JP4872172B2 - Method for producing fluororesin coating and fluororesin coating - Google Patents

Description

【００３７】
［式中、Ｒはメチル基又はエチル基を表し、Ｘは単結合、−Ｃ_２Ｈ_４ＮＨ−、−ＣＯＮＨ−又はＣ_２Ｈ_４ＮＨ−Ｃ_２Ｈ_４ＮＨ−ＮＨ−を表し、ｙは２又は３である。］
で表されるアミノシラン化合物又はその部分若しくは完全加水分解物等が挙げられる。
【００３８】
（２）ポリオール系加硫剤
水酸基、特にフェノール性水酸基を分子内に少なくとも２個有する化合物及び高分子化合物であって、加硫性能を有するものが挙げられる。例えば、ビスフェノールＡ、ビスフェノールＡＦ、ヒドロキノン等のフェノール誘導体及びその塩；フェノール樹脂等エノール型水酸基を分子内に２個以上有するポリヒドロキシ化合物及びその塩；下記一般式
Ｒｆ′（ＣＨ_２ＯＨ）_２
〔ただし、Ｒｆ′は、パーフルオロアルキルポリエーテル基である。〕で表される化合物等が挙げられる。
【００３９】
（３）ポリチオール系加硫剤
トリアジンチオール、１，６−ヘキサンジチオール、４，４’−ジメチルメルカプトジフェニル、１，５−ナフタレンジチオール等が挙げられる。
【００４０】
上記加硫剤としては、上記以外にも、フッ素ゴム用加硫剤として市販されている加硫剤はいずれも使用することができ、１種又は２種以上を用いることができる。
上記加硫剤としては、後述する媒体が有機溶剤の場合にはその有機溶剤に可溶なものを用いることが好ましく、上記媒体が水の場合には水に可溶なものを用いることが好ましい。
【００４１】
上記加硫剤は、効率よく充分に上記加硫を行わせる点から、固形分基準で上記フッ素ゴム（ａ２）１００質量部に対し、０．１〜２０質量部であることが好ましく、０．５〜１５質量部であることがより好ましい。
【００４２】
上記フッ素ゴム（ａ２）には、上記加硫を促進させるために、加硫助剤を用いることもできる。上記加硫助剤としては特に限定されないが、例えば、トリフェニルホスフィンベンジルクロライド塩等の４級ホスフォニウム塩；トリメチルアミン、トリエチルアミン、トリｎ−プロピルアミン、トリｎ−ブチルアミン、トリイソブチルアミン、メチルジエチルアミン、ジメチルエチルアミン、ジメチルｎ−プロピルアミン、ジメチルｎ−ブチルアミン、ジメチルイソブチルアミン、ジメチルイソプロピルアミン、ジメチル−ｓｅｃ−ブチルアミン、ジメチル−ｔｅｒｔ−ブチルアミン、トリアリルアミン、ジアリルメチルアミン、アリルジメチルアミン、ベンジルジメチルアミン、ベンジルジエチルアミン、Ｎ−アリルピペリジン、Ｎ−エチルピペリジン、Ｎ−ブチルピペリジン、Ｎ−メチルピロリジン、Ｎ−シクロヘキシルピロリジン、Ｎ−ｎ−ブチルピロリジン、Ｎ−エチルピロリジン、Ｎ−ベンジルピロリジン、２，４，６−トリメチルピリジン等の３級アミン；第４級アンモニウム塩等の化合物が好ましい。
【００４３】
上記第４級アンモニウム塩としては、例えば、トリメチルベンジルアンモニウムクロライド、トリエチルベンジルアンモニウムクロライド、ジメチルデシルベンジルアンモニウムクロライド、トリエチルベンジルアンモニウムクロライド、ミリスチルベンジルジメチルアンモニウムクロライド、ドデシルトリメチルアンモニウムクロライド、ジメチルテトラデシルベンジルアンモニウムクロライド、トリメチルテトラデシルアンモニウムクロライド、ステアリルトリメチルアンモニウムクロライド、ジステアリルジメチルアンモニウムクロライド、テトラブチルアンモニウムハイドロオキサイド、１，４−フェニレンジメチレンビストリメチルアンモニウムジクロライド、１，４−フェニレンジメチレンビストリエチルアンモニウムジクロライド、エチレンビストリエチルアンモニウムジブロマイド等のアルキル及びアラルキル第４級アンモニウム塩；
【００４４】
８−メチル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムクロライド、８−メチル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムアイオダイド、８−メチル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムハイドロオキサイド、８−メチル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウム−メチルサルフェート、８−メチル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムブロマイド、８−プロピル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムブロマイド、８−ドデシル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムクロライド、８−ドデシル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムハイドロオキサイド、８−エイコシル−１，８−ジアザ−ビシクロ［５．４、０］−７−ウンデセニウムクロライド、８−テトラコシル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムクロライド、８−ベンジル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムクロライド、８−ベンジル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムハイドロオキサイド、８−フェネチル−１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウムクロライド、８−（３−フェニルプロピル）−１，８−ジアザ−ピシクロ［５．４．０］−７−ウンデセニウムクロライド等の第４級１，８−ジアザ−ビシクロ［５．４．０］−７−ウンデセニウム塩等が挙げられる。
【００４５】
上記加硫助剤としては、上記媒体が有機溶剤の場合にはその有機溶剤に可溶なものを用いることが好ましく、上記媒体が水の場合には水に可溶なものを用いることが好ましい。
【００４６】
上記加硫助剤は、効率よく充分に上記加硫を行わせる点から、固形分基準で上記フッ素ゴム（ａ２）１００質量部に対し、０〜１０質量部が好ましく、０．１〜８質量部がより好ましい。
【００４７】
上記塗料組成物（Ａ）は、上記溶融性フッ素樹脂（ａ１）及び上記フッ素ゴム（ａ２）に加え、一般的なフッ素ゴム組成物に通常添加される各種添加剤、例えば充填材、着色剤、受酸剤等を必要に応じて配合したものであってよい。
【００４８】
上記充填材としては特に限定されず、例えば、カーボンブラック、ホワイトカーボン、炭酸カルシウム、硫酸バリウム、タルク、珪酸カルシウム等が挙げられる。
上記着色剤としては特に限定されず、例えば、無機顔料、複合酸化物顔料等が挙げられる。
上記受酸剤としては特に限定されず、例えば、酸化マグネシウム、酸化鉛、酸化亜鉛、炭酸鉛、炭酸亜鉛、ハイドロタルサイト等の複塩が挙げられる。上記受酸剤は、通常、その活性度に応じ、固形分基準で上記フッ素ゴム（ａ２）１００質量部に対し、１〜４０質量部を配合することができる。
【００４９】
上記塗料組成物（Ａ）は、更に、媒体を含有するものであってよい。本明細書において、上記媒体とは、塗料組成物の成分を溶解又は分散させる物質である。
上記塗料組成物（Ａ）に用いられる媒体としては特に限定されず、有機溶剤又は水の何れを用いてもよい。
【００５０】
上記有機溶剤としては、例えばメチルエチルケトン、メチルイソブチルケトン等のケトン類；酢酸ブチル、酢酸イソペンチル等のエステル類；ジエチレングリコールジメチルエーテル等のエーテル類；トルエン、キシレン等の炭化水素類；Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチル−２−ピロリドン等のアミド類等が挙げられる。上記有機溶剤は、上記塗料組成物（Ａ）全体の質量を基準にして４０〜９０質量％用いることが好ましい。
【００５１】
上記媒体として水を用いる場合には、上記フッ素ゴム（ａ２）及び上記溶融性フッ素樹脂（ａ１）を上記媒体中に分散させるため、分散剤を用いることが好ましい。
上記分散剤としては、ラウリル硫酸塩、パーフルオロアルキルカルボン酸塩、ω−ハイドロパーフルオロアルキルカルボン酸塩等のアニオン系界面活性剤；ポリエチレングリコール誘導体、ポリエチレングリコール／ポリプロピレングリコール誘導体等の非イオン性界面活性剤；アルキルポリエチレングリコールエーテル、アルキルフェニルポリエチレングリコールエーテル、アルキルポリエチレングリコールエステル、エチレングリコール／プロピレングリコール共重合体、ポリエチレングリコールアルキルエステル、ポリカルボン酸塩等の樹脂系分散剤等が挙げられる。上記分散剤は、上記塗料組成物（Ａ）全体の質量を基準にして０．１〜１０質量％用いることが好ましい。
【００５２】
上記媒体として水を用いる場合、乾燥遅延剤を用いてもよい。上記乾燥遅延剤としては特に限定されず、例えば、水溶性かつ高沸点の有機溶剤等が挙げられ、例えば、エチレングリコール、トリエチレングリコール、ジエタノールアミン、トリエタノールアミン、ブチルカルビトール、セロソルブ、酢酸セロソルブ等が挙げられる。乾燥遅延剤を加えることが好ましい。
【００５３】
上記媒体としての水は、上記塗料組成物（Ａ）全体の質量を基準にして３０〜９０質量％用いることが好ましい。
上記媒体としては、得られる塗膜の表面平滑化、環境保護等の点から、水を用いることが好ましく、上記水は上記媒体中７０〜１００質量％であることがより好ましい。
【００５４】
上記塗料組成物（Ａ）としては、保存安定性の向上を目的として、安定剤を添加したものであってよい。上記安定剤としては特に限定されず、例えば、炭素数１〜１２の有機酸等が挙げられ、炭素数１〜９の有機酸が好ましい。炭素数が９を越える有機酸は、塗膜中に残存しやすい。より好ましくは、炭素数１〜４の有機酸である。上記安定剤として更に好ましい有機酸としては、蟻酸、酢酸、プロピオン酸等のモノカルボン酸；シュウ酸、マロン酸、コハク酸等のジカルボン酸等が挙げられる。
【００５５】
上記塗料組成物（Ａ）は、更に、接着性付与剤を添加したものであってもよい。
上記塗料組成物（Ａ）は、上記接着性付与剤を添加することにより、被塗装物との親和性や接着性を高めることができ、上記被塗装物が後述のプライマーを塗布したものである場合、プライマーとの親和性を付与することもできる。
【００５６】
上記接着性付与剤としては特に限定されず、例えば、上記被塗装物が金属又はガラスである場合、シランカップリング剤、チタンカップリング剤、アルミニウムカップリング剤等のカップリング剤等が挙げられる。上記接着性付与剤としては、また、上記加硫剤の中で接着性を有するものを用いることができ、例えば、アミノシラン化合物、ポリアミドアミン、フェノール樹脂等の添加量に応じて接着性付与剤として機能し得るもの等が挙げられる。
【００５７】
上記塗料組成物（Ａ）は、上述のフッ素ゴム（ａ２）、溶融性フッ素樹脂（ａ１）、加硫剤及び所望により用いるその他の成分を、例えばオープンロール又はニーダー等を用いて混練することにより、容易に調製することができる。上記塗料組成物（Ａ）の調製方法としては、例えば、上述のフッ素ゴム（ａ２）、加硫剤及び必要に応じ加硫助剤等のその他の成分を配合してフッ素ゴム組成物を調製し、別途調製した上記溶融性フッ素樹脂（ａ１）を更に加える方法等を用いることができる。
【００５８】
上記フッ素ゴム組成物の調製方法としては特に限定されず、例えば、次のいずれかの方法で行うことができる。
（１）上記媒体が有機溶剤の場合
乳化重合で得られた上記フッ素ゴム（ａ２）のベースポリマーを凝析・乾燥させることによりフッ素生ゴムが得られる。これに、任意成分である上述の充填材、受酸剤及び着色剤をオープンロール又はニーダーで混練し、コンパウンドとする。このコンパウンドを上記有機溶剤に溶解又は分散し、必要に応じて上記安定剤を加えてＰ液とする。一方、上述の加硫剤並びに任意成分である加硫助剤及び接着性付与剤を有機溶剤に溶解してＱ液とする。１液型の場合には、はじめからＰ液とＱ液を混合して、調製する。
【００５９】
（２）上記媒体が水の場合
上記分散剤の存在下で水に分散させたフッ素ゴム（ａ２）の濃縮液を調製する。フッ素ゴム（ａ２）のラテックスをそのまま使用してもよい。任意成分である上述の充填材、受酸剤、着色剤も分散剤を用いて予めミル分散させる。これらの液を混合し、必要ならば上記安定剤を加え、更に水で適当な濃度及び粘度に調製してＲ液とする。一方、上述の加硫剤及び加硫助剤を別途用い、これらが水溶性の場合、これらの水溶液を調製し、これらが非水溶性の場合、分散剤を用いたこれらの水系分散液を調製し、得られる調製液に必要に応じて上記接着性付与剤を加え、Ｓ液とする。１液型の場合には、はじめからＲ液とＳ液を混合して、調製する。
【００６０】
上記フッ素ゴム（ａ２）と上記溶融性フッ素樹脂（ａ１）とを配合する方法としては特に限定されず、例えば、以下の方法を用いることができる。
（１）上記溶融性フッ素樹脂（ａ１）を固体のまま配合する場合
上記溶融性フッ素樹脂（ａ１）を微粉末状に粉砕し、上述のフッ素ゴム（ａ２）のコンパウンドに混練する。
【００６１】
（２）上記媒体が有機溶剤の場合
上記溶融性フッ素樹脂（ａ１）の微粉末を有機溶剤に分散させるか、または、上記溶融性フッ素樹脂（ａ１）のディスパージョンを有機溶剤に転相してオルガノゾルを作成し、これを有機溶剤媒体である上記塗料組成物（Ａ）の他の成分と混合する。
【００６２】
（３）上記媒体が水の場合
上記溶融性フッ素樹脂（ａ１）の微紛末を上述の分散剤を用いて分散させる。または、上記溶融性フッ素樹脂（ａ１）のディスパージョンをそのまま分散させるか若しくは分散剤を用いて分散させる。これらの分散系を水媒体である上記塗料組成物（Ａ）の他の成分と混合する。
【００６３】
