WO2015045624A1 - 表面処理鋼板、有機樹脂被覆金属容器、並びに表面処理鋼板の製造方法 - Google Patents
表面処理鋼板、有機樹脂被覆金属容器、並びに表面処理鋼板の製造方法 Download PDFInfo
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- WO2015045624A1 WO2015045624A1 PCT/JP2014/070500 JP2014070500W WO2015045624A1 WO 2015045624 A1 WO2015045624 A1 WO 2015045624A1 JP 2014070500 W JP2014070500 W JP 2014070500W WO 2015045624 A1 WO2015045624 A1 WO 2015045624A1
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- steel sheet
- treated steel
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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
- C25D9/00—Electrolytic coating other than with metals
- C25D9/04—Electrolytic coating other than with metals with inorganic materials
- C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
- C25D9/10—Electrolytic coating other than with metals with inorganic materials by cathodic processes on iron or steel
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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
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/12—Process control or regulation
-
- 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
- C25D3/54—Electroplating: Baths therefor from solutions of metals not provided for in groups C25D3/04 - C25D3/50
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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
- C25D7/00—Electroplating characterised by the article coated
Definitions
- the present invention relates to a surface-treated steel sheet, an organic resin-coated metal container, and a method for producing a surface-treated steel sheet.
- chromate treatment has been known as a treatment for improving the adhesion between steel sheet and organic coating, and it has been widely used due to its excellent corrosion resistance and adhesion.
- There are two types of chromate treatment one containing hexavalent chromium and the other containing no hexavalent chromium.
- hexavalent chromium is used as a starting material, Regardless of the situation, there is an increasing trend to ban the inclusion of hexavalent chromium in the starting material itself.
- a chromate treatment of the type in which hexavalent chromium does not remain is used in the final product, and usually, coating with an organic resin or the like is further performed thereon.
- cathodic electrolysis of a tin-plated steel plate in an aqueous solution of sodium dichromate cathodic electrolysis treatment of a steel plate in a fluoride-containing chromic anhydride aqueous solution, or treatment of an aluminum alloy with phosphoric acid chromate and an organic resin thereon The one coated with is used.
- Patent Document 1 an immersion treatment using a treatment liquid containing Zr (zirconium) or Ti (titanium) has been proposed as a non-chromium-based surface treatment being studied for steel sheets.
- the surface-treated steel sheet by Zr or Ti immersion treatment is inferior in the corrosion resistance of the coating, and the coating deposition rate is slower than the electrolytic chromic acid-treated steel sheet (TFS) conventionally used as a can material.
- TFS electrolytic chromic acid-treated steel sheet
- the problem was that the productivity was remarkably inferior.
- Zr and / or Ti treatment and / or Al treatment using cathodic electrolysis have been proposed as high-speed treatment processes instead of immersion treatment, all of which form a metal oxygen compound on the surface of the substrate at high speed. It is known that it can be made (Patent Documents 2, 3, and 4).
- the surface of the metal oxygen compound film is 80 ° C. or higher.
- Patent Document 6 A technique relating to a method for producing a steel plate for containers having a chemical conversion coating with a metal Zr content of 1 to 100 mg / m 2 and an F content of 0.1 mg / m 2 or less is disclosed (Patent Document 6). ).
- the degree of processing is large, the underlying iron is likely to be exposed by processing, or the adhesion to the organic resin is likely to decline, so ensuring the corrosion resistance by increasing the coating amount and simultaneously with the organic resin There was a need to improve the adhesion of the.
- Another problem to be solved by the present invention is to prevent the components constituting the metal container from eluting into the contents.
- maintaining the quality of the contents is very important, and special attention must be paid to the dissolution of components from the metal containers into the contents.
- typical examples of elution of metallic components of containers are iron elution due to corrosion and elution of anions such as sulfate ions and fluorine ions in the coating.
- metal surface treatment It is necessary to pay attention to many things such as the coating amount and surface morphology of the film, or the adhesion strength with organic resin coatings such as films and coatings.
- Patent Document 5 shows an example in which the surface of a metal oxygen compound coating on a metal plating layer is washed with hot water to improve adhesion.
- a large coating amount as described above it has been found that cleaning of electrolytic chromic acid-treated steel plates that have been used conventionally is insufficient to achieve the desired surface treatment characteristics and elution control. It was.
- the conventional electrolytic chromic acid treatment line it requires longer cleaning time than the conventional washing, so that the operation speed of the surface treatment line is restricted or the treatment tank for washing.
- there are many problems such as productivity load and energy use load, such as using a large amount of hot water.
- the present invention has been made in view of such a situation, and its purpose is to provide a surface-treated steel sheet having excellent adhesion and corrosion resistance with an organic resin layer when an organic resin layer is formed on the surface, and an organic resin. It is in providing the organic resin coating container excellent in adhesiveness and fluorine elution tolerance, and the manufacturing method of the said surface-treated steel plate.
- a surface-treated steel sheet having a compound coating mainly containing Zr and containing F on at least one surface of the steel sheet, wherein the amount of Zr in the coating is 80 to 350 mg / m 2.
- a surface-treated steel sheet is provided in which the amount is 0.5 to 10 mg / m 2 .
- an organic resin-coated metal container prepared using the surface-treated steel sheet.
- a method for producing a surface-treated steel sheet comprising a compound coating mainly containing Zr and containing F on at least one surface of the steel sheet, wherein the steel sheet is in an aqueous solution containing Zr ions and F ions.
- the steel sheet is in an aqueous solution containing Zr ions and F ions.
- the ion-containing aqueous solution in the surface conditioning step is an alkaline aqueous solution containing one or more ions of sodium ion, ammonium ion, and potassium ion; 2.
- the pH of the ion-containing aqueous solution in the surface conditioning step is 9 or more, Is preferred.
- a method for producing a surface-treated steel sheet comprising a compound coating mainly containing Zr and containing F on at least one surface of a steel sheet, wherein the steel sheet is in an aqueous solution containing Zr ions and F ions.
- a surface conditioning step of controlling the F content in the coating to 0.5 to 10 mg / m 2.
- an organic resin layer when an organic resin layer is formed on the surface, it is possible to provide a surface-treated steel sheet having excellent adhesion to the organic resin layer and excellent corrosion resistance, and excellent adhesion to the organic resin and fluorine elution resistance.
- An organic resin-coated metal container can be provided, and a method for producing the surface-treated steel sheet can be provided.
- the present invention after forming the organic resin layer on the surface, it is possible to effectively prevent peeling of the organic resin layer even when subjected to processing or heat treatment, and the organic resin layer is cracked, Surface-treated steel sheet that can hardly corrode even when the metal surface is exposed in a wet environment and can suppress the elution of the metal component components of the container, an organic resin-coated metal container using the surface-treated steel sheet, and the surface-treated steel sheet
- the manufacturing method of can be provided.
- the surface conditioning step with ion-containing water according to the present invention is used, the hot water cleaning that has been conventionally used for cleaning electrolytic chromic acid-treated steel sheets can be changed to warm water or room temperature water, and only hot water cleaning is used. Compared with the case, the processing time is short, and the manufacturing method of the surface treatment steel plate excellent in energy load can be provided.
- the surface-treated steel sheet of the present invention is a surface-treated steel sheet having a compound coating containing F and mainly Zr on at least one surface of the steel plate, wherein the amount of Zr in the coating is 80 to 350 mg / m 2 . It is an important feature that the F amount is 0.5 to 10 mg / m 2 .
