JP4474714B2 - Method for producing electrical steel sheet with insulating coating - Google Patents
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- JP4474714B2 JP4474714B2 JP2000027612A JP2000027612A JP4474714B2 JP 4474714 B2 JP4474714 B2 JP 4474714B2 JP 2000027612 A JP2000027612 A JP 2000027612A JP 2000027612 A JP2000027612 A JP 2000027612A JP 4474714 B2 JP4474714 B2 JP 4474714B2
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Description
【０００１】
【発明の属する技術分野】
本発明は実質的にクロムを含有しない絶縁被膜を有する電磁鋼板およびその製造方法に関し、外観および密着性に優れた絶縁被膜付き電磁鋼板およびその製造方法を提供するものである。
【０００２】
【従来の技術】
モータや変圧器などに使用される電磁鋼板の絶縁被膜は層間抵抗だけでなく、加工成形時および保管時の利便さの観点から種々の特性が要求される。電磁鋼板をモータおよびトランスのコア、磁気シールド材など電磁気を応用した用途に使用する場合、電磁鋼板を金型で打ち抜き積層するので、絶縁被膜の絶縁性が極めて重要になる。また、打抜加工後に磁気特性を向上させるため、７５０〜８５０℃で歪取り焼鈍を行う場合が多く、歪取り焼鈍に耐え得ることが要求される場合がある。このように、電磁鋼板は幅広く使用されるため、用途に適応した絶縁被膜が必要になり、種々の被膜が開発されている。
【０００３】
絶縁被膜は、（１）溶接性、耐熱性を重視し、歪取り焼鈍に耐え得る無機質被膜、（２）打抜性、溶接性の両立を目指し、歪取り焼鈍に耐え得る樹脂含有の有機／無機複合被膜、および（３）特殊用途で歪取り焼鈍不可の有機質被膜、の３種に大別される。汎用品として歪取り焼鈍に耐え得るのは、（１）および（２）の無機質を含む被膜であり、特に、有機樹脂を含有したクロム酸塩系絶縁被膜は、いわゆる１コート１ベークが可能であるため、無機質絶縁被膜に比べて打抜性が格段に向上し、広く利用されている。
【０００４】
例えば、特公昭６０−３６４７６号公報には、少なくとも１種の２価金属を含む重クロム酸塩系水溶液に、該水溶液中のＣｒＯ3 ：１００重量部に対し、有機樹脂エマルジョン（酢酸ビニル／ベオバ比＝９０／１０〜４０／６０）を樹脂固形分で５〜１２０重量部および有機還元剤を１０〜６０重量部の割合で配合した処理液を生地鉄板の表面に塗布し、常法による焼き付けを行なう電磁鋼板の絶縁被膜形成法が開示されている。
【０００５】
また、昨今は環境意識が高まる傾向にあり、電磁鋼板の製造課程あるいは需要家において、クロムを実質的に含まず、打ち抜き性が良好な絶縁被膜が求められている。これに対するものとして、先に本願出願人が提案した、樹脂およびコロイダルシリカを成分とする絶縁被膜（特開平１０−３４８１２号公報）などが知られている。
【０００６】
【発明が解決しようとする課題】
クロムを含まない処理液、例えば、樹脂およびコロイダルシリカを成分とした処理液を電磁鋼板に塗布焼付けした場合、塗布後、焼付乾燥前において、鋼板の鉄成分が処理液中に溶出し、焼付け後の被膜に不透明部分が発生して絶縁被膜の外観および絶縁被膜の鋼板への密着性が劣る場合があった。電磁鋼板の場合は、一般の表面処理鋼板のようにめっきなどの防錆用表面処理をしていないため、特に、絶縁被膜形成用処理液として酸性の水系塗料を塗布した場合、該塗料中に溶出した鉄成分が錆び、良好な絶縁被膜を得ることが難しい場合があった。
【０００７】
本発明は前記問題点を解決すべくなされたものであって、クロムを実質的に含有しない酸性有機樹脂、および必要に応じて無機コロイドを含有する絶縁被膜形成用処理液を電磁鋼板に塗布焼付けした場合においても、鉄の処理液中への溶出を低減し、該被膜の外観および該被膜の鋼板への密着性が良好な絶縁被膜付き電磁鋼板およびその製造方法を提供するものである。
【０００８】
