JP3543090B2 - Resin-coated steel sheet for automobile fuel tank and method of manufacturing the same - Google Patents
Resin-coated steel sheet for automobile fuel tank and method of manufacturing the same Download PDFInfo
- Publication number
- JP3543090B2 JP3543090B2 JP2001537414A JP2001537414A JP3543090B2 JP 3543090 B2 JP3543090 B2 JP 3543090B2 JP 2001537414 A JP2001537414 A JP 2001537414A JP 2001537414 A JP2001537414 A JP 2001537414A JP 3543090 B2 JP3543090 B2 JP 3543090B2
- Authority
- JP
- Japan
- Prior art keywords
- resin
- steel sheet
- phr
- solution
- coating
- 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
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D161/00—Coating compositions based on condensation polymers of aldehydes or ketones; Coating compositions based on derivatives of such polymers
- C09D161/04—Condensation polymers of aldehydes or ketones with phenols only
- C09D161/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
- C08L61/04—Condensation polymers of aldehydes or ketones with phenols only
- C08L61/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
- C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
- C23C28/3225—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only with at least one zinc-based layer
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
- C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Laminated Bodies (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Paints Or Removers (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は自動車燃料タンク用無鉛表面処理鋼板に係り、より詳しくは、クロメート層がコーティングされた無鉛表面処理鋼板の表面に樹脂溶液がコーティングされた樹脂被覆鋼板及びこのような樹脂被覆鋼板の製造方法に関する。
【０００２】
【従来の技術】
自動車の燃料を保存する燃料タンク（ｆｕｅｌ ｔａｎｋ）の外面は大気中の腐食環境に耐えることができる耐食性（ｃｏｓｍｅｔｉｃ ｃｏｒｒｏｓｉｏｎ ｒｅｓｉｓｔａｎｃｅ）及びその内面はガソリンなどのような燃料に耐えることができる腐食抵抗性（以下、耐燃料性（ｆｕｅｌ ｃｏｒｒｏｓｉｏｎ ｒｅｓｉｓｔａｎｃｅ）という）が要求される。
【０００３】
また、鋼板を用いて燃料タンクを製作する場合、鋼板をプレスして上部及び下部の二つの容器形態に製作した後、これら上部及び下部容器を密着させて連結部分を点（ｓｐｏｔ）とシーム（ｓｅａｍ）などの抵抗溶接法で溶接したりソルダリング（ｓｏｌｄｅｒｉｎｇ）またはブレイジング（ｂｒａｚｉｎｇ）のような接合方法で接合して製作する。このように自動車用燃料タンクは二つの部品を密着させて接合するため、自動車用燃料タンクに用いられる鋼板は加工性及び溶接性が優れた材料が要求される。
【０００４】
このような材料特性に適した鋼板のうちの一つがターン（ｔｅｒｎｅ）鋼板である。しかし、ターン鋼板は冷延鋼板に鉛−錫の合金をメッキしたものであって、鉛を含有するので環境汚染を引き起こすという問題点があるため、その使用が規制されてきた。
【０００５】
このような理由のため鉛を用いない無鉛メッキ鋼板に関する研究が活発に行われている。
【０００６】
鉛を用いない無鉛メッキ鋼板としては本発明者が開発した国際特許公開番号ＷＯ００／３２８４３号がある。その発明は亜鉛及び亜鉛合金メッキ鋼板にクロメート層をメッキし、その上に樹脂溶液をコーティングした無鉛メッキ鋼板を用いて耐食性及び耐燃料性を向上させている。
【０００７】
前記発明で無鉛メッキ鋼板のコーティングに用いた樹脂溶液は主剤溶液としてフェノキシ樹脂を用いている。しかし、このようなフェノキシ樹脂は一般的な樹脂よりガラス転移温度が高いため加工されない平板部ではエポキシやアクリルまたはウレタン樹脂等に比べて耐食性及び耐燃料性が優れた特性を有するが、加工部では樹脂の高いガラス転移温度の影響のためシーム加工時に平板部に比べて耐食性及び耐燃料性が多少劣る問題がある。
【０００８】
このような問題点を改善するための方法としてはフェノキシ樹脂のガラス転移温度を低くしたり、フェノキシ樹脂層とその下部のクロメート層とを化学的に結合させることによってシーム加工時にも塗膜が剥離しないように改善する方法などがある。
【０００９】
フェノキシ樹脂のガラス転移温度を低くする方法としては日本特許公開番号平２−１８９８１号がある。この発明はフェノキシ樹脂のガラス転移温度を下降させて樹脂分子をゴムに変性させることによって樹脂とこれと結合する下部の素材との塗膜密着力を強化する方法に関する。しかし、このような方法を水溶性樹脂に適用する場合、ゴムに変成する時に水溶性化が難しく、水溶性化されたフェノキシ樹脂に水溶性化されたゴムを投入することも難しいという問題がある。
【００１０】
【発明が解決しようとする課題】
本発明はこのような問題点を改善したものであって、その技術的課題は、樹脂被覆鋼板の製造に用いられる樹脂溶液を樹脂の物理的特性を損傷させないでフェノキシ樹脂のガラス転移温度だけを下降させることができる添加剤を添加した樹脂溶液を提供することにある。
【００１１】
本発明の他の目的はこのような樹脂溶液を用いてフェノキシ樹脂と素地金属との密着力を向上させることができる自動車燃料タンク用樹脂被覆鋼板の製造方法を提供することにある。
【００１２】
【課題を解決するための手段】
このような技術的課題を達成するための、本発明の特徴による自動車燃料タンク用表面処理鋼板を製造するための樹脂溶液は、
（ａ）数平均分子量が２５，０００〜５０，０００である水溶性フェノキシ樹脂の主剤溶液と、
（ｂ）前記主剤溶液に対して２〜１５ｐｈｒのメラミン樹脂と、
（ｃ）前記主剤溶液に対して１０〜２０ｐｈｒのコロイダルシリカとを含み、
及び
（ｄ）分子量が２０，０００〜５０，０００であり、エチレン及びアクリル樹脂が各々５０〜８０％、５０〜２０％含まれている水溶性エチレン−アクリル樹脂を前記主剤溶液に対して５〜１５ｐｈｒ、及び／または前記主剤溶液に対して０．５〜３．０ｐｈｒのリン酸エステルを混合してなる。
【００１３】
本発明の他の特徴は、亜鉛または亜鉛合金がメッキされた冷延鋼板にクロメート被膜処理された表面処理鋼板において、
（ｅ）数平均分子量が２５，０００〜５０，０００である水溶性フェノキシ樹脂の主剤溶液と、
（ｆ）前記主剤溶液に対して２〜１５ｐｈｒのメラミン樹脂と、
（ｇ）前記主剤溶液に対して１０〜２０ｐｈｒのコロイダルシリカとを含み、
及び
（ｈ）分子量が２０，０００〜５０，０００であり、エチレン及びアクリル樹脂が各々５０〜８０％、５０〜２０％含まれている水溶性エチレン−アクリル樹脂を前記主剤溶液に対して５〜１５ｐｈｒ、及び／または前記主剤溶液に対して０．５〜３．０ｐｈｒのリン酸エステルを混合してなる樹脂溶液を
前記クロメート処理された冷延鋼板上に塗布して樹脂被膜を乾燥した後の被膜の厚さが２〜１０μｍである自動車燃料タンク用樹脂被覆鋼板を提供することにある。
【００１４】
本発明の他の特徴は亜鉛または亜鉛合金がメッキされた冷延鋼板にクロメート被膜処理された表面処理鋼板を製造する方法において、請求項１の樹脂被覆溶液を塗布して１６０〜２５０℃の焼付け温度で乾燥して乾燥被膜の厚さが２〜ｌ０μｍになるようにする樹脂被覆段階を含む自動車燃料タンク用樹脂被覆鋼板の製造方法を提供することにある。ここで前記樹脂被覆溶液の塗布方法はロールコーティング法で塗布するのが望ましい。
