JP3930135B2 - Metallic finishing method - Google Patents

Description

【００２４】
式中、Ｒ₁は水素またはメチル基を表わし、Ｒ₂は炭化水素基または置換基 を有する炭化水素またはオキシアルキレン基を含む有機基を表わし、Ａは炭 素数２ないし４個のアルキレン基または置換されたアルキレン基を表わし、 ｎは０または正の数であり、Ｍはアルカリまたはアルカリ土類金属、アンモ ニウム、有機アミン塩基、または有機第四級アンモニウム塩基などを意味し 、ｍはＭの原子価またはイオン価である、
で示されるスルホン酸塩；または下記一般式▲３▼または▲４▼
【００２５】
【化２】

【００２６】
式中、Ｒ₁は置換基を有してもよい炭化水素基、フェニル基、アミノ基またはカルボン酸残基を表わし、Ｒ₂は水素原子またはメチル基を表し、Ａは炭素数２ないし４のアルキレン基を表わし、ｎは０ないし１００の正の数であり、Ｍは１価または２価の陽イオンを表わし、ｍはＭのイオン価を表す、
で示されるスルホコハク酸ジエステル塩；または下記一般式▲５▼
【００２７】
【化３】

【００２８】
式中、Ｒ₁は炭素数４〜１８のアルキル基、アルケニル基、もしくはアラルキル基を表わし、Ｒ₂は水素または炭素数４〜１８のアルキル基、アルケニル基、もしくはアラルキル基を表わし、Ａは炭素数２〜４のアルキレン基もしくは置換アルキレン基を表わし、ｎは２〜２００の整数であり、Ｍはアルカリ金属原子、ＮＨ、アルカノールアミン残基を表わす、
で示される化合物などがある。これらはそれ自体既知のものであり（例えば特公昭４９−４６２９１号公報、特開昭５８−２０３９６０号公報、特開昭６２−２２１４３１号公報、特開昭６３−２３７２５号公報など参照。）、「エレミノールＪＳ−２」（商品名、三洋化成工業株式会社製) 、「ラテムルＳ」シリーズ（商品名、花王株式会社製）、「アクアロンＨＳ」シリーズ（商品名、第一工業製薬株式会社製）などとして市販されている。
【００２９】
ＩＩ）アリル基含有カチオン性反応性乳化剤
代表的なものとして下記一般式▲６▼
【００３０】
【化４】

【００３１】
式中、Ｒ₁は置換基を有してもよい炭素数８〜２２の炭化水素基を表わし、Ｒ₂およびＲ₃は炭素数１〜３のアルキル基を表わし、Ｒ₄は水素原子、ま たはメチル基を表わし、Ｘ^-は１価の陰イオンを表わす、
で示される第四級アンモニウム塩を有する反応性乳化剤が挙げられる。このものはそれ自体既知であり（特開昭６０−７８９４７号公報参照）、例えば「ラテムルＫ−１８０」（商品名、花王株式会社製）として市販されている。
【００３２】
ＩＩＩ）アリル基含有非イオン性反応性乳化剤
代表的なものとして下記一般式▲７▼
【００３３】
【化５】

【００３４】
式中、Ｒ₁は炭素数４〜１８のアルキル基、アルケニル基もしくはアラルキル基を表わし、Ｒ₂は水素または炭素数４〜１８のアルキル基、アルケニル基もしくはアラルキル基を表わし、Ａは炭素数２〜４のアルキレン基もしくは置換アルキレン基を表わし、ｎは２〜２００の整数である、
で示される化合物が挙げられる。このものはそれ自体既知であり（特開昭６２−１００５０２号公報参照）、例えば「Ｈ−３３５５Ｎ」（商品名、第一工業製薬製）として市販されている。
【００３５】
上記乳化重合においては比較的低反応性の基であるアクリル基を含有する反応性乳化剤であれば、上記アニオン性、カチオン性、非イオン性の何れの反応性乳化剤も前記代表例として例示したものに限定されることなく広く使用することができるが、重合中徐々に重合体に取り込まれていく反応性乳化剤が適しており、本発明においてはカチオン性反応性乳化剤が好適である。
【００３６】
非イオン性の反応性乳化剤アニオン性反応性乳化剤またはカチオン性反応性乳化剤と任意の割合で混合して使用でき、その混合比率は所望の特性に応じて適宜選択される。
【００３７】
反応性乳化剤の使用量は、単独で使用する場合も、また、カチオン性反応性乳化剤と非イオン性反応性乳化剤の混合物またはアニオン性反応性乳化剤と非イオン性反応性乳化剤の混合物として使用する場合も、全量で、通常重合体微粒子（ｃ）を構成するモノマー（ｉ）〜（ｉｉｉ）の合計１００重量部に対して一般に０．１〜３０重量部、好ましくは０．５〜５重量部の範囲内とするのが適当である。
【００３８】
上記乳化重合に用いる重合開始剤としては、下記一般式▲８▼
【００３９】
【化６】

