JP3778791B2 - Pre-painting method and molded product - Google Patents
Pre-painting method and molded product Download PDFInfo
- Publication number
- JP3778791B2 JP3778791B2 JP2000338630A JP2000338630A JP3778791B2 JP 3778791 B2 JP3778791 B2 JP 3778791B2 JP 2000338630 A JP2000338630 A JP 2000338630A JP 2000338630 A JP2000338630 A JP 2000338630A JP 3778791 B2 JP3778791 B2 JP 3778791B2
- Authority
- JP
- Japan
- Prior art keywords
- washing
- water
- chemical conversion
- coating
- treatment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Description
【０００１】
【発明の属する技術分野】
本発明は、金属成形物の塗装前処理方法に関し、更に詳しくは、リン酸亜鉛皮膜で被覆された亜鉛系メッキ鋼板を板金構成体とする金属成形物の電着塗装前処理方法に関する。
【０００２】
【従来の技術】
一般的に、自動車等の金属成形物は、自動車メーカー等において、電気亜鉛系メッキ鋼板を自動車車体に成形、プレス溶接し、車体の凹凸部を砥石で削る等の成形検査が行われて、脱脂、水洗、表面調整、リン酸亜鉛皮膜化成処理、及び、化成後水洗という一連の塗装前処理工程が行われた後、電着塗装されている。
【０００３】
従来は、自動車メーカーに搬入される電気亜鉛系メッキ鋼板は、良好な成形性を保つために、潤滑油塗布、巻取等の処理が行われたものであった。
しかしながら、近年では、電気亜鉛系メッキ鋼板の経時的酸化を防止したり、プレス成形性等を向上させる観点から、予めリン酸亜鉛皮膜で被覆した電気亜鉛系メッキ鋼板が搬入されるようになってきた。
【０００４】
特開平８−６７９８９号公報には、亜鉛系メッキ鋼板の一方の面に付着量０．０５〜０．５ｇ／ｍ2 からなるリン酸塩結晶皮膜が分散して存在し、他方の面に付着量０．５〜３．０ｇ／ｍ2 のリン酸塩皮膜が形成された自動車用防錆鋼板が開示されている。これは、付着量０．５〜３．０ｇ／ｍ2 のリン酸塩皮膜が形成された面を合わせ部となる面とし、付着量０．０５〜０．５ｇ／ｍ2 のリン酸塩結晶皮膜が分散して存在する面を自動車の車体部位となる面とすることによって、合わせ部耐食性、塗装性、溶接性に優れた防錆鋼板を提供するものである。
【０００５】
しかしながら、成形、プレス溶接された後に車体の凹凸部を砥石で削る等の成形検査が行われると、予めリン酸亜鉛皮膜で被覆された電気亜鉛系メッキ鋼板は、その後塗装前処理を経て電着塗装が行われた場合、砥石で削られた部分と削られなかった部分の間に大きな電気抵抗差が生じて、電着塗膜表面が不均一になり、塗膜外観に劣るという問題点があった。砥石で削られた部分は、塗装前処理工程にて新たにリン酸亜鉛皮膜が形成され補修されるものの、電気抵抗の不均一を完全に解消するまでには至らなかった。特に、電着塗装後に砥石で削られた部分が凹状の傷跡になる場合、その部分の補修が困難で、傷が目立つという問題があった。
【０００６】
【発明が解決しようとする課題】
本発明の目的は、電着塗装した場合に、塗膜表面が均一であって、良好な外観が得られるリン酸塩皮膜で被覆された金属成形物の電着塗装前処理方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明は、皮膜量０．１〜２ｇ／ｍ２のリン酸塩皮膜で被覆された亜鉛系メッキ鋼板を成形し、上記成形物をリン酸塩皮膜化成処理する工程及び化成後水洗する工程を含む処理工程によって処理を行うことからなる電着塗装前処理方法であって、上記化成後水洗における水洗液に、塩基性化合物又はその水溶液を添加することによって、上記水洗液のｐＨを４〜７の範囲に制御することを特徴とする電着塗装前処理方法である。
以下、本発明を詳述する。
【０００８】
本発明者らは、化成後水洗工程において使用される水洗液のｐＨは、その前工程であるリン酸塩皮膜化成処理液の持ち込みがあるため、通常３程度であるが、この場合には、リン酸塩皮膜が酸溶解する皮膜減量が大きいため、リン酸塩皮膜の膜厚の差が砥石で削られた部分とそれ以外の部分との間で大きくなり、その結果、電着塗装後の塗膜表面が不均一になることがわかった。一方、化成後水洗工程において使用される水洗液のｐＨを中性に近いｐＨ４〜７になるように制御した場合には、リン酸塩皮膜の酸溶解が抑制され、砥石で削られた部分と削っていない部分とのリン酸塩皮膜の膜厚の差が小さく、電着塗装を行っても、塗膜表面が均一になることを見出し、本発明を完成した。
【０００９】