上記フッ素ゴム（ａ２）と上記溶融性フッ素樹脂（ａ１）との配合比は、固形分基準の質量比として上記フッ素ゴム（ａ２）：上記溶融性フッ素樹脂（ａ１）が３０：７０〜７０：３０であることが好ましい。上記フッ素ゴム（ａ２）が３０：７０未満であると、フッ素ゴム本来の弾性が失われたり、得られる塗膜にひび割れ等の欠陥が生じたり、上記フッ素ゴム（ａ２）と被塗装物との接着性に劣ったりすることがある。上記フッ素ゴム（ａ２）が７０：３０を越えると、得られる上記溶融性フッ素樹脂（Ａ）層は上記溶融性フッ素樹脂（Ｂ）層との融着が悪くなり、層間剥離を起こすことがある。より好ましくは、４０：６０〜６０：４０である。
【００６４】
上記塗料組成物（Ｂ）は、溶融性フッ素樹脂（ｂ）を含有するものである。
上記溶融性フッ素樹脂（ｂ）は、上記溶融性フッ素樹脂として上述した特徴を有するものである。
【００６５】
上記溶融性フッ素樹脂（ｂ）は、更に、造膜性及び得られる塗膜の表面平滑性の点から、上記溶融性フッ素樹脂（ｂ）を構成する粒子の平均粒子径が０．２μｍ以上であるものが好ましい。０．２μｍ未満であると、塗膜表面の平滑性が不充分となるほか、造膜性が低下して塗膜にクラックを生じる場合がある。
【００６６】
上記溶融性フッ素樹脂（ｂ）は、後述の水性媒体を用いる場合、上記平均粒子径が０．２〜１μｍであるものが好ましい。１μｍを超えると、かえって塗膜表面の平滑性が悪化し、後述する表面粗さ〔Ｒｚ〕が２μｍを超える場合がある。より好ましくは、０．２〜０．４μｍである。
本明細書において、上記平均粒子径は、電子顕微鏡、遠心沈降分離法又は光散乱法を用いて測定した個々の粒子の粒子径の平均値である。
上記平均粒子径は、通常、適宜粒度分布を用い、目的とする対象粒径に適した測定法により測定した値の平均値として求められる。上記対象粒径に適した測定法としては、通常、平均粒子径１μｍを超える場合、光散乱（レーザー）法、平均粒子径０．２〜１μｍの場合、遠心分離沈降法又は光散乱法、及び、平均粒子径０．２μｍ未満の場合、電子顕微鏡又は光散乱法がそれぞれ用いられる。
【００６７】
上記塗料組成物（Ｂ）は、上記溶融性フッ素樹脂（ｂ）に加え、一般的なフッ素樹脂組成物に通常添加される各種添加剤、例えば乾燥遅延剤、充填材、着色剤、安定剤、接着性付与剤等を必要に応じて配合したものであってよい。上記各種添加剤としては、上記塗料組成物（Ａ）について上述したものと同様のものを用いることができる。
【００６８】
上記塗料組成物（Ｂ）は、上記媒体を用いることなく粉体塗料としてもよいが、得られる塗膜表面の平滑化の点から、上記媒体を用いることが好ましい。上記媒体としては特に限定されず、有機溶剤又は水の何れを用いてもよい。
【００６９】
上記有機溶剤としては、上記塗料組成物（Ａ）の媒体として上述した有機溶剤と同様のものが挙げられる。この場合、上記塗料組成物（Ｂ）は、例えば、乳化重合により得られた上記溶融性フッ素樹脂（ｂ）のディスパージョンを上記有機溶剤に転相してオルガノゾルとし、塗装することができる。
【００７０】
上記塗料組成物（Ｂ）は、造膜性、塗膜表面の平滑化及び環境保護の点から、上記媒体として水を含有する水性媒体を用いることがより好ましい。
上記水性媒体としては上記媒体に水を用いるものであれば特に限定されず、例えば、上記有機溶剤を含有するものであってもよいが、環境保護の点から、水は上記媒体中７０〜１００質量％であることが好ましく、１００質量％であることがより好ましい。
【００７１】
上記媒体として上記水性媒体を用いる場合、上記溶融性フッ素樹脂（ｂ）の分散性と造膜性を向上させるため、分散剤を用いることが好ましい。上記分散剤としては、例えば、上記塗料組成物（Ａ）について上述した分散剤と同様のものを用いてもよいが、本発明においては、得られる塗膜表面の平滑性を高めるため、非イオン性界面活性剤が好ましい。
【００７２】
上記非イオン性界面活性剤としては、造膜性及び分解性が良好である点から、親水親油バランス〔ＨＬＢ〕が１５以上であることが好ましい。１５未満であると、造膜性が不充分となって塗膜にクラックを生じたり、後述の焼成時に充分に分解せず、塗膜に残存して塗膜物性を劣化させる場合がある。より好ましくは、１５〜２０であり、更に好ましくは、１５〜１８である。
本明細書において、ＨＬＢとは、下記式により求められる値をいう。
ＨＬＢ＝親水性基の重量％／５
【００７３】
このような非イオン性界面活性剤としてはＨＬＢが１５以上であれば特に限定されないが、例えば、ポリエチレングリコール、ポリエチレングリコールアルキルエーテル、ポリエチレングリコールアルキルフェニルエーテル、ポリエチレングリコールアルキルエステル、ポリエチレングリコールポリプロピレングリコールポリエチレングリコールブロックコポリマー、ポリオキシエチレンソルビタンモノアルキレート等であって、ＨＬＢが１５以上のものであればよく、これらは１種又は２種以上を用いることができる。
【００７４】
上記非イオン性界面活性剤は、固形分基準で上記溶融性フッ素樹脂（ｂ）１００質量部に対し８〜２０質量部であることが好ましい。８質量部未満であると、造膜性が不充分となる傾向にあり、２０質量部を超えると、塗膜における残存量が多くなり、塗膜物性の低下を招きかねない。より好ましくは、１２〜１８質量部である。
【００７５】
上記塗料組成物（Ｂ）としては、上記溶融性フッ素樹脂（ｂ）の水性分散液であることが好ましい。上記溶融性フッ素樹脂（ｂ）の水性分散液とは、上記媒体として上記水性媒体を用いてこれを分散媒とし、上記溶融性フッ素樹脂（ｂ）を分散質とする分散系である。
【００７６】
上記溶融性フッ素樹脂（ｂ）の水性分散液は、好ましくは上記分散剤を含有し、より好ましくは上記非イオン性界面活性剤を含有するものである。上記溶融性フッ素樹脂（ｂ）の水性分散液は、また、乾燥遅延剤を用いることが好ましい。上記乾燥遅延剤としては、例えば、上記塗料組成物（Ａ）について上述したものと同様のものを用いることができる。
【００７７】
上記溶融性フッ素樹脂（ｂ）の水性分散液は、例えば、乳化重合により得られた上記溶融性フッ素樹脂（ｂ）のディスパージョンを上記水性媒体及び好適には上記分散剤及び上記乾燥遅延剤を用いて、水性塗料とし、塗装することができる。
【００７８】
上記塗料組成物（Ｂ）は、上記溶融性フッ素樹脂（ｂ）並びに所望により上記媒体及び／又は上記各種添加剤を用い、例えば従来公知の方法等により容易に調製することができる。上記塗料組成物（Ｂ）の調製方法としては、例えば、上述のフッ素ゴム（ａ２）、加硫剤、加硫助剤及び受酸剤は加えないものの、既に述べた上記溶融性フッ素樹脂（ａ１）を上記フッ素ゴム（ａ２）と配合する方法に準じて調製することができる。
【００７９】
本発明のフッ素樹脂被覆物製造方法は、上記塗料組成物（Ａ）を被塗装物に塗布し、乾燥した後、上記塗料組成物（Ｂ）を塗布し、焼成することよりなるフッ素樹脂被覆物を製造する方法であって、上記塗料組成物（Ｂ）は、上記フッ素ゴム（ａ２）を加硫させる前に塗布するものである。
【００８０】
上記被塗装物としては上記焼成を行う温度を超える耐熱温度を有するものであれば特に限定されず、用途に応じて選択することができ、例えば、鉄、ステンレス鋼、銅、アルミニウム、真鍮等の金属類；ガラス板、ガラス繊維の織布及び不織布等のガラス製品；ポリプロピレン、ポリオキシメチレン、ポリイミド、ポリアミドイミド、ポリスルホン、ポリエーテルサルホン、ポリエーテルエーテルケトン等の汎用樹脂及び耐熱性樹脂の成形品及び被覆物；ＳＢＲ、ブチルゴム、ＮＢＲ、ＥＰＤＭ等の汎用ゴムの成形品及び被覆物；シリコーンゴム、フッ素ゴム等の耐熱性ゴムの成形品及び被覆物；天然繊維及び合成繊維の織布及び不織布等が挙げられ、これらを１種又は２種以上用いたものであってもよい。
【００８１】
上記被塗装物としては、なかでも、後述する用途に好適である場合が多く、多用されている点から、金属類及び／又は弾性体を含有するものが好ましい。上記弾性体とは、上述の汎用ゴム、耐熱性ゴム等の弾性を有する材料を含有するものである。上記弾性体としては、後述の焼成による劣化を防止するため、上記耐熱性ゴムを用いたものが好ましく、シリコーンゴムを用いたものがより好ましい。
【００８２】
上記被塗装物は、用途によるが、例えばＯＡ機器用ロール、ＯＡ機器用ベルト等の他材と接触する用途に用いられる基板である場合、他材との接触面積を確保するため、弾性を有することが好ましい。弾性を有する上記被塗装物としては、上記弾性体が好ましく、金属類等の非弾性体を含有するものである場合、弾性を得るため、上記非弾性体の上に上記弾性体を積層させたものが好ましい。
【００８３】
上記被塗装物は、その材質によるが、表面の脱脂及び／又は洗浄を施したものであってもよい。上記被塗装物は、特に金属類である場合、表面の脱脂及び洗浄を行うことが好ましく、この場合、例えば、表面の脱脂及び洗浄を行った後にシリコーンゴムからなる層を形成させることができる。
【００８４】
上記被塗装物は、その材質によるが、上記脱脂及び／若しくは洗浄を施した後又は上記脱脂及び／若しくは洗浄を施すことなく、下塗り塗料としてプライマーを塗布したものであってもよい。上記被塗装物は、上記プライマーが塗布されたものであることにより、上述の塗料組成物（Ａ）層との密着性を向上させることができる。
【００８５】
上記プライマーとしては特に限定されず、上記被塗装物の材質に応じて選択することができ、例えば、市販のフッ素ゴム用下塗り塗料を用いることができる。上記プライマーとしては、例えば、シランカップリング剤等のシラン系プライマー；シリコーン樹脂等のシリコーン系プライマー；チタンカップリング剤、アルミニウムカップリング剤等のその他のカップリング剤；エポキシ樹脂、フェノール樹脂、エポキシ／フェノール樹脂、アクリル樹脂等のその他の樹脂系プライマー等が挙げられる。
【００８６】
上記被塗装物は、シリコーンゴムを表面に有するものである場合、更にその上に上記プライマーを塗布したものであることが好ましい。
【００８７】
上記塗料組成物（Ａ）は、塗装作業性の向上、得られる塗膜物性の向上等のため、塗布するに際し、上述の媒体を更に添加する等の従来公知の方法等により、必要に応じて希釈してもよい。なお、上記塗料組成物（Ｂ）についても同様に希釈してよい。
【００８８】
上記被塗装物に上記塗料組成物（Ａ）を塗布する方法としては特に限定されず、例えば、ハケ塗り、スプレーコーティング、浸漬塗布、フローコーティング、ディスペンサーコーティング、スクリーンコーティング等の従来公知の方法を用いることができる。
【００８９】
上記塗料組成物（Ａ）を塗布した後、上述の媒体として用いた有機溶剤又は水を蒸発させるため、通常、乾燥する。上記乾燥は、例えば室温〜１００℃で１０〜１２０分間行う。
【００９０】
このようにして得られた上記塗料組成物（Ａ）層の上に、上記塗料組成物（Ｂ）を塗布する。上記塗料組成物（Ｂ）を塗布する段階では、上記塗料組成物（Ａ）層において、上記フッ素ゴム（ａ２）は実質的に加硫されておらず、上記溶融性フッ素樹脂（ａ１）は溶融していない。
【００９１】
上記塗料組成物（Ｂ）の塗布の後、必要に応じて乾燥し、次いで焼成する。上記塗布及び乾燥の方法としては、上記塗料組成物（Ａ）と同様の方法を用いることができる。
上記焼成は、上記被塗装物、上記溶融性フッ素樹脂等の劣化を防止しつつ、得られる塗膜表面を平滑化する点から、特定の範囲内の焼成温度で行う。
【００９２】
上記特定の範囲内の焼成温度の下限は、上記溶融性フッ素樹脂（ａ１）の融点及び上記溶融性フッ素樹脂（ｂ）の融点のうち高い方の温度よりも１０℃高い温度である。上記下限未満であると、上記溶融性フッ素樹脂（ａ１）及び上記溶融性フッ素樹脂（ｂ）が溶融しないか、または、溶融しても溶融粘度が不充分であり、造膜性に劣ったり、充分に平滑な表面を有する塗膜が得られない。
【００９３】
上記特定の範囲内の焼成温度の上限は、上記溶融性フッ素樹脂（ａ１）の分解温度、上記溶融性フッ素樹脂（ｂ）の分解温度及び上記被塗装物の耐熱温度のうち最も低い温度未満の温度である。上記上限を超えると、上記溶融性フッ素樹脂が分解して非粘着性等のフッ素樹脂本来の優れた特性が充分に得られないか、または、上記被塗装物が熱劣化して目的とする品質が得られない。
【００９４】
上記焼成温度の上限としては、上記被塗装物がシリコーンゴムを含有するものであって、上記プライマーが塗布されたものである場合、上記シリコーンゴムの耐熱温度及び上記プライマーの耐熱温度のうち低い方の温度未満の温度にすることが好ましい。上記上限を超えると、上記シリコーンゴムが熱劣化して充分な弾性が得られない場合や、上記プライマーが分解して上記被塗装物と上記塗料組成物（Ａ）層との間の接着性が不充分となり、層間剥離等を起す場合がある。なお、通常、上記プライマーの耐熱温度の方が上記シリコーンゴムの耐熱温度よりも低いので、上記焼成温度の上限は上記プライマーの耐熱温度に支配されることが多い。
【００９５】
上記焼成温度としては、例えば、上記被塗装物がシリコーンゴムを含有し、上記プライマーが塗布されたものである場合において、用いるシリコーンゴムの耐熱温度と用いるプライマーの耐熱温度によるが、上記溶融性フッ素樹脂としてＰＦＡを用いるとき、３２０〜３３０℃が好ましく、上記溶融性フッ素樹脂としてＦＥＰを用いるとき、２５０〜３１０℃が好ましい。
【００９６】
上記焼成は、焼成温度によるが、通常、０．２５〜８時間行うことが好ましい。
上記焼成を行うことにより、上記塗料組成物（Ａ）中の溶融性フッ素樹脂（ａ１）が上記塗料組成物（Ａ）層の表面にブリードアップし、上記溶融性フッ素樹脂（ｂ）と融着するとともに、上記フッ素ゴム（ａ２）の加硫が起こり、この加硫の進行につれて上記フッ素ゴム（ａ２）と上記溶融性フッ素樹脂（ａ１）との結合が進むものと考えられる。
【００９７】
上記塗料組成物（Ｂ）から形成される塗膜の膜厚は、用いる上記溶融性フッ素樹脂（ｂ）の平均粒子径、用途等によるが、上記焼成の後において１〜２０μｍであることが好ましい。１μｍ未満であると、上記溶融性フッ素樹脂からなる層の使用耐久性が不充分となる場合があり、また、上記溶融性フッ素樹脂からなる層の厚膜化が特に要求されない場合には、通常、本発明のフッ素樹脂被覆物製造方法を用いる必要は特にない。２０μｍを超えると、上述の範囲内の平均粒子径を有する上記溶融性フッ素樹脂（ｂ）を用いることによっては得ることが容易でない。より好ましくは、１〜１５μｍであり、更に好ましくは、２〜１０μｍである。