- the method for producing a surface-treated steel sheet according to the present invention is a method for producing a surface-treated steel sheet in which a compound film containing F and containing Zr as a main component is formed on at least one surface of a steel sheet, wherein Zr ions and F ions are produced.
- the ion-containing aqueous solution in the surface adjustment step is an alkaline aqueous solution containing one or more ions of sodium ion, ammonium ion, and potassium ion, and the pH of the ion-containing aqueous solution in the surface adjustment step is 9 or more. Is preferable.
- a method for producing a surface-treated steel sheet in which a compound coating containing F and containing Zr as a main component is formed on at least one surface of a steel sheet, comprising Zr ions and F ions.
- the surface-treated steel sheet obtained by the present invention is usually used as a metal container member such as a can having an organic resin layer formed on the metal compound film on the surface.
- a metal container member such as a can having an organic resin layer formed on the metal compound film on the surface.
- Compound coating containing F and mainly Zr A compound coating containing F and containing Zr as a main component is considered to have an amorphous structure such as ZrO x (OH) YZ F Z. It is considered that this film is dehydrated by drying or firing and F is lost and changes to an oxide film having a large amount of crystal components, and eventually becomes a film close to ZrO 2 when heating proceeds. However, excessive heating that exceeds the thermal history experienced by normal cans induces cracks in the coating due to structural changes, and results in a more ceramic-like coating. This is not preferable because it causes a decrease in adhesion. Thus, most of the coating, it is preferable to place basically minimum F or OH bear structured as ZrO x (OH) Y-Z F Z remaining.
- the Zr amount needs to be 80 mg / m 2 or more, preferably 100 mg / m 2 or more.
- the amount of Zr was less than 80 mg / m 2 , the cross-cut corrosion resistance after the organic resin coating and the organic resin adhesion after the retort were insufficient.
- the amount of Zr exceeds 350 mg / m 2 , the coating is deposited more than necessary, which is not preferable because it is not economical and the work adhesion gradually decreases.
- the decrease in adhesion with the resin coating film during retort is considered to be caused by elution of the coating components and alkali generation by the cathode reaction, thereby inducing interfacial peeling between the coating resin and the metal coating. Therefore, removing F more than necessary in the coating suppresses the elution of F from the coating, while increasing the amount of Zr ensures the coating of the coating, and the cathode as a reverse reaction of the anode reaction. It is important to make the reaction difficult to occur. On the other hand, when the F amount is extremely reduced, the structural change of the coating is induced, the cohesive strength of the coating is reduced, and the corrosion resistance in the cross-cut test with the resin-coated metal plate is reduced.
- the amount of Zr of the surface treatment film formed on the substrate is required to be at least 80 mg / m 2 or more, more preferably 100 mg / m 2 or more.
- the amount of Zr is less than 80 mg / m 2 , the cross-cut corrosion resistance after the organic resin coating and the organic resin adhesion after the retort are insufficient.
- the F amount of the surface treatment film it is necessary to control the F amount of the surface treatment film to 10 mg / m 2 or less. If the amount of F exceeds 10 mg / m 2 and is present in the film more than necessary, a part of the film structure is hydrated in the hydrothermal sterilization process such as retort, causing structural change and existing in the film. F, which is an excessive anion, is likely to elute, causing a decrease in adhesion to the resin coating due to the elution of the coating components. However, on the other hand, as described above, it must be avoided to reduce F extremely. F is also an active ingredient necessary for the coating. When the F content is less than 0.5 mg / m 2 , the structural change of the coating proceeds due to hydration, and the corrosion resistance decreases due to a decrease in the cohesive strength of the coating.
- the form of the organic resin coating and the metal container is not particularly limited, but the polyester resin-coated seamless can prepared by processing the precoated surface-treated steel sheet coated with the polyester resin is an organic resin. It is most preferably used in terms of adhesion to the coating film, elution resistance of the metal component of the container, cross-cut corrosion resistance, and the like.
- this invention is a manufacturing method of a surface treatment steel plate, Comprising: In a film formation process, by carrying out cathode electrolysis of the steel plate in the aqueous solution containing Zr ion and F ion, F is formed on at least one side of the steel plate. A compound coating containing Zr as a main component is formed so that the amount of Zr is 80 to 350 mg / m 2 .
- the steel sheet after forming the compound film is squeezed with a roll of an electrolytic solution, then washed with water, and further squeezed with rinsing water with a roll, and then sent to the next surface adjustment step.
- the steel sheet after forming the compound film may be subjected to the next surface adjustment step without rinsing after the electrolytic solution is squeezed with a roll.
- Zr ions and F ions are included as essential components in the electrolytic treatment solution used in the film forming step.
- the electrolytic treatment liquid used in the film forming step may contain components other than Zr ions and F ions.
- Certain Fe ions may be included.
- the agent for forming the Zr ions constituting the electrolytic treatment solution is not particularly limited, 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 can be used.
- the above-mentioned drugs may be used alone or in combination of two or more.
- a treatment liquid containing F ions in addition to the Zr ions described above as the electrolytic treatment liquid.
- the F ions act as a complexing agent for enhancing the solubility of Zr ions in the electrolytic treatment liquid.
- the Zr compound can be precipitated, and therefore the adhesion between the coating and the organic resin layer can be further improved.
- F in the electrolytic treatment solution is small, local precipitation of Zr occurs, and the presence of the film results in a film with poor film thickness uniformity in which a thick part and a thin part are mixed, resulting in adhesion after processing. And a film with poor corrosion resistance. Therefore, in the film forming step, it is necessary to manage the molar ratio F / Zr in the film so that the molar ratio F / Zr of F to Zr in the film is 0.6 or more.
- an electrolytic processing liquid for example, zirconium ammonium fluoride, aluminum fluoride, titanium fluoride, sodium fluoride, ammonium fluoride, hydrofluoric acid , Calcium fluoride, hexafluorosilicic acid, sodium hexafluorosilicate, and the like can be used. Among them, a drug having high solubility in water is preferable.
- an electrolyte such as nitrate ion or ammonium ion is added to the electrolytic treatment liquid within a range not impeding the formation of the Zr compound film for the purpose of improving the conductivity in the treatment liquid and adjusting the pH of the treatment liquid. Also good.
- one or more additives among organic acids such as citric acid, lactic acid, tartaric acid and glycolic acid, and polymer compounds such as polyacrylic acid, polyitaconic acid and phenol resin are added to the electrolytic treatment solution. It may be.
- the formed Zr compound film can contain an additive such as an organic acid or a phenol resin.
- adhesion to the organic resin layer can be further improved.
- the current density when the cathodic electrolysis treatment is performed on the substrate is not particularly limited, but is preferably 1 to 30 A / dm 2 .
- the cathodic electrolysis treatment when performing the cathodic electrolysis treatment on the base material, it is preferable to use an intermittent electrolysis method in which a cycle of energization and deenergization is repeated.
- the total energization time for the base material (cycle of energization and deenergization) Is preferably 0.3 to 20 seconds.
- the counter electrode installed on the base material may be anything as long as it does not dissolve in the electrolytic processing solution during the cathode electrolytic treatment.
- a titanium plate coated with iridium oxide is preferred because it has a low overvoltage and is difficult to dissolve in the electrolytic treatment solution.
