of a house or the like as a humidity control material to prevent mold generation and wood decay due to condensation under the wooden house floor. It has the feature of exhibiting a high humidity control effect in response to changes in environmental humidity.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an HCC experimental device.
FIG. 2a is an explanatory view showing the relationship between the firing temperature of charcoal and the specific surface area.
FIG. 2b is an explanatory view showing the relationship between the firing temperature of the charcoal and the pore volume.
FIG. 3a is a photograph explanatory view of untreated charcoal observed by a scanning electron microscope. FIG. 3b is a photograph explanatory view of PEG4000-supporting charcoal observed by a scanning electron microscope.
FIG. 4 is a graph showing the moisture absorption properties of PEG1000.
FIG. 5 is a graph showing a moisture absorption characteristic under a 100% RH atmosphere carrying PEG1000 (750 ° C.) charcoal.
FIG. 6 is a comparison (750 ° C.) of the water content of PEG1000-loaded charcoal, PEG only, and charcoal only.
FIG. 7 is a diagram showing a moisture absorption / desorption mechanism of PEG-supporting charcoal.

Claims

When the humidity in the air becomes 70% RH or more, a PEG film (polyethylene glycol) exhibiting a hygroscopic action is carried on the surface of a porous substrate having fine pores, and only water is discharged from the PEG film by capillary action. By acting as a water reservoir by absorbing and condensing into the pores, the water concentration of (PEG + water) does not exceed a certain concentration, so that no deliquescence occurs in the PEG membrane, and PEG alone and The material exhibits a higher capacity of moisture absorption than that of the material alone. On the other hand, when the humidity in the outside air becomes 70% RH or less, the water condensed in the pores of the base material is taken into the PEG film and released to the atmosphere. Due to the difference in the molecular structure of PEG, the moisture absorption rate of the PEG film and the pore structure of the substrate are characterized by the fact that it exhibits a dehumidifying effect and promotes the release of water compared to the substrate alone and exhibits a low water content. Water condensation Synergy by a freely Moisture adjustment, which thin film, plate, fiber, granular or powder form and the humidity control material.

According to claim 1, polyethylene glycol (PEG) is supported on the surface of charcoal as a base material at a calcination temperature of about 700 ° C. in a film form, so that at high humidity, moisture in the air moves to the charcoal through the PEG film, The charcoal, which is the carrier of the PEG membrane, not only serves as a PEG carrier, but also stores water.On the contrary, when the outside air is low in humidity, the water condensed in the pores of the charcoal is taken into the PEG membrane and released into the air. A humidity control material having an HCC value of 15 to 30% at a humidity of 90% RH to 55% RH and a moisture absorption rate of 40% or more under an atmosphere of 100% RH.

Paper or cotton fiber prepared from the base material according to claim 1 so that moisture easily passes through water vapor and easily moves as semi-free water without being absorbed and fixed, and has a small moisture permeability resistance value and a small moisture permeability specific resistance value. , Chemical fiber, wool, activated carbon, perlite, and various materials carbonized with organic matter, gypsum board, plaster, wood fiber board, wood, pulp fiber, cement, gypsum, calcium silicate hydrate, quicklime, soda lime, 2. A PEG membrane is supported as in claim 1, comprising one or more of silica gel, zeolite, silicon earth, clay (molycuronite), other silicate compounds and the like, and mineral fiber, rigid polyurethane foam and the like. Humidity control materials.

Claim 1, claim 2, in addition to PEG according to claim 3, -OH group or -COOH, -N molecular structure _{<(- NH 2, -NHφ,} -Nφ),> CO, -O- etc. Etc., as well as fatty acid salts, glycerin fatty acids, sorbitan fatty acids, sucrose fatty acids, and carboxymethylcellulose, polyvinyl alcohol, polyallylamine, water-soluble cellulose acetate, and natural polymer polymers, starch-poly Acrylonitrile hydrolyzate, starch-polyacrylate crosslinked product, vinyl acetate-methyl acrylate copolymer saponified product, one or more of sodium polyacrylate crosslinked product, etc., as a moisture adsorbent in air, or as a film Humidity control material characterized by its use.