即ち、本発明の塗装前処理方法において、化成後水洗における水洗液のｐＨは、４〜７の範囲に制御されるものである。ｐＨ４未満では、リン酸塩皮膜が酸溶解していく皮膜減量が大きいため、砥石で削られた部分と削っていない部分とのリン酸塩皮膜の膜厚の差が大きくなり、その結果、電着塗装した場合に塗膜表面が不均一となる。ｐＨ７を超えても、上記範囲内で得られる以上の効果もなく、７を超えるｐＨに制御するための塩基性化合物の添加量が多くなり不経済である。好ましくは、ｐＨ５〜７の範囲であり、より好ましくは、ｐＨ５．５〜６．５の範囲である。
【００１０】
上記化成後水洗における水洗液については、上記のように、通常ｐＨ３程度であるが、ｐＨ４〜７の範囲に制御するために、化成液が付着する被処理物を浸漬、噴霧等の方法で大量の清浄水で洗浄し、被処理物と接液する水洗水のｐＨを４〜７に制御する方法か、若しくは、上記水溶液に塩基性化合物又はその水溶液を添加して、水洗液ｐＨを４〜７に制御する方法が好適である。上記塩基性化合物又はその水溶液としては特に限定されず、例えば、水酸化ナトリウム、水酸化カリウム及びそれらの水溶液、アンモニア水等を挙げることができる。塩基性化合物等の添加を不要とする方法では、水洗槽内液のｐＨを４〜７に制御するために、化成工程直後に被処理物の一部又は全部を清浄水で洗浄し、その処理水を次の水洗工程での供給原水とせずに、そのまま廃棄する方法等を採用してよい。
【００１１】
本発明の塗装前処理方法は、リン酸塩皮膜で被覆された亜鉛系メッキ鋼板を成形し、上記成形物をリン酸塩皮膜化成処理する工程及び化成後水洗する工程を含む処理工程によって処理を行うことからなるものである。
上記亜鉛系メッキ鋼板に使用される下地鋼板は特に限定されず、例えば、通常の自動車用の鋼板である軟鋼板、高張力鋼板、深絞り鋼板、耐食鋼板、表面改質処理を施した鋼板等を挙げることができる。また、鋼板の両面に施す亜鉛系めっきは、常法に従って行ない、溶融めっき、電気めっきのいずれでも可能である。めっき皮膜の種類も特に限定されず、例えば、亜鉛めっき；亜鉛−鉄、亜鉛−ニッケル、亜鉛−クロム、亜鉛−マンガンなどの合金めっき；亜鉛−ＳｉＯ2 、亜鉛Ｃｒ2 Ｏ3 等の分散めっき等を挙げることができる。
【００１２】
上記亜鉛系メッキ鋼板は、必要により予め、アルカリ脱脂洗浄液、無リン・無窒素脱脂洗浄液等の脱脂；その後の洗浄；及び表面調整を行うことができる。上記脱脂、その後の洗浄及び表面調整については、従来の方法に従って行うことができる。
次に、リン酸塩皮膜化成処理〔１〕が行われる。上記リン酸塩処理液は、通常のリン酸亜鉛を主成分とするものであり、カチオン成分として、亜鉛以外にＮｉ2+、Ｍｇ2+、Ｃｏ2+、Ｃｕ2+、Ｍｎ2+、Ｃａ+ 、Ｎａ2+、Ｆｅ2+、ＮＨ4 + 、Ｈ+ 、アニオン成分として、ＰＯ4 3- 、ＮＯ3 - 、ＮＯ2 - 、Ｆ- 、ＳｉＦ6 2- 、ＣｌＯ3 - 、ＳＯ4 2- 等が含まれていてもよい。また、一部有機酸等を含むこともできる。
【００１３】
上記リン酸塩皮膜化成処理〔１〕によるリン酸亜鉛皮膜の皮膜量は、０．１〜２ｇ／ｍ2 である。０．１ｇ／ｍ2 未満では、皮膜量が少ないので、プレス成形性及び防錆性が不充分となる。２ｇ／ｍ2 を超えると、溶接性が不充分となる。好ましくは、１〜２ｇ／ｍ2 である。また、亜鉛系メッキ鋼板のうち、合わせ部の対象となる面は、耐食性が要求されることから、０．５〜１．５ｇ／ｍ2 であることが好ましい。
【００１４】
上記リン酸塩皮膜化成処理〔１〕を施された亜鉛系メッキ鋼板は、目的とする成形物に成形、プレス溶接され、成形物の凹凸部を砥石で削る等の成形検査が行われる。
上記成形物は、その後、脱脂、水洗、表面調整、リン酸塩皮膜化成処理〔２〕、及び、化成後水洗、更に、必要に応じて乾燥され、その後、電着塗装される。
【００１５】
上記成形後に行われる脱脂、水洗、表面調整、及び、リン酸塩皮膜化成処理〔２〕は、成形前に亜鉛系メッキ鋼板に対して行われるものと同じ条件であってもよい。但し、上記リン酸塩皮膜化成処理〔１〕は防錆性、プレス成形性及び溶接性といった成形時並びに成形前の性能を確保するために行うものであるのに対して、上記リン酸塩皮膜化成処理〔２〕は塗装後の成形物として高度な耐食性を確保するために行うという相違点から、リン酸塩皮膜化成処理〔２〕の方が長時間行うことが好ましい。処理時間は、化成処理液の濃度及び処理温度にもよるが、通常、リン酸塩皮膜化成処理〔１〕においては１〜３０秒、リン酸塩皮膜化成処理〔２〕においては３０秒〜５分程度である。
【００１６】
上記リン酸塩皮膜化成処理〔２〕が行われた後、化成後水洗が行われる。本発明においては、この水洗液のｐＨを４〜７の範囲に制御する必要がある。
上記化成後水洗においては、スプレー水洗又は浸漬水洗のどちらでもよく、これらの方法を組み合わせて水洗することもできるが、化成後水洗が不充分であるとその後の電着塗装において塗膜外観等に悪影響を及ぼすことから、数段水洗することが好ましく、最終の水洗は、純水で行うことが適当である。数段水洗する場合には、そのいずれの水洗水もｐＨ４〜７の範囲に制御する必要がある。
