Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/10—Electroplating with more than one layer of the same or of different metals
• • 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
  • C23C2/08—Tin or alloys based thereon
• • 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/26—After-treatment
• • 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/26—After-treatment
  • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
• • 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
  • C23C22/00—Chemical 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
  • C23C22/05—Chemical 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
  • C23C22/06—Chemical 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
  • C23C22/07—Chemical 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 containing phosphates
• • 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
  • C23C22/00—Chemical 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
  • C23C22/05—Chemical 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
  • C23C22/06—Chemical 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
  • C23C22/07—Chemical 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 containing phosphates
  • C23C22/08—Orthophosphates
• • 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
  • C23C22/00—Chemical 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
  • C23C22/05—Chemical 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
  • C23C22/06—Chemical 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
  • C23C22/07—Chemical 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 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/20—Orthophosphates containing aluminium cations
• • 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
  • C23C22/00—Chemical 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
  • C23C22/73—Chemical 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 characterised by the process
• • 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
  • C23C28/321—Coatings 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
• • 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
• • 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
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/36—Phosphatising
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/30—Electroplating: Baths therefor from solutions of tin
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/48—After-treatment of electroplated surfaces

Definitions

• This disclosure relates to tin-plated steel sheets for use in DI cans, food cans, beverage cans, and the like, and particularly relates to a tin-plated steel sheet having a chemical conversion coating containing no chromium (Cr) on the surface and a method for manufacturing the same.
• tin-plated steel sheets As surface-treated steel sheets for use in cans, tin-plated steel sheets referred to as “tinplates” have been widely used.
• a chromate coating is formed on the tin-plated surface of the steel sheets by chromate treatment such as immersing the steel sheet in an aqueous solution containing a hexavalent chromium compound such as dichromic acid, or electrolyzing the steel sheet in the solution.
• chromate treatment such as immersing the steel sheet in an aqueous solution containing a hexavalent chromium compound such as dichromic acid, or electrolyzing the steel sheet in the solution.
• Japanese Examined Patent Application Publication No. 55-24516 discloses a method for surface-treating a tin-plated steel sheet. The method includes forming a chemical conversion coating by performing direct current electrolysis using the tin-plated steel sheet as a cathode in a phosphoric acid solution.
• Japanese Examined Patent Application Publication No. 58-41352 discloses a chemical conversion solution containing phosphate ions, one or more of chlorates and bromates, and tin ions and having a pH of 3 to 6.
• 49-28539 discloses a surface treatment method, for tinplates, including applying one or more of calcium phosphates, magnesium phosphates, and aluminum phosphates so that the coating thickness is 15 ⁇ g/m 2 or lower.
• Japanese Unexamined Patent Application Publication No. 2005-29808 discloses a surface-treated steel sheet, for containers, successively having an iron (Fe)-nickel (Ni) diffusion layer, an Ni layer, and an Ni—Sn alloy layer, a non-alloyed Sn layer and further having 1 to 100 mg/m 2 of a phosphate coating layer in terms of phosphorus (P) on the steel sheet surface.
• Japanese Unexamined Patent Application Publication No. 2007-239091 discloses a method for manufacturing a tin-plated steel sheet including plating a steel sheet with tin, immersing the tin-plated steel sheet in a chemical conversion solution containing tin ions and phosphate ions or subjecting the steel sheet to cathodic electrolysis in a chemical conversion solution, and then heating the same to 60 to 200° C. to form a chemical conversion coating, thereby suppressing degradation of appearance and reduction in paint adhesion caused by oxidization of the tin-plated surface to a degree equal to or higher than the suppression degree obtained by conventional chromate coatings.
• JP '091 has a problem that a heating unit used subsequently to chemical conversion is necessary and therefore the cost of chemical conversion is high.
• a tin-plated steel sheet including an Sn-containing plating layer in which the mass per unit area of Sn is 0.05 to 20 g/m 2 and which is disposed on at least one surface of the steel sheet; a first chemical conversion coating which contains P and Sn, in which the mass per unit area of P is 0.3 to 10 mg/m 2 , and which is disposed on the Sn-containing plating layer; and a second chemical conversion coating which contains P and Al, in which the mass per unit area of P is 1.2 to 10 mg/m 2 and the mass per unit area of Al is 0.24 to 8.7 mg/m 2 , and which is disposed on the first chemical conversion coating.
• a tin-plated steel sheet can be manufactured by the following method: a method including forming an Sn-containing plating layer on at least one surface of a steel sheet such that the mass per unit area of Sn is 0.05 to 20 g/m 2 , immersing the steel sheet in a chemical conversion solution containing tetravalent tin ions and phosphate ions or cathodically electrolyzing the steel sheet in the chemical conversion solution, immersing the steel sheet in a chemical conversion solution containing 5 to 200 g/L of aluminum phosphate monobasic and having a pH of 1.5 to 2.4 or cathodically electrolyzing the steel sheet in this chemical conversion solution, and then drying the steel sheet.
• Drying is preferably performed at a temperature of lower than 60° C.
• a chemical conversion coating of the tin-plated steel sheet can be formed at a high line speed of 300 m/minute or more similarly as in the case of the current chromate treatment.
