JP2022149319A - Precoat plated steel sheet - Google Patents

Abstract

To achieve further improvement of scratch resistance while keeping workability.SOLUTION: A precoat plated steel sheet includes a plated steel sheet having a plating layer on a surface of the steel sheet, and a colored film layer positioned on the plating layer, wherein the plating layer has Vickers hardness of 100-800 Hv, thickness of the colored film layer is 1-10 μm, and the colored film layer contains a film-forming component having a glass transition point Tg of 30°C or higher, and resin particles.SELECTED DRAWING: Figure 1A

Description

The present invention relates to a precoat plated steel sheet.

Organic resin-coated steel sheets (also known as pre-coated steel sheets) are made by coating the surface layer of zinc-based steel sheets with an organic resin film to replace conventional post-coated products that are coated after molding, such as for home appliances, building materials, and automobiles. ) has come into use. This pre-coated steel sheet is a steel sheet that has undergone rust prevention treatment or a plated steel sheet and is coated with a colored organic film. have. This organic resin-coated plated steel sheet is often used as a material for home appliances, building materials, automobiles, etc., without being subjected to further coating after press working. Therefore, such an organic resin-coated plated steel sheet is required to have excellent scratch resistance so as not to lose its beauty during processing. Therefore, various techniques have been proposed in the past in order to improve various properties such as scratch resistance of precoated steel sheets.

For example, Patent Document 1 below proposes a technique of providing a colored coating film containing two types of particles having a predetermined average particle size and a coloring pigment on at least one side of a metal plate.

JP 2012-121020 A

However, the technique disclosed in the above-mentioned Patent Document 1 is to contain spherical silica particles having an average particle diameter of 5 to 50 nm in a colored film having a thickness of 2 to 10 μm, thereby achieving a resistance to a predetermined pencil hardness. Although scratchability is obtained, the resistance to scratches due to contact with harder substances such as metals is not sufficient, and there is still room for improvement.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a precoat that can further improve scratch resistance while maintaining workability. To provide a plated steel sheet.

In order to solve the above problems, the present inventors have made intensive studies and found that by setting the hardness of the plating used for the pre-coated plated steel sheet to an appropriate range and the softening temperature of the coating to an appropriate range, it is possible to improve the scratch resistance. Based on the idea that it might be possible to further improve the sticking property, the present invention was completed.
The gist of the present invention completed based on this idea is as follows.

(1) A plated steel sheet having a plated layer on the surface of the steel sheet, and a colored film layer located on the plated layer, the plated layer having a Vickers hardness of 100 to 800 Hv, and the thickness of the colored film layer is 1 to 10 μm, and the colored film layer contains a film-forming component having a glass transition point Tg of 30° C. or higher and resin particles.
(2) The precoated plated steel sheet according to (1), wherein the content of the resin particles in the colored film layer is 5 to 50% by mass with respect to the total content of the film-forming component and the resin particles. .
(3) The precoat plated steel sheet according to (1) or (2), wherein the resin particles have an average particle size of 1 to 15 μm.
(4) Any one of (1) to (3), wherein the colored film layer has a Vickers hardness of 10 to 70 Hv measured at an indentation depth of 3/4 of the thickness of the film from the surface layer. pre-coated plated steel sheet.
(5) The precoated plated steel sheet according to any one of (1) to (4), wherein the colored film layer contains, as the film-forming component, a resin of the same type as the resin that is the material of the resin particles.
(6) The precoat plated steel sheet according to any one of (1) to (5), wherein the resin particles are acrylic resin particles, and the film-forming component is an acrylic resin.
(7) The precoated plated steel sheet according to any one of (1) to (6), wherein the plated steel sheet is a zinc-based plated steel sheet.
(8) The plating layer contains Al: 4 to 22% by mass, Mg: 1 to 10% by mass, Si: 0.0001 to 2.0000% by mass, and the balance is Zn and impurities. , The precoat plated steel sheet according to any one of (1) to (7).
(9) The precoat plated steel sheet according to (7) or (8), wherein the coating amount of the plating layer on both sides of the steel sheet is 30 to 600 g/m ² in total.
(10) The precoated plated steel sheet according to any one of (1) to (9), wherein the colored film layer contains at least one of aluminum pigment, carbon black and TiO ₂ as a coloring pigment.
(11) The precoat plated steel sheet according to any one of (1) to (10), wherein the colored film layer further contains an antirust pigment.
(12) The precoated plated steel sheet according to any one of (1) to (11), further comprising a chemical conversion film layer between the plated layer and the colored film layer.

