Production method for surface-treated metal sheet, surface-treated metal sheet, and layered material

Abstract

Provided is a production method for a surface-treated metal sheet that includes a step for preparing a metal base material 10, a zinc phosphate treatment step for forming a zinc phosphate layer 20 on the surface of the metal base material 10, and a sealing step for forming a sealing layer 30 on the zinc phosphate layer 20. The phosphorus content W(P) of the zinc phosphate layer 20 is 100–300 mg / m2. The sealing layer 30 contains zirconium and a urethane resin, and the deposited amount W(R) of the sealing layer 30 is 60–700 mg / m2.

Description

Method for manufacturing surface-treated metal sheet, surface-treated metal sheet, and laminate

[0001] The present invention relates to a method for manufacturing a surface-treated metal sheet, a surface-treated metal sheet, and a laminate.

[0002] Coated metal sheets, in which a resin coating layer is formed on a metal sheet, are widely used in building exterior components, automotive components, and the like, and are known, for example, as joint fillers used in joints (see, for example, Patent Document 1). Surface-treated galvanized steel sheets are known, which include a zinc phosphate plating layer and a resin layer formed on a galvanized steel sheet (see, for example, Patent Document 1). Surface-treated steel sheets that can be used for automotive components, building materials, and the like are known, which include a zinc phosphate crystal layer (first layer) formed on a galvanized steel sheet and a resin-containing coating layer (second layer) (see, for example, Patent Document 1). Patent Document 1 states that the anchor effect of the zinc phosphate crystals results in excellent adhesion between the zinc phosphate crystal layer and the coating layer.

[0003] JP 2017-155261 A

[0004] However, because the zinc phosphate crystal layer is composed of multiple needle-shaped zinc phosphate crystals, when forming a coating layer, the resin material cannot penetrate all the way to the base of the zinc phosphate crystals, which can result in voids forming inside the zinc phosphate crystal layer. Therefore, the technology described in Patent Document 1 has a problem in that moisture that has entered these voids reacts with zinc, causing corrosion and gas generation, which can easily cause blisters (swelling). The occurrence of blisters can deteriorate the appearance of the surface-treated steel sheet, or the surface-treated steel sheet can easily corrode from the blisters, thereby reducing its corrosion resistance.

[0005] An object of the present invention is to provide a method for manufacturing a surface-treated metal sheet, a surface-treated metal sheet, and a laminate that can suppress the occurrence of blistering when a coating layer is formed and provide a laminate with excellent appearance.

[0006] [1] According to a first aspect of the present invention, there is provided a method for manufacturing a metal substrate, comprising the steps of: preparing a metal substrate; forming a zinc phosphate layer on the surface of the metal substrate; and forming a sealing layer on the zinc phosphate layer; wherein the phosphorus content W(P) contained in the zinc phosphate layer is 100 to 300 mg / m ２ The sealing layer contains zirconium and a urethane resin, and the coating weight W(R) of the sealing layer is 60 to 700 mg / m ２ The present invention provides a method for producing a surface-treated metal sheet.

[0007] [2] According to aspect 2 of the present invention, there is provided a method for manufacturing a surface-treated metal sheet according to aspect 1, in which the ratio "W(P) / W(R)" of the phosphorus content W(P) contained in the zinc phosphate layer to the adhesion amount W(R) of the sealing layer is 0.3 to 3.5.

[0008] [3] According to aspect 3 of the present invention, there is provided a method for producing a surface-treated metal sheet according to aspect 1 or 2, wherein the step of preparing the metal substrate includes forming a zinc plating layer on the surface of the metal substrate.

[0009] [4] According to a fourth aspect of the present invention, there is provided a method for producing a surface-treated metal sheet according to any one of the first to third aspects, wherein the zirconium content W (Zr) of the surface-treated metal sheet is 1.5 to 23.0 mg / m ２ The present invention provides a method for producing a surface-treated metal sheet.

[0010] [5] According to a fifth aspect of the present invention, there is provided a surface-treated metal sheet comprising a metal substrate, a zinc phosphate layer formed on at least one surface of the metal substrate, and a sealing layer formed by laminating on the zinc phosphate layer, wherein the phosphorus content W(P) contained in the zinc phosphate layer is 100 to 300 mg / m ２ The sealing layer is made of a urethane resin containing zirconium, and the adhesion amount W(R) of the sealing layer is 60 to 700 mg / m ２ The surface-treated metal sheet is provided as follows.

[0011] [6] According to a sixth aspect of the present invention, in the surface-treated metal sheet of the fifth aspect, the zirconium content is W (Zr) 1.5 to 23.0 mg / m ２ The surface-treated metal sheet is provided as follows.

[0012] [7] According to aspect 7 of the present invention, there is provided a surface-treated metal sheet according to aspect 5 or 6, wherein the ratio "W(P) / W(R)" of the phosphorus content W(P) contained in the zinc phosphate layer to the adhesion amount W(R) of the sealing layer is 0.3 to 3.5.

[0013] [8] According to an eighth aspect of the present invention, there is provided the surface-treated metal sheet of any one of the fifth to seventh aspects, wherein the ratio "W(P) / W(Zr)" of the phosphorus content W(P) contained in the zinc phosphate layer to the zirconium content W(Zr) is 10 to 120.