- the surface-treated steel sheet obtained by forming a compound coating containing F and containing Zr as a main component in the coating forming step is immersed and sprayed with an ion-containing aqueous solution. Or cathodic electrolysis in the aqueous solution, and the amount of F in the coating is controlled to 0.5 to 10 mg / m 2 by this treatment, and then the ion-containing aqueous solution is formed from the steel sheet. After squeezing with a roll, it is rinsed with water, and further after squeezing flush water with a roll, it is dried with hot air or the like.
- a surface-treated steel sheet obtained by forming a compound film mainly containing Zr and containing F on the base material in the above-mentioned film formation process Spray and / or dipping treatment is performed with water at a temperature of not lower than ° C., and the F amount in the coating is controlled to 0.5 to 10 mg / m 2 by this treatment. After squeezing, dry.
- water at 90 ° C. or higher as described in a comparative example, in order to make the F content in the film in the range of 0.5 to 1.0 mg / m 2 , it takes 3 seconds to adjust the surface. It is insufficient.
- the surface adjustment process has the following two meanings.
- the resin-coated and can-molded container is gradually heated in a hydrothermal sterilization process such as retort, and a part of the film structure is gradually hydrated to cause a structural change.
- OH and F which are excessive anions present therein, are easily eluted into the contents. Therefore, the 1st meaning has the meaning which reduces the excess anion in a film in the surface adjustment process beforehand, before resin coating is given as a material for cans.
- the surface conditioning step if one or more ions of Na + , NH 4 + , K + are contained in the aqueous solution, these ions easily bind to F as an anion, so that F is efficiently removed. It is effective to do. Moreover, in the surface adjustment step, it is preferable to make the pH of the aqueous solution itself alkaline. As a result, the F in the film tends to exist in the form of free F ions rather than in the form of complex ions, and can be removed more efficiently. In the surface adjustment step, the pH of the ion-containing aqueous solution is more preferably 9 or more. As described above, the F amount can be controlled to 10 mg / m 2 or less by the surface adjustment step.
- the second meaning is not to reduce F excessively.
- Appropriate F is also an active ingredient necessary for the coating, and when F is not present or extremely small, the structural change of the coating is likely to proceed due to hydration, resulting in a decrease in the cohesive strength of the coating. Induces a decrease in corrosion resistance. Therefore, it is necessary to control the F amount to 0.5 mg / m 2 or more by the surface adjustment step.
- the total amount of Na + , NH 4 + and K + ions contained in the aqueous solution is preferably 0.001 mol / l or more, more preferably 0.01 mol / l or more, and 0.02 mol / l. More preferably, it is 1 or more.
- pH of this aqueous solution is 9 or more.
- the effect of removing F in the coating is greater than that obtained by immersion only by applying cathodic electrolysis treatment in an ion-containing aqueous solution.
- the electric conductivity of the ion-containing aqueous solution used for the cathodic electrolysis is preferably larger from the viewpoint of efficiency, but is preferably at least 2 mS / cm or more.
- the ion source of the ion-containing aqueous solution used in the surface conditioning step is not particularly limited, but ammonia, ammonium zirconium carbonate, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, sodium phosphate, sodium hydrogen phosphate, potassium hydroxide, Those exhibiting alkalinity such as potassium carbonate and sodium borate are preferable, and those having high solubility in water are more preferable. Further, it is more preferable to provide a buffering action by combining two or more kinds of alkalis or alkaline compounds, such as adding sodium hydroxide to an aqueous sodium carbonate solution.
- ammonia-ammonium chloride sodium bicarbonate- Examples thereof include sodium carbonate, sodium hydrogen carbonate-sodium hydroxide, disodium hydrogen phosphate-sodium hydroxide, potassium chloride-sodium hydroxide, boric acid-potassium chloride-sodium hydroxide, glycine-sodium hydroxide.
- various surfactants and chelating agents can be added to the ion-containing aqueous solution as necessary.
- the temperature of the ion-containing aqueous solution is not particularly limited, but is preferably 40 ° C. or higher, and more preferably 60 ° C. or higher.
- the total treatment time for immersion, spraying, cathodic electrolysis and the like in the ion-containing aqueous solution is preferably 0.5 to 5 seconds, and more preferably within 0.5 to 3 seconds.
- the surface conditioning step it is preferable to perform cathodic electrolysis with an ion-containing aqueous solution.
- treatment with an ion-containing aqueous solution and treatment with immersion or spraying with warm water or hot water of about 40 ° C. to 95 ° C. may be used in combination.
- a method for producing a surface-treated steel sheet can be obtained.
- the surface-treated steel sheet using the method for producing a surface-treated steel sheet obtained according to the present invention is excellent in the adhesion of the organic resin layer when the organic resin layer is formed on the surface.
- the organic resin layer can be prevented from being peeled even when the molding process and contents are filled and the retort treatment is performed.
- corrosion does not easily proceed, and elution of the metal component component of the container can be suppressed.
- Step substrate examples of the steel sheet include hot rolled steel sheets based on aluminum-killed steel continuous cast materials, cold rolled steel sheets obtained by cold rolling these hot rolled steel sheets, Zn, Sn, Ni, A steel plate provided with a metal plating layer containing Cu, Al, or the like can be used.
- the purpose of increasing the amount of Zr targeted by the present invention is based on a steel plate that does not have a metal plating layer or that has iron exposed on a part of the surface even if it has a plating layer. Most preferably used as a material.
- the thickness of the substrate is not particularly limited and may be appropriately selected depending on the intended use, but is preferably 0.07 to 0.4 mm.
- Organic resin coating it does not specifically limit as resin which comprises the organic resin layer which coat
- thermoplastic resins examples include polyethylene, polypropylene, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic ester copolymers, olefin resin films such as ionomers, polyethylene terephthalate, poly Polyethylene film such as butylene terephthalate, or non-stretched or biaxially stretched thermoplastic film such as nylon 6, nylon 6,6, nylon 11, nylon 12 or other polyamide film, polyvinyl chloride film, polyvinylidene chloride film, etc. It may be. Among these, non-oriented polyethylene terephthalate obtained by copolymerizing isophthalic acid is particularly preferable. Moreover, the resin for constituting such an organic resin layer may be used alone, or may be used by blending different resins.
- thermoplastic resin When the thermoplastic resin is coated as the organic resin coating, it may be a single resin layer or a multilayer resin layer formed by coextrusion or the like.
- a polyester resin having a composition with excellent adhesion is selected for the base layer, that is, the surface-treated steel sheet, and the surface layer is excellent in content resistance, that is, extraction resistance and non-adsorption of flavor components. This is advantageous because polyester resins having different compositions can be selected.
- Examples of multilayer polyester resin layers are shown as surface layer / lower layer, polyethylene terephthalate / polyethylene terephthalate / isophthalate, polyethylene terephthalate / polyethylene / cyclohexylene dimethylene / terephthalate, polyethylene terephthalate / isophthalate with low isophthalate content.
- Polyethylene terephthalate / isophthalate having a high phthalate / isophthalate content polyethylene terephthalate / isophthalate / [blend of polyethylene terephthalate / isophthalate and polybutylene terephthalate / adipate] and the like are of course not limited thereto.
- the thickness ratio of the surface layer to the lower layer is preferably in the range of 5:95 to 95: 5.
