JP2003193252A - Method of producing silicon steel sheet with insulating film having excellent film appearance - Google Patents
Method of producing silicon steel sheet with insulating film having excellent film appearanceInfo
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- JP2003193252A JP2003193252A JP2001388647A JP2001388647A JP2003193252A JP 2003193252 A JP2003193252 A JP 2003193252A JP 2001388647 A JP2001388647 A JP 2001388647A JP 2001388647 A JP2001388647 A JP 2001388647A JP 2003193252 A JP2003193252 A JP 2003193252A
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- Prior art keywords
- steel sheet
- coating
- film
- insulating film
- temperature
- Prior art date
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Abstract
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、六価クロム等の有
害な化合物を含まず、また低温焼付けで形成することが
できる絶縁被膜付きの電磁鋼板の製造方法に関し、特に
その被膜外観の有利な向上を図ろうとするものである。
【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
び保管時における利便性の観点から種々の特性が要求さ
れる。すなわち、電磁鋼板を、モータやトランスのコア
および磁気シールド材など電磁気を応用した用途に利用
する場合には、電磁鋼板を所定の形状に打ち抜いたの
ち、積層して使用するので、その表面に被成した絶縁被
膜の絶縁性が特に重要になる。また、打ち抜き加工後の
電磁鋼板は、その磁気特性を向上させるために、750〜8
50 ℃程度の温度で歪取り焼鈍が行われることが多いた
め、かような高温での歪取り焼鈍に耐え得る被膜特性が
要求される。このように、電磁鋼板は、幅広い用途に使
用されることから、用途に応じた種々の絶縁被膜の開発
が行われている。
【０００３】ところで、絶縁被膜の種類は、(1) 溶接
性、耐熱性を重視し、高温での歪取り焼鈍に耐え得る無
機質被膜、(2) 打抜性、溶接性の両立を目的とし、高温
での歪取り焼鈍に耐え得る樹脂含有の有機・無機複合被
膜、(3) 打抜性には優れるものの、歪取り焼鈍が不可の
有機質被膜の３つに大別される。上記したように、汎用
品として歪取り焼鈍に耐え得るのは、 (1)および(2) に
掲げた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
で製造が可能なため、無機質絶縁被膜に比較して打抜性
を格段に向上させ得ることから、広く利用されている。
【０００４】例えば、特公昭60−36476 号公報には、少
なくとも一種の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＝90／10〜40／6
0））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、地鉄鋼板の
表面に塗布し、常法による焼付けを行うことからなる電
磁鋼板の絶縁被膜形成方法が開示されている。しかしな
がら、少なくとも一種の２価金属を含むクロム酸塩系被
膜は、六価クロムを三価に還元して不溶化する必要があ
るため、比較的高温で焼き付ける必要がある。なお、六
価クロムは毒性が強いため、環境汚染の問題が懸念さ
れ、さらには廃液処理にコストが嵩むという問題があ
る。
【０００５】上記の問題の解決策としては、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主
成分とする処理液を、絶縁被膜材料として利用すること
が考えられるが、かような処理液を電磁鋼板の表面に塗
布、焼き付けた場合、塗布後、焼付け乾燥前において、
鋼板中のFeが塗装被膜中に溶出し、被膜の外観および密
着性の急激な劣化を招く。
【０００６】この点、出願人会社は、上記の問題を解決
するものとして、特願2000−27612号明細書において、
クロムを含まない絶縁コーティング液を塗布するに先立
ち、地鉄鋼板の表面にりん酸化合物被膜を被成すること
により、クロムを含有せず、また低温での焼付けが可能
な絶縁被膜付きの電磁鋼板を提案した。上記の技術によ
り、被膜の外観や密着性に優れた絶縁被膜が得られるよ
うになった。
【０００７】
【発明が解決しようとする課題】しかしながら、上記の
技術を適用した場合であっても、絶縁被膜に白色模様が
生じる場合があり、被膜外観の著しい劣化を招いてい
た。また、かような白色模様が生じた箇所は、単に外観
を劣化させるだけでなく、歪取り焼鈍後の耐はく離性に
劣る点でも問題を残していた。
【０００８】本発明は、上記の問題を有利に解決するも
ので、クロムを含有せず、また低温での焼付け（50〜25
0 ℃）が可能な絶縁被膜を形成するに際し、白色模様の
発生を効果的に防止して、優れた被膜外観さらに耐はく
離性を有する絶縁被膜付き電磁鋼板を有利に製造するこ