本発明者は、前記問題点を解決すべく鋭意検討した結果、リン酸洗浄により、予め、鋼板表面に厚さ１０〜１００ｎｍのリン系化合物の被膜を形成させることにより、その後塗布焼付けした絶縁被膜の外観および絶縁被膜の鋼板への密着性が改善されること、特に、水系の酸性塗料を塗布焼付けした場合に、その改善効果が大きいことを見出し、本発明を完成したものである。
【０００９】
すなわち、本発明は、乾燥後の絶縁被膜１００質量％に対するクロム含有量が１質量％以下であり、有機樹脂を含有する絶縁被膜付き電磁鋼板を製造するに当たり、該電磁鋼板の表面にリン酸酸洗処理を行い、厚さ１０〜１００ｎｍのリン系化合物層を形成し、ついで、該表面に、有機樹脂および無機コロイドを含有する酸性水溶液である絶縁被膜形成用処理液を塗布し、焼き付けることを特徴とする外観および密着性に優れた絶縁被膜付き電磁鋼板の製造方法である。
【００１０】
また、本発明は、乾燥後の絶縁被膜１００質量％に対するクロム含有量が１質量％以下であり、有機樹脂を含有する絶縁被膜付き電磁鋼板を製造するに当たり、該電磁鋼板の表面にリン酸酸洗処理を行い、厚さ１０〜１００ｎｍのリン系化合物層を形成し、ついで、該表面に、有機樹脂および無機コロイドを含有する酸性水溶液である絶縁被膜形成用処理液を塗布し、焼き付けることを特徴とする外観および密着性に優れた絶縁被膜付き電磁鋼板の製造方法によって製造された電磁鋼板である。
【００１１】
【発明の実施の形態】
本発明の出発素材は電磁鋼板（電気鉄板）である。鋼板中の成分を調整して、比抵抗を大きくし、所望の磁気特性を有するようにした鋼板である。例えば、Ａｌの含有量が０．０５〜３質量％、Ｓｉの含有量が０．１〜７質量％である鋼板が好ましい。
【００１２】
本発明の絶縁被膜付き電磁鋼板の絶縁被膜は、クロムを実質的に含有しない有機樹脂を主成分とする水性塗料を塗布焼付けして得られる被膜である。クロム実質的に含有しないとは、絶縁被膜の乾燥後の重量に対してクロム量が１質量％以下であることを意味する。好ましいのはクロムを含有しない場合である。
【００１３】
絶縁被膜の付着量は乾燥質量で０．０５〜４ｇ／ｍ2 であるのが好ましい。付着量が０．０５ｇ／ｍ2 未満であると被膜が不均一になり、地鉄が露出することにより、スティキング性、沸騰水蒸気曝露性が不足する。一方、付着量が４ｇ／ｍ2 を超えると低温乾燥時に被膜の膨れが発生するなど外観が悪化する。より好ましいのは０．１〜２ｇ／ｍ2 である。
【００１４】
絶縁被膜を形成する樹脂成分は特に制限されないが、アクリル樹脂、アルキッド樹脂、ポリオレフィン樹脂、スチレン樹脂、酢酸ビニル樹脂などの熱可塑性樹脂、エポキシ樹脂、フェノール樹脂、ウレタン樹脂、メラミン樹脂などの熱硬化性樹脂であり、これらの１種または２種以上を組み合わせた有機樹脂である。特に好ましいのはアクリル樹脂、エポキシ樹脂、およびこれらの樹脂の混合物または共重合体である。中でもガラス転移点が３０〜１５０℃であるものが好ましい。ガラス転移点が３０℃未満であると耐溶剤性（特にアセトンのように極性の強い溶剤の場合）、耐食性が不足する。一方、ガラス転移点が１５０℃を超えると低温焼き付け時の造膜性、被膜密着性が劣る。特に好ましいのはガラス転移点が６０〜１５０℃の樹脂である。
【００１５】
絶縁被膜は樹脂成分の他に無機コロイドを含有することができる。無機コロイドの含有により、被膜形成後の歪取り焼鈍が可能になる。無機コロイドは特に制限されないが、Ｓｉ，Ａｌ，Ｚｒ，Ｔｉ，Ｓｎ，Ｓｅ，Ｔｅ，Ａｓ，Ｓｂ，Ｐ，Ｓ，Ｂｉなどの元素の酸化物、水酸化物およびこれらの水和物などであり、造膜性、経済性からコロイダルシリカ（シリカゾル）が好ましい。酸性でのコロイド安定性を考慮するとアルミナ処理したシリカまたはアルミナ含有シリカが特に好ましい。粒径は特に限定されないが、好ましいのは数ｎｍ〜１００ｎｍ程度のものである。
【００１６】
絶縁被膜の性能を一層向上させるために、防錆剤など添加剤を配合してもよい。この場合、歪取り焼鈍後の性能を確保するために有機物質１００質量部に対する無機物質の合計量は３〜３００質量部の範囲とすることが好ましい。
【００１７】
本発明の絶縁被膜付き電磁鋼板においては、電磁鋼板の表面に厚さ１０〜２００ｎｍのリン系化合物層が形成されている。絶縁被膜にＣｒが含有されない場合には、特に外観を良好にし、同時に打ち抜き密着性を満足させるために、厚さを１０〜２００ｎｍに維持する必要がある。厚さが１０ｎｍ未満では、鋼板から処理液への鉄の溶出を十分に抑制することができない。一方、厚さが２００ｎｍを超えると打ち抜き加工時の被膜密着性が低下する傾向が見られる。