【００９８】
本発明のフッ素樹脂被覆物は、上記フッ素樹脂被覆物製造方法により製造されたものであることを特徴とするものである。本明細書において、上記フッ素樹脂被覆物とは、上記被塗装物の上に形成された塗膜を有するものを意味する。従って、上記フッ素樹脂被覆物は、上記被塗装物の上に形成された塗膜のみであってもよいし、上記被塗装物及びこの被塗装物の上に形成された塗膜であってもよく、これらの表面及び／又は裏面に必要に応じてコーティング等のその他の層の形成、洗浄、裏面の研磨等の表面処理を施したものであってもよい。
【００９９】
上記フッ素樹脂被覆物は、表面が平滑性を有するものである。
上記フッ素樹脂被覆物は、表面粗さ〔Ｒｚ〕が２μｍ以下である。２μｍを超えると、表面の平滑性が不充分となり、紙片やトナー等の汚染物質が付着しやすく長期間の使用耐久性に劣るほか、例えばＯＡ機器用ロールやＯＡ機器用ベルト等に用いられる場合、記録媒体への定着画像の乱れ、紙皺等を招きやすい等の問題を生じる。好ましくは、１．６μｍ以下であり、通常、０．８μｍ以上である。
【０１００】
上記表面粗さ〔Ｒｚ〕は、ＪＩＳ−Ｂ０６０１に規定される十点平均粗さである。本明細書において、上記Ｒｚは、測定長を４ｍｍとして、表面粗さ計（商品名：サーフコム４７０Ａ、東京精機社製）を用いて測定した値である。
【０１０１】
上記フッ素樹脂被覆物は、表面の水との接触角が１０２〜１３０°であることが好ましい。１０２°未満であると、離型性に劣る場合や、表面の平滑性に劣って汚染物質の付着等の上記問題を生じる場合があり、１３０°を超えると、別途表面平滑化処理等が必要となる場合があり、工程の簡略化、エネルギー等の低減といった本発明の目的を逸脱する場合がある。より好ましくは、１０２〜１１０°である。本明細書において、上記接触角は、接触角計としてゴニオメーター（協和界面科学社製）を用いて測定した値である。
【０１０２】
上記フッ素樹脂被覆物は、表面の光沢（６０°−６０°）が５０％以上であることが好ましい。５０％未満であると、表面の平滑性に劣る場合や、用途により商品価値が低下する場合がある。より好ましくは、５０〜９５％である。本明細書において、上記光沢（６０°−６０°）は、デジタル変角光沢計（スガ試験機社製）を用いて測定した値である。
【０１０３】
本発明のフッ素樹脂被覆物製造方法は、上記溶融性フッ素樹脂（ａ１）及び上記溶融性フッ素樹脂（ｂ）を用い、上記塗料組成物（Ｂ）を塗布する前に上記フッ素ゴム（ａ２）の加硫を行わず、上記特定範囲内の温度で焼成することから、得られるフッ素樹脂被覆物の塗膜表面の良好な平滑性を達成することができる。本発明のフッ素樹脂被覆物製造方法がこのような有利な効果を奏する機構は明確ではないが、次のように考えられる。
【０１０４】
即ち、従来のようにフッ素ゴムを加硫させた上にフッ素樹脂組成物を塗布し焼成することにより得られる塗膜表面の平滑性が損なわれていたことと異なり、本発明において上記特定範囲内の温度で焼成する時に上記フッ素ゴム（ａ２）、上記溶融性フッ素樹脂（ａ１）及び上記溶融性フッ素樹脂（ｂ）が同時期又はほぼ同時期に軟化又は溶融することとなり、更に、上記溶融性フッ素樹脂は溶融粘度が比較的低く溶融時の流動性に優れている結果、得られる塗膜表面は、凹凸がならされて平均化し、平滑になるものと考えられる。
【０１０５】
本発明のフッ素樹脂被覆物製造方法は、また、上記フッ素ゴム（ａ２）の加硫を単独の工程として行う必要がなく、塗膜形成後等に表面平滑化処理を別途行う必要もないことから、工程を簡略化し、エネルギー、時間、労力等を低減することができるので、工業的に有利な製造方法である。
【０１０６】
本発明のフッ素樹脂被覆物製造方法によれば、更に、表面の上記溶融性フッ素樹脂からなる層を比較的厚くすること、及び、造膜性に優れ、クラックや層間剥離のない塗膜を得ることを両立することができ、非粘着性等のフッ素樹脂本来の特性を長期間損なうことなく使用耐久性に優れた塗膜を有するフッ素樹脂被覆物を製造することができる。
【０１０７】
上記フッ素樹脂被覆物は、表面に上記溶融性フッ素樹脂からなる層を有している点から、耐熱性、耐溶剤性、潤滑性、非粘着性等のフッ素樹脂の特性が要求される分野で好適に使用することができ、例えば、複写機、プリンター、ファクシミリ等のＯＡ機器に用いられる定着ロール、圧着ロール等のＯＡ機器用ロール；上記ＯＡ機器用の搬送ベルト；シート及びベルト；Ｏ−リング、ダイヤフラム、耐薬品性チューブ、燃料ホース、バルブシール、化学プラント用ガスケット、エンジンガスケット等のその他の工業製品等が挙げられる。
【０１０８】
上記フッ素樹脂被覆物は、非粘着性等の上記フッ素樹脂本来の特性を発揮することができるとともに、平滑性が良好である表面を有する点から、ＯＡ機器用ロール又はＯＡ機器用ベルトに好適に用いられ、ＯＡ機器用ロール又はＯＡ機器用ベルトであることが好ましい。
【０１０９】
【実施例】
以下に実施例を挙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。
調製例１ 「フッ素ゴムディスパージョンＡ」の調製
乳化重合によりＶｄＦとＴＦＥとＨＦＰの共重合体を製造し、得られた重合混合溶液を、非イオン性界面活性剤としてＨＳ−２０８（ＨＬＢ＝１２．６、日本油脂社製）の２０重量％水溶液及びＨＳ−２１５（ＨＬＢ＝１５．０、日本油脂社製）の２０重量％水溶液との混合物を用いて濃縮し、固形分濃度を６０重量％とした。これを「フッ素ゴムディスパージョンＡ」とする。
【０１１０】
調製例２ 「Ｐｉｇペースト」の調製
充填剤（タロックスＲ−５１６Ｌ、チタン工業社製）３重量部及び受酸剤（ＤＨＴ−４Ａ、協和化学工業社製）５重量部を、界面活性剤として上記ＨＳ−２０８の２０重量％水溶液２重量部とともに純水４６重量部に分散させてペーストを調製した。これを「Ｐｉｇペースト」とする。
【０１１１】
調製例３ 「フッ素ゴム塗料主剤」の調製
「フッ素ゴムディスパージョンＡ」７０重量部、「Ｐｉｇペースト」２３．５重量部、増粘剤ＡとしてＤＳ−６０ＨＮ（日本油脂社製）の５重量％水溶液６重量部、増粘剤ＢとしてＵＨ−１４０Ｓ（旭電化工業社製）の５０重量％水溶液０．５重量部を混合して充分に分散させた。
【０１１２】
調製例４ 「ＦＥＰディスパージョン」の調製
乳化重合によりＴＦＥ／ＨＦＰ共重合体〔ＦＥＰ〕を製造し、得られた重合混合溶液を、界面活性剤として上記ＨＳ−２０８及び上記ＨＳ−２１５の各２０重量％水溶液を用いて濃縮し、固形分濃度を６０重量％とし、固形分基準でＦＥＰ１００重量部に対し上記ＨＳ−２０８及び上記ＨＳ−２１５はそれぞれ４重量部とした。融点は２４０℃、ＭＦＲは１ｇ／１０分、平均粒子径は０．１８μｍであった。これを「ＦＥＰディスパージョン」とする。
【０１１３】
調製例５ 「ＰＦＡディスパージョン」の調製
乳化重合によりＴＦＥ／ＰＦＶＥ共重合体〔ＰＦＡ〕を製造し、得られた重合混合溶液を、界面活性剤として上記ＨＳ−２０８及び上記ＨＳ−２１５の各２０重量％水溶液を用いて濃縮し、固形分濃度を６０重量％とし、固形分基準でＰＦＡ１００重量部に対し上記ＨＳ−２０８及び上記ＨＳ−２１５はそれぞれ４重量部とした。融点は３１０℃、ＭＦＲは５５ｇ／１０分、平均粒子径は０．１９μｍであった。これを「ＰＦＡディスパージョン」とする。
【０１１４】
調製例６ 「ＥＰＡディスパージョン」の調製
乳化重合によりＴＦＥ／ＨＦＰ／ＰＦＶＥ共重合体〔ＥＰＡ〕を製造し、得られた重合混合溶液を、界面活性剤として上記ＨＳ−２０８及び上記ＨＳ−２１５の各２０重量％水溶液を用いて濃縮し、固形分濃度を６０重量％とし、固形分基準でＥＰＡ１００重量部に対し上記ＨＳ−２０８及び上記ＨＳ−２１５はそれぞれ４重量部とした。融点は２７５℃、ＭＦＲは２０ｇ／１０分、平均粒子径は０．１８μｍであった。これを「ＥＰＡディスパージョン」とする。
【０１１５】
調製例７ 「加硫剤溶液Ａ」の調製
３，９−ビス（３−アミノプロピル）−２，４，８，１０−テトラオキサ−２−スピロ［５，５］−ウンデカン（エポメートＦ−１００、油化シェル社製）５０％水溶液に、γ−アミノプロピルトリエトキシシラン（Ａ−１１００、日本ユニカー社製）６０％水溶液を重量比４／６の比率で混合し調製した。これを「加硫剤溶液Ａ」とする。
【０１１６】
調製例８ 「加硫剤溶液Ｂ」の調製
γ−アミノプロピルトリエトキシシラン（Ａ−１１００、日本ユニカー社製）６０％水溶液を調製した。これを「加硫剤溶液Ｂ」とする。
【０１１７】
調製例９ 「塗料Ａ１」の調製
「フッ素ゴム塗料主剤」１００重量部、「ＦＥＰディスパージョン」７０重量部を混合して（固形分基準でフッ素ゴム：ＦＥＰ＝５０：５０重量比）充分に分散させた。この水性分散液１００重量部に「加硫剤溶液Ａ」５重量部を混合し、塗料を調製した。これを「塗料Ａ１」とする。
【０１１８】
調製例１０ 「塗料Ａ２」の調製
「フッ素ゴム塗料主剤」１００重量部、「ＦＥＰディスパージョン」７０重量部を混合して（固形分基準でフッ素ゴム：ＦＥＰ＝５０：５０重量比）充分に分散させた。この水性分散液１００重量部に「加硫剤溶液Ｂ」５重量部を混合し、塗料を調製した。これを「塗料Ａ２」とする。
【０１１９】
調製例１１ 「塗料Ａ３」の調製
「フッ素ゴム塗料主剤」１００重量部、「ＦＥＰディスパージョン」４７重量部を混合して（固形分基準でフッ素ゴム：ＦＥＰ＝６０：４０重量比）充分に分散させた。この水性分散液１００重量部に「加硫剤溶液Ａ」５重量部を混合し、塗料を調製した。これを「塗料Ａ３」とする。
【０１２０】
調製例１２ 「塗料Ａ４」の調製
「フッ素ゴム塗料主剤」９５重量部、「ＦＥＰディスパージョン」１００重量部を混合して（固形分基準でフッ素ゴム：ＦＥＰ＝４０：６０重量比）充分に分散させた。この水性分散液１００重量部に「加硫剤溶液Ａ」５重量部を混合し、塗料を調製した。これを「塗料Ａ４」とする。
【０１２１】
調製例１３ 「塗料Ｂ」の調製
「フッ素ゴム塗料主剤」１００重量部、「ＰＦＡディスパージョン」７０重量部を混合して（固形分基準でフッ素ゴム：ＰＦＡ＝５０：５０重量比）充分に分散させた。この水性分散液１００重量部に「加硫剤溶液Ａ」５重量部を混合し、塗料を調製した。これを「塗料Ｂ」とする。
【０１２２】
調製例１４ 「塗料Ｃ」の調製
「フッ素ゴム塗料主剤」１００重量部、「ＥＰＡディスパージョン」７０重量部を混合して（固形分基準でフッ素ゴム：ＥＰＡ＝５０：５０重量比）充分に分散させた。この水性分散液１００重量部に「加硫剤溶液Ａ」５重量部を混合し、塗料を調製した。これを「塗料Ｃ」とする。
【０１２３】
調製例１５ 「ＰＦＡ塗料」の調製
乳化重合によりＴＦＥ／ＰＦＶＥ共重合体〔ＰＦＡ〕を製造し、得られた重合混合溶液を、界面活性剤として上記ＨＳ−２０８及び上記ＨＳ−２１５の各２０重量％水溶液を用いて濃縮し、固形分濃度を６０重量％とした。融点は３１０℃、ＭＦＲは２５ｇ／１０分、平均粒子径は０．２４μｍであった。このディスパージョン１００重量部に、非イオン系界面活性剤としてエマルゲン１２０（ＨＬＢ＝１５．３、花王社製）の３０％水溶液を２０重量部、エチレングリコールを１０重量部を混合分散し、塗料を調製した。これを「ＰＦＡ塗料」とする。
【０１２４】
実施例１
（塗装板の作成）
予めアセトンで洗浄したアルミニウム板の表面上半面に、「塗料Ａ１」をスプレー塗装し、８０〜１００℃で１５分間乾燥した後、室温まで空冷し、約３０μｍの膜厚を有する下層塗膜を作成した。そして、その上から塗板全面に「ＰＦＡ塗料」をスプレー塗装し、室温で約１時間及び８０〜１００℃で１５分間乾燥した後、３２５℃で３０分間焼成して、総膜厚約４０μｍの塗装板を作成した。
【０１２５】
（塗膜特性の評価）
得られた塗装板の塗膜表面の特性を以下のように評価した。結果を表１に示す。
１．塗膜外観
塗膜表面上のクラック、発泡、ブツ、フクレ等の有無を目視で観察し、評価した。
２．対水接触角
塗膜表面に純水を一滴滴下してゴニオメーター（協和界面科学社製）を用いて接触角を測定した。
【０１２６】
３．表面粗さ
塗膜表面の十点平均表面粗さ〔Ｒｚ〕を表面粗さ計（サーフコム４７０Ａ、東京精機社製）を用い、測定長を４ｍｍとして測定した。
４．光沢
塗膜表面の光沢（６０°−６０°）を、デジタル変角光沢計（スガ試験機社製）を用いて測定した。
【０１２７】
実施例２
「塗料Ａ１」に代わり「塗料Ａ２」を用いたこと以外は、実施例１と同様にして塗装板を作成し、評価した。
実施例３
「塗料Ａ１」に代わり「塗料Ａ３」を用いたこと以外は、実施例１と同様にして塗装板を作成し、評価した。
【０１２８】
実施例４
「塗料Ａ１」に代わり「塗料Ａ４」を用いたこと以外は、実施例１と同様にして塗装板を作成し、評価した。
実施例５
「塗料Ａ１」に代わり「塗料Ｂ」を用いたこと以外は、実施例１と同様にして塗装板を作成し、評価した。
【０１２９】
実施例６
「塗料Ａ１」に代わり「塗料Ｃ」を用いたこと以外は、実施例１と同様にして塗装板を作成し、評価した。
比較例１
「ＰＦＡ塗料」に代わり「ＰＦＡディスパージョン」を用いたこと以外は、実施例１と同様にして塗装板を作成し、評価した。
【０１３０】
比較例２
「ＰＦＡ塗料」に代わりＰＦＡ水性塗料（ＡＷ−５０００、ダイキン工業社製、融点は３００℃、ＭＦＲは２０ｇ／１０分、平均粒子径は２５μｍであった。）を用いたこと以外は、実施例１と同様にして塗装板を作成し、評価した。
比較例３
塗装板の作成において、「塗料Ａ１」を塗装し、８０〜１００℃で１５分間乾燥した後空冷前に、２００℃で２時間焼成する工程を追加したこと以外は、実施例１と同様にして塗装板を作成し、評価した。
【０１３１】
【表１】

【０１３２】
