TWI617636B - Precoated metal plate - Google Patents

Abstract

A precoated metal plate comprising: a metal plate and a coating film, the coating film being disposed on at least one surface of the metal plate and having a film thickness of 5 to 30 μm, and containing a bright pigment and a white pigment, the white pigment average particle a diameter of 200 to 400 nm and a content of 0.5 to 4.0% by mass; the white pigment is at least one selected from the group consisting of titanium oxide, zinc oxide, barium sulfate, basic carbonate, and cerium oxide; The content of the bright pigment in the coating film is A in mass%, and when the white pigment content is B in mass%, the value of B/A is 0.03 to 0.27.

Description

Pre-coated metal sheet

FIELD OF THE INVENTION This invention relates to a precoated metal sheet. The case is based on Japanese Patent Application No. 2016-56852, which was filed on March 22, 2016 in Japan, and its contents are hereby incorporated by reference.

BACKGROUND OF THE INVENTION Metal sheets used in the field of home appliances, building materials, and automobiles have been painted after processing. On the other hand, in recent years, there has been a case where a surface of a metal plate is coated with a coating film (coloring coating film) which has been previously colored, and it is processed in a state where the coating film has been coated. Therefore, a metal plate which is to be coated after processing is referred to as a post-coated metal plate, and a metal plate which has been processed in a state in which the colored coating film has been coated is referred to as a pre-coated metal plate. In recent years, reflecting the improvement in interior preference, etc., advanced design is sought for pre-coated metal sheets, and the design of metal coating on the surface of pre-coated metal sheets is frequently used. Consumers have a variety of requirements for coloring, and one is a metal coating with a small difference in hue and gloss due to different line-of-sight directions.

Further, there are cases where the precoated metal sheet subjected to metal coating is simply referred to as a precoated metal sheet, and there is a case where it is referred to as a metal precoated metal sheet. Similarly, there are cases where the post-coated metal sheet subjected to the metal coating is referred to simply as a post-coated metal sheet, and there is a case where it is referred to as a metal-coated metal sheet. In addition, a change in color tone and brightness depending on the direction of the line of sight may be referred to as flop (Flip-Flop property). The large flop is that the hue and the brilliance vary greatly depending on the direction of the line of sight. When the flop is small, the hue and the brilliance are hardly changed depending on the direction of the line of sight.

The related art of metal pre-coated metal sheets is almost always a problem in obtaining a metallic coating film having a strong metallic feeling. For example, in Patent Document 1, a thin aluminum sheet is oriented parallel to the coated surface, and an aqueous dispersion of a thin aluminum sheet is coated on the coated surface of the uncured base paint to form a whiteness and a metallic luster. A coating film that is excellent and has a large flop. Patent Documents 2 and 3 disclose that scaly graphite pigment or interference pearl mica is added to a bright pigment, that is, a scaly aluminum pigment or a high aspect ratio aluminum powder, to produce a flop. The metal coating film or the technique of using a thermoplastic resin composition for a molded article having a metallic feeling.

Patent Document 4 discloses a metal coating composition excellent in substrate shielding property, which suppresses a black color tone and exhibits a pearly color opaque feeling and an iridescent sensation, and the metal coating composition is a titanium dioxide pigment, a scaly aluminum pigment carrying a pigment, A coloring pigment other than titanium dioxide, a pearlescent pigment, and a resin for forming a coating film are used as a constituent component. Patent Document 5 discloses a method for preparing a precoated metal having a glossy metallic finish, which is a method of coating an organic solvent type coating on a metal plate via a primer coating film or without a primer coating film. The organic solvent-based coating material comprises: mica-like iron oxide powder containing 60% by weight or more of α-iron oxide, a resin for forming a coating film, and a coloring pigment.

Patent Document 6 discloses a glittering paint composition characterized by containing a vehicle liquid, a thin aluminum oxide sheet pigment (A) coated with a metal oxide, and a thin aluminum sheet pigment or a fine particle titanium dioxide pigment (B-1), and It is shielded. Patent Document 7 discloses a glittering paint composition comprising (1) a thin aluminum flake pigment, (2) an interference type mica pigment having a dark portion region, and (3) in addition to the interference type mica pigment having a dark portion region of the above (2) Interfering bright pigment, and (4) vehicle.