[0014] [9] According to a ninth aspect of the present invention, there is provided a surface-treated metal sheet according to any one of the fifth to eighth aspects, wherein the metal substrate comprises an original metal sheet and a zinc plating layer mainly containing zinc, and the zinc phosphate layer is formed on the zinc plating layer.

[0015]

[10] According to a tenth aspect of the present invention, in the surface-treated metal sheet of the ninth aspect, the zinc content W(Zn) of the zinc plating layer is 3 to 30 g / m ２ The surface-treated metal sheet is provided as follows.

[0016]

[11] According to aspect 11 of the present invention, there is provided a laminate comprising a surface-treated metal plate according to any one of aspects 5 to 10 and a coating layer made of a resin material and formed on the sealing layer.

[0017] According to the present invention, it is possible to provide a method for manufacturing a surface-treated metal sheet, a surface-treated metal sheet, and a laminate material that can suppress the occurrence of blisters when a coating layer is formed and can produce a laminate material with an excellent appearance.

[0018] Fig. 1 is a schematic cross-sectional view showing the configuration of a surface-treated metal sheet according to an embodiment of the present invention. Fig. 2 is an enlarged view of part II in Fig. 1. Fig. 3 is a schematic cross-sectional view showing the configuration of a laminate according to an embodiment of the present invention.

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] <Surface-treated metal sheet 1> Fig. 1 is a schematic cross-sectional view showing the configuration of a surface-treated metal sheet 1 in this embodiment, Fig. 2 is an enlarged view of part II in Fig. 1, and Fig. 3 is a schematic cross-sectional view showing the configuration of a laminate material 100 in this embodiment. The surface-treated metal sheet 1 in this embodiment includes a metal substrate 10, a zinc phosphate layer 20 provided on the metal substrate 10, and a sealing layer 30 provided on the zinc phosphate layer 20. As shown in Fig. 3, the surface-treated metal sheet 1 is suitably used as a laminate material 100 in which a resin coating layer 40 is formed on the sealing layer 30. Hereinafter, the configuration of the surface-treated metal sheet 1 will be described mainly using Figs. 1 and 2.

[0021] <Metal Substrate 10> The metal substrate 10 in this embodiment is a plated sheet including a metal original sheet 11 and a zinc-plated layer 12 containing zinc formed on the metal original sheet 11.

[0022] The metal base plate 11 is not particularly limited, but examples include iron- or aluminum-based metal base plates. Examples of iron-based metal base plates 11 include carbon steel plates and stainless steel plates. Examples of carbon steel plates include low-carbon aluminum-killed steel (carbon content: 0.01 to 0.15 wt.%), ultra-low carbon steel (carbon content: less than 0.01 wt.%), and non-aging carbon steel obtained by adding Ti, Nb, or the like to ultra-low carbon steel. When using a steel plate as the metal base plate 11, it is preferable to use a hot-rolled plate of such steel that is pickled to remove surface scale (oxide film), cold-rolled, electrolytically cleaned, annealed, and temper-rolled. The annealing method may be either continuous annealing or box annealing, and is not particularly limited.

[0023] The thickness of the metal plate 11 in this embodiment is not particularly limited, but is preferably 0.04 to 2.00 mm, and more preferably 0.04 to 1.50 mm.

[0024] The zinc-plated layer 12 is a layer containing zinc provided on the original metal sheet 11. In the case of an alloy, the zinc-plated layer 12 is composed of an alloy primarily containing zinc. Examples of metals constituting the zinc-plated layer 12 include zinc, zinc-cobalt-molybdenum alloy, zinc-cobalt alloy, zinc-nickel alloy, zinc-iron alloy, alloyed molten zinc, and zinc-aluminum-magnesium alloy. Among these metals obtained by zinc-based plating, zinc-cobalt-molybdenum alloy or pure zinc with a weight percentage of zinc of 99.9 wt % or more (hereinafter also referred to as "pure zinc") is more preferred from the viewpoint of improving the corrosion resistance of the surface-treated metal sheet 1. The zinc-plated layer 12 can be formed by electroplating the surface of the original metal sheet 11 using a plating bath of a predetermined composition.

[0025] The zinc content W (Zn) of the zinc plating layer 12 is preferably 3 to 30 g / m ２ and more preferably 5 to 20 g / m ２ The zinc content W(Zn) represents the amount on one surface of the metal original plate 11.

[0026] The thickness of the zinc plating layer 12 is not particularly limited, but is preferably 0.3 to 8.0 μm. As the zinc plating layer 12 becomes thicker, the surface roughness of the zinc plating layer 12 becomes slightly smoother, which may affect the subsequent formation of the zinc phosphate layer 20. In particular, in the case of zinc-based plating, crystals precipitate in a plate-like shape, which tends to make the surface roughness of the zinc plating layer 12 smoother. Therefore, from the viewpoint of suppressing reduction in surface roughness, the thickness of the zinc plating layer 12 is more preferably 0.3 to 5.0 μm. Even more preferably, from the viewpoint of corrosion resistance, the thickness is 0.6 to 5.0 μm. From the viewpoint of more preferably achieving both corrosion resistance and suppressing reduction in surface roughness due to zinc plating, the thickness of the zinc plating layer 12 is particularly preferably 0.7 μm to 4.5 μm.

