Painted metal sheet

Abstract

[Problem] To further improve designability and productivity of a coated metal plate. [Solution] The present invention relates to a coated metal plate having a metal plate, an organic resin film layer located on the surface of the metal plate, and organic resin particles dispersed in the organic resin film layer. The content of the organic resin particles in the organic resin film layer is 1.0-16.6 volume% per one surface with respect to the total solid content volume of the organic resin film layer. When the organic resin film layer is viewed in a plan view from above, the organic resin particles are dispersed in the organic resin film layer at a surface density of 30-120 particles / mm2. In a cross section obtained by cutting the organic resin film layer in the thickness direction at an arbitrary position, a relationship represented by formulas (1) to (4) is established.

Description

[Technical Field]

[0001] This invention relates to painted metal sheets. [Background technology]

[0002] Metal sheets with high aesthetic appeal are increasingly being used in applications such as home appliances, building materials, and automobiles. Examples of such metal sheets with high aesthetic appeal include metal sheets with colored organic coatings and metal sheets with highly glossy surfaces.

[0003] In metal sheets with such high aesthetic appeal as described above, the scratch resistance of the outermost surface of the metal sheet is crucial in order to maintain its excellent aesthetic appeal. Therefore, many proposals have been made to improve the scratch resistance of metal sheets with high aesthetic appeal.

[0004] For example, Patent Document 1 below proposes a technique for improving the scratch resistance of an organic coating in a zinc-plated steel sheet having an organic coating, by incorporating beads having a particle size larger than the thickness of the organic coating (hereinafter also referred to as "large particle size beads") into the organic coating. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2014 / 112544 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, when zinc-plated steel sheets having an organic coating containing large-diameter beads, as proposed in Patent Document 1, are wound into a coil or subjected to a predetermined press processing treatment, the large-diameter beads sometimes detach from the organic coating, reducing the aesthetic appeal of the organic coating. Furthermore, there is concern that the large-diameter beads detached from the organic coating may contaminate the various equipment used for winding into coils or press processing, hindering the process. For these reasons, when handling organic coatings containing large-diameter beads, sufficient care must be taken during handling, and there was room for further improvement from the perspective of increasing productivity.

[0007] Furthermore, when winding the material into a coil or applying a predetermined pressing process, even if the large-diameter beads do not fall off, they may deform due to the winding tension of the coil or the pressure during pressing. When such deformation occurs, the organic coating in the deformed area becomes relatively flat, resulting in a partial change in gloss and a decrease in the desired design aesthetic. This decrease in design aesthetic due to a change in gloss is also called a pressure mark. Thus, there was room for further improvement in organic coatings containing large-diameter beads, even from the perspective of maintaining design aesthetics.

[0008] Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to provide a painted metal sheet that has an organic resin coating layer containing particles with a particle size larger than the film thickness, while also being able to further improve design and productivity. [Means for solving the problem]

[0009] In order to solve the above problems, as a result of intensive studies by the present inventors, it was conceived that if the surface of particles having a particle size larger than the average film thickness contained in the organic resin film layer could be coated with an organic resin, it might be possible to prevent the particles from falling off or deforming. Based on such a concept, the present inventors carefully studied the coating conditions of a paint containing particles having a particle size larger than the average film thickness. As a result, the present inventors found that when the average particle size of the particles, the average film thickness of the organic resin film layer, the thickness of the organic resin coating the surface of the particles, etc. satisfy specific conditions, it is possible to prevent the particles from falling off or deforming from the organic resin film layer and further improve the design and productivity of the painted metal plate. Based on such findings, the gist of the present invention completed is as follows.

[0010] [1] A painted metal plate having a metal plate, an organic resin film layer located on the surface of the metal plate, and organic resin particles dispersed in the organic resin film layer, wherein the content of the particles in the organic resin film layer is 1.0 to 16.6% by volume per side with respect to the total solid volume of the organic resin film layer. When the organic resin film layer is viewed from above in a plan view, the organic resin particles are dispersed in the organic resin film layer at a surface density of 30 to 120 particles / mm 2 and a painted metal plate in which the relationships represented by the following formulas (1) to (4) are satisfied in a cross section obtained by cutting the organic resin film layer in the thickness direction at an arbitrary position. 10 ≦ T ≦ 40 ··· Formula (1) 50 ≦ φ ≦ 100 ··· Formula (2) 1.50 ≦ φ / T ≦ 10.00 ··· Formula (3) 15.00 ≦ φ / t ≦ 90.00 ··· Formula (4) Here, in the above formulas (1) to (4), T: The average film thickness of the organic resin film layer in the portion where the organic resin particles do not exist in the cross section, φ: The average particle size of the organic resin particles, t: In the cross-section, the average thickness of the particle-coated portion is the portion where the organic resin particles protrude from the surface of the organic resin coating layer in the area where the organic resin particles are absent, and the portion where the organic resin coating layer covers the organic resin coating layer. The units of T, φ, and t are μm. [2] The organic resin coating layer is located on both surfaces of the metal plate, and the organic resin particles are present only in the organic resin coating layer located on one surface of the metal plate, and on both surfaces of the metal plate of The painted metal plate according to [1], wherein the following relationships expressed by formulas (5) and (6) hold true for the two organic resin coating layers located on the surface. 3 ≤ GA ≤ 30 ··· Equation (5) 0.7 ≤ GA / GB ≤ 1.3 ··· Equation (6) Here, in equations (5) and (6) above, GA: The 60-degree specular gloss level G on the surface of the organic resin coating layer containing the organic resin particles, as defined in JIS Z 8741:1997. S (60°) GB: The 60-degree specular gloss G of the surface of the organic resin coating layer that does not contain the organic resin particles, as defined in JIS Z 8741:1997. S (60°) That is the case. [3] The painted metal plate according to [1] or [2], wherein T and t satisfy the relationship expressed by the following formula (7). 5.0 ≦ T / t ≦ 60.0 ··· Formula (7) [4] The painted metal plate according to [1] or [2], wherein the binder resin contained in the organic resin film layer and the organic resin particles satisfy the relationship represented by the following formulas (8) to (10). EA ≤ EB ··· Equation (8) 60 ≦ EA ≦ 150 ··· Formula (9) 60 ≦ EB ≦ 250 ··· Formula (10) Here, in equations (8) to (10) above, EA: Compression modulus of the binder resin contained in the organic resin film layer at 25°C EB: Compression modulus of the organic resin particles at 25°C The units of EA and EB are MPa. [5] The painted metal plate according to [1] or [2], wherein the organic resin particles are resin particles made of urethane resin, and the glass transition temperature Tg of the urethane resin is in the range of -40 to 40°C. [6] The painted metal plate according to [1] or [2], wherein the organic resin particles are resin particles made of acrylic resin, and the glass transition temperature Tg of the acrylic resin is in the range of 40 to 160°C. [ 7 The painted metal sheet according to [1] or [2], wherein the metal sheet is a zinc-plated steel sheet in which a zinc-plated layer, which is a plating layer containing at least zinc, is located on the surface of the base steel sheet. [ 8 Between the organic resin coating layer and the zinc-based plating layer, there is further a rust-preventive coating layer containing a rust-preventive pigment and a resin. 7 Painted metal sheet as described in [ ]. [ 9 The rust-preventive pigment is a pigment containing at least one of the elements P, V, Si, and Mg. 8 Painted metal sheet as described in [ ]. [ 10 The painted metal sheet according to [1] or [2], wherein the organic resin film layer further contains a coloring agent. [Effects of the Invention]

[0011] As described above, the present invention makes it possible to prevent particle detachment and deformation from the organic resin coating layer, thereby further improving the design and productivity of painted metal sheets. [Brief explanation of the drawing]

[0012] [Figure 1A] A schematic diagram illustrating an example of the structure of a painted metal plate according to an embodiment of the present invention. [Figure 1B]This is a schematic diagram illustrating an example of the structure of a painted metal plate according to the same embodiment. [Figure 1C] This is a schematic diagram illustrating an example of the structure of a painted metal plate according to the same embodiment. [Figure 1D] This is a schematic diagram illustrating an example of the structure of a painted metal plate according to the same embodiment. [Figure 2] This is a schematic diagram illustrating the organic resin coating layer in a painted metal sheet according to the same embodiment. [Figure 3] This is a schematic diagram illustrating the organic resin coating layer in a painted metal sheet according to the same embodiment. [Figure 4] This is a schematic diagram illustrating the organic resin coating layer in a painted metal sheet according to the same embodiment. [Modes for carrying out the invention]

[0013] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0014] (Regarding painted metal sheets) <Structure of painted metal sheet> In the following, the structure of a painted metal plate according to an embodiment of the present invention will be described with reference to Figures 1A to 1D. Figures 1A to 1D are schematic diagrams illustrating an example of the structure of a painted metal plate according to this embodiment. Here, in this embodiment, a painted metal plate means a metal plate having a coating on its surface. In this embodiment, the painted metal plate does not necessarily have to contain colorants such as various dyes and pigments in the coating.

[0015] As schematically shown in Figure 1A, the painted metal plate 1 according to this embodiment comprises a base metal plate 10 and an organic resin coating layer 20 located on one surface of the metal plate 10. Furthermore, the organic resin coating layer 20 according to this embodiment contains organic resin particles 201 in a dispersed state.

[0016] As schematically shown in Figure 1B, in the painted metal plate 1 according to this embodiment, one surface of the base metal plate 10 is provided with an organic resin coating layer 20 containing organic resin particles 201, and the other surface of the metal plate 10 may be provided with an organic resin coating layer 25 that does not contain organic resin particles 201.

[0017] As schematically shown in Figure 1C, in the painted metal plate 1 according to this embodiment, an organic resin coating layer 20 containing organic resin particles 201 may be provided on both surfaces of the base metal plate 10.

[0018] Furthermore, in the painted metal plate 1 according to this embodiment, as schematically shown in Figure 1D, a rust-preventive coating layer 30 containing rust-preventive pigment and resin may be further provided between the metal plate 10 and the organic resin coating layer 20, if necessary.