【００４０】
式中、Ｘは炭素原子数２〜１２個の直鎖または分岐鎖アルキレン基を表わす、
または、下記一般式▲９▼
【００４１】
【化７】

【００４２】
式中、Ｘ¹、Ｘ²及びＸ³は少なくとも１個が水酸基であり、残りは水素で ある、
で示される水溶性アゾアミド化合物が特に適している。これらのものはそれ自体既知であり（特開昭６１−２１８６１８号公報、特開昭６１−６３６４３号公報参照）、例えばＶＡシリーズ（商品名、和光純薬株式会社製）として市販されている。重合開始剤の必要使用量は、当該技術分野において明らかである。一般的に、最適必要量は微粒子重合体（ｃ）を形成するモノマー（ｉ）〜（ｉｉｉ）の合計１００重量部に対して０．１〜１．５重量部の範囲内である。
【００４３】
上記モノマー（ｉ）〜（ｉｉｉ）の共重合は、アクリル共重合体を製造するためのそれ自体既知の方法である乳化重合法によって行うことができる。上記のモノマー混合物を水媒体中でアリル基を含有する反応性乳化剤及び水溶性アゾアミド化合物重合開始剤の存在下に通常約５０〜１００℃、好ましくは８０〜９５℃の反応温度において約１〜約２０時間反応を続けることにより行うことができる。
【００４４】
乳化重合によって得られる重合体微粒子（ｃ）の水分散液は総重量に基づいて通常、約１０〜４０重量％の樹脂固形分を有する。水分散液中の微粒子重合体（ｃ）の粒径は一般に５００ｎｍ以下、好ましくは５０〜１００ｎｍの範囲内である。粒径の調整は分子内にアリル基を有する反応性乳化剤の種類や量を調整することによって行なうことができ、容易に所望の範囲の粒径を有する微粒子重合体（ｃ）を得ることができる。
【００４５】
バインダー樹脂（ａ）に対する希釈剤（ｂ）の配合割合は、バインダー樹脂（ａ）を均一に溶解することができ、且つ重合体微粒子（ｃ）がバインダー樹脂（ａ）の希釈剤（ｂ）溶液中に安定に分散できるような量的割合であれば特に限定されるものではないが、取り扱い易さ、貯蔵安定性などの点から、希釈剤（ｂ）は通常、バインダー樹脂（ａ）１００重量部に対して２００〜６００重量部の範囲内で用いるのが望ましい。また、バインダー樹脂（ａ）に対する重合体微粒子（ｃ）との配合割合は、一般的には、バインダー樹脂（ａ）１００重量部あたり重合体微粒子（ｃ）１〜５０重量部、好ましくは５〜４０重量部、さらに好ましくは５〜３０重量部の範囲内で用いることが望ましい。
【００４６】
本発明において、重合体微粒子（ｃ）は通常、バインダー樹脂（ａ）と希釈剤（ｂ）とを含有する均一な系中に添加、配合される。その際、重合体微粒子（ｃ）は、有機溶剤中に分散した形に変換してから配合することが望ましい。重合体微粒子（ｃ）の水分散液から有機溶剤分散液への転換は、重合体微粒子（ｃ）の水分散液をスプレードライ方式や単純な乾燥等によって水を蒸発させた後、樹脂固形分を取り出し、ついでそれを有機溶剤中に再分散することによっておこなうことができる。
【００４７】
本発明において、上記非メタリック塗料（Ａ）は、被塗物に直接塗装することもできるが、電着塗料（アニオン型、カチオン型）などのプライマーおよび熱硬化性中塗り塗料を塗装し、これらの塗膜を硬化させた後に塗装することが好ましい。塗装機としては霧化式塗装機を用いることが好ましく、例えば、エアースプレー塗装機、エアレススプレー塗装機およびエアー霧化式もしくは回転式静電塗装機などが挙げられ、塗装時の塗料粘度は、フォードカップ＃４で約１５〜約６０秒、特に１５〜３５秒（２０℃）に調整しておくことが好ましく、塗装膜厚は加熱硬化膜厚に基づいて約２〜約２０μｍ、特に約５〜約１５μｍが適している。
【００４８】
塗着した非メタリック塗料（Ａ）の粘度調整は、塗装時における該塗料の不揮発分濃度、溶剤組成、粘度などを適宜調整することによって容易に行なうことができ、塗装直後の塗着粘度が低い場合には室温で放置するかもしくは予備加熱して溶剤などを揮発せしめることによって調整できる。非メタリック塗料（Ａ）と次に説明する水性メタリック塗料（Ｂ）との塗装間隔をできるだけ短縮するには、非メタリック塗料（Ａ）の塗装直後の塗着粘度が高くなるように、該非メタリック塗料（Ａ）に粘度調整剤を配合しておくことであり、かかる粘度調整剤としては公知の各種のものを使用できる。具体例としては、例えば、「ベントン２７」（ＮＬケミカル社製、チキソトロピック性付与剤）、「エロジル＃２００」（日本エアロジル社製、シリカ系チキソトロピック性付与剤）などを挙げることができる。
【００４９】
熱硬化型水性メタリック塗料（Ｂ）：
該水性メタリック塗料（Ｂ）は、前記メタリック顔料を含有しない有機溶液型または非水分散型熱硬化性塗料（Ａ）塗膜面上に塗装する塗料であって、水をその主たる溶媒とし、水溶性もしくは水分散型熱硬化型アクリル樹脂、メタリック顔料を主成分とし、必要に応じて着色顔料、体質顔料、塗面調整剤、粘度調整剤などを配合してなるものである。
【００５０】
該水性メタリック塗料（Ｂ）の構成成分である水溶性もしくは水分散型熱硬化型アクリル樹脂としては、従来から公知のものは全て包含される。その代表例として、例えば水溶性アクリル樹脂としては、α，β−モノエチレン性不飽和カルボン酸、そのヒドロキシアルキルエステル及びその他のα，β−モノエチレン性不飽和単量体から選ばれた１種又は２種以上の単量体を重合して得られる酸価約２０〜約１００及び水酸基価約２０〜約２００のアクリル樹脂を挙げることができる。
【００５１】
上記した水溶性アクリル樹脂の原料である重合性不飽和単量体にはアクリル酸、メタクリル酸、マレイン酸、イタコン酸などのα，β−モノエチレン性不飽和カルボン酸類と（メタ）アクリル酸２−ヒドロキシエチル、（メタ）アクリル酸２−ヒドロキシプロピルなどのα，β−モノエチレン性不飽和カルボン酸のヒドロキシアルキルエステル類と（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ｎ−ブチル、（メタ）アクリル酸イソブチル、（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸ラウリル、（メタ）アクリル酸デシルなどのα，β−モノエチレン性不飽和カルボン酸のアルキルエステル類；（メタ）アクリルアミド、Ｎ−メチロール（メタ）アクリルアミド、ジアセトンアクリルアミドなどの（メタ）アクリルアミド誘導体；（メタ）アクリル酸グリシジルなどのα，β−モノエチレン性不飽和カルボン酸のグリシジルエステル類；酢酸ビニル、プロピオン酸ビニルなどの飽和カルボン酸のビニルエステル類；スチレン、α−メチルスチレン、ビニルトルエンなどの芳香族不飽和単量体などが用いられる。
【００５２】
重合反応は、上記単量体をアゾビスイソブチロニトリル、ベンゾイルパーオキサイド、ジブチルパーオキサイドなどのラジカル重合触媒を用いてブチルセロソルブなどの水と相溶性のある有機溶媒中で行なわれる。樹脂の酸価が約２０未満ならば水に溶解し難く、約１００を越える場合には残存カルボキシル基の影響で塗膜性能が低下する。
【００５３】
かくして得られる水溶性アクリル樹脂は、アンモニアあるいはトリエチルアミン、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、ジメチルアミノエタノールなどのアミン類あるいは水酸化ナトリウム、水酸化カリウムなどのアルカリ金属の水酸化物などの塩基性物質を用いて中和する。この後、適当な固形分にするため水および必要に応じ水と相溶性のある有機溶剤を添加し、水希釈される。
【００５４】
他方、水分散性アクリル樹脂は、分散安定剤としてイオン性又は非イオン性、もしくはその双方の低分子又は高分子界面活性剤を用いるか又は水溶性樹脂を用いるかして、上記した水溶性アクリル樹脂の原料である重合性不飽和単量体を水性媒体中で通常公知の方法で乳化重合することによって調製される公知のものである。
【００５５】
また、アクリル樹脂の架橋剤として使用される水溶性アミノ樹脂としては、メラミン、ベンゾグアナミン、トリアジン系化合物、尿素、ジシアンジアミドなどとホルムアルデヒドとの縮合又は共縮合によって得られるものであり、炭素数１〜８のアルコール類の変性剤で変性したもの、カルボキシル基含有アミノ樹脂等も使用される。通常、アミノ基１当量に対し、ホルムアルデヒド約０．５〜約２．０当量をｐＨ調節剤（例えばアンモニア、水酸化ナトリウム、アミン類）を使用し、アルカリ性又は酸性にて公知の方法により反応させることによって調製される。本発明において好適なものはメラミンホルムアルデヒド樹脂である。
【００５６】
本発明の水性メタリック塗料（Ｂ）を構成するアクリル樹脂成分とアミノ樹脂成分との配合割合は、固形分重量を基準にして下記の割合で配合するのが適当である。
【００５７】
アクリル樹脂成分：約５０〜約９０重量部、好ましくは約６５〜約８５重量部
アミノ樹脂成分：約１０〜約５０重量部、好ましくは約１５〜約３５重量部また、成分として水分散性アクリル樹脂が用いられる場合には、同時に水溶性アクリル樹脂も併用され、次のような割合である。
【００５８】
水分散性アクリル樹脂成分：約１０〜約７０重量部、好ましくは約２０〜約５０重量部
水溶性アクリル樹脂成分：約１０〜約７０重量部、好ましくは約３０〜約５０重量部
アミノ樹脂成分：約１０〜約５０重量部、好ましくは約１５〜約３５重量部また、メタリック顔料としては、公知のものが使用でき、例えば、アルミニウム、銅、真鍮、雲母状態酸化鉄、青銅、ステンレススチールなどの燐片状メタリック粉末が挙げられ、これらの配合量は熱硬化性樹脂組成物の固形分１００重量部あたり、約１〜約５０重量部が好ましい。
【００５９】
該水性メタリック塗料（Ｂ）は、前記非メタリック塗料（Ａ）と同様にして塗装することができ、塗装時粘度はフォードカップ＃４で約１０〜約４０秒（２０℃）、塗装膜厚は加熱硬化塗膜に基づいて約５〜約２５μｍが好ましい。
【００６０】
本発明において、非メタリック塗料（Ａ）と水性メタリック塗料（Ｂ）とは、親和性のあることが好ましく、具体的には該両塗料に含まれる熱硬化性樹脂組成物の一部もしくは全部が共通もしくは類似しているか、もしくは異種であっても両者間に親和性があることが望ましい。
【００６１】
透明熱硬化性塗料（Ｃ）：
該透明熱硬化性塗料（Ｃ）（以下、「トップコート」と略称することがある）は、前記水性メタリック塗料（Ｂ）の塗面に最上層塗膜として塗装する透明な塗膜を形成する塗料である。従って、該トップコートは、光沢、耐候性、耐酸性、耐アルカリ性、耐溶剤性、耐温水性などの優れた塗膜を形成することが好ましく、具体的にはアクリル樹脂（基体樹脂）とアミノ樹脂（架橋剤）とからなる熱硬化性樹脂組成物をビヒクル成分とする有機溶剤溶液型もしくは非水分散液型の塗料が挙げられ、更に、紫外線吸収剤、着色剤などを適宜配合することもできる。
また、該トップコートのビヒクル成分は、メタリックムラ発生防止の観点から、水性メタリック塗料に含まれる熱硬化性樹脂組成物との相溶性の劣るものを使用することが好ましい。例えば、アクリル樹脂を基体樹脂とする系については、該トップコートのアクリル樹脂のソルビリティーパラメーター（ＳＰ値）と水性メタリック塗料のアクリル樹脂のＳＰ値の差が約０．１〜約１．０であることが好ましい。
【００６２】
塗装は、前記非メタリック塗料（Ａ）と同様にして塗装することができ、塗装時粘度はフォードカップ＃４で約１０〜約６０秒（２０℃）、塗装膜厚は加熱硬化塗膜に基づいて約５〜約５０μｍが好ましい。
【００６３】
本発明のメタリック仕上げ方法は、上記した非メタリック塗料（Ａ）及び水性メタリック塗料（Ｂ）を塗布し、約６０〜約１００℃で約５〜約２０分間程度プレヒートし、更に透明熱硬化性塗料（Ｃ）を塗り重ね、約１００〜約１８０℃で約１５〜約４５分間加熱して、三層の塗膜を同時に硬化させることによって行なわれる。
【００６４】
かくして仕上げたメタリック塗膜は、メタリック塗料（Ｂ）の塗装時不揮発分含有率が高いにもかかわらず、メタリック顔料が塗面に対し平行にかつ均一に配向しており（メタリックムラがない）、しかも平滑性に優れた高鮮映感のものとなる。
【００６５】
【発明の効果】
本発明のメタリック仕上げ方法では、非メタリック塗料（Ａ）が特定の架橋微粒子を含有しているため、該非メタリック塗料（Ａ）の上に塗り重ねられた水性メタリック塗料（Ｂ）のひび割れの防止に極めて有効である。
【００６６】
【実施例】
以下に、実施例及び比較例によって、本発明を更に詳細に説明する。実施例中、「部」及び「％」は別記しない限り「重量部」及び「重量％」を示す。
【００６７】
非メタリック塗料（Ａ）の製造
（１）微粒子重合体分散液（ｃ）の製造
製造例１〜６
撹拌装置、温度計、冷却管および加熱マントルを備えたえ５Ｌフラスコに表１に示す量の脱イオン水および表１に示す種類の乳化剤を表１に示す量だけ加え、撹拌しながら９０℃まで昇温した。これに表１に示す重合開始剤１０部を脱イオン水４００部に溶解した水溶液の３３％を加えた。１５分後に表１に示すモノマーの混合物および重合開始剤の滴下を開始した。モノマー混合物の滴下は４時間で、重合開始剤の滴下は４．５時間かけてそれぞれ行ない、その重合温度は９０℃に保った。重合開始剤水溶液の滴下終了後も３０分間加熱して９０℃に保った後室温に冷却し、濾布を用いて取り出し、固形分１５％の水性重合体微粒子水分散液ＭＧ１〜ＭＧ６を得た。
【００６８】
これらの水分散液ＭＧ１〜ＭＧ６をそれぞれステンレンバット上で６０℃の電気熱風式乾燥機中で乾燥させ、固形樹脂として取り出した。しかるのち、プロピレングリコールモノメチルエーテル溶剤中に分散させて固形分濃度１０％の重合体微粒子溶剤分散液ＹＧ１〜ＹＧ６をそれぞれ調製した。重合体微粒子水分散液ＭＧ１〜ＭＧ６水分散液及び重合体微粒子溶剤分散液ＹＧ１〜ＹＧ６の性質を表１に示す。
【００６９】
【表１】

