JP6294787B2 - Painted metal plate and exterior building materials - Google Patents

Description

  The present invention relates to a coated metal sheet for exterior and exterior building materials.

  The painted metal plate is excellent in versatility, designability, durability and the like, and is used in various applications. In a coated metal plate for use as an exterior building material, a gloss modifier is usually blended in the top coat film on the surface of the painted metal plate mainly from the viewpoint of design. Silica particles are usually used for the gloss modifier in the coated metal plate for exterior building materials. The particle size of the silica particles is usually defined by the average particle size. The average particle diameter of the silica particles as the gloss adjusting agent in the coated metal plate is usually 3 to 30 μm depending on the color and application (see, for example, Patent Document 1 (paragraph 0018)). Further, a matting agent having a larger particle size than that of the gloss adjusting agent needs to be further added in order to impart an unevenness to the coating film and to give the appearance and texture of a so-called “matte coated steel sheet”. Examples of the type of matting agent include glass beads and resin beads. Usually, the average particle diameter of a matting agent is 10-50 micrometers (for example, refer patent document 2 (paragraph 0016)).

JP 2011-148107 A JP 2004-154993 A

  For painted metal sheets for exterior building materials, chromate-based coated steel sheets are used. In the chromate-based coated steel sheet, efforts have been made to improve the moldability and the corrosion resistance of the cut end surface portion, and the chromate-based coated steel sheet has long-term durability. On the other hand, in recent years, there is a strong interest in environmental protection in the technical field of exterior building materials. For this reason, legal regulations that prohibit the use of ingredients that have a negative impact on the environment or are likely to be possible are being considered. For example, in a coated metal plate, it has been studied to limit the use of a hexavalent chromium component that is widely used as a rust preventive component in the near future. Various studies have been conducted on chromate-free coated steel sheets, including pre-coating treatments and optimization of anti-corrosion pigments, and properties that are comparable to chromate-based coated steel sheets can be obtained at the forming and cutting end surfaces. .

  However, in the chromate-based coated steel sheet, the flat part corrosion resistance was not a big problem, but in the chromate-free coated steel sheet, the corrosion in the flat part may be remarkable, and in particular, silica particles were used as the gloss modifier. In this case, as shown in FIG. 1, in actual use, corrosion such as spot rust and swelling of the coating film may occur in the flat portion earlier than the assumed years of use.

  The present invention provides a coated metal plate and an exterior building material that have a matte design and have excellent flat portion corrosion resistance equivalent to or better than a coated metal plate that includes a chromate-free metal plate even if it is chromate-free. The task is to do.

  The inventors diligently studied the cause of the above-described corrosion at the flat portion. FIG. 2 is a photomicrograph of the corroded portion of the flat portion of the chromate-free painted metal plate. In FIG. 2, part A is a part where silica particles as a gloss adjusting agent are exposed from the top coat film, and part B is a part where the silica particles are dropped from the top coat film. FIG. 3 is a reflection electron micrograph of the cross section along the straight line L in FIG. 2 of the A part of the painted metal plate, and FIG. 4 is the B part of the painted metal plate in FIG. It is a reflection electron micrograph of the cross section along the straight line L. FIG. 3 clearly shows that the silica particles exposed on the surface of the top coating film are cracked, and FIG. 4 shows that the holes in the top coating film from which the silica particles have fallen are corroded on the metal plate. It clearly shows that this is the starting point.

  As described above, when the present inventors use particles having pores such as silica particles for the gloss adjusting agent, the corrosion is caused by cracking, disintegrating, or dropping off of the gloss adjusting agent of the top coat film. In addition, it was confirmed that the gloss modifier exposed from the top coating film, which was depleted by actual use, was cracked, collapsed, and dropped from the top coating film.

  Further, as a result of studying the gloss modifier, the present inventors have found that the silica particles defined by the average particle diameter include particles that are considerably larger than the average particle diameter with respect to the thickness of the top coat film. It was confirmed that For example, when the present inventors observed the silica particle whose average particle diameter is 3.3 micrometers among the commercially available silica particles used for the said gloss regulator with an electron microscope, silica particles with a particle diameter of about 15 micrometers are found. It was confirmed that it was included (FIG. 5). Furthermore, when the present inventors observed the surface (B part in FIG. 6A) of the said silica particle, it confirmed that the countless fine space | gap peculiar to aggregated particles was opening on the surface (FIG. 6B). .

  In addition, when the present inventors use agglomerated particles such as silica or polyacrylonitrile (PAN) as a matting agent that can be further used for the topcoat film, the matting agent exposed from the topcoat film is similarly used. It was confirmed that the portion where the cracks were broken, collapsed or dropped off was the starting point of corrosion (FIGS. 7 and 8).

  And the present inventors pay attention to the fact that such large particle size aggregated particles cause a decrease in corrosion resistance, and by using a gloss adjusting agent and a matting agent having a specific particle size with respect to the film thickness of the top coat film, It has been found that corrosion resistance equal to or higher than the corrosion resistance obtained by using a chromate-based chemical conversion treatment in a conventional metal plate and the use of a chromium-containing anticorrosive pigment in an undercoat film is obtained. Then, the present inventors have found that the same tendency as described above is observed even when a fibrous matting agent is used as the matting agent, and completed the present invention.

That is, this invention relates to the following coating metal plates and exterior building materials.
[1] A coated metal plate having a metal plate and a top coat film disposed on the metal plate, wherein the top coat film is a particle having pores, a gloss modifier and a fibrous matte The gloss adjusting agent content in the top coating film is 0.01 to 15% by volume, and the matting agent content in the top coating film is 0.01 to 15% by volume. The number average particle diameter of the gloss modifier is R (μm), the film thickness of the top coat film is T (μm), and the 97.5% particle diameter in the cumulative particle size distribution of the gloss modifier is D1 _97.5 (μm), 97.5% fiber diameter in the number-based cumulative particle size distribution of the matting agent D2 _97.5 (μm), upper limit particle diameter in the number particle size distribution of the gloss modifier Is Ru (μm), and the average fiber length of the matting agent is L (μm). Sometimes a painted metal plate that satisfies the following formula.
D1 _{97.5 /} T ≦ 0.7
Ru ≦ 1.2T
R ≧ 1.0
0.5 ≦ D2 _97.5 /T≦7.0
3 ≦ T ≦ 20
1 ≦ L / D2 _97.5 ≦ 20
[2] The painted metal plate according to [1], wherein the Ru is less than the T.
[3] The painted metal plate according to [1] or [2], wherein the metal plate is subjected to a non-chromate antirust treatment, and the painted metal plate is chromate-free.
[4] The coated metal plate according to [1] or [2], wherein the metal plate is subjected to a chromate rust prevention treatment.
[5] The coated metal plate according to any one of [1] to [4], wherein the gloss adjusting agent is silica particles.
[6] The coated metal plate according to any one of [1] to [5], further including an undercoat film between the metal plate and the topcoat film.
[7] The coated metal plate according to [6], further including an intermediate coating film between the undercoat film and the topcoat film.
[8] The coated metal plate according to any one of [1] to [7], wherein the glossiness at 75 ° is 1 to 25.
[9] The painted metal plate according to any one of [1] to [8], which is a coated metal plate for exterior use.
[10] An exterior building material composed of the coated metal plate according to any one of [1] to [8].

Moreover, this invention relates to the manufacturing method of the following coated metal plates.
[11] A method for producing a coated metal plate having a metal plate and a top coat film disposed on the metal plate, wherein the top coat paint containing a resin, a gloss adjusting agent and a matting agent is applied to the metal plate. And a step of curing the coating film of the top coating to form the top coating film, and the content of the gloss modifier in the top coating film is 0.01 to 15 volumes. %, The content of the matting agent in the top coat film is 0.01 to 15% by volume, the gloss modifier is particles having pores, and the matting agent is fibrous. The number average particle diameter of the gloss modifier is R (μm), the film thickness of the top coat film is T (μm), and the 97.5% particle diameter in the cumulative particle size distribution of the gloss modifier is D1 _97.5 (μm), cumulative number-based fiber diameter of the matting agent The 97.5% fiber diameter in the particle size distribution _{D2 97.5} (μm), the upper limit particle diameter of the number particle size distribution of the gloss modifier Ru (μm), an average fiber length of the matting agent and L ([mu] m) A method for producing a coated metal plate using the gloss adjusting agent and matting agent satisfying the following formula:
D1 _{97.5 /} T ≦ 0.7
Ru ≦ 1.2T
R ≧ 1.0
0.5 ≦ D2 _97.5 /T≦7.0
3 ≦ T ≦ 20
1 ≦ L / D2 _97.5 ≦ 20
[12] The method for producing a coated metal plate according to [11], wherein the top coating is subjected to a treatment for pulverizing particles in the top coating.

  In the present invention, the exposure and cracking of the gloss adjusting agent and the matting agent are prevented from cracking and falling off in the expected service life. As a result, it has the desired design with adjusted gloss, and even if it is chromate-free, it has excellent flat part corrosion resistance equivalent to or better than a painted metal plate including a metal plate treated with chromate rust. A painted metal plate is provided.

It is a microscope picture of the corrosion part (coating blister) which generate | occur | produced in the flat part of the chromate-free painted metal plate after 5 years of actual use. It is a microscope picture of the corroded part in the flat part of a chromate-free painted metal plate. FIG. 3 is a reflection electron micrograph of a cross section taken along a straight line L in FIG. 2 of a portion A of the painted metal plate shown in FIG. FIG. 3 is a reflection electron micrograph of a cross section along a straight line L in FIG. 2 of a portion B of the coated metal plate shown in FIG. 2. It is an electron micrograph of the commercially available silica particle whose average particle diameter is 3.3 micrometers. FIG. 6A is an electron micrograph of commercially available silica particles, and FIG. 6B is an electron micrograph showing the portion B in FIG. 6A further enlarged. FIG. 7 is a photomicrograph of a cross section of a corroded portion of a flat portion of a chromate-free painted metal plate using silica particles as a matting agent. FIG. 8 is a photomicrograph of a cross section of a corroded portion of a flat portion of a chromate-free coated metal plate using PAN particles as a matting agent.

  Hereinafter, a coated metal plate according to an embodiment of the present invention will be described. The said coating metal plate has a metal plate and the top coat film arrange | positioned on the said metal plate.

  The said metal plate can be selected from a well-known metal plate in the range in which the effect in this Embodiment is acquired. Examples of the metal plate include cold rolled steel sheet, galvanized steel sheet, Zn—Al alloy plated steel sheet, Zn—Al—Mg alloy plated steel sheet, aluminum plated steel sheet, stainless steel sheet (austenite, martensite, ferrite, ferrite -Including martensite two-phase system), aluminum plates, aluminum alloy plates, copper plates and the like. The metal plate is preferably a plated steel plate from the viewpoint of corrosion resistance, weight reduction and cost effectiveness. In particular, the plated steel sheet is preferably a molten 55% Al—Zn alloy plated steel sheet, a Zn—Al—Mg alloy plated steel sheet, or an aluminum plated steel sheet from the viewpoint of corrosion resistance and suitability as an exterior building material.

