JP3696410B2 - Thermosetting powder coating composition - Google Patents

Description

［式（１）中、Ｘ¹及びＸ²は下記一般式（ａ）〜（ｆ）
【００４８】
【化１４】

（式（ａ）〜（ｆ）中、Ｒａ、Ｒb、Ｒc、Ｒd及びＲeは、直接結合、炭素原子数１〜８のアルキレン基、フェニレン基、アルキレン基誘導体、フェニレン基誘導体、若しくは、エーテル結合及び／又はエステル結合を有する炭化水素基を表わし、Ｒfは、炭素原子数１〜８のアルキル基、フェニル基又はそれらの誘導体を表わす。）
のうちの何れかの式で示される基であり、Ｒ¹及びＲ²は、直接結合、炭素原子数１〜８のアルキレン基、フェニレン基又はそれらの誘導体を表わし、Ｒ³〜Ｒ⁸は炭素原子数１〜８のアルキル基、フェニル基又はそれらの誘導体を表わし、ｎ1は１〜１,５００の数を表わす。］
【００４９】
【化１５】

［式（II）中、Ｘ³は、前記一般式（ａ）〜（ｅ）のうちの何れかの式で示される基であり、Ｒ⁹〜Ｒ¹⁵は、炭素原子数１〜８のアルキル基、フェニル基又はそれらの誘導体を表わし、Ｒ¹⁶は、直接結合、炭素原子数１〜８のアルキレン基、フェニレン基、アルキレン基誘導体、フェニレン基誘導体、若しくは、エーテル結合及び／又はエステル結合を有する炭化水素基を表わし、ｎ2は１〜１,５００の数を表わす。］
【００５０】
【化１６】

［式（III）中、Ｘ⁴は、前記一般式（ａ）〜（ｅ）のうちの何れかの式で示される基であり、Ｒ¹⁷〜Ｒ²⁵は、炭素原子数１〜８のアルキル基、フェニル基又はそれらの誘導体を表わし、Ｒ²⁶は、直接結合、炭素原子数１〜８のアルキレン基、フェニレン基、アルキレン基誘導体、フェニレン基誘導体、若しくは、エーテル結合及び／又はエステル結合を有する炭化水素基を表わし、x1は１〜１,３００の数、y1は１〜２００の数を表わす。］
【００５１】
【化１７】

［式（IV）中、、Ｘ⁵、Ｘ⁶及びＸ⁷は、前記一般式（ａ）〜（ｅ）のうちの何れかの式で示される基であり、Ｒ³⁰〜Ｒ³⁶は、炭素原子数１〜８のアルキル基、フェニル基又はそれらの誘導体を表わし、Ｒ²⁷〜Ｒ²⁹は、直接結合、炭素原子数１〜８のアルキレン基、フェニレン基、アルキレン基誘導体、フェニレン基誘導体、若しくは、エーテル結合及び／又はエステル結合を有する炭化水素基を表わし、x2は１〜１,３００の数、y2は１〜２００の数を表わす。］
のうちの何れかの式で示される少なくとも１種の化合物であることが好ましい。さらに具体的には、有機変性ポリシロキサン（Ｂ）は、下記一般式（Ｖ）〜（XXVIII）
【００５２】
【化１８】