Patent Document 8 discloses a coating composition which can form a coating film excellent in chemical resistance and weather resistance, and the coating composition contains a polyester resin component (A), a melamine resin component (B), and a bright pigment component (C); The polyester resin component (A) contains 50 to 100% by mass of a fatty acid-modified polyester resin (A1) having a number average molecular weight of 5,000 to 30,000, a hydroxyl value of 5 to 100 mgKOH/g, and an oil content of 3 to 30%. The melamine resin component (B) contains 50 to 100% by mass of a butyl etherified melamine resin (B1). Patent Document 9 discloses a solvent type containing a urea-modified acrylic resin (A), an urethane-modified polyester resin (B), a hardener (C), a bright pigment (D), and inorganic fine particles (E). When the metal base paint composition is applied by the coating method using the two-coating method, the color change of the metal base coating film and the transparent coating film is not changed, and the transparency is excellent and fine. A coating film with a bright sensation and strong flop.

Patent Document 10 discloses a chromate-free coated metal sheet having a coating film α (film thickness: 1.5 to 10 μm) on at least one side of a metal plate and having a metallic appearance, and the coating film α is an organic resin A. The film-forming component contains a flaky aluminum pigment C whose surface has been deactivated.

CITATION LIST Patent Literature Patent Literature 1: JP-A-2000-000514, JP-A-2000-271536, JP-A No. 2000-271536, JP-A No. 2000-319521, JP-A No. 2000-319521, Patent Document 4: Japanese Patent Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. 2000-86945. Patent Document No. JP-A No. 2000-86945. Japanese Patent Laid-Open Publication No. Hei. No. Hei. No. Hei. No. Hei. No. 2005-220289. Patent Document 10: International Patent Publication No. WO2013/065354

SUMMARY OF THE INVENTION Problems to be Solved by the Invention In the case of coating a metal plate with a metal, it is necessary to have a sufficient metallic feeling in a corner portion where the coating is easily thinned, and the film thickness of the coating film must be 30, including the corner portion. ~100μm. The drying time after coating must be the time corresponding to the film thickness of the coating film.

On the other hand, metal pre-coated metal sheets (especially metal pre-coated steel sheets) are manufactured on a continuous manufacturing line, and the length of the heat-drying line after coating is limited, and drying must be completed in a short time. Therefore, the film thickness of the coating film is set to 3 to 30 μm, which is relatively thin compared with the thickness of the coating film of the metal-coated metal plate. Further, when the coating film having a large thickness is rapidly dried in a short period of time, the solvent in the coating film is rapidly evaporating and evaporating, and a large amount of defects called bubbles are generated in the coating film, resulting in metal pretreatment. The appearance of the coated metal sheet is deteriorated.

The coating film of the metal pre-coated metal plate is strongly thinned, and the flaky (scaly) bright pigment is strongly oriented, and the bright pigment is disposed in a state in which the flat surface of the bright pigment is arranged in parallel with the surface of the coating film. As a result, the appearance of the metal precoated metal sheet tends to be strong when viewed from a certain direction, and the metallic feeling is weak when viewed from other directions (that is, the flop becomes stronger).

Although the metal precoated metal sheet has the appearance as described above, in Patent Documents 1 to 10, the purpose thereof is to obtain a metallic feeling of the metal precoated metal sheet, or to have a strong flop. Metallic pre-coated metal sheets. That is, there is almost no conventional technique of pre-coating a metal plate of a metal having a small change in hue and glitter due to a difference in line of sight (i.e., having a weak flop).

The present invention has been made in view of the above circumstances, and an object thereof is to provide a precoated metal sheet having a small change in hue and glitter due to a difference in line of sight direction, that is, a precoated metal sheet having a weak flop (metal precoating) Metal plate).

Means for Solving the Problems In order to solve the above problems, the present invention has attained the following means.

(1) A precoated metal sheet according to an aspect of the present invention includes: a metal plate and a coating film which is provided on at least one surface of the metal plate and has a film thickness of 5 to 30 μm and contains a bright pigment and a white pigment having an average particle diameter of 200 to 400 nm and a content of 0.5 to 4.0% by mass; the white pigment is selected from the group consisting of titanium oxide, zinc oxide, barium sulfate, basic carbonate, and cerium oxide. In addition, at least one of the above-mentioned bright pigment content in the coating film is A in mass%, and when the white pigment content is B in mass%, the value of B/A is 0.03 to 0.27.

(2) The precoated metal sheet according to the above (1), wherein the white pigment has an average particle diameter of 250 to 350 nm.

