JP2004204073A - Coating composition, coating film, and coated article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a coating composition which contains a surfactant having no possibility of forming endocrine disrupters, being good in mechanical stability and storage stability, and giving a coating film excellent in adhesion to substrates. <P>SOLUTION: The coating composition comprises an aqueous dispersion containing a heat-resistant resin, a fluoropolymer, and the surfactant. The surfactant is a non-alkylphenol-type nonionic surfactant. The non-alkylphenol-type nonionic surfactant is used in an amount of 0.1 to 20 pts. mass per 100 pts. mass solids of the fluoropolymer. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３８】
（式中、Ｒｆは、炭素数４〜２０のパーフルオロアルキル基を表し、Ｒ^１は、水素原子又は炭素数１〜１０のアルキル基を表し、Ｒ^２は、炭素数１〜１０のアルキレン基を表し、Ｒ^３は、水素原子又はメチル基を表し、Ｒ^４は、炭素数１〜１７のアルキル基を表し、ｒは、１〜１０の整数を表し、ｓは、０〜１０の整数を表す。）で表されるものである。
【００３９】
上記含フッ素重合体は、上記ＰＡＥ（ｄ）の単独重合体であってもよいし、また、上記ＰＡＥ（ｄ）と上記ＰＡＥ（ｄ）と共重合し得る単量体（ｅ）との共重合体であってもよい。上記単量体（ｅ）としては特に限定されず、例えば、（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸ベンジルエステル、ジ（メタ）アクリル酸ポリエチレングリコール、Ｎ−メチロールプロパンアクリルアミド、（メタ）アクリル酸アミド、アルキル基の炭素数が１〜２０である（メタ）アクリル酸のアルキルエステル等の（メタ）アクリル酸誘導体；エチレン、塩化ビニル、フッ化ビニル、スチレン、α−メチルスチレン、ｐ−メチルスチレン等の置換又は非置換エチレン；アルキル基の炭素数が１〜２０であるアルキルビニルエーテル、アルキル基の炭素数が１〜２０であるハロゲン化アルキルビニルエーテル等のビニルエーテル類；アルキル基の炭素数が１〜２０であるビニルアルキルケトン等のビニルケトン類；無水マレイン酸等の脂肪族不飽和ポリカルボン酸及びその誘導体；ブタジエン、イソプレン、クロロプレン等のポリエン等が挙げられる。
【００４０】
上記含フッ素重合体は、非粘着性、滑り性、耐熱性等に優れる点から、ＰＴＦＥ、ＦＥＰ及び／又はＰＦＡが好ましく、例えば、ＰＴＦＥ、ＦＥＰ、ＰＦＡ、ＰＴＦＥとＦＥＰとの混合物、ＰＴＦＥとＰＦＡとの混合物等が挙げられる。
【００４１】
上記ＰＴＦＥはＴＦＥ、ＦＥＰはＴＦＥとＨＦＰ、ＰＦＡはＴＦＥとＰＡＶＥがそれぞれ必須単量体であるが、これらの必須単量体以外のその他の微量単量体が付加されているものであってもよい。
上記微量単量体としては特に限定されず、例えば、ＣＴＦＥ等の上記不飽和炭化水素（ａ）；３ＦＨ等の上記不飽和化合物（ｂ）；パーフルオロ（アルコキシビニルエーテル）、（パーフルオロアルキル）エチレン等の上記その他の単量体（ｃ）等が挙げられる。上記微量単量体としては、含フッ素重合体が上記ＰＴＦＥである場合、更に、ＨＦＰ、ＰＡＶＥが挙げられ、上記ＦＥＰである場合、更に、ＰＡＶＥが挙げられ、上記ＰＦＡである場合、更に、ＨＦＰが挙げられる。上記微量単量体は、１種又は２種以上を用いることができる。
上記微量単量体は、その種類によって異なるが、通常、含フッ素重合体の質量の１質量％以下であることが好ましい。より好ましい上限は０．５質量％であり、更に好ましい上限は０．３質量％であり、好ましい下限は、０．０１質量％である。
【００４２】
上記含フッ素重合体は、ＰＴＦＥ及び／又はＦＥＰがより好ましい。上記「ＰＴＦＥ及び／又はＦＥＰ」とは、ＰＴＦＥ、ＦＥＰ、ＰＴＦＥとＦＥＰとの混合物を意味する。
【００４３】
上記含フッ素重合体は、例えば、乳化重合、懸濁重合等の従来公知の重合方法を用いて重合することにより得ることができる。上記重合方法により得られる含フッ素重合体は、所望により、上述の範囲内の平均粒子径を有するように粉砕する。上記粉砕の方法としては特に限定されず、例えば、上記含フッ素重合体をロールでシート状に圧縮し、粉砕機により粉砕し分級する方法等が挙げられる。
上記含フッ素重合体は、乳化重合や懸濁重合を用いて得る場合、得られる重合体成分のみを単離することなくディスパージョンのまま被覆用組成物の調製に用いてもよいし、上記ディスパージョンは、得られる重合体成分からなる分散液に界面活性剤（Ｓ１）を添加することにより上記分散液を濃縮し、必要に応じ更に界面活性剤（Ｓ２）を添加して、被覆用組成物として調製したものであってもよい。本明細書において、重合により得られた含フッ素重合体からなるディスパージョンを濃縮したものであって、上記界面活性剤（Ｓ２）を添加していないものを「生成重合体濃縮液」ということがある。
【００４４】
本発明の被覆用組成物において、上記含フッ素重合体は、上述のように水性媒体に粒子として分散したものである。上記含フッ素重合体は、平均粒子径が０．０１〜５０μｍである粒子からなるものが好ましい。０．０１μｍ未満であると、含フッ素重合体からなる粒子の分散性が悪く、得られる被覆用組成物が機械的安定性及び貯蔵安定性に劣るおそれがある。５０μｍを超えると、含フッ素重合体からなる粒子の均一分散性に欠け、得られる被覆用組成物を用いて塗装する際、表面が平滑な塗膜が得られず、塗膜物性が劣る場合がある。より好ましい上限は、５μｍであり、更に好ましい上限は、０．５μｍであり、より好ましい下限は、０．０５μｍである。上記機械的安定性は、送液・再分散の際、ホモジナイザー等による強い攪拌や剪断力を与えても、再分散不可能な凝集体を生成しにくい性質のことである。
【００４５】
本発明の被覆用組成物において、上記水性分散体は、上記含フッ素重合体とともに、非アルキルフェノール型ノニオン界面活性剤からなるものである。
本明細書において、上記「非アルキルフェノール型ノニオン界面活性剤」とは、分子構造中にアルキルェノールに由来する分子構造部分を有していないノニオン界面活性剤を意味する。
【００４６】
上記非アルキルフェノール型ノニオン界面活性剤は、下記一般式（Ｉ）：
Ｒ−Ｏ−Ａ−Ｈ
（式中、Ｒは、直鎖状又は分岐鎖状の炭素数８〜１９の飽和若しくは不飽和の非環式脂肪族炭化水素基、又は、炭素数８〜１９の飽和環式脂肪族炭化水素基を表す。Ａは、オキシエチレンユニットを３〜２５個及びオキシプロピレンユニットを０〜５個有するポリオキシアルキレン鎖を表す。）で表されるノニオン界面活性剤が好ましい。
本明細書において、上記一般式（Ｉ）における上記Ｒの炭素数、オキシエチレンユニットの個数及びオキシプロピレンユニットの個数は、上記非アルキルフェノール型ノニオン界面活性剤の各分子における値の平均である。
【００４７】
上記非環式脂肪族炭化水素基は、環状構造を有していない脂肪族炭化水素基である。上記飽和環式脂肪族炭化水素基は、飽和環状構造を有している脂肪族炭化水素基である。上記飽和環式脂肪族炭化水素基は、炭素数の合計が８〜１９であれば、飽和環状構造を１個又は２個以上有していてもよい。上記飽和環式脂肪族炭化水素基は、置換基を含めた炭素数の合計が８〜１９であれば、飽和環状構造の炭素原子に結合している水素原子が直鎖状又は分岐鎖状のアルキル基に置換されていてもよく、上記水素原子は、１個又は２個以上置換されていてもよい。
【００４８】
上記一般式（Ｉ）における上記Ｒは、含フッ素重合体からなる粒子の分散性に優れ、得られる被覆用組成物が機械的安定性及び貯蔵安定性に優れる点から、炭素数の好ましい上限が１６であり、より好ましい上限が１４であり、好ましい下限が１０である。上記Ｒは、炭素数が１３であることが更に好ましい。上記Ｒは、炭素数が１３の飽和の非環式脂肪族炭化水素基であることが特に好ましく、このようなものとしては、例えば、トリデシル基、イソトリデシル基等が挙げられる。
【００４９】
上記一般式（Ｉ）におけるＡは、オキシエチレンユニットを３〜２５個及びオキシプロピレンユニットを０〜５個有するポリオキシアルキレン鎖を表す。本明細書において、上記「オキシエチレンユニット」は、オキシエチレン基であり、上記「オキシプロピレンユニット」は、オキシプロピレン基である。本明細書において、上記「オキシエチレンユニットを３〜２５個及びオキシプロピレンユニットを０〜５個有するポリオキシアルキレン鎖」とは、３〜２５個のオキシエチレンユニットと、０〜５個のオキシプロピレンユニットとからなるポリオキシアルキレン鎖を意味する。
上記ポリオキシアルキレン鎖は、オキシエチレンユニットとオキシプロピレンユニットとのみからなるものであることが好ましいが、上記オキシプロピレンユニットは、上記ポリオキシアルキレン鎖中に存在していなくてもよい。
【００５０】
上記オキシプロピレンユニットが５個を超えると、上記非アルキルフェノール型ノニオン界面活性剤の溶解力を低下させるので、含フッ素重合体からなる粒子の分散性を下げ、被覆用組成物の機械的安定性及び貯蔵安定性が劣るおそれがある。上記オキシプロピレンユニットは、少ないほど好ましく、好ましい上限は、３個である。上記オキシプロピレンユニットは、上記ポリオキシアルキレン鎖中に存在していないことがより好ましい。
上記ポリオキシアルキレン鎖の上記オキシエチレンユニットの好ましい上限は、上記Ｒの炭素数にもよるが、７個であり、より好ましい上限は、６個である。
【００５１】
上記ポリオキシアルキレン鎖は、上記オキシエチレンユニットが３〜７個であり、上記オキシプロピレンユニットが０〜３個であるものが好ましく、上記オキシエチレンユニットが３〜６個であり、上記オキシプロピレンユニットが存在していないものがより好ましい。
【００５２】
上記一般式（Ｉ）における−Ｏ−と上記一般式（Ｉ）におけるＡのポリオキシアルキレン鎖との結合は、ポリオキシアルキレン鎖における炭素原子が上記一般式（Ｉ）における−Ｏ−に隣接して結合する配向によるものであり、例えば、上記ポリオキシアルキレン鎖中のオキシエチレンユニットと−Ｏ−とが結合している場合、上記−Ｏ−と隣接するオキシエチレンユニットとは−Ｏ−（ＣＨ_２ＣＨ_２Ｏ）−で表される配向で結合している。
【００５３】
非アルキルフェノール型ノニオン界面活性剤は、ＨＬＢ値が１２未満であるものからなることが好ましい。生成重合体濃縮液に添加する上述の界面活性剤（Ｓ２）として用いる非アルキルフェノール型ノニオン界面活性剤は、ＨＬＢ値が１２未満であるものが好ましい。
上記非アルキルフェノール型ノニオン界面活性剤は、一般の界面活性剤と同様に、その分子構造に基づく固有のＨＬＢ値を有している。上記ＨＬＢ値は、界面活性剤の親水性及び疎水性のバランスの指標であり、一般に、親水性が高いほど値が大きく、疎水性が高いほど値が小さい。本明細書において、上記「ＨＬＢ値」とは、Ｇｒｉｆｆｉｎの算出方法に基づいて算出した値を意味する。
【００５４】