本発明においては、常にｐＨ４〜７の範囲に制御する必要性から、水洗水の一部を定期的にサンプリングする自動制御による方法が好ましい。
上記化成後水洗の後は、公知の方法に従って、必要に応じて乾燥され、その後、電着塗装を行うことができる。
【００１７】
本発明の塗装前処理方法は、プレ処理鋼板のリン酸亜鉛皮膜の皮膜量が０．１〜２ｇ／ｍ2 であるため、防錆性、プレス成形性及び溶接性に優れ、更に、化成後水洗における水洗液のｐＨが４〜７の範囲に制御されるので、電着塗装した後の電着皮膜の膜厚が均一で、その表面に凹状の傷跡が生じにくい。
【００１８】
【発明の実施の形態】
上記リン酸塩皮膜化成処理〔２〕が行われた後の化成後水洗においては、通常、効果的に洗浄するために、多段式スプレー洗浄及び浸漬洗浄を組み合わせて行い、最終洗浄は純水により行われるが、全使用水量及び廃棄水量の削減の点から、各処理後の液は、それぞれその前段階の水洗工程における水洗水として使用される。
【００１９】
図１は、化成後水洗槽のｐＨ制御フローシートである。これは、スプレー水洗、浸漬水洗、スプレー水洗の順で化成後水洗が行われる。
まず、成形物は、入槽スプレー１でスプレー水洗が行われるが、この処理前液として、浸漬水洗槽２中の水洗液がスプレーポンプ３を介して供給される。次いで、成形物は、浸漬水洗槽２に浸漬され、成形物の内部及び袋構造部分が効果的に洗浄される。浸漬水洗槽２には、ｐＨ計４を介してｐＨコントローラー５が接続されている。ｐＨコントローラー５は、浸漬水洗槽２の水洗液のｐＨが４〜７の範囲となるようにモニターされ、薬液タンク６から薬液ポンプ７によって塩基性水溶液が浸漬水洗槽２に適宜追加されるとともに、スプレーポンプ３にスプレーポンプＯＮ−ＯＦＦ信号が出される。その後、成形物は、出槽スプレー８でスプレー水洗が行われるが、この処理後液は、浸漬水洗槽２に供給される。なお、出槽スプレー８で使用される水洗液としては、純水を使用することができる。
図１に示したようなｐＨを自動制御する方法によって、化成後水洗における水洗水のｐＨを一定に保ち、かつ、数段水洗する場合、そのいずれの水洗水もｐＨ４〜７の範囲に制御することができる。
【００２０】
【実施例】
以下に実施例を掲げて本発明を更に詳しく説明するが、本発明はこれら実施例のみに限定されるものではない。
実施例１
（１）プレ皮膜処理
市販の電気亜鉛メッキ鋼板（新日本製鐵社製ジンコート、無処理；目付量３０／３０；０．０７ｃｍ×７ｃｍ×１５ｃｍ）を下記の工程条件でプレ皮膜処理を施した。そのうち、化成処理工程においては、表１に示すように接液時間を変えた処理ａ〜ｄを行った。
脱脂：サーフクリーナーＳＤ２８０ＭＺ処理（日本ペイント社製脱脂剤） ４０℃１２０秒流動浸漬
水洗：水道水 流水洗 １０秒接液
表面調整：サーフファイン５ＭＺ−１（日本ペイント社製表面調整剤） ２０℃１０秒流動浸漬
化成処理：サーフダインＳＤ２５００ＭＺＬ（日本ペイント社製化成処理剤） ４０℃ 流動浸漬
水洗：純水 流水洗 １０秒接液
上記処理ａ〜ｄをそれぞれ行った後の亜鉛メッキ鋼板の重量と、処理後の亜鉛メッキ鋼板を無水クロム酸５重量％溶液に２０〜２５℃×５分間浸漬してプレ皮膜を溶解し、水洗次いで乾燥した後の重量とを測定し、その重量差を単位面積当たりに換算したものを皮膜量として表１に示した。
【００２１】
【表１】
（２）塗装前処理
上記４種のプレ皮膜処理（１）された電気亜鉛メッキ鋼板に、線状の砥石傷を入れた。これは、実際の自動車車体成形後の成形検査を想定したものである。
その後、自動車塗装前処理ラインを想定した下記の塗装前処理工程条件で処理した。
脱脂：上記プレ皮膜処理（１）における脱脂工程と同じ方法
第１水洗：上記脱脂液の１０倍希釈濃度液で流動水洗 １０秒接液
第２水洗：上記脱脂液の１００倍希釈濃度液で流動水洗 ４０℃１２０秒流動浸漬
表面調整：上記プレ皮膜処理（１）における表面調整工程と同じ方法
化成処理：上記プレ皮膜処理（１）における化成処理工程と同じ方法 但し接液条件は４０℃で１２０秒一定の流動浸漬
化成後第３水洗：水酸化ナトリウムによってｐＨ６．０に制御した水洗液で水洗１０秒接液
化成後第４水洗：水酸化ナトリウムによってｐＨ６．０に制御した水洗液で水洗１０秒接液
純水第５水洗：純水による流水洗 １０秒接液
【００２３】
（３）カチオン電着塗装
上記の塗装前処理（２）を施したプレ処理鋼板を電着塗装した。
塗装条件：パワートップＶ−２０（当社製カチオン型電着塗装） ２００Ｖ×３０秒昇圧 塗料液温３２℃
塗装前処理（２）を行った後の処理鋼板とプレ皮膜処理（１）を行う前の亜鉛メッキ鋼板の重量の差を測定し、単位面積当たりに換算した値を水洗後の皮膜量として表２に示した。
【００２４】
評価
１．プレ皮膜処理（１）を行った電気亜鉛メッキ鋼板について、下記のようにして溶接性及び成形性を評価した。結果を表１に示した。
溶接性
先端径４．５ｍｍのＣｕ−Ｃｒ合金系電極チップ（ＣＦ型）を用い、以下の条件で溶接を行った。
スクイズタイム：３０サイクル
溶接時間：１３サイクル
保持時間：２サイクル