• a tin-plated steel sheet successively includes an Sn-containing plating layer, a first chemical conversion coating containing P and Sn, and a second chemical conversion coating containing P and Al on at least one surface of a general cold-rolled steel sheet for cans using low carbon steel or extremely low carbon steel.
• the Sn-containing plating layer is formed on at least one surface of the steel sheet.
• the mass per unit area of Sn needs to be 0.05 to 20 g/m 2 . This is because when the mass per unit area of Sn is lower than 0.05 g/m 2 , the corrosion resistance is poor and when the mass per unit area of Sn exceeds 20 g/m 2 , the plating layer thickness increases, which causes an increase in cost.
• the mass per unit area of Sn can be measured by coulometry or surface analysis using fluorescence X-rays.
• the Sn-containing plating layer is not particularly limited and is preferably a plating layer such as a plating layer containing an Sn layer (hereinafter referred to as “Sn layer”), a plating layer having a two-layer structure in which an Sn layer is formed on an Fe—Sn layer (hereinafter referred to as “Fe—Sn layer/Sn layer”), a plating layer having a two-layer structure in which an Sn layer is formed on Fe—Sn—Ni layer (hereinafter referred to as “Fe—Sn—Ni layer/Sn layer”), or a plating layer having a three-layer structure in which an Fe—Sn—Ni layer and an Sn layer are successively formed on an Fe—Ni layer (hereinafter referred to as “Fe—Ni layer/Fe—Sn—Ni layer/Sn layer”).
• a plating layer such as a plating layer containing an Sn layer (hereinafter referred to as “Sn layer”),
• the Sn-containing plating layer may be a continuous plated layer or a discontinuous layer with a dotted pattern.
• the Sn-containing plating layer can be formed by a known process.
• the Sn-containing plating layer can be formed by electroplating a steel sheet with Sn using a usual tin phenolsulfonate plating bath, tin methanesulfonate plating bath, or tin halide plating bath such that the mass per unit area is 2.8 g/m 2 , performing reflow treatment at a temperature equal to or higher than the melting point of Sn, that is, 231.9° C., to form a plating layer of Fe—Sn layer/Sn layer, performing cathodic electrolysis at 1 to 3 A/dm 2 in a 10 to 15 g/L aqueous sodium carbonate solution to remove an Sn oxide film formed on the surface after the reflow treatment, and washing the steel sheet with water.
• the plating layer containing Ni among the above-described Sn-containing plating layers can be formed by plating a steel sheet with nickel before tin plating and, as required, performing annealing treatment or performing reflow treatment or the like after tin plating.
• the first chemical conversion coating which contains P and Sn
• the Sn-containing plating layer is provided on the Sn-containing plating layer.
• a chemical conversion solution containing tetravalent tin ions and phosphate ions is used as described in detail below, similarly as in the current chromate treatment.
• the mass per unit area of P in the chemical conversion coating needs to be 0.3 to 10 mg/m 2 . This is because, when the mass per unit area of P is lower than 0.3 mg/m 2 , the surface coverage of the coating becomes insufficient.
• the first chemical conversion coating can be formed by immersing the plated steel sheet in a chemical conversion solution containing tetravalent tin ions and phosphate ions or cathodically electrolyzing the plated steel sheet in the chemical conversion solution.
• the steel sheet may be washed with water after the immersion treatment or the cathodic electrolysis treatment.
• the reason why the chemical conversion solution containing tetravalent tin ions and phosphate ions is used is to form the chemical conversion coating at a high line speed of 300 m/minute or more as described above. More specifically, tetravalent tin ions have high solubility and a larger number of tetravalent tin ions can be added compared with the case of divalent tin ions.
• the second chemical conversion coating containing P and Al is provided on the above-described first chemical conversion coating. This is because when a chemical conversion coating containing P and Al is formed, degradation of appearance and reduction in paint adhesion can be suppressed to a degree equal to or higher than the suppression degree obtained by conventional chromate coatings simply by drying at low temperatures without positively heating after chemical conversion treatment. The reason is not clear, but is believed to be because a dense chemical conversion coating of phosphate having stronger barrier properties to the oxidization of the tin-plated layer is formed by introduction of Al into the chemical conversion coating.
• the mass per unit area of P in the chemical conversion coating needs to be 1.2 to 10 mg/m 2 and the mass per unit area of Al therein needs to be 0.24 to 8.7 mg/m 2 .
• the mass per unit area of P is lower than 1.2 mg/m 2 or the mass per unit area of Al is lower than 0.24 mg/m 2 , an effect of suppressing oxidization of the tin-plated surface becomes insufficient.
• the appearance deteriorates and paint adhesion decreases with time and when the mass per unit area of P exceeds 10 mg/m 2 , the cohesive failure of the coating itself occurs.
• the paint adhesion is likely to decrease.
• the upper limit of the mass per unit area of Al of 8.7 mg/m 2 is a stoichiometrically derived value when the total amount of the coating is occupied by aluminum phosphate tribasic.
• the mass per unit area of P is lower than 10 mg/m 2 , the value does not exceed this value.
• the mass per unit area of P or the mass per unit area of Al in the chemical conversion coating can be measured by surface analysis using fluorescence X-rays.
• the second chemical conversion coating can be formed by immersing the steel sheet having the first chemical conversion coating in a chemical conversion solution containing 5 to 200 g/L of aluminum phosphate monobasic and having a pH of 1.5 to 2.4 or cathodically electrolyzing the steel sheet having the first chemical conversion coating in this chemical conversion solution, and then drying the steel sheet. After the immersion or cathodic electrolysis treatments, the steel sheet may be washed with water, and then may be dried. In this case, based on the following reason, the chemical conversion solution containing 5 to 200 g/L of aluminum phosphate monobasic and having a pH of 1.5 to 2.4 is used.
• the content of the aluminum phosphate monobasic is lower than 5 g/L, the mass per unit area of Al in the coating is not sufficient and strong barrier properties to the oxidization of the tin-plated layer is not obtained.
• the content of the aluminum phosphate monobasic exceeds 200 g/L, the stability of the chemical conversion solution is deteriorated, a precipitate is formed in the chemical conversion solution and adheres to the surface of the tin-plated steel sheet, which causes a degradation of appearance and a reduction in paint adhesion.