[0027] In this embodiment, the zinc plating layer 12 is formed on both sides of the metal original plate 11, but the form of the metal substrate 10 is not particularly limited to this, and the zinc plating layer 12 may be formed on only one side of the metal original plate 11. Alternatively, the metal substrate 10 may not be provided with the zinc plating layer 12 and may be composed of only the metal original plate 11.

[0028] <Zinc phosphate layer 20> The zinc phosphate layer 20 is a layer made of zinc phosphate crystals formed on both sides of the metal substrate 10. The zinc phosphate layer 20 is formed to improve the adhesion of the surface-treated metal sheet 1 to the resin material (coating layer 40) (hereinafter also referred to as coating layer adhesion). The zinc phosphate crystals are needle-shaped or scale-shaped, and from the viewpoint of improving coating layer adhesion, needle-shaped zinc phosphate crystals are preferred. In this embodiment, the zinc phosphate layer 20 is formed on both sides of the metal substrate 10, but is not particularly limited thereto, and the zinc phosphate layer 20 may be formed on only one side of the metal substrate 10.

[0029] The phosphorus content W(P) contained in the zinc phosphate layer 20 is 100 to 300 mg / m ２ and preferably 120 to 280 mg / m ２ and more preferably 160 to 250 mg / m ２ By setting the phosphorus content W(P) within the above range and combining it with the control of the sealing layer 30, adhesion to the resin material (coating layer 40) can be ensured and blistering can be suppressed. If the phosphorus content W(P) is too low, the adhesion to the coating layer decreases, and if the phosphorus content W(P) is too high, it becomes difficult for the resin to penetrate to the base of the zinc phosphate crystals during the sealing process, which may make blisters more likely to occur. The phosphorus content W(P) can be determined by fluorescent X-ray analysis. Note that the phosphorus content W(P) represents the amount on one side of the metal substrate 10.

[0030] The zinc phosphate layer 20 may contain other inorganic components in the zinc phosphate crystals, such as zirconium, titania, alumina, calcium carbonate, talc, silica, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, etc. Among these, it is more preferable that zirconium is contained. The content of zirconium in the zinc phosphate layer 20 is 0.01 mg / m ２ Above, 1mg / m ２ Less than is preferred.

[0031] <Sealing layer 30> The sealing layer 30 is a layer containing a urethane resin and zirconium. The sealing layer 30 is formed to suppress moisture penetration from the outside into the zinc phosphate layer 20. In this embodiment, the sealing layer 30 is formed on each of the zinc phosphate layers 20 formed on both sides of the metal substrate 10, but the sealing layer 30 may be formed only on the zinc phosphate layer 20 on one side.

[0032] The urethane resin contained in the sealing layer 30 is a reaction product of a polyol and a polyisocyanate. Examples of polyols include polymer polyols such as polyacrylic polyols, polyester polyols, and polyether polyols. Examples of polyisocyanates include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, and araliphatic diisocyanates. The content of the urethane resin in the sealing layer 30 is preferably 85% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more, based on 100% by weight of the entire sealing layer 30.

[0033] The adhesion amount W(R) of the sealing layer 30 is 60 to 700 mg / m ２ From the viewpoint of more stably suppressing the occurrence of blisters and improving the adhesion of the coating layer, the amount is preferably 60 to 500 mg / m ２ and more preferably 70 to 240 mg / m ２ and more preferably 75 to 200 mg / m ２By using a sealing layer 30 containing a urethane resin and zirconium, setting the adhesion weight W(R) of the sealing layer 30 within the above range, and combining this with controlling the phosphorus content W(P) of the zinc phosphate layer 20, adhesion to the resin material (coating layer 40) can be ensured and blistering can be suppressed. If the adhesion weight W(R) of the sealing layer 30 is too low, the voids at the base of the zinc phosphate layer 20 will not be filled, making it difficult to suppress blistering. On the other hand, if the adhesion weight W(R) is too high, when forming the coating layer 40 on the surface-treated metal sheet 1 to produce the laminate 100, stress generated in the sealing layer 30 during the baking process after applying the resin material may be released during cooling after baking. This may cause the sealing layer 30 to shrink, enveloping the zinc phosphate layer 20, and may result in the creation of new voids between the sealing layer 30 and the metal substrate 10, or between the zinc phosphate layer 20 and the metal substrate 10. In this way, if the adhesion weight W(R) of the sealing layer 30 is too large, blisters may easily occur due to voids that occur at any interface of the laminate 100 after the baking process. Note that the adhesion weight W(R) of the sealing layer 30 represents the adhesion weight on one surface of the metal substrate 10.

[0034] In FIG. 1 , the sealing layer 30 is shown laminated on the zinc phosphate layer 20 to facilitate understanding of the order of the manufacturing process. However, because the zinc phosphate layer 20 is composed of needle-shaped or scale-shaped zinc phosphate crystals, in reality, as shown in FIG. 2 , the sealing layer 30 penetrates through the areas between the zinc phosphate crystals constituting the zinc phosphate layer 20 to the base of the zinc phosphate crystals. The sealing layer 30 may also be in contact with the zinc plating layer 12 of the metal substrate 10 between the bases of the zinc phosphate crystals. The sealing layer 30 may completely cover each zinc phosphate crystal, or may only cover some of the zinc phosphate crystals, such as the tops or sides of the zinc phosphate crystals. However, it is preferable that the sealing layer 30 cover the bases of the zinc phosphate crystals. In this way, the sealing layer 30 penetrates into the zinc phosphate layer 20, filling the spaces between the bases of the zinc phosphate crystals constituting the zinc phosphate layer 20. This prevents moisture from penetrating into the zinc phosphate layer 20 from the outside. Therefore, when the surface-treated metal plate 1 in this embodiment is laminated with a resin material (coating layer 40) to form a laminate 100, corrosion and gas generation due to moisture penetration can be suppressed, and the occurrence of blisters can be suppressed.

