KR102081372B1 - Coated steel sheet having high corrosion resistance and method for manufacturing the same - Google Patents

Coated steel sheet having high corrosion resistance and method for manufacturing the same Download PDF

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KR102081372B1
KR102081372B1 KR1020170161639A KR20170161639A KR102081372B1 KR 102081372 B1 KR102081372 B1 KR 102081372B1 KR 1020170161639 A KR1020170161639 A KR 1020170161639A KR 20170161639 A KR20170161639 A KR 20170161639A KR 102081372 B1 KR102081372 B1 KR 102081372B1
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steel sheet
based alloy
alloy plating
corrosion resistance
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KR20190062944A (en
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김인규
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포스코강판 주식회사
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    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C28/00Coating 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
    • C23C28/30Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/321Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer with at least one metal alloy layer
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05DPROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05DPROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/24Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials for applying particular liquids or other fluent materials
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00Layered products comprising a layer of metal
    • B32B15/04Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING 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
    • C09D175/00Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04Polyurethanes
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C21/00Alloys based on aluminium
    • C22C21/02Alloys based on aluminium with silicon as the next major constituent
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C21/00Alloys based on aluminium
    • C22C21/06Alloys based on aluminium with magnesium as the next major constituent
    • C22C21/08Alloys based on aluminium with magnesium as the next major constituent with silicon
    • CCHEMISTRY; METALLURGY
    • C23COATING 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
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    • C23C2/00Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/12Aluminium or alloys based thereon
    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C2/00Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26After-treatment
    • CCHEMISTRY; METALLURGY
    • C23COATING 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
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    • C23C2/00Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/34Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36Elongated material
    • C23C2/40Plates; Strips
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    • C23C22/00Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
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    • C23C28/00Coating 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
    • C23C28/30Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34Coatings 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
    • BPERFORMING OPERATIONS; TRANSPORTING
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Abstract

본 발명은 내식성이 우수한 도장강판 및 그 제조방법에 관한 것으로서, 가공 또는 파손에 의해 외부로 노출되는 도장강판의 도금층 및 절단면의 내부식성을 향상시키는 것을 목적으로 한다.
이를 위하여 본 발명은, 소지강판(10); 상기 소지강판(10)의 일면 또는 양면에 형성된 Al-Si-Mg계 합금 도금층(20); 상기 Al-Si-Mg계 합금 도금층(20) 상에 형성된 하도 도막층(40); 및 상기 하도 도막층(40) 상에 형성된 상도 도막층(50)을 포함하여 이루어지고, 상기 Al-Si-Mg계 합금 도금층(20)은, 전체 중량을 기준으로 Si가 1 ~ 10 중량%, Mg가 1 ~ 10 중량%, 잔부가 Al 및 불가피한 불순물을 포함하고, 상기 Al-Si-Mg계 합금 도금층(20)의 편면 도금 부착량은 60 ~ 450mg/m2인 것을 특징으로 한다.
The present invention relates to a coated steel sheet excellent in corrosion resistance and a method for manufacturing the same, and to improve the corrosion resistance of the plated layer and the cut surface of the coated steel sheet exposed to the outside by processing or breakage.
To this end, the present invention, the steel plate 10; Al-Si-Mg-based alloy plating layer 20 formed on one side or both sides of the base steel sheet 10; A coat layer 40 formed on the Al-Si-Mg-based alloy plating layer 20; And a top coat layer 50 formed on the bottom coat layer 40, wherein the Al-Si-Mg-based alloy plating layer 20 has 1 to 10 wt% of Si, based on the total weight of the coat. Mg is 1 to 10% by weight, the balance includes Al and unavoidable impurities, the Al-Si-Mg-based alloy plating layer 20 is characterized in that the single-side plating adhesion amount is 60 ~ 450mg / m 2 .

Description

내식성이 우수한 도장강판 및 그 제조방법{COATED STEEL SHEET HAVING HIGH CORROSION RESISTANCE AND METHOD FOR MANUFACTURING THE SAME}Painted steel sheet with excellent corrosion resistance and manufacturing method thereof {COATED STEEL SHEET HAVING HIGH CORROSION RESISTANCE AND METHOD FOR MANUFACTURING THE SAME}

본 발명은 내식성이 우수한 도장강판 및 그 제조방법에 관한 것으로서, 더욱 상세하게는, 소지강판에 Al-Si-Mg계 합금 도금층을 형성함으로써, 가공 또는 파손에 의해 도장강판의 도금층 및 절단면이 외부로 노출되더라도 부식을 억제할 수 있는 고내식성 도장강판 및 그 제조방법에 관한 것이다. The present invention relates to a coated steel sheet excellent in corrosion resistance and a manufacturing method thereof, and more particularly, by forming an Al-Si-Mg-based alloy plating layer on the base steel sheet, the coating layer and the cut surface of the coated steel sheet to the outside by processing or breakage The present invention relates to a highly corrosion-resistant coated steel sheet and a method of manufacturing the same that can suppress corrosion even when exposed.

일반적으로 도장강판의 소지로는 아연도금강판이 널리 사용되고 있다. In general, galvanized steel sheet is widely used as the base of the coated steel sheet.

상기 아연도금강판은 강판의 표면에 아연(Zn)을 도금한 것으로서, 아연도금강판을 도장강판의 소지로 사용할 경우, 내부식성이 우수하고 표면 외관이 미려하다는 장점이 있다.The galvanized steel sheet is plated with zinc (Zn) on the surface of the steel sheet, when the galvanized steel sheet is used as the base of the coated steel sheet, there is an advantage of excellent corrosion resistance and beautiful surface appearance.

아연도금강판을 소지로 사용한 도장강판의 경우, 평상시에는 도장층이 모재인 철을 보호하고 있어 내부식성에 별다른 문제가 없다.In the case of a coated steel sheet using a galvanized steel sheet, there is usually no problem in corrosion resistance since the coating layer protects iron, which is a base material.

그러나 도장강판의 가공 또는 파손에 의해 도금층 및 절단면이 외부에 노출되면 도금의 열화가 진행된다.However, when the plating layer and the cut surface are exposed to the outside by the processing or breakage of the coated steel sheet, the plating deteriorates.

이렇게 열화된 부분에서는 주위의 아연도금이 희생 양극의 역할을 하여 강판의 부식을 다소 억제하기는 하지만, 계속되는 도금층의 열화를 막을 수가 없다. 즉 아연의 희생방식 기능만으로는 부식을 근본적으로 방지할 수가 없다는 문제가 있다.In such a deteriorated portion, the surrounding galvanizing serves as a sacrificial anode to somewhat suppress corrosion of the steel sheet, but it cannot prevent the deterioration of the plating layer. That is, there is a problem that the corrosion prevention function alone cannot fundamentally prevent corrosion.