加圧力：２５０ｋｇｆ
この条件で溶接電流を０．３ｋＡ刻みで変化させ、基準ナゲット径（４×（板厚）1/2 ）を形成できる最低電流値と内チリの発生する電流値との範囲（適正電流範囲）を求めた。適正電流範囲が１ｋＡ以上を良好と評価した。
【００２５】
成形性
平板引き抜きによる動摩擦係数を評価した。３０ｍｍ幅サンプルに防錆油（パーカー興産製ノックスラスト５３０）を１．５ｇ／ｍ2 塗油し、５００ｋｇｆの圧着荷重で、２００ｍｍ／分の速度で引き抜き、引き抜き力から動摩擦係数を算出した。動摩擦係数が０．１２以下を良好と評価した。
２．カチオン電着塗装（３）を行った電気亜鉛メッキ鋼板について、砥石傷跡を含めた部位で塗装均一性を目視により評価した。結果を表２に示した。
【００２６】
比較例１
上記塗装前処理（２）において、化成後第３水洗及び化成後第４水洗の水酸化ナトリウムによるｐＨ制御を行わなかったこと以外は、実施例１と同様に処理した。このときのｐＨは３．８であった。結果を表２に示した。
【００２７】
【表２】
実施例２
実施例１の塗装前処理（２）において化成後第３水洗及び化成後第４水洗の水洗液のｐＨを表３のように変えたこと以外は、実施例１と同様にして処理した。水洗液のｐＨは、水酸化ナトリウム又はリン酸を用いて調整した。目視による塗装均一性の評価結果を表３に示した。
【００２９】
【表３】
表２及び表３の結果より、水洗液のｐＨを４〜７に制御した場合には、電着塗装した塗膜表面は砥石傷跡部分でもそれ以外の部分と均一であった。一方、ｐＨ制御を行わなかった比較例１及び水洗液のｐＨが４未満の場合には、電着塗膜表面が砥石傷跡部分において凹状となり、均一ではなかった。
【００３１】
【発明の効果】
本発明の塗装前処理方法は、上述の構成よりなるので、電着塗装した後の電着皮膜表面が均一なものが得られる。
【図面の簡単な説明】
【図１】化成後水洗槽のｐＨ制御フローシートの１例である。
【符号の説明】
１ 入槽スプレー
２ 浸漬水洗槽
３ スプレーポンプ
４ ｐＨ計
５ ｐＨコントローラー
６ 薬液タンク
７ 薬液ポンプ
８ 出槽スプレー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pretreatment method for coating a metal molded product, and more particularly to a pretreatment method for electrodeposition coating of a metal molded product using a zinc-based plated steel sheet coated with a zinc phosphate coating as a sheet metal component.
[0002]
[Prior art]
In general, metal moldings such as automobiles are degreased by automobile manufacturers, etc. after forming and inspecting electrogalvanized steel sheets on automobile bodies, press welding, and shaving uneven parts of the bodies with a grindstone. After a series of pre-painting treatment steps of water washing, surface conditioning, zinc phosphate film chemical conversion treatment, and post-chemical conversion water washing, electrodeposition coating is performed.
[0003]
Conventionally, electrogalvanized steel sheets carried into automobile manufacturers have been subjected to treatments such as lubricating oil coating and winding in order to maintain good formability.
However, in recent years, an electrogalvanized steel sheet that has been previously coated with a zinc phosphate film has been brought in from the viewpoint of preventing the time-dependent oxidation of the electrogalvanized steel sheet or improving the press formability. It was.
