JP4112866B2 - Non-oriented electrical steel sheet with excellent coating performance - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は無方向性電磁鋼板の製造において、高速ラインにおける塗れ性が極めて優れると共に、焼付け後の絶縁被膜の性状として、打ち抜き性、溶接性、密着性、占積率、外観等被膜特性の優れる有機−無機系絶縁被膜剤とそれを用いた絶縁被膜の形成方法に関する。
【０００２】
【従来の技術】
周知のごとく、無方向性電磁鋼板をモーターやトランスの鉄心に使用する場合には、所定の形状に打ち抜いた後、所定枚数積み重ね、溶接、かしめ或いは接着等により鉄心とされる。また、この際、必要に応じて歪焼鈍が施される。通常、この無方向性電磁鋼板表面には絶縁被膜処理が施される。
【０００３】
この絶縁被膜としては、絶縁性の他に打ち抜き性、溶接性、耐食性、密着性、占積率等が重要で、さらにコア打ち抜き後に歪み取り焼鈍工程を必要とする場合には、歪み取り焼鈍後の密着性、絶縁性、耐食性等も重要となる。
【０００４】
従来、絶縁被膜剤としては、無機系、有機系、有機−無機混合系被膜が使用条件や目的に応じて適用されてきた。一般に、無機系被膜は耐熱性や溶接性は優れるが打ち抜き性が劣る。一方、有機被膜の場合には打ち抜き性、密着性は優れるが耐熱性が悪く、溶接性が劣る欠点がある。
【０００５】
このような両者の欠点を解決すべく、中間的な特性が得られる有機−無機系被膜が用いられるようになった。有機−無機系被膜としては、特開昭５２−３３８４６号公報には、燐酸系、クロム酸系の１種又は２種以上と有機樹脂の混合被膜を形成するに際し、処理液中に有機樹脂粒子を添加して表面粗さを２〜１０μＨmaxとする打ち抜き性と溶接性の優れた絶縁被膜形成法が提案されている。
【０００６】
特開平３−２４０９７０号公報には、歪取り焼鈍後の被膜特性が優れた無方向性電磁鋼板の製造法として、ＣｒＯ3１００質量部、Ａｌ，Ｍｇ，Ｃａ，Ｚｎから選ばれる酸化物の１種又は２種以上２０〜４０質量部、粒子径０．２〜０．５μｍに調整したアクリル、スチレン、酢ビ及び又はこれらの共重合体からなる樹脂の１種又は２種以上の微粒子エマルジョン溶液１０〜６０質量部、粒子径を１〜５０μｍに調整したメチルメタアクリレート、ポリアクリルニトリル、ポリスチレン、セルローズ、シリコン、メラミン、フェノール、ポバール樹脂及び／又はこれらの共重合体、架橋体の１種又は２種以上を２〜３０質量部からなるものが開示され、これにより、打ち抜き性、溶接性が良好で且つ、歪取り後の潤滑性、絶縁性、耐蝕性が著しく改善されることが述べられている。
【０００７】
特開平４−１７６８７３号公報には、 電磁鋼板の表面にクロム酸系の１種又は２種以上とクロム酸金属塩（ＣｒＯ3に換算して）１質量部に対して、水分散性エマルジョン０．１〜５質量部、粒径が２〜５０μｍの球状有機樹脂粒子０．１〜１．０質量部を主成分とする水溶液を焼き付けて表面粗さが０．５〜１．５μｍの被膜を形成する溶接性と密着性に優れた電磁鋼板の電気絶縁被膜処理方法が提案されている。
【０００８】
これらの従来技術おいては、何れも打ち抜き性向上の目的で添加される有機樹脂の溶接性劣化を緩和するために、極めて粗い粒子状物質を添加して表面粗度の粗さを得て溶接性向上効果を得ている。このため、占積率の低下の弊害は否めず、塗れ性、液安定性、外観やコストアップをもたらす問題がある。
【０００９】
【発明が解決しようとする課題】
上述したような従来の有機−無機成分を基本とするコーティング剤やその処理方法においては、被膜成分の鋼板への塗れ性や液の安定性、外観が十分でなく、更には、近年の高速の塗布・焼付け処理ラインにおける液の塗れ性、塗布性問題から生じる打ち抜き性、溶接性や外観不良の問題は根強く更なる改善が望まれている。
【００１０】
【課題を解決するための手段】
本発明は、有機−無機成分を基本とする絶縁皮膜剤の塗れ性向上と、これによる打ち抜き性、溶接性、密着性、外観の改善をすべく考案されたものである。これにより、従来の半有機被覆の欠点を改善するための塗れ性の優れた絶縁被覆剤による表面均一性、皮膜性能の優れた無方向性電磁鋼板を提供することを目的とし、以下の構成を要旨とする。
（１）絶縁被膜が、クロム酸として１００質量部に対し、粒子径０．０４〜０．１９μｍの超微粒樹脂を含む樹脂エマルジョンを固形分として５〜５０質量部含有し、樹脂中の粒子径０．０４〜０．１９μｍの超微粒樹脂が、質量で、樹脂固形分の３０％以上の樹脂であり、クロム酸を主体とする絶縁被膜剤により処理され、絶縁被膜成分中の有機物成分を有機Ｃとして２．５〜２５．０％を含有し、膜厚０．５〜１０．０μｍの絶縁被膜を有することを特徴とする被膜性能の優れる無方向性電磁鋼板。
（２）前記樹脂中の粒子径０．０４〜０．１９μｍの超微粒樹脂の残部が、粒子径０．３５〜０．５０μｍの樹脂であることを特徴とする（１）に記載の被膜性能の優れる無方向性電磁鋼板。
（３）前記樹脂が、Ｔｇ：２０〜１００℃のアクリル、スチレン、酢酸ビニル、ポリスチレン、ポリプロピレン、ポリアミド、ポリカーボネート、メラミン、ポリウレタン、アルキド、イソシアネート、エポキシ樹脂の１種又は２種以上からなることを特徴とする（１）又は（２）に記載の被膜性能の優れる無方向性電磁鋼板。
（４）前記絶縁被膜の表面粗度Ｒａ値が０．１〜１．０μｍ、光沢度が７０以上であることを特徴とする（１）〜（３）のいずれかに記載の被膜性能の優れる無方向性電磁鋼板。
【００１１】
ただし、光沢度：Ｌ方向、光源入射角（θ）：４５度で測定。
【００１２】
【発明の実施の形態】
本発明者等は、クロム酸、硼酸を無機成分の主成分とし、樹脂エマルジョンを有機成分の主成分とする半有機系絶縁被膜における、被膜の処理工程と被膜特性上の欠点であった、高速塗布・焼付けラインにおける塗れ性不良と、それによりもたらされる打ち抜き性や溶接性不良の問題を解決すべく、液組成や焼付け条件の改善に取り組んだ。
【００１３】
即ち、従来の絶縁被膜技術では、特に１５０ｍ／分以上のような高速ラインにおいて、液の塗れ性が十分でなくなり、均一塗布が困難になり、安定した塗布膜が得られなくなるため、生産性を阻害するような低速通板や、塗れ性向上のため塗布量を増やす等を行う必要が生じる。しかしながら、このような条件変更を行っても、本質的な液塗れ性不良の性質から、塗布前の鋼板性状などの要因によっては、安定して均一な膜厚を有する製品が得られない問題が残る。
【００１４】
このような不均一被膜が形成されると、打ち抜き時にポンチに不均一な欠けをもたらす。また膜厚が増加すると、有機成分の絶対量増加により、溶接時において分解ガスによる溶接不良が生じやすい。