[0035] The inventors have discovered that when using a conventional surface-treated metal sheet having a zinc phosphate layer, the cause of blisters occurring after forming a coating layer made of a resin material is voids that form at the interfaces between the layers constituting the surface-treated metal sheet or within each layer. Through further testing to suppress blistering, the inventors have concluded that there are two patterns in which these voids form. The first pattern is that in a conventional surface-treated metal sheet having only a zinc phosphate layer without a sealing layer, the resin material has difficulty penetrating the spaces between the zinc phosphate crystals, resulting in voids where the resin material does not reach the base of the zinc phosphate layer. The inventors have found that the above problem can be solved by forming a predetermined sealing layer 30 on the zinc phosphate layer 20, allowing the sealing layer 30 to penetrate into the spaces between the zinc phosphate crystals and preventing voids from forming at the base of the zinc phosphate layer 20.

[0036] The second pattern is that stress generated in the resin material during the baking process of the coating layer made of a resin material formed on the surface of the surface-treated metal sheet is released during cooling, resulting in the formation of voids at one of the interfaces of the laminated material after the baking process. Furthermore, even when a sealing layer is formed on a conventional surface-treated metal sheet having a zinc phosphate layer to prevent voids from forming at the base of the zinc phosphate layer, new voids may still form between the sealing layer and the metal sheet or between the zinc phosphate layer and the metal sheet during the baking process of the coating layer formation process. The inventors have discovered that this second pattern is caused by stress generated within the sealing layer during the baking process, similar to the stress generated in the coating layer during baking, and the release of the stress during cooling causes the sealing layer to shrink, enveloping the zinc phosphate layer. Furthermore, the inventors have found that this phenomenon of stress generation within the sealing layer occurs when, for example, a phenolic resin or a silicone resin is selected as the material for the sealing layer, or even when a urethane resin is selected, if the adhesion amount is too high or if the sealing layer does not contain zirconium. The inventors have discovered that by making the sealing layer 30 a layer containing a urethane resin and zirconium, setting the adhesion amount W(R) of the sealing layer 30 within the above range, and combining this with controlling the phosphorus content W(P) of the zinc phosphate layer, it is possible to significantly suppress the formation of voids during application of the coating layer and the formation of voids after such a baking process.

[0037] The content of zirconium in the sealing layer 30 is preferably 1.5 to 23.0 mg / m ２ and more preferably 1.8 to 10 mg / m ２ and more preferably 1.8 to 6.0 mg / m ２ By including zirconium in the sealing layer 30 in the above range, the surface-treated metal sheet 1 can be made to have better adhesion to the resin material (coating layer 40). The zirconium content of the sealing layer 30 represents the amount on one surface of the metal substrate 10.

[0038] In addition to zirconium, the sealing layer 30 may contain other inorganic components, such as titania, alumina, calcium carbonate, talc, silica, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and the like.

[0039] The zirconium content W (Zr) of the surface-treated metal sheet 1 is expressed as a deposition amount per unit area of ​​the metal substrate 10, and is preferably 1.5 to 23.0 mg / m ２ and more preferably 1.8 to 11 mg / m ２ and more preferably 2.0 to 6.0 mg / m ２ When zirconium is contained in both the zinc phosphate layer 20 and the sealing layer 30, the zirconium content W(Zr) of the surface-treated metal sheet 1 is the total content of zirconium contained in the zinc phosphate layer 20 and the sealing layer 30. By setting the zirconium content W(Zr) within the above range, the surface-treated metal sheet 1 can be made to have an excellent blister suppression effect. Furthermore, it can be made to have excellent adhesion to the resin material (coating layer 40). The zirconium content W(Zr) represents the amount on one surface of the metal substrate 10.

[0040] The ratio "W(P) / W(R)" of the phosphorus content W(P) in the zinc phosphate layer 20 to the adhesion weight W(R) of the sealing layer 30 is preferably 0.3 to 3.5, more preferably 0.4 to 3.0, and even more preferably 1.0 to 3.0. By controlling the balance between the sealing layer 30 and the zinc phosphate layer 20 within the above range, the sealing layer 30 can fill the base of the zinc phosphate layer 20 on the surface-treated metal sheet 1, reducing voids, and leaving the surface irregularities formed by zinc phosphate crystals unfilled by the sealing layer 30. As a result, when a resin material (coating layer 40) is laminated on the surface-treated metal sheet 1, the adhesion of the coating layer can be improved while the occurrence of blisters can be further suppressed.

[0041] The ratio "W(P) / W(Zr)" of the phosphorus content W(P) contained in the zinc phosphate layer 20 to the total content W(Zr) of zirconium contained in the zinc phosphate layer 20 and the sealing layer 30 is preferably 10 to 120, more preferably 15 to 100, and even more preferably 40 to 80. By controlling "W(P) / W(Zr)" within the above range, when a resin material (coating layer 40) is laminated on the surface-treated metal sheet 1, the adhesion of the coating layer can be improved and the occurrence of blisters can be further suppressed.

