JP2004115738A - Adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive having strong adhesive force without releasing harmful substances such as formaldehyde. <P>SOLUTION: First, polyvinyl alcohol whose hydroxy groups are partly substituted with acylacetoxy groups and a diamine-based crosslinking agent are prepared each in a state of an aqueous solution. On the other hand, a member A and a member B each consisting of a wood, paper or cloth are prepared. Then, applying the substituted polyvinyl alcohol aqueous solution on the surface to be stuck of the member A, and the crosslinking agent aqueous solution on the surface to be stuck of the member B, respectively, and both surfaces to be stuck are stuck together. After a prescribed time of curing, hardening takes place and the member A and the member B are stuck together. At this time, a crosslinked polyvinyl alcohol is considered to be produced by a reaction illustrated in the scheme. The adhesive of this invention has excellent performances with high water resistance and heat resistance. <P>COPYRIGHT: (C)2004,JPO

Description

（Ｂ成分）：アミノ基を二個以上有する有機化合物。ただし、ここで「アミノ基」とは、−ＮＨ_２　または　−ＮＨ−　で表される原子団であり、炭素原子に直接結合していても良いし、結合していなくても良い。
【０００９】
【発明の実施の形態】
次に、本発明の実施形態について説明する。
【００１０】
（接着剤）
本発明の接着剤は、強固な接着力を有し、しかもホルムアルデヒド等の有害物質を放出することがない。さらに、生分解性を有することにより、土壌中等に残留して環境汚染の原因となることがない。また、前記Ａ成分とＢ成分とが室温で短時間に反応して硬化するという性質を有することにより、加熱等の手間がなく容易に接着できる。
【００１１】
本発明の接着剤は、使用前においては前記Ａ成分およびＢ成分は混合されずに独立して存在し、使用時に、接着対象物における接着面の一方に前記Ａ成分を、他方に前記Ｂ成分を塗布し、前記Ａ成分を塗布した面とＢ成分を塗布した面とを接触させて両成分を反応させ、接着力を発生させることが好ましい。しかし、本発明の接着剤の使用形態はこれに限定されず、他の方法により使用することも可能である。例えば、使用前においては前記Ａ成分およびＢ成分は混合されずに独立して存在し、使用時に前記Ａ成分と前記Ｂ成分とを混合し、接着対象物における接着面の一方または双方に前記混合物を塗布し、前記接着面同士を接触させて接着しても良い。
【００１２】
本発明の接着剤において、使用前における前記Ａ成分およびＢ成分の形態は特に限定されないが、例えば、水溶液の状態であることが好ましい。すなわち、前記Ａ成分およびＢ成分が水溶性を有することにより、有機溶媒を使用する必要がないため、有機溶媒由来の有害物質が放出されるおそれがなく、しかも接着剤としての使い勝手が良い。また、本発明の接着剤における前記Ａ成分と前記Ｂ成分との使用量比は特に限定されないが、例えば質量比で１０：１００〜１０：０．１、好ましくは１０：１０〜１０：１、より好ましくは１０：４である。
【００１３】
本発明の接着剤は、例えば、木、紙および布のうち少なくとも一種類を接着した製品の製造に使用することができ、特に木製品の製造に使用することが好ましい。具体的な製品は特に限定されないが、木製品としては例えば木造住宅および室内装飾品等、紙製品としては例えば紙管等の製造に使用することができる。また、上記製品は同種の材質同士の接着に限定されず、木と紙、紙と布等の異質な材質を本発明の接着剤により接着しても良い。
【００１４】
（接着主剤）
次に、前記接着主剤（Ａ成分）について説明する。
【００１５】
本発明の接着剤における接着主剤は、前記の構造を有する置換ポリビニルアルコールである。前記式（１）中、Ｒ^１は、好ましくは炭素数１〜６の直鎖または分枝アルキル基、より好ましくは、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基、ｓｅｃ−ブチル基およびｔｅｒｔ−ブチル基からなる群から選択される少なくとも一つであり、特に好ましくはメチル基である。また、水酸基のアシルアセトキシ基による置換度は特に限定されないが、水溶性の観点から４０％以下が好ましい。この場合、前記置換度の下限は特に限定されないが、０％を超える値であることは言うまでもない。
【００１６】
前記置換ポリビニルアルコールは、例えば、下記スキーム１のようにして製造することができる。すなわち、式（６）で表されるポリビニルアルコールと、式（７）で表されるジケテンとを反応させ、前記ポリビニルアルコール（６）の水酸基の一部をアセトアセチル基で置換して、式（８）で表される置換ポリビニルアルコールを得る。なお、式（６）および（８）は、それぞれ分子の一部分を表している。この反応を行なう条件は特に限定されないが、例えばＤＭＳＯ等の非プロトン性極性溶媒を用いて行なうことが出来る。
【化４】

【００１７】
（架橋剤）
次に、前記架橋剤（Ｂ成分）について説明する。
【００１８】
本発明の接着剤における架橋剤は、前記の通り、アミノ基を２個以上有する有機化合物であり、下記（Ｉ）および（ＩＩ）に記載の物質のうち少なくとも一方であることが好ましい
（Ｉ）　下記一般式（２）から（５）で表される化合物のうち少なくとも一種類。
【化５】

ただし、上記式中、Ｒ^２〜Ｒ^７はそれぞれアルキレン基である。
（ＩＩ）　タンパク質分子の全部または一部をヒドラジン分解して得られる化合物。ただし、ここで「タンパク質」とは、ペプチドであっても良い。
【００１９】
前記式（２）から（５）において、Ｒ^２〜Ｒ^７は、好ましくは、それぞれ炭素数１〜１２の直鎖または分枝アルキレン基であり、より好ましくは、それぞれ炭素数１〜６の直鎖アルキレン基である。
【００２０】
前記式（２）から（５）においては、
Ｒ^２がメチレン基、ジメチレン基（エチレン基）、トリメチレン基またはテトラメチレン基であり、
Ｒ^３がジメチレン基（エチレン基）またはヘキサメチレン基であり、
Ｒ^４およびＲ^５がそれぞれジメチレン基（エチレン基）であり、
Ｒ^６およびＲ^７がそれぞれジメチレン基（エチレン基）であることが特に好ましい。
【００２１】
前記タンパク質は、特に限定されないが、ゼラチンおよびカゼインのうち少なくとも一方が好ましい。ゼラチンは精製ゼラチンでも良いが、いわゆるニカワ（膠）と呼ばれる未精製ゼラチンを使用することができる。
【００２２】
前記タンパク質のヒドラジン分解に際しては、例えば下記スキーム２のような反応が起こると考えられる。なお、Ｒ^８、Ｒ^９およびＲ^１０は、タンパク質中のアミノ酸残基側鎖であり、それぞれ同一でも異なっていても良い。ヒドラジン分解の条件は特に限定されないが、例えば、６０〜７０℃で３〜４時間反応させる。
【化６】

【００２３】
また、上記ヒドラジン分解に際して、ヒドラジンの添加量は特に限定されないが、残存するヒドラジンが接着主剤と架橋剤との反応を阻害する可能性があるため、適量を使用することが好ましい。前記ヒドラジン添加量は、タンパク質に対し例えば１〜１００重量％、好ましくは３〜１００重量％、より好ましくは５〜１００重量％である。また、前記阻害の機構としては、例えば、架橋剤中に残留したヒドラジンが、下記スキーム３のように置換ポリビニルアルコール上の置換基を切断すると考えられる。
【化７】

【００２４】
本発明に使用する架橋剤は、前記式（３）および（４）で表される化合物からなる群から選択される少なくとも一種類であることが、さらに接着力に優れるため好ましい。
【００２５】
なお、本発明の接着主剤と架橋剤との反応においては、例えば下記スキーム４のような反応が起こっていると考えられる。なお、Ｒ^１１は、架橋剤分子から両端のアミノ基を除いた部分を表す。
【化８】

【００２６】
【実施例】
次に、本発明の実施例について説明する。
【００２７】
［合成］
以下のようにして、アセトアセチル化ポリビニルアルコール（以下、「ＡＡ−ＰＶＡ」と呼ぶことがある。）および各種架橋剤を合成した。
【００２８】
（ＡＡ−ＰＶＡの合成）
ポリビニルアルコール（和光純薬工業株式会社、平均重合度４００〜６００、ケン化率９６ｍｏｌ％以上）とジケテン（和光純薬工業株式会社）とを原料に用い、ジメチルスルホキシド（ＤＭＳＯ）を溶媒に用いてＡＡ−ＰＶＡを合成した。具体的には、まず、１０００ｍｌ四つ口フラスコにポリビニルアルコール（ＰＶＡ）とＤＭＳＯとを入れ、窒素雰囲気下、約６０℃に加熱し、ＰＶＡが完全に溶解するまでメカニカルスターラーで攪拌した。次に、この溶液中に、ジケテン（Ｄｉｋｅｔｅｎｅ）を滴下ろうとを用いて約３０分間かけて滴下し、１時間反応させた。その後反応を停止させ、反応溶液にエタノールとヘキサンの混合溶媒を加えてＡＡ−ＰＶＡを沈殿させ、沈殿物を分離して水に溶解させた。その水溶液を透析膜（和光純薬工業株式会社、サイズ３６）を用いて透析し、凍結乾燥して目的物を得た。
【００２９】
ＰＶＡとジケテンとのモル比を変化させることにより、様々なアセトアセチル化度（ＡＡ化度）のＡＡ−ＰＶＡを合成した。例えば、ＰＶＡ、ジケテンおよびＤＭＳＯをそれぞれ下記表１の使用量で合成を行なったところ、ＡＡ化度がそれぞれ６．３％、１２．７％、２１．２％および３５．９％のＡＡ−ＰＶＡが得られた。図１〜４に、それぞれの^１ＨＮＭＲ測定図を示す。なお、本実施例における^１ＨＮＭＲ測定用機器としては、ＪＥＯＬ社の商品名ＥＸ−２７０を用いた。また、測定溶媒にはＤＭＳＯ−ｄ_６を使用した。
【表１】