リン系化合物の被膜の厚さは、第１図に示すような厚み−ＧＤＳ強度の関係図を用いて計算される。すなわち、絶縁被膜と鋼板の間に存在するリンの最大強度Ｐh の半分Ｐａ［（最大強度Ｐh −バックグラウンドＰb ）×１／２］を与える被膜の厚さＴａである。
リン系化合物はリンと鉄、亜鉛などの金属との化合物であり、ＦｅＰＯ4 ，Ｆｅ3 （ＰＯ4 ）2 ，ＦｅＨＰＯ4 ，Ｆｅ（Ｈ2 ＰＯ4 ）2 ，Ｚｎ2 Ｆｅ（ＰＯ4 ）2 ，Ｚｎ3 （ＰＯ4 ）2 およびこれらの水和物を例示することができる。
【００１８】
リン系化合物層は、リン酸酸洗処理、リン酸塩処理およびこれらの併用により形成されるが、リン酸酸洗処理が特に好ましい。リン酸酸洗処理、リン酸塩処理およびこれらの併用の処理条件（濃度、温度、時間など）はそれぞれの薬剤および処理装置に適したものであれば特に制限されるものではない。被膜の厚さの制御は、例えば、リン酸酸洗処理とリン酸塩処理を併用する場合は、濃度、温度、時間などを適宜調整することにより可能である。
【００１９】
リン酸酸洗処理は、前記のリン系化合物層の層厚が得られるならば特に規制されず、一般的な方法で実施可能である。例えば、濃度０．００１質量％以上および温度５℃以上のリン酸液中に電磁鋼板を浸漬したり、該リン酸液を接触させたりする方法などが好ましく実施される。さらに好ましいのは、濃度０．０１〜２０質量％および温度３０〜７０℃のリン酸液に浸漬する方法である。濃度が０．００１質量％未満であるとリン系化合物層の形成が不十分となり、鉄の溶出を十分抑制することができない。また、温度が５℃未満であるとリン系化合物層の形成反応が遅く、外観向上が十分期待できない。
【００２０】
リン酸塩処理は、前記のリン系化合物層の層厚が得られるならば特に規制されず、一般的な方法で実施可能である。例えば、主剤として鉄、亜鉛、マグネシウム、カルシウム、アルミニウムなどのリン酸塩の１種または２種以上を含有する水溶液に電磁鋼板を浸漬したり、該水溶液に接触させたりする方法などが好ましく実施される。
【００２１】
リン酸酸洗処理とリン酸塩処理を併用する場合は、リン酸酸洗処理を行なった後、リン酸塩処理を行なうのが一般的であるが、これに限定されない。
【００２２】
リン系化合物層が形成のための前記処理を行なった電磁鋼板をリンス処理するのが好ましい。使用する水に制限はないが、水道水で予備洗浄した後、イオン交換水で仕上げるのが好ましい。
リンス処理液として、水を媒体とした塗料を用いることもできる。すなわち、塗料のエマルジョン、ディスパージョン、水溶液も使用できる。
【００２３】
リン系化合物層が形成された電磁鋼板は、ついで絶縁被膜形成用処理液を塗布し焼付けされる。その結果、前記したようなクロムを実質的に含有しない絶縁被膜付き電磁鋼板が得られる。
クロムを実質的に含有しない絶縁被膜形成用処理液中では、クロムを含有する処理液のような鋼板の不動態効果が望めない。よって、乾燥後の絶縁被膜１００質量部に対してクロム量が１質量％以下と低い場合には、鋼板の鉄が溶出しやすくなり、絶縁被膜付き電磁鋼板の外観および被膜密着性などの被膜性能が劣化する。しかし、本発明においては、鋼板表面にリン系化合物層が存在するので、該層が鉄の溶出を抑制するものと推考される。
【００２４】
絶縁被膜形成用処理液の塗布は工業的に一般に用いられるロールコーター法、フローコーター、スプレー塗装、ナイフコーターなど種々の方法で実施される。焼き付け方法も通常工業的に実施される熱風式、赤外式、誘導加熱式などが実施可能である。焼付けは、特に規制するものではなく、例えば、絶縁被膜中の水分が蒸発する程度の低温加熱で十分である。例えば、５０〜２５０℃程度の低い到達板温で１分以内の短時間焼き付けすれば十分である。
【００２５】
【実施例】
以下、本発明の効果を実施例に基づいて具体的に説明する。
（例１〜１９）板厚０．５ｍｍの電磁鋼板の表面に第１表に記載のリン酸処理剤またはリン酸塩処理剤（濃度１質量％）を用いて表面処理し、第１表に示す層厚のリン系化合物層を形成した。ついで、第１表に示す樹脂およびコロイダルシリカ（粒径２０ｎｍ）を含有する酸性（ｐＨ４〜５）水性液（樹脂固形分濃度２質量％、シリカ含有量２質量％）をロールコーターで塗布し、第１表に示す所定時間放置後、到達板温２００℃で焼き付け放冷し、絶縁被膜付き電磁鋼板を得た。絶縁被膜中のクロム含有量、絶縁被膜の外観および絶縁被膜の電磁鋼板との密着性を第１表に合わせて示した。例１〜８は発明例、例９〜１１は参考例、例１２〜１９は比較例である。
【００２６】
