JPH09122578A - Colored resin-coated metallic sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the gloss of a colored resin-coated metallic sheet by using a metallic sheet with the specular gloss satisfying a specified expression to form a coating film. SOLUTION: The 60 deg. specular gloss G0 of a metallic sheet before a colored resin coating film is formed thereon is allowed to satisfy 40<G0<310. Meanwhile, the surface shape of the uncoated metallic sheet is also an important parameter to improve the gloss. Namely, the surface shape is set so that the center line surface roughness Ra of the metallic sheet and the peak number PPI exceeding the 100×10<-6> inch peak count level on the roughness curve per inch are allowed to satisfy 0.4<Ra <1.8 and 10<PPI<110, respectively. An electrogalvanized steel sheet is used as the metallic sheet before a colored resin coating film is formed thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a colored resin-coated metal sheet used for interior / exterior parts of automobiles and household electric appliances, outer panel materials such as steel furniture, and building materials. Relates to a colored resin-coated metal plate which is beautifully colored and has a good sharpness reflecting the luster of the base metal, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, zinc-based plated metal sheets have been widely used for automobiles, household electric appliances, building materials and the like. As they are, these zinc-based plated metal plates have insufficient corrosion resistance and adhesion to paints, so chemical treatments such as chromate treatment and phosphate treatment have been applied to the plating layer. When high corrosion resistance, chemical resistance, designability, etc. are required, a resin film is often provided on these chemical conversion treatment layers. In particular, in the case of a metal plate used for applications where design is important from the viewpoint of appearance and perfection of color tone as a product, the resin film corresponding to the outermost coating is colored in the color tone required by the user. There must be.

As a method of coloring a resin film, a method of adding a coloring pigment such as an organic pigment or an inorganic pigment to a paint is generally adopted. From the viewpoint of coloring power, the organic pigment is more preferable than the inorganic pigment. It is known that the inorganic pigment is superior in terms of hiding property. Usually, in order to hide the color tone of the base of the metal plate, the paint often contains an inorganic pigment alone or together with an organic pigment, in any case, in order to completely hide the color tone of the substrate, A coating film of 10 g / m ² or more was required.

Further, in order to impart a high degree of corrosion resistance and chemical resistance to the resin film, an organic solvent-based bake-curable paint capable of forming a dense coating film is suitable. The paint is also used for the above, but it is difficult to obtain a stable coating amount due to the evaporation of the organic solvent, a long drying equipment for baking and curing, and a local exhaust equipment for collecting the evaporated organic solvent. However, it is difficult to perform high-speed production on the same line as the plated metal plate manufacturing process. After all, the obtained coated metal plate is very expensive because of the large required amount of coating film adhesion and the problems of these facilities.

As a solution to the above problems, there has been proposed a colored resin-coated steel sheet which can be manufactured at low cost in the plating metal plate manufacturing process. For example, JP-A-5-16292
JP-A No. 2003-242242 discloses a colored steel sheet in which a chromate coating layer is provided on the surface of a zinc-based plated steel sheet, and a colored resin layer having a thickness of 5 μm or less is formed thereon so that the L ^* value is 60 or less.
However, it is known that the color tone of the colored steel plate is determined by the color tone of the base metal plate, the color tone and thickness of the resin film,
It is difficult to obtain a stable color tone even if the colored resin layer has an L ^* value of 60 or less when the thickness of the colored resin film is reduced, because the coloring property and the hiding property of the colored steel sheet are deteriorated. . The L ^* value is an index indicating “lightness” defined by JIS Z 8730, and the L ^* value increases blackness on the (−) side and whiteness on the (+) side. That is, when the color tone of the colored resin layer is black, the L ^* value is 60 or less,
In addition, if the color tone is white, the L ^* value may be 60 or more, which is not an index showing the concealing property of the base metal plate (conversely, gloss). Anxiety remains.

On the other hand, in Japanese Patent Laid-Open No. 31450/1993, resin 1 is prepared after chromate treatment is applied to a zinc-based surface-treated steel sheet.
To 100 parts, as a coloring agent, a titanium white / total coloring pigment ratio of 30 to 100 is used as a coloring pigment of 0.30 to 0.95.
Parts, 20 to 40 parts of colloidal silica as a film reinforcing material is dispersed to form a water-soluble or water-dispersible resin coating layer having a thickness of 1 to 3 μm. A colored coated surface-treated steel sheet is disclosed.

However, in Japanese Patent Laid-Open No. 31450/1993,
The pigment concentration is as high as 30 parts or more in order to improve the underlayer concealing property of the processed part, but the adhesion between the resin coating film and the base metal plate decreases as the pigment concentration added to the resin film increases. There is a problem of doing. It has also been pointed out that when the pigment addition concentration is high, the corrosion resistance which is the original performance of the resin-coated metal plate is deteriorated.

With the recent diversification of uses of colored metal plates,
In many cases, an appearance that does not completely hide the color tone of the base material but takes advantage of the metallic luster of the base material is required. For example, it is used in a portion such as a bottom plate and a back plate of a refrigerator or a washing machine, an FDD component, a cassette chassis, etc. where the product appearance is difficult to see, and an application requiring a metallic luster in design.
Even if it is hard to see, the appearance of the base metal plate is inferior in terms of design.Therefore, not only parts that require metal luster, but also colored metal plates that are beautifully colored while maintaining metal luster are required. ing.