(3) In the precoated metal sheet according to the above (1) or (2), the bright pigment may be a thin aluminum sheet.

(4) In the precoated metal sheet according to any one of the above items (1) to (3), the value of the B/A may be 0.05 to 0.20.

(5) In the precoated metal sheet according to any one of the above items (1) to (4), when the light is incident on the surface at an incident angle of 45°, and the light is regularly reflected. When the angle of incidence is 0° and the incident position of the light is 90°, the brightness of 15°, that is, the brightness of L15 and 110°, that is, L110, L15 and L110, which is the difference between L15 and L110, is measured by a multi-angle spectrophotometer. It can also be below 70.

(6) In the precoated metal sheet according to any one of the above aspects (1) to (5), the surface of the coating film may further have a clear coating film.

Advantageous Effects of Invention According to the above aspect, it is possible to provide a precoated metal sheet having a small change in hue and glitter due to a difference in line of sight direction.

MODE FOR CARRYING OUT THE INVENTION First, the description of the background of the present invention will be described. In order to solve the above problems, the inventors of the present invention first investigated the difference in properties of a coating film such as a post-coated metal sheet and a pre-coated metal sheet. The investigation found that in the post-coated metal sheet, the film thickness of the coating film is relatively large compared to the thickness of the bright pigment, so that the bright pigment has a high degree of directionality in the coating film, and after the incident, Light coated with metal sheets tends to diffusely reflect.

On the other hand, the present inventors have understood the following matters regarding the pre-coated metal sheets. That is, the film thickness of the coating film is relatively small compared to the thickness of the bright pigment, so that the flat surface of the bright pigment is oriented parallel to the surface of the coating film in the coating film. As a result, most of the light incident on the precoated metal sheet is regularly reflected. Therefore, the difference in hue and glitter due to the difference in the direction of the line of sight becomes large (that is, the flop increases).

The present inventors have found that in order to reduce flop in a precoated metal sheet, it has been found that the flop can be reduced by mixing a fine white pigment in an appropriate amount in the coating film, and the present invention has been completed.

Next, the inventors of the present invention investigated a metal plate, a precoated metal plate of the prior art, and a precoated metal plate of the present embodiment in accordance with a conventional technique, and investigated the reason why the flop is different.

Fig. 1 is a view showing the principle of color tone measurement by a polygon spectrophotometer. 1 is a view showing a case where the incident surface (coating surface) is irradiated with incident light rays in a direction obliquely upward 45° from the left side, and the direction corresponding to the right oblique 45° of the regular reflection is used as a reference angle (0°) (ie, The light incident position is set to 90°), and the light receiver is disposed on the incident light side in the directions of 15°, 25°, 45° (vertical upper), 75°, and 110°, and the brightness L is measured. .

In general, human visual performance can be expressed in Lab (sometimes expressed as L*a*b) space, where a represents the red direction, -a represents the green direction, b represents the yellow direction, and -b represents the blue direction. , L indicates the brightness (brightness). The present inventors have understood that among the above indexes, the difference in flop with respect to the metal coating film is mainly caused by the difference in the L value indicating the brightness. That is, the present inventors have understood that when the difference in L value is large due to the difference in angle, the flop is large, and when the difference in L value is small due to the difference in angle, the flop is small.

The present inventors have arranged the photoreceiver at each angle and measured the L value, and as a result, it has been found that as long as the difference ΔL between the L value at 15° and the L value at 110° is 70 or less, even if it is pre-coated The metal plate can still achieve flop similar to the post-coated metal plate.

Fig. 2A is a schematic view showing the cross-sectional structure of a coated metal plate after the prior art. Fig. 2B is a schematic view showing the cross-sectional structure of a precoated metal sheet of the prior art. Fig. 2C is a schematic view showing the cross-sectional structure of the precoated metal sheet of the embodiment. As shown in FIG. 2A, the post-coated metal sheet of the prior art has a coating film thickness of 30 to 100 μm which is relatively thick, so that the directivity of the bright pigment 5 in the coating film is small, that is, the bright pigment 5 is oriented to various directions. The direction exists. Light incident from the upper left obliquely is reflected on the flat surface of the bright pigment 5 in various directions, and as a result, the reflected light advances in various directions. Therefore, the surface of the metal plate after the back coating is small in flop.

As shown in Fig. 2B, the precoated metal sheet of the prior art has a relatively small film thickness (about 3 to 30 μm), so that the bright pigment 5 is oriented in the coating film at an angle slightly parallel to the surface of the coating film. Then, the light incident on the precoated metal sheet becomes more likely to be positively reflected, and the flop will become larger.