第１表から明らかなように本発明例はいずれも外観および密着性に優れている。
なお、各性能評価法の詳細は以下の通りである。
【００２７】
（リン系化合物層の厚さ）
ＧＤＳで表面からのリン強度を測定し、絶縁被膜と鋼板の間に存在するリンの最大強度Ｐh の半分Ｐa ［（最大強度Ｐh −バックグラウンドＰb ）×１／２］に当たるピーク幅をもってリン系化合物層の厚さＴa とした。
【００２８】
（外観判定）
目視により鉄溶出状況を観察し、以下のように判定した。
○： 良好（無色透明な被膜が得られた）
△： 若干悪い（不透明な部分や、変色が若干見られた）
×： 悪い（斑点状の不透明部分が多く見受けられ、醜い）
××： 非常に悪い（全面を不透明な被膜で覆われ、明らかに不良である）
【００２９】
（密着性）
絶縁被膜付き電磁鋼板の鋼板表面に“セロファン”テープを貼付した後、剥がし、その部分の被膜の剥離状態を観察して、以下のように判定した。
◎： 剥離なし
△： やや剥離する（目視で３０％以下の剥離が認められる）
×： 剥離する（目視で３０％超の剥離が認められる）
【００３０】
【表１】
【００３１】
【発明の効果】
本発明により、クロム含有量が少ない、またはクロムを含有しない絶縁被膜形成用処理剤を電磁鋼板に塗布焼き付けしても絶縁被膜の外観および絶縁被膜の密着性の良好な電磁鋼板を得ることができる。
【図面の簡単な説明】
【図１】 リン系化合物層の厚さの評価法を示す説明図である。
【符号の説明】
Ｐh ： ＧＤＳ強度の最大強度
Ｐb ： ＧＤＳ強度のバックグラウンド
Ｐa ： ［（最大強度Ｐh −バックグラウンドＰb ）×１／２］で示されるＧＤＳ強度
Ｔa ： Ｐａの時のリン系化合物層の厚さ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic steel sheet having an insulating coating substantially free of chromium and a method for producing the same, and to provide a magnetic steel sheet with an insulating coating excellent in appearance and adhesion and a method for producing the same.
[0002]
[Prior art]
Insulating coatings on electrical steel sheets used for motors and transformers are required not only for interlayer resistance but also for various characteristics from the viewpoint of convenience during processing and storage. When electromagnetic steel sheets are used for electromagnetic applications such as motor and transformer cores and magnetic shield materials, the insulating properties of the insulating coating are extremely important because the electromagnetic steel sheets are punched and laminated with a mold. In addition, in order to improve the magnetic properties after the punching, strain relief annealing is often performed at 750 to 850 ° C., and it may be required to withstand the strain relief annealing. As described above, since the electrical steel sheet is widely used, an insulating coating suitable for the application is required, and various coatings have been developed.