- known compounding agents for resins such as anti-blocking agents such as amorphous silica, inorganic fillers, various antistatic agents, lubricants, antioxidants, ultraviolet absorbers, etc. are blended according to known formulations. can do.
- anti-blocking agents such as amorphous silica
- inorganic fillers such as inorganic fillers, various antistatic agents, lubricants, antioxidants, ultraviolet absorbers, etc.
- tocopherol vitamin E
- Tocopherol has been conventionally known as an antioxidant to prevent a decrease in molecular weight due to oxidative decomposition during heat treatment of a polyester resin and to improve dent resistance.
- Tocopherol is blended with a polyester composition blended as a modified resin component, not only the dent resistance, but also when the film is cracked due to severe conditions such as retort sterilization and hot bender, It is possible to prevent the corrosion from proceeding from the crack and to obtain the effect that the corrosion resistance is remarkably improved.
- Tocopherol is preferably blended in an amount of 0.05 to 3% by weight, particularly 0.1 to 2% by weight.
- the thickness of the organic resin coating applied to the surface-treated steel sheet obtained by the present invention is desirably 3 to 50 ⁇ m, particularly 5 to 40 ⁇ m in general for the thermoplastic resin coating.
- the thickness is preferably in the range of 1 to 50 ⁇ m, particularly 3 to 30 ⁇ m. When the thickness is less than the above range, the corrosion resistance becomes insufficient, and when the thickness exceeds the above range, a problem is likely to occur in terms of workability.
- Formation of the organic coating on the surface-treated steel sheet obtained by the present invention can be performed by any means.
- thermoplastic resin coating extrusion coating, cast film thermal bonding, biaxially stretched film thermal bonding
- the extrusion coating method it can be manufactured by extrusion coating a polyester resin in a molten state on a surface-treated metal material and thermally bonding it. That is, after the polyester resin is melt-kneaded with an extruder, it is extruded from a T-die into a thin film, and the extruded molten resin film is passed together with a surface-treated metal material between a pair of laminating rolls to be pressed and integrated under cooling. Then quench rapidly.
- an extruder for surface layer resin and an extruder for lower layer resin are used, and the resin flow from each extruder is merged in a multiple multilayer die, and thereafter a single layer Extrusion coating may be performed as in the case of resin. Further, by passing a surface-treated metal material vertically between a pair of laminate rolls and supplying a molten resin web on both sides thereof, a polyester resin coating layer can be formed on both sides of the substrate.
- an organic coated surface-treated steel sheet having an organic coating made of a polyester resin by the extrusion coating method is specifically performed as follows. If necessary, the surface-treated steel sheet is preheated by a heating device and supplied to a nip position between a pair of laminate rolls. On the other hand, the polyester resin is extruded in the form of a thin film through a die head of an extruder, supplied between the laminate roll and the surface-treated steel sheet, and pressed onto the surface-treated steel sheet by the laminate roll.
- the laminating roll is maintained at a constant temperature, and a thin film made of a thermoplastic resin such as polyester is pressure-bonded to the surface-treated steel sheet to thermally bond them together and cooled from both sides to obtain an organic-coated surface-treated steel sheet.
- a thin film made of a thermoplastic resin such as polyester is pressure-bonded to the surface-treated steel sheet to thermally bond them together and cooled from both sides to obtain an organic-coated surface-treated steel sheet.
- the formed organic-coated surface-treated steel sheet is further cooled in order to guide it to a cooling water tank or the like to prevent thermal crystallization.
- the polyester resin layer has a low crystallinity level and a difference from the amorphous density of 0.05 g / cm 3 or less due to selection of the resin composition and rapid cooling with a roll or a cooling bath. Therefore, sufficient workability is ensured for subsequent can manufacturing, lid processing, and the like.
- the rapid cooling operation is not limited to the above example, and the laminate sheet can be rapidly cooled by spraying cooling water on the formed organic-coated surface-treated steel sheet.
- the thermal adhesion of the polyester resin to the surface-treated steel sheet is performed by the amount of heat that the molten resin layer has and the amount of heat that the surface-treated steel sheet has.
- the heating temperature (T 1 ) of the surface-treated steel sheet is generally 90 ° C. to 290 ° C., particularly 100 ° C. to 280 ° C., while the laminating roll temperature is suitably 10 ° C. to 150 ° C.
- the organic resin coating on the surface-treated steel sheet obtained by the production method of the present invention can also be produced by thermally bonding a polyester resin film previously formed by a T-die method or an inflation film-forming method to the surface-treated steel sheet. be able to.
- an unstretched film formed by a cast molding method in which the extruded film is rapidly cooled can be used, and this film is biaxially stretched sequentially or simultaneously at the stretching temperature, and the stretched film is heat-set. It is also possible to use a biaxially stretched film produced by the above method.
- the can formed from the surface-treated steel sheet obtained by the present invention may be any can-making method as long as it is formed from the above-mentioned organic-coated surface-treated steel sheet, and a three-piece can (welded can) having a side seam. Or a seamless can (two-piece can) or can lid, but as mentioned above, considering the use of a surface-treated steel sheet with a large amount of Zr from the viewpoint of adhesion to an organic resin, the seamless can Application to is most preferable.
- Seamless cans are drawn, drawn and re-squeezed, bent and stretched by drawing and redrawing (stretching), drawn and redrawed by drawing and redrawing, or drawn or drawn so that the organic coating is on the inner surface of the can. It is manufactured by attaching to a conventionally known means such as ironing.
- a conventionally known means such as ironing.
- organic coating is applied by extrusion coating. It is particularly preferred that it comprises a thermoplastic resin coating. That is, since the organic coated surface-treated steel sheet is excellent in work adhesion, it is possible to provide a seamless can having excellent corrosion resistance and excellent coating adhesion even when subjected to severe processing. .
- the can lid formed from the surface-treated steel sheet obtained by the present invention may be formed by any conventionally known lid-making method as long as it is formed from the aforementioned organic-coated surface-treated steel sheet. -Applicable to tab type easy open can lids and full open type easy open can lids. In the can lid of the present invention, the lid can be formed using any of the various embodiments of the organic-coated surface-treated steel sheet of the present invention without limitation.
- the present invention will be described more specifically with reference to examples.
- the present invention is not limited to these examples.
- the to-be-treated material, degreasing agent, and organic coating used in the examples are arbitrarily selected from commercially available materials, and do not limit the method for manufacturing the steel sheet for surface treatment of the present invention.
- the preparation method of a surface treatment board and the evaluation method of each characteristic are as follows.
- ⁇ Film formation process> A low carbon steel plate having a thickness of 0.225 mm and a width of 200 mm was used as an original plate, and then alkaline electrolytic degreasing and sulfuric acid immersion pickling were performed as pretreatment. Thereafter, the steel sheet was immersed in an electrolytic treatment solution and subjected to cathodic electrolysis, whereby a compound film containing F on the surface of the steel sheet and mainly composed of Zr was formed on both surfaces. Next, the steel plate was squeezed with a roll, washed with water, and further washed with squeezed water. As the electrolytic treatment liquid, an aqueous solution having a Zr concentration of 6000 ppm and an F concentration of 7000 ppm was used as a Zr compound.
- PH of electrolytic treatment solution 3.0 (pH adjustment with nitric acid and / or ammonia)
- Electrolytic solution temperature 40 ° C
- Current density during cathode electrolysis 10 A / dm 2
- Energization method during cathodic electrolysis A cycle of energization for 0.15 seconds and energization for 0.1 seconds was performed a plurality of times (hereinafter referred to as the number of cycles).