表１から、各実施例は、表面粗さ〔Ｒｚ〕が２μｍ以下であり、光沢及び水接触角が比較的大きい値であるので、表面平滑性が良好であり、また、塗膜外観にも優れるのに対し、各比較例は、Ｒｚが２μｍを超え、塗膜外観に劣っており、上述の塗料組成物（Ｂ）の塗布前に加硫した比較例３、並びに、上記塗料組成物（Ｂ）が非イオン性界面活性剤を含有しなかったり上記溶融性フッ素樹脂（ｂ）の平均粒子径が０．２〜１μｍの範囲内にない比較例２及び比較例３では、表面平滑性や塗膜外観に劣ることがわかった。
【０１３３】
【発明の効果】
本発明のフッ素樹脂被覆物製造方法は、上述の構成よりなるので、フッ素ゴムを加硫するための単独の工程、及び、別途行う表面平滑化処理工程を経る必要なくして、表面平滑性を有する塗膜を得ることができ、工程簡略化や、エネルギー、時間、労力等の削減が可能となり、しかも、フッ素樹脂からなる層を厚くしてその特性の発揮を長期間持続させることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a fluororesin coating obtained by coating with fluororesin and fluororubber, and more specifically, has a surface smoothness without separately performing a surface smoothing treatment, and vulcanizes fluororubber. The present invention relates to a method for producing a fluororesin coating that does not need to be performed as a single step.
[0002]
[Prior art]
Fluorocarbon resin has excellent properties such as heat resistance, weather resistance, oil resistance, solvent resistance, chemical resistance, non-adhesiveness, and contamination resistance. It is used as a coating material.
[0003]
As the coating material, for example, a coating film formed by coating a coating composition containing a fluororesin on a substrate as an object to be coated can be used. Coating using a fluororesin depends on the type of fluororesin and the like, but is usually carried out by applying it to an object to be coated, drying it as necessary, and firing it.
[0004]
When a flexible substrate such as rubber is used as the object to be coated, or when flexibility is required for the resulting coating film, if fluorine resin is blended with the fluororesin and painted, Since the surface of the coating film can be bleed-up, a flexible coating film having the characteristics of a fluororesin can be obtained on the surface.
[0005]
However, since the fluororesin layer on the surface of the coating film thus obtained is usually relatively thin, in particular, contact and friction with other materials such as rolls for office automation [OA] equipment and belts for OA equipment are essential. When used in various applications, there is a problem that the durability becomes insufficient due to wear of the coating surface.
[0006]
For the purpose of improving the durability of the fluororesin layer on the surface of the paint film, a coating composition containing a fluororesin is applied on the fluororesin layer that has been bleed-up by applying a blend of fluororesin and fluororubber. Further, a fluororesin layer is formed to increase the thickness of the fluororesin layer.
[0007]
As a method for overcoating a coating composition containing a fluororesin, Japanese Patent Application Laid-Open No. 2000-263715 discloses that a compound of an applied fluororesin and fluororubber is vulcanized until a specific degree of vulcanization is reached. A method of applying a coating composition containing a fluororesin is disclosed.
[0008]
In order to improve the durability of the fluororesin layer, it is effective to form a fluororesin layer having a certain thickness and to prevent the adhesion of contaminants to the coating film surface. Examples of the contaminant include paper powder and toner. When the contaminant enters the concave portion on the surface of the coating film, it becomes easier to adhere and adhere with the core as a core.
[0009]
Therefore, in order to prevent the adhesion of contaminants, it is desirable that the coating surface be smooth. When the surface of the coating film is smoothed, for example, when used as a roll for OA equipment, the fixing property of the toner to the recording medium can be improved, and the stain resistance is improved, so that the image is stained and jammed. Such problems can also be prevented.
[0010]
As a method for smoothing the surface of the coating film, Japanese Patent Application Laid-Open No. 2000-305396 discloses a coating obtained by coating a mixture of fluororesin and fluororubber and then coating a dispersion containing fluororesin. Has been disclosed in which a surface smoothing treatment is carried out by placing in a smooth tube and heating to press the surface layer of the coating against the inner wall of the tube.
[0011]
However, in this method, not only a surface smoothing treatment is separately required, but also a mixture containing a fluororesin and a fluororubber is applied and dried, followed by a rubber curing step by heating, and then a dispersion containing the fluororesin Since it is applied, dried and baked, there is a problem that it is necessary to cure the rubber as a single step, and the number of heating steps increases, resulting in an increase in cost, labor, energy and the like.
[0012]
[Problems to be solved by the invention]
In view of the above, an object of the present invention is to produce a fluororesin-coated material having a coating film with good surface smoothness without having to go through a step of vulcanizing fluororubber and a surface smoothing treatment step separately. It is to provide a method.
[0013]
[Means for Solving the Problems]
The present invention is a coating composition containing a meltable fluororesin (b) after applying a coating composition (A) containing a meltable fluororesin (a1) and a fluororubber (a2) to an object to be coated and drying it. A fluororesin coating production method for producing a fluororesin coating comprising applying and firing a product (B), wherein the coating composition (B) vulcanizes the fluororubber (a2) The lower limit of the firing is 10 ° C. higher than the higher of the melting point of the meltable fluororesin (a1) and the melting point of the meltable fluororesin (b). The upper limit is a temperature range in which the decomposition temperature of the meltable fluororesin (a1), the decomposition temperature of the meltable fluororesin (b) and the heat resistance temperature of the object to be coated are lower than the lowest temperature. Yes, the above fluororesin coating , A fluorine resin coating manufacturing method, wherein the surface roughness [Rz] is 2μm or less.
[0014]
The coating composition (B) is preferably an aqueous dispersion of a meltable fluororesin (b).
The meltable fluororesin (b) preferably has an average particle size of 0.2 to 1 μm.
