Technical field
[0001]
The present invention relates to a precoated metal sheet.
The present application, to 09 May 30, 2016, claiming priority based on Japanese Patent Application No. 2016-193436, filed in Japan, the contents of which are incorporated here.
BACKGROUND
[0002]
　For home appliances, building materials, etc. for automobiles, on behalf of the post painting product which has been painted after conventional molding, precoated metal sheet coated with colored organic film it has come to be used. Characteristic that the precoated metal sheet is obtained by coating a colored organic coating on the steel sheet or plated steel sheet subjected to anti-rust treatment, while having a beautiful appearance, has a sufficient workability, corrosion resistance is good have.
[0003]
　When applying the precoated metal plate in the air conditioner outdoor unit and housing equipment heavy salinity district specification, in addition to the corrosion resistance high chemical resistance (acid resistance and alkali resistance) is required. Recently, the required level as acid resistance and alkali resistance have been advanced, in a conventional precoated metal sheet, is no longer able to satisfy the requirements for sophisticated.
[0004]
　For example, Patent Document 1, chrome-free system primer coating composition capable of forming a coating film excellent in corrosion resistance at the end face and scratched surface and processing unit of the precoated coated metal plate is described. Patent Document 1, the primer coating composition is described that includes a variety of non-chromium-based anticorrosive pigment.
　In Patent Document 1, although described are that the primer coating composition is useful in improving the corrosion resistance of the coated metal plate, no consideration is chemical resistance.
[0005]
　Patent Document 2, not only the corrosion resistance of the flat portion of the coated metal plate, coated metal plates having a cured coating film excellent in corrosion resistance of the machined portion and the end face is described. Further, the coating composition for forming a cured coating film, as a component of a chromium-based coating composition, it has been described that includes a variety of anti-corrosion pigment mixture.
　In Patent Document 2, the coating composition have been described that can form a coating film excellent in corrosion resistance of the machined portion and the end face, no consideration is chemical resistance.
[0006]
　Patent Document 3 has a cured coating film excellent in corrosion resistance of the machined portion and the end face of such coated metal plate, plated steel plate containing aluminum as a main component is described. Further, the coating composition for forming the cured coating film, as anticorrosive pigments, vanadium compounds, phosphoric acid metal salt containing magnesium, may contain magnesium ion exchange silica anticorrosive pigment mixture are described.
　In Patent Document 3, although the coating composition based on a cured coating film formed coated metal plate is described to be excellent in corrosion resistance, no consideration is chemical resistance.
[0007]
　Patent Document 4, which has excellent corrosion resistance and moisture resistance, describes a coated steel sheet having a coating film formed by using the coating film forming object to let hard coating composition corroded in short corrosion resistance test there. Further, as a coating composition, vanadium compound and rust promoting agent. However, Patent Document 4, no consideration is chemical resistance.
[0008]
　As described above, the coating compositions described in Patent Documents 1 to 4 are all be one intended to form a corrosion resistant coating, not for the purpose of improving the chemical resistance .
　Results of studies of the present inventors, even as a coating contained the anticorrosive pigment, It just high resistance required for the precoated metal sheet that is applied to the air conditioner outdoor unit and housing equipment heavy salt damage area specification It was found to not be satisfied chemical resistance (the acid resistance and alkali resistance).
CITATION
Patent Document
[0009]
Patent Document 1: Japanese Patent 2012-012497 JP
Patent Document 2: Japanese Patent 2012-131907 JP
Patent Document 3: WO 2012/086494 Patent
Patent Document 4: Japanese Patent 2013-67699 JP
Summary of the Invention
Problems that the Invention is to Solve
[0010]
　As described above, the precoated metal plate to be used in the air conditioner outdoor unit and housing equipment heavy salt damage district specification is assumed, has high degree of chemical resistance is required. However, the conventional precoated metal sheet, paint precoated metal plate, the purpose of improvement of corrosion resistance, has not been considered with respect to chemical resistance.
　The present invention was made in view of the above problems. An object of the present invention is to provide a precoated metal plate having a high degree of chemical resistance in addition to corrosion resistance.
Means for Solving the Problems
[0011]
　The present inventors have conducted extensive studies to accomplish the above objects.
　As high chemical resistance, for example, that there is no even abnormal by immersion for 120 hours in 5% sulfuric acid as acid resistance, and that there is no abnormality was immersed for 120 hours in 5% sodium hydroxide solution as alkali resistance, that there is a case in which it is required to satisfy the conditions. However, the present inventors have, a conventional general paint using painted precoated steel sheet, as a result of the chemical resistance test described above, about 50 hours for acid resistance test, about 24 hours in alkali resistance test blistering the coating film occurred, it could not satisfy the required when exceeded.
　Therefore, the present inventors have found that in order to investigate the cause, in the acid resistance and alkali resistance test was carried out most early stage swelling portion of the cross-sectional microscopy. As a result, the precoated metal sheet, acid, even when immersed in either alkaline, only a small gap at the interface between the plating and the coating film occurs, corrosion plating itself was observed. That starting point of blistering coating, believed that drug reaches the plating surface through the coating film (the surface of the plating layer plated metal sheet has), a fine gap outermost layer occurs dissolved plating It is. Therefore, to improve the chemical resistance, chemicals be transmissive occurs hardly a coating film, so as not to cause a gap chemicals entering to improve the adhesion between the plated surface and coating it, and the plating surface is possible to form a barrier layer so difficult to dissolve by means of chemicals, it was suggested to be effective.
　The present invention, these findings the by was developed on the basis of, specifically, as follows.
[0012]
(1) precoated metal sheet according to one embodiment of the present invention includes a plated metal plate, a primer layer formed on the surface of the plated metal plate, and an upper layer film formed on the surface of the primer layer, the the primer layer, a binder resin, and a pigment particle comprising a vanadium compound and a magnesium compound, the cross section of the thickness direction of the primer layer, the thickness direction from the interface between the plated metal plate and the primer layer in a region within 1.0 .mu.m, when observed by EPMA mapping, absent detection concentration is less than 0.6% area of the vanadium element is continuously the thickness direction and the direction perpendicular to 2.0μm or more and area detecting concentration of magnesium element is less than 3.0% is not present in succession the thickness direction and the direction perpendicular to 2.0μm or more.