- ⁇ Surface adjustment process> The steel sheet after completion of the film forming process was treated with an ion-containing aqueous solution for a predetermined time, and then the steel sheet was squeezed with a roll, washed with water, further squeezed with a roll, and then dried with hot air.
- some steel plates were treated with ion-containing water, then immersed in warm water of 40 ° C. or higher, or further washed with warm water sprayed after immersion, and then dried with hot air.
- the ion-containing water treatment is omitted, the hot water washing treatment is performed by immersing with 90-95 ° C. warm water or spraying after the immersion, and then the hot water is squeezed with a roll from the steel plate. Dried.
- Preparation of organic resin-coated surface-treated steel sheet The obtained surface-treated steel sheet has a polyethylene terephthalate / isophthalate copolymer composition containing 11 mol% of an isophthalic acid component on one surface of a metal plate on the inner surface side of the can.
- a 19 ⁇ m stretched film has a polyethylene terephthalate / isophthalate copolymer composition containing 12 mol% of an isophthalic acid component on the other surface on the outer surface side of the can, and is colored white with titanium oxide.
- the stretched film having a thickness of 13 ⁇ m was subjected to thermocompression bonding via a laminate roll and immediately water-cooled to obtain an organic resin-coated surface-treated steel sheet while paying attention so that an appropriate orientation state remains in the film.
- the produced organic resin-coated surface-treated steel sheet was used for the production of metal cans, except that a part was used for cross-cut corrosion resistance evaluation.
- Cross-cut corrosion resistance evaluation Cross-cut scratches that reach a 4 cm-long substrate with a cutter are made in the portion corresponding to the inner surface of the can of the prepared organic resin-coated surface-treated steel sheet, and the model solution (weight concentration of sodium chloride and citric acid is 1 each In a 5% aqueous solution), and aged for 1 week at 37 ° C. to evaluate the corrosion state. Then, the test piece was taken out from the model liquid, and the state of discoloration due to peeling of the organic resin layer or generation of the corrosion product was observed and evaluated for the crosscut portion and its periphery. In the vicinity of the crosscut portion, the maximum width of discoloration or film peeling was 2 mm or more per side, x was 1 mm or more and less than 2 mm, and ⁇ was less than 1 mm.
- Example 1 First, in the film forming step, cathodic electrolysis was carried out on the steel sheet for seven cycles, the electrolytic treatment solution was squeezed with a roll, then washed with normal temperature water, and the rinsing water was further squeezed with a roll. Next, in the surface adjustment step, after immersing in a mixed aqueous solution of sodium carbonate and sodium hydrogen carbonate at 40 ° C. adjusted to pH 9.5 for 1 second and further immersed in hot water at 95 ° C. for 1 second, the aqueous solution was squeezed with a roll. Then, after washing with water and further squeezing the washing water with a roll, the surface-treated steel sheet was obtained by drying.
- the ion-containing aqueous solution may be adjusted by appropriately adding a drug so as to have a target pH, or may be adjusted by previously determining the drug concentration.
- the pH value measured at 25 ° C. was used.
- Tables 1 and 2 when the ion-containing aqueous solution treatment was not performed, or when warm water washing was not performed with water of 40 ° C. or higher, a ⁇ symbol was described in the table.
- Examples 2 to 22 In the same manner as in Example 1, the conditions of the coating formation process and the coating amount (Zr amount and F amount), the conditions of the surface adjustment step and the F amount of the coating after passing through the process, the performance evaluation of the organic resin-coated surface-treated steel sheet and metal can The results are shown in Table 1. However, in Examples 3 to 11 and Examples 21 to 22, the warm water cleaning was performed by immersing the first half of the treatment time shown in Table 1 and the latter half by spraying.
- Comparative Examples 1 to 10 In the same manner as in Example 1, the conditions of the coating formation process and the coating amount (Zr amount and F amount), the conditions of the surface adjustment step and the F amount of the coating after passing through the process, the performance evaluation of the organic resin-coated surface-treated steel sheet and metal can The results are shown in Table 2. However, in Comparative Examples 6 to 8 and Comparative Example 10, washing with warm water was performed by immersing the first half of the treatment time described in Table 2 and spraying the latter half.
- the amount of Zr in the film is set to 80 to 350 mg / m 2 in the film forming process, and the steel sheet after the film forming process is completed in the surface adjustment process with an ion-containing aqueous solution or hot water at 90 ° C.
- a plate having an F content in the coating of 0.5 mg / m 2 to 10 mg / m 2 was produced.
- each of the obtained organic resin-coated metal plates is excellent in cross-cut corrosion resistance, excellent in inner surface adhesion of metal cans, and F-eluting resistance, and is in close contact with organic resin layers.
- the container is excellent in maintaining the quality of the contents because the organic resin layer is in good contact even after the molding process and retort treatment, or even when the organic resin layer is cracked. It was confirmed.
- Comparative Examples 3 to 5 in which the amount of Zr is 80 mg / m 2 or more and does not pass the surface adjustment step, the cross-cut corrosion resistance of the organic resin-coated metal sheet is improved, but the F elution resistance is lowered.
- Comparative Example 6 in which the surface adjustment step was performed with hot water at 90 ° C. for 1 second.
- Comparative Examples 7 to 8 which were performed with hot water at 90 ° C. for 2 to 3 seconds, an improvement in the inner surface adhesion of the can was observed, but the results were insufficient for improving the F elution.