[0003]
Insulating coatings are (1) an inorganic coating that emphasizes weldability and heat resistance and can withstand strain relief annealing, and (2) a resin-containing organic / resin that can withstand strain relief annealing with the aim of achieving both punchability and weldability. It is roughly classified into three types: inorganic composite coatings, and (3) organic coatings that cannot be subjected to strain relief annealing for special applications. A general-purpose product that can withstand strain relief annealing is a coating containing an inorganic material of (1) and (2). Particularly, a chromate-based insulating coating containing an organic resin can be so-called 1-coat 1-bake. For this reason, the punchability is remarkably improved as compared with the inorganic insulating coating, and it is widely used.
[0004]
For example, in Japanese Patent Publication No. 60-36476, an organic resin emulsion (vinyl acetate / veova) is added to a dichromate aqueous solution containing at least one divalent metal with respect to 100 parts by weight of CrO 3 in the aqueous solution. Ratio = 90/10 to 40/60) is applied to the surface of the dough iron plate with a treatment liquid in which 5 to 120 parts by weight of the resin solid content and 10 to 60 parts by weight of the organic reducing agent are applied, and baking is performed in a conventional manner. A method for forming an insulating coating on an electromagnetic steel sheet is disclosed.
[0005]
In recent years, environmental consciousness tends to increase, and there is a demand for an insulating coating that is substantially free of chromium and has good punchability in the manufacturing process or customers of electrical steel sheets. As a countermeasure against this, an insulating coating (Japanese Patent Laid-Open No. 10-34812), which has been previously proposed by the applicant of the present application and contains resin and colloidal silica as components, is known.
[0006]
[Problems to be solved by the invention]
When a treatment liquid containing no chromium, for example, a treatment liquid composed of resin and colloidal silica is applied and baked onto an electrical steel sheet, the iron component of the steel sheet is eluted in the treatment liquid after application and before baking and drying. In some cases, an opaque portion was generated in the film, and the appearance of the insulating film and the adhesion of the insulating film to the steel sheet were inferior. In the case of electromagnetic steel sheets, since surface treatment for rust prevention such as plating is not performed like general surface-treated steel sheets, especially when an acidic water-based paint is applied as a treatment liquid for insulating film formation, The eluted iron component rusted and it was sometimes difficult to obtain a good insulating film.
[0007]
The present invention has been made to solve the above-mentioned problems, and is a method of applying and baking a treatment liquid for forming an insulating film containing an acidic organic resin substantially free of chromium and, if necessary, an inorganic colloid on an electrical steel sheet. Even in this case, it is possible to provide an electromagnetic steel sheet with an insulating coating and a method for producing the same, in which the elution of iron into the treatment liquid is reduced and the appearance of the coating and the adhesion of the coating to the steel plate are good.
[0008]
As a result of diligent investigation to solve the above problems, the present inventor formed a coating of a phosphorous compound having a thickness of 10 to 100 nm on the surface of the steel plate in advance by phosphoric acid cleaning , and thereafter applied and baked. The present invention has been completed by finding that the appearance of the coating and the adhesion of the insulating coating to the steel sheet are improved, and in particular, when the aqueous acidic coating is applied and baked, the improvement effect is great.
[0009]
That is, according to the present invention, the chromium content with respect to 100% by mass of the insulating coating after drying is 1% by mass or less. A washing treatment is performed to form a phosphorous compound layer having a thickness of 10 to 100 nm, and then an insulating film forming treatment solution that is an acidic aqueous solution containing an organic resin and an inorganic colloid is applied to the surface and baked. It is the manufacturing method of the electrical steel sheet with the insulating film excellent in the external appearance and adhesiveness characterized .
[0010]
In addition, the present invention has a chromium content of 1% by mass or less with respect to 100% by mass of the insulating coating after drying. A washing treatment is performed to form a phosphorous compound layer having a thickness of 10 to 100 nm, and then an insulating film forming treatment solution that is an acidic aqueous solution containing an organic resin and an inorganic colloid is applied to the surface and baked. It is the electrical steel sheet manufactured by the manufacturing method of the electrical steel sheet with the insulation film excellent in the external appearance and adhesiveness characterized .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The starting material of the present invention is an electromagnetic steel plate (electric iron plate). It is a steel plate in which the components in the steel plate are adjusted to increase the specific resistance so as to have desired magnetic properties. For example, a steel plate having an Al content of 0.05 to 3 mass% and an Si content of 0.1 to 7 mass% is preferable.
