JP3990738B2

JP3990738B2 - Water dispersant and water dispersion

Info

Publication number: JP3990738B2
Application number: JP22112893A
Authority: JP
Inventors: 宏一斉藤; 徹八木
Original assignee: Nippon Paint Co Ltd; Nippon Paint Holdings Co Ltd
Current assignee: Nippon Paint Co Ltd; Nippon Paint Holdings Co Ltd
Priority date: 1993-09-06
Filing date: 1993-09-06
Publication date: 2007-10-17
Anticipated expiration: 2022-10-17
Also published as: JPH0768147A

Description

【０００１】
【産業上の利用分野】
本発明は、水分散剤及び水分散体、特に、アクリル系樹脂からなる水分散剤及びそれを用いた水分散体に関する。
【０００２】
【従来の技術】
一般的な塗料は、有機溶剤中に顔料やバインダーとしての樹脂を含んでいる。ところで、環境汚染防止の見地から、有機溶剤の使用が抑制されつつある。このため、塗料に関しても、水性塗料への転換が進行しつつある。水性塗料としては、樹脂や顔料等の疎水性材料を水分散剤を用いて水中に分散させたエマルジョンタイプのものが知られている。このようなエマルジョンタイプの水性塗料を実現するための水分散剤は、一般に、分子中に親水基と疎水基の双方を有するものである。たとえば、特開平１−２０３０３１号には、疎水性モノマーとカルボキシル基含有モノマーとスルホ基含有モノマーとの共重合体からなる乳化分散剤が示されている。また、特開平４−１９８２５７号には、ビニル部分に親水基を有するビニル変性アルキド樹脂からなる水分散剤が示されている。
【０００３】
【発明が解決しようとする課題】
特開平１−２０３０３１号に示された乳化分散剤は、疎水性材料との相溶性が不十分なため分散安定性が小さい。このため、この分散剤を用いたエマルジョン塗料は、層分離しやすい。また、特開平４−１９８２５７号に示された水分散剤は、ビニル変性しているためアルキド樹脂骨格部分の炭素−炭素不飽和結合数が少なく、これが塗膜形成時に塗膜の乾燥性を低下させる原因となってる。このため、得られた塗膜の耐水性が低い。
【０００４】
本発明の目的は、疎水性材料の水分散安定性を改善し、またエマルジョン塗料からなる塗膜の耐水性を高めることにある。
【０００５】
【課題を解決するための手段】
本発明の水分散剤は、酸性硫酸エステル基、酸性硫酸エステルの中和塩、酸性リン酸エステル基及び酸性リン酸エステルの中和塩からなる群から選ばれた親水基を含む親水性分岐鎖と、不飽和結合を有する炭素鎖を有する疎水性分岐鎖とを含むアクリル系樹脂からなる。
【０００６】
この水分散剤は、たとえば下記の一般式（６）で示される単量体２〜５０重量％と、下記の一般式（７）で示される単量体３０〜７０重量％と、下記の一般式（８）で示される単量体３０重量％以下と、前記一般式（６）、（７）及び（８）で示される単量体以外のアクリル樹脂形成性単量体５０重量％以下とをラジカル重合することにより得られた、数平均分子量が２，０００〜２００，０００のアクリル系樹脂である。
【０００７】
【化１９】

【０００８】
【化２０】

【０００９】
【化２１】

【００１０】
さらに、本発明に係る水分散体は、分散媒としての水と、疎水性材料と、上述の水分散剤とを含んでいる。
＊＊＊＊＊＊＊
水分散剤
本発明の水分散剤は、親水性分岐鎖と疎水性分岐鎖とを含むアクリル系樹脂からなる。すなわち、この水分散剤は、アクリル系の主鎖に親水性分岐鎖と疎水性分岐鎖とが結合したアクリル系グラフトポリマーである。このグラフトポリマーの親水性分岐鎖に含まれる親水基は、下記の一般式（１１）、（１２）で示される酸性硫酸エステル基、酸性硫酸エステルの中和塩、酸性リン酸エステル基及び酸性リン酸エステルの中和塩からなる群から選ばれた少なくとも１種の親水基である。
【００１１】
【化２２】

【００１２】
また、疎水性分岐鎖に含まれる炭素鎖は、不飽和結合を有している。このような不飽和結合を有する炭素鎖は、たとえば乾性油または半乾性油に由来する脂肪酸残基、例えば、炭素数が１４〜１８でありかつ炭素−炭素間の不飽和結合数が１〜３の脂肪酸残基である。
このようなアクリル系樹脂は、親水性分岐鎖と疎水性分岐鎖との双方を含むため、水分散剤として機能する。この水分散剤は、疎水性分岐鎖が疎水性材料との良好な相溶性及びぬれ性を示し、疎水性材料を水中に分散させると層分離しにくい分散体を形成し得る。また、この疎水性分岐鎖は、不飽和結合を有する炭素鎖のために酸化重合可能である。したがって、本発明の水分散剤をたとえばエマルジョン塗料に用いると、その塗料からなる塗膜の乾燥時に当該炭素鎖が酸化重合して塗膜の硬化を促進するので、塗膜の耐水性を高めることができる。
水分散剤の製造方法
上述の水分散剤は、下記の一般式（６）、（７）、（８）で示される単量体と、これらの一般式で示される単量体以外のアクリル樹脂形成性単量体とをラジカル重合することにより合成される。
【００１３】
【化２３】