【００１５】
本発明の場合、水溶性フェノキシ樹脂にエチレン−アクリル樹脂及びリン酸エステルを添加した樹脂被覆溶液を製造することによって、向上した加工後の塗膜密着性、耐燃料性、及び耐食性を有するとともに鉛が全く用いられない新メッキ系燃料タンク鋼板を提供し、既存Ｐｂ−Ｓｎメッキ鋼板に比べて環境汚染問題を効果的に防止することができるようになる。また、自動車燃料タンク用鋼板の品質向上が可能であるので需要者の要求に十分に対応することができる。
【００１６】
【発明の実施の形態】
以下、本発明好ましい実施例及び添付した図面を用いて本発明を詳細に説明する。
【００１７】
本発明による樹脂被覆鋼板は図１のように、冷延鋼板上に亜鉛または亜鉛−ニッケル電気メッキを実施し、電気メッキ層がメッキされた鋼板に、クロムの付着量が１００ｍｇ／ｍ２になるようにクロメート処理した後、本発明による樹脂溶液が２〜ｌ０μｍ程度塗布されている構造を有する。
【００１８】
本発明で用いた基本鋼板としては炭素含量が０．０３％以下である低炭素鋼で冷間加工した冷延鋼板を用いた。
【００１９】
このような冷延鋼板の表面にメッキされる金属層は亜鉛（Ｚｎ）または亜鉛−ニッケル（Ｚｎ−Ｎｉ）、亜鉛−コバルト（Ｚｎ−Ｃｏ）、亜鉛−マンガン（Ｚｎ−Ｍｎ）、亜鉛−クロム（Ｚｎ−Ｃｒ）等の亜鉛系合金をメッキして用いることができる。本発明では亜鉛のみがメッキされたものよりは耐食性が優れた亜鉛合金メッキ鋼板である亜鉛−ニッケル鋼板を用いた。
【００２０】
亜鉛−ニッケルメッキ鋼板に塗布されるクロメート溶液は反応型、電解型、塗布型があるが、耐食性の面で優れた塗布型が好ましい。クロメート溶液をメッキ鋼板上に塗布する場合、メッキ鋼板の一面のみ塗布することもでき両面に被覆することもできるが、両面に被覆するのが好ましい。
【００２１】
しかし、本発明による樹脂溶液の場合は基本的に需要者の要求によって選択的に一面または両面に塗布することとなる。
【００２２】
このような選択は、本発明による樹脂被覆鋼板を用いて燃料タンクを製作する場合の溶接条件によって変わる。即ち、溶接の容易な高電流条件と電極を頻繁に交換する場合には両面に樹脂が被覆された鋼板を用いるのが好ましく、低電流条件と電極を頻繁に交替しない場合には一面にのみ樹脂が被覆された鋼板を用いるのが好ましい。
【００２３】
一面にのみ樹脂が被覆された鋼板で燃料タンクを製作する場合、樹脂被覆面が燃料と接触する側に向かうようにし、樹脂が被覆されていない面であるクロメートのみが塗布された面は外側に向かうようにして溶接するのが好ましい。このような方法で溶接すると、熔接用電極は樹脂が接触しない部分で溶接を行うこととなるので溶接を容易にすることができる。そして、樹脂が被覆されていない面は必要によって燃料タンクの耐食性補強のために厚く（約ｌ００μｍ）ペイントを塗装するため耐食性に及ぼす影響は殆どないということができる。
【００２４】
以下、本発明の樹脂被覆鋼板に用いた樹脂溶液について詳細に説明する。
【００２５】
本発明の樹脂溶液はフェノキシ樹脂を主剤溶液としここにメラミン樹脂及びコロイダルシリカが混合されている基本溶液に、エチレン−アクリル樹脂またはリン酸エステルを１つ以上添加して製造される。
【００２６】
本発明の樹脂溶液における主成分であるフェノキシ樹脂の混合量は数平均分子量が２５，０００〜５０，０００であるのが好ましい。数平均分子量が２５，０００未満である場合には所望の物性確保が難しく、５０，０００超である場合には合成方法の限界のため合成が不可能であるからである。
【００２７】
フェノキシ樹脂は耐食性及び耐燃料性が非常に優れ、その理由は以下の通りである。
【００２８】
フェノキシ樹脂は他の樹脂とは異なる物理的特徴を有しており、そのうち最も大きな特性はガラス転移温度（Ｇｌａｓｓ Ｔｒａｎｓｉｔｉｏｎ Ｔｅｍｐｅｒａｔｕｒｅ−Ｔｇ）が高いということである。つまり、ウレタン、エポキシ、アクリル樹脂の場合は、分子量によって少しずつは相違するが、ガラス転移温度が大概５０℃付近またはそれ以下であるのに比べて、フェノキシ樹脂の場合は１００℃である。このように高いガラス転移温度は樹脂鎖が動く温度が高いということを意味するもので、ガラス転移温度以下の温度では樹脂自体の鎖がマイクロブラウン運動をせずそのままであるので外部低分子の腐食因子（水分、ガソリンなど）に対して１次的な防御効果を有する。つまり、樹脂鎖がマイクロブラウン運動をすると、動く鎖の間に低分子が容易に浸透するようになって腐食因子の浸透が容易になるというのである。したがって、高いガラス転移温度の樹脂はそれだけ素地金属に対する遮蔽効果が大きいため、平板状態では相当な遮蔽効果を発揮することができる。
【００２９】
しかし、フェノキシ樹脂は上記長所とともに次のような問題点もある。即ち、樹脂塗膜はそれ自体が硬い（ｈａｒｄ）ため、一旦加工されるときは軟らかな樹脂、つまり低いガラス転移温度のものに比べて延伸がよく起こらないだけでなく下部の金属メッキ層との密着性も弱いため、苛酷な加工時には樹脂塗膜にひびが入りながら塗膜密着性が弱くなる。さらに、もっと激しい加工にさらされると塗膜が剥離する現象が発生し素地金属である金属メッキ層にまで腐食因子が容易に浸透してむしろ腐食がよりはげしく起こることがある。
【００３０】
自動車の燃料タンクを製造する場合、加工工程で成形性を向上させるために加工前にプレス油を塗布した後にプレスし、これを除去するために脱脂工程を遂行する。しかし、このように脱脂工程を遂行すると樹脂を硬くするため、塗膜密着性が弱い部位で脱脂工程による損傷が生じるので樹脂処理した元来の遮蔽効果を期待できなくなる。したがって、純粋なフェノキシ樹脂よりは塗膜密着性及び延伸率が優れた他の樹脂を添加してポリアロイ（ｐｏｌｙ−ａｌｌｏｙ）あるいはポリブレンド（ｐｏｌｙ−ｂｌｅｎｄ）状態で用いるのが好ましい。
【００３１】
前記ポリブレンドを形成する他の樹脂の条件は、第一に水溶性フェノキシ樹脂との相溶性があってゲル化またはスラッジが発生しないこと、第二にフェノキシ樹脂それ自体が保有している優れた特性である耐食性及び耐燃料性に影響を及ぼさないと共に、樹脂全体のガラス転移温度を低くすることによって塗膜密着性を向上させる効果があることである。
【００３２】
このような条件にかなう樹脂としてはエチレン−アクリル樹脂がある。
【００３３】
フェノキシ樹脂にエチレン−アクリル樹脂を添加する方式には、フェノキシ樹脂にエチレン−アクリル樹脂を化学的に結合させる方法と物理的に混入する方法があるが、ここでは物理的に混入する方式が好ましい。
【００３４】
本発明で化学的結合方式が適切でない理由は、用いられるエチレン−アクリル樹脂が気相で合成され、既に水溶化された状態であるので水溶化された状態の樹脂と水溶化されたフェノキシ樹脂を合成することは不可能であるためである。
【００３５】
本発明で用いられるエチレン−アクリル樹脂は分子量が２０，０００〜５０，０００であって、エチレン及びアクリル樹脂が各々５０〜８０％、５０〜２０％含まれている。アクリル樹脂が２０％未満含まれている場合には水溶化が不可能であり、反対に８０％超添加される場合にはガラス転移温度が高くなって密着性が悪くなる問題があるためである。エチレン−アクリル樹脂の含量はフェノキシ樹脂に対して５〜１５ｐｈｒ（ｐａｒｔｓ ｐｅｒ ｈｕｎｄｒｅｄ ｒｅｓｉｎ：主剤１００重量部当り添加される量）であるのが好ましい。エチレン−アクリル樹脂が５ｐｈｒ未満である場合には塗膜密着性効果が少なく、反対に１５ｐｈｒ超である場合には耐燃料性が低下する。耐燃料性が低下する理由は、燃料として用いられるガソリンの場合は典型的に炭素及び水素から構成された炭化水素化合物であるため、炭素及び水素のみからなる構造で構成されたエチレン樹脂と分子構造上類似してるのでエチレン−アクリル樹脂にガソリンが浸透して膨潤が起こるためである。
【００３６】
本発明の樹脂溶液において、樹脂の塗膜密着性を向上させる方法には前述のポリブレンド方法以外に、添加剤を投入する方法がある。
【００３７】
添加剤の役割はシーム加工時にフェノキシ樹脂とその下部層であるクロメート層との密着力を強化させることである。本発明で用いた添加剤であるリン酸エステルの作用原理を図２を参照して簡単に説明する。
【００３８】
図２はリン酸エステルの分子構造を示すものであって、リン酸エステルの水酸基は水分子の水素原子と水素結合を形成することで水分がこれ以上浸透することを防止することによって耐食性を向上させ、リン酸エステルの酸素は表面層の金属イオンと結合して塗膜密着性を向上させる。
【００３９】
リン酸エステルの添加量はフェノキシ樹脂対比０．５〜３．０ｐｈｒ添加するのが好ましい。リン酸エステルの添加量が０．５ｐｈｒ未満になると密着力向上効果が低下し、３．０ｐｈｒ超になると添加量の増加による効果がなくなるためである。
【００４０】