As described above, according to the present invention, it is possible to further improve the scratch resistance while maintaining workability.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which showed typically the structure of the precoat plated steel plate which concerns on embodiment of this invention. It is explanatory drawing which showed typically the structure of the precoat plated steel plate which concerns on the same embodiment.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

(Regarding pre-coated plated steel sheets)
Hereinafter, a precoat plated steel sheet according to an embodiment of the present invention will be described in detail with reference to FIGS. 1A and 1B. 1A and 1B are explanatory diagrams schematically showing the structure of the precoat plated steel sheet according to this embodiment.

As schematically shown in FIG. 1A, the precoat plated steel sheet 1 according to the present embodiment includes a steel sheet 10 as a base material, a plating layer 20 provided on the surface of the steel sheet 10, and a coating layer 20 on the surface of the plating layer 20. and a positioned colored film layer 30 . Moreover, as shown in FIG. 1A, it is preferable to further have a chemical conversion coating layer 40 between the plating layer 20 and the colored coating layer 30 .

Further, the plated layer 20, the colored film layer 30 and the chemical conversion film layer 40 may be provided on both sides of the steel sheet 10 as schematically shown in FIG. 1B.

<About the steel plate 10>
The steel sheet used as the base material is not particularly limited, and various steel sheets can be used according to the mechanical strength and the like required for the precoat plated steel sheet 1 . As such a steel plate 10, for example, Al-killed steel, ultra-low carbon steel containing Ti, Nb, etc., high-strength steel containing ultra-low carbon steel further containing strengthening elements such as P, Si, Mn, etc. Various steel plates such as

In addition, the thickness of the steel sheet 10 according to the present embodiment is not particularly limited, and may be appropriately set according to the mechanical strength required for the precoat plated steel sheet 1, for example, 0.2 mm to 10.0 mm. can be to some extent.

<Regarding plating layer 20>
The plating layer 20 of the precoat plated steel sheet 1 according to the present embodiment has a Vickers hardness (the test load is set according to the thickness of the plating layer) defined in JIS Z2244: 2009. The plating is 100 to 800 Hv. layer. When the plating layer 20 has such a hardness, the hardness of the colored film layer 30 located above the plating layer 20 is influenced by the plating layer 20, thereby exhibiting better scratch resistance.

When the Vickers hardness of the plating layer 20 is less than 100 Hv, the hardness of the plating layer 20 is insufficient, and the above effects cannot be exhibited. The Vickers hardness of the plating layer 20 is preferably 110 Hv or higher, more preferably 120 Hv or higher.

On the other hand, when the Vickers hardness of the plating layer 20 exceeds 800 Hv, the workability is inferior, which is not preferable. The Vickers hardness of the plating layer 20 is preferably 600 Hv or less, more preferably 500 Hv or less.

The type of plating is not particularly limited as long as the Vickers hardness as described above can be achieved. However, by using zinc-based plating, it is possible to more easily achieve the above Vickers hardness. Examples of such zinc-based plating include zinc-nickel alloy plating, alloyed hot-dip zinc plating, aluminum-zinc alloy plating, zinc-aluminum-magnesium alloy plating, zinc-vanadium composite plating, zinc-zirconium composite plating, and the like. .

Among such zinc-based platings, zinc-aluminum-magnesium alloy plating is particularly preferable, and contains Al: 4 to 22% by mass, Mg: 1 to 10% by mass, and Si: 0.0001 to 2.0000% by mass. Zinc-aluminum-magnesium-silicon alloy plating, in which the balance is Zn and impurities, is more preferred.

[Al: 4 to 22% by mass]
The corrosion resistance of the precoat plated steel sheet 1 according to the present embodiment is improved by setting the Al content to 4% by mass or more and 22% by mass or less. If the Al content is less than 4% by mass, the corrosion resistance may deteriorate. The content of Al is preferably 5% by mass or more. On the other hand, if the Al content exceeds 22% by mass, the effect of improving the corrosion resistance of the plating layer 20 may be saturated. The Al content is preferably 16% by mass or less.

[Mg: 1 to 10% by mass]
The corrosion resistance of the precoat plated steel sheet 1 according to the present embodiment is improved by setting the Mg content to 1% by mass or more and 10% by mass or less. If the Mg content is less than 1% by mass, the effect of improving the corrosion resistance of the precoat plated steel sheet 10 may be insufficient. The content of Mg is preferably 2% by mass or more. On the other hand, when the Mg content exceeds 10% by mass, dross generation in the plating bath becomes significant, which may make it difficult to stably produce a hot-dip plated steel sheet. The content of Mg is preferably 5% by mass or less.