上記非アルキルフェノール型ノニオン界面活性剤は、上記ＨＬＢ値が１２以上であると、含フッ素重合体からなる粒子が凝集しやすく、得られる被覆用組成物の機械的安定性が不充分である場合があり、また、得られる被覆用組成物を基材に塗装して乾燥した後、上塗り用含フッ素重合体からなる上塗り塗料を塗装する場合、ハジキが発生し易い。上記ＨＬＢ値は、１１以下であることがより好ましく、１０以下であることが更に好ましい。上記ＨＬＢ値は、上記範囲内であれば、得られる被覆用組成物の分散性を悪化させない点で、５以上であることがより好ましい。上記ＨＬＢ値の更に好ましい下限は７であり、特に好ましい下限は９である。
【００５５】
上記非アルキルフェノール型ノニオン界面活性剤としては、１種又は２種以上を用いることができる。上記ＨＬＢ値は、上記非アルキルフェノール型ノニオン界面活性剤を２種以上用いる場合、それぞれのＨＬＢ値と混合割合とから算出することができる。上記非アルキルフェノール型ノニオン界面活性剤を２種以上用いる場合、上記により算出されるＨＬＢ値は、１２以下であることが好ましい。上述のように、非アルキルフェノール型ノニオン界面活性剤がＨＬＢ値１２未満であるものからなる場合、用いる非アルキルフェノール型ノニオン界面活性剤としては、ＨＬＢ値が１２未満のものを少なくとも１種用いるのであれば、ＨＬＢ値が１２以上のものの１種又は２種以上を併用してもよい。
生成重合体濃縮液に添加する上述の界面活性剤（Ｓ２）として用いる上記非アルキルフェノール型ノニオン界面活性剤は、１種又は２種以上を用いることができ、算出されるＨＬＢ値が１２未満であれば、ＨＬＢ値が１２未満のものとともに、ＨＬＢ値が１２以上のものの１種又は２種以上を用いてもよい。
【００５６】
本発明の被覆用組成物において、上記水性分散体は、上記非アルキルフェノール型ノニオン界面活性剤とともに、必要に応じてアニオン界面活性剤やカチオン界面活性剤を用いたものであってもよく、上記アニオン界面活性剤やカチオン界面活性剤としては、例えば、フッ素原子が結合している含フッ素系界面活性剤を用いてもよい。
【００５７】
本発明の被覆用組成物は、上述のように、界面活性剤として非アルキルフェノール型ノニオン界面活性剤を用いるものであり、必要に応じてアニオン界面活性剤やカチオン界面活性剤を用いたものである。従来の塗料組成物に用いられていたアルキルフェノール系ノニオン界面活性剤は、塗布や焼成を行うことにより熱分解した際、内分泌撹乱物質のおそれがあるアルキルフェノールを生じる場合があるが、上記非アルキルフェノール型ノニオン界面活性剤は、アルキルフェノール系ノニオン界面活性剤と異なりその構造中にアルキルェノールに由来する分子構造部分を有さないので、熱分解しても上記アルキルフェノールを生じるおそれがない。
【００５８】
本発明の被覆用組成物において、上記非アルキルフェノール型ノニオン界面活性剤は、上記含フッ素重合体の固形分１００質量部に対して０．１〜２０質量部である。
本明細書において、上記「固形分」とは、２０℃において固体であるものを意味する。本明細書において、上記「含フッ素重合体の固形分」とは、被覆用組成物を基材上に塗布したのち８０〜１００℃以下の温度で乾燥し、３８０〜４００℃で４５分間焼成した後の残渣における含フッ素重合体の固形分を意味する。
【００５９】
上記非アルキルフェノール型ノニオン界面活性剤は、上記含フッ素重合体の固形分１００質量部に対して０．１質量部未満であると、得られる組成物中で含フッ素重合体からなる粒子が沈降しやすく、貯蔵安定性に劣る。２０質量部を超えると、得られる組成物が粘度を増し、塗装作業性が悪くなる。より好ましい下限は、５質量部であり、更に好ましい下限は、７質量部である。
本発明の被覆用組成物は、非アルキルフェノール型ノニオン界面活性剤を上述の量で配合してなるものであるので、機械的安定性及び貯蔵安定性に優れたものである。
【００６０】
本発明の被覆用組成物において、上記水性分散体は、上記含フッ素重合体と非アルキルフェノール型ノニオン界面活性剤とともに、耐熱樹脂からなるものである。
上記耐熱樹脂は、通常、耐熱性を有すると認識されている樹脂であればよく、連続使用可能温度が１５０℃以上の樹脂が好ましい。
上記耐熱樹脂としては特に限定されず、例えば、ポリアミドイミド樹脂、ポリイミド樹脂、ポリエーテルスルホン樹脂、ポリエーテルイミド樹脂、ポリエーテルエーテルケトン樹脂、芳香族ポリエステル樹脂、ポリアリレンサルファイド樹脂等が挙げられる。上記耐熱樹脂としては、１種又は２種以上を用いることができる。
【００６１】
上記ポリアミドイミド樹脂〔ＰＡＩ〕は、分子構造中にアミド結合及びイミド結合を有する重合体からなる樹脂である。上記ＰＡＩとしては特に限定されず、例えば、アミド結合を分子内に有する芳香族ジアミンとピロメリット酸等の芳香族四価カルボン酸との反応；無水トリメリット酸等の芳香族三価カルボン酸と４，４−ジアミノフェニルエーテル等のジアミンやジフェニルメタンジイソシアネート等のジイソシアネートとの反応；芳香族イミド環を分子内に有する二塩基酸とジアミンとの反応等の各反応により得られる高分子量重合体からなる樹脂等が挙げられる。上記ＰＡＩとしては、耐熱性に優れる点から、主鎖中に芳香環を有する重合体からなるものが好ましい。
【００６２】
上記ポリイミド樹脂〔ＰＩ〕は、分子構造中にイミド結合を有する重合体からなる樹脂である。上記ＰＩとしては特に限定されず、例えば、無水ピロメリット酸等の芳香族四価カルボン酸無水物の反応等により得られる高分子量重合体からなる樹脂等が挙げられる。上記ＰＩとしては、耐熱性に優れる点から、主鎖中に芳香環を有する重合体からなるものが好ましい。
【００６３】
上記ポリエーテルスルホン樹脂〔ＰＥＳ〕は、下記一般式：
【００６４】
【化２】

【００６５】
で表される繰り返し単位を有する重合体からなる樹脂である。上記ＰＥＳとしては特に限定されず、例えば、ジクロロジフェニルスルホンとビスフェノールとの重縮合により得られる重合体からなる樹脂等が挙げられる。
ＰＡＩ、ＰＩ及びＰＥＳは、それぞれが１種又は２種以上からなるものであってよい。
【００６６】
上記耐熱樹脂は、被塗装物と、被覆用組成物を塗装することにより得られる塗膜との密着性を向上させることができ、この密着性を高温下においても維持することができる点から、ＰＡＩ及び／又はＰＩがより好ましい。上記「ＰＡＩ及び／又はＰＩ」とは、ＰＡＩ、ＰＩ、又は、ＰＡＩとＰＩとの混合物を意味する。
【００６７】
上記耐熱樹脂は、被塗装物との密着性に優れ、上記塗膜を形成する際に焼成時の温度下でも充分な耐熱性を有し、得られる塗膜が耐食性及び耐水蒸気性に優れる点から、ＰＡＩ、ＰＩ及び／又はＰＥＳが好ましい。上記「ＰＡＩ、ＰＩ及び／又はＰＥＳ」とは、ＰＡＩ、ＰＩ、ＰＥＳ、ＰＡＩとＰＩとの混合物、ＰＥＳとＰＡＩとの混合物、ＰＥＳとＰＩとの混合物、ＰＥＳとＰＡＩとＰＩとの混合物を意味する。
【００６８】
上記耐熱樹脂は、耐熱性、被塗装物への密着性に優れ、なかでも、上記塗膜の耐食性及び耐水蒸気性が特に優れる点から、ＰＥＳと、ＰＡＩ及び／又はＰＩがより好ましい。上記「ＰＥＳと、ＰＡＩ及び／又はＰＩ」とは、ＰＥＳとＰＡＩとの混合物、ＰＥＳとＰＩとの混合物、又は、ＰＥＳとＰＡＩとＰＩとの混合物を意味する。上記耐熱樹脂は、上記ＰＥＳ及びＰＡＩの混合物であることが更に好ましい。
本発明の被覆用組成物において、ＰＥＳは、ＰＥＳと、ＰＡＩ及び／又はＰＩとの合計質量の６５〜８５質量％であることが好ましい。６５質量％未満であると、被覆用組成物から得られる塗膜の耐水蒸気性が低下するおそれがあり、８５質量％を超えると、塗膜の耐食性が低下するおそれがある。
【００６９】
本発明の被覆用組成物において、上記耐熱樹脂は、後述の水性媒体に粒子として分散したもの、又は、水性媒体に溶解したものである。上記耐熱樹脂が水性媒体に粒子として分散している場合、上記耐熱樹脂からなる粒子は、上記水性媒体に粒子として分散した平均粒子径が０．１〜１０μｍである粒子であることが好ましい。上記耐熱樹脂の平均粒子径が上記範囲内であると、被覆用組成物から得られる塗膜の耐食性が良好である。
【００７０】
本発明の被覆用組成物において、上述の水性分散体は、上記耐熱樹脂と含フッ素重合体と非アルキルフェノール型ノニオン界面活性剤とともに、必要に応じ、その他の樹脂からなるものであってもよい。上記その他の樹脂を配合することにより、被覆用組成物から得られる塗膜の造膜性、耐食性等を向上させることができる。
【００７１】
上記その他の樹脂としては特に限定されず、例えば、フェノール樹脂、尿素樹脂、エポキシ樹脂、ウレタン樹脂、メラミン樹脂、ポリエステル樹脂、ポリエーテル樹脂、アクリル樹脂、アクリルシリコーン樹脂、シリコーン樹脂、シリコーンポリエステル樹脂等が挙げられる。
【００７２】
本発明の被覆用組成物において、上記水性分散体は、含フッ素重合体からなる粒子を主に分散質とし、水性媒体を分散媒とするものである。上記水性媒体は水を含むものであれば特に限定されず、例えば、水及び有機液体との混合物、水等が挙げられる。
【００７３】
上記有機液体としては特に限定されず、例えば、トルエン、キシレン、トリメチルベンゼン、メチルエチルベンゼン、プロピルベンゼン、ブチルベンゼン等の芳香族炭化水素系溶剤；炭素数が６〜１２の飽和炭化水素系溶剤；Ｎ−メチル−２−ピロリドン、２−ピロリドン、Ｎ，Ｎ−ジメチルアセトアミド等の含窒素系溶剤；γ−ブチロラクトン等のラクトン類；酢酸ブチル等の非環状エステル類；メチルイソブチルケトン、メチルエチルケトン等のケトン類；ブチルセロソルブ等のグリコールエーテル類；エチレングリコール、トリエチレングリコール、プロピレングリコール等のグリコール類；１−ブタノール、ジアセトンアルコール等のモノアルコール類等が挙げられる。
【００７４】
上記芳香族炭化水素系溶剤としては、市販品であるソルベッソ１００、ソルベッソ１５０、ソルベッソ２００（何れも商品名、エクソン化学社製）等を用いてもよい。上記飽和炭化水素系溶剤としては、市販品であるミネラルスピリット（日本工業規格、工業ガソリン４号）等を用いてもよい。上記有機液体は、単独で用いてもよいし、２種以上を併用してもよい。
上記有機液体としては、含窒素系溶剤を用いることが好ましく、Ｎ−メチル−２−ピロリドン、ジメチルアセトアミドを用いることがより好ましい。
【００７５】
上記水性媒体は、例えば、後述の各種添加剤が溶解又は分散しているものであってもよい。上記水性媒体は、含フッ素重合体の重合に用いた水性媒体であってもよいし、重合に用いた水性媒体とは別に用意したものであってもよいが、上記含フッ素重合体を乳化重合や懸濁重合により得る場合、含フッ素重合体の重合に用いた水性媒体をそのまま用いることができる。
【００７６】
本発明の被覆用組成物は、塗装性、被覆用組成物から得られる塗膜の性質向上等を目的として、更に、一般的なコーティング用組成物に通常用いられる各種添加剤を配合してなるものであってもよい。上記各種添加剤としては特に限定されず、本発明の被覆用組成物を用いることにより得られる後述の被覆物品の用途に応じて選択され、例えば、レベリング剤、固体潤滑剤、顔料、充填材、顔料分散剤、沈降防止剤、水分吸収剤、表面調整剤、チキソトロピー性付与剤、粘度調節剤、ゲル化防止剤、紫外線吸収剤、光安定剤、可塑剤、色分かれ防止剤、皮張り防止剤、スリ傷防止剤、防カビ剤、抗菌剤、酸化防止剤、帯電防止剤、シランカップリング剤等が挙げられる。
【００７７】
本発明の被覆用組成物は、２５℃における粘度が０．１〜５００００ｍＰａ・ｓであることが好ましい。粘度が０．１ｍＰａ・ｓ未満であると、被塗装物上への塗布時にタレ等を生じやすく、目的とする膜厚を得ることが困難となる場合があり、５００００ｍＰａ・ｓを超えると、塗装作業性が悪くなる場合があり、得られる塗膜の膜厚が均一とならず、表面平滑性等に劣る場合がある。より好ましい下限は、１ｍＰａ・ｓであり、より好ましい上限は、３００００ｍＰａ・ｓである。上記粘度は、ＢＭ型単一円筒型回転粘度計（東京計器社製）を用いて測定することにより得られる値である。
【００７８】
本発明の被覆用組成物は、上述のワンコートに用いる塗料組成物であってもよいし、上述のツーコートに用いるプライマー組成物であってもよいが、プライマー組成物に好適である。
【００７９】
本発明の被覆用組成物をプライマー組成物として用いる場合、上記耐熱樹脂は、上記耐熱樹脂と含フッ素重合体との合計固形分質量の１５〜５０質量％であることが好ましい。