【００５３】
【化１９】

【００５４】
【化２０】

【００５５】
【化２１】

【００５６】
【化２２】

【００５７】
【化２３】

【００５８】
【化２４】

（式（Ｖ）〜（XXVIII）中、Ｒは各々独立して、直接結合、炭素原子数１〜２０のアルキレン基、フェニレン基、アルキレン基誘導体、フェニレン基誘導体、若しくは、エーテル結合及び／又はエステル結合を有する炭化水素基を表わし、ｎは各々独立して１〜１,５００の数、ｘは各々独立して１〜１,３００の数、ｙは各々独立して１〜２００の数を表わす。）
のうちの何れかの式で示される化合物であることがより好ましい。
【００５９】
一般式（Ｉ）のＲ³〜Ｒ⁸、一般式（II）のＲ⁹〜Ｒ¹⁵、一般式（III）のＲ¹⁷〜Ｒ²⁵、及び、一般式（IV）のＲ³⁰〜Ｒ³⁶は、炭素原子数１〜８のアルキル基、フェニル基またはそれらの誘導体を包含する炭化水素基である。これらとしては、フェニル基、メチル基が好ましく、メチル基がより好ましい。
【００６０】
各一般式（Ｉ）〜（IV）の繰返し単位数（n1、n2、x1+y1、x2+y2）の範囲は、各式に定義した通りであるが、さらにその範囲の下限値は、１０が好ましく、１００がより好ましく、５００が特に好ましい。
【００６１】
一般式（Ｖ）〜（XII）の有機変性ポリシロキサンのエポキシ当量は、２００〜５,０００であることが好ましい。また、一般式（XIII）〜（XVI）の有機変性ポリシロキサンのカルボキシル当量は、５００〜５,０００であることが好ましい。また、一般式（XVII）〜（XX）の有機変性ポリシロキサンの−ＯＨ当量は、１,０００〜５,０００であることが好ましい。また、一般式（XXI）〜（XXVIII）の有機変性ポリシロキサンの−ＮＨ₂当量は、５００〜１０,０００であることが好ましい。
【００６２】
一般式（Ｉ）で示される有機変性ポリシロキサン（Ｂ）の市販品としては、例えば、Ｘ¹及びＸ²が一般式（ａ）で表される基である、ＢＹ１６−８５５、ＢＹ１６−８５５Ｂ（以上、東レダウコーニングシリコーン株式会社製、商品名）、ＫＦ−１０５、Ｘ−２２−１６３Ａ、Ｘ−２２−１６３Ｂ、Ｘ−２２−１６３Ｃ（以上、信越化学工業株式会社製、商品名）等の両末端エポキシ変性ジメチルポリシロキサンが挙げられる。
【００６３】
また例えば、Ｘ¹及びＸ²が一般式（ｂ）で表される基である、Ｘ−２２−１６９ＡＳ、Ｘ−２２−１６９Ｂ（以上、信越化学工業株式会社製、商品名）等の両末端脂環エポキシ変性ジメチルポリシロキサンが挙げられる。
【００６４】
また例えば、Ｘ¹及びＸ²が一般式（ｃ）で表される基である、ＢＹ１６−７５０（以上、東レダウコーニングシリコーン株式会社製、商品名）、Ｘ−２２−１６２Ａ、Ｘ−２２−１６２Ｃ（以上、信越化学工業株式会社製、商品名）等の両末端カルボキシル変性ジメチルポリシロキサンが挙げられる。
【００６５】
また例えば、Ｘ¹及びＸ²が一般式（ｄ）で表される基である、ＢＹ１６−７５２（以上、東レダウコーニングシリコーン株式会社製、商品名）、Ｘ−２２−１６９Ｂ（以上、信越化学工業株式会社製、商品名）等の両末端フェノール変性ジメチルポリシロキサンが挙げられる。
【００６６】
また例えば、Ｘ¹及びＸ²が一般式（ｅ）で表される基である、ＢＹ１６−８５３、ＢＹ１６−８５３Ｂ（以上、東レダウコーニングシリコーン株式会社製、商品名）、Ｘ−２２−１６１ＡＳ、Ｘ−２２−１６１Ａ、Ｘ−２２−１６１Ｂ、ＫＦ−８０１２（以上、信越化学工業株式会社製、商品名）等の両末端アミノ変性ジメチルポリシロキサンが挙げられる。
【００６７】
一般式（II）で示される有機変性ポリシロキサン（Ｂ）の市販品としては、例えば、Ｘ³が一般式（ａ）で表される基である、Ｘ−２２−１７３ＤＸ（以上、信越化学工業株式会社製、商品名）等の片末端エポキシ変性ジメチルポリシロキサンが挙げられる。
【００６８】
一般式（III）で示される有機変性ポリシロキサン（Ｂ）の市販品としては、例えば、Ｘ⁴が一般式（ａ）で表される基である、ＳＦ８４１１、ＳＦ８４１３（以上、東レダウコーニングシリコーン株式会社製、商品名）、ＫＦ−１００１、ＫＦ−１０１（以上、信越化学工業株式会社製、商品名）等の側鎖エポキシ変性ジメチルポリシロキサンが挙げられる。
【００６９】
また例えば、Ｘ⁴が一般式（ｂ）で表される基である、ＢＹ１６−８３９（以上、東レダウコーニングシリコーン株式会社製、商品名）、ＫＦ−１０２（以上、信越化学工業株式会社製、商品名）等の側鎖脂環エポキシ変性ジメチルポリシロキサンが挙げられる。
【００７０】
また例えば、Ｘ⁴が一般式（ｃ）で表される基である、ＳＦ８４１８（以上、東レダウコーニングシリコーン株式会社製、商品名）、Ｘ−２２−３７０１Ｅ（以上、信越化学工業株式会社製、商品名）等の側鎖カルボキシル変性ジメチルポリシロキサンが挙げられる。
【００７１】
また例えば、Ｘ⁴が一般式（ｅ）で表される基である、例えば、ＢＹ１６−８２８、ＢＹ１６−８５９（以上、東レダウコーニングシリコーン株式会社製、商品名）、ＫＦ−８６４、ＫＦ−８６５、ＫＦ−８６８、ＫＦ８００３（以上、信越化学工業株式会社製、商品名）等の側鎖アミノ変性ジメチルポリシロキサンが挙げられる。
【００７２】
有機変性ポリシロキサン（Ｂ）の重量平均分子量は、通常、５００〜１００,０００が好ましく、１,０００〜９０,０００がより好ましい。有機変性ポリシロキサン（Ｂ）の重量平均分子量が上記範囲であると、得られる塗膜の外観が良好であり、且つ、耐擦り傷性、耐酸性、リコート性が良好である。
【００７３】
［有機変性ポリシロキサン（Ｂ）の作用機構］
本発明において使用する熱硬化性粉体塗料組成物中の有機変性ポリシロキサン（Ｂ）の作用効果は、次のようなものであると推測される。
【００７４】
加熱により有機変性ポリシロキサン（Ｂ）中の反応性官能基が、アクリル系共重合体（Ａ）又は硬化剤（Ｃ）の反応性官能基と反応することで、有機変性ポリシロキサン（Ｂ）が硬化塗膜中に均一に保持され、ポリシロキサンの有する特性により、特に耐溶剤性、耐酸性、耐擦り傷性に優れた架橋塗膜を形成できる。また、有機変性ポリシロキサン（Ｂ）が加熱硬化により３次元網目構造内に取り込まれるので、相溶性が持続され、かつポリシロキサン骨格が塗膜表面に極端に局在化することが防止される。
【００７５】
また、焼き付け時の昇温の際に、有機変性ポリシロキサン（Ｂ）中の反応性官能基が、アクリル系共重合体（Ａ）又は硬化剤（Ｃ）と架橋反応して、３次元網目構造中に取り込まれる際に、内部可塑化が起こり、塗料の溶融粘度が低下し、塗膜の平滑性が良好になる側面も担っている。
【００７６】
アクリル系共重合体（Ａ）又は硬化剤（Ｃ）の反応性官能基と反応可能な官能基を有さないポリシロキサンを用いた場合、そのポリシロキサンは、アクリル系共重合体（Ａ）及び硬化剤（Ｃ）と架橋反応可能な反応基を有さない為、加熱硬化時のアクリル系共重合体（Ａ）及び硬化剤（Ｃ）との相溶性が不十分であり、得られる塗膜の耐酸性には優れるものの、クリア塗膜にした場合の外観（透明性、平滑性）、耐溶剤性及びリコート性の低下が起こり、バランス取りが困難になる。
【００７７】
［有機変性ポリシロキサン（Ｂ）の使用量］
本発明における有機変性ポリシロキサン（Ｂ）の使用量は、アクリル系共重合体（Ａ）１００重量部を基準として、０.０１〜２.０重量部である。この使用量が２.０重量部を越えると、塗膜は白濁し、透明性や鮮映性の低下が起こる傾向がある。また、この使用量が０.０１重量部未満では、得られる塗膜の耐酸性や耐擦り傷性の改良が不十分となる。この使用量は、０.０１〜１.０重量部であることがより好ましい。
【００７８】
［硬化剤（Ｃ）］
本発明で用いる硬化剤（Ｃ）は、多価カルボン酸（ｃ１）及び多価カルボン酸無水物（ｃ２）からなる群より選択された少なくとも１種の多価カルボン酸系化合物からなるものであることが好ましい。以下、多価カルボン酸（ｃ１）及び多価カルボン酸無水物（ｃ２）の例について説明する。
【００７９】
［多価カルボン酸（ｃ１）］
多価カルボン酸（ｃ１）としては、脂肪族、芳香族、脂環族の何れの化合物も使用できる。芳香族多価カルボン酸の具体例としては、例えば、イソフタル酸、トリメリット酸等が挙げられ、これらは単独で又は組み合わせて使用できる。脂環式多価カルボン酸の具体例としては、例えば、ヘキサヒドロフタル酸、テトラヒドロフタル酸等が挙げられ、これらは単独で又は組み合わせて使用できる。また、カルボキシル基を有するポリエステル樹脂等も使用できる。
【００８０】
但し、本発明においては、脂肪族多価カルボン酸を用いることが、平滑性、耐候性等の塗膜特性の点で好ましい。
【００８１】
本明細書において用いる「脂肪族」なる語の概念には、狭義の脂肪族のみならず、実質的に芳香族度が低い脂環族をも包含する。すなわち、この「脂肪族」化合物なる語の概念には、少なくとも１個の炭素原子を含む２価の炭化水素基を分子内に有する、実質的に芳香族度の低い化合物からなる群をも包含し、具体的には、狭義の脂肪族基のみならず、実質的に芳香族度の低い脂環族基、これらを組み合わせた基、又はこれらが水酸基、窒素、硫黄、けい素、りんなどで結合されるような２価の残基を分子内に有する化合物からなる群をも包含し、さらに具体的には、上記のものに例えば、アルキル基、シクロアルキル基、アリル基、アルコキシル基、シクロアルコキシル基、アリルオキシル基、ハロゲン（Ｆ，Ｃｌ，Ｂｒ等）基等が置換した基を分子内に有する化合物からなる群をも包含する。これらの置換基を適宜選択することにより、本発明に用いる共重合体の諸特性（耐熱性、強靭性、分解性、強度特性等）を制御することができる。本明細書において用いる「脂肪族」化合物なる語の概念には、一種類の化合物のみならず、二種類以上の組合せによるものをも包含する。
【００８２】
以下、この脂肪族多価カルボン酸の例について説明する。
【００８３】
脂肪族多価カルボン酸は、実質的に、分子内にカルボキシル基を少なくとも２個有する脂肪族化合物であれば、特に制限されず、１種類又は２種類以上を用いることができる。特に炭素原子数８〜２０の脂肪族ジカルボン酸が好ましい。
【００８４】
脂肪族多価カルボン酸の具体例としては、脂肪族ジカルボン酸などが挙げられる。脂肪族ジカルボン酸の具体例としては、例えば、セバシン酸、ウンデカン２酸、ドデカン２酸、ブラシリン酸、エイコサン２酸、オクタデカン２酸等が挙げられ、これらの中では、セバシン酸、ドデカン２酸、ブラシリン酸、及び、エイコサン２酸が好ましく、ドデカン２酸がより好ましい。これらは単独で又は組み合わせて使用できる。
【００８５】
平滑性、耐衝撃性、耐候性等の塗膜特性に関して、脂環式多価カルボン酸については、芳香族度が高くなるに従い、塗膜特性が劣化する。
【００８６】
［多価カルボン酸無水物（ｃ２）］
本明細書において用いる「アンヒドリド」、「アンヒドリド基」、「アンヒドリド結合」及び「ポリアンヒドリド」なる語の概念には、「ＭＡＲＵＺＥＮ高分子大辞典−Ｃｏｎｃｉｓｅ Ｅｎｃｙｃｌｏｐｅｄｉａ ｏｆ ＰｏｌｙｍｅｒＳｃｉｅｎｃｅ ａｎｄ Ｅｎｇｉｎｅｅｒｉｎｇ（Ｋｒｏｓｃｈｗｉｔｚ編、三田 達監訳、丸善、東京、１９９４年）」・９９６〜９９８頁の「ポリアンヒドリド」の項に記載されているそれぞれの語に関する概念をも包含する。本明細書において用いる「酸無水物」及び「アンヒドリド」なる語の概念は、相互に等価の概念であり、本出願の明細書において用いる「酸無水物」または「アンヒドリド」なる語の概念には、化学大辞典・第３巻（共立出版刊・１９６３年）・９９６頁左欄〜９９７頁右欄記載の「酸無水物」の項に記載されている概念をも包含する。
【００８７】
本発明においては、橋架け効果等の点から、線状の脂肪族多価カルボン酸無水物が好ましい。以下、脂肪族多価カルボン酸酸無水物の例について説明する。
【００８８】