【００１５】
本発明者等はこのような問題を解決すべく溶液成分や処理条件の研究を行った。その結果、粒子径を超微粒とした樹脂エマルジョンを用い、クロム酸系化合物、硼酸系化合物の適正な配合条件の処理液とすることにより、超微細粒子による鋼板表面への被覆効果と吸着効果、及び超微細粒子を覆う界面活性剤による塗れ性向上効果により、処理液の塗れ性が極めて改善し、外観が優れる均一な膜厚を得ると共に、優れた打ち抜き性、溶接性、密着性、耐食性等、の被膜性能が得られる絶縁被膜剤溶液と絶縁被膜形成技術の開発に成功した。
【００１６】
以下に本発明を詳細に説明する。
【００１７】
本発明においては、先ず、その絶縁被膜剤組成に特徴があり、その絶縁被膜剤により得られる美麗で均一な被膜を有する無方向性電磁鋼板が基本となる。
【００１８】
即ち、粒子径０．０４〜０．１９μｍの超微粒樹脂を有機成分として含有し、クロム酸を主体とする被膜剤により処理され、被膜中の有機成分を有機Ｃとして２．５〜２５質量％含有し、膜厚０．５〜１０．０μｍを有する無方向性電磁鋼板に特徴がある。
【００１９】
絶縁被膜に配合される樹脂の粒子径は、まず鋼板表面への塗れ性に影響する。超微粒樹脂を用いることは高速塗布ラインにおいて１０μｍ以下、特に１μｍ以下の薄い膜厚を得るのに重要である。粒子径は小さいほど高速ラインでの塗れ性、塗膜の均一性が向上する。飛躍的な塗れ性改善効果を得るためには超微粒樹脂の粒子径が０．１９μｍ以下であることが重要である。特に、粒子径０．１４μｍ以下では飛躍的に塗れ性の向上が得られる。このような超微粒樹脂エマルジョンを主成分とする絶縁被膜剤を塗布すると、被膜欠陥がなく表面外観が均一で且つ、均一な膜厚を有する製品が得られる。
【００２０】
超微粒子樹脂の粒子径の下限は０．０４μｍとした。安定なエマルジョンとするためには、比表面積に応じた界面活性剤の使用が必要であるが、粒子径が０．０４μｍ未満と小さ過ぎると、界面活性剤の必要量が増し、塗布作業工程での泡立ち性が増して塗布行程の作業を困難にする。又、樹脂製造コスト面においても好ましくない。一方、超微粒樹脂の粒子径が０．１９μｍ超になると、鋼板への塗れ性向上効果が十分でなく、塗布工程における作業条件の影響を受けやすいことから制限される。
【００２１】
樹脂は粒子径０．０４〜０．１９μｍの超微粒樹脂を含むものを５〜５０質量部配合する。５質量部未満の場合、塗れ性向上効果が弱まるほか、密着性、打ち抜き性が低下するため制限される。５０質量部超の場合には、塗れ性の向上は優れるが、溶接性、耐熱性を低下するため制限される。５〜５０質量部の範囲であれば、塗れ性、打ち抜き性、溶接性、耐蝕性、耐熱性等の優れる絶縁被膜が得られる。
【００２２】
超微粒樹脂エマルジョンの使用においては、塗れ性、被覆性向上のためには必ずしも樹脂分の１００％を占める必要はなく、溶接性や滑り性等の他の被膜性能向上の目的で、粒子径０．２〜０．５μｍの中粒或いは粗粒エマルジョンと併用しても良い。本発明の超微粒樹脂エマルジョンに通常のエマルジョンを複合して使用する場合は、超微粒樹脂を全樹脂の少なくとも３０質量％以上とし、残部は粒子径０．３５〜０．５０μｍの粗粒子樹脂を配合して使用する。超微粒樹脂が３０質量％未満では塗れ性向上効果が低下する。
【００２３】
この場合にも超微粒樹脂によって塗れ性の向上効果が得られ、外観、占積率低下の影響を最小限として溶接性、滑り性が改善される。超微粒樹脂エマルジョンを用いた本発明においては、その溶液の表面接触角が１５度以下（２０℃、１０Ｂｅ）と、従来の処理液より低下することにより、塗れ性の劇的な向上効果が得られる。
【００２４】
超微粒樹脂と併用して配合される粗粒子の粒子径は０．３５〜０．５０μｍである。０．３５μｍ未満では複合による滑り性や溶接性向上効果が弱い。一方０．５０μｍ超の場合、エマルジョンそのものの沈降性が大きくなって溶液安定性が悪く、工業生産に適さない。
【００２５】
又、絶縁被膜中の有機分としては有機Ｃ量で２．５〜２５％とすることが重要である。有機Ｃ量は樹脂成分添加量と焼付け条件により制御することができる。特に、焼付け温度は重要で、樹脂の炭化を起こさないように焼付け焼鈍温度サイクルを制御するのが重要である。有機Ｃ量が２．５％未満では打ち抜き性、耐蝕性、絶縁性等が低下する。一方、２５．０％超と被膜中に占める割合が多くなりすぎると溶接性を低下するため制限される。
【００２６】
絶縁被膜の膜厚は０．５〜１０μｍである。本発明の塗れ性の優れるエマルジョンを用いた場合には、高速ライン塗布においても膜厚０．５μｍ程度までの均一な薄塗りが可能である。膜厚が０．５μｍ未満では、鋼板の表面状態によっては耐蝕性、絶縁性、打ち抜き性に影響する。一方、１０μｍ超の場合には、本発明の超微粒樹脂エマルジョンを用いても、高速ラインでは、均一な塗膜が得られ難く、高速ラインでは焼付け時の突沸現象と呼ぶ被膜形成での脱水時に生じるクレーター状欠陥が抑制できなくなるため制限される。
【００２７】
本発明の絶縁被膜を用いた製品の表面粗度はＲａ値で０．１〜０．４５とするのが好ましい。超微粒樹脂エマルジョンを用いた場合には、超微粒樹脂効果により均一で、滑らか且つ、光沢の優れる絶縁被膜を形成する。しかしながら被膜表面のＲａが０．１μｍ未満では、溶接性、滑り性等が低下する。一方、粗粒樹脂を混合した場合にはＲａは大きくなるが、０．４５μｍ超では占積率が低下するため制限される。特に本発明の超微粒樹脂のみを樹脂として用いた場合の鋼板の表面粗度は、Ｒａで０．１０〜０．２５μｍとすることができる。
【００２８】
また光沢度はＬ方向入射角４５度の測定条件において７０以上である。光沢度は絶縁被膜のスムース性の一つの目安となる。光沢度の測定は一定角度から光線を当てその反射率を測定することによって得られるもので、市販の光沢度計により測定する。本発明では、光源の入射角４５度（鋼板Ｌ方向）で測定した値で評価した。本発明に規定する範囲で超微粒樹脂エマルジョンを使用する場合、粗粒子エマルジョンとの複合した場合でも光沢度７０以上の、平滑で光沢の優れる絶縁被膜が得られる。
【００２９】
次に本発明の絶縁被膜剤について説明する。
【００３０】
本発明の超微粒樹脂エマルジョンを有機成分とする絶縁被膜剤は、次のような組成で溶液が調整される。即ち、無機成分としてクロム酸をＣｒＯ3として１００質量部に対し、硼酸又は硼酸塩の１種又は２種以上を１０〜４５質量部、ＭｇＯ，ＺｎＯ，ＣａＯ，Ａｌ2Ｏ3の１種又は２種以上を１０〜３５質量部、還元剤としてグリセリン、アジピン酸、コハク酸等の中から選ばれる１種又は２種以上を１０〜３０質量部配合し、さらに、粒子径０．０４〜０．１９μｍの超微粒樹脂を含むエマルジョンを５〜５０質量部配合される。