Abstract
Description
クロメート処理には、被膜中に6価クロムを含有するタイプと含有しないタイプがあるが、近年、環境および労働衛生の観点から、出発原料として6価クロムを使用するものであれば、最終製品の状態にかかわらず出発原料自体への6価クロム含有を禁止しようとする動きが強まっている。
本発明の表面処理鋼板の製造方法においては、
1.表面調整工程におけるイオン含有水溶液がナトリウムイオン,アンモニウムイオン,カリウムイオンのうち1種又は2種以上のイオンを含むアルカリ性水溶液であること、
2.表面調整工程におけるイオン含有水溶液のpHが9以上であること、
が好適である。
また、表面調整工程におけるイオン含有水溶液がナトリウムイオン,アンモニウムイオン,カリウムイオンのうち1種又は2種以上のイオンを含むアルカリ性水溶液であること、表面調整工程におけるイオン含有水溶液のpHが9以上であること、が好適である。
以下に、本発明における表面処理鋼板、表面処理鋼板を利用した有機樹脂被覆容器、並びに表面処理鋼板について説明する。
Fを含有しZrを主体とする化合物被膜は、ZrOx(OH)Y―ZFZのような非結晶性の構造をとると考えられる。この被膜は、乾燥や焼成により、脱水すると共にFが抜けて、結晶成分を多く持つ酸化被膜に変化し、加熱が進むと最終的にはZrO2に近い被膜となると考えられる。しかし、通常の缶材が受ける熱履歴を越える過度の加熱は、構造変化に起因する被膜のクラックを誘発すると共に、よりセラミックスライクな被膜となるため、加工性の低下はもちろん、樹脂被覆との密着性低下を招くため好ましくない。したがって、被膜の大部分は、基本的に必要最小限のFやOHは残存するZrOx(OH)Y―ZFZのような構造に留めて置く事が好ましい。
鋼板の少なくとも片面上に形成する金属化合物の被膜量としては、Zr量が80mg/m2以上、好ましくは100mg/m2以上とする必要がある。Zr量が80mg/m2未満では、有機樹脂被覆後のクロスカット耐食性やレトルト後の有機樹脂密着性が不十分であった。また、Zr量350mg/m2を越えると必要以上に被膜を析出させる事となり、不経済であるばかりでなく、加工密着性も徐々に低下していくので好ましくない。
一方、表面処理被膜のF量としては10mg/m2以下に制御する必要がある。F量が10mg/m2を越えて、被膜中に必要以上に存在すると、レトルトのような熱水殺菌処理工程において、被膜構造の一部が水和して構造変化を起こし、被膜中に存在する過剰なアニオンであるFが溶出し易い状態となり、被膜成分の溶出による樹脂被覆との密着低下の原因となる。しかしながら、その一方で、前述のように、Fを極端に減らすことは避けなければならない。Fは被膜に必要な有効成分でもあり、F量が0.5mg/m2未満では、水和による被膜の構造変化が進行し、被膜の凝集力低下に起因し、耐食性が低下する。
本発明においては、後述するように、有機樹脂被覆や金属容器の形態に特に限定はないが、ポリエステル樹脂を被覆したプレコート表面処理鋼板を加工することにより作成したポリエステル樹脂被覆シームレス缶が、有機樹脂被覆膜との密着性や、容器構成金属成分の溶出耐性、クロスカット耐食性などの点において、最も好適に用いられる。
<被膜形成工程>
まず、本発明においては、表面処理鋼板の製造方法であって、被膜形成工程において、Zrイオン、Fイオンを含む水溶液中で、鋼板を陰極電解することにより、鋼板の少なくとも片面上に、Fを含有しZrを主体とする化合物被膜をZr量が80~350mg/m2となるように形成する。化合物被膜を形成後の鋼板は、電解液をロールで絞った後、水洗し、更に水洗水をロールで絞った後、次の表面調整工程に送られる。また、化合物被膜を形成後の鋼板を、ロールで電解液を絞った後に、水洗を行うことなく、次の表面調整工程におくってもよい。
次いで、本発明においては表面調整工程として、上記被膜形成工程において、Fを含有しZrを主体とする化合物被膜を形成することにより得られた表面処理鋼板を、イオン含有水溶液にて、浸漬、スプレー、あるいは該水溶液中での陰極電解、のいずれか一つ以上の処理を行い、この処理により前記被膜中のF量を0.5~10mg/m2に制御し、次いで鋼板からイオン含有水溶液をロールで絞った後、水洗し、更に水洗水をロールで絞った後、熱風等により乾燥する。
また、本発明においては他の形態の表面調整工程として、上記被膜形成工程において、基材上にFを含有しZrを主体とする化合物被膜を形成することにより得られた表面処理鋼板を、90℃以上の水でスプレー及び/又は浸漬処理を行い、この処理により前記被膜中のF量を0.5~10mg/m2に制御し、次いで鋼板をロールで絞った後、水洗し、更にロールで絞った後、乾燥する。但し、90℃以上の水のみで処理した場合には、被膜中のF量を0.5~1.0mg/m2範囲とするには比較例で述べるように、表面調整には3秒では不十分である。
表面調整工程には、以下の2つの意味がある。表面調整工程を経ない場合、樹脂被覆され缶成形された容器は、レトルトのような熱水殺菌処理工程において、徐々にではあるが被膜構造の一部が水和して構造変化を起こし、被膜中に存在する過剰なアニオンであるOHやFが内容品中に溶出し易い状態となる。
したがって、第1の意味は、缶用材料として樹脂被覆が施される前に、あらかじめ表面調整工程にて被膜中の過剰なアニオンを減らしておく意味合いがある。表面調整工程において、Na+,NH4 +,K+のうち1種又は2種以上のイオンを水溶液中に含むと、これらのイオンはアニオンであるFと結合し易いため効率的にFを除去するのに有効である。
また、表面調整工程においては、水溶液自体のpHをアルカリにすることが好ましい。これにより、被膜中のFは、錯イオンの形でなく遊離Fイオンの形で存在し易くなり、より効率的に除去することが可能となるのである。表面調整工程において、イオン含有水溶液のpHは9以上とすることがより好ましい。
以上のように、表面調整工程によりF量を10mg/m2以下に制御する事が可能となる。
一方、第2の意味は、過度にFを減らさないことである。適度なFは被膜に必要な有効成分でもあり、Fが存在しないか極端に少ない場合には、水和による被膜の構造変化が進行し易く、被膜の凝集力低下に起因し、表面処理被膜の耐食性低下を誘発する。したがって、表面調整工程によりF量を0.5mg/m2以上に制御する事が必要である。
また、イオン含有水溶液中で陰極電解処理を加えることにより、被膜中のFを除く効果が浸漬のみの場合よりも大きくなる。陰極電解処理に用いるイオン含有水溶液の電気伝導度は効率の点から考えると大きい方が好ましいが、少なくとも2mS/cm以上であることが好ましい。但し、前述したように、表面調整工程での水溶液のpHを高くしすぎたり、陰極電解処理での通電時間あるいは電流密度を大きくしすぎると、Fをほとんど含まない被膜となり、被膜の凝集力が低下するため、F量の管理には注意が必要である。
鋼板としては、たとえば、アルミキルド鋼連鋳材などをベースとした熱延鋼板、これらの熱延鋼板を冷間圧延した冷延鋼板、これらの熱延鋼板や冷延鋼板にZn、Sn、Ni、Cu、Alなどを含む金属めっき層を備えた鋼板などを用いることができる。これらのなかでも、本発明の目的とするZr量を大きくする用途には、金属めっき層を有しないか、めっき層を有していても表面の一部に鉄が露出している鋼板が基材として最も好適に用いられる。