【００７０】
表１において、
（注１）
１，６−ＨＤＤＡ：１，６−ヘキサンジオールジアクリレート
ＩＢＸ：イソボルニルメタクリレート
ＣＨＭＡ：シクロヘキシルメタクリレート
ＣＨＡ：シクロヘキシルアクリレート
ＴＣＤＡ：トリシクロデカントリアクリレート
ＩＢＸＡ：イソボルニルアクリレート
Ｓｔ：スチレン
ＭＭＡ：メチルメタクリレート
ｎ−ＢＡ：ｎ−ブチルアクリレート
Ｋ−１８０：ラテムルＫ−１８０、商品名、花王（株）社製、第４級アンモニウム塩系アリル基含有カチオン性反応性乳化剤、２５％水溶液
ＶＡ−０８６：商品名、和光純薬工業（株）社製、水溶性アゾアミド重合開始剤、２，２´−アゾビス［２−メチル−Ｎ−（２−ヒドロキシエチル）−プロピオンアミド］
（注２）
乳化重合時の重合安定性：乳化重合終了後、微粒子重合体を１００メッシュステンレス網で濾過したとき、ステンレス網上に残る凝塊物を、十分水洗いした後、重量を測定し、この重量の仕込みモノマーとの百分率をもって評価した。
【００７１】
◎：この百分率が０．５％以下
○：この百分率が０．５〜２％
△：この百分率が２〜５％
×：この百分率が５％以上
（注３）
水分散液中での微粒子重合体の粒子径：水分散液を脱イオン水で希釈して、コールター社ナノサイザーＮ−４で測定した
（注４）
溶剤分散液中での微粒子重合体の粒子径：溶剤分散液をアセトンで希釈して、コールター社ナノサイザーＮ−４で測定した
（２）被膜形成性バインダー樹脂（ａ）の製造
製造例７
スチレン１５部、メチルメタクリレート２０部、エチルアクリレート４６部、ヒドロキシエチルアクリレート１５部およびアクリル酸４部を重合開始剤α，α´−アゾビスイソブチロニトリルを用いてキシレン中で重合させて、樹脂固形分７０％のアクリル樹脂溶液を得た。該アクリル樹脂の数平均分子量は、約２０，０００、酸価は３１．１ｍｇＫＯＨ／ｇであった。
【００７２】
上記で得たアクリル樹脂溶液の樹脂固形分１００部に対して、ジメチルアミノエタノールを５部（中和当量１．０１）を加えて中和し、イソブチルアルコールで樹脂固形分が５０％のアクリル樹脂中和溶液（ａ−１）を得た。
【００７３】
（３）非メタリック塗料（Ａ−１）〜（Ａ−７）の製造
製造例８〜１４
表２に示す配合で各成分を混合し、イソプロピルアルコールで粘度１７．５秒（フォードカップ＃４／２０℃）に調製し、非メタリック塗料（Ａ−１）〜（Ａ−７）を得た。
【００７４】
【表２】

【００７５】
水性メタリック塗料（Ｂ）の製造
（１）水溶性アクリル樹脂水溶液（Ｗ−１）の製造
製造例１５
スチレン１５部、メチルメタクリレート２０部、エチルアクリレート２５部、ブチルアクリレート２０部、ヒドロキシエチルアクリレート１５部及びアクリル酸５部を重合開始剤α，α´−アゾビスイソブチロニトリルを用いてブチルセルソルブ中で重合させ、樹脂固形分７０％のアクリル樹脂溶液を得た。かくして得られたアクリル樹脂溶液１００部に対して４．３部のジメチルアミノエタノールを加えた後、水を加えて固形分濃度５５％の水溶性アクリル樹脂水溶液（Ｗ−１）を得た。
【００７６】
（２）水性メタリック塗料（Ｂ−１）の製造
製造例１６
５５％水溶性アクリル樹脂水溶液（Ｗ−１）（製造例１５） １００部
１００％サイメル３５０ ２５部
上記各成分を混合したものに、下記のアルミペースト分散液
アルミペースト＃４９１９（東洋アルミ（株）製品） １０部
アルミペースト＃５５−５１９（東洋アルミ（株）製品） ２０部
イソプロピルアルコール ３０部
を混合し、水で粘度１６秒（フォードカップ＃４／２０℃）に調製し、水性メタリック塗料（Ｂ−１）を得た。
【００７７】
透明熱硬化性塗料（Ｃ）の製造
（１）アクリル樹脂溶液（Ｔ−１）の製造
製造例１７
撹拌機、温度計、環流冷却器等の備わった通常のアクリル樹脂反応容器にセルソルブアセテート４０部を仕込んで加熱撹拌し、１３５℃に達してから下記の単量体混合物を３時間かかって添加した。
【００７８】
メチルメタクリレート １０部
イソブチルメタクリレート ３０部
ｎ−ブチルメタクリレート １２部
２−エチルヘキシルメタクリレート ２０部
２−ヒドロキシエチルメタクリレート ２５部
メタクリル酸 ３部
セロソルブアセテート ５０部
α，α´−アゾビスイソブチロニトリル ４部
上記単量体混合物を添加後、反応を１３５℃のまま続け、その後セロソルブアセテート１０部、α，α´−アゾビスイソブチロニトリル０．６部よりなる混合物を１時間３０分かかって添加した。その後２時間反応させた後、減圧下でセロソルブアセテートを留去し、樹脂固形分６５％に調製し、アクリル樹脂溶液（Ｔ−１）を製造した。アクリル樹脂溶液（Ｔ−１）の樹脂分の数平均分子量（蒸気圧浸透法で測定）は６，１００であり、アクリル樹脂溶液の粘度はＺ２（ガードナー気泡粘度、２５℃）であった。
【００７９】
（２）アクリル樹脂非水分散液（Ｎ−１）の製造
製造例１８
メラミン１２６部、ブチルホルムアルデヒド（４０％）４１２部、ｎ−ブタノール１９０部、キシレン３６部を反応容器に仕込み、加熱して留出してくる水を水分離器で分離しつつ、７時間反応させた後、系を減圧し、１００部の留出液を除去した後、炭化水素系溶剤「シェルゾール１４０」（シェル石油（株）製品）５０部、ｎ−ヘプタン５０部を加え、樹脂分６０％、ワニス粘度Ｊ（ガードナー気泡粘度、２５℃）のメラミン樹脂溶液を製造した。
【００８０】
上記メラミン樹脂溶液５８部、ｎ−ヘプタン３０部、ベンゾイルパーオキシド０．１５部を反応容器に仕込み、これを９５℃に加熱し、下記単量体混合物を３時間かかって滴下した。
【００８１】
スチレン １５部
アクリロニトリル ９部
メチルメタクリレート １３部
メチルアクリレート １５部
ｎ−ブチルメタクリレート １．８部
２−ヒドロキシエチルメタクリレート １０部
アクリル酸 １．２部
ベンゾイルパーオキシド ０．５部
ｎ−ブタノール ５部
「シェルゾール１４０」 ３０部
ｎ−ヘプタン ９部
上記単量体混合物の滴下終了後１時間たってから、ｔ−ブチルパーオクトエート０．６５部、「シェルゾール１４０」３．５部の混合物を１時間かけて滴下した。その後、そのまま９５℃に保って２時間撹拌を続けた。その後、減圧して溶剤３４部を除去し、樹脂固形分６０％、ワニス粘度Ａ（ガードナー気泡粘度、２５℃) のアクリル樹脂非水分散液（Ｎ−１）を得た。
【００８２】
（３）透明熱硬化性塗料（Ｃ−１）の製造
製造例１９