특히 용융아연도금강판은, 염소가 있는 대기 환경에서 연속적으로 도금의 열화가 진행된다는 문제가 있다. In particular, hot-dip galvanized steel sheet has a problem in that plating deterioration proceeds continuously in an atmospheric environment with chlorine.

이러한 내식성 문제를 해결하기 위한 방안으로, 아연도금강판 도금층 성분에 Mg과 Al을 첨가한 Zn-Mg-Al 3원계 합금도금강판을 도장강판의 소지로 사용하는 방안이 제안된 바 있다. In order to solve this corrosion resistance problem, a method of using Zn-Mg-Al ternary alloy plated steel sheet containing Mg and Al added to the galvanized steel sheet plating layer components has been proposed.

상기한 Zn-Mg-Al 3원계 합금도금강판은, 내식성이 일반 아연도금강판에 비해 3 ~ 5배 우수한 것으로 알려져 있다. The Zn-Mg-Al ternary alloy plated steel sheet is known to have 3 to 5 times better corrosion resistance than a general galvanized steel sheet.

그러나 상기한 Zn-Mg-Al 3원계 합금도금강판은, Mg의 첨가로 인해 도금층 내에 브리틀(Brittle)한 특성을 갖는 금속간 화합물을 생성하게 된다.However, the Zn-Mg-Al ternary alloy plated steel sheet produces an intermetallic compound having brittle characteristics in the plating layer due to the addition of Mg.

이에 따라 강판의 가공시 상기 금속간 화합물에서 크랙(Crack)이 발생하게 되고, 이 크랙은 도장층까지 전파되어 제품의 가공성을 저하시키는 문제가 있다. Accordingly, when the steel sheet is processed, cracks are generated in the intermetallic compound, and the cracks propagate to the coating layer, thereby degrading the workability of the product.

또한 가공부위의 크랙이 심할 경우에는, 모재인 철이 외부에 그대로 노출되어 내식성을 저하시키게 되는 문제가 있다. In addition, when the crack of the processing site is severe, there is a problem that the base material iron is exposed to the outside as it is to lower the corrosion resistance.

현재 도장강판의 주 용도인 건자재시장을 중심으로 제품의 내구성 및 내구성의 향상과 수명연장의 요구가 증가하고 있는데, 도료적으로 내구성 및 내식성을 향상시키는데는 한계가 있다.The demand for improving the durability and durability of the product and extending the lifespan is increasing mainly in the building materials market, which is the main use of the coated steel sheet. However, there is a limit in improving the durability and corrosion resistance in paints.

상기한 요구를 충족하기 위해서는, 단가는 높지만 상대적으로 내식성이 우수한 용융알루미늄도금강판을 사용한 도장강판의 개발이 요구되고 있다. In order to meet the above requirements, development of a coated steel sheet using a molten aluminum plated steel sheet having a high unit price but relatively excellent corrosion resistance is required.

상기한 용융알루미늄도금강판은, 용융아연도금강판과 대비할 때 대기 중에서의 내식성이 5배 정도인 것으로 알려져 있다. The molten aluminum plated steel sheet is known to have about five times the corrosion resistance in the atmosphere as compared with the hot dip galvanized steel sheet.

용융아연도금과 용융알루미늄도금의 부식방식은 근본적인 차이가 있다.There is a fundamental difference between the corrosion methods of hot dip galvanizing and hot dip aluminum plating.

즉 아연도금의 경우에는 아연의 희생방식을 이용하는 반면, 알루미늄도금의 주된 부식방식은 표면층에 형성되는 알루미늄 산화막(부동태 피막)을 이용한다.That is, in the case of zinc plating, a sacrificial method of zinc is used, whereas the main corrosion method of aluminum plating uses an aluminum oxide film (dynamic film) formed on the surface layer.

상기 산화막은 대기 중에 노출됨과 동시에 도금표면에 얇게 형성되고, 이 산화막이 마모 등에 의해 제거되면 즉시 새로운 산화막이 형성되어 부식의 진행을 방지하게 된다. The oxide film is exposed to the air and formed thin on the plating surface. When the oxide film is removed by abrasion or the like, a new oxide film is formed immediately to prevent the progress of corrosion.

KR 10-2015-0003356 AKR 10-2015-0003356 A KR 10-2011-0088573 AKR 10-2011-0088573 A KR 특2002-0040771 AKR Patent 2002-0040771 A

본 발명은 상기와 같은 문제점을 해결하기 위한 것으로서, 가공 또는 파손에 의해 도장강판의 도금층 및 절단면이 외부에 노출되더라도, 부식이 효과적으로 억제되도록 하는 고내식 도장강판 및 그 제조방법을 제공하는 데 그 목적이 있다. The present invention is to solve the above problems, to provide a high corrosion-resistant coated steel sheet and a method of manufacturing the same so that corrosion is effectively suppressed even if the coating layer and the cut surface of the coated steel sheet by the processing or damage to the outside. There is this.

상기와 같은 목적을 달성하기 위한 본 발명에 따른 도장강판은, 소지강판; 상기 소지강판의 일면 또는 양면에 형성된 Al-Si-Mg계 합금 도금층; 상기 Al-Si-Mg계 합금 도금층 상에 형성된 하도 도막층; 및 상기 하도 도막층 상에 형성된 상도 도막층을 포함하여 이루어지고, 상기 Al-Si-Mg계 합금 도금층은, 전체 중량을 기준으로 Si가 1 ~ 10 중량%, Mg가 1 ~ 10 중량%, 잔부가 Al 및 불가피한 불순물을 포함하고, 상기 Al-Si-Mg계 합금 도금층의 편면 도금 부착량은 60 ~ 450mg/m2인 것을 특징으로 한다.Painted steel sheet according to the present invention for achieving the above object, the holding steel sheet; Al-Si-Mg-based alloy plating layer formed on one side or both sides of the base steel sheet; A coat layer formed on the Al-Si-Mg-based alloy plating layer; And a top coat layer formed on the undercoat layer, wherein the Al-Si-Mg-based alloy plating layer has Si in an amount of 1 to 10 wt%, Mg in an amount of 1 to 10 wt%, and a glass It contains additional Al and unavoidable impurities, the one-side plating adhesion amount of the Al-Si-Mg-based alloy plating layer is characterized in that 60 ~ 450mg / m 2 .