とができる方法を提案することを目的とする。
【０００９】
【課題を解決するための手段】まず、発明者らは、白色
模様が発生した部分を電子顕微鏡で観察したところ、か
ような白色模様部は、表面がひび割れ状になっているだ
けでなく、表面粗さも粗くなっていること、さらには周
囲の正常塗装部と比較して膜厚が局所的に厚くなってい
ることが判明した。
【００１０】そこで、かような被膜異常を解消すべく鋭
意検討を重ねた結果、以下に述べる知見を得た。
(1) 熱風炉で絶縁被膜を焼き付ける場合、造膜時におけ
る被膜の最表面と鋼板接触部との温度差が大きいと、均
一な造膜反応が起こらず、その結果被膜の最表面にひび
割れが生じる。そして、かような現象は特に被膜厚が厚
い領域で生じ易い。
(2) この点、造膜開始時の焼付け温度を低温化し、膜厚
方向に均一に伝熱させるようにすれば、白色模様の発生
は防止される。本発明は、上記の知見に立脚するもので
ある。
【００１１】すなわち、本発明は、電磁鋼板の表面に、
六価クロムを含まない絶縁被膜を、低温焼付けによって
被成することからなる電磁鋼板の製造方法において、絶
縁被膜の塗装処理に先立ち、りん酸酸洗処理および乾燥
処理を施して、鋼板の表面にりん酸化合物被膜を形成
し、ついで絶縁被膜用処理液を塗装したのち、その焼付
けを行うに際し、昇温速度と到達板温が下記の関係を満
足する条件下で焼付け処理を行うことを特徴とする被膜
外観に優れた絶縁被膜付き電磁鋼板の製造方法である。
記
ｙ≦0.0355・Ｔ
ここで、ｙ：昇温速度（℃/s）
Ｔ：到達板温（℃）
【００１２】
【発明の実施の形態】以下、本発明を具体的に説明す
る。前述したとおり、白色模様の発生は、造膜時におけ
る被膜の最表面と鋼板接触部との温度差が大きく、均一
な造膜反応が起こらないことに起因することが解明され
た。従って、かような白色模様の発生を防止するには、
造膜開始時の焼付け温度を低温化し、膜厚方向に均一に
伝熱させれば良く、そのためには、絶縁被膜の塗装焼付
け時における昇温速度が重要なファクターと考えられ
る。
【００１３】そこで、発明者らは、白色模様の発生に及
ぼす昇温速度の影響を焼付到達板温との関係で調査し
た。すなわち、りん酸酸洗処理およびその後の乾燥処理
によって40nm厚のりん酸化合物被膜を被成した電磁鋼板
に対し、樹脂／コロイダルシリカの質量配合割合が50／
50の絶縁被膜用塗布液を塗装したのち、昇温速度および
到達板温を種々に変化させ、到達温度に１分間保持する
焼付け処理を行った。かくして得られた絶縁被膜付き電
磁鋼板の白色模様の発生状況について調べた結果を、昇
温速度と焼付到達板温との関係で図１に示す。
【００１４】同図に示したとおり、白色模様の発生の有
無は、昇温速度および焼付到達板温と強い相関があり、
昇温速度をｙ（℃/s）、焼付到達板温をＴ（℃）とした
場合、次式
ｙ≦0.0355・Ｔ
を満足する条件下で焼付け処理を行うことによって、白
色模様の発生を完全に防止できることが判明した。
【００１５】すなわち、下記式を満足する条件下で焼付
け処理を行うことによって、所期した目的が有利に達成
されることが究明されたのである。
記
ｙ≦0.0355・Ｔ
ここで、ｙ：昇温速度（℃/s）
Ｔ：到達板温（℃）
なお、到達板温は、50〜250 ℃程度とするのが好まし
く、また加熱時間はその温度に１分間程度保持する短時
間焼付けで十分である。
【００１６】次に、本発明を工程順に具体的に説明す
る。まず、本発明では、絶縁被膜の塗装処理に先立ち、
りん酸酸洗処理および乾燥処理により、鋼板の表面にり
ん酸化合物被膜を形成する。上記したりん酸化合物被膜
の膜厚は10〜200 nm程度とするのが好ましい。というの
は、被膜厚みが10nmに満たないと鋼板から塗装被膜中へ
のFeの溶出を完全に防止することができず、一方 200nm
を超えると打ち抜き加工時の被膜密着性が劣化する傾向
にあるからである。ここに、りん酸化合物とは、りんと
鉄、亜鉛等の金属との化合物であり、例えばFePO4, Fe3
(PO4)2, FeHPO4, Fe(H2PO4)2, Zn2Fe (PO4)2および Zn3
(PO4)2やこれらの水和物が例示される。
【００１７】また、りん酸酸洗処理工程における処理条
件（処理液の濃度、処理温度、処理時間等）は、特に制
限されることはなく、乾燥処理後に上記の膜厚のりん酸
化合物被膜を生成させることができればいずれでも良い
が、特に好適な処理条件を掲げると次のとおりである。
・処理液（H3PO4)濃度：0.01〜20mass％
・処理温度：５℃以上、より好ましくは30〜70℃
【００１８】なお、上記のりん酸酸洗処理に代えて、り
ん酸塩処理を用いることもでき、さらにはりん酸酸洗処
理とりん酸塩処理とを併用することもできる。この場合
のりん酸塩処理としては、例えば、主剤として鉄、亜
鉛、マグネシウム、カルシウムおよびアルミニウム等の
りん酸塩の一種または二種以上を含有する水溶液に電磁
鋼板を浸漬したり、該水溶液を鋼板表面に塗布する方法
が好ましい。
【００１９】上記のりん酸化合物被膜形成処理後、絶縁
被膜の塗装処理を行う。図２に、本発明に従う、絶縁被
膜の塗装工程を模式で示したが、図中番号１が絶縁被膜
の塗装装置、２が熱風炉による塗液焼付け設備、３が鋼
板の冷却設備である。本発明では、上記の塗液焼付け設
備２における焼付け処理において、昇温速度と到達板温
を管理し、これらの関係が次式
ｙ≦0.0355・Ｔ
を満足するように制御することが重要である。なお、従
来は、焼付け時における昇温速度については特に考慮が
払われてなく、作業能率の面から10℃/s以上で昇温する
のがほとんどであった。
【００２０】上記の処理によって形成する絶縁被膜とし
ては、クロムを実質的に含有しない有機樹脂からなる有
機質被膜、またはかような有機樹脂中に無機コロイドを
含有する有機・無機複合被膜が好適である。ここに、上