[Si: 0.0001 to 2.0000% by mass]
By setting the Si content to 0.0001% by mass or more and 2.0000% by mass or less, it is possible to ensure the adhesion of the plating layer 20 . If the Si content exceeds 2.0000% by mass, the effect of improving the adhesion of the plating layer 20 may be saturated. The Si content is more preferably 1.6000% by mass or less.

Furthermore, in the plating layer 20 according to the present embodiment, elements such as Fe, Sb, and Pb may be contained singly or in combination in an amount of 1% by mass or less in place of part of the remaining Zn.

As the plated steel sheet provided with the plating layer 20 having the chemical composition as described above, for example, a hot dip zinc- An aluminum-magnesium-silicon alloy plated steel sheet (for example, "Superdyma (registered trademark)" manufactured by Nippon Steel Corporation) and the like can be mentioned.

The plated layer 20 according to this embodiment as described above can be manufactured, for example, as follows. First, the surface of the prepared steel plate 10 is subjected to pretreatment such as cleaning and degreasing as necessary. After that, the steel sheet, which has been pretreated as necessary, is immersed in a hot-dip plating bath having a desired chemical composition, and the steel sheet is pulled out of the plating bath. In such a plating operation, the plating may be performed by either a continuous plating method for coils or a plating method for individual cut plates.

The temperature of the hot-dip plating bath varies depending on the composition, but is preferably in the range of 400-500° C., for example.

In addition, the coating amount as described above can be controlled by adjusting the lifting speed of the steel sheet, the flow rate of the wiping gas ejected from the wiping nozzle provided above the plating bath, and the flow rate adjustment. The total coating weight on both sides of the steel sheet is preferably 30 to 600 g/m ² (that is, 15 to 300 g/m ² per side). If the adhesion amount is less than 30 g/m ² , the corrosion resistance is lowered, which is not preferable. If the coating amount exceeds 600 g/m ² , the molten metal that adheres to the steel sheet will drip, making it impossible to smoothen the surface of the hot-dip plated layer, which is not preferable. By providing the plating layer 20 with the amount of adhesion as described above, it is possible to more reliably achieve the Vickers hardness as described above. More preferably, the coating amount of the plating layer 20 on both sides of the steel sheet is 40 to 550 g/m ² in total. After adjusting the adhesion amount of the hot-dip coating layer, the steel sheet is cooled. At this time, the cooling conditions need not be particularly limited.

<Regarding the colored film layer 30>
The colored film layer 30 is a film layer colored in a desired color by containing a color pigment. The colored film layer 30 contains a film-forming component 301 having a glass transition point Tg of 30° C. or higher and resin particles 303, as schematically shown in FIGS. 1A and 1B. Due to the film-forming component 301 having the glass transition point Tg as described above, the colored film layer 30 has an appropriate hardness, and the scratch resistance of the precoated plated steel sheet 1 (in particular, resistance to scratches) is improved. can be made In addition, since the colored film layer 30 contains the resin particles 303, the impact applied to the colored film layer 30 can be reduced due to the toughness and ductility of the resin particles 303, and the scratch resistance of the colored film layer 30 can be improved. Adherability (in particular, resistance to scratches) can be improved. Moreover, even if the colored film layer 30 is damaged, the damage can be prevented from reaching the plating layer 20, and the corrosion resistance of the precoated plated steel sheet 1 can be maintained.

If the glass transition point Tg of the film forming component 301 is less than 30° C., the hardness of the colored film layer 30 is insufficient, and desired scratch resistance cannot be exhibited. The glass transition point Tg of the film forming component 301 is preferably 35° C. or higher, more preferably 40° C. or higher. On the other hand, the upper limit of the glass transition point Tg is not particularly specified, but if it exceeds 70°C, workability may deteriorate. Therefore, the glass transition point Tg of the film-forming component 301 is preferably 70° C. or lower. The glass transition point Tg can be determined, for example, by TMA (thermo-mechanical analysis), by inserting a needle from the surface of the film to be measured in the film thickness direction, causing a constant temperature change, and changing the thermal expansion of the object to be measured. or by DMA (dynamic viscoelasticity measurement), the viscoelasticity is analyzed by periodically changing the temperature of the film peeled off from the substrate and changing the temperature. It is possible to specify by a method or the like.