또한 상기 합금 도금층과 하도 도막층의 사이에 형성되는 화성 도막층을 더 포함하는 것을 특징으로 한다.In addition, it is characterized in that it further comprises a chemical conversion coating layer formed between the alloy plating layer and the undercoat coating layer.

또한 상기 상도 도막층 상에 형성되는 클리어 도막층을 더 포함하는 것을 특징으로 한다.In addition, it characterized in that it further comprises a clear coating layer formed on the top coat layer.

또한 상기 하도 도막층은, 폴리에스테르 수지, 우레탄, 불소 수지로 이루어진 군으로부터 선택된 1종 이상을 20 ~ 70 중량% 포함하고, 상기 하도 도막층의 두께는 10.0 ~ 50.0㎛인 것을 특징으로 한다.In addition, the undercoat layer comprises 20 to 70% by weight of at least one selected from the group consisting of polyester resins, urethanes and fluorine resins, and the thickness of the undercoat layer is 10.0 to 50.0 μm.

상기 상도 도막층은, 폴리에스테르 수지, 우레탄, 불소 수지 및 에폭시 수지로 이루어진 군으로부터 선택된 1종 이상을 20 ~ 70 중량% 포함하고, 상기 상도 도막층의 두께는 10.0 ~ 50.0㎛인 것을 특징으로 한다.The top coat layer comprises 20 to 70 wt% of at least one selected from the group consisting of polyester resins, urethanes, fluorine resins, and epoxy resins, and the thickness of the top coat layer is 10.0 to 50.0 μm. .

또한 상기 화성 도막층은, Cr, Zr, Si 및 Ti으로 이루어진 군으로부터 선택된 1종 이상의 금속을 5.0 ~ 20.0 중량% 포함하고, 상기 화성 도막층의 부착량은 편면 기준으로 15 ~ 100mg/m2인 것을 특징으로 한다.In addition, the chemical conversion coating layer, 5.0 to 20.0% by weight of one or more metals selected from the group consisting of Cr, Zr, Si and Ti, the coating amount of the chemical conversion coating layer is 15 to 100mg / m 2 based on one side. It features.

또한 상기 클리어 도막층은, 아크릴 수지, 멜라민 수지, 폴리에스테르 수지 및 불소 수지로 이루어진 군으로부터 선택된 1종 이상을 20 ~ 70 중량% 포함하고, 상기 클리어 도막층의 두께는 5.0 ~ 20.0㎛인 것을 특징으로 한다.In addition, the clear coating layer, 20 to 70% by weight of one or more selected from the group consisting of acrylic resin, melamine resin, polyester resin and fluorine resin, the thickness of the clear coating layer is 5.0 to 20.0㎛ It is done.

한편 본 발명에 따른 도장강판의 제조방법은, (a) 소지강판의 일면 또는 양면에 Al-Si-Mg계 합금 도금층을 형성하는 단계(S10); (b) 상기 Al-Si-Mg계 합금 도금강판의 일면에 하도 도막 조성물을 도포한 후, PMT 180 ~ 260℃의 조건으로 건조하여 하도 도막층을 형성하는 단계(S30); 및 (c) 상기 하도 도막층이 형성된 Al-Si-Mg계 합금도금강판의 일면에 상도 도막 조성물을 도포한 후, PMT 180 ~ 260℃의 조건으로 건조하여 상도 도막층을 형성하는 단계(S40)를 포함하는 것을 특징으로 한다.On the other hand, the manufacturing method of the coated steel sheet according to the present invention, (a) forming an Al-Si-Mg-based alloy plating layer on one side or both sides of the steel sheet (S10); (b) applying an undercoat film composition to one surface of the Al-Si-Mg-based alloy plated steel sheet, and then drying under conditions of PMT 180 to 260 ° C to form a undercoat film layer (S30); And (c) applying a top coat composition to one surface of the Al-Si-Mg-based alloy plated steel sheet on which the bottom coat layer is formed, and drying under conditions of PMT 180 to 260 ° C. to form a top coat layer (S40). Characterized in that it comprises a.

또한 하도 도막층을 형성하는 상기 S30 단계 이전에, Al-Si-Mg계 합금도금강판의 일면 또는 양면에 화성처리액을 도포하고, PMT 60 ~ 130℃의 조건으로 건조시켜 화성 도막층을 형성하는 단계(S20)를 더 포함하는 것을 특징으로 한다.In addition, before the step S30 of forming the undercoat layer, the chemical conversion treatment is applied to one or both surfaces of the Al-Si-Mg-based alloy plated steel sheet, and dried under the conditions of PMT 60 ~ 130 ℃ to form a chemical coating layer It further comprises a step (S20).

또한 상도 도막층을 형성하는 상기 S40 단계 이후에, Al-Si-Mg계 합금도금강판의 일면에 클리어 도료를 도포한 후, PMT 180 ~ 260℃의 조건으로 건조하여 클리어 도막층을 형성하는 단계를 더 포함하는 것을 특징으로 한다. In addition, after the step S40 of forming a top coat layer, after applying a clear paint on one surface of the Al-Si-Mg-based alloy plated steel sheet, and dried under the conditions of PMT 180 ~ 260 ℃ to form a clear coat layer It further comprises.

상기한 과제의 해결 수단은, 본 발명의 특징을 모두 열거한 것은 아니며, 본 발명의 특징과 그에 따른 장점 및 효과는 하기의 구체적인 실시형태를 참조하여 보다 상세하게 이해될 수 있을 것이다.Means for solving the above problems are not all listed the features of the present invention, the features of the present invention and its advantages and effects will be understood in more detail with reference to the following specific embodiments.

본 발명에 의하면, 내식성이 매우 우수하여, 가공 또는 파손에 의해 도장강판의 도금층 및 절단면이 외부에 노출되더라도, 부식이 효과적으로 억제되는 효과가 있다. According to the present invention, the corrosion resistance is very excellent, and even if the plating layer and the cut surface of the coated steel sheet are exposed to the outside by processing or breakage, the corrosion is effectively suppressed.

도 1은 본 발명에 따른 도장강판의 개략적인 단면도.
도 2는 본 발명에 따른 도장강판의 제조과정을 나타낸 흐름도.
1 is a schematic cross-sectional view of a coated steel sheet according to the present invention.
2 is a flow chart showing a manufacturing process of the coated steel sheet according to the present invention.