本明細書において、上記「耐熱樹脂と含フッ素重合体との合計固形分質量」とは、本発明の被覆用組成物を被塗装物上に塗布したのち８０〜１００℃以下の温度で乾燥し、３８０〜４００℃で４５分間焼成した後の残渣における上記耐熱樹脂と含フッ素重合体との合計質量を意味する。
【００８０】
上記耐熱樹脂は、上記耐熱樹脂及び含フッ素重合体の固形分合計量の１５質量％未満であると、耐熱樹脂が少ないので、被覆用組成物から得られる塗膜と被塗装物との密着性が不充分である場合がある。５０質量％を超えると、含フッ素重合体が少ないので、上記塗膜と上塗り塗膜との密着性が不充分であるおそれがある。より好ましい下限は、２０質量％であり、より好ましい上限は、４０質量％である。
【００８１】
本発明の被覆用組成物は、従来公知の方法等により調製することができ、例えば、上記耐熱樹脂、含フッ素重合体、非アルキルフェノール型ノニオン界面活性剤及び必要に応じて配合するその他の樹脂を適宜混合して上記水性媒体に分散することにより水性ディスパージョンを得、必要に応じて粘度調節剤等を用いて塗装しやすい粘度に調整し、所望に応じて上記粘度調節剤以外の各種添加剤を配合する方法等が挙げられる。本発明の被覆用組成物は、また、上記耐熱樹脂、含フッ素重合体、顔料等のそれぞれの分散体を予め調製し、得られる分散体を混合することより調製を行うものであってもよい。上記それぞれの分散体の調製は、必要に応じて上記非アルキルフェノール型ノニオン界面活性剤等を用いてもよい。
【００８２】
本発明の被覆用組成物は、界面活性剤として非アルキルフェノール型ノニオン界面活性剤を用いるものであるので、塗装時に乾燥や焼成を行っても内分泌撹乱物質を生じるおそれがなく、また、上述の量を配合してなるものであるので機械的安定性及び貯蔵安定性に優れたものである。
本発明の被覆用組成物は、また、含フッ素重合体からなるものであり、被覆用組成物が上述のワンコートに用いる塗料組成物である場合、被塗装物に非粘着性、潤滑性等を付与することができ、上述のツーコートに用いるプライマー組成物である場合、塗装することにより得られる塗膜と上述の上塗り塗膜との密着性を向上させることができるものである。
本発明の被覆用組成物は、また、耐熱樹脂からなるものであり、上記耐熱樹脂が上述のように被塗装物との接着性を有するので、塗装することにより得られる塗膜が被塗装物への密着性に優れたものである。
【００８３】
本発明の被覆用組成物は、上述の構成からなるものであるので、塗料組成物として被覆物品の作製に好適に用いることができる。
上記被覆物品の作製は、本発明の被覆用組成物を被塗装物上に塗布し、必要に応じて乾燥することにより塗布膜を得ることよりなる。
【００８４】
上記被塗装物は、その種類に応じて予め脱脂処理、粗面化処理等の表面処理を行ったものであってもよい。上記粗面化処理の方法としては特に限定されず、例えば、酸又はアルカリによるケミカルエッチング、陽極酸化（アルマイト処理）、サンドブラスト等が挙げられる。上記表面処理は、上記被覆用組成物をハジキを生じず均一に塗布することができる点、及び、被塗装物と塗布膜との密着性が向上する点から、行うことが好ましい。
【００８５】
上記塗布の方法としては特に限定されず、例えば、スプレー塗装、ロール塗装、ドクターブレードによる塗装、ディップ（浸漬）塗装、含浸塗装、スピンフロー塗装、カーテンフロー塗装等が挙げられる。
上記乾燥としては特に限定されず、例えば、従来公知の方法等が用いられ、６０〜３００℃の温度で５〜６０分間行うことが好ましい。
【００８６】
上記被覆物品の作製は、上記塗膜の上に上塗り塗膜を積層させない上述のワンコートの場合、上記塗布膜を得た後、この塗布膜を焼成することにより塗膜を得るものである。上記焼成としては特に限定されず、例えば、従来公知の方法等が用いられ、上記含フッ素重合体、上記耐熱樹脂等の種類によるが、通常、２６０〜４１０℃で１０〜３０分間行う。
【００８７】
上記被覆物品の作製は、上記塗膜の上に上塗り塗膜を積層させる上述のツーコートの場合、上記塗布膜を得た後、この塗布膜上に上塗り塗料を塗布し、必要に応じて乾燥し、次いで焼成することにより被覆用組成物からなる塗膜と、上塗り塗料からなる上塗り塗膜とを得るものである。
【００８８】
本明細書において、上記「上塗り塗料」は、上記塗布膜上に塗布する塗料であって、上塗り用含フッ素重合体からなるものである。上記上塗り用含フッ素重合体は、主鎖又は側鎖を構成する炭素原子に直接結合しているフッ素原子を有する重合体である。上記上塗り用含フッ素重合体は、主鎖又は側鎖を構成する炭素原子に直接結合しているフッ素原子を有する重合体である点で上記含フッ素重合体と共通するが、上記上塗り塗料に配合されている点で、本発明の被覆用組成物に配合されている上記含フッ素重合体とは概念上異なるものである。上記上塗り用含フッ素重合体は、上記上塗り塗膜中に存在することにより、被塗装物に非粘着性、潤滑性等を付与することができ、上記含フッ素重合体と親和性を有するので上記塗膜との密着性も向上することができる。
【００８９】
上記上塗り用含フッ素重合体としては特に限定されず、例えば、ＰＴＦＥ、ＰＦＡ、ＦＥＰ等が挙げられるが、上記塗膜と上塗り塗膜との層間密着性を向上させる点から、本発明の被覆用組成物における上記含フッ素重合体と同じもの、又は、溶融加工性の有無等の性質が類似するものが好ましい。上記上塗り塗料としては、主成分がＰＴＦＥであるＰＴＦＥ系塗料、主成分がＰＦＡであるＰＦＡ系塗料、主成分がＦＥＰであるＦＥＰ系塗料等が挙げられる。
【００９０】
上記上塗り塗料は、上記上塗り用含フッ素重合体とともに、塗装性、得られる塗膜の性質向上等を目的として、更に、上述の被覆用組成物に用い得る各種添加剤と同様の添加剤を配合してなるものであってもよい。
上記上塗り塗料は、例えば、主成分がＰＴＦＥ、ＰＦＡ又はＦＥＰである場合、水性ディスパージョン系塗料、溶剤系塗料等の液状塗料が挙げられ、主成分がＰＦＡ又はＦＥＰである場合、粉体塗料が挙げられる。
【００９１】
上記塗布膜は、上記上塗り塗料として液状塗料を用いる場合、通常、上記上塗り塗料を塗布する前に焼成を行わないが、必要に応じて焼成を行ってもよい。上記上塗り塗料を塗布する前の焼成は、工程の簡略化や、エネルギー、労力、時間等の低減を図ることができる点で、行わないことが好ましい。
上記塗布膜は、上記上塗り塗料として粉体塗料を用いる場合、通常、上記上塗り塗料を塗布する前に焼成を行う。
【００９２】
上記上塗り塗料の塗布の方法としては特に限定されず、例えば、上記上塗り塗料が液状塗料である場合、本発明の被覆用組成物を塗布する方法と同様の方法等が挙げられ、上記上塗り塗料が粉体塗料である場合、静電スプレー塗装、流動浸漬塗装、ロトライニング法等が挙げられる。
上記上塗り塗料を塗布した後の乾燥及び焼成は、それぞれ上述の被覆用組成物を塗布した後に行う乾燥及び焼成と同様の条件で行うことができる。
【００９３】
上記被覆物品の作製は、上述のツーコートの場合、上記上塗り塗料の代わりにフィルムを用いることにより上記上塗り塗膜を得るものであってもよい。
本明細書において、上記フィルムは、主として上記上塗り用含フッ素重合体からなるものであり、フィルム状に成形されたものである。上記上塗り塗膜の形成に上記フィルムを用いる場合、上記塗布膜上に上記フィルムを載置し、加熱圧着することにより上記塗布膜と上記フィルムとを密着させる等の従来公知の方法等を用いることができる。
【００９４】
焼成後における上記塗膜の膜厚及び上記上塗り塗膜の膜厚としては特に限定されず、被覆物品の用途によるが、上記塗膜の膜厚が１〜１００μｍであり、上記上塗り塗膜の膜厚が１０〜２００μｍであることが好ましい。
【００９５】
上記塗膜は、上述のワンコートにより上記被塗装物上に形成されたものである場合、上記含フッ素重合体が有する非粘着性、潤滑性等を被塗装物に付与することができ、上述のツーコートにより上記塗膜の上に上塗り塗膜が積層されたものである場合、被塗装物との密着性と上記上塗り塗膜との密着性の両方に優れたものである。
【００９６】
上記被覆物品は、被塗装物と、上記塗膜とからなるものであって、上記塗膜は、上記被塗装物上に塗装することにより得られたものである。上記被覆物品は、少なくとも上記被塗装物と上記塗膜とからなるものであれば、更に、上記上塗り塗膜を有するものであってもよい。
【００９７】
上記被塗装物としては特に限定されず、例えば、鉄、アルミニウム、銅等の金属単体及びこれらの合金類等の金属；ホーロー、ガラス、セラミックス等の非金属無機材料等が挙げられる。上記合金類としては、ステンレス等が挙げられる。
【００９８】
上記被覆物品は、上述のワンコートに用いた含フッ素重合体、又は、上述のツーコートに用いた上塗り用含フッ素重合体が有する特性を利用した用途に使用することができる。
上記被覆物品としては特に限定されず、例えば、上記特性として非粘着性を利用する場合、フライパン、グリル鍋、圧力鍋、その他の各種鍋、炊飯器、餅つき器、オーブン、ホットプレート、パン焼き型、包丁、ガステーブル等の調理器具；電気ポット、製氷トレー等の飲食用容器；練りロール、圧延ロール、コンベアホッパー等の食品工業用部品；オフィスオートメーション機器〔ＯＡ〕用ロール、ＯＡ用ベルト、製紙ロール、フィルム製造用カレンダーロール等の工業用品；発泡スチロール成形用等の金型、合板・化粧板製造用離型板等の成形金型離型；レンジフード等の厨房用品；コンベアーベルト等の冷凍食品製造装置等が挙げられる。
【００９９】
上記被覆物品としては、また、上記特性として滑り性を利用する場合、のこぎり、やすり等の工具；アイロン等の家庭用品；金属箔；食品加工機、包装機、紡繊機械等のすべり軸受；カメラ・時計の摺動部品；自動車部品等が挙げられる。
【０１００】
【実施例】
以下に実施例を掲げて本発明を更に詳しく説明するが、本発明はこれら実施例のみに限定されるものではない。以下、「％」「部」は、それぞれ質量％、質量部を表す。
製造例１ ポリエーテルスルホン樹脂水性分散体の調製
数平均分子量約２４０００のポリエーテルスルホン樹脂〔ＰＥＳ〕６０部及び脱イオン水６０部を、セラミックボールミル中でＰＥＳからなる粒子が完全に粉砕されるまで約１０分間攪拌した。次いで、Ｎ−メチル−２−ピロリドン〔ＮＭＰ〕１８０部を添加し、更に、４８時間粉砕し、分散体を得た。得られた分散体を更にサンドミルで１時間粉砕し、ＰＥＳ濃度が約２０％のＰＥＳ水性分散体を得た。ＰＥＳ水性分散体中のＰＥＳからなる粒子の粒子径は、２〜３μｍであった。
【０１０１】
製造例２ ポリアミドイミド樹脂水性分散体の調製
固形分２９％のポリアミドイミド樹脂〔ＰＡＩ〕ワニス（ＮＭＰを７１％含む）を水中に投入してＰＡＩを析出させた。これをボールミル中で４８時間粉砕してＰＡＩ水性分散体を得た。得られたＰＡＩ水性分散体において、固形分は、２０％であり、ＰＡＩからなる粒子の平均粒子径は、２μｍであった。
【０１０２】
実施例１
製造例２で得られたＰＡＩ水性分散体に、ポリテトラフルオロエチレン〔ＰＴＦＥ〕水性分散体（平均粒子径０．２８μｍ、固形分６０％、分散剤としてポリエーテル系ノニオン界面活性剤（ＨＬＢ値＝１４）をＰＴＦＥの固形分１００部に対して６部含有している）を、ＰＡＩが、ＰＡＩ及びＰＴＦＥの合計固形分質量の２０％となるように加え、増粘剤としてメチルセルロースをＰＴＦＥの固形分質量に対して０．７％添加し、分散安定剤としてポリオキシエチレントリデシルエーテル（ＨＬＢ値＝１０）をＰＴＦＥの固形分１００部に対して６部添加して、ＰＴＦＥの固形分３４％の塗料組成物を得た。
得られた塗料組成物約１００ｍｌを４０℃、３００ｒｐｍの条件で６時間攪拌したが、凝集物の発生はなく、機械的安定性は良好であった。
【０１０３】
得られた塗料組成物について、下記の評価を行った。
（評価用塗装板の作製）