【００３１】
以上の組成からなる絶縁被膜剤は、溶液の鋼板面での塗れ性が極めて向上し、均一な塗膜が得られる。
【００３２】
クロム酸に配合されるＭｇＯ，ＺｎＯ，ＣａＯ，Ａｌ2Ｏ3の等の酸化物は、重クロム酸塩を生成するモル比以下に抑え、良好な絶縁被膜を得るのに適している。クロム酸及び酸化物成分は絶縁被膜の耐熱性、緻密性、絶縁性、耐蝕性等の向上に寄与する。
【００３３】
配合される酸化物はＭｇＯ，ＺｎＯ，ＣａＯ，Ａｌ2Ｏ3の１種又は２種以上を、ＣｒＯ3１００質量当り１５〜３５質量部である。１５質量部未満ではフリーのクロム酸が増加して、焼付け条件の厳密なコントロールが必要で、被膜のベタツキ、ステイッキング性等を劣化する場合があるため制限される。４５質量部超の場合、酸化物の種類によっては未溶解の酸化物が生じたり、析出物による塗れ性や被膜性能の低下が生じるため制限される。好ましくはＣｒＯ3と酸化物による重クロム酸塩を形成するモル比以下である。
【００３４】
硼酸或いは硼酸塩は絶縁被膜の外観と耐熱性向上に寄与する。ＣｒＯ3：１００質量当り、硼酸硼酸塩が１０質量部未満では耐熱性と外観の向上効果が十分でない。一方、３０部超では溶液での溶解性が低くなり析出が生じて均一な塗膜が得られなかったり、析出物による塗れ性不良が生じる場合があるので制限される。
【００３５】
還元剤であるグリセリン、アジピン酸、コハク酸は被膜焼付け過程のＣｒＯ3の還元に作用し、被膜生成温度の低下、短時間化を実現するのに重要である。還元剤の配合量がＣｒＯ3：１００質量当り、５質量部未満の場合、焼付け条件が狭まり、樹脂成分を安定に保つために不利であり制限される。一方、２０質量部超の場合にも同様に焼付け温度に敏感になりすぎる問題がある。還元剤としては本発明外の有機化合物を用いても良いが、安価に、安定した効果が得られるのはグリセリン、アジピン酸、コハク酸等である。
【００３６】
本発明における樹脂としては、アクリル、スチレン、酢酸ビニル、ポリスチレン、ポリプロピレン、ポリアミド、ポリカーボネート、メラミン、ポリウレタン、アルキド、イソシアネート、エポキシ樹脂の１種又は２種以上、及び／又はこれらの共重合体、架橋体が用いられる。これらの樹脂成分であれば安価で、被膜性能の優れた絶縁被膜が得られる。
【００３７】
樹脂のガラス転移点Ｔｇを２０〜１００℃としたのは、２０℃未満の場合、絶縁被膜が低温で融着するブロッキング現象がおきやすく、被膜硬度が弱いために絶縁被膜が鉄心加工工程で傷がつき易いためである。また、極端な場合、スリッター等で発粉現象が生じやすくなり、好ましくない。一方、Ｔｇが１００℃超では造膜性が低下して、焼付け条件によっては被膜の緻密さや滑らかさが低下して、外観として特に光沢が減少し、被膜性能に影響する。
【００３８】
Ｔｇは主に樹脂の種類によって決まるが、例えばアクリル樹脂のように複数種類の樹脂からなる場合には、メチルメタアクリレート、ブチルアクリレート、エチルアクリレート等の、Ｔｇの異なるアクリル樹脂の配合割合を変更することで調整できる。
【００３９】
本発明の樹脂エマルジョンを製造する際は、界面活性剤としてポリオキシエチレンノニルフェノールエーテル、ポリオキシエチレンノニルフェノールエーテル、ドデシルベンゼルスルホン酸Ｎａ、ポリオキシエチレンオレールエーテルサルフェートＮａ、ポリオキシエチレンノニエルフェノールエーテルサルフェートＮＨ4、スルホコハク酸ジナトリウムのエトキシ化アルコール、スルホコハク酸ジナトリウムのエトキシ化ノニルフェノール半エステル、モノドデシルジフェニルオキシドジスルホン酸Ｎａ、ジドデシルジフェニルオキシドジスルホン酸Ｎａ、アセチレンジオールのＥＯ付加物の１種又は２種以上が用いられる。
【００４０】
界面活性剤は粒子径に応じて適量用いられるのが通常である。本発明の超微粒樹脂エマルジョンにおいては、これらの界面活性剤を適量用いることにより、樹脂粒子の安定性と良好な塗れ性が得られる。本発明の樹脂粒子径では、好ましくは質量で樹脂固形分の０．５〜８．０％が配合される。０．５％未満ではエマルジョン粒子の安定性と塗れ性が得られない。一方、８．０％超になると発砲性により塗布作業性を困難にし、泡による被膜表面欠陥を生じる場合がある。
【００４１】
樹脂はあらかじめ界面活性剤と配合してエマルジョンとした後、他の被膜組成物と配合して絶縁被膜剤とする。これにより、絶縁被膜中で樹脂が凝集せず、均一な分散状態を得ることができる。なお、被膜処理剤配合工程でさらに界面活性剤を添加して使用してもよい。特に、塗布条件（ロール条件、鋼板表面性状等）が劣る場合には、若干の補助効果を発揮する。
【００４２】
以上の組成からなる本発明の絶縁被膜剤の特徴としては、表面接触角が１５度以下である。表面接触角は鋼板に高速塗布する場合の重要な条件の一つであり、小さいほど優れた塗れ性が得られる。表面接触角は固体と液体間の接触角（塗れ）を測定した値で、市販の接触角計（例：協和界面科学製ＣＡ−Ｓ１５０型）で測定した値である。本発明の超微粒樹脂を利用する場合、界面活性剤の添加なしで１５度以下の接触角が達成される。特に、粒子径０．１４未満のエマルジョンの適用においては、表面接触角１０度以下のような極めて小さい値が得られる。
【００４３】
次に本発明の絶縁被膜処理法方について説明する。
【００４４】
本発明の絶縁被膜剤を用いて絶縁被膜焼付け処理を行う場合は、連続焼鈍とコーティングを行うラインにおいて、最終板厚の冷延コイルを洗浄と仕上げ焼鈍を行った後、前記絶縁被膜剤を希釈溶液としてゴムロール等で塗布し、焼付け処理が行われる。焼付け処理は１８０℃〜４００℃である。１８０℃未満では造膜が十分でなく、ベタツキ、耐蝕性やスティッキング性を低下する。一方、４００℃超では有機分の分解や焼失が生じて、外観、打ち抜き性を阻害するのみならず、本発明の目的とする有機成分を有機Ｃとして２．５〜２５．０％含有する絶縁被膜の製品が得られない。好ましい焼付け温度は２５０〜３５０℃である。なお、焼付け時間は特に限定しないが、所望の被膜状態及び有機Ｃ量となるよう、適宜決定される。
【００４５】
【実施例】
（実施例１）
質量でＳｉ：０．３５％、Ａｌ：０．００２％、Ｍｎ：０．２５％を含有する板厚０．５ｍｍの無方向性電磁鋼板冷延コイルを連続焼鈍ラインで焼鈍後、同ラインにて表１に示すような粒子径を変更した樹脂エマルジョンを用いた絶縁被膜剤を乾燥後の質量で１．０ｇ／ｍ2（片面あたり）塗布し、到達板温３３０℃で焼き付け処理を行った。この際のラインスピードは１８０ｍ／ｍｉｎ．であった。
【００４６】