이하, 첨부된 도면을 참조하여 본 발명의 바람직한 실시예를 상세히 설명한다.Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

본 발명에 따른 내식성이 우수한 도장강판은, 도 1에 도시된 바와 같이, 소지강판(10); 상기 소지강판(10)의 일면 또는 양면에 형성된 Al-Si-Mg계 합금 도금층(20); 상기 Al-Si-Mg계 합금 도금층(20) 상에 형성된 하도 도막층(40); 및 상기 하도 도막층(40) 상에 형성된 상도 도막층(50)을 포함하여 이루어진다.Painted steel sheet excellent in corrosion resistance according to the invention, as shown in Figure 1, the holding steel plate 10; Al-Si-Mg-based alloy plating layer 20 formed on one side or both sides of the base steel sheet 10; A coat layer 40 formed on the Al-Si-Mg-based alloy plating layer 20; And a top coat layer 50 formed on the bottom coat layer 40.

여기서 상기 Al-Si-Mg계 합금 도금층(20)은, 전체 중량을 기준으로 Si가 1 ~ 10 중량%, Mg가 1 ~ 10 중량%, 잔부가 Al 및 불가피한 불순물을 포함하고, 상기 Al-Si-Mg계 합금 도금층(20)의 편면 도금 부착량은 60 ~ 450mg/m2인 것이 바람직하다. Here, the Al-Si-Mg-based alloy plating layer 20, based on the total weight of Si 1 to 10% by weight, Mg 1 to 10% by weight, the balance contains Al and unavoidable impurities, the Al-Si It is preferable that the single-side plating adhesion amount of -Mg type alloy plating layer 20 is 60-450 mg / m <2> .

본 발명에서 소지강판의 종류는 특별히 한정하지 않으며, 예를 들어 통상의 도금강판의 소지로 사용되는 열연강판 또는 냉연강판을 사용할 수 있다. In the present invention, the kind of base steel sheet is not particularly limited, and for example, a hot rolled steel sheet or a cold rolled steel sheet used as a base of a conventional plated steel sheet may be used.

다만, 열연강판의 경우에는 그 표면에 다량의 산화 스케일을 가지고 있고, 이러한 산화 스케일은 도금 밀착성을 저하시켜 도금 품질을 저하시키는 문제가 있다.However, in the case of a hot-rolled steel sheet has a large amount of oxidation scale on its surface, such an oxidation scale has a problem of lowering plating adhesion and degrading plating quality.

따라서 열연강판을 사용할 경우에는, 산 용액에 의해 미리 산화 스케일을 제거한 후 사용하는 것이 좋다.Therefore, when using a hot-rolled steel sheet, it is good to use after removing an oxidation scale with an acid solution previously.

도 1에는 상기 Al-Si-Mg계 합금 도금층(20)이 소지강판의 양면에 형성되는 것으로 도시되어 있지만, 상기 합금 도금층(20)은 소지강판의 일면에 형성될 수도 있다. Although the Al-Si-Mg-based alloy plating layer 20 is shown on both sides of the steel sheet in FIG. 1, the alloy plating layer 20 may be formed on one surface of the steel sheet.

상기 Si는, 합금 도금층(20) 내에서 Fe-Al합금층 성장을 억제하는 역할을 한다.The Si serves to suppress the Fe—Al alloy layer growth in the alloy plating layer 20.

상기 Fe-Al합금층은 유해상이라고 불리는 금속간화합물로서, 브리틀(Brittle)한 특성으로 인해 가공 시 도금층의 박리 및 크랙(Crack)을 유발하여 도장강판의 가공성을 저하시키게 된다.The Fe-Al alloy layer is an intermetallic compound called a harmful phase, and due to the brittle characteristics, it causes peeling and cracking of the plating layer during processing, thereby reducing workability of the coated steel sheet.

또한 그 함량이 과다할 경우에는 도금층 내에서 Si가 석출되어 가공 시 크랙을 유발할 수 있기 때문에, 상기 Si 함량의 상한은 10 중량%로 하는 것이 바람직하다.In addition, when the content is excessive, Si may precipitate in the plating layer, which may cause cracks during processing. Therefore, the upper limit of the Si content is preferably 10% by weight.

상기 Mg은, 표면에 부동태 산화피막을 형성시켜 도장강판의 내식성 향상에 매우 중요한 역할을 하는 원소이다. The Mg is an element that plays a very important role in improving the corrosion resistance of the coated steel sheet by forming a passivation oxide film on the surface.

즉 상기 Mg은, 도금층 내부에서 Si 성분과 반응하여 Mg2Si를 형성함으로써, 알루미늄도금강판이 희생방식 특성을 갖도록 한다.That is, the Mg reacts with the Si component in the plating layer to form Mg 2 Si, so that the aluminum plated steel sheet has sacrificial anticorrosive properties.

그러나 상기 Mg2Si 화합물의 양이 너무 많아지게 되면, 가공 시 도금층의 크랙 및 박리 현상을 유발하게 된다. 이에 따라 Mg 함량의 상한은 10 중량%인 것이 바람직하다.However, when the amount of the Mg 2 Si compound is too large, it causes cracking and peeling of the plating layer during processing. Accordingly, the upper limit of the Mg content is preferably 10% by weight.

상기 조성 이외의 나머지 성분은 Al과 기타 불가피한 불순물로 이루어진다.The remaining components other than the above composition consist of Al and other unavoidable impurities.

상기 불순물은 통상의 제조과정에서 원료 또는 주위 환경으로부터 불가피하게 혼입되는 물질을 말한다. The impurities refer to materials which are inevitably incorporated from raw materials or the surrounding environment in a conventional manufacturing process.

이러한 불순물들은 통상의 기술자에게 자명한 내용이므로, 이에 대한 상세한 설명은 생략하기로 한다.Since these impurities are obvious to those skilled in the art, a detailed description thereof will be omitted.

또한 상기 Al-Si-Mg계 합금 도금층(20)의 편면 도금 부착량은 20 ~ 200mg/m2 인 것이 바람직하다.In addition, the single-side plating adhesion amount of the Al-Si-Mg-based alloy plating layer 20 is preferably 20 to 200 mg / m 2 .

상기 합금 도금층(20)의 편면 도금 부착량이 20mg/m2 미만인 경우에는 충분한 내식성을 확보하기가 어렵고, 200mg/m2을 초과하는 경우에는 도금층의 박리 및 크랙이 발생할 가능성이 높아진다. If the single-side plating adhesion amount of the alloy plating layer 20 is less than 20 mg / m 2 , it is difficult to secure sufficient corrosion resistance, and if it exceeds 200 mg / m 2 , the possibility of peeling and cracking of the plating layer is increased.

하도 도막층(40)은, 상기 Al-Si-Mg계 합금 도금층(20) 상에 형성되며, 후술할 상도 도막층과의 밀착력을 부여하고, 도장강판의 내식성 및 가공성을 향상시키는 역할을 한다.The undercoat layer 40 is formed on the Al-Si-Mg-based alloy plating layer 20, and provides adhesion to the top coat layer, which will be described later, and serves to improve corrosion resistance and workability of the coated steel sheet.