本発明ではフェノキシ樹脂の短所を補完するためにフェノキシ樹脂に前記エチレン−アクリル樹脂及びリン酸エステルを全て混合するか選択的に混合することができる。エチレン−アクリル樹脂及びリン酸エステルを全て混合する場合にはフェノキシ樹脂自体のガラス転移温度が降下し、これと共にリン酸エステルの各イオンが金属と結合し２種類が複合的にフェノキシ樹脂の加工後の塗膜密着性を向上させることができる。
【００４１】
本発明のフェノキシ樹脂を主剤溶液とする樹脂溶液に硬化剤としてメラミン樹脂をさらに添加してもよい。
【００４２】
メラミン樹脂の添加量はフェノキシ樹脂含量対比２〜１５ｐｈｒ添加される。この時、添加されるメラミン樹脂の場合、反応性の良いものを選定するのが好ましい。添加量がフェノキシ樹脂対比２ｐｈｒ未満である場合には樹脂被覆後の硬化反応が充分でないため所望の物理的特性を確保することが難しく、反対に１５ｐｈｒ超である場合には過剰添加によって硬化剤相互間の反応が発生して被膜層の物理的特性に悪い影響を及ぼすため好ましくない。
【００４３】
本発明の樹脂溶液にさらに添加される物質としてはコロイダルシリカがある。コロイダルシリカは樹脂の耐食性向上のために添加される。コロイダルシリカの添加量はフェノキシ樹脂含量対比１０〜２０ｐｈｒであるのが好ましい。コロイダルシリカの含量が１０ｐｈｒ未満になると含量が少なすぎるため耐食性効果がなく、反対に２０ｐｈｒ超になるとシリカ投入量に比べて耐食性向上効果がないためである。
【００４４】
以下、本発明の樹脂溶液を利用した樹脂被覆鋼板の製造方法について説明する。
【００４５】
本発明の樹脂被覆鋼板は、亜鉛及び亜鉛合金メッキ鋼板にクロメート処理を行った後に焼付け乾燥し、前記樹脂溶液を被覆した後に再び鋼板を焼付け乾燥する方法で製造される。
【００４６】
クロメート層の上側に塗布される樹脂被膜の乾燥厚さは２．０〜１０．０μｍとするのが好ましい。被膜の厚さが２μｍ未満である場合には被膜厚さが薄いため充分な耐食性及び耐燃料性を確保することが難しく、１０μｍ超である場合には被膜厚さの増加によって耐食性及び耐燃料性に影響がないだけでなく、鋼板を互いに溶接する場合に溶接性が低下するためである。
【００４７】
前記樹脂溶液被覆後の焼付け温度は鋼板温度（ＭＴ−Ｍｅｔａｌ Ｔｅｍｐｅｒａｔｕｒｅ）基準で１６０〜２５０℃の温度範囲が好ましく、焼付け温度が１６０℃未満になると樹脂の硬化反応が十分でないため耐食性及び耐燃料性が低下し、反対に２５０℃超になると硬化反応はそれ以上起こらず熱量損失がその分だけ大きいためである。
【００４８】
一方、鋼板の塗布方法としてはロールによるロールコーティング、スプレー、浸漬法など多様な方法があるが、本発明の場合はロールコーティング方法を用いるのが好ましい。
【００４９】
本発明のクロメート処理及び樹脂溶液塗布に用いられるロールコーティング設備は図３に示されている通りである。図３による樹脂溶液塗布方法はドリップパンにある樹脂をピックアップロール（Ｐ．Ｕ．Ｒ）に付けてトランスファロール（Ｔ．Ｆ．Ｒ）に転写した後、アプリケータロール（Ａ．ｐ．Ｒ）で最終的に鋼板に付けた後にオーブンで乾燥して樹脂被膜を形成する方法である。この時に付着する樹脂付着量は各ロール駆動方向、回転速度、各ロール相互密着圧力等で調節する。
【００５０】
本発明において、前記ロールコーティング法を用いると鋼板の片面及び両面に被覆することが可能である。
【００５１】
以下、本発明の理解を助けるために好ましい実施例を提示する。しかし、下記の実施例は本発明をより容易に理解するために提供されるものにすぎず、本発明が下記の実施例に限られるのではない。
【００５２】
実施例１
数平均分子量が５０，０００であるフェノキシ樹脂に硬化剤としてメラミン樹脂を５ｐｈｒ添加した後、粒径が２０ｎｍであるコロイダルシリカを１５ｐｈｒ、ワックスを２ｐｈｒ混合した樹脂溶液の組成を、これと異なる特別な明記がない限り、標準溶液組成という。また、メッキ付着量が３０ｇ／ｍ２である電気亜鉛及び亜鉛合金メッキ鋼板上にクロメート処理を行い、鋼板温度が１６０℃になるように焼付け乾燥して冷却した後、それぞれの組成で製造した樹脂溶液を塗布した後に鋼板温度が１９０℃になるように焼付け乾燥して被膜乾燥厚さが３μｍである樹脂被覆鋼板を製造する一連の工程を標準鋼板製造方法という。
【００５３】
前記標準溶液組成に、エチレン樹脂対アクリル樹脂の重量比率が８０：２０であるエチレン−アクリル樹脂を下記の表１のような含量で混合して樹脂溶液を製造した後、２０〜３０ｇ／ｍ２の亜鉛メッキ付着量でメッキして１００ｍｇ／ｍ２のクロメート処理を行った鋼板に前記樹脂溶液をロールコーティング方法で塗布し、鋼板温度が１９０℃になるように焼付け乾燥した後に水冷して乾燥樹脂塗膜厚さが３μｍである樹脂被覆鋼板を製造した。
【００５４】
前記方法で製造された樹脂被覆鋼板に対する耐食性評価は塩水噴霧試験器を用いて加工部のみを評価した。評価のための試片は平板を９５ｍｍに切断して直径５０ｍｍ、高さ２５ｍｍであるカップを製作した後、５００時間が経過すると塩水噴霧器から取り出して蒸留水で洗浄し乾燥して製造した。その次に、耐食性は試片に発生した錆の比率によって下記のように評価して、その結果を下表１に示した。
◎：白錆発生面積が全体試片面積対比５％以下
○：白錆発生面積が全体試片面積対比５〜３０％
□：白錆発生面積が全体試片面積対比３０〜５０％
△：白錆発生面積が全体試片面積対比５０〜１００％
【００５５】
また、加工後、塗膜密着性評価のために２種類のモードを用いた。即ち、１次モードは平板を９５ｍｍに切断して直径５０ｍｍ、高さ２５ｍｍであるカップを製作した後、高さ２５ｍｍカップ試片の周囲にセロファンテープを付けて樹脂が剥離される面積を求めることであり、２次モードは５０℃、１０％苛性ソーダ溶液に３分間超音波を加えて洗浄した後、１次と同一に評価して求めることである。さらに、塗膜密着性は下記のような基準によって評価し、その結果も表１に示した。
◎：剥離された面積が０％
○：剥離された面積が１〜５％
□：剥離された面積が５〜１０％
△：剥離された面積が１０〜２０％
×：剥離された面積が２０％超
【００５６】
耐燃料性評価は燃料が接触する部位の平板を９５ｍｍに切断して直径５０ｍｍ、高さ２５ｍｍであるカップを製作し、その内部に３タイプの溶液を２５ｍｌ投入した後、鋼板上に“Ｏ”リングを置き、その上を透明なガラス板で覆いクランプで固定してガソリンの漏油を防止するようにした。耐燃料性評価に用いられた溶液はＡ、Ｂ、Ｃの３タイプに分け、Ａタイプの場合は通常用いられるレギュラーガソリンに５％塩を混合した溶液を用い、Ｂタイプは通常用いられるレギュラーガソリンに０．２％塩を混合した溶液を用い、Ｃタイプはメタノールと添加剤が含まれているレギュラーガソリンをそのまま用い、前記Ｃタイプの組成はレギュラーガソリン８５％＋メタノール１４％＋蟻酸６０ｐｐｍとＣｌ−２０ｐｐｍが含まれている蒸留水１％であった。
【００５７】
また、自動車の運行中の状況を再現するために、カップ内の燃料が揺動を受けるように予め製作された揺動装置を用いた。前記方法により四ヶ月経過した後に取り出して蒸留水で洗浄し乾燥した後、発生した錆の比率によって耐燃料性を評価してその結果を表１に示した。評価基準は下記の通りである。
◎：白錆発生面積が全体試片面積対比５％以下
○：白錆発生面積が全体試片面積対比５〜３０％
□：白錆発生面積が全体試片面積対比３０〜５０％
△：白錆発生面積が全体試片面積が比５０〜１００％
×：赤錆発生
【００５８】
【表１】
前記表１に樹脂溶液のうちの添加剤であるエチレン−アクリル樹脂と硬化剤であるメラミン樹脂の含量変化による品質評価結果を示した。表１から分かるように、エチレン−アクリル樹脂の含量が２０ｐｈｒ超である場合、塗膜密着性及び耐食性は良好であったが、耐燃料性は減少する傾向を示した。また、エチレン−アクリル樹脂の含量が５ｐｈｒ未満である比較例の場合も、各品質評価において本発明の実施例より悪い結果を示すことが分かる。
【００６０】
実施例２
前記標準溶液組成に添加剤としてリン酸エステルを下記の表２のような含量で混合して樹脂溶液を製造した後、２０〜３０ｇ／ｍ２の亜鉛メッキ付着量でメッキして１００ｍｇ／ｍ２のクロメート処理を行った鋼板に前記樹脂溶液をロールコーティング方法で塗布し、鋼板温度が１９０℃になるように焼付け乾燥した後に水冷して乾燥樹脂塗膜厚さが３μｍである樹脂被覆鋼板を製造した。その後、前記実施例１と同じ条件で品質評価を実施して、その結果を表２に示した。
【００６１】
【表２】
前記表２に樹脂溶液のうちの添加剤であるリン酸エステルと硬化剤であるメラミン樹脂の含量変化による品質評価結果を示した。前記表２から分かるように、リン酸エステル含量が本発明の０．５〜３．０ｐｈｒの範囲内にある場合、加工後の塗膜密着成が向上した。しかし、リン酸エステル含量が３．０ｐｈｒを超過したり０．５ｐｈｒ未満である場合、各品質評価において、実施例に比べて劣ることが分かる。
【００６３】
【発明の効果】
本発明によって前記標準溶液組成に添加剤としてリン酸エステル及びエチレン−アクリル樹脂を複合添加すると、前記実施例のようにリン酸エステルとエチレン−アクリル樹脂を単独に添加したものに比べて、同等以上の優れた効果があることが分かった。
【図面の簡単な説明】