【００３０】
なお、ＡＡ−ＰＶＡのＡＡ化度は、^１ＨＮＭＲを測定してピーク面積を算出し、下記式により求めた。ただし、ＸはＡＡ化度、Ｗ_ＡＡは、アセトアセチル基由来メチル基プロトン（２．５ｐｐｍ付近）のピーク面積、Ｗ_ＰＶＡは、ＰＶＡ主鎖由来メチレン基プロトン（１．５〜２．２５ｐｐｍ付近）のピーク面積である。
Ｘ（％）＝（Ｗ_ＡＡ／（１．５×Ｗ_ＰＶＡ））×１００
【００３１】
上記以外にも、同様の方法により、種々のＡＡ化度を有するＡＡ−ＰＶＡを合成した。図５〜７に、ＡＡ化度が４．４％、７．５％および１４．３％のものの^１ＨＮＭＲ測定図をそれぞれ示す。
【００３２】
さらに、上記各ＡＡ−ＰＶＡは、ＦＴ−ＩＲ測定によりＡＡ化がなされていることを確認した。ＡＡ化度が高いほどアセトアセチル基中のカルボニル基由来ピーク（１７１０ｃｍ^−１および１７３０ｃｍ^−１）が増大し、ヒドロキシ基由来ピーク（３４００ｃｍ^−１）が減少していた。ＦＴ−ＩＲは、ＡＡ−ＰＶＡの薄膜を作製して測定し、測定用機器としては、島津製作所株式会社の商品名ＦＴ−ＩＲ　８２００Ｄを使用した。
【００３３】
（ヒドラジド系架橋剤の合成）
マロン酸ジメチル、コハク酸ジメチルおよびグルタル酸ジメチル（いずれも東京化成工業株式会社）を、それぞれヒドラジン一水和物（ナカライテスク株式会社）と反応させ、マロン酸ジヒドラジド（ＭＤＨ）、コハク酸ジヒドラジド（ＳＤＨ）およびグルタル酸ジヒドラジド（ＧＤＨ）を得た。具体的には、まず、エタノール２００ｍｌ中に、上記カルボン酸エステルとヒドラジン一水和物とを約１：２．１のモル比で投入して攪拌し、反応させてヒドラジド化合物を得た。次に、そのヒドラジド化合物をメタノールからの再結晶により精製した。すなわち、まず、ヒドラジド化合物とメタノールとをナスフラスコに入れ、還流冷却器を付けて水浴上で約６７℃に加熱してヒドラジド化合物を溶解させた。次に、その溶液を熱いまま濾過して不溶物を除去して透明な濾液を得た後、その濾液を冷却して結晶を析出させた。その結晶を室温で吸引濾取し、真空乾燥して目的物を得た。下記表２に、本合成における各試薬の使用量を、また、下記表３に、各ヒドラジド化合物の収量および収率を示す。
【表２】

【表３】

【００３４】
（タンパク質系架橋剤の合成）
ニカワおよびカゼインをそれぞれヒドラジン分解し、架橋剤を合成した。試薬としては、ニカワ（新田ゼラチン、粘度６５．６ｍＰ、ゼリー強度１８２ｇ）、ニュージランドカゼイン（日成共益株式会社、ＡＬＡＣＩＤファースト、３０Ｍ）、ヒドラジン一水和物（ナカライテスク株式会社）、および水酸化ナトリウム（キシダ化学株式会社、特級）を用いた。なお、ここで、水酸化ナトリウム以外の試薬は、化学用または一般用である。
【００３５】
ニカワのヒドラジン分解は、以下のようにして行なった。すなわち、まず、三つ口フラスコにジムロート冷却管と温度計とを取り付け、ニカワと蒸留水とを入れ、室温で約１時間放置し、ニカワをある程度溶解させた。次に、これを水浴上で６０〜７０℃に加温しながら攪拌し、ニカワを完全に溶解させた後、ヒドラジン一水和物を加え、７０℃で３時間攪拌して反応させ、ニカワが部分的にヒドラジン分解された架橋剤を得た。反応後の水溶液は、冷却した後、そのまま接着試験に使用した。本合成では、ニカワとヒドラジンとの混合比を種々変化させて８種類合成した。下記表４に、試薬の使用量を示す。
【表４】

【００３６】
カゼインのヒドラジン分解は、以下のようにして行なった。すなわち、まず、三つ口フラスコにジムロート冷却管と温度計とを取り付け、カゼインと蒸留水とを入れ、室温で約１時間放置し、カゼインをある程度溶解させた。次に、これを水浴上で６０〜７０℃に加温しながら攪拌し、カゼインを完全に溶解させた。そして、ここに１０％水酸化ナトリウム水溶液（蒸留水を使用）を加え、ｐＨを８に調製した。さらに攪拌し、溶液が粘稠なのり状になった後、ヒドラジン一水和物を加え、７０℃で３時間攪拌して反応させ、カゼインが部分的にヒドラジン分解された架橋剤を得た。反応後の水溶液は、冷却した後、そのまま接着試験に使用した。本合成では、カゼインとヒドラジンとの混合比を変化させて２種類合成した。下記表５に、試薬の使用量を示す。
【表５】

【００３７】
（その他の架橋剤）
その他、本実施例に使用する架橋剤として、１，２−エチレンジアミン、１，６−ヘキサメチレンジアミン、ジエチレントリアミン、ピペラジン６水和物（以上、キシダ化学株式会社）、ポリエチレンイミン（３０％水溶液、Ｍｗ６００００〜８００００、ナカライテスク株式会社）、およびアジピン酸ジヒドラジド（市販品）をそれぞれ準備した。これらは、購入したものをそのまま使用した。なお、アジピン酸ジヒドラジドはヒドラジド系化合物であるが、本実施例では、便宜上「その他の架橋剤」として取り扱う。
【００３８】
［接着試験］
上記ＡＡ−ＰＶＡと、各種架橋剤とをそれぞれ用いて接着試験を行なった。なお、コールドプレスには神藤金属工業所製ＹＳ−５型テストプレス（商品名）を使用し、圧縮せん断試験（引っ張り試験）には、新興通信社製ＴＭＣ−５００型圧縮引張万能試験機（商品名）を使用した。
【００３９】
（実施例１：ヒドラジド系架橋剤を用いた接着試験）
まず、前記ヒドラジド系架橋剤を用いた接着試験を行なった。
【００４０】
ＡＡ−ＰＶＡの水溶液（以下、「水性ワニス」または「ワニス」と呼ぶことがある）と、前記ヒドラジド系架橋剤の水溶液とをそれぞれ調製し、試験片（被着材）としてラワン材を用いて、圧縮せん断接着強さ試験法により初期接着力および最終接着力を測定した。最終接着力については、常態試験と耐水試験によりそれぞれ測定した。前記各接着試験は、前記ＡＡ−ＰＶＡ水性ワニスおよび前記架橋剤水溶液をそれぞれ別の接着面に塗布して貼り合せる、いわゆるハネムーン型接着により行なった。ＡＡ−ＰＶＡワニスはＡＡ化度が６．３％、１２．７％、２１．２％および３５．９％のＡＡ−ＰＶＡをそれぞれ３０重量％濃度に調製したものを、架橋剤水溶液については前記各架橋剤を５重量％、１０重量％および２０重量％濃度に調製したものをそれぞれ用いて試験を行なった。ＡＡ−ＰＶＡワニスおよび架橋剤水溶液の塗布量は、それぞれ１００ｇ／ｍ^２および４０ｇ／ｍ^２とした。接着条件は、プレス圧０．６９ＭＰａ（７ｋｇｆ／ｃｍ^２）、圧締時間５分間とし、その他の条件はＪＩＳ６８５２により行なった。各試験の最終結果は、１０回の試験の平均値により決定した。
【００４１】
初期接着力は、以下の条件により測定した。すなわち、まず、被着材として、幅２．５ｃｍ、長さ３ｃｍ、厚さ１ｃｍのラワン材を２個準備した。次に、一方の被着材の片面に前記ＡＡ−ＰＶＡワニス０．０６２５ｇを、もう一方の被着材の片面に前記架橋剤水溶液０．０２５ｇを塗布した。塗布面積はそれぞれ２．５ｃｍ×２．５ｃｍとし、長さ方向の一端から０．５ｃｍは塗布せずに残した。その後、各被着材を４分半開放放置し、塗布面同士を貼り合せてさらに３０秒間放置し、そして５分間コールドプレスした。図８に、前記被着材の貼り合せ状態の斜視図を模式的に示す。コールドプレス後、圧縮せん断速度（クロスヘッドスピード）２ｍｍ／ｍｉｎで初期接着力測定を行なった。
【００４２】
最終接着力（常態試験および耐水試験）は、以下の条件により測定した。すなわち、まず、ラワン材の幅が１２ｃｍであることと、ＡＡ−ＰＶＡワニスおよび架橋剤水溶液の塗布量がそれぞれ０．３ｇおよび０．１２ｇであること以外は前記初期接着力試験と同様にしてコールドプレスを行なった。図９に、被着材の貼り合せ状態の斜視図を模式的に示す。コールドプレス後、貼り合せた被着材を４８時間養生し、２．５ｃｍ幅に切断して試験片を作製し、試験を行なった。なお、ここまでの操作および試験片の形状は、常態試験、耐水試験とも同じである。常態試験は、４８時間養生し切断して作製した試験片をそのまま用いて行なった。耐水試験は、前記試験片を３０±１℃の水に３時間浸し、続いて２０±１℃の水に１０分間浸した後、乾燥せずに直ちに試験した。圧縮せん断速度は、常態試験および耐水試験ともに２ｍｍ／ｍｉｎとした。
【００４３】
（実施例１−１）
ＡＡ化度２１．２％のＡＡ−ＰＶＡワニスに対し、マロン酸ジヒドラジド（ＭＤＨ）の５重量％、１０重量％および２０重量％水溶液をそれぞれ用い、初期接着試験、常態試験および耐水試験を行なって接着強度を測定した。常態試験および耐水試験においては木破率も測定した。図１０〜１２に、初期接着試験、常態試験および耐水試験の結果をそれぞれグラフで示し、図１３および下記表６に、それら全ての試験結果をまとめて示す。
【表６】