【００１４】
【化２４】

【００１５】
【化２５】

【００１６】
一般式（６）で示される単量体において、基Ｒ²¹は、たとえば次の一般式（９）で示される。
【００１７】
【化２６】

【００１８】
この一般式（９）において、基Ｒ³⁰の具体例は、たとえば次の通りである。
【００１９】
【化２７】

【００２０】
また、一般式（９）において、αの部分の繰り返し単位は、ランダム状、ブロック状または交互状のいずれに配列されていてもよい。
上述の一般式（６）で示される単量体の具体例としては、第一工業製薬株式会社製の“アクアロンＨＳ−２０”及び“アクアロンＨＳ−１０”、旭電化工業株式会社製の“アデカリアソープＳＥ−３０Ｎ”，“同ＳＥ−２０Ｎ”及び“同ＳＥ−１０Ｎ”、日本乳化剤株式会社製の“Ａｎｔｏｘ−ＭＳ−６０”及びユニケミカル株式会社製の“ホスマーＰＥ”が挙げられる。なお、これらの単量体の構造式は次の通りである。
アクアロンＨＳ−２０：
【００２１】
【化２８】

【００２２】
アクアロンＨＳ−１０：
【００２３】
【化２９】

【００２４】
アデカリアソープＳＥ−３０Ｎ：
【００２５】
【化３０】

【００２６】
アデカリアソープＳＥ−２０Ｎ：
【００２７】
【化３１】

【００２８】
アデカリアソープＳＥ−１０Ｎ：
【００２９】
【化３２】

【００３０】
Ａｎｔｏｘ−ＭＳ−６０：
【００３１】
【化３３】

【００３２】
ホスマーＰＥ：
【００３３】
【化３４】

【００３４】
なお、本発明では、上述の一般式（６）で示される単量体が２種以上併用されてもよい。
上述の一般式（７）で示される単量体において、基Ｒ²⁴は、たとえば下記の一般式（１０）で示される炭素鎖である。
【００３５】
【化３５】

【００３６】
このような一般式（７）で示される単量体は、たとえばグリシジルメタクリレート、アリルグリシジルエーテルまたはダイセル化学工業株式会社製の“サイクロマーＭ−１００”等のエポキシ基含有モノマーにオレイン酸、リノール酸、リノレイン酸あるいはこれらを主成分とする大豆油脂肪酸、脱水ヒマシ油脂肪酸、サフラワー油脂肪酸、アマニ油脂肪酸、トール油脂肪酸のような乾性油脂肪酸または半乾性油脂肪酸を付加させると得られる。なお、“サイクロマーＭ−１００”の化学構造は次の通りである。
【００３７】
【化３６】

【００３８】
なお、本発明では、一般式（７）で示される単量体が２種以上併用されてもよい。
上述の一般式（８）で示される単量体において、基Ｒ²⁷は、たとえば次の有機残基である。
【００３９】
【化３７】

【００４０】
なお、上記有機残基において、β部分の繰り返し単位はブロック状、ランダム状または交互状のいずれに配列されていてもよい。
このような一般式（８）で示される単量体としては、基Ｒ²⁷がカルボキシル基を有するものとしてアクリル酸、メタクリル酸、クロトン酸、マレイン酸が例示できる。一方、基Ｒ²⁷としてポリオキシエチレン鎖を含むものとしては、新中村化学株式会社製の“ＮＫエステルＭ−９０Ｇ（エチレンオキシド９モル）”及び“ＮＫエステルＭ−２３０Ｇ（同２３モル）”、日本油脂株式会社製の“ＰＭＥ−４０００（エチレンオキシド９８モル）”が例示できる。
【００４１】
前記一般式（６）、（７）及び（８）で示される単量体以外のアクリル樹脂形成性単量体としては、アクリル系樹脂を形成するために通常用いられるものであればあらゆる種類のものが利用できる。具体的には、メチルアクリレート，エチルアクリレート，プロピルアクリレート，ブチルアクリレート，ヘキシルアクリレート，２−エチルヘキシルアクリレート，ラウリルアクリレート，ステアリルアクリレート等のアクリル酸エステル類、メチルメタクリレート，エチルメタクリレート，プロピルメタクリレート，ブチルメタクリレート，ヘキシルメタクリレート，２−エチルヘキシルメタクリレート，ラウリルメタクリレート，ステアリルメタクリレート等のメタクリル酸エステル類、酢酸ビニルやプロピオン酸ビニル等のカルボン酸のビニルエステル類、スチレン，α−メチルスチレン，ビニルナフタレン，ブタジエン，イソプレン等の不飽和炭化水素類、無水マレイン酸，無水イタコン酸等の酸無水物類、２−アクリルアミド−２−メチルプロパンスルホン酸，スルホエチルメタクリレート，スチレンスルホン酸等のスルホン酸類及びそれらの塩、アクリロニトリル，メタクリロニトリル等のニトリル類、アクリルアミド，メタクリルアミド，Ｎ−メチロールアクリルアミド，Ｎ，Ｎ−ジメチルアクリルアミド，ジアセトンアクリルアミド等のアミド類、ヒドロキシエチルアクリレート，ヒドロキシエチルメタクリレート，ヒドロキシプロピルメタクリレート，ヒドロキシブチルアクリレート等のアルコール類が例示できる。これらの単量体は、２種以上併用されてもよい。
【００４２】
本発明の水分散剤は、一般式（６）で示される単量体を２〜５０重量％、一般式（７）で示される単量体を３０〜７０重量％、一般式（８）で示される単量体を３０重量％以下、前記一般式で示される単量体以外のアクリル系樹脂形成性単量体を５０重量％以下混合してラジカル重合すると得られる。
ここで、一般式（６）で示される単量体の混合割合が２重量％未満の場合は、分散剤の分子中に含まれる親水基が少なくなり、分散剤としての機能が期待できない。逆に、割合が５０重量％を超えると、分散剤の親水性が大きくなり過ぎ、塗膜形成時に塗膜の耐水性が低下する。また、一般式（７）で示される単量体の混合割合が３０重量％未満の場合は、塗膜形成後に水分散剤が酸化重合しにくくなるので、塗膜の耐水性を高めるのが困難になる。逆に、７０重量％を超えると、水分散剤の分子中に含まれる疎水基の割合が大きくなり、水分散剤として機能にくくなる。一般式（８）で示される単量体の混合割合が３０重量％を超えると、分散剤の親水性が大きくなり過ぎ、塗膜形成時に塗膜の耐水性が低下する。さらに、上述の一般式（６）、（７）及び（８）で示される単量体以外のアクリル樹脂形成性単量体の混合割合が５０重量％を超えると、親水性及び疎水性の分岐鎖が減少し、分散剤としての機能が低くなる。
【００４３】
ラジカル重合時には、通常の溶液重合法が採用され得る。具体的には、アルコール類、グリコールエーテル類、グリコールエステル類等の親水性の有機溶媒中に上述の単量体を加え、さらにアゾビスイソブチロニトリルやアゾビスイソ酪酸ジメチル等のアゾ系の重合開始剤を加えて５０〜１５０℃で１〜１０時間加熱すると、本発明の水分散剤が得られる。
【００４４】
このようなラジカル重合法を経由して得られる本発明の水分散剤は、下記の一般式（１）、（２）及び（３）で示される繰り返し単位、及び上述のその他のアクリル樹脂形成性単量体由来の繰り返し単位を単量体の混合量に対応して含むアクリル系樹脂である。
【００４５】
【化３８】