【図１】自動車燃料タンク用樹脂被覆鋼板の被覆層を概略的に示した断面図である。
【図２】本発明の樹脂溶液に添加されるリン酸エステルが素地金属と結合する状況を示す模式図である。
【図３】本発明の樹脂溶液を冷延鋼板にコーティングする設備を示すロールコーティング設備の概略図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lead-free surface-treated steel sheet for an automobile fuel tank, and more particularly, to a resin-coated steel sheet in which a resin solution is coated on the surface of a lead-free surface-treated steel sheet coated with a chromate layer, and a method for producing such a resin-coated steel sheet. About.
[0002]
[Prior art]
The outer surface of a fuel tank for storing fuel of a vehicle has a corrosion resistance capable of withstanding a corrosive environment in the atmosphere, and the inner surface has a corrosion resistance capable of withstanding a fuel such as gasoline. Hereinafter, it is required to have fuel resistance.
[0003]
When a fuel tank is manufactured using a steel plate, the steel plate is pressed into two upper and lower container shapes, and the upper and lower containers are brought into close contact with each other to connect a spot and a seam (spot). For example, it is manufactured by welding using a resistance welding method such as seam, or by using a joining method such as soldering or brazing. As described above, since the two parts of the automobile fuel tank are brought into close contact with each other and joined, a steel sheet used for the automobile fuel tank is required to be a material having excellent workability and weldability.
[0004]
One of the steel sheets suitable for such material properties is a turn steel sheet. However, the use of a turn steel sheet is a cold-rolled steel sheet plated with a lead-tin alloy and has a problem of causing environmental pollution since it contains lead, and thus its use has been restricted.
[0005]
For these reasons, research on lead-free plated steel sheets that do not use lead has been actively conducted.
[0006]
As a lead-free plated steel sheet not using lead, there is International Patent Publication No. WO00 / 32843 developed by the present inventors. According to the invention, corrosion resistance and fuel resistance are improved by using a lead-free plated steel sheet in which a chromate layer is plated on a zinc and zinc alloy plated steel sheet and a resin solution is coated thereon.
[0007]
The resin solution used for coating the lead-free plated steel sheet in the above invention uses a phenoxy resin as a base solution. However, such a phenoxy resin has a higher glass transition temperature than a general resin, so that a flat portion that is not processed has excellent corrosion resistance and fuel resistance as compared with epoxy, acrylic, or urethane resin, etc. Due to the effect of the high glass transition temperature of the resin, there is a problem that the corrosion resistance and the fuel resistance are somewhat inferior to the flat part during seam processing.
[0008]
As a method for improving such a problem, a coating film is peeled even during seam processing by lowering a glass transition temperature of a phenoxy resin or chemically bonding a phenoxy resin layer and a chromate layer thereunder. There are ways to improve it.
[0009]
As a method of lowering the glass transition temperature of the phenoxy resin, there is Japanese Patent Publication No. 2-18981. BACKGROUND OF THE
[0010]
[Problems to be solved by the invention]
The present invention has been made to solve such problems, and the technical problem is that the resin solution used in the production of resin-coated steel sheet only changes the glass transition temperature of the phenoxy resin without damaging the physical properties of the resin. An object of the present invention is to provide a resin solution to which an additive that can be lowered is added.
[0011]
Another object of the present invention is to provide a method for producing a resin-coated steel sheet for an automobile fuel tank, which can improve the adhesion between a phenoxy resin and a base metal using such a resin solution.