厚さ２．０ｍｍのアルミニウム板（Ａ−１０５０Ｆ）の表面をアセトンで脱脂した後、ＪＩＳ Ｂ １９８２に準拠して測定した表面粗度Ｒａ値が２．５〜３．５μｍとなるようにサンドブラストを行い、粗面化した。エアーブローにより表面のダストを除去した後、得られた塗料組成物を、重力式スプレーガンＲＧ−２型（商品名、アネスト岩田社製、ノズル径１．０ｍｍ）を用い、乾燥膜厚が１０〜１５μｍとなるように、吹き付け圧力０．２ＭＰａでスプレー塗装により塗布した。得られた塗布膜を８０〜１００℃で１５分間乾燥し、室温まで冷却した。得られた塗布膜の上に、上塗り塗料としてＰＴＦＥを含有する水性塗料ポリフロンＰＴＦＥ ＥＫ−３７００Ｃ−２０１（商品名、ダイキン工業社製）を同様の条件でスプレー塗装により塗布し、８０〜１００℃で１５分間乾燥した。その後３８０℃で２０分間焼成し、膜厚約２０μｍの上塗り塗膜を作製し、評価用塗装板を得た。
【０１０４】
（塗装性及び外観）
上記評価用塗装板の作製過程において、上塗り塗料を塗布した時の塗装性と、上塗り塗料を塗布し、次いで乾燥、焼成した後の塗装板の外観とをそれぞれ目視で観察し、評価を行った。
【０１０５】
上塗り塗料の塗装性は良好で、均一な塗膜を形成することができ、焼成後の塗膜外観も均一で良好であった。
【０１０６】
実施例２
製造例１で得られたＰＥＳ水性分散体、及び、製造例２で得られたＰＡＩ水性分散体を、ＰＥＳが、ＰＥＳとＰＡＩとの合計固形分質量の８５％となるように混合し、これにＰＴＦＥ水性分散体（平均粒子径０．２８μｍ、固形分６０％、分散剤としてポリエーテル系ノニオン界面活性剤（ＨＬＢ値＝１４）をＰＴＦＥの固形分１００部に対して６部含有している）を、ＰＥＳ及びＰＡＩが、ＰＥＳ、ＰＡＩ及びＰＴＦＥの合計固形分質量の２０％となるように加え、増粘剤としてメチルセルロースをＰＴＦＥの固形分質量に対して０．７％添加し、分散安定剤としてポリオキシエチレントリデシルエーテル（ＨＬＢ値＝１０）をＰＴＦＥの固形分１００部に対して６部添加して、ＰＴＦＥの固形分３４％の塗料組成物を得た。
得られた塗料組成物約１００ｍｌを４０℃、３００ｒｐｍの条件で６時間攪拌したが、凝集物の発生はなく、機械的安定性は良好であった。
得られた塗料組成物を用いて、実施例１と同様に評価用塗装板を作製し、評価を行った。上塗り塗料の塗装性は良好で、均一な塗膜を形成することができ、焼成後の塗膜外観も均一で良好であった。
【０１０７】
比較例
ポリオキシエチレントリデシルエーテルに替えてポリオキシエチレンオクチルフェニルエーテル（ＨＬＢ値＝１３）を使用した以外は、実施例２と同様に塗料組成物を得た。
得られた塗料組成物約１００ｍｌを４０℃、３００ｒｐｍの条件で攪拌したが、約３０分で全体がゲル化した。
得られた塗料組成物を用いて、実施例１と同様に評価用塗装板を作製し、評価を行った。上塗り塗料は、塗装時にハジキが発生し、塗装性に劣っていた。焼成後の塗膜外観は、上塗り塗料の塗装時に発生したハジキの箇所に斑点が認められ、劣っていた。
【０１０８】
【発明の効果】
本発明の被覆用組成物は、上述の構成を有するので、内分泌撹乱物質を発生するおそれがなく、機械的安定性及び貯蔵安定性が良好で、被塗装物への密着性に優れた塗膜を得ることができるものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to coating compositions, coatings and coated articles.
[0002]
[Prior art]
Fluoropolymers such as polytetrafluoroethylene [PTFE] have excellent properties such as heat resistance and electrical insulation, and the molded articles have a low coefficient of friction and excellent non-adhesiveness. The surface properties exhibit chemical resistance, water / oil repellency, release properties, slidability and the like.
[0003]
Since the fluorinated polymer has such properties, for example, it is prepared into a coating composition, and is applied on an object to be coated to provide a coating film made of the fluorinated polymer, thereby releasing the mold. There are a wide range of applications in the fields of mold materials, household appliances such as rolls for office automation [OA] equipment, irons, kitchen utensils such as frying pans and hot plates, food industry, electric industry, and machine industry.
[0004]
On the other hand, the fluorine-containing polymer has a problem of poor adhesion to the object to be coated due to its non-adhesiveness. For the purpose of improving the adhesion, a primer containing a binder resin such as a heat-resistant resin and a fluorine-containing polymer is applied as an undercoat on an object to be coated in advance.
[0005]
When the fluoropolymer is obtained by, for example, a method such as emulsion polymerization, since water is used as a medium, the primer composed of the fluoropolymer is often an aqueous dispersion. The aqueous primer composed of this aqueous dispersion has a fluoropolymer and a binder resin dispersed in the form of particles, respectively, but mechanical stability and storage stability have been ensured by adding a surfactant. .
[0006]
As the aqueous primer to which the surfactant is added, one comprising an adhesion aid such as polyamideimide, a modified tetrafluoroethylene polymer having a core / shell structure, and a tetrafluoroethylene copolymer having a non-core / shell structure is used. (For example, see Patent Document 1).
[0007]
As the surfactant of this aqueous primer, an anionic surfactant or a nonionic surfactant is added during the polymerization of the modified tetrafluoroethylene polymer, but the type and amount of the surfactant are not described.
[0008]
Aqueous primers to which a surfactant has been added include those made of polyethersulfone, polyamideimide and / or polyimide, and fluororesins such as PTFE (see, for example, Patent Document 2).
[0009]
As the surfactant of the aqueous primer, an anionic surfactant or a nonionic surfactant is added in an amount of 1 to 15% by mass based on the solid content of the paint, but the type is not described.
[0010]
As a nonionic surfactant added to an aqueous primer for many years, an alkylphenol-based nonionic surfactant represented by polyoxyethylene octyl phenyl ether has been used, but alkylphenol may be an endocrine disrupting substance (environmental hormone). Therefore, development of a nonionic surfactant which does not generate an endocrine disrupting substance is desired from an environmental point of view.
[0011]
A composition for coating using a nonionic surfactant which does not generate endocrine disrupting substances includes a compound represented by the formula R'-O- (C₂H₄O)_n-H (wherein, R 'represents a branched saturated aliphatic hydrocarbon group having 10 to 15 carbon atoms having one secondary carbon atom in the middle of the main chain; There is a PTFE-containing aqueous dispersion composition using a nonionic surfactant having an HLB value of 12 to 14 represented by an integer (see, for example, Patent Document 3).
[0012]
However, since this PTFE-containing aqueous dispersion composition does not contain a binder resin such as a heat-resistant resin, there is a problem that a coating film obtained by coating is inferior in adhesion to an object to be coated. It is not described that it can be used as a primer.