【００４６】
【化３９】

【００４７】
【化４０】

【００４８】
なお、一般式（１）、（２）及び（３）に含まれる基Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、Ｒ⁸及びＲ⁹は、それぞれ上述の一般式（６）、（７）及び（８）でそれぞれ示される単量体に含まれる基Ｒ¹⁹、Ｒ²⁰、Ｒ²¹、Ｒ²²、Ｒ²³、Ｒ²⁴、Ｒ²⁵、Ｒ²⁶及びＲ²⁷と同じである。
上述のアクリル系樹脂の数平均分子量は、２，０００〜２００，０００が好ましい。分子量が２，０００未満の場合は、一般式（１）で示される繰り返し単位が含まれないものの割合が増すので好ましくない。逆に、分子量が２００，０００を超えると、粘度が高くなり過ぎて水分散剤としての機能が損なわれる。
水分散体
本発明の水分散体は、アルキド樹脂、エポキシエステル樹脂、油変性ポリウレタン樹脂等の事実上水に不溶の樹脂やカーボンブラック、クロムイエロー、フタロシアニンブルー等の顔料等の疎水性材料を上述の水分散剤を用いて水中に安定に分散させたものである。
【００４９】
このような水分散体を得る場合は、まず上述の水分散剤と、その０．１〜１０重量倍の疎水性材料とを充分に混合する。なお、水分散剤は、予めアンモニア、アルカノールアミン類等の親水性アミンを用いて中和しておいてもよい。次に、水分散剤と疎水性材料との混合物に必要に応じて親水性有機溶剤を追加し、室温〜沸点以下の温度で攪拌しながら１０分〜１０時間にわたって水を添加する。これにより、水分散体が得られる。なお、水の添加量は、水分散体の固形分が２０〜７０重量％となるよう調整するのが好ましい。
【００５０】
得られた水分散体は、そのまま水性塗料として用いることができる。この場合、水分散体中に含まれる水分散剤は、疎水性材料、即ち疎水性樹脂とともに塗膜を形成する。塗膜に含まれた水分散剤は、上述の一般式（２）で示される繰り返し単位に含まれる基Ｒ⁶が酸化重合し、塗膜の耐水性を高める。ここで、疎水性樹脂がアルキド樹脂等の酸化重合性の水不溶性樹脂の場合、塗膜形成時に水分散剤と水不溶性樹脂とが架橋して一体化し、塗膜の耐水性がより向上する。
【００５１】
なお、上述の水分散体にナフテン酸コバルト、ナフテン酸鉛、ナフテン酸ジルコニウム、ナフテン酸カルシウム等のドライヤー成分を１種または２種以上添加すると、基Ｒ⁶の酸化重合が促進されるので、塗膜の初期耐水性が高まる。
【００５２】
【実施例】
製造例１（アルキド樹脂の合成）
攪拌機、還流冷却器、水分離器、温度制御装置及び窒素導入管を備えたフラスコに大豆油脂肪酸６３１．６部、ペンタエリスリトール１７７．９部、無水フタル酸１６８．９部、テトラヒドロ無水フタル酸１２．７部、無水トリメリット酸８．９部及び還流用キシレン５０部を仕込んだ。これを窒素気流下で２２０℃に昇温し、２２０℃を維持しながら樹脂酸価が５．０になるまで反応させて酸化重合性アルキド樹脂ワニスを得た。得られたアルキド樹脂ワニスは、不揮発分が９６重量％で数平均分子量が５，０００であった。
製造例２（エポキシエステル樹脂の合成）
製造例１で使用したものと同一の装置に“エポトートＹＤ−０１４Ｕ”（東都化成株式会社製エポキシ樹脂：エポキシ当量９００〜１，０００）４３７．５部、大豆油脂肪酸５６２．５部及び還流用キシレン３０部を仕込んだ。これを窒素気流下において２３０℃に昇温し、２３０℃を維持しながら樹脂酸価が４．０になるまで反応させて酸化重合性エポキシエステル樹脂ワニスを得た。得られたエポキシエステル樹脂ワニスは、不揮発分が９６重量％であり、数平均分子量が６，０００であった。
製造例３（脂肪酸変性アクリルモノマーの合成）
攪拌機、還流冷却器、温度制御装置及び空気導入管を備えたフラスコに大豆油脂肪酸２９６部、グリシジルメタクリルレート１４２部、“ＰＦＧ”（日本乳化剤株式会社製のプロピレングリコールモノプロピルエーテル）４７．８部、テトラブチルアンモニウムクロライド０．１４部及びパラメトキシフェノール０．７部を仕込んだ。これに空気を吹き込みながら２００℃で２０分間反応させ、大豆油脂肪酸変性アクリルモノマーを得た。このアクリルモノマーの有効成分は９０重量％であった。
実施例１（水分散剤の合成）
攪拌機、還流冷却器、滴下漏斗、温度制御装置及び窒素導入管を備えたフラスコに上述の“ＰＦＧ”４８部を仕込み、これを窒素気流下で１００℃に加熱した。これに、製造例３で得られた脂肪酸変性モノマー６６．７部、上述の“Ａｎｔｏｘ−ＭＳ−６０”２２．２部、メタクリル酸７．７部、スチレン２０部、メタクリル酸メチル１２．３部及び“Ｖ−６０１”（和光純薬株式会社製の２，２′−アゾビスイソ酪酸ジメチル）２．５部の混合物を滴下漏斗から３時間かけて滴下した。１時間同温度で攪拌を継続した後、“Ｖ−６０１”のＰＦＧ１０％溶液５部をさらに加えて１時間保持し、反応を終了した。得られたワニスは、不揮発分６５重量％で数平均分子量が４，０００であった。
実施例２（水分散剤の製造）
実施例１で用いたものと同じ装置を使用し、フラスコに“ＰＦＧ”を５０部仕込んだ。また、滴下漏斗に製造例３で得られた脂肪酸変性モノマー６６．７部、上述の“ＨＳ−１０”５部、上述の“ＰＭＥ−４０００”１５部、スチレン２０部、メタクリル酸メチル２０部及び上述の“Ｖ−６０１”２．５部からなる混合物を仕込み、実施例１と同様に重合を行った。得られたワニスは、不揮発分６５重量％であり、数平均分子量が６，３００であった。
比較例１（水分散剤の合成）
フラスコに仕込む“ＰＦＧ”を５０部に、滴下漏斗に仕込む“Ａｎｔｏｘ−ＭＳ−６０”２２．２部を第一工業製薬株式会社製の“アクアロンＲＮ−２０”２０部に変更した点を除き実施例１と同様に重合を行い、ワニスを得た。得られたワニスは、揮発分が６５重量％であり、数平均分子量が４，１００であった。
【００５３】
なお、上述の“アクアロンＲＮ−２０”の構造式は次の通りである。
【００５４】
【化４１】