As shown in Fig. 2C, in the precoated metal sheet of the present embodiment, an appropriate amount of fine white pigment 7 is mixed in the coating film. Due to the white pigment 7, the incident light rays before reaching the bright pigment 5 or the reflected light reflected by the bright pigment 5 are diffused. As a result, although the directivity of the bright pigment 5 is high, the flop is smaller than that of the conventional precoated metal sheet. Further, in Fig. 2C, the diameter of the white pigment 7 is enlarged and displayed.

Therefore, in the precoated metal sheet of the present embodiment, an appropriate amount of fine white pigment 7 is contained in the coating film, whereby the change in color tone and glitter due to the difference in line of sight direction (flop discoloration) can be reduced.

Hereinafter, the precoated metal sheet of the embodiment will be described with reference to the drawings. (Pre-coated metal plate 10) First, the pre-coated metal plate 10 will be described. 3 and 4 are schematic views showing the configuration of the precoated metal sheet 10.

As shown in FIGS. 3 and 4, the precoated metal sheet 10 is provided with a metal plate 1 and a coating film 3 having a film thickness of 5 to 30 μm. The coating film 3 is provided on at least one surface of the metal plate 1 and contains a bright pigment. 5. A white pigment 7 having an average particle diameter of 200 to 400 nm and a content of 0.5 to 4.0% by mass. In addition, the white pigment 7 is one or more selected from the group consisting of titanium oxide, zinc oxide, barium sulfate, basic carbonate, and cerium oxide.

<Metal Sheet 1> The precoated metal sheet 10 is provided with a metal sheet 1 as a base material. The metal plate 1 is not particularly limited, and a known metal plate can be used, or it can be made of an alloy material. The metal plate 1 can be exemplified by a steel plate, a stainless steel plate, an aluminum plate, an aluminum alloy plate, a titanium plate, and a copper plate. The metal plate 1 can also be plated on the surface. Examples of the plating type include galvanization, aluminum plating, copper plating, and nickel plating. It can also be used for alloy plating. For the steel sheet, generally known steel sheets and plated steel sheets such as a hot-dip galvanized steel sheet, an electrogalvanized steel sheet, a galvanized-nickel alloy steel sheet, a molten alloyed galvanized steel sheet, an aluminum-plated steel sheet, or an aluminum-zinc alloy-plated steel sheet can be used. .

<Coating Film 3> The precoated metal sheet 10 is provided with a coating film 3 which is provided on at least one surface of the metal sheet 1 and contains a bright pigment 5 and an average particle diameter of 200 to 400 nm and a content of 0.5 to 4.0. % of white pigment 7, having a film thickness of 5 to 30 μm. The coating film 3 may be provided on one surface of the metal plate 1 as shown in FIG. 3, or may be provided on both surfaces of the metal plate 1 as shown in FIG.

<Bright Pigment 5> The coating film 3 has a bright pigment 5. Here, the bright pigment 5 is a general term for a pigment having a glittering feeling such as a pearl pigment, a glass flake pigment, and a metallic pigment. Specifically, as the pearl pigment, a generally known pearl pigment such as mica or synthetic mica can be used, and a commercially available product can also be used.

The so-called glass flake pigment is a flake-shaped glass frit, and the surface may be coated with a metal or metal oxide. Commercially available products can also be used for the glass flake pigment. As the metallic pigment, fine particles of a metal such as aluminum or silver, or flaky fine particles or the like can be used. The bright pigment 5 is preferably a metal pigment capable of obtaining an appropriate metallic appearance, particularly a thin aluminum sheet.

However, the bright pigment 5 is a scaly aluminum pigment carrying a pigment described in Patent Document 4 (a metallic pigment which chemically adsorbs an organic or inorganic coloring pigment on the surface of a scaly aluminum pigment), Patent Literature The mica-like iron oxide powder described in the fifth embodiment or the thin aluminum oxide sheet pigment coated with the metal oxide described in Patent Document 6 cannot provide appropriate flop, which is not preferable. Although the reason for this is not determined, it is considered that when the above pigment is added to the coating film 3, some interaction occurs between the above pigment and the white pigment 7 to be described later, and an appropriate flop can not be obtained. Sexuality.