(2) The precoated metal sheet according to (1) is a film thickness of 3 ~ 15 [mu] m of the primer layer, the maximum diameter of the thickness direction of the pigment particles, 80% of the thickness of the primer layer it may be less than or equal to.
(3) above (1) or precoated metal sheet according to (2), the binder resin may contain an isocyanate resin.
(4) above (1) to precoated metal sheet according to any one of (3), the content of the pigment particles, relative to the total solid weight of the primer layer, from 15 to 70 mass% it may be.
(5) above (1) to precoated metal sheet according to any one of (4), the vanadium compound, calcium vanadate, one or more selected from the group consisting of magnesium vanadate and ammonium metavanadate , and the said magnesium compound is magnesium vanadate, magnesium oxide, magnesium hydroxide, may be one or more selected from the group consisting of magnesium phosphate.
(6) above (1) to precoated metal sheet according to any one of (5) is between the plated metal plate and the primer layer may further have a chemical conversion film.
(7) above (1) to precoated metal sheet according to any one of (6), the plated metal plate may be a Zn-Al-Mg plated steel sheet.
Effect of the invention
[0013]
　According to this aspect of the present invention, since the distribution of the vanadium compound and the magnesium compound in the primer layer is controlled to be present densely in the lower inner layer, the concentration of the bottom of the primer layer, the vanadium compound and the magnesium compound is not a thin portion is formed and pre-coated metal sheet is obtained with excellent corrosion resistance and high chemical resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
FIG. 1 is a photograph showing a cross-section of the precoated metal sheet of the present invention.
[FIG 2A] is an example of EPMA mapping photograph showing the distribution of the vanadium compound in the primer layer in the cross section of the precoated metal sheet of the present invention (V) (magnification 6000 times).
[FIG 2B] is an example of EPMA mapping photograph showing the distribution of the magnesium compound in the primer layer in the cross section of the precoated metal sheet of the present invention (Mg) (magnification 6000 times).
It is a diagram tracing the EPMA mapping photograph (magnification 6000 times) of FIG 3A] FIG 2A.
It is a diagram tracing the EPMA mapping photograph (magnification 6000 times) of FIG. 3B] Figure 2B.
DESCRIPTION OF THE INVENTION
[0015]
　Hereinafter, (sometimes referred to as pre-coated metal sheet according to the following embodiment) precoated metal plate according to an embodiment of the present invention will be described in detail.
[0016]
　Precoated metal plate according to the present embodiment includes a plated metal plate, wherein a plated metal plate formed on a surface primer layer, and a top layer film formed on a surface of said primer layer.
　The primer layer contains a binder resin and pigment particles containing vanadium compound and magnesium compound.
　Further, in the primer layer, in the thickness direction of the cross section, the area within 1.0μm in the thickness direction from the interface between the plated metal plate and the primer layer, when observed by EPMA mapping, detection of vanadium element concentration is not present is continuously region is less than 0.6% the thickness direction and the direction perpendicular to 2.0μm or more and area the film detecting the concentration of elementary magnesium is less than 3.0% in the thickness direction perpendicular to the direction it does not exist continuously over 2.0 .mu.m.
　Precoated metal plate according to the present embodiment, depending on the application, even if both sides of the metal plate is coated with a coating film described above may be only one side covered, also, a part of the surface covered even the entire surface may be covered. Chemical resistance, corrosion resistance superior in coating film coated portion of the metal plate. When forming the above-described coating on only one side, the surface opposite to impart the minimum corrosion resistance and design properties, may form a known film.
[0017]
　
　plated metal plate used in the precoated metal plate according to the present embodiment (coated metal plate) is a metal plate having a plating layer on the surface. As the constituent metal of the metal plate is not particularly limited, for example, aluminum, titanium, zinc, copper, nickel, and steel and the like are applicable. When using steel, even ordinary steel, may be a steel containing additional elements such as chromium, it is not particularly limited.
　The type of the plating layer formed on the surface of the metal plate also is not particularly limited.
　The applicable plating layer, for example, zinc, aluminum, cobalt, tin, plating made of any one of nickel, and, still further metal elements of these metal elements, alloy plating containing a nonmetallic element etc. the. In particular, the zinc-based plating layer, for example, plating of zinc, zinc and aluminum, cobalt, tin, nickel, iron, chromium, titanium, magnesium, alloy plating with at least one manganese, or still other metallic elements, various zinc-based alloy plating containing a nonmetallic element (e.g., a zinc, aluminum, magnesium, quaternary alloy plating silicon) and the like.
[0018]
　The aluminum-based plating layer, made of aluminum plating, or alloy plating of aluminum and silicon, zinc, and at least one magnesium (e.g., an alloy plating of aluminum and silicon, an alloy plating of aluminum and zinc, aluminum, silicon ternary alloy plating) or the like of magnesium.
[0019]
　The plated metal plate having a zinc-based alloy plated layer or an aluminum-based plating layer, and specific examples thereof include galvanized steel sheet (GI) and Zn-Al-Mg plated steel sheet. With Zn-Al-Mg plated steel sheet to the original sheet, the excellent corrosion resistance is obtained than galvanized steel sheet, preferably. Zn-Al-Mg plating, by the proportion of each component, Zn-6% Al-3% Mg, Zn-11% Al-3% Mg-0.2% Si, and those containing an Ni traces of various Although there, Zn-Al-Mg plated steel sheet component ratio of Zn-11% Al-3% Mg-0.2% Si is particularly preferred.
[0020]
　These plated metal plate degreased and washed, chromate treatment, was subjected to conventional surface treatment such as phosphate treatment, or non-chromate treatment, it is possible to form the primer layer on the surface. Preferred surface treatment, phosphating, is a non-chromate treatment.
[0021]
　
　primer layer formed on the surface of the plated metal plate contains a binder resin and pigment particles containing vanadium compound and magnesium compound.
　Further, the primer layer of the precoated metal plate according to the present embodiment, the vanadium compound and the magnesium compound, region within 1.0μm from the interface with the lower region (plated metal plate and the primer layer in the thickness direction of the primer layer in), as described later, the detected concentration is not present is continuously region is less than 0.6% the thickness direction and the direction perpendicular to 2.0μm or more and detecting the concentration of elemental magnesium vanadium element there it is necessary region is less than 3.0% is distributed so as not to present continuously over 2.0μm in film thickness direction perpendicular to the direction.