[0019] In addition, Figure 1D illustrates a case in which a rust-preventive coating layer 30 is provided on a painted metal plate 1 having the structure shown in Figure 1A. However, in a painted metal plate 1 having a structure as shown in Figures 1B and 1C, the rust-preventive coating layer 30 may be further provided at least between the metal plate 10 and the organic resin coating layer 20, or between the metal plate 10 and the organic resin coating layer 25.

[0020] The following sections will provide a detailed explanation of each component of the painted metal plate 1, as shown in Figures 1A to 1D.

[0021] [Regarding the metal plate 10] In the painted metal sheet 1 according to this embodiment, various metal sheets can be used as the base metal sheet 10. Examples of materials for such metal sheets include iron, iron-based alloys, aluminum, aluminum-based alloys, copper, copper-based alloys, titanium, and the like. It is also possible to use plated metal sheets, which are metal sheets that have been plated, as the metal sheet 10.

[0022] Furthermore, when using a steel sheet as the metal sheet 10, various types of steel sheets can be used, such as Al-killed steel, ultra-low carbon steel containing Ti, Nb, etc., and high-strength steel in which reinforcing elements such as P, Si, Mn are further added to ultra-low carbon steel.

[0023] Among the various metal sheets described above, it is preferable to use a zinc-plated steel sheet as the metal sheet 10 in this embodiment, which has various zinc-based plating layers containing at least zinc provided on the surface of a steel sheet as a base material. Examples of zinc-plated steel sheets include zinc-plated steel sheets, zinc-nickel plated steel sheets, zinc-iron plated steel sheets, zinc-chromium plated steel sheets, zinc-aluminum plated steel sheets, zinc-titanium plated steel sheets, zinc-magnesium plated steel sheets, zinc-manganese plated steel sheets, zinc-aluminum-magnesium plated steel sheets, and zinc-aluminum-magnesium-silicon plated steel sheets. Furthermore, as a zinc-plated steel sheet, it is also possible to use one in which a small amount of dissimilar metal elements or impurities such as cobalt, molybdenum, tungsten, nickel, titanium, chromium, aluminum, manganese, iron, magnesium, lead, bismuth, antimony, tin, copper, cadmium, arsenic, etc. are dispersed in the plating, or an inorganic substance such as silica, alumina, titania is dispersed. Furthermore, as zinc-plated steel sheets, steel sheets having a multi-layer plating combining the above-mentioned plating with other types of plating (for example, iron plating, iron-phosphorus plating, nickel plating, cobalt plating, etc.) may be used. The plating method is not particularly limited, and various known plating methods such as electroplating, hot-dip plating, vapor deposition, dispersion plating, and vacuum plating may be used.

[0024] Among such zinc-based platings, it is particularly preferable to use zinc-aluminum-magnesium alloy plating, and more preferably to use zinc-aluminum-magnesium-silicon alloy plating containing Al: 4-22% by mass, Mg: 1-10% by mass, Si: 0.0001-2.0000% by mass, with the remainder being Zn and impurities.

[0025] [Al:4~22% by mass] By setting the Al content to 4% by mass or more, it is possible to further improve the corrosion resistance of the steel sheet. The Al content is more preferably 5% by mass or more. On the other hand, by setting the Al content to 22% by mass or less, it is possible to further improve the corrosion resistance of the steel sheet while suppressing the saturation of the corrosion resistance improvement effect described above. The Al content is more preferably 16% by mass or less.

[0026] [Mg:1~10% by mass] By increasing the Mg content to 1% by mass or more, the corrosion resistance of the steel sheet can be further improved. More preferably, the Mg content is 2% by mass or more. On the other hand, by adjusting the Mg concentration in the plating bath used to form the plating layer so that the Mg content in the zinc-based plating layer after production is 10% by mass or less, it is possible to stabilize the generation of dross in the plating bath and stably manufacture plated steel sheets. It is even more preferable to adjust the Mg concentration in the plating bath used to form the zinc-based plating layer so that the Mg content in the zinc-based plating layer after production is 5% by mass or less.

[0027] [Si:0.0001~2.0000% by mass] By setting the Si content to 0.0001% by mass or more, it is possible to further improve the adhesion of the zinc-based plating layer (more specifically, the adhesion between the base steel sheet and the zinc-based plating layer). On the other hand, by setting the Si content to 2.0000% by mass or less, it is possible to further improve the adhesion of the zinc-based plating layer while suppressing the saturation of the adhesion-improving effect of the zinc-based plating layer. The Si content is more preferably 1.6000% by mass or less.

[0028] Furthermore, in the zinc-based plating layer according to the present embodiment, a part of the remaining Zn may be replaced by one or more of elements such as Fe, Sb, and Pb in a total amount of 1% by mass or less.

[0029] Examples of the zinc-based plated steel sheet provided with the zinc-based plating layer having the above chemical components include hot-dip zinc-aluminum-magnesium alloy plated steel sheets having a Zn-6%Al-3%Mg alloy plating layer, and plated steel sheets having a Zn-11%Al-3%Mg-0.2%Si alloy plating layer, such as hot-dip zinc-aluminum-magnesium-silicon alloy plated steel sheets (e.g., "Super Dyma (registered trademark)" manufactured by Nippon Steel Corporation).

[0030] Note that the total plating adhesion amount of the zinc-based plating layer on both sides of the steel sheet is 30 g / m 2 or more (that is, 15 g / m 2 or more per side). It is preferable that the adhesion amount is 30 g / m 2 or more. By setting the adhesion amount to 30 g / m 2 or more, it becomes possible to surely ensure the corrosion resistance of the zinc-based plated steel sheet. The plating adhesion amount is more preferably 40 g / m 2 or more in total on both sides of the steel sheet. On the other hand, the total plating adhesion amount is preferably 600 g / m 2 or less (that is, 300 g / m 2 or less per side). By setting the adhesion amount to 600 g / m 2 or less, it becomes possible to further improve the corrosion resistance while ensuring the smoothness of the surface of the zinc-based plating layer. The plating adhesion amount is more preferably 550 g / m 2 or less in total on both sides of the steel sheet.

[0031] When various plated metal sheets are used as the metal sheet 10, if a rust preventive coating layer 30 is further provided on the surface of such a metal sheet 10, such a rust preventive coating layer 30 will be located on the surface of various plating layers provided on the plated metal sheet.

[0032] Here, the thickness of the metal plate 10 as described above is not particularly limited and can be set appropriately according to the mechanical strength (e.g., tensile strength, etc.) and workability required for the painted metal plate 1 according to this embodiment.

[0033] [Regarding the organic resin coating layer 20] Next, the organic resin coating layer 20 of the painted metal plate 1 according to this embodiment will be described. The organic resin coating layer 20 according to this embodiment is a coating layer in which organic resin particles 201 exist dispersed in a binder resin 203 as a film-forming component, as illustrated in Figures 1A to 1D. In addition, the organic resin coating layer 20 according to this embodiment may also contain various additives such as crosslinking agents and colorants, in addition to the organic resin particles 201 and binder resin 203.

[0034] In the painted metal sheet 1 according to this embodiment, organic resin particles 201 are dispersed in the binder resin 203 within the organic resin film layer 20, and in addition, these organic resin particles 201 satisfy the conditions detailed below. As a result, in the painted metal sheet 1 according to this embodiment, the binder resin 203 achieves predetermined corrosion resistance and scratch resistance, and the painted metal sheet 1 as a whole achieves excellent design that combines a textured appearance and a matte appearance. Furthermore, in the painted metal sheet 1 according to this embodiment, it is possible to prevent the occurrence of pressure marks caused by the organic film becoming relatively flat in deformed areas.

[0035] ≪About Organic Resin Particles 201≫ In the organic resin coating layer 20 according to this embodiment, it is more preferable that the organic resin particles 201 have predetermined toughness and ductility. Having predetermined toughness and ductility allows the organic resin coating layer 20 to mitigate impacts. As a result, the scratch resistance of the organic resin coating layer 20 can be further improved in the painted metal plate 1 according to this embodiment. Furthermore, having predetermined toughness and ductility of the organic resin particles 201 makes it possible to better prevent the occurrence of pressure marks caused by the organic coating becoming relatively flat in deformed areas. Moreover, even if the organic resin coating layer 20 is scratched, it is possible to prevent the scratch from reaching the metal plate 10, thus maintaining the corrosion resistance of the painted metal plate 1.

[0036] In the organic resin coating layer 20 according to this embodiment, the organic resin particles 201 can be made of various materials, as long as they have predetermined toughness and ductility. However, from the viewpoint of having superior toughness and ductility, organic resin particles made of organic resin are used rather than inorganic particles made of inorganic compounds such as silica and ceramics. The organic resin of the present invention refers to a resin including synthetic resins or natural resins, and may contain a small amount of inorganic additives.

[0037] Examples of organic resin particles 201 include acrylic resin particles, polyester resin particles, urethane resin particles, fluororesin resin particles, silicone resin particles, and polyolefin resin particles. Among these, it is more preferable to use urethane resin particles or acrylic resin particles as the organic resin particles 201, as this allows for easier achievement of desired toughness and ductility.

[0038] Furthermore, when using urethane-based resin particles or acrylic-based resin particles as the organic resin particles 201, it is preferable that the resin constituting these resin particles exhibits a predetermined glass transition temperature Tg.

[0039] More specifically, when urethane resin particles are used as the organic resin particles 201, the glass transition temperature Tg of the urethane resin is preferably in the range of -40°C to 40°C. Furthermore, when acrylic resin particles are used as the organic resin particles 201, the glass transition temperature Tg of the acrylic resin is preferably in the range of 40°C to 160°C.

[0040] The constituent resin of the organic resin particles 201 has the glass transition temperature Tg described above, which allows the organic resin particles 201 to exhibit even more desirable toughness and ductility. As a result, even if the particles 201 are deformed by an external force, they can quickly restore to their shape before the impact. This makes it possible to further prevent the occurrence of pressure marks caused by the organic coating becoming relatively flat in the deformed area.