脂肪族多価カルボン酸無水物は、実質的に、分子内にカルボキシル基を有するか又は有しない、線状の２量体以上のオリゴ又はポリの脂肪族の酸無水物（アンヒドリド）であって、分子内に実質的に存在するカルボキシル基及び／又は酸無水物（アンヒドリド）基を、少なくとも２個有する化合物であれば、特に制限されず、１種類または２種類以上を用いることができる。
【００８９】
本明細書において「線状」なる語の概念には、線状のみならず、線状の２量体以上のオリゴまたはポリの脂肪族の酸無水物（アンヒドリド）が、線状と同様の作用を奏する大環状を形成している場合をも包含する。
【００９０】
脂肪族多価カルボン酸無水物の具体例としては、１種類または２種類以上の脂肪族ジカルボン酸を脱水縮合して得られる線状重縮合物が挙げられる。例えば、１種類の脂肪族多価カルボン酸を脱水縮合して得られる線状重縮合物のある種のものは、以下の一般式で表すことができる。
【００９１】
ＨＯ−［ＯＣ（ＣＨ₂）ｍＣＯＯ］ｎ−Ｈ
ここでｍは１以上、ｎは２以上の、それぞれ自然数であり、好ましくはｍは３０以下である。
【００９２】
脂肪族ジカルボン酸の線状酸無水物（ｃ２）の具体例としては、例えば、上記脂肪族多価カルボン酸（ｃ１）の脱水線状縮合物が挙げられる。これらの中では、セバシン酸、ドデカン２酸、ブラシリン酸、及び、エイコサン２酸からなる群より選択された少なくとも１種の化合物の脱水縮合により誘導された線状の２量体以上のオリゴまたはポリ酸無水物が好ましく、ドデカン２酸の脱水線状縮合物がさらに好ましい。
【００９３】
多価カルボン酸無水物（ｃ２）のその他の具体例として、例えば、欧州特許公開公報６９５,７７１号に記載のポリイソシアネート変性のジカルボン酸（ポリ）無水物や欧州特許公開公報２９９,４２０号に記載のポリオール変性ポリマー状ポリ酸無水物等の変性ポリ酸無水物も好適に使用することができる。
【００９４】
多価カルボン酸無水物（ｃ２）として、市販の多価カルボン酸無水物も好適に使用が可能である。これら市販の多価カルボン酸無水物の具体例としては、例えば、フィアノバレジン社製の商品名「Ａｄｄｉｔｏｌ ＶＸＬ１３８１」、岡村製油（株）製の商品名「ＰＳ−ＡＨ」等が挙げられる。
【００９５】
多価カルボン酸無水物（ｃ２）は、融点が４０〜１７０℃の範囲にあるように調整することが好ましい。多価カルボン酸無水物（ｃ２）の融点が上記範囲では、塗膜外観が良好で、且つ、粉体塗料のブロッキング性が良好になる。
【００９６】
［脂肪族ジカルボン酸無水物による架橋結合形成］
無水こはく酸や無水フタル酸のような多価カルボン酸の環状無水物を、アクリル系共重合体（Ａ）中のエポキシ基と反応させると、その無水物は、その分子中の特定のグリシジル基のエポキシ環とのみ反応する確率が高いため、複数のアクリル系共重合体（Ａ）分子を橋架けする効果が小さい。
【００９７】
一方、脂肪族ジカルボン酸の（共）重縮合物を、エポキシ基と反応させると、その縮合物は、アンヒドリド基部分で開裂して複数のフラグメントとなり、それぞれが、別々のアクリル系共重合体（Ａ）分子中のエポキシ基と反応し、複数のアクリル系共重合体（Ａ）分子を橋架けする効果が発揮されるので、塗膜の耐溶剤性、耐酸性等の化学的特性が向上する。
【００９８】
［硬化剤（Ｃ）の使用量］
硬化剤（Ｃ）の使用量は、アクリル系共重合体（Ａ）１００重量部を基準として、５〜６０重量部が好ましく、１５〜５０重量部がより好ましい。
【００９９】
また、当量比としては、アクリル系共重合体（Ａ）のエポキシ基１当量に対して、硬化剤（Ｃ）の架橋反応可能な官能基（カルボキシル基及び／又は酸無水物基等）が０.５〜１.５当量であることが好ましく、０.７〜１.２当量であることがより好ましい。
【０１００】
硬化剤（Ｃ）の使用量や官能基の当量比をこれら範囲内にすることにより、塗膜の外観、耐溶剤性、擦り傷性などの特性を向上できる。
【０１０１】
［硬化剤（Ｃ）の融点］
硬化剤（Ｃ）の融点は、４０〜１７０℃であることが好ましい。融点が４０℃以上の硬化剤（Ｃ）を用いることは、粉体塗料の貯蔵安定性等においてより優れた結果をもたらす。一方、融点が１７０℃以下の硬化剤（Ｃ）を用いることは、塗料焼付け時の加熱流動性、得られる塗膜の平滑性等において、より優れた結果をもたらす。
【０１０２】
［添加剤］
本発明の粉体塗料組成物には、通常、塗料に添加される種々の添加剤を添加することができる。
【０１０３】
すなわち、本発明の粉体塗料組成物に、目的に応じて、適宜、エポキシ樹脂、ポリエステル樹脂、ポリアミドなどを包含する合成樹脂組成物、繊維素又は繊維素誘導体などを包含する天然樹脂又は半合成樹脂組成物を配合して、塗膜外観又は塗膜物性を向上させることもできる。
【０１０４】
さらに本発明の粉体塗料組成物には、目的に応じて、適宜、硬化触媒、顔料、流動調整剤、チクソ剤（チクソトロピー調整剤）、帯電調整剤、表面調整剤、光沢付与剤、ブロッキング防止剤、可塑剤、紫外線吸収剤、ワキ防止剤（脱ガス剤）、着色防止剤、酸化防止剤等の添加剤を配合してもよい。また、クリアコートとして使用する場合に、少量の顔料を配合し、完全な隠ぺい性の発現しない程度に着色していてもよい。
【０１０５】
なお「粉体塗料組成物」とは、一般に硬化剤（Ｃ）を含んでそれ自体が粉体塗料として使用されるものを言うが、本発明の「粉体塗料組成物」は、それだけでなく、硬化剤（Ｃ）を添加する前の粉体塗料用の樹脂成分材料の意味も含むものとする。
【０１０６】
本発明の粉体塗料組成物を製造するための方法（組成物の配合方法）は、アクリル系共重合体（Ａ）、有機変性ポリシロキサン（Ｂ）、及び、所望により硬化剤（Ｃ）を、所望の比率になるように配合可能な方法であれば特に制限されず、公知又は公用の方法を採用できる。また、有機変性ポリシロキサン（Ｂ）の分散性を高めるために、有機変性ポリシロキサン（Ｂ）をアクリル系共重合体（Ａ）又は硬化剤（Ｃ）に溶融させ、予め均一に分散しておく方法も採用できる。
【０１０７】
本発明の粉体塗料組成物を製造するための方法の具体例としては、ロール機、ニーダー機、ミキサー（バンバリー型、トランスファー型等）、カレンダー設備、押出機等の混練機を適宜組み合わせ、各工程の条件（温度、溶融若しくは非溶融、回転数、真空雰囲気、不活性ガス雰囲気等）を適宜設定して、充分に均一に混合する方法が挙げられる。この後、粉砕装置等を用いて、均一な微細粉末状態の粉体塗料を得ることができる。ただし、本発明はこれらに限定されるものではない。
【０１０８】
更に、本発明の粉体塗料組成物に添加剤等を加える配合混練工程の一態様として、アクリル系共重合体（Ａ）、有機変性ポリシロキサン（Ｂ）及び硬化剤（Ｃ）に、必要に応じ、ブロッキング防止剤、表面調整剤、可塑剤、帯電調整剤、顔料、充填剤、増量剤等の添加剤を加え、好ましくは４０〜１３０℃、より好ましくは６０〜１３０℃の範囲で、溶融混練装置により充分に溶融混練し、冷却すれば、その添加剤が配合された本発明の粉体塗料組成物が得られる。この後、適当な粒度（通常、１５０メッシュ以下）に均一に粉砕すれば、微細粉末状態の粉体塗料が得られる。この溶融混練装置としては、通常、加熱ロール機、加熱ニーダー機、押出機（エクストルーダー）等を使用できる。
【０１０９】
本発明の組成物からなる熱硬化性粉体塗料を塗装する方法の具体例としては、例えば、静電塗装法、流動浸漬法等の塗装方法によって、その熱硬化性粉体塗料を対象物に付着せしめ、加熱して熱硬化させ塗膜を形成させる方法が挙げられる。この熱硬化の為の焼付けは、通常約１００℃〜約２００℃、好ましくは約１２０℃〜約１８０℃の温度において、通常約１０〜約６０分間行なわれる。この焼付けにより、アクリル系共重合体（Ａ）、有機変性ポリシロキサン（Ｂ）、及び硬化剤（Ｃ）が架橋反応する。この焼付け後、室温まで冷却すれば、優れた特性を有する硬化塗膜が得られる。
【０１１０】
本発明の熱硬化性粉体塗料組成物は、先に述べたような優れた特性を有するので、自動車の車体又は自動車部品等のトップコート用途に非常に有用である。とりわけ、自動車の車体又は自動車部品を本発明の組成物からなる熱硬化性粉体塗料を用いて上塗り塗装する方法、顔料入り又はメタリックの水性塗料の下塗り塗料の上に本発明の組成物からなる熱硬化性粉体塗料を上塗り塗料として静電塗装し、該下塗り塗料と該上塗り塗料を同時に焼き付ける塗膜形成方法などにおいて非常に有用である。
【０１１１】
［語「誘導体」の概念］
本出願の特許請求の範囲及び明細書において用いる「誘導体」なる語の概念には、特定の化合物の水素原子が、他の原子あるいは原子団Ｚによって置換されたものを包含する。
【０１１２】
ここで、Ｚは、少なくとも１個の炭素原子を含む１価の炭化水素基であり、より具体的には、脂肪族、実質的に芳香族度の低い脂環族、これらを組み合わせた基、又はこれらが水酸基、カルボキシル基、アミノ基、窒素、硫黄けい素、りんなどで結合されるような残基であってもよく、これらのうち、特に、狭義の脂肪族系の構造のものが好ましい。Ｚは、上記のものに、例えば、水酸基、アルキル基、シクロアルキル基、アリル基、アルコキシル基、シクロアルコキシル基、アリルオキシル基、ハロゲン（Ｆ、Ｃｌ、Ｂｒ等）基等が置換した基であってもよい。
【０１１３】
これらの置換基を適宜選択することにより、本発明の粉体塗料組成物により形成される塗膜の諸特性を制御することができる。
【０１１４】
【実施例】
以下、本発明をさらに具体的に説明するために、実施例及び比較例を挙げて説明するが、これらは、本発明の内容の理解を助けるためのものであって、その記載によって本発明が何ら限定されるものではない。また、以下の記述の中で用いる「部」及び「％」は、特に説明の無い限り、それぞれ「重量部」及び「重量％」を意味する。
【０１１５】
［製造例１〜４：アクリル系共重合体の製造］
まず、撹拌機、温度計、還流コンデンサー及び窒素導入管を備えた４つ口フラスコに、有機溶媒としてキシレンを装入し、撹拌しながら還流温度まで昇温した。キシレンの装入量は、後ほど仕込む単量体の合計重量の６６.７部に相当する量とした。次いで、系を環流温度に保持、撹拌しながら、表１に示す単量体にラジカル重合開始剤としてｔ−ブチル−パーオキシ−２−エチルヘキサノエート（商標名パーブチルＯ、日本油脂株式会社製）を表１に示す量だけ溶解し、その混合溶液を５時間に渡り滴下して、さらに、その後パーブチルＯを０.５重量部滴下し、１００℃で５時間保持した。得られた重合溶液の溶剤を加熱減圧下で除去する事により固体のアクリル系共重合体（製造例１〜４）を得た。得られたアクリル系共重合体（製造例１〜４）の物性を次の方法により分析し、その結果を表１に記載した。
▲１▼ ガラス転移温度（Ｔｇ）：
モノマー組成に基づき、Ｆｏｘの式により計算して求めた。
▲２▼ 数平均分子量（Ｍｎ）：
ＧＰＣにより、ポリスチレンを標準として測定した。
【０１１６】
［製造例５：アクリル系共重合体の製造］
単量体成分として、ポリジメチルシロキサンマクロモノマー（東亜合成株式会社製、商品名シリコーンマクロモノマーＡＫ−３０）０.１重量部を、単量体（ａ１）及び単量体（ａ２）と共に共重合させたこと以外は、製造例１と全く同様な手法で、シリコーンマクロモノマーが共重合した固体のアクリル系共重合体（製造例５）を得た。
【０１１７】
［製造例６：アクリル系共重合体の製造］
単量体成分として、γ−メタクリロキシプロピルトリメトキシシラン０.１重量部を、単量体（ａ１）及び単量体（ａ２）と共に共重合させた以外は、製造例１と全く同様な手法で、シリコーン系単量体が共重合した固体のアクリル系共重合体（製造例６）を得た。
【０１１８】
［製造例７：有機変性ポリシロキサン含有アクリル系共重合体の製造］
製造例１で用いたものと同様な反応器に、有機溶媒としてキシレンを６６.７重量部装入し、さらに有機変性ポリシロキサンとして、Ｘ−２２−１６３Ａ（両末端エポキシ変性のジメチルポリシロキサン、エポキシ当量９５０ｇ／ｅｑ.、信越化学工業株式会社製、商品名）を０.１重量部添加し、撹拌しながら還流温度まで昇温した。
