JP6880922B2 - Painted metal plate - Google Patents

Description

The present invention relates to a painted metal plate.

The painted metal plate is generally excellent in durability, weather resistance and design, and is preferably used as an exterior building material, for example. Among the coated metal plates for exterior building materials, the coated metal plate having a coating film made of fluororesin is suitable for the coated metal plate that requires long-term durability. Such a fluororesin-based coated metal plate has a transparent coating film made of a mixed resin of polyvinylidene fluoride and an acrylic resin on the surface of the stainless steel plate, and the transparent coating film has a specific degree of crystallinity and hardness. A fluororesin-based coated stainless steel plate having a fluororesin coating is known (see, for example, Patent Document 1), and has a fluororesin-based coloring layer containing a fluororesin, an acrylic resin, an inorganic fired pigment, and an organic pigment on the surface of the steel plate. , And a fluororesin-based coated steel plate having a coating film made of polyester having a specific glass transition temperature on the back surface of the steel plate is known (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2001-09367 Japanese Unexamined Patent Publication No. 2008-0872242

However, in a fluororesin-based coating film, crystallization of the fluororesin generally progresses over time, so that the ductility of the coating film may decrease. That is, the molecules of the fluororesin move relatively easily in a temperature range above the glass transition temperature (for example, about −40 ° C. in the case of polyvinylidene fluoride). The fluororesin is generally a polymer having crystallinity, and in the temperature range above the glass transition temperature described above, it has an irregular molecular arrangement structure (amorphous structure) to a regular molecular arrangement structure (crystal structure). Has the property of changing to. Then, the crystallized fluororesin has a strong binding force between its molecular chains. Therefore, the ductility of the fluororesin-based coating film on the fluororesin-based coated metal plate that has been stored for a long period of time tends to be low.

Therefore, in the fluororesin-based coated metal plate, the fluororesin-based coating film has high ductility immediately after its production, so that the coating film does not break (coating cracking) during the molding process, but for a long period of time after production. If the fluororesin-based coating film is molded after being stored, the fluororesin-based coating film may be broken because the ductility is reduced. For this reason, the fluororesin-based coated metal plate after long-term storage may not simultaneously satisfy the three performances required, for example, workability, designability (freedom of coloring), and low glossiness. The exterior building material produced in use may not exhibit the desired performance.

An object of the present invention is to provide a fluororesin-based coated metal plate having sufficient processability, designability and low gloss even after long-term storage.

It is known that the decrease in ductility of the fluororesin-based coating film over time is a phenomenon observed only when the fluororesin-based coating film contains a pigment. The present inventor has investigated in detail the relationship between the pigment in the fluororesin-based coating film and the decrease in ductility of the coating film, and as a result, the particle size and content of the pigment in the coating film are within a specific range. It was found that if it is inside, the decrease in workability with time is suppressed.

The present invention has a metal plate, a colored coating film arranged on the metal plate, and a gloss adjusting coating film arranged on the colored coating film, as one means for solving the above problems. In the metal plate, the colored coating film contains a base resin containing a fluorine resin and constituting the film structure of the colored coating film, and pigment particles containing colored pigment particles and dispersed in the colored coating film. It is contained, the thickness of the colored coating film is 50 μm or less, the content of the pigment particles in the colored coating film is 12% by volume or less, and the content of the colored pigment particles in the colored coating film is 2 volumes. % Or more, and the content of particles having a particle size of more than 3 μm in the colored coating film is 1% by volume or less, and a coated metal plate satisfying either the following condition 1 or condition 2 is provided.
[Condition 1] The gloss-adjusting coating film is composed of a topcoat base resin containing a fluororesin, and also contains spherulites that form irregularities on the surface of the gloss-adjusting coating film of the topcoat base resin. Moreover, the arithmetic mean roughness of the surface of the gloss adjusting coating film is 50 nm or more.
[Condition 2] The gloss-adjusting coating film contains a topcoat base resin constituting the film structure, and does not contain spherulites forming irregularities on the surface of the gloss-adjusting coating film of the topcoat base resin. Moreover, the arithmetic mean roughness of the surface of the gloss adjusting coating film is 200 nm or more.

According to the present invention, it is possible to provide a fluororesin-based coated metal plate having sufficient workability, designability and low gloss even after long-term storage.

It is a photographic image which shows an example of the spherulite in the gloss-adjusting coating film which photographed the surface of the gloss-adjusting coating film in the coated metal plate of this invention by the electron microscope at a magnification of 2000 times.