【００５５】
比較例２（水分散剤の合成）
フラスコに仕込む“ＰＦＧ”を５５部に、また滴下漏斗に仕込む混合物を“Ａｎｔｏｘ−ＭＳ−６０”２２．２部、メタクリル酸７．７部、スチレン３０部、メタクリル酸メチル２７．６部、アクリル酸２−エチルヘキシル３４．８部及び“Ｖ−６０１”２．５部からなる混合物に変更する点を除き実施例１と同様に重合を行いワニスを得た。得られたワニスは、不揮発分が６５重量％であり、数平均分子量が６，４００であった。
実施例３〜６、比較例３，４（水分散体の製造）
攪拌機、還流冷却器、滴下漏斗、温度制御装置、窒素導入管を備えたフラスコに、表１に示す各成分を表１に示す割合で加えて攪拌し均一化させた。次に、製造例１または製造例２で得られた疎水性樹脂を表１に示す割合で加え、窒素雰囲気下において５０℃でさらに３０分間攪拌混合した。さらに、フラスコ内を５０℃に保ちながら脱イオン水１１８．４部を滴下漏斗から５時間かけて滴下し、そのまま更に３０分間攪拌した。得られた水分散体について、貯蔵安定性、並びに塗料として用いた場合に形成された塗膜の耐水性及び鉛筆硬度を調べた。試験方法は次の通りである。結果を表１に示す。
〔貯蔵安定性〕
５０℃で２週間貯蔵した後の状態変化を調べた。評価の基準は次の通りである。
○：粘度変化±２０％未満で外観変化なし。
×：外観変化（ゲル化または層分離）あり。
〔耐水性〕
水分散体にドライヤーとして“Ｄｉｃｎａｔｅ３１１１”（大日本インキ化学工業株式会社製のエマルジョン型コバルト系ドライヤー：不揮発分３５重量％）を０．２重量％添加した。この水分散体をバーコーターを用いて磨き鋼板に乾燥塗膜の厚さが約３０μｍになるよう塗布した。これを室温で３日間乾燥した後に塗装板を水に浸漬し、室温で３日間さらに放置した後の状態を観察した。評価の基準は次の通りである。
○：外観変化なし。
△：やや白化。
×：白化。
〔鉛筆硬度〕
耐水性試験の場合と同様にして作成された塗装板の塗膜硬度をＪＩＳ−Ｋ５４００にしたがって引っかき試験により調べた。
【００５６】
【表１】