【００４４】
図１０〜１３および表６から分かる通り、いずれの濃度のＭＤＨ水溶液を用いても良好な接着強度試験結果が得られたが、総合すると、１０重量％ＭＤＨ水溶液が接着強度、木破率ともに高く優れていた。
【００４５】
（実施例１−２）
次に、ＡＡ化度２１．２％のＡＡ−ＰＶＡワニスに対し、１０重量％濃度のマロン酸ジヒドラジド（ＭＤＨ）、コハク酸ジヒドラジド（ＳＤＨ）およびグルタル酸ジヒドラジド（ＧＤＨ）水溶液をそれぞれ用いて初期接着試験を行ない、接着強度を測定した。さらに、架橋剤（プライマー、以下、Ｐと記することがある）を用いない以外は同様にして初期接着試験を行ない、架橋剤を用いた場合との比較を行なった。図１４および下記表７にその結果を示す。
【表７】

【００４６】
図１４および表７から分かる通り、ＭＤＨ、ＳＤＨおよびＧＤＨのそれぞれを架橋剤として用いると、架橋剤を用いない場合と比較して接着強度が飛躍的に向上した。
【００４７】
（実施例１−３）
さらに、ＡＡ化度がそれぞれ６．３％、１２．７％、２１．２％および３５．９％のＡＡ−ＰＶＡワニスに対し、１０重量％濃度のマロン酸ジヒドラジド（ＭＤＨ）、コハク酸ジヒドラジド（ＳＤＨ）およびグルタル酸ジヒドラジド（ＧＤＨ）水溶液をそれぞれ用いて常態試験および耐水試験を行なった。さらに、架橋剤を用いない以外は同様にして常態試験および耐水試験を行ない、架橋剤を用いた場合との比較を行なった。図１５〜１９および下記表８に、それぞれのデータを架橋剤の種類により比較した結果を示す。
【表８】

【００４８】
図１５〜１９および表８から分かる通り、架橋剤を用いた場合は、いずれの架橋剤においても架橋剤なしの場合と比較して極めて良好な接着試験結果が得られ、特に耐水試験では接着強度および木破率が大幅に向上していた。架橋剤なしの場合は、常態試験での接着強度においては、特にＡＡ化度３５．９％では比較的良好な結果が得られたが、木破率が低く、また、耐水試験では接着強度および木破率ともに低く実用に耐えなかった。
【００４９】
図２０〜２８と、下記表９および表１０に、上記と同じデータをＡＡ化度により比較した結果を示す。図２０〜２６および表９は、常態試験と耐水試験とのデータを別々にまとめて比較したものであり、図２７および２８と表１０は、常態試験と耐水試験とのデータを同一のグラフおよび表にまとめたものである。
【表９】

【表１０】

【００５０】
図２０〜２８と、表９および表１０から分かる通り、架橋剤を用いた場合は、いずれの架橋剤でも、どのＡＡ化度でも良好な接着試験結果が得られた。特に、ＡＡ化度６．３％の場合は、どの架橋剤を用いても、常態試験と耐水試験の両方において、および接着強度と木破率との両方において極めて良好な結果が得られた。
【００５１】
また、図２７および２８から分かる通り、架橋剤を使用した場合は、特にＡＡ化度６．３％の場合は、耐水試験においても常態試験と大差ない接着強度および木破率が得られた。このことは、本実施例における接着剤が高い耐水性を有し、木材片に対する接着剤として優秀であることを示す。
【００５２】
（実施例２：タンパク質系架橋剤を用いた接着試験）
次に、前記タンパク質系架橋剤を用いた接着試験を行なった。
【００５３】
ＡＡ−ＰＶＡワニスと、前記タンパク質系架橋剤の水溶液とをそれぞれ調製し、試験片（被着材）としてラワン材を用いて、圧縮せん断接着強さ試験法により初期接着力および最終接着力を測定した。最終接着力については、常態試験および耐水試験によりそれぞれ測定した。各接着試験は、実施例１と同様、ハネムーン型接着により行なった。ＡＡ−ＰＶＡワニスはＡＡ化度が４．４％、７．５％および１４．３％のＡＡ−ＰＶＡをそれぞれ３０重量％濃度に調製したものを、タンパク質系架橋剤水溶液については前記の通り調製したものをそれぞれ用いて試験を行なった。ＡＡ−ＰＶＡワニスおよび架橋剤水溶液の塗布量、ならびに接着条件は、実施例１と同様とした。
【００５４】
初期接着力および最終接着力（常態試験および耐水試験）については、実施例１と同様の条件により測定した。
【００５５】
（実施例２−１）
ＡＡ化度４．４％のＡＡ−ＰＶＡワニスを用い、前記の通り調製したニカワヒドラジン分解物水溶液を架橋剤として用いて初期接着試験および常態試験を行なった。架橋剤調製（ニカワのヒドラジン分解）時におけるニカワとヒドラジンとの混合比を変化させて試験を行ない、接着強度を比較した。図２９および下記表１１〜１６にその結果を示す。
【表１１】

【表１２】

【表１３】

【表１４】

【表１５】

【表１６】

【００５６】
図２９および表１１〜１６から分かる通り、特に、架橋剤調製時におけるヒドラジン添加量がニカワに対し５重量％の場合に、初期接着試験および常態試験ともに高い接着強度が得られた。この場合の接着強度は、ＡＡ−ＰＶＡのみ（架橋剤なし）の場合、およびヒドラジンを添加しないニカワ（ＮＨ−０）を架橋剤として用いた場合よりも大幅に上回っていた。
【００５７】
（実施例２−２）
ニカワに対するヒドラジン添加量が６０重量％の架橋剤について、ヒドラジン分解時の反応時間が３時間の他、１時間、および６時間のものについても初期接着試験を行なった。また、同じくヒドラジン添加量が６０重量％の架橋剤について、タンパク質の種類を、前記カゼインおよび粉末ニカワ（森川商店、中粘度、Ｆ０−１）に変えて初期接着試験を行なった。粉末ニカワ（森川商店）のヒドラジン分解は、前記ニカワ（新田ゼラチン）と同様に行なった。図３０と下記表１７および１８にこれらの結果を示す。
【表１７】

【表１８】

【００５８】
図３０上図および表１７から分かる通り、ヒドラジン分解の反応時間を長くすることにより、接着強度が若干向上した。また図３０下図および表１８から分かる通り、タンパク質はどの種類を用いてもおおむね良好な接着強度が得られたが、本実施例の新田ゼラチン製ニカワが最も良い結果が得られた。これはタンパク質の粘度の違いによるものであると思われる。
【００５９】
（実施例２−３）
さらに、同じくヒドラジン添加量６０重量％の架橋剤を用い、ＡＡ−ＰＶＡのＡＡ化度が４．４％の他、７．５％および１４．３％のものについて初期接着試験を行なった。また、ヒドラジン添加量６０重量％および５重量％の架橋剤をそれぞれ用い、初期接着試験および常態試験の他、耐水試験を行なった。図３１と下記表１９および２０にこれらの結果を示す。
【表１９】