記の有機樹脂としては、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
脂等の熱可塑性樹脂およびエポキシ樹脂、フェノール樹
脂、ウレタン樹脂、メラニン樹脂等の熱硬化性樹脂が有
利に適合する。中でもガラス転移温度が30〜150 ℃程度
のものが好適である。また、無機コロイドとしては、S
i，Al，Zr，Ti，Sn，Se，Te，As，Sb，Ｐ，ＳおよびBi
等の酸化物、水酸化物およびこれらの水和物が有利に適
合するが、とりわけ好適なのはコロイダルシリカであ
る。なお、かかる無機コロイドの粒径は、特に限定され
ないが、数nm〜100 nm程度のものが好適である。
【００２１】さらに、絶縁被膜の付着量は、乾燥質量で
0.05〜４g/m2程度とするのが好ましい。というのは、付
着量が0.05g/m2に満たないと被膜が不均一になって耐ス
ティッキング性や耐沸騰水蒸気曝露性が劣化し、一方４
g/m2を超えると低温乾燥時に被膜膨れが発生して被膜外
観が損なわれるからである。ここに、かような絶縁被膜
用処理液の塗装方法としては、従来から一般的に用いら
れているロールコーター法、フローコーター法、スプレ
ー塗装およびナイフコーター等を使用することができ
る。また、焼付け方法については、通常工業的に実施さ
れている熱風式が有利に適合する。
【００２２】
【実施例】板厚：0.5 mmの電磁鋼板の表面に、りん酸液
(H3PO4濃度：２mass％）、液温：30℃の条件でりん酸酸
洗処理を施し、ついで80℃, 50秒の乾燥処理を施して膜
厚：20nmのりん酸化合物被膜を鋼板の表面に被成したの
ち、エポキシ樹脂およびコロイダルシリカを含有する水
性液（樹脂固形分濃度：２mass％、シリカ含有量：２ma
ss％）の絶縁被膜用処理液をロールコーターで塗布し、
昇温速度：7.0 ℃/s, 到達板温：200 ℃、加熱時間：１
分間の条件で焼き付けて、絶縁被膜付き電磁鋼板（発明
例）を製造した。また、比較のため、昇温速度を従来の
ように10℃/sとする以外は、発明例と同様にして絶縁被
膜付き電磁鋼板（比較例）を製造した。
【００２３】かくして得られた各絶縁被膜付き電磁鋼板
の被膜外観について調査したところ、比較例では約20％
の白色模様が発生したのに対し、発明例では白色模様の
発生は全く見られなかった。
【００２４】
【発明の効果】かくして、本発明によれば、クロムを含
有しない絶縁被膜を低温焼付けで形成するに際し、従来
懸念された白色模様の発生を完全に防止して、被膜外観
および耐はく離性に優れた絶縁被膜付き電磁鋼板を安定
して得ることができる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a magnetic steel sheet which does not contain harmful compounds such as hexavalent chromium and has an insulating coating which can be formed by low-temperature baking. In particular, it is intended to advantageously improve the appearance of the coating. 2. Description of the Related Art Insulating coatings on magnetic steel sheets used for motors, transformers and the like are required to have various characteristics from the viewpoint of not only interlayer resistance but also convenience during working and storage. In other words, when electromagnetic steel sheets are used for applications that apply electromagnetism such as motor and transformer cores and magnetic shielding materials, the electromagnetic steel sheets are punched into a predetermined shape and then laminated and used. The insulating property of the formed insulating film becomes particularly important. The magnetic steel sheet after punching is 750 to 8 to improve its magnetic properties.
Since the strain relief annealing is often performed at a temperature of about 50 ° C., a film property capable of withstanding the strain relief annealing at such a high temperature is required. As described above, since the electromagnetic steel sheet is used for a wide range of applications, development of various insulating films according to the application has been performed. [0003] By