  The metal plate preferably has a chemical conversion treatment film on the surface thereof from the viewpoint of improving the adhesion and corrosion resistance of the coated metal plate. The chemical conversion treatment is a kind of pretreatment for coating a metal plate, and the chemical conversion treatment film is a layer of a composition formed by the pretreatment for coating. The above metal plate is preferably subjected to non-chromate rust prevention treatment from the viewpoint of reducing the environmental load in the production and use of the coated metal plate, and the chromate rust prevention treatment is preferably applied to the corrosion resistance. From the viewpoint of further improving the ratio.

  Examples of the chemical conversion coating by the non-chromate antirust treatment include Ti-Mo composite coating, fluoroacid coating, phosphate coating, resin coating, resin and silane coupling agent coating, silica coating, silica And silane coupling agent-based coatings, zirconium-based coatings, and zirconium and silane coupling agent-based coatings.

From the above viewpoint, the amount of the Ti—Mo composite coating on the metal plate is preferably 10 to 500 mg / m ² in terms of total Ti and Mo, and the amount of the fluoroacid coating is fluorine. It is preferably ³ to 100 mg / m ² in terms of conversion or total metal elements, and the amount of the phosphate film deposited is preferably 0.1 to 5 g / m ² in terms of phosphorus elements.

Further, the amount of the resin-based coating is preferably ¹ to 500 mg / m ² in terms of resin, and the amount of the resin and the silane coupling agent-based coating is 0.1 to 50 mg / m in terms of Si. preferably ² is the coating weight of the silica-based coating is preferably 0.1 to 200 mg / ^{m 2} in terms of Si, the adhesion amount of the silica and silane coupling agent-based coating, in terms of Si is preferably 0.1 to 200 mg / ^{m 2,} the adhesion amount of the zirconium-based coating is preferably 0.1-100 mg / ^{m 2} in terms of Zr, of the zirconium and a silane coupling agent-based coating The amount of adhesion is preferably 0.1 to 100 mg / m ² in terms of Zr.

Examples of the chromate rust prevention treatment include a coating type chromate treatment and a phosphoric acid-chromic acid treatment. From said viewpoint, it is preferable that the adhesion amount of the film | membrane by the said chromate rust prevention process in the said metal plate is 20-80 g / m < ² > in conversion of chromium element.

  The top coat film is usually composed of a resin. The resin is appropriately selected from the viewpoints of design properties and weather resistance. Examples of the resin include polyester, acrylic resin, and urethane resin.

  The film thickness T of the top coat film is 3 to 20 μm. If the film thickness T of the topcoat film is too thick, it may cause the occurrence of coating defects (waki), decrease in productivity and increase in manufacturing cost, and if it is too thin, the desired design and expected design properties. Flat part corrosion resistance may not be obtained. For example, in order to obtain a coated metal plate that has good productivity, exhibits the desired gloss and color, and can be used as an exterior building material for at least 10 years, the film thickness T of the top coat film is: From the above viewpoint, for example, it is preferably 13 μm or more, more preferably 14 μm or more, and further preferably 15 μm or more. For the above reasons, the film thickness T of the top coat film is preferably 19 μm or less, and more preferably 18 μm or less. The film thickness T of the top coat film is, for example, an average value of the distances from the bottom surface to the surface at a plurality of portions where the matting agent is not present in the top coat film.

  When the coated metal plate has a coating film other than the top coating film, the film thickness T of the top coating film can be determined in consideration of the presence of the other coating film. For example, when the coated metal plate has an undercoat film and an overcoat film, which will be described later, the film thickness T of the topcoat film is preferably 9 to 20 μm from the viewpoint of design properties, corrosion resistance, and workability. . Moreover, when the coated metal plate has an undercoat coating film, an intermediate coating film and a top coating film described later, the film thickness T of the top coating film is preferably 3 to 18 μm from the above viewpoint.

  The film thickness T of the top coat film is preferably thicker when the color of the top coat film is bright from the viewpoint of the design properties of the coated metal plate, and can be thinner when the color of the top coat film is dark. . For example, if the L value of the top coat film is 80 or less, the film thickness T of the top coat film can be 15 μm or less, and if the L value of the top coat film is more than 80, for example. The film thickness T is preferably more than 15 μm.

  Alternatively, the film thickness T of the top coat film is such that the color of the top coat film is close to the color of the surface of the steel sheet before the top coat film is formed (for example, the undercoat film described later) from the viewpoint of the design properties of the coated metal sheet. It can be made as thin as possible. For example, if the absolute value ΔL of the difference between the L value of the top coat film and the L value of the surface color of the steel sheet before the coating is formed is 10 or less, the film thickness T of the top coat film is not clear. If ΔL is 20 or less, the film thickness T can be 15 μm or less, and if ΔL is 50 or less, the film thickness T can be 17 μm or less.

  The L value can be obtained by calculating from a measurement result using a commercially available spectrocolorimeter (for example, “CM3700d” manufactured by Konica Minolta Optics, Inc.) using a Hunter color difference formula.

  The top coat film contains a gloss modifier. The gloss modifier is used to properly roughen the surface of the top coat film for the purpose of achieving the desired gloss on the coated metal plate or adjusting the gloss variation between production lots. Blended in to bring the desired appearance with luster to the painted metal sheet.

  The gloss-controlling agent has a number average particle size R (hereinafter also referred to as “R1”) of 1.0 μm or more. If the gloss modifier is too small, the gloss of the top coat film is too high, and the desired design properties may not be obtained. As described above, the number average particle diameter R1 of the gloss adjusting agent can be appropriately determined within a range satisfying the following formula according to the intended designability (glossiness) of the coated metal plate. If it is too high, the roughness of the top coat film will increase, and the desired design properties will not be obtained. For example, the number average particle size R1 of the gloss modifier is preferably 2.0 μm or more and 3.0 μm or more from the viewpoint of obtaining a coated metal plate having a flat portion corrosion resistance and a glossiness of 1 to 25 at 75 °. Is more preferably 5.0 μm or more, or even more preferably 7.0 μm or more. The number average particle diameter can be confirmed by observing the cross section of the top coat film, or by an image analysis method and a Coulter method (for example, using a precision particle size distribution measuring device “Multisizer 4” manufactured by Beckman Coulter, Inc.). It is possible to measure.

  Further, when the coated metal plate has a coating film other than the top coat film, the number average particle diameter R1 of the gloss adjusting agent can be determined according to the film thickness T of the top coat film. For example, when the coated metal plate has an undercoating film and an overcoating film, the number average particle diameter R1 of the gloss adjusting agent is selected from the viewpoints of design properties, corrosion resistance, and workability due to the desired gloss. It is preferably 0 μm or more. When the coated metal plate has an undercoat film, an intermediate coat film and a topcoat film, which will be described later, the number average particle diameter R1 of the gloss modifier is 1.0 μm or more from the above viewpoint. It is preferable.

  Content of the said gloss regulator in the said top coat film is 0.01-15 volume%. When there is too much the said content, the glossiness of top coat film is too low, and process part adhesiveness falls. If the content is too small, the gloss cannot be controlled, and therefore the desired designability may not be obtained even if the content is large or small. For example, from the viewpoint of obtaining a coated metal plate having a glossiness of 1 to 25 at 75 °, the content of the gloss modifier in the top coat film is preferably 0.2% by volume or more, and 0.4% by volume. More preferably, it is 0.6 vol% or more. For the above reasons, the content of the gloss modifier in the top coat film is preferably 13% by volume or less, and more preferably 11% by volume or less. The content can be confirmed by measuring the ash content of the top coat film, collecting the gloss adjusting agent by dissolving the top coat film, image analysis of cross-sectional images in which elements are identified at a plurality of locations, and the like.

  The gloss adjusting agent is a particle having pores (hereinafter also referred to as “pore particle”). Examples of the pore particles include aggregates in which primary particles are chemically bonded, aggregates in which primary particles are physically bonded, and porous particles. The porous particles have a porous structure at least inside the particles. The gloss adjusting agent may be composed of only the pore particles or may contain particles other than the pore particles. The pore particles may be inorganic particles or organic particles, and can be selected from known pore particles used as a gloss adjusting agent as long as the following formula is satisfied. Examples of the material of the fine pore particles include silica, calcium carbonate, barium sulfate, polyacrylonitrile, and a calcium carbonate-calcium phosphate complex. The gloss adjusting agent is preferably silica particles from the viewpoint of having a high gloss adjusting effect on the coated metal plate.

The coated metal plate has a number average particle diameter of the gloss modifier of R1 (μm), a film thickness of the top coat film of T (μm), and a cumulative particle size distribution based on the number of gloss modifiers (hereinafter referred to as “number” When the 97.5% particle diameter in “particle size distribution” is D1 _97.5 (μm), the following formula is satisfied. However, when the upper limit particle diameter of the number particle size distribution of the gloss adjusting agent is Ru (μm), the Ru is 1.2 T or less. The “upper limit particle size (Ru)” is a particle size when the particle size distribution curve in the number particle size distribution is not less than the number average particle size R1 and overlaps the baseline.
D1 _{97.5 /} T ≦ 0.7

D1 _97.5 is a substantial index of the particle size of the gloss modifier that can achieve the effect of the present invention. When D1 _{97.5 / T} is too large, the pore particles are exposed by attrition due to actual use of the top coating film, it may not be obtained the desired flat portion corrosion resistance and D1 _{97.5 / T} If it is too small, the desired glossiness may not be obtained.

For example, from the viewpoint of obtaining a coated metal plate having a glossiness of 1 to 25 at 75 °, D1 _97.5 / T is preferably 0.3 or more, and more preferably 0.4 or more. Further, for example, from the viewpoint of obtaining a coated metal plate having an actual service life of at least 10 years as an exterior building material, D1 _97.5 / T is preferably 0.6 or less, and is 0.5 or less. It is more preferable.

On the other hand, in the number particle size distribution, particles larger than D1 _97.5 contain only about 2.5% of the number of all the particles. Therefore, in the particle size distribution of the number average particle size R1 or more in the number particle size distribution satisfying “D1 _{97.5 /} T ≦ 0.7”, the gloss adjusting agent in which the particle size distribution curve exhibits a specific sharpness is used as it is. It is possible to apply to the invention. That is, the overlapping point (Ru) between the particle size distribution curve in the number particle size distribution of the number average particle size R1 or more satisfying “D1 _{97.5 /} T ≦ 0.7” and the baseline in the number particle size distribution is 1.2 T or less. The gloss modifier described above can be applied to the present invention.