この後、製品からサンプルを切り出し被膜性能について調査した。ここで、ＴＩＧ溶接性は、１２０Ａ，Ｔｈ−Ｗ（１．５ｍｍφ），Ａｒ流量６ｌ／Ｍｉｎ．、締め付け：１２．３ＭＰａ，スピ−ド；６０ｃｍ／分の条件で溶接したときの溶接部外観を判断した。また打ち抜き性は、スチ−ルダイスによる打ち抜きで、かえり高さ５０μｍに達するまでの打ち抜き回数を測定した。結果を表２に示す。
【００４７】
【表１】
【表２】
この試験の結果、本発明の絶縁被膜を塗布した材料は高速コーティング試験において、何れも非常に良好な塗れ性を示し、極めて光沢の優れる均一な絶縁被膜を形成した。被膜特性においても、良好な耐食性、溶接性、打ち抜き性が得られ、特に、粒子径０．１４μｍ以下のエマルジョンを用いた場合には良好であった。
【００５０】
一方、比較例の樹脂エマルジョンの粒子径が０．２５，０．５０μｍの場合は、エッジ部に斑点の発生が多く見られ、絶縁被膜の均一性、光沢度等の外観が本発明に比しかなり劣る結果となり、打ち抜き性においても不均一塗布の影響を受けて本発明に比しやや劣る結果となった。
【００５１】
ここで、図２に本発明で０．１μmの超微粒樹脂エマルジョンを用いた本発明３と、０．２５μｍの樹脂エマルジョンを用いた比較例の顕微鏡写真を示す。本発明の場合には，極めて微細な粒子が分散している様子が見られる。
【００５２】
又、この試験における絶縁被膜中の有機Ｃ量を定量したところ、７．５〜１２．０％であった。
（実施例２）
実施例１と同一の鋼板を用い、連続焼鈍ラインにおいて同様にして処理し、表３に示すように粒子径の異なる樹脂エマルジョンを複合、或いは単独使用した絶縁被膜剤を乾燥後質量で１．５ｇ／ｍ2塗布し、３３０℃で焼付け処理を行った。
【００５３】
この後、このコイルからサンプルを切り出し、実施例１と同様に被膜性能の評価を行った。結果を表４に示す。
【００５４】
【表３】
【表４】
この試験の結果、本発明の絶縁被膜を塗布した材料は高速コーティング試験において、何れも非常に良好な塗れ性を示し、極めて光沢の優れる均一な絶縁被膜を形成した。被膜特性においても、良好な耐食性、溶接性、打ち抜き性が得られ、特に、粒子径０．１０μｍの樹脂を全樹脂中の５０質量％以上用いた場合には塗れ性、耐蝕性が極めて良好であった。又、超微粒樹脂に粗粒子エマルジョンを複合した場合、溶接性が改善される傾向で極めて良好な結果が得られた。
【００５７】
占積率に付いても本発明の複合エマルジョンでは、従来の粗粒子樹脂エマルジョンに比較して遜色なく良好であった。一方、比較例の粗粒子エマルジョンの場合は、エッジ部に斑点の発生が多く見られ、絶縁被膜の均一性、光沢度等の外観が本発明に比しかなり劣る結果となった。
（実施例３）
実施例１と同一の鋼板を用い、連続焼鈍ラインにおいて同様にして処理し、表５に示すように樹脂の粒子径とＴｇを変更した絶縁被膜剤を乾燥後質量で１．０ｇ／ｍ2塗布し、３３０℃で焼付け処理を行った。この試験においては本発明１，２と比較例１の溶液については均一な塗布条件を得られる限界の付着量とラインスピードの関係を調査した。
【００５８】
この後、このコイルからサンプルを切り出し、被膜性能の評価を行った。ここで、スティッキング性は、３×４ｃｍに切断した鋼板を図１（ａ）に示すように積層し、締め付け圧３．９ＭＰａで締め付け、７５０℃×２Ｈｒ，Ｎ2中で焼鈍の後，図１（ｂ）の方法で剥離力を測定した。またブロッキング性は、スティッキング試験と同様にサンプル切り出し、積層、締め付けの後、１００℃×２４Ｈｒ，大気中で加熱し、スティッキング試験と同様に剥離力を測定した。結果を表６に示す。
【００５９】
【表５】
【表６】
この試験の結果、本発明の絶縁被膜を塗布した材料は高速コーティング試験において、何れも非常に良好な塗れ性を示し、極めて光沢の優れる均一な絶縁被膜を形成した。被膜特性においても、良好な耐食性、溶接性、打ち抜き性が得られた。しかしながら樹脂のＴｇが０℃と低い場合にはブロッキング性、スティッキング性がやや劣る傾向となった。一方、比較例のエマルジョン粒子径０．３５μｍの場合は、エッジ部に斑点の発生が多く見られ、絶縁被膜の均一性、光沢度等の外観が本発明に比しかなり劣る結果となった。
【００６２】
又、本発明１，２と比較例１の溶液を用いて、ラインスピード１８０ｍ／ｍｉｎ．の条件で塗布性限界を調査した結果を図３に示す。本発明の超微粒樹脂エマルジョンでは付着量０．５ｇ／ｍ2程度の薄塗りでもほぼ均一に塗布が可能であった。これに対し、比較例の粒子径の大きい従来のエマルジョンの場合、付着量をかなり増加しないと外観の良い絶縁被膜が形成されなかった。この傾向はラインスピードを低下した場合には緩和される傾向であるものの、超微粒樹脂エマルジョンとの差異は歴然としており、工業生産での塗れ性の差異はカバーできるものでないことが確認された。又、活性剤を添加する方法も試みたが、抜本的な解決にはならなかった。
【００６３】
【発明の効果】
本発明によれば、クロム酸、硼酸塩−有機樹脂エマルジョンによる半有機の絶縁被膜において、樹脂エマルジョンの粒子径を超微粒化することにより、鋼板へ塗布性の向上を得、高速ラインにおいて、均一で極めて優れた被膜性能を有する絶縁被膜を得る。これにより、薄塗り被膜での外観、耐食性、溶接性、打ち抜き性等の優れた無方向性電磁鋼板の製造が可能となる。
【図面の簡単な説明】
【図１】スティッキング性とブロッキング性の測定方法を示す図である。
【図２】本発明溶液として粒子径０．１μｍの超微粒樹脂エマルジョンと比較例の０．２５μｍの粗粒樹脂エマルジョンを用いた場合の鋼板表面形状を顕微鏡観察した結果を示す図である。
【図３】本発明溶液と比較例溶液により、良好な塗れ性の得られる塗布量を調査した結果を示す図である。[0001]
BACKGROUND OF THE INVENTION
In the production of a non-oriented electrical steel sheet, the present invention is extremely excellent in paintability in a high-speed line and excellent in coating properties such as punchability, weldability, adhesion, space factor, and appearance as properties of the insulating coating after baking. The present invention relates to an organic-inorganic insulating coating agent and a method for forming an insulating coating using the same.