• the pH of the chemical conversion solution is lower than 1.5, the deposition of the coating becomes difficult and a sufficient mass per unit area cannot be secured even when the treatment time is extremely prolonged to several 10 seconds.
• the pH of the chemical conversion solution exceeds 2.4, the deposition of the coating rapidly occurs and thus the control of the mass per unit area becomes difficult.
• Drying is preferably performed at a temperature lower than 60° C. This is because the chemical conversion coating formed by the manufacturing method can sufficiently suppress oxidization of the tin-plated layer even when the drying temperature is lower than 60° C. Thus, a particular heating facility is unnecessary.
• the drying temperature is the peak temperature of the steel sheet.
• the amount of the aluminum phosphate monobasic is preferably adjusted to 60 to 120 g/L.
• the cathodic electrolysis treatment is more preferable than the immersion treatment. It is more preferable to generate hydrogen gas by cathodic electrolysis to consume protons near the interface between the tin-plated surface and the chemical conversion solution to thereby forcibly increase the pH.
• 1 to 20 g/L of orthophosphoric acid can be blended to adjust the pH or increase the reaction rate described below.
• the pH of the chemical conversion solution can be adjusted by adding acid or alkali such as phosphoric acid, sulfuric acid or sodium hydroxide.
• a promoter such as FeCl 2 , NiCl 2 , FeSO 4 , NiSO 4 , sodium chlorate, or nitrite salt; an etching agent such as a fluorine ion; and/or a surfactant such as sodium lauryl sulfate or acetylene glycol can be appropriately added.
• the temperature of the chemical conversion solution is preferably set to 70° C. or more. This is because when the temperature is set to 70° C. or more, the reaction rate increases with an increase in temperature and treatment at a higher line speed can be achieved. However, when the temperature is excessively high, the evaporation rate of moisture from the chemical conversion solution increases and the composition of the chemical conversion solution changes with time.
• the temperature of the chemical conversion solution is preferably 85° C. or lower.
• the treatment time is preferably set to 2.0 seconds or lower in total similarly as in the current chromate treatment.
• the treatment time is more preferably 1 second or lower.
• the treatment can be performed at the current line speed of 300 m/minute or more.
• the current density during the cathodic electrolysis treatment is preferably adjusted to 10 A/dm 2 or lower. This is because when the current density exceeds 10 A/dm 2 , changes in the mass per unit area to changes in the current density become high, which makes it difficult to secure a stable mass per unit area.
• To form a chemical conversion coating there is a method using application or anode electrolysis treatment in addition to the immersion treatment or the cathodic electrolysis treatment.
• the former treatment is likely to cause surface reaction unevenness, which makes it difficult to obtain uniform appearance and, in the latter method, the coating is likely to be deposited in a powder shape. Thus, degradation of appearance or degradation of paint adhesion is likely to occur. Thus, these methods are not preferable.
• the raw material used to form a steel sheet was:
• cathodic electrolysis was performed at a current density of 1 A/dm 2 in an aqueous 10 g/L sodium carbonate solution having a bath temperature of 50° C. Thereafter, immersion treatment was performed at a treatment time shown in Tables 1 and 2 or cathodic electrolysis treatment was performed at a current density and a treatment time shown in Tables 1 and 2 using a chemical conversion solution containing orthophosphoric acid and stannic chloride pentahydrate and having a temperature as shown in Tables 1 and 2. Then, wringing was performed by a wringer roll, followed by washing with water was performed.
• the mass per unit area of Sn in the Sn-containing plating layer, the mass per unit area of P in the first chemical conversion coating, and the mass per unit area of P and the mass per unit area of Al in the second chemical conversion coating were measured by the above-described method.
• the produced tin-plated steel sheets were evaluated for the appearance immediately after the production, the amount of the Sn oxide film and the appearance after long-term storage, the paint adhesion, and the corrosion resistance by the following methods.
• Amount of Sn oxide film and appearance after long-term storage The tin-plated steel sheets were stored for 10 days under an environment of 60° C. and a relative humidity of 70%. Then, the appearance was visually observed and also the amount of the Sn oxide film formed on the surface was evaluated as follows by electrolyzing with a current density of 25 uA/cm 2 in an electrolysis solution which was a 1/1000 N HBr solution, and determining the amount of electricity required for electrochemical reduction. When evaluated as A or B, the amount of Sn oxide film after long-term storage was small and the appearance was also good.
• Paint adhesion An epoxy phenol paint was applied to the tin-plated steel sheets immediately after production so that the mass per unit area was 50 mg/dm 2 , and then cured at 210° C. for 10 minutes. Subsequently, the two painted tin-plated steel sheets were laminated so that the coated surfaces face each other with a nylon adhesion film interposed therebetween, and pressure-bonded to each other under the bonding conditions of a pressure of 2.94 ⁇ 10 5 Pa, a temperature of 190° C., and a pressure-bonding time of 30 seconds. Then, the laminate was divided into test pieces having a width of 5 mm. Then, the test pieces were torn off using a tensile testing machine and evaluated as follows by measuring the strength. When evaluated as A or B, the paint adhesion was good. The same paint adhesion evaluation was also performed after the tin-plated steel sheets were stored for six months at a room temperature environment.
• Corrosion resistance An epoxy phenol paint was applied to the tin-plated steel sheets so that the mass per unit area was 50 mg/dm 2 , and then cured at 210° C. for 10 minutes. Subsequently, the steel sheets were immersed in a commercially-available tomato juice at 60° C. for 10 days. Then, the stripping of the paint and the generation of rust were visually evaluated. When evaluated as A or B, the corrosion resistance was good.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Electrochemistry (AREA)
• Inorganic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Thermal Sciences (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Chemical Treatment Of Metals (AREA)
• Electroplating Methods And Accessories (AREA)
• Coating With Molten Metal (AREA)