The shape of the bright pigment 5 is not particularly limited, but in order to appropriately reflect light, it is preferably in the form of a sheet. Here, the sheet-like shape means that the aspect ratio (average particle diameter D50 (accumulated weight 50% particle diameter) / thickness ratio) is generally 5 to 20. The size of the bright pigment 5 is not particularly limited, but in order to obtain appropriate flop, the average particle diameter (D50 (accumulated weight 50% particle diameter) is preferably 20 to 50 μm, and the thickness is 0.5 to 5.0. Μm is preferred.

<White Pigment 7> The coating film 3 contains a white pigment 7 having an average particle diameter of 200 to 400 nm and a content of 0.5 to 4.0% by mass. The white pigment 7 functions as a white pigment 7 depending on the type, particle diameter, and amount of addition, and the coating film 3 becomes cloudy or loses luster, or the color tone changes to a blue-gray tone, so that a white pigment must be appropriately selected. The type, particle size and amount of addition of 7.

The white pigment 7 is at least one selected from the group consisting of titanium oxide, zinc oxide, barium sulfate, basic carbonate, and cerium oxide. When the white pigment 7 contained in the coating film 3 is at least one of the above compounds, appropriate flop can be obtained, which is preferable.

The white pigment 7 has an average particle diameter of 200 to 400 nm. When the average particle diameter of the white pigment 7 is 200 nm or less, a sufficient diffusion reflection effect cannot be obtained, which is not preferable. Further, when the average particle diameter of the white pigment 7 exceeds 400 nm, it functions as a white pigment, and if the color tone changes to a blue-gray tone or the metallic feeling is lost, it is not preferable. The average particle diameter of the white pigment 7 is preferably from 250 to 350 nm.

The coating film 3 contains 0.5 to 4.0% by mass of the white pigment 7. When the content of the white pigment 7 is less than 0.5% by mass, since it is not possible to obtain an appropriate flop, it is not preferable. When the content of the white pigment 7 exceeds 4% by mass, the transparency of the coating film 3 is lowered and the metallic feeling is lost, which is not preferable. The coating film 3 is preferably contained in an amount of 1.0 to 3.0% by mass of the white pigment 7, more preferably 1.5 to 2.5% by mass.

By setting the content of the white pigment 7 of the coating film 3 to 0.5 to 4.0% by mass, the light irradiated onto the surface of the precoated metal sheet 10 can be appropriately reflected. The light that illuminates the pre-coated metal plate 10 is reflected in a state of near-discriminate reflection, but is different from the so-called disordered reflection, and a very small amount of white pigment 7 is diffused and reflected to enhance the metallic feeling other than the regular reflection. To reflect.

In the prior art, in order to form a white coating film, in order to add a white pigment to a coating film, for example, in International Publication No. 2014/175420, 30 to 60% by mass of a white pigment, that is, titanium oxide, is added to the coating film. in. On the other hand, in the present embodiment, the white pigment 7 is not added in order to form a white coating film, but the white pigment 7 is added in order to impart appropriate flop to the coating film 3. Therefore, the amount of the white pigment 7 added to the coating film 3 is greatly reduced as compared with the conventional technique, and is 0.5 to 4.0% by mass.

The resin of the main component of the coating film 3 is not particularly limited. From the viewpoint of high transparency, the resin of the coating film 3 is preferably polyethylene, polyester, acrylic or the like. Similarly to the conventional metal coating film, a coloring agent (dye) or various additives may be mixed in the coating film 3, and a transparent coating film (not shown) may be formed on the surface. The coloring agent (dye) added to the coating film 3 may be an azo dye, an anthraquinone dye, an anthraquinone dye, a sulfur dye, a phthalocyanine dye, a diphenylmethane and a triphenylmethane dye, another nitro dye, or a pyridine dye. And other known dyes.

<Content ratio of Bright Pigment 5 to White Pigment 7 of Coating Film 3> As described above, the coating film 3 contains the bright pigment 5 and the white pigment 7, but in order to exhibit appropriate flop, in the coating film 3 When the content of the bright pigment 5 (unit: mass%) is A, and the content of the white pigment 7 in the coating film 3 (unit: mass%) is B, the value of B/A must be 0.03 to 0.27. The value of B/A is preferably from 0.05 to 0.20, preferably from 0.06 to 0.18.

Examples of various additives that can be added to the coating film 3 include additives such as an antifoaming agent, a leveling agent, and a dispersing aid; and organic wax components such as polyethylene, polypropylene, ester, paraffin, and fluorine; and molybdenum disulfide; Inorganic wax components, etc.; diluents, solvents, and water to reduce the viscosity of the coating.