The resin particles 303 are particulate substances manufactured by using an organic resin as a raw material. By including such resin particles 303 in the colored film layer 30, the impact applied to the colored film layer 30 can be mitigated by the toughness and ductility of the resin particles 303, as mentioned above. Moreover, even if the colored film layer 30 is scratched, the scratch can be prevented from reaching the plating layer 20 .

In the precoat plated steel sheet 1 according to this embodiment, the thickness of the colored film layer 30 is 1 to 10 μm. If the thickness of the colored film layer 30 is less than 1 μm, the desired scratch resistance cannot be exhibited. The thickness of the colored film layer 30 is preferably 2 μm or more, more preferably 3 μm or more. On the other hand, if the thickness of the colored film layer 30 exceeds 10 μm, it is costly and may cause coating film defects such as popping, making it difficult to obtain a stable appearance. The thickness of the colored film layer 30 is preferably 8 μm or less, more preferably 7 μm or less.

The thickness of the colored film layer 30 can be measured by observing the cross section of the coating film or using an electromagnetic film thickness meter. Alternatively, it may be calculated by dividing the mass of the coating film adhered per unit area by the specific gravity of the coating film or the post-drying specific gravity of the composition. When the thickness is measured by cross-sectional observation, the thickness is measured at a plurality of arbitrary positions (for example, 10 positions), and the average value of the obtained plurality of thicknesses is used as the thickness of the colored film layer 30 .

The colored film layer 30 has a Vickers hardness measured from the surface layer to a depth of indentation of 3/4 of the thickness of the film (the test load is a size that can realize a desired indentation depth, and the hardness of the colored film layer 30 is ) is preferably 10 to 70Hv. Such Vickers hardness is measured using a universal hardness tester (manufactured by Fisher Instruments Co., Ltd.). Regardless of the position where the resin particles 303 are present or not, the hardness is measured from the film surface under the indentation depth conditions as described above at any 10 positions, and the 10 measurements obtained. Calculate the average of the values. When the colored film layer 30 has the above Vickers hardness, it becomes possible to further improve the scratch resistance. The Vickers hardness of the colored film layer 30 is more preferably 15 to 65 Hv.

In the colored film layer 30 according to this embodiment, the content of the resin particles 303 is preferably 5 to 50% by mass with respect to the total content of the film-forming component 301 and the resin particles 303 . When the content of the resin particles 303 is within the range described above, it becomes easier to achieve the Vickers hardness described above, and the scratch resistance can be further improved. The content of resin particles 303 in colored film layer 30 is more preferably 10 to 45% by mass.

Here, in the colored film layer 30 according to the present embodiment, the film-forming component 301 that functions as a binder for the resin particles 303 is preferably the same resin as the resin that is the material of the resin particles 303 . By using such a film-forming component 301, the affinity between the film-forming component 301 and the resin particles 303 can be further improved, and the scratch resistance of the colored film layer 30 can be further improved. Become.

The resin used as the material of the resin particles 303 is not particularly limited, and particles made of various organic resins can be used, but it is preferable to use resin particles made of acrylic resin. By using such acrylic resin particles as the resin particles 303, it becomes easier to achieve the Vickers hardness described above at a lower cost.

In place of the resin particles 303, inorganic particles made of an inorganic compound such as silica or ceramics may be used. However, since the inorganic particles are fragile particles, the effects of using the resin particles 303 as described above cannot be obtained.

In this embodiment, the average particle diameter of the resin particles 303 is preferably 1 to 15 μm. When the resin particles 303 have the average particle diameter as described above, it is possible to further improve the scratch resistance of the precoated plated steel sheet.

Here, the average particle size refers to the particle size that is 50% by mass from the smaller particle size in the cumulative distribution curve of the particle size, and is measured by a known measurement method such as a dynamic light scattering method or a laser diffraction method. It is possible. Moreover, the average particle diameter of the resin particles 303 already embedded in the colored film layer 30 can be measured by direct observation from a cross section, for example. The method of cross-sectional observation is not particularly limited, but a coated metal plate is embedded in a room-temperature-drying epoxy resin perpendicular to the coating film thickness direction, and the embedded surface is mechanically polished and then observed with a SEM (scanning electron microscope). Or, using a FIB (focused ion beam) device, cut out a sample for observation with a thickness of 50 nm to 100 nm so that the vertical cross section of the coating film can be seen from the coated metal plate, and the coating film cross section is subjected to TEM (transmission electron A method of observing with a microscope, etc. can be used.

The coloring pigment contained in the colored film layer 30 is not particularly limited, and various known pigments can be appropriately used according to the desired color tone of the colored film layer 30 . Examples of such color pigments include aluminum pigments, carbon black, TiO ₂ and the like. Also, the content thereof may be appropriately set, and may be, for example, about 3 to 60% by mass.