【表２０】

【００６０】
図３１上図および表１９から分かる通り、どのＡＡ化度でも同様に良好な結果が得られたが、ＡＡ化度１４．３％のものを用いた場合が若干接着強度が優れていた。さらに、図３１下図および表２０から分かる通り、特にヒドラジン添加量５重量％の架橋剤を用いた場合に、常態試験および耐水試験の双方において高い接着強度が得られた。なお、本実施例の接着剤は、高い接着力を有するのみでなく、沸騰水中で煮沸することにより剥離可能であることも分かった。このことは、接着剤としての使い勝手の高さを示す。
【００６１】
（実施例３：その他の架橋剤を用いた接着試験）
さらに、前記その他の架橋剤を用いた接着試験を行なった。
【００６２】
ＡＡ−ＰＶＡ水性ワニスと、前記その他の架橋剤の水溶液とをそれぞれ調製し、試験片（被着材）としてレッドメランチ材を用いて、圧縮せん断接着強さ試験法により初期接着力、最終接着力および時間依存接着力を測定した。最終接着力については、常態試験、耐水試験、耐温水試験および煮沸繰り返し試験によりそれぞれ測定した。前記各接着試験は、前記と同様、ハネムーン型接着により行なった。ＡＡ−ＰＶＡワニスはＡＡ化度が３．１％、１０．３％、２２．６％、３４．７％および３８．０％のＡＡ−ＰＶＡをそれぞれ３０重量％濃度に調製したものを、架橋剤水溶液については前記各架橋剤を５重量％および１０重量％濃度に調製したものをそれぞれ用いて試験を行なった。ＡＡ−ＰＶＡワニスおよび架橋剤水溶液の塗布量は、それぞれ１００ｇ／ｍ^２および５０ｇ／ｍ^２とした。接着条件は、プレス圧０．４９ＭＰａ、圧締時間５分間とし、その他の条件はＪＩＳＫ６８５２により行なった。各試験の最終結果は、１０回の試験の平均値により決定した。
【００６３】
初期接着力は、上記架橋剤水溶液の塗布量およびプレス圧以外の条件については実施例１と同様にして測定した。
【００６４】
最終接着力（常態試験、耐水試験、耐温水試験および煮沸繰り返し試験）は、以下のようにして測定した。すなわち、まず、試験片を、実施例１と同様にして作製した。常態試験および耐水試験については、上記架橋剤水溶液の塗布量およびプレス圧以外の条件については実施例１と同様にして測定した。耐温水試験は、４８時間養生後の試験片を６０±３℃の水に３時間浸し、続いて室温の水に浸して冷却し、乾燥せずにそのまま試験する以外は常態試験と同様にして行なった。煮沸繰り返し試験は、４８時間養生後の試験片を沸騰水に４時間浸し、続いて６０±３℃の空気中で２０時間乾燥し、再び沸騰水に４時間浸し、そして室温の水に浸して冷却し、乾燥せずにそのまま試験する以外は常態試験と同様にして行なった。
【００６５】
時間依存接着力は、試験片の幅を２５ｍｍに代えて１０ｍｍとし、塗布面積を２５ｍｍ×２５ｍｍに代えて２５ｍｍ×１０ｍｍとし、養生時間を４８時間に代えて０．５時間、１時間、３時間、２４時間または４８時間とする以外は常態試験と同様の条件で測定した。
【００６６】
（実施例３−１）
種々のＡＡ化度のＡＡ−ＰＶＡワニスと、５重量％濃度ヘキサメチレンジアミン（ＨＭＤＡ）水溶液とを用いて初期接着力を測定した。図３２にその結果を示す。同図から分かる通り、ＨＭＤＡを架橋剤に用いた場合、初期接着においても比較的高い接着強度が得られ、特にＡＡ−ＰＶＡのＡＡ化度が１０．３％以上では２ＭＰａ前後の接着強度が得られた。この試験ではＡＡ化度が高いほど大きい接着強度が得られたが、その効果は直線的ではなく、ＡＡ化度１０．３％でも、３４．７％の場合とさほど変わらない接着強度が得られた。
【００６７】
（実施例３−２）
次に、５重量％濃度ＨＭＤＡ水溶液を用い、ＡＡ化度が３．１％および３４．７％のＡＡ−ＰＶＡワニスをそれぞれ用いて時間依存接着力を測定した。図３３にその結果を示す。同図から分かる通り、いずれのＡＡ化度においても、２４〜４８時間後には、１０〜１２ＭＰａ程度の大きい接着強度および７０〜９０％程度の非常に高い木破率が得られた。なお、接着後３０分（０．５時間）では、ＡＡ化度３４．７％の方が３．１％よりも接着強度が約２倍大きかった。しかし、接着後２４〜４８時間後には、ＡＡ化度３．１％の方が３４．７％よりも若干接着強度が大きく、木破率もＡＡ化度３４．７％よりわずかに低いだけであった。すなわち、ＡＡ化度は、この数値範囲では最終接着力にあまり影響しないと言える。
【００６８】
（実施例３−３）
ＡＡ化度３８．０％のＡＡ−ＰＶＡワニスを用い、各種架橋剤の１０重量％濃度水溶液をそれぞれ用いて最終接着力を測定した。図３４にその結果を示す。同図から分かる通り、常態試験においては、いずれの架橋剤を用いても約３〜９ＭＰａという大きい接着強度が得られた。特に、ＨＭＤＡを用いた場合は、常態試験で９ＭＰａ程度、耐水試験では６ＭＰａ以上、耐温水試験においても５ＭＰａ程度という非常に大きい接着強度が得られた。
【００６９】
（実施例３−４）
さらに、ＡＡ化度３．１％および３８．０％のＡＡ−ＰＶＡワニスをそれぞれ用い、５重量％および１０重量％濃度のＨＭＤＡ水溶液をそれぞれ用いて最終接着力を測定した。図３５にその結果を示す。同図から分かる通り、いずれのワニスおよび架橋剤水溶液の組み合わせにおいても、常態試験で７〜１０ＭＰａ程度、耐温水試験でも４〜６ＭＰａ程度という非常に大きい接着強度が得られた。中でも、ＡＡ化度３．１％ワニスと５重量％濃度ＨＭＤＡ水溶液との組み合わせが最も接着強度が大きかった。特に、この組み合わせは煮沸繰り返し試験においても約２ＭＰａという高い接着強度を示し、耐水性および耐熱性が非常に大きいことを表す。なお、ＡＡ化度が３８％の場合は煮沸繰り返し試験における接着強度が低いが、これは、沸騰水中で煮沸することにより剥離可能であることを示す。すなわち、本実施例の接着剤は、ＡＡ化度および架橋剤濃度を変化させることにより接着力を調節して使い勝手をコントロールすることもできる。
【００７０】
【発明の効果】
以上説明した通り、本発明の接着剤は、強固な接着力を有し、ポリビニルアルコールの置換度、架橋剤の種類および量等を適宜選択することにより、非常に大きい耐水性および耐熱性を持たせることも可能である。さらに、置換ポリビニルアルコールと架橋剤とが室温で短時間に反応して硬化することにより、加熱等の手間なしに容易に接着することもできる。本発明の接着剤は、ホルムアルデヒド等の有害物質を放出することがなく、さらに、生分解性を有することにより、土壌中等に残留して環境汚染の原因となることがない。したがって、木造住宅等への用途に最適であり、また、それに止まらず、木製品、紙管等の紙製品および布製品全般の製造に好適に使用することができる。
【図面の簡単な説明】
【図１】ＡＡ化度６．３％のＡＡ−ＰＶＡの^１ＨＮＭＲスペクトルを示す図である。
【図２】ＡＡ化度１２．７％のＡＡ−ＰＶＡの^１ＨＮＭＲスペクトルを示す図である。
【図３】ＡＡ化度２１．２％のＡＡ−ＰＶＡの^１ＨＮＭＲスペクトルを示す図である。
【図４】ＡＡ化度３５．９％のＡＡ−ＰＶＡの^１ＨＮＭＲスペクトルを示す図である。
【図５】ＡＡ化度４．４％のＡＡ−ＰＶＡの^１ＨＮＭＲスペクトルを示す図である。
【図６】ＡＡ化度７．５％のＡＡ−ＰＶＡの^１ＨＮＭＲスペクトルを示す図である。
【図７】ＡＡ化度１４．３％のＡＡ−ＰＶＡの^１ＨＮＭＲスペクトルを示す図である。
【図８】圧縮せん断試験片の一例を示す模式図である。
【図９】圧縮せん断試験片のその他の一例を示す模式図である。
【図１０】接着力試験の一例の結果を示すグラフである。
【図１１】接着力試験のその他の一例の結果を示すグラフである。
【図１２】接着力試験のさらにその他の一例の結果を示すグラフである。
【図１３】接着力試験のさらにその他の一例の結果を示すグラフである。
【図１４】接着力試験のさらにその他の一例の結果を示すグラフである。
【図１５】接着力試験のさらにその他の一例の結果を示すグラフである。
【図１６】接着力試験のさらにその他の一例の結果を示すグラフである。
【図１７】接着力試験のさらにその他の一例の結果を示すグラフである。
【図１８】接着力試験のさらにその他の一例の結果を示すグラフである。
【図１９】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２０】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２１】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２２】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２３】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２４】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２５】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２６】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２７】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２８】接着力試験のさらにその他の一例の結果を示すグラフである。
【図２９】接着力試験のさらにその他の一例の結果を示すグラフである。
【図３０】接着力試験のさらにその他の一例の結果を示すグラフである。
【図３１】接着力試験のさらにその他の一例の結果を示すグラフである。
【図３２】接着力試験のさらにその他の一例の結果を示すグラフである。
【図３３】接着力試験のさらにその他の一例の結果を示すグラフである。
【図３４】接着力試験のさらにその他の一例の結果を示すグラフである。
【図３５】接着力試験のさらにその他の一例の結果を示すグラフである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an adhesive.
[0002]
[Prior art]
Wood adhesives that are currently widely used include phenolic resins, urea resins, melamine resins, and the like. However, these adhesives may release formaldehyde, which is a substance that has been pointed out to be carcinogenic and to cause allergies such as chemical sensitivity.
[0003]
For example, when the above various adhesives are used for a wooden house, volatile organic compounds such as formaldehyde may be gradually released and released into the living environment. In particular, since recent houses tend to be highly airtight, the concentration of the volatile organic compound in the air increases, which may lead to deterioration of physical condition of residents. As a method for solving this problem, there are a method of minimizing the amount of the various adhesives used in a house, and a method of using an adsorbent that absorbs formaldehyde. However, none of these methods solve the problem fundamentally.
[0004]
On the other hand, polyvinyl alcohol (PVA) is a substance that can be used as an adhesive or as a protective colloid for aqueous emulsion adhesives. Since it is water-soluble, it can be used easily, and it has been widely used because it does not emit harmful substances such as formaldehyde.However, it has poor adhesive strength and water resistance and requires long presses. is there.
[0005]
As means for solving the above problem, an acetoacetyl group is introduced into a PVA molecule (for example, see Patent Document 1). Furthermore, it has been reported that the water resistance of an emulsion stabilized by PVA was improved by introducing an acetoacetyl group into PVA (for example, see Non-Patent Document 1). However, acetoacetylated polyvinyl alcohol cannot be said to have sufficient adhesive strength and water resistance as an adhesive used for wooden houses and the like.
[0006]
[Patent Document 1]
JP-A-57-059971
[Non-patent document 1]
Y. Kuroyanagi, K .; Sato and T.S. Ataka, J. et al. Adhes. Soc. Jpn. , 1999, 35, 233-238.
[0007]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide an adhesive which does not emit harmful substances such as formaldehyde and has a strong adhesive force.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the adhesive of the present invention is an adhesive containing the following main adhesive (A component) and a crosslinking agent (B component).
(Component A): a substituted polyvinyl alcohol having a structure in which a part of hydroxyl groups of polyvinyl alcohol is substituted with an acylacetoxy group represented by the following general formula (1). However, in the formula, R ¹ Is an alkyl group.
Embedded image