[0004]
In JP-A-8-67989, a phosphate crystal film consisting of 0.05 to 0.5 g / m 2 is dispersed on one surface of a galvanized steel sheet and adhered to the other surface. An automobile rust-proof steel sheet in which a phosphate film having an amount of 0.5 to 3.0 g / m 2 is formed is disclosed. This is because the surface on which the phosphate film having an adhesion amount of 0.5 to 3.0 g / m 2 is formed is the surface to be a joint portion, and the phosphate crystal having an adhesion amount of 0.05 to 0.5 g / m 2 By providing the surface in which the film is dispersed as a surface to be a vehicle body part of an automobile, a rust-proof steel sheet excellent in mating portion corrosion resistance, paintability, and weldability is provided.
[0005]
However, after forming and press-welding, if molding inspection such as shaving the uneven parts of the car body with a grindstone is performed, the electrogalvanized steel sheet coated with a zinc phosphate film in advance will be subjected to electrodeposition after painting pretreatment. When painting is performed, there is a problem that a large electrical resistance difference occurs between the part that has been shaved with the grindstone and the part that has not been shaved, resulting in a non-uniform surface of the electrodeposited coating film and poor coating appearance. there were. Although the zinc phosphate film was newly formed and repaired in the pre-painting process, the portion cut with the grindstone did not completely eliminate the uneven electrical resistance. In particular, when a portion cut by a grindstone after electrodeposition coating becomes a concave scar, it is difficult to repair that portion, and there is a problem that the scratch is conspicuous.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for pretreatment of electrodeposition coating of a metal molded article coated with a phosphate film that has a uniform coating surface and can provide a good appearance when electrodeposition coating is performed. It is in.
[0007]
[Means for Solving the Problems]
The present invention includes forming a zinc-based plated steel sheet coated with a phosphate film having a film amount of 0.1 to 2 g / m 2 , and subjecting the molded product to a phosphate film chemical conversion treatment and a process of washing with water after chemical conversion. An electrodeposition coating pretreatment method comprising performing a treatment by a treatment step comprising adding a basic compound or an aqueous solution thereof to the washing solution in the washing after the chemical conversion to adjust the pH of the washing solution to 4-7. It is the electrodeposition coating pretreatment method characterized by controlling to the range.
The present invention is described in detail below.
[0008]
The inventors of the present invention have a pH of the washing solution used in the post-chemical conversion rinsing step, which is usually about 3 because there is a phosphate film chemical conversion treatment solution that is the previous step. Because the film weight loss of the phosphate film that dissolves in the acid is large, the difference in the film thickness of the phosphate film becomes large between the part that was shaved with the grindstone and the other parts. It was found that the coating surface was uneven. On the other hand, when the pH of the water washing solution used in the post-chemical conversion water washing step is controlled to be
[0009]
That is, in the pre-coating treatment method of the present invention, the pH of the water washing liquid in the post-chemical conversion water washing is controlled in the range of 4-7. If the pH is less than 4, the film weight loss by which the phosphate film dissolves in the acid is large, and therefore the difference in the film thickness of the phosphate film between the part that is shaved with the grindstone and the part that is not shaved increases. When coated, the coating surface becomes uneven. Even if it exceeds pH 7, there is no effect more than that obtained within the above range, and the amount of the basic compound added to control the pH exceeding 7 is increased, which is uneconomical. Preferably, it is the range of pH 5-7, More preferably, it is the range of pH 5.5-6.5.
[0010]
As described above, the washing water in the post-chemical conversion water washing is usually about pH 3. However, in order to control the pH within a range of 4 to 7, a large amount of the treatment object to which the chemical formation liquid adheres is immersed or sprayed. Or a method of controlling the pH of washing water in contact with the object to be treated to 4 to 7, or adding a basic compound or an aqueous solution thereof to the aqueous solution to adjust the washing solution pH to 4 to 4. The method of controlling to 7 is suitable. It does not specifically limit as said basic compound or its aqueous solution, For example, sodium hydroxide, potassium hydroxide and those aqueous solution, ammonia water, etc. can be mentioned. In a method that does not require the addition of a basic compound or the like, in order to control the pH of the solution in the washing tank to 4 to 7, a part or all of the object to be treated is washed with clean water immediately after the chemical conversion step, and the treatment is performed. You may employ | adopt the method etc. which discard water as it is, without making water into the supply raw water in the next washing process.
[0011]
The pre-painting treatment method of the present invention forms a galvanized steel sheet coated with a phosphate film, and performs the treatment by a treatment process including a step of subjecting the molded product to a phosphate film chemical conversion treatment and a step of washing with water after chemical conversion. Is to do.
The base steel plate used for the galvanized steel sheet is not particularly limited. For example, a mild steel sheet, a high-tensile steel sheet, a deep-drawn steel sheet, a corrosion-resistant steel sheet, a steel sheet subjected to surface modification treatment, etc. Can be mentioned. Moreover, the zinc-based plating applied to both surfaces of the steel plate is performed according to a conventional method, and can be either hot dipping or electroplating. The type of the plating film is not particularly limited, for example, zinc plating; alloy plating such as zinc-iron, zinc-nickel, zinc-chromium, zinc-manganese; dispersion plating such as zinc-SiO 2 , zinc Cr 2 O 3, etc. Can be mentioned.