【０１１９】
次いで、系を環流温度に保持、撹拌しながら、表１に示す単量体にパーブチルＯを５.０重量部溶解し、その混合溶液を５時間に渡り滴下して、さらに、その後パーブチルＯを０.５重量部滴下し、１００℃で５時間保持した。得られた重合溶液の溶剤を加熱減圧下で除去する事により、数平均分子量２８００の、固体の有機変性ポリシロキサン含有アクリル系共重合体（製造例７）を得た。
【０１２０】
［製造例８：有機変性ポリシロキサン含有アクリル系共重合体の製造］
製造例１で用いたものと同様な反応器にキシレンを１００重量部装入し、製造例１で得られたアクリル系共重合体を１００重量部を添加し、撹拌しながら１００℃に加熱し均一に溶解した後、さらに有機変性ポリシロキサン（Ｂ）としてＫＦ−８０１２（両末端アミノ変性のジメチルポリシロキサン、−ＮＨ₂当量２,３００ｇ／ｅｑ.、信越化学工業株式会社製、商品名）を０.１重量部添加し、撹拌しながら還流温度まで昇温し、有機変性ポリシロキサンを均一に分散させた。
【０１２１】
次いで、得られた樹脂溶液の溶剤を加熱減圧下で除去する事により、数平均分子量２９００の、有機変性ポリシロキサンが変性された固体アクリル系共重合体（製造例８）を得た。
【０１２２】
［製造例９：シラン化合物が変性されたアクリル系共重合体の製造］
製造例１で用いたものと同様な反応器に、キシレンを１００重量部装入し、製造例１で得られたアクリル系共重合体を１００重量部を添加し、撹拌しながら１００℃に加熱し均一に溶解した後、さらに、γ−アミノプロピルトリメトキシシランを０.１重量部添加し、撹拌しながら還流温度まで昇温し、γ−アミノプロピルトリメトキシシランを均一に分散させた。次いで、得られた樹脂溶液の溶剤を加熱減圧下で除去する事により、数平均分子量２８００の、γ−アミノプロピルトリメトキシシランが含有された固体のアクリル系共重合体（製造例９）を得た。
【０１２３】
［製造例１０：ドデカン２酸線状酸無水物（ｃ２）の製造］
ドデカン２酸及び無水酢酸（モル比＝１：０.８）を反応器に装入し、１５０℃に加熱し、無水酢酸が系外に流出しないように系を減圧又は真空にしながら、生成する酢酸を除去して５時間反応させた。反応終了後直ちに冷却すると、白色の固形物［ドデカン２酸線状酸無水物（製造例１０）］が得られた。この化合物の融点は約７３〜約８２℃であった。
【０１２４】
［実施例１〜１４］
製造例１〜４において製造したアクリル系共重合体（Ａ）、有機変性ポリシロキサン（Ｂ）、及び、硬化剤（Ｃ）を、表２に示す重量比で配合し［硬化剤（Ｃ）の官能基／アクリル系共重合体（Ａ）中のエポキシ基＝１／１］、アクリル系共重合体（Ａ）及び硬化剤（Ｃ）の合計１００部に対し、ＴＩＮＵＶＩＮ１４４（チバスペシャリティケミカルズ株式会社製、商標名、光安定剤）、ベンゾイン（ワキ防止剤）を各１重量部、ＴＩＮＵＶＩＮ９００（チバスペシャリティケミカルズ株式会社製、紫外線吸収剤）を２重量部、実施例１２〜１４のみオクタン酸錫（商標名ネオスタンＵ−２８、硬化触媒、日東化成株式会社製）を０.３重量部添加した。上記混合物を、ヘンシェルミキサーを用い均一にドライブレンドした後、二軸エクストルーダーＰＣＭ−３０（池貝機販株式会社製）を用い、シリンダー温度を１１０℃、スクリューの回転数を２００ｒｐｍに設定し、２回混練（２パス）を行った。この溶融混練物を冷却後、粉砕機にて微粉砕し、１５０メッシュの篩を通過した区分を回収して、熱硬化性粉体塗料（実施例１〜１４）を得た。
【０１２５】
［実施例１５、１６］
製造例７、８で得た有機変性ポリシロキサン含有アクリル系共重合体と、硬化剤（Ｃ）を、表２で示す配合比で配合したこと以外は、実施例１と全く同様な方法で熱硬化性粉体塗料（実施例１５、１６）を得た。
【０１２６】
［比較例１］
有機変性ポリシロキサンを用いなかったこと以外は、実施例１と全く同様な方法で、熱硬化性粉体塗料（比較例１）を得た。
【０１２７】
［比較例２］
有機変性ポリシロキサンを用いなかったこと以外は、実施例２と全く同様な方法で、熱硬化性粉体塗料（比較例２）を得た。
【０１２８】
［比較例３］
流動調整剤としてＲｅｓｉｍｉｘ ＲＬ−４（三井化学株式会社製、商標名）を１重量部添加したこと以外は、比較例１と全く同様な方法で熱硬化性粉体塗料（比較例３）を得た。
【０１２９】
［比較例４］
有機変性ポリシロキサン（Ｂ）としてＸ−２２−３７０１Ｅ（信越化学工業株式会社、商品名）を５.０重量部使用したこと以外は、実施例１と全く同様な方法で熱硬化性粉体塗料（比較例４）を得た。
【０１３０】
［比較例５］
本発明の範囲内の有機変性ポリシロキサン（Ｂ）を用いる代わりに、側鎖アルキル変性のジメチルポリシロキサンであるＳＦ８４１６（東レダウコーニングシリコーン株式会社製、商品名）を０.１重量部用いたこと以外は、実施例１と全く同様な方法で熱硬化性粉体塗料（比較例５）を得た。
【０１３１】
［比較例６］
本発明の範囲内の有機変性ポリシロキサン（Ｂ）を用いる代わりに、反応性官能基が変性されていないポリジメチルシロキサンであるＫＦ９６Ｈ−１００００（信越化学工業株式会社製、商品名、２５℃における粘度１０,０００ｃsｔ）を０.１重量部用いたこと以外は、実施例１と全く同様な方法で熱硬化性粉体塗料（比較例６）を得た。
【０１３２】
［比較例７］
本発明の範囲内の有機変性ポリシロキサン（Ｂ）を用いる代わりに、γ−グリシドキシプロピルトリメトキシシランを０.１重量部用いたこと以外は、実施例１と全く同様な方法で熱硬化性粉体塗料組成物（比較例７）を得た。
【０１３３】
［比較例８］
製造例５で得られたシリコーンマクロモノマーが共重合したアクリル系共重合体１００重量部と、硬化剤としてドデカン２酸を３０.９重量部使用したこと以外は、実施例１と全く同様な方法で熱硬化性粉体塗料（比較例８）を得た。
【０１３４】
［比較例９］
製造例６で得られたシリコーン系単量体（γ−メタクリロキシプロピルトリメトキシシラン）が共重合したアクリル系共重合体１００重量部と、硬化剤としてドデカン２酸を３１.１重量部使用したこと以外は、実施例１と全く同様な方法で熱硬化性粉体塗料（比較例９）を得た。
【０１３５】
［比較例１０］
製造例９で得られたγ−アミノプロピルトリメトキシシランが変性されたアクリル系共重合体１００重量部と、硬化剤としてドデカン２酸を３１.０重量部使用したこと以外は、実施例１と全く同様な手法で、熱硬化性粉体塗料（比較例１０）を得た。
【０１３６】
〔実施例及び比較例の評価〕
ポリエステル−メラミン架橋の黒色塗料を、りん酸亜鉛処理を施した０.８ｍｍ厚の梨地鋼板に２０μｍ厚で塗装し、その後１７０℃で３０分間焼付けをして下地処理鋼板を調製した。この下地処理鋼板に、各実施例及び比較例で調製した熱硬化性粉体塗料を、膜厚が６０〜７０μｍになるように静電塗装し、１５０℃で３０分間焼付けをして、塗装板を得た。
【０１３７】
この塗装板について、以下の評価を行なった。
▲１▼ 塗膜の平滑性；平滑性について、目視で塗膜の外観を評価し、非常に優れているものを◎、優れているものを○、僅かに凸凹があるものを△、劣るものを×とした。
▲２▼ 塗膜の鮮映性；鮮映性について、目視で塗膜の外観を評価し、非常に優れているものを◎、優れているものを○、僅かに曇りがあるものを△、劣るものを×とした。
▲３▼ 光沢；光沢計測定値（６０°グロス）で評価した。
▲４▼ 耐溶剤性；キシレンを含浸させたガーゼで、塗膜表面を５０回往復摩擦した後、摩擦箇所の目視観察を行った。痕跡が、全くないものを◎、僅かにあるものを○、顕著にあるものを×とした。
▲５▼ 耐酸性（耐酸性雨性）；塗膜表面に４０ｖｏｌ％の硫酸水溶液を０.４ｍｌスポットし、６０℃の乾燥機中２０分間放置した後、スポット箇所を水洗・乾燥し、塗膜の表面状態を目視観察した。痕跡が、全くないものを◎、僅かにあるものを○、顕著にあるものを△、全面にエッチングがあるものを×とした。
▲６▼ 耐擦り傷性；塗膜表面を３％のクレンザー懸濁液を用いてブラシで摩擦する擦傷試験を行ない、摩擦の前後で光沢性の（２０°グロス）評価を行ない、光沢保持率を算出した。光沢保持率が６０％以上のものを耐擦り傷性が非常に優れているものとして◎、５０％以上６０％未満のものを優れているものとして○、５０％未満のものを耐擦り傷性が不十分なものとして×とした。
▲７▼ 耐候性；ＱＵＶテスターで２,０００時間照射し、この照射の前後で２０°の光沢度を評価し、２０°光沢保持率を算出した。光沢保持率は次式により計算した。
【０１３８】
光沢保持率［％］＝（照射後の２０°光沢度）÷（照射前の２０°光沢度）×１００
この光沢保持率が、８０％以上を◎、７０〜８０％を○、７０％以下を×とした。
▲８▼ 粉体塗料の貯蔵安定性；粉体塗料組成物を、３０℃の恒温槽中で３０日間貯蔵した。その後、この粉体塗料組成物を、１０ｍｍφ、０.３ｇのペレットに成形した。このペレットを、りん酸亜鉛処理を施した０.８ｍｍ厚の梨地鋼板に貼着し、垂直に保って、１５０℃で３０分間保持した。この際の加熱流動度（ｍｍ）を測定した。ペレットの加熱流動度が、１００ｍｍ以上のものを○、２０ｍｍ以上１００ｍｍ未満ものを△、２０ｍｍ未満のものを×とした。
▲９▼ リコート性；１５０℃で３０分間焼き付けた塗装板をさらに同温度で３０分オーバーベークした後、その塗装板の塗膜形成に使用したものと同一の粉体塗料を静電塗装し、１５０℃で３０分間焼付けを行った。この試験塗膜の２ｍｍ巾、１０×１０の碁盤目密着試験を行い、試験後、剥離せずに残ったマス目の数を表示した。全く剥離が認められない場合は１００であり、リコート性が良好な塗膜と判定され、全て剥離の場合は０であり、リコート性が不十分であると判定される。
【０１３９】
これらの塗膜の評価結果を、表３〜表５に示す。実施例１〜１６は、本発明の範囲内で構成要素の種類及び組合せを変えた組成物に関する。比較例１〜１０は、本発明の組成物と比較する為のものであり、本発明の範囲から外れる構成要素の種類及び組合せの組成物に関する。
【０１４０】
実施例１〜１６の評価結果から明らかなように、本発明の組成物は、評価項目▲１▼〜▲９▼の全てについて優れた性能を同時に発現している。
【０１４１】
比較例１、２は、有機変性ポリシロキサン（Ｂ）を使用しなかった粉体塗料組成物の例であり、塗膜の平滑性、耐酸性及び耐擦傷性が劣っている。
【０１４２】
比較例３は、有機変性シリコーンオイル（Ｂ）を使用せずに、低Ｔｇのアクリル系の流動調整剤を使用した例であるが、この場合塗膜の平滑性は比較例１に対して良好ではあるが塗膜の耐酸性、耐擦り傷性の改良が不十分である
比較例４は、有機変性ポリシロキサン（Ｂ）を本発明の範囲外の量で多用した例であるが、この場合塗膜の耐溶剤性やリコート性が劣る。
【０１４３】
比較例５、６は、本発明の範囲外の反応性官能基を有さないポリシロキサンを使用した例であるが、この場合、塗膜の外観、耐擦り傷性、耐酸性及びリコート性が劣る。
【０１４４】
比較例７は、本発明の範囲内の有機変性ポリシロキサン（Ｂ）を用いる代わりに、γ−グリシドキシプロピルトリメトキシシランを０.１重量部添加した例であるが、この場合塗膜の耐酸性、耐擦り傷性、粉体塗料の貯蔵安定性が劣る。
【０１４５】
比較例８は、シリコーンマクロモノマーが共重合したアクリル系共重合体を用いた例であるが、この場合塗膜のリコート性の改良が不十分である。
【０１４６】
比較例９は、シリコーン系単量体（γ−メタクリロキシプロピルトリメトキシシラン）が共重合したアクリル系共重合体を使用した例であるが、この場合、塗膜の耐擦り傷性及び耐酸性、塗料の貯蔵安定性が劣る。
【０１４７】
比較例１０はγ−アミノプロピルトリメトキシシランが変性されたアクリル系共重合体を使用した例であるが、この場合、塗膜の耐擦り傷性及び耐酸性、塗料の貯蔵安定性が劣る。
【０１４８】
【表１】