[0042] <Method for manufacturing surface-treated metal sheet 1> The surface-treated metal sheet 1 in this embodiment can be manufactured by a method including a step of preparing a metal substrate 10, a zinc phosphate treatment step of forming a zinc phosphate layer 20 on the surface of the metal substrate 10, and a sealing step of forming a sealing layer 30 on the zinc phosphate layer 20.

[0043] In the step of preparing the metal substrate 10, the above-described metal original sheet 11 is prepared, and if necessary, a zinc plating layer 12 is formed on the metal original sheet 11. The metal plating conditions can be appropriately selected depending on the desired configuration of the zinc plating layer 12.

[0044] For example, when the zinc plating layer 12 is made of a zinc-cobalt-molybdenum alloy, it can be formed by electroplating using a plating bath having a composition of 150 to 300 g / L of zinc sulfate, 5 to 60 g / L of cobalt sulfate, 0.01 to 0.5 g / L of ammonium molybdate, 5 to 60 g / L of ammonium sulfate, and 50 g / L or less of sodium sulfate. The electroplating conditions are preferably pH 2.0 to 4.5, bath temperature 30 to 60°C, and current density 5 to 50 A / dm ２ is.

[0045] When the zinc-cobalt-molybdenum alloy is used for the zinc-plated layer 12, the zinc, cobalt, and molybdenum contents of the zinc-plated layer 12 are preferably 0.1 to 5 wt % cobalt, 0.001 to 1 wt % molybdenum, and the remainder zinc. The metal contents of the zinc-plated layer 12 can be adjusted by adjusting the composition of the plating bath and the electroplating conditions to suitable ranges.

[0046] Furthermore, for example, when the zinc plating layer 12 is made of pure zinc, it can be formed by electroplating using a plating bath having a composition of, for example, 150 to 300 g / L of zinc sulfate and 10 to 100 g / L of sodium sulfate. The electroplating conditions are preferably pH 0.5 to 3.0, bath temperature 30 to 60°C, and current density 5 to 80 A / dm ２ is.

[0047] In the zinc phosphate treatment step, a zinc phosphate layer 20 made of zinc phosphate crystals is formed on the surface of the metal substrate 10. Specifically, the metal substrate 10 is subjected to surface conditioning as a pretreatment, and then immersed in a zinc phosphate treatment solution containing zinc phosphate crystals as a main treatment, followed by rinsing with water and drying, thereby forming the zinc phosphate layer 20. A known surface conditioner containing Ti colloid or zinc phosphate colloid can be used for the surface conditioning. The zinc phosphate treatment solution may further contain hydrosilicic acid as an etching agent, zinc nitrate as an accelerator, and zirconium or the like as an inorganic component.

[0048] Commercially available zinc phosphate treatment solutions may be used, such as Palbond (registered trademark) and Enares (registered trademark) manufactured by Nippon Parkerizing Co., Ltd., and Surfdyne (registered trademark) manufactured by Nippon Paint Surf Chemicals Co., Ltd.

[0049] The amount of phosphorus attached to the metal substrate 10 in the zinc phosphate treatment step, i.e., the phosphorus content W(P) contained in the zinc phosphate layer 20, is 100 to 300 mg / m ２ and preferably 150 to 250 mg / m ２ In addition, when zirconium is contained in the treatment solution in the zinc phosphate treatment step, the content of zirconium in the formed zinc phosphate layer 20 is 0.01 mg / m ２ Above, 1mg / m ２ It is preferable that it is less than 1000 kJ / s.

[0050] Next, in the sealing step, a sealing layer 30 is formed on the metal substrate 10 on which the zinc phosphate layer 20 has been formed. Specifically, an aqueous dispersion (sealing treatment liquid) containing a urethane resin and zirconium is applied to the surface of the zinc phosphate layer 20 by immersion or by roll coating, and then dried to form the sealing layer 30. The drying temperature varies depending on the type of resin, but is preferably 80 to 150°C.

[0051] The solid content concentration (urethane resin concentration) of the sealing treatment liquid is preferably 3 to 40% by weight, more preferably 3 to 30% by weight, and even more preferably 4 to 20% by weight.

[0052] The pH of the sealing treatment liquid is preferably 3 to 11, and more preferably 4 to 10. The viscosity of the sealing treatment liquid at 20°C is preferably 0.5 to 3.0 mPa·s, more preferably 1.0 to 2.0 mPa·s, and even more preferably 1.2 to 1.8 mPa·s.

[0053] The zirconium content of the sealing treatment liquid is preferably 1.0 to 5.0 g / L. By setting the zirconium content of the sealing treatment liquid within the above range, the zirconium content W (Zr) can be appropriately controlled within a range that makes it easy to form the sealing layer 30 when applying the sealing layer 30 to the resulting surface-treated metal sheet 1, and the sealing layer 30 can be embedded in the base of the zinc phosphate layer 20, thereby further improving the adhesion of the surface-treated metal sheet 1 to the resin material (coating layer 40) and suppressing the occurrence of blisters.