[0012]
[Means for Solving the Problems]
To achieve such a technical problem, a resin solution for producing a surface-treated steel plate for an automobile fuel tank according to the features of the present invention is:
(A) a base solution of a water-soluble phenoxy resin having a number average molecular weight of 25,000 to 50,000;
(B) 2-15 phr melamine resin with respect to the base solution;
(C) 10 to 20 phr of colloidal silica with respect to the base solution,
And (d) a water-soluble ethylene-acrylic resin having a molecular weight of 20,000 to 50,000, containing 50 to 80% of ethylene and an acrylic resin, and 50 to 20%, respectively. 15 phr and / or 0.5 to 3.0 phr of a phosphoric acid ester mixed with the base solution.
[0013]
Another feature of the present invention is a cold-rolled steel sheet plated with zinc or a zinc alloy, which is a surface-treated steel sheet subjected to chromate coating treatment,
(E) a base solution of a water-soluble phenoxy resin having a number average molecular weight of 25,000 to 50,000,
(F) 2-15 phr melamine resin with respect to the base solution;
(G) 10 to 20 phr of colloidal silica with respect to the base solution,
And (h) a water-soluble ethylene-acrylic resin having a molecular weight of 20,000 to 50,000 and containing 50 to 80% of ethylene and 50 to 20% of acrylic resin, respectively, with respect to the base solution. 15 phr and / or a resin solution obtained by mixing 0.5 to 3.0 phr of a phosphate ester with the base solution is applied to the cold-rolled steel sheet subjected to the chromate treatment, and the resin film is dried. An object of the present invention is to provide a resin-coated steel sheet for an automobile fuel tank having a thickness of 2 to 10 μm.
[0014]
Another feature of the present invention is a method of manufacturing a surface-treated steel sheet having a chromate coating on a cold-rolled steel sheet plated with zinc or a zinc alloy, wherein the resin coating solution according to
[0015]
In the case of the present invention, by producing a resin coating solution obtained by adding an ethylene-acrylic resin and a phosphoric acid ester to a water-soluble phenoxy resin, the coating film adhesion after processing, fuel resistance, and corrosion resistance are improved and lead is obtained. The present invention provides a new plated fuel tank steel plate in which no Pb is used, and can effectively prevent environmental pollution problems compared to existing Pb-Sn plated steel plates. Further, since the quality of the steel plate for an automobile fuel tank can be improved, it is possible to sufficiently meet the demands of consumers.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention and the accompanying drawings.
[0017]
As shown in FIG. 1, the resin-coated steel sheet according to the present invention is formed by electroplating zinc or zinc-nickel on a cold-rolled steel sheet, and the amount of chromium deposited on the steel sheet having the electroplated layer becomes 100 mg / m 2 . After the chromate treatment, the resin solution according to the present invention is applied in a thickness of about 2 to 10 μm.
[0018]
As the basic steel sheet used in the present invention, a cold-rolled steel sheet cold-worked with a low carbon steel having a carbon content of 0.03% or less was used.
[0019]
The metal layer plated on the surface of the cold rolled steel sheet is zinc (Zn) or zinc-nickel (Zn-Ni), zinc-cobalt (Zn-Co), zinc-manganese (Zn-Mn), zinc-chromium. A zinc-based alloy such as (Zn-Cr) can be plated and used. In the present invention, a zinc-nickel steel sheet which is a zinc alloy-plated steel sheet having more excellent corrosion resistance than that in which only zinc is plated is used.
[0020]
The chromate solution applied to the zinc-nickel plated steel sheet includes a reaction type, an electrolytic type, and a coating type, but a coating type excellent in corrosion resistance is preferable. When the chromate solution is applied on the plated steel sheet, it can be applied on only one side of the plated steel sheet or can be coated on both sides, but preferably coated on both sides.
[0021]
However, in the case of the resin solution according to the present invention, it is basically applied selectively to one or both surfaces according to the demand of the consumer.
[0022]
Such a choice depends on welding conditions when a fuel tank is manufactured using the resin-coated steel sheet according to the present invention. In other words, it is preferable to use a steel sheet coated with resin on both sides when the electrodes are frequently replaced with high current conditions that are easy to weld, and only on one surface when the electrodes are not frequently replaced with low current conditions. It is preferable to use a steel sheet coated with.
[0023]
When manufacturing a fuel tank with a steel plate coated with resin only on one side, make the resin coated side face the side that comes into contact with fuel, and the side where only chromate, which is not coated with resin, is on the outside. It is preferable to weld in such a manner as to face each other. When welding is performed by such a method, welding is performed at a portion where the resin does not come into contact with the welding electrode, so that welding can be facilitated. The surface not coated with the resin is thick (about 100 μm) to reinforce the corrosion resistance of the fuel tank, if necessary, so that it can be said that there is almost no influence on the corrosion resistance because the paint is applied.
[0024]
Hereinafter, the resin solution used for the resin-coated steel sheet of the present invention will be described in detail.
[0025]
The resin solution of the present invention is produced by adding one or more ethylene-acrylic resin or phosphate to a basic solution containing a phenoxy resin as a main solution and a melamine resin and colloidal silica mixed therein.
[0026]
The mixing amount of the phenoxy resin as the main component in the resin solution of the present invention preferably has a number average molecular weight of 25,000 to 50,000. When the number average molecular weight is less than 25,000, it is difficult to secure desired physical properties, and when the number average molecular weight is more than 50,000, synthesis is impossible due to the limitation of the synthesis method.
[0027]
The phenoxy resin has extremely excellent corrosion resistance and fuel resistance, for the following reasons.
[0028]
Phenoxy resins have different physical characteristics from other resins, the greatest of which is the high glass transition temperature (Tg). In other words, in the case of urethane, epoxy, and acrylic resins, the glass transition temperature is almost 50 ° C. or less, while the glass transition temperature is almost 50 ° C. or less, while it is 100 ° C. in the case of phenoxy resin. Such a high glass transition temperature means that the temperature at which the resin chains move is high.At a temperature lower than the glass transition temperature, the chains of the resin itself do not undergo micro-Brownian motion, so corrosion of external low molecules is caused. It has a primary defense effect against factors (moisture, gasoline, etc.). In other words, when the resin chains make micro-Brownian motion, small molecules can easily penetrate between the moving chains, thereby facilitating the penetration of corrosion factors. Therefore, since a resin having a high glass transition temperature has a large shielding effect on the base metal, a considerable shielding effect can be exhibited in a flat plate state.
[0029]
However, the phenoxy resin has the following problems in addition to the above advantages. In other words, since the resin coating itself is hard, once it is processed, not only does it not stretch well compared to a soft resin, that is, a resin having a low glass transition temperature, but it also forms a hard coating with the lower metal plating layer. Since the adhesion is also weak, the film adhesion is weakened while the resin coating is cracked during severe processing. Further, when subjected to more severe processing, a phenomenon in which the coating film is peeled off may occur, and the corrosion factor may easily penetrate into the metal plating layer, which is the base metal, and the corrosion may occur more strongly.
[0030]
When manufacturing a fuel tank for an automobile, a press oil is applied before processing in order to improve formability in a processing step, and then pressed, and a degreasing step is performed to remove the press oil. However, when the degreasing step is performed as described above, the resin is hardened, and damage is caused by the degreasing step at a portion where the coating film adhesion is weak, so that the original shielding effect of the resin treatment cannot be expected. Therefore, it is preferable to add another resin having better coating film adhesion and elongation ratio than a pure phenoxy resin and use it in a poly-alloy or poly-blend state.
[0031]
The conditions of the other resins forming the polyblend are, first, compatibility with the water-soluble phenoxy resin and no gelation or sludge is generated, and second, the excellent properties of the phenoxy resin itself. This has the effect of not affecting the corrosion resistance and fuel resistance, which are the characteristics, and improving the coating film adhesion by lowering the glass transition temperature of the entire resin.
[0032]
As a resin satisfying such conditions, there is an ethylene-acrylic resin.
[0033]
The method of adding the ethylene-acryl resin to the phenoxy resin includes a method of chemically bonding the ethylene-acryl resin to the phenoxy resin and a method of physically mixing the ethylene-acryl resin with the phenoxy resin. Here, the method of physically mixing the ethylene-acryl resin is preferable.
[0034]
The reason why the chemical bonding method is not suitable in the present invention is that the ethylene-acrylic resin used is synthesized in the gas phase and is already in a water-soluble state, so that the water-soluble resin and the water-soluble phenoxy resin are used. This is because it is impossible to combine them.