The colored film layer 30 can be formed by applying a coating composition containing components constituting the colored film layer 30 as described above, baking the composition at a temperature of 150° C. or more and less than 300° C., and curing and drying the composition. It is possible. If the baking temperature is less than 150°C, the baking hardening may be insufficient and the corrosion resistance and scratch resistance of the coating film may decrease. heat deterioration of the steel may occur, and the workability may decrease.

The coating composition as described above can be applied by generally known coating methods such as roll coating, curtain flow coating, air spray, airless spray, immersion, bar coating, and brush coating.

In addition, the colored film layer 30 may contain additives such as antirust pigments, surface-modified metal powders and glass powders, dispersants, leveling agents, waxes, aggregates, etc. or a diluent solvent or the like can be further included.

Here, when a rust preventive pigment is contained, the content is preferably 1 to 15% by mass, for example. Moreover, the rust preventive pigment to be used is not particularly limited, and various known rust preventive pigments can be used.

<Regarding chemical conversion coating layer 40>
The chemical conversion treatment film layer 40 according to the present embodiment is a film layer that can be positioned between the plating layer 20 and the colored film layer 30, and removes impurities such as oil adhering to the surface of the plating layer 20 and surface oxides. , is a layer formed by chemical conversion treatment after removal by known degreasing and washing processes.

The detailed configuration of the chemical conversion coating layer 40 according to the present embodiment is not particularly limited, and resins, silane coupling agents, zirconium compounds, silica, phosphoric acid and salts thereof, fluorides, vanadium compounds, and , tannin or tannic acid. By containing these substances, it is possible to further improve the film-forming property after applying the chemical conversion treatment solution, the barrier property (denseness) of the film against corrosive factors such as moisture and corrosive ions, and the film adhesion to the plating surface. contributes to raising the corrosion resistance of the film.

In particular, when the chemical conversion coating layer 40 contains one or more of a silane coupling agent or a zirconium compound, a crosslinked structure is formed in the coating layer 40, and the bonding with the plating surface is also strengthened. It is possible to further improve the adhesion and barrier properties of the film.

In addition, when the chemical conversion treatment film layer 40 contains at least one of silica, phosphoric acid and its salts, fluoride, or vanadium compound, it functions as an inhibitor, and a precipitated film or passive film on the plating or steel surface. By forming, it is possible to further improve the corrosion resistance.

Below, the details of each component that can be included in the chemical conversion coating layer 40 as described above will be described with reference to examples.

[resin]
The resin is not particularly limited, and known organic resins such as polyester resins, polyurethane resins, epoxy resins, phenol resins, acrylic resins, and polyolefin resins can be used. Use at least one resin (polyester resin, urethane resin, epoxy resin, acrylic resin, etc.) that has a forced site or polar functional group in the molecular chain in order to further improve the adhesion to the plated steel sheet for pre-coated plated steel sheet. preferably. The resin may be used alone or in combination of two or more.

The content of the resin in the chemical conversion coating layer 40 is preferably 0% by mass or more and 85% by mass or less with respect to the solid content of the coating, for example. The resin content is more preferably 0% by mass or more and 60% by mass or less, and still more preferably 1% by mass or more and 40% by mass or less. If the resin content exceeds 85% by mass, the ratio of other film-constituting components decreases, and the performance required of the film other than corrosion resistance may decrease.

[Silane coupling agent]
Silane coupling agents include, for example, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane. , γ-(2-aminoethyl)aminopropylmethyldiethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ- methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltriethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropylmethyldiethoxy Silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane , γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropylmethyldiethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, γ-ani linopropylmethyldimethoxysilane, γ-anilinopropyltriethoxysilane, γ-anilinopropylmethyldiethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, octadecyldimethyl [3 -(trimethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(methyldimethoxysilyl)propyl]ammonium chloride, octade sildimethyl[3-(triethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(methyldiethoxysilyl)propyl]ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, Examples include dimethyldichlorosilane and trimethylchlorosilane. The addition amount of the silane coupling agent in the chemical conversion agent for forming the chemical conversion coating layer 40 can be, for example, 2 to 80 g/L. If the amount of the silane coupling agent added is less than 2 g/L, the adhesion to the plated surface may be insufficient, and the working adhesion of the coating film may decrease. Further, when the amount of the silane coupling agent added exceeds 80 g/L, the cohesive force of the chemical conversion film layer becomes insufficient, and the working adhesion of the coating film layer may decrease. The silane coupling agents as exemplified above may be used alone or in combination of two or more.