[0054] The sealing treatment liquid may further contain a crosslinking agent. When a crosslinking agent is contained, a crosslinked structure can be introduced by crosslinking the urethane-based resin particles, thereby improving the adhesion durability of the surface-treated metal sheet 1 to the resin material (coating layer 40). As the crosslinking agent, a crosslinking agent containing an amino group, an oxazoline group, an epoxy group, a carbodiimide group, or the like can be used.

[0055] The adhesion amount W(R) of the sealing layer 30 in the sealing step is 60 to 700 mg / m ２ and preferably 60 to 500 mg / m２ and more preferably 70 to 240 mg / m ２ By setting the adhesion weight W(R) of the sealing layer 30 within the above range, it is possible to suppress the occurrence of blisters when a resin material (coating layer 40) is formed on the surface-treated metal sheet 1.

[0056] Furthermore, the ratio "W(P) / W(R)" of the phosphorus content W(P) contained in the zinc phosphate layer 20 to the adhesion amount W(R) of the sealing layer 30 is preferably 0.3 to 3.5, more preferably 0.4 to 3.0, and even more preferably 1.0 to 3.0. By setting "W(P) / W(R)" within the above range, the occurrence of blisters can be further suppressed.

[0057] The ratio "W(P) / W(Zr)" of the phosphorus content W(P) contained in the zinc phosphate layer 20 to the total content W(Zr) of zirconium contained in the zinc phosphate layer 20 and the sealing layer 30 is preferably 10 to 120, more preferably 15 to 100, and even more preferably 40 to 80. By controlling "W(P) / W(Zr)" within the above range, when a resin material (coating layer 40) is laminated on the surface-treated metal sheet 1, the adhesion of the coating layer can be improved and the occurrence of blisters can be further suppressed.

[0058] The surface-treated metal sheet 1 of this embodiment can be manufactured in the above manner. The surface-treated metal sheet 1 thus obtained has enhanced adhesion to the resin material (coating layer 40) due to the zinc phosphate layer 20, and the sealing layer 30 suppresses the formation of voids within the zinc phosphate layer 20, thereby suppressing the occurrence of blisters when the resin material (coating layer 40) is laminated. Blisters are likely to occur in components used in humid environments, particularly high-temperature humid environments or pressure environments (e.g., packing components in piping), when moisture or humidity penetrates the resin and reaches the gap between the resin and the surface-treated metal sheet, creating a corrosive environment on the metal sheet surface. Similarly, when the resin on the surface of a laminate is scratched, the metal sheet surface is likely to become corrosive. In this case, if there is a void between the resin and the surface-treated metal sheet, the environment is particularly likely to become corrosive, accelerating the occurrence of blisters. In contrast, the surface-treated metal sheet 1 of this embodiment suppresses the formation of voids within the zinc phosphate layer 20, thereby significantly suppressing the surface of the metal substrate 10 from becoming a corrosive environment. Therefore, the surface-treated metal sheet 1 of this embodiment can improve the appearance of the laminate material 100 obtained by laminating the coating layer 40 made of a resin material thereon. Furthermore, since it is possible to suppress leakage due to blisters, i.e., the leakage of gas or liquid to the outside through voids formed by the formation of blisters, it is possible to suppress a decrease in corrosion resistance. Furthermore, the laminate material 100 obtained using the surface-treated metal sheet 1 of this embodiment suppresses the formation of blisters, has an excellent appearance, and is able to suppress a decrease in corrosion resistance. Therefore, it can be suitably used as a water system piping component, an interior or exterior building component, an outdoor electrical component, an automotive exterior component, an automotive inner layer component, a gasket material, or a bearing material.

[0059] The resin material used for the coating layer 40 laminated on the surface-treated metal sheet 1 is not particularly limited, but examples thereof include phenolic epoxy resins, ethylene vinyl acetate resins, etc. The coating layer 40 may be formed directly on the surface-treated metal sheet 1, or an adhesive resin may be disposed on the surface-treated metal sheet 1 and the coating layer 40 may be formed via the adhesive resin. Examples of such adhesive resins include olefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, ethylene-acrylic acid copolymer, and ethylene-methacrylic acid copolymer, as well as urethane resins.

[0060] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0061] <Phosphorus Deposition Amount W (P) and Zirconium Content W (Zr)> The surface-treated metal sheet 1 obtained in each example was measured using an X-ray fluorescence analyzer to determine the phosphorus deposition amount W (P), zirconium content W (Zr), and zinc deposition amount. The X-ray fluorescence analyzer used was a ZSX100e (manufactured by Rigaku Corporation). It was confirmed that the X-ray fluorescence measurement enabled quantification of the metal elements contained in the surface treatment layer of the surface-treated metal sheet 1 using a calibration curve method. Here, the term "surface treatment layer" refers to all layers (i.e., the zinc phosphate layer 20 and the sealing layer 30) formed on the steel sheet in the surface-treated metal sheet 1 of each example.

[0062] <Sealing layer adhesion weight W(R)> For the surface-treated metal sheet 1 obtained in each example, the weight of the metal sheet was measured before and after the sealing process, and the difference was calculated as the sealing layer adhesion weight to determine the adhesion weight W(R) of the sealing layer 30.