The coating composition (B) further contains a nonionic surfactant, and the nonionic surfactant has a hydrophilic / lipophilic balance [HLB] of 15 or more, and the nonionic surfactant. The surfactant is preferably 8 to 20 parts by mass with respect to 100 parts by mass of the meltable fluororesin (b) based on the solid content.
[0015]
The fluororesin coating preferably has a surface gloss (60 ° -60 °) of 50% or more.
The film thickness of the coating film formed from the coating composition (B) is preferably 1 to 20 μm.
[0016]
The blending ratio of the fluororubber (a2) to the meltable fluororesin (a1) is 30:70 to 70:70 in terms of mass ratio based on solid content of the fluororubber (a2): the meltable fluororesin (a1). 30 is preferable.
It is preferable that melting | fusing point of the said meltable fluororesin (a1) and the said meltable fluororesin (b) is 320 degrees C or less.
The meltable fluororesin (b) is a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer, a tetrafluoroethylene / hexafluoropropylene copolymer or a tetrafluoroethylene / hexafluoropropylene / perfluoro (alkyl vinyl ether) copolymer. A polymer is preferred.
The meltable fluororesin (b) is more preferably a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer.
[0017]
The object to be coated contains a silicone rubber and is coated with a primer, and the upper limit of the temperature range for performing the baking is lower among the heat resistant temperature of the silicone rubber and the heat resistant temperature of the primer. It is preferable that the temperature is lower than this temperature.
Hereinafter, the present invention will be described in detail.
[0018]
In the method for producing a fluororesin coating according to the present invention, a coating composition (A) containing a meltable fluororesin (a1) and a fluororubber (a2) is applied to an object to be coated, dried, and then melted fluororesin ( a coating composition (B) containing b), and a method for manufacturing a fluororesin coating for manufacturing a fluororesin coating comprising baking the coating composition (B), The rubber (a2) is applied before vulcanization.
[0019]
In this specification, the coating film formed from the said coating composition (A) may be called a coating composition (A) layer. The coating composition (A) layer is a coating film after the coating composition (A) is applied and dried, and before the coating composition (B) is applied, or the fluororesin Of the coating film formed on the object to be coated after the step of baking the coating composition (B) in the coating production method, the part derived from the coating composition (A) is included.
[0020]
In this specification, the coating film formed from the said coating composition (B) may be called a coating composition (B) layer. The coating composition (B) layer is the coating composition of the coating film formed on the object to be coated after the step of firing the coating composition (B) in the fluororesin coating manufacturing method. It is a part derived from a thing (B).
[0021]
The coating composition (A) contains a meltable fluororesin (a1) and a fluororubber (a2).
The substance belonging to the meltable fluororesin (a1) may be the same as or different from the substance belonging to the meltable fluororesin (b), but the coating composition (A) From the viewpoint of improving the adhesion and fusing properties between the layer and the coating composition (B) layer, the same is preferable. In this specification, when it describes about the matter common to the said meltable fluororesin (a1) and the said meltable fluororesin (b), it may be called the said meltable fluororesin, without distinguishing both.
[0022]
The meltable fluororesin is preferably a melt processable fluororesin because it can be melted by heating in the fluororesin coating production method of the present invention to form a coating film, and has a melting point of 320 ° C. or lower. More preferred is a fluororesin. When the melting point exceeds 320 ° C., the adhesiveness between the coating composition (A) layer and the coating composition (B) layer tends to decrease, and the smoothness of the resulting coating film surface becomes insufficient. There is. The melting point is more preferably 200 to 320 ° C, still more preferably 230 to 320 ° C.
[0023]
The meltable fluororesin preferably has a melt viscosity that can be melted during firing described below to obtain sufficient film-forming properties and smoothness of the coating surface. For example, in the case of PFA described later, ASTM D3307 The melt flow rate [MFR] measured by the method is more preferably 1 to 80 g / 10 min. When it exceeds 80 g / 10 minutes, the fluidity at the time of firing becomes too high, and it may be difficult to obtain a uniform film thickness depending on the shape of an object to be coated such as a curved surface. If it is less than 1 g / 10 minutes, the fluidity at the time of firing becomes too low, causing cracks and the like. More preferably, it is 10-40 g / 10min.
[0024]
The meltable fluororesin is not particularly limited. For example, tetrafluoroethylene [TFE] / hexafluoropropylene [HFP] copolymer [FEP], TFE / perfluoro (alkyl vinyl ether) [PFVE] copolymer [PFA ], TFE / HFP / PFVE copolymers [EPA], TFE / chlorotrifluoroethylene [CTFE] copolymers, TFE fluorine-containing copolymers such as TFE / ethylene copolymer [ETFE]; And fluorine-containing homopolymers such as polytetrafluoroethylene [LMW-PTFE].
[0025]
In the present specification, the fluorine-containing copolymer and the fluorine-containing homopolymer are a copolymer or a homopolymer having a fluorine atom directly bonded to a carbon atom constituting the main chain. The TFE-based fluorine-containing copolymer is a fluorine-containing copolymer containing TFE as a monomer component.
[0026]
The PFVE is not particularly limited and includes, for example, compounds represented by the following formulas (1) to (5). In the following formula, n, m, and k are all integers.
Formula (1) CF₂= CFO (CF₂) N-CF₃[N = 1-9] Formula (2) CF₂= CFO (CF₂CF₂CF₂O)_m-CF₂CF₂CF₃[1 ≦ m ≦ 5]
Formula (3) CF₂= CFO [CF₂CF (CF₃]]_m-CF₂CF₂CF₃[1 ≦ m ≦ 5]
Formula (4) CF₂= CFO [CF₂CF (CF₃]]_m-CF₂CF₂CH₂I [1 ≦ m ≦ 5]
Formula (5) CF₂= CFOCFOCH₂(CF₂)_kX [k = 1 to 12, X = H, F or Cl]
[0027]
As said meltable fluororesin, FEP, PFA, and EPA are preferable from the point of non-adhesiveness and surface smoothness, FEP and PFA are more preferable, PFA is still more preferable. As said meltable fluororesin, 1 type (s) or 2 or more types can be used.
[0028]
It does not specifically limit as a preparation method of the said meltable fluororesin, For example, conventionally well-known methods, such as emulsion polymerization and suspension polymerization, etc. can be used.
[0029]
The coating composition (A) contains fluororubber (a2) together with the meltable fluororesin (a1).
The fluororubber (a2) is not particularly limited, but the main chain is —CH₂A fluorine-containing copolymer having a repeating unit represented by-is preferred.
[0030]
Examples of such fluororubber (a2) include a copolymer having a molecular structure in which the main chain includes the following repeating units.
-CF₂-CH₂-, -CH₂-CH₂-And CH₂-CH (CH₃)-At least one repeating unit selected from-
-CF₂-CF (CF₃)-, -CF₂-CF₂-, -CF₂-CFCl-, -CF₂-CF (CF₂H)-and CF₂-CF (ORf)-
[Wherein Rf is a fluoroalkyl group having 1 to 9 carbon atoms. ] At least 1 type of repeating unit selected from these.
[0031]
Examples of the fluororubber (a2) include vinylidene difluoride [VdF] and HFP copolymers, VdF fluorine-containing copolymers such as VdF, TFE and HFP copolymers; TFE and propylene copolymer And a copolymer of PFVE and alkene such as a copolymer and a copolymer of ethylene and HFP. Of these, a VdF-based fluorine-containing copolymer is preferable from the viewpoint of crosslinkability. Here, the VdF fluorine-containing copolymer is a fluorine-containing copolymer containing VdF as a monomer component.
[0032]
The molecular weight of the fluororubber (a2) is preferably 5000 to 200000. If it is less than 5,000, the degree of vulcanization may be inferior, and if it exceeds 200,000, the fluidity of the coating composition (A) may be deteriorated and the coating workability may be inferior.
[0033]
The fluororubber (a2) is preferably a fluorine-containing copolymer capable of exhibiting elasticity, and for example, a commercially available product can be used. For example, “DAIEL” (registered trademark, manufactured by Daikin Industries, Ltd.) , “Viton Frome” (registered trademark, manufactured by EI DuPont), “Afras” (registered trademark, manufactured by Asahi Glass), and the like. The fluororubber (a2) may also be synthesized by a conventionally known method such as emulsion polymerization.
As said fluororubber (a2), 1 type (s) or 2 or more types can be used.
[0034]
The fluororubber (a2) is vulcanized and cured by firing, which will be described later, in the fluororesin coating production method of the present invention. The vulcanizing agent used for the vulcanization is not particularly limited, and for example, a commonly used fluororubber vulcanizing agent can be used. As the vulcanizing agent, the following are preferably used.
[0035]
(1) Polyamine vulcanizing agent
Triethylenetetramine, tetraethylenepentamine, ethylenediamine, triethylenediamine, ethanolamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxa-2-spiro [5.5] -undecane, etc. Aliphatic polyamines and salts thereof; aromatic amines and salts thereof such as diaminodiphenylmethane, xylylenediamine, phenylenediamine, diaminodiphenylsulfone, diaminodiphenyl ether; modified polyamines; polyamidoamines;
[0036]
[Chemical 1]

[0037]
[Wherein, R represents a methyl group or an ethyl group, X represents a single bond, —C₂H₄NH-, -CONH- or C₂H₄NH-C₂H₄NH—NH— is represented, and y is 2 or 3. ]
Or a partial hydrolyzate thereof or the like.
[0038]
(2) Polyol vulcanizing agent
Examples thereof include compounds having at least two hydroxyl groups, particularly phenolic hydroxyl groups in the molecule, and polymer compounds having vulcanization performance. For example, phenol derivatives such as bisphenol A, bisphenol AF, and hydroquinone, and salts thereof; polyhydroxy compounds such as phenol resin, having two or more enol-type hydroxyl groups in the molecule; and salts thereof;
Rf ′ (CH₂OH)₂
[Wherein Rf ′ is a perfluoroalkyl polyether group. And the like.
[0039]
(3) Polythiol vulcanizing agent
Examples include triazine thiol, 1,6-hexanedithiol, 4,4'-dimethylmercaptodiphenyl, 1,5-naphthalenedithiol, and the like.
[0040]
As the vulcanizing agent, in addition to the above, any vulcanizing agent marketed as a vulcanizing agent for fluororubber can be used, and one or more can be used.
As the vulcanizing agent, when the medium described later is an organic solvent, it is preferable to use a material soluble in the organic solvent, and when the medium is water, it is preferable to use a material soluble in water. .
[0041]
The vulcanizing agent is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the fluororubber (a2) on the basis of solid content from the viewpoint of efficiently and sufficiently performing the vulcanization. More preferably, it is 5-15 mass parts.
[0042]
In the fluororubber (a2), a vulcanization aid can be used to promote the vulcanization. Although it does not specifically limit as said vulcanization | cure adjuvant, For example, quaternary phosphonium salts, such as a triphenylphosphine benzyl chloride salt; Trimethylamine, triethylamine, tri n-propylamine, tri n-butylamine, triisobutylamine, methyldiethylamine, dimethyl Ethylamine, dimethyl n-propylamine, dimethyl n-butylamine, dimethylisobutylamine, dimethylisopropylamine, dimethyl-sec-butylamine, dimethyl-tert-butylamine, triallylamine, diallylmethylamine, allyldimethylamine, benzyldimethylamine, benzyldiethylamine N-allylpiperidine, N-ethylpiperidine, N-butylpiperidine, N-methylpyrrolidine, N-cyclohexylpyrrolidine, -n- butyl pyrrolidine, N- ethylpyrrolidine, N- benzyl pyrrolidine, tertiary amines such as 2,4,6-trimethylpyridine; compounds such as quaternary ammonium salts are preferred.
[0043]
Examples of the quaternary ammonium salt include trimethylbenzylammonium chloride, triethylbenzylammonium chloride, dimethyldecylbenzylammonium chloride, triethylbenzylammonium chloride, myristylbenzyldimethylammonium chloride, dodecyltrimethylammonium chloride, dimethyltetradecylbenzylammonium chloride, Trimethyltetradecylammonium chloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, tetrabutylammonium hydroxide, 1,4-phenylenedimethylenebistrimethylammonium dichloride, 1,4-phenylenedimethylenebistriethylammonium dichlora De, alkyl and aralkyl quaternary ammonium salts such as ethylene bis-triethylammonium dibromide;
[0044]
8-methyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium chloride, 8-methyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium Iodide, 8-methyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium hydroxide, 8-methyl-1,8-diaza-bicyclo [5.4.0] -7 Undecenium-methyl sulfate, 8-methyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium bromide, 8-propyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium bromide, 8-dodecyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium chloride, 8-dodecyl-1,8-diaza-bicyclo [5.4. 0] -7-Undeceni Muhydrooxide, 8-eicosyl-1,8-diaza-bicyclo [5.4,0] -7-undecenium chloride, 8-tetracosyl-1,8-diaza-bicyclo [5.4.0] -7 -Undecenium chloride, 8-benzyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium chloride, 8-benzyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium hydroxide, 8-phenethyl-1,8-diaza-bicyclo [5.4.0] -7-undecenium chloride, 8- (3-phenylpropyl) -1,8-diaza- And quaternary 1,8-diaza-bicyclo [5.4.0] -7-undecenium salts such as picyclo [5.4.0] -7-undecenium chloride.