【０１４９】
【表２】

【０１５０】
【表３】

【０１５１】
【表４】

【０１５２】
【表５】

【０１５３】
【発明の効果】
以上説明したように、本発明によれば、
（ｉ）塗料組成物調製の際の相溶性を改善し、製造時の汚染を防止すること、
（ii）基質（下地）上における塗膜の完全被覆性を改善すること、
（iii）熱硬化により形成された塗膜の外観特性（平滑性、鮮映性等）、物理特性（耐擦傷性、リコート性等）、耐候性、耐紫外線性、及び化学特性（耐酸性雨性、耐溶剤性等）等の塗膜特性に関して、同時に優れた性能を発現させ、特に、耐酸性雨性、リコート性、耐溶剤性、及び耐擦傷性を顕著に改善すること、並びに
（iv） 塗料組成物の貯蔵安定性がを改善すること
が可能なトップコート用熱硬化性粉体塗料組成物を提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermosetting powder coating composition, and more specifically, excellent appearance characteristics (smoothness, etc.), physical characteristics (scratch resistance, recoatability, etc.), weather resistance, ultraviolet resistance, and chemicals. The present invention relates to a thermosetting powder coating composition capable of forming a coating film after baking having characteristics (acid rain resistance, solvent resistance, etc.) and having excellent storage stability.
[0002]
[Prior art]
Compared with solvent paints, powder paints have many advantages such as less risk of fire and toxicity, and high workability, and their fields of use have expanded in recent years. Among them, thermosetting acrylic resins are considered promising in terms of gloss, weather resistance, chemical resistance, and mechanical strength, and various attempts have been made to develop thermosetting acrylic resins for powder coatings. Yes. As a conventional powder coating composition containing a thermosetting acrylic resin, a copolymer of acrylic acid or methacrylic acid alkyl ester and acrylic acid or methacrylic acid glycidyl ester, the molecular weight of which is 1,000 to In general, a 30,000 acrylic resin blended with a thermosetting agent is used (for example, German Patent Application Publication Nos. 2,057,577 and 2,014,914). Gazettes). However, the smoothness, strength, chemical resistance and metal adhesion of the coating film obtained from this composition are not always sufficient.
[0003]
In addition, a composition comprising an acrylic resin and a curing agent is further blended with a cellulose derivative to improve the smoothness of the coating film (for example, JP-A-48-7943), or a polyvalent epoxy resin is blended. In addition, a composition (for example, Japanese Patent Application Laid-Open No. 48-17844) with improved chemical resistance and adhesion of the coating film has been proposed. However, a coating film formed from a powder coating comprising these compositions is not always sufficient in terms of strength.
[0004]
Regarding solvent paint, for example, Japanese Patent Application Laid-Open No. 61-151272 discloses (A) a radical polymerizable compound mainly composed of (meth) acrylate, (B) a radical polymerizable silicone macromonomer, and (C) a non-radical. A highly weather-resistant paint comprising a graft polymer formed by radical copolymerization with a crosslinkable monomer having a polymerizable reactive functional group as a main component of a resin is disclosed. However, since the silicone macromonomer of this paint is used at a high concentration (10 to 30% by weight) in the graft polymer, the coating film formed by this paint is excellent in weather resistance and solvent resistance, but is not fresh. It is inferior in film quality and recoatability. Further, this highly weather-resistant coating material is a solvent-type coating material as apparent from the composition of the resin, the curing agent, and the like and also from the description of the examples. As described below, the solvent paint is not preferable from the viewpoint of environmental protection and resource saving.
[0005]
Recently, environmental problems such as air pollution, global warming, and acid rain have become major problems. In particular, in the technical field of paints, from the producer's standpoint, air pollution becomes a problem when organic solvents generated in large quantities in the painting process or baking process are released to the environment. On the other hand, from the consumer's standpoint, when products coated in weather environments (rain, snow, mist, smog, etc.), soil or sewage that have been significantly acidified in recent years are exposed, Durability is a problem. Furthermore, when using solvent paint, it is necessary to provide a closed system that prevents the organic solvent from leaking into the atmosphere, so it is economical compared to powder paint that does not require such a large-scale equipment. It is disadvantageous. Therefore, from the viewpoint of environmental protection and resource saving, it is very effective to use a powder coating rather than a solvent coating, and the shift from solvent coating to powder coating is the trend of the times.
[0006]
However, despite the increasing demand for powder coatings from this background, the appearance characteristics of the coating film formed by thermosetting in the known powder coating technology compared to the case of solvent coating technology. (Smoothness, sharpness, etc.), physical properties (impact resistance, adhesion, scratch resistance, recoatability, etc.), weather resistance, UV resistance, and chemical properties (acid rain resistance, solvent resistance, etc.) Is a problem in that it is inferior. Among these problems, acid rain resistance, solvent resistance, and scratch resistance are particularly problems.
[0007]
Regarding the powder coating technology, for example, as disclosed in US Pat. No. 3,845,016 (Labana et al.), US Pat. No. 3,919,347 and JP-A-5-112743, etc. A thermosetting powder coating containing an acrylic polymer having a glycidyl group as a component and a dicarboxylic acid or polyvalent carboxylic acid anhydride as a curing agent component is coated on a substrate (underlying) and then thermally cured. A technique for forming a coating film on a substrate (base) is known. However, although the cured coating film obtained by these techniques has excellent appearance characteristics (smoothness), it is particularly inferior in acid rain resistance, solvent resistance, and scratch resistance.
[0008]
As another improvement technique for the purpose of solving the problems of the above-mentioned known techniques, for example, as disclosed in US Pat. No. 4,877,837 (Reising et al.), In the resin component of the powder coating composition, Research and development for surface modification of coating films has been promoted by introducing silicone compounds having reactive functional groups such as silanol groups and alkoxysilyl groups. However, since this powder coating composition contains highly reactive silanol groups and alkoxysilyl groups in the silicone compound, the storage stability of the coating is remarkably inferior.
[0009]
Japanese Patent Publication No. 3-43311 discloses a powder coating composition comprising a vinyl copolymer comprising a glycidyl group-containing vinyl monomer, a silicon-containing vinyl monomer and other monomers, and an aliphatic dibasic acid. Disclosure. The silicon-containing vinyl monomer used in this composition has a highly reactive functional group such as an alkoxysilyl group in addition to the vinyl polymerizable unsaturated double bond, and has only one silicon atom in one molecule. A compound. Although the coating film obtained from this powder coating composition is excellent in the smoothness of the coating film, it has a highly reactive functional group other than an unsaturated double bond in the silicon-containing vinyl monomer. Since the content of silicon in one molecule is small, the storage stability of the paint, the acid rain resistance and the solvent resistance of the coating film are inferior.
[0010]
Japanese Patent Publication No. 09-505847 discloses a technique relating to a powder coating suitable for car body painting, characterized by using a specific epoxide group-containing polyacrylate resin as a binder. Has been. This powder coating is formed using an epoxide group-containing polyacrylate resin obtained by polymerizing the following components (a) to (d) as a binder.
(A) 10.0 to 50.00% by weight of an ethylenically unsaturated monomer or mixture thereof containing at least one epoxide group in the molecule;
(B) an aliphatic or cycloaliphatic ester of (meth) acrylic acid or a mixture thereof from 5.00 to 84.99 wt.
(C) Statistically, at least one polymerizable ethylenically unsaturated group and at least two general formulas per molecule: (—SiR ¹ R ² -O-) [R ¹ And R ² Are the same or different, a C1-C8 aliphatic or cycloaliphatic group or an optionally substituted phenyl group. An ethylenically unsaturated compound or a mixture thereof having a structural unit of 0.01 to 4.99% by weight, and
(D) 5.0 to 84.99% by weight of an ethylenically unsaturated monomer different from a, b and c, or a mixture thereof.
[0011]
In the technology relating to the powder coating disclosed in JP-T-09-505847, an ethylenically unsaturated polysiloxane macromonomer is copolymerized with another vinyl monomer as a resin-forming component constituting the powder coating composition. Thus, a silicone-modified epoxide group-containing polyacrylate resin is produced.
[0012]
In this technique, it is essential to use an ethylenically unsaturated polysiloxane macromonomer, and in the method for producing a two-layer coating on the substrate surface using the powder coating,
(1) A colored base paint is applied to the surface of the substrate,
(2) A polymer film is formed from the paint applied in step (1),
(3) A transparent powder coating containing an epoxide group-containing polyacrylate resin as a binder is applied onto the base coating film thus obtained,
(4) Bake the base film together with the transparent powder film
It is disclosed. In this technology, although the adhesion between the base coat and the top coat is excellent when the powder paint is baked onto the base coating film, the recoat property of the top (clear) coats, that is, the powder paint is applied and baked. Correlation adhesion when a powder coating is baked onto the baked coating film is not always good.
[0013]
JP-B-3-45111 includes (A) 100 parts by weight of a thermosetting resin and (B) a glycidyl group-containing silicon-based additive having no vinyl polymerizable unsaturated bond having a number average molecular weight of 150 or more. A thermosetting resin composition comprising 0.01 to 10 parts by weight as an essential component is disclosed.
[0014]
In Japanese Patent Publication No. 4-70331, a thermosetting resin selected from the group consisting of polyester, epoxy resin and vinyl polymer or a resin-forming component thereof is used based on the weight of these resins or resin-forming components. The production of a thermosetting resin for powder coatings modified with the above silicon-containing compound, characterized by reacting a silicon compound having no vinyl polymerizable unsaturated bond in the range of 0.01 to 30% A method is disclosed.
[0015]
In the techniques disclosed in Japanese Patent Publication Nos. 3-45111 and 4-70331, the appearance (smoothness) of the coating film is excellent, but the silane compound having high reactivity in the molecule of the silicon-containing compound. Because of the use of a coating, the coating has poor storage stability (solid phase resistance), and the content of silicon in one molecule is low, so the coating has acid resistance and scratch resistance. Improvement was insufficient.
[0016]
In JP-A-9-241538, a copolymer in which an organopolysiloxane and an acrylic polymer are bonded in a graft or block form, an epoxy group, a hydroxyl group and a side chain of the acrylic polymer in the copolymer are disclosed. What is claimed is: 1. A powder coating composition comprising a silicone / acrylic-graft copolymer as a main component, which contains one or more groups selected from carboxyl groups and has a glass transition point of 45 [deg.] C. or higher. It is disclosed.
[0017]
In this technique, the following points are disclosed.
(1) A point of using a radically polymerizable polysiloxane or an organopolysiloxane having an SH group in the molecule as the organopolysiloxane and using a graft or block copolymer.
(2) The amount of the organopolysiloxane used is at least 5% by weight or more in the copolymer.
[0018]
However, when an organopolysiloxane compound is used in an amount as disclosed in this technology, the transparency and sharpness of the coating film in the case of a clear coat is reduced, and adhesion with the undercoat film of the coating film is reduced. And recoatability of top coats is inferior.
[0019]
European Patent Publication No. 275051 discloses a powder coating containing a polyacrylate resin produced by polymerizing an ethylenically unsaturated monomer in the presence of a silicone resin as a binder. However, a large amount of the silicone resin described here brings about a decrease in transparency and sharpness in the case of a clear coat, a decrease in adhesion to an undercoat film, and a recoat property between top coats.
[0020]
When the various problems described above are summarized, any of the following points (i) to (iv) is particularly problematic in the prior art relating to the thermosetting powder coating composition containing a silicone compound.
(I) Regarding the production of a coating composition or resin component, when a silicone compound is frequently used, the transparency and sharpness of the coating film are poor when it is made a clear coat, and the adhesion with the undercoat film and the recoat of the top coat film Inferior. Moreover, the apparatus used for the production of the coating composition and the resin component is significantly soiled by a large amount of the silicone compound. Furthermore, the silicone compound remaining in the apparatus has a great adverse effect on other coating compositions or resin components, and may deteriorate the appearance of the coating film.
(Ii) Regarding the formation of a coating film, the coating film is easily repelled or repelled on the substrate (underlying), so that an incomplete coating tends to be formed.
(Iii) It is difficult to achieve excellent performance at the same time with respect to coating properties such as appearance properties, physical properties, weather resistance, ultraviolet resistance, and chemical properties.
(Iv) The storage stability of the coating composition is poor.
[0021]
[Problems to be solved by the invention]
An object of the present invention is to solve the above problems (i) to (iv) in the conventional powder coating technology. Specifically, the object of the present invention is to
(I) improving compatibility during preparation of the coating composition and preventing contamination during production;
(Ii) improving the complete coverage of the coating on the substrate (base);
(Iii) Appearance characteristics (smoothness, sharpness, etc.), physical characteristics (scratch resistance, recoatability, etc.), weather resistance, UV resistance, and chemical characteristics (acid rain resistance) The coating film properties such as properties, solvent resistance, etc.), at the same time, exhibiting excellent performance, especially remarkably improving acid rain resistance, recoatability, solvent resistance, and scratch resistance, and
(Iv) Improving the storage stability of the coating composition
It is an object of the present invention to provide a thermosetting powder coating composition for a top coat that can be applied.
[0022]
[Means for Solving the Problems]
The object is to provide a monomer (a1) having at least one radical polymerizable unsaturated bond and at least one epoxy group in one molecule, and at least one radical polymerizable unsaturated in one molecule. 100 parts by weight of an acrylic copolymer (A) obtained by polymerization in a reaction system containing a monomer (a2) having a saturated bond and no epoxy group, and at least 1 in one molecule Containing 0.01 to 2.0 parts by weight of an organically modified polysiloxane (B) having one functional group and at least two silicon atoms and having no radically polymerizable unsaturated bond The component (B) is a thermosetting powder coating composition for a top coat, wherein a part or all of the component (B) reacts with and binds to the component (A) or is completely unreacted. Achieved by things.
[0023]
In contrast to the prior art, in the thermosetting powder coating composition of the present invention, the polysiloxane compound has a functional group but no radical polymerizable unsaturated bond, and the number of silicon atoms is 2. One or more organically modified polysiloxanes (B) are added in a small amount within a specific range.
[0024]
When a small amount of such organically modified polysiloxane (B) having a specific structure is used, the organically modified polysiloxane (B) is uniformly crosslinked and retained throughout the cured coating film, and as a result, a coating film having excellent characteristics can be formed. The storage stability of the paint is not impaired.
[0025]
The organically modified polysiloxane (B) having this specific structure may be contained in an unreacted state before curing the coating film, that is, at the stage of the thermosetting powder coating composition, or a part thereof. May be contained in a state of reacting with and bound to a resin component or the like. Accordingly, the content of 0.01 to 2.0 parts by weight of the organically modified polysiloxane (B) defined in the present invention indicates the total amount including the organically modified polysiloxane (B) in a bonded state.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
[Acrylic copolymer (A)]
The acrylic copolymer (A) used in the present invention includes a monomer (a1) having at least one radical polymerizable unsaturated bond and at least one epoxy group in one molecule, and one molecule. It is a copolymer obtained by polymerizing in a reaction system containing a monomer (a2) having at least one radical polymerizable unsaturated bond therein and having no epoxy group.
[0027]
[Monomer (a1)]
The monomer (a1) is not particularly limited as long as it is a monomer having at least one radical polymerizable unsaturated bond and at least one epoxy group in one molecule. The epoxy group of the monomer (a1) remains after the acrylic copolymer (A) is formed, and contributes to the curing of the coating film by crosslinking reaction with the functional group of the curing agent (C).
[0028]
Specific examples of the monomer (a1) include glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, N-glycidyl (meth) acrylic acid amide, allyl glycidyl ether, glycidyl vinyl sulfonate, and 3,4- Examples thereof include epoxycyclohexyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether. In these, glycidyl (meth) acrylate is preferable and glycidyl methacrylate is more preferable. These can be used alone or in combination of two or more.
[0029]
[Monomer (a2)]
The monomer (a2) is not particularly limited as long as it is a monomer having at least one radical polymerizable unsaturated bond in one molecule and having no epoxy group. Generally, it is preferable that the reactive functional group of the curing agent (C) does not have a reactive functional group of a kind that contributes to the curing of the coating film by a crosslinking reaction.
[0030]
As the monomer (a2), there are carboxylic acids, acid anhydrides, carboxylic acid esters, unsaturated hydrocarbons, aromatic vinyl hydrocarbons, nitriles, amides, etc. having an unsaturated double bond. Can be mentioned. In these, the carboxylic acid ester which has a radically polymerizable unsaturated double bond is preferable.
[0031]
Specific examples of such a monomer (a2) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl. (Meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, 2-ethyloctyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) (Meth) acrylic acid derivatives such as acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, dimethylamino (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate; Esters of dicarboxylic acids such as oleic acid, fumaric acid, itaconic acid; amides such as (meth) acrylamide; α, β-unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid and maleic anhydride, or anhydrides thereof And the like. These can be used alone or in combination of two or more.
[0032]
Other specific examples of the monomer (a2) include aromatic vinyl hydrocarbons such as styrene, α-methylstyrene and vinyltoluene; halogenation such as vinyl chloride, vinylidene chloride, vinyl fluoride and monochlorotrifluoroethylene. Ethylenically unsaturated monomers; Nitriles such as (meth) acrylonitrile; Aliphatic vinyl esters such as vinyl acetate; Ethylene, propylene, α-olefins such as C 4-20 α-olefins; Alkyls such as lauryl vinyl ether And unsaturated monomers such as vinyl ether. These can be used alone or in combination of two or more.
[0033]
Monomers (a1) and (a2) are used in an amount of 15 to 60 parts by weight of monomer (a1) and 100 parts by weight of monomer (a1) and monomer (a2). The monomer (a2) is preferably 40 to 85 parts by weight, more preferably 20 to 55 parts by weight of the monomer (a1) and 45 to 80 parts by weight of the monomer (a2). The use of the monomer (a1) in an amount equal to or more than the above-mentioned specific amount (preferably 15 parts by weight, more preferably 20 parts by weight) is particularly the acid rain resistance and scratch resistance of the obtained coating film. And better results in solvent resistance and the like. On the other hand, using the monomer (a1) in an amount equal to or less than the above-mentioned specific amount (preferably 60 parts by weight, more preferably 55 parts by weight) means that the obtained coating film has smoothness, sharpness, and It provides better results in the storage stability of the coating composition.
[0034]
It is preferable that 39-55 weight part is (meth) acrylic acid ester which has a C1-C12 alkyl group and / or a cyclohexyl group among 40-85 weight part of monomers (a2). Use of such a (meth) acrylic acid ester in an amount within the above range brings about a better result in terms of the hardness and weather resistance of the coating film.
[0035]
When styrene is used as a part of the monomer (a2), the amount is preferably 1 to 30 parts by weight with respect to 100 parts by weight of the monomer (a1) and the monomer (a2) in total. 10-20 weight part is still more preferable. In this case, the total amount of the monomer (a2) is preferably 40 to 85 parts by weight, and more preferably 50 to 80 parts by weight. The advantage of using styrene as a part of the monomer (a2) is that it can impart further excellent gloss and smoothness to the coating film. Furthermore, the use of styrene in an amount not more than the above-mentioned specific amount (desirably 30 parts by weight, preferably 20 parts by weight) leads to better results in prevention of yellowing of the coating film obtained, weather resistance, etc. .
[0036]
In general, when a small amount of conjugated dienes such as butadiene, nitriles such as acrylonitrile, or amides such as acrylamide is used as the monomer (a2), problems arise in terms of coating coloration and weather resistance. In the case where a small amount of a monomer having a group capable of reacting with an epoxy group such as a carboxyl group, an acid anhydride group or an amino group is used in the molecule, an acrylic copolymer component (A ) Tends to cause no problem in terms of gelation. Therefore, these monomers are used in small amounts [for example, 5 parts by weight or less based on the total weight of the monomer (a1) and the monomer (a2)] and used in combination with the other monomers (a2). It is preferable.
[0037]
In general, the acrylic copolymer (A) is preferably adjusted so that its glass transition point (Tg) is in the range of 30 to 100 ° C. The use of the acrylic copolymer (A) having a Tg of 30 ° C. or higher usually gives more excellent results in the storage stability of the coating composition. On the other hand, using an acrylic copolymer (A) having a Tg of 100 ° C. or lower usually prevents a decrease in heat fluidity, resulting in appearance characteristics such as smoothness of the resulting coating film, etc. Give better results.
[0038]
Tg of this acrylic copolymer (A) can be calculated by Fox's formula. Here, the Fox formula is for calculating the Tg of the copolymer based on the Tg of the homopolymer of the monomer for each monomer forming the copolymer, The details thereof are described in Bulletin of the American Physical Society, Series 2 (Volume of the American Physical Society, Series 2) Vol. 1, No. 3, p. 123 (1956).
[0039]
The Tg of various ethylenically unsaturated monomers, which are the basis for evaluating the Tg of copolymers according to the Fox formula, is, for example, Shin Polymer Library, Volume 7, Introduction to Synthetic Resins for Paints (Kyozo Kitaoka) , Kobunshi Shuppankai, Kyoto, 1974) The values described in Table 10-2 (main raw material monomers for acrylic resins for paints) on pages 168 to 169 can be employed.
[0040]
All the descriptions are made a part of the disclosure of the present application specification by specifying the cited references and the reference range, and in view of the matters or disclosure described in the specification of the present application by referring to the specified reference range. Matters or disclosure that can be derived directly and unambiguously by the contractor.
[0041]
The number average molecular weight (Mn) of the acrylic copolymer (A) is preferably 1,000 to 10,000, and more preferably 1,500 to 4,000. The use of the acrylic copolymer (A) having Mn equal to or higher than the above-mentioned specific value (preferably 1,000, more preferably 1,500) gives more excellent results in the storage stability of the coating composition. Bring. On the other hand, the use of the acrylic copolymer (A) having Mn equal to or less than the above-mentioned specific value (preferably 10,000, more preferably 4,000) makes it possible to obtain appearance characteristics such as smoothness of the resulting coating film Give better results. The Mn of the acrylic copolymer (A) can be measured by GPC using, for example, polystyrene as a standard.
[0042]
The acrylic copolymer (A) can be prepared by radical polymerization methods such as a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method. In particular, the solution polymerization method is suitable.
[0043]
As a method for adjusting the molecular weight of the acrylic copolymer (A), mercaptans such as dodecyl mercaptan, disulfides such as dibenzoyl sulfide, and thioglycolic acid such as 2-ethylhexyl thioglycolate having 1 to 18 carbon atoms. Use means such as polymerization in the presence of alkyl ester, chain transfer agent of halogenated hydrocarbons such as carbon tetrabromide; organic solvent having a large chain transfer effect such as isopropyl alcohol, isopropylbenzene, toluene, etc. be able to.
[0044]
In the present invention, an organically modified polysiloxane (B) is added to the acrylic copolymer (A) by adding an organically modified polysiloxane (B) described later during the production process of the acrylic copolymer (A). ) In advance can be obtained. As a method for producing this organically modified polysiloxane-containing acrylic copolymer component, for example,
(1) The organically modified polysiloxane (B) is dissolved in the monomer component in advance, and bulk polymerization or solution polymerization is performed. In the case of solution polymerization, the organic solvent is removed after polymerization.
(2) After performing solution polymerization with an organic solvent, when removing the solvent, the organic modified polysiloxane (B) is added and uniformly dispersed, and then the organic solvent is removed.
And the like. However, during the production process of the acrylic copolymer (A), for example, the organically modified polysiloxane (B) having a reactive functional group capable of reacting with the epoxy group of the acrylic copolymer (A) is added. In this case, it is necessary to appropriately select the type, functional group amount, molecular weight, and the like of the reactive functional group of the organically modified polysiloxane (B) so that an undesirable gel is not generated during the production process.
[0045]
[Organic modified polysiloxane (B)]
The organically modified polysiloxane (B) is an organically modified polysiloxane having at least one functional group and at least two silicon atoms in one molecule and having no radically polymerizable unsaturated bond. If there is, there is no particular limitation. Specifically, this functional group is a group reactive to the acrylic copolymer (A) or the curing agent (C).
[0046]
The organically modified polysiloxane (B) has the following general formulas (I), (II), (III) and (IV)
[0047]
Embedded image