[0063] <Appearance Evaluation> A phenolic epoxy solvent (E-361-1 manufactured by Toyochem Co., Ltd.) was applied to the obtained surface-treated metal sheet 1 and dried at 205°C for 10 minutes to form a 15 μm coating layer 40 on the surface of the surface-treated metal sheet 1, thereby obtaining a laminate 100. This laminate 100 was subjected to a steam exposure test under conditions of a temperature of 146°C, a relative humidity of 100% Rh, and 168 hours. Thereafter, the surface of the laminate 100 was observed with an optical microscope, and the number of blisters with a diameter of 10 μm or more in an area of ​​1 mm length x 0.7 mm width in the optical microscope photograph was counted and evaluated as follows: A: 0 to 1 (almost no blisters); B: 2 to 4 (few blisters); C: 5 to 19 (slightly many blisters); D: 20 or more (very many blisters); E: 20 or more blisters with a diameter of 20 μm or more (very many blisters and some large blisters present).

[0064] <Resin Adhesion> A vinyl acetate resin was thermocompression bonded to the obtained surface-treated metal sheet 1, and a T-peel test (hereinafter also referred to as a peel test) was performed in accordance with JIS K 6854-3 to measure the peel strength of the surface-treated metal sheet 1 against the vinyl acetate resin. Specifically, two surface-treated metal sheets 1 each having a width of 25 mm and a length of 80 mm were arranged facing each other, and a vinyl acetate resin (product name: Mersen, manufactured by Tosoh Corporation) was sandwiched between the two surface-treated metal sheets 1. The surface-treated metal sheet 1 and the vinyl acetate resin were thermocompression bonded at a temperature of 150°C, a pressure of 0.5 MPa, and a time of 2 minutes to obtain a laminate 100. The prepared laminate 100 was subjected to a peel test at a peel rate of 200 mm / min using a tensile tester (product name "AGX-V," manufactured by Shimadzu Corporation), and the maximum peel strength [unit: N / 20 mm] was measured. If the maximum peel strength is 5 N / 20 mm or more, it can be determined that the resin adhesion is excellent and that there is no significant decrease in adhesion due to the formation of the sealing layer 30.

[0065] Example 1 A cold-rolled sheet (thickness: 0.2 mm) of low-carbon aluminum-killed steel was prepared as the metal base sheet 11. Next, this metal base sheet 11 was subjected to alkaline electrolytic degreasing and pickling by immersion in sulfuric acid, and then pickled in a bath temperature of 40°C at a current density of 15 A / dm ２By carrying out plating under the above conditions, a metal substrate 10 was obtained in which a zinc plating layer 12 made of zinc-cobalt-molybdenum alloy plating was formed on both sides of a metal original sheet 11. The composition of the zinc plating layer 12 was measured using an X-ray fluorescence analyzer and found to be Co: 0.16 wt %, Mo: 0.02 wt %, the balance Zn, and the zinc content W(Zn) was 10 g / m ２ It was.

[0066] Next, the metal substrate 10 was immersed in a surface conditioner and a zinc phosphate treatment solution in that order, followed by rinsing with water and drying, thereby forming a zinc phosphate layer 20 on both sides of the metal substrate 10. The surface conditioner and zinc phosphate treatment solution used were those with the following conditions: {Surface conditioner (pretreatment)} Bath composition: Preparene (manufactured by Nihon Parkerizing Co., Ltd.) 4 g / L Bath temperature: 50°C pH: 6.0 to 9.0 {Zinc phosphate treatment solution (main treatment)} Bath composition: Palbond (manufactured by Nihon Parkerizing Co., Ltd.) 50 g / L Bath temperature: 50°C pH: 2.0 to 3.0

[0067] Next, an aqueous dispersion containing a urethane resin and zirconium (solid content 7% by weight, viscosity 1.6 mPa·s at 20°C, pH 6.5, zirconium content 2.6 g / L) was applied onto the zinc phosphate layer 20 using a roll coater, and dried at a temperature of 100°C for 2 seconds to form a sealing layer 30. The adhesion weight W(R) of the sealing layer 30 was 100 mg / m ２ In this manner, a surface-treated metal sheet 1 was obtained. The obtained surface-treated metal sheet 1 was evaluated using the method described above. The results are shown in Table 1. As will be described later, the conditions for forming the zinc phosphate layer 20 were the same in all of Examples 1 to 4 and Comparative Examples 1 to 10. Therefore, the zirconium content in the sealing layer 30 in Example 1 was calculated by subtracting the zirconium content measured in Comparative Example 1, in which the sealing layer 30 was not formed (i.e., the zirconium content in the zinc phosphate layer 20), from the zirconium content W(Zr) in the surface treatment layer in Example 1. In the subsequent Examples and Comparative Examples, the zirconium content in the sealing layer 30 was calculated using the same method.

[0068] Examples 2 to 4, Comparative Examples 3 and 4 Surface-treated metal sheets 1 were obtained and evaluated in the same manner as in Example 1, except that the adhesion weight W(R) of the sealing layer 30 was changed to the value shown in Table 1. The results are shown in Table 1.

[0069] Comparative Example 1 A surface-treated metal sheet was obtained and evaluated in the same manner as in Example 1, except that the metal substrate 10 having the zinc phosphate layer 20 formed thereon was not subjected to a sealing treatment. The results are shown in Table 1.

[0070] Comparative Example 2 A surface-treated metal sheet was obtained and evaluated in the same manner as in Example 1, except that an aqueous dispersion containing a phenolic resin (solid concentration by weight: 13%, viscosity at 20°C: 1.9 mPa s, pH 4.0) was used instead of the aqueous dispersion containing a urethane resin during the sealing treatment. The results are shown in Table 1.