[0013]
[Patent Document 1]
JP-A-59-199774
[Patent Document 2]
International Publication No. 99/64523 pamphlet
[Patent Document 3]
JP-A-11-152385 (pages 1-4)
[0014]
[Problems to be solved by the invention]
In view of the above circumstances, an object of the present invention is to use a surfactant that does not generate an endocrine disrupting substance, has good mechanical stability and storage stability, and has excellent adhesion to an object to be coated. To provide a coating composition capable of obtaining the following.
[0015]
[Means for Solving the Problems]
The present invention is a coating composition comprising an aqueous dispersion containing a heat-resistant resin, a fluoropolymer and a surfactant, wherein the surfactant is a non-alkylphenol-type nonionic surfactant, and the non-alkylphenol The nonionic surfactant is a coating composition characterized by being 0.1 to 20 parts by mass based on 100 parts by mass of the solid content of the fluoropolymer.
Hereinafter, the present invention will be described in detail.
[0016]
The coating composition of the present invention is composed of an aqueous dispersion, and the aqueous dispersion is composed of a heat-resistant resin, a fluoropolymer and a surfactant. The surfactant is a non-alkylphenol-type nonionic surfactant.
The coating composition of the present invention is capable of forming a coating film on the object to be coated by applying the composition to the object to be coated. In the present specification, “coating” for the coating composition means a step of applying the coating composition, drying if necessary, and then firing.
[0017]
Since the coating film has a difference in surface tension between the fluoropolymer and the heat-resistant resin, the fluoropolymer floats during firing, and the fluoropolymer is mainly disposed on the surface side of the coating film. The heat-resistant resin is mainly disposed on the object to be coated. Since the heat-resistant resin has adhesiveness to the object to be coated, the coating film can have excellent adhesion to the object to be coated.
[0018]
The above-mentioned coating film may be formed by laminating a top coating film on the coating film, if necessary. The above top coat is usually formed by applying a top coat composed of a fluoropolymer for top coat. The above-mentioned coating film, when a topcoat coating film is laminated on the coating film, since the fluoropolymer has an affinity with the above-mentioned fluoropolymer for topcoat, is also excellent in adhesion to the topcoat coating film. .
[0019]
When a top coat is laminated on the above-mentioned coat, application of the top coat is performed by applying the coating composition, drying and baking if necessary, applying the top coat, and This is a step of drying and then firing.
[0020]
In the present specification, a product having the object to be coated and the coating film is referred to as a coated article. The coated article may further have the top coat.
[0021]
In the present specification, the method for producing the coated article is referred to as one-coat when the overcoat film is not laminated on the coating film. The one coat is formed by applying the coating composition on the object to be coated, drying if necessary, and then firing.
[0022]
In the present specification, the method for producing the coated article is referred to as two-coating when the overcoat film is laminated on the coating film. The two-coat is usually applied the coating composition on the object to be coated, dried if necessary, and then without baking, apply the top coating, and dried if necessary, It consists of firing. In the case of the two-coat, the coating composition is used as an undercoat of the top coat and functions as a primer.
[0023]
In the coating composition of the present invention, the above-mentioned aqueous dispersion mainly contains particles made of a fluoropolymer as a dispersoid and an aqueous medium as a dispersion medium. The non-alkylphenol-type nonionic surfactant forms micelles in the aqueous medium, incorporates the fluoropolymer into the micelles, and incorporates the fluoropolymer into the aqueous medium as oil-in-water particles. It is to disperse.
[0024]
In the coating composition of the present invention, the aqueous dispersion comprises a fluoropolymer.
The fluorine-containing polymer is a polymer having a fluorine atom directly bonded to a carbon atom constituting a main chain or a side chain. The fluoropolymer may be non-melt-processable or melt-processable.
[0025]
The fluorine-containing polymer is obtained by polymerizing a fluorine-containing monoethylenically unsaturated hydrocarbon (a).
The above-mentioned fluorine-containing monoethylenically unsaturated hydrocarbon (a) (hereinafter referred to as “unsaturated hydrocarbon (a)”) refers to a vinyl group in which a hydrogen atom is partially or entirely substituted by a fluorine atom, It is an unsaturated hydrocarbon having one in it.
[0026]
The unsaturated hydrocarbon (a) may be substituted with a halogen atom other than a fluorine atom such as a chlorine atom and / or a fluorinated methyl group such as a trifluoromethyl group. However, the unsaturated hydrocarbon (a) excludes trifluoroethylene described below.
[0027]
The unsaturated hydrocarbon (a) is not particularly limited and includes, for example, tetrafluoroethylene [TFE], hexafluoropropylene [HFP], chlorotrifluoroethylene [CTFE], vinylidene fluoride [VdF], vinyl fluoride [ VF], and these can be used alone or in combination of two or more.
[0028]
The fluoropolymer is a copolymer of at least one kind of the unsaturated hydrocarbon (a) and an unsaturated compound (b) copolymerizable with the unsaturated hydrocarbon (a). Is also good.
As the unsaturated compound (b), a polymer obtained by polymerizing only one or more unsaturated compounds (b) is not used as the fluorine-containing polymer. The above-mentioned unsaturated hydrocarbon in that hydrogen (a) can be used as the above-mentioned fluoropolymer, a polymer obtained by polymerizing only one or more kinds of the above-mentioned unsaturated hydrocarbons (a). This is different from (a).
[0029]
The unsaturated compound (b) is not particularly limited and includes, for example, trifluoroethylene [3FH]; monoethylenically unsaturated hydrocarbons having no halogen atom such as ethylene [Et] and propylene [Pr]. . One or two or more of these can be used.
[0030]
The fluorinated polymer may be a homopolymer, a copolymer, a mixture of a homopolymer and at least one or more copolymers, or at least 2 It may be a mixture comprising at least one kind of copolymer.
[0031]
The homopolymer is not particularly restricted but includes, for example, polytetrafluoroethylene [PTFE], polychlorotrifluoroethylene [PCTFE], polyvinylidene fluoride [PVdF], polyvinyl fluoride [PVF] and the like.
[0032]
The copolymer is not particularly limited, and includes, for example, a binary copolymer, a ternary copolymer and the like. Examples of the above binary copolymer include TFE / HFP copolymer [FEP], TFE / CTFE copolymer, TFE / VdF copolymer, TFE / 3FH copolymer, Et / TFE copolymer [ETFE] ], TFE / Pr copolymers and other TFE-based copolymers; VdF / HFP copolymers; Et / CTFE copolymers [ECTFE]; Et / HFP copolymers and the like. In the present specification, the “TFE-based copolymer” means a product obtained by copolymerizing TFE with one or more other monomers other than TFE. In the TFE-based copolymer, the ratio of other monomers other than TFE added to the TFE-based copolymer is usually 1 mass of the total mass of the TFE and the other monomer. %.
Examples of the terpolymer include a VdF / TFE / HFP copolymer.
[0033]
Other monomers other than the TFE in the TFE-based copolymer may be other monomers (c) copolymerizable with the following TFE. The other monomer (c) has the following general formula:
X (CF₂)_mO_nCF = CF₂
(Wherein, X represents a hydrogen atom, a chlorine atom or a fluorine atom, m represents an integer of 1 to 6, and n represents an integer of 0 or 1) (however, HFP ), The following general formula:
C₃F₇O [CF (CF₃) CF₂O]_p-CF = CF₂
(Wherein, p represents an integer of 1 or 2), or the following general formula:
X (CF₂)_qCY = CH₂
(Wherein, X is the same as described above, Y represents a hydrogen atom or a fluorine atom, and q represents an integer of 1 to 6). One or two or more of these can be used.
[0034]
The other monomer (c) is not particularly limited as long as it is represented by the above general formula. For example, a perfluoroolefin having 4 or more carbon atoms such as perfluorobutylene; perfluoro (methyl vinyl ether) And perfluoro (alkyl vinyl ether) [PAVE] such as perfluoro (ethyl vinyl ether).
Examples of the TFE-based copolymer obtained by copolymerizing TFE and the other monomer (c) include a TFE / PAVE copolymer [PFA].
[0035]
The “mixture comprising a homopolymer and at least one or more copolymers” is not particularly limited, and examples thereof include a mixture of PTFE and PFA, a mixture of PTFE and FEP, and a mixture of PTFE, PFA and FEP. Is mentioned. The “mixture of at least two or more copolymers” is not particularly limited, and includes, for example, a mixture of PFA and FEP.
[0036]
The fluoropolymer is obtained by polymerizing a perfluoroalkyl group-containing ethylenically unsaturated monomer (d) having a perfluoroalkyl group (hereinafter, referred to as “PAE (d)”). It may be. The PAE (d) has the following general formula:
[0037]
Embedded image

[0038]
(Wherein, Rf represents a perfluoroalkyl group having 4 to 20 carbon atoms;¹Represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms;²Represents an alkylene group having 1 to 10 carbon atoms;³Represents a hydrogen atom or a methyl group;⁴Represents an alkyl group having 1 to 17 carbon atoms, r represents an integer of 1 to 10, and s represents an integer of 0 to 10. ).
[0039]
The fluoropolymer may be a homopolymer of the PAE (d) or a copolymer of the PAE (d) and the monomer (e) copolymerizable with the PAE (d). It may be a polymer. The monomer (e) is not particularly limited, and examples thereof include cyclohexyl (meth) acrylate, benzyl (meth) acrylate, polyethylene glycol di (meth) acrylate, N-methylolpropaneacrylamide, and (meth) acryl. (Meth) acrylic acid derivatives such as acid amides and alkyl esters of (meth) acrylic acid having an alkyl group having 1 to 20 carbon atoms; ethylene, vinyl chloride, vinyl fluoride, styrene, α-methylstyrene, p-methyl A substituted or unsubstituted ethylene such as styrene; a vinyl ether such as an alkyl vinyl ether having an alkyl group having 1 to 20 carbon atoms and a halogenated alkyl vinyl ether having an alkyl group having 1 to 20 carbon atoms; Vinyl ketones such as vinyl alkyl ketones having a weight of from 20 to 20; Aliphatic unsaturated polycarboxylic acids and derivatives thereof such as phosphate; butadiene, isoprene, polyenes such as chloroprene.
[0040]
The fluorinated polymer is preferably PTFE, FEP and / or PFA from the viewpoint of excellent non-adhesiveness, slipperiness, heat resistance and the like. For example, PTFE, FEP, PFA, a mixture of PTFE and FEP, PTFE and PFA And the like.
[0041]
The above-mentioned PTFE is TFE, FEP is TFE and HFP, and PFA is TFE and PAVE, respectively. Good.
The above-mentioned trace monomer is not particularly limited. For example, the above unsaturated hydrocarbon (a) such as CTFE; the above unsaturated compound (b) such as 3FH; perfluoro (alkoxy vinyl ether), (perfluoroalkyl) ethylene And the other monomers (c). When the fluorine-containing polymer is the above-mentioned PTFE, the above-mentioned trace monomers further include HFP and PAVE. When the above-mentioned FEP is the above-mentioned FEP, further PAVE is mentioned. Is mentioned. One or more kinds of the above-mentioned trace monomers can be used.
Although the amount of the above-mentioned trace monomer varies depending on the kind, it is usually preferable that the amount is 1% by mass or less of the mass of the fluoropolymer. A more preferred upper limit is 0.5% by mass, a still more preferred upper limit is 0.3% by mass, and a preferred lower limit is 0.01% by mass.
[0042]
The fluorinated polymer is more preferably PTFE and / or FEP. The above “PTFE and / or FEP” means PTFE, FEP, or a mixture of PTFE and FEP.
[0043]
The fluorinated polymer can be obtained, for example, by polymerizing using a conventionally known polymerization method such as emulsion polymerization or suspension polymerization. The fluoropolymer obtained by the above polymerization method is pulverized so that it has an average particle diameter in the above-mentioned range, if desired. The method of pulverization is not particularly limited, and examples thereof include a method in which the fluoropolymer is compressed into a sheet by a roll, pulverized by a pulverizer, and classified.