【００５７】
【発明の効果】
本発明の水分散剤は、上述の親水性分岐鎖と、不飽和結合を有する炭素鎖を含む疎水性分岐とを含むアクリル系樹脂からなるので、疎水性材料を安定に水分散でき、しかも乾燥時には高い耐水性を示す塗膜を形成することができる。
本発明の水分散体は、上述の水分散剤を含むため、疎水性材料が安定に水分散化されており、また、塗料として用いたときに耐水性の高い塗膜が形成できる。[0001]
[Industrial application fields]
The present invention relates to an aqueous dispersant and an aqueous dispersion, in particular, an aqueous dispersant composed of an acrylic resin and an aqueous dispersion using the same.
[0002]
[Prior art]
A common paint contains a pigment or a resin as a binder in an organic solvent. By the way, from the viewpoint of preventing environmental pollution, the use of organic solvents is being suppressed. For this reason, the conversion to water-based paints is also progressing regarding paints. As the water-based paint, an emulsion type is known in which a hydrophobic material such as a resin or pigment is dispersed in water using a water dispersant. In general, an aqueous dispersant for realizing such an emulsion-type water-based paint has both a hydrophilic group and a hydrophobic group in the molecule. For example, Japanese Patent Application Laid-Open No. 1-203031 discloses an emulsifying dispersant composed of a copolymer of a hydrophobic monomer, a carboxyl group-containing monomer, and a sulfo group-containing monomer. Japanese Patent Application Laid-Open No. 4-198257 discloses an aqueous dispersant made of a vinyl-modified alkyd resin having a hydrophilic group in the vinyl portion.
[0003]
[Problems to be solved by the invention]
The emulsifying dispersant disclosed in Japanese Patent Application Laid-Open No. 1-203031 has low dispersion stability because of insufficient compatibility with the hydrophobic material. For this reason, the emulsion paint using this dispersant is easily separated into layers. In addition, since the water dispersant disclosed in JP-A-4-198257 is vinyl-modified, the number of carbon-carbon unsaturated bonds in the alkyd resin skeleton portion is small, and this reduces the drying property of the coating film when the coating film is formed. It is the cause. For this reason, the water resistance of the obtained coating film is low.
[0004]
An object of the present invention is to improve the water dispersion stability of a hydrophobic material and to increase the water resistance of a coating film made of an emulsion paint.
[0005]
[Means for Solving the Problems]
The aqueous dispersant of the present invention comprises a hydrophilic branched chain containing a hydrophilic group selected from the group consisting of an acidic sulfate group, a neutralized salt of an acidic sulfate, an acidic phosphate group and a neutralized salt of an acidic phosphate. And an acrylic resin containing a hydrophobic branched chain having a carbon chain having an unsaturated bond.
[0006]
For example, the water dispersant includes 2 to 50% by weight of a monomer represented by the following general formula (6), 30 to 70% by weight of a monomer represented by the following general formula (7), and the following general formula: 30% by weight or less of the monomer represented by (8) and 50% by weight or less of the acrylic resin-forming monomer other than the monomers represented by the general formulas (6), (7) and (8). It is an acrylic resin having a number average molecular weight of 2,000 to 200,000 obtained by radical polymerization.
[0007]
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[0008]
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[0009]
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[0010]
Furthermore, the water dispersion according to the present invention includes water as a dispersion medium, a hydrophobic material, and the above-described water dispersant.
＊＊＊＊＊＊＊
Water dispersant The water dispersant of the present invention comprises an acrylic resin containing a hydrophilic branched chain and a hydrophobic branched chain. That is, this aqueous dispersant is an acrylic graft polymer in which a hydrophilic branched chain and a hydrophobic branched chain are bonded to an acrylic main chain. The hydrophilic groups contained in the hydrophilic branched chain of this graft polymer are acidic sulfate groups represented by the following general formulas (11) and (12), neutralized salts of acidic sulfates, acidic phosphate groups and acidic phosphorus groups. It is at least one hydrophilic group selected from the group consisting of neutralized salts of acid esters.
[0011]
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[0012]
Moreover, the carbon chain contained in the hydrophobic branched chain has an unsaturated bond. The carbon chain having such an unsaturated bond is, for example, a fatty acid residue derived from drying oil or semi-drying oil, such as 14 to 18 carbon atoms and 1 to 3 carbon-carbon unsaturated bonds. Of fatty acid residues.
Such an acrylic resin functions as an aqueous dispersant because it contains both hydrophilic and hydrophobic branched chains. In this water-dispersing agent, the hydrophobic branched chain exhibits good compatibility and wettability with the hydrophobic material, and when the hydrophobic material is dispersed in water, a dispersion in which layer separation is difficult to form can be formed. In addition, this hydrophobic branched chain can be oxidatively polymerized because of the carbon chain having an unsaturated bond. Therefore, when the aqueous dispersant of the present invention is used in, for example, an emulsion paint, the carbon chain oxidizes and polymerizes at the time of drying of the paint film made of the paint, thereby promoting the hardening of the paint film. it can.
Method for producing water dispersant The above-mentioned water dispersant includes monomers represented by the following general formulas (6), (7) and (8), and monomers other than those represented by these general formulas. It is synthesized by radical polymerization with an acrylic resin-forming monomer.
[0013]
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[0014]
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[0015]
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[0016]
In the monomer represented by the general formula (6), the group R ²¹ is represented by, for example, the following general formula (9).
[0017]
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[0018]
In the general formula (9), specific examples of the group R ³⁰ are, for example, as follows.
[0019]
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[0020]
Further, in the general formula (9), the repeating units of the α portion may be arranged in any of random, block, or alternating.
Specific examples of the monomer represented by the general formula (6) include “AQUALON HS-20” and “AQUALON HS-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “ADEKA” manufactured by Asahi Denka Kogyo Co., Ltd. Examples include rear soap SE-30N, SE-20N and SE-10N, “Antox-MS-60” manufactured by Nippon Emulsifier Co., Ltd. and “Phosmer PE” manufactured by Unichemical Co., Ltd. The structural formulas of these monomers are as follows.
Aqualon HS-20:
[0021]
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[0022]
Aqualon HS-10:
[0023]
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[0024]
ADEKA rear soap SE-30N:
[0025]
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[0026]
ADEKA rear soap SE-20N:
[0027]
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[0028]
ADEKA rear soap SE-10N:
[0029]
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[0030]
Antox-MS-60:
[0031]
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[0032]
Hosmer PE:
[0033]
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[0034]
In the present invention, two or more monomers represented by the above general formula (6) may be used in combination.