The colored metal plate having both the metallic luster and the design is such that, for example, a yellow resin coating film is formed on the metal plate while utilizing the luster of the base material, and the luster of the base metal plate and the resin coating film The colors are made to act on each other so as to give a golden color that is preferred by users. As a conventional method for obtaining a golden appearance, a coloring method by anodic oxidation of Ti,
Although there is a method such as gloss chromate treatment called UNIQLO or gold plating, the treatment cost is high. Further, in the anodic oxidation or chromate treatment, it is difficult to obtain a stable color tone because the treatment film thickness changes depending on the treatment conditions such as the pH of the treatment liquid and the electrolytic voltage.

Further, in the case of a method of forming a colored resin coating film while making the best use of the luster of a base metal plate (hereinafter sometimes referred to as the original plate), the glossiness of the resin-coated metal plate obtained is such that the glossiness and surface shape of the original plate. It is known to be greatly affected by. When the unevenness of the original plate is large, the resin coating film is formed by reflecting the unevenness, so that the reflected light is scattered and, as a result, the glossiness is lowered. In particular, when the resin coating film contains a colorant for imparting a design property, the scattering of reflected light is more remarkable.

[0011]

Therefore, in the present invention,
To accurately and efficiently identify a metal plate that does not reduce the glossiness after painting with a colored resin and use this metal plate as a base plate to provide a colored resin-coated metal plate with excellent gloss. Listed as an issue.

[0012]

The present invention comprises a coloring pigment.
It is a colored resin coated metal plate with a resin coating film
The 60 ° specular gloss of the metal plate before forming the colored resin coating film.
To G₀ And then G ₀ Where satisfies the following formula (1)
Has the point. 40 <G₀ <310 (1) The metal plate before forming the colored resin coating film has the following formulas (2) to (3).
It is also excellent in gloss because it shows a surface shape that satisfies
Is an important parameter in obtaining a colored resin coated metal plate
is there. 0.4 <Ra <1.8 (2) 10 <PPI <110 (3) where Ra is the center line of the metal plate before the formation of the colored resin coating film.
Surface roughness (μm), PPI is the roughness per inch
100 × 10 in the curve^-6Inch peak count
It shall indicate the number of peaks above the level.

According to the present invention, in order to obtain a colored resin-coated metal sheet with less deterioration in glossiness, the 60 ° specular glossiness of the metal sheet before the formation of the colored resin coating film is G ₀ , and the coated metal sheet after the resin coating film is formed. It is also defined as a preferable condition that G ₁ satisfies the following expression (4) when the 60 ° specular glossiness of is G ₁ . _{G 0> G 1 ≧ 0.5G 0} ... (4) 0.2~ adhered amount of the colored resin coating film at a dry coating weight in terms of
3.0 g / m ² , and the color pigment is 1 to 30 in the dry coating film.
It is also a preferred embodiment of the present invention that it is contained by weight. When a metal plate having a good golden-tone appearance is required, the a value and the b value of the chromaticness index in the Hunter's color difference formula are calculated by the following formula (5).
Is desired to be satisfied. -4 ≦ a value ≦ 6 and 2 ≦ b value ≦ 25 (5)

In the present invention, any metal plate satisfying the above various conditions can be used as the metal plate before the formation of the colored resin coating film, but use of an electrogalvanized steel plate is recommended. At this time, the electrogalvanized steel sheet before forming the colored resin coating film has a surface shape that satisfies the following formula (6): 30 <S <70 (6) where S is the area ratio of the plateau portion. (%), And represents the percentage of the total area of the plateau portion (the portion in which the convex portion of the surface is pressed down and the top portion becomes a plateau) per unit area. Alternatively, the orientation of hexagonal zinc crystals in the galvanized layer of the electrogalvanized steel sheet satisfies the following expression (7),

[0015]

(Equation 2)

In an arbitrary observation region on the surface of the galvanized layer of the electrogalvanized steel sheet, Zn having a length of 5 μm or more
The area of the region in which the single crystal grows with a certain directionality is 70% or less of the total area of the arbitrary observation region. That is, a colored resin-coated metal plate having a beautiful appearance using an electrogalvanized steel plate. Is a preferable condition for obtaining

Incidentally, in manufacturing the above-mentioned colored resin-coated metal plate, a method for manufacturing a colored resin-coated metal plate using a water-dispersible or water-soluble paint containing a coloring pigment is also included in the present invention.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The greatest feature of the present invention is that it is a metal plate coated with a colored resin, but has an excellent surface gloss. In the present invention, when the 60 ° specular gloss of a metal plate (hereinafter sometimes referred to as an original plate) before forming a colored resin coating film is G ₀ , as a metal plate that does not reduce the gloss after coating with a colored resin, In addition, it is necessary to select one in which G ₀ satisfies the following expression (1). 40 <G ₀ <310 (1) Note that G ₀ is a 60 ° specular gloss level defined in JIS Z 8741, and is measured by a gloss meter manufactured by Nippon Denshoku Co., Ltd. in the present invention. .

In order to increase the glossiness after coating with the colored resin, it is desired that the original plate has a high glossiness, but if it is too high, the reflectance in a specific direction becomes high and a mirror-like appearance is obtained. It is not preferable when applied to automobiles, electric appliances, building materials, etc. Therefore, in the present invention, the upper limit of G ₀ is specified to be 310. On the other hand, however, when the gloss of the original plate is too low, the gloss of the colored resin-coated metal plate obtained is inferior. Therefore, the lower limit of G ₀ of the original plate is set to 40.