[0012]
The galvanized steel sheet may be subjected to degreasing such as an alkaline degreasing cleaning liquid, phosphorus-free / nitrogen-free degreasing cleaning liquid; subsequent cleaning; and surface adjustment as necessary. About the said degreasing | defatting, subsequent washing | cleaning, and surface adjustment, it can carry out according to the conventional method.
Next, phosphate film chemical conversion treatment [1] is performed. The phosphating solution is mainly composed of normal zinc phosphate, and as a cation component, in addition to zinc, Ni 2+ , Mg 2+ , Co 2+ , Cu 2+ , Mn 2+ , Ca + , Na 2+ , Fe 2+ , NH 4 + , H + , as anion components, PO 4 3− , NO 3 − , NO 2 − , F − , SiF 6 2− , ClO 3 − , SO 4 2− Etc. may be included. Moreover, some organic acids etc. can also be included.
[0013]
The coating amount of the zinc phosphate coating by the phosphate coating conversion treatment [1] is 0.1 to 2 g / m 2 . If it is less than 0.1 g / m 2 , the amount of film is small, so that the press moldability and rust prevention properties are insufficient. If it exceeds 2 g / m 2 , the weldability becomes insufficient. Preferably, a 1 to 2 g / m 2. Moreover, since the corrosion resistance is requested | required, the surface used as the object of a matching part among zinc-based plated steel plates is preferably 0.5 to 1.5 g / m 2 .
[0014]
The zinc-based plated steel sheet that has been subjected to the phosphate film chemical conversion treatment [1] is molded and press-welded to a target molded product, and a molding inspection is performed such as shaving the uneven portions of the molded product with a grindstone.
Thereafter, the molded product is degreased, washed with water, surface-adjusted, phosphate film chemical treatment [2], washed with water after chemical conversion, dried as necessary, and then electrodeposited.
[0015]
The degreasing, washing, surface adjustment, and phosphate film chemical conversion treatment [2] performed after the forming may be performed under the same conditions as those performed on the galvanized steel sheet before forming. However, the phosphate film chemical conversion treatment [1] is performed to ensure the performance before molding and before molding such as rust prevention, press formability and weldability, whereas the phosphate film From the difference that the chemical conversion treatment [2] is performed in order to ensure high corrosion resistance as a molded product after coating, the phosphate film chemical conversion treatment [2] is preferably performed for a longer time. The treatment time depends on the concentration of the chemical conversion treatment solution and the treatment temperature, but is usually 1 to 30 seconds in the phosphate film chemical treatment [1] and 30 seconds to 5 in the phosphate film chemical treatment [2]. About minutes.
[0016]
After the phosphate film chemical conversion treatment [2] is performed, water washing is performed after chemical conversion. In the present invention, it is necessary to control the pH of this washing solution in the range of 4-7.
In the post-chemical conversion water washing, either spray water washing or immersion water washing may be used, and these methods may be combined and water washing may be performed. In order to have an adverse effect, it is preferable to wash with several stages, and it is appropriate to carry out the final washing with pure water. In the case of washing with several stages, it is necessary to control any washing water within a pH range of 4-7.
In the present invention, since it is necessary to always control the pH in the range of 4 to 7, an automatic control method that periodically samples a part of the washing water is preferable.
After the above chemical conversion and water washing, it is dried as necessary according to a known method, and then electrodeposition coating can be performed.
[0017]
The coating pretreatment method of the present invention is excellent in rust prevention, press formability and weldability because the coating amount of the zinc phosphate coating on the pretreated steel sheet is 0.1 to 2 g / m 2. Since the pH of the water washing solution in the water washing is controlled in the range of 4 to 7, the film thickness of the electrodeposition film after the electrodeposition coating is uniform, and concave scars are not easily generated on the surface.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
In the post-formation water washing after the phosphate film chemical conversion treatment [2] is performed, in order to effectively wash, the multi-stage spray washing and the immersion washing are usually combined, and the final washing is performed with pure water. Although it is carried out, from the viewpoint of reducing the total amount of water used and the amount of waste water, the liquid after each treatment is used as washing water in the previous washing step.
[0019]
FIG. 1 is a pH control flow sheet of a water tank after chemical conversion. This is performed after chemical conversion in the order of spray water washing, immersion water washing, and spray water washing.
First, the molded product is rinsed with an in-vessel spray 1, and as a pre-treatment solution, a rinse solution in the immersion rinse
By the method of automatically controlling the pH as shown in FIG. 1, when the pH of the washing water in the washing after the chemical conversion is kept constant, and when washing with several stages, the washing water is controlled in the range of pH 4-7. be able to.
[0020]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.
Example 1
(1) Pre-coating treatment A commercially available electrogalvanized steel sheet (Shin Nippon Steel Co., Ltd. gin coat, untreated; basis weight 30/30; 0.07 cm × 7 cm × 15 cm) was subjected to pre-coating treatment under the following process conditions. . Among them, in the chemical conversion treatment step, as shown in Table 1, treatments a to d with different liquid contact times were performed.