[0022]
　As long as the distribution as described above, the form of addition of these compounds is not particularly limited. That is, the form of adding the vanadium compound and the magnesium compound into the coating solution for forming the primer layer, the liquid may be either solid. However, solid form, it is preferable to add, especially in particulate form. Trend because, if these compounds were added as a liquid, which solidified by solvent during drying of the coating film is vaporized compound is precipitated, resulting in the compound is present in a fine and uniform state in the coating film There are, there may be a case that the vanadium compound in the lower region of the primer layer, the need to add more compounds to increase the concentration of the magnesium compound occurs. More specifically, it is preferable to add a pigment particle containing the vanadium compound and the magnesium compound to the coating solution for forming the primer layer.
[0023]
　Water containing acid or alkali component is transmitted through the upper layer film formed on the surface of the primer layer, and a primer layer, to reach the plating surface, dissolving the plated surface.
　Vanadium compound in the primer layer is dissolved in water containing entering the acid or alkali component, where the vanadate ions are released. The vanadate ions, to produce the salt reacts with the metal of the plated surface. This salt, by forming the dense barrier layer in the interface between the plating and the primer layer, to retard penetration was chemicals to attack the plated surface. Therefore, by the vanadium compound in the lower region of the primer layer is densely present, from the very early stage of the plating is dissolved by acid or alkali reaching the plating surface, quickly to high concentrations of vanadate ions plated surface is supplied, it is possible to form a dense barrier layer.
[0024]
　The vanadium compounds, such as calcium vanadate, magnesium vanadate, ammonium metavanadate, potassium vanadate, sodium vanadate, ammonium vanadate, various vanadates such as phosphoric vanadate, and use particles of pigments such as vanadium oxide be able to. Vanadium pentoxide is preferably not used because of toxicity. These compounds may be included alone, or may include multiple is.
　Among these vanadium compounds, for reasons of balance between corrosion resistance and water resistance by having a moderate solubility as anticorrosive pigment is good, calcium vanadate, magnesium vanadate, and / or ammonium metavanadate particularly preferred.
[0025]
　The content of the vanadium compound in the primer layer, based on the entire solid content mass of the primer layer is preferably 3 to 50 mass%. If the content is less than 3 wt%, the area within 1.0μm in film thickness direction from the lower surface in the thickness direction cross section of the primer layer (the interface with the plated metal plate and the primer layer), the vanadium element can not be sufficiently densely present, the corrosion resistance and chemical resistance is a concern that undesirably reduced.
　On the other hand, if the content of the vanadium compound to the total solid content of the primer layer exceeds 50 wt%, not only economical saturated the effect of corrosion resistance and chemical resistance improvement, the increase of the total content of pigment It invited, so the workability may be lowered undesirably. On having improved corrosion resistance and chemical resistance, in order to ensure the processability required as pre-coated metal sheet, the content of the vanadium compound in the total solid mass of the primer layer is 4-50 wt% even more preferably from 10 to 30% by weight.
[0026]
　Magnesium compound of the primer layer is dissolved in water containing entering the acid or alkali component, in which magnesium ions are released. The magnesium ions will react with the plating surface to produce the salt. Further, in the alkaline environment, magnesium hydroxide is formed at the same time. These salts and / or magnesium hydroxide, plating - by forming the dense barrier layer to the primer layer interface, to retard penetration was chemicals to attack the plated surface.
[0027]
　The magnesium compound, magnesium vanadate, magnesium oxide, magnesium hydroxide, various phosphate magnesium such as magnesium phosphate, magnesium silicate, magnesium carbonate, magnesium chloride, magnesium nitrate, magnesium citrate, magnesium acetate, magnesium formate, etc. pigment particles such as various magnesium and magnesium ion exchange silica, can be used. These compounds may be included alone, or may include multiple is.
　Among these magnesium compounds, because of the balance between corrosion resistance and water resistance by having a moderate solubility as anticorrosive pigment is good, magnesium vanadate, magnesium oxide is particularly preferred.
[0028]
　The amount of magnesium compound of the primer layer with respect to the total solid mass of the primer layer is preferably 3 to 50 mass%. When the content of the magnesium compound to the total solid content of the primer layer is less than 3 wt%, within 1.0μm in film thickness direction from the lower surface of the cross section of the primer layer (the interface with the plated metal plate and the primer layer) can not the magnesium in the area elements to be present in sufficiently tight, because the corrosion resistance and chemical resistance is a concern that undesirably reduced.
　On the other hand, if the content of the magnesium compound to the total solid content of the primer layer exceeds 50 wt%, not only economical saturated the effect of corrosion resistance and chemical resistance improvement, the increase of the total content of pigment It invited, so the workability may be lowered undesirably. On having improved corrosion resistance and chemical resistance, from the viewpoint of securing the workability required, the content of the magnesium compound, more preferably from 4 to 50 wt%, more preferably 10 to 30 mass%.
[0029]
　Vanadium compound and magnesium compound, if any average particle diameter is 1.0μm or less, will be present in sufficiently fine state. In this case, the vanadium compound and the magnesium compound uniformly dispersed in the coating solution, coating, is moved in the direction of the interface between the plated metal plate with a primer layer by heat drying process, densely in a position adjacent to the plated surface it is advantageous in order to exist. Therefore, the average particle size of the vanadium compound and the magnesium compound in the primer layer, respectively, are preferably in the following range 1.0 .mu.m.
　If the average particle diameter of the primer layer and 1.0μm or less, it is preferable that a 1.0μm or less the average particle size of the pigment particles to be added to the coating solution.
[0030]
　When the average particle size of the added pigment particles is less than 0.5 [mu] m, it takes time to classification of pigment is not preferable because the increased cost. Therefore, the average particle size of the vanadium compound and the magnesium compound contained in the primer layer may be more than 0.5 [mu] m.
[0031]
　Method of measuring the average particle size of the vanadium compound and the magnesium compound contained in the primer layer is as follows.