[In formula (1), X ¹ And X ² Are the following general formulas (a) to (f)
[0048]
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(In the formulas (a) to (f), Ra, Rb, Rc, Rd and Re are a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or an ether bond. And / or a hydrocarbon group having an ester bond, and Rf represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or a derivative thereof.)
A group represented by any one of the formulas: ¹ And R ² Represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group or a derivative thereof; ^Three ~ R ⁸ Represents an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof, and n1 represents a number of 1 to 1,500. ]
[0049]
Embedded image

[In the formula (II), X ^Three Is a group represented by any one of the general formulas (a) to (e), and R ⁹ ~ R ¹⁵ Represents an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof; ¹⁶ Represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or a hydrocarbon group having an ether bond and / or an ester bond, and n2 is 1 to 1,500. Represents the number of ]
[0050]
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[In the formula (III), X ^Four Is a group represented by any one of the general formulas (a) to (e), and R ¹⁷ ~ R ^{twenty five} Represents an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof; ²⁶ Represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or a hydrocarbon group having an ether bond and / or an ester bond, and x1 represents 1 to 1,300. Y1 represents a number from 1 to 200. ]
[0051]
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[In formula (IV), X ^Five , X ⁶ And X ⁷ Is a group represented by any one of the general formulas (a) to (e), and R ³⁰ ~ R ³⁶ Represents an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof; ²⁷ ~ R ²⁹ Represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or a hydrocarbon group having an ether bond and / or an ester bond, and x2 represents 1 to 1,300. Y2 represents a number from 1 to 200. ]
Of these, at least one compound represented by any one of the formulas is preferred. More specifically, the organically modified polysiloxane (B) has the following general formulas (V) to (XXVIII):
[0052]
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[0053]
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[0054]
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[0055]
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[0056]
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[0057]
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[0058]
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(In the formulas (V) to (XXVIII), each R is independently a direct bond, an alkylene group having 1 to 20 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or an ether bond and / or an ester. Each represents independently a number of 1 to 1,500, each x independently represents a number 1 to 1,300, and each y independently represents a number 1 to 200. .)
Of these, a compound represented by any one of the formulas is more preferred.
[0059]
R in general formula (I) ^Three ~ R ⁸ R of general formula (II) ⁹ ~ R ¹⁵ R of general formula (III) ¹⁷ ~ R ^{twenty five} And R in the general formula (IV) ³⁰ ~ R ³⁶ Is a hydrocarbon group including an alkyl group having 1 to 8 carbon atoms, a phenyl group, or a derivative thereof. As these, a phenyl group and a methyl group are preferable, and a methyl group is more preferable.
[0060]
The range of the number of repeating units (n1, n2, x1 + y1, x2 + y2) in each of the general formulas (I) to (IV) is as defined in each formula, and the lower limit of the range is 10 Is preferable, 100 is more preferable, and 500 is particularly preferable.
[0061]
The epoxy equivalent of the organically modified polysiloxane of the general formulas (V) to (XII) is preferably 200 to 5,000. Moreover, it is preferable that the carboxyl equivalents of the organically modified polysiloxanes of the general formulas (XIII) to (XVI) are 500 to 5,000. Moreover, it is preferable that -OH equivalent of the organic modified polysiloxane of general formula (XVII)-(XX) is 1,000-5,000. In addition, —NH of the organically modified polysiloxane of the general formulas (XXI) to (XXVIII) ₂ The equivalent is preferably 500 to 10,000.
[0062]
Examples of commercially available organically modified polysiloxane (B) represented by the general formula (I) include X ¹ And X ² Are groups represented by the general formula (a), BY16-855, BY16-855B (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), KF-105, X-22-163A, X-22- Examples thereof include both-end epoxy-modified dimethylpolysiloxanes such as 163B, X-22-163C (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).
[0063]
For example, X ¹ And X ² Is a group represented by the general formula (b), and both terminal alicyclic epoxy-modified dimethylpolysiloxanes such as X-22-169AS and X-22-169B (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) Can be mentioned.
[0064]
For example, X ¹ And X ² Is a group represented by the general formula (c), BY16-750 (above, manufactured by Toray Dow Corning Silicone Co., Ltd., trade name), X-22-162A, X-22-162C (above, Shin-Etsu Chemical Co., Ltd.) And both-end carboxyl-modified dimethylpolysiloxanes manufactured by the company and trade names).
[0065]
For example, X ¹ And X ² Is a group represented by the general formula (d), BY16-752 (above, product name, manufactured by Toray Dow Corning Silicone Co., Ltd.), X-22-169B (above, product name, manufactured by Shin-Etsu Chemical Co., Ltd.) And both-end phenol-modified dimethylpolysiloxane.
[0066]
For example, X ¹ And X ² Are groups represented by the general formula (e), BY16-853, BY16-853B (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), X-22-161AS, X-22-161A, X- Examples include 22-161B, KF-8012 (above, Shin-Etsu Chemical Co., Ltd., trade name) and the like, both-end amino-modified dimethylpolysiloxane.
[0067]
Examples of commercially available organically modified polysiloxane (B) represented by the general formula (II) include X ^Three Is a one-terminal epoxy-modified dimethylpolysiloxane such as X-22-173DX (above, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), which is a group represented by the general formula (a).
[0068]
Examples of commercially available organically modified polysiloxane (B) represented by the general formula (III) include X ^Four Is a group represented by the general formula (a), SF8411, SF8413 (above, manufactured by Toray Dow Corning Silicone Co., Ltd., trade name), KF-1001, KF-101 (above, manufactured by Shin-Etsu Chemical Co., Ltd., product) Side chain epoxy-modified dimethylpolysiloxane.
[0069]
For example, X ^Four Is a group represented by the general formula (b), such as BY16-839 (above, Toray Dow Corning Silicone Co., Ltd., trade name), KF-102 (above, Shin-Etsu Chemical Co., Ltd., trade name), etc. A side chain alicyclic epoxy-modified dimethylpolysiloxane may be mentioned.
[0070]
For example, X ^Four Is a group represented by the general formula (c), such as SF8418 (above, product name, manufactured by Toray Dow Corning Silicone Co., Ltd.), X-22-3701E (above, product name, manufactured by Shin-Etsu Chemical Co., Ltd.), etc. A side chain carboxyl-modified dimethylpolysiloxane may be mentioned.
[0071]
For example, X ^Four Is a group represented by the general formula (e), for example, BY16-828, BY16-859 (above, Toray Dow Corning Silicone Co., Ltd., trade name), KF-864, KF-865, KF-868, Examples include side chain amino-modified dimethylpolysiloxane such as KF8003 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).
[0072]
The weight average molecular weight of the organically modified polysiloxane (B) is usually preferably from 500 to 100,000, more preferably from 1,000 to 90,000. When the weight average molecular weight of the organically modified polysiloxane (B) is in the above range, the appearance of the resulting coating film is good, and the scratch resistance, acid resistance, and recoatability are good.
[0073]
[Action mechanism of organically modified polysiloxane (B)]
The effects of the organically modified polysiloxane (B) in the thermosetting powder coating composition used in the present invention are presumed to be as follows.
[0074]
When the reactive functional group in the organic modified polysiloxane (B) reacts with the reactive functional group of the acrylic copolymer (A) or the curing agent (C) by heating, the organic modified polysiloxane (B) becomes Due to the properties of the polysiloxane that are uniformly retained in the cured coating film, it is possible to form a crosslinked coating film that is particularly excellent in solvent resistance, acid resistance, and scratch resistance. In addition, since the organically modified polysiloxane (B) is incorporated into the three-dimensional network structure by heat curing, compatibility is maintained and the polysiloxane skeleton is prevented from being extremely localized on the coating film surface.
[0075]
In addition, the reactive functional group in the organically modified polysiloxane (B) undergoes a crosslinking reaction with the acrylic copolymer (A) or the curing agent (C) at the time of temperature increase during baking, so that a three-dimensional network structure is obtained. When taken in, internal plasticization occurs, the melt viscosity of the paint is lowered, and the smoothness of the coating film is also improved.
[0076]
When a polysiloxane having no functional group capable of reacting with the reactive functional group of the acrylic copolymer (A) or the curing agent (C) is used, the polysiloxane is selected from the acrylic copolymer (A) and Since it does not have a reactive group capable of crosslinking with the curing agent (C), the compatibility with the acrylic copolymer (A) and the curing agent (C) at the time of heat curing is insufficient, and the resulting coating film Although it is excellent in acid resistance, the appearance (transparency, smoothness), solvent resistance and recoatability in the case of a clear coating film are lowered, making it difficult to balance.
[0077]
[Amount of use of organically modified polysiloxane (B)]
The amount of the organically modified polysiloxane (B) used in the present invention is 0.01 to 2.0 parts by weight based on 100 parts by weight of the acrylic copolymer (A). When the amount used exceeds 2.0 parts by weight, the coating film becomes cloudy and there is a tendency for transparency and sharpness to deteriorate. Moreover, if this usage-amount is less than 0.01 weight part, the improvement of the acid resistance of the coating film obtained and abrasion resistance will become inadequate. The amount used is more preferably 0.01 to 1.0 part by weight.
[0078]
[Curing agent (C)]
The curing agent (C) used in the present invention is composed of at least one polycarboxylic acid compound selected from the group consisting of polyvalent carboxylic acid (c1) and polyvalent carboxylic acid anhydride (c2). It is preferable. Hereinafter, examples of the polyvalent carboxylic acid (c1) and the polyvalent carboxylic acid anhydride (c2) will be described.
[0079]
[Polyvalent carboxylic acid (c1)]
As the polyvalent carboxylic acid (c1), any of aliphatic, aromatic and alicyclic compounds can be used. Specific examples of the aromatic polyvalent carboxylic acid include isophthalic acid and trimellitic acid, and these can be used alone or in combination. Specific examples of the alicyclic polyvalent carboxylic acid include, for example, hexahydrophthalic acid and tetrahydrophthalic acid, and these can be used alone or in combination. Moreover, the polyester resin etc. which have a carboxyl group can also be used.
[0080]
However, in the present invention, it is preferable to use an aliphatic polyvalent carboxylic acid from the viewpoint of coating properties such as smoothness and weather resistance.
[0081]
The term “aliphatic” used in the present specification includes not only an aliphatic group in a narrow sense but also an alicyclic group having a substantially low degree of aromaticity. That is, the concept of the term “aliphatic” compound includes a group consisting of compounds having a divalent hydrocarbon group containing at least one carbon atom in the molecule and having a substantially low degree of aromaticity. Specifically, not only in a narrowly defined aliphatic group, but also in an alicyclic group having a substantially low degree of aromaticity, a group in which these are combined, or a group such as a hydroxyl group, nitrogen, sulfur, silicon, or phosphorus. It also includes a group consisting of compounds having a divalent residue in the molecule, such as an alkyl group, a cycloalkyl group, an allyl group, an alkoxyl group, a cyclo group. It also includes a group consisting of compounds having in the molecule a group substituted by an alkoxyl group, an allyloxyl group, a halogen (F, Cl, Br, etc.) group or the like. By appropriately selecting these substituents, various properties (heat resistance, toughness, decomposability, strength properties, etc.) of the copolymer used in the present invention can be controlled. The term “aliphatic” compound used herein includes not only one type of compound but also a combination of two or more types.
[0082]
Hereinafter, examples of the aliphatic polyvalent carboxylic acid will be described.
[0083]
The aliphatic polyvalent carboxylic acid is not particularly limited as long as it is an aliphatic compound having at least two carboxyl groups in the molecule, and one kind or two or more kinds can be used. In particular, an aliphatic dicarboxylic acid having 8 to 20 carbon atoms is preferred.
[0084]
Specific examples of the aliphatic polycarboxylic acid include aliphatic dicarboxylic acid. Specific examples of the aliphatic dicarboxylic acid include, for example, sebacic acid, undecane diacid, dodecane diacid, brassic acid, eicosane diacid, octadecane diacid, and the like. Among these, sebacic acid, dodecanedioic acid, Brassic acid and eicosane diacid are preferable, and dodecanedioic acid is more preferable. These can be used alone or in combination.
[0085]
Regarding the coating film properties such as smoothness, impact resistance, and weather resistance, the coating film properties of the alicyclic polyvalent carboxylic acid deteriorate as the degree of aromaticity increases.
[0086]
[Polyhydric carboxylic acid anhydride (c2)]
As used herein, the terms “anhydride”, “anhydride group”, “anhydride bond” and “polyanhydride” include the term “MARUZEN Macromolecule Dictionary-Concise Encyclopedia of PolymerScience and Engineering (edited by Kroschida et al. , Maruzen, Tokyo, 1994) ”and the concept relating to each word described in“ Polyanhydride ”on pages 996-998. As used herein, the terms “anhydride” and “anhydride” are equivalent to each other, and the term “anhydride” or “anhydride” used in the specification of the present application includes And the concept described in the section of “Acid Anhydride” described in Chemistry Dictionary, Volume 3 (published by Kyoritsu Shuppan, 1963), page 996, left column to page 997, right column.
[0087]
In the present invention, a linear aliphatic polyvalent carboxylic acid anhydride is preferable from the viewpoint of the bridging effect and the like. Hereinafter, examples of the aliphatic polycarboxylic acid anhydride will be described.
[0088]
The aliphatic polycarboxylic anhydride is substantially a linear dimeric or higher oligo- or poly-aliphatic acid anhydride (anhydride) with or without a carboxyl group in the molecule. The compound is not particularly limited as long as it is a compound having at least two carboxyl groups and / or acid anhydride (anhydride) groups substantially present in the molecule, and one kind or two or more kinds can be used.
[0089]
In the present specification, the term “linear” includes not only linear, but also linear or dimeric oligo- or poly-aliphatic acid anhydrides (anhydrides) that have the same effect as linear. The case where the macrocycle which plays is formed is also included.
[0090]
Specific examples of the aliphatic polycarboxylic acid anhydride include linear polycondensates obtained by dehydration condensation of one or more aliphatic dicarboxylic acids. For example, a certain type of linear polycondensate obtained by dehydration condensation of one kind of aliphatic polyvalent carboxylic acid can be represented by the following general formula.
[0091]
HO- [OC (CH ₂ ) MCOO] n-H
Here, m is a natural number of 1 or more and n is 2 or more, preferably m is 30 or less.
[0092]
Specific examples of the linear acid anhydride (c2) of the aliphatic dicarboxylic acid include, for example, a dehydrated linear condensate of the aliphatic polycarboxylic acid (c1). Among these, a linear dimer or more oligo- or poly-derivative derived from dehydration condensation of at least one compound selected from the group consisting of sebacic acid, dodecanedioic acid, brassic acid, and eicosane diacid. An acid anhydride is preferable, and a dehydrated linear condensate of dodecanedioic acid is more preferable.
[0093]
Other specific examples of the polyvalent carboxylic acid anhydride (c2) include, for example, polyisocyanate-modified dicarboxylic acid (poly) anhydride described in European Patent Publication No. 695,771 and European Patent Publication No. 299,420. Modified polyanhydrides such as the polyol-modified polymeric polyanhydrides described can also be suitably used.
[0094]
As the polyvalent carboxylic acid anhydride (c2), a commercially available polyvalent carboxylic acid anhydride can also be suitably used. Specific examples of these commercially available polyvalent carboxylic acid anhydrides include, for example, trade name “Additol VXL1381” manufactured by Fianovalerine, trade name “PS-AH” manufactured by Okamura Oil Co., Ltd., and the like.
[0095]
The polyvalent carboxylic acid anhydride (c2) is preferably adjusted so that the melting point is in the range of 40 to 170 ° C. When the melting point of the polyvalent carboxylic acid anhydride (c2) is in the above range, the coating film appearance is good and the blocking property of the powder coating is good.
[0096]
[Crosslink formation by aliphatic dicarboxylic acid anhydride]
When a cyclic anhydride of a polycarboxylic acid such as succinic anhydride or phthalic anhydride is reacted with an epoxy group in the acrylic copolymer (A), the anhydride is converted into a specific glycidyl group in the molecule. Since the probability of reacting only with the epoxy ring is high, the effect of bridging the plurality of acrylic copolymer (A) molecules is small.
[0097]
On the other hand, when a (co) polycondensate of an aliphatic dicarboxylic acid is reacted with an epoxy group, the condensate is cleaved at an hydride group portion into a plurality of fragments, each of which is a separate acrylic copolymer ( A) Since it reacts with the epoxy group in the molecule and bridges the plurality of acrylic copolymer (A) molecules, chemical properties such as solvent resistance and acid resistance of the coating are improved. .
[0098]
[Amount of curing agent (C)]
The amount of the curing agent (C) used is preferably 5 to 60 parts by weight and more preferably 15 to 50 parts by weight based on 100 parts by weight of the acrylic copolymer (A).
[0099]
Moreover, as an equivalent ratio, the functional group (carboxyl group and / or acid anhydride group etc.) of the curing agent (C) capable of crosslinking reaction is 0 with respect to 1 equivalent of the epoxy group of the acrylic copolymer (A). It is preferably 0.5 to 1.5 equivalents, and more preferably 0.7 to 1.2 equivalents.
[0100]
By setting the use amount of the curing agent (C) and the equivalent ratio of the functional groups within these ranges, properties such as the appearance of the coating film, solvent resistance, and scratch resistance can be improved.
[0101]
[Melting point of curing agent (C)]
It is preferable that melting | fusing point of a hardening | curing agent (C) is 40-170 degreeC. The use of the curing agent (C) having a melting point of 40 ° C. or higher brings more excellent results in the storage stability of the powder coating material. On the other hand, the use of the curing agent (C) having a melting point of 170 ° C. or lower brings about more excellent results in the heat fluidity during baking of the paint, the smoothness of the resulting coating film, and the like.
[0102]
[Additive]
Various additives that are usually added to paints can be added to the powder coating composition of the present invention.
[0103]
That is, in the powder coating composition of the present invention, a natural resin or a semi-synthetic material including a synthetic resin composition including an epoxy resin, a polyester resin, a polyamide, or the like, a fiber element or a fiber element derivative, as appropriate, depending on the purpose A resin composition can be blended to improve the appearance or physical properties of the coating film.
[0104]
Furthermore, the powder coating composition of the present invention includes a curing catalyst, a pigment, a flow modifier, a thixotropic agent (thixotropic modifier), a charge modifier, a surface modifier, a gloss imparting agent, and an antiblocking agent, depending on the purpose. You may mix | blend additives, such as an agent, a plasticizer, a ultraviolet absorber, a wax inhibitor (degassing agent), a coloring inhibitor, and antioxidant. Moreover, when using as a clear coat, you may mix | blend a small amount of pigment and may color to such an extent that perfect concealment property is not expressed.
[0105]
The “powder coating composition” generally refers to a composition containing a curing agent (C) and used as a powder coating itself, but the “powder coating composition” of the present invention is not limited thereto. The meaning of the resin component material for the powder coating material before the addition of the curing agent (C) is also included.
[0106]
The method for producing the powder coating composition of the present invention (composition method of composition) comprises an acrylic copolymer (A), an organically modified polysiloxane (B), and optionally a curing agent (C). The method is not particularly limited as long as it can be blended so as to obtain a desired ratio, and a publicly known or publicly used method can be adopted. Further, in order to improve the dispersibility of the organically modified polysiloxane (B), the organically modified polysiloxane (B) is melted in the acrylic copolymer (A) or the curing agent (C) and uniformly dispersed in advance. A method can also be adopted.