[0012]
The insulating coating of the electrical steel sheet with an insulating coating of the present invention is a coating obtained by applying and baking an aqueous paint mainly composed of an organic resin that does not substantially contain chromium. The phrase “substantially not containing chromium” means that the amount of chromium is 1% by mass or less based on the weight of the insulating coating after drying. The case where it does not contain chromium is preferable.
[0013]
The adhesion amount of the insulating coating is preferably 0.05 to 4 g / m 2 in terms of dry mass. When the adhesion amount is less than 0.05 g / m 2 , the coating becomes non-uniform, and the base iron is exposed, so that the sticking property and the boiling water vapor exposure property are insufficient. On the other hand, when the adhesion amount exceeds 4 g / m 2 , the appearance deteriorates, for example, swelling of the coating occurs at low temperature drying. More preferred is 0.1 to 2 g / m 2 .
[0014]
The resin component that forms the insulating film is not particularly limited, but is thermosetting such as thermoplastic resin such as acrylic resin, alkyd resin, polyolefin resin, styrene resin, vinyl acetate resin, epoxy resin, phenol resin, urethane resin, melamine resin, etc. It is a resin, and is an organic resin in which one or more of these are combined. Particularly preferred are acrylic resins, epoxy resins, and mixtures or copolymers of these resins. Among them, those having a glass transition point of 30 to 150 ° C. are preferable. When the glass transition point is less than 30 ° C., solvent resistance (particularly in the case of a solvent having a strong polarity such as acetone) and corrosion resistance are insufficient. On the other hand, if the glass transition point exceeds 150 ° C., the film-forming property and film adhesion during low-temperature baking are poor. Particularly preferred is a resin having a glass transition point of 60 to 150 ° C.
[0015]
The insulating coating can contain an inorganic colloid in addition to the resin component. The inclusion of the inorganic colloid makes it possible to perform strain relief annealing after the film formation. The inorganic colloid is not particularly limited, but includes oxides, hydroxides and hydrates of elements such as Si, Al, Zr, Ti, Sn, Se, Te, As, Sb, P, S, and Bi. Colloidal silica (silica sol) is preferable from the viewpoint of film forming properties and economy. In view of the colloidal stability in acidity, silica treated with alumina or silica containing alumina is particularly preferable. The particle size is not particularly limited but is preferably about several nm to 100 nm.
[0016]
In order to further improve the performance of the insulating coating, additives such as a rust inhibitor may be blended. In this case, in order to ensure the performance after strain relief annealing, the total amount of the inorganic substance with respect to 100 parts by mass of the organic substance is preferably in the range of 3 to 300 parts by mass.
[0017]
In the electrical steel sheet with an insulating coating of the present invention, a phosphorous compound layer having a thickness of 10 to 200 nm is formed on the surface of the electrical steel sheet. When Cr is not contained in the insulating coating, it is necessary to maintain the thickness at 10 to 200 nm in order to improve the appearance and satisfy the punching adhesion at the same time. If the thickness is less than 10 nm, the elution of iron from the steel sheet to the treatment liquid cannot be sufficiently suppressed. On the other hand, when the thickness exceeds 200 nm, the coating adhesion at the time of punching tends to decrease.
The thickness of the phosphorus compound coating is calculated using a relationship between thickness and GDS intensity as shown in FIG. That is, the coating thickness Ta gives half Pa [(maximum strength Ph−background Pb) × 1/2] of the maximum strength Ph of phosphorus existing between the insulating coating and the steel plate.
The phosphorus compound is a compound of phosphorus and a metal such as iron or zinc. FePO 4 , Fe 3 (PO 4 ) 2 , FeHPO 4 , Fe (H 2 PO 4 ) 2 , Zn 2 Fe (PO 4 ) 2 , Zn 3 (PO 4 ) 2 and hydrates thereof can be exemplified.
[0018]
The phosphorus-based compound layer is formed by a phosphoric acid pickling treatment, a phosphate treatment and a combination thereof, and a phosphoric acid pickling treatment is particularly preferable. The treatment conditions (concentration, temperature, time, etc.) of the phosphate pickling treatment, the phosphate treatment and the combination thereof are not particularly limited as long as they are suitable for each chemical and treatment apparatus. The thickness of the coating can be controlled, for example, by appropriately adjusting the concentration, temperature, time, etc. when using a phosphate pickling treatment and a phosphate treatment.