上記配合でディスパー分散により透明熱硬化性塗料を得、次いでナフテゾール＃１５０ ３５部、ブチルセロソルブ３５部、ｎ−ブタノール３０部よりなる混合溶剤で３５秒（フォードカップ＃４／２０℃）に粘度調整し、固形分濃度５３％の透明熱硬化性塗料（Ｃ−１）を得た。
【００８３】
実施例１〜５及び比較例１〜２
リン酸亜鉛化成処理を施した厚さ0.8mm のダル銅板上にポリブタジエン系電着塗料を乾燥膜厚約２０μｍになるよう電着塗装し、１７０℃で２０分間焼き付けた後、＃４００のサンドペーパーで研ぎ、石油ベンジンで拭いて脱脂した。ついで自動車用中塗りサーフェイサーを乾燥膜厚約２５μｍとなるようエアースプレー塗装し、１４０℃で３０分間焼き付けた後、＃４００のサンドペーパーで水研し、水切り乾燥した。ついで石油ベンジンで脱脂し、試験用の素材とした。次に、湿度６０〜８０％の塗装ブースで上記調整された素材の上に、上述の非メタリック塗料（Ａ−１）〜（Ａ−７）をそれぞれミニベルＧ（日本ランズバーグ社製、回転静電塗装機）を用いて乾燥膜厚が５〜１０μｍになる様塗付し、常温で２分間放置した後、水性メタリック塗料（Ｂ−１）をＲＥＡ（日本ランズバーク社製、静電エアスプレー）を用いて乾燥膜厚が１０〜１５μｍになる様塗付し、常温で３分間放置した後、８０℃で１０分間プレヒートし、更に透明熱硬化性塗料（Ｃ−１）を乾燥膜厚が３５〜４０μｍになる様ミニベルＧを用いて塗付した。そして１０分間常温で放置した後、電気熱風乾燥器で、１４０℃×３０分間加熱硬化せしめた。得られた塗膜の水性メタリック塗膜の割れ及びリコート付着性を表３に示す。表３における試験方法は次の通りである。
【００８４】
水性メタリック塗膜の割れ：得られた塗板を目視にて次の基準で評価した。
【００８５】
○：水性メタリック塗膜に割れが生じていない、
×：水性メタリック塗膜に割れが生じた。
【００８６】
リコート付着性：焼付けした試験板を１６０℃×３０分の条件でオーバーベークし、室温で放冷し、２時間後に同種の塗料を塗装し１４０℃×３０分間焼付けた後放冷し、クロスカット〜セロハンテープ剥離テストを行ない、次の基準で評価した。
【００８７】
○：全く剥離が認められない、
△：わずかに剥離が認められる、
×：著しい剥離が認められる。
【００８８】
【表３】