상기 하도 도막층(40)은, 폴리에스테르(Polyester), 우레탄(Urethane), 수지 및 불소(Fluoride) 수지로 이루어진 군으로부터 선택된 1종 이상을 20~70 중량% 포함하는 것이 바람직하다. The undercoat layer 40 preferably contains 20 to 70% by weight of at least one selected from the group consisting of polyester, urethane, resin, and fluoride resin.

폴리에스테르 수지의 경우, 가공성 향상을 위해 분자량이 20,000Mw 이상인 고분자 폴리에스테르 수지인 것이 바람직하며, 필요 시 에폭시 수지를 3% 이하로 소량 첨가하여 소재와의 밀착성을 높이는 것이 좋다. In the case of the polyester resin, it is preferable that it is a high molecular polyester resin having a molecular weight of 20,000 Mw or more in order to improve processability, and if necessary, a small amount of epoxy resin is added to 3% or less to increase the adhesion with the material.

상기 수지외에 안료 및 첨가제가 더 포함될 수 있고, 상기 첨가제로는 예를 들어 소포제, 평활제, 소광제 등이 있다. In addition to the resin, pigments and additives may be further included, and the additives include, for example, antifoaming agents, leveling agents, and matting agents.

또한 상기 하도 도막층(20)의 두께는, 2.0 ~ 10.0㎛인 것이 바람직하다.Moreover, it is preferable that the thickness of the said undercoat film layer 20 is 2.0-10.0 micrometers.

상기 하도 도막층(20)의 두께가 2.0㎛ 미만이 되면 도장강판의 충분한 내식성과 가공성을 확보할 수 없고, 반면에 10.0㎛을 초과하게 되면 도장강판의 밀착성을 저하시킬 우려가 높아진다.If the thickness of the undercoat layer 20 is less than 2.0 μm, sufficient corrosion resistance and workability of the coated steel sheet may not be secured. On the other hand, if the thickness of the undercoat layer 20 exceeds 10.0 μm, the adhesion of the coated steel sheet may decrease.

상도 도막층(50)은, 상기 하도 도막층(40) 상에 형성되어 목적하는 색상을 구현하고, 도장강판에 내약품성, 내식성, 내습성, 내후성 등의 기능성을 부여하는 역할을 한다.The top coat layer 50 is formed on the bottom coat layer 40 to implement a desired color, and serves to provide functionalities such as chemical resistance, corrosion resistance, moisture resistance, and weather resistance to the coated steel sheet.

상기 상도 도막층(50)은 폴리에스테르(Polyester) 수지, 우레탄(Urethane), 불소(Fluoride) 수지 및 아크릴(acrylic) 수지로 이루어진 군으로부터 선택된 1종 이상을 20 ~ 70 중량% 포함하는 것이 바람직하다. The top coat layer 50 preferably includes 20 to 70 wt% of at least one selected from the group consisting of polyester resins, urethanes, fluoride resins, and acrylic resins. .

상기 수지 외의 잔부로서 안료 및 기타 첨가제가 첨가될 수 있고, 상기 첨가제로는 예를 들어 소포제, 평활제, 소광제 등이 있다.Pigments and other additives may be added as the remainder other than the resin, and the additives include, for example, antifoaming agents, leveling agents, quenchers and the like.

또한 상기 상도 도막층(50)의 두께는, 10.0 ~ 50.0㎛ 인 것이 바람직하다.Moreover, it is preferable that the thickness of the said top coat layer 50 is 10.0-50.0 micrometers.

상기 상도 도막층(50)의 두께가 10㎛ 미만이 되면 내약품성, 내식성, 내습성, 내후성 등의 물성이 저하되어 도장강판의 기능을 충분히 발휘하지 못할 우려가 높다. 반면에 그 두께가 50.0㎛을 초과하게 되면 도장강판의 외관이 불량해지고, 가공성 및 내열성이 저하될 우려가 높다.When the thickness of the top coat layer 50 is less than 10 μm, physical properties such as chemical resistance, corrosion resistance, moisture resistance, weather resistance, etc. are lowered, and there is a high possibility that the function of the coated steel sheet may not be sufficiently exhibited. On the other hand, when the thickness exceeds 50.0 μm, the appearance of the coated steel sheet is poor, and there is a high possibility that workability and heat resistance may be reduced.

한편, 도 1에 도시된 바와 같이, 상기 Al-Si-Mg계 합금 도금층(20)과 하도 도막층(40)의 사이에 화성 도막층(30)을 더 포함할 수 있다. Meanwhile, as illustrated in FIG. 1, a chemical conversion coating layer 30 may be further included between the Al—Si—Mg based alloy plating layer 20 and the lower coating layer 40.

상기 화성 도막층(30)은, Al-Si-Mg계 합금 도금층(20)과 하도 도막층(40) 간 의 더욱 밀착성을 향상시키고, 도장강판의 내식성을 더욱 향상시키는 역할을 한다.The chemical conversion coating layer 30 serves to further improve the adhesion between the Al-Si-Mg-based alloy plating layer 20 and the undercoat coating layer 40 and further improve the corrosion resistance of the coated steel sheet.

상기 화성 도막층(30)은, Cr, Zr, Si 및 Ti으로 이루어진 군으로부터 선택된 1종 이상의 금속을 5.0 ~ 20.0 중량% 포함하는 것이 바람직하다. It is preferable that the said chemical conversion coating layer 30 contains 5.0-20.0 weight% of 1 or more types of metals chosen from the group which consists of Cr, Zr, Si, and Ti.

상기 금속성분 외의 잔부로, 용제, 무기화합물, 표면장력조정제, 증류수 및 가교제가 포함될 수 있다. The remainder other than the metal component may include a solvent, an inorganic compound, a surface tension modifier, distilled water, and a crosslinking agent.

또한 상기 화성 도막층(30)의 부착량은, 편면 기준으로 15 ~ 100mg/m2인 것이 바람직하다. In addition, it is preferable that the adhesion amount of the said chemical conversion coating layer 30 is 15-100 mg / m <2> on a single side | surface basis.

상기 화성 도막층(30)의 부착량이 15mg/m2 미만이 되면 그 효과가 충분하지 않게 되고, 반면에 100mg/m2를 초과하게 되면 도장강판의 도장 밀착성 및 내식성을 오히려 저하시키게 된다. When the adhesion amount of the chemical conversion coating layer 30 is less than 15mg / m 2 , the effect is not sufficient, whereas when it exceeds 100mg / m 2 , the coating adhesion and corrosion resistance of the coated steel sheet is rather deteriorated.