[0107]
Specific examples of the method for producing the powder coating composition of the present invention include a roll machine, a kneader machine, a mixer (Banbury type, transfer type, etc.), a calendar facility, and a kneading machine such as an extruder as appropriate. Examples of the method include setting the process conditions (temperature, melting or non-melting, rotation speed, vacuum atmosphere, inert gas atmosphere, etc.) as appropriate and mixing them sufficiently uniformly. Thereafter, a powder coating in a uniform fine powder state can be obtained using a pulverizer or the like. However, the present invention is not limited to these.
[0108]
Furthermore, as an aspect of the blending and kneading step of adding an additive or the like to the powder coating composition of the present invention, the acrylic copolymer (A), the organically modified polysiloxane (B) and the curing agent (C) are necessary. Depending on the case, additives such as antiblocking agents, surface modifiers, plasticizers, charge modifiers, pigments, fillers, extenders, etc. are added, preferably in the range of 40 to 130 ° C, more preferably in the range of 60 to 130 ° C. If the mixture is sufficiently melt-kneaded by a kneader and cooled, the powder coating composition of the present invention in which the additive is blended can be obtained. Then, if it grind | pulverizes uniformly to a suitable particle size (usually 150 mesh or less), the powder coating material of a fine powder state will be obtained. As this melt-kneading apparatus, a heating roll machine, a heating kneader, an extruder (extruder), etc. can be used normally.
[0109]
As a specific example of a method for applying a thermosetting powder coating comprising the composition of the present invention, for example, the thermosetting powder coating is applied to an object by a coating method such as electrostatic coating or fluidized immersion. The method of making it adhere and heating and heat-curing and forming a coating film is mentioned. The baking for the thermosetting is usually performed at a temperature of about 100 ° C. to about 200 ° C., preferably about 120 ° C. to about 180 ° C., usually for about 10 to about 60 minutes. By this baking, the acrylic copolymer (A), the organically modified polysiloxane (B), and the curing agent (C) undergo a crosslinking reaction. After this baking, if it cools to room temperature, the cured coating film which has the outstanding characteristic will be obtained.
[0110]
Since the thermosetting powder coating composition of the present invention has excellent characteristics as described above, it is very useful for top coat applications such as automobile bodies or automobile parts. In particular, a method for overcoating an automobile body or an automobile part with a thermosetting powder coating comprising the composition of the present invention, comprising the composition of the present invention on a primer coating with a pigmented or metallic aqueous coating. It is very useful in a method of forming a coating film in which a thermosetting powder coating is electrostatically applied as a top coating and the undercoat and the top coating are baked simultaneously.
[0111]
[Concept of the word “derivative”]
The concept of the term “derivative” as used in the claims and specification of the present application includes those in which a hydrogen atom of a specific compound is replaced by another atom or atomic group Z.
[0112]
Here, Z is a monovalent hydrocarbon group containing at least one carbon atom, more specifically, an aliphatic group, an alicyclic group having a substantially low degree of aromaticity, a group obtained by combining these, Alternatively, it may be a residue bonded with a hydroxyl group, a carboxyl group, an amino group, nitrogen, sulfur silicon, phosphorus, or the like, and among these, in particular, those having a strictly aliphatic structure are preferable. . Z is a group obtained by substituting, for example, a hydroxyl group, an alkyl group, a cycloalkyl group, an allyl group, an alkoxyl group, a cycloalkoxyl group, an allyloxyl group, a halogen (F, Cl, Br, etc.) group or the like. May be.
[0113]
By appropriately selecting these substituents, various properties of the coating film formed from the powder coating composition of the present invention can be controlled.
[0114]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, which are intended to assist the understanding of the contents of the present invention. It is not limited at all. Further, “parts” and “%” used in the following description mean “parts by weight” and “% by weight”, respectively, unless otherwise specified.
[0115]
[Production Examples 1 to 4: Production of acrylic copolymer]
First, xylene as an organic solvent was charged into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube, and the temperature was raised to the reflux temperature while stirring. The amount of xylene charged was equivalent to 66.7 parts of the total weight of monomers charged later. Next, while maintaining the system at the reflux temperature and stirring, t-butyl-peroxy-2-ethylhexanoate (trade name: Perbutyl O, manufactured by NOF Corporation) as a radical polymerization initiator for the monomers shown in Table 1 Was dissolved in the amount shown in Table 1, and the mixed solution was added dropwise over 5 hours. Thereafter, 0.5 part by weight of perbutyl O was added dropwise, and the mixture was held at 100 ° C. for 5 hours. A solid acrylic copolymer (Production Examples 1 to 4) was obtained by removing the solvent of the obtained polymerization solution under heating and reduced pressure. The physical properties of the obtained acrylic copolymers (Production Examples 1 to 4) were analyzed by the following method, and the results are shown in Table 1.
(1) Glass transition temperature (Tg):
Based on the monomer composition, it was calculated by the Fox equation.
(2) Number average molecular weight (Mn):
Measured by GPC using polystyrene as a standard.
[0116]
[Production Example 5: Production of acrylic copolymer]
As a monomer component, 0.1 part by weight of a polydimethylsiloxane macromonomer (manufactured by Toa Gosei Co., Ltd., trade name silicone macromonomer AK-30) is copolymerized together with the monomer (a1) and the monomer (a2). A solid acrylic copolymer (Production Example 5) in which a silicone macromonomer was copolymerized was obtained in the same manner as in Production Example 1 except for the above.
[0117]
[Production Example 6: Production of acrylic copolymer]
Except for copolymerizing 0.1 part by weight of γ-methacryloxypropyltrimethoxysilane together with monomer (a1) and monomer (a2) as a monomer component, the same procedure as in Production Example 1 Thus, a solid acrylic copolymer (Production Example 6) in which a silicone monomer was copolymerized was obtained.
[0118]
[Production Example 7: Production of organic-modified polysiloxane-containing acrylic copolymer]
Into a reactor similar to that used in Production Example 1, 66.7 parts by weight of xylene as an organic solvent was charged, and X-22-163A (both ends epoxy-modified dimethylpolysiloxane, 0.1 parts by weight of an epoxy equivalent of 950 g / eq. (Manufactured by Shin-Etsu Chemical Co., Ltd., trade name) was added, and the temperature was raised to the reflux temperature while stirring.
[0119]
Next, while maintaining the system at the reflux temperature and stirring, 5.0 parts by weight of perbutyl O was dissolved in the monomers shown in Table 1, and the mixed solution was added dropwise over 5 hours. 0.5 parts by weight of the solution was added dropwise, and the mixture was kept at 100 ° C. for 5 hours. By removing the solvent of the obtained polymerization solution under heating and reduced pressure, a solid organically modified polysiloxane-containing acrylic copolymer (Production Example 7) having a number average molecular weight of 2800 was obtained.
[0120]
[Production Example 8: Production of organically modified polysiloxane-containing acrylic copolymer]
100 parts by weight of xylene was charged into a reactor similar to that used in Production Example 1, 100 parts by weight of the acrylic copolymer obtained in Production Example 1 was added, and the mixture was heated to 100 ° C. with stirring. After uniformly dissolving, KF-8012 (both terminal amino-modified dimethylpolysiloxane, —NH) is further added as an organically modified polysiloxane (B). ₂ 0.1 part by weight of an equivalent of 2,300 g / eq. (Trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, the temperature was raised to the reflux temperature while stirring, and the organically modified polysiloxane was uniformly dispersed.
[0121]
Subsequently, the solvent of the obtained resin solution was removed under heating and reduced pressure to obtain a solid acrylic copolymer (Production Example 8) having a number average molecular weight of 2900 and modified with an organically modified polysiloxane.
[0122]
[Production Example 9: Production of acrylic copolymer modified with silane compound]
In a reactor similar to that used in Production Example 1, 100 parts by weight of xylene was charged, and 100 parts by weight of the acrylic copolymer obtained in Production Example 1 was added and heated to 100 ° C. with stirring. After uniformly dissolving, 0.1 part by weight of γ-aminopropyltrimethoxysilane was further added, and the temperature was raised to the reflux temperature while stirring to uniformly disperse γ-aminopropyltrimethoxysilane. Subsequently, the solvent of the obtained resin solution is removed by heating under reduced pressure to obtain a solid acrylic copolymer (Production Example 9) having a number average molecular weight of 2800 and containing γ-aminopropyltrimethoxysilane. It was.
[0123]
[Production Example 10: Production of dodecanedioic acid linear acid anhydride (c2)]
Dodecanedioic acid and acetic anhydride (molar ratio = 1: 0.8) are charged into the reactor and heated to 150 ° C., and the system is produced while reducing or vacuuming the system so that acetic anhydride does not flow out of the system. Acetic acid was removed and reacted for 5 hours. Upon cooling immediately after completion of the reaction, a white solid [dodecanedioic acid linear acid anhydride (Production Example 10)] was obtained. The melting point of this compound was about 73 to about 82 ° C.
[0124]
[Examples 1 to 14]
The acrylic copolymer (A), organically modified polysiloxane (B), and curing agent (C) produced in Production Examples 1 to 4 were blended at a weight ratio shown in Table 2 [of the curing agent (C). TINUVIN 144 (manufactured by Ciba Specialty Chemicals Co., Ltd.) for a total of 100 parts of functional group / epoxy group in acrylic copolymer (A) = 1/1], acrylic copolymer (A) and curing agent (C) , Brand name, light stabilizer), 1 part by weight of benzoin (anti-cracking agent) each, 2 parts by weight of TINUVIN 900 (manufactured by Ciba Specialty Chemicals Co., Ltd., UV absorber), tin octoate (trademark only for Examples 12-14) The name Neostan U-28, a curing catalyst, manufactured by Nitto Kasei Co., Ltd.) was added in an amount of 0.3 parts by weight. After the above mixture was uniformly dry blended using a Henschel mixer, a biaxial extruder PCM-30 (manufactured by Ikekai Machine Sales Co., Ltd.) was used, the cylinder temperature was set to 110 ° C., and the screw rotation speed was set to 200 rpm. Repeated kneading (2 passes) was performed. The melt-kneaded product was cooled and then finely pulverized by a pulverizer, and the sections that passed through a 150-mesh sieve were collected to obtain thermosetting powder coating materials (Examples 1 to 14).
[0125]
[Examples 15 and 16]
Except that the organic-modified polysiloxane-containing acrylic copolymer obtained in Production Examples 7 and 8 and the curing agent (C) were blended in the blending ratio shown in Table 2, heat was applied in the same manner as in Example 1. A curable powder coating material (Examples 15 and 16) was obtained.
[0126]
[Comparative Example 1]
A thermosetting powder coating material (Comparative Example 1) was obtained in the same manner as in Example 1 except that the organically modified polysiloxane was not used.
[0127]
[Comparative Example 2]
A thermosetting powder coating material (Comparative Example 2) was obtained in the same manner as in Example 2 except that the organically modified polysiloxane was not used.
[0128]
[Comparative Example 3]
A thermosetting powder coating material (Comparative Example 3) is obtained in the same manner as Comparative Example 1 except that 1 part by weight of Resimix RL-4 (trade name, manufactured by Mitsui Chemicals, Inc.) is added as a flow modifier. It was.
[0129]
[Comparative Example 4]
A thermosetting powder coating is produced in the same manner as in Example 1 except that 5.0 parts by weight of X-22-3701E (Shin-Etsu Chemical Co., Ltd., trade name) is used as the organically modified polysiloxane (B). (Comparative Example 4) was obtained.
[0130]
[Comparative Example 5]
Instead of using the organically modified polysiloxane (B) within the scope of the present invention, 0.1 part by weight of SF8416 (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), which is a side chain alkyl-modified dimethylpolysiloxane, was used. Except for the above, a thermosetting powder coating material (Comparative Example 5) was obtained in the same manner as in Example 1.
[0131]
[Comparative Example 6]
Instead of using the organically modified polysiloxane (B) within the scope of the present invention, KF96H-10000 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., trade name, viscosity at 25 ° C.) is a polydimethylsiloxane in which the reactive functional group is not modified. A thermosetting powder coating material (Comparative Example 6) was obtained in the same manner as in Example 1 except that 0.1 part by weight of 10,000 cst) was used.
[0132]
[Comparative Example 7]
Thermosetting was carried out in the same manner as in Example 1 except that 0.1 part by weight of γ-glycidoxypropyltrimethoxysilane was used instead of using the organically modified polysiloxane (B) within the scope of the present invention. Powder coating composition (Comparative Example 7) was obtained.
[0133]
[Comparative Example 8]
Except for using 100 parts by weight of the acrylic copolymer copolymerized with the silicone macromonomer obtained in Production Example 5 and 30.9 parts by weight of dodecanedioic acid as a curing agent, the same method as in Example 1 A thermosetting powder coating (Comparative Example 8) was obtained.
[0134]
[Comparative Example 9]
100 parts by weight of an acrylic copolymer obtained by copolymerizing the silicone monomer (γ-methacryloxypropyltrimethoxysilane) obtained in Production Example 6 and 31.1 parts by weight of dodecanedioic acid as a curing agent were used. Except for this, a thermosetting powder coating material (Comparative Example 9) was obtained in the same manner as in Example 1.
[0135]
[Comparative Example 10]
Example 1 except that 100 parts by weight of the acrylic copolymer modified with γ-aminopropyltrimethoxysilane obtained in Production Example 9 and 31.0 parts by weight of dodecanedioic acid as a curing agent were used. A thermosetting powder coating material (Comparative Example 10) was obtained in exactly the same manner.
[0136]
[Evaluation of Examples and Comparative Examples]
A black coating material of polyester-melamine cross-linking was applied to a 0.8 mm-thick satin steel plate treated with zinc phosphate at a thickness of 20 μm, and then baked at 170 ° C. for 30 minutes to prepare a base-treated steel plate. The base-treated steel sheet was electrostatically coated with the thermosetting powder coating prepared in each example and comparative example so that the film thickness was 60 to 70 μm, and baked at 150 ° C. for 30 minutes. Got.
[0137]
The coated plate was evaluated as follows.
(1) Smoothness of the coating film: Regarding the smoothness, the appearance of the coating film was visually evaluated, ◎ indicates that it is excellent, ○ indicates that it is excellent, △ indicates that it is slightly uneven, and it is inferior Was marked with x.
(2) Vividness of the coating film: Regarding the sharpness, the appearance of the coating film was visually evaluated, ◎ indicating that it was excellent, ◯ indicating excellent, △ indicating slightly cloudy, Inferior ones were marked with x.
{Circle around (3)} Gloss; evaluated by gloss meter measurement (60 ° gloss).
(4) Solvent resistance: The surface of the coating film was rubbed back and forth 50 times with gauze impregnated with xylene, and then the rubbing spots were visually observed. A mark with no trace was marked with ◎, a mark with a slight mark was marked with ○, and a mark with marked marks was marked with ×.
(5) Acid resistance (acid rain resistance): 0.4 ml of 40 vol% sulfuric acid aqueous solution was spotted on the surface of the coating film, left in a dryer at 60 ° C. for 20 minutes, and then the spot was washed and dried. The surface condition of was visually observed. A mark with no trace was marked with ◎, a mark with a slight mark was marked with ◯, a marked mark was marked with △, and a mark with an entire surface was marked with x.
(6) Scratch resistance: A scratch test is performed in which the surface of the coating is rubbed with a brush using a 3% cleanser suspension, and the glossiness (20 ° gloss) is evaluated before and after the friction. Calculated. Gloss retention ratio of 60% or more indicates excellent scratch resistance ◎, 50% or more of less than 60% excellent ○, less than 50% scratch resistance is poor It was set as x as sufficient.
{Circle around (7)} Weather resistance: irradiated with a QUV tester for 2,000 hours, evaluated for 20 ° gloss before and after this irradiation, and calculated 20 ° gloss retention. The gloss retention was calculated according to the following formula.
[0138]
Gloss retention [%] = (20 ° gloss after irradiation) ÷ (20 ° gloss before irradiation) × 100
The gloss retention was evaluated as ◎ for 80% or more, ◯ for 70 to 80%, and x for 70% or less.
(8) Storage stability of powder coating; The powder coating composition was stored in a thermostatic bath at 30 ° C. for 30 days. Thereafter, this powder coating composition was formed into 10 mmφ, 0.3 g pellets. The pellets were attached to a 0.8 mm-thick satin steel plate treated with zinc phosphate, kept vertical, and held at 150 ° C. for 30 minutes. The heating fluidity (mm) at this time was measured. The pellets having a heat fluidity of 100 mm or more were evaluated as “◯”, those having a pellet flow rate of 20 mm or more and less than 100 mm as “Δ”, and those having a pellet less than 20 mm as “X”.
(9) Recoating property: After the coating plate baked at 150 ° C. for 30 minutes is further overbaked at the same temperature for 30 minutes, the same powder coating material used for the coating film formation of the coating plate is electrostatically coated, Baking was performed at 150 ° C. for 30 minutes. The test coating film was subjected to a 2 mm width, 10 × 10 cross-cut adhesion test, and the number of cells remaining without peeling after the test was displayed. When no peeling is observed, it is 100, and it is determined that the coating film has good recoating property. When all peeling is performed, it is 0, and it is determined that the recoating property is insufficient.
[0139]
The evaluation results of these coating films are shown in Tables 3 to 5. Examples 1-16 relate to compositions with varying types and combinations of components within the scope of the present invention. Comparative Examples 1-10 are for comparison with the compositions of the present invention and relate to compositions of component types and combinations that are outside the scope of the present invention.
[0140]
As is apparent from the evaluation results of Examples 1 to 16, the composition of the present invention simultaneously exhibits excellent performance for all of the evaluation items (1) to (9).
[0141]
Comparative Examples 1 and 2 are examples of powder coating compositions in which the organically modified polysiloxane (B) was not used, and the smoothness, acid resistance, and scratch resistance of the coating film were inferior.
[0142]
Comparative Example 3 is an example in which a low Tg acrylic flow regulator was used without using the organically modified silicone oil (B). In this case, the smoothness of the coating film was better than that of Comparative Example 1. However, the acid resistance and scratch resistance improvement of the coating film is insufficient.
Comparative Example 4 is an example in which the organically modified polysiloxane (B) is frequently used in an amount outside the range of the present invention. In this case, the solvent resistance and recoatability of the coating film are inferior.
[0143]
Comparative Examples 5 and 6 are examples using a polysiloxane having no reactive functional group outside the scope of the present invention. In this case, the appearance, scratch resistance, acid resistance and recoatability of the coating film are inferior. .
[0144]
Comparative Example 7 is an example in which 0.1 part by weight of γ-glycidoxypropyltrimethoxysilane was added instead of using the organically modified polysiloxane (B) within the scope of the present invention. Acid resistance, scratch resistance, and storage stability of powder coating are inferior.
[0145]
Comparative Example 8 is an example using an acrylic copolymer copolymerized with a silicone macromonomer, but in this case, the improvement in the recoatability of the coating film is insufficient.
[0146]
Comparative Example 9 is an example using an acrylic copolymer copolymerized with a silicone monomer (γ-methacryloxypropyltrimethoxysilane). In this case, the scratch resistance and acid resistance of the coating film, The storage stability of the paint is poor.
[0147]
Comparative Example 10 is an example using an acrylic copolymer modified with γ-aminopropyltrimethoxysilane. In this case, however, the scratch resistance and acid resistance of the coating film and the storage stability of the paint are inferior.
[0148]
[Table 1]