[0045]
As the vulcanization aid, when the medium is an organic solvent, a solvent soluble in the organic solvent is preferably used. When the medium is water, a solvent soluble in water is preferably used. .
[0046]
The vulcanization aid is preferably 0 to 10 parts by mass, preferably 0.1 to 8 parts by mass with respect to 100 parts by mass of the fluororubber (a2) based on the solid content, from the viewpoint of efficiently and sufficiently performing the vulcanization. Part is more preferred.
[0047]
The coating composition (A) includes various additives usually added to a general fluororubber composition, for example, a filler, a colorant, in addition to the meltable fluororesin (a1) and the fluororubber (a2). An acid acceptor or the like may be blended as necessary.
[0048]
The filler is not particularly limited, and examples thereof include carbon black, white carbon, calcium carbonate, barium sulfate, talc, and calcium silicate.
The colorant is not particularly limited, and examples thereof include inorganic pigments and composite oxide pigments.
The acid acceptor is not particularly limited, and examples thereof include double salts such as magnesium oxide, lead oxide, zinc oxide, lead carbonate, zinc carbonate, and hydrotalcite. The acid acceptor can usually be blended in an amount of 1 to 40 parts by mass with respect to 100 parts by mass of the fluororubber (a2) based on the solid content.
[0049]
The coating composition (A) may further contain a medium. In the present specification, the medium is a substance that dissolves or disperses the components of the coating composition.
It does not specifically limit as a medium used for the said coating composition (A), You may use any of an organic solvent or water.
[0050]
Examples of the organic solvent include ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as butyl acetate and isopentyl acetate; ethers such as diethylene glycol dimethyl ether; hydrocarbons such as toluene and xylene; N, N-dimethylacetamide; Examples include amides such as N-methyl-2-pyrrolidone. The organic solvent is preferably used in an amount of 40 to 90% by mass based on the mass of the entire coating composition (A).
[0051]
When water is used as the medium, a dispersant is preferably used in order to disperse the fluororubber (a2) and the meltable fluororesin (a1) in the medium.
Examples of the dispersant include anionic surfactants such as lauryl sulfate, perfluoroalkylcarboxylate, and ω-hydroperfluoroalkylcarboxylate; nonionic interfaces such as polyethylene glycol derivatives and polyethylene glycol / polypropylene glycol derivatives Activating agents; Alkyl polyethylene glycol ethers, alkyl phenyl polyethylene glycol ethers, alkyl polyethylene glycol esters, ethylene glycol / propylene glycol copolymers, polyethylene glycol alkyl esters, polycarboxylates and other resin dispersants. The dispersant is preferably used in an amount of 0.1 to 10% by mass based on the total mass of the coating composition (A).
[0052]
When water is used as the medium, a drying retarder may be used. The drying retardant is not particularly limited, and examples thereof include water-soluble and high-boiling organic solvents, such as ethylene glycol, triethylene glycol, diethanolamine, triethanolamine, butyl carbitol, cellosolve, cellosolve acetate, and the like. Is mentioned. It is preferred to add a drying retardant.
[0053]
Water as the medium is preferably used in an amount of 30 to 90% by mass based on the mass of the entire coating composition (A).
As said medium, it is preferable to use water from points, such as surface smoothing of the coating film obtained and environmental protection, and it is more preferable that the said water is 70-100 mass% in the said medium.
[0054]
The coating composition (A) may be added with a stabilizer for the purpose of improving storage stability. It does not specifically limit as said stabilizer, For example, a C1-C12 organic acid etc. are mentioned, A C1-C9 organic acid is preferable. Organic acids having 9 or more carbon atoms tend to remain in the coating film. More preferably, it is a C1-C4 organic acid. More preferable organic acids as the stabilizer include monocarboxylic acids such as formic acid, acetic acid and propionic acid; dicarboxylic acids such as oxalic acid, malonic acid and succinic acid.
[0055]
The coating composition (A) may further contain an adhesion promoter.
The coating composition (A) can enhance the affinity and adhesiveness with the object to be coated by adding the adhesiveness-imparting agent, and the object to be coated is coated with a primer described later. In some cases, affinity with a primer can also be imparted.
[0056]
It does not specifically limit as said adhesive imparting agent, For example, when the said to-be-coated article is a metal or glass, coupling agents, such as a silane coupling agent, a titanium coupling agent, and an aluminum coupling agent, etc. are mentioned. As the above-mentioned adhesion imparting agent, those having adhesiveness among the above vulcanizing agents can be used. For example, depending on the addition amount of aminosilane compound, polyamidoamine, phenol resin, etc. The thing etc. which can function are mentioned.
[0057]
The coating composition (A) is prepared by kneading the above-described fluororubber (a2), meltable fluororesin (a1), vulcanizing agent, and other components as required using, for example, an open roll or a kneader. Can be easily prepared. As a method for preparing the coating composition (A), for example, a fluororubber composition is prepared by blending the above-described fluororubber (a2), a vulcanizing agent, and other components such as a vulcanizing aid as required. Alternatively, a method of further adding the meltable fluororesin (a1) prepared separately can be used.
[0058]
It does not specifically limit as a preparation method of the said fluororubber composition, For example, it can carry out by one of the following methods.
(1) When the medium is an organic solvent
A raw fluororubber is obtained by coagulating and drying the base polymer of the fluororubber (a2) obtained by emulsion polymerization. The above-mentioned filler, acid acceptor and colorant, which are optional components, are kneaded with an open roll or kneader to obtain a compound. This compound is dissolved or dispersed in the organic solvent, and the stabilizer is added as necessary to obtain a liquid P. On the other hand, the above-described vulcanizing agent, optional vulcanization aid and adhesiveness-imparting agent are dissolved in an organic solvent to form Q solution. In the case of the 1-component type, the P solution and the Q solution are mixed from the beginning.
[0059]
(2) When the medium is water
A concentrated solution of fluororubber (a2) dispersed in water in the presence of the dispersant is prepared. You may use the latex of fluororubber (a2) as it is. The filler, acid acceptor, and colorant, which are optional components, are also mill-dispersed in advance using a dispersant. These liquids are mixed, if necessary, the above-mentioned stabilizer is added, and further adjusted to an appropriate concentration and viscosity with water to obtain R liquid. On the other hand, if the above-mentioned vulcanizing agent and vulcanization aid are separately used and these are water-soluble, these aqueous solutions are prepared, and if these are water-insoluble, these aqueous dispersions using a dispersant are prepared. Then, if necessary, the above-mentioned adhesion-imparting agent is added to the resulting preparation liquid to make S liquid. In the case of the one-component type, the R solution and the S solution are mixed from the beginning to prepare.
[0060]
The method of blending the fluororubber (a2) and the meltable fluororesin (a1) is not particularly limited, and for example, the following method can be used.
(1) When blending the meltable fluororesin (a1) as a solid
The meltable fluororesin (a1) is pulverized into a fine powder and kneaded into the compound of the fluororubber (a2).
[0061]
(2) When the medium is an organic solvent
The fine powder of the meltable fluororesin (a1) is dispersed in an organic solvent, or the dispersion of the meltable fluororesin (a1) is phase-shifted into an organic solvent to prepare an organosol, which is used as an organic solvent medium And the other components of the coating composition (A).
[0062]
(3) When the medium is water
The fine powder of the meltable fluororesin (a1) is dispersed using the dispersant described above. Alternatively, the dispersion of the meltable fluororesin (a1) is dispersed as it is or dispersed using a dispersant. These dispersions are mixed with the other components of the coating composition (A) as an aqueous medium.
[0063]
The blending ratio of the fluororubber (a2) to the meltable fluororesin (a1) is 30:70 to 70:70 in terms of mass ratio based on solid content of the fluororubber (a2): the meltable fluororesin (a1). 30 is preferable. When the fluororubber (a2) is less than 30:70, the original elasticity of the fluororubber is lost, or a defect such as cracking occurs in the obtained coating film, or the fluororubber (a2) and the object to be coated Adhesiveness may be inferior. When the fluororubber (a2) exceeds 70:30, the meltable fluororesin (A) layer obtained is poorly fused with the meltable fluororesin (B) layer and may cause delamination. . More preferably, it is 40: 60-60: 40.
[0064]
The coating composition (B) contains a meltable fluororesin (b).
The meltable fluororesin (b) has the characteristics described above as the meltable fluororesin.
[0065]
In the meltable fluororesin (b), the average particle size of the particles constituting the meltable fluororesin (b) is 0.2 μm or more from the viewpoint of film forming property and surface smoothness of the resulting coating film. Some are preferred. If it is less than 0.2 μm, the smoothness of the coating film surface becomes insufficient, and the film-forming property may be lowered to cause cracks in the coating film.
[0066]
The meltable fluororesin (b) preferably has an average particle diameter of 0.2 to 1 μm when an aqueous medium described later is used. If it exceeds 1 μm, the smoothness of the coating film surface is rather deteriorated, and the surface roughness [Rz] described later may exceed 2 μm. More preferably, it is 0.2 to 0.4 μm.
In the present specification, the average particle diameter is an average value of particle diameters of individual particles measured using an electron microscope, a centrifugal sedimentation method, or a light scattering method.
The average particle diameter is usually obtained as an average value of values measured by a measurement method suitable for the target particle diameter, using a particle size distribution as appropriate. As a measurement method suitable for the target particle size, usually, when the average particle size exceeds 1 μm, the light scattering (laser) method, when the average particle size is 0.2 to 1 μm, centrifugal sedimentation method or light scattering method, and When the average particle diameter is less than 0.2 μm, an electron microscope or a light scattering method is used.
[0067]
In addition to the meltable fluororesin (b), the coating composition (B) includes various additives that are usually added to general fluororesin compositions, such as drying retarders, fillers, colorants, stabilizers, An adhesiveness imparting agent or the like may be blended as necessary. As said various additives, the thing similar to what was mentioned above about the said coating composition (A) can be used.
[0068]
Although the said coating composition (B) is good also as a powder coating without using the said medium, it is preferable to use the said medium from the point of smoothing of the coating-film surface obtained. The medium is not particularly limited, and either an organic solvent or water may be used.
[0069]
As said organic solvent, the thing similar to the organic solvent mentioned above as a medium of the said coating composition (A) is mentioned. In this case, the coating composition (B) can be coated by, for example, phase-dispersing the dispersion of the meltable fluororesin (b) obtained by emulsion polymerization into the organic solvent to form an organosol.
[0070]
In the coating composition (B), it is more preferable to use an aqueous medium containing water as the medium from the viewpoints of film forming properties, smoothing of the coating surface, and environmental protection.
The aqueous medium is not particularly limited as long as it uses water as the medium. For example, the aqueous medium may contain the organic solvent. From the viewpoint of environmental protection, water is 70 to 100 in the medium. It is preferable that it is mass%, and it is more preferable that it is 100 mass%.
[0071]
When the aqueous medium is used as the medium, a dispersant is preferably used in order to improve the dispersibility and film-forming property of the meltable fluororesin (b). As the dispersant, for example, the same dispersant as described above for the coating composition (A) may be used. However, in the present invention, in order to improve the smoothness of the coating film surface obtained, A surfactant is preferred.
[0072]
As said nonionic surfactant, it is preferable that hydrophilic-lipophilic balance [HLB] is 15 or more from the point that film forming property and decomposability are favorable. If it is less than 15, the film-forming property may be insufficient and cracks may be generated in the coating film, or it may not be sufficiently decomposed during firing described later, and may remain in the coating film to deteriorate the coating film properties. More preferably, it is 15-20, More preferably, it is 15-18.
In this specification, HLB means the value calculated | required by a following formula.
HLB =% by weight of hydrophilic group / 5
[0073]
Such a nonionic surfactant is not particularly limited as long as the HLB is 15 or more. For example, polyethylene glycol, polyethylene glycol alkyl ether, polyethylene glycol alkyl phenyl ether, polyethylene glycol alkyl ester, polyethylene glycol polypropylene glycol polyethylene glycol It is a block copolymer, polyoxyethylene sorbitan monoalkylate, etc., and HLB should just be 15 or more, and these can use 1 type, or 2 or more types.
[0074]
It is preferable that the said nonionic surfactant is 8-20 mass parts with respect to 100 mass parts of said meltable fluororesins (b) on the solid content basis. If the amount is less than 8 parts by mass, the film-forming property tends to be insufficient. If the amount exceeds 20 parts by mass, the remaining amount in the coating film increases, which may lead to deterioration of the coating film properties. More preferably, it is 12-18 mass parts.
[0075]
The coating composition (B) is preferably an aqueous dispersion of the meltable fluororesin (b). The aqueous dispersion of the meltable fluororesin (b) is a dispersion using the aqueous medium as the medium and using the melt as a dispersion medium and the meltable fluororesin (b) as a dispersoid.