[0041] Furthermore, by using acrylic resin particles having the above-mentioned glass transition temperature Tg as the organic resin particles 201, it becomes possible to prevent the occurrence of pressure marks at an even lower cost compared to using urethane resin particles having the above-mentioned glass transition temperature Tg.

[0042] However, when using acrylic resin particles having the above-mentioned glass transition temperature Tg as the organic resin particles 201, it is preferable that, in addition to the above-mentioned glass transition temperature Tg, the acrylic resin particles satisfy predetermined conditions regarding their shape. The conditions regarding the shape of such acrylic resin particles will be explained in detail below.

[0043] When urethane resin particles are used as organic resin particles 201, the glass transition temperature Tg of the urethane resin is more preferably in the range of -10 to 20°C. Furthermore, when acrylic resin particles are used as particles 201, the glass transition temperature Tg of the acrylic resin is more preferably in the range of 60 to 120°C.

[0044] Furthermore, the glass transition temperature Tg can be determined by thermomechanical analysis (TMA), which involves inserting a needle into the surface of the organic resin particle being measured, subjecting it to a constant temperature change, and measuring the change in thermal expansion of the object.

[0045] In the painted metal sheet 1 according to this embodiment, the content of organic resin particles 201 in the organic resin film layer 20 is 1.0 to 16.6 volume% per side relative to the total solid content volume of the organic resin film layer 20. If the content of organic resin particles 201 in the organic resin film layer 20 is less than 1.0 volume% per side, the content of organic resin particles 201 is too low, and the desired design properties, which combine a textured appearance and a matte appearance, cannot be achieved. By having a content of organic resin particles 201 in the organic resin film layer 20 of 1.0 volume% or more per side, it becomes possible to achieve the desired design properties for the painted metal sheet 1. The content of organic resin particles 201 per side in the organic resin film layer 20 is preferably 2.2 volume% or more, and more preferably 3.4 volume% or more.

[0046] On the other hand, if the content of organic resin particles 201 in the organic resin coating layer 20 exceeds 16.6 volume% per side, the content of organic resin particles 201 becomes too high, making it impossible to achieve the required scratch resistance for the organic resin coating layer 20. By setting the content of organic resin particles 201 in the organic resin coating layer 20 to 16.6 volume% or less per side, it becomes possible to achieve the desired design while ensuring the required scratch resistance for the organic resin coating layer 20. The content of organic resin particles 201 per side in the organic resin coating layer 20 is preferably 13.3 volume% or less, and more preferably 10.0 volume% or less.

[0047] Here, the method for determining the content of organic resin particles 201 in the organic resin film layer 20 of the painted metal sheet 1 according to this embodiment, based on the state of the painted metal sheet that has already been manufactured, will be explained again below.

[0048] Furthermore, the organic resin particles 201 may contain multiple types of organic resin particles with different average particle sizes. Also, the organic resin particles 201 may possess functions as various additives that can be added to the organic resin film layer 20, such as colorants or rust inhibitors.

[0049] ≪About Binder Resin 203≫ Furthermore, the binder resin 203, which is a film-forming component contained in the organic resin film layer 20 according to this embodiment, can be any material as long as it functions as a binder for the organic resin particles 201. However, from the viewpoint of ease of manufacture and cost-effectiveness, as well as corrosion resistance and scratch resistance, it is preferable to use various organic resins as the binder resin 203. Examples of such binder resins 203 include acrylic resins, polyester resins, urethane resins, fluororesins, and the like.

[0050] Furthermore, in the organic resin coating layer 20 according to this embodiment, it is more preferable to select a resin of the same type as the organic resin particles 201 as the binder resin 203. This further improves the affinity between the organic resin particles 201 and the binder resin 203, thereby improving the adhesion and barrier properties of the organic resin coating layer 20.

[0051] <Regarding the state of existence of organic resin particles 201 in the organic resin coating layer 20> Next, with reference to Figure 2, the state of existence of organic resin particles 201 in the organic resin coating layer 20 will be described in detail. Figure 2 is a schematic diagram illustrating the organic resin particles 201 present in the organic resin coating layer of the painted metal plate according to this embodiment.

[0052] As previously mentioned, in the painted metal plate 1 according to this embodiment, organic resin particles 201 are dispersed in the organic resin film layer 20, covered with a film-forming component such as a binder resin 203. In discussing the state of existence of these organic resin particles 201, we will focus below on the cross-section obtained by cutting the organic resin film layer 20 according to this embodiment at an arbitrary position in the thickness direction, as schematically shown in Figure 2.

[0053] In the painted metal plate 1 according to this embodiment, when the cross-section obtained as described above is observed with an electron microscope (more specifically, with a field emission scanning electron microscope (FE-SEM)), the following relationships shown in equations (101) to (104) hold between the average particle size of the organic resin particles 201 and the average film thickness of the organic resin coating layer 20.

[0054] 10 ≦ T ≦ 40 ··· Formula (101) 50 ≦ φ ≦ 100 ··· Formula (102) 1.50 ≦ φ / T ≦ 10.00 ··· Formula (103) 15.00 ≦ φ / t ≦ 90.00 ··· Formula (104)

[0055] Here, in equations (101) to (104) above, T: Average thickness of the organic resin coating layer 20 in the portion of the cross-section where organic resin particles 201 are absent. φ: Average particle size of organic resin particles 201, t: In the cross-section, the average thickness of the "particle-coated portion," which is the portion of the organic resin particles 201 that protrudes from the surface of the organic resin coating layer 20 in areas where organic resin particles 201 are not present, is the portion covered by the organic resin coating layer 20. Furthermore, the units of T, φ, and t mentioned above are μm, respectively.

[0056] Furthermore, when examining the average film thickness T, average particle size φ, and average film thickness t of the particle coating portion of the organic resin film layer 20 as described above, the field of view of any size of 100 × 100 μm in the cross-section of interest will be observed using FE-SEM. If particles with a particle size that do not fit within the 100 × 100 μm field of view are observed, the observation field of view will be appropriately enlarged so that the particles fit within the field of view, and the particle size, film thickness of the organic resin film layer, and film thickness of the particle coating portion will be measured.

[0057] ◇Average particle size φ of organic resin particles 201 If the average particle size φ of the organic resin particles 201 is less than 50 μm, the average particle size of the organic resin particles 201 is too small, and the desired scratch resistance cannot be achieved. By making the average particle size φ of the organic resin particles 201 50 μm or more, the scratch resistance required for the coated metal plate 1 according to this embodiment can be achieved. The average particle size φ of the organic resin particles 201 is preferably 55 μm or more, and more preferably 60 μm or more.

[0058] On the other hand, if the average particle size φ of the organic resin particles 201 exceeds 100 μm, the average particle size of the organic resin particles 201 becomes too large, making them prone to detaching from the organic resin coating layer 20, and thus preventing the achievement of the desired design. By making the average particle size φ of the organic resin particles 201 100 μm or less, the detachment of the organic resin particles 201 from the organic resin coating layer 20 can be prevented, and the desired design can be achieved. The average particle size φ of the organic resin particles 201 is preferably 90 μm or less, and more preferably 85 μm or less.

[0059] The average particle size φ of the organic resin particles 201 in the cross-section described above is determined by the following procedure. First, the cross-section obtained by cutting the organic resin film layer 20 at an arbitrary position is observed and polished repeatedly. For each cross-section obtained by polishing, the average particle size φ of the particles 201, the average film thickness T of the organic resin film layer 20, and the various measurements used to calculate the average film thickness t of the particle-coated portion are measured and recorded using the procedure described below.

[0060] In determining the average particle size φ of particle 201, the cross-sectional area S of the particle 201 of interest in an arbitrary field of view in each cross-section is measured as a measurement value used to calculate the average particle size φ mentioned above.

[0061] Next, using the obtained cross-sectional areas S, the particle diameter (equivalent diameter of a circle) corresponding to each cross-sectional area is 2 × (S / π). 0.5 This can be calculated as follows. The cross-section in which the particle size of the organic resin particles 201 present in a 100 μm × 100 μm field of view is maximized is identified from among the multiple cross-sections observed. The identified cross-section with the maximum particle size is selected as one of the cross-sections for determining the average particle size φ of the organic resin particles 201, the average film thickness T of the organic resin coating layer 20, and the average film thickness t of the particle coating portion.

[0062] In this embodiment, when two or more organic resin particles 201 are observed in a single field of view, the operation of finding the maximum particle size of one organic resin particle 201 of interest (for example, referred to as particle A) and the operation of finding the maximum particle size of a different organic resin particle 201 (for example, referred to as particle B) are performed separately and independently. The above measurement is performed for any 20 organic resin particles 201 of interest, and the average value of the obtained 20 measured values ​​is treated as the average particle size φ of the organic resin particles 201.

[0063] In the example shown in Figure 2, two organic resin particles 201 are present in the field of view, and from the measurements described above, φ1 and φ2 are obtained as the maximum particle diameters of the organic resin particles 201, respectively. In this case, the two values ​​φ1 and φ2 are used as measured particle diameters to calculate the average particle size φ of the organic resin particles 201.

[0064] When selecting a cross-section from among several cross-sections to determine the average particle size φ of the organic resin particles 201, the average film thickness T of the organic resin coating layer 20, and the average film thickness t of the particle coating portion, the following points should be noted: The equivalent diameter of a circle may not be maximized in the first cross-section observed. Therefore, the equivalent diameter of a circle is calculated by repeatedly performing a small amount of polishing and then calculating the equivalent diameter of a circle from the cross-sectional area. In this way, the point where the maximum value is obtained is searched for.

[0065] ◇Average film thickness T of the organic resin coating layer 20 in the area where organic resin particles 201 are not present in the cross-section If the average film thickness T of the organic resin coating layer 20 in the portion of the cross-section where organic resin particles 201 are absent is less than 10 μm, the thickness of the organic resin coating layer 20 is too thin, and the desired corrosion resistance cannot be achieved. The corrosion resistance required for the coated metal plate 1 according to this embodiment can be achieved when the average film thickness T is 10 μm or more. The average film thickness T is preferably 13 μm or more, more preferably more than 15 μm, and even more preferably 16 μm or more.