In the present invention, G _{0 of} the metal plate is represented by the above formula (1).
It has also been found that in order to achieve the above range and to improve the adhesion to the colored resin coating film, one satisfying the following conditions (2) to (3) may be selected. 0.4 <Ra <1.8 (2) 10 <PPI <110 (3) where Ra is the center line surface roughness (μm) of the metal plate before forming the colored resin coating film, and PPI is In the roughness curve per inch, 100 × 10 ⁻⁶ inch (100 μinc
It shall indicate the number of peaks above the peak count level of h).

When Ra is 0.4, the surface of the original plate is too smooth and the adhesion to the colored resin coating film is deteriorated. Also,
The handling flaws at the time of line passing may be conspicuous and the product yield may be reduced, leading to an increase in cost. Therefore, Ra is preferably smaller than 1.8. However, the rougher the surface of the metal plate is, the lower the glossiness is, and the larger the "galling" becomes in the processing with a strict clearance, it is desirable that Ra be smaller than 1.8.

The peak count PPI, which is one of the indicators of surface roughness, is the SAE standard (Social Society of Automotive Technology)
ety of Automobile Engineers) J911-1986 "SU
RFACE TEXTURE MEASUREMENT OF COLD ROLLED SHEET STE
It is defined in "EL" and indicates the number of peaks in a roughness curve per inch that exceeds a certain reference level (peak count level). In the present invention, 100 × 10
^A master plate having a number of peaks exceeding ^-6 inches that satisfies the formula (3), that is, an original plate having a PPI of more than 10 and less than 110 can be preferably used. When the PPI is 10 or less, the above-mentioned inconveniences such as not only a mirror-like appearance but also an excessively smooth surface of the original plate and conspicuous handling flaws occur. Further, when the PPI is 110 or more, scattered light increases and the glossiness decreases, which is not preferable as the original plate.

The glossiness G ₁ of the metal plate after coating with the colored resin is
1 / gloss G ₀ of the metal plate before forming the colored resin coating film
It is preferable that 2 or more (0.5 G ₀ or more), that is, G ₁ satisfies the following expression (4). _{G 0> G 1 ≧ 0.5G 0} ... (4)

If G ₁ <0.5G ₀ in the above formula (4), there is a large difference in appearance between the resin-coated metal plate and the original plate, and it cannot be said that the color tone and gloss of the original plate are reflected and it is good. Does not have a glossy appearance. After the colored resin coating film is formed, light reflection occurs at the interface between the original plate and the resin coating film, so that G ₁ ≧ G
It cannot be ₀ . On the contrary, if G ₁ ≧ G ₀ (G ₀ >)
If it is not G ₁ ), the coating effect of the colored resin is not obtained at all.

In order to satisfy the above formula (4), the amount of resin coating film deposited on the original plate is 0.2 to 3.0 g / in terms of dry coating film weight.
m ² is good. If it is less than 0.2 g / m ² , the coloring effect of the resin coating film on the original plate may be too small.
Further, since the solid content in the coating material decreases, it is difficult to form a coating film uniformly on the surface of the original plate, and it may not be possible to sufficiently exhibit the performances such as corrosion resistance and workability, which are important as a resin-coated metal plate.

On the other hand, if the amount of coating film adhered is too large, the ability to conceal the original plate becomes large, which deviates from the above formula (4). Further, if the amount of coating film adhered exceeds 3.0 g / m ² , it takes time to dry the coating film, the continuous production efficiency deteriorates, and the amount of the pigment-containing resin coating material used increases, which leads to an increase in cost. Only. Further, since the coating film is easily peeled off during press working, the corrosion resistance is inferior, and the peeled coating film may be accumulated on the mold to hinder the press molding. As an upper limit at which such a problem does not occur, in the present invention, the resin coating film deposition amount is 3.0 g / m ²
It is preferable to set the following. From a practical point of view, the more preferable coating amount of the resin coating film is in the range of 0.3 to 2.0 g / m ² .

In addition to the above-mentioned adjustment of the coating film adhesion amount, the adjustment of the pigment concentration in the coating material is also a means preferably adopted for satisfying the above formula (4). In the present invention, it is preferable to adjust the concentration of the color pigment in the paint to be 1 to 30% by weight (based on the solid content of the paint) of the dry coating film. When the concentration of the coloring pigment is less than 1% by weight, the coloring effect of the coating film is small and the purpose of the present invention is not met. Conversely, the higher the pigment concentration, the greater the coloring effect, but the adhesiveness between the resin coating film and the original plate tends to deteriorate, so the upper limit is recommended to be 30% by weight. Further, if there are too many pigments in the coating film, the corrosion resistance, which is the original performance of the resin coating film, may be poor, and the color tone of the coating film may change significantly due to corrosion. The more preferable concentration range of the pigment in the paint is
5-2 to dry coating weight (to solid content of paint)
The range is 0% by weight.

For the colored resin-coated metal plate of the present invention, it is preferable to use a coating material containing a fine particulate coloring pigment having excellent dispersibility in the coating material. By using various pigments together, the color tone of the resin-coated metal plate can be controlled in various ways.