[0002]
[Prior art]
As is well known, when a non-oriented electrical steel sheet is used for an iron core of a motor or a transformer, the iron core is punched into a predetermined shape and then stacked by welding, welding, caulking or bonding. At this time, strain annealing is performed as necessary. Usually, the non-oriented electrical steel sheet is subjected to an insulating coating treatment.
[0003]
For this insulating film, punching, weldability, corrosion resistance, adhesion, space factor, etc. are important in addition to insulation, and if a strain relief annealing process is required after core punching, after strain relief annealing Adhesion, insulation, corrosion resistance, etc. are also important.
[0004]
Conventionally, as the insulating coating agent, inorganic, organic, and organic-inorganic mixed coatings have been applied according to use conditions and purposes. In general, inorganic coatings are excellent in heat resistance and weldability but inferior in punchability. On the other hand, in the case of an organic coating, punching and adhesion are excellent, but heat resistance is poor and weldability is inferior.
[0005]
In order to solve both of these drawbacks, organic-inorganic coatings capable of obtaining intermediate characteristics have been used. As an organic-inorganic coating, Japanese Patent Application Laid-Open No. 52-33846 discloses an organic resin particle in a treatment liquid when a mixed coating of one or more of phosphoric acid and chromic acid and an organic resin is formed. Has been proposed to form an insulating film excellent in punchability and weldability with a surface roughness of 2 to 10 μHmax.
[0006]
JP-A-3-240970 discloses CrO as a method for producing a non-oriented electrical steel sheet having excellent coating properties after strain relief annealing. Three 100 parts by mass, one or more oxides selected from Al, Mg, Ca, Zn, 20 to 40 parts by mass, acrylic, styrene, vinyl acetate and / or these adjusted to a particle size of 0.2 to 0.5 μm 10 to 60 parts by mass of one or more fine particle emulsion solutions of a resin composed of a copolymer of the following: methyl methacrylate, polyacrylonitrile, polystyrene, cellulose, silicon, melamine, phenol adjusted to a particle size of 1 to 50 μm , PVA resin and / or copolymers thereof, and one or two or more of cross-linked products are disclosed comprising 2 to 30 parts by mass, whereby the punchability and weldability are good and after strain relief It is stated that the lubricity, insulation and corrosion resistance of the resin are remarkably improved.
[0007]
Japanese Patent Laid-Open No. 4-176873 discloses that one or more chromic acid salts and a chromic acid metal salt (CrO Three An aqueous solution containing 0.1 to 1.0 parts by mass of a water-dispersible emulsion and 0.1 to 1.0 parts by mass of spherical organic resin particles having a particle diameter of 2 to 50 μm per 1 part by mass) Has been proposed to form a coating having a surface roughness of 0.5 to 1.5 [mu] m, and a method for treating an electrical insulating coating on an electrical steel sheet having excellent weldability and adhesion.
[0008]
In these conventional techniques, in order to alleviate the weldability deterioration of the organic resin added for the purpose of improving the punchability, an extremely rough particulate material is added to obtain the roughness of the surface roughness and welding. The effect of improving the performance is obtained. For this reason, there are unavoidable adverse effects of a decrease in the space factor, and there are problems that result in paintability, liquid stability, appearance, and cost increase.
[0009]
[Problems to be solved by the invention]
In the conventional coating agent based on the organic-inorganic component as described above and the processing method thereof, the coatability of the coating component on the steel plate, the stability of the liquid, and the appearance are not sufficient, and furthermore, the recent high speed There is a strong demand for further improvements in the problems of the wettability of the liquid in the coating / baking treatment line, the punchability resulting from the coating problem, the weldability and the appearance defect.
[0010]
[Means for Solving the Problems]
The present invention has been devised to improve the wettability of an insulating film agent based on an organic-inorganic component and to improve punchability, weldability, adhesion, and appearance. Insulation coating agent with excellent wettability to improve the disadvantages of conventional semi-organic coatings In Non-oriented electrical steel with excellent surface uniformity and film performance Board The following is the gist of the present invention.
(1) The insulating coating contains 5 to 50 parts by mass of a resin emulsion containing an ultrafine resin having a particle diameter of 0.04 to 0.19 μm with respect to 100 parts by mass as chromic acid, and the particle diameter in the resin An ultrafine resin of 0.04 to 0.19 μm is a resin having a mass of 30% or more of resin solids, treated with an insulating coating agent mainly composed of chromic acid, and organic components in the insulating coating component are organic A non-oriented electrical steel sheet having excellent coating performance, comprising 2.5 to 25.0% as C and having an insulating coating having a thickness of 0.5 to 10.0 μm.
(2) The film performance according to (1), wherein the remainder of the ultrafine resin having a particle size of 0.04 to 0.19 μm in the resin is a resin having a particle size of 0.35 to 0.50 μm Excellent non-oriented electrical steel sheet.
(3) The resin has a Tg of 20 to 100. ℃ (1) or (2) characterized by comprising one or more of acrylic, styrene, vinyl acetate, polystyrene, polypropylene, polyamide, polycarbonate, melamine, polyurethane, alkyd, isocyanate, epoxy resin Non-oriented electrical steel sheet with excellent coating performance.
(4) The surface roughness Ra value of the insulating coating is 0.1 to 1.0 μm, and the glossiness is 70 or more. Excellent coating performance according to any one of (1) to (3) Non-oriented electrical steel sheet.
[0011]
However, glossiness: measured in the L direction, light source incident angle (θ): 45 degrees.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The inventors of the present invention have found that a semi-organic insulating coating containing chromic acid and boric acid as the main component of inorganic components and a resin emulsion as the main component of the organic component is a drawback in the coating process and coating characteristics. In order to solve the problems of poor paintability in the coating and baking line and the resulting punchability and poor weldability, we worked on improving the liquid composition and baking conditions.
[0013]
That is, with the conventional insulating coating technology, particularly in a high-speed line such as 150 m / min or more, the liquid coating property becomes insufficient, uniform coating becomes difficult, and a stable coating film cannot be obtained. It is necessary to perform a low-speed passing plate that impedes or increase the coating amount to improve the paintability. However, even if such a condition change is performed, there is a problem that a product having a stable and uniform film thickness cannot be obtained depending on factors such as the properties of the steel sheet before coating due to the inherent poor liquid paintability. Remains.
[0014]
When such a non-uniform film is formed, non-uniform chipping is caused in the punch at the time of punching. Further, when the film thickness is increased, an increase in the absolute amount of organic components tends to cause poor welding due to decomposition gas during welding.
[0015]
The present inventors have studied solution components and processing conditions in order to solve such problems. As a result, by using a resin emulsion with an ultrafine particle diameter and using a treatment liquid with an appropriate blending condition of chromic acid compound and boric acid compound, the coating effect and adsorption effect on the steel sheet surface by ultrafine particles, In addition, the wettability improvement effect by the surfactant that covers the ultrafine particles greatly improves the wettability of the treatment liquid, obtains a uniform film thickness with excellent appearance, and excellent punchability, weldability, adhesion, corrosion resistance, etc. , Succeeded in developing an insulating coating agent solution and an insulating coating forming technology that can achieve the coating performance of
[0016]
The present invention is described in detail below.
[0017]
In the present invention, first, the insulating coating Agent The composition is characterized by its Insulation coating The non-oriented electrical steel sheet having a beautiful and uniform film obtained by the agent is the basis.
[0018]
That is, it contains an ultrafine resin having a particle size of 0.04 to 0.19 μm as an organic component, is treated with a coating agent mainly composed of chromic acid, and the organic component in the coating is 2.5 to 25% by mass as organic C. It is characterized by the non-oriented electrical steel sheet containing and having a film thickness of 0.5 to 10.0 μm.