[0066] On the other hand, if the average film thickness T of the organic resin coating layer 20 in the portion of the cross-section where organic resin particles 201 are absent exceeds 40 μm, the thickness of the organic resin coating layer 20 is too thick, which reduces the adhesion of the organic resin coating layer 20 and is therefore undesirable. By making the average film thickness T 40 μm or less, the desired corrosion resistance can be achieved while ensuring the adhesion of the organic resin coating layer 20. The average film thickness T is preferably 35 μm or less, and more preferably 30 μm or less.

[0067] The average film thickness T of the organic resin coating layer 20 in the portion of the cross-section where organic resin particles 201 are absent is determined by the following procedure. First, the thickness of the organic resin coating layer 20 in the portion of the cross-section of interest where organic resin particles 201 are absent is measured at an arbitrary location. In this case, the thickness of the organic resin coating layer 20 in the portion where organic resin particles 201 are absent can be measured using the length measuring function implemented in the FE-SEM. Measurements are taken by changing the field of view five times, and the value obtained by averaging the five measured values ​​is taken as the average film thickness T of the organic resin coating layer 20 in the portion where organic resin particles 201 are absent.

[0068] Here, the cross-section used to calculate the average film thickness T as described above is the cross-section selected to determine the average particle size φ of the organic resin particles 201 as described above.

[0069] In the case of Figure 2, it is assumed that in one field of view of interest, measurement results for thickness T1, T2, and T3 are obtained at three locations where organic resin particles 201 are not present. In this case, the average thickness of the organic resin film layer 20 in the one field of view of interest is (1 / 3) × (T1 + T2 + T3). By performing such observations at any five fields of view and further averaging the multiple average values ​​obtained by the number of fields of view, the average film thickness T of the organic resin film layer 20 in the areas where particles 201 are not present can be obtained.

[0070] ◇Relationship between the average particle size φ of organic resin particles 201 and the average film thickness T of the organic resin coating layer 20 In the organic resin coating layer 20 according to this embodiment, the ratio (φ / T) obtained by dividing the average particle size φ of the organic resin particles 201 obtained as described above by the average film thickness T is 1.50 or more. If the ratio (φ / T) is less than 1.50, the thickness of the organic resin coating layer 20 is too thick compared to the average particle size φ of the organic resin particles 201, resulting in insufficient protrusion of the organic resin particles 201, and making it impossible to achieve the desired scratch resistance and design. By having a ratio (φ / T) of 1.50 or more, it is possible to achieve the desired design while achieving the scratch resistance required for the painted metal plate 1. The value of the ratio (φ / T) is preferably 1.80 or more, and more preferably 2.00 or more.

[0071] On the other hand, if the ratio (φ / T) value exceeds 10.00, the average particle size φ of the organic resin particles 201 is too large compared to the average film thickness T. As a result, the organic resin particles 201 are not stably held by the organic resin coating layer 20, and the organic resin particles 201 tend to fall off, making it impossible to achieve the desired design. The ratio (φ / T) value is preferably 7.00 or less, and more preferably 5.00 or less.

[0072] ◇Relationship between the average particle size φ of organic resin particles 201 and the average film thickness t of the particle coating portion As is clear from the fact that the ratio (φ / T) in equation (103) above is 1.50 or more, some organic resin particles 201 exist in a state of protrusion from the surface of the organic resin coating layer 20 in areas where organic resin particles 201 are not present. Even organic resin particles 201 in this state are covered with film-forming components such as the binder resin 203 in the organic resin coating layer 20, as schematically shown in Figure 2. Below, the relationship between the average particle size φ of the organic resin particles 201 and the average film thickness of the film-forming component covering the organic resin particles 201, as described above, will be explained with reference to Figure 2.

[0073] In the cross-section mentioned earlier, the portion of the organic resin particles 201 that protrudes from the surface of the organic resin coating layer 20 in areas where organic resin particles 201 are absent, and which is covered by the organic resin coating layer 20, will be referred to as the "particle-covered portion." In the example shown in Figure 2, the approximately semicircular portion located above the line segment L connecting the surface positions of the organic resin coating layer 20 in areas where organic resin particles 201 are absent is the "particle-covered portion."

[0074] In this embodiment, the average film thickness of the film-forming component covering the surface of the organic resin particles 201 in the particle-coated portion described above is denoted as t. The average film thickness t of such a particle-coated portion is determined by the following procedure.

[0075] First, the position of the center of gravity is determined for each organic resin particle 201 present in the field of view. Here, the position of the center of gravity can be determined by analyzing the image obtained by microscopic observation using known methods. Then, a line is virtually set that passes through the identified center of gravity and is parallel to the surface normal direction of the metal plate 10. Using this set line as a reference, auxiliary lines are virtually set in the +45° direction and the -45° direction. The film thickness of the film-forming component present on these auxiliary lines is measured using the length-measuring function implemented in the FE-SEM. Therefore, two measurement values ​​are obtained from a single organic resin particle 201 present in the field of view, as schematically shown in Figure 2.

[0076] As shown in Figure 2, assume that two organic resin particles 201 are present in one field of view. In this case, measurement values ​​t1 and t2 are obtained from the organic resin particle 201 located on the left side of the figure, and measurement values ​​t3 and t4 are obtained from the organic resin particle 201 located on the right side of the figure. The average of the measurements obtained in this way (in the case of Figure 2, (1 / 4) × (t1 + t2 + t3 + t4)) is taken as the average thickness of the particle coating portion in the field of view of interest.

[0077] The above measurements are performed at 20 arbitrary fields of view in the cross-section of interest, and the average thickness of the particle coating in each field of view is calculated. Then, the multiple average values ​​obtained are further averaged by the number of fields of view, and the resulting value is taken as the average thickness t of the particle coating.

[0078] In the organic resin coating layer 20 according to this embodiment, the average film thickness t of the particle-coated portion obtained in this manner is greater than 0 μm. Furthermore, the larger the average film thickness t of the particle-coated portion, the more effectively the applied force can be dispersed when the coil winding tension or pressure during press processing is applied to the particle-coated portion. This makes it possible to more effectively suppress the occurrence of pressure marks and the like, thereby further improving the aesthetic appearance of the painted metal sheet 1.

[0079] The average film thickness t of the particle coating portion described above is preferably 0.6 μm or more, and more preferably 0.7 μm or more. Furthermore, the average film thickness t of the particle coating portion is preferably 5.0 μm or less, and more preferably 3.0 μm or less.

[0080] Furthermore, if the straight line passing through the center of gravity of the organic resin particles 201 and parallel to the surface normal direction of the metal plate 10 is used as the virtual auxiliary line described above, the film thickness of the film-forming component existing on such an auxiliary line (for example, the film-forming component existing on the angle bisector of the angle between the two virtual auxiliary lines set in the +45° and -45° directions in Figure 2) may be zero. However, in this embodiment, it is sufficient if the average film thickness t of the particle coating portion obtained by the method described above is greater than 0 μm.

[0081] In the organic resin coating layer 20 according to this embodiment, the ratio (φ / t) defined by the average film thickness t of the particle coating portion obtained as described above and the average particle size φ of the particles 201 is 15.00 or more. If the ratio (φ / t) is less than 15.00, the average film thickness t of the particle coating portion is too thick compared to the average particle size φ of the organic resin particles 201, resulting in insufficient protrusion of the organic resin particles 201, and making it impossible to achieve the desired scratch resistance and design. By setting the ratio (φ / t) to 15.00 or more, it becomes possible to achieve the desired design while also achieving the scratch resistance required for the painted metal plate 1. The value of the ratio (φ / t) is preferably 30.00 or more, and more preferably 50.00 or more.

[0082] On the other hand, if the ratio (φ / t) value exceeds 90.00, the average particle size φ of the organic resin particles 201 is too large compared to the average film thickness t. As a result, the particles 201 are not stably held by the film-forming component, and the organic resin particles 201 tend to fall off, making it impossible to achieve the desired design. The ratio (φ / t) value is preferably 85.00 or less, and more preferably 80.00 or less.

[0083] ◇Relationship between the average film thickness T of the organic resin coating layer 20 and the average film thickness t of the particle coating portion Furthermore, in the organic resin film layer 20 according to this embodiment, it is preferable that the average film thickness t of the particle-coated portion obtained as described above and the average film thickness T of the organic resin film layer 20 in the portion of the cross-section where organic resin particles 201 are not present satisfy the following relationship. More specifically, it is preferable that the ratio (T / t) of the average film thickness T of the organic resin film layer 20 to the average film thickness t of the particle-coated portion satisfies the relationship expressed by the following formula (105).

[0084] 5.0 ≦ T / t ≦ 60.0 ··· Formula (105)

[0085] By having a ratio (T / t) of 5.0 or higher, the organic resin coating layer 20 according to this embodiment can more stably retain the organic resin particles 201, thereby achieving superior scratch resistance and design properties. The ratio (T / t) is more preferably 8.0 or higher.

[0086] On the other hand, by setting the ratio (T / t) to 60.0 or less, it becomes possible to achieve better corrosion resistance while ensuring the adhesion of the organic resin coating layer 20. More preferably, the ratio (T / t) is 50.0 or less.

[0087] ◇Distribution state of organic resin particles 201 when the organic resin coating layer 20 is viewed from above in a plan view. Because the relationships expressed by equations (101) to (104) above hold true, in the painted metal sheet 1 according to this embodiment, the particles 201 are covered by the film-forming components of the organic resin film layer 20, yet a distribution state is achieved in which the degree of particle protrusion can be recognized at the locations where the organic resin particles 201 exist. As a result, the painted metal sheet 1 according to this embodiment achieves a distinctive appearance due to the shape of the organic resin particles 201, exhibiting high design quality.