Degreasing: Surf cleaner SD280MZ treatment (Degreasing agent manufactured by Nippon Paint Co., Ltd.) 40 ° C. 120 seconds Fluid immersion water washing: Tap water Flowing water washing 10 seconds Liquid contact surface adjustment: Surffine 5MZ-1 (Nippon Paint Co., Ltd. surface conditioning agent) 20 ° C. 10 Second fluid immersion chemical conversion treatment: Surfdyne SD2500MZL (Chemical conversion treatment agent manufactured by Nippon Paint Co., Ltd.) 40 ° C. Fluid immersion water washing: Pure water Flowing water washing 10 seconds Liquid contact The weight of the galvanized steel sheet after each of the above treatments a to d, The treated galvanized steel sheet is immersed in a 5% by weight solution of chromic anhydride at 20 to 25 ° C. for 5 minutes to dissolve the pre-coating, washed with water and then dried, and the weight difference per unit area is measured. Table 1 shows the amount converted to the film thickness.
[0021]
[Table 1]
(2) Pre-coating treatment Linear whetstone scratches were placed on the above-mentioned four types of pre-coating (1) electrogalvanized steel sheets. This assumes the molding inspection after the actual automobile body molding.
Then, it processed on the following coating pre-processing process conditions supposing the automobile coating pre-processing line.
Degreasing: The same method as the degreasing step in the pre-film treatment (1) First water washing: Fluid water washing with a 10-fold diluted concentration liquid of the degreasing liquid Second liquid washing for 10 seconds: Fluid flow with a 100-fold diluted concentration liquid of the degreasing liquid Washing at 40 ° C. for 120 seconds Flow immersion surface adjustment: Same method as the surface adjustment step in the pre-coating treatment (1) Chemical conversion treatment: Same method as the chemical conversion treatment step in the pre-coating treatment (1) However, the wetted condition is 120 at 40 ° C. 3rd water washing after fluid dipping for 2 seconds: water washing with pH 6.0 controlled by sodium hydroxide 10 seconds water washing after water contact formation for 4 seconds: water washing with water washing pH adjusted to 6.0 with sodium hydroxide 10 Second wetted pure water 5th water wash: Washing with pure water 10 seconds wetted liquid [0023]
(3) Cationic electrodeposition coating The pre-treated steel sheet subjected to the coating pretreatment (2) was electrodeposited.
Painting conditions: Power Top V-20 (our company's cationic electrodeposition coating) 200V x 30 seconds pressure increase paint liquid temperature 32 ° C
The difference between the weight of the treated steel sheet after pre-coating treatment (2) and the galvanized steel sheet before pre-coating treatment (1) was measured, and the value converted per unit area was expressed as the amount of film after water washing. It was shown in 2.
[0024]
Evaluation 1. About the electrogalvanized steel plate which performed the pre membrane | film | coat process (1), weldability and formability were evaluated as follows. The results are shown in Table 1.
Weldability Using a Cu-Cr alloy-based electrode tip (CF type) with a tip diameter of 4.5 mm, welding was performed under the following conditions.
Squeeze time: 30 cycles Welding time: 13 cycles Holding time: 2 cycles Applied pressure: 250 kgf
Under this condition, the welding current is changed in increments of 0.3 kA, and the range between the minimum current value that can form the standard nugget diameter (4 x (plate thickness) 1/2 ) and the current value that generates internal dust (appropriate current range) Asked. An appropriate current range of 1 kA or higher was evaluated as good.
[0025]
It was evaluated dynamic friction coefficient due moldability <br/> flat withdrawal. A 30 mm width sample was coated with 1.5 g / m 2 of rust-preventing oil (Parker Kosan Knoxlast 530), extracted at a speed of 200 mm / min with a pressure load of 500 kgf, and the dynamic friction coefficient was calculated from the pulling force. A dynamic friction coefficient of 0.12 or less was evaluated as good.
2. About the electrogalvanized steel sheet which performed cation electrodeposition coating (3), the coating uniformity was visually evaluated in the site | part including the grindstone scar. The results are shown in Table 2.
[0026]
Comparative Example 1
In the coating pretreatment (2), the treatment was performed in the same manner as in Example 1 except that the pH was not controlled by sodium hydroxide in the third and fourth water washings after the chemical conversion. The pH at this time was 3.8. The results are shown in Table 2.
[0027]
[Table 2]
Example 2
The treatment was performed in the same manner as in Example 1 except that in the pre-coating treatment (2) of Example 1, the pH of the washing water in the third water wash after conversion and the fourth water wash after conversion was changed as shown in Table 3. The pH of the washing water was adjusted using sodium hydroxide or phosphoric acid. Table 3 shows the results of visual evaluation of coating uniformity.
[0029]
[Table 3]
From the results shown in Tables 2 and 3, when the pH of the washing solution was controlled to 4 to 7, the surface of the coating film subjected to electrodeposition coating was uniform with the other parts even at the grindstone scar. On the other hand, when the pH of Comparative Example 1 in which pH control was not performed and the washing solution was less than 4, the surface of the electrodeposition coating film was concave at the grindstone scar part, and was not uniform.
[0031]
【The invention's effect】
Since the coating pretreatment method of the present invention has the above-described configuration, a uniform electrodeposition film surface after electrodeposition coating can be obtained.