　It was embedded in a resin so as to appear the plate thickness direction cross-section by cutting the precoated metal sheet of interest into an appropriate size, polished cross-section, then the magnification 6000 the EPMA mapping analysis of the primer layer of the cross section (polished surface) carried out at twice (accelerating voltage 15kV). Select V and Mg as a detection target element, a mapping shooting the location and the element concentration of each element. Then, the same position of the same sample, and the SEM image photographed at a magnification of 6000 times, by comparing the previous EPMA mapping image, identifies all vanadium compound and the magnesium compound on the SEM image. The 20μm and measurement range in the direction of the plane of the metal plate on the SEM image, all particle size (if not a perfect circle longest diameter: diameter) of the vanadium compound and the magnesium compound present in the primer layer in the range to measure. The vanadium compound, calculates the average particle size for each of the magnesium compound, the average particle size of the vanadium compound contained in the primer layer and the magnesium compound.
　If a plurality of vanadium compound and the magnesium compound are aggregated, the aggregated compounds regarded one and the particle size measured (major axis).
[0032]
　The primer layer of the precoated metal plate according to the present embodiment, it is important to contain the vanadium compound and the magnesium compound at the same time.
　When containing a vanadium compound and the magnesium compound at the same time, while vanadate ions emitted from the vanadium compound is adsorbed on the plating surface to form a salt by reacting with metal plating surface, magnesium ions emitted from a magnesium compound magnesium hydroxide plating surface to form the coating of vanadium salts of the plating surface is stronger barrier properties in the form to fill the portion not sufficient. As a result, it is possible to particularly dramatically improve the alkali resistance which is inferior in Al-containing plating. This effect, vanadium compounds, greater than the magnesium compound the sum of effects obtained when present alone, respectively. That is, a synergistic effect can be obtained by containing a vanadium compound and the magnesium compound at the same time, it is possible to obtain very good chemical resistance, in particular a very good alkali resistance.
[0033]
　As described above, in the precoated metal plate according to the present embodiment, in a region close to the plated metal plates in the primer layer, the vanadium compound and the magnesium compound is intensively distributed, are each a certain level of concentration This is very important. That is, in the primer layer, the region within 1.0μm from the lower surface in the thickness direction cross section of the primer layer (the interface with the plated metal plate and the primer layer) in the thickness direction, EPMA (Electron Probe Micro Analyzer) Mapping when observed by absent area detecting concentration of vanadium element is less than 0.6% is continuously above 2.0μm in film thickness direction perpendicular to the direction (plane direction), and the detected concentration of elemental magnesium there area of ​​less than 3.0% is not present in succession a film thickness direction and the direction perpendicular to 2.0μm or more.
[0034]
　Vanadium compound and the magnesium compound in the primer layer, is present as particles, these compounds lower the element concentration in the sparse portion, sufficient corrosion resistance and chemical resistance can be obtained. The concentration of the vanadium element (detection concentration obtained by EPMA mapping) is less than 0.6%, or the concentration of elemental magnesium (detection concentration) in the region of less than 3.0%, the vanadic acid released from a vanadium compound and a magnesium compound the concentration of ions and magnesium ions becomes insufficient to ensure the chemical resistance and corrosion resistance.
　That is, the area within 1.0μm in film thickness direction from the lower surface of the primer layer, when observed by EPMA mapping, detecting density areas or elemental magnesium detection concentration is less than 0.6% of the vanadium element 3.0 area of less than percent, (to vertical (perpendicular to the thickness direction) direction) plane direction when present continuously over 2.0μm in that part is present sparse portion of the vanadium compound and a magnesium compound, since vanadate ions or magnesium ions are not supplied sufficiently plated surface, no sufficient corrosion resistance and chemical resistance can be obtained. Therefore, in the primer layer of the precoated metal plate according to the present embodiment, in a region within 1.0μm in film thickness direction from the lower surface of the primer layer, the detected concentration is lower than 0.6% area of the vanadium element, magnesium element any of the detected concentration of less than 3.0% area of which is controlled so as not to present continuously over 2.0μm in the planar direction (the thickness direction perpendicular to the direction).
[0035]
　How to measure the vanadium element and magnesium element concentration by EPMA mapping is as follows.
　Embedded in a resin so as to cut the precoated metal sheet of interest to size the plate thickness direction cross-section visible, polished cross-section, then the EPMA mapping analysis of the primer layer of the cross section, the thickness direction of the primer layer for a range of more than 20μm in the direction orthogonal to the performed at 6000 × magnification (accelerating voltage 15kV). Select V and Mg as a detection target element, to map the location and concentration of element of each element.
　Figure 2A an example of the distribution and EPMA mapping photograph showing the distribution of each of the magnesium compound of the vanadium compound in the primer layer cross-section of the precoated metal plate according to the present embodiment (magnification 6000 times), in FIG. 2B, these were traced FIG , 3A, shown in Figure 3B. In Figure 2A, Figure 2B, with the concentration indicated by the color mapping, at the following intervals 2.0μm in the planar direction, it is shown together detect concentrations measured in detail. Figure 2A, as shown in Figure 2B, in the primer layer of the precoated metal plate according to the present embodiment, the detected concentration is also a region of less than 0.6%, the area below the detection concentration of 3.0 percent of elemental magnesium vanadium element also, none existed continuously over 2.0μm in the planar direction (the thickness direction perpendicular to the direction).
[0036]
　By fine particles of vanadium compound and the magnesium compound from the lower surface region within 1.0μm of the cross section of the primer layer is intensively distributed, vanadium compound and the magnesium compound serving as the source of each ion plating It will be present densely in the vicinity. In this case, none of these vanadate ions and magnesium ions released from the compound can reach quickly plated surface. Thus, when the drug is entering, before the plated surface is affected by the chemicals which has entered, to rapidly form a dense barrier layer on the plating surface, it penetrates the drug is prevented from eroding the plated surface can. As a result, it is possible to impart excellent chemical resistance to the precoated metal plate. Vanadium compound and magnesium compound present in the upper region of the primer layer also dissolved in water containing acid or alkali component, releasing vanadate ions, magnesium ions. However, when the distance from the plating surface is long, released vanadate ions, magnesium ions diffuse mostly in the primer layer, the concentration reaching the plating surface is very small, the contribution to the chemical resistance improvement It is considered very small.
[0037]
　The region within 1.0μm from the lower surface of the cross section of the primer layer, by concentrating distributed fine particles of vanadium compound and a magnesium compound, in addition to the improvement of chemical resistance, corrosion resistance is further improved. This has been demonstrated by the results of Examples described later. The reason for this is not clear, scratched upper film and the primer layer, even if the plated surface was injured, the region within 1.0μm from the lower surface of the cross section of the primer layer, concentrate there Te vanadium compound and released from the magnesium compound vanadate ions and magnesium ions, presumably because by covering the immediate injured plated surface.