the way, the types of insulating coatings are (1) an inorganic coating which emphasizes weldability and heat resistance and which can withstand strain relief annealing at high temperatures, and (2) a combination of punching properties and weldability. It is roughly classified into three types: a resin-containing organic-inorganic composite film that can withstand high-temperature strain relief annealing, and (3) an organic film that is excellent in punching properties but cannot perform strain relief annealing. As described above, the coatings containing inorganic substances listed in (1) and (2) can withstand the strain relief annealing as a general-purpose product. In particular, the chromate-based insulating coating containing an organic resin is a so-called 1 Since it can be manufactured with one coat of baking, it is widely used because punching properties can be remarkably improved as compared with inorganic insulating coatings. For example, Japanese Patent Publication No. 60-36476 discloses a dichromate aqueous solution containing at least one divalent metal, an organic resin emulsion (vinyl acetate) based on 100 parts by weight of CrO 3 in the aqueous solution. / Veova ratio = 90/10-40/6
0)) is applied to the surface of a steel base steel sheet with a treatment liquid in which 5 to 120 parts by weight of a resin solid content and 10 to 60 parts by weight of an organic reducing agent are blended, and baking is performed by a conventional method. A method for forming an insulating coating on an electromagnetic steel sheet is disclosed. However, a chromate-based coating containing at least one kind of divalent metal needs to be burned at a relatively high temperature because hexavalent chromium needs to be reduced to trivalent and insolubilized. Since hexavalent chromium is highly toxic, there is a concern about environmental pollution, and furthermore, there is a problem that waste liquid treatment is costly. As a solution to the above problem, it is conceivable to use a processing solution containing no chromium, for example, a processing solution containing resin and colloidal silica as main components, as an insulating coating material. When applied to the surface of the electromagnetic steel sheet, baking, after coating, before baking and drying,
Fe in the steel sheet elutes into the paint film, causing a rapid deterioration of the appearance and adhesion of the film. [0006] In this regard, the applicant company has disclosed in Japanese Patent Application No. 2000-27612 as a solution to the above problem.