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metallic finishing method, and more particularly to a metallic finishing method using an aqueous metallic paint.
[0002]
[Prior art and problems]
A neutralized product of a polycarboxylic acid resin having an acid value of 5 to 100 and an amino resin are essential components, and an organic solution type or non-aqueous dispersion type thermosetting paint containing no metallic pigment is applied to the object to be coated. The viscosity of the applied paint is adjusted to 10 poise (20 ° C.) or more, a thermosetting water-based metallic paint is applied thereon, and further a transparent thermosetting paint is applied, and then the above three-layer coating film is formed. A metallic finishing method characterized by heating and curing at the same time is known from Japanese Patent Publication No. 4-25076.
[0003]
However, the method according to the publication cannot prevent cracks generated in the coating film of the thermosetting water-based metallic paint further coated on the organic solution-type or non-aqueous dispersion-type thermosetting paint containing no metallic pigment. There was a problem.
[0004]
[Problems to be solved by the invention]
The present inventors are free from the above-mentioned problems, and are free from cracks in the coating film of a thermosetting water-based metallic paint further coated on an organic solution-type or non-aqueous dispersion-type thermosetting paint containing no metallic pigment. As a result of intensive research to develop a metallic finishing method with improved resistance, thermosetting on organic solution type or non-aqueous dispersion type thermosetting paint containing specific cross-linked fine particles and no metallic pigment It has been found that applying the water-based metallic paint again is extremely effective in solving the above problems. In other words, organic solution type or non-aqueous dispersion type thermosetting paints that do not contain metallic pigments containing specific cross-linked fine particles have a finished appearance of coating film, interlayer adhesion, water resistance, solvent resistance, chemical resistance, etc. The present inventors have found that it is extremely effective in preventing cracking of a thermosetting water-based metallic paint that has been applied without adversely affecting various performances, and has completed the present invention.
[0005]
[Means for solving the problems]
Thus, according to the present invention,
An organic solution type or non-aqueous dispersion type thermosetting paint (A) containing no metallic pigment is applied to the object to be coated, and a thermosetting aqueous metallic paint (B) is applied on the applied paint (A). In the metallic finishing method, wherein the paint (A) is coated and further coated with the transparent thermosetting paint (C), and then the paint film composed of the three layers is heated and cured at the same time.
(A) a film-forming binder resin,
(B) a volatile organic liquid diluent dissolving the film-forming binder (a), and
(C) containing fine polymer particles that are not dissolved in the solution of the binder resin (a) in the diluent (b) and are stably dispersed, and the fine polymer particles (c)
(I) a polymerizable monomer having at least two radically polymerizable unsaturated groups in the molecule;
(Ii) a (meth) acrylate having a saturated cyclic group, and
(Iii) Other radically polymerizable unsaturated monomers
There is provided a metallic finishing method characterized in that it is a gelled polymer fine particle obtained by emulsion polymerization in the presence of a reactive emulsifier containing an allyl group in the molecule.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the paint used in the present invention and the method of finishing the coating with these will be described in detail.
[0007]
Thermosetting paint (A):
This paint is used to orient the metallic pigment in the aqueous metallic coating film to be formed uniformly and parallel to the coating surface without being affected by atmospheric humidity, and to finish the metallic coating surface smoothly. Thus, it is an organic solution type or non-aqueous dispersion type thermosetting paint that does not contain a flake-like metallic pigment.
[0008]
In the present invention, the film-forming binder resin (a) used in the thermosetting paint (A) is a mixture of a neutralized product of a polycarboxylic acid resin having an acid value of 5 to 100 mgKOH / g and an amino resin. .
[0009]
As the polyvalent carboxylic acid resin having an acid value of 5 to 100 mgKOH / g, various known resins can be used as long as these requirements are satisfied. Among them, typical examples include acrylic acid, methacrylic acid, and the like. At least one carboxyl group-containing polymerizable unsaturated monomer such as acid, maleic acid, itaconic acid, crotonic acid, etc., for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate A hydroxyalkyl ester having 1 to 8 carbon atoms of acrylic acid or methacrylic acid such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate Acrylic acid such as isobutyl methacrylate, t-butyl acrylate, t-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, decyl acrylate, or the like Methacrylic acid alkyl or cycloalkyl ester having 1 to 24 carbon atoms; acrylamide, methacrylamide, N-methylacrylamide, N-ethylmethacrylamide, diacetoneacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N -Functional amides or methacrylamides such as butoxymethylacrylamide; Polymerizable nitriles such as acrylonitrile; glycidyl group-containing vinyl monomers such as glycidyl acrylate, glycidyl methacrylamide, and allyl glycidyl ether; styrene, vinyl toluene, vinyl propionate, α-methylstyrene, vinyl acetate, acrylonitrile, methacrylonitrile, Vinyl monomers such as vinyl propionate, vinyl pivalate, and veova monomer (shell chemical products); α-olefins such as ethylene and propylene; diene compounds such as butadiene and isoprene; vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris (2 -Methoxyethoxy) silane, hydrolyzable alkoxysilyl group-containing monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, etc. An acrylic resin or vinyl resin obtained by copolymerization with other radically polymerizable unsaturated monomers, preferably having a number average molecular weight of about 5,000 to about 40,000; ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol , 2,2-dimethylpropanediol, glycerin, trimethylolpropane, pentaerythritol, and other monohydric alcohols or monoepoxy compounds having one glycidyl group in the molecule (for example, “ Cardura E "(trade name, manufactured by Shell Chemical Co., Ltd.) is used as an alcohol component, phthalic anhydride, isophthalic acid, terephthalic acid tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, succinic anhydride, adipic acid, Sebachi Acids, polybasic acids such as trimellitic anhydride, pyromellitic anhydride, and monobasic acids such as benzoic acid and t-butylbenzoic acid used in combination as needed, and the alcohol component and the acid component Oil-free alkyd resin obtained by condensing, or in addition to the alcohol component and the acid component, castor oil, dehydrated castor oil, tung oil, safflower oil, soybean oil, flaxseed oil, tall oil, coconut oil, and the like An oil-modified alkyd resin obtained by adding an oil component, which is one or a mixture of two or more fatty acids, to the above-mentioned acid component and alcohol component and reacting the three components, preferably having a number average molecular weight, 500 to 10,000; a graft copolymer obtained by grafting an acrylic resin or vinyl resin onto an alkyd resin, preferably a number average molecule Examples thereof include a graft copolymer obtained by reacting a vinyl monomer and / or an acrylic monomer with an alkyd resin having a copolymerizable unsaturated group in an amount of about 5,000 to about 40,000.
[0010]
The acid value of the polyvalent carboxylic acid resin needs to be in the range of 5 to 100 mgKOH / g, preferably in the range of 10 to 50 mgKOH / g, more preferably in the range of 30 to 50 mgKOH / g. Is good. When the acid value of the resin is less than 5 mgKOH / g, the thermosetting water-based metallic paint (B) to be applied next is not well-adapted, and the water-based metallic paint (B) has no effect of sucking water. Uneven flow of metallic paint (B), defects such as sagging are produced, and the metallic feeling is remarkably deteriorated. Conversely, when the acid value is more than 100 mgKOH / g, the water resistance of the coating film is deteriorated, which is not preferable.
[0011]
Moreover, said polyhydric carboxylic acid resin can be made to contain a hydroxyl group, for example by copolymerizing said hydroxyalkyl ester, and when such resin is used, coating-film hardness, water resistance, and acid resistance will improve. In this case, when the hydroxyl value of the resin is in the range of about 10 to about 200 mgKOH / g, a remarkable effect of improving the coating film performance is recognized, and in particular, the range of 25 to 70 mgKOH / g is preferable.
[0012]
Examples of basic substances that neutralize these polycarboxylic acid resins include various basic substances such as ammonia, methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, dimethylethanolamine, diethanolamine, and triethanolamine. Can be used. In general, the amount of the neutralizing agent used is preferably about 0.1 to about 2.0 equivalents, particularly preferably about 0.3 to about 1.2 equivalents, relative to the carboxyl group in the resin. When the amount of the neutralizing agent used is less than about 0.1 equivalent, the heat-curable water-based metallic paint (B) to be applied next is not well-adapted and there is no effect of sucking moisture of the water-based metallic paint (B). For this reason, irregularities such as uneven flow and sagging of the water-based metallic paint (B) are produced, and the metallic feeling is remarkably deteriorated. On the other hand, when the amount is more than about 2.0 equivalent, the coating film performance is deteriorated.
[0013]
The amino resin used in the present invention is a crosslinking agent for curing the polyvalent carboxylic acid resin, and various known crosslinking agents are used. For example, melamine, benzoguanamine, triazine compounds, urea, dicyandiamide, etc. and formaldehyde And those obtained by modification with a modifier. Of these, melamine formaldehyde resin is preferred.
[0014]
The blending ratio of the polyvalent carboxylic acid resin and the amino resin is generally about 50 to about 90 parts by weight of the polyvalent carboxylic acid resin, preferably from the viewpoint of the coating film performance, based on the solid content weight. It is used in the range of 65 to about 85 parts by weight, amino resin: about 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight.
[0015]
The diluent as component (b) used in the present invention is a volatile organic liquid diluent that dissolves the film-forming binder resin (a) but stably disperses the polymer fine particles (c), Any liquid mixture conventionally used as a solvent in the coating composition is included. Specifically, for example, aromatic hydrocarbons such as toluene and xylene; petroleum boiling fractions containing a substantial proportion of aromatics; aliphatic hydrocarbons such as hexane, heptane and octane; butyl acetate; Ester solvents such as ethylene glycol diacetate and ethylene glycol 2-ethoxyethyl acetate; ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, diethylene glycol monobutyl ether and propylene glycol monomethyl ether; methanol, ethanol, n-propanol, Examples thereof include alcohol solvents such as isopropanol, n-butanol, isobutanol, t-butanol and hexanol. Of these, ether solvents are preferred.
[0016]
The polymer fine particle as the component (c) used in the present invention is
(I) a polymerizable monomer having at least two radically polymerizable unsaturated groups in the molecule;
(Ii) a (meth) acrylate having a saturated cyclic group, and
(Iii) Other radically polymerizable unsaturated monomers
Is a gelled polymer fine particle obtained by emulsion polymerization in the presence of a reactive emulsifier containing an allyl group in the molecule.
[0017]
The monomer (i) includes a polymerizable unsaturated monocarboxylic acid ester of a polyhydric alcohol, a polymerizable unsaturated alcohol ester of a polybasic acid, an aromatic compound substituted with two or more vinyl groups, and the like. Specific examples thereof include ethylene glycol diacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylol Methylolpropane trimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol acrylate, pentaerythritol diacrylate, Taerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerol dimethacrylate, glycerol diacrylate, glycerol allyloxy dimethacrylate, 1,1,1-trishydroxymethylethanedi Acrylate, 1,1,1-trishydroxymethylethane triacrylate, 1,1,1-trishydroxymethylethane trimethacrylate, 1,1,1-trishydroxymethylpropane diacrylate, 1,1,1-trishydroxymethyl Propane triacrylate, 1,1,1-trishydroxymethylpropane dimethacrylate, 1,1,1-trishi B carboxymethyl trimethacrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate and divinyl benzene. These monomers (i) may be used alone or in combination of two or more.
[0018]
The (meth) acrylate having a saturated cyclic group (ii) plays an extremely important role in the polymer fine particle as the component (c). That is, when the polymer fine particle (c) contains a saturated cyclic group, the coating film of the thermosetting water-based metallic paint further coated on the paint (A) is not cracked. There is an effect. Examples of the (meth) acrylate having a saturated cyclic group include cyclohexyl acrylate, cyclohexyl methacrylate, tricyclodecane triacrylate, isobornyl acrylate, isobornyl methacrylate, and the like. , Isobornyl acrylate, isobornyl methacrylate and the like. These monomers (ii) may be used alone or in combination of two or more.
[0019]
The other radical polymerizable unsaturated monomer (iii) is the remaining component constituting the polymer fine particles (c), and specific examples thereof include carboxyl group-containing polymerization exemplified in the film-forming binder resin (a). Unsaturated monomer, hydroxyalkyl ester having 1 to 8 carbon atoms of acrylic acid or methacrylic acid, alkyl or cycloalkyl ester having 1 to 24 carbon atoms of acrylic acid or methacrylic acid, functional acrylic Alternatively, methacrylamide, polymerizable nitrile, glycidyl group-containing vinyl monomer, vinyl monomer, diene compound, hydrolyzable alkoxysilyl group-containing monomer, and the like can be given. These monomers (iii) may be used alone or in combination of two or more according to desired properties.
[0020]
The mixing ratio of the monomers (i) to (iii) constituting the polymer fine particles (c) in the present invention is not strictly limited.
Monomer (i): 1 to 99% by weight, preferably 3 to 30% by weight, more preferably 5 to 20% by weight
Monomer (ii): 1 to 99% by weight, preferably 3 to 50% by weight, more preferably 10 to 30% by weight
Monomer (iii): 0 to 98% by weight, preferably 20 to 94% by weight, more preferably 50 to 85% by weight
Can be within the range.
[0021]
Examples of the reactive emulsifier containing an allyl group in the molecule used for the emulsion polymerization of the monomers (i) to (iii) include those belonging to the following groups.
[0022]
I)Allyl group-containing anionic reactive emulsifier
The following general formula (1) or (2)
[0023]
[Chemical 1]

[0024]
Where R₁Represents hydrogen or a methyl group, R₂Represents an organic group including a hydrocarbon group or a hydrocarbon having a substituent or an oxyalkylene group, A represents an alkylene group having 2 to 4 carbon atoms or a substituted alkylene group, and n represents 0 or a positive number. M represents an alkali or alkaline earth metal, ammonium, an organic amine base, or an organic quaternary ammonium base, and m represents the valence or ionic valence of M.
Or the following general formula (3) or (4)
[0025]
[Chemical 2]

[0026]
Where R₁Represents a hydrocarbon group, phenyl group, amino group or carboxylic acid residue which may have a substituent, R₂Represents a hydrogen atom or a methyl group, A represents an alkylene group having 2 to 4 carbon atoms, n represents a positive number of 0 to 100, M represents a monovalent or divalent cation, and m represents M Represents the ionic value of
Or a sulfosuccinic acid diester salt represented by the following general formula (5)
[0027]
[Chemical Formula 3]

[0028]
Where R₁Represents an alkyl group having 4 to 18 carbon atoms, an alkenyl group, or an aralkyl group;₂Represents hydrogen or an alkyl, alkenyl, or aralkyl group having 4 to 18 carbon atoms, A represents an alkylene group or substituted alkylene group having 2 to 4 carbon atoms, n is an integer of 2 to 200, and M is Represents an alkali metal atom, NH, an alkanolamine residue,
And the like. These are known per se (for example, see JP-B-49-46291, JP-A-58-203960, JP-A-62-221431, JP-A-63-23725, etc.). "ELEMINOL JS-2" (trade name, manufactured by Sanyo Chemical Industries), "Latemuru S" series (trade name, manufactured by Kao Corporation), "AQUALON HS" series (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Are commercially available.
[0029]
II)Allyl group-containing cationic reactive emulsifier
The following general formula (6)
[0030]
[Formula 4]