[0038]
　The primer layer of the precoated metal plate according to the present embodiment may include a rust preventive pigment other than vanadium compound described above and a magnesium compound. For example, mention may be made of aluminum tripolyphosphate, calcium ion exchange silica, the anticorrosive pigment such as silica. If necessary, precipitated barium sulfate, and extender pigment clay, may further contain coloring pigments such as titanium oxide.
[0039]
　The total content of pigment particles (pigment particles vanadium compound, the pigment particles are magnesium compounds, and other pigment particles) with respect to the total solid mass of the primer layer, from 15 to 70 mass% preferable. If the content is less than 15 wt%, by where the rigidity and cohesion of the coating film decreases, the coating film peeling occurs when the coating film surface is rubbed with the mold during the pressing of the steel sheet (coating film galling) was made for easy, undesirable. Further, when the total content exceeds 70 mass%, since the workability is deteriorated, unfavorably. Corrosion, in view of the balance of chemical resistance and processability, and more preferably 20 to 50 mass%.
[0040]
　The size of the pigment particles of the primer layer is preferably the maximum diameter of the membrane thickness direction of the total pigment particles is 80% or less of the film thickness of the primer layer. Chemicals are believed to easily penetrated along the interface between the pigment and the binder resin. Therefore, the pigment having a large diameter to the thickness direction exceeds 80% of the primer layer thickness is present, may become a form close to the primer layer pigment penetrates vertically, locally infiltration of chemicals promote there is a risk that is. In this case, the starting point of the bulging chemicals penetrated position, considered chemical resistance is lowered. It is more preferable from this point of view, the maximum diameter of the membrane thickness direction of the pigment particles is less than or equal to 60% of the thickness of the primer layer.
[0041]
　Maximum diameter in the thickness direction of the pigment of the primer layer may be obtained by the following method.
　Was embedded in a resin so as to appear the plate thickness direction cross-section by cutting the precoated steel sheet of interest into an appropriate size, polished cross-section, then taking a SEM image of the primer layer of the cross-section at a magnification 6000 times. The 100μm in the direction of the plane of the steel sheet on the SEM image and the measurement range, of all pigments present in the measurement range, if the film thickness direction of the particle size (pigment of the primer layer is not a perfect circle, occupied by the pigment range far distance position to) is the film thickness direction of the greatest pigment particle size from the nearest position from the substrate, is defined as the maximum diameter of the total pigment contained in the primer layer. If a plurality of pigment are aggregated to measure the maximum diameter is regarded as one of this.
[0042]
　The film thickness of the primer layer is preferably 3 ~ 15 [mu] m. If the film thickness is less than 3 [mu] m, it is not preferable because no sufficient corrosion resistance and chemical resistance can be obtained. On the other hand, if the film thickness exceeds 15 [mu] m, since processability is undesirably reduced. Corrosion, chemical resistance, and in view of good balance of processability, the thickness of the primer layer is more preferably in the range of 4 ~ 10 [mu] m.
[0043]
　The binder resin contained in the primer layer is not particularly limited. For example, a polymer polyester resin, polyester resin, acrylic resin, epoxy resin, urethane resin, fluorine resin, or a film-forming resin component, such as those modified resins, butylated melamine resins, methylated melamine resins, butylmethyl mixed melamine resin , urea resins, by isocyanate resin and crosslinker components of these mixtures based, or the like can be used those obtained by cross-linking by heating. Or electron beam-curable resin, or the like may be used ultraviolet-curing resin. As the crosslinking agent used in these binder resins, it is particularly preferable to use a curing agent of an isocyanate resin. For example, the film-forming resin component comprising a polyester resin, a crosslinker component of the isocyanate resin, it is preferable to use those obtained by cross-linking by heating. Coating film formed by isocyanate curing, together with crosslinking points becomes dense urethane bond, and reacting with a hydroxyl group (-OH) present on the plating surface of the plated metal plate, to improve the adhesion between the plated metal plate effect by it obtained, because the chemical resistance good resin is obtained.
　As a method for the binder resin to confirm that the isocyanate curing cleaves precoated metal sheet of interest into an appropriate size to the embedding resin, polished cross-sectional direction, then microscopic primer layer coating section FT performs IR measured by a method such as -IR, 1550 cm -1 absorption and urethane bond in the vicinity, 2260 cm -1 can be determined by checking the C = N absorption peak derived from isocyanate appearing in the vicinity.
[0044]
　Examples of the isocyanate resin used as a curing agent, IPDI (isophorone diisocyanate), TDI (tolylene diisocyanate), MDI (4,4'-diphenylmethane diisocyanate), HMDI (hexamethylene diisocyanate), hydrogenated MDI, hydrogenated XDI (xylylene diisocyanate), monomeric various isocyanates typified by hydrogenated TDI, etc., dimers, a prepolymer having trimers and these isocyanate skeleton, methanol, ethanol, butanol, propanol, phenol, cresol , block typified chlorophenol, nitrophenol, hydro phenol, acetylacetone, ethyl acetoacetate, ethyl malonate, lactam, phosgene, 1-chloro-2-propanol, the MEK oxime, etc. Those blocks are mentioned click agent. However, the type of isocyanate resin type and the blocking agent is not limited to those described above. Lactam block MDI, MEK oxime-blocked IPDI are particularly preferred.
[0045]
　Primer layer precoated metal sheet according to the present embodiment, anticorrosive pigment, extender pigment, in addition to a binder resin, a colorant, a viscosity adjusting agent, leveling agent, it may also contain defoamers, additives such as ultraviolet absorber .
[0046]

　The precoated metal plate according to the present embodiment, the upper layer film on the primer layer. The upper layer coating, according to the application, the binder resin, as long as it contains a coloring pigment is not particularly limited. Upper film, like the upper film of conventional precoated steel sheet may be used as the coating layer or layers.