[0088] Here, the distribution of organic resin particles 201 when the organic resin coating layer 20 is viewed from above in a plan view will be explained with reference to Figure 3. Figure 3 is a schematic diagram illustrating the organic resin particles in the organic resin coating layer of the painted metal plate according to this embodiment.

[0089] As schematically shown in Figure 3, we will focus on the organic resin coating layer 20 according to this embodiment when viewed from above in a plan view. As described above, although the organic resin particles 201 are covered by the film-forming component of the organic resin coating layer 20, the location of the organic resin particles 201 can be determined when viewed from above in a plan view. In Figure 3, the location of such organic resin particles 201 is indicated by a dashed line.

[0090] In the painted metal plate 1 according to this embodiment, as illustrated in Figure 3, when the organic resin film layer 20 is viewed from above in a plan view, the organic resin particles 201 are present in the organic resin film layer 20 at a density of 30 to 120 particles / mm². 2 It is dispersed with a surface density of [value].

[0091] Here, the surface density of the organic resin particles 201 is determined by observing the surface of the organic resin film layer 20 from above with an optical microscope. More specifically, using an optical microscope, the surface density is determined for any 1 mm 2 Observe a field of view of a certain size and count the number of organic resin particles 201 present in that field of view. In this case, if only a part of an organic resin particle 201 is present in the field of view, rather than the whole particle, the number is counted to one decimal place, for example, 0.1 to 0.9 particles, depending on the area ratio of the particle present in the field of view. If multiple organic resin particles 201 overlap in the thickness direction of the organic resin film layer 20, the entire overlapping organic resin particle 201 is counted as one particle. Perform this count for any five fields of view, and the average of the five counts obtained is taken as the surface density of the particles 201. When calculating the average value, if the obtained average value contains a decimal value, the decimal value is truncated.

[0092] In Figure 3, the shape of the field of view when counting particles is shown as a rectangle, but the shape of the field of view is not particularly limited. The shape of the field of view when counting particles may be, for example, a square, a polygon, a circle, or an ellipse.

[0093] The resulting surface density is 30 particles / mm². 2If the surface density is less than 30 particles / mm², the number of organic resin particles 201, which contribute to the high aesthetic appeal of the painted metal sheet 1, is too small, and the aesthetic appeal required for the painted metal sheet 1 cannot be achieved. Furthermore, in such cases, the degree of protrusion of the organic resin particles 201 becomes insufficient, making it difficult to achieve the scratch resistance required for the painted metal sheet 1. 2 As a result, it is possible to achieve the design and scratch resistance required for the painted metal sheet 1. The surface density of the organic resin particles 201 is preferably 35 particles / mm 2 The above is more preferable, 50 pieces / mm 2 That's all.

[0094] On the other hand, the surface density of the organic resin particles 201 is 120 particles / mm². 2 If the surface density is greater than 120 particles / mm², the probability of multiple organic resin particles 201 overlapping in the thickness direction increases, making the organic resin particles 201 more likely to fall off, which is undesirable. 2 The following conditions make it possible to achieve the desired aesthetic appeal and scratch resistance for the painted metal sheet 1 while suppressing the shedding of the organic resin particles 201. The surface density of the organic resin particles 201 is preferably 110 particles / mm². 2 The following, more preferably 100 pieces / mm 2 The following applies:

[0095] Using the surface density of the organic resin particles 201, the average particle size φ of the organic resin particles 201, and the average film thickness T of the organic resin coating layer 20 in the portion of the cross-section where the organic resin particles 201 are absent, as determined above, it is possible to determine the content of particles 201 in the organic resin coating layer 20 of the coated metal sheet 1 according to this embodiment from the state of the already manufactured coated metal sheet. The method is described below. First, assuming that the organic resin particles 201 are spheres, the average volume V of the particles is calculated using the following equation (a) with respect to the average particle size φ of the organic resin particles 201. Next, the average volume V of the particles is multiplied by the surface density of the organic resin particles 201 to obtain the volume per unit area (1 mm²). 2Next, calculate the volume of organic resin particles 201 per 1 mm. Then, calculate the average film thickness T in the area where organic resin particles 201 are not present and 1 mm. 2 Multiply by the unit area (1mm 2 First, determine the volume of the organic resin coating layer 20 per unit area. Then, calculate the volume percentage using the following formula (b). V = 4 / 3πφ 3 ...Formula (a) Volume % of organic resin particles 201 = 100 × surface density of 201 organic resin particles × V ÷ (T × 1 mm 2 )...Equation (b)

[0096] In this embodiment, the organic resin coating layer 20 may contain some organic resin particles 201 that are not completely covered by the organic resin coating layer 20 and whose parts are exposed from the organic resin coating layer 20. However, the less of these partially exposed organic resin particles 201 there are, the better. The amount of partially exposed organic resin particles 201 should be 20 particles / mm³ at the same surface density as described above. 2 The following is preferable: 0 pieces / mm 2 It is most preferable that this be the case.

[0097] ≪Regarding the compressive modulus of organic resin particles 201 and binder resin 203≫ Furthermore, in the organic resin film layer 20 according to this embodiment, it is more preferable that the organic resin particles 201 and binder resin 203 contained in the film layer satisfy all of the relationships represented by the following formulas (106) to (108).

[0098] EA ≤ EB ··· Equation (106) 60 ≦ EA ≦ 150 ··· Formula (107) 60 ≦ EB ≦ 250 ··· Formula (108)

[0099] Here, in equations (106) to (108) above, EA: Compression modulus of binder resin 203 contained in organic resin film layer 20 at 25°C EB: Compression modulus of organic resin particles 201 contained in organic resin film layer 20 at 25°C The units for EA and EB are MPa.

[0100] When the compressive moduli at 25°C of the organic resin particles 201 and the binder resin 203 satisfy all the relationships expressed by equations (106) to (108) above, the binder resin 203 can more easily follow the deformation of the organic resin particles 201 when an external force is applied to the particles and the particles deform (in other words, the binder resin 203 can more easily deform in accordance with the deformation of the organic resin particles 201). As a result, the formation of extra voids between the organic resin particles 201 and the binder resin 203 is prevented, and the adhesion and barrier properties of the organic resin coating layer 20 are further improved.

[0101] Here, the compressive modulus EA of the binder resin 203 at 25°C is more preferably 80 or higher. Furthermore, the compressive modulus EA of the binder resin 203 at 25°C is more preferably 130 or lower. On the other hand, the compressive modulus EB of the organic resin particles 201 at 25°C is more preferably 90 or higher. Furthermore, the compressive modulus EB of the organic resin particles 201 at 25°C is more preferably 210 or lower.

[0102] The compressive moduli EA and EB of the organic resin particles 201 and binder resin 203 at 25°C can be determined by focusing on the cross-section obtained by cutting the organic resin film layer 20 in the thickness direction according to this embodiment, and measuring the compressive stress-strain curves for the organic resin particles 201 and binder resin 203, respectively. More specifically, in accordance with JIS K 7181:2011, a nanoindenter is pressed into the area corresponding to the organic resin particles 201 and the area corresponding to the binder resin 203 in the cross-section of interest, and the load and displacement are measured. The measurement temperature is 25°C. Through such measurement, compressive stress-strain curves can be obtained for the organic resin particles 201 and binder resin 203, respectively. From the obtained compressive stress-strain curves, the compressive moduli of the organic resin particles 201 and binder resin 203 can be calculated in accordance with JIS K 7181:2011.

[0103] The above measurements should be performed at 10 locations for each of the organic resin particles 201 and the binder resin 203, and the average of the multiple compressive moduli obtained should be taken as the compressive moduli EB and EA of the organic resin particles 201 and binder resin 203 of interest.

[0104] Regarding the shape of organic resin particles when using acrylic resin particles: As mentioned above, acrylic resin particles may be used as the organic resin particles 201, and it is preferable that such acrylic resin particles satisfy the shape conditions described below. The preferred shape conditions for acrylic resin particles will be described below with reference to Figure 4. Figure 4 is a schematic diagram illustrating the organic resin particles in the organic resin film layer of the painted metal plate according to this embodiment.

[0105] The acrylic resin particles, which are an example of organic resin particles 201 present in the organic resin coating layer 20, preferably have a substantially circular cross-sectional shape as illustrated in Figure 2. However, at least a portion of the acrylic resin particles may have a substantially elliptical cross-sectional shape in a cross-section obtained by cutting the organic resin coating layer 20 in the thickness direction at an arbitrary position, as illustrated in Figure 4.

[0106] Furthermore, as illustrated in Figure 4, it is preferable that the resin particles made of acrylic resin having a substantially elliptical shape have a minor axis direction of the substantially elliptical shape that is substantially parallel to the thickness direction of the organic resin film layer 20, and a major axis direction of the substantially elliptical shape that is substantially parallel to the direction perpendicular to the thickness direction (in other words, substantially parallel to the surface of the metal plate 10).

[0107] Furthermore, when the average length of the minor axis of the approximately elliptical shape of the acrylic resin particles is denoted as Mφ (unit: μm), it is preferable that the relationship between this average length Mφ and the average film thickness T of the organic resin coating layer 20 in the area where the organic resin particles 201 are not present is satisfied by the following equation (109).

[0108] 1.5 ≦ Mφ / T ≦ 80.0 ··· Formula (109)

[0109] Even if the acrylic resin particles used as organic resin particles 201 have the glass transition temperature described above and a substantially elliptical cross-sectional shape, as long as the cross-sectional shape satisfies the relationship in equation (109) above, the portion where such substantially elliptical acrylic resin particles are present will not be visible as a pressure mark. Therefore, even if the acrylic resin particles are deformed by the winding tension of the coil or the pressure during press processing, the aesthetic appearance of the painted metal plate 1 according to this embodiment can be maintained.