[0149]
[Table 2]

[0150]
[Table 3]

[0151]
[Table 4]

[0152]
[Table 5]

[0153]
【The invention's effect】
As explained above, according to the present invention,
(I) improving compatibility during preparation of the coating composition and preventing contamination during production;
(Ii) improving the complete coverage of the coating on the substrate (base);
(Iii) Appearance characteristics (smoothness, sharpness, etc.), physical characteristics (scratch resistance, recoatability, etc.), weather resistance, UV resistance, and chemical characteristics (acid rain resistance) The coating film properties such as properties, solvent resistance, etc.), at the same time, exhibiting excellent performance, especially remarkably improving acid rain resistance, recoatability, solvent resistance, and scratch resistance, and
(Iv) Improving the storage stability of the coating composition
It is possible to provide a thermosetting powder coating composition for a top coat that can be applied.

Claims (19)

A monomer (a1) having at least one radically polymerizable unsaturated bond and at least one epoxy group in one molecule, and at least one radically polymerizable unsaturated bond in one molecule; And 100 parts by weight of an acrylic copolymer (A) obtained by polymerization in a reaction system containing a monomer (a2) having no epoxy group, and
Organo-modified polysiloxane (B) having at least one functional group and at least two silicon atoms in one molecule and having no radically polymerizable unsaturated bond, 0.01 to 2.0 weight The component (B) is partly or wholly reacted with the component (A) in a combined state, or the component (B) is contained in an unreacted state. Powder coating composition. Furthermore, it contains 5 to 60 parts by weight of a curing agent (C) composed of at least one polycarboxylic acid compound selected from the group consisting of polycarboxylic acid (c1) and polyhydric carboxylic acid anhydride (c2). The thermosetting powder coating composition according to claim 1. The thermosetting powder coating composition according to claim 2, wherein the functional group of the organically modified polysiloxane (B) is a group reactive to the acrylic copolymer (A) or the curing agent (C). The thermosetting powder coating composition according to claim 2, wherein a part or all of the component (B) is contained in a state of being reacted and bonded to the acrylic copolymer (A) or the component (C). object. The thermosetting powder coating composition according to claim 1, wherein the component (B) is entirely contained in an unreacted state. The organically modified polysiloxane (B) has the following general formulas (I), (II), (III) and (IV)

[In the formula (1), X ¹ and X ² are the following general formulas (a) to (f)

(In the formulas (a) to (f), Ra, Rb, Rc, Rd and Re are a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or an ether bond. And / or a hydrocarbon group having an ester bond, and Rf represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or a derivative thereof.)
Wherein R ¹ and R ² represent a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group or a derivative thereof, and R ^{3 to} R ⁸ represent carbon. It represents an alkyl group having 1 to 8 atoms, a phenyl group or a derivative thereof, and n1 represents a number from 1 to 1,500. ]

[In the formula (II), X ³ is a group represented by any one of the general formulas (a) to (e), and R ^{9 to} R ¹⁵ are alkyl having 1 to 8 carbon atoms. R ¹⁶ represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or an ether bond and / or an ester bond. Represents a hydrocarbon group, and n2 represents a number of 1 to 1,500. ]

[In the formula (III), X ⁴ is a group represented by any one of the general formulas (a) to (e), and R ^{17 to} R ²⁵ are alkyl having 1 to 8 carbon atoms. R ²⁶ represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or an ether bond and / or an ester bond. Represents a hydrocarbon group, x1 represents a number from 1 to 1,300, and y1 represents a number from 1 to 200. ]

[In the formula (IV), X ⁵ , X ⁶ and X ⁷ are groups represented by any one of the general formulas (a) to (e), and R ^{30 to} R ³⁶ are carbon Represents an alkyl group having 1 to 8 atoms, a phenyl group, or a derivative thereof, and R ^{27 to} R ²⁹ are a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or Represents a hydrocarbon group having an ether bond and / or an ester bond, x2 represents a number from 1 to 1,300, and y2 represents a number from 1 to 200. ]
The thermosetting powder coating composition according to claim 1, comprising at least one organically modified polysiloxane represented by any one of the formulas. The organically modified polysiloxane (B) has the following general formulas (V), (V ′), (VI), (VI ′), (VII), (VII ′), (VIII), (VIII ′), (IX ), (X), (XI), (XII), (XIII), (XIV), (XV), (XVI), (XVII), (XVIII), (XIX), (XX), (XXI), (XXII), (XXIII), (XXIV), (XXV), (XXVI), (XXVII) and (XXVIII)

(In the formulas (V) to (XXVIII), each R is independently a direct bond, an alkylene group having 1 to 20 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or an ether bond and / or an ester. Each represents independently a number of 1 to 1,500, each x independently represents a number 1 to 1,300, and each y independently represents a number 1 to 200. .)
The thermosetting powder coating composition according to claim 1, comprising at least one organically modified polysiloxane represented by any one of the formulas. The thermosetting powder coating composition according to claim 7, wherein the organically modified polysiloxane represented by any one of the general formulas (V) to (XII) has an epoxy equivalent of 200 to 5,000. The thermosetting powder coating material according to claim 7, wherein the organically modified polysiloxane having a carboxyl group represented by any one of the general formulas (XIII) to (XVI) has a carboxyl equivalent of 500 to 5,000. Composition. The thermosetting according to claim 7, wherein the organically modified polysiloxane modified with phenol represented by any one of the general formulas (XVII) to (XX) has an -OH equivalent weight of 1,000 to 5,000. Powder coating composition. Organomodified polysiloxanes, thermosetting powder -NH ₂ according to claim 7 having an equivalent weight of 500 to 10,000 having an amino group represented by any of the formulas of the general formula (XXI) ~ (XXVIII) Body paint composition. The thermosetting powder coating composition according to claim 1, comprising 0.01 to 1.0 part by weight of the organically modified polysiloxane (B) with respect to 100 parts by weight of the acrylic copolymer (A). The acrylic copolymer (A) is used in an amount of 15 to 60 parts by weight of the monomer (a1) and 100% by weight of the monomer (a1) and the monomer (a2). a2) a copolymer obtained by polymerization in a reaction system containing 40 to 85 parts by weight,
40 to 85 parts by weight of monomer (a2) includes 1 to 30 parts by weight of styrene and 39 to 55 parts by weight of (meth) acrylic acid ester having an alkyl group and / or a cyclohexyl group having 1 to 12 carbon atoms. The thermosetting powder coating composition according to claim 1. The thermosetting powder coating composition according to claim 1, wherein the monomer (a1) contains at least one monomer selected from the group consisting of glycidyl (meth) acrylate and β-methylglycidyl (meth) acrylate. . The thermosetting powder according to claim 2, wherein the functional group capable of undergoing a crosslinking reaction of the curing agent (C) is 0.5 to 1.5 equivalents relative to 1 equivalent of the epoxy group of the acrylic copolymer (A). Paint composition. The thermosetting powder coating composition according to claim 2, wherein the melting point of the curing agent (C) is 40 to 170 ° C. The polyvalent carboxylic acid (c1) is an aliphatic dicarboxylic acid having 8 to 20 carbon atoms, and the polyvalent carboxylic acid anhydride (c2) is derived by dehydration condensation of an aliphatic dicarboxylic acid having 8 to 20 carbon atoms. The thermosetting powder coating composition according to claim 16, which is a linear dimer or higher oligo or polyanhydride. A method for producing a thermosetting powder coating using the composition according to claim 1, comprising at least an acrylic copolymer (A), an organically modified polysiloxane (B) and a curing agent (C). A method for producing a thermosetting powder coating, comprising: a step of melt-kneading raw materials; and a step of cooling and pulverizing the melt-kneaded product. The method for producing a thermosetting powder coating according to claim 18, wherein the melt-kneading step is performed at a temperature of 40 to 130 ° C.