(Component B): an organic compound having two or more amino groups. Here, “amino group” refers to —NH ₂ Or an atomic group represented by -NH-, which may or may not be directly bonded to a carbon atom.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described.
[0010]
(adhesive)
The adhesive of the present invention has a strong adhesive force and does not emit harmful substances such as formaldehyde. Furthermore, by having biodegradability, it does not remain in soil or the like and cause environmental pollution. In addition, since the component A and the component B have a property of reacting and curing at room temperature in a short time, they can be easily bonded without trouble such as heating.
[0011]
In the adhesive of the present invention, before use, the A component and the B component are present independently without being mixed, and at the time of use, the A component is used on one of the bonding surfaces of the object to be bonded, and the B component is used on the other. Is applied, and the surface on which the component A has been applied and the surface on which the component B has been applied are brought into contact with each other to cause the two components to react with each other to generate an adhesive force. However, the use form of the adhesive of the present invention is not limited to this, and the adhesive can be used by other methods. For example, before use, the A component and the B component exist independently without being mixed, and the A component and the B component are mixed at the time of use, and the mixture is applied to one or both of the bonding surfaces of the bonding object. May be applied, and the bonding surfaces may be brought into contact with each other for bonding.
[0012]
In the adhesive of the present invention, the forms of the component A and the component B before use are not particularly limited, but are preferably in the form of, for example, an aqueous solution. That is, since the components A and B are water-soluble, there is no need to use an organic solvent, so there is no risk that harmful substances derived from the organic solvent will be released, and the usability as an adhesive is good. Further, the usage ratio of the component A and the component B in the adhesive of the present invention is not particularly limited, but is, for example, 10: 100 to 10: 0.1, preferably 10:10 to 10: 1 by mass ratio. More preferably, the ratio is 10: 4.
[0013]
The adhesive of the present invention can be used, for example, for producing a product to which at least one of wood, paper, and cloth is adhered, and is particularly preferably used for producing a wooden product. The specific product is not particularly limited, but the wooden product can be used for manufacturing, for example, a wooden house and an upholstery, and the paper product can be used for manufacturing, for example, a paper tube. Further, the above-mentioned products are not limited to the bonding between materials of the same kind, and different materials such as wood and paper, and paper and cloth may be bonded by the adhesive of the present invention.
[0014]
(Adhesive agent)
Next, the adhesive main agent (component A) will be described.
[0015]
The main adhesive in the adhesive of the present invention is a substituted polyvinyl alcohol having the above structure. In the above formula (1), R ¹ Is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and tert. At least one selected from the group consisting of -butyl groups, and particularly preferably a methyl group. The degree of substitution of the hydroxyl group with the acylacetoxy group is not particularly limited, but is preferably 40% or less from the viewpoint of water solubility. In this case, the lower limit of the substitution degree is not particularly limited, but it goes without saying that it is a value exceeding 0%.
[0016]
The substituted polyvinyl alcohol can be produced, for example, as shown in Scheme 1 below. That is, a polyvinyl alcohol represented by the formula (6) is reacted with a diketene represented by the formula (7), and a part of the hydroxyl group of the polyvinyl alcohol (6) is substituted with an acetoacetyl group, thereby obtaining the formula ( The substituted polyvinyl alcohol represented by 8) is obtained. Equations (6) and (8) each represent a part of the molecule. The conditions for carrying out this reaction are not particularly limited, but the reaction can be carried out using an aprotic polar solvent such as DMSO.
Embedded image

[0017]
(Crosslinking agent)
Next, the crosslinking agent (component B) will be described.
[0018]
As described above, the crosslinking agent in the adhesive of the present invention is an organic compound having two or more amino groups, and is preferably at least one of the substances described in (I) and (II) below.
(I) At least one of the compounds represented by the following general formulas (2) to (5).
Embedded image

However, in the above formula, R ² ~ R ⁷ Is an alkylene group.
(II) A compound obtained by hydrazinolysis of all or a part of a protein molecule. However, the “protein” here may be a peptide.
[0019]
In the above formulas (2) to (5), R ² ~ R ⁷ Is preferably a linear or branched alkylene group having 1 to 12 carbon atoms, more preferably a linear alkylene group having 1 to 6 carbon atoms.
[0020]
In the equations (2) to (5),
R ² Is a methylene group, a dimethylene group (ethylene group), a trimethylene group or a tetramethylene group,
R ³ Is a dimethylene group (ethylene group) or a hexamethylene group,
R ⁴ And R ⁵ Are dimethylene groups (ethylene groups),
R ⁶ And R ⁷ Is particularly preferably a dimethylene group (ethylene group).
[0021]
The protein is not particularly limited, but is preferably at least one of gelatin and casein. Gelatin may be purified gelatin, but unpurified gelatin called glue can be used.
[0022]
Upon the hydrazinolysis of the protein, it is considered that a reaction such as the following scheme 2 occurs. Note that R ⁸ , R ⁹ And R ¹⁰ Is a side chain of an amino acid residue in a protein, and may be the same or different. The conditions for the hydrazine decomposition are not particularly limited. For example, the reaction is carried out at 60 to 70 ° C. for 3 to 4 hours.
Embedded image

[0023]
In addition, the amount of hydrazine to be added during the hydrazine decomposition is not particularly limited, but it is preferable to use an appropriate amount because hydrazine remaining may inhibit the reaction between the adhesive agent and the crosslinking agent. The amount of the hydrazine added is, for example, 1 to 100% by weight, preferably 3 to 100% by weight, and more preferably 5 to 100% by weight based on the protein. Further, as the mechanism of the inhibition, for example, it is considered that hydrazine remaining in the crosslinking agent cleaves the substituent on the substituted polyvinyl alcohol as shown in the following scheme 3.
Embedded image

[0024]
The crosslinking agent used in the present invention is preferably at least one selected from the group consisting of the compounds represented by the formulas (3) and (4), because it is more excellent in adhesive strength.
[0025]
In the reaction between the adhesive main agent and the crosslinking agent of the present invention, for example, it is considered that a reaction as shown in the following scheme 4 has occurred. Note that R ¹¹ Represents a portion obtained by removing amino groups at both ends from a crosslinking agent molecule.
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[0026]
【Example】
Next, examples of the present invention will be described.
[0027]
[Synthesis]
As described below, acetoacetylated polyvinyl alcohol (hereinafter, sometimes referred to as “AA-PVA”) and various crosslinking agents were synthesized.
[0028]
(Synthesis of AA-PVA)
Using polyvinyl alcohol (Wako Pure Chemical Industries, Ltd., average degree of polymerization 400-600, saponification rate of 96 mol% or more) and diketene (Wako Pure Chemical Industries, Ltd.) as raw materials, and using dimethyl sulfoxide (DMSO) as a solvent AA-PVA was synthesized. Specifically, first, polyvinyl alcohol (PVA) and DMSO were put in a 1000 ml four-necked flask, heated to about 60 ° C. under a nitrogen atmosphere, and stirred with a mechanical stirrer until PVA was completely dissolved. Next, diketen was dropped into this solution using a dropping funnel over about 30 minutes, and reacted for 1 hour. Thereafter, the reaction was stopped, and a mixed solvent of ethanol and hexane was added to the reaction solution to precipitate AA-PVA. The precipitate was separated and dissolved in water. The aqueous solution was dialyzed using a dialysis membrane (Wako Pure Chemical Industries, Ltd., size 36), and lyophilized to obtain the desired product.
[0029]
By changing the molar ratio of PVA and diketene, AA-PVA with various degrees of acetoacetylation (AA degree) was synthesized. For example, when PVA, diketene and DMSO were synthesized in the amounts used in Table 1 below, AA-PVA having AA conversions of 6.3%, 12.7%, 21.2% and 35.9% respectively was used. was gotten. 1 to 4 show the respective ¹ The HNMR measurement figure is shown. In this embodiment, ¹ EX-270 (trade name of JEOL) was used as an instrument for HNMR measurement. In addition, DMSO-d was used as the measurement solvent. ₆ It was used.
[Table 1]