[0019]
The phosphoric acid pickling treatment is not particularly restricted as long as the layer thickness of the phosphorus compound layer can be obtained, and can be implemented by a general method. For example, a method of immersing a magnetic steel sheet in a phosphoric acid solution having a concentration of 0.001% by mass or more and a temperature of 5 ° C. or more or bringing the phosphoric acid solution into contact is preferably performed. More preferred is a method of dipping in a phosphoric acid solution having a concentration of 0.01 to 20% by mass and a temperature of 30 to 70 ° C. When the concentration is less than 0.001% by mass, the phosphorus compound layer is not sufficiently formed, and iron elution cannot be sufficiently suppressed. On the other hand, if the temperature is less than 5 ° C., the formation reaction of the phosphorus compound layer is slow, and the appearance cannot be sufficiently improved.
[0020]
The phosphating treatment is not particularly limited as long as the layer thickness of the phosphorus compound layer can be obtained, and can be implemented by a general method. For example, a method in which a magnetic steel sheet is immersed in or brought into contact with an aqueous solution containing one or more of phosphates such as iron, zinc, magnesium, calcium, and aluminum as the main agent is preferably implemented. The
[0021]
When the phosphate pickling treatment and the phosphate treatment are used in combination, the phosphate pickling treatment is generally performed after the phosphoric acid pickling treatment, but the present invention is not limited to this.
[0022]
It is preferable to rinse the electrical steel sheet that has been subjected to the treatment for forming the phosphorus compound layer. Although there is no restriction | limiting in the water to be used, after pre-washing with tap water, finishing with ion-exchange water is preferable.
A paint using water as a medium can also be used as the rinse treatment liquid. That is, paint emulsions, dispersions, and aqueous solutions can also be used.
[0023]
The electrical steel sheet on which the phosphorus compound layer is formed is then baked by applying a treatment liquid for forming an insulating film. As a result, an electrical steel sheet with an insulating coating substantially free of chromium as described above is obtained.
In the treatment liquid for forming an insulating film that does not substantially contain chromium, the passive effect of the steel plate like the treatment liquid containing chromium cannot be expected. Therefore, when the amount of chromium is as low as 1% by mass or less with respect to 100 parts by mass of the insulating coating after drying, the iron of the steel plate is likely to elute, and the coating performance such as the appearance and coating adhesion of the electrical steel sheet with the insulating coating. Deteriorates. However, in the present invention, since a phosphorus-based compound layer is present on the surface of the steel plate, it is assumed that the layer suppresses elution of iron.
[0024]
Application of the treatment liquid for forming the insulating coating is performed by various methods such as a roll coater method, a flow coater, spray coating, and a knife coater that are generally used industrially. As the baking method, a hot air method, an infrared method, an induction heating method, or the like, which is usually performed industrially, can be performed. The baking is not particularly restricted, and for example, low-temperature heating sufficient to evaporate water in the insulating coating is sufficient. For example, it is sufficient if baking is performed for a short time within 1 minute at a low plate temperature of about 50 to 250 ° C.
[0025]
【Example】
Hereinafter, the effect of the present invention will be specifically described based on examples.
(Examples 1 to 19) The surface of a 0.5 mm-thick magnetic steel sheet was surface-treated using the phosphoric acid treatment agent or phosphate treatment agent (concentration 1% by mass) described in Table 1, and A phosphorus compound layer having the thickness shown was formed. Then, an acidic (pH 4-5) aqueous liquid (resin solid content concentration 2 mass%, silica content 2 mass%) containing the resin shown in Table 1 and colloidal silica (particle size 20 nm) was applied with a roll coater, After leaving for a predetermined time shown in Table 1, the steel plate was baked and allowed to cool at an ultimate plate temperature of 200 ° C. to obtain an electrical steel sheet with an insulating coating. The chromium content in the insulating coating, the appearance of the insulating coating, and the adhesion of the insulating coating to the electrical steel sheet are shown in Table 1. Examples 1 to 8 are invention examples, examples 9 to 11 are reference examples, and examples 12 to 19 are comparative examples.
[0026]
As is clear from Table 1, all of the inventive examples are excellent in appearance and adhesion.
The details of each performance evaluation method are as follows.
[0027]
(Thickness of phosphorus compound layer)
Phosphorus compound having a peak width corresponding to half Pa [(maximum intensity Ph−background Pb) × 1/2] of the maximum phosphorus intensity Ph existing between the insulating coating and the steel sheet by measuring the phosphorus intensity from the surface with GDS The layer thickness was Ta.
[0028]
(Appearance judgment)
The state of iron elution was observed visually and judged as follows.