When the above-mentioned fluoropolymer is obtained by emulsion polymerization or suspension polymerization, it may be used for preparing a coating composition as a dispersion without isolating only the obtained polymer component, or John concentrates the dispersion by adding a surfactant (S1) to the obtained dispersion of the polymer component, and further adds a surfactant (S2) as necessary, to form a coating composition. May be prepared. In the present specification, a product obtained by concentrating a dispersion comprising a fluoropolymer obtained by polymerization and not adding the above-mentioned surfactant (S2) is referred to as “product polymer concentrate”. is there.
[0044]
In the coating composition of the present invention, the fluoropolymer is dispersed as particles in an aqueous medium as described above. The fluoropolymer preferably comprises particles having an average particle diameter of 0.01 to 50 μm. If it is less than 0.01 μm, the dispersibility of the fluoropolymer particles is poor, and the resulting coating composition may be poor in mechanical stability and storage stability. If it exceeds 50 μm, the particles comprising the fluoropolymer lack uniform dispersibility, and when coated using the obtained coating composition, a coating film having a smooth surface cannot be obtained, and the coating film properties may be poor. is there. A more preferred upper limit is 5 μm, a still more preferred upper limit is 0.5 μm, and a more preferred lower limit is 0.05 μm. The above-mentioned mechanical stability refers to a property that hardly generates an aggregate that cannot be re-dispersed even when a strong stirring or a shearing force is applied by a homogenizer or the like at the time of feeding and re-dispersion.
[0045]
In the coating composition of the present invention, the aqueous dispersion comprises a non-alkylphenol-type nonionic surfactant together with the fluoropolymer.
In the present specification, the “non-alkylphenol-type nonionic surfactant” means a nonionic surfactant having no molecular structure derived from alkylenol in the molecular structure.
[0046]
The non-alkylphenol-type nonionic surfactant has the following general formula (I):
R-O-A-H
(Wherein, R represents a linear or branched, saturated or unsaturated, acyclic aliphatic hydrocarbon group having 8 to 19 carbon atoms, or a saturated cyclic aliphatic hydrocarbon having 8 to 19 carbon atoms) A represents a polyoxyalkylene chain having 3 to 25 oxyethylene units and 0 to 5 oxypropylene units.) Is preferable.
In the present specification, the number of carbon atoms of R, the number of oxyethylene units, and the number of oxypropylene units in the general formula (I) are an average of the values of the molecules of the non-alkylphenol-type nonionic surfactant.
[0047]
The acyclic aliphatic hydrocarbon group is an aliphatic hydrocarbon group having no cyclic structure. The saturated cyclic aliphatic hydrocarbon group is an aliphatic hydrocarbon group having a saturated cyclic structure. If the total number of carbon atoms is 8 to 19, the saturated cyclic aliphatic hydrocarbon group may have one or more saturated cyclic structures. If the total number of carbon atoms including the substituent is 8 to 19, the saturated cyclic aliphatic hydrocarbon group has a straight-chain or branched-chain hydrogen atom bonded to a carbon atom of the saturated cyclic structure. The alkyl group may be substituted, and one or more hydrogen atoms may be substituted.
[0048]
In the general formula (I), R is preferably an upper limit of the number of carbon atoms in terms of excellent dispersibility of particles made of a fluoropolymer and excellent mechanical stability and storage stability of the obtained coating composition. 16, a more preferred upper limit is 14, and a preferred lower limit is 10. More preferably, R has 13 carbon atoms. It is particularly preferable that R is a saturated acyclic aliphatic hydrocarbon group having 13 carbon atoms, such as a tridecyl group and an isotridecyl group.
[0049]
A in the general formula (I) represents a polyoxyalkylene chain having 3 to 25 oxyethylene units and 0 to 5 oxypropylene units. In the present specification, the “oxyethylene unit” is an oxyethylene group, and the “oxypropylene unit” is an oxypropylene group. In the present specification, the “polyoxyalkylene chain having 3 to 25 oxyethylene units and 0 to 5 oxypropylene units” refers to 3 to 25 oxyethylene units and 0 to 5 oxypropylene units. It means a polyoxyalkylene chain consisting of units.
The polyoxyalkylene chain is preferably composed only of an oxyethylene unit and an oxypropylene unit, but the oxypropylene unit may not be present in the polyoxyalkylene chain.
[0050]
When the number of the oxypropylene units exceeds 5, the dissolving power of the non-alkylphenol-type nonionic surfactant is reduced, so that the dispersibility of the particles made of the fluoropolymer is reduced, and the mechanical stability of the coating composition and The storage stability may be poor. The smaller the number of the oxypropylene units, the more preferable, and the preferable upper limit is three. More preferably, the oxypropylene unit is not present in the polyoxyalkylene chain.
A preferred upper limit of the oxyethylene unit of the polyoxyalkylene chain is 7, although it depends on the number of carbon atoms of R, and a more preferred upper limit is 6.
[0051]
The polyoxyalkylene chain preferably has 3 to 7 oxyethylene units and 0 to 3 oxypropylene units, and has 3 to 6 oxyethylene units, and the oxypropylene unit Is more preferably not present.
[0052]
The bond between —O— in the general formula (I) and the polyoxyalkylene chain of A in the general formula (I) is such that a carbon atom in the polyoxyalkylene chain is adjacent to —O— in the general formula (I). For example, when the oxyethylene unit in the polyoxyalkylene chain and -O- are bonded, the above-mentioned -O- and the adjacent oxyethylene unit are -O- (CH₂CH₂O) —bonded in the orientation represented by-.
[0053]
The non-alkylphenol type nonionic surfactant preferably has an HLB value of less than 12. The non-alkylphenol-type nonionic surfactant used as the above-mentioned surfactant (S2) to be added to the resulting polymer concentrate preferably has an HLB value of less than 12.
The non-alkylphenol-type nonionic surfactant has a unique HLB value based on its molecular structure, like a general surfactant. The HLB value is an index of the balance between hydrophilicity and hydrophobicity of a surfactant. Generally, the higher the hydrophilicity, the larger the value, and the higher the hydrophobicity, the smaller the value. In the present specification, the “HLB value” means a value calculated based on the Griffin calculation method.
[0054]
When the non-alkylphenol-type nonionic surfactant has the HLB value of 12 or more, particles made of a fluoropolymer are likely to aggregate, and the mechanical stability of the obtained coating composition may be insufficient. In addition, when the obtained coating composition is applied to a substrate and dried, and then a topcoat comprising a fluoropolymer for topcoat is applied, cissing is likely to occur. The above HLB value is more preferably 11 or less, further preferably 10 or less. If the HLB value is within the above range, it is more preferably 5 or more from the viewpoint that the dispersibility of the obtained coating composition is not deteriorated. A more preferred lower limit of the HLB value is 7, and a particularly preferred lower limit is 9.
[0055]
As the non-alkylphenol-type nonionic surfactant, one or more kinds can be used. When two or more non-alkylphenol-type nonionic surfactants are used, the HLB value can be calculated from the respective HLB values and the mixing ratio. When two or more non-alkylphenol-type nonionic surfactants are used, the HLB value calculated as described above is preferably 12 or less. As described above, when the non-alkylphenol-type nonionic surfactant is composed of one having an HLB value of less than 12, as the non-alkylphenol-type nonionic surfactant to be used, at least one of those having an HLB value of less than 12 is used. , HLB values of 12 or more may be used alone or in combination.
The non-alkylphenol-type nonionic surfactant used as the above-mentioned surfactant (S2) to be added to the produced polymer concentrate can be used alone or in combination of two or more, provided that the calculated HLB value is less than 12. For example, one or more of those having an HLB value of 12 or more may be used together with those having an HLB value of less than 12.
[0056]
In the coating composition of the present invention, the aqueous dispersion may be one using an anionic surfactant or a cationic surfactant, if necessary, together with the non-alkylphenol-type nonionic surfactant. As the surfactant or the cationic surfactant, for example, a fluorinated surfactant having a fluorine atom bonded thereto may be used.
[0057]
As described above, the coating composition of the present invention uses a non-alkylphenol-type nonionic surfactant as a surfactant, and optionally uses an anionic surfactant or a cationic surfactant. . Alkylphenol-based nonionic surfactants used in conventional coating compositions, when thermally decomposed by applying or baking, may produce an alkylphenol that may be an endocrine disrupting substance, but the non-alkylphenol-type nonionic Since the surfactant has no molecular structure derived from alkyl phenol in the structure thereof unlike the alkylphenol-based nonionic surfactant, there is no possibility that the above-mentioned alkyl phenol is generated even when thermally decomposed.
[0058]
In the coating composition of the present invention, the non-alkylphenol-type nonionic surfactant is 0.1 to 20 parts by mass based on 100 parts by mass of the solid content of the fluoropolymer.
In the present specification, the “solid content” means a solid at 20 ° C. In the present specification, the “solid content of the fluoropolymer” refers to a coating composition that is applied on a substrate, dried at a temperature of 80 to 100 ° C. or lower, and baked at 380 to 400 ° C. for 45 minutes. It means the solid content of the fluoropolymer in the later residue.
[0059]
When the non-alkylphenol-type nonionic surfactant is less than 0.1 part by mass with respect to 100 parts by mass of the solid content of the fluoropolymer, particles composed of the fluoropolymer precipitate in the obtained composition. Easy and poor storage stability. If the amount exceeds 20 parts by mass, the composition obtained will have an increased viscosity and the coating workability will be poor. A more preferred lower limit is 5 parts by mass, and a still more preferred lower limit is 7 parts by mass.
The coating composition of the present invention is obtained by blending a non-alkylphenol-type nonionic surfactant in the above-described amount, and thus has excellent mechanical stability and storage stability.
[0060]
In the coating composition of the present invention, the aqueous dispersion comprises a heat-resistant resin together with the fluoropolymer and a non-alkylphenol-type nonionic surfactant.
The heat-resistant resin may be any resin that is generally recognized as having heat resistance, and is preferably a resin having a continuous usable temperature of 150 ° C. or higher.
The heat-resistant resin is not particularly limited, and examples thereof include polyamide imide resin, polyimide resin, polyether sulfone resin, polyether imide resin, polyether ether ketone resin, aromatic polyester resin, and polyarylene sulfide resin. As the heat-resistant resin, one type or two or more types can be used.
[0061]
The polyamide imide resin [PAI] is a resin comprising a polymer having an amide bond and an imide bond in a molecular structure. The PAI is not particularly limited, and may be, for example, a reaction between an aromatic diamine having an amide bond in the molecule and an aromatic tetravalent carboxylic acid such as pyromellitic acid; and an aromatic trivalent carboxylic acid such as trimellitic anhydride. Reaction with diamine such as 4,4-diaminophenyl ether or diisocyanate such as diphenylmethane diisocyanate; high molecular weight polymer obtained by each reaction such as reaction between dibasic acid having aromatic imide ring in the molecule and diamine Resins. As the PAI, those made of a polymer having an aromatic ring in the main chain are preferable from the viewpoint of excellent heat resistance.
[0062]
The polyimide resin [PI] is a resin composed of a polymer having an imide bond in the molecular structure. The PI is not particularly limited, and examples thereof include a resin made of a high molecular weight polymer obtained by a reaction of an aromatic tetravalent carboxylic anhydride such as pyromellitic anhydride or the like. The PI is preferably a polymer composed of a polymer having an aromatic ring in the main chain, from the viewpoint of excellent heat resistance.