[0035]
The ethylene-acrylic resin used in the present invention has a molecular weight of 20,000 to 50,000, and contains 50 to 80% and 50 to 20% of ethylene and acrylic resin, respectively. If the acrylic resin content is less than 20%, water solubility cannot be achieved, and if it is more than 80%, on the other hand, there is a problem that the glass transition temperature becomes high and the adhesion becomes poor. . The content of the ethylene-acrylic resin is preferably 5 to 15 phr (parts per hundred resin: an amount added per 100 parts by weight of the main agent) based on the phenoxy resin. When the ethylene-acrylic resin is less than 5 phr, the coating film adhesion effect is small, and when it is more than 15 phr, the fuel resistance is reduced. The reason for the decrease in fuel resistance is that gasoline used as a fuel is typically a hydrocarbon compound composed of carbon and hydrogen, so ethylene resin composed only of carbon and hydrogen and a molecular structure This is because gasoline permeates the ethylene-acrylic resin and swells because of similarity.
[0036]
In the resin solution of the present invention, in addition to the above-described polyblend method, there is a method of adding an additive, in addition to the above-described polyblend method.
[0037]
The role of the additive is to enhance the adhesion between the phenoxy resin and the lower chromate layer during seam processing. The working principle of the phosphoric acid ester as the additive used in the present invention will be briefly described with reference to FIG.
[0038]
Fig. 2 shows the molecular structure of the phosphate ester. The hydroxyl group of the phosphate ester forms a hydrogen bond with the hydrogen atom of the water molecule, thereby preventing moisture from penetrating further and improving corrosion resistance. Then, the oxygen of the phosphoric acid ester binds to the metal ions in the surface layer to improve the adhesion of the coating film.
[0039]
The addition amount of the phosphate ester is preferably 0.5 to 3.0 phr compared to the phenoxy resin. If the amount of the phosphoric acid ester is less than 0.5 phr, the effect of improving the adhesion is reduced, and if it is more than 3.0 phr, the effect due to the increase in the added amount is lost.
[0040]
In the present invention, in order to compensate for the disadvantages of the phenoxy resin, the ethylene-acrylic resin and the phosphate may be mixed with the phenoxy resin, or may be selectively mixed. When the ethylene-acrylic resin and the phosphoric acid ester are all mixed, the glass transition temperature of the phenoxy resin itself drops, and at the same time, each ion of the phosphoric acid ester binds to the metal, and two kinds of the phenoxy resin are combined after processing Can improve the adhesion of the coating film.
[0041]
A melamine resin may be further added as a curing agent to a resin solution containing the phenoxy resin of the present invention as a main solution.
[0042]
The melamine resin is added in an amount of 2 to 15 phr based on the phenoxy resin content. At this time, in the case of the melamine resin to be added, it is preferable to select a resin having good reactivity. If the addition amount is less than 2 phr relative to the phenoxy resin, the curing reaction after resin coating is not sufficient and it is difficult to secure the desired physical properties. This is not preferable because a reaction occurs between the layers and adversely affects the physical properties of the coating layer.
[0043]
A substance further added to the resin solution of the present invention is colloidal silica. Colloidal silica is added to improve the corrosion resistance of the resin. The amount of colloidal silica to be added is preferably 10 to 20 phr based on the phenoxy resin content. If the content of colloidal silica is less than 10 phr, the content is too small, so that there is no corrosion resistance effect. If it exceeds 20 phr, on the other hand, there is no effect of improving the corrosion resistance as compared with the amount of silica input.
[0044]
Hereinafter, a method for producing a resin-coated steel sheet using the resin solution of the present invention will be described.
[0045]
The resin-coated steel sheet of the present invention is manufactured by subjecting a zinc and zinc alloy-plated steel sheet to a chromate treatment, baking and drying, coating the resin solution, and then baking and drying the steel sheet again.
[0046]
The dry thickness of the resin film applied on the upper side of the chromate layer is preferably 2.0 to 10.0 μm. When the thickness of the coating is less than 2 μm, it is difficult to secure sufficient corrosion resistance and fuel resistance because the coating thickness is small, and when it is more than 10 μm, the corrosion resistance and fuel resistance are increased due to an increase in the coating thickness. This is because not only is there no effect on the weldability, but also the weldability decreases when the steel sheets are welded to each other.
[0047]
The baking temperature after coating with the resin solution is preferably in the range of 160 to 250 ° C. based on the steel sheet temperature (MT-Metal Temperature). If the baking temperature is lower than 160 ° C., the curing reaction of the resin is not sufficient, so that the corrosion resistance and the fuel resistance are low. On the other hand, when the temperature exceeds 250 ° C., the curing reaction does not occur any more and the heat loss is correspondingly large.
[0048]
On the other hand, there are various methods for applying a steel sheet, such as roll coating with a roll, spraying, and dipping. In the present invention, it is preferable to use a roll coating method.
[0049]
The roll coating equipment used for chromate treatment and resin solution application of the present invention is as shown in FIG. In the resin solution application method shown in FIG. 3, the resin in the drip pan is applied to a pickup roll (PUR), transferred to a transfer roll (TFR), and then applied to an applicator roll (APR). And finally drying in an oven to form a resin film. The amount of resin adhered at this time is adjusted by the driving direction of each roll, the rotation speed, the pressure of each roll in close contact, and the like.
[0050]
In the present invention, it is possible to coat one side and both sides of a steel sheet by using the roll coating method.
[0051]
Hereinafter, preferred examples will be presented to assist the understanding of the present invention. However, the following examples are provided only for easier understanding of the present invention, and the present invention is not limited to the following examples.
[0052]
Example 1
After adding 5 phr of a melamine resin as a curing agent to a phenoxy resin having a number average molecular weight of 50,000, the composition of a resin solution obtained by mixing 15 phr of colloidal silica having a particle size of 20 nm and 2 phr of a wax is different from the above. Unless otherwise specified, it is referred to as the standard solution composition. In addition, a chromate treatment is performed on an electrolytic zinc and zinc alloy plated steel sheet having a plating adhesion amount of 30 g / m 2 , and the steel sheet is baked so as to have a temperature of 160 ° C., cooled, and then cooled. A series of steps of producing a resin-coated steel sheet having a coating dry thickness of 3 μm by baking and drying the steel sheet at a temperature of 190 ° C. after applying the solution is referred to as a standard steel sheet manufacturing method.
[0053]
An ethylene-acryl resin having a weight ratio of ethylene resin to acrylic resin of 80:20 was mixed with the standard solution composition at a content as shown in Table 1 below to prepare a resin solution, and then 20 to 30 g / m 2. The above resin solution is applied by roll coating to a steel sheet which has been subjected to a chromate treatment of 100 mg / m 2 after being coated with a zinc plating adhesion amount, and baked and dried so that the steel sheet temperature becomes 190 ° C., followed by water cooling to dry resin. A resin-coated steel sheet having a coating thickness of 3 μm was produced.
[0054]
The corrosion resistance of the resin-coated steel sheet manufactured by the above method was evaluated using a salt spray tester only for the processed part. A test piece for evaluation was manufactured by cutting a flat plate into 95 mm to produce a cup having a diameter of 50 mm and a height of 25 mm, and after 500 hours, taking out of the salt water sprayer, washing with distilled water, and drying. Next, the corrosion resistance was evaluated by the ratio of rust generated on the specimen as follows, and the results are shown in Table 1 below.
：: White rust occurrence area is 5% or less of the whole specimen area ：: White rust occurrence area is 5 to 30% of the whole specimen area
□: White rust generation area is 30 to 50% of the total specimen area
Δ: White rust generation area is 50 to 100% of the whole specimen area
[0055]
After processing, two types of modes were used for evaluation of coating film adhesion. That is, in the first mode, a flat plate is cut into 95 mm to make a cup with a diameter of 50 mm and a height of 25 mm, and then a cellophane tape is attached around the cup specimen of a height of 25 mm to determine the area from which the resin is peeled off. In the second mode, cleaning is performed by applying ultrasonic waves to a 10% caustic soda solution at 50 ° C. for 3 minutes, and then evaluated and determined in the same manner as in the first mode. Further, coating film adhesion was evaluated according to the following criteria, and the results are also shown in Table 1.