[0019]
The particle size of the resin blended in the insulating film first affects the wettability on the steel sheet surface. Use of the ultrafine resin is important for obtaining a thin film thickness of 10 μm or less, particularly 1 μm or less in a high-speed coating line. The smaller the particle size, the better the paintability and uniformity of the coating on the high-speed line. In order to obtain a dramatic improvement in paintability, it is important that the particle size of the ultrafine resin is 0.19 μm or less. In particular, when the particle size is 0.14 μm or less, drastic improvement in paintability can be obtained. When an insulating coating agent mainly composed of such an ultrafine resin emulsion is applied, a product having a uniform surface appearance and a uniform film thickness with no coating defects is obtained.
[0020]
The lower limit of the particle diameter of the ultrafine resin was 0.04 μm. In order to obtain a stable emulsion, it is necessary to use a surfactant according to the specific surface area. However, if the particle diameter is too small, less than 0.04 μm, the necessary amount of the surfactant increases, This increases the foaming property of the coating and makes the operation of the coating process difficult. Also, it is not preferable in terms of resin production cost. On the other hand, if the particle size of the ultrafine resin exceeds 0.19 μm, the effect of improving the wettability to the steel sheet is not sufficient, and it is limited because it is easily affected by the working conditions in the coating process.
[0021]
The resin contains 5 to 50 parts by mass of an ultrafine resin having a particle size of 0.04 to 0.19 μm. When the amount is less than 5 parts by mass, the effect of improving the wettability is weakened, and the adhesiveness and punching property are reduced, so that it is limited. In the case of more than 50 parts by mass, the improvement of the paintability is excellent, but is limited because the weldability and heat resistance are lowered. If it is the range of 5-50 mass parts, the insulating film which is excellent in paintability, punchability, weldability, corrosion resistance, heat resistance, etc. will be obtained.
[0022]
In the use of an ultrafine resin emulsion, it is not always necessary to occupy 100% of the resin content in order to improve paintability and coverage. For the purpose of improving other film performance such as weldability and slipperiness, the particle size is 0. It may be used in combination with a medium or coarse emulsion of 2 to 0.5 μm. When a normal emulsion is used in combination with the ultrafine resin emulsion of the present invention, the ultrafine resin is at least 30% by mass of the total resin, and the remainder is a coarse particle resin having a particle size of 0.35 to 0.50 μm. Mix and use. When the ultrafine resin is less than 30% by mass, the effect of improving the coatability is lowered.
[0023]
Even in this case, the effect of improving the paintability is obtained by the ultrafine resin, and the weldability and the slipperiness are improved with the influence of the appearance and the reduction of the space factor being minimized. In the present invention using an ultrafine resin emulsion, the surface contact angle of the solution is 15 degrees or less (20 ° C., 10 Be), which is lower than that of the conventional processing solution. It is done.
[0024]
The particle diameter of the coarse particles blended with the ultrafine resin is 0.35 to 0.50 μm. If it is less than 0.35 μm, the effect of improving slipperiness and weldability due to the composite is weak. On the other hand, when it exceeds 0.50 μm, the sedimentation property of the emulsion itself becomes large and the solution stability is poor, which is not suitable for industrial production.
[0025]
Moreover, it is important that the organic content in the insulating coating is 2.5 to 25% in terms of organic C. The amount of organic C can be controlled by the resin component addition amount and baking conditions. In particular, the baking temperature is important, and it is important to control the baking annealing temperature cycle so as not to cause carbonization of the resin. When the amount of organic C is less than 2.5%, punchability, corrosion resistance, insulation, and the like are deteriorated. On the other hand, if the proportion of the coating exceeds 25.0% and the coating amount is too large, the weldability is deteriorated, which is limited.
[0026]
The film thickness of the insulating coating is 0.5 to 10 μm. When the emulsion having excellent wettability according to the present invention is used, even thin coating with a film thickness of about 0.5 μm is possible even in high-speed line coating. When the film thickness is less than 0.5 μm, depending on the surface state of the steel sheet, the corrosion resistance, insulation, and punchability are affected. On the other hand, in the case of more than 10 μm, even if the ultrafine resin emulsion of the present invention is used, it is difficult to obtain a uniform coating film on the high-speed line. The crater-like defects that occur are limited because they cannot be suppressed.
[0027]
The surface roughness of the product using the insulating coating of the present invention is preferably 0.1 to 0.45 in terms of Ra value. When the ultrafine resin emulsion is used, a uniform, smooth and excellent gloss coating is formed by the ultrafine resin effect. However, if Ra on the surface of the coating is less than 0.1 μm, weldability, slipperiness and the like are lowered. On the other hand, when coarse resin is mixed, Ra increases, but if it exceeds 0.45 μm, the space factor is reduced, so that it is limited. In particular, the surface roughness of the steel sheet when only the ultrafine resin of the present invention is used as the resin can be 0.10 to 0.25 μm in Ra.
[0028]
Further, the glossiness is 70 or more under the measurement condition of an L direction incident angle of 45 degrees. The glossiness is a measure of the smoothness of the insulating coating. The glossiness is obtained by irradiating light from a certain angle and measuring the reflectance, and is measured by a commercially available glossmeter. In this invention, it evaluated by the value measured with the incident angle of 45 degree | times (steel plate L direction) of the light source. When the ultrafine resin emulsion is used within the range specified in the present invention, a smooth and excellent gloss coating having a glossiness of 70 or more can be obtained even when combined with a coarse particle emulsion.
[0029]
Next, the insulating coating agent of the present invention will be described.
[0030]
The ultrafine resin emulsion of the present invention is an organic component Insulation coating The solution of the agent is adjusted with the following composition. That is, chromic acid as an inorganic component is CrO. Three 10 parts by mass or more of boric acid or borate to 100 parts by mass, MgO, ZnO, CaO, Al 2 O Three 10 to 35 parts by mass of 1 type or 2 or more, and 10 to 30 parts by mass of 1 type or 2 or more types selected from glycerin, adipic acid, succinic acid and the like as a reducing agent. 5 to 50 parts by mass of an emulsion containing an ultrafine resin of 0.04 to 0.19 μm is blended.
[0031]
Insulating film comprising the above composition Agent The coating property of the solution on the steel plate surface is greatly improved, and a uniform coating film can be obtained.
[0032]
MgO, ZnO, CaO, Al blended with chromic acid 2 O Three Oxides such as are suppressed to a molar ratio or less that produces dichromate, and are suitable for obtaining a good insulating film. Chromic acid and an oxide component contribute to improvement of heat resistance, denseness, insulation, corrosion resistance, etc. of the insulating coating.
[0033]
The compounded oxide is MgO, ZnO, CaO, Al 2 O Three 1 type or 2 types or more of CrO Three It is 15-35 mass parts per 100 masses. If it is less than 15 parts by mass, the amount of free chromic acid is increased, and it is necessary to strictly control the baking conditions. In the case of exceeding 45 parts by mass, depending on the type of oxide, an undissolved oxide is generated, and the coating property and the coating performance are deteriorated due to precipitates. Preferably CrO Three And a molar ratio of forming a dichromate salt with an oxide.
[0034]
Boric acid or borate contributes to the appearance and heat resistance of the insulating coating. CrO Three : When the borate borate is less than 10 parts by mass per 100 parts by mass, the heat resistance and the appearance are not sufficiently improved. On the other hand, if it exceeds 30 parts, the solubility in the solution becomes low and precipitation occurs, so that a uniform coating film cannot be obtained, or poor paintability due to precipitates may occur.