Examples of pigment types for coloring the following respective colors are: red: organic pigments such as insoluble azo (naphthol and anilide) or soluble azo, red iron oxide, cadmium red, red lead Inorganic pigments such as: Yellow: Insoluble azo pigments (naphthol and anilide pigments), soluble azo pigments, quinacridone pigments, etc.
Inorganic pigments such as chrome yellow, cadmium yellow, nickel titanium yellow, yellow tan, strontium chromate, green: organic phthalocyanine pigments, blue: organic phthalocyanine pigments, dark blue, ultramarine blue, cobalt blue, emerald green and other inorganic pigments, black : Organic pigments such as aniline black and carbon black, inorganic pigments such as iron black, white: inorganic pigments such as titanium oxide, calcium carbonate, zinc oxide, barium sulfate, lithopone and lead white. Among the above color pigments, those having the same color but different chemical structures, or two or more color pigments of different colors are mixed at an appropriate mixing ratio to give a gray, brown, or
It can be colored in a desired color such as purple, orange or golden.

The average particle size of the color pigment is 0.05 to 1.0.
μm is preferred. If it is less than 0.05 μm, the coloring effect of the film is small and the design may be poor.
On the other hand, if it is larger than 1.0 μm, the proportion of large-diameter pigment exposed on the surface of the coating film increases as the pigment concentration increases, so the pigment may fall off during sliding of the obtained colored coated metal plate. The color tone may change. Further, if the particle size of the pigment is large, the dispersibility in the paint is poor, and it is difficult to obtain a uniformly colored coating film. A more preferable range of the particle size of the pigment is 0.1 to 0.7 μm.

The material of the base resin in the coating material for forming the colored resin coating film is not particularly limited, and polyethylene, polyurethane, polyester, epoxy, acrylic, etc. can be used. It is also preferable to introduce a functional group into the base resin to improve the adhesion with the color pigment. In addition, since the organic solvent-based coating composition has a bad working environment and requires a facility for recovering a volatile solvent, in the present invention, it is recommended to use a water-dispersible coating composition or a water-soluble resin solution containing a color pigment. .

In adjusting the paint for forming a colored resin coating film, a partial cross-linking agent, a diluting solvent, an anti-skinning agent, a leveling agent, and a decoloring agent are used as long as the appearance and color tone of the colored resin-coated metal sheet of the present invention are not significantly changed. Foaming agent, penetrating agent, film forming aid,
It is possible to further enhance the coating film performance by appropriately adding various additives such as a thickener and a lubricant, and finely divided silica, colloidal silica, silane coupling agent and the like for improving adhesion and corrosion resistance.

As described above, the present invention provides a colored resin-coated metal plate having excellent gloss.
In particular, we also succeeded in providing a colored resin-coated metal plate having a chromate-treated film-like color tone that is preferred by users.
That is, the a and b values of the chromatinex index of the Hunter's color difference formula defined by JIS Z 8730 are:
When the following expression (5) is satisfied, the resin-coated metal plate of the present invention exhibits a chromate-treated film-like golden color. -4 ≦ a value ≦ 6 and 2 ≦ b value ≦ 25 (5)

Here, the a value and the b value are numerical values of hues representing color tones defined by the International Lighting Commission and approved by JIS, and the a value is greenish on the (-) side,
Redness increases on the (+) side, b value is bluish on the (-) side,
It indicates that the yellowness increases on the (+) side. A yellow pigment may be added alone to the coating material in order to adjust the range of the a value and the b value, but it is more preferable to mix two or more kinds of the yellow pigment and the red pigment because the hue can be easily adjusted.

The metal plate used as the original plate before resin coating in the present invention is not particularly limited, and various alloy steel plates such as mild steel and stainless steel plates as well as Al.Al.
Alloy plate, Cu / Cu alloy plate, Ti / Ti alloy plate, or Zn / Zn alloy plating, Al /
Various plated metal plates with Al alloy plating, Cu plating, Ni plating, Cr plating, etc., phosphate treatment,
A wide range of metal plates that have undergone chemical conversion treatment such as chromate treatment can be used.

Among them, the electrogalvanized steel sheet has corrosion resistance,
It is preferable for obtaining a colored resin-coated metal sheet having excellent gloss because it has excellent coating film adhesion during processing, an appearance, and the like, and also has excellent surface appearance and gloss. This is because if the original plate has excellent gloss, naturally the gloss after coating with the colored resin also becomes excellent. And, it was found that the surface shape of the electrogalvanized steel sheet and the orientation of the crystals in the electrogalvanized layer affect the surface gloss, so in the present invention, the electrogalvanized steel sheet having the following features. It is recommended to select as the original plate.

First, as the surface shape of the original galvanized steel sheet, it is preferable that the plateau area ratio S satisfies the following expression (6). 30 <S <70 (6) However, S is the area ratio (%) of the plateau part, and is the total of the plateau part (the part where the surface convex part is pressed down and the top is plateau-shaped) per unit area. It shall indicate the percentage of area.

The S of the original plate, that is, the area ratio (%) of the plateau, is the total area of the plateau (a part where the surface convex portion is pressed down and the top is plateau-shaped) per unit area to the total surface area. The plateau portion is a portion which is observed as a plateau when the surface of the original plate is observed with an SEM (scanning electron microscope) at a magnification of about 100 times. The presence of this plateau portion has the effect of suppressing the scattering of reflected light and increasing the glossiness, so the plateau area ratio (%) S is 3
It is preferably more than 0%. S is 110%
In the above case, the surface is shimmering and the appearance is unfavorable. Therefore, it is recommended that S be smaller than 110%.
Further, an electrogalvanized steel sheet in which the orientation of hexagonal Zn crystals in the electrogalvanized layer satisfies the following expression (7) can also be preferably used.