Applications Claiming Priority (3)

Related Parent Applications (1)

Related Child Applications (1)

Publications (1)

Family

ID=41507153

Family Applications (2)

Family Applications After (1)

Country Status (9)

Cited By (2)

Families Citing this family (6)

Citations (3)

Family Cites Families (8)

• 2008
  • 2008-07-10 JP JP2008179680A patent/JP5338163B2/ja not_active Expired - Fee Related
• 2009
  • 2009-07-02 MY MYPI20106102 patent/MY152832A/en unknown
  • 2009-07-02 CN CN200980126866.4A patent/CN102089462B/zh active Active
  • 2009-07-02 EP EP09794486.2A patent/EP2312017B1/de not_active Not-in-force
  • 2009-07-02 US US13/003,091 patent/US20110168563A1/en not_active Abandoned
  • 2009-07-02 ES ES09794486T patent/ES2412781T3/es active Active
  • 2009-07-02 KR KR1020117000306A patent/KR101290986B1/ko active IP Right Grant
  • 2009-07-02 WO PCT/JP2009/062493 patent/WO2010005042A1/ja active Application Filing
  • 2009-07-03 TW TW098122645A patent/TWI428476B/zh active
• 2013
  • 2013-12-18 US US14/132,090 patent/US9441310B2/en active Active

Patent Citations (3)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events