[0110] Here, the average length Mφ of the minor axis of the approximately elliptical shape described above can be determined as follows. That is, in the cross-section used to determine the average particle size φ of the organic resin particles 201, the average film thickness T of the organic resin coating layer 20, and the average film thickness t of the particle coating portion, as explained earlier, the length of the minor axis of the approximately elliptical shape present in any field of view is measured. For example, if acrylic resin particles having an elliptical shape as shown in Figure 4 are present in the field of view, the length Mφ1 in the figure is measured using the length measuring function implemented in the FE-SEM. Such measurements are performed for all acrylic resin particles having an approximately elliptical shape present in the field of view, and the average value of the obtained measurements is calculated. Such measurements are performed for 20 fields of view in the cross-section, and the multiple average values ​​obtained are further averaged by the number of fields of view. The average value obtained in this way can be taken as the average length Mφ of the minor axis of the approximately elliptical shape.

[0111] The ratio (Mφ / T) is preferably 5.0 or higher, and more preferably 10.0 or higher. Furthermore, the ratio (Mφ / T) is preferably 70.0 or lower, and more preferably 60.0 or lower.

[0112] ≪Regarding other ingredients≫ The organic resin coating layer 20 according to this embodiment may, in addition to the organic resin particles 201 and binder resin 203 described above, optionally contain various additives such as crosslinking agents and colorants.

[0113] The above-mentioned colorants are not specifically defined, and various known colorants (i.e., various dyes and pigments) can be used depending on the desired color tone of the organic resin film layer 20. Examples of such colorants include aluminum pigment, titanium dioxide, zinc oxide, zirconium oxide, calcium carbonate, barium sulfate, kaolin clay, carbon black, iron oxide, Hansa yellow, pyrazolone orange, phthalocyanine, azo pigment carbon black, etc. The content can also be set appropriately, for example, to about 3 to 60% by mass.

[0114] Furthermore, the organic resin coating layer 20 according to this embodiment may, if necessary, contain rust-preventive pigments, extender pigments, surface-modified metal powders or glass powders, dispersants, leveling agents, waxes, aggregates, or diluting solvents, to the extent that the above effects are not impaired.

[0115] In this case, when the organic resin film layer 20 contains a rust-preventive pigment, the content is preferably, for example, about 1 to 15% by mass. Furthermore, various known rust-preventive pigments can be used.

[0116] The organic resin coating layer 20 of the painted metal plate 1 according to this embodiment has been described in detail above with reference to Figures 2 to 4.

[0117] [Regarding the organic resin coating layer 25] The organic resin film layer 25 that the painted metal plate 1 according to this embodiment may have has the same structure as the organic resin film layer 20 described above, except that it does not have the organic resin particles 201 described earlier. That is, such an organic resin film layer 25 has at least a binder resin 203 as a film-forming component, and may further have various additives. For this reason, a detailed explanation of the organic resin film layer 25 according to this embodiment will be omitted below.

[0118] [Regarding the rust-preventive coating layer 30] Next, a rust-preventive coating layer 30, which may be provided between the metal plate 10 and the organic resin coating layer 20 as needed in the painted metal plate 1 according to this embodiment, will be briefly described. This rust-preventive coating layer 30 is a coating layer containing a rust-preventive pigment and a resin.

[0119] Here, the resin contained in the rust-preventive coating layer 30 functions as a film-forming component, and any material can be used. However, from the viewpoint of ease of manufacture and cost-effectiveness, as well as corrosion resistance and scratch resistance, it is preferable to use various organic resins as such resins. Examples of such resins include acrylic resins, polyester resins, urethane resins, and fluororesins.

[0120] Furthermore, the rust-preventive coating layer 30 according to this embodiment may contain various known rust-preventive pigments as rust-preventive pigments. However, it is preferable that the rust-preventive coating layer 30 according to this embodiment contains a pigment containing at least one of the elements P, V, Si, and Mg as such rust-preventive pigment.

[0121] Examples of pigments containing at least one of the above elements P, V, Si, and Mg include zinc phosphate, zinc phosphite, magnesium zinc phosphate, magnesium phosphate, magnesium phosphite, silica, calcium ion exchange silica, zirconium phosphate, aluminum dihydrogen tripolyphosphate, zinc oxide, zinc phosphomolybdate, barium metaborate, strontium chromate, and the like.

[0122] The average thickness of the rust-preventive coating layer 30 is not particularly limited; for example, it can be approximately 3.0 to 12.0 μm.

[0123] <Regarding the glossiness of painted metal sheet 1> One of the characteristics of the painted metal plate 1 according to this embodiment that corresponds to its high design quality is its glossiness, which gives it a matte appearance. The glossiness will be described in detail below.

[0124] In the painted metal plate 1 according to this embodiment, the surface of the organic resin coating layer 20 containing organic resin particles 201 has a 60-degree specular gloss G as defined in JIS Z 8741:1997. S When measuring (60°), the specular gloss of that 60° G SThe (60°) value is preferably within the range of 3 to 30. In the painted metal sheet 1 according to this embodiment, if the surface of the organic resin film layer 20 exhibits a glossiness within the above range, the painted metal sheet 1 according to this embodiment will exhibit a superior matte appearance (and consequently, superior design). 60° specular glossiness G S The value of (60°) is more preferably 5 or greater. Also, the 60° specular gloss G S The value of (60°) is more preferably 25 or less.

[0125] Furthermore, if the painted metal plate 1 according to this embodiment has an organic resin film layer 20 containing organic resin particles 201 and an organic resin film layer 25 that does not contain organic resin particles 201, as shown in Figure 1B, it is preferable that the following relationships represented by formulas (110) and (111) hold true.

[0126] 3 ≤ GA ≤ 30 ··· Equation (110) 0.7 ≤ GA / GB ≤ 1.3 ··· Equation (111)

[0127] Here, in equations (110) and (111) above, GA: The 60-degree specular gloss level G as defined in JIS Z 8741:1997 on the surface of the organic resin coating layer 20 containing organic resin particles 201. S (60°) GB: The 60-degree specular gloss level G as defined in JIS Z 8741:1997 on the surface of the organic resin coating layer 25 that does not contain organic resin particles 201. S (60°) Furthermore, such a 60-degree specular gloss G S For measuring (60°), a gloss meter conforming to JIS Z 8741:1997 should be used.

[0128] Even if the painted metal plate 1 according to this embodiment has an organic resin coating layer 25 that does not contain organic resin particles 201, the gloss of the painted metal plate 1 satisfies both formulas (110) and (111), so that an excellent matte appearance is recognized regardless of which side of the coating layer the painted metal plate 1 is viewed from.

[0129] Here, the ratio (GA / GB) is more preferably 0.9 or higher. Furthermore, the ratio (GA / GB) is more preferably 1.1 or lower.

[0130] Furthermore, the 60-degree specular gloss level G S (60°) can be measured using various gloss meters in accordance with JIS Z 8741:1997.

[0131] The painted metal plate 1 according to this embodiment has been described in detail above with reference to Figures 1A to 4.

[0132] (Regarding the manufacturing method of painted metal sheets) Next, an example of a method for manufacturing a painted metal sheet according to this embodiment will be described. First, the base metal sheet is subjected to various pretreatments, including alkaline degreasing, water washing, and pickling, to create a clean metal sheet surface.

[0133] Subsequently, various known rust-preventive coatings are applied to the metal plate as needed to form a rust-preventive film layer, and then dried. Here, the application of the rust-preventive coating can be carried out by generally known application methods, such as roll coating, curtain flow coating, air spray, airless spray, dipping, bar coating, or brush application. Furthermore, there are no particular limitations on the heating method for the rust-preventive coating, and any method can be adopted, such as hot air, near-infrared radiation, far-infrared radiation, induction heating, or a combination thereof.

[0134] Next, an organic resin coating layer is formed by applying a paint to the surface of the metal plate on which a rust-preventive coating layer has been formed, and then heating and drying it. Here, the paint is prepared by including the above-mentioned binder resin and, if necessary, various additives in a solvent. Furthermore, the paint applied to at least one surface of the metal plate is made to contain the above-mentioned organic resin particles to form the organic resin coating layer 20.

[0135] Here, attention must be paid to the surface tension and viscosity of the paint used to form the organic resin film layer 20 as described above. More specifically, it is important that the surface tension of the paint be in the range of 28 to 32 mN / m, and the viscosity of the paint be in the range of 400 to 700 mPa·s.

[0136] Here, the surface tension and viscosity are measured as follows. The measurement temperature for surface tension and viscosity is 25°C. More specifically, the surface tension of the paint is measured using the platinum ring method with a DY-300 manufactured by Kyowa Interface Science Co., Ltd. The viscosity of the paint is determined by measuring the relationship between the shear rate and the viscosity of the paint using a rheometer (MCR702e) manufactured by Anton Paar. In this case, the shear rate is 1000 s. -1 The viscosity of the paint at that time is used. This is because the shear rate acting on the paint during curtain painting, as described later, is approximately 1000 s. -1 Therefore.

[0137] Furthermore, it is important to apply the prepared paint using a curtain flow coater. By applying paint containing particles using a curtain flow coater, it is possible to apply the paint without causing the particles to settle or paint defects (roping) to occur.

[0138] After applying the paint to the surface of the metal plate (or rust-preventive coating layer), the paint is heat-cured. The heating temperature can be set according to the solvent used, but it is preferable to set it in the range of 200 to 250°C. When heat-curing the paint, attention must be paid to the heating rate. More specifically, it is important that the heating rate to the boiling point of the solvent be in the range of 7 to 27°C / second. By applying the paint having the above-described surface tension and viscosity using a curtain flow coater and heat-curing it under the above-described heating rate, an organic resin coating layer 20 with the state of organic resin particles described above can be formed. The heating rate is more preferably in the range of 15 to 25°C / second.

[0139] Furthermore, there are no particular limitations on the method of heating the paint; any method can be used, such as hot air, near-infrared radiation, far-infrared radiation, induction heating, or a combination of these.

[0140] The method for manufacturing a painted metal sheet according to this embodiment has been described above. [Examples]

[0141] In the following, the painted metal sheet according to this embodiment will be described in detail with reference to examples and comparative examples. Note that the following examples are merely examples of painted metal sheets according to this embodiment, and the painted metal sheet according to this embodiment is not limited to the examples below.