[0076]
The aqueous dispersion of the meltable fluororesin (b) preferably contains the dispersant, and more preferably contains the nonionic surfactant. The aqueous dispersion of the meltable fluororesin (b) preferably uses a drying retarder. As said drying retarder, the thing similar to what was mentioned above about the said coating composition (A) can be used, for example.
[0077]
The aqueous dispersion of the meltable fluororesin (b) is prepared by, for example, dispersing the meltable fluororesin (b) obtained by emulsion polymerization with the aqueous medium, and preferably the dispersant and the drying retarder. It can be used as a water-based paint and painted.
[0078]
The coating composition (B) can be easily prepared by, for example, a conventionally known method using the meltable fluororesin (b) and optionally the medium and / or the various additives. As the method for preparing the coating composition (B), for example, the above-described fluororubber (a2), the vulcanizing agent, the vulcanization aid and the acid acceptor are not added. ) Can be prepared according to the method of blending with the fluororubber (a2).
[0079]
The method for producing a fluororesin coating according to the present invention comprises applying the coating composition (A) to an object to be coated and drying, then applying the coating composition (B), and firing the coating. The coating composition (B) is applied before the fluororubber (a2) is vulcanized.
[0080]
The object to be coated is not particularly limited as long as it has a heat-resistant temperature exceeding the temperature at which the baking is performed, and can be selected according to the application, for example, iron, stainless steel, copper, aluminum, brass, etc. Metals; Glass products such as glass plates, woven and non-woven fabrics of glass fibers; Molding of general-purpose resins and heat-resistant resins such as polypropylene, polyoxymethylene, polyimide, polyamideimide, polysulfone, polyethersulfone, and polyetheretherketone Articles and coatings; moldings and coatings of general-purpose rubbers such as SBR, butyl rubber, NBR and EPDM; moldings and coatings of heat-resistant rubbers such as silicone rubber and fluororubber; woven and non-woven fabrics of natural and synthetic fibers These may be used, and one or more of these may be used.
[0081]
Among the above-mentioned objects to be coated, in many cases, they are suitable for the uses described later, and those containing metals and / or elastic bodies are preferred from the point of being frequently used. The elastic body contains a material having elasticity such as the above-mentioned general-purpose rubber and heat-resistant rubber. As the elastic body, in order to prevent deterioration due to firing described later, one using the heat-resistant rubber is preferable, and one using silicone rubber is more preferable.
[0082]
Although the said to-be-coated article is a board | substrate used for the use which contacts with other materials, such as a roll for OA equipment, a belt for OA equipment, etc. depending on a use, it has elasticity in order to secure a contact area with other materials. It is preferable. As the object to be coated having elasticity, the elastic body is preferable, and when it contains a non-elastic body such as metals, the elastic body is laminated on the non-elastic body in order to obtain elasticity. Those are preferred.
[0083]
Although the said to-be-coated article is based on the material, what gave the surface degreasing and / or washing | cleaning may be sufficient. In particular, when the object to be coated is a metal, it is preferable to degrease and wash the surface. In this case, for example, a layer made of silicone rubber can be formed after degreasing and washing the surface.
[0084]
Although the said to-be-coated article is based on the material, after giving the said degreasing and / or washing | cleaning, without applying the said degreasing and / or washing | cleaning, you may apply | coat the primer as undercoat. The said to-be-coated object can improve adhesiveness with the above-mentioned coating composition (A) layer by the said primer being apply | coated.
[0085]
It does not specifically limit as said primer, It can select according to the material of the said to-be-coated object, For example, commercially available undercoat for fluororubber can be used. Examples of the primer include silane primers such as silane coupling agents; silicone primers such as silicone resins; other coupling agents such as titanium coupling agents and aluminum coupling agents; epoxy resins, phenol resins, epoxy / Other resin primers such as phenol resin and acrylic resin can be used.
[0086]
In the case where the object to be coated has silicone rubber on the surface, it is preferable that the primer is further applied thereon.
[0087]
The coating composition (A) is applied by a conventionally known method such as further addition of the above-mentioned medium when applied for the purpose of improving the coating workability, improving the physical properties of the obtained coating film, etc. It may be diluted. In addition, you may dilute similarly about the said coating composition (B).
[0088]
The method of applying the coating composition (A) to the object to be coated is not particularly limited, and for example, a conventionally known method such as brush coating, spray coating, dip coating, flow coating, dispenser coating, screen coating or the like is used. be able to.
[0089]
After the coating composition (A) is applied, the organic solvent or water used as the medium is evaporated to evaporate. The drying is performed, for example, at room temperature to 100 ° C. for 10 to 120 minutes.
[0090]
The coating composition (B) is applied on the coating composition (A) layer thus obtained. In the step of applying the coating composition (B), the fluororubber (a2) is not substantially vulcanized in the coating composition (A) layer, and the meltable fluororesin (a1) is melted. Not done.
[0091]
After application of the coating composition (B), the coating composition is dried as necessary and then baked. As the coating and drying method, the same method as that for the coating composition (A) can be used.
The firing is performed at a firing temperature within a specific range from the viewpoint of smoothing the surface of the obtained coating film while preventing deterioration of the article to be coated and the meltable fluororesin.
[0092]
The lower limit of the firing temperature within the specific range is a temperature that is 10 ° C. higher than the higher one of the melting point of the meltable fluororesin (a1) and the melting point of the meltable fluororesin (b). If it is less than the lower limit, the meltable fluororesin (a1) and the meltable fluororesin (b) do not melt, or the melt viscosity is insufficient even when melted, and the film-forming property is inferior. A coating film having a sufficiently smooth surface cannot be obtained.
[0093]
The upper limit of the firing temperature within the specific range is less than the lowest temperature among the decomposition temperature of the meltable fluororesin (a1), the decomposition temperature of the meltable fluororesin (b), and the heat resistance temperature of the object to be coated. Temperature. If the above upper limit is exceeded, the meltable fluororesin will decompose and the original excellent properties such as non-adhesiveness will not be obtained sufficiently, or the object to be coated will be thermally deteriorated and the desired quality Cannot be obtained.
[0094]
As the upper limit of the firing temperature, when the object to be coated contains silicone rubber and the primer is applied, the lower one of the heat resistant temperature of the silicone rubber and the heat resistant temperature of the primer It is preferable that the temperature is lower than the above temperature. When the upper limit is exceeded, the silicone rubber is thermally deteriorated and sufficient elasticity cannot be obtained, or the primer is decomposed and the adhesion between the article to be coated and the coating composition (A) layer is increased. Insufficient and may cause delamination. In general, since the heat resistance temperature of the primer is lower than the heat resistance temperature of the silicone rubber, the upper limit of the baking temperature is often governed by the heat resistance temperature of the primer.
[0095]
As the firing temperature, for example, in the case where the object to be coated contains silicone rubber and the primer is applied, the melting fluorine depends on the heat resistance temperature of the silicone rubber to be used and the heat resistance temperature of the primer to be used. When using PFA as resin, 320-330 degreeC is preferable, and when using FEP as said meltable fluororesin, 250-310 degreeC is preferable.
[0096]
The firing is preferably performed for 0.25 to 8 hours, although it depends on the firing temperature.
By performing the firing, the meltable fluororesin (a1) in the coating composition (A) bleeds up to the surface of the coating composition (A) layer, and is fused to the meltable fluororesin (b). At the same time, vulcanization of the fluororubber (a2) occurs, and it is considered that as the vulcanization progresses, the bond between the fluororubber (a2) and the meltable fluororesin (a1) proceeds.
[0097]
The film thickness of the coating film formed from the coating composition (B) depends on the average particle diameter, use, etc. of the meltable fluororesin (b) used, but is preferably 1 to 20 μm after the firing. . When the thickness is less than 1 μm, the use durability of the layer made of the meltable fluororesin may be insufficient, and when the film thickness of the layer made of the meltable fluororesin is not particularly required, There is no particular need to use the method for producing a fluororesin coating according to the present invention. When it exceeds 20 μm, it is not easy to obtain by using the meltable fluororesin (b) having an average particle diameter within the above-mentioned range. More preferably, it is 1-15 micrometers, More preferably, it is 2-10 micrometers.
[0098]
The fluororesin coating of the present invention is manufactured by the above fluororesin coating manufacturing method. In this specification, the said fluororesin coating means what has a coating film formed on the said to-be-coated article. Accordingly, the fluororesin coating may be only a coating film formed on the object to be coated, or may be a coating film formed on the object to be coated and the object to be coated. The surface and / or the back surface may be subjected to surface treatment such as formation of other layers such as coating, washing, and polishing of the back surface as necessary.
[0099]
The fluororesin coating has a smooth surface.
The fluororesin coating has a surface roughness [Rz] of 2 μm or less. When the thickness exceeds 2 μm, the surface smoothness becomes insufficient, and contaminants such as paper pieces and toner are liable to adhere, resulting in poor long-term use durability. For example, when used for rolls for OA equipment, belts for OA equipment, etc. This causes problems such as disturbance of a fixed image on the recording medium and a tendency to cause paper jams. Preferably, it is 1.6 μm or less, and usually 0.8 μm or more.
[0100]
The surface roughness [Rz] is a ten-point average roughness defined in JIS-B0601. In the present specification, Rz is a value measured using a surface roughness meter (trade name: Surfcom 470A, manufactured by Tokyo Seiki Co., Ltd.) with a measurement length of 4 mm.
[0101]
The fluororesin coating preferably has a surface contact angle with water of 102 to 130 °. If the angle is less than 102 °, the releasability may be inferior, or the surface smoothness may be inferior and the above problems such as adhesion of contaminants may occur. If the angle exceeds 130 °, a separate surface smoothing treatment is required. And may deviate from the object of the present invention, such as simplification of processes and reduction of energy. More preferably, it is 102-110 degrees. In the present specification, the contact angle is a value measured using a goniometer (manufactured by Kyowa Interface Science Co., Ltd.) as a contact angle meter.
[0102]
The fluororesin coating preferably has a surface gloss (60 ° -60 °) of 50% or more. If it is less than 50%, the surface smoothness may be inferior, or the commercial value may decrease depending on the application. More preferably, it is 50 to 95%. In the present specification, the gloss (60 ° -60 °) is a value measured using a digital variable gloss meter (manufactured by Suga Test Instruments Co., Ltd.).
[0103]
The method for producing a fluororesin coating according to the present invention uses the meltable fluororesin (a1) and the meltable fluororesin (b), and applies the fluororubber (a2) before applying the coating composition (B). Since calcination is performed without performing vulcanization, the coating film surface of the obtained fluororesin coating can have good smoothness. The mechanism by which the fluororesin coating production method of the present invention exhibits such advantageous effects is not clear, but is considered as follows.
[0104]
That is, unlike the conventional case where the smoothness of the coating film surface obtained by vulcanizing fluororubber and applying and baking a fluororesin composition is impaired, the present invention falls within the above specified range. The fluororubber (a2), the meltable fluororesin (a1), and the meltable fluororesin (b) are softened or melted at the same time or almost at the same time, and the meltability is further increased. As a result of the relatively low melt viscosity of the fluororesin and excellent fluidity at the time of melting, it is considered that the surface of the obtained coating film is smoothed and smoothed and smoothed.
[0105]
The fluororesin-coated material production method of the present invention also eliminates the need for vulcanizing the fluororubber (a2) as a single step, and does not require a separate surface smoothing treatment after coating film formation. Since the process can be simplified and energy, time, labor and the like can be reduced, this is an industrially advantageous production method.
[0106]
According to the method for producing a fluororesin-coated product of the present invention, it is possible to further increase the thickness of the layer made of the above-mentioned meltable fluororesin on the surface, and to obtain a coating film that is excellent in film forming properties and has no cracks or delamination This makes it possible to produce a fluororesin coating having a coating film excellent in durability for use without impairing the original properties of the fluororesin such as non-adhesive properties for a long period of time.
[0107]
Since the fluororesin coating has a layer made of the meltable fluororesin on the surface, it is a field where characteristics of fluororesin such as heat resistance, solvent resistance, lubricity and non-adhesiveness are required. For example, rolls for OA equipment such as fixing rolls and pressure rolls used for OA equipment such as copying machines, printers, facsimiles, etc .; transport belts for the OA equipment; sheets and belts; O-rings And other industrial products such as diaphragms, chemical resistant tubes, fuel hoses, valve seals, gaskets for chemical plants, engine gaskets, and the like.
[0108]
The fluororesin coating is suitable for rolls for OA equipment or belts for OA equipment from the viewpoint that it can exhibit the original properties of the fluororesin such as non-adhesiveness and has a smooth surface. It is preferably used and is a roll for OA equipment or a belt for OA equipment.
[0109]
【Example】
EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited only to these examples.
Preparation Example 1 Preparation of “Fluororubber Dispersion A”
A copolymer of VdF, TFE, and HFP was produced by emulsion polymerization, and the resulting polymerization mixed solution was used as a nonionic surfactant, 20% by weight of HS-208 (HLB = 12.6, manufactured by NOF Corporation). It concentrated using the mixture with 20 weight% aqueous solution of aqueous solution and HS-215 (HLB = 15.0, Nippon Oil & Fats Co., Ltd.), and made solid content concentration 60 weight%. This is referred to as “fluororubber dispersion A”.