Prior to applying a chromium-free insulating coating solution, a magnetic steel sheet with an insulating coating that does not contain chromium and can be baked at low temperatures by forming a phosphate compound coating on the surface of the base steel sheet Suggested. According to the above technique, an insulating film having excellent appearance and adhesion can be obtained. [0007] However, even when the above technique is applied, a white pattern may be formed on the insulating film, resulting in remarkable deterioration of the film appearance. In addition, the portion where such a white pattern is formed not only deteriorates the appearance, but also has a problem in that the peeling resistance after strain relief annealing is poor. The present invention advantageously solves the above-mentioned problems, and does not contain chromium and has a low temperature baking (50 to 25).
0 ° C.), a method capable of effectively preventing the occurrence of a white pattern when forming an insulating coating capable of producing an electromagnetic steel sheet with an insulating coating having excellent coating appearance and peel resistance. The purpose is to propose. Means for Solving the Problems First, when the inventors observed a portion where a white pattern was generated with an electron microscope, the white pattern portion had only a cracked surface. However, it was also found that the surface roughness was rough, and that the film thickness was locally thicker than the surrounding normal painted portion. Therefore, as a result of intensive studies to eliminate such a coating abnormality, the following findings were obtained. (1) When baking an insulating film in a hot blast stove, if the temperature difference between the outermost surface of the film and the steel plate contact area during film formation is large, a uniform film forming reaction does not occur, and as a result, cracks are formed on the outermost surface of the film. Occurs. Such a phenomenon tends to occur particularly in a region where the film thickness is large. (2) In this regard, if the baking temperature at the start of film formation is lowered and the heat is uniformly transferred in the film thickness direction, generation of a white pattern is prevented. The present invention is based on the above findings. That is, the present invention provides a method for manufacturing a magnetic steel sheet, comprising:
In a method of manufacturing an electrical steel sheet comprising applying an insulating coating containing no hexavalent chromium by low-temperature baking, prior to the coating of the insulating coating, a phosphoric acid pickling treatment and a drying treatment are applied to the surface of the steel sheet. After forming a phosphate compound film, and then applying a treatment liquid for an insulating film, when performing baking, the baking treatment is performed under conditions where the temperature rise rate and the reached plate temperature satisfy the following relationship. This is a method for producing an electrical steel sheet with an insulating coating having excellent coating appearance. Note that y ≦ 0.0355 · T Here, y: temperature rise rate (° C./s) T: ultimate plate temperature (° C.) The present invention will be specifically described below. As described above, it has been clarified that the occurrence of the white pattern is caused by a large temperature difference between the outermost surface of the coating and the contact portion of the steel sheet at the time of film formation, and a uniform film forming reaction does not occur. Therefore, to prevent the occurrence of such a white pattern,
What is necessary is to lower the baking temperature at the start of film formation and to conduct heat uniformly in the film thickness direction. For that purpose, it is considered that the rate of temperature rise at the time of baking the coating of the insulating film is an important factor. Therefore, the present inventors investigated the effect of the heating rate on the occurrence of a white pattern in relation to the temperature of the plate that reached the printing. That is, the mass ratio of resin / colloidal silica was 50/50 with respect to the magnetic steel sheet coated with a phosphate compound film having a thickness of 40 nm by the phosphoric acid pickling treatment and the subsequent drying treatment.
After applying 50 coating liquids for an insulating film, a baking treatment was performed in which the heating rate and the reached plate temperature were variously changed and the obtained temperature was maintained for 1 minute. FIG. 1 shows the relationship between the heating rate and the temperature of the sheet reached by baking. As shown in the figure, the presence or absence of the occurrence of a white pattern has a strong correlation with the heating rate and the temperature of the plate that has reached the seizure.