In the monomer represented by the general formula (7), the group R ²⁴ is a carbon chain represented by the following general formula (10), for example.
[0035]
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[0036]
The monomer represented by the general formula (7) includes, for example, oleic acid and linoleic acid in addition to an epoxy group-containing monomer such as glycidyl methacrylate, allyl glycidyl ether, or “Cyclomer M-100” manufactured by Daicel Chemical Industries, Ltd. It can be obtained by adding linolenic acid or a dry oil fatty acid such as soybean oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid, linseed oil fatty acid, tall oil fatty acid or the like as a main component thereof. The chemical structure of “Cyclomer M-100” is as follows.
[0037]
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[0038]
In the present invention, two or more monomers represented by the general formula (7) may be used in combination.
In the monomer represented by the above general formula (8), the group R ²⁷ is, for example, the following organic residue.
[0039]
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[0040]
In the organic residue, the repeating unit of the β portion may be arranged in any of a block shape, a random shape, or an alternating shape.
Examples of such a monomer represented by the general formula (8) include acrylic acid, methacrylic acid, crotonic acid, and maleic acid as the group R ²⁷ having a carboxyl group. On the other hand, those containing a polyoxyethylene chain as the group R ²⁷ include “NK ester M-90G (9 mol of ethylene oxide)” and “NK ester M-230G (23 mol)” manufactured by Shin-Nakamura Chemical Co., Ltd., Japan. Examples thereof include “PME-4000 (98 mol of ethylene oxide)” manufactured by Yushi Co., Ltd.
[0041]
As the acrylic resin-forming monomer other than the monomers represented by the general formulas (6), (7) and (8), all kinds of monomers can be used as long as they are usually used for forming an acrylic resin. Things are available. Specifically, acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl Methacrylic acid esters such as methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, vinyl esters of carboxylic acids such as vinyl acetate and vinyl propionate, styrene, α-methylstyrene, vinyl naphthalene, butadiene, isoprene, etc. Saturated hydrocarbons, acid anhydrides such as maleic anhydride and itaconic anhydride, 2-acrylamide-2 Sulfonic acids such as methylpropanesulfonic acid, sulfoethylmethacrylate, styrenesulfonic acid and their salts, nitriles such as acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, diacetone Examples include amides such as acrylamide and alcohols such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl acrylate. Two or more of these monomers may be used in combination.
[0042]
The water dispersant of the present invention is represented by 2 to 50% by weight of the monomer represented by the general formula (6), 30 to 70% by weight of the monomer represented by the general formula (7), and represented by the general formula (8). And 30% by weight or less of the monomer, and 50% by weight or less of the acrylic resin-forming monomer other than the monomer represented by the above general formula is mixed and obtained by radical polymerization.
Here, when the mixing ratio of the monomer represented by the general formula (6) is less than 2% by weight, the hydrophilic group contained in the molecule of the dispersant is reduced, and the function as the dispersant cannot be expected. On the other hand, when the ratio exceeds 50% by weight, the hydrophilicity of the dispersant becomes too large, and the water resistance of the coating film is lowered during the coating film formation. In addition, when the mixing ratio of the monomer represented by the general formula (7) is less than 30% by weight, it is difficult to increase the water resistance of the coating film because the aqueous dispersant is difficult to undergo oxidative polymerization after the coating film is formed. Become. On the other hand, if it exceeds 70% by weight, the proportion of the hydrophobic group contained in the molecule of the water dispersant increases, and it becomes difficult to function as a water dispersant. When the mixing ratio of the monomer represented by the general formula (8) exceeds 30% by weight, the hydrophilicity of the dispersant becomes too large, and the water resistance of the coating film is lowered during the formation of the coating film. Further, when the mixing ratio of the acrylic resin-forming monomer other than the monomers represented by the general formulas (6), (7) and (8) exceeds 50% by weight, hydrophilic and hydrophobic branching is performed. The chain is reduced and the function as a dispersant is lowered.
[0043]
At the time of radical polymerization, a normal solution polymerization method can be employed. Specifically, the above monomers are added to a hydrophilic organic solvent such as alcohols, glycol ethers, glycol esters, and azo-based polymerization such as azobisisobutyronitrile or dimethyl azobisisobutyrate is started. When the agent is added and heated at 50 to 150 ° C. for 1 to 10 hours, the aqueous dispersant of the present invention is obtained.
[0044]
The water dispersant of the present invention obtained through such radical polymerization method has repeating units represented by the following general formulas (1), (2) and (3), and the other acrylic resin-forming units described above. It is an acrylic resin containing a repeating unit derived from a monomer corresponding to the mixing amount of the monomer.
[0045]
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[0046]
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[0047]
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[0048]
The groups R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ^8, and R ⁹ included in the general formulas (1), (2), and (3) are the same as those described above. Groups R ¹⁹ , R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ and R ²⁷ contained in the monomers represented by the general formulas (6), (7) and (8), respectively. Is the same.
The number average molecular weight of the acrylic resin is preferably 2,000 to 200,000. When the molecular weight is less than 2,000, the ratio of those not containing the repeating unit represented by the general formula (1) increases, which is not preferable. On the other hand, when the molecular weight exceeds 200,000, the viscosity becomes too high and the function as a water dispersant is impaired.
Aqueous dispersion The aqueous dispersion of the present invention comprises a hydrophobic resin such as a substantially insoluble resin such as alkyd resin, epoxy ester resin, and oil-modified polyurethane resin, and pigments such as carbon black, chrome yellow, and phthalocyanine blue. The material is stably dispersed in water using the above-mentioned water dispersant.
[0049]
When obtaining such an aqueous dispersion, first, the above-mentioned aqueous dispersant and 0.1 to 10 times by weight of the hydrophobic material are sufficiently mixed. The water dispersant may be neutralized in advance using a hydrophilic amine such as ammonia or alkanolamines. Next, if necessary, a hydrophilic organic solvent is added to the mixture of the water dispersant and the hydrophobic material, and water is added over 10 minutes to 10 hours while stirring at a temperature of room temperature to boiling point. Thereby, an aqueous dispersion is obtained. The amount of water added is preferably adjusted so that the solid content of the aqueous dispersion is 20 to 70% by weight.
[0050]