[0030]
The degree of AA conversion of AA-PVA is as follows: ¹ HNMR was measured to calculate the peak area, which was determined by the following equation. Where X is AA degree, W _AA Is the peak area of the methyl group proton derived from the acetoacetyl group (around 2.5 ppm), W _PVA Is the peak area of the methylene group proton derived from the PVA main chain (around 1.5 to 2.25 ppm).
X (%) = (W _AA /(1.5×W _PVA )) × 100
[0031]
Other than the above, AA-PVA having various degrees of AA was synthesized by the same method. FIGS. 5 to 7 show that the degree of AA conversion is 4.4%, 7.5% and 14.3%. ¹ The HNMR measurement diagram is shown.
[0032]
Furthermore, it was confirmed that each AA-PVA had been converted to AA by FT-IR measurement. As the degree of AA conversion increases, the peak derived from the carbonyl group in the acetoacetyl group (1710 cm ^-1 And 1730cm ^-1 ) Increases, and a peak derived from a hydroxy group (3400 cm ^-1 ) Had decreased. The FT-IR was prepared by measuring a thin film of AA-PVA, and the measurement was carried out using FT-IR 8200D (trade name, manufactured by Shimadzu Corporation).
[0033]
(Synthesis of hydrazide crosslinking agent)
Dimethyl malonate, dimethyl succinate and dimethyl glutarate (all from Tokyo Chemical Industry Co., Ltd.) were respectively reacted with hydrazine monohydrate (Nacalai Tesque, Inc.) to produce malonic dihydrazide (MDH) and succinic dihydrazide (SDH). ) And glutaric acid dihydrazide (GDH). Specifically, first, the above-mentioned carboxylic acid ester and hydrazine monohydrate were charged into 200 ml of ethanol at a molar ratio of about 1: 2.1, stirred, and reacted to obtain a hydrazide compound. Next, the hydrazide compound was purified by recrystallization from methanol. That is, first, the hydrazide compound and methanol were placed in an eggplant-shaped flask, and heated to about 67 ° C. on a water bath with a reflux condenser to dissolve the hydrazide compound. Next, the solution was filtered while it was still hot to remove insolubles to obtain a transparent filtrate, and the filtrate was cooled to precipitate crystals. The crystals were collected by suction filtration at room temperature and dried in vacuo to give the desired product. Table 2 below shows the amount of each reagent used in the present synthesis, and Table 3 below shows the yield and yield of each hydrazide compound.
[Table 2]

[Table 3]

[0034]
(Synthesis of protein-based crosslinking agent)
Hydrazinolysis of glue and casein was carried out to synthesize a cross-linking agent. The reagents include Nika (Nitta Gelatin, viscosity 65.6 mP, jelly strength 182 g), New Zealand Casein (Nissei Kyoeki, ALACID First, 30M), hydrazine monohydrate (Nacalai Tesque, Inc.), and hydroxylated Sodium (Kishida Chemical Co., Ltd., special grade) was used. Here, the reagents other than sodium hydroxide are for chemical or general use.
[0035]
Hydrazine decomposition of glue was performed as follows. That is, first, a Dimroth condenser tube and a thermometer were attached to a three-necked flask, glue and distilled water were added, and the mixture was left at room temperature for about 1 hour to dissolve glue to some extent. Next, this was stirred on a water bath while heating to 60 to 70 ° C. to dissolve the glue completely. Then, hydrazine monohydrate was added, and the mixture was stirred and reacted at 70 ° C. for 3 hours. A partially hydrazino-degraded crosslinker was obtained. After cooling, the aqueous solution after the reaction was used for the adhesion test as it was. In this synthesis, eight types were synthesized by changing the mixing ratio of glue and hydrazine in various ways. Table 4 below shows the amounts of reagents used.
[Table 4]

[0036]
The hydrazinolysis of casein was performed as follows. That is, first, a Dimroth condenser tube and a thermometer were attached to a three-necked flask, casein and distilled water were added, and the mixture was left at room temperature for about 1 hour to dissolve casein to some extent. Next, this was stirred while heating to 60 to 70 ° C on a water bath to completely dissolve casein. Then, a 10% aqueous sodium hydroxide solution (using distilled water) was added thereto to adjust the pH to 8. After further stirring to give a viscous paste, hydrazine monohydrate was added, and the mixture was stirred and reacted at 70 ° C. for 3 hours to obtain a cross-linking agent in which casein was partially hydrolyzed. After cooling, the aqueous solution after the reaction was used for the adhesion test as it was. In this synthesis, two types were synthesized by changing the mixing ratio of casein and hydrazine. Table 5 below shows the amounts of reagents used.
[Table 5]

[0037]
(Other crosslinking agents)
In addition, as crosslinking agents used in this example, 1,2-ethylenediamine, 1,6-hexamethylenediamine, diethylenetriamine, piperazine hexahydrate (above, Kishida Chemical Co., Ltd.), polyethyleneimine (30% aqueous solution, Mw 60000) ~ 80000, Nacalai Tesque, Inc.), and adipic dihydrazide (commercially available), respectively. These were used as purchased. Note that adipic dihydrazide is a hydrazide-based compound, but is treated as “other cross-linking agent” in this example for convenience.
[0038]
[Adhesion test]
An adhesion test was performed using each of the AA-PVA and various cross-linking agents. The cold press uses a YS-5 type test press (trade name) manufactured by Shinto Metal Industry Co., Ltd. The compression-shear test (tensile test) uses a TMC-500 type compression-tensile universal tester (product manufactured by Shinko Tsushin) First name).
[0039]
(Example 1: Adhesion test using hydrazide crosslinking agent)
First, an adhesion test using the hydrazide-based crosslinking agent was performed.
[0040]
An aqueous solution of AA-PVA (hereinafter sometimes referred to as “aqueous varnish” or “varnish”) and an aqueous solution of the hydrazide-based cross-linking agent are respectively prepared, and using a Lauan material as a test piece (adhering material). The initial adhesive strength and the final adhesive strength were measured by a compression shear adhesive strength test method. The final adhesive strength was measured by a normal state test and a water resistance test, respectively. Each of the adhesion tests was performed by so-called honeymoon-type adhesion in which the AA-PVA aqueous varnish and the aqueous solution of the cross-linking agent were applied and bonded to different adhesion surfaces. The AA-PVA varnish was prepared by adjusting AA-PVA having a degree of AA of 6.3%, 12.7%, 21.2% and 35.9% to a concentration of 30% by weight, respectively. The test was carried out using each of the cross-linking agents prepared at a concentration of 5% by weight, 10% by weight and 20% by weight, respectively. The coating amounts of the AA-PVA varnish and the aqueous solution of the crosslinking agent were 100 g / m, respectively. ² And 40 g / m ² And The bonding conditions were a press pressure of 0.69 MPa (7 kgf / cm ² ), The pressing time was 5 minutes, and the other conditions were in accordance with JIS 6852. The final result of each test was determined by the average of 10 tests.
[0041]
The initial adhesive strength was measured under the following conditions. That is, first, two Lauan materials having a width of 2.5 cm, a length of 3 cm, and a thickness of 1 cm were prepared as adherends. Next, 0.0625 g of the AA-PVA varnish was applied to one surface of one adherend, and 0.025 g of the aqueous crosslinking agent solution was applied to one surface of the other adherend. The application area was 2.5 cm × 2.5 cm, and 0.5 cm from one end in the length direction was left unapplied. Thereafter, each adherend was left open for 4.5 minutes, the coated surfaces were stuck together and left for an additional 30 seconds, and cold pressed for 5 minutes. FIG. 8 schematically shows a perspective view of a state where the adherends are bonded. After the cold pressing, the initial adhesive strength was measured at a compression shear rate (crosshead speed) of 2 mm / min.
[0042]
The final adhesive strength (normal state test and water resistance test) was measured under the following conditions. That is, first, cold was performed in the same manner as in the initial adhesion test except that the width of the Lauan material was 12 cm and the application amounts of the AA-PVA varnish and the aqueous solution of the crosslinking agent were 0.3 g and 0.12 g, respectively. Pressed. FIG. 9 schematically shows a perspective view of a state where the adherends are bonded. After cold pressing, the adhered adhered materials were cured for 48 hours and cut into 2.5 cm widths to prepare test pieces, which were then tested. The operation up to this point and the shape of the test piece are the same in the normal state test and the water resistance test. The normal state test was carried out using a test piece prepared by curing and cutting for 48 hours as it was. In the water resistance test, the test piece was immersed in water at 30 ± 1 ° C. for 3 hours, then immersed in water at 20 ± 1 ° C. for 10 minutes, and immediately tested without drying. The compression shear rate was 2 mm / min for both the normal test and the water resistance test.
[0043]
(Example 1-1)
An initial adhesion test, a normal state test and a water resistance test were performed on 5% by weight, 10% by weight and 20% by weight aqueous solutions of malonic acid dihydrazide (MDH) with respect to an AA-PVA varnish having an AA degree of 21.2%. The adhesive strength was measured. In the normal state test and the water resistance test, the wood fracture rate was also measured. 10 to 12 graphically show the results of the initial adhesion test, normal state test and water resistance test, respectively, and FIG. 13 and Table 6 below collectively show the test results.
[Table 6]

[0044]
As can be seen from FIGS. 10 to 13 and Table 6, good adhesion strength test results were obtained using any concentration of MDH aqueous solution. It was excellent.
[0045]
(Example 1-2)
Next, initial adhesion to an AA-PVA varnish having a degree of AA conversion of 21.2% using an aqueous solution of malonic acid dihydrazide (MDH), succinic acid dihydrazide (SDH) and glutaric acid dihydrazide (GDH) at a concentration of 10% by weight, respectively. A test was performed to measure the adhesive strength. Furthermore, an initial adhesion test was performed in the same manner except that no cross-linking agent (primer, hereinafter, sometimes referred to as P) was used, and a comparison was made with the case where a cross-linking agent was used. FIG. 14 and Table 7 below show the results.
[Table 7]