[0142] <1. Preparation of varnish paint> Amorphous polyester resins manufactured by Toyobo Co., Ltd., namely "Byron® 500 (Tg 4℃)", "Byron® 270 (Tg 50℃)", and "Byron® UR-6100 (Tg -30℃)", were dissolved in an organic solvent (a mixture of cyclohexanone and Solvesso 150 (product name) in a mass ratio of 1:1). The mixing ratio of these polyester resins was then adjusted.

[0143] Next, melamine resin "Cymel® 303" manufactured by Ornex Japan Co., Ltd. and melamine resin "Super Beccamine®" manufactured by DIC Corporation were added to the above solution as curing agents. The amount of melamine resin added was such that the mass ratio of the solid content of the resins was 70:30 for polyester resin solids to melamine resin solids. In addition, 0.5% by mass of the acidic catalyst "Catalyst 600" manufactured by Ornex Japan Co., Ltd. was added to this mixed solution of polyester resin and melamine resin. A varnish coating was obtained by stirring this mixed solution. The polyester resin and melamine resin contained in this varnish coating mainly function as binder resins. The compressive modulus of the binder resin was adjusted by adjusting the ratio of the polyester resin and the melamine resin.

[0144] <2. Preparation of particle-containing paint> To the above varnish paint, particle-containing paint was prepared by dispersing either "Art Pearl (registered trademark)," a urethane resin manufactured by Negami Kogyo Co., Ltd., or "MBX," acrylic beads manufactured by Sekisui Chemical Co., Ltd., as organic resin particles. In addition, at some levels, carbon black "Toka Black #7300" manufactured by Tokai Carbon Co., Ltd. and titanium dioxide "R-820" manufactured by Ishihara Sangyo Co., Ltd. were added as colorants (indicated as "CB" in the "Colorant" column in Table 1 below). Here, the colorants were used in a mass ratio (carbon black:titanium dioxide) of 20:80. The amount of colorant added was adjusted so that the mass ratio (varnish solids:colorant) of the solids in the varnish was 92:8. In addition, at some levels, only titanium dioxide was added as a colorant (indicated as "TiO2" in the "Colorant" column in Table 1 below). Particle-containing paint was prepared by stirring this mixture.

[0145] <3. Preparation of the back coating> For the back surface coating, we used "FlexiCoat 100," a polyester / melamine paint manufactured by Nippon Paint Industrial Coatings Co., Ltd. This paint was colored beige using white and yellow pigments. The gloss level was adjusted by adding silica microparticles as a gloss modifier to the paint. The dry film thickness was 5 μm.

[0146] <4. Preparation of rust-preventive paint> Two amorphous polyester resins manufactured by Toyobo Co., Ltd., "Byron® 500 (Tg 4℃)" and "Byron® 270 (Tg 50℃)," were mixed in a mass ratio of 1:1. Next, these polyester resin mixtures were dissolved in an organic solvent (a mixture of cyclohexanone and Solvesso 150 (product name) in a mass ratio of 1:1) to prepare a primer varnish. To this primer varnish, the isocyanate "Coronate HX" manufactured by Tosoh Corporation was added. The amount of isocyanate added was such that the mass ratio of solids to isocyanate in the varnish was 95:5. Furthermore, as rust-preventive pigments, condensed aluminum "K-WHITE #450H" manufactured by Teika Co., Ltd., calcium-modified silica "SHIELDEX C303" manufactured by GRACE, calcium vanadate apatite (reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and magnesium hydroxide (reagent manufactured by Kanto Chemical Co., Ltd.) were used, respectively. Each component was added to achieve a concentration of 50% by mass in the dried film, and the mixture was stirred to prepare a rust-preventive coating.

[0147] <5. Preparation of test specimens> Next, various metal plates (all commercially available) were prepared as base metal plates. More specifically, the metal plates used were Zn-0.2 mass%Al plated steel plate (GI), Zn-11 mass%Al-3 mass%Mg-0.2 mass%Si plated steel plate (SD), stainless steel 304 (SUS), and aluminum A5052 (Al). The thickness of each metal plate was 0.6 mm.

[0148] To improve adhesion between the metal plate and the coating, a chemical conversion treatment film was formed on the surface of the metal plate prior to the application of the paint. The chemical conversion treatment film was made using chromate-free chemical conversion treatment liquid "CT-E300N" manufactured by Nippon Parkerizing Co., Ltd., with a drying adhesion amount of 100 mg / m². 2 The coating was applied under these conditions and dried at a metal plate temperature of 60°C to form a chemical conversion treatment film.

[0149] On one side of the metal plate described above, either the particle-containing paint alone or a two-layer coating of the rust-preventive paint and the particle-containing paint was applied, while the back surface paint was applied to the opposite side, and then heated and baked. A curtain flow coater was used to apply the paint. In this way, test specimens were prepared. Multiple such test specimens were prepared for each level. Details of the test specimens produced in this manner are shown in Table 1 below. Furthermore, the various properties of the particle-containing paint used (surface tension and viscosity at 25°C) and the conditions during heating and baking are shown in Table 2 below.

[0150] For each test material obtained, the average film thickness T, t, average particle diameter φ, and gloss (more specifically, the 60-degree specular gloss G) were determined according to the method described earlier. S (60°)GA, GB, particle content, surface density of organic resin particles, compressive modulus EA and EB at 25°C were measured. The results obtained are summarized in Table 1 below. In addition, the amount of partially exposed particles was checked for the test material corresponding to the example, and it was found that such an amount was within the acceptable upper limit (20 particles / mm²). 2 It was confirmed that it was less than ). The confirmation was made by repeatedly observing the resin-embedded sample and observing the cross-section while polishing it, until it was 1 mm. 2 The number of particles was observed over a considerable cross-sectional area.

[0151] [Table 1]

[0152] [Table 2]

[0153] Each test material obtained as described above was evaluated from the viewpoints of texture, workability, pressure marking, and corrosion resistance. The evaluation method is as follows.

[0154] (Textured appearance) In addition to the surface of the test material, a resin molded product (with a textured surface; the resin used was the exterior material of the Canon iR ADVC5250F multifunction printer) was also used. For both the test material and the resin molded product, visual observation from a distance of 30 cm and tactile sensation were evaluated to determine whether they could be distinguished from the test material. The evaluators were 20 randomly selected individuals with visual acuity of 1.0 or higher. The percentage of evaluators who could distinguish between the two was calculated as the distinguishability rate and used as the evaluation of the design quality. The evaluation criteria were as follows. A passing level was set at 3 or higher. <Evaluation Criteria> Score 5: Discrimination rate 0% 4: Discrimination rate greater than 0% and less than or equal to 10% 3: Discrimination rate is over 10% but 20% or less. 2: Discrimination rate is over 20% but 50% or less. 1: Discrimination rate exceeds 50%

[0155] (Processing adhesion) Cylindrical cup molding was performed with the surface of the test material facing outwards. A die with a diameter of φ50 mm was used. The shoulder radius of both the die and the punch was set to 5 mm. The drawing height was set to 50 mm, and the wrinkle-holding pressure was set to 1 ton. After processing, cellophane tape (Nichiban Co., Ltd.'s Cellotape® registered trademark, 24 mm wide) was applied to the cup body. Then, the cellophane tape was peeled off in a direction at a 45° angle to the surface normal direction of the test material. The percentage of paint adhesion area on the peeled cellophane tape was visually evaluated. The processing adhesion was evaluated according to the following evaluation criteria, and this was used for evaluation of the aesthetic appearance. A passing level was set at 3 or higher. <Evaluation Criteria> Rating 5: No paint peeling. 4: Coating peeling area ratio is less than 5% 3: The area ratio of paint film peeling is 5% or more, but less than 10%. 2: The area ratio of paint film peeling is 10% or more, but less than 30%. 1: The paint film peeling area ratio is 30% or more.

[0156] (Pressure marking) Two test specimens of the same quality were used. The surface of one specimen was placed on top of the back surface of the other specimen, and pressure was applied at 10 MPa. The test temperature was 50°C, and the test time was 10 minutes. After the test, the surface appearance was visually evaluated to determine the presence or absence of pressure marks. The pressure markability was evaluated according to the following evaluation criteria, and this was used for the evaluation of the aesthetic appearance. A passing level was 3 or higher. <Evaluation Criteria> Rating 5: Pressure marks are not visible when viewed from the front (normal to the surface of the test material) or from an oblique angle. 4: The pressure mark is not visible from the front, but it can be faintly seen when viewed from an angle. 3: The pressure mark is slightly visible when viewed from the front, and slightly visible when viewed from an angle. 2: When viewed from the front, the pressure mark is slightly visible, and when viewed from an angle, the pressure mark is clearly visible. 1: The pressure mark is clearly visible whether viewed from the front or from an angle.

[0157] (corrosion resistance) An X-shaped cut was formed on the surface of the test specimen using an NT cutter. The cut was made so that it reached the base metal plate. A salt spray test (SST) in accordance with JIS Z 2371:2015 was then performed for 240 hours. After the test, the test specimen was washed and dried, and the maximum blister width from the X-shaped cut was measured. Of the blisters that occurred on both sides of the cut, the maximum blister width on one side was measured. A 10x magnifying glass was used for observation. Corrosion resistance was evaluated according to the following criteria. A passing level was 3 or higher. <Evaluation Criteria> Rating 5: Maximum swelling width is less than 2mm 4: Maximum swelling width is 2mm or more but less than 3mm. 3: Maximum swelling width is 3mm or more but less than 5mm. 2: Maximum swelling width is 5mm or more, but less than 7mm. 1: Maximum swelling width is 7mm or more

[0158] The results obtained are summarized in Table 3 below.

[0159] [Table 3]

[0160] As is clear from Table 3 above, the test material corresponding to the embodiment of the present invention showed excellent textured appearance, workability, pressure mark resistance, and corrosion resistance, while the test material corresponding to the comparative example of the present invention failed in at least one of the following: textured appearance or workability.