The obtained water dispersion can be used as it is as a water-based paint. In this case, the water dispersant contained in the water dispersion forms a coating film together with the hydrophobic material, that is, the hydrophobic resin. In the aqueous dispersant contained in the coating film, the group R ⁶ contained in the repeating unit represented by the above general formula (2) undergoes oxidative polymerization to increase the water resistance of the coating film. Here, when the hydrophobic resin is an oxidatively polymerizable water-insoluble resin such as an alkyd resin, the water dispersant and the water-insoluble resin are cross-linked and integrated at the time of coating film formation, and the water resistance of the coating film is further improved.
[0051]
When one or more dryer components such as cobalt naphthenate, lead naphthenate, zirconium naphthenate and calcium naphthenate are added to the aqueous dispersion described above, the oxidative polymerization of the group R ⁶ is promoted. The initial water resistance of the membrane is increased.
[0052]
【Example】
Production Example 1 (Synthesis of alkyd resin)
A flask equipped with a stirrer, a reflux condenser, a water separator, a temperature controller, and a nitrogen introduction tube was charged with 631.6 parts of soybean oil fatty acid, 177.9 parts of pentaerythritol, 168.9 parts of phthalic anhydride, and 12 of tetrahydrophthalic anhydride. .7 parts, trimellitic anhydride 8.9 parts and refluxing xylene 50 parts were charged. This was heated to 220 ° C. under a nitrogen stream and reacted until the resin acid value reached 5.0 while maintaining 220 ° C. to obtain an oxidation polymerizable alkyd resin varnish. The obtained alkyd resin varnish had a nonvolatile content of 96% by weight and a number average molecular weight of 5,000.
Production Example 2 (Synthesis of epoxy ester resin)
In the same apparatus as used in Production Example 1, 437.5 parts of “Epototo YD-014U” (Epoxy resin manufactured by Toto Kasei Co., Ltd .: Epoxy equivalent 900-1,000), 562.5 parts of soybean oil fatty acid and for refluxing 30 parts of xylene were charged. This was heated to 230 ° C. under a nitrogen stream and reacted until the resin acid value was 4.0 while maintaining 230 ° C. to obtain an oxidatively polymerizable epoxy ester resin varnish. The obtained epoxy ester resin varnish had a nonvolatile content of 96% by weight and a number average molecular weight of 6,000.
Production Example 3 (Synthesis of fatty acid-modified acrylic monomer)
296 parts of soybean oil fatty acid, 142 parts of glycidyl methacrylate, “PFG” (propylene glycol monopropyl ether manufactured by Nippon Emulsifier Co., Ltd.) 47.8 parts in a flask equipped with a stirrer, reflux condenser, temperature controller and air introduction tube , 0.14 part of tetrabutylammonium chloride and 0.7 part of paramethoxyphenol were charged. This was reacted at 200 ° C. for 20 minutes while blowing air to obtain a soybean oil fatty acid-modified acrylic monomer. The active ingredient of this acrylic monomer was 90% by weight.
Example 1 (Synthesis of water dispersant)
A flask equipped with a stirrer, reflux condenser, dropping funnel, temperature controller and nitrogen inlet tube was charged with 48 parts of the above-mentioned “PFG” and heated to 100 ° C. under a nitrogen stream. To this, 66.7 parts of the fatty acid-modified monomer obtained in Production Example 3, 22.2 parts of the above-mentioned “Antox-MS-60”, 7.7 parts of methacrylic acid, 20 parts of styrene, 12.3 parts of methyl methacrylate A mixture of 2.5 parts of “V-601” (dimethyl 2,2′-azobisisobutyrate manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise from the dropping funnel over 3 hours. After stirring at the same temperature for 1 hour, 5 parts of a 10% PFG solution of “V-601” was further added and held for 1 hour to complete the reaction. The obtained varnish had a nonvolatile content of 65% by weight and a number average molecular weight of 4,000.
Example 2 (Production of water dispersant)
Using the same apparatus as used in Example 1, 50 parts of “PFG” was charged to the flask. Also, 66.7 parts of the fatty acid-modified monomer obtained in Production Example 3, 5 parts of “HS-10”, 15 parts of “PME-4000”, 20 parts of styrene, 20 parts of methyl methacrylate, and A mixture comprising 2.5 parts of the above-mentioned “V-601” was charged, and polymerization was carried out in the same manner as in Example 1. The obtained varnish had a nonvolatile content of 65% by weight and a number average molecular weight of 6,300.
Comparative Example 1 (Synthesis of water dispersant)
Implemented except that "PFG" charged to the flask was changed to 50 parts, and "2.2" part of "Antox-MS-60" charged to the dropping funnel was changed to 20 parts "AQUALON RN-20" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Polymerization was carried out in the same manner as in Example 1 to obtain a varnish. The obtained varnish had a volatile content of 65% by weight and a number average molecular weight of 4,100.
[0053]
The structural formula of “AQUALON RN-20” described above is as follows.
[0054]
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[0055]
Comparative Example 2 (Synthesis of water dispersant)
55 parts of “PFG” charged in the flask and 22.2 parts of “Antox-MS-60”, 7.7 parts of methacrylic acid, 30 parts of styrene, 27.6 parts of methyl methacrylate, acrylic A varnish was obtained by performing polymerization in the same manner as in Example 1 except that the mixture was changed to a mixture consisting of 34.8 parts of 2-ethylhexyl acid and 2.5 parts of “V-601”. The obtained varnish had a nonvolatile content of 65% by weight and a number average molecular weight of 6,400.
Examples 3 to 6, Comparative Examples 3 and 4 (Production of water dispersion)
Each component shown in Table 1 was added to a flask equipped with a stirrer, reflux condenser, dropping funnel, temperature control device, and nitrogen introduction tube at the ratio shown in Table 1, and the mixture was stirred and homogenized. Next, the hydrophobic resin obtained in Production Example 1 or Production Example 2 was added in the ratio shown in Table 1, and the mixture was further stirred and mixed at 50 ° C. for 30 minutes in a nitrogen atmosphere. Further, 118.4 parts of deionized water was dropped from the dropping funnel over 5 hours while keeping the inside of the flask at 50 ° C., and the mixture was further stirred for 30 minutes. About the obtained water dispersion, the storage stability and the water resistance and pencil hardness of the coating film formed when used as a paint were examined. The test method is as follows. The results are shown in Table 1.
[Storage stability]
The state change after 2 weeks storage at 50 ° C. was examined. The criteria for evaluation are as follows.
○: Change in viscosity is less than ± 20% and there is no change in appearance.
X: Appearance change (gelation or layer separation).
〔water resistant〕
0.2% by weight of “Dicnate 3111” (Emulsion type cobalt-based dryer manufactured by Dainippon Ink & Chemicals, Inc .: nonvolatile content: 35% by weight) was added to the aqueous dispersion as a dryer. This aqueous dispersion was applied to a polished steel plate using a bar coater so that the thickness of the dried coating film was about 30 μm. After drying this at room temperature for 3 days, the coated plate was immersed in water, and the state after further standing at room temperature for 3 days was observed. The criteria for evaluation are as follows.
○: No change in appearance.
Δ: Slightly whitened.
X: Whitening.
〔Pencil hardness〕
The coating film hardness of the coated plate prepared in the same manner as in the water resistance test was examined by a scratch test according to JIS-K5400.
[0056]
[Table 1]