[0046]
As can be seen from FIG. 14 and Table 7, when each of MDH, SDH and GDH was used as a cross-linking agent, the adhesive strength was dramatically improved as compared with the case where no cross-linking agent was used.
[0047]
(Example 1-3)
Furthermore, for AA-PVA varnishes with AA conversions of 6.3%, 12.7%, 21.2% and 35.9%, respectively, malonic dihydrazide (MDH) and succinic dihydrazide (MDH) at a concentration of 10% by weight. SDH) and a glutaric acid dihydrazide (GDH) aqueous solution, respectively, to perform a normal state test and a water resistance test. Furthermore, a normal state test and a water resistance test were performed in the same manner except that no cross-linking agent was used, and a comparison was made with the case where a cross-linking agent was used. FIGS. 15 to 19 and Table 8 below show the results of comparing the respective data according to the type of the crosslinking agent.
[Table 8]

[0048]
As can be seen from FIGS. 15 to 19 and Table 8, when a crosslinking agent was used, an extremely good adhesion test result was obtained as compared with the case where no crosslinking agent was used. And the rate of wood breakage was greatly improved. In the case of no cross-linking agent, relatively good results were obtained with the AA degree of 35.9% in the adhesive strength in the normal state test, but the wood breakage rate was low, and the adhesive strength and The wood breakage rate was low and it did not endure practical use.
[0049]
FIGS. 20 to 28 and Tables 9 and 10 below show the results of comparing the same data as described above by the degree of AA conversion. 20 to 26 and Table 9 separately summarize and compare the data of the normal test and the water resistance test. FIGS. 27 and 28 and Table 10 show the same graph and data of the normal test and the water resistance test. These are summarized in the table.
[Table 9]

[Table 10]

[0050]
As can be seen from FIGS. 20 to 28 and Tables 9 and 10, when the crosslinking agent was used, good adhesion test results were obtained with any of the crosslinking agents at any AA degree. In particular, when the degree of AA conversion was 6.3%, very good results were obtained in both the normal test and the water resistance test, and in both the adhesive strength and the wood fracture rate, regardless of the use of any crosslinking agent.
[0051]
Further, as can be seen from FIGS. 27 and 28, when the crosslinking agent was used, particularly when the degree of AA conversion was 6.3%, even in the water resistance test, the adhesive strength and the wood fracture rate which were not much different from those in the normal state test were obtained. This indicates that the adhesive in this example has high water resistance and is excellent as an adhesive for wood pieces.
[0052]
(Example 2: Adhesion test using protein-based crosslinking agent)
Next, an adhesion test using the protein-based crosslinking agent was performed.
[0053]
An AA-PVA varnish and an aqueous solution of the protein-based cross-linking agent were prepared, and the initial adhesive strength and the final adhesive strength were measured by a compressive shear adhesive strength test method using a Lauan material as a test piece (adhering material). did. The final adhesive strength was measured by a normal test and a water resistance test, respectively. Each adhesion test was performed by honeymoon-type adhesion as in Example 1. The AA-PVA varnish was prepared by preparing AA-PVA having AA conversion of 4.4%, 7.5% and 14.3% to a concentration of 30% by weight, respectively, and the protein-based crosslinking agent aqueous solution was prepared as described above. A test was performed using each of the test pieces. The application amounts of the AA-PVA varnish and the aqueous solution of the crosslinking agent, and the bonding conditions were the same as in Example 1.
[0054]
The initial adhesive strength and the final adhesive strength (normal state test and water resistance test) were measured under the same conditions as in Example 1.
[0055]
(Example 2-1)
Using an AA-PVA varnish having a degree of AA conversion of 4.4%, an initial adhesion test and a normal state test were carried out using the aqueous solution of a decomposition product of glucan hydrazine prepared as described above as a crosslinking agent. A test was performed by changing the mixing ratio of glue and hydrazine during the preparation of the crosslinking agent (hydrazine decomposition of glue), and the adhesive strength was compared. FIG. 29 and Tables 11 to 16 below show the results.
[Table 11]

[Table 12]

[Table 13]

[Table 14]

[Table 15]

[Table 16]

[0056]
As can be seen from FIG. 29 and Tables 11 to 16, particularly when the amount of hydrazine added during the preparation of the crosslinking agent was 5% by weight relative to glue, high adhesive strength was obtained in both the initial adhesion test and the normal state test. The adhesive strength in this case was significantly higher than in the case of using only AA-PVA (without a crosslinking agent) and in the case of using glue (NH-0) to which hydrazine was not added as a crosslinking agent.
[0057]
(Example 2-2)
The initial adhesion test was carried out for a crosslinking agent having a hydrazine addition amount of 60% by weight with respect to glue, with a reaction time of hydrazine decomposition of 3 hours, as well as 1 hour and 6 hours. Similarly, with respect to the crosslinking agent having the hydrazine addition amount of 60% by weight, an initial adhesion test was performed by changing the type of protein to the above-mentioned casein and powdered glue (Morikawa Shoten, medium viscosity, F0-1). Hydrazine decomposition of powdered glue (Morikawa Shoten) was performed in the same manner as for glue (Nitta Gelatin). FIG. 30 and Tables 17 and 18 below show these results.
[Table 17]

[Table 18]

[0058]
As can be seen from the upper diagram of FIG. 30 and Table 17, by increasing the reaction time for hydrazine decomposition, the adhesive strength was slightly improved. In addition, as can be seen from the lower diagram of FIG. 30 and Table 18, no matter which kind of protein was used, generally good adhesive strength was obtained, but Nitta gelatin manufactured by Nitta Gelatin of this example gave the best results. This appears to be due to differences in protein viscosity.
[0059]
(Example 2-3)
Further, an initial adhesion test was carried out for the AA-PVA having a degree of AA conversion of 4.4%, 7.5% and 14.3% in addition to the crosslinker having a hydrazine addition amount of 60% by weight. In addition, a water resistance test was performed in addition to an initial adhesion test and a normal state test, using hydrazine addition amounts of 60% by weight and 5% by weight of a crosslinking agent, respectively. FIG. 31 and Tables 19 and 20 below show these results.
[Table 19]

[Table 20]