[0161] Furthermore, in No. 26 and No. 27, which used stainless steel 304 (SUS) or aluminum A5052 (Al) as the metal plate, the metal plate fractured during the cylindrical cup forming process to evaluate "work adhesion," making it impossible to evaluate "work adhesion." Therefore, in Table 3 above, the "work adhesion" column for No. 26 and No. 27 is marked with "-".

[0162] In addition, the productivity of applying the No. 1 particle-containing paint shown in Table 1 above using a curtain flow coater and a roll coater commonly used in the manufacture of pre-coated steel sheets was compared. A two-roll coater consisting of a pickup roll and an applicator roll was used. The substrate speed was varied in 10 mpm increments between 10 mpm and 80 mpm.

[0163] In the case of the curtain flow coater, a beautiful appearance was obtained when the metal sheet speed was in the range of 50 to 80 mpm, and the performance was equivalent to that of No. 1 shown in Table 1 above. On the other hand, in the case of the roll coater, roping occurred when the sheet speed was in the range of 20 to 80 mpm, but at a sheet speed of 10 mpm, a beautiful appearance was obtained similar to that of the curtain flow coater. From these results, it can be said that painting with a curtain flow coater is 5 to 8 times more productive than using the roll coater, which is a general-purpose painting method.

[0164] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention.

[0165] The embodiments disclosed herein are illustrative and not restrictive in all respects. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the appended claims, the technical scope of the invention as described later, and the spirit thereof. For example, the constituent elements of the embodiments described above can be combined in any way without impairing their effects. Furthermore, such any combination will naturally yield the effects and benefits of each constituent element in the combination, as well as other effects and benefits that will be obvious to those skilled in the art from the description herein.

[0166] Furthermore, the effects described herein are merely descriptive or illustrative, and not limiting. In other words, the technology according to the present invention may produce other effects that will be apparent to those skilled in the art from the description herein, in addition to or instead of the effects described above.

[0167] Furthermore, the following configurations also fall within the technical scope of the present invention. [1] A painted metal plate comprising a metal plate, an organic resin coating layer located on the surface of the metal plate, and organic resin particles dispersed in the organic resin coating layer, The content of the organic resin particles in the organic resin film layer is 1.0 to 16.6% by volume per side, relative to the total solid content volume of the organic resin film layer. When the organic resin film layer is viewed from above in a plan view, the organic resin particles are present in the organic resin film layer at a density of 30 to 120 particles / mm². 2 It is dispersed with a surface density of, A painted metal sheet in which the following relationships expressed by equations (1) to (4) hold in a cross-section obtained by cutting the organic resin film layer at an arbitrary position in the thickness direction. 10 ≦ T ≦ 40 ··· Formula (1) 50 ≦ φ ≦ 100 ··· Formula (2) 1.50 ≦ φ / T ≦ 10.00 ··· Formula (3) 15.00 ≦ φ / t ≦ 90.00 ··· Formula (4) Here, in equations (1) to (4) above, T: Average thickness of the organic resin coating layer in the portion of the cross-section where the organic resin particles are absent. φ: Average particle size of the organic resin particles, t: In the cross-section, the average thickness of the particle-coated portion is the portion where the organic resin particles protrude from the surface of the organic resin coating layer in the area where the organic resin particles are absent, and the portion where the organic resin coating layer covers the organic resin coating layer. The units of T, φ, and t are μm. [2] The organic resin coating layer is located on both surfaces of the metal plate, and the organic resin particles are present only in the organic resin coating layer located on one surface of the metal plate. Both of the aforementioned metal plates of The painted metal plate according to [1], wherein the following relationships expressed by formulas (5) and (6) hold true for the two organic resin coating layers located on the surface. 3 ≤ GA ≤ 30 ··· Equation (5) 0.7 ≤ GA / GB ≤ 1.3 ··· Equation (6) Here, in equations (5) and (6) above, GA: The 60-degree specular gloss level G on the surface of the organic resin coating layer containing the organic resin particles, as defined in JIS Z 8741:1997. S (60°) GB: The 60-degree specular gloss G of the surface of the organic resin coating layer that does not contain the organic resin particles, as defined in JIS Z 8741:1997. S (60°) That is the case. [3] The painted metal plate according to [1] or [2], wherein T and t satisfy the relationship expressed by the following formula (7). 5.0 ≦ T / t ≦ 60.0 ··· Formula (7) [4] A painted metal plate according to any one of [1] to [3], wherein the binder resin contained in the organic resin film layer and the organic resin particles satisfy the relationship expressed by the following formulas (8) to (10). EA ≤ EB ··· Equation (8) 60 ≦ EA ≦ 150 ··· Formula (9) 60 ≦ EB ≦ 250 ··· Formula (10) Here, in equations (8) to (10) above, EA: Compression modulus of the binder resin contained in the organic resin film layer at 25°C EB: Compression modulus of the organic resin particles at 25°C The units of EA and EB are MPa. [5] The aforementioned organic resin particles are resin particles made of urethane resin. The painted metal sheet according to any one of [1] to [4], wherein the glass transition temperature Tg of the urethane resin is in the range of -40 to 40°C. [6] The aforementioned organic resin particles are resin particles made of acrylic resin. The painted metal plate according to any one of [1] to [4], wherein the glass transition temperature Tg of the acrylic resin is in the range of 40 to 160°C. [ 7 ] The metal sheet is a zinc-plated steel sheet in which a zinc-plated layer, which is a plating layer containing at least zinc, is located on the surface of a base steel sheet [1]~[ 6 A painted metal sheet as described in any one of the following. [ 8 ] Between the aforementioned organic resin coating layer and the aforementioned zinc-based plating layer, there is further a rust-preventive coating layer containing a rust-preventive pigment and a resin, 7 Painted metal sheet as described in [ ]. [ 9 ] The rust-preventive pigment is a pigment containing at least one element from P, V, Si, and Mg, [ 8 Painted metal sheet as described in [ ]. [ 10 ] The aforementioned organic resin film layer further contains a coloring agent, [1]~[ 9 A painted metal sheet as described in any one of the following. [Explanation of Symbols]

[0168] 1 Painted metal plate 10 metal plate 20, 25 Organic resin coating layer 30 Rust-preventive coating layer 201 Organic resin particles 203 Binder resin

Claims

1. A painted metal plate comprising a metal plate, an organic resin coating layer located on the surface of the metal plate, and organic resin particles dispersed in the organic resin coating layer, The content of the organic resin particles in the organic resin film layer is 1.0 to 16.6% by volume per side, relative to the total solid content volume of the organic resin film layer. When the organic resin film layer is viewed from above in a plan view, the organic resin particles are present in the organic resin film layer at a density of 30 to 120 particles / mm². ２ It is dispersed with a surface density of, A painted metal sheet in which the following relationships expressed by equations (1) to (4) hold true in a cross-section obtained by cutting the organic resin film layer in the thickness direction at an arbitrary position. 10≦T≦40... Formula (1) 50≦φ≦100... Formula (2) 1.50 ≦ φ / T ≦ 10.00 ... Formula (3) 15.00≦φ / t≦90.00... Formula (4) Here, in equations (1) to (4) above, T: Average thickness of the organic resin coating layer in the portion of the cross-section where the organic resin particles are absent. φ: Average particle size of the organic resin particles, t: In the cross-section, the portion of the organic resin particles that protrudes from the surface of the organic resin coating layer in the area where the organic resin particles are absent is the average thickness of the particle-coated portion, which is the portion covered by the organic resin coating layer. The units of T, φ, and t are μm.

2. The organic resin coating layer is located on both surfaces of the metal plate, and the organic resin particles are present only in the organic resin coating layer located on one surface of the metal plate. The painted metal plate according to claim 1, wherein the following relationships represented by formulas (5) and (6) hold true for the two organic resin coating layers located on both surfaces of the metal plate. 3 ≤ GA ≤ 30 ... Equation (5) 0.7 ≤ GA / GB ≤ 1.3 ... Equation (6) Here, in equations (5) and (6) above, GA: The 60-degree specular gloss G of the surface of the organic resin coating layer containing the organic resin particles, as defined in JIS Z 8741:1997. Ｓ (60°) GB: The 60-degree specular gloss G of the surface of the organic resin coating layer that does not contain the organic resin particles, as defined in JIS Z 8741:1997. Ｓ (60°) That is the case.

3. The painted metal plate according to claim 1 or 2, wherein T and t satisfy the relationship represented by the following formula (7). 5.0≦T / t≦60.0... Formula (7)

4. The painted metal plate according to claim 1 or 2, wherein the binder resin contained in the organic resin film layer and the organic resin particles satisfy the relationship represented by the following formulas (8) to (10). EA ≦ EB ... Formula (8) 60≦EA≦150... Formula (9) 60≦EB≦250... Formula (10) Here, in equations (8) to (10) above, EA: Compression modulus of the binder resin contained in the organic resin film layer at 25°C EB: Compression modulus of the organic resin particles at 25°C The units of EA and EB are MPa.

5. The aforementioned organic resin particles are resin particles made of urethane resin. The painted metal plate according to claim 1 or 2, wherein the glass transition temperature Tg of the urethane resin is in the range of -40 to 40°C.

6. The aforementioned organic resin particles are resin particles made of acrylic resin. The painted metal plate according to claim 1 or 2, wherein the glass transition temperature Tg of the acrylic resin is in the range of 40 to 160°C.

7. The painted metal sheet according to claim 1 or 2, wherein the metal sheet is a zinc-plated steel sheet in which a zinc-plated layer, which is a plating layer containing at least zinc, is located on the surface of a base steel sheet.

8. The painted metal plate according to claim 7, wherein a rust-preventive coating layer containing a rust-preventive pigment and a resin is further positioned between the organic resin coating layer and the zinc-based plating layer.

9. The painted metal plate according to claim 8, wherein the rust-preventive pigment is a pigment containing at least one of the elements P, V, Si, and Mg.

10. The painted metal plate according to claim 1 or 2, wherein the organic resin film layer further contains a coloring agent.

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