[0035]
The reducing agents glycerin, adipic acid, and succinic acid are CrO in the film baking process. Three This is important for reducing the film formation temperature and shortening the time. The amount of reducing agent is CrO Three : When the amount is less than 5 parts by mass per 100 parts by mass, the baking conditions are narrowed, which is disadvantageous and limited in order to keep the resin component stable. On the other hand, in the case of more than 20 parts by mass, there is a problem that it is too sensitive to the baking temperature. As the reducing agent, an organic compound other than the present invention may be used, but it is glycerin, adipic acid, succinic acid, etc. that can provide a stable effect at low cost.
[0036]
As the resin in the present invention, one or more of acrylic, styrene, vinyl acetate, polystyrene, polypropylene, polyamide, polycarbonate, melamine, polyurethane, alkyd, isocyanate, epoxy resin, and / or a copolymer or a cross-linkage thereof are used. The body is used. If these resin components are used, an inexpensive insulating coating having excellent coating performance can be obtained.
[0037]
The reason why the glass transition point Tg of the resin is 20 to 100 ° C. is that when the temperature is less than 20 ° C., the insulating coating is likely to be fused at a low temperature, and the coating hardness is weak. It is because it is easy to stick. In extreme cases, a powdering phenomenon tends to occur with a slitter or the like, which is not preferable. On the other hand, when Tg exceeds 100 ° C., the film-forming property is lowered, and depending on the baking conditions, the denseness and smoothness of the film are lowered, and the gloss is particularly reduced as the appearance, which affects the film performance.
[0038]
Tg is mainly determined by the type of resin. For example, when the resin is composed of a plurality of types of resins such as an acrylic resin, the blending ratio of acrylic resins having different Tg such as methyl methacrylate, butyl acrylate, and ethyl acrylate is changed. Can be adjusted.
[0039]
In producing the resin emulsion of the present invention, polyoxyethylene nonylphenol ether, polyoxyethylene nonylphenol ether, sodium dodecyl benzene sulfonate, polyoxyethylene oleyl ether sulfate Na, polyoxyethylene noniel phenol ether sulfate are used as surfactants. NH Four , Ethoxylated alcohol of disodium sulfosuccinate, ethoxylated nonylphenol half ester of disodium sulfosuccinate, monododecyl diphenyl oxide disulfonate Na, didodecyl diphenyl oxide disulfonate Na, acetylenediol EO adduct Is used.
[0040]
The surfactant is usually used in an appropriate amount depending on the particle diameter. In the ultrafine resin emulsion of the present invention, by using an appropriate amount of these surfactants, the stability of the resin particles and good paintability can be obtained. In the resin particle diameter of the present invention, 0.5 to 8.0% of resin solid content is preferably blended by mass. If it is less than 0.5%, the stability and paintability of the emulsion particles cannot be obtained. On the other hand, if it exceeds 8.0%, the coating workability becomes difficult due to the foaming property, and the coating surface defect may be caused by bubbles.
[0041]
The resin is pre-blended with a surfactant to make an emulsion, and then blended with other coating compositions. Insulation Coating Agent And Thereby, resin does not aggregate in an insulating film, and a uniform dispersion state can be obtained. In addition, you may use it, adding surfactant further in a film processing agent mixing | blending process. Especially when application conditions (roll conditions, steel sheet surface properties, etc.) are inferior , Demonstrate some auxiliary effect.
[0042]
The present invention comprising the above composition Insulation Coating Agent As a feature, the surface contact angle is 15 degrees or less. The surface contact angle is one of the important conditions for high-speed coating on a steel sheet. The surface contact angle is a value obtained by measuring a contact angle (painting) between a solid and a liquid, and is a value measured by a commercially available contact angle meter (for example, CA-S150 manufactured by Kyowa Interface Science). When utilizing the ultrafine resin of the present invention, a contact angle of 15 degrees or less is achieved without the addition of a surfactant. Especially in the application of emulsions with a particle size of less than 0.14 , A very small value such as a surface contact angle of 10 degrees or less is obtained.
[0043]
Next, the method for treating an insulating film of the present invention will be described.
[0044]
Of the present invention Insulation Coating Agent In the case where the insulating film baking process is performed using the above, after the cold rolled coil of the final plate thickness is washed and finish-annealed in the line for continuous annealing and coating, the insulating film Agent Apply as a diluted solution with a rubber roll, etc. , A baking process is performed. The baking process is performed at 180 ° C to 400 ° C. If it is less than 180 ° C., film formation is not sufficient, and stickiness, corrosion resistance and sticking properties are deteriorated. On the other hand, when the temperature exceeds 400 ° C., the organic component is decomposed or burnt out, and not only the appearance and punchability are hindered, but also the insulating component containing 2.5 to 25.0% of the organic component of the present invention as organic C A coated product cannot be obtained. A preferable baking temperature is 250 to 350 ° C. In addition , The baking time is not particularly limited, but the desired coating state And And the amount of organic C is appropriately determined.
[0045]
【Example】
(Example 1)
A non-oriented electrical steel sheet cold rolled coil with a thickness of 0.5 mm containing Si: 0.35% by mass, Al: 0.002%, and Mn: 0.25% is annealed in a continuous annealing line, and then the same line. As shown in Table 1, the insulating film agent using a resin emulsion with a changed particle size as shown in Table 1 is 1.0 g / m in mass after drying. 2 It was applied (per one side) and baked at an ultimate plate temperature of 330 ° C. The line speed at this time is 180 m / min. Met.
[0046]
Thereafter, a sample was cut out from the product and investigated for coating performance. Here, TIG weldability is 120A, Th-W (1.5 mmφ), Ar flow rate 6 l / Min. Tightening: 12.3 MPa, speed: The appearance of the welded part when welding was performed at 60 cm / min was judged. The punching property was measured by punching with a steel die until the burr height reached 50 μm. The results are shown in Table 2.
[0047]
[Table 1]
[Table 2]
As a result of this test, all the materials coated with the insulating coating of the present invention showed very good paintability in a high-speed coating test, and formed a uniform insulating coating with extremely excellent gloss. Also in the film properties, good corrosion resistance, weldability and punchability were obtained, and particularly good when an emulsion having a particle size of 0.14 μm or less was used.
[0050]
On the other hand, when the particle diameter of the resin emulsion of the comparative example is 0.25 and 0.50 μm, many spots are observed at the edge, and the appearance of the insulating film is uniform and glossy compared to the present invention. The results were considerably inferior, and the punchability was slightly inferior to that of the present invention due to the influence of non-uniform coating.
[0051]
Here, FIG. 2 shows micrographs of the
[0052]
Moreover, when the amount of organic C in the insulating coating in this test was quantified, it was 7.5 to 12.0%.
(Example 2)
Using the same steel plate as in Example 1, it was processed in the same manner in a continuous annealing line, and as shown in Table 3, an insulating coating agent composed of resin emulsions having different particle diameters, or used alone, was 1.5 g in weight after drying. / M 2 It apply | coated and the baking process was performed at 330 degreeC.
[0053]
Thereafter, a sample was cut out from this coil, and the coating performance was evaluated in the same manner as in Example 1. The results are shown in Table 4.
[0054]
[Table 3]
[Table 4]
As a result of this test, all the materials coated with the insulating coating of the present invention showed very good paintability in a high-speed coating test, and formed a uniform insulating coating with extremely excellent gloss. Also in coating properties, good corrosion resistance, weldability, and punchability can be obtained. Especially when a resin having a particle size of 0.10 μm is used in an amount of 50% by mass or more of the total resin, the coatability and corrosion resistance are extremely good. there were. In addition, when the coarse particle emulsion was combined with the ultrafine resin, extremely good results were obtained with a tendency to improve the weldability.