[0039]

(Equation 3)

It is known that Zn crystals have a hexagonal close-packed crystal structure. Most of the Zn crystals are oriented in the (002) plane or the (103) plane, of which (103)
The plating layer in the portion strongly oriented on the surface has a smaller amount of specularly reflected rays with respect to the incident rays and is inferior in surface gloss as compared with the portion oriented in the (002) plane. Therefore, it is preferable for the colored resin-coated metal plate of the present invention to satisfy the above conditions, that is, to have the zinc plating layer strongly oriented on the (002) plane.

The respective orientation indexes in the above equation are obtained by comparing the orientation strength of each Miller index plane [(002) plane and (103) plane] with the orientation of a powder pattern having no anisotropy. It is a numerical value. Specifically, the diffraction intensity I (hkl) of the (hkl) plane is 2θ = 30 to 8 by the X-ray diffraction method.
The relative intensity IF (hkl) of I (hkl) with respect to the total peak ΣI (hkl) [ie I
(Hkl) / ΣI (hkl)], and
Relative intensity of powder pattern obtained by card I
Dividing by FR (hkl) gives the orientation index of the (hkl) plane. When the values obtained by calculating the orientation indices of the (002) plane and the (103) plane and substituting them in the above equation (2) are 2.0 or more, the (103) plane with low gloss is relatively small and the overall quality is good. An electrogalvanized layer that gives a bright gloss is obtained.
The upper limit is not particularly limited, but 15 is recommended in consideration of workability. If it exceeds 15, flaking may easily occur during processing. Regarding the above phenomenon related to electrogalvanized steel sheet, Japanese Patent Application No.
It is described in detail in No. 2939.

On the other hand, in any observation area on the surface of the galvanized layer of the electrogalvanized steel sheet, Zn having a length of 5 μm or more
A metal plate in which the area of a region in which a single crystal grows with a certain directionality is 70% or less of the total area of the arbitrary observation region is also preferably used in the present invention.

Here, the "region in which the Zn single crystal grows with a certain directionality" means that the zinc-plated single crystal on the surface of the electrogalvanized layer does not grow randomly but is constant. Is in a state of being aligned and growing (epitaxial growth state). There is a non-uniform state due to fine unevenness of the steel sheet before electrogalvanizing and other influences, resulting in a non-uniform crystal morphology, but if the area in which the galvanized single crystals are aligned and grown is a large area, it is non-uniform. Even if there are few regions with different crystal morphology, the difference in color tone is noticeable. If such an original plate is used, the image clarity of the resin-coated metal plate will be poor.

From this, in any observation area on the surface of the plating layer of the electrogalvanized steel sheet, "the area of the area where the Zn single crystal having a length of 5 μm or more grows in a certain direction is the total area of the observation area". 70% or less "
It was set as a preferable requirement. At this time, if the Zn single crystal is too small, even if the Zn single crystal grows in an array, no visible image defect does not occur on the surface of the resin-coated metal plate.
The length of the Zn single crystal included in the above setting requirements is 5 μm or more. The original plate satisfying the above requirements has a uniform color tone and sharpness, so that it gives a colored resin-coated metal plate having a beautiful appearance when applied to the present invention.

Next, the method for producing the colored resin-coated metal plate of the present invention will be described. The resin-coated metal plate is a paint containing the resin component and a color pigment (preferably a water-dispersed paint).
Can be applied to the surface of the original plate by a known coating method, and then dried to manufacture. Although the coating method is not particularly limited, for example, the surface of the long metal belt, which has been cleaned and subjected to coating pretreatment (for example, phosphate treatment, chromate treatment, etc.) as needed, is applied by a roll coater method, a spray method, Examples thereof include a method in which a coating material is applied using a curtain flow coater method or the like and the material is passed through a hot air drying oven to be dried. The roll coater method is practically preferable in consideration of the uniformity of the coating film thickness, the treatment cost, the coating efficiency, and the like. The colored resin coating film may be formed on only one side or both sides of the original plate depending on the application. The drying temperature of the coating film is preferably equal to or lower than the heat resistant temperature of the color pigment so that the color pigment to be added is not denatured and the color tone is not changed.

The metal plate to which the resin coating is applied may be subjected to a phosphate treatment or a chromate treatment as a pretreatment for coating in order to improve the adhesion to the resin coating film or the corrosion resistance. However, regarding the chromate-treated material, it is preferable to suppress the Cr adhesion amount during the chromate treatment to 35 mg / m ² or less from the viewpoint of the chromium elution property during the use of the resin-coated metal plate. Within this range, the resin-coated metal plate of the present invention,
Chromium elution from the underlying chromate treatment layer can be suppressed. Further, the conventional chromate-treated material has a tendency that the water-resistant adhesion of the top coating film provided as necessary tends to decrease in a wet environment with the elution of hexavalent chromium, but with the resin-coated metal sheet of the present invention, Since the elution is suppressed, the water-resistant adhesion of the top coating film does not deteriorate.

[0047]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which do not limit the present invention.
Modifications and alterations that do not depart from the spirit described below are all included in the technical scope of the present invention.