[0060]
As can be seen from the upper diagram of FIG. 31 and Table 19, similarly good results were obtained at any AA conversion degree, but when the one having an AA conversion degree of 14.3% was used, the adhesive strength was slightly superior. Furthermore, as can be seen from the lower diagram of FIG. 31 and Table 20, high adhesive strength was obtained in both the normal state test and the water resistance test, particularly when a crosslinking agent with an added amount of hydrazine of 5% by weight was used. In addition, it turned out that the adhesive of this example not only has high adhesive strength but also can be peeled off by boiling in boiling water. This indicates a high usability as an adhesive.
[0061]
(Example 3: Adhesion test using other crosslinking agents)
Further, an adhesion test using the other crosslinking agent was performed.
[0062]
An AA-PVA aqueous varnish and an aqueous solution of the above-mentioned other cross-linking agent were prepared, respectively, and the initial adhesive strength and the final adhesive strength were determined by a compression-shear adhesive strength test method using a red merunch material as a test piece (adhering material). Force and time dependent adhesion were measured. The final adhesive strength was measured by a normal state test, a water resistance test, a hot water resistance test, and a repeated boiling test. Each of the above-mentioned adhesion tests was performed by honeymoon-type adhesion in the same manner as described above. AA-PVA varnish was prepared by crosslinking AA-PVA having a degree of AA of 3.1%, 10.3%, 22.6%, 34.7% and 38.0% to a concentration of 30% by weight, respectively. With respect to the aqueous solution of the agent, a test was carried out using each of the above crosslinking agents prepared at a concentration of 5% by weight and 10% by weight, respectively. The coating amounts of the AA-PVA varnish and the aqueous solution of the crosslinking agent were 100 g / m, respectively. ² And 50 g / m ² And The bonding conditions were a press pressure of 0.49 MPa and a pressing time of 5 minutes, and the other conditions were in accordance with JIS K 6852. The final result of each test was determined by the average of 10 tests.
[0063]
The initial adhesive strength was measured in the same manner as in Example 1 except for the application amount of the crosslinking agent aqueous solution and the conditions other than the pressing pressure.
[0064]
The final adhesive strength (normal state test, water resistance test, hot water resistance test and boiling test) was measured as follows. That is, first, a test piece was prepared in the same manner as in Example 1. In the normal state test and the water resistance test, conditions other than the application amount of the aqueous solution of the crosslinking agent and the pressing pressure were measured in the same manner as in Example 1. The hot water test is performed in the same manner as the normal test except that the test specimen after curing for 48 hours is immersed in water at 60 ± 3 ° C. for 3 hours, then immersed in water at room temperature, cooled, and tested without drying. Done. In the repeated boiling test, the test piece after aging for 48 hours was immersed in boiling water for 4 hours, subsequently dried in air at 60 ± 3 ° C. for 20 hours, immersed again in boiling water for 4 hours, and immersed in water at room temperature. The test was performed in the same manner as in the normal test except that the test was performed without cooling and drying.
[0065]
The time-dependent adhesive strength was 10 mm instead of 25 mm for the width of the test piece, the coating area was 25 mm × 10 mm instead of 25 mm × 25 mm, and the curing time was 0.5 hour, 1 hour, and 3 hours instead of 48 hours. , 24 hours or 48 hours, except that the measurement was carried out under the same conditions as in the normal test.
[0066]
(Example 3-1)
The initial adhesive strength was measured using AA-PVA varnishes of various AA degrees and a 5% by weight aqueous solution of hexamethylenediamine (HMDA). FIG. 32 shows the result. As can be seen from the figure, when HMDA is used as a cross-linking agent, a relatively high bonding strength is obtained even in the initial bonding, and especially when the AA degree of AA-PVA is 10.3% or more, a bonding strength of about 2 MPa is obtained. Was done. In this test, the higher the degree of AA conversion, the higher the adhesive strength was obtained, but the effect was not linear, and even with the AA degree of 10.3%, an adhesive strength that was not so different from that of 34.7% was obtained. Was.
[0067]
(Example 3-2)
Next, using a 5% by weight aqueous HMDA solution, time-dependent adhesive strength was measured using AA-PVA varnishes having AA conversion of 3.1% and 34.7%, respectively. FIG. 33 shows the result. As can be seen from the figure, a high adhesive strength of about 10 to 12 MPa and a very high wood fracture rate of about 70 to 90% were obtained after 24 to 48 hours at any AA degree. In addition, 30 minutes (0.5 hours) after the bonding, the bonding strength was about twice as large for the AA degree of 34.7% as for 3.1%. However, 24 to 48 hours after bonding, the AA degree of 3.1% has slightly higher adhesive strength than 34.7%, and the wood fracture rate is slightly lower than the AA degree of 34.7%. there were. That is, it can be said that the AA degree does not significantly affect the final adhesive strength in this numerical range.
[0068]
(Example 3-3)
Using an AA-PVA varnish having a degree of AA conversion of 38.0%, final adhesion was measured using 10% by weight aqueous solutions of various crosslinking agents. FIG. 34 shows the result. As can be seen from the figure, in the normal state test, a large adhesive strength of about 3 to 9 MPa was obtained using any of the crosslinking agents. In particular, when HMDA was used, a very large adhesive strength of about 9 MPa in a normal state test, 6 MPa or more in a water resistance test, and about 5 MPa in a hot water resistance test was obtained.
[0069]
(Example 3-4)
Further, the final adhesive strength was measured using AA-PVA varnishes having AA conversion degrees of 3.1% and 38.0%, respectively, and using HMDA aqueous solutions having a concentration of 5% by weight and 10% by weight, respectively. FIG. 35 shows the result. As can be seen from the figure, in all combinations of the varnish and the aqueous solution of the crosslinking agent, a very large adhesive strength of about 7 to 10 MPa was obtained in the normal test and about 4 to 6 MPa in the hot water resistance test. Above all, the combination of a varnish having a degree of AA of 3.1% and an aqueous solution of HMDA having a concentration of 5% by weight had the highest adhesive strength. In particular, this combination shows a high adhesive strength of about 2 MPa even in the repeated boiling test, indicating that the water resistance and heat resistance are extremely large. When the degree of AA conversion is 38%, the adhesive strength in the repeated boiling test is low, which means that it can be peeled off by boiling in boiling water. That is, the adhesive of the present embodiment can control the usability by changing the degree of AA conversion and the concentration of the crosslinking agent to adjust the adhesive force.
[0070]
【The invention's effect】
As described above, the adhesive of the present invention has a strong adhesive force, and has extremely large water resistance and heat resistance by appropriately selecting the degree of substitution of polyvinyl alcohol, the type and amount of the crosslinking agent, and the like. It is also possible. Further, the substituted polyvinyl alcohol and the cross-linking agent react and cure at room temperature in a short time, so that they can be easily bonded without trouble such as heating. The adhesive of the present invention does not emit harmful substances such as formaldehyde, and has biodegradability, so that it does not remain in soil or the like and cause environmental pollution. Therefore, it is most suitable for use in wooden houses and the like, and is not limited thereto, and can be suitably used in the manufacture of paper products such as wood products and paper tubes and fabric products in general.
[Brief description of the drawings]
FIG. 1 shows the relationship between AA-PVA having an AA conversion of 6.3%. ¹ It is a figure which shows an HNMR spectrum.
FIG. 2: AA-PVA having a degree of AA conversion of 12.7% ¹ It is a figure which shows an HNMR spectrum.
FIG. 3 shows that AA-PVA having a degree of AA conversion of 21.2% ¹ It is a figure which shows an HNMR spectrum.
FIG. 4 shows the results of AA-PVA having a degree of AA conversion of 35.9%. ¹ It is a figure which shows an HNMR spectrum.
FIG. 5: AA-PVA having a degree of AA conversion of 4.4% ¹ It is a figure which shows an HNMR spectrum.
FIG. 6 shows the results of AA-PVA having an AA conversion degree of 7.5%. ¹ It is a figure which shows an HNMR spectrum.
FIG. 7: AA-PVA having a degree of AA conversion of 14.3% ¹ It is a figure which shows an HNMR spectrum.
FIG. 8 is a schematic diagram showing an example of a compression shear test piece.
FIG. 9 is a schematic diagram showing another example of a compression shear test piece.
FIG. 10 is a graph showing the results of an example of an adhesion test.
FIG. 11 is a graph showing the results of another example of the adhesion test.
FIG. 12 is a graph showing the results of still another example of the adhesion test.
FIG. 13 is a graph showing the results of still another example of the adhesion test.
FIG. 14 is a graph showing the results of still another example of the adhesion test.
FIG. 15 is a graph showing the results of still another example of the adhesion test.
FIG. 16 is a graph showing the results of still another example of the adhesion test.
FIG. 17 is a graph showing the results of still another example of the adhesion test.
FIG. 18 is a graph showing the results of still another example of the adhesion test.
FIG. 19 is a graph showing the results of still another example of the adhesion test.
FIG. 20 is a graph showing the results of still another example of the adhesion test.
FIG. 21 is a graph showing the results of still another example of the adhesion test.
FIG. 22 is a graph showing the results of still another example of the adhesion test.
FIG. 23 is a graph showing the results of still another example of the adhesion test.
FIG. 24 is a graph showing the results of still another example of the adhesion test.
FIG. 25 is a graph showing the results of still another example of the adhesion test.
FIG. 26 is a graph showing the results of still another example of the adhesion test.
FIG. 27 is a graph showing the results of still another example of the adhesion test.
FIG. 28 is a graph showing the results of still another example of the adhesion test.
FIG. 29 is a graph showing the results of still another example of the adhesion test.
FIG. 30 is a graph showing the results of still another example of the adhesion test.
FIG. 31 is a graph showing the results of still another example of the adhesion test.
FIG. 32 is a graph showing the results of still another example of the adhesion test.
FIG. 33 is a graph showing the results of still another example of the adhesion test.
FIG. 34 is a graph showing the results of still another example of the adhesion test.
FIG. 35 is a graph showing the results of still another example of the adhesion test.

Claims (15)

An adhesive containing the following adhesive agent (component A) and a crosslinking agent (component B).
(Component A): a substituted polyvinyl alcohol having a structure in which a part of hydroxyl groups of polyvinyl alcohol is substituted with an acylacetoxy group represented by the following general formula (1). However, in the formula, R ¹ is an alkyl group.

(Component B): an organic compound having two or more amino groups. The adhesive according to claim 1, wherein the degree of substitution of the hydroxyl group in the component A by an acylacetoxy group is 40% or less. The adhesive according to claim 1, wherein in the formula (1), R ¹ is a linear or branched alkyl group having 1 to 6 carbon atoms. In the formula (1), R ¹ is at least selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group and a tert-butyl group. The adhesive according to claim 1, wherein the adhesive is one. The adhesive according to claim ¹ , wherein in the formula (1), R ¹ is a methyl group. The adhesive according to any one of claims 1 to 5, wherein the B component is at least one of the following substances (I) and (II).
(I) At least one of the compounds represented by the following general formulas (2) to (5).

However, in the above formula, R ^{2 to} R ⁷ are each an alkylene group.
(II) A compound obtained by hydrazinolysis of all or a part of a protein molecule. Adhesive according to the equation (2) to ^(5), according to claim 6 R 2 to R ⁷ are each straight-chain or branched alkylene group having 1 to 12 carbon atoms. Formula (2) to ^(5), adhesive of claim 6 R 2 to R ⁷ are each a straight-chain alkylene group having 1 to 6 carbon atoms. In the formulas (2) to (5),
R ² is a methylene group, a dimethylene group (ethylene group), a trimethylene group or a tetramethylene group;
R ³ is a dimethylene group (ethylene group) or a hexamethylene group;
R ⁴ and R ⁵ are each a dimethylene group (ethylene group);
R ⁶ and R ⁷ are each a dimethylene group (ethylene group);
The adhesive according to claim 6. The adhesive according to any one of claims 6 to 9, wherein the protein is at least one of gelatin and casein. The adhesive according to any one of claims 6 to 9, wherein the B component is at least one selected from the group consisting of compounds represented by the formulas (3) and (4). Before use, the A component and the B component are present independently without being mixed. At the time of use, the A component is applied to one of the bonding surfaces of the object to be bonded, and the B component is applied to the other. The adhesive according to any one of claims 1 to 11, wherein the surface to which the B component has been applied is brought into contact with the surface to which the B component has been applied so that the two components react to generate an adhesive force. Before use, the A component and the B component exist independently without being mixed, and the A component and the B component are mixed at the time of use, and the mixture is applied to one or both of the bonding surfaces of an object to be bonded. The adhesive according to any one of claims 1 to 11, wherein the adhesive surfaces are brought into contact with each other and adhered. The adhesive according to any one of claims 1 to 13, wherein the A component and the B component are in an aqueous solution state before use. The adhesive according to any one of claims 1 to 14, which is used for manufacturing a product to which at least one of wood, paper and cloth is adhered.

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