[0047]
　As the binder resin of the upper layer film, it is not particularly limited. For example, a polymer polyester resin, polyester resin, acrylic resin, epoxy resin, urethane resin, fluorine resin, or a film-forming resin component, such as those modified resins, butylated melamine resins, methylated melamine resins, butylmethyl mixed melamine resin , urea resins, by isocyanate resin and crosslinker components of these mixtures based, or the like can be used those obtained by cross-linking by heating. Or electron beam-curable resin, or the like may be used ultraviolet-curing resin. Also these resins alone, or may be used in combination of two or more.
[0048]
　The coloring pigment of the upper layer film may be a known inorganic and organic coloring pigments, titanium oxide as inorganic coloring pigments, zinc oxide, zirconium oxide, calcium carbonate, barium sulfate, alumina, kaolin clay, carbon black, oxide it can be used such as iron, as the organic color pigments can be used Hansa Yellow, pyrazolone orange, phthalocyanine, azo pigments.
[0049]
　The thickness of the upper layer film is preferably 5 ~ 50 [mu] m as a dry thickness. If it is less than 5μm not only chemical resistance and corrosion resistance is a concern to be reduced, decreased color covering property, it can not be sufficiently obtained design. The workability dry film thickness exceeds 50μm is deteriorated. The thickness of the upper layer coating is more preferably 10 ~ 25 [mu] m.
[0050]
　Precoated metal plate according to the present embodiment, regardless of the manufacturing process, as long as the above-described configuration, the effect is obtained. However, according to the manufacturing method including, for example following steps, preferably so it obtained stably.
[0051]
　
　on the plated metal plate, if desired to form a chemical conversion coating by performing a chemical conversion treatment by a known method, then applying a primer layer forming coating solution, and dried by heating primers to form a layer.
　Chemical treatment, although known non-chromate-type treatment can be widely used, in particular, a treatment liquid containing tannic acid and a silane coupling agent, 10 ~ 1000 mg / m on a dry film weight 2 is coated and dried so as to by, since very high coating adhesion can be obtained.
[0052]
　Primer layer coating solution]
　The primer layer coating liquid for forming the, the solvent, the above-mentioned binder resin components, as well, it is preferable to comprise a pigment comprising a vanadium compound and a magnesium compound. In addition to these components, a leveling agent, a defoaming agent, a colorant, a viscosity modifier, it may contain additives such as ultraviolet absorbers.
[0053]
　To be vanadium element and magnesium element from the lower region (a region within 1.0μm from the interface in the thickness direction of the plated metal plate and the primer layer) of the primer layer is densely detected as described above, coating solution for forming the primer layer is applied to the plated surface of the metal plate, was then heated dried by step, to move the pigment particles of the vanadium compound and the magnesium compound in the coating liquid in the direction of the interface between the plated metal plate Te, it is effective to localize vanadium compound and magnesium compound. Its surface energy pigment particles containing vanadium compound and the magnesium compound is an inorganic pigment Any sufficiently higher than that of the binder resin. Therefore, by the pigment particles are controlled into a state that can be moved sufficiently freely in the coating solution, in a series of steps, the surface tension is relatively low binder resin component is moved to the surface direction of the primer layer by convection , the pigment particles are localized in the lower region of the primer layer.
　To a state in which the pigment particles described above can move sufficiently freely in the coating solution, the viscosity of the coating solution for forming the primer layer, in the range of 20 seconds to 50 seconds in Iwata cup viscometer it is desirable. The viscosity of the coating solution can be adjusted by a solvent amount. For higher viscosity than 50 seconds of the coating liquid, the pigment particles containing vanadium compound and the magnesium compound in the coating liquid can not move freely, from the lower region of the primer layer after drying as a result vanadium element and magnesium element is not densely detected. Meanwhile, since the viscosity of the coating solution is in the low viscosity than 20 seconds, solvent ratio is too high in the coating solution, coating defects bubbles remaining in the coating film so-called "side" in the drying step occurs, producing unfavorable as a condition.
[0054]
　Although the method of coating the coating solution having a controlled concentration range mentioned above is not particularly limited, dipping method, a curtain flow method, roll coating method, bar coating method, an electrostatic method, a brush coating method, T-die method, such as lamination, any method can be used. The drying method of the coating liquid, actively generate convection in the coating liquid by heating from the original sheet side in the heating step, high-frequency induction heating can be promoted vanadium compound pigments and magnesium compounds localization of the pigment, or heating system that combines the high-frequency induction heating is preferable.
[0055]

　the plated metal plate in which the primer layer is formed, after applying the upper layer coating the coating liquid for forming the upper film and dried by heating. If the upper layer coating are multiple further repeated to produce a precoated metal plate this step. For the method of applying the upper layer film is not particularly limited, for example, a dipping method, a curtain flow method, roll coating method, bar coating method, an electrostatic method, a brush coating method, T-die method, lamination, spraying, etc. and the like. In addition, it is also possible to use a wet-on-wet coating method or a multilayer simultaneous coating method.
[0056]
　The drying method is hot air, near infrared, far infrared, high frequency induction heating or heating method according to these composite such as is any method can be applied.
Example
[0057]
　Hereinafter, the present invention will be described with reference to examples. Conditions in examples are an example of conditions adopted for confirming the workability and effects of the present invention, the present invention is not limited to this single example of conditions. The present invention does not depart from the gist of the present invention, as long as they achieve the object of the present invention may employ various conditions.
　Used in Example (Embodiment) and Comparative Example, plated metal plate, primer layer, shown in Tables 1 to 4 and the following contents of the upper layer film.
[0058]
　 SD: Zn-11% Al-3% Mg-0.2% Si alloy-plated steel sheet (sheet thickness: 0.6 mm, coating weight: per side 40 g / m 2 )
　GI: hot-dip galvanized steel sheet (thickness: 0.6 mm, coating weight: per side 40 g / m 2 )
　after alkali degreasing the front and back surfaces of the original plate, chromate-free chemical conversion solution (silane coupling agent, tannic acid, silica, and a polyester resin mixed system) by chemical treatment (coating weight: one side 100 mg / m 2 was used after) and. Plating layer was formed on both sides of the metal plate.
[0059]
　
　to form a primer layer on one surface of the chemical conversion treated plated metal plate. Film-forming resin component and a curing agent was used in the binder resin of the primer layer used in Examples and Comparative Examples are as follows.