[0057]
In terms of space factor, the composite emulsion of the present invention was inferior and better than the conventional coarse particle resin emulsion. On the other hand, in the case of the coarse particle emulsion of the comparative example, many spots were observed at the edge portion, and the appearance such as uniformity and glossiness of the insulating coating was considerably inferior to the present invention.
(Example 3)
Using the same steel plate as in Example 1, the same treatment was performed in a continuous annealing line, and the insulating coating agent with the resin particle size and Tg changed as shown in Table 5 was 1.0 g / m after drying. 2 It apply | coated and the baking process was performed at 330 degreeC. In this test, for the solutions of the
[0058]
Thereafter, a sample was cut out from the coil, and the coating performance was evaluated. Here, the sticking property is obtained by laminating steel plates cut into 3 × 4 cm as shown in FIG. 1 (a), tightening at a tightening pressure of 3.9 MPa, 750 ° C. × 2 Hr, N 2 After annealing, peeling force was measured by the method shown in FIG. Further, the blocking property was cut out as in the sticking test, sampled, laminated, and clamped, then heated at 100 ° C. × 24 Hr in the atmosphere, and the peel force was measured in the same manner as in the sticking test. The results are shown in Table 6.
[0059]
[Table 5]
[Table 6]
As a result of this test, all the materials coated with the insulating coating of the present invention showed very good paintability in a high-speed coating test, and formed a uniform insulating coating with extremely excellent gloss. Also in the film properties, good corrosion resistance, weldability and punchability were obtained. However, when the Tg of the resin is as low as 0 ° C., the blocking property and sticking property tend to be slightly inferior. On the other hand, in the case of the emulsion particle size of 0.35 μm in the comparative example, many spots were observed at the edge portion, and the appearance of the insulation coating such as uniformity and glossiness was considerably inferior to that of the present invention.
[0062]
Also, using the solutions of the
[0063]
【The invention's effect】
According to the present invention, in a semi-organic insulating coating made of chromic acid and a borate-organic resin emulsion, by improving the particle size of the resin emulsion to an ultrafine particle size, it is possible to obtain improved coating properties on a steel plate, and uniformly in a high speed line An insulating film having extremely excellent film performance is obtained. Thereby, it becomes possible to produce a non-oriented electrical steel sheet having excellent appearance, corrosion resistance, weldability, punchability and the like with a thin coating film.
[Brief description of the drawings]
FIG. 1 is a diagram showing a method for measuring sticking property and blocking property.
FIG. 2 is a view showing the result of microscopic observation of the surface shape of a steel sheet when an ultrafine resin emulsion having a particle size of 0.1 μm and a comparatively coarse resin emulsion of 0.25 μm are used as the solution of the present invention.
FIG. 3 is a diagram showing the results of investigating the amount of coating with which good paintability can be obtained with the solution of the present invention and the comparative example solution.
Claims (4)
ただし、光沢度：Ｌ方向、光源入射角（θ）：４５度で測定。The non-oriented electrical steel sheet having excellent coating performance according to any one of claims 1 to 3, wherein the insulating coating has a surface roughness Ra value of 0.1 to 1.0 µm and a glossiness of 70 or more. .
However, glossiness: measured in the L direction, light source incident angle (θ): 45 degrees.
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| JP2002007611A JP4112866B2 (en) | 2002-01-16 | 2002-01-16 | Non-oriented electrical steel sheet with excellent coating performance |
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| JP2002007611A JP4112866B2 (en) | 2002-01-16 | 2002-01-16 | Non-oriented electrical steel sheet with excellent coating performance |
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| JP4354851B2 (en) * | 2004-03-08 | 2009-10-28 | 日新製鋼株式会社 | Antirust treatment liquid for steel plate and antirust treatment method |
| WO2009113392A1 (en) * | 2008-03-13 | 2009-09-17 | 新日本製鐵株式会社 | Electromagnetic steel sheet having insulating coating film with excellent thermal conductivity therein, and process for production thereof |
| JP6074129B2 (en) * | 2010-09-07 | 2017-02-01 | 新日鐵住金株式会社 | Electrical steel sheet with insulation film |
| EP3072936A1 (en) * | 2015-03-24 | 2016-09-28 | Voestalpine Stahl GmbH | Coil and electrical strip or sheet |
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| JPS54134043A (en) * | 1978-04-10 | 1979-10-18 | Kawasaki Steel Co | Electromagnetic steel plate having excellent volume ratio* punching property* and weldability for use as laminated ironcore |
| JPS61183479A (en) * | 1985-02-09 | 1986-08-16 | Nippon Steel Corp | Surface treatment of electrical steel sheet |
| JP2692279B2 (en) * | 1989-07-19 | 1997-12-17 | 日本鋼管株式会社 | A method of forming an insulating film with excellent corrosion resistance on the surface of electrical steel sheets |
| JP3109203B2 (en) * | 1991-12-28 | 2000-11-13 | 日本鋼管株式会社 | Electrical steel sheet having insulating coating excellent in abrasion resistance and method for producing the same |
| JP2662148B2 (en) * | 1992-09-18 | 1997-10-08 | 新日本製鐵株式会社 | Non-oriented electrical steel sheet with excellent coating properties and surface treatment agent for the steel sheet |
| JPH0762551A (en) * | 1993-08-24 | 1995-03-07 | Sumitomo Metal Ind Ltd | Magnetic steel sheet excellent in rust resistance after stress relieving annealing |
| JPH07230908A (en) * | 1993-12-21 | 1995-08-29 | Kobe Steel Ltd | Magnetic steel plate having insulating film and manufacture thereof |
| JP2831975B2 (en) * | 1996-06-28 | 1998-12-02 | 株式会社神戸製鋼所 | Electro-galvanized steel sheet |
| JP3294515B2 (en) * | 1996-10-04 | 2002-06-24 | 日本鋼管株式会社 | Method of forming insulating film for electrical steel sheet |
| JP3299459B2 (en) * | 1996-10-31 | 2002-07-08 | 川崎製鉄株式会社 | Non-oriented electrical steel sheet excellent in punching property and seizure resistance after annealing and method for forming insulating film thereof |
| JP3572938B2 (en) * | 1998-04-17 | 2004-10-06 | Ｊｆｅスチール株式会社 | Electrical steel sheet with excellent sticking and corrosion resistance |
| JP2000026762A (en) * | 1998-04-28 | 2000-01-25 | Mitsui Chemicals Inc | Emulsion composition for treating metal surface |
| JP2000034574A (en) * | 1998-07-15 | 2000-02-02 | Nkk Corp | Silicon steel sheet excellent in resistance to bad odor, sticking and corrosion |
| JP3381632B2 (en) * | 1998-07-15 | 2003-03-04 | 日本鋼管株式会社 | Electrical steel sheet with excellent odor resistance, sticking resistance and corrosion resistance |
| JP3334657B2 (en) * | 1998-12-28 | 2002-10-15 | 住友金属工業株式会社 | Electrical steel sheet with insulating film excellent in corrosion resistance and its manufacturing method |
| JP2003034880A (en) * | 2001-07-26 | 2003-02-07 | Kawasaki Steel Corp | Method for forming insulation film superior in adhesiveness on surface of grain-oriented electrical steel sheet, and method for manufacturing grain- oriented electrical steel sheet |
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