[0031]
Where R₁Represents an optionally substituted hydrocarbon group having 8 to 22 carbon atoms, R₂And R_ThreeRepresents an alkyl group having 1 to 3 carbon atoms, and R_FourRepresents a hydrogen atom or a methyl group, and X^-Represents a monovalent anion,
And a reactive emulsifier having a quaternary ammonium salt represented by the formula: This is known per se (see Japanese Patent Application Laid-Open No. 60-78947), and is commercially available, for example, as “Latemuru K-180” (trade name, manufactured by Kao Corporation).
[0032]
III)Allyl group-containing nonionic reactive emulsifier
The following general formula (7) is typical.
[0033]
[Chemical formula 5]

[0034]
Where R₁Represents an alkyl group having 4 to 18 carbon atoms, an alkenyl group or an aralkyl group;₂Represents hydrogen or an alkyl group having 4 to 18 carbon atoms, an alkenyl group or an aralkyl group, A represents an alkylene group having 2 to 4 carbon atoms or a substituted alkylene group, and n is an integer of 2 to 200.
The compound shown by these is mentioned. This is known per se (see Japanese Patent Application Laid-Open No. Sho 62-100502) and is commercially available, for example, as “H-3355N” (trade name, manufactured by Daiichi Kogyo Seiyaku).
[0035]
In the emulsion polymerization, any anionic, cationic or nonionic reactive emulsifier may be exemplified as the representative example as long as it is a reactive emulsifier containing an acrylic group which is a relatively low reactive group. The reactive emulsifier that is gradually taken into the polymer during polymerization is suitable, and a cationic reactive emulsifier is preferred in the present invention.
[0036]
A nonionic reactive emulsifier can be used by mixing with an anionic reactive emulsifier or a cationic reactive emulsifier at an arbitrary ratio, and the mixing ratio is appropriately selected according to desired characteristics.
[0037]
The reactive emulsifier can be used alone or when used as a mixture of a cationic reactive emulsifier and a nonionic reactive emulsifier or as a mixture of an anionic reactive emulsifier and a nonionic reactive emulsifier. Is generally 0.1 to 30 parts by weight, preferably 0.5 to 5 parts by weight based on 100 parts by weight in total of the monomers (i) to (iii) usually constituting the polymer fine particles (c). It is appropriate to be within the range.
[0038]
As a polymerization initiator used for the emulsion polymerization, the following general formula (8)
[0039]
[Chemical 6]

[0040]
In the formula, X represents a linear or branched alkylene group having 2 to 12 carbon atoms,
Or the following general formula (9)
[0041]
[Chemical 7]