Example 1 Using a work roll having a different surface roughness, cold rolled low carbon Al killed steel was subjected to degreasing, cleaning and annealing to obtain several kinds of base steel sheets having different surface roughness. . Further, these base steel sheets were subjected to electrogalvanizing or hot dip galvanizing treatment in the steps shown below.

(1) Electrogalvanizing Treatment: Degreasing of Alkali Scrubber It was carried out at 60 ° C. using a 3% sodium orthosilicate aqueous solution. : Electrolytic degreasing → washing with water Using a 3% sodium orthosilicate aqueous solution, it was carried out at 60 ° C. and 20 A / dm ² . Then, it was washed with water. : Pickling → Washing 5% sulfuric acid aqueous solution was used at 60 ° C., followed by washing with water. : Electrogalvanizing → Washing with water Electrogalvanizing was performed under the following conditions, and then washing with water. Plating solution _{composition; ZnSO 4 · 7H 2 O ...} 300~400g / l NaSO 4 ... 50~100g / l H 2 SO 4 ... 25~ 35g / l current density; 50-200 / dm ² plating solution temperature; 60 ° C. Plating Liquid flow rate: 0.8 to 2.4 m / sec Plating coverage: 5 to 50 g / m ²

(2) Hot dip galvanizing treatment is the same as above. Reduction: Reduction was performed at 800 ° C. for 30 seconds in a mixed gas of N ₂ —H ₂ (1: 1). : Hot dip galvanizing treatment Hot dip galvanizing was performed under the following conditions. Plating bath composition; Zn-0.13% Al Plating bath temperature; 460 ° C. Penetration plate temperature; 500 ° C. Immersion time; 2 seconds Plating adhesion amount: 30 to 300 g / m ²

The steel sheet after electroplating or hot dip coating is subjected to SKP (skin pass) rolling to adjust the glossiness, and then chromate treatment (Cr deposition amount: 20 mg / m).
² ) was performed to obtain a resin-coated original plate. Using a water-dispersed polyethylene-based emulsion as a base resin that constitutes the coating film, organic pigments (average particle diameter 0.2 to 0.5 μm) having various color tones shown in Table 1 are contained in a solid content of 10% by weight. Addition was performed to prepare color pigment-containing water-dispersed paints A to D.

[0052]

[Table 1]

Coating materials A to D shown in Table 1 were applied to various original plates by a roll coater so as to have a predetermined adhesion amount, and the coating film was dried while being transferred in a hot air drying oven. The performance of the obtained resin coated plate was evaluated by the following test methods and shown in Tables 2 and 3.

[Glossiness] A 60 ° specular glossiness (G60) defined in JIS Z 8741 was measured using a gloss meter manufactured by Nippon Denshoku Co., Ltd. G of 60 ° specular gloss of the original plate
_0, and the glossiness after the resin coating and G _1, was calculated G ₁ / G ₀ as an index representing the gloss change before and after painting.

[Appearance] The appearance of the colored resin-coated metal plate was visually evaluated. The evaluation criteria are as follows. <Evaluation Criteria for Appearance> Excellent: The appearance is good reflecting the gloss of the original plate. × Inferior: Low gloss. Alternatively, the specular gloss is too high and the appearance is poor.

[0056]

[Table 2]

[0057]

[Table 3]

From Tables 2 and 3, it is clear that the examples satisfying the formula (1): 40 <G ₀ <310 defined in the present invention show excellent appearance. However, when the original plate has a glossiness G ₀ of 40 or less, the glossiness after resin coating is low, and conversely G ₀
In the cases where the ratio was more than 310, the glossiness was too high, and the desired appearance was not obtained in any case.

Example 2 In the same manner as in Example 1, using a galvanized steel sheet after chromate treatment having different surface roughness as the original plate, a colored resin coated steel sheet with the coating materials A and C shown in Table 1 was produced. Example 1 of the original plate and the obtained resin-coated plate
The glossiness, the change in glossiness, and the appearance were evaluated in the same manner as in, and the following evaluations were also performed.

[Surface Roughness] The surface roughness of the original plate was measured using a surface roughness profiler manufactured by Tokyo Seimitsu Co., Ltd.
The center line average roughness Ra was determined according to B0601. Also, as the peak count PPI, in the roughness curve,
The number of peaks exceeding the peak count level of 100 × 10 ⁻⁶ inches was counted.

[Ratio of Plateau Area] The surface of the original plate was observed with a scanning electron microscope manufactured by JEOL Ltd. at a magnification of 100, and a total field of view including the plateau portion was measured by a Carl-Zeiss image analyzer. The area of the place was analyzed. The plateau area ratio (%) was an average value of 10 fields of view obtained by dividing the area of the plateau-like portion on the original plate by the total area of observation.

[0062]

[Table 4]

[0063]

[Table 5]

As is clear from Tables 4 and 5, Ra, P
Each of the experimental examples in which the PI and the plateau area ratio are within the preferred range of the present invention has a good appearance. However, Ra, P
In the examples using the original plate in which either the PI or the plateau area ratio does not fall within the preferred range of the present invention, the glossiness was inferior or the glossiness was too high, resulting in a mirror-like poor appearance.