[Zirconium compound]
Examples of zirconium compounds include zirconium normal propylate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium monoethylacetoacetate, zirconium acetylacetonate bisethylacetoacetate, Zirconium acetate, zirconium monostearate, zirconium carbonate, zirconium ammonium carbonate, potassium zirconium carbonate, sodium zirconium carbonate and the like can be mentioned. The amount of the zirconium compound added in the chemical conversion treatment agent for forming the chemical conversion coating layer 40 can be, for example, 2 to 80 g/L. If the amount of the zirconium compound added is less than 2 g/L, the adhesion to the plated surface may be insufficient, and the working adhesion of the coating film may be reduced. Moreover, when the amount of the zirconium compound added exceeds 80 g/L, the cohesive force of the chemical conversion coating layer may be insufficient, and the processing adhesion of the coating layer may decrease. Such zirconium compounds may be used alone or in combination of two or more.

[silica]
Examples of silica include commercially available products such as "Snowtex N", "Snowtex C", "Snowtex UP", and "Snowtex PS" manufactured by Nissan Chemical Industries, Ltd., and "Adelite AT-20Q" manufactured by ADEKA Corporation. or powdered silica such as Aerosil #300 manufactured by Nippon Aerosil Co., Ltd. can be used. Silica can be appropriately selected according to the required performance of the precoated plated steel sheet. The amount of silica added in the chemical conversion agent for forming the chemical conversion coating layer 40 is preferably 1 to 40 g/L. If the amount of silica added is less than 1 g/L, the working adhesion of the coating layer may decrease. is likely to be saturated, so it is uneconomical.

[Phosphoric acid and its salts]
Examples of phosphoric acid and salts thereof include phosphoric acids such as orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid and tetraphosphoric acid and salts thereof, ammonium salts such as triammonium phosphate and diammonium hydrogen phosphate, Phosphonic acids such as aminotri(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid) and their salts, organic phosphoric acids such as phytic acid and salts thereof. Examples of salts of phosphoric acid other than ammonium salts include metal salts with Na, Mg, Al, K, Ca, Mn, Ni, Zn, Fe, and the like. Phosphoric acid and its salt may be used alone or in combination of two or more.

The content of phosphoric acid and its salt is preferably 0% by mass or more and 20% by mass or less with respect to the solid content of the film. When the content of phosphoric acid and its salt exceeds 20% by mass, the film becomes brittle, and the work followability of the film may deteriorate when the precoated plated steel sheet is formed. The content of phosphoric acid and its salt is more preferably 1% by mass or more and 10% by mass or less.

[Fluoride]
Examples of fluorides include ammonium zircon fluoride, ammonium silicofluoride, ammonium titanium fluoride, sodium fluoride, potassium fluoride, calcium fluoride, lithium fluoride, titanium hydrofluoric acid, and zircon hydrofluoric acid. . Such fluorides may be used alone or in combination of two or more.

The fluoride content is preferably 0% by mass or more and 20% by mass or less with respect to the solid content of the film. If the content of fluoride exceeds 20% by mass, the film becomes brittle, and the work followability of the film may deteriorate when the precoated plated steel sheet is formed. The content of fluoride is more preferably 1% by mass or more and 10% by mass or less.

[Vanadium compound]
Examples of vanadium compounds include vanadium pentoxide, metavanadic acid, ammonium metavanadate, sodium metavanadate, vanadium oxytrichloride, and other vanadium compounds obtained by reducing pentavalent vanadium compounds to divalent to tetravalent vanadium trioxide. , vanadium dioxide, vanadium oxysulfate, vanadium oxyoxalate, vanadium oxyacetylacetonate, vanadium acetylacetonate, vanadium trichloride, phosphovanadomolybdic acid, vanadium sulfate, vanadium dichloride, vanadium oxide, etc. A vanadium compound etc. can be mentioned. Such vanadium compounds may be used alone or in combination of two or more.

In addition, 0 mass % or more and 20 mass % or less of content of a vanadium compound is preferable with respect to film|membrane solid content. When the content of the vanadium compound exceeds 20% by mass, the film becomes brittle, and the work followability of the film may deteriorate when the precoated plated steel sheet is formed. The content of the vanadium compound is more preferably 1% by mass or more and 10% by mass or less.