(Method of Manufacturing Precoated Metal Sheet 10) Next, a method of manufacturing the precoated metal sheet 10 will be described.

The precoated metal sheet 10 can be manufactured by using a general continuous coating line or a coating line for a cutting board, and appropriately selecting a necessary treatment, and performing the selected treatment. The representative manufacturing steps of the coating line are carried out in the order of washing, drying, chemical conversion treatment, drying, painting, drying and baking, cooling, and drying. However, the manufacturing steps of the precoated metal sheet 10 in the present embodiment are not limited thereto.

When a transparent coating film (not shown) is formed on the surface of the coating film 3, the coating film 3 may be coated with a coating material for a transparent coating film after drying and baking and curing the coating film 3 (hereinafter, referred to as " Clear coating"), and dry and burn hardened. Alternatively, the coating layer and the clear coating may be applied together by wet-wet or multi-layer coating, and then the two layers of the layer may be simultaneously dried and burned and hardened. If the wet stacking or multi-layer simultaneous coating method is used, the manufacturing steps can be omitted, which is more suitable.

Moreover, when the metal plate 1 is a zinc-based plated steel sheet, it can be used in a continuous plating steel plate apparatus or a continuous hot-dip galvanized steel sheet apparatus, after the plating step, using a wet-stacking coating apparatus or a simultaneous multilayer coating apparatus. By manufacturing the line, coating can be applied before the formation of the oxide film on the surface of the plated metal, and the appearance defects caused by the oxide film can be prevented.

Here, the multi-layer simultaneous coating means that the slit mold coater or the slide hopper type curtain coater can be distinguished by two or more parallel slits or the like. A method in which a coating material is discharged and laminated, and a coating liquid is applied to a substrate while a plurality of coating liquids are simultaneously laminated, and the coating liquid of the laminated layer is simultaneously dried and baked.

The wet-stack wet coating is to apply a coating liquid on a substrate first, and further apply another coating liquid to the coating liquid in a wet state before drying, and then dry the laminated layer coating liquid at the same time. The method of burning. Specifically, the wet-stack wet coating method may be, for example, a coating method by a coating method such as roll coating, dip coating, curtain flow coating, or roll curtain coating. After the coating layer is applied, before the coating layer is dried and baked, a curtain flow coating, a roll curtain coating, a sliding funnel curtain coating, a slit die coating, etc. are further applied thereon. A method of coating the second layer with the second layer after drying, and then drying and drying the multilayer coating film in a wet state.

In the present embodiment, a method of simultaneously drying, baking and hardening a coating film which is applied simultaneously or wet-wet coating can be used, and a generally known baking furnace for a coating material such as a hot air drying furnace can be used. A heating furnace, an induction heating furnace, an infrared heating furnace, or a heating furnace in combination therewith.

In this way, by laminating the coating liquid in an undried state and applying it at the same time, since the system performs the drying step which is conventionally performed in each layer, it is also advantageous from the viewpoint of productivity or manufacturing cost, and there are also few drying apparatuses. The advantages that can be achieved.

[Examples] <Example 1> A resin which forms a coating film is a polyester. After the coating composition was changed by changing the composition of the coating film as described in the table, a coating film having a film thickness in the table was formed on the galvanized steel sheet as a sample. With respect to each sample, flop (ΔL), metallic feeling, and appearance were evaluated by the method described later.

<Vertical color difference (ΔL)> The flop of each sample was measured in the following manner. First, using a multi-angle spectrophotometer MA-68II manufactured by X-RITE Co., Ltd., an L value of 15°, that is, L15, and an L value of 110°, that is, L110, were measured. Next, ΔL indicated by the formula L15-L110=ΔL is calculated, and ΔL is an index of flop.

The flop is evaluated as follows according to the value of ΔL. Excellent: △L≦60 Excellent: 60<△L≦65 Acceptable: 65<△L≦70 Bad: 70<△L In the above four grades, it will be evaluated as excellent, excellent, and still Can be considered qualified.