또한 도 1에 도시된 바와 같이, 상기 상도 도막층(50) 상에 클리어 도막층(60)이 더 형성될 수도 있다.In addition, as shown in FIG. 1, a clear coating layer 60 may be further formed on the top coat layer 50.

상기 클리어 도막층(60)은, 최종 제품의 색상과 광택도를 부여하고, 최종 제품의 외관을 화학적, 기계적 마찰 등 외부 환경으로부터 보호해 주는 역할을 한다.The clear coating layer 60 provides a color and glossiness of the final product, and serves to protect the appearance of the final product from external environments such as chemical and mechanical friction.

상기 클리어 도막층(60)은, 아크릴(Acrylic) 수지, 멜라민(Melamine) 수지, 폴리에스테르(Polyester) 수지 및 불소(Fluoride) 수지로 이루어진 군으로부터 선택된 1종 이상을 20.0 ~ 70.0 중량% 포함하는 것이 바람직하다.The clear coating layer 60, 20.0 ~ 70.0% by weight of one or more selected from the group consisting of acrylic resin, melamine resin, polyester resin and fluoride resin desirable.

상기 수지 외 잔부로서 안료 및 기타 첨가제가 첨가될 수 수 있다. 상기 첨가제로는 예를 들어 소포제, 평활제, 소광제 등이 있으며, 그 종류는 특별히 한정하지 않는다. Pigments and other additives may be added as the remainder other than the resin. Examples of the additives include antifoaming agents, leveling agents, and matting agents, and the kind thereof is not particularly limited.

또한 상기 클리어 도막층(60)의 두께는, 5.0 ~ 20.0㎛인 것이 바람직하다.Moreover, it is preferable that the thickness of the said clear coat layer 60 is 5.0-20.0 micrometers.

상기 클리어 도막층(60)의 두께가 5.0㎛ 미만이 되면 도장강판의 외관을 보호하는 기능이 저하될 우려가 높고, 반면에 20.0㎛를 초과하게 되면 도장강판의 가공성 및 광택에 악영향을 미칠 우려가 높다.If the thickness of the clear coating layer 60 is less than 5.0㎛ high risk of protecting the appearance of the coated steel sheet is high, while if it exceeds 20.0㎛ there is a fear that adversely affects the workability and gloss of the coated steel sheet high.

이어서 도 2를 참고하여 본 발명에 따른 내식성이 우수한 도장강판의 제조방법에 대하여 설명한다.Next, with reference to Figure 2 will be described a method for producing a coated steel sheet excellent in corrosion resistance according to the present invention.

먼저, 소지강판의 일면 또는 양면에 Al-Si-Mg계 합금 도금층(20)을 형성한다(S10).First, the Al-Si-Mg-based alloy plating layer 20 is formed on one or both surfaces of the steel sheet (S10).

상기 Al-Si-Mg계 합금도금강판을 준비하는 단계에 대해서는 특별히 한정하지 않으며, 통상의 용융도금 또는 전기도금 방식을 사용할 수 있다. The step of preparing the Al-Si-Mg-based alloy plated steel sheet is not particularly limited, and a conventional hot dip plating or electroplating method may be used.

또한 이러한 준비에는, Al-Si-Mg계 합금도금강판의 표면에 잔존하는 스케일이나 먼지 등의 이물질을 제거하는 과정이 포함될 수 있다.In addition, the preparation may include a process of removing foreign substances such as scale or dust remaining on the surface of the Al-Si-Mg-based alloy plated steel sheet.

이어서 상기 Al-Si-Mg계 합금도금강판의 일면에 하도 도막 조성물을 도포한 후, PMT(Peak Metal Temperature) 180 ~ 260℃의 조건으로 건조하여 하도 도막층(40)을 형성한다(S30).Subsequently, after coating the undercoat composition on one surface of the Al-Si-Mg-based alloy plated steel sheet, the undercoat layer 40 is dried under conditions of 180 to 260 ° C of PMT (Peak Metal Temperature) to form the undercoat layer 40 (S30).

상기 PMT는 건조 과정 중 강판이 받는 최고 온도를 의미하는데, 하도 도막층 (40)형성시 PMT가 180℃ 미만일 경우에는, 하도 도막층(40)이 완전히 건조되지 아니하여 제품의 외관에 악영향을 주게 된다. The PMT means the highest temperature that the steel sheet receives during the drying process. When the PMT is less than 180 ° C. when the undercoat layer 40 is formed, the undercoat layer 40 is not completely dried, thereby adversely affecting the appearance of the product. do.

반면에 상기 PMT가 260℃를 초과하는 경우에는, 하도 도막층(40) 내 수지 성분의 변형을 일으킬 수 있고, 이로 인해 최종 제품의 외관 결함을 야기할 가능성이 높아지게 된다. On the other hand, when the PMT exceeds 260 ° C., deformation of the resin component in the undercoat layer 40 may occur, thereby increasing the likelihood of causing an appearance defect of the final product.

또한 하도 도막층(40)을 형성하는 S30 단계 이전에, Al-Si-Mg계 합금도금강판의 일면 또는 양면에 화성처리액을 도포하고, PMT 60 ~ 130℃의 조건으로 건조시켜 화성 도막층(30)을 형성하는 단계(S20)가 더 포함될 수 있다. In addition, before the S30 step of forming the undercoat layer 40, a chemical conversion treatment solution is applied to one or both surfaces of the Al-Si-Mg alloy plated steel sheet, and dried under conditions of PMT 60 to 130 ° C. 30 may be further included (S20).

화성 도막층(30) 형성시, 상기 PMT가 60℃ 미만일 경우에는 부착성이 저하될 우려가 높고, 반면에 130℃를 초과하는 경우에는 경화반응이 일어나지 않고 열량손실만 가져오게 되는 결과를 초래한다. In the formation of the chemical conversion coating layer 30, when the PMT is less than 60 ° C., there is a high possibility that the adhesiveness is lowered. On the other hand, when the temperature is over 130 ° C., the curing reaction does not occur and only a calorie loss occurs. .

이어서, 하도 도막층(40)이 형성된 Al-Si-Mg계 합금도금강판의 일면에 상도 도막 조성물을 도포한 후, PMT 180 ~ 260℃의 조건으로 건조하여 상도 도막층(50)을 형성한다.Subsequently, after coating the top coat composition on one surface of the Al-Si-Mg alloy plating steel sheet on which the undercoat layer 40 is formed, the top coat layer 50 is formed by drying under the conditions of PMT 180 to 260 ° C.