Example 3 In the same manner as in Example 1, a chromate-treated electrogalvanized steel sheet having a different surface roughness was used as an original plate, and a colored resin-coated steel sheet according to coating materials A and B shown in Table 1 was used as a coating film. It was produced by changing the amount of adhesion. With respect to the original plate and the obtained resin-coated plate, the glossiness and the change in glossiness were measured in the same manner as in Example 1.
The appearance was evaluated, and the following evaluations were also performed, and are also shown in Table 6.

[Color Tone (Colorability)] Using a color difference meter manufactured by Nippon Denshoku Co., Ltd., the chromaticness index: a value and b value of the Hunter color difference formula defined by JIS Z 8730 were measured, and resin coating was performed. Hue of metal plate C ₁ = (a ² + b ² )
^1/2 was calculated. Similarly, the hue C _{0 of the} original plate was obtained, the hue difference ΔC = C ₁ -C ₀ was calculated, and the colorability was evaluated according to the following criteria. <Evaluation method of colorability> ◎ Excellent: Hue difference 8 or more ○ Good: 〃 2 or more and less than 8 × Poor: Less than 〃 2

[Corrosion resistance (white rust resistance)] Corrosion resistance of the resin-coated metal plate is 5% by weight specified in JIS Z2371.
It measured according to the salt spray test. The white rust 1% generation time by electro-pure zinc plating of the lower layer of the resin coating film was evaluated according to the following criteria. <Evaluation criteria of white rust resistance> ◎ Excellent: White rust occurs at 240 hr or more ○ Good: White rust occurs at 120 hr or more and less than 240 hr △ Slightly inferior: White rust occurs at 48 hr or more and less than 120 hr × Inferior: White rust occurs at less than 48 hr

[0068]

[Table 6]

The experimental examples in which the change in glossiness G ₁ / G ₀ was 0.5 or more were all excellent in appearance, colorability and corrosion resistance. These are because the concentration of the color pigment and the amount of the coating film adhered to each other were within the preferable ranges. On the other hand, in the case where the change in glossiness was less than 0.5, the amount of coating film adhered was too large, so that the color tone of the original plate could not be reflected and the appearance was inferior. Further, when the amount of coating film adhered is small, the glossiness is large, but the coloring property is poor and the corrosion resistance is also poor, so that it is unsuitable for use in the colored resin-coated metal plate of the present invention.

Example 4 An Al-killed cold-rolled steel sheet was electrogalvanized in the same manner as in Example 1 except that the electrogalvanizing conditions in Example 1 were changed as follows. Plating solution _{composition; ZnSO 4 · 7H 2 O ...} 300~400g / l NaSO 4 ... 50~100g / l H 2 SO 4 ... 25~ 35g / l current density; 50-200 / dm ² plating solution temperature; 60 ° C. Plating Liquid flow rate: 0.8 to 2.4 m / sec Plating coverage: 5 to 50 g / m ²

In Examples 5 and 6 which will be described later, a zinc single crystal having a length of 5 μm or more with respect to the entire area of an arbitrary observation region on the surface of the galvanized layer of the electrogalvanized steel sheet grows with a certain directionality. The ratio of the area of the region (hereinafter referred to as the epitaxial growth rate) is 70% or less, and the orientation index of the hexagonal zinc crystal in the zinc plating layer to the (002) plane is less than that of the (103) plane. An appropriate amount of quaternary ammonium salt was added to the pickling bath and the electrogalvanizing conditions were changed within the above range so that the amount was doubled or more.

The obtained electrogalvanized steel sheet was subjected to chromate treatment (Cr adhesion amount: 20 mg / m) to prepare a resin coating original plate. The original plate before coating had a 60 ° specular gloss (measured by the following method; hereinafter, G ₀ ) was 60.
The epitaxial growth rate was 0.51.

The coating solutions E to G shown in Table 7 were coated with a roll coater to have a predetermined film thickness, and then the coating film was dried while being transferred in a hot air drying furnace. The color pigment-containing water-dispersible coatings E to G in Table 7 were produced in the same manner as in Example 1. The various resin coated steel sheets obtained were subjected to various performance evaluation tests, and the results are shown in Table 8. The color tone, appearance, and change in glossiness were measured as described above, and the Cr elution resistance was evaluated by the following method.

[Cr elution resistance] Cr elution resistance is 70 m
The measurement was performed on 50 m × 70 mm colored resin-coated steel sheets as follows. <Test Method> The Cr deposition amount on the front and back of the test material is measured by a fluorescent X-ray method, and the average Cr deposition amount (mg / m ² ) on the front and back of the test material is obtained. The test material is immersed in 500 ml of an aqueous NaOH solution having a pH of 11 at 80 ° C., and ultrasonic waves are applied for 2 minutes. Immerse in 500 ml of pure water at 80 ° C. and apply ultrasonic waves for 2 minutes. This is repeated twice. To the Cr elution solution (500 ml of NaOH aqueous solution + 1000 ml of water) obtained in and, 10 ml of hydrochloric acid was added,
This is heated and concentrated to 100 ml. Hexavalent Cr was extracted from the heated and concentrated solution using methyl isobutyl ketone, concentrated, and then concentrated by atomic absorption spectrophotometry, and the amount of eluted Cr per unit test area (mg)
/ M ² ). The amount of eluted Cr obtained in step 1 was divided by the average amount of deposited Cr determined in to obtain the Cr elution rate (%).