[Brief description of the drawings]
FIG. 1 is an example of a pH control flow sheet for a post-chemical conversion water washing tank.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1
Claims (2)
前記化成後水洗における水洗液に、塩基性化合物又はその水溶液を添加することによって、前記水洗液のｐＨを４〜７の範囲に制御する
ことを特徴とする電着塗装前処理方法。By forming a zinc-based plated steel sheet coated with a phosphate film having a film amount of 0.1 to 2 g / m 2 , and a process including a process of subjecting the molded product to a phosphate film chemical conversion treatment and a step of washing with water after chemical conversion An electrodeposition coating pretreatment method comprising processing,
The electrodeposition coating pretreatment method characterized by controlling the pH of the water washing liquid in a range of 4 to 7 by adding a basic compound or an aqueous solution thereof to the water washing liquid in the post-chemical conversion water washing. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000338630A JP3778791B2 (en) | 2000-11-07 | 2000-11-07 | Pre-painting method and molded product |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000338630A JP3778791B2 (en) | 2000-11-07 | 2000-11-07 | Pre-painting method and molded product |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2002146596A JP2002146596A (en) | 2002-05-22 |
| JP3778791B2 true JP3778791B2 (en) | 2006-05-24 |
Family
ID=18813811
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000338630A Expired - Fee Related JP3778791B2 (en) | 2000-11-07 | 2000-11-07 | Pre-painting method and molded product |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3778791B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016156896A1 (en) * | 2015-03-31 | 2016-10-06 | Arcelormittal | Panel for vehicle comprising a coated steel sheet locally reinforced |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6075367A (en) * | 1983-09-30 | 1985-04-27 | Nippon Steel Corp | Production of automobile |
| JPH07173687A (en) * | 1993-12-17 | 1995-07-11 | Nkk Corp | Zr-cr composite plated steel sheet excellent in corrosion resistance |
| JPH07278891A (en) * | 1994-04-12 | 1995-10-24 | Nippon Parkerizing Co Ltd | Pretreatment for coating of metal material |
| JPH0867989A (en) * | 1994-08-26 | 1996-03-12 | Nkk Corp | Rustproof steel sheet for automobile excellent in joined part corrosion resistance, coating suitability and weldability and its production |
-
2000
- 2000-11-07 JP JP2000338630A patent/JP3778791B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2002146596A (en) | 2002-05-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2686380C (en) | Metallizing pretreatment of zinc surfaces | |
| KR101431942B1 (en) | Method for producing steel sheet for container | |
| JP4276530B2 (en) | Chemical conversion treatment agent and surface treatment metal | |
| EP0744475B1 (en) | Process for improving the formability and weldability properties of zinc coated sheet steel | |
| JP4650128B2 (en) | Method for producing alloyed hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet | |
| CN104024476A (en) | Method for producing cold-rolled steel sheet having excellent chemical conversion properties and excellent corrosion resistance after coating | |
| AU628169B2 (en) | Electroplating of hot-galvanized steel sheet and continuous plating line therefor | |
| US6432220B1 (en) | Process for the preliminary treatment of a metallic workpiece before coating | |
| JP6051171B2 (en) | Process and composition for improving the corrosion performance of zinc surfaces pretreated with zirconium oxide | |
| JP2007016266A (en) | Method for manufacturing galvannealed steel sheet, and galvannealed steel sheet | |
| JP3778791B2 (en) | Pre-painting method and molded product | |
| JPS6017827B2 (en) | Pretreatment method for metal surfaces for cationic electrodeposition coating | |
| WO1995027809A1 (en) | Method of pre-treating metal substrates prior to painting | |
| JPH0759755B2 (en) | Method for manufacturing A-l alloy coated plate for automobiles having excellent system rust resistance | |
| JP2947633B2 (en) | Nickel / chromium-containing galvanized steel sheet / steel material for coating base and its manufacturing method | |
| JP4344219B2 (en) | Inorganic organic composite-treated zinc-coated steel sheet with excellent corrosion resistance after electrodeposition coating | |
| JPH04168293A (en) | Pretreatment of iron-aluminum sheet metal structure before coating | |
| JPS6075367A (en) | Production of automobile | |
| JPH05247665A (en) | Post-treatment washing method for surface of metallic material subjected to phosphate treatment | |
| JP3241170B2 (en) | Pretreatment method for cationic electrodeposition coating of aluminum-based metal materials | |
| JPH042758A (en) | Production of hot-dip zinc alloy coated steel sheet excellent in press formability and corrosion resistance after coating | |
| JPH08325790A (en) | Equipment for production of electrogalvanized hot rolled sheet having excellent lubricity | |
| JPH03138391A (en) | Production of surface treated steel sheet excellent in coating suitability and corrosion resistance | |
| JPH0617286A (en) | Production of galvanized aluminum sheet | |
| JPH0617296A (en) | Production of composite plated al sheet excellent in moldability |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| RD04 | Notification of resignation of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7424 Effective date: 20040317 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20041126 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20050801 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050817 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20051017 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20051122 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20060105 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20060131 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20060228 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090310 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100310 Year of fee payment: 4 |
|
| LAPS | Cancellation because of no payment of annual fees |