상도 도막층(50) 형성시, 상기 PMT가 180℃ 미만일 경우에는 상도 도막층(50)이 완전히 건조되지 아니하여 제품의 외관에 악영향을 주게 된다. When the top coat layer 50 is formed, when the PMT is less than 180 ° C., the top coat layer 50 is not completely dried, which adversely affects the appearance of the product.

반면에 상기 PMT가 260℃를 초과하는 경우에는, 상도 도막층(50) 내 수지 성분이 변형을 일으킬 수 있고, 도막층의 황변현상이 발생하게 되어 구현하고자 하는 색상과 차이가 나게 된다. 이에 따라 최종 제품에 외관 결함이 발생하게 된다.On the other hand, when the PMT exceeds 260 ° C., the resin component in the top coat layer 50 may cause deformation, and yellowing of the coat layer may occur, which may be different from the color to be implemented. This results in appearance defects in the final product.

또한 상도 도막층(50)을 형성하는 S40 단계 이후에, 상도 도막층(50)이 형성된 Al-Si-Mg계 합금도금강판의 일면에 클리어 도료를 도포한 후, PMT 180 ~ 260℃의 조건으로 건조하여 클리어 도막층(60)을 형성하는 단계(S50)를 더 포함할 수 있다.In addition, after the S40 step of forming the top coat layer 50, a clear paint is applied to one surface of the Al-Si-Mg-based alloy plated steel sheet on which the top coat layer 50 is formed, and then under conditions of 180 ° F to 260 ° C. Drying may further include forming a clear coating layer 60 (S50).

클리어 도막층(60) 형성시, 상기 PMT가 180℃ 미만일 경우에는, 클리어 도막층(60)이 완전히 건조되지 아니하여 제품의 외관에 악영향을 주게 된다. When the PMT is less than 180 ° C. at the time of forming the clear coating layer 60, the clear coating layer 60 is not completely dried and adversely affects the appearance of the product.

반면에 상기 PMT가 260℃를 초과하는 경우에는, 클리어 도막층(60) 내 수지 성분이 변형을 일으킬 수 있고, 도막층의 황변현상이 발생하게 되어 구현하고자 하는 색상과 차이가 나게 된다. 이에 따라 최종 제품에 외관 결함이 발생하게 된다.On the other hand, when the PMT exceeds 260 ° C., the resin component in the clear coating layer 60 may cause deformation, and yellowing of the coating layer may occur, which is different from the color to be implemented. This results in appearance defects in the final product.

한편, 화성처리액, 하도 도막 조성물, 상도 도막 조성물 및 클리어 도료를 도포하는 방식은 특별히 한정되지 아니한다. 예를 들어 접촉식인 경우에는 롤코팅 방식으로, 비접촉식인 경우에는 다이코팅 방식으로 도포할 수 있다.In addition, the method of apply | coating a chemical conversion treatment liquid, an undercoat coating composition, a topcoat coating composition, and a clear coating is not specifically limited. For example, in the case of a contact type, it may be applied by a roll coating method, and in the case of a non-contact type, a die coating method.

또한, 건조 수단은 적외선을 이용한 IR 히터(Infrared Ray Heater), 인덕션 히터(Induction Heater) 및 열풍오븐(Dry Oven) 등의 열원을 사용하는 것이 바람직하나, 이에 한정하는 것은 아니다. In addition, the drying means preferably uses heat sources such as an IR heater (Infrared Ray Heater), an induction heater (Induction Heater) and a hot air oven (Dry Oven) using an infrared ray, but is not limited thereto.

이하 본 발명에 의해 제조된 도장강판의 시험예를 설명한다. Hereinafter, a test example of the coated steel sheet produced by the present invention.

먼저 편면 도금 부착량이 80mg/m2 인 Al-Si-Mg계 합금도금강판을 준비하여, 하도 도막 조성물(아크릴 35 중량%, 안료 10 중량%, 용제 50 중량% 및 기타 첨가제 5중량% 함유)을 도포한 후, PMT 220℃의 조건으로 건조하여 건조 도막 두께 5.0㎛의 하도 도막층을 형성하였다.First, an Al-Si-Mg-based alloy plated steel sheet having a single-sided plating amount of 80 mg / m 2 was prepared, and the undercoat composition (containing 35 wt% acrylic, 10 wt% pigment, 50 wt% solvent, and 5 wt% other additives) was prepared. After apply | coating, it dried on the conditions of PMT 220 degreeC, and formed the undercoat film layer of dry coating film thickness of 5.0 micrometers.

이어서 하도 도막층이 형성된 합금도금강판의 표면에 상도 도막 조성물(불소수지 35 중량%, 안료 10 중량%, 용제 50 중량% 및 기타 첨가제 5 중량% 함유)을 도포한 후, PMT 249℃의 조건으로 건조하여 건조 도막 두께 20.0㎛의 상도 도막층을 형성하여 도장강판(발명예 1)을 제조하였다.Subsequently, a top coat composition (containing 35 wt% of fluororesin, 10 wt% of pigment, 50 wt% of solvent, and 5 wt% of other additives) was applied to the surface of the alloy coated steel sheet on which the undercoat layer was formed, and then under the conditions of PMT 249 ° C. It dried and formed the top coat layer of 20.0 micrometers in dry coat film thickness, and manufactured the coated steel plate (invention example 1).

그리고 위와 같이 제조된 도장강판의 내식성 평가를 위해, 7.0mm(폭)× 15.0mm(너비)의 크기로 시편을 절단하고, ASTM D B1117에 준하는 염수분무규격시험에 의해 2000시간 동안 부식촉진시험을 수행한 후, 평면 X-CUT부 및 절단 단면부에서의 백청 발생 여부 및 도막 부풀음 전파 깊이를 측정하였다.In order to evaluate the corrosion resistance of the coated steel sheet manufactured as described above, the specimen was cut to a size of 7.0 mm (width) x 15.0 mm (width), and subjected to a corrosion promotion test for 2000 hours by a salt spray standard test according to ASTM D B1117. After performing, the white rust and the coating film swelling propagation depth were measured in the planar X-CUT section and the cut section.

한편, 본 발명과의 비교를 위해, 편면 도금 부착량이 80mg/m2 인 통상의 아연도금강판을 준비하고, 상기 발명예와 동일한 조건으로 그 표면에 하도 도막층 및 상도 도막층을 형성하여 도장강판(비교예 1)을 제조한 후, 그 내식성을 평가하였다.On the other hand, for comparison with the present invention, a conventional galvanized steel sheet having a single-side plating adhesion amount of 80 mg / m 2 is prepared, and a coated steel sheet is formed by forming a coat layer and a top coat layer on the surface under the same conditions as the above-described invention. After the (Comparative Example 1) was produced, the corrosion resistance thereof was evaluated.