[0042]
Where X¹, X²And X^ThreeIs at least one hydroxyl group and the rest is hydrogen,
A water-soluble azoamide compound represented by the formula is particularly suitable. These are known per se (see Japanese Patent Application Laid-Open Nos. 61-218618 and 61-63643), and are commercially available, for example, as the VA series (trade name, manufactured by Wako Pure Chemical Industries, Ltd.). The required amount of polymerization initiator is apparent in the art. In general, the optimum necessary amount is in the range of 0.1 to 1.5 parts by weight with respect to 100 parts by weight in total of the monomers (i) to (iii) forming the fine particle polymer (c).
[0043]
The copolymerization of the monomers (i) to (iii) can be carried out by an emulsion polymerization method which is a method known per se for producing an acrylic copolymer. In the presence of a reactive emulsifier containing an allyl group and a water-soluble azoamide compound polymerization initiator in an aqueous medium, the monomer mixture is usually about 50 to 100 ° C., preferably about 1 to about 1 at a reaction temperature of 80 to 95 ° C. This can be done by continuing the reaction for 20 hours.
[0044]
The aqueous dispersion of polymer fine particles (c) obtained by emulsion polymerization usually has a resin solid content of about 10 to 40% by weight based on the total weight. The particle size of the fine particle polymer (c) in the aqueous dispersion is generally 500 nm or less, preferably in the range of 50 to 100 nm. The particle size can be adjusted by adjusting the type and amount of the reactive emulsifier having an allyl group in the molecule, and the fine particle polymer (c) having a particle size in a desired range can be easily obtained. .
[0045]
The blending ratio of the diluent (b) to the binder resin (a) is such that the binder resin (a) can be uniformly dissolved, and the polymer fine particles (c) are in the diluent (b) solution of the binder resin (a). Although it is not particularly limited as long as it is a quantitative ratio that can be stably dispersed in the diluent, the diluent (b) is usually 100% by weight of the binder resin (a) from the viewpoints of ease of handling and storage stability. It is desirable to use within the range of 200 to 600 parts by weight with respect to parts. The blending ratio of the polymer fine particles (c) to the binder resin (a) is generally 1 to 50 parts by weight of polymer fine particles (c), preferably 5 to 100 parts by weight per 100 parts by weight of the binder resin (a). It is desirable to use within a range of 40 parts by weight, more preferably 5 to 30 parts by weight.
[0046]
In the present invention, the polymer fine particles (c) are usually added and blended in a uniform system containing the binder resin (a) and the diluent (b). At that time, the polymer fine particles (c) are preferably blended after being converted into a form dispersed in an organic solvent. The conversion of the polymer fine particles (c) from the aqueous dispersion to the organic solvent dispersion is carried out by evaporating water from the aqueous dispersion of the polymer fine particles (c) by a spray drying method or simple drying, and then the resin solid content. Can be taken out and then redispersed in an organic solvent.
[0047]
In the present invention, the non-metallic paint (A) can be directly applied to an object to be coated, but a primer such as an electrodeposition paint (anionic type or cationic type) and a thermosetting intermediate coating are applied. It is preferable to apply after the coating film is cured. As the coating machine, it is preferable to use an atomizing type coating machine, for example, an air spray coating machine, an airless spray coating machine, an air atomizing type or a rotary electrostatic coating machine, etc. Ford cup # 4 is preferably adjusted to about 15 to about 60 seconds, particularly 15 to 35 seconds (20 ° C.), and the coating film thickness is about 2 to about 20 μm, particularly about 5 based on the heat-cured film thickness. ˜about 15 μm is suitable.
[0048]
The viscosity adjustment of the non-metallic paint (A) applied can be easily performed by appropriately adjusting the non-volatile concentration, solvent composition, viscosity, etc. of the paint at the time of application, and the application viscosity immediately after application is low. In some cases, it can be adjusted by leaving the solution at room temperature or preheating it to volatilize the solvent. In order to shorten the coating interval between the non-metallic paint (A) and the water-based metallic paint (B) described below as much as possible, the non-metallic paint (A) is coated so that the coating viscosity immediately after coating is increased. (A) is blending a viscosity modifier, and various known viscosity modifiers can be used. Specific examples include “Benton 27” (manufactured by NL Chemical Co., thixotropic property imparting agent), “Erosil # 200” (manufactured by Nippon Aerosil Co., Ltd., silica-based thixotropic property imparting agent), and the like.
[0049]
Thermosetting water-based metallic paint (B):
The water-based metallic paint (B) is an organic solution type or non-water-dispersed thermosetting paint (A) that does not contain the metallic pigment. Or a water-dispersible thermosetting acrylic resin and a metallic pigment as main components, and a coloring pigment, an extender pigment, a coating surface adjusting agent, a viscosity adjusting agent and the like are blended as necessary.
[0050]
As the water-soluble or water-dispersed thermosetting acrylic resin that is a constituent of the water-based metallic paint (B), all conventionally known ones are included. Representative examples thereof include, for example, a water-soluble acrylic resin selected from α, β-monoethylenically unsaturated carboxylic acid, its hydroxyalkyl ester and other α, β-monoethylenically unsaturated monomers. Alternatively, an acrylic resin having an acid value of about 20 to about 100 and a hydroxyl value of about 20 to about 200 obtained by polymerizing two or more kinds of monomers can be mentioned.
[0051]
The polymerizable unsaturated monomer which is a raw material of the water-soluble acrylic resin described above includes α, β-monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, and (meth) acrylic acid 2 -Hydroxyethyl, hydroxyalkyl esters of α, β-monoethylenically unsaturated carboxylic acid such as 2-hydroxypropyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic Alkyl esters of α, β-monoethylenically unsaturated carboxylic acids such as n-butyl acid, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and decyl (meth) acrylate Class: (meth) acrylamide, N-methylol (meth) acrylamide, diacetone acrylamide, etc. (Meth) acrylamide derivatives; glycidyl esters of α, β-monoethylenically unsaturated carboxylic acids such as glycidyl (meth) acrylate; vinyl esters of saturated carboxylic acids such as vinyl acetate and vinyl propionate; styrene, α- Aromatic unsaturated monomers such as methylstyrene and vinyltoluene are used.
[0052]
The polymerization reaction is carried out in an organic solvent compatible with water, such as butyl cellosolve, using a radical polymerization catalyst such as azobisisobutyronitrile, benzoyl peroxide, or dibutyl peroxide. If the acid value of the resin is less than about 20, it is difficult to dissolve in water, and if it exceeds about 100, the performance of the coating film deteriorates due to the influence of residual carboxyl groups.
[0053]
The water-soluble acrylic resin thus obtained is basic such as ammonia or amines such as triethylamine, monoethanolamine, diethanolamine, triethanolamine and dimethylaminoethanol, or alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Neutralize with material. Thereafter, in order to obtain an appropriate solid content, water and, if necessary, an organic solvent compatible with water are added and diluted with water.
[0054]
On the other hand, the water-dispersible acrylic resin uses the above-mentioned water-soluble acrylic as a dispersion stabilizer by using ionic or nonionic or both low-molecular or high-molecular surfactants or using a water-soluble resin. It is a well-known thing prepared by emulsion-polymerizing the polymerizable unsaturated monomer which is a raw material of resin in an aqueous medium by a normally well-known method.
[0055]
The water-soluble amino resin used as a crosslinking agent for acrylic resins is obtained by condensation or cocondensation of melamine, benzoguanamine, triazine compounds, urea, dicyandiamide, and the like with formaldehyde, and has 1 to 8 carbon atoms. Those modified with alcohol modifiers, carboxyl group-containing amino resins, and the like are also used. Usually, about 0.5 to about 2.0 equivalents of formaldehyde are reacted with 1 equivalent of amino group by a known method using a pH adjuster (for example, ammonia, sodium hydroxide, amines) in an alkaline or acidic manner. It is prepared by. Preferred in the present invention is a melamine formaldehyde resin.
[0056]
The blending ratio of the acrylic resin component and the amino resin component constituting the aqueous metallic paint (B) of the present invention is suitably blended at the following ratio based on the solid content weight.
[0057]
Acrylic resin component: about 50 to about 90 parts by weight, preferably about 65 to about 85 parts by weight
Amino resin component: about 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight In addition, when a water-dispersible acrylic resin is used as a component, a water-soluble acrylic resin is also used at the same time. It is a ratio.
[0058]
Water dispersible acrylic resin component: about 10 to about 70 parts by weight, preferably about 20 to about 50 parts by weight
Water-soluble acrylic resin component: about 10 to about 70 parts by weight, preferably about 30 to about 50 parts by weight
Amino resin component: about 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight Further, as the metallic pigment, known ones can be used, for example, aluminum, copper, brass, mica state iron oxide, bronze, Examples thereof include flake-like metallic powders such as stainless steel, and the amount thereof is preferably about 1 to about 50 parts by weight per 100 parts by weight of the solid content of the thermosetting resin composition.
[0059]
The water-based metallic paint (B) can be applied in the same manner as the non-metallic paint (A), and the viscosity at the time of painting is about 10 to about 40 seconds (20 ° C.) with Ford Cup # 4. About 5 to about 25 μm is preferred based on the heat-cured coating.
[0060]
In the present invention, the non-metallic paint (A) and the water-based metallic paint (B) are preferably compatible with each other, specifically, part or all of the thermosetting resin composition contained in the both paints. It is desirable that there is an affinity between the two even if they are common, similar or different.
[0061]
Transparent thermosetting paint (C):
The transparent thermosetting paint (C) (hereinafter sometimes abbreviated as “top coat”) forms a transparent paint film to be applied as the uppermost paint film on the paint surface of the water-based metallic paint (B). It is a paint. Accordingly, it is preferable that the top coat forms an excellent coating film such as gloss, weather resistance, acid resistance, alkali resistance, solvent resistance, hot water resistance, and the like. Specifically, acrylic resin (base resin) and amino Examples include organic solvent solution-type or non-aqueous dispersion-type paints that use a thermosetting resin composition comprising a resin (crosslinking agent) as a vehicle component, and may contain UV absorbers, colorants, and the like as appropriate. it can.
Moreover, it is preferable to use the vehicle component of the top coat that is incompatible with the thermosetting resin composition contained in the aqueous metallic paint from the viewpoint of preventing the occurrence of metallic unevenness. For example, for a system using an acrylic resin as a base resin, the difference between the solubility parameter (SP value) of the acrylic resin of the top coat and the SP value of the acrylic resin of the aqueous metallic paint is about 0.1 to about 1.0. Preferably there is.
[0062]
The paint can be applied in the same manner as the non-metallic paint (A), the viscosity at the time of painting is about 10 to about 60 seconds (20 ° C.) with Ford Cup # 4, and the coating film thickness is based on the heat-cured coating film. About 5 to about 50 μm is preferable.
[0063]
In the metallic finishing method of the present invention, the non-metallic paint (A) and the aqueous metallic paint (B) described above are applied, preheated at about 60 to about 100 ° C. for about 5 to about 20 minutes, and further, a transparent thermosetting paint. (C) is applied repeatedly and heated at about 100 to about 180 ° C. for about 15 to about 45 minutes to simultaneously cure the three-layer coating film.
[0064]
The metallic coating thus finished has a metallic pigment oriented uniformly and parallel to the coating surface (there is no metallic unevenness) despite the high non-volatile content when the metallic paint (B) is applied. Moreover, it has a high image quality with excellent smoothness.
[0065]
【The invention's effect】
In the metallic finishing method of the present invention, since the non-metallic paint (A) contains specific crosslinked fine particles, the water-based metallic paint (B) coated on the non-metallic paint (A) is prevented from cracking. It is extremely effective.
[0066]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight” unless otherwise specified.
[0067]
Production of non-metallic paint (A)
(1) Production of fine particle polymer dispersion (c)
Production Examples 1-6
To a 5 L flask equipped with a stirrer, thermometer, cooling pipe and heating mantle, add the amount of deionized water shown in Table 1 and the type of emulsifier shown in Table 1 in the amounts shown in Table 1, and stir up to 90 ° C. The temperature rose. To this, 33% of an aqueous solution obtained by dissolving 10 parts of the polymerization initiator shown in Table 1 in 400 parts of deionized water was added. After 15 minutes, dropping of the monomer mixture and polymerization initiator shown in Table 1 was started. The monomer mixture was dropped for 4 hours and the polymerization initiator was dropped for 4.5 hours, and the polymerization temperature was maintained at 90 ° C. Even after completion of the dropwise addition of the polymerization initiator aqueous solution, the mixture was heated for 30 minutes and kept at 90 ° C., cooled to room temperature, and taken out using a filter cloth to obtain aqueous polymer fine particle aqueous dispersions MG1 to MG6 having a solid content of 15%. .
[0068]
These aqueous dispersions MG1 to MG6 were each dried on a stainless steel vat in an electric hot air dryer at 60 ° C. and taken out as a solid resin. Thereafter, polymer fine particle solvent dispersions YG1 to YG6 having a solid content concentration of 10% were prepared by dispersing in a propylene glycol monomethyl ether solvent. Table 1 shows properties of the polymer fine particle aqueous dispersions MG1 to MG6 and the polymer fine particle solvent dispersions YG1 to YG6.
[0069]
[Table 1]

[0070]
In Table 1,
(Note 1)
1,6-HDDA: 1,6-hexanediol diacrylate
IBX: Isobornyl methacrylate
CHMA: cyclohexyl methacrylate
CHA: cyclohexyl acrylate
TCDA: Tricyclodecane triacrylate
IBXA: Isobornyl acrylate
St: Styrene
MMA: Methyl methacrylate
n-BA: n-butyl acrylate
K-180: Latemul K-180, trade name, manufactured by Kao Corporation, quaternary ammonium salt-based allyl group-containing cationic reactive emulsifier, 25% aqueous solution
VA-086: trade name, manufactured by Wako Pure Chemical Industries, Ltd., water-soluble azoamide polymerization initiator, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide]
(Note 2)
Polymerization stability at the time of emulsion polymerization: When the fine particle polymer is filtered through a 100 mesh stainless steel mesh after the emulsion polymerization is completed, the coagulum remaining on the stainless steel mesh is thoroughly washed with water, and then the weight is measured. Evaluation was made as a percentage of the monomer.
[0071]
◎: This percentage is 0.5% or less
○: This percentage is 0.5-2%
Δ: This percentage is 2 to 5%
×: This percentage is 5% or more
(Note 3)
Particle size of fine particle polymer in aqueous dispersion: diluted with deionized water and measured with Coulter Nanosizer N-4
(Note 4)
Particle size of fine particle polymer in solvent dispersion: Solvent dispersion was diluted with acetone and measured with Coulter Nanosizer N-4
(2) Production of film-forming binder resin (a)
Production Example 7
15 parts of styrene, 20 parts of methyl methacrylate, 46 parts of ethyl acrylate, 15 parts of hydroxyethyl acrylate and 4 parts of acrylic acid are polymerized in xylene using a polymerization initiator α, α′-azobisisobutyronitrile An acrylic resin solution having a solid content of 70% was obtained. The acrylic resin had a number average molecular weight of about 20,000 and an acid value of 31.1 mgKOH / g.
[0072]
100 parts of the resin solid content of the acrylic resin solution obtained above are neutralized by adding 5 parts of dimethylaminoethanol (neutralization equivalent of 1.01), and the acrylic resin has a resin solid content of 50% with isobutyl alcohol. A neutralized solution (a-1) was obtained.
[0073]
(3) Production of non-metallic paints (A-1) to (A-7)
Production Examples 8-14
Each component was mixed with the composition shown in Table 2, and prepared with isopropyl alcohol to a viscosity of 17.5 seconds (Ford Cup # 4/20 ° C.) to obtain non-metallic paints (A-1) to (A-7). .
[0074]
[Table 2]