The Cr elution resistance evaluation criteria are as follows. <Cr elution resistance> ◎ Excellent: Cr elution rate of less than 0.01% ○ Good: 〃 0.01% or more and less than 0.1% × Inferior: 〃 0.1% or more

[0076]

[Table 7]

[0077]

[Table 8]

The experimental examples in which the a value and the b value were within the preferred range specified in the present invention reflected the color tone of the chromate treatment and exhibited a golden color. It can also be seen that it has excellent Cr elution resistance. On the other hand, when the a value and the b value were out of the preferable ranges, the chromate-treated appearance was not exhibited or the Cr elution resistance was poor.

Example 5 When an electrogalvanized steel sheet was produced in the same manner as in Example 4, an appropriate amount of quaternary ammonium salt was added to the pickling bath in order to change the epitaxial growth rate, and electrogalvanizing conditions were applied. Was appropriately changed within the above range. The coated steel sheets obtained by using the coating materials H and I shown in Table 9 were resin-coated. Table 10 summarizes the evaluations of gloss change, epitaxial growth rate, and image clarity. The evaluation criteria for clearness are as follows. ◎: Excellent image clarity ○: Good 〃 ×: Inferior to 〃

[0080]

[Table 9]

[0081]

[Table 10]

In an example using an electrogalvanized steel sheet having an epitaxial growth rate within the preferred range of the present invention, a resin coated plate having excellent image clarity was obtained. However, in an example using a steel plate out of this preferable range, the image clarity is inferior.

Example 6 When producing an electrogalvanized steel sheet in the same manner as in Example 4, (002) hexagonal zinc crystals in the galvanized layer were produced.
In order to change the orientation to the plane relative to the (103) plane, an appropriate amount of quaternary ammonium salt was added to the pickling bath, and the electrogalvanizing conditions were appropriately changed within the above range. After that, resin coating was performed using the same paint as in Example 5, and the plating orientation index, gloss change, and appearance (reflection of original plate color tone) of each sample were evaluated, and shown in Table 11.

[0084]

[Table 11]

The orientation of the zinc crystal in the (002) plane is (1
It can be seen that in the preferred experimental example of the present invention in which the surface area is at least twice as large as that of the (03) surface, a resin-coated plate having an excellent appearance is obtained as compared with the experimental example that is not so.

[0086]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, it can be manufactured at a low cost and with simple equipment, and has an excellent surface reflecting the glossiness and color tone of the original plate before coating with a resin coating film. A colored resin-coated metal plate having gloss and appearance and a method for manufacturing the same can be provided.

Claims (10)

[Claims] 1. A colored resin-coated metal plate on which a resin coating film containing a color pigment is formed, where G ₀ is the 60 ° specular gloss of the metal plate before the formation of the colored resin coating film. A colored resin-coated metal plate, wherein ₀ satisfies the following formula (1). 40 <G ₀ <310 (1) 2. The colored resin-coated metal plate according to claim 1, wherein the metal plate before formation of the colored resin coating film has a surface shape that satisfies the following formulas (2) and (3). 0.4 <Ra <1.8 (2) 10 <PPI <110 (3) where Ra is the center line surface roughness (μm) of the metal plate before forming the colored resin coating film, and PPI is The roughness curve per inch shall indicate the number of peaks above the peak count level of 100 × 10 ⁻⁶ inches. 3. A 60 ° specular gloss of a metal plate before forming a colored resin coating film is G ₀ , and a 60 ° of a coated metal plate after forming a resin coating film is 60 °.
The colored resin-coated metal sheet according to claim 1 or 2, wherein G ₁ satisfies the following expression (4) when the specular gloss is G ₁ . _{G 0> G 1 ≧ 0.5G 0} ... (4) 4. The coating amount of the colored resin coating film is 0.2 to 3.0 g / m ² in terms of dry coating film weight, and the coloring pigment is contained in the dry coating film in an amount of 1 to 30% by weight. Claim 1
3. The colored resin-coated metal plate according to any one of 3 above. 5. The colored resin-coated metal according to any one of claims 1 to 4, wherein the a and b values of the chromaticness index in the Hunter color difference formula have a golden color tone that satisfies the following formula (5). Board. -4 ≦ a value ≦ 6 and 2 ≦ b value ≦ 25 (5) 6. The colored resin-coated metal plate according to claim 1, wherein the metal plate before forming the colored resin coating film is an electrogalvanized steel plate. 7. The colored resin-coated metal sheet according to claim 6, wherein the electrogalvanized steel sheet before the formation of the colored resin coating film has a surface shape that satisfies the following formula (6). 30 <S <70 (6) However, S is the area ratio (%) of the plateau part, and the total of the plateau part (the part where the surface convex part is pressed down and the top is plateau-shaped) per unit area. It shall indicate the percentage of area. 8. The colored resin-coated metal sheet according to claim 6, wherein the orientation of hexagonal zinc crystals in the galvanized layer of the electrogalvanized steel sheet satisfies the following expression (7). (Equation 1) 9. The area of a region where a Zn single crystal having a length of 5 μm or more grows in a certain direction in an arbitrary observation region on the surface of a galvanized layer of an electrogalvanized steel sheet,
The colored resin-coated metal plate according to any one of claims 6 to 8, which is 70% or less of the total area of the arbitrary observation region. 10. A colored resin-coated metal plate characterized by using a water-dispersible or water-soluble paint containing a colored pigment in producing the colored resin-coated metal plate according to any one of claims 1 to 9. Manufacturing method.