[0071] Comparative Examples 5 to 8 Surface-treated metal sheets were obtained and evaluated in the same manner as in Example 1, except that, during the sealing treatment, an aqueous dispersion containing a silicone resin was used instead of the aqueous dispersion containing a urethane resin, and the sealing layer adhesion weight W(R) was changed to the value shown in Table 1. The results are shown in Table 1.

[0072] <Comparative Examples 9 and 10> Surface-treated metal sheets were obtained and evaluated in the same manner as in Example 1, except that an aqueous dispersion containing a urethane resin but not containing zirconium (solid content concentration 7% by weight, viscosity at 20°C 1.6 mPa s, pH 6.5) was used for the sealing treatment, and the sealing layer adhesion weight W(R) was changed to the value shown in Table 1. The results are shown in Table 1.

[0073]

[0074] As shown in Table 1, the sealing layer 30 has a zinc phosphate layer 20 and a sealing layer 30 containing zirconium and a urethane resin, and the phosphorus content W(P) is 100 to 300 mg / m ２ and the adhesion amount W(R) of the sealing layer is 60 to 700 mg / m ２The surface-treated metal sheets 1 of Examples 1 to 4, in which the coating layer 40 made of a resin material was formed, suppressed the occurrence of blisters and also had excellent adhesion to the resin material (coating layer 40). In particular, in Examples 1 and 2, in which the ratio "W(P) / W(R)" of the phosphorus content W(P) contained in the zinc phosphate layer 20 to the sealing layer adhesion amount W(R) was appropriately controlled, the occurrence of blisters could be significantly suppressed.

[0075] On the other hand, the surface-treated metal sheets of Comparative Example 1, which does not have a sealing layer, Comparative Example 2, which uses a phenolic resin as the sealing layer, Comparative Examples 3 and 4, which have a sealing layer adhesion amount W(R) outside the specific range, Comparative Examples 5 to 8, which use a silicone resin as the sealing layer, and Comparative Examples 9 and 10, which use a urethane resin that does not contain zirconium as the sealing layer, resulted in the generation of many blisters when the resin material was laminated.

[0076] DESCRIPTION OF SYMBOLS 1... Surface-treated metal sheet 10... Metal substrate 11... Original metal sheet 12... Zinc plating layer 20... Zinc phosphate layer 30... Sealing layer 100... Laminated material 40... Coating layer

Claims

1. A method for manufacturing a metal substrate, comprising: a step of preparing a metal substrate; a zinc phosphate treatment step of forming a zinc phosphate layer on the surface of the metal substrate; and a sealing step of forming a sealing layer on the zinc phosphate layer, wherein the phosphorus content W(P) contained in the zinc phosphate layer is 100 to 300 mg / m ２ The sealing layer contains zirconium and a urethane resin, and the adhesion amount W(R) of the sealing layer is 60 to 700 mg / m ２ The method for manufacturing a surface-treated metal sheet is as follows.

2. A method for manufacturing a surface-treated metal sheet according to claim 1, wherein the ratio "W(P) / W(R)" of the phosphorus content W(P) contained in the zinc phosphate layer to the adhesion amount W(R) of the sealing layer is 0.3 to 3.

5.

3. A method for producing a surface-treated metal sheet according to claim 1 or 2, wherein the step of preparing the metal substrate includes forming a zinc plating layer on the surface of the metal substrate.

4. The method for producing a surface-treated metal sheet according to any one of claims 1 to 3, wherein the zirconium content W (Zr) of the surface-treated metal sheet is 1.5 to 23.0 mg / m ２ The method for manufacturing a surface-treated metal sheet is as follows.

5. A surface-treated metal sheet comprising a metal substrate, a zinc phosphate layer formed on at least one surface of the metal substrate, and a sealing layer formed by laminating on the zinc phosphate layer, wherein the phosphorus content W(P) contained in the zinc phosphate layer is 100 to 300 mg / m ２ the sealing layer is made of a urethane resin containing zirconium, and the adhesion amount W(R) of the sealing layer is 60 to 700 mg / m ２ A surface-treated metal plate.

6. The surface-treated metal sheet according to claim 5, wherein the zirconium content W (Zr) is 1.5 to 23.0 mg / m ２ A surface-treated metal plate.

7. A surface-treated metal sheet according to claim 5 or 6, wherein the ratio "W(P) / W(R)" of the phosphorus content W(P) contained in the zinc phosphate layer to the adhesion amount W(R) of the sealing layer is 0.3 to 3.

5.

8. A surface-treated metal sheet according to any one of claims 5 to 7, wherein the ratio "W(P) / W(Zr)" of the phosphorus content W(P) contained in the zinc phosphate layer to the zirconium content W(Zr) is 10 to 120.

9. A surface-treated metal sheet according to any one of claims 5 to 8, wherein the metal substrate comprises an original metal sheet and a zinc plating layer mainly containing zinc, and the zinc phosphate layer is formed on the zinc plating layer.

10. The surface-treated metal sheet according to claim 9, wherein the zinc content W(Zn) of the zinc plating layer is 3 to 30 g / m ２ A surface-treated metal plate.

11. A laminate comprising the surface-treated metal sheet according to any one of claims 5 to 10, and a coating layer made of a resin material and formed on the sealing layer.

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