[Tannin or tannic acid]
Both hydrolyzable tannin and condensed tannin can be used as tannin or tannic acid. Examples of tannins and tannic acids include hamameta tannins, quintuple tannins, gallic tannins, myrobalan tannins, divisibi tannins, algarovira tannins, valonia tannins, catechins, and the like. The amount of tannin or tannic acid added to the chemical conversion agent for forming the chemical conversion coating 40 can be 2 to 80 g/L. If the amount of tannin or tannic acid added is less than 2 g/L, the adhesion to the plated surface may be insufficient, and the working adhesion of the coating film may be reduced. If the amount of tannin or tannic acid added exceeds 80 g/L, the cohesive force of the chemical conversion film may be insufficient, and the processing adhesion of the coating film may be reduced.

Further, an acid, an alkali, or the like may be added to the chemical conversion treatment agent for forming the chemical conversion treatment film 40 for pH adjustment within a range that does not impair the performance.

A chemical conversion treatment agent containing various components as described above is applied on one side or both sides of the plating layer 20 and then dried to form the chemical conversion coating layer 40 . In the precoated plated steel sheet according to the present embodiment, it is preferable to form a chemical conversion coating layer 40 of 10 to 1000 mg/m ² per side on the plated layer 20 . The coating amount of the chemical conversion coating layer 40 is more preferably 20-800 mg/m ² , and most preferably 50-600 mg/m ² . Incidentally, the film thickness of the chemical conversion treatment film layer 40 corresponding to such an adhesion amount is approximately 0.01 to 1 μm although it depends on the components contained in the chemical conversion treatment agent.

As described above, the colored film layer 30 and the chemical conversion treatment film layer 40 according to the present embodiment have been described with reference to the coating compositions and chemical conversion treatment agents used to form the respective films. Generally, when these treatment agents and compositions are applied to plated steel sheets, these components are usually different from the component composition of the film formed. For example, with a chemical conversion treatment agent, the composition of the chemical conversion treatment agent and the chemical conversion film after application are different due to the reaction with the plated steel sheet, volatilization of volatile components in the chemical treatment agent, etc., and the formed chemical conversion treatment Determining the composition of the coating layer is usually technically difficult. In addition, it is also technically difficult to specify the composition of such a chemical conversion coating layer by instrumental analysis or the like. This also applies to the colored film layer. Therefore, in this embodiment, the colored film layer 30 and the chemical conversion treatment film layer 40 to be formed are specified by specifying the composition of the coating composition and the chemical conversion treatment agent.

Hereinafter, the precoat plated steel sheet according to the present invention will be specifically described while showing examples and comparative examples. The examples shown below are merely examples of the precoat plated steel sheet according to the present invention, and the precoat plated steel sheet according to the present invention is not limited to the following examples.

(1) Plated Steel Sheet Eleven types of metal sheets A1 to A11 shown in Table 1 below were prepared. A steel plate having a thickness of 0.7 mm was used as the base material of the plated metal plate. Furthermore, plated steel sheets were also prepared by subjecting these metal sheets to 60 mg/m ² of chromate-free chemical conversion treatment (CT-E300/manufactured by Nihon Parkerizing Co., Ltd.). The treatment liquid used for the chemical conversion treatment contains a silane coupling agent as its component, and the film layer formed by such chemical conversion treatment functions as a chemical conversion treatment film layer. The presence or absence of chemical conversion treatment is shown in Table 6 below.

(2) Preparation of colored paint A colored paint used for forming a colored film layer was prepared.
Resins shown in Table 2 below were prepared as binder resins. A melamine-based curing agent was added as a curing agent to each resin solution in an amount of 15% by mass in terms of solid content. Furthermore, the particles shown in Table 3 below were prepared and added at a predetermined particle size and in a predetermined amount shown in Table 6 below. As color pigments, aluminum pigment, titanium oxide, and carbon black (CB) shown in Table 4 below were prepared and added in predetermined amounts shown in Table 6 below. Further, as rust preventive pigments, compounds shown in Table 5 below were prepared and added in predetermined amounts shown in Table 6 below to prepare colored paints.

(3) Sample preparation The colored paint prepared as described above is applied to a plated steel sheet using a bar coater so that the dry film thickness becomes the film thickness shown in Table 6 below. A colored film layer was formed by heating so that the temperature (PMT) was 200°C.

(4) Sample Evaluation Each sample prepared by the above method was evaluated for performance based on the following criteria. The obtained evaluation results are also shown in Table 7 below.

<Appearance>
The appearance of the produced samples was evaluated according to the following criteria, and a score of 2 or more was regarded as acceptable, and a score of 1 was regarded as unacceptable.
Evaluation criteria 3: It has a uniform colored film appearance.
2: Appearance of colored film is slightly uneven.
1: The appearance of the colored film is uneven due to popping and the like.