[0060]
(Film-forming resin component)
Polyester resin "Vylon 300" (manufactured by Toyobo; Tg7 ° C., a number average molecular weight 26000, a hydroxyl value of 4, an acid value of 2 or less)
[0061]
(Curing agent)
Melamine resin "Cymel 235" (manufactured by Mitsui Chemicals, Inc., methoxy / butoxy mixture modified melamine resin)
isocyanate "Coronate 2536" (Nippon Polyurethane Industry Co., Ltd .; lactam block / diisocyanate (MDI))
　film-forming the mixing ratio of the resin component and the curing agent, the curing agent is 80 to 20 in the case of melamine resin, the curing agent is in the case of isocyanate was 90 to 10 (all solids weight ratio).
[0062]
　Examples and vanadium compound pigments and magnesium compound pigment was used in the primer layer used in Comparative Examples, other anticorrosive pigments are as follows.
A: Calcium vanadate
B: magnesium vanadate
C: calcium vanadate - Magnesium
D: magnesium oxide
E: Ca ion exchange silica (Grace Co.: seal Dex
C303) F: aluminum phosphate (manufactured by Tayca Corporation: K-White # 82)
　in table 1, which pigment concentration is shown in italics indicate that was used to remove the pigment particle size of less than 1.0 .mu.m.
[0063]
　In addition, some of the primer layer was added the following pigments in the amount of the following (wt-% solids).
G: barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.: Precipitated barium sulfate 100)
5% H: titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd.: CR95) 2%
[0064]
　The above binder resin and pigment variously selected, the pigment weight concentration as shown in Table 1 (PWC), mixed and dispersed by composition ratio to prepare a primer layer forming coating liquid. Then, cyclohexanone was diluted with the addition of one-to-one mixed solvent of Solvesso 150 (a hydrocarbon-based organic solvent), was adjusted to a predetermined viscosity of the coating material.
[0065]
　Various primer layer forming coating solution prepared chemical conversion treatment to the surface of the metal plate subjected to coating with a bar coater so that a variety of dry film thickness, PMT reached (peak metal temperature) 215 ° C. in 45 seconds under conditions in which, dried in an induction heating oven.
[0066]
　
　on which to form a primer layer, (containing 50% by weight of Nippon Paint Co. polymeric polyester / butylated melamine curing FLC7000 paint (titanium oxide white pigment at a solids concentration)) white paint for precoated was applied with a bar coater so that a variety of dry film thickness, dried in a hot air oven under the conditions reached in PMT (peak metal temperature) 230 ° C. in 45 seconds.
[0067]

　In common to all Examples and Comparative Examples, the precoat backside paint (BASF Corp. RB02 paint), dry film on the back surface of the metal plate subjected to chemical conversion treatment (a surface which did not form a primer layer) thickness was coated by a bar coater so that the 5 [mu] m, the condition reached in PMT (peak metal temperature) 230 ° C. in 45 seconds, and dried in a hot air oven.
[0068]

　above as fabricated in Example and Comparative Example Resin as by cutting the precoated metal sheet to a size of 15 × 20 mm visible thickness direction of the the embedded, polished cross-section, then, was subjected to EPMA mapping analysis of the primer layer of the cross-section at a magnification of 6000 times (accelerating voltage 15kV). In a region within 1.0μm in film thickness direction from the lower surface of the cross section of the primer layer, the range of 20μm in a plane direction (direction perpendicular to the film thickness), the detected concentration of the vanadium element is less than 0.6% area , and the detected concentration of the magnesium element region of less than 3.0 percent, to confirm whether there continuously over 2.0μm in the planar direction.
[0069]
　Detection concentration is less than 0.6% area of ​​the vanadium element, for each of the detected concentration is lower than 3.0% area of ​​the magnesium element, is detected in the absence or more consecutive 2.0μm in the plane direction (densely the case) OK, were if present continuously over 2.0μm in the plane direction (if detection is sparse) was evaluated as NG.
[0070]
　In the manner described above, in the primer layer, a vanadium compound, an average particle diameter of the magnesium compound, to determine the maximum diameter in the thickness direction before the pigment.
[0071]
　
　using pre-coated metal sheet of Examples and Comparative Examples, corrosion resistance (SST), chemical resistance (acid resistance, alkali resistance), and were evaluated processability (T bend). Hereinafter, a method for evaluation and each test.
[0072]
Corrosion resistance (salt spray test (SST))
　from pre-coated metal sheet, samples were taken 70 × 150 mm, deep wound up to this cut end surface of the sample was coated seal, leading to iron fabric with a cutter knife coating the steel sheet surface a specimen placed in a X shape, upper and lower short sides painted seal, two left and right long sides were prepared and test pieces were cut by shear in a direction facing burr on the back side. These test pieces by the method of JIS K5600-7-1, 960 hours and 1500 hours, was carried out the salt spray test.
[0073]
　After completion of the salt spray test, the maximum blister width from the X-cut portion and the cut end surface (X-cut portion on one side) were measured by loupe observation. The evaluation criteria were as follows, it was one rejected.
4: 2 mm less than
3: 2 mm more than 4mm less
2: less than 4mm or 6 mm
1: 6 mm or more
[0074]
Chemical resistance (acid resistance, and alkali resistance)
　of the cut end surface and the rear surface of the precoated metal sheet of the sample size 50 × 50 mm test piece was sealed with Teflon (registered trademark) adhesive tape, a 5% sulfuric acid as the acid resistance test 120 time was immersed for 120 hours in 5% sodium hydroxide solution as alkali resistance test. After completion of the test, to evaluate the degree of swelling of the coating film.
[0075]
　The evaluation criteria were as follows, it was one rejected.
4: completely no blistering
3: mild swelling (swelling area ratio less than
1%) 2: moderate blistering (swelling area ratio less than
1-10%) 1: Severe swelling (10% or more blister area ratio)
[0076]
Processability (T bend)
　were T bend test. At 20 ° C., subjected to bending 0T, the state of cracking and peeling of the processed portion was observed with a 10-fold loupe, and evaluated as follows, to a fail.
4: cracking, peeling is not observed at all.
3: very slight cracks or peeling is seen.
2: moderate cracking or peeling seen.
1: severe cracking or peeling is seen.
[0077]
　Table 3 The evaluation results are shown in Table 4. Embodiment will be described with respect to differences in the major evaluation results of Comparative Examples.