なお、本発明により得られる表面処理鋼板を被覆する有機樹脂層を構成する樹脂としては、特に限定されず、本発明の表面処理鋼板の用途(たとえば、特定の内容物を充填する缶容器などの用途)に応じて適宜選択すればよいが、各種熱可塑性樹脂から成る樹脂被覆や、熱硬化性塗料又は熱可塑性塗料からなる塗膜を挙げることができる。熱可塑性樹脂から成る樹脂被覆としては、ポリエチレン、ポリプロピレン、エチレン-プロピレン共重合体、エチレン-酢酸ビニル共重合体、エチレン-アクリルエステル共重合体、アイオノマー等のオレフィン系樹脂フィルム、またはポリエチレンテレフタレート、ポリブチレンテレフタレート等のポリエステルフィルム、もしくはナイロン6、ナイロン6,6、ナイロン11、ナイロン12等のポリアミドフィルム、ポリ塩化ビニルフィルム、ポリ塩化ビニリデンフィルム等の熱可塑性樹脂フィルムの未延伸または二軸延伸したものであってもよい。その中でも、イソフタル酸を共重合化してなる無配向のポリエチレンテレフタレートが特に好ましい。また、このような有機樹脂層を構成するための樹脂は、単独で用いてもよく、異なる樹脂をブレンドして用いてもよい。
多層ポリエステル樹脂層の例を示すと、表層/下層として表示して、ポリエチレンテレフタレート/ポリエチレンテレフタレート・イソフタレート、ポリエチレンテレフタレート/ポリエチレン・シクロへキシレンジメチレン・テレフタレート、イソフタレート含有量の少ないポリエチレンテレフタレート・イソフタレート/イソフタレート含有量の多いポリエチレンテレフタレート・イソフタレート、ポリエチレンテレフタレート・イソフタレート/[ポリエチレンテレフタレート・イソフタレートとポリブチレンテレフタレート・アジペートとのブレンド物]等であるが、勿論上記の例に限定されない。表層:下層の厚み比は、5:95~95:5の範囲にあるのが望ましい。
中でも、トコフェロール(ビタミンE)を用いることが好ましい。トコフェロールは、従来より酸化防止剤としてポリエステル樹脂の熱処理時における酸化分解による分子量低下を防止して耐デント性を向上させるものであることが知られているが、特にポリエステル樹脂に前述したエチレン系重合体を改質樹脂成分として配合したポリエステル組成物にこのトコフェロールを配合すると、耐デント性のみならず、レトルト殺菌やホットベンダー等の過酷な条件に付され被膜にクラックが生じたような場合でも、クラックから腐食が進むことが防止され、耐食性が著しく向上するという効果を得ることができる。
トコフェロールは、0.05~3重量%、特に0.1~2重量%の量で配合することが
好ましい。
また、本発明の製造方法により得られる表面処理鋼板の有機樹脂被覆は、T-ダイ法やインフレーション製膜法で予め製膜されたポリエステル樹脂フィルムを表面処理鋼板に熱接着させることによっても製造することができる。フィルムとしては、押し出したフィルムを急冷した、キャスト成形法による未延伸フィルムを用いることもでき、また、このフィルムを延伸温度で、逐次或いは同時二軸延伸し、延伸後のフィルムを熱固定することにより製造された二軸延伸フィルムを用いることもできる。
<缶>
本発明により得られる表面処理鋼板から形成される缶体は、前述した有機被覆表面処理鋼板から成形されている限り、任意の製缶法によるものでよく、側面継ぎ目を有するスリーピース缶(溶接缶)や、シームレス缶(ツーピース缶)、あるいは缶蓋とすることができるが、前述したように、有機樹脂との密着性の観点からZr量が大きい表面処理鋼板を利用する点を考慮すると、シームレス缶への適用がもっとも好ましい。
シームレス缶は、有機被覆が缶内面側になるように、絞り加工、絞り・再しぼり加工、絞り・再絞りによる曲げ伸ばし加工(ストレッチ加工)、絞り・再絞りによる曲げ伸ばし・しごき加工或いは絞り・しごき加工等の従来公知の手段に付すことによって製造される。
また、絞り・再絞りによる曲げ伸ばし加工(ストレッチ加工)、絞り・再絞りによる曲げ伸ばし・しごき加工、絞り・しごき加工等の高度な加工が施されるシームレス缶においては、有機被覆が押出コート法による熱可塑性樹脂被覆から成るものであることが特に好ましい。
すなわち、かかる有機被覆表面処理鋼板は、加工密着性に優れていることから、過酷な加工に賦された場合にも被覆の密着性に優れ、優れた耐食性を有するシームレス缶を提供することができる。
本発明により得られる表面処理鋼板から形成される缶蓋は、前述した有機被覆表面処理鋼板から成形されている限り、従来公知の任意の製蓋法によるものでよく、平蓋や、ステイ・オン・タブタイプのイージーオープン缶蓋やフルオープンタイプのイージーオープン缶蓋に適用することができる。
本発明の缶蓋においては本発明の有機被覆表面処理鋼板の種々の態様のものを制限なく用いて蓋を成形することができる。
なお、表面処理板の作製方法および各特性の評価方法は、以下のとおりである。
原板として、厚さ0.225mm、幅200mmの低炭素鋼板を用い、次いで、前処理としてアルカリ電解脱脂、硫酸浸漬の酸洗を行った。その後、鋼板を電解処理液に浸漬させ、陰極電解処理を行うことにより、鋼板の表面にFを含有し、Zrを主体とする化合物被膜を両面に形成した。次いで鋼板をロールで絞った後、水洗し、更に水洗水をロールで絞った。
電解処理液としては、Zr化合物としてフッ化ジルコニウムアンモニウムを溶解させ、Zr濃度6000ppm、F濃度7000ppmの組成の水溶液を用いた。
電解処理液のpH:3.0(硝酸及び/又はアンモニアにてpH調整を実施)
電解処理液の温度:40℃
陰極電解時の電流密度:10A/dm2
陰極電解時の通電方法:0.15秒通電、0.1秒通電停止のサイクルを複数回(以後、サイクル数と呼ぶ)実施した。
<表面調整工程>
被膜形成工程終了後の鋼板を、イオン含有水溶液で所定時間処理し、次いで鋼板をロールで絞った後、水洗し、更にロールで絞った後、熱風により乾燥した。
このうち、一部の鋼板については、イオン含有水で処理した後に、40℃以上の加温水で浸漬または浸漬後にスプレーする加温水洗浄を更に行ってから、熱風により乾燥した。
また、その他の鋼板は、イオン含有水処理を省略し、90~95℃の加温水で浸漬または浸漬後にスプレーする加温水洗浄の処理を行い、次いで鋼板から加温水をロールで絞った後に、熱風により乾燥した。
各実施例および各比較例において得られた表面処理板について、蛍光X線分析装置(リガク社製、型番:ZSX100e)を用いて、金属化合物被膜に含まれるZr量を測定した。
蛍光X線分析ではF量の微量分析は定量精度の点で限界があり、特にF量1.5mg/m2以下の表面処理板から直接Fを定量する事は困難である。種々検討の結果、我々は以下の測定方法を選定した。即ち、レトルト加圧可能な特殊セルを用いて、一定面積の表面処理板を一定量の超純水に接触させた状態で、130℃で30分間のレトルト処理を行った。この処理により超純水中に抽出されたフッ素イオンをイオンクロマトグラフ(DIONEX製DX-320)により測定した。得られたF濃度から、超純水中に存在するF重量を求め、これを表面処理板の単位面積当たりに存在するF重量に換算することにより、被膜中のF量と定義した。
1.有機樹脂被覆表面処理鋼板の作製
得られた表面処理鋼板を、缶内面側となる金属板の片面上に、イソフタル酸成分を11モル%含有するポリエチレンテレフタレート/イソフタレート共重合組成を有する、厚さ19μmの延伸フィルムを、缶外面側となるもう一方の片面上に、イソフタル酸成分を12モル%含有するポリエチレンテレフタレート/イソフタレート共重合組成を有し、酸化チタンを含有してホワイトに着色した、厚さ13μmの延伸フィルムを、ラミネートロールを介して熱圧着後、直ちに水冷することにより、フィルムに適度な配向状態が残るように留意しながら有機樹脂被覆表面処理鋼板を得た。作製した有機樹脂被覆表面処理鋼板は、一部をクロスカット耐食性評価用として用いた以外は、金属缶の作製に使用した。
作製した有機樹脂被覆表面処理鋼板の缶内面側に相当する部分にカッターで長さ4cmの素地に達するクロスカット傷を入れ、モデル液(塩化ナトリウムとクエン酸の重量濃度がそれぞれ1.5%の水溶液)に、浸漬させて37℃で1週間経時して、腐食状態を評価した。その後、試験片をモデル液から取り出し、クロスカット部分及びその周囲について、有機樹脂層の剥離あるいは、腐食生成物の生成による変色の状態を目視評価にて観察して評価した。クロスカット部周辺において、変色またはフィルム剥離の最大幅が片側あたり2mm以上であったものを×、1mm以上2mm未満のものを○、1mm未満のものを◎とした。