[0057]
【The invention's effect】
Since the water dispersant of the present invention is composed of an acrylic resin containing the above-described hydrophilic branched chain and a hydrophobic branch containing a carbon chain having an unsaturated bond, the hydrophobic material can be stably dispersed in water, and at the time of drying. A coating film exhibiting high water resistance can be formed.
Since the aqueous dispersion of the present invention contains the above-described aqueous dispersant, the hydrophobic material is stably dispersed in water, and a coating film having high water resistance can be formed when used as a paint.

Claims

Hydrophilic branched chain containing a hydrophilic group selected from the group consisting of acidic sulfate ester group, neutral salt of acidic sulfate ester, acidic phosphate ester group and neutralized salt of acidic phosphate ester, and drying oil or semi-drying oil An aqueous dispersion comprising an acrylic resin containing a hydrophobic branched chain containing a carbon chain having an unsaturated bond, which is a fatty acid residue derived from the above.

The aqueous dispersant according to claim 1, wherein the neutralized salt of the acidic sulfate ester and the neutralized salt of the acidic phosphate ester are neutralized salts with a base selected from the group consisting of ammonia, an amine, and an alkali metal.

2 to 50% by weight of the repeating unit represented by the following general formula (1), 30 to 70% by weight of the repeating unit represented by the following general formula (2), and the repeating unit represented by the following general formula (3) The number average molecular weight including 30% by weight or less and 50% by weight or less of repeating units derived from acrylic resin-forming monomers other than the repeating units represented by the general formulas (1), (2) and (3) An aqueous dispersant comprising an acrylic graft polymer of 2,000 to 200,000.

The group R ³ contained in the general formula (1), the group R ⁶ contained in the general formula (2), and the group R ⁹ contained in the general formula (3) are as follows: 3. A water dispersant according to 3.

The repeating unit derived from the acrylic resin-forming monomer is at least selected from the group consisting of acrylic esters, methacrylic esters, dialkyl esters of fumaric acid, styrene, styrene derivatives, acrylonitrile, methacrylonitrile, vinyl acetate. The water dispersant according to claim 3 or 4, which is a repeating unit derived from one species.

2 to 50% by weight of the monomer represented by the following general formula (6), 30 to 70% by weight of the monomer represented by the following general formula (7), and the following general formula (8) Synthesized by radical polymerization of 30% by weight or less of the monomer and 50% by weight or less of the acrylic resin-forming monomer other than the monomers represented by the general formulas (6), (7) and (8). An aqueous dispersant comprising an acrylic graft polymer having a number average molecular weight of 2,000 to 200,000.

The group R ²¹ contained in the general formula (6), the group R ²⁴ contained in the general formula (7), and the group R ²⁷ contained in the general formula (8) are as follows: 6. A water dispersing agent according to 6.

The acrylic resin-forming monomer is at least one single member selected from the group consisting of acrylic esters, methacrylic esters, dialkyl esters of fumaric acid, styrene, styrene derivatives, acrylonitrile, methacrylonitrile, and vinyl acetate. The water dispersant according to claim 6 or 7, which is a monomer.

Water as a dispersion medium, a hydrophobic material, and a hydrophilic group selected from the group consisting of an acidic sulfate group, a neutralized salt of acidic sulfate, an acidic phosphate group, and a neutralized salt of acidic phosphate An aqueous dispersion comprising an aqueous dispersion comprising an acrylic resin comprising a hydrophilic branched chain and a hydrophobic branched chain containing a carbon chain having an unsaturated bond which is a fatty acid residue derived from a drying oil or a semi-drying oil .

The water dispersant contains 2 to 50% by weight of the repeating unit represented by the following general formula (1), 30 to 70% by weight of the repeating unit represented by the following general formula (2), and the following general formula (3). And 30% by weight or less of the repeating unit represented by formula (1), (2) and 50% by weight or less of the repeating unit derived from an acrylic resin-forming monomer other than the repeating units represented by (3). The water dispersion according to claim 9, comprising an acrylic resin having a number average molecular weight of 2,000 to 200,000.

The group R ³ contained in the general formula (1), the group R ⁶ contained in the general formula (2), and the group R ⁹ contained in the general formula (3) are as follows: The water dispersion according to 10.

The repeating unit derived from the acrylic resin-forming monomer is at least selected from the group consisting of acrylic esters, methacrylic esters, dialkyl esters of fumaric acid, styrene, styrene derivatives, acrylonitrile, methacrylonitrile, vinyl acetate. The aqueous dispersion according to claim 10 or 11, which is a repeating unit derived from one species.

The aqueous dispersion according to claim 9, 10, 11 or 12, wherein the hydrophobic material is a hydrophobic resin selected from the group consisting of alkyd resins, epoxy esters and oil-modified polyurethane resins.

The water dispersion according to claim 13, wherein the weight ratio A: B of the hydrophobic resin (A) and the water dispersant (B) is from 2: 8 to 8: 2.