Assuming that the heating rate is y (° C./s) and the plate temperature at which the printing has been achieved is T (° C.), the baking treatment is performed under the conditions satisfying the following equation: y ≦ 0.0355 · T to completely generate the white pattern. It was found that it could be prevented. That is, it has been found that the intended purpose can be advantageously achieved by performing the baking treatment under the conditions satisfying the following formula. Note that y ≦ 0.0355 · T where, y: heating rate (° C./s) T: reached plate temperature (° C.) The reached plate temperature is preferably about 50 to 250 ° C., and the heating time is Short-time baking at a temperature of about one minute is sufficient. Next, the present invention will be specifically described in the order of steps. First, in the present invention, prior to the coating treatment of the insulating film,
The phosphoric acid pickling treatment and the drying treatment form a phosphate compound film on the surface of the steel sheet. The thickness of the above-mentioned phosphate compound film is preferably about 10 to 200 nm. That is, if the coating thickness is less than 10 nm, the elution of Fe from the steel sheet into the coating film cannot be completely prevented, while 200 nm
This is because, when it exceeds, the adhesiveness of the coating at the time of punching tends to deteriorate. Here, the phosphoric acid compound is a compound of phosphorus and a metal such as iron or zinc, for example, FePO 4 , Fe 3
(PO 4 ) 2 , FeHPO 4 , Fe (H 2 PO 4 ) 2 , Zn 2 Fe (PO 4 ) 2 and Zn 3
(PO 4 ) 2 and hydrates thereof are exemplified. The treatment conditions (treatment solution concentration, treatment temperature, treatment time, etc.) in the phosphoric acid pickling treatment step are not particularly limited, and the phosphoric acid compound film having the above film thickness after the drying treatment is obtained. Any method can be used as long as it can be generated. Particularly preferred processing conditions are as follows.・ Treatment liquid (H 3 PO 4 ) concentration: 0.01 to 20 mass% ・ Temperature: 5 ° C. or more, more preferably 30 to 70 ° C. In place of the above-mentioned phosphoric acid pickling treatment, phosphate treatment Can be used, and furthermore, the phosphoric acid pickling treatment and the phosphate treatment can be used in combination. As the phosphate treatment in this case, for example, immersing the electromagnetic steel sheet in an aqueous solution containing one or more of phosphates such as iron, zinc, magnesium, calcium and aluminum as a main agent, The method of applying to the surface is preferred. After the above-mentioned phosphoric acid compound film forming treatment, a coating treatment of the insulating film is performed. FIG. 2 schematically shows a process of coating an insulating film according to the present invention. In the figure, reference numeral 1 denotes a coating device for an insulating film, reference numeral 2 denotes a coating liquid baking facility using a hot-blast furnace, and reference numeral 3 denotes a cooling facility for a steel plate. In the present invention, in the baking treatment in the coating liquid baking equipment 2 described above, it is important to control the heating rate and the reached plate temperature, and to control such a relationship so as to satisfy the following expression y ≦ 0.0355 · T. . Heretofore, no particular consideration has been given to the rate of temperature rise during baking, and in most cases, the rate of temperature rise is 10 ° C./s or more from the viewpoint of work efficiency. As the insulating film formed by the above treatment, an organic film made of an organic resin substantially containing no chromium, or an organic / inorganic composite film containing an inorganic colloid in such an organic resin is preferable. . Here, as the organic resin, thermoplastic resins such as acrylic resin, alkyd resin, polyolefin resin, styrene resin and vinyl acetate resin and thermosetting resins such as epoxy resin, phenol resin, urethane resin and melanin resin are advantageous. Complies with Among them, those having a glass transition temperature of about 30 to 150 ° C. are preferred. As the inorganic colloid, S
i, Al, Zr, Ti, Sn, Se, Te, As, Sb, P, S and Bi
Oxides, hydroxides and hydrates thereof are advantageously suitable, but especially preferred is colloidal silica. The particle size of the inorganic colloid is not particularly limited, but is preferably about several nm to 100 nm. Further, the adhesion amount of the insulating film is expressed by dry mass.
It is preferred to be about 0.05 to 4 g / m 2 . If the amount of coating is less than 0.05 g / m 2 , the coating becomes non-uniform and sticking resistance and boiling water vapor exposure are deteriorated.
If it exceeds g / m 2 , the film will swell during drying at low temperature and the appearance of the film will be impaired. Here, as a coating method of such a treatment liquid for an insulating film, a roll coater method, a flow coater method, a spray coating, a knife coater, and the like, which are conventionally generally used, can be used. In addition, as for the baking method, a hot-air method which is usually practiced industrially is advantageously applied. EXAMPLE A phosphoric acid solution was applied to the surface of a 0.5 mm thick electromagnetic steel sheet.