○: Good (colorless and transparent film was obtained)
Δ: Slightly bad (Opaque parts and slight discoloration were observed)
×: Poor (a lot of speckled opaque parts are seen and ugly)
XX: Very bad (the whole surface is covered with an opaque film, which is clearly bad)
[0029]
(Adhesion)
After applying “cellophane” tape to the surface of the electrical steel sheet with an insulating coating, the tape was peeled off, and the peeled state of the coating at that portion was observed, and the determination was made as follows.
◎: No peeling △: Slightly peeling (30% or less peeling is observed visually)
×: Peeling (visually more than 30% peeling is recognized)
[0030]
[Table 1]
[0031]
【The invention's effect】
According to the present invention, an electrical steel sheet having a good appearance of the insulation film and good adhesion of the insulation film can be obtained even if a treatment agent for forming an insulation film containing little or no chromium is applied and baked on the electrical steel sheet. .
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a method for evaluating the thickness of a phosphorus compound layer.
[Explanation of symbols]
Ph: Maximum intensity of GDS intensity Pb: GDS intensity background Pa: GDS intensity Ta expressed by [(maximum intensity Ph-background Pb) × 1/2]: Thickness of phosphorus compound layer at Pa
Claims (2)
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| JP2000027612A JP4474714B2 (en) | 2000-02-04 | 2000-02-04 | Method for producing electrical steel sheet with insulating coating |
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| JP2000027612A JP4474714B2 (en) | 2000-02-04 | 2000-02-04 | Method for producing electrical steel sheet with insulating coating |
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| JP4474714B2 true JP4474714B2 (en) | 2010-06-09 |
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| JP2003193251A (en) * | 2001-12-21 | 2003-07-09 | Jfe Steel Kk | Method of producing silicon steel sheet with insulating film having excellent appearance and adhesion |
| JP4380120B2 (en) * | 2002-08-01 | 2009-12-09 | Ｊｆｅスチール株式会社 | Electrical steel sheet with insulation film |
| JP4360667B2 (en) * | 2002-08-01 | 2009-11-11 | Ｊｆｅスチール株式会社 | Electrical steel sheet with insulation film |
| JP4122927B2 (en) * | 2002-10-28 | 2008-07-23 | Ｊｆｅスチール株式会社 | Oriented electrical steel sheet for magnetic shield with excellent coating adhesion and corrosion resistance |
| JP3921199B2 (en) * | 2003-11-04 | 2007-05-30 | 新日本製鐵株式会社 | Method for producing unidirectional silicon steel sheet excellent in film adhesion of tension imparting insulating film |
| JP4264362B2 (en) * | 2004-01-15 | 2009-05-13 | 新日本製鐵株式会社 | Insulating coating agent for grain-oriented electrical steel sheet not containing chromium and grain-oriented electrical steel sheet having an insulating film not containing chromium |
| BRPI0520381B1 (en) | 2005-07-14 | 2016-03-08 | Nippon Steel & Sumitomo Metal Corp | non-chromium grain oriented electrical steel sheet insulating film agent. |
| KR101561280B1 (en) | 2013-11-27 | 2015-10-16 | 주식회사 포스코 | Coating composition for non-oriented electrical steel, method of manufacturing non-oriented electrical product and non-oriented electrical product |
| JP6455526B2 (en) * | 2014-12-26 | 2019-01-23 | 新日鐵住金株式会社 | Electrical steel sheet |
| US20180022927A1 (en) * | 2015-02-05 | 2018-01-25 | Nippon Steel & Sumitomo Metal Corporation | Electrical steel sheet |
| KR102412265B1 (en) | 2017-07-13 | 2022-06-24 | 닛폰세이테츠 가부시키가이샤 | grain-oriented electrical steel sheet |
| CN110832117B (en) * | 2017-07-13 | 2022-01-07 | 日本制铁株式会社 | Grain-oriented electromagnetic steel sheet and method for producing same |
| WO2020149322A1 (en) | 2019-01-16 | 2020-07-23 | 日本製鉄株式会社 | Grain-oriented electrical steel sheet and method for manufacturing same |
| KR102582970B1 (en) | 2019-01-16 | 2023-09-26 | 닛폰세이테츠 가부시키가이샤 | Manufacturing method of grain-oriented electrical steel sheet |
| JP7188458B2 (en) | 2019-01-16 | 2022-12-13 | 日本製鉄株式会社 | Grain-oriented electrical steel sheet and manufacturing method thereof |
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