[0075]
Manufacture of water-based metallic paint (B)
(1) Production of water-soluble acrylic resin aqueous solution (W-1)
Production Example 15
15 parts of styrene, 20 parts of methyl methacrylate, 25 parts of ethyl acrylate, 20 parts of butyl acrylate, 15 parts of hydroxyethyl acrylate and 5 parts of acrylic acid are used as polymerization initiator α, α'-azobisisobutyronitrile to butyl cellosolve The resultant was polymerized in an acrylic resin solution having a resin solid content of 70%. After adding 4.3 parts of dimethylaminoethanol to 100 parts of the acrylic resin solution thus obtained, water was added to obtain a water-soluble acrylic resin aqueous solution (W-1) having a solid content concentration of 55%.
[0076]
(2) Production of water-based metallic paint (B-1)
Production Example 16
55 parts water-soluble acrylic resin aqueous solution (W-1) (Production Example 15) 100 parts
100% Cymel 350 25 parts
The following aluminum paste dispersion is mixed with the above components.
Aluminum paste # 4919 (product of Toyo Aluminum Co., Ltd.) 10 parts
Aluminum paste # 55-519 (product of Toyo Aluminum Co., Ltd.) 20 parts
30 parts isopropyl alcohol
Were mixed with water and the viscosity was adjusted to 16 seconds (Ford Cup # 4/20 ° C.) to obtain an aqueous metallic paint (B-1).
[0077]
Manufacture of transparent thermosetting paint (C)
(1) Production of acrylic resin solution (T-1)
Production Example 17
Charge 40 parts of Cellosolve Acetate into an ordinary acrylic resin reaction vessel equipped with a stirrer, thermometer, reflux condenser, etc., and heat and stir. After reaching 135 ° C., add the following monomer mixture over 3 hours did.
[0078]
10 parts of methyl methacrylate
30 parts isobutyl methacrylate
12 parts of n-butyl methacrylate
20 parts of 2-ethylhexyl methacrylate
2-hydroxyethyl methacrylate 25 parts
Methacrylic acid 3 parts
50 parts of cellosolve acetate
α, α'-Azobisisobutyronitrile 4 parts
After addition of the monomer mixture, the reaction was continued at 135 ° C., after which a mixture of 10 parts of cellosolve acetate and 0.6 part of α, α′-azobisisobutyronitrile was added over 1 hour 30 minutes. . Then, after reacting for 2 hours, cellosolve acetate was distilled off under reduced pressure to prepare a resin solid content of 65% to produce an acrylic resin solution (T-1). The number average molecular weight (measured by vapor pressure infiltration method) of the resin content of the acrylic resin solution (T-1) was 6,100, and the viscosity of the acrylic resin solution was Z2 (Gardner bubble viscosity, 25 ° C.).
[0079]
(2) Production of acrylic resin non-aqueous dispersion (N-1)
Production Example 18
126 parts of melamine, 412 parts of butylformaldehyde (40%), 190 parts of n-butanol and 36 parts of xylene were charged in a reaction vessel, and the reaction was carried out for 7 hours while heating and separating the distilled water with a water separator. Thereafter, the system was depressurized and 100 parts of distillate was removed. Then, 50 parts of hydrocarbon solvent “Shellsol 140” (Shell Petroleum Co., Ltd.) and 50 parts of n-heptane were added, and the resin content was 60%. A melamine resin solution having a varnish viscosity J (Gardner cell viscosity, 25 ° C.) was produced.
[0080]
The reaction vessel was charged with 58 parts of the melamine resin solution, 30 parts of n-heptane and 0.15 part of benzoyl peroxide, heated to 95 ° C., and the following monomer mixture was added dropwise over 3 hours.
[0081]
15 parts of styrene
9 parts acrylonitrile
13 parts of methyl methacrylate
15 parts of methyl acrylate
n-Butyl methacrylate 1.8 parts
2-hydroxyethyl methacrylate 10 parts
Acrylic acid 1.2 parts
Benzoyl peroxide 0.5 parts
n-Butanol 5 parts
"Shellsol 140" 30 parts
9 parts of n-heptane
One hour after the completion of the dropwise addition of the monomer mixture, a mixture of 0.65 part of t-butyl peroctoate and 3.5 parts of “Shellsol 140” was added dropwise over 1 hour. Thereafter, the mixture was kept at 95 ° C. and stirred for 2 hours. Thereafter, 34 parts of the solvent was removed under reduced pressure to obtain an acrylic resin non-aqueous dispersion (N-1) having a resin solid content of 60% and a varnish viscosity A (Gardner cell viscosity, 25 ° C.).
[0082]
(3) Production of transparent thermosetting paint (C-1)
Production Example 19

With the above composition, a transparent thermosetting paint is obtained by dispersing the dispersion, and then the viscosity is adjusted to 35 seconds (Ford Cup # 4/20 ° C.) with a mixed solvent consisting of 35 parts of Naphthezol # 150, 35 parts of butyl cellosolve and 30 parts of n-butanol. A transparent thermosetting paint (C-1) having a solid content concentration of 53% was obtained.
[0083]
Examples 1-5 and Comparative Examples 1-2
A polybutadiene electrodeposition coating was applied on a 0.8 mm thick dull copper plate that had been subjected to zinc phosphate conversion treatment, and was dried to a dry film thickness of about 20 μm. After baking at 170 ° C. for 20 minutes, # 400 sandpaper And then degreased by wiping with petroleum benzine. Next, an automotive intermediate coating surfacer was air spray-coated to a dry film thickness of about 25 μm, baked at 140 ° C. for 30 minutes, then water-polished with # 400 sandpaper, and then drained and dried. Subsequently, it was degreased with petroleum benzine and used as a test material. Next, the above-described non-metallic paints (A-1) to (A-7) are respectively applied to the above-described non-metallic paints (A-1) to (A-7) in a painting booth having a humidity of 60 to 80%. Using an electrocoating machine) so that the dry film thickness is 5 to 10 μm, and after standing at room temperature for 2 minutes, water-based metallic paint (B-1) is applied to REA (Nippon Landsberg, electrostatic air spray). Is applied so that the dry film thickness becomes 10 to 15 μm, left at room temperature for 3 minutes, preheated at 80 ° C. for 10 minutes, and further the transparent thermosetting paint (C-1) is dried to 35 It applied using the minibell G so that it might be set to -40 micrometers. Then, after leaving at room temperature for 10 minutes, it was cured by heating with an electric hot air dryer at 140 ° C. for 30 minutes. Table 3 shows the cracks and recoat adhesion of the aqueous metallic coating film of the obtained coating film. The test methods in Table 3 are as follows.
[0084]
Cracking of aqueous metallic coating:The obtained coated plate was visually evaluated according to the following criteria.
[0085]
○: No cracking occurred in the aqueous metallic coating film,
X: Cracking occurred in the aqueous metallic coating film.
[0086]
Recoat adhesion:The baked test plate is overbaked at 160 ° C for 30 minutes, allowed to cool at room temperature, and after 2 hours, the same type of paint is applied and baked at 140 ° C for 30 minutes, then allowed to cool, and the cross-cut to cellophane tape is removed The test was conducted and evaluated according to the following criteria.
[0087]
○: No separation is observed,
Δ: Slight peeling is observed,
X: Remarkable peeling is recognized.
[0088]
[Table 3]

Claims (5)

An organic solution type or non-aqueous dispersion type thermosetting paint (A) containing no metallic pigment is applied to the object to be coated, and a thermosetting aqueous metallic paint (B) is applied on the applied paint (A). In the metallic finishing method, wherein the paint (A) is coated and further coated with the transparent thermosetting paint (C), and then the paint film composed of the three layers is heated and cured at the same time.
(A) a film-forming binder resin,
(B) a volatile organic liquid diluent in which the film-forming binder (a) is dissolved, and (c) a binder resin (a) in the diluent (b) that is stably dissolved without being dissolved in the solution. Polymer fine particles, and the polymer fine particles (c)
(I) a polymerizable monomer having at least two radically polymerizable unsaturated groups in the molecule;
Gelation weight obtained by emulsion polymerization of (ii) (meth) acrylate having a saturated cyclic group, and (iii) other radical polymerizable unsaturated monomer in the presence of a reactive emulsifier containing an allyl group in the molecule. A metallic finishing method characterized by being a coalesced fine particle. The method according to claim 1, wherein the film-forming binder resin (a) is a mixture of a neutralized product of a polyvalent carboxylic acid resin having an acid value of 5 to 100 mgKOH / g and an amino resin. The method according to claim 1, wherein 0.1 to 30 parts by weight of polymer fine particles (c) are blended with 100 parts by weight of the film-forming binder resin (a). 2. The (meth) acrylate (ii) having a saturated cyclic group is one or more selected from cyclohexyl acrylate, cyclohexyl methacrylate, tricyclodecane triacrylate, isobornyl acrylate, and isobornyl methacrylate. the method of. The method according to claim 1, wherein the (meth) acrylate (ii) having a saturated cyclic group is isobornyl acrylate and / or isobornyl methacrylate.