그 결과, 발명예 1과 비교예 1 모두, X-CUT 부위에서 백청 및 도막 부풀음은 발생하지 않았다. As a result, in both invention example 1 and comparative example 1, white rust and coating film swelling did not generate | occur | produce in the X-CUT site | part.

그러나 절단 단면부에서, 발명예 1은 백청이 발생하지 않았지만, 비교예 1은 백청이 발생하였다. However, in the cut end part, inventive example 1 did not generate white rust, but the comparative example 1 produced white rust.

또한 절단 단면부에서 발명예 1의 도막 부풀음 전파 깊이는 0 mm인 반면, 비교예 1의 도막 부풀음 전파 깊이는 2.0 mm로 나타났다.In addition, the coating film swelling propagation depth of Inventive Example 1 was 0 mm in the cut section, whereas the coating film swelling propagation depth of Comparative Example 1 was 2.0 mm.

이로써 본 발명에 따른 도장강판은, 아연도금강판에 비해 단면부 내식성이 현저히 향상됨을 확인할 수 있었다. As a result, it was confirmed that the coated steel sheet according to the present invention significantly improved the cross-section corrosion resistance compared with the galvanized steel sheet.

이상에서는 본 발명의 바람직한 실시예를 예시적으로 설명한 것으로서 본 발명의 범위는 상기한 특정 실시예에 한정되지 아니한다. 해당 기술분야에서 통상의 지식을 가진 자라면 본 발명의 기술적 사상의 범위를 벗어남이 없이 다양한 변경 및 수정이 가능하다는 것을 이해할 수 있을 것이다. As mentioned above, the preferred embodiment of the present invention has been exemplarily described, and the scope of the present invention is not limited to the above-described specific embodiment. Those skilled in the art will understand that various changes and modifications can be made without departing from the scope of the present invention.

10: 소지강판
20: Al-Si-Mg계 합금 도금층
30: 화성 도막층
40: 하도 도막층
50: 상도 도막층
60: 클리어(Clear) 도막층
10: steel plate
20: Al-Si-Mg alloy plating layer
30: Mars coating layer
40: undercoat layer
50: top coat layer
60: clear coating layer

Claims (10)

소지강판(10);
상기 소지강판(10)의 일면 또는 양면에 형성된 Al-Si-Mg계 합금 도금층(20);
상기 Al-Si-Mg계 합금 도금층(20) 상에 형성된 하도 도막층(40); 및
상기 하도 도막층(40) 상에 형성된 상도 도막층(50)을 포함하여 이루어지고,
상기 Al-Si-Mg계 합금 도금층(20)은, 전체 중량을 기준으로 Si가 1 ~ 10 중량%, Mg가 1 ~ 10 중량%, 잔부가 Al 및 불가피한 불순물을 포함하고,
상기 Al-Si-Mg계 합금 도금층(20)의 편면 도금 부착량은 60 ~ 450mg/m2이며,
상기 합금 도금층(20)과 하도 도막층(40)의 사이에 형성되는 화성 도막층(30)을 더 포함하고,
상기 상도 도막층(50) 상에 형성되는 클리어 도막층(60)을 더 포함하며,
상기 하도 도막층(40)은, 폴리에스테르(Polyester) 수지, 우레탄(Urethane), 불소(Fluoride) 수지로 이루어진 군으로부터 선택된 1종 이상을 20 ~ 70 중량% 포함하고, 상기 하도 도막층(40)의 두께는 10.0 ~ 50.0㎛이며,
상기 상도 도막층(50)은, 폴리에스테르(Polyester) 수지, 우레탄(Urethane), 불소(Fluoride) 수지 및 에폭시(Epoxy) 수지로 이루어진 군으로부터 선택된 1종 이상을 20 ~ 70 중량% 포함하고, 상기 상도 도막층의 두께는 10.0 ~ 50.0㎛이며,
상기 화성 도막층(30)은, Cr, Zr, Si 및 Ti으로 이루어진 군으로부터 선택된 1종 이상의 금속을 5.0 ~ 20.0 중량% 포함하고, 상기 화성 도막층(30)의 부착량은 편면 기준으로 15 ~ 100mg/m2이며,
상기 클리어 도막층(60)은, 아크릴(Acrylic) 수지, 멜라민(Melamine) 수지, 폴리에스테르(Polyester) 수지 및 불소(Fluoride) 수지로 이루어진 군으로부터 선택된 1종 이상을 20 ~ 70 중량% 포함하고, 상기 클리어 도막층(60)의 두께는 5.0 ~ 20.0㎛인 것을 특징으로 하는 내식성이 우수한 도장강판.
Holding steel plate (10);
Al-Si-Mg-based alloy plating layer 20 formed on one side or both sides of the base steel sheet 10;
A coat layer 40 formed on the Al-Si-Mg-based alloy plating layer 20; And
It comprises a top coat layer 50 formed on the undercoat layer 40,
The Al-Si-Mg-based alloy plating layer 20, based on the total weight of Si 1 to 10% by weight, Mg 1 to 10% by weight, the balance contains Al and unavoidable impurities,
One-side plating adhesion amount of the Al-Si-Mg-based alloy plating layer 20 is 60 ~ 450mg / m 2 ,
Further comprising a chemical conversion coating layer 30 formed between the alloy plating layer 20 and the undercoat film layer 40,
Further comprising a clear coating layer 60 formed on the top coat layer 50,
The undercoat layer 40 may include 20 to 70 wt% of at least one selected from the group consisting of polyester resin, urethane, and fluoride resin, and the undercoat layer 40 The thickness of 10.0 ~ 50.0㎛,
The top coat layer 50 may include 20 to 70 wt% of at least one selected from the group consisting of polyester resins, urethanes, fluoride resins, and epoxy resins. The thickness of the top coat layer is 10.0 ~ 50.0㎛,
The chemical conversion coating layer 30 includes 5.0 to 20.0% by weight of at least one metal selected from the group consisting of Cr, Zr, Si, and Ti, and the adhesion amount of the chemical conversion coating layer 30 is 15 to 100 mg based on one side. / m 2 ,
The clear coating layer 60 includes 20 to 70% by weight of one or more selected from the group consisting of acrylic resins, melamine resins, polyester resins and fluoride resins. The coated steel sheet excellent in corrosion resistance, characterized in that the thickness of the clear coating layer 60 is 5.0 ~ 20.0㎛.
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