[0063]
The polyether sulfone resin [PES] has the following general formula:
[0064]
Embedded image

[0065]
It is a resin which consists of a polymer which has a repeating unit represented by these. The PES is not particularly limited, and examples thereof include a resin made of a polymer obtained by polycondensation of dichlorodiphenyl sulfone and bisphenol.
Each of PAI, PI and PES may be composed of one kind or two or more kinds.
[0066]
The heat-resistant resin, the object to be coated, can improve the adhesion between the coating film obtained by coating the coating composition, from the point that this adhesion can be maintained even at a high temperature, PAI and / or PI are more preferred. The “PAI and / or PI” means PAI, PI, or a mixture of PAI and PI.
[0067]
The heat-resistant resin is excellent in adhesion to an object to be coated, has sufficient heat resistance even at the temperature at the time of firing when forming the coating film, and the obtained coating film has excellent corrosion resistance and steam resistance. Thus, PAI, PI and / or PES are preferred. The above “PAI, PI and / or PES” means PAI, PI, PES, a mixture of PAI and PI, a mixture of PES and PAI, a mixture of PES and PI, and a mixture of PES, PAI and PI. I do.
[0068]
The heat-resistant resin is more preferably PES, PAI and / or PI, because it is excellent in heat resistance and adhesion to an object to be coated, and particularly excellent in corrosion resistance and water vapor resistance of the coating film. The above “PES, PAI and / or PI” means a mixture of PES and PAI, a mixture of PES and PI, or a mixture of PES, PAI and PI. More preferably, the heat resistant resin is a mixture of the above PES and PAI.
In the coating composition of the present invention, PES is preferably 65 to 85% by mass of the total mass of PES and PAI and / or PI. If the amount is less than 65% by mass, the water vapor resistance of the coating film obtained from the coating composition may decrease. If the amount exceeds 85% by mass, the corrosion resistance of the coating film may decrease.
[0069]
In the coating composition of the present invention, the heat-resistant resin is dispersed in an aqueous medium described below as particles or dissolved in an aqueous medium. When the heat-resistant resin is dispersed as particles in an aqueous medium, the particles made of the heat-resistant resin are preferably particles dispersed in the aqueous medium and having an average particle diameter of 0.1 to 10 μm. When the average particle size of the heat-resistant resin is within the above range, the corrosion resistance of the coating film obtained from the coating composition is good.
[0070]
In the coating composition of the present invention, the above-mentioned aqueous dispersion may be composed of another resin, if necessary, together with the above-mentioned heat-resistant resin, fluoropolymer and non-alkylphenol-type nonionic surfactant. By blending the above-mentioned other resins, it is possible to improve the film forming property, corrosion resistance and the like of the coating film obtained from the coating composition.
[0071]
The other resins are not particularly limited, and include, for example, phenol resin, urea resin, epoxy resin, urethane resin, melamine resin, polyester resin, polyether resin, acrylic resin, acrylic silicone resin, silicone resin, silicone polyester resin, and the like. No.
[0072]
In the coating composition of the present invention, the above-mentioned aqueous dispersion mainly contains particles made of a fluoropolymer as a dispersoid and an aqueous medium as a dispersion medium. The aqueous medium is not particularly limited as long as it contains water, and examples thereof include a mixture of water and an organic liquid, and water.
[0073]
The organic liquid is not particularly limited, and examples thereof include aromatic hydrocarbon solvents such as toluene, xylene, trimethylbenzene, methylethylbenzene, propylbenzene, and butylbenzene; saturated hydrocarbon solvents having 6 to 12 carbon atoms; -Nitrogen-containing solvents such as -methyl-2-pyrrolidone, 2-pyrrolidone, N, N-dimethylacetamide; lactones such as γ-butyrolactone; acyclic esters such as butyl acetate; ketones such as methyl isobutyl ketone and methyl ethyl ketone Glycol ethers such as butyl cellosolve; glycols such as ethylene glycol, triethylene glycol and propylene glycol; monoalcohols such as 1-butanol and diacetone alcohol.
[0074]
As the aromatic hydrocarbon solvent, commercially available Solvesso 100, Solvesso 150, Solvesso 200 (all trade names, manufactured by Exxon Chemical Co., Ltd.) and the like may be used. As the saturated hydrocarbon solvent, a commercially available mineral spirit (Japanese Industrial Standard, Industrial Gasoline No. 4) or the like may be used. The organic liquids may be used alone or in combination of two or more.
As the organic liquid, it is preferable to use a nitrogen-containing solvent, and it is more preferable to use N-methyl-2-pyrrolidone or dimethylacetamide.
[0075]
The aqueous medium may be, for example, one in which various additives described below are dissolved or dispersed. The aqueous medium may be the aqueous medium used for the polymerization of the fluoropolymer, or may be prepared separately from the aqueous medium used for the polymerization. Or when obtained by suspension polymerization, the aqueous medium used for the polymerization of the fluoropolymer can be used as it is.
[0076]
The coating composition of the present invention, for the purpose of improving paintability, properties of a coating film obtained from the coating composition, and the like, further comprises various additives commonly used in general coating compositions. It may be something. The various additives are not particularly limited and are selected according to the use of a coated article described below obtained by using the coating composition of the present invention, and include, for example, a leveling agent, a solid lubricant, a pigment, a filler, Pigment dispersant, antisettling agent, moisture absorber, surface conditioner, thixotropic agent, viscosity modifier, gelling agent, ultraviolet absorber, light stabilizer, plasticizer, color separation inhibitor, anti-skinning agent , An anti-scratch agent, a fungicide, an antibacterial agent, an antioxidant, an antistatic agent, a silane coupling agent and the like.
[0077]
The coating composition of the present invention preferably has a viscosity at 25 ° C. of 0.1 to 50,000 mPa · s. When the viscosity is less than 0.1 mPa · s, sagging or the like is apt to occur at the time of application on the object to be coated, and it may be difficult to obtain a target film thickness. The workability may be deteriorated, the thickness of the obtained coating film may not be uniform, and the surface smoothness may be poor. A more preferred lower limit is 1 mPa · s, and a more preferred upper limit is 30,000 mPa · s. The above viscosity is a value obtained by measuring using a BM type single cylindrical rotational viscometer (manufactured by Tokyo Keiki Co., Ltd.).
[0078]
The coating composition of the present invention may be a coating composition used for the one-coat described above or a primer composition used for the two-coat described above, but is suitable for the primer composition.
[0079]
When the coating composition of the present invention is used as a primer composition, the heat-resistant resin is preferably 15 to 50% by mass of the total solid content of the heat-resistant resin and the fluoropolymer.
In the present specification, the "total solid content mass of the heat-resistant resin and the fluoropolymer" means that after coating the coating composition of the present invention on an object to be coated, the composition is dried at a temperature of 80 to 100C or lower. , The total mass of the heat-resistant resin and the fluoropolymer in the residue after baking at 380 to 400 ° C for 45 minutes.
[0080]
When the heat-resistant resin is less than 15% by mass of the total solid content of the heat-resistant resin and the fluoropolymer, the heat-resistant resin is small, so that the adhesion between the coating film obtained from the coating composition and the object to be coated is small. May be insufficient. If it exceeds 50% by mass, the amount of the fluoropolymer is small, so that the adhesion between the coating film and the overcoat film may be insufficient. A more preferred lower limit is 20% by mass, and a more preferred upper limit is 40% by mass.
[0081]
The coating composition of the present invention can be prepared by a conventionally known method or the like.For example, the above heat-resistant resin, a fluorine-containing polymer, a non-alkylphenol-type nonionic surfactant and other resins to be blended as necessary Aqueous dispersion is obtained by appropriately mixing and dispersing in the above aqueous medium, and if necessary, the viscosity is adjusted to be easily applied by using a viscosity modifier or the like, and various additives other than the above viscosity modifier are optionally added. And the like. The coating composition of the present invention may be prepared by preparing dispersions of the heat-resistant resin, fluoropolymer, pigment and the like in advance, and mixing the resulting dispersions. . For the preparation of each of the above dispersions, the above-mentioned non-alkylphenol-type nonionic surfactant may be used as necessary.
[0082]
Since the coating composition of the present invention uses a non-alkylphenol-type nonionic surfactant as a surfactant, there is no risk of producing an endocrine disrupting substance even when drying or baking is performed at the time of coating. Is excellent in mechanical stability and storage stability.
The coating composition of the present invention is also composed of a fluoropolymer, and when the coating composition is a coating composition used for the above-described one coat, non-adhesiveness, lubricity, etc. In the case of the primer composition used in the above-described two-coat, it can improve the adhesion between the coating film obtained by painting and the above-mentioned top coating film.
The coating composition of the present invention is also composed of a heat-resistant resin, and since the heat-resistant resin has an adhesive property with the object to be coated as described above, the coating film obtained by coating the object to be coated is Excellent adhesion to
[0083]
Since the coating composition of the present invention has the above-described configuration, it can be suitably used as a coating composition for producing a coated article.
The production of the coated article comprises applying the coating composition of the present invention onto an object to be coated and, if necessary, drying to obtain a coated film.
[0084]
The object to be coated may have been previously subjected to a surface treatment such as a degreasing treatment or a roughening treatment according to the type thereof. The method of the surface roughening treatment is not particularly limited, and examples thereof include chemical etching with an acid or an alkali, anodic oxidation (alumite treatment), and sandblasting. The surface treatment is preferably performed from the viewpoint that the coating composition can be uniformly applied without repelling and that the adhesion between the object to be coated and the coating film is improved.
[0085]
The coating method is not particularly limited, and examples thereof include spray coating, roll coating, coating with a doctor blade, dip (dipping) coating, impregnation coating, spin flow coating, curtain flow coating, and the like.
The drying is not particularly limited. For example, a conventionally known method is used, and the drying is preferably performed at a temperature of 60 to 300 ° C. for 5 to 60 minutes.
[0086]
In the production of the coated article, in the case of the above-mentioned one coat in which an overcoat is not laminated on the coating, the coating is obtained by obtaining the coating and firing the coating. The calcination is not particularly limited, and for example, a conventionally known method is used. The calcination is usually performed at 260 to 410 ° C. for 10 to 30 minutes, depending on the type of the fluorinated polymer or the heat-resistant resin.
[0087]
In the case of the above-mentioned two-coating in which a top coat is laminated on the above-mentioned coat in the production of the above-mentioned coated article, after obtaining the above-mentioned coating film, a top-coat paint is applied on this coating film and dried if necessary. Then, by firing, a coating film composed of the coating composition and a top coating film composed of the top coating material are obtained.
[0088]
In the present specification, the above-mentioned "overcoat paint" is a paint to be applied on the above-mentioned coating film, and is made of a fluoropolymer for overcoat. The above fluorine-containing polymer for overcoating is a polymer having a fluorine atom directly bonded to a carbon atom constituting a main chain or a side chain. The above-mentioned fluoropolymer for overcoating is common to the above-mentioned fluoropolymer in that it is a polymer having a fluorine atom directly bonded to a carbon atom constituting a main chain or a side chain, but is blended into the above-mentioned topcoat paint. This is conceptually different from the above-mentioned fluoropolymer blended in the coating composition of the present invention. The above-mentioned fluoropolymer for overcoating, by being present in the overcoating film, can impart non-adhesiveness, lubricity, etc. to the object to be coated, and has an affinity with the above-mentioned fluoropolymer, so that Adhesion with a coating film can also be improved.
[0089]
The above-mentioned fluoropolymer for topcoat is not particularly limited, and includes, for example, PTFE, PFA, FEP, and the like. The same thing as the above-mentioned fluoropolymer in a composition, or the thing with similar properties, such as the presence or absence of melt processability, is preferable. Examples of the top coat include PTFE-based paints whose main component is PTFE, PFA-based paints whose main component is PFA, and FEP-based paints whose main component is FEP.