  Even if the upper limit particle size Ru (μm) is 1.2 T or less (over 0.7 T), the reason why sufficient flat part corrosion resistance is exhibited is considered as follows. First, in the top coat film, since the resin composition of the top coat film is covered on the gloss adjuster, a gloss adjuster having a particle size of up to 1.2 T is usually not exposed on the surface of the top coat film. Therefore, it is considered. Further, in the gloss adjusting agent, particles having a particle size larger than 0.7T are not greatly deviated from the normal distribution even if the actual number particle size distribution in the range larger than R1 deviates from the normal distribution. Since it is difficult to think, it is considered that there is less than 2.5% of the total at most. For this reason, it is thought that the particle | grains larger than 0.7T in the said gloss regulator are too few to have a substantial influence on flat part corrosion resistance. Furthermore, the gloss modifier is generally irregular and is usually flat to some extent. The gloss adjusting agent in the top coating film is usually more easily oriented in the horizontal direction than the vertical direction by applying the below-described top coating paint. This is probably because the particle size in the film thickness direction is usually smaller than the major axis (for example, 1.2 T) of the gloss modifier.

If the Ru is too large, the fine pore particles may be exposed due to depletion associated with the actual use of the top coat film, and the desired flat portion corrosion resistance may not be obtained. From the viewpoint of obtaining a coated metal plate having an actual use age of at least 10 years as an exterior building material, Ru is preferably less than T, more preferably 0.7T or less, and 0.6T or less. Is more preferable. R1, D1 _97.5 and Ru can be obtained from the number particle size distribution of the gloss modifier.

  In addition, the side smaller than the average particle diameter R1 in the number particle size distribution of the gloss adjusting agent may be in any form as long as the condition of the particle size distribution is satisfied.

  A commercially available product or a classified product thereof can be used as the gloss adjusting agent that satisfies the conditions relating to the particle size distribution.

  In manufacturing the coated metal plate, the gloss modifier may not satisfy the above-mentioned particle size conditions (for example, there are coarse particles having a particle size larger than 1.2 T). Alternatively, the above conditions may be deviated during the manufacturing process. In this case, it is preferable from the viewpoint of obtaining the above-described coated metal plate to perform a step of pulverizing the coarse particles in a later-described top coating material, as in a treatment by a roller mill described later.

  The top coat film also contains a matting agent. The matting agent described above expresses irregularities that can be visually confirmed larger than the roughness imparted by the gloss modifier on the topcoat, and is blended in the topcoat to give the texture and paint the desired appearance. Bring to a metal plate. In addition, the matting agent has a particle size that is sufficiently large to counteract the gloss, and when it has particles larger than the film thickness of the top coat film, it can prevent scratches on the top coat film. . Thereby, the scratch resistance of the coated metal plate can also be improved. Moreover, the improvement effect of the intensity | strength of the top coat film in the plane direction by the said matting agent is anticipated.

  The matting agent has a fibrous shape. That is, the matting agent has a substantially constant cross section and a long axis along a direction in which the cross section continues. The major axis of the cross-sectional shape is the fiber diameter of the matting agent, and the length of the major axis is the fiber length of the matting agent. The material of the matting agent can be appropriately determined within a range where the effects of the present embodiment can be obtained. For example, the matting agent may be a material in which pores are formed on the surface of the matting agent. A material in which pores are not formed on the surface of the quencher may be used. The pores refer to voids that can cause the matting agent to crack due to expansion of a substance (for example, water) present therein. From the viewpoint of preventing the occurrence of cracks, the matting agent preferably does not have the pores on its surface.

  The matting agent material may be an organic substance such as a resin or an inorganic substance. The matting agent can be selected from known fibrous particles. Examples of the matting agent include potassium titanate fiber, wollastonite fiber, silicon carbide fiber, alumina fiber, alumina silicate fiber, silica fiber, rock wool, slag wool, glass fiber, carbon fiber and the like.

  If the number average fiber diameter (hereinafter also referred to as “R2”) of the matting agent is too small, the desired design with low glossiness may not be obtained. The desired design may not be obtained due to streaking. R2 can be appropriately determined within a range satisfying the formula described later according to the desired designability (glossiness) of the coated metal plate. For example, in order to obtain a coated metal sheet having a flat portion corrosion resistance and a glossiness at 75 ° of 1 to 25, R2 is preferably 5.0 μm or more, and more preferably 10.0 μm or more. It is more preferably 15.0 μm or more, further preferably 20 μm or more, and further preferably 25 μm or more. For the above reasons, R2 is preferably 75 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less.

  If the average fiber length (hereinafter also referred to as “L”) of the matting agent is too small, the scratch resistance of the top coating film may be insufficient, and if too large, the adhesion of the top coating film is insufficient. It may become. The L can be appropriately determined within a range satisfying the following formula according to the desired mechanical properties of the coated metal plate. For example, in order to obtain a coated metal sheet having a glossiness of 1 to 25 at 75 ° together with the above mechanical properties, the L is preferably 5.0 μm or more, and preferably 10.0 μm or more. More preferably, it is 15.0 μm or more, more preferably 20 μm or more, and further preferably 25 μm or more. For the above reasons, L is preferably 100 μm or less, more preferably 75 μm or less, still more preferably 50 μm or less, and even more preferably 40 μm or less.

The matting agent satisfies the following formula when the 97.5% fiber diameter in the cumulative particle size distribution based on the number is D2 _97.5 (μm).
1 ≦ L / D2 _97.5 ≦ 20

The D2 _97.5 substantially defines the size of the matting agent. The matting agent is fibrous in shape, and the matting agent is usually produced by cutting the matting agent fibers to the desired length. Therefore, the fiber diameter of the matting agent is substantially constant. On the other hand, D2 _97.5 means that there is only 2.5% of a matting agent having a fiber diameter deviating from it. In view of the above manufacturing method of matting agent, D2 _97.5 can be regarded as the practical maximum value of the fiber diameter of the matting agent.

When the ratio of the L to the _{D2 97.5 (L / D2 97.5)} is less than 1, it may be the effect of suppressing scratching of the top coating film by matting agent becomes insufficient. When the ratio L / D2 _97.5 is larger than 20, the adhesion of the top coat film may be insufficient.

When the matting agent R2, D2 _97.5 and L are present independently from the top coat as in the preparation of the top coat described below, for example, measure by the following method. Can do. First, the matting agent is spread on a flat sample table so as not to overlap each other. For the sample stage, either a slide glass specified in JIS R3703 or a filter paper or a metal plate having flatness according to the observation magnification is used. Next, a photomicrograph of the matting agent on the sample stage is taken at a magnification at which the fiber length and fiber diameter can be measured up to two significant figures. Then, although the entire outline of the matting agent can be observed in the micrograph, all 200 or more fibers are measured for fiber length and fiber diameter, for example, by applying a ruler to the micrograph, up to 2 significant figures. . From the measurement results obtained, R2 is the average value of all the measured values of the fiber diameter, D2 _97.5 is the number particle size distribution of the fiber diameter, and L is the average value of all the measured values of the fiber length. Desired.

The R2, D2 _97.5, and L of the matting agent in the top coat film can be confirmed by observing a cross section of the top coat film, or by image analysis method and Coulter method ( For example, it can be measured using a precision particle size distribution measuring apparatus “Multisizer 4” manufactured by Beckman Coulter.

  Content of the said matting agent in the said top coat film is 0.01-15 volume%. If the content is too large, streaks may be generated in the top coat film, and the adhesion of the processed part may be lowered. If the content is too small, the desired gloss (matte appearance) cannot be obtained, and the scratch resistance may be insufficient. For example, from the viewpoint of obtaining a coated metal plate having a glossiness of 1 to 25 at 75 °, the content of the matting agent in the top coat film is preferably 0.1% by volume or more, and 0.4% by volume. More preferably, it is 0.6 vol% or more. For the above reason, the content of the matting agent in the top coat film is preferably 15% by volume or less, and more preferably 10% by volume or less. The content can be confirmed by measuring the ash content of the top coat film, collecting the matting agent by dissolving the top coat film, or analyzing the cross-sectional images of the elements identified at a plurality of locations.

Moreover, the said coating metal plate satisfies the following formula. As described above, T is the film thickness (μm) of the top coat film, and D2 _97.5 is 97.5% particle diameter (μm) in the cumulative particle size distribution of the matting agent. .
0.5 ≦ D2 _97.5 /T≦7.0

Since the shape of the matting agent is fibrous, the matting agent is usually arranged in the top coat so that its longitudinal direction is along the plane direction. In consideration of the above arrangement in the top coat in combination with the above-described method for producing the matting agent, D2 _97.5 is effectively the fiber diameter of the matting agent in the film thickness direction of the top coat. Can be regarded as the maximum value of. If the D2 _97.5 / T is less than 0.5, the desired texture may not be obtained and the scratch resistance may be insufficient. When D2 _97.5 / T is too large, the adhesion of the top coat film may be insufficient.

The D2 _97.5 / T is preferably 1 or more and more preferably 2 or more from the viewpoint of obtaining a coated metal sheet having a glossiness of 1 to 25 at 75 ° in addition to the above viewpoint. More preferably, it is 3 or more. Further, for example, from the viewpoint of obtaining a coated metal plate having an actual service life of at least 10 years as an exterior building material, D2 _97.5 / T is preferably 7 or less, and more preferably 5 or less. .

  The top coat film may further contain components other than the above-described resin, gloss adjuster, and matting agent as long as the effect of the present embodiment is obtained. For example, the top coat film may further contain a colorant. Examples of colorants include inorganic pigments such as titanium oxide, calcium carbonate, carbon black, iron black, iron oxide yellow, titanium yellow, bengara, bitumen, cobalt blue, cerulean blue, ultramarine blue, cobalt green, molybdenum red; CoAl, Composite oxide fired pigments containing metal components such as CoCrAl, CoCrZnMgAl, CoNiZnTi, CoCrZnTi, NiSbTi, CrSbTi, FeCrZnNi, MnSbTi, FeCr, FeCrNi, FeNi, FeCrNiMn, CoCr, Mn, Co, SnZnTi; Al flakes, resin-coated Al flakes , Ni flakes, stainless steel flakes and other metallic pigments; and quinacridone red, resol red B, brilliant scarlet G, pigment scarlet 3 , Brilliant Carmine 6B, Lake Red C, Lake Red D, Permanent Red 4R, Bordeaux 10B, Fast Yellow G, Fast Yellow 10G, Para Red, Watching Red, Benzidine Yellow, Benzidine Orange, Bon Maroon L, Bon Maroon L, Brilliant Fast Scarlet , Organic pigments such as Vermillion Red, Phthalocyanine Blue, Phthalocyanine Green, Fast Sky Blue, and Aniline Black. The colorant is sufficiently small with respect to the gloss adjusting agent. For example, the number average particle diameter of the colorant is 0.01 to 1.5 μm. Moreover, content of the coloring agent in top coat film is 2-20 volume%, for example.

  The top coat film may further contain extender pigments. Examples of the extender pigment include barium sulfate and titanium oxide. The extender pigment is sufficiently smaller than the gloss adjusting agent. For example, the extender pigment has a number average particle diameter of 0.01 to 1 μm. Moreover, content of the extender pigment in top coat film is 0.1-15 volume%, for example.

  Moreover, the said top coat film may further contain the lubricant from a viewpoint of preventing generation | occurrence | production of the galling in the top coat film at the time of the process of a coating metal plate. Examples of the lubricant include organic waxes such as fluorine wax, polyethylene wax, styrene wax, and polypropylene wax, and inorganic lubricants such as molybdenum disulfide and talc. The content of the lubricant in the top coat film is, for example, 0 to 10% by volume.

  The top coating film is produced by a known method in which a coating material for a top coating film is applied to the surface of the metal plate or the surface of an undercoating film described later, dried, and cured as necessary. The coating material for the top coat film contains the material for the top coat film described above, but may further contain other components in addition to the material as long as the effects of the present embodiment can be obtained.

  For example, the paint for the top coat film may further contain a curing agent. The said hardening | curing agent bridge | crosslinks the above-mentioned polyester or acrylic resin at the time of hardening (baking) at the time of producing top coat film. The type of the curing agent can be appropriately selected from the above-described crosslinking agents and known curing agents according to the type of resin used and the baking conditions.

  Examples of the curing agent include melamine compounds, isocyanate compounds, and combinations of melamine compounds and isocyanate compounds. Examples of the melamine compound include an imino group type, a methylol imino group type, a methylol group type or a fully alkyl group type melamine compound. The isocyanate compound may be aromatic, aliphatic, or alicyclic, and examples include m-xylene diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, and block compounds thereof.

  Moreover, the top coat film may further contain a curing catalyst as appropriate within a range that does not affect the storage stability of the paint for the top coat film. Content of the said hardening | curing agent in top coat film is 10-30 volume%, for example.

  Further, the top coat film may appropriately contain 10% by volume or less of an ultraviolet absorber (UVA) or a light stabilizer (HALS) in order to further improve the weather resistance. Furthermore, the top coat film may contain a hydrophilizing agent for preventing rain streak stains, for example, 30% by volume or less of a partial hydrolysis condensate of tetraalkoxysilane.

  The said coated metal plate may have a further component in the range with the effect in this Embodiment. For example, it is preferable that the said coated metal plate further has an undercoat film between the said metal plate and the said top coat film from a viewpoint of improving the adhesiveness and corrosion resistance of the top coat film in a coated metal plate. The said undercoat coating film is arrange | positioned on the surface of a metal plate, or the said chemical conversion treatment film surface, when the said chemical conversion treatment film is produced.

  The undercoat coating film is made of a resin. Examples of the resin include epoxy resin, polyester, epoxy-modified polyester resin, acrylic resin, and phenoxy resin.

  The undercoat coating film may further contain a rust preventive pigment, a color pigment, a metallic pigment, an extender pigment, and the like. Examples of the rust preventive pigment include non-chromium rust preventive pigments such as modified silica, vanadate, magnesium hydrogen phosphate, magnesium phosphate, zinc phosphate, and aluminum polyphosphate, strontium chromate, and zinc chromate. , Chromium-based anticorrosive pigments such as barium chromate and calcium chromate are included. Examples of the color pigment include titanium oxide, carbon black, chromium oxide, iron oxide, bengara, titanium yellow, cobalt blue, cobalt green, aniline black, and phthalocyanine blue. Examples of the metallic pigment include aluminum flake (non-leafing type), bronze flake, copper flake, stainless steel flake and nickel flake. Examples of the extender pigment include barium sulfate, titanium oxide, silica, and calcium carbonate.

  The content of the pigment in the undercoat coating film can be determined as appropriate within the range where the effect of the present embodiment can be obtained. For example, the content of the rust preventive pigment in the primer coating film is, for example, It is preferable that it is 10-70 volume%.

  Moreover, the said coated metal plate may further have an intermediate coating film between the said undercoat coating film and the said top coating film from a viewpoint of improving the adhesiveness and corrosion resistance of the top coating film in a coating metal plate.

  The intermediate coating film is made of a resin. Examples of the resin include fluororesins such as polyvinylidene fluoride, polyester, polyester-modified silicone, acrylic resin, polyurethane, and polyvinyl chloride. The intermediate coating film may further contain an additive such as a rust preventive pigment, a coloring pigment, and a metallic pigment as appropriate within the range in which the effect of the present embodiment can be obtained, similarly to the undercoat coating film. .

  The painted metal plate according to the present embodiment is a chromate-free and chromate-based painted metal plate. “Chromate-free” means that the coated metal plate does not substantially contain hexavalent chromium. The fact that the above-mentioned coated metal plate is “chromate-free” means that, for example, any of the above-described metal plate, chemical conversion film, undercoat film and topcoat film is a metal in which the topcoat film or undercoat film is produced alone. Four test pieces of 50 mm × 50 mm were cut out from the plate, immersed in 100 mL of boiling pure water for 10 minutes, and the hexavalent chromium eluted in the pure water was then added to the JIS H8625 appendix 2.4.1. It can be confirmed by the fact that it is below the detection limit when quantified by an analytical method of concentration based on the “diphenylcarbazide colorimetric method”. In the actual use, the coated metal plate does not elute hexavalent chromium into the environment, and exhibits sufficient corrosion resistance at the flat portion. The “flat part” refers to a part that is covered with the top coating film of the metal plate and is not deformed by bending, drawing, overhanging, embossing, roll molding, or the like.

  The painted metal plate is suitable for a matte painted metal plate. Matte means that the gloss at 75 ° is 1 to 25. When the glossiness is too high, enamel-like gloss is dominant and the matte view may not be obtained. The glossiness is adjusted by the average particle diameter of the gloss adjusting agent and matting agent, the content of these in the top coat film, and the like.

  The coated metal plate includes a first step of applying a top coating containing the resin, the gloss adjusting agent and the matting agent on the metal plate, and curing the coating film of the top coating to form the top coating. A second step of forming a coating film.

  In the first step, the top coat may be applied directly to the surface of the metal plate, may be applied to the chemical conversion film formed on the surface of the metal plate, or the painted metal. You may apply | coat to the said undercoat film formed in the surface of the board or the surface of the said chemical conversion treatment film.

  The top coat is prepared, for example, by dispersing the above-described top coat material in a solvent. The coating material may contain a solvent, a crosslinking agent, and the like. Examples of the solvent include hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; ethers such as cellosolve; and ketones such as methyl isobutyl ketone, methyl ethyl ketone, isophorone and cyclohexanone.

  The top coat is applied by a known method such as roll coating, curtain flow coating, spray coating, or dip coating. The amount of the top coat applied is appropriately adjusted according to the desired film thickness T of the top coat.

  In addition, as above-mentioned, by mix | blending a matting agent with a top coat film, not only a unique design is expressed but the damage resistance of a coating-film metal plate can also be improved. In order to achieve both the design and the scratch resistance, it is preferable to apply a coating thicker than a coating film containing only a gloss adjusting agent and no matting agent. Also, by adding a matting agent to the top coat film, the proportion of non-volatile components of the paint increases, so it is possible to paint thicker than a paint film that contains only a gloss modifier and no matte agent. .

  The gloss adjusting agent contained in the top coating satisfies the above-mentioned size condition. When the gloss adjusting agent does not satisfy the above-mentioned size condition in the top coating, the top coating satisfying the above condition is performed by subjecting the top coating to a process of pulverizing particles in the top coating. It is possible to obtain Examples of the above-mentioned “treatment for crushing particles” include treatment by a roller mill. More specifically, before blending the matting agent into the top coat, the treatment is performed by appropriately setting the clearance between the rollers of the roller mill and the treatment time so that the Ru is less than 1.2T. Do. Thereafter, by adding a matting agent, it is possible to obtain the top coating material satisfying the above conditions.

  The second step can be performed by, for example, a known method of baking the top coat onto a metal plate. For example, in the second step, the metal plate to which the paint for the top coat film is applied is heated so that the reached temperature is 200 to 250 ° C.

  The method for producing a coated metal plate may further include other steps than the first step and the second step described above as long as the effects of the present invention are obtained. Examples of the other steps include a step of forming a chemical conversion coating, a step of forming an undercoat coating, and a step of forming an intermediate coating.

  The chemical conversion coating is applied to the surface of the metal plate by a known method such as a roll coating method, a spin coating method, or a spraying method, and the metal plate is applied after coating. It can be formed by drying without washing with water. From the viewpoint of productivity, the drying temperature and drying time of the metal plate are preferably, for example, 60 to 150 ° C. and 2 to 10 seconds at the ultimate temperature of the metal plate.

  The said undercoat coating film is produced by application | coating of the coating material for undercoat films. The coating material may contain a solvent, a crosslinking agent, and the like. Examples of the solvent include hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; ethers such as cellosolve; and ketones such as methyl isobutyl ketone, methyl ethyl ketone, isophorone and cyclohexanone. Examples of the crosslinking agent include melamine resins and isocyanate resins that crosslink the above-described resins. The coating for the undercoat film is prepared by uniformly mixing and dispersing the above-described materials.

  The coating for the undercoat film is a metal with a coating amount that can provide a dry film thickness of 1 to 10 μm (preferably 3 to 7 μm) by a known method such as roll coating, curtain flow coating, spray coating, or dip coating. Applied to the board. For example, the coating film of the paint is baked on the metal plate by heating the metal plate at a temperature of 180 to 240 ° C. at the temperature reached by the metal plate.

  The intermediate coating film is also produced by applying a coating material for the intermediate coating film, similarly to the undercoat coating film. The paint may also contain the solvent, the crosslinking agent, and the like in addition to the material for the intermediate coating film. The coating for the intermediate coating film is prepared by uniformly mixing and dispersing the materials described above. The coating material for the intermediate coating film is, for example, an undercoating with a coating amount of 1 to 10 [mu] m (preferably 3 to 7 [mu] m) as a sum of the dry film thickness of the coating material and the film thickness of the undercoating film by the above-mentioned known method. It is preferable from a viewpoint of workability that it is applied to the coating film. For example, the coating film of the paint is baked on the metal plate by heating the metal plate at a temperature of 180 to 240 ° C. at the temperature reached by the metal plate.

  The use of the coated metal plate is suitable for exterior use. “Exterior” refers to a portion that is exposed to the outside air, such as a roof, a wall, an accessory, a signboard, and an outdoor installation device, and is used for a portion that can be irradiated with sunlight or its reflected light. Examples of the exterior coated metal plate include a painted metal plate for exterior building materials.

  The coated metal plate is formed into an exterior building material such as an exterior building material by known processes such as bending, drawing, overhanging, embossing, and roll molding. Thus, the said exterior building material is comprised with the said coating metal plate. The exterior building material may further include another configuration within a range in which the above effect can be obtained. For example, the exterior building material may further have a configuration that is provided for appropriate installation in actual use of the exterior building material. Examples of such a configuration include a member for fixing the exterior building material to the building, a member for connecting the exterior building materials to each other, a mark indicating the direction when the exterior building material is attached, and heat insulation. Foam sheet and foam layer. These configurations may be included in the above-described exterior coated metal plate.

  In the coated metal plate, the gloss adjusting agent (pore particles) is sufficiently confined in the top coat film. Moreover, the particle size of the gloss adjusting agent in the top coat film in the film thickness direction of the top coat film tends to be sufficiently small as the particle shape is flat. Furthermore, about 97.5% by number, and most of the above gloss modifiers have a sufficiently small particle size of “0.7 T” or less than the film thickness T of the top coat film. Therefore, even if the resin of the top coat film is gradually depleted from the surface of the top coat film due to actual use in exterior applications, the above top coat is not exposed within the expected years of use. It is possible to design a coating film.

  On the other hand, in the coated metal plate, the matting agent is covered with the resin constituting the top coating film, but at least some of the particles of the matting agent are part of the top coating film that does not contain the matting agent. Great for film thickness. Therefore, even if it is within the intended years of use, a matting agent appears from the top coat when the resin of the top coat is gradually depleted from the surface of the top coat by actual use in exterior applications. Sometimes. In such a situation, when pore particles are blended in the top coat film as a matting agent, the portion of the top coat film where the matting agent is cracked, collapsed or dropped off may be a starting point of corrosion. For this reason, in the said coated metal plate, a primary particle is mix | blended as a matting agent. Therefore, even if the primary particles are exposed from the surface of the top coat film by actual use in exterior applications, cracks and collapses that occur in the pore particles and falling off from the top coat film are prevented, such as rainwater. Corrosion factors cannot reach the metal plate.

  Therefore, cracking and disintegration of the gloss modifier (pore particles) within the intended years of use and dropping off from the top coating film, and cracking, disintegration of the matting agent (primary particles), and from the top coating film Dropping is prevented, and corrosive factors such as rainwater cannot reach the metal plate during the intended use years. For this reason, if the said coated metal plate is chromate-free (if the said metal plate is non-chromate rust-proofing treatment), it expresses at least the flat part corrosion resistance equivalent to the conventional coated metal plate that has been chromated, If the chromate treatment is performed, the flat portion corrosion resistance equal to or higher than that of the conventional coated metal plate subjected to the chromate treatment is exhibited. Examples of the “chromate treatment” of the coated metal plate in the present embodiment include the use of an undercoat film containing a chromate rust preventive pigment in addition to the chromate rust preventive treatment of the metal plate. Examples of `` treated coated metal plate '' include a coated metal plate having a non-chromate rust-proof metal plate and an undercoat film containing a chromate-based anti-rust pigment, a chromate rust-proof metal plate and a chromate. And a coated metal plate having an undercoating film containing no rust preventive pigment, and a coated metal plate having a chromate rust preventive-treated metal plate and an undercoating film containing a chromate rust preventive pigment.

As is clear from the above description, according to the present embodiment, particles (pores) having a metal plate and a top coat film disposed on the metal plate, the top coat film having pores. Particles) and a glossy agent in the form of a fiber, and the content of the gloss modifier in the top coat film is 0.01 to 15% by volume, and the matte in the top coat film The content of the agent is 0.01 to 15% by volume, the number average particle diameter of the gloss adjusting agent is R1 (μm), the film thickness of the top coat film is T (μm), and the number of the gloss adjusting agent. The 97.5% particle diameter in the particle size distribution is D1 _97.5 (μm), the 97.5% fiber diameter in the cumulative particle size distribution of the matting agent is D2 _97.5 (μm), The upper limit particle size in the number particle size distribution is Ru (μm), and the average size of the matting agent is Long when the L ([mu] m), because it satisfies the following equation, it is possible to provide a coated metal plate be a chromate-free has sufficient flat portion corrosion resistance.
D1 _{97.5 /} T ≦ 0.7
Ru ≦ 1.2T
R1 ≧ 1.0
0.5 ≦ D2 _97.5 /T≦7.0
3 ≦ T ≦ 20
1 ≦ L / D2 _97.5 ≦ 20

  Further, the Ru of less than T is more effective from the viewpoint of further improving the flat portion corrosion resistance of the coated metal plate or from the viewpoint of further extending the life of the coated metal plate having sufficient flat portion corrosion resistance. is there.

  In addition, the non-chromate anti-rust treatment is applied to the metal plate, and the fact that the painted metal plate is chromate-free is more effective from the viewpoint of reducing the environmental load in the use or production of the painted metal plate. And it is more effective that the said metal plate is subjected to the chromate rust prevention treatment from the viewpoint of further improving the flat portion corrosion resistance of the coated metal plate.

  In addition, the fact that the gloss adjusting agent is silica particles is more effective from the viewpoint of inexpensively producing a coated metal plate having the desired design.

  Further, the coating metal plate further having an undercoat film between the metal plate and the top coat film is more effective from the viewpoint of improving the adhesion and corrosion resistance of the top coat film on the paint metal plate, It is more effective from the above viewpoint to further have an intermediate coating film between the undercoating film and the top coating film.

  Further, when the glossiness at 75 ° of the coated metal plate is 1 to 25, both the desired design and sufficient flat portion corrosion resistance are realized.

  Moreover, it is much more effective that the said coating metal plate is a coating metal plate for exteriors from the viewpoint of reducing the environmental load by the elution of chromium at the time of actual use.

  Moreover, even if the exterior building material comprised with the said coating metal plate is chromate free, it can show the flat part corrosion resistance excellent in the actual use for 10 years or more.

Further, the above-described method for producing a coated metal plate having the above metal plate and a top coat film disposed on the above metal plate is obtained by applying a top coat paint containing a resin, a gloss adjusting agent and a matting agent to the above metal. Including a step of coating on a plate and a step of curing the coating film of the top coating material to form the top coating film, wherein the content of the gloss modifier in the top coating film is 0.01 to 15 The content of the matting agent in the top coat film is 0.01 to 15% by volume, the gloss modifier is particles having pores, and the matting agent is a fiber. The number average particle size of the gloss modifier is R1 (μm), the film thickness of the top coat film is T (μm), and the 97.5% particle size in the number particle size distribution of the gloss modifier is D1 _{97. .5 (μm),} cumulative particle size based on the number of the matting agent The 97.5% fiber diameter in the cloth _{D2 97.5} (μm), the upper limit particle diameter of the number particle size distribution of the gloss modifier and Ru (μm), an average fiber length of the matting agent L ([mu] m) Sometimes, the gloss modifier and matting agent satisfying the following formula are used. Therefore, even if it is chromate free, the coated metal plate which has the flat part corrosion resistance equivalent to or better than the coated metal plate including the metal plate subjected to the chromate rust prevention treatment can be provided.
D1 _{97.5 /} T ≦ 0.7
Ru ≦ 1.2T
R1 ≧ 1.0
0.5 ≦ D2 _97.5 /T≦7.0
3 ≦ T ≦ 20
1 ≦ L / D2 _97.5 ≦ 20

  In the manufacturing method, when the top coating material is subjected to a treatment for pulverizing particles in the top coating material, coarse particles that are unintentionally and irregularly present in the top coating film are substantially removed from the top coating material. Therefore, it is more effective from the viewpoint of improving the corrosion resistance of the flat portion of the coated metal plate.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, this invention is not limited by these Examples.

[Preparation of painted original plates 1 to 5]
A molten 55% Al—Zn alloy-plated steel sheet having a double-side adhesion amount of 150 g / m ² was alkali degreased (coating original sheet 1). Next, the following non-chromate antirust treatment solution at 20 ° C. is applied to the surface of the plated layer of the plated steel plate as a pretreatment for coating, and the plated steel plate is dried at 100 ° C. without being washed with water. A non-chromate rust-proof plated steel sheet (painted original sheet 2) having an adhesion amount of / m ² was obtained.
(Non-chromate anti-rust treatment liquid)
Hexafluorotitanic acid 55g / L
Hexafluorozirconic acid 10g / L
Aminomethyl-substituted polyvinylphenol 72g / L
Water rest

Moreover, the following primer coating of epoxy resin type is applied to the surface of the coating original plate 2, the chemical conversion treated steel sheet is heated so that the ultimate temperature of the plated steel sheet is 200 ° C., and the undercoat film has a dry film thickness of 5 μm. The above-mentioned chromate-free plated steel sheet (painted original sheet 3) was obtained.
Phosphate mixture 15% by volume
Barium sulfate 5% by volume
Silica 1% by volume
Clear paint

Further, instead of the chromate-free treatment solution, using “Surfcoat NRC300NS” (“Surfcoat” is a registered trademark of the company) made by Nippon Paint Co., Ltd., which is a chromate treatment solution, adhesion of 20 mg / m ^{2 in} terms of chromium The amount of chromate rust prevention treatment is applied, and then the following primer coating of epoxy resin is applied to the surface of the chromate rust prevention plated steel plate, and the above chemical conversion is made so that the ultimate temperature of the plated steel plate is 200 ° C. The treated steel plate was heated to obtain a plated steel plate (painted original plate 4) having a chromate-based undercoat film having an undercoat film having a dry film thickness of 5 μm.
Strontium chromate 15% by volume
Barium sulfate 5% by volume
Silica 1% by volume
Clear paint

  In the undercoat paint, the clear paint is “NSC680” manufactured by Nippon Fine Coatings Co., Ltd. In the undercoat paint, the phosphate mixture is a mixture of magnesium hydrogen phosphate, magnesium phosphate, zinc phosphate, and aluminum tripolyphosphate. Further, the silica is an extender, and the average particle diameter is 5 μm. Furthermore, the above volume% is a ratio to the solid content in the undercoat paint.

In addition, the following intermediate coating material of polyester type is applied to the surface of the coating original plate 3, the chemical conversion treatment steel plate is heated so that the ultimate temperature of the plated steel plate is 220 ° C., and dried on the undercoat coating film. The chromate-free plated steel sheet (painted original sheet 5) having an intermediate coating film thickness of 5 μm was obtained.
Carbon black 7% by volume
Silica particles 1 1% by volume
Polyester paint remaining

  The polyester-based paint is “CA clear paint” manufactured by Nippon Fine Coatings Co., Ltd., and is a polyester-based paint (PE). Carbon black is a coloring pigment. The volume% is a ratio with respect to the solid content in the intermediate coating.

[Preparation of gloss modifier]
Silica particles 1-9 (Sil-1-9), polyacrylonitrile (PAN) particles, and calcium carbonate-calcium phosphate complex (CaCPC) particles were prepared as gloss modifiers.

Each of the silica particles 1 to 9, the PAN particle, and the CaCPC particle is, for example, a classified product or a mixture thereof, and has a normal distribution-like particle size distribution. As shown in Table 1, the number average particle diameter (R1) of the silica particles 1 is 3.0 μm, the 97.5% particle diameter (D1 _97.5 ) in the number particle size distribution is 6.1 μm, The upper limit particle size (Ru) in the particle size distribution is 12.0 μm. Silica particle 2 has R1 of 1.0 μm, D1 _97.5 of 2.0 μm, and Ru of 2.6 m. R1 of the silica particle 3 is 1.0 μm, D1 _97.5 is 1.4 μm, and Ru is 1.5 m. R1 of the silica particles 4 is 8.2 μm, D1 _97.5 is 10.4 μm, and Ru is 18.8 m. The silica particle 5 has R1 of 5.5 μm, D1 _97.5 of 9.6 μm, and Ru of 10.8 m. R1 of the silica particles 6 is 3.7 μm, D1 _97.5 is 5.4 μm, and Ru is 7.0 m. R1 of the silica particles 7 is 0.7 μm, D1 _97.5 is 1.4 μm, and Ru is 2.0 m. R1 of the silica particles 8 is 5.0 μm, D1 _97.5 is 7.6 μm, and Ru is 14.0 m. R1 of the silica particle 9 is 7.5 μm, D1 _97.5 is 9.2 μm, and Ru is 14.8 m. In both PAN particles and CaCPC particles, R1 is 5.0 μm, D1 _97.5 is 7.6 μm, and Ru is 9.5 m.

[Preparation of matting agent]
As the matting agent, glass fibers 1 to 8 (Gla-1 to 8), ceramic (Cera) fibers, and potassium titanate (Pota-Ti) fibers shown in Table 2 were prepared. These glass fibers 1 to 8, ceramic fibers, and potassium titanate fibers all have no pores on the surface.

  Glass fibers 1 to 8, ceramic fibers, and potassium titanate fibers are all cut products of a desired fiber length of fibers having a desired fiber diameter. Accordingly, the fiber has a sufficiently sharp normal distribution-like particle size distribution with respect to the fiber diameter, and a very sharp particle size distribution with a normal distribution required for the fiber length.

[Preparation of top coat]
The following components were mixed in the following amounts to obtain a top coat.
Carbon black 7% by volume
Silica particles 1 5% by volume
Glass fiber 1 5% by volume
Clear paint 1 remaining

  The clear paint 1 is a “CA clear paint” manufactured by Nippon Fine Coatings Co., Ltd., and is a polyester paint (PE). Carbon black is a coloring pigment. The following volume% is a ratio with respect to the solid content in the top coat.

[Preparation of painted metal plate 1]
The top coating is applied to the surface of the undercoat film of the coating original plate 3, the coating original plate 3 is heated so that the temperature reached by the plated steel plate on the coating original plate 3 is 220 ° C., and an overcoat is applied with a dry film thickness T of 15 μm. A membrane was prepared. Thus, a coated metal plate 1 was produced.

The coated metal plate 1 is cut to expose its cross section, enclosed in an epoxy resin block, further polished, and the cross section taken with a scanning electron microscope. The particle size distribution of the silica particles 1 and the glass fibers 1 was determined by treating and analyzing the above, and R1, R2, D1 _97.5 , D2 _97.5, and Ru are substantially the same as the above numerical values. It was confirmed.

[Preparation of painted metal plates 2, 3, 6, 7]
A coated metal plate 2 was produced in the same manner as the coated metal plate 1 except that the amount of the top coating was changed so that the dry film thickness T was 13 μm. Further, a coated metal plate 3 was produced in the same manner as the coated metal plate 1 except that the coating amount of the top coating was changed so that the dry film thickness T was 10 μm. Further, a coated metal plate 6 was produced in the same manner as the coated metal plate 1 except that the coating amount of the top coating was changed so that the dry film thickness T was 20 μm. Further, a coated metal plate 7 was produced in the same manner as the coated metal plate 1 except that the amount of top coating applied was changed so that the dry film thickness T was 22 μm.

[Preparation of painted metal plates 4 and 5]
Use the silica particles 2 instead of the silica particles 1, use the glass fibers 2 instead of the glass fibers 1, and apply the amount of the top coat so that the dry film thickness T is 3 μm. A coated metal plate 4 was produced in the same manner as the painted metal plate 1 except that the coating metal plate 4 was changed.

  Further, the coated metal was used except that the silica particles 2 were used in place of the silica particles 1 as the gloss adjusting agent in the top coating and the coating amount of the top coating was changed so that the dry film thickness T was 2.2 μm. The coated metal plate 5 was produced in the same manner as the plate 4.

[Preparation of painted metal plates 8 to 11]
A coated metal plate 8 was produced in the same manner as the coated metal plate 1 except that the silica particles 4 were used in place of the silica particles 1 as the gloss modifier in the top coat. A coated metal plate 9 was produced in the same manner as the coated metal plate 2 except that the silica particles 5 were used in place of the silica particles 1 as the gloss modifier in the top coat. Further, a coated metal plate 10 was produced in the same manner as the coated metal plate 1 except that the silica particles 6 were used in place of the silica particles 1 as the gloss modifier in the top coat. Further, a coated metal plate 11 was produced in the same manner as the coated metal plate 1 except that the silica particles 7 were used in place of the silica particles 1 as the gloss adjusting agent in the top coat.

[Preparation of painted metal plates 12 to 17]
A coated metal plate 12 was produced in the same manner as the painted metal plate 1 except that the content of silica particles in the top coat was changed to 0.005% by volume. Further, a coated metal plate 13 was produced in the same manner as the painted metal plate 1 except that the content of silica particles in the top coat was changed to 0.01% by volume. Moreover, the coating metal plate 14 was produced like the coating metal plate 1 except having changed the content of the silica particle in top coat into 0.1 volume%. A coated metal plate 15 was produced in the same manner as the painted metal plate 1 except that the content of silica particles in the top coat was changed to 13% by volume. A coated metal plate 16 was produced in the same manner as the painted metal plate 1 except that the content of silica particles in the top coat was changed to 15% by volume. Further, a coated metal plate 17 was produced in the same manner as the coated metal plate 1 except that the content of silica particles in the top coat was changed to 20% by volume.

[Preparation of painted metal plates 18 to 24]
A coated metal plate 18 was produced in the same manner as the painted metal plate 1 except that the glass fiber 2 was used in place of the glass fiber 1 as the matting agent in the top coat. A coated metal plate 19 was produced in the same manner as the painted metal plate 1 except that the glass fiber 3 was used in place of the glass fiber 1 as the matting agent in the top coat. A coated metal plate 20 was produced in the same manner as the painted metal plate 1 except that the glass fiber 4 was used in place of the glass fiber 1 as the matting agent in the top coat. A coated metal plate 21 was produced in the same manner as the painted metal plate 1 except that the glass fiber 5 was used in place of the glass fiber 1 as the matting agent in the top coat. A coated metal plate 22 was prepared in the same manner as the painted metal plate 1 except that the glass fiber 6 was used in place of the glass fiber 1 as the matting agent in the top coat. A coated metal plate 23 was produced in the same manner as the coated metal plate 1 except that the glass fiber 7 was used in place of the glass fiber 1 as the matting agent in the top coat. A coated metal plate 24 was produced in the same manner as the coated metal plate 1 except that the glass fiber 8 was used in place of the glass fiber 1 as the matting agent in the top coat.

[Preparation of painted metal plates 25-30]
A coated metal plate 25 was produced in the same manner as the painted metal plate 1 except that the glass fiber content in the top coat was changed to 0.005% by volume. Further, a coated metal plate 26 was produced in the same manner as the coated metal plate 1 except that the glass fiber content in the top coat was changed to 0.01% by volume. A coated metal plate 27 was produced in the same manner as the painted metal plate 1 except that the glass fiber content in the top coat was changed to 0.1% by volume. A coated metal plate 28 was produced in the same manner as the painted metal plate 1 except that the glass fiber content in the top coat was changed to 13% by volume. A coated metal plate 29 was produced in the same manner as the painted metal plate 1 except that the glass fiber content in the top coat was changed to 15% by volume. A coated metal plate 30 was produced in the same manner as the coated metal plate 1 except that the glass fiber content in the top coat was changed to 20% by volume.

[Preparation of painted metal plates 31 to 33]
A coated metal plate 31 was produced in the same manner as the coated metal plate 1 except that a top coat film was formed on the coated original plate 1 instead of the painted original plate 3. Further, a coated metal plate 32 was produced in the same manner as the coated metal plate 1 except that a top coat film was formed on the painted original plate 2 instead of the painted original plate 3. Further, a coated metal plate 33 was produced in the same manner as the painted metal plate 1 except that a top coat film was formed on the painted plate 4 instead of the coated plate 3.

[Production of painted metal plates 34 and 35]
A coated metal plate 34 was produced in the same manner as the coated metal plate 33 except that the silica particles 5 were used in place of the silica particles 1 as the gloss modifier in the top coat. Further, a coated metal plate 35 was produced in the same manner as the coated metal plate 33 except that the silica particles 6 were used in place of the silica particles 1 as the gloss adjusting agent in the top coat.

[Preparation of painted metal plates 36 and 37]
A coated metal plate 36 was obtained in the same manner as the painted metal plate 1 except that the clear paint 2 was used instead of the clear paint 1 of the top coat. The clear paint 2 is a thermosetting acrylic resin paint “E41” manufactured by Nippon Fine Coatings Co., Ltd., and is an acrylic resin (AR) paint. Further, a coated metal plate 37 was obtained in the same manner as the painted metal plate 1 except that the clear paint 3 was used instead of the clear paint 1. The clear paint 3 is a thermosetting urethane resin paint “KP1101” manufactured by Kansai Paint Co., Ltd., and is a polyurethane (PU) paint.

[Preparation of painted metal plates 38 to 41]
A coated metal plate 38 was obtained in the same manner as the coated metal plate 1 except that polyacrylonitrile particles were used instead of the silica particles 1 of the top coat. Further, a coated metal plate 39 was obtained in the same manner as the coated metal plate 1 except that the calcium carbonate-calcium phosphate composite particles were used in place of the silica particles 1 of the top coat. A coated metal plate 40 was obtained in the same manner as the coated metal plate 1 except that the silica particles 8 were used instead of the silica particles 1 of the top coat. A coated metal plate 41 was obtained in the same manner as the coated metal plate 1 except that the silica particles 9 were used instead of the silica particles 1 of the top coat.

[Preparation of painted metal plates 42 and 43]
A coated metal plate 42 was produced in the same manner as the coated metal plate 1 except that ceramic fibers were used in place of the glass fibers 1 as the matting agent in the top coat. In addition, a coated metal plate 43 was produced in the same manner as the coated metal plate 1 except that potassium titanate fibers were used in place of the glass fibers 1 as the matting agent in the top coat.

[Preparation of painted metal plate 44]
Painted in the same way as the coated metal plate 1 except that the top coat film was formed on the painted base plate 1 instead of the painted base plate 3 and the coating amount of the top coat was changed so that the dry film thickness T was 10 μm. A metal plate 44 was produced.

[Evaluation]
The following measurements and tests were performed for each of the painted metal plates 1 to 44.

(1) 75 ° gloss (G75)
The specular glossiness (G75) at 75 ° defined by JIS K5600-4-7 (ISO 2813: 1994) of each of the painted metal plates 1 to 44 was measured with a gloss meter VG-2000 manufactured by Nippon Denshoku Co., Ltd. .

(2) Appearance of Appearance Each of the coated metal plates 1 to 44 was evaluated for the appearance of the top coat film after drying according to the following criteria.
(Evaluation criteria)
G: Abnormal gloss and coating film defects are not observed, flat, and matte appearance is recognized. NG1: Gloss is too high and matte appearance is not obtained (glossiness is greater than 25).
NG2: Wrinkles are seen during coating NG3: Streaks are seen during painting NG4: Insufficient concealment

(3) Scratch resistance A Clemens-type scratch test in which a load of 400 g was applied to each of the coated metal plates 1 to 44 using a 125 μmφ diamond needle was evaluated according to the following criteria.
(Evaluation criteria)
G: No scratch reaching the substrate (metal plate) NG: No scratch reaching the substrate (metal plate)

(4) Process part adhesiveness Each of the coated metal plates 1 to 44 was subjected to 0T bending (adhesion bending) process, a cellophane tape peeling test of the 0T bent part was performed, and the following criteria were evaluated.
(Evaluation criteria)
G: No peeling of coating film NG: Peeling of coating film is observed

(5) Flat part corrosion resistance For each of the coated metal plates 1 to 44, first, the xenon lamp method accelerated weathering test specified in JIS K5600-7-7 (ISO 11341: 2004) was conducted for 1,000 hours, and then A “neutral salt spray cycle test” (so-called JASO method) defined in JIS H8502 was conducted for 720 hours. The above two tests are carried out as one cycle, and for each of the coated metal plates 1 to 45, one cycle (the actual use durability is equivalent to about 5 years) test product and two cycles (the actual use durability is 10 years) Corresponding to the degree) Each of the test products was washed with water, visually and magnified with a 10-fold magnifier, and the presence or absence of swelling of the coating film on the flat portion of the coated metal plate was observed and evaluated according to the following criteria.
(Evaluation criteria)
A: No swelling is observed. B: Slightly minute swelling is observed in the enlarged observation, but the swelling is not visually recognized. C: The swelling is observed visually.

For coated metal plates 1 to 44, the type of coating original plate, the type of gloss adjusting agent, the type of matting agent, R1, R2, D1 _97.5 , D2 _97.5 , Ru, the type of resin of the top coat film, T Content of gloss adjusting agent, content of matting agent, value of D1 _97.5 / T, value of D2 _97.5 / T, value of Ru / T, and whether different from Examples or Comparative Examples It shows in Tables 3-5. Moreover, the result of the said evaluation of the coating metal plates 1-44 is shown in Table 6 and Table 7.

(5) Flat part corrosion resistance For each of the coated metal plates 1, 33, 34 and 35, the above-mentioned test relating to flat part corrosion resistance was conducted up to 3 cycles (equivalent to about 15 years of actual use). Each of these was washed with water, visually and magnified with a 10-fold magnifier, and the presence or absence of swelling of the coating film on the flat part of the coated metal plate was observed and evaluated according to the above-mentioned criteria. The results are shown in Table 8.

[Reference Experiment 1]
Particles having a particle size R1 ′ of 0.7 Tμm (T = 15 μm) or more were removed from the silica particles 1 to obtain silica particles 1 substantially free of particles of 10.5 μm or more. This is designated silica particle 10 (Sil-10). A coated metal plate 45 was prepared in the same manner as the coated metal plate 1 except that the silica particles 10 were used in place of the silica particles 1 as the gloss modifier in the top coat.

  Further, particles having a particle size R1 ′ of 0.8 Tμm (12.0 μm) or more are removed, and silica particles A substantially free of particles of 12.0 μm or more are separately prepared. 97.5 parts by volume of silica particles 10 is mixed with 2.5 volume parts of silica particles A, and is composed of 97.5 volume parts of silica particles 10 of 0.7 T or less and 2.5 volume parts of silica particles A of 0.8 T or less. Silica particles (content ratio: 97.5 / 2.5) were obtained. This is designated as silica particle 11 (Sil-11). A coated metal plate 46 was produced in the same manner as the coated metal plate 1 except that the silica particles 11 were used in place of the silica particles 1 as the gloss modifier in the top coat.

  Further, particles having a particle size R1 ′ of 0.9 Tμm (13.5 μm) or more are removed, and silica particles B substantially free of particles of 13.5 μm or more are separately prepared. 97.5 parts by volume of silica particles 10 is mixed with 2.5 volume parts of silica particles B, and is composed of 97.5 volume parts of silica particles 10 of 0.7 T or less and 2.5 volume parts of silica particles B of 0.9 T or less. Silica particles were obtained. This is designated as silica particle 12 (Sil-12). A coated metal plate 47 was produced in the same manner as the coated metal plate 1 except that the silica particles 12 were used in place of the silica particles 1 as the gloss modifier in the top coat.

  Further, particles having a particle size R1 ′ of 1.0 Tμm (15.0 μm) or more are removed, and silica particles C substantially free of particles of 15.0 μm or more are separately prepared. 97.5 parts by volume of silica particles 10 is mixed with 2.5 volume parts of silica particles C, and is composed of 97.5 volume parts of silica particles 10 of 0.7 T or less and 2.5 volume parts of silica particles C of 1.0 T or less. Silica particles were obtained. This is designated as Silica Particle 13 (Sil-13). And the coated metal plate 48 was produced like the coated metal plate 1 except having used the silica particle 13 instead of the silica particle 1 for the gloss regulator in top coat.

  In addition, silica particles D having a particle size R1 ′ of 1.1 Tμm (16.5 μm) or more are removed, and silica particles D substantially free of particles of 16.5 μm or more are separately prepared. 10 is mixed with 2.5 volume parts of silica particles D, and is composed of 97.5 volume parts of silica particles 10 of 0.7 T or less and 2.5 volume parts of silica particles D of 1.1 T or less. Silica particles were obtained. This is designated as silica particle 14 (Sil-14). A coated metal plate 49 was prepared in the same manner as the coated metal plate 1 except that the silica particles 14 were used in place of the silica particles 1 as the gloss modifier in the top coat.

  Further, particles having a particle size R1 ′ of 1.2 Tμm (18.0 μm) or more are removed, and silica particles E substantially free of particles of 18.0 μm or more are separately prepared. 10 is mixed with 2.5 volume parts of silica particles E, and is composed of 97.5 volume parts of silica particles 10 of 0.7 T or less and 2.5 volume parts of silica particles E of 1.2 T or less. Silica particles were obtained. This is designated silica particle 15 (Sil-15). And the coated metal plate 50 was produced like the coated metal plate 1 except having used the silica particle 15 instead of the silica particle 1 for the gloss regulator in top coat.

  Further, particles having a particle size R1 ′ of 1.3 Tμm (19.5 μm) or more are removed, and silica particles F substantially free of particles of 19.5 μm or more are separately prepared. 97.5 parts by volume of silica particles 10 is mixed with 2.5 volume parts of silica particles F, and is composed of 97.5 volume parts of silica particles 10 of 0.7 T or less and 2.5 volume parts of silica particles F of 1.3 T or less. Silica particles were obtained. This is designated as silica particle 16. A coated metal plate 51 was prepared in the same manner as the coated metal plate 1 except that the silica particles 16 were used in place of the silica particles 1 as the gloss modifier in the top coat.

About the coating metal plates 45-51, the flat part corrosion resistance was evaluated by the method of 2 cycles mentioned above. Coated metal plates 45 to 51, coating raw plate type, top coat resin type, T, gloss modifier type, R1, D1 _97.5 , cut value, added silica particle main component particle size R1 ', The content ratio of the two types of silica particles, the type of matting agent, the content of matting agent, and the evaluation results of the flat portion corrosion resistance are shown in Table 9.

[Reference Experiment 2]
By changing the content ratio of the silica particles 10 and the silica particles E in the silica particles 15, 97.0 parts by volume of the silica particles 10 of 0.7T or less and 3.0 parts by volume of the silica particles E of 1.2T or less. Silica particles composed of This is designated as silica particles 17. A coated metal plate 52 was prepared in the same manner as the coated metal plate 1 except that the silica particles 17 were used instead of the silica particles 1 as the gloss adjusting agent in the top coat.

  Moreover, the content ratio of the silica particle 10 and the silica particle E in the silica particle 15 is changed, and 96.5 volume parts of the silica particle 10 of 0.7 T or less and 3.5 of the silica particle E of 1.2 T or less are used. Silica particles composed of a volume part were obtained. This is referred to as silica particles 18. A coated metal plate 53 was prepared in the same manner as the coated metal plate 1 except that the silica particles 18 were used in place of the silica particles 1 as the gloss modifier in the top coat.

About the coating metal plates 52 and 53, the flat part corrosion resistance was evaluated by the test method of 2 cycles mentioned above. Coated metal plates 50, 52 and 53, the type of coating original plate, the type of resin of the top coat film, T, the type of gloss modifier, R1, D1 _97.5 , the cut value, and the main particles of added silica particles Table 10 shows the diameter R1 ′, the content ratio of the two types of silica particles, the type of matting agent, the content of the matting agent, and the evaluation results of the flat portion corrosion resistance.

[Reference Experiment 3]
A coated metal plate 54 was produced in the same manner as the painted metal plate 51 except that the top coat of the painted metal plate 51 was processed by a roller mill under the condition of pulverizing the silica particles F before blending the matting agent. The coated metal plate 54 was evaluated for flat portion corrosion resistance by the above-described two-cycle method. As a result, both determinations of 1 cycle and 2 cycles were B.

  As is clear from Tables 6 and 7, all of the painted metal plates 1 to 4, 6, 10, 13 to 16, 19, 20, 24, 26 to 29, and 31 to 44 have a matte gloss design. It has sufficient work part adhesion and scratch resistance, and has flat part corrosion resistance equivalent to actual use for 10 years.

  On the other hand, the coated metal plate 5 has insufficient concealability, that is, the visibility of the top coat film is expressed only to the extent that the undercoat (undercoat film) of the top coat film can be visually observed. Therefore, the desired design was not obtained. Moreover, the scratch resistance was insufficient. These are considered because the top coat film was too thin. In addition, in the coating metal plate 5, since the expected designability was not obtained, it judged that it was not worth performing the evaluation test of flat part corrosion resistance, and the said evaluation test was not implemented.

  In addition, the coated metal plate 7 was cracked when the top coat film was applied, and the desired designability was not obtained. For this reason, it judged that it was not worth performing the evaluation test of flat part corrosion resistance, and the said evaluation test was not implemented. The reason why the above design property was not obtained is considered that the film thickness of the top coat film was too thick.

Further, the coated metal plates 8 and 9 had insufficient flat portion corrosion resistance. This is considered because the gloss adjusting agent was too large for the film thickness of the top coat film. That is, in the coated metal plate 8, D1 _97.5 is too large, and in the painted metal plate 9, Ru is too large, so that the gloss modifier is exposed from the top coat during the durability test due to light degradation of the top coat. This is probably due to the fact that

  In addition, the coated metal plates 11 and 12 were both too glossy, and the desired design (matte appearance) was not obtained. This is presumably because the particle size of the gloss adjusting agent was too small in the coated metal plate 11 and the content of the gloss adjusting agent was insufficient in the coated metal plate 12. In the coated metal plates 11 and 12, since the expected designability was not obtained, it was judged that it was not worth performing an evaluation test of the flat portion corrosion resistance, and the evaluation test was not performed.

  Further, the painted metal plate 17 was streaked during the coating of the top coat film, and the desired designability was not obtained. This is presumably because the gloss adjusting agent content was too much. In the coated metal plate 17, since the desired designability was not obtained, it was determined that it was not worth performing an evaluation test of the flat portion corrosion resistance, and the evaluation test was not performed.

Further, both the coated metal plates 18 and 22 had insufficient scratch resistance. Therefore, the evaluation test of the flat portion corrosion resistance could not be performed. The reason why the scratch resistance was insufficient was considered that the matting agent was too small, that is, D2 _97.5 / T was too small for the coated metal plate 18 and L / D2 _{97 for the} painted metal plate 22. _.5 is too small.

Moreover, as for the coating metal plates 21 and 23, the process part adhesiveness was inadequate. Therefore, the evaluation test of the flat portion corrosion resistance could not be performed. The reason why the processed part adhesion of the coated metal plate 21 was insufficient was considered to be because D2 _97.5 / T was too large, and the processed part adhesion of the coated metal plate 23 was insufficient. , L / D2 _97.5 is too large.

  Further, the coated metal plate 25 had a glossiness that was too high, and the scratch resistance was insufficient. Therefore, the evaluation test of the flat portion corrosion resistance could not be performed. This is probably because the content of the matting agent was too small.

  Further, the coated metal plate 30 was streaked during coating of the top coat film, and the processed part adhesion was insufficient. Therefore, the evaluation test of the flat portion corrosion resistance could not be performed. This is considered because the content of the matting agent was too much.

  In addition, the painted metal plates 31 to 33 all exhibit the desired design (matte) regardless of the type of the coated original plate, and have sufficient work adhesion, scratch resistance, and flat part corrosion resistance. Was. This is thought to be because the flat portion corrosion resistance is provided by the top coat film.

  In addition, both of the coated metal plates 36 and 37 exhibit the desired design (matte) regardless of the type of resin of the top coat film, and have sufficient work adhesion, scratch resistance and flat part corrosion resistance. Had. This is considered to be because, if the resin has sufficient durability to be used for the top coat film, the flat portion corrosion resistance is exhibited regardless of the type of resin constituting the top coat film.

  In addition, both painted metal plates 38 and 39 exhibit the desired design (matte) regardless of the type of gloss modifier, and have sufficient work adhesion, scratch resistance, and flat part corrosion resistance. Was. This is considered to be because, even if the particles have pores, regardless of whether they are inorganic particles or organic particles, sufficient flat portion corrosion resistance is exhibited if they are not exposed from the surface of the top coat film.

  In addition, both of the coated metal plates 42 and 43 exhibit the desired design (matte) regardless of the type of matting agent, and have sufficient work adhesion, scratch resistance, and flat part corrosion resistance. Was. This is considered to be because the above-mentioned properties are sufficiently expressed if the fibrous matting agent has a sufficient size regardless of whether it is an inorganic particle or an organic particle.

  Moreover, the coated metal plate 44 showed excellent results in any evaluation. This is because the coated metal plate 44 has an intermediate coating film, so that the design and functionality of the intermediate coating film are imparted, and as a result, the design and functionality expressed only by the top coating film are better. This is thought to be due to the manifestation of various characteristics.

  Further, as apparent from Table 8, all of the coated metal plates 33, 34 and 35 maintain the flat portion corrosion resistance for a longer period than the painted metal plate 1. This is because the coating original plate 4 in the coated metal plates 33, 34 and 35 contains a chromate rust preventive pigment in the undercoat coating film and the plated steel plate is subjected to a chromate rust prevention treatment. This is probably because it has higher corrosion resistance than the coating original plate 3 in FIG.

  Further, as apparent from Table 9 and Table 10, if the gloss modifier is particles up to 1.2 times (1.2 T) the film thickness of the top coat film, particles larger than 0.7 T It can be seen that even if it is contained up to at least 2.5% by volume of particles of 0.7T or less, no substantial adverse effect is exerted on the flat portion corrosion resistance of the coated metal plate. This is because particles whose size is slightly larger than the film thickness T of the top coat film are likely to be arranged in a direction in which the major axis is along the direction of application of the top coat. This is thought to be because the resin continues to be sufficiently covered.

  Further, the gloss adjusting agent may contain a small amount of large particles (coarse particles) that can be detected at positions deviating from the particle size distribution. As is apparent from Table 9, such coarse particles are considered to be exposed from the top coat film during durable use and cause the flat portion corrosion resistance of the coated metal plate to be impaired. However, when an appropriate pulverization step is applied to the top coating material containing the coarse particles, a coated metal plate having sufficient flat portion corrosion resistance can be obtained. This is presumably because the coarse particles are pulverized small enough in the top coat to a degree sufficient for the coated metal plate to exhibit the desired flat portion corrosion resistance.

  In the coated metal plate according to the present invention, it is possible to prevent the deterioration of the corrosion resistance at the flat portion due to the exposure, collapse, and drop-off of the gloss modifier from the top coat film, and the exposure, crack, collapse, and drop-off of the matting agent. The Therefore, even if it is used for a long period of time for exterior use, a coated metal plate that exhibits the desired appearance and corrosion resistance for a long period of time can be obtained. Therefore, the present invention is expected to further extend the life and further promote the use of the coated metal sheet for exterior use.

Claims (12)

A coated metal plate having a metal plate and a top coat film disposed on the metal plate,
The top coat film contains a gloss adjusting agent which is a particle having pores and a matting agent which is a fibrous inorganic substance ,
The content of the gloss modifier in the top coat film is 0.01 to 15% by volume,
The content of the matting agent in the top coat film is 0.01 to 15% by volume,
The number average particle diameter of the gloss modifier is R (μm), the film thickness of the top coat film is T (μm), and the 97.5% particle diameter in the cumulative particle size distribution of the gloss modifier is D1 _{97. 5} (μm), D2 _97.5 (μm) of 97.5% fiber diameter in the number-based cumulative particle size distribution of the matting agent, and Ru ( μm), a coated metal plate that satisfies the following formula when the average fiber length of the matting agent is L (μm).
D1 _{97.5 /} T ≦ 0.7
Ru ≦ 1.2T
R ≧ 1.0
0.5 ≦ D2 _97.5 /T≦7.0
3 ≦ T ≦ 20
1 ≦ L / D2 _97.5 ≦ 20   The painted metal plate according to claim 1, wherein Ru is less than T. The metal plate is subjected to non-chromate rust prevention treatment,
The painted metal plate is chromate-free,
The painted metal plate according to claim 1 or 2.   The said metal plate is a coating metal plate of Claim 1 or 2 with which the chromate rust prevention process was performed.   The coated metal plate according to any one of claims 1 to 4, wherein the gloss adjusting agent is silica particles.   The coated metal plate according to any one of claims 1 to 5, further comprising an undercoat film between the metal plate and the topcoat film.   The coated metal plate according to claim 6, further comprising an intermediate coating film between the undercoating film and the top coating film.   The coated metal plate according to any one of claims 1 to 7, wherein the glossiness at 75 ° is 1 to 25.   The coated metal plate according to any one of claims 1 to 8, which is a coated metal plate for exterior use.   The exterior building material comprised with the coating metal plate as described in any one of Claims 1-8. A method for producing a coated metal plate having a metal plate and a top coat film disposed on the metal plate,
Applying a top coat containing a resin, a gloss modifier and a matting agent on the metal plate;
Curing the coating film of the top coating material to form the top coating film; and
Including
The content of the gloss modifier in the top coat film is 0.01 to 15% by volume,
The content of the matting agent in the top coat film is 0.01 to 15% by volume,
The gloss modifier is a particle having pores,
The matting agent is a fibrous inorganic substance ,
The number average particle diameter of the gloss modifier is R (μm), the film thickness of the top coat film is T (μm), and the 97.5% particle diameter in the cumulative particle size distribution of the gloss modifier is D1 _{97. 5} (μm), 97.5% fiber diameter in the cumulative particle size distribution based on the number of fiber diameters of the matting agent is D2 _97.5 (μm), and the upper limit particle diameter of the number particle size distribution of the gloss modifier is Ru ( μm), a method for producing a coated metal plate using the gloss adjusting agent and the matting agent satisfying the following formula when the average fiber length of the matting agent is L (μm).
D1 _{97.5 /} T ≦ 0.7
Ru ≦ 1.2T
R ≧ 1.0
0.5 ≦ D2 _97.5 /T≦7.0
3 ≦ T ≦ 20
1 ≦ L / D2 _97.5 ≦ 20 The method for producing a coated metal plate according to claim 11, wherein the top coating is subjected to a process of pulverizing particles in the top coating.