The coated metal plate according to the embodiment of the present invention includes a metal plate, a colored coating film arranged on the metal plate, and a gloss adjusting coating film arranged on the colored coating film.

The metal plate can be selected from known metal plates as long as the effect in the present embodiment can be obtained. 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, and stainless steel sheet (austenite type, martensite type, ferrite type, ferrite). -Includes martensite two-phase system), aluminum plates, aluminum alloy plates and copper plates.

The metal plate is preferably a plated steel plate or a stainless steel plate from the viewpoint of corrosion resistance and weight reduction, and is preferably a plated steel plate from the viewpoint of cost effectiveness. Further, the metal plate 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. is there.

The thickness of the metal plate can be appropriately determined based on the intended use of the coated metal plate and the like. For example, the thickness of the metal plate is preferably 0.2 to 3.0 mm when the coated metal plate is used as an exterior building material, and from the viewpoint of workability for that purpose, 0.25 to 2 It is preferably 0.0 mm.

The colored coating film contains a fluororesin, a base resin constituting the film structure of the colored coating film, and pigment particles dispersed in the colored coating film.

The thickness of the colored coating film is 50 μm or less. The thickness of the colored coating film can be expressed by the average value of the distances from the bottom surface to the surface at a plurality of locations (for example, 10 arbitrarily selected locations) of the colored coating film. If the thickness exceeds 50 μm, it is necessary to increase the amount of the colored paint applied when producing the colored coating film, and when the film of the paint is heated and cured, armpits (foam-like blisters and holes) are required. ) Is likely to occur as a coating defect. In addition, since the coating amount is large, it is disadvantageous in terms of cost.

The thickness of the colored coating film is appropriately set within the range of the above thickness based on various factors such as the content of the colored pigment, the color tone, the degree of ultraviolet shielding, and the degree of processing during the molding process of the coated metal plate. It is possible to decide.

For example, the thickness of the colored coating film is such that the higher the content of the colored pigment, the lower the color tone brightness (L value specified in JIS) of the colored pigment, or the higher the ultraviolet shielding degree, the more the colored coating film is thickened. Since it is excellent in color development (color hiding property against the color of the base) and the ultraviolet shielding rate to the base, it can be reduced. Further, when the degree of processing is low, the ductility required for the colored coating film is low, so that the thickness of the colored coating film can be reduced.

Further, for example, from the viewpoint of maintaining long-term adhesion between the colored coating film and its base (suppressing interface breakage for a long period of time), it is preferable to reduce the ultraviolet transmittance of the colored coating film, and for that purpose, the colored coating film is used. It is preferable to increase the thickness of. Further, in general, when a tensile stress is applied to a coating film, even if the elongation displacement is the same, the lower the film thickness, the higher the elongation deformation strain. Therefore, from the viewpoint of reducing the elongation deformation strain, the thickness of the colored coating film is preferably large.

As described above, the lower limit of the thickness of the colored coating film cannot be unconditionally stated, but for example, the degree of processing is equivalent to the degree of processing of 4T, and the L value of the colored pigment particles (for example, titanium oxide particles) is If it exceeds 80, the thickness of the colored coating film is preferably 20 μm or more, and more preferably 25 μm. Further, when the degree of processing is as described above and the L value of the colored pigment particles (for example, iron-chromium-based fired pigment particles) is 70 or less, the thickness of the colored coating film is preferably 15 μm or more, preferably 18 μm or more. Is more preferable.

The content of the pigment particles in the colored coating film is 12% by volume or less. The pigment particles include colored pigment particles and may further contain other pigment particles.

The pigment particles are in the colored coating film and do not deform even if the colored coating film is deformed, and suppress the deformation of the coating film. Therefore, if the content exceeds 12% by volume, the effect of suppressing deformation of the coating film due to the pigment particles is enhanced, and the ductility of the colored coating film may be insufficient.

The content of the colored pigment particles in the colored coating film is 2% by volume or more. The colored pigment is contained in the colored coating film for the purpose of imparting designability. Therefore, if the content is less than 2% by volume, the coloring and color hiding by the coloring pigment particles are insufficient, the underlying color is transparent, and the designability may be insufficient. Further, the fluororesin, which is a base resin described later, has a property of transmitting ultraviolet rays, and if the content of the colored pigment particles is less than 2% by volume, the amount of ultraviolet rays irradiated to the base of the colored coating film in an outdoor environment. There is a possibility that the adhesiveness at the interface between the base and the colored coating film will decrease at an early stage, and the colored coating film will peel off from the base.