◎: peeled area is 0%
：: Peeled area is 1 to 5%
□: Peeled area is 5 to 10%
Δ: Peeled area is 10 to 20%
×: Exfoliated area is more than 20%.
For the evaluation of fuel resistance, a flat plate at a portion where fuel comes into contact was cut into 95 mm to make a cup having a diameter of 50 mm and a height of 25 mm, and 25 ml of three types of solutions were put therein, and then "O" was placed on a steel plate. The ring was placed, covered with a transparent glass plate and secured with a clamp to prevent gasoline oil leakage. The solutions used for fuel resistance evaluation were divided into three types: A, B, and C. In the case of the A type, a solution obtained by mixing 5% salt with a commonly used regular gasoline was used. For the B type, a normally used regular gasoline was used. A solution obtained by mixing 0.2% salt with the same is used. For the C type, regular gasoline containing methanol and additives is used as it is. The composition of the C type is 85% regular gasoline + 14% methanol + 60 ppm formic acid and Cl - 20 ppm was 1% distilled water included.
[0057]
Further, in order to reproduce the situation during the operation of the automobile, a rocking device that was manufactured in advance so that the fuel in the cup was rocked was used. After four months had elapsed according to the above method, it was taken out, washed with distilled water and dried, and the fuel resistance was evaluated based on the ratio of generated rust. The results are shown in Table 1. The evaluation criteria are as follows.
：: White rust occurrence area is 5% or less of the whole specimen area ：: White rust occurrence area is 5 to 30% of the whole specimen area
□: White rust generation area is 30 to 50% of the total specimen area
Δ: White rust generation area is 50-100% of the total specimen area
×: Red rust occurred.
[Table 1]
Table 1 shows quality evaluation results based on changes in the contents of the ethylene-acrylic resin as an additive and the melamine resin as a curing agent in the resin solution. As can be seen from Table 1, when the content of the ethylene-acrylic resin was more than 20 phr, the coating film adhesion and the corrosion resistance were good, but the fuel resistance tended to decrease. Also, it can be seen that Comparative Example in which the content of ethylene-acrylic resin is less than 5 phr shows worse results in each quality evaluation than Examples of the present invention.
[0060]
Example 2
A phosphate solution was mixed with the standard solution composition as an additive at a content shown in Table 2 below to prepare a resin solution, and then plated with a zinc plating adhesion amount of 20 to 30 g / m 2 to 100 mg / m 2. The resin solution is applied to a steel plate which has been subjected to the chromate treatment by a roll coating method, baked and dried so that the steel plate temperature becomes 190 ° C., and then water-cooled to produce a resin-coated steel plate having a dry resin film thickness of 3 μm. did. Thereafter, quality evaluation was performed under the same conditions as in Example 1, and the results are shown in Table 2.
[0061]
[Table 2]
Table 2 shows the quality evaluation results according to the change in the content of the phosphate ester as an additive and the melamine resin as a curing agent in the resin solution. As can be seen from Table 2, when the phosphate ester content was in the range of 0.5 to 3.0 phr of the present invention, the adhesion of the coating film after processing was improved. However, when the phosphoric ester content exceeds 3.0 phr or is less than 0.5 phr, it can be seen that each quality evaluation is inferior to the examples.
[0063]
【The invention's effect】
When a phosphate ester and an ethylene-acrylic resin are added as an additive to the standard solution composition according to the present invention, compared with the case where the phosphate ester and the ethylene-acrylic resin are added alone as in the above example, the equivalent or higher It was found that there was an excellent effect.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a coating layer of a resin-coated steel sheet for a vehicle fuel tank.
FIG. 2 is a schematic view showing a situation where a phosphate ester added to a resin solution of the present invention binds to a base metal.
FIG. 3 is a schematic view of a roll coating facility showing a facility for coating a cold rolled steel sheet with the resin solution of the present invention.
Claims (4)
（ｊ）前記主剤溶液に対して２〜１５ｐｈｒのメラミン樹脂と、
（ｋ）前記主剤溶液に対して１０〜２０ｐｈｒのコロイダルシリカとを含み、
及び
（ｌ）分子量が２０，０００〜５０，０００であり、エチレン及びアクリル樹脂が各々５０〜８０％、５０〜２０％含まれている水溶性エチレン−アクリル樹脂を前記主剤溶液に対して５〜１５ｐｈｒと、及び／または前記主剤溶液に対して０．５〜３．０ｐｈｒのリン酸エステルとを混合してなる自動車燃料タンク用樹脂被覆鋼板の製造に用いられる樹脂溶液。(I) a base solution of a water-soluble phenoxy resin having a number average molecular weight of 25,000 to 50,000,
(J) 2 to 15 phr of melamine resin with respect to the base solution;
(K) 10 to 20 phr of colloidal silica with respect to the base solution,
And (l) a water-soluble ethylene-acrylic resin having a molecular weight of 20,000 to 50,000, containing 50 to 80% of ethylene and an acrylic resin, and 50 to 20%, respectively, of 5 to 50% based on the base solution. A resin solution used for producing a resin-coated steel sheet for an automobile fuel tank, which is obtained by mixing 15 phr and / or 0.5 to 3.0 phr of a phosphate ester with respect to the base solution.
（ｍ）数平均分子量が２５，０００〜５０，０００である水溶性フェノキシ樹脂の主剤溶液と、
（ｎ）前記主剤溶液に対して２〜１２ｐｈｒのメラミン樹脂と、
（ｏ）前記主剤溶液に対して１０〜２０ｐｈｒのコロイダルシリカとを含み、
及び
（ｐ）分子量が２０，０００〜５０，０００であり、エチレン及びアクリル樹脂が各々５０〜８０％、５０〜２０％含まれている水溶性エチレン−アクリル樹脂を前記主剤溶液に対して５〜１５ｐｈｒ、及び／または前記主剤溶液に対して０．５〜３．０ｐｈｒのリン酸エステルを混合してなる樹脂溶液を
前記クロメート処理された冷延鋼板上に塗布して樹脂被膜を乾燥した後の被膜の厚さが２〜１０μｍであることを特徴とする自動車燃料タンク用樹脂被覆鋼板。In a surface-treated steel sheet that has been subjected to chromate coating on a cold-rolled steel sheet plated with zinc or zinc alloy,
(M) a base solution of a water-soluble phenoxy resin having a number average molecular weight of 25,000 to 50,000,
(N) 2 to 12 phr of a melamine resin with respect to the base solution;
(O) containing 10 to 20 phr of colloidal silica with respect to the base solution,
And (p) a water-soluble ethylene-acrylic resin having a molecular weight of 20,000 to 50,000, containing 50 to 80% of ethylene and an acrylic resin, and 50 to 20%, respectively. 15 phr and / or a resin solution obtained by mixing 0.5 to 3.0 phr of a phosphate ester with the base solution is applied to the cold-rolled steel sheet subjected to the chromate treatment, and the resin film is dried. A resin-coated steel sheet for an automobile fuel tank, wherein the thickness of the coating is 2 to 10 μm.