(H 3 PO 4 concentration: 2 mass%), phosphoric acid pickling treatment at a liquid temperature of 30 ° C., followed by drying treatment at 80 ° C. for 50 seconds to form a phosphate compound film having a thickness of 20 nm on a steel plate. Aqueous solution containing epoxy resin and colloidal silica (resin solid content: 2 mass%, silica content: 2 ma)
ss%) of the treatment solution for insulating coating with a roll coater,
Heating rate: 7.0 ° C / s, Ultimate plate temperature: 200 ° C, Heating time: 1
Then, it was baked under the conditions of minutes to produce an electrical steel sheet with an insulating coating (inventive example). Further, for comparison, an electrical steel sheet with an insulating coating (comparative example) was manufactured in the same manner as in the inventive example, except that the heating rate was 10 ° C./s as in the prior art. When the appearance of each of the thus obtained magnetic steel sheets provided with an insulating coating was examined, the comparative example showed that about 20%
No white pattern was generated in the inventive examples. As described above, according to the present invention, when an insulating film containing no chromium is formed by low-temperature baking, the occurrence of a white pattern, which has been a concern in the past, is completely prevented, and the film appearance and peeling resistance are prevented. An electromagnetic steel sheet with an insulating coating having excellent properties can be stably obtained.
【図面の簡単な説明】
【図１】 白色模様の発生に及ぼす昇温速度と焼付到達
板温との関係を示す図である。
【図２】 本発明に従う、絶縁被膜の塗装工程を示す模
式図である。
【符号の説明】
１ 絶縁被膜の塗装装置
２ 熱風炉による塗液焼付け設備
３ 鋼板の冷却設備BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the relationship between the temperature increase rate and the temperature of a plate that has reached seizure on the occurrence of a white pattern. FIG. 2 is a schematic view showing a step of coating an insulating film according to the present invention. [Description of Signs] 1 Insulation coating equipment 2 Coating liquid baking equipment with hot blast stove 3 Steel plate cooling equipment
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 4K026 AA03 BA03 BB10 CA23 CA26 CA37 CA41 DA02 DA03 DA11 EB11 ────────────────────────────────────────────────── ─── Continuation of front page F term (reference) 4K026 AA03 BA03 BB10 CA23 CA26 CA37 CA41 DA02 DA03 DA11 EB11
Claims (1)
い絶縁被膜を、低温焼付けによって被成することからな
る電磁鋼板の製造方法において、 絶縁被膜の塗装処理に先立ち、りん酸酸洗処理および乾
燥処理を施して、鋼板の表面にりん酸化合物被膜を形成
し、ついで絶縁被膜用処理液を塗装したのち、その焼付
けを行うに際し、昇温速度と到達板温が下記の関係を満
足する条件下で焼付け処理を行うことを特徴とする被膜
外観に優れた絶縁被膜付き電磁鋼板の製造方法。 記 ｙ≦0.0355・Ｔ ここで、ｙ：昇温速度（℃/s） Ｔ：到達板温（℃）Claims: 1. A method for manufacturing an electromagnetic steel sheet, comprising forming an insulating coating containing no hexavalent chromium on a surface of the magnetic steel sheet by low-temperature baking, wherein prior to coating the insulating coating. After performing a phosphoric acid pickling treatment and a drying treatment, a phosphate compound film is formed on the surface of the steel sheet, and then a coating solution for an insulating film is applied. A method for producing a magnetic steel sheet with an insulating coating having an excellent coating appearance, wherein baking is performed under conditions satisfying the following relationship. Note that y ≦ 0.0355 · T where y: heating rate (° C./s) T: ultimate plate temperature (° C.)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001388647A JP2003193252A (en) | 2001-12-21 | 2001-12-21 | Method of producing silicon steel sheet with insulating film having excellent film appearance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001388647A JP2003193252A (en) | 2001-12-21 | 2001-12-21 | Method of producing silicon steel sheet with insulating film having excellent film appearance |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2003193252A true JP2003193252A (en) | 2003-07-09 |
Family
ID=27597086
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001388647A Pending JP2003193252A (en) | 2001-12-21 | 2001-12-21 | Method of producing silicon steel sheet with insulating film having excellent film appearance |
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| JP (1) | JP2003193252A (en) |
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| JP2005187924A (en) * | 2003-12-26 | 2005-07-14 | Jfe Steel Kk | Method for depositing chromium-free insulation film for grain-oriented electrical steel sheet |
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