得られた有機樹脂被覆表面処理鋼板の両面に、パラフィンワックスを両面に静電塗油後、直径143mmの円形に打抜き、定法に従い、径91mm、高さ36mmの絞りカップを作製した。ついでこの絞りカップを同時絞りしごき加工を2回繰り返して径が小さくハイトの大きいカップに成形した。この様にして得られたカップの諸特性は以下の通りであった。
カップ径 52.0mm
カップ高さ 111.7mm
元板厚に対する缶壁部の板厚減少率 30%
このカップはドーミング成形後、樹脂フィルムの歪みをとるために220℃で60秒間熱処理を行い、続いて開口端端部のトリミング加工、曲面印刷し、直径50.8mmにネックイン加工、フランジ加工を行い、200gシームレス缶を作製した。
作製した缶を用いて、常法に基づいて蒸留水を充填後125℃30分のレトルト処理を行った。その後、蓋を缶胴から取り外して内容品を除去後、表面処理板の圧延45度方向を境にして半分に切断した。次に、この半分に切断された缶を、1重量%塩化ナトリウム水溶液に0.02重量%の界面活性剤を添加した液に1時間浸漬後、更に圧延135度方向を境にして缶底側から更に半分にはさみで切断し、最後に切断した缶内面側ボトムラジアス部切断面の剥離状態を観察し、密着性を評価した。切断面付近に剥離が認められたものを×、切断部を先端のとがった針で触ると少し剥離するものを○、剥離が見られなかったものを◎とした。
作製した缶を用いて183gの超純水を充填し、130℃で30分のレトルト処理を行った後、超純水中に抽出されたフッ素イオンをイオンクロマトグラフ(DIONEX製DX-320)により測定した。Fが検出されたものを×、検出限界(0.1ppm)以下のものを○とした。
まず被膜形成工程に於いて、鋼板上に、サイクル数7回の陰極電解を実施し、電解処理液をロールで絞った後、常温水で水洗し、更に水洗水をロールで絞った。次いで、表面調整工程において、pH9.5に調整した40℃の炭酸ナトリウムと炭酸水素ナトリウムの混合水溶液に1秒間浸漬後、更に95℃の熱水に1秒間浸漬した後、水溶液をロールで絞った後、水洗し、更に水洗水をロールで絞った後、乾燥することにより、表面処理鋼板を得た。
実施例1と同様に、被膜形成工程の条件および被膜量(Zr量およびF量)、表面調整工程の条件および工程通過後の被膜のF量、有機樹脂被覆表面処理鋼板および金属缶の性能評価結果を表1に記載した。但し、実施例3~11および実施例21~22において、加温水洗浄は、表1に記載した処理時間の前半半分を浸漬で行い、後半半分をスプレーにて実施した。また、実施例14~16は、表面調整工程において、イオン含有水溶液中で鋼板を陰極とし、10A/dm2の電流密度で0.15秒通電、0.1秒通電停止のサイクルを2回繰り返すことにより実施した。
実施例1と同様に、被膜形成工程の条件および被膜量(Zr量およびF量)、表面調整工程の条件および工程通過後の被膜のF量、有機樹脂被覆表面処理鋼板および金属缶の性能評価結果を表2に記載した。但し、比較例6~8および比較例10において、加温水洗浄は、表2に記載した処理時間の前半半分を浸漬で行い、後半半分をスプレーにて実施した。また、比較例9は、表面調整工程において、イオン含有水溶液中で鋼板を陰極とし、10A/dm2の電流密度で0.15秒通電、0.1秒通電停止のサイクルを4回繰り返すことにより実施した。
また、電解クロム酸処理鋼板においては、被膜中のF量は0.4mg/m2程度であるが、各実施例においては、表面調整工程後においても、被膜中のF量は0.5mg/m2以上あり、表面処理鋼板として、Zrを主体とする化合物からなる表面処理被膜を持つ鋼板の場合は、電解クロム処理鋼板よりF量が多い必要がある事が明らかとなった。
Claims (6)
- 鋼板の少なくとも片面上に、Fを含有しZrを主体とする化合物被膜を有する表面処理鋼板であって、該被膜中のZr量は80~350mg/m2であり、F量は0.5~10mg/m2であることを特徴とする表面処理鋼板。
- 請求項1に記載の表面処理鋼板を用いて作成した有機樹脂被覆金属容器。
- 鋼板の少なくとも片面上に、Fを含有しZrを主体とする化合物被膜を形成する表面処理鋼板の製造方法であって、Zrイオン、Fイオンを含む水溶液中で、鋼板を陰極電解することにより、該被膜中のZr量を80~350mg/m2とする被膜形成工程と、それに続いて、イオン含有水溶液にて、浸漬、スプレー、あるいは該イオン含有水溶液中での陰極電解、のいずれか一つ以上の処理を行い前記被膜中のF量を0.5~10mg/m2に制御する表面調整工程、とを有することを特徴とする表面処理鋼板の製造方法。
- 前記表面調整工程における前記イオン含有水溶液がナトリウムイオン、アンモニウムイオン,カリウムイオンのうち1種又は2種以上のイオンを含むアルカリ性水溶液であることを特徴とする請求項3に記載の表面処理鋼板の製造方法。
- 前記表面調整工程における前記イオン含有水溶液のpHが9以上であることを特徴とする請求項3または4に記載の表面処理鋼板の製造方法。
- 鋼板の少なくとも片面上に、Fを含有しZrを主体とする化合物被膜を形成する表面処理鋼板の製造方法であって、Zrイオン、Fイオンを含む水溶液中で、鋼板を陰極電解することにより、該被膜中のZr量を80~350mg/m2とする被膜を形成する被膜形成工程と、それに続いて、鋼板に対し、90℃以上の水でスプレー及び/又は浸漬を行い前記被膜中のF量を0.5~10mg/m2に制御する表面調整工程、とを有することを特徴とする表面処理鋼板の製造方法。
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US15/025,238 US20160230301A1 (en) | 2013-09-25 | 2014-08-04 | Surface-Treated Steel Sheet, Organic Resin Coated Metal Container, and Method for Producing Surface-Treated Steel Sheet |
CN201480053046.8A CN105579622B (zh) | 2013-09-25 | 2014-08-04 | 表面处理钢板、有机树脂覆层金属容器以及表面处理钢板的制造方法 |
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KR20160060655A (ko) | 2016-05-30 |
CN105579622A (zh) | 2016-05-11 |
EP3051006A1 (en) | 2016-08-03 |
JP5873609B2 (ja) | 2016-03-01 |
EP3051006B1 (en) | 2019-06-19 |
EP3051006A4 (en) | 2017-07-19 |
TR201910649T4 (tr) | 2019-08-21 |
US20160230301A1 (en) | 2016-08-11 |
CN105579622B (zh) | 2018-07-27 |
PH12016500527A1 (en) | 2016-05-23 |
US20170342584A1 (en) | 2017-11-30 |
US10934629B2 (en) | 2021-03-02 |
JPWO2015045624A1 (ja) | 2017-03-09 |
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