[0090]
The above-mentioned top coat paint is further blended with the above-mentioned fluoropolymer for top coat with the same additives as the various additives that can be used in the above-mentioned coating composition for the purpose of improving coatability, properties of the obtained coating film, and the like. It may be made by doing.
The top coating, for example, when the main component is PTFE, PFA or FEP, an aqueous dispersion-based coating, a liquid coating such as a solvent-based coating, and when the main component is PFA or FEP, the powder coating is No.
[0091]
When a liquid paint is used as the top coat, the coating film is not usually baked before applying the top coat, but may be baked as needed. It is preferable not to perform baking before applying the above-mentioned top coat, since simplification of the process and reduction of energy, labor, time and the like can be achieved.
When a powder coating is used as the top coating, the coating film is usually baked before applying the top coating.
[0092]
The method of applying the top coat is not particularly limited.For example, when the top coat is a liquid paint, the same method as the method of applying the coating composition of the present invention may be used. In the case of a powder coating, electrostatic spray coating, fluidized immersion coating, a lot lining method and the like can be mentioned.
Drying and baking after the application of the top coat can be performed under the same conditions as the drying and baking performed after the coating composition is applied, respectively.
[0093]
In the production of the coated article, in the case of the above-described two-coat, the above-mentioned top coat may be obtained by using a film instead of the above-mentioned top coat.
In the present specification, the film is mainly composed of the fluoropolymer for overcoating and is formed into a film. When the above film is used for forming the overcoat film, a conventionally known method such as placing the film on the coating film and bonding the coating film and the film by heating and pressing is used. Can be.
[0094]
The film thickness of the coating film after firing and the film thickness of the topcoat film are not particularly limited, and depending on the use of the coated article, the film thickness of the coating film is 1 to 100 μm, and the film of the topcoat film. The thickness is preferably from 10 to 200 μm.
[0095]
When the coating film is formed on the object to be coated by the one coat described above, the non-adhesiveness of the fluoropolymer, lubricity, and the like can be imparted to the object to be coated. When a top coat is laminated on the above-mentioned coat by the two-coating method, both the adhesion to the object to be coated and the adhesion to the top coat are excellent.
[0096]
The coated article comprises an object to be coated and the coating film, and the coating film is obtained by coating the object to be coated. The above-mentioned coated article may further have the above-mentioned overcoating film as long as it comprises at least the above-mentioned object to be coated and the above-mentioned coating film.
[0097]
The object to be coated is not particularly restricted but includes, for example, metals such as iron, aluminum, copper and the like, and metals such as alloys thereof; and non-metallic inorganic materials such as enamel, glass and ceramics. Examples of the alloys include stainless steel.
[0098]
The coated article can be used for applications utilizing the properties of the fluoropolymer used for the one-coat described above or the overcoat fluoropolymer used for the two-coat described above.
The coated article is not particularly limited. For example, when non-adhesiveness is used as the property, a frying pan, a grill pan, a pressure cooker, other various pots, a rice cooker, a rice cake sticker, an oven, a hot plate, and a baking mold Cooking utensils such as kitchen knives, gas tables, etc .; Food and beverage containers such as electric pots and ice trays; Parts for the food industry such as kneading rolls, rolling rolls, conveyor hoppers; Rolls for office automation equipment [OA], belts for OA, papermaking Industrial products such as rolls and calender rolls for film production; molds for styrofoam molding and the like, molds for mold release such as plywood and decorative board production; kitchenware such as range hoods; frozen foods such as conveyor belts A manufacturing apparatus.
[0099]
As the above-mentioned coated articles, when utilizing the slipperiness as the above-mentioned property, tools such as saws and files; household goods such as irons; metal foils; sliding bearings such as food processing machines, packaging machines, and spinning machines; -Sliding parts for watches; automotive parts and the like.
[0100]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Hereinafter, “%” and “parts” represent mass% and parts by mass, respectively.
Production Example 1 Preparation of aqueous dispersion of polyether sulfone resin
60 parts of a polyether sulfone resin [PES] having a number average molecular weight of about 24000 and 60 parts of deionized water were stirred for about 10 minutes in a ceramic ball mill until particles composed of PES were completely ground. Next, 180 parts of N-methyl-2-pyrrolidone [NMP] was added, and the mixture was further ground for 48 hours to obtain a dispersion. The obtained dispersion was further pulverized by a sand mill for 1 hour to obtain a PES aqueous dispersion having a PES concentration of about 20%. The particle size of the particles made of PES in the aqueous PES dispersion was 2-3 μm.
[0101]
Preparation Example 2 Preparation of Polyamideimide Aqueous Dispersion
A polyamideimide resin [PAI] varnish having a solid content of 29% (containing 71% NMP) was poured into water to precipitate PAI. This was ground in a ball mill for 48 hours to obtain an aqueous PAI dispersion. In the obtained PAI aqueous dispersion, the solid content was 20%, and the average particle size of the particles composed of PAI was 2 μm.
[0102]
Example 1
The PAI aqueous dispersion obtained in Production Example 2 was added to a polytetrafluoroethylene [PTFE] aqueous dispersion (average particle diameter: 0.28 μm, solid content: 60%, and a polyether nonionic surfactant (HLB value = 14) is contained in an amount of 6 parts based on 100 parts of the solid content of PTFE) so that PAI becomes 20% of the total solid content of PAI and PTFE, and methylcellulose is used as a thickening agent. 0.7% with respect to the solid weight of the PTFE, and 6 parts of polyoxyethylene tridecyl ether (HLB value = 10) as a dispersion stabilizer was added to 100 parts of the solid content of PTFE, and the solid content of PTFE was 34%. Was obtained.
About 100 ml of the obtained coating composition was stirred at 40 ° C. and 300 rpm for 6 hours, but no aggregate was generated and the mechanical stability was good.
[0103]
The following evaluation was performed about the obtained coating composition.
(Preparation of coated plate for evaluation)
After the surface of an aluminum plate (A-1050F) having a thickness of 2.0 mm is degreased with acetone, sand blasting is performed so that the surface roughness Ra value measured according to JIS B 1982 is 2.5 to 3.5 μm. And roughened. After removing dust on the surface by air blowing, the obtained coating composition was dried with a dry film thickness of 10 using a gravity type spray gun RG-2 (trade name, manufactured by Anest Iwata, nozzle diameter 1.0 mm). It was applied by spray coating at a spray pressure of 0.2 MPa so as to have a thickness of １５15 μm. The obtained coating film was dried at 80 to 100 ° C. for 15 minutes and cooled to room temperature. On the obtained coating film, a water-based coating material containing polytetrafluoroethylene (PTFE) EK-3700C-201 (trade name, manufactured by Daikin Industries, Ltd.) containing PTFE as a top coating material was applied by spray coating under the same conditions, and was applied at 80 to 100 ° C. Dry for 15 minutes. Thereafter, it was baked at 380 ° C. for 20 minutes to produce a top coat having a thickness of about 20 μm, thereby obtaining a coated plate for evaluation.
[0104]
(Paintability and appearance)
In the process of preparing the above-mentioned evaluation coated plate, the coatability when the top coating was applied and the appearance of the coated plate after applying the top coating, then drying and firing were visually observed and evaluated. .
[0105]
The coatability of the top coat was good, a uniform coating film could be formed, and the appearance of the coating film after firing was uniform and good.
[0106]
Example 2
The PES aqueous dispersion obtained in Production Example 1 and the PAI aqueous dispersion obtained in Production Example 2 were mixed so that PES was 85% of the total solid mass of PES and PAI. Contains 6 parts of a PTFE aqueous dispersion (average particle size 0.28 μm, solid content 60%, polyether nonionic surfactant (HLB value = 14) as a dispersant per 100 parts of PTFE solid content). ) Was added so that PES and PAI became 20% of the total solid content of PES, PAI and PTFE, and methylcellulose was added as a thickening agent at 0.7% to the solid content of PTFE, and the dispersion stability was improved. As an agent, 6 parts of polyoxyethylene tridecyl ether (HLB value = 10) was added to 100 parts of the solid content of PTFE to obtain a coating composition having a PTFE solid content of 34%.
About 100 ml of the obtained coating composition was stirred at 40 ° C. and 300 rpm for 6 hours, but no aggregate was generated and the mechanical stability was good.
Using the obtained coating composition, a coated plate for evaluation was prepared and evaluated in the same manner as in Example 1. The coatability of the top coat was good, a uniform coating film could be formed, and the appearance of the coating film after firing was uniform and good.
[0107]
Comparative example
A coating composition was obtained in the same manner as in Example 2, except that polyoxyethylene octylphenyl ether (HLB value = 13) was used instead of polyoxyethylene tridecyl ether.
About 100 ml of the obtained coating composition was stirred at 40 ° C. and 300 rpm, but the whole gelled in about 30 minutes.
Using the obtained coating composition, a coated plate for evaluation was prepared and evaluated in the same manner as in Example 1. The topcoat paint was repelled at the time of painting and was poor in paintability. The appearance of the coating film after firing was inferior, with spots observed at repelling spots generated during the application of the top coat.
[0108]
【The invention's effect】
Since the coating composition of the present invention has the above-mentioned constitution, there is no possibility of generating an endocrine disrupting substance, the mechanical stability and the storage stability are good, and the coating film having excellent adhesion to the object to be coated is provided. Can be obtained.

Claims (9)

Heat-resistant resin, a coating composition comprising an aqueous dispersion containing a fluoropolymer and a surfactant,
The surfactant is a non-alkylphenol-type nonionic surfactant,
The coating composition, wherein the amount of the non-alkylphenol-type nonionic surfactant is 0.1 to 20 parts by mass based on 100 parts by mass of the solid content of the fluoropolymer. The aqueous dispersion contains particles made of a fluoropolymer and particles made of a heat-resistant resin,
The aqueous dispersion is mainly composed of particles made of the fluoropolymer as a dispersoid, and an aqueous medium as a dispersion medium,
The coating composition according to claim 1, wherein the particles made of the heat-resistant resin are particles dispersed as particles in the aqueous medium and having an average particle size of 0.1 to 10 µm. The coating composition according to claim 1, wherein the heat-resistant resin is a polyamide-imide resin and / or a polyimide resin. The heat-resistant resin is a polyether sulfone resin, a polyamide imide resin and / or a polyimide resin,
3. The coating composition according to claim 1, wherein the polyethersulfone resin accounts for 65 to 85% by mass of the total mass of the polyethersulfone resin and the polyamideimide resin and / or the polyimide resin. 4. The fluorinated polymer is a polytetrafluoroethylene, a tetrafluoroethylene / hexafluoropropylene copolymer, and / or a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer. A coating composition according to any one of the preceding claims. The coating composition according to claim 1, 2, 3, 4, or 5, wherein the non-alkylphenol-type nonionic surfactant has an HLB value of less than 12. The non-alkylphenol type nonionic surfactant has the following general formula (I):
R-O-A-H
(Wherein, R represents a linear or branched, saturated or unsaturated, acyclic aliphatic hydrocarbon group having 8 to 19 carbon atoms, or a saturated cyclic aliphatic hydrocarbon having 8 to 19 carbon atoms) A represents a polyoxyalkylene chain having 3 to 25 oxyethylene units and 0 to 5 oxypropylene units.) A nonionic surfactant represented by the formula: 7. The coating composition according to 4, 5, or 6. The coating composition according to claim 1, 2, 3, 4, 5, 6, or 7, which is a primer composition. The coating composition according to claim 8, wherein the heat-resistant resin is 15 to 50% by mass of the total solid content of the heat-resistant resin and the fluoropolymer.