請求項１の樹脂被覆溶液を塗布し１６０〜２５０℃の焼付け温度で乾燥して乾燥被膜の厚さが２〜ｌ０μｍになるようにする樹脂被覆段階を含むことを特徴とする自動車燃料タンク用樹脂被覆鋼板の製造方法。In a method for producing a surface-treated steel sheet subjected to chromate coating on a cold-rolled steel sheet plated with zinc or a zinc alloy,
2. A resin for an automobile fuel tank, comprising a step of applying the resin coating solution of claim 1 and drying at a baking temperature of 160 to 250 [deg.] C. so that the thickness of the dried coating is 2 to 10 [mu] m. Manufacturing method of coated steel sheet.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-1999-0050110A KR100402014B1 (en) | 1999-11-12 | 1999-11-12 | A resin coating solution for coated steel sheets with exellent adhesion after forming and a method for manufacturing resin coating steel sheets by using it |
| KR1999/50110 | 1999-11-12 | ||
| PCT/KR2000/001297 WO2001034713A1 (en) | 1999-11-12 | 2000-11-13 | Resin-coated steel sheet for fuel tanks of automobile and method of fabricating the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003514095A JP2003514095A (en) | 2003-04-15 |
| JP3543090B2 true JP3543090B2 (en) | 2004-07-14 |
Family
ID=19619722
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001537414A Expired - Fee Related JP3543090B2 (en) | 1999-11-12 | 2000-11-13 | Resin-coated steel sheet for automobile fuel tank and method of manufacturing the same |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP1153095A4 (en) |
| JP (1) | JP3543090B2 (en) |
| KR (1) | KR100402014B1 (en) |
| CN (1) | CN1340087A (en) |
| WO (1) | WO2001034713A1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100423441B1 (en) * | 1999-12-28 | 2004-03-19 | 주식회사 포스코 | A preparing method of resin coating solution for fuel tank body with excellent solution stability, the resin coating solution prepared from it and a method for manufacturing organic resin coated steel sheets having enhanced anti-alkali resistance using it |
| DE10024256A1 (en) * | 2000-05-17 | 2001-11-29 | Daimler Chrysler Ag | Coating solution from several starting materials for the production of a hardened coating for preferably metallic surfaces |
| KR100508504B1 (en) * | 2000-11-22 | 2005-08-17 | 주식회사 포스코 | Resin coating solution for fuel tank with excellent welding properties and resin coated steel sheet by using it |
| KR100498094B1 (en) * | 2000-12-21 | 2005-07-01 | 주식회사 포스코 | A coating composition for fuel container having corrosion resistance adhesive and a coating method by using them |
| KR20030053762A (en) * | 2001-12-24 | 2003-07-02 | 주식회사 포스코 | A Coating Composition for Fingerprint Resistance Steel Plate Having Superior Chemical Resistance and Adhesive |
| KR100544725B1 (en) * | 2001-12-26 | 2006-01-24 | 주식회사 포스코 | Manufacturing method of resin coated steel sheet for automotive fuel tank with excellent corrosion resistance and fuel resistance |
| KR100928834B1 (en) * | 2002-12-27 | 2009-11-27 | 주식회사 포스코 | Manufacturing method of resin-coated steel sheet for automobile fuel tank |
| CN101346493B (en) * | 2005-12-27 | 2013-01-09 | Posco公司 | Surface treated Cr-free steel sheet for used in fuel tank, preparing method thereof and treatment composition therefor |
| KR100804934B1 (en) * | 2006-12-27 | 2008-02-20 | 주식회사 포스코 | Excellent heat-dissipating black resin composition, method for treating a steel sheet using the same and steel sheet treated thereby |
| US8663793B2 (en) | 2006-12-27 | 2014-03-04 | Posco | Excellent heat-dissipating black resin composition, method for treating a zinc coated steel sheet using the same and steel sheet treated thereby |
| CN101250312B (en) * | 2008-04-01 | 2010-06-16 | 长春依多科化工有限公司 | Foaming sound-proof acrylic resin vehicle bottom protective plastisol and preparation method thereof |
| TWI480422B (en) * | 2013-10-07 | 2015-04-11 | China Steel Corp | A device and method for cleaning the mouth of a zinc tank |
| KR101792240B1 (en) * | 2015-09-18 | 2017-10-31 | 주식회사 포스코 | Composition for surface-treating a single-side-plated steel sheet, surface-treated steel sheet using the same composition, and the method for surface-treatent sheet using the sam composition |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4391855A (en) * | 1980-08-25 | 1983-07-05 | Depor Industries | Corrosion resistant coating and method for coating metal substrate |
| KR100193146B1 (en) * | 1990-07-20 | 1999-06-15 | 월터 클리웨인, 한스-피터 위트린 | Stabilized Monomer Composition |
| JPH0671579B2 (en) * | 1990-11-28 | 1994-09-14 | 株式会社神戸製鋼所 | Resin coated steel sheet with excellent electrodeposition and weldability |
| JP2563006B2 (en) * | 1991-06-24 | 1996-12-11 | 新日本製鐵株式会社 | Coating composition for galvanized steel wire and galvanized steel wire for cable applied with the same |
| JPH06146010A (en) * | 1992-11-04 | 1994-05-27 | Nippon Steel Corp | Galvanized steel wire for resin coated cable |
| US5578669A (en) * | 1993-12-24 | 1996-11-26 | Nippon Paint Co., Ltd. | Water-based polyurethane coating composition |
| JPH0885187A (en) * | 1994-09-20 | 1996-04-02 | Nippon Paint Co Ltd | Laminated metallic plate and manufacture thereof |
| US5707704A (en) * | 1994-12-27 | 1998-01-13 | Kimoto Co., Ltd. | Masking films |
-
1999
- 1999-11-12 KR KR10-1999-0050110A patent/KR100402014B1/en active IP Right Grant
-
2000
- 2000-11-13 CN CN00803601A patent/CN1340087A/en active Pending
- 2000-11-13 JP JP2001537414A patent/JP3543090B2/en not_active Expired - Fee Related
- 2000-11-13 EP EP00976423A patent/EP1153095A4/en not_active Withdrawn
- 2000-11-13 WO PCT/KR2000/001297 patent/WO2001034713A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| CN1340087A (en) | 2002-03-13 |
| WO2001034713A1 (en) | 2001-05-17 |
| KR20010046371A (en) | 2001-06-15 |
| EP1153095A4 (en) | 2003-04-09 |
| JP2003514095A (en) | 2003-04-15 |
| KR100402014B1 (en) | 2003-10-17 |
| EP1153095A1 (en) | 2001-11-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3418177B2 (en) | Surface-treated steel sheet for fuel tank and method for producing the same | |
| JP5093797B2 (en) | Steel plate for containers with excellent can processability | |
| JP3543090B2 (en) | Resin-coated steel sheet for automobile fuel tank and method of manufacturing the same | |
| JP3497413B2 (en) | Surface treated steel sheet for fuel containers with excellent corrosion resistance, workability and weldability | |
| EP0119608B1 (en) | Coating composite for extended corrosion resistance | |
| JP2003518558A (en) | Resin-coated steel sheet for automobile fuel tank and method of manufacturing the same | |
| AU718855B2 (en) | Rustproof steel sheet for automobile fuel tank with excellent resistance weldability corrosion resistance and press moldability | |
| KR100396084B1 (en) | Surface-Treated Steel Sheet for Automotive Fuel Tanks and Method of Fabricating thereof | |
| JPS5815554B2 (en) | Plated steel materials for cationic electrodeposition coating | |
| JP3462869B2 (en) | Chromate treated steel sheet for automobile fuel tank and method of manufacturing the same | |
| JP3847921B2 (en) | Steel plate for high corrosion resistant fuel tank | |
| JPS6160896A (en) | Steel plate for vessel for alcohol or alcohol-containing fuel | |
| JP2578532B2 (en) | Phosphate treated Sn plated steel sheet | |
| JP3847926B2 (en) | Steel plate for high corrosion resistant fuel tank | |
| JP3934762B2 (en) | Steel plate for high corrosion resistant fuel tank | |
| JP2000017450A (en) | Automotive fuel tank excellent in corrosion resistance | |
| JP3328578B2 (en) | Steel plate for fuel tank with high corrosion resistance | |
| JPS61266596A (en) | Steel sheet for fuel container | |
| JPH0241594B2 (en) | ||
| JPH0536516B2 (en) | ||
| JPS6187881A (en) | Steel sheet for alcohol or alcoholic fuel container | |
| JPH0689475B2 (en) | Steel plate for fuel container | |
| JPS61270388A (en) | Steel sheet for fuel vessel | |
| JPS61270389A (en) | Steel sheet for fuel vessel | |
| JPH10305517A (en) | Steel plate for fuel container having high corrosion resistance |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20040305 |
|
| 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: 20040309 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20040405 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090409 Year of fee payment: 5 |
|
| LAPS | Cancellation because of no payment of annual fees |