　Comparative Examples 1,2,3,4,6 and 7, pigment particles vanadium compound, does not contain either or both of the magnesium compound. Therefore, the region of the detected concentration less than 0.6% of the vanadium element from the lower surface region within 1.0μm in film thickness direction of the cross section of the primer layer is not present continuously over 2.0μm in the planar direction, and , the detected concentration of 3.0% less than the area of the magnesium element is not present in succession over 2.0μm in the planar direction, it did not meet the condition that. As a result, chemical resistance, particularly alkali resistance was decreased. Also were lower corrosion resistance.
　And detecting a concentration of 3.0% less than the area of the detected concentration of 0.6% less than in the region is not present in succession over 2.0μm in the planar direction and elemental magnesium vanadium element is continuous in the planar direction 2.0μm or more the fact that no over the entire measuring range, the detected concentration is equal to or greater than 0.6% area of the vanadium element is present in the following intervals 2.0 .mu.m, and the detected concentration of 3.0% or more regions of the magnesium element It means that there at intervals of less than 2.0μm.
[0078]
　Comparative Example 5, the vanadium compound, containing both magnesium compound, was less content. As a result, the region within 1.0μm in film thickness direction from the lower surface of the cross section of the primer layer, detecting a concentration of less than 0.6% area of ​​the vanadium element is not present in succession over 2.0μm in the planar direction and detecting a concentration of 3.0% less than the area of ​​the magnesium element is not present in succession over 2.0μm in the planar direction, it did not meet the condition that. As a result, chemical resistance, in particular resulted alkali resistance is poor, also was low corrosion resistance.
[0079]
　Comparative Examples 8, 9, and 10, results of using the pigment removal of particle size less than 1.0μm vanadium compound and a magnesium compound, an average particle diameter of the magnesium compound containing is increased. As a result, the detected concentration of 3.0% less than the area of ​​the detected concentration of 0.6% less than the area and magnesium element not present continuously over 2.0μm in the planar direction of the vanadium element is more than 2.0μm in the planar direction not continuously exist, it does not satisfy the condition that, chemical resistance, was particularly alkali resistance low.
[0080]
　Comparative Example 11, the higher the viscosity of the primer layer forming coating solution, coating, fluidized pigment is not sufficiently performed in the drying process. As a result, the detected concentration of 3.0% less than the area of ​​the detected concentration of 0.6% less than the area and magnesium element not present continuously over 2.0μm in the planar direction of the vanadium element is more than 2.0μm in the planar direction It does not exist in succession, did not meet the condition that. Therefore, chemical resistance, was particularly alkali resistance low.
[0081]
　Both Examples 1 to 42, corrosion resistance, chemical resistance, were generally good in both formability. However, the difference of superiority or inferiority in performance was observed by a variety of conditions. For example, Example 15 has a high total pigment concentration in the primer layer, also Examples 17 and 18, by a high pigment concentration of vanadium compound or a magnesium compound, either as a result increases the total pigment concentration of the primer layer , workability tended to decrease.
[0082]
　Example 21, by a thick primer film thickness, workability tended to decrease. Examples 23 and 24, by a thin primer film thickness does not satisfy the condition that the major axis of the pigment particles is not more than 80% of the thickness of the primer layer, corrosion resistance and chemical resistance tended to decrease .
[0083]
　Example 25, coating defects primer layer (aside) is generated by the low viscosity of the coating liquid, after application and drying the upper layer film with even appear as poor appearance tend to corrosion resistance and chemical resistance is lowered It was seen.
[0084]
　Examples 28, 29 and 30, because it uses a melamine resin as a curing agent for the binder resin, workability alkali resistance and than the isocyanate curing tended to decrease.
[0085]
　Example 35, the film thickness of the upper layer coating is thick, workability tended to decrease.
[0086]
[Table 1]

[0087]
[Table 2]

[0088]
[table 3]

[0089]
[Table 4]

Industrial Applicability
[0090]
　According to the present invention, to control the distribution of vanadium compound and the magnesium compound in the primer layer in the inner-layer bottom, the bottom of the primer layer, by so that the concentration of the vanadium compound and the magnesium compound does not form a thin portion, and sufficient workability, precoated metal sheet is obtained and a good corrosion resistance and high chemical resistance. Therefore, there is a high availability of the industry.

The scope of the claims
[Requested item 1]
　A plated metal plate,
　wherein a primer layer formed on the surface of the plated metal plate,
　and an upper layer film formed on the surface of the primer layer,
has,
　the primer layer, a binder resin, a vanadium compound and a magnesium compound and a pigment particle comprising,
　said thickness direction of the cross section of the primer layer, the region within 1.0μm in the thickness direction from the interface between the plated metal plate and the primer layer, when observed by EPMA mapping , the detected concentration of the vanadium element is not present in succession a region is less than 0.6% the thickness direction and the direction perpendicular to 2.0μm or more and, in the detected concentration of the magnesium element is less than 3.0% a region is not present in succession the thickness direction and the direction perpendicular to 2.0μm or more,
precoated metal sheet, characterized in that.
[Requested item 2]
　The thickness of the primer layer becomes 3 ~ 15 [mu] m,
　the thickness direction of the maximum diameter of the pigment particles, the film is not more than 80% of the thickness of the primer layer,
according to claim 1, characterized in that pre-coated metal plate.
[Requested item 3]
　Precoated metal plate according to claim 1 or 2, wherein the binder resin is characterized in that it comprises an isocyanate resin.
[Requested item 4]
　The content of the pigment particles, relative to the total solid weight of the primer layer is 15 to 70 mass%,
the precoated metal sheet according to any one of claims 1 to 3, characterized in that.
[Requested item 5]
　Wherein the vanadium compound is calcium vanadates, is at least one selected from the group consisting of magnesium vanadate and ammonium metavanadate,
　said magnesium compound, magnesium vanadate, magnesium oxide, magnesium hydroxide, of magnesium phosphate it is one or more selected from the group,
precoated metal sheet according to any one of claims 1 to 4, characterized in that.
[Requested item 6]
　Wherein between the plated metal plate and the primer layer, further precoated metal sheet according to any one of claims 1 to 5, characterized in that it has a chemical conversion film.
[Requested item 7]
　The precoated metal sheet according to any one of claims 1 to 6, characterized in that said plated metal plate is a Zn-Al-Mg plated steel sheet.