[0110]
Preparation Example 2 Preparation of “Pig Paste”
2 wt% aqueous solution of HS-208 2 as a surfactant with 3 parts by weight of a filler (Tarox R-516L, manufactured by Titanium Industry Co., Ltd.) and 5 parts by weight of an acid acceptor (DHT-4A, manufactured by Kyowa Chemical Industry Co., Ltd.) 2 A paste was prepared by dispersing in 46 parts by weight of pure water together with parts by weight. This is called “Pig paste”.
[0111]
Preparation Example 3 Preparation of “Fluororubber paint main agent”
70 parts by weight of “fluororubber dispersion A”, 23.5 parts by weight of “Pig paste”, 6 parts by weight of 5% by weight DS-60HN (manufactured by NOF Corporation) as thickener A, UH as thickener B 0.5 parts by weight of a 50 wt% aqueous solution of −140S (Asahi Denka Kogyo Co., Ltd.) was mixed and sufficiently dispersed.
[0112]
Preparation Example 4 Preparation of “FEP Dispersion”
A TFE / HFP copolymer [FEP] is produced by emulsion polymerization, and the resulting polymerization mixed solution is concentrated using 20 wt% aqueous solutions of HS-208 and HS-215 as surfactants, The partial concentration was 60% by weight, and HS-208 and HS-215 were each 4 parts by weight with respect to 100 parts by weight of FEP on a solid basis. The melting point was 240 ° C., the MFR was 1 g / 10 min, and the average particle size was 0.18 μm. This is referred to as “FEP dispersion”.
[0113]
Preparation Example 5 Preparation of “PFA dispersion”
A TFE / PFVE copolymer [PFA] was produced by emulsion polymerization, and the resulting polymerization mixed solution was concentrated using 20 wt% aqueous solutions of HS-208 and HS-215 as surfactants to obtain solids. The partial concentration was 60% by weight, and HS-208 and HS-215 were each 4 parts by weight with respect to 100 parts by weight of PFA on a solid basis. The melting point was 310 ° C., the MFR was 55 g / 10 min, and the average particle size was 0.19 μm. This is referred to as “PFA dispersion”.
[0114]
Preparation Example 6 Preparation of “EPA Dispersion”
A TFE / HFP / PFVE copolymer [EPA] is produced by emulsion polymerization, and the resulting polymerization mixture solution is concentrated using 20 wt% aqueous solutions of HS-208 and HS-215 as surfactants. The solid content concentration was 60% by weight, and HS-208 and HS-215 were each 4 parts by weight with respect to 100 parts by weight of EPA based on the solid content. The melting point was 275 ° C., the MFR was 20 g / 10 min, and the average particle size was 0.18 μm. This is referred to as “EPA dispersion”.
[0115]
Preparation Example 7 Preparation of “vulcanizing agent solution A”
3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxa-2-spiro [5,5] -undecane (Epomate F-100, manufactured by Yuka Shell Co.) in 50% aqueous solution -Aminopropyltriethoxysilane (A-1100, manufactured by Nihon Unicar) 60% aqueous solution was mixed at a ratio of 4/6 by weight to prepare. This is designated as “vulcanizing agent solution A”.
[0116]
Preparation Example 8 Preparation of “vulcanizing agent solution B”
A 60% aqueous solution of γ-aminopropyltriethoxysilane (A-1100, manufactured by Nihon Unicar Company) was prepared. This is designated as “vulcanizing agent solution B”.
[0117]
Preparation Example 9 Preparation of “Paint A1”
100 parts by weight of “fluorine rubber paint main component” and 70 parts by weight of “FEP dispersion” were mixed (fluorine rubber: FEP = 50: 50 weight ratio based on solid content) and sufficiently dispersed. A coating material was prepared by mixing 5 parts by weight of “vulcanizing agent solution A” with 100 parts by weight of this aqueous dispersion. This is referred to as “paint A1”.
[0118]
Preparation Example 10 Preparation of “Paint A2”
100 parts by weight of “fluorine rubber paint main component” and 70 parts by weight of “FEP dispersion” were mixed (fluorine rubber: FEP = 50: 50 weight ratio based on solid content) and sufficiently dispersed. A coating material was prepared by mixing 5 parts by weight of “vulcanizing agent solution B” with 100 parts by weight of this aqueous dispersion. This is designated as “paint A2”.
[0119]
Preparation Example 11 Preparation of “Paint A3”
100 parts by weight of “fluororubber paint main agent” and 47 parts by weight of “FEP dispersion” were mixed (fluorine rubber: FEP = 60: 40 weight ratio based on solid content) and sufficiently dispersed. A coating material was prepared by mixing 5 parts by weight of “vulcanizing agent solution A” with 100 parts by weight of this aqueous dispersion. This is designated as “paint A3”.
[0120]
Preparation Example 12 Preparation of “Paint A4”
95 parts by weight of “fluorine rubber paint main component” and 100 parts by weight of “FEP dispersion” were mixed (fluorine rubber: FEP = 40: 60 weight ratio on a solid basis) and sufficiently dispersed. A coating material was prepared by mixing 5 parts by weight of “vulcanizing agent solution A” with 100 parts by weight of this aqueous dispersion. This is designated as “paint A4”.
[0121]
Preparation Example 13 Preparation of “Paint B”
100 parts by weight of “fluorine rubber paint main component” and 70 parts by weight of “PFA dispersion” were mixed (fluorine rubber: PFA = 50: 50 weight ratio based on solid content) and sufficiently dispersed. A coating material was prepared by mixing 5 parts by weight of “vulcanizing agent solution A” with 100 parts by weight of this aqueous dispersion. This is designated as “paint B”.
[0122]
Preparation Example 14 Preparation of “Paint C”
100 parts by weight of “fluorine rubber paint main component” and 70 parts by weight of “EPA dispersion” were mixed (fluorine rubber: EPA = 50: 50 weight ratio based on solid content) and sufficiently dispersed. A coating material was prepared by mixing 5 parts by weight of “vulcanizing agent solution A” with 100 parts by weight of this aqueous dispersion. This is referred to as “paint C”.
[0123]
Preparation Example 15 Preparation of “PFA paint”
A TFE / PFVE copolymer [PFA] was produced by emulsion polymerization, and the resulting polymerization mixed solution was concentrated using 20 wt% aqueous solutions of HS-208 and HS-215 as surfactants to obtain solids. The partial concentration was 60% by weight. The melting point was 310 ° C., the MFR was 25 g / 10 min, and the average particle size was 0.24 μm. 100 parts by weight of this dispersion was mixed and dispersed with 20 parts by weight of a 30% aqueous solution of Emulgen 120 (HLB = 15.3, manufactured by Kao Corporation) as a nonionic surfactant and 10 parts by weight of ethylene glycol. Prepared. This is referred to as “PFA paint”.
[0124]
Example 1
(Creation of painted plate)
“Paint A1” is spray-coated on the upper half of the surface of an aluminum plate previously washed with acetone, dried at 80 to 100 ° C. for 15 minutes, then air-cooled to room temperature, and a lower coating film having a film thickness of about 30 μm is produced. did. Then, “PFA paint” is spray-coated on the entire surface of the coated plate, dried at room temperature for about 1 hour and at 80 to 100 ° C. for 15 minutes, and then baked at 325 ° C. for 30 minutes to give a total film thickness of about 40 μm. A board was created.
[0125]
(Evaluation of coating properties)
The characteristics of the coating film surface of the obtained coated plate were evaluated as follows. The results are shown in Table 1.
1. Paint film appearance
The presence or absence of cracks, foaming, blisters, swelling, etc. on the surface of the coating film was visually observed and evaluated.
2. Water contact angle
One drop of pure water was dropped on the surface of the coating film, and the contact angle was measured using a goniometer (manufactured by Kyowa Interface Science Co., Ltd.).
[0126]
3. Surface roughness
The ten-point average surface roughness [Rz] of the coating film surface was measured using a surface roughness meter (Surfcom 470A, manufactured by Tokyo Seiki Co., Ltd.) with a measurement length of 4 mm.
4). Luster
The gloss (60 ° -60 °) on the surface of the coating film was measured using a digital variable gloss meter (manufactured by Suga Test Instruments Co., Ltd.).
[0127]
Example 2
A coated plate was prepared and evaluated in the same manner as in Example 1 except that “paint A2” was used instead of “paint A1”.
Example 3
A coated plate was prepared and evaluated in the same manner as in Example 1 except that “paint A3” was used instead of “paint A1”.
[0128]
Example 4
A coated plate was prepared and evaluated in the same manner as in Example 1 except that “paint A4” was used instead of “paint A1”.
Example 5
A coated plate was prepared and evaluated in the same manner as in Example 1 except that “paint B” was used instead of “paint A1”.
[0129]
Example 6
A coated plate was prepared and evaluated in the same manner as in Example 1 except that “paint C” was used instead of “paint A1”.
Comparative Example 1
A coated plate was prepared and evaluated in the same manner as in Example 1 except that “PFA dispersion” was used instead of “PFA paint”.
[0130]
Comparative Example 2
Example except that PFA water-based paint (AW-5000, manufactured by Daikin Industries, melting point: 300 ° C., MFR: 20 g / 10 min, average particle size: 25 μm) was used instead of “PFA paint”. A coated plate was prepared and evaluated in the same manner as in 1.
Comparative Example 3
In the preparation of the coated plate, “Coating A1” was applied, dried at 80 to 100 ° C. for 15 minutes, and then air-cooled, followed by adding a step of baking at 200 ° C. for 2 hours. A painted board was created and evaluated.
[0131]
[Table 1]

[0132]
From Table 1, each example has a surface roughness [Rz] of 2 μm or less, a gloss and a water contact angle that are relatively large values, so that the surface smoothness is good, and the coating film appearance is also good. In contrast, each Comparative Example has an Rz of more than 2 μm and is inferior in the appearance of the coating film. Comparative Example 3 vulcanized before the coating composition (B) was applied, and the coating composition ( In Comparative Example 2 and Comparative Example 3 where B) does not contain a nonionic surfactant or the average particle diameter of the meltable fluororesin (b) is not in the range of 0.2 to 1 μm, surface smoothness and It was found that the coating film appearance was inferior.
[0133]
【The invention's effect】
Since the fluororesin-coated material manufacturing method of the present invention has the above-described configuration, it has surface smoothness without having to go through a single step for vulcanizing fluororubber and a separate surface smoothing treatment step. A coating film can be obtained, the process can be simplified, energy, time, labor, etc. can be reduced, and the layer made of a fluororesin can be thickened to maintain its properties for a long period of time.

Claims (7)

The coating composition (B) containing the fusible fluororesin (b) is coated with the coating composition (A) containing the fusible fluororesin (a1) and fluororubber (a2) and dried. A method for producing a fluororesin coating for producing a fluororesin coating comprising applying and baking,
The coating composition (B) is an aqueous dispersion of a meltable fluororesin (b) having an average particle size of 0.2 to 1 μm,
The coating composition (B) further contains a nonionic surfactant having a hydrophilic / lipophilic balance [HLB] of 15 or more, and the nonionic surfactant is meltable on a solid content basis. 8 to 20 parts by mass with respect to 100 parts by mass of the fluororesin (b),
The coating composition (B) is applied before vulcanizing the fluororubber (a2),
In the firing, the lower limit is a temperature 10 ° C. higher than the higher one of the melting point of the meltable fluororesin (a1) and the melting point of the meltable fluororesin (b), and the upper limit is the meltable fluororesin ( a1), the melting temperature of the meltable fluororesin (b), and the temperature range that is lower than the lowest temperature among the heat-resistant temperatures of the object to be coated,
The method for producing a fluororesin coating, wherein the fluororesin coating has a surface roughness [Rz] of 2 μm or less. The method for producing a fluororesin coating according to claim 1 , wherein the fluororesin coating has a surface gloss (60 ° -60 °) of 50% or more. The method for producing a fluororesin coating according to claim 1 or 2 , wherein the coating film formed from the coating composition (B) has a thickness of 1 to 20 µm. The blending ratio of the fluororubber (a2) and the meltable fluororesin (a1) is 30:70 to 70:30, where the fluororubber (a2): the meltable fluororesin (a1) is 30:70 to 70:30 as a mass ratio based on solid content The method for producing a fluororesin coating according to claim 1, 2 or 3 . The method for producing a fluororesin coating according to claim 1, 2, 3, or 4, wherein the meltable fluororesin (a1) and the meltable fluororesin (b) have a melting point of 320 ° C or lower. The meltable fluororesin (b) is a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene / hexafluoropropylene copolymer or tetrafluoroethylene / hexafluoropropylene / perfluoro (alkyl vinyl ether) copolymer. The method for producing a fluororesin coating according to claim 1, 2, 3, 4, or 5 . The process for producing a fluororesin coating according to claim 1, 2, 3, 4, or 5, wherein the meltable fluororesin (b) is a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer.