EP3508617B1 - Surface-treated steel sheet, organic resin-coated steel sheet, and container using same - Google Patents

Surface-treated steel sheet, organic resin-coated steel sheet, and container using same Download PDF

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Publication number
EP3508617B1
EP3508617B1 EP17845989.7A EP17845989A EP3508617B1 EP 3508617 B1 EP3508617 B1 EP 3508617B1 EP 17845989 A EP17845989 A EP 17845989A EP 3508617 B1 EP3508617 B1 EP 3508617B1
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European Patent Office
Prior art keywords
steel sheet
film
tin
treatment
treated steel
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EP17845989.7A
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German (de)
English (en)
French (fr)
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EP3508617A4 (en
EP3508617A1 (en
Inventor
Naomi Taguchi
Kenji Yanada
Masahiko Matsukawa
Miwa Uchikawa
Keisuke Yoshida
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Toyo Kohan Co Ltd
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Toyo Kohan Co Ltd
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    • 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
    • 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
    • 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
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel
    • 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
    • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
    • C25D5/505—After-treatment of electroplated surfaces by heat-treatment of electroplated tin coatings, e.g. by melting
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/06—Wires; Strips; Foils
    • C25D7/0614—Strips or foils

Definitions

  • the present invention relates to a method of preparing a surface-treated steel sheet, an organic resin-coated steel sheet and a container, particularly to a method of preparing a surface-treated steel sheet, an organic resin-coated steel sheet and a container using the same which undergoes tin plating and for which generation of sulfidation blackening is restrained.
  • the chromate treatment has been known as a treatment for enhancing the adhesion of the steel sheet to an organic resin formed on its surface, and has been widely used because of excellent corrosion resistance and adhesion thereof.
  • a chromate treatment in which a cathode electrolysis treatment is conducted in an aqueous solution of sodium dichromate is used. Since the surface of a tin-plated steel sheet or tin alloy-plated steel sheet having undergone such a chromate treatment has excellent adhesion to organic resins, a barrier layer of an organic resin can be favorably formed by coating, lamination, and the like.
  • sulfidation blackening in which the container inner surface is blackened may be generated in a retort treatment step for high-temperature sterilization.
  • This is considered to be the result of a process in which a sulfur-containing amino acid component such as cysteine and methionine in the fish meat is pyrolyzed, and H 2 S or HS - ion as the pyrolytic product reacts with tin and/or iron, to form a film of tin sulfide and/or iron sulfide in the container.
  • hexavalent chromium in the chromate treatment particularly has toxicity and exerts a high burden on the environment.
  • great expense is needed for waste water treatment, exhaust treatment, waste disposal, and the like, which are generated when the chromate treatment is conducted, irrespectively of the use of hexavalent chromium.
  • the present invention has been made in consideration of solution to the above-mentioned problems. Accordingly, it is an object of the present invention to provide a method of preparing a surface-treated steel sheet, an organic resin-coated steel sheet, and a container using the same for which generation of sulfidation blackening can be restrained, while taking influences of stannous oxide and stannic oxide into account.
  • a method of preparing a surface-treated steel sheet (1) as defined in the annexed claims which steel sheet includes: a steel sheet; a tin plating layer formed on the steel sheet; and a chemical conversion film that is formed on the tin plating layer and contains essentially no chromium, in which in measurements using anode polarization, a current density ratio of a current density I1 at a potential representing a reaction of stannous oxide (SnO) after undergoing a heat treatment equivalent to coating and baking to the sum (I1 + 12), where I2 is a current density at a potential representing a reaction of stannic oxide (SnO 2 ), is less than 0.36; and wherein, in said method, the tin plating layer is formed on the steel sheet, a chemical conversion film is formed on the tin plating layer, and a current density ratio of a current density I1 at a potential representing a
  • the chemical conversion film is preferably a film containing an aluminum-oxygen compound as a main ingredient.
  • the chemical conversion film preferably further contains a phosphoric acid compound.
  • the chemical conversion film preferably contains zirconium.
  • an embodiment of the present invention there is provided a method of preparing an organic resin-coated steel sheet in which the surface-treated steel sheet is prepared by the method according to any one of (1) to (4) above and is coated with an organic resin.
  • a method of preparing a container including preparing the surface-treated steel sheet by the method according to any one of (1) to (4) above or preparing the above-mentioned organic resin-coated steel sheet.
  • the surface-treated steel sheet is preferably subjected to coating and baking.
  • stannous oxide which would cause sulfidation blackening can be restrained, and, therefore, starting points serving as generation sites of sulfidation blackening and spreading of the starting points can be restrained. Further, with stannic oxide also increased, the stannic oxide can produce an effect to function as a barrier layer for restraining reactions of the sulfur component with the surface-treated steel sheet.
  • a surface-treated steel sheet 10prepared according to the present embodiment illustrated in Fig. 1 includes a steel sheet 1 as a base material, a tin plating layer 2 formed on the steel sheet, and a chemical conversion film 3 that is formed on the tin plating layer 2 and contains essentially no chromium (hereinafter, referred to as chromium-free film 3).
  • a film (the tin plating layer 2, the chromium-free film 3, or the like) is formed on both face-side and back-side surfaces of the steel sheet 1 will be described in the following embodiment, a film may be formed on only one surface of the steel sheet 1.
  • a surface of the surface-treated steel sheet 10 may further be coated with an organic resin layer 4 to be an organic resin-coated steel sheet.
  • a current density ratio of a current density I1 at a potential representing a reaction of stannous oxide (SnO) to the sum (I1 + I2), where 12 is a current density at a potential representing a reaction of stannic oxide (SnO 2 ), is less than 0.36.
  • the steel sheet 1 as the base material need only be excellent in workability in drawing, workability in drawing and ironing, or workability in working (DTR) by drawing and unbending, and is not particularly limited.
  • a metal sheet of iron or any of various alloys or the like having a thickness of the order of 0.1 to 0.5 mm is used as the steel sheet 1.
  • a hot rolled steel sheet using an aluminum-killed steel continuous cast material as a base a cold rolled steel sheet obtained by cold rolling of the hot rolled steel sheet or the like can be used as the metal sheet.
  • a steel sheet obtained by pickling the aluminum-killed steel or the like by electrolytic pickling or the like to remove a scale on the surface, then cold rolling the steel sheet, and subjecting the steel sheet to electrolytic pickling, annealing, rolling, and the like may be used as the cold rolled steel sheet.
  • the tin plating layer 2 of the present embodiment is formed, for example, on both sides of the steel sheet 1.
  • the thickness of the tin plating layer 2 is not particularly limited, and need only be appropriately selected according to the use of the surface-treated steel sheet 10 to be manufactured.
  • the thickness in terms of tin amount is preferably not less than 0.5 g/m 2 , more preferably from 1.0 to 15 g/m 2 .
  • the tin plating layer 2 may be formed on at least one side of the steel sheet 1, as aforementioned.
  • the method for applying the tin plating layer 2 to the steel sheet 1 is not particularly limited, and examples of the method include methods using a known plating bath such as a ferrostan bath, a halogen bath, or a sulfate bath.
  • a tin-iron alloy layer may be formed between the steel sheet 1 and the tin plating layer 2 by a method in which after tin plating is conducted in the above-mentioned mode, a treatment (so-called reflow treatment) of heating to or above the melting temperature of tin and then quenching is conducted.
  • a tin-iron alloy layer is formed between the steel sheet 1 and the tin plating layer 2, whereby corrosion resistance is further enhanced.
  • a tin plating bath and its plating conditions will be set forth below.
  • tin plating is formed on a steel sheet under the following conditions.
  • ferrostan bath has been described as an example above, a halogen bath containing a tin halide as a main ingredient may be used.
  • a chromium-free film 3 of the present embodiment is a chemical conversion film that is formed on the tin plating layer 2 and contains essentially no chromium. Note that the expression "contains essentially no chromium" in the present embodiment includes a case where the chemical conversion film would inevitably contain chromium as an impurity, in addition to a mode in which the chemical conversion film does not contain any chromium component at all.
  • the current density ratio of a current density I1 at a potential representing a reaction of stannous oxide (SnO) to the sum (I1 + I2), where 12 is a current density at a potential representing a reaction of stannic oxide (SnO 2 ), is less than 0.36 can be applied as the chromium-free film 3 in the present embodiment. If the current density ratio exceeds 0.35, generation of sulfidation blackening would not be restrained, which is unfavorable.
  • Examples of such a chromium-free film 3 include a film containing a phosphoric acid compound, a film containing an aluminum-oxygen compound as a main ingredient, and a film containing zirconium.
  • a phosphoric acid compound film as the chromium-free film 3 is a layer that contains tin phosphate, and is formed by immersing a steel sheet 1 formed with the aforementioned tin plating layer 2 (hereinafter referred to also as tin-plated steel sheet) in an electrolytic treatment liquid containing phosphoric acid ions, and performing a cathode electrolysis treatment with the steel sheet 1 side as a cathode.
  • phosphoric acid H 3 PO 4
  • sodium dihydrogenphosphate NaH 2 PO 4
  • disodium hydrogenphosphate Na 2 HPO 4
  • phosphorous acid H 3 PO 3
  • the phosphoric acid and phosphates may be used either singly or as a mixture thereof; among others, a mixture of phosphoric acid with sodium dihydrogenphosphate is preferred since it can cause favorable precipitation of tin phosphate as a phosphoric acid compound film.
  • the concentration of the phosphoric acid ions in the electrolytic treatment liquid is not particularly limited, and is preferably 5 to 200 g/L in terms of the amount of phosphorus. With the concentration of the phosphoric acid ions in the electrolytic treatment liquid set in the above-mentioned range, tin phosphate can be favorably precipitated on the tin-plated steel sheet.
  • the pH of the electrolytic treatment liquid is not specifically restricted, and is preferably 1 to 7. If the pH is less than 1, the formed tin phosphate would tend to be dissolved. On the other hand, if the pH exceeds 7, dissolution of an oxide film layer on the surface of the tin-plated steel sheet would be insufficient, resulting in that it may be impossible to form a homogeneous phosphoric acid compound film on the tin-plated steel sheet, since it is difficult to form a phosphoric acid compound film on the part where the oxide film layer is much left.
  • the temperature of the electrolytic treatment liquid is preferably 30 to 60°C.
  • a current is passed while the tin-plated steel sheet immersed in the electrolytic treatment liquid containing the phosphoric acid ions is set on the cathode side, whereby tin is dissolved from the tin-plated steel sheet, to generate tin ions (Sn 2+ ).
  • the tin ions Sn 2+ generated from the tin-plated steel sheet react with the phosphoric acid ions PO 4 3- in the electrolytic treatment liquid, resulting in precipitation as tin phosphate such as Sn 3 (PO 4 ) 2 on the tin-plated steel sheet.
  • the tin ions Sn 2+ generated from the tin-plated steel sheet are precipitated also as tin oxide (SnO X ) on the tin-plated steel sheet.
  • the current density at the time of performing the cathode electrolysis treatment is not particularly limited, and is preferably 1 to 30 A/dm 2 . With the current density set in the above-mentioned range, a phosphoric acid compound film can be favorably formed on the tin-plated steel sheet.
  • the electrolytic quantity of electricity of the electrolytic treatment liquid is 1 to 10 C/dm 2 , preferably 2 to 5 C/dm 2 .
  • a counter electrode plate to be set against the tin-plated steel sheet may be any electrode plate that is not dissolved in the electrolytic treatment liquid during when the electrolytic treatment is conducted. From the viewpoint of being dissolved in the electrolytic treatment liquid with difficulty, however, a titanium plate coated with iridium oxide or a titanium plate coated with platinum is preferred.
  • the current passing time in performing the cathode electrolysis treatment is not specifically restricted, and is preferably 0.15 to 3.0 sec, more preferably 0.15 to 1.0 sec. It is necessary only to control the phosphorus content of the phosphoric acid compound film to an appropriate level, together with the current passing time.
  • the appropriate content of phosphorus in the phosphoric acid compound film is preferably 0.5 to 20 mg/m 2 , more preferably 0.5 to 5.0 mg/m 2 , and particularly preferably 0.9 to 4.0 mg/m 2 .
  • the above-mentioned PTL 2 to 4 may be further referred to.
  • the phosphoric acid compound film is not indispensable as the chromium-free film 3, and it may be omitted as required.
  • a film containing an aluminum-oxygen compound as a main ingredient (hereinafter referred to also as aluminum-oxygen compound film) as the chromium-free film 3 is formed on the tin plating layer 2 or on the phosphoric acid compound film. More specifically, for example, after washing the tin-plated steel sheet with water, the tin-plated steel sheet is subjected to an electrolytic treatment in an electrolytic treatment liquid that contains Al ions, whereby an aluminum-oxygen compound film can be precipitated on the tin-plated steel sheet.
  • specific examples of the aluminum-oxygen compound include Al 2 O 3 , Al(OH) 3 , a composite oxide with fluorine represented by AlF x O y .
  • a compound for forming Al ions in the electrolytic treatment liquid there can be used, for example, aluminum nitrate, aluminum sulfate, aluminum hydrochloride, aluminum fluoride, and the like.
  • an Al compound film which contains fluorine and is composed mainly of aluminum and oxygen can be formed on the steel sheet 1 formed with the tin plating layer 2.
  • fluorine is not indispensable but may be omitted as required, where the electrolytic treatment liquid contains F ions, the F ions function as a complexing agent for enhancing solubility of Al in the electrolytic treatment liquid.
  • the method for such an electrolytic treatment may be either of an anode electrolysis treatment and a cathode electrolysis treatment; from the viewpoint that an aluminum-oxygen compound film can be favorably formed, however, the cathode electrolysis treatment is preferred.
  • the content of Al ions in the electrolytic treatment liquid for forming the aluminum-oxygen compound film can be appropriately selected according to the film amount of the aluminum-oxygen compound film to be formed.
  • the content of Al ions in the electrolytic treatment liquid for example, in terms of mass concentration of Al atoms, is preferably 0.5 to 10 g/L, more preferably 1 to 5 g/L. Where the content of Al ions in the electrolytic treatment liquid is set in the above-mentioned range, stability of the electrolytic treatment liquid can be enhanced, and precipitation efficiency of the aluminum-oxygen compound can be enhanced.
  • At least one additive selected from among organic acids (citric acid, lactic acid, tartaric acid, glycolic acid, etc.), polyacrylic acid, polyitaconic acid, phenol resin, and the like, may be added to the electrolytic treatment liquid for forming the aluminum-oxygen compound film.
  • organic acids citric acid, lactic acid, tartaric acid, glycolic acid, etc.
  • polyacrylic acid polyitaconic acid
  • phenol resin and the like
  • the content of phosphoric acid ions in the electrolytic treatment liquid is preferably not more than 0.55 g/L, more preferably not more than 0.33 g/L, and further preferably 0.11 g/L.
  • the aluminum-oxygen compound film is a uniform one, and the appearance quality of the surface-treated steel sheet 10 is enhanced.
  • the total current passing time (the total current passing time in repeating the cycle of current passing and stopping of the current passing) for the base material is preferably not more than 1.5 sec, more preferably not more than one second.
  • the number of cycles of the current passing and the stopping of the current passing is preferably one to 10, which may be controlled together with the current passing time in such a manner that the aluminum content of the aluminum-oxygen compound film will be suitable.
  • a suitable content of aluminum in the aluminum-oxygen compound film is preferably 3 to 40 mg/m 2 , more preferably 5 to 15 mg/m 2 , and particularly preferably 5.1 to 10.6 mg/m 2 .
  • a counter electrode plate disposed against the base material may be any electrode plate that is not dissolved in the electrolytic treatment liquid during when the electrolytic treatment is conducted. From the viewpoint of demonstrating a small oxygen overvoltage and being dissolved in the electrolytic treatment liquid with difficulty, however, a titanium plate coated with iridium oxide or a titanium plate coated with platinum is preferred.
  • the pH of the electrolytic treatment liquid for forming the aluminum-oxygen compound film is preferably 1 to 5.
  • the temperature of the electrolytic treatment liquid for forming the aluminum-oxygen compound film is preferably 30 to 60°C.
  • the electrolytic quantity of electricity in the electrolytic treatment liquid for forming the aluminum-oxygen compound film is 0.1 to 5 C/dm 2 , preferably 0.2 to 1.6 C/dm 2 .
  • a zirconium film as the chromium-free film 3 can be formed by subjecting the steel sheet 1 formed with the tin plating layer 2 to cathode electrolysis in an electrolytic treatment liquid which is an aqueous solution containing Zr ions and F ions.
  • a chemical agent for forming Zr ions constituting the electrolytic treatment liquid is not particularly limited, and there can be used, for example, K 2 ZrF 6 , (NH 4 ) 2 ZrF 6 , (NH 4 ) 2 ZrO(CO 3 ) 2 , H 2 ZrF 6 , ZrO(NO 3 ) 2 , ZrO(CH 3 COO) 2 , and the like. These chemicals may be used either singly or in combination of two or more of them.
  • a Zr compound film that contains fluorine and is composed mainly of zirconium and oxygen can be formed on the steel sheet 1 formed with the tin plating layer 2.
  • fluorine is not indispensable but may be omitted as required.
  • the electrolytic treatment liquid contains F ions
  • the F ions function as a complexing agent for enhancing solubility of Zr ions in the electrolytic treatment liquid, whereby a Zr compound film having a uniform film thickness can be precipitated.
  • the amount of Zr contained in the zirconium film is preferably in the range of 5 to 50 mg/m 2 , more preferably 5 to 30 mg/m 2 .
  • the amount of F is preferably in the range of 0.3 to 10 mg/m 2 .
  • the Zr concentration in the electrolytic treatment liquid is preferably 1,000 to 10,000 ppm.
  • the F concentration in the electrolytic treatment liquid is preferably 600 to 13,000 ppm.
  • the pH of the electrolytic treatment liquid for forming the zirconium film is preferably 2 to 5, and more preferably 2.5 to 4.
  • the temperature of the electrolytic treatment liquid is preferably 30 to 60°C.
  • a chemical agent for forming F ions contained in the electrolytic treatment liquid is not specifically restricted.
  • the current density in the case of performing the electrolytic treatment is not particularly limited, and is preferably 1 to 30 A/dm 2 .
  • a counter electrode plate may be any electrode plate that is not dissolved in the electrolytic treatment during when the cathode electrolysis treatment is conducted. From the viewpoint of demonstrating a small oxygen overvoltage and being dissolved in the electrolytic treatment liquid with difficulty, however, a titanium plate coated with iridium oxide is preferred.
  • zirconium film is not indispensable as the chromium-free film 3, but may be omitted as required.
  • the above-mentioned surface-treated steel sheet 10 may be formed further with an organic resin layer 4, to be an organic resin-coated steel sheet.
  • the organic resin layer 4 includes coating films of known coating materials or the like.
  • the organic resin layer 4 also may be formed on at least one side of the steel sheet 1, like the foregoing.
  • thermoplastic resin there may be mentioned, for example, a thermoplastic resin.
  • thermoplastic resin there can be used olefin resin film of polyethylene, polypropylene, ethylene-propylene copolymer, ethylenevinyl acetate copolymer, ethylene-acrylate copolymer, ionomers, etc., polyester films of polyethylene terephthalate, polybutylene terephthalate, etc., unoriented or biaxially oriented films such as polyvinyl chloride film, polyvinylidene chloride film, etc., and polyamide films of nylon 6, nylon 6,6, nylon 11, nylon 12, etc.
  • an unoriented polyethylene terephthalate obtained by copolymerization of isophthalic acid is particularly preferred.
  • organic materials for constituting the organic resin layer may be used either singly or as a blend of different organic materials.
  • a multilayer configuration including a plurality of organic resin layers may also be adopted.
  • a thermosetting resin there can be used epoxyphenolic resins, polyester resins, and the like.
  • polyester resins are preferable since they are easy to apply and bake, they are excellent in workability, adhesion to metal and retort resistance, and they do not generate a poisonous or corrosive gas when incinerated.
  • polyester resins include polyester resins containing at least one of ethylene terephthalate, butylene terephthalate, 1,4-cyclohexanedimethyl terephthalate, ethylene isophthalate, butylene isophthalate, ethylene adipate, butylene adipate, ethylene naphthalate, and butylene naphthalate.
  • the surface-treated steel sheet 10 of the present embodiment can be formed as a container by a method in which, for example, the organic resin layer 4 is further formed thereon, to obtain an organic material-coated steel sheet, followed by working thereof.
  • Such a container include seamless cans (two-piece cans) and three-piece cans (welded cans).
  • Such a container can be manufactured by subjecting the organic material-coated steel sheet to conventionally known means such as, for example, drawing, drawing and re-drawing, bending and stretching by drawing and re-drawing, bending and stretching and ironing by drawing and re-drawing, or drawing and ironing.
  • the present inventors paid attention to the proportions of stannous oxide and stannic oxide, in regard of factors concerning the fact that a tinplate having undergone tin plating demonstrates excellent sulfidation blackening resistance. Specifically, the generation of tin sulfide (or iron sulfide) which causes the sulfidation blackening is considered to occur under an influence of the presence of stannous oxide on the surface of a tin-plated steel sheet (tinplate). It has been found that the amount of stannous oxide (SnO) increases when a heat treatment of coating and baking (approximately 150 to 210°C) is conducted in the process of can production, for example.
  • stannous oxide serves as a starting point of generation of tin sulfide which causes sulfidation blackening
  • stannic oxide functions as a barrier layer for restraining the reaction between the above-mentioned sulfur component and the steel sheet side. It is to be noted, however, that the simple presence of a large amount of stannic oxide is not favorable and that excessive growth of stannic oxide would influence, for example, a lowering in adhesion of a coating material.
  • the present embodiment based on electrochemical measurement results utilizing anode polarization measurement, a ratio between stannous oxide and stannic oxide that is preferable for restraining the generation of tin sulfide or iron sulfide has been found.
  • the present embodiment is characterized in that when a reaction due to anode polarization is utilized, the difference between a reaction of stannous oxide and a reaction of stannic oxide clearly appears as a potential difference, and stannous oxide and stannic oxide in the surface-treated steel sheet 10 can be discriminated from each other.
  • stannous oxide (SnO) stannous oxide
  • the chromium-free film 3 described in the present embodiment is not in the form of being preferentially precipitated on the tin plating like a hydrous chromium oxide film conventionally used, but an amorphous film is precipitated in such a manner as to uniformly cover the whole part of the tin plating. It is considered, therefore, that where the chromium-free film 3 of the present embodiment is applied on the tin plating, the amount of SnO on the tin-plated steel sheet is reduced as a whole due to etching, electrolysis, or the like, whereby the number of active sites for SnS generation is decreased.
  • a pretreatment step of immersion or an electrolytic treatment in an acidic or basic aqueous solution has been separately needed for reducing the amount of SnO in the tin plating layer, prior to chromate treatment.
  • the aforementioned strong etching action at the time of forming the chromium-free film 3 ensures that the same action as that of the pretreatment needed conventionally can be produced simultaneously with film formation.
  • the conventional pretreatment step is unnecessitated, and the production cost of the surface-treated steel sheet 10 can be suppressed.
  • anode polarization measurement was used in the present embodiment. More specifically, the surface-treated steel sheet 10 as an object of measurement can be subjected to anode polarization measurement by use of a potentiostat device under the following conditions.
  • model liquid is not limited to sodium sulfide nonahydrate, and other corrosive solution such as aqueous sulfuric acid solution may be used. It is to be noted that attention should be paid to the fact that each potential (potential of SnO, SnO 2 , and the like) of the film composition described later in the present embodiment is the value of the model liquid in the present embodiment. Since the value of each potential may vary if the model liquid is different, each potential required can be calculated by appropriate experiments or the like.
  • the measurement is performed by immersing the surface-treated steel sheet 10 in the model liquid.
  • a potential is applied to the anode side from an immersion potential, and, while performing polarization at a polarization rate of 50 mV/min, current density is measured at predetermined time intervals.
  • immersion potential may be measured in several tens of seconds (for example, 30 to 300 seconds), prior to anode polarization measurement, and thereafter the anode polarization measurement may be conducted.
  • Polarization curves (an example) based on the anode polarization measurement are illustrated in Fig. 2 .
  • Fig. 2 potentials of the film compositions that react with HS in the aqueous solution are indicated by arrows, and the relevant reactional formulas are represented by the following formulas.
  • the potential (-0.24 V) of SnO represents a fixed potential at which an oxidation-reduction reaction occurs in the aqueous Na 2 S ⁇ 9H 2 O solution.
  • the reaction with SnO is restrained, as compared to the case of other samples, and, further, the reactions with Fe, Sn and HS - are also restrained.
  • the chromium-free film 3 in the present embodiment can be not only restrained in its reaction with SnO, which is considered to be a starting point of generation of the sulfide, but also can be restrained in its reaction with Fe and Sn.
  • the characteristics and generation of the sulfidation blackening can be predicted, which can be applied, for example, to selection of the kind, thickness, and the like, of the chromium-free film 3 to be coated with the tin plating layer 2 based on the measurement results.
  • a cold rolled steel sheet of a low-carbon aluminum-killed steel having a thickness of 0.225 mm was used as the steel sheet 1 (base material).
  • the steel sheet 1 was degreased by cathode electrolysis at 60°C for 10 seconds using an aqueous solution of a known alkali degreasing agent.
  • the steel sheet 1 after degreasing was washed with tap water, and was pickled by immersing in a pickling treatment agent (5% aqueous sulfuric acid solution) at normal temperature for five seconds.
  • a tin plating layer 2 having a plating thickness of 2.8 g/m 2 was formed on the surface of the steel sheet using a known ferrostan bath under the following conditions, and, after washing with water, a reflow treatment was conducted, to produce a tin-plated steel sheet.
  • a chromium-free film 3 Al-oxygen compound film
  • the tin-plated steel sheet obtained was immersed in a treatment bath containing the ingredients of the following after-treatment composition liquid, and, while stirring the treatment bath, cathode electrolysis was conducted using as an anode an iridium oxide-coated titanium plate disposed at a position corresponding to an inter-electrode distance of 17 mm. Immediately after the cathode electrolysis, an after-treatment of washing with running water and drying was conducted.
  • the film amount of P and Al in the surface-treated steel sheet 10 obtained by forming the chromium-free film 3 (P and Al-oxygen compound film) was measured by a fluorescent X-ray device (produced by Rigaku Corporation; ZSX100e).
  • the surface-treated steel sheet 10 obtained as above and subjected to a heat treatment at 190°C for 10 minutes was put to the following electrochemical measurement. Further, as a comparison, the surface-treated steel sheet not subjected to the heat treatment was also put to the following electrochemical measurement.
  • such a heat treatment is conducted in a temperature range corresponding to the general coating and baking performed at the time of container production (can production or the like); for example, for the surface-treated steel sheet in the present embodiment, the heat treatment is conducted at approximately 150 to 210°C, as above-mentioned.
  • the heat treatment corresponding to coating and baking is not limited to the above-mentioned temperature range, and a suitable temperature range may be appropriately set according, for example, to the material of the base material of the surface-treated steel sheet to be treated, the kind of plating, the film thickness of the plating, etc.
  • Anode polarization measurement was conducted using the above-mentioned potentiostat device.
  • an electrochemical measurement system HAG3001 produced by Hokuto Denko Corporation was used as the measurement device.
  • an aqueous Na 2 S ⁇ 9H 2 O solution (containing 2 g/L of Na 2 S ⁇ 9H 2 O mixed therein) was used as the model liquid.
  • the pH of the model liquid was 4.7, and the liquid temperature thereof was controlled to 37°C.
  • the measurement was conducted by immersing the surface-treated steel sheet 10 obtained as above in the model liquid. Note that in Example 1, in order that the surface potential of the sample becomes stable before anode polarization measurement, the anode polarization measurement was performed after preliminary measurement of immersion potential for 50 seconds. A potential was applied to the anode side from the immersion potential, and, while performing polarization at a polarization rate of 50 mV/min, current density was measured at predetermined time intervals.
  • Example 2 Substantially the same procedure as in Example 1 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 1.2 C/dm 2 , and the thickness of the chromium-free film 3 (Al-oxygen compound film) was 10 mg/m 2 .
  • Example 2 Substantially the same procedure as in Example 1 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 0.8 C/dm 2 , and the thickness of the chromium-free film 3 (Al-oxygen compound film) was 7 mg/m 2 .
  • Example 2 Substantially the same procedure as in Example 1 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 0.6 C/dm 2 , and the thickness of the chromium-free film 3 (Al-oxygen compound film) was 5 mg/m 2 .
  • Example 2 Substantially the same procedure as in Example 1 was repeated, except that a phosphoric acid compound film was formed before the Al treatment.
  • a phosphoric acid compound film as a chromium-free film 3 (first chromium-free film) was formed on a tin-plated steel sheet. More specifically, the tin-plated steel sheet obtained as above-mentioned was immersed in the following electrolytic treatment liquid, and, while stirring the electrolytic treatment liquid, the phosphoric acid compound film was formed on the tin plating layer 2, using as an electrode an iridium oxide-coated titanium plate disposed at a position corresponding to an inter-electrode distance of 17 mm.
  • an Al-oxygen compound film as a chromium-free film 3 (second chromium-free film) was formed in a thickness of 2 mg/m 2 in substantially the same manner as in Example 1.
  • the film amounts of P and Al in the surface-treated steel sheet 10 obtained by forming the chromium-free films 3 (P and Al-oxygen compound films) were measured by a fluorescent X-ray device (produced by Rigaku Corporation; ZSX100e).
  • Example 5 Substantially the same procedure as in Example 5 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 1.2 C/dm 2 , and the thickness of the Al-oxygen compound film was 10 mg/m 2 .
  • Example 5 Substantially the same procedure as in Example 5 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 0.6 C/dm 2 , and the thickness of the Al-oxygen compound film was 5 mg/m 2 .
  • Example 5 Substantially the same procedure as in Example 5 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 0.4 C/dm 2 , and the thickness of the Al-oxygen compound film was 3 mg/m 2 .
  • a zirconium film (Zr ox ) as a chromium-free film was formed in a thickness of 10 mg/dm 2 , by a method in which a treatment liquid obtained by dissolving ammonium zirconium fluoride as a zirconium ion source and having a Zr concentration of 5,500 ppm by weight and a pH of 3.0 was used at a treatment liquid temperature of 40°C and with an electrolytic quantity of electricity of 3 C/dm 2 .
  • Example 2 Substantially the same procedure as in Example 1 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 0.2 C/dm 2 , and the thickness of the chromium-free film 3 (Al-oxygen compound film) was 2 mg/m 2 .
  • Example 2 Substantially the same procedure as in Example 1 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 0.4 C/dm 2 , and the thickness of the chromium-free film 3 (Al-oxygen compound film) was 3 mg/m 2 .
  • Example 5 Substantially the same procedure as in Example 5 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 0.2 C/dm 2 , and the thickness of the Al-oxygen compound film was 2 mg/m 2 .
  • Example 5 Substantially the same procedure as in Example 5 was repeated, except that the electrolytic quantity of electricity in the electrolytic treatment liquid for P treatment was 4.2 C/dm 2 , the electrolytic quantity of electricity in the electrolytic treatment liquid for Al treatment was 0.2 C/dm 2 , and the thickness of the Al-oxygen compound film was 2 mg/m 2 .
  • a zirconium film (Zr ox ) was formed in a thickness of 5 mg/dm 2 , using substantially the same treatment liquid as in Example 9 and with an electrolytic quantity of electricity of 1.5 C/dm 2 .
  • Example 2 After a tin-plated steel sheet was obtained in substantially the same manner as in Example 1, a chromate treatment was conducted to form a laminate structure of metallic chromium (Cr°) and a hydrous chromium oxide film (Cr ox ) , with respective thicknesses of 10 mg/dm 2 , and a total metallic Cr amount of 20 mg/dm 2 .
  • Cr° metallic chromium
  • Cr ox hydrous chromium oxide film
  • the surface-treated steel sheet obtained in each of Examples and Comparative Examples was cut to 40 mm square, and the cut sections were protected with a 3 mm wide tape, to produce a specimen.
  • the thus produced specimen was put in a test container can (produced by Toyo Seikan Co., Ltd.; J280TULC), and the test container can was filled with the following model liquid for evaluation in such a manner that the specimen was wholly immersed. Thereafter, the test container can was seamed with an aluminum lid, and a retort treatment was conducted under the conditions of 130°C and five hours.
  • test container can was opened, the degree of blackening of the specimen was observed by visual inspection, and evaluated according to the following criteria. Note that the evaluation of sulfidation blackening resistance evaluation was conducted with respect to all the Examples and Comparative Examples.
  • sulfidation blackening resistance is not limited to the case of using the above-mentioned model liquid for evaluation; for example, a real liquid present as a product in practice, such as salmon boiled plain, may also be used.
  • the surface-treated steel sheet, the organic resin-coated steel sheet and the container using the same prepared according to the present invention are sufficiently restrained from generation of sulfidation blackening, even in a situation of, for example, making contact with high protein, and are applicable to a wide field of industry.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Electrochemistry (AREA)
  • Mechanical Engineering (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Containers Having Bodies Formed In One Piece (AREA)
  • Rigid Containers With Two Or More Constituent Elements (AREA)
  • Laminated Bodies (AREA)
EP17845989.7A 2016-08-31 2017-07-28 Surface-treated steel sheet, organic resin-coated steel sheet, and container using same Active EP3508617B1 (en)

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JP2016168933A JP2018035394A (ja) 2016-08-31 2016-08-31 表面処理鋼板、有機樹脂被覆鋼板、及びこれらを用いた容器
PCT/JP2017/027469 WO2018042980A1 (ja) 2016-08-31 2017-07-28 表面処理鋼板、有機樹脂被覆鋼板、及びこれらを用いた容器

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EP4092159A4 (en) * 2020-03-26 2023-07-19 Nippon Steel Corporation SN PLATED STEEL SHEET
JP2022007321A (ja) * 2020-06-26 2022-01-13 東洋鋼鈑株式会社 表面処理鋼板、金属容器および表面処理鋼板の製造方法
JP7074953B2 (ja) * 2021-02-09 2022-05-25 東洋鋼鈑株式会社 表面処理鋼板、有機樹脂被覆鋼板、及びこれらを用いた容器

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US20180016693A1 (en) * 2015-01-26 2018-01-18 Toyo Kohan Co., Ltd. Surface-treated steel sheet, metal container, and method for producing surface-treated steel sheet
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