<Scratch resistance>
The scratch resistance was evaluated by the following coin scratch test. A coin was brought into contact with the coated surface of the prepared sample while being inclined at an angle of 45 degrees, and the load was changed to 100 g, 500 g, and 1000 g to scratch. The flaws caused by each load were evaluated according to the following criteria, and samples with a score of 2 or higher for all loads were considered acceptable.
Evaluation Criteria 5: No peeling of coating film and change in glossiness are observed.
4: No peeling of the coating film was observed, but slight gloss change was observed.
3: Slight peeling of the coating film is observed, and gloss change is observed.
2: Peeling of the coating film is observed partially, and gloss change is observed.
1: The coating film is completely peeled off.

<Workability>
Workability was evaluated based on the following criteria. The prepared sample was bent 180° with the coated surface facing outward, and the outer side of the bent portion was evaluated according to the following evaluation criteria. The bending process was performed in an atmosphere of 20° C. with a 0.7 mm spacer interposed therebetween. A score of 2 or more was considered acceptable, and a score of 1 was considered unacceptable.
Evaluation criteria 5: No cracks are observed in the coating film.
4: Very slight cracks are observed in the coating film.
3: Slight cracks are observed in the coating film.
2: Cracks are observed in the coating film.
1: Significant cracks are observed in the entire coating film.

<Corrosion resistance>
As reference performance, corrosion resistance was evaluated based on the following criteria. After tape-sealing the end face of the test plate, a salt spray test (SST) in accordance with JIS Z 2371 was performed for 72 hours, and the state of rust generation was observed and evaluated according to the following evaluation criteria.
Evaluation Criteria 4: Less than 1% rusted area.
3: Rust generation area is 1% or more and less than 3% 2: Rust generation area is 3% or more and less than 5% 1: Rust generation area is 5% or more

As is clear from Table 7 above, the precoated steel sheets corresponding to the examples of the present invention have excellent appearance, scratch resistance and workability. On the other hand, it can be seen that the precoated steel sheets corresponding to the comparative examples of the present invention are inferior in performance in any of appearance, scratch resistance, and workability.

Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

1 pre-coated plated steel sheet 10 steel sheet 20 plating layer 30 colored film layer 40 chemical conversion treatment film layer 301 film-forming component 303 resin particles

Claims (12)

A plated steel plate having a plated layer on the surface of the steel plate;
A colored film layer located on the plating layer;
with
The plating layer has a Vickers hardness of 100 to 800 Hv,
The thickness of the colored film layer is 1 to 10 μm,
A precoated plated steel sheet, wherein the colored film layer contains a film-forming component having a glass transition point Tg of 30° C. or higher, and resin particles. The precoated plated steel sheet according to claim 1, wherein the content of the resin particles in the colored film layer is 5 to 50% by mass with respect to the total content of the film-forming component and the resin particles. The precoat plated steel sheet according to claim 1 or 2, wherein the resin particles have an average particle size of 1 to 15 µm. The precoated plated steel sheet according to any one of claims 1 to 3, wherein the colored film layer has a Vickers hardness of 10 to 70 Hv measured at an indentation depth of 3/4 of the thickness of the film from the surface layer. The precoated plated steel sheet according to any one of claims 1 to 4, wherein the colored film layer contains, as the film-forming component, the same resin as the resin that is the material of the resin particles. The precoat plated steel sheet according to any one of claims 1 to 5, wherein the resin particles are acrylic resin particles, and the film-forming component is an acrylic resin. The precoat plated steel sheet according to any one of claims 1 to 6, wherein the plated steel sheet is a zinc-based plated steel sheet. The plating layer contains Al: 4 to 22% by mass, Mg: 1 to 10% by mass, Si: 0.0001 to 2.0000% by mass, and the balance is Zn and impurities. The precoat plated steel sheet according to any one of 1 to 7. The precoat plated steel sheet according to claim 7 or 8, wherein the coating amount of the plating layer on both sides of the steel sheet is 30 to 600 g/m ² in total. The precoated plated steel sheet according to any one of claims 1 to 9, wherein the colored film layer contains at least one of an aluminum pigment, carbon black and TiO ₂ as a coloring pigment. The precoat plated steel sheet according to any one of claims 1 to 10, wherein the colored film layer further contains an antirust pigment. The precoated plated steel sheet according to any one of claims 1 to 11, further comprising a chemical conversion coating layer between the plating layer and the colored coating layer.

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