<Metal sensation> The metallic feeling was evaluated in the following manner. Eight evaluators who were skilled in evaluating the metallic feeling of the precoated metal sheets evaluated the metallic feeling of the precoated metal sheets under natural sunlight in the following three grades. 3 points: Metallic feeling 2 points: Low metallic feeling 1 point: No metal feeling According to the total score of 8 people, the metal feeling is evaluated according to the following four levels. Excellent: 20 points or more and 24 points or less: 16 points or more and less than 20 points: 12 points or more and less than 16 points: 8 points or more and 12 points or less in the above 4 In the grade evaluation, those who are evaluated as excellent, excellent, and acceptable are considered qualified.

<Appearance> The appearance was evaluated in the following manner. An evaluator who was skilled in evaluating the appearance of the precoated metal sheet observed the appearance of the precoated metal sheet under natural sunlight. The appearance is evaluated in the following two levels. Excellent: No defects were found. Inferiority: A defect of 1 mmφ or more was found. In the above two grade evaluations, those who are evaluated as excellent are considered as qualified.

The conditions and evaluation results of the respective examples and comparative examples are shown in Tables 1 to 5.

[Table 1]

[Table 2]

[table 3]

[Table 4]

[table 5]

As shown in Tables 1 to 3, all the evaluations of the flop, the metallic feeling and the appearance satisfying the conditions satisfying the conditions of the present invention are desirable. On the other hand, as shown in Tables 4 and 5, in the comparative examples which did not satisfy the conditions of the present invention, evaluation of either flop, metallic feeling or appearance was not preferable.

<Example 2> Next, the kinds of the resin in the coating film were changed without changing the conditions of the bright pigment and the white pigment, and the flop, the metallic feeling and the appearance were examined in the same manner as in Example 1. The evaluation results are shown in Table 6.

[Table 6]

As shown in Table 6, the desired evaluation results were obtained regardless of the use of any of the resins. Further, in Tables 1 to 6, the aluminum used as the bright pigment means a thin aluminum sheet.

Industrial Applicability According to the above-described embodiment, it is possible to provide a precoated metal sheet having a small change in hue and gloss depending on the direction of the line of sight.

1‧‧‧Metal sheet

3‧‧·coating film

5‧‧‧Light pigment

7‧‧‧White pigment

10‧‧‧Pre-coated metal sheets

Fig. 1 is a view showing the principle of measurement of the brightness L by a polygon spectrophotometer. Fig. 2A is a schematic view showing the cross-sectional structure of a coated metal plate after the prior art. Fig. 2B is a schematic view showing the cross-sectional structure of a precoated metal sheet of the prior art. Fig. 2C is a schematic view showing the cross-sectional structure of the precoated metal sheet of the embodiment. Fig. 3 is a schematic view showing the configuration of a precoated metal sheet of the embodiment. Fig. 4 is a schematic view showing the configuration of a precoated metal sheet of the embodiment.

Claims (5)

A precoated metal sheet, comprising: a metal plate; and a coating film disposed on at least one surface of the metal plate and having a film thickness of 5 to 30 μm, and containing a bright pigment and a white pigment, the white pigment The average particle diameter is 200 to 400 nm and the content is 0.5 to 4.0% by mass; and the white pigment is at least one selected from the group consisting of titanium oxide, zinc oxide, barium sulfate, basic carbonate, and cerium oxide; Further, the content of the bright pigment in the coating film is A in mass%, and when the white pigment content is B in mass%, the value of B/A is 0.03 to 0.27. The precoated metal sheet of claim 1, wherein the aforementioned average particle diameter of the white pigment is from 250 to 350 nm. A precoated metal sheet according to claim 1 or 2, wherein the aforementioned bright pigment is a thin aluminum sheet. The precoated metal sheet of claim 1 or 2, which satisfies one or more of the following: the value of B/A is 0.05 to 0.20; the incident angle of 45° is applied to the surface, and When the angle of the positive reflected light of the light is 0° and the incident position of the light is 90°, the brightness of 15°, that is, the brightness of L15 and 110°, that is, L110, L15 and L110, is measured by a multi-angle spectrophotometer. The difference is that L15-L110 is 70 or less; and the surface of the coating film has a clear coating film. A precoated metal sheet according to claim 3, which satisfies the following Either or more: the value of B/A is 0.05 to 0.20; the light is incident on the surface at an incident angle of 45°, and the angle at which the specular reflected light of the light is emitted is 0°, and the light is made When the incident position is 90°, the brightness of 15° is measured by a multi-angle spectrophotometer, that is, the lightness of L15 and 110°, that is, L110, and the difference between L15 and L110, that is, L15-L110 is 70 or less; the surface of the coating film is more transparent. Coating film.