For the content of the pigment particles in the colored coating film, for example, the cross section of the colored coating film is magnified and observed with a microscope or the like, and the cross-sectional area of the pigment and the resin in an arbitrary range (for example, the range of the colored coating film thickness × 200 μm width) is determined. It can be obtained by measuring and calculating this ratio.

The content of particles having a particle size of more than 3 μm in the colored coating film is 1% by volume or less. Here, the "particle size" means the size of the particles in the colored coating film, and when the pigment particles are present in the colored coating film as primary particles, it may be the primary particle size or the pigment. When the particles are agglomerated, it may be the particle size of the agglomerated particles.

In the molding process of a coated metal plate, tensile stress is applied to the surface of the coating film that the coated metal plate has. When the extensibility of the coating film is low, the coating film may be broken and a part of the underlying metal plate may be exposed. When exposed for a long period of time in an outdoor environment, a situation occurs in which the metal plate is in direct contact with factors that promote metal corrosion such as water and chloride ions for a long period of time, and the metal plate starts from the exposed part of the metal plate. Corrosion may progress. On the other hand, when the coating film has high extensibility, the coating film does not break and the underlying metal plate is not exposed to the outside world. Therefore, the progress of corrosion of the underlying metal plate can be suppressed for a long period of time, and long-term durability is exhibited.

If the content of the particles having a particle size of more than 3 μm in the colored coating film exceeds 1% by volume, the ductility of the colored coating film becomes insufficient, and the above-mentioned underlying metal plate may be corroded. From the viewpoint of the long-term durability, the smaller the content is, the more preferable, and it is most preferable that the colored coating film does not contain the particles.

The base resin contains a fluororesin. The fluororesin may be one kind or more. Examples of the above-mentioned fluororesin components include fully fluorinated resins in which all hydrogen atoms of hydrocarbon groups in the resin are replaced with fluorine atoms, such as polytetrafluoroethylene, and polyvinyl fluoride and vinylidene fluoride. Included are partially fluorinated resins, such as trifluorinated ethylene, in which some of the fluorine atoms of a fully fluorinated resin are replaced by other atoms such as hydrogen and chlorine atoms. The fluororesin is excellent in durability, chemical resistance, heat resistance, abrasion resistance, stain resistance, etc., and is particularly polyvinylidene fluoride (PVDF) because it has high processability and mechanical strength. preferable.

The base resin may further contain a resin other than the fluororesin. The base resin may or may not be bonded to each other. The other resins mentioned above may be one kind or more, and examples thereof include acrylic resins. The acrylic resin contributes to the improvement of coating film adhesion. The acrylic resin is preferably a thermoplastic acrylic resin or a thermosetting acrylic resin having compatibility with polyvinylidene fluoride. Examples of the acrylic resin include polymers of acrylic monomers such as methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and butyl methacrylate, or copolymers of monomers containing the acrylic monomers.

The content of the fluororesin in the base resin can be appropriately determined within the range in which the effect of the present embodiment can be obtained, and is preferably, for example, 50 to 85% by mass, preferably 70 to 85% by mass. Is more preferable. For example, the base resin may be composed of 50 to 85% by mass of a fluororesin and a residual acrylic resin. For example, the base resin is preferably a resin having a mass ratio (PVDF: AR) of polyvinylidene fluoride (PVDF) and an acrylic resin (AR) of 50:50 to 85:15. If the mass ratio of polyvinylidene fluoride is too low, the properties of the fluororesin such as weather resistance, corrosion resistance, and stain resistance may not be fully exhibited, and if the mass ratio of polyvinylidene fluoride is too high, the colored coating may not be exhibited. The adhesion of the film may decrease, and the processability of the coated metal plate may decrease.

The colored pigment particles may be one kind or more, and may be either organic colored pigment particles or inorganic colored pigment particles generally available as colored pigments for paints. The colored pigment particles are non-transparent and give a color tone to the colored coating film.

Examples of the above-mentioned inorganic coloring pigments include titanium oxide, chromium oxide, carbon black, iron black, iron oxide yellow, titanium yellow, red iron oxide, navy blue, cobalt blue, cerulean blue, ultramarine blue, cobalt green, and molybdenum red. included.

Examples of the above organic coloring pigments include Kinacridon Red, Resole Red B, Brilliant Scarlet G, Pigment Scarlet 3B, Brilliant Carmine 6B, Lake Red C, Lake Red D, Permanent Red 4R, Bordeaux 10B, Fast Yellow G, Fast Yellow. Includes 10G, Parared, Watching Red, Benzidine Yellow, Benzidine Orange, Bonmaroon L, Bonmaroon M, Brilliant Fast Scarlet, Vermilion Red, Phtalocyanin Blue, Phtalussin Green, Fast Sky Blue, and Aniline Black.

The colored pigment particles may be particles of a composite oxide calcined pigment containing a metal component, and examples of the calcined pigment include CoAl, CoCrAl, CoCrZnMgAl, CoNiZnTi, CoCrZnTi, NiSbTi, CrSbTi, FeCrZnNi, MnSbTi, FeCr. , FeCrNi, FeNi, FeCrNiMn, FeZn, CoCr, MnCo, and SnZnTi.

Further, the colored pigment particles may be metallic pigment particles, and examples of the metallic pigment particles include Al flakes, resin-coated Al flakes, metal oxide-coated Al flakes, Ni flakes, Cu flakes, and. Includes stainless steel flakes.

Further, the colored pigment particles may be particles of a pearl pigment, and examples of the pearl pigment particles include titanium oxide-coated mica, iron oxide-coated mica, and titanium oxide-iron oxide-coated mica.

The number average particle diameter of the colored pigment particles can be appropriately determined within the range in which the effect of the present embodiment can be obtained, and is usually 3 μm or less, for example, 0.01 to 1.5 μm. When the particle size of the colored pigment particles is smaller, the content of the colored pigment particles in the colored coating film can be increased. From this viewpoint, the average particle size of the colored pigment particles is 2.0 μm or less. It is preferably 0.5 μm or less, and more preferably 0.5 μm or less. For example, if the average particle size is 2.0 μm or less, it is usually possible to contain up to 5% by volume of colored pigment particles in the colored coating film, and if the average particle size is 0.5 μm or less, coloring is possible. The coating film can contain up to 10% by volume of colored pigment particles.

Examples of other pigment particles that the colored coating film may contain include gloss modifier particles and extender pigment particles.

The gloss adjusting agent particles can be used from the viewpoint of imparting desired gloss to the colored coating film or from the viewpoint of forming irregularities on the upper surface of the colored coating film. The gloss modifier particles may be more even one species, examples of the material include inorganic materials such as silica or calcium carbonate, and acrylic resin or urethane resin, benzo grayed Anamin resins, styrene resins, polyethylene resins, polypropylene Resins, resin materials such as fluororesins, etc. are included. The particle size of the gloss adjusting agent particles contained in the colored coating film is 3 μm or less. Since the average particle size of commercially available gloss adjuster particles is usually more than 3 μm, when using commercially available gloss adjuster particles, particles having a particle size of 3 μm or less may be separated and used by classification, or The content is preferably less than 1% by volume.

The content of the gloss adjusting agent particles in the colored coating film varies depending on, for example, the particle size of the gloss adjusting agent particles, but the desired design property is exhibited by blending the gloss adjusting agent particles in the colored coating film. From the viewpoint of the above, it is preferably 0.2 to 1.0% by volume.

Alternatively, from the viewpoint of adjusting the gloss of the colored coating film and improving the adhesion of the gloss adjusting coating film to the colored coating film by the anchor effect at the interface of the colored coating film, the particles of the gloss adjusting agent particles in the colored coating film. The diameter is preferably larger (for example, the above particle size is more than 3 μm), and the content thereof is preferably 0.2% by volume or more. As described above, the content is preferably 1.0% by volume or less from the viewpoint of processability after storage.

The extender pigment particles are pigments contained in the coating film from the viewpoint of adjusting the hardness of the coating film and reducing the cost of the coating film (the effect of increasing the bulk), and generally do not affect the color tone of the coating film. Since the extender pigment particles are usually cheaper than the fluororesin, it is preferable that the colored coating film contains the extender pigment particles within the range in which the effect of the present embodiment can be obtained. Further, it is preferable that the extender pigment particles have a high transmittance of visible light. The extender pigment particles may be one or more, and examples thereof include particles of barium sulfate, titanium oxide, silica and calcium carbonate. For example, the number average particle size of the extender pigment particles is 0.01 to 1 μm, and the content of the extender pigment particles in the colored coating film is, for example, 0.1 to 10% by volume.

The colored coating film may further contain additives other than the above-mentioned base resin and pigment particles as long as the effects of the present embodiment can be obtained. For example, the colored coating film may contain 10% by volume or less of an ultraviolet absorber or a light stabilizer from the viewpoint of further improving the weather resistance. Further, as the additive, the colored coating film may further contain one or more of a plasticizer, a dye, an antioxidant, an antistatic agent, a surfactant and a dispersion aid.

The gloss-adjusting coating film has a specific surface roughness that realizes low glossiness, and the surface roughness varies depending on the composition of the gloss-adjusting coating film. The gloss adjusting coating film satisfies either the following condition 1 or condition 2.
[Condition 1] The gloss-adjusting coating film is composed of a topcoat base resin containing a fluororesin, and also contains spherulites that form irregularities on the surface of the gloss-adjusting coating film of the topcoat base resin. Moreover, the arithmetic mean roughness of the surface of the gloss adjusting coating film is 50 nm or more.
[Condition 2] The gloss-adjusting coating film contains a topcoat base resin constituting the film structure, and does not contain spherulites forming irregularities on the surface of the gloss-adjusting coating film of the topcoat base resin. Moreover, the arithmetic mean roughness of the surface of the gloss adjusting coating film is 200 nm or more.

Under the above condition 1, the arithmetic mean roughness of the gloss adjusting coating film is 50 nm or more. Under the above condition 1, when the surface roughness is 50 nm or more, in addition to the light scattering effect due to the unevenness of the surface, the light scattering effect at the crystal grain boundary is added, and the mirror glossiness at 60 ° of the coated metal plate is 40. The following is realized, and a low-gloss painted metal plate is realized. The surface roughness can be appropriately determined from the viewpoint of glossiness and designability required for the coated metal plate, but it is more preferably 100 nm or more from the viewpoint of further reducing the mirror surface glossiness. It is more preferably 300 nm or more, and on the other hand, it is preferably 400 nm or less from the viewpoint that the gloss reducing effect reaches a plateau.

Under the above condition 2, the low glossiness is substantially exhibited only by the light scattering effect on the surface of the gloss adjusting coating film. In condition 2, when the arithmetic mean roughness is 200 nm or more, the mirror surface glossiness of the coated metal plate at 60 ° is 40 or less, and a low-gloss coated metal plate is realized. The surface roughness can be appropriately determined from the viewpoint of glossiness and designability required for the coated metal plate, but is more preferably 300 nm or more from the viewpoint of further reducing the mirror surface glossiness. On the other hand, from the viewpoint that the gloss reduction effect reaches a plateau, it is preferably 4000 nm or less.

In addition, in condition 2, "does not contain spherulite" means that the said spherulite is not contained enough to satisfy the said condition 1. Therefore, under condition 2, the gloss adjusting coating film may contain the above spherulite in an amount less than the amount satisfying condition 1.

The surface roughness can be determined by using a known measuring device of either a contact type or a non-contact type. Examples of contact measuring devices include contact roughness meters and atomic force microscopes. Examples of non-contact measuring devices include white interferometers, laser microscopes, and electron microscopes.

The gloss adjusting coating film is usually composed of a base resin (also referred to as "topcoat base resin"). The topcoat base resin may be appropriately determined from known resins based on the above conditions 1 and 2 and within the range in which the effects of the present embodiment can be obtained, and may be one kind or more. Examples of the topcoat base resin include the completely fluorinated resin, the partially fluorinated resin, the polyester resin, the modified silicon resin, the acrylic resin, the urethane resin, and the vinyl chloride resin.

The topcoat base resin is preferably a polyester resin, a completely fluorinated resin, a partially fluorinated resin, or a vinyl chloride resin from the viewpoint of durability in an outdoor environment, and further from the viewpoint of adhesion to a colored coating film. It is preferably a fully fluorinated resin or a partially fluorinated resin. The fluororesin may be the same as or different from that of the base resin in the colored coating film. The content of the fluororesin in the topcoat base resin is preferably 50 to 85% by mass from the same viewpoint as that in the colored coating film, for example.

The thickness of the gloss adjusting coating film can be appropriately determined within the range in which the effect of the present embodiment can be obtained, and is preferably 0.01 to 25 μm, more preferably 3 to 15 μm. If the thickness is 0.01 μm or less, it may be difficult to achieve an arithmetic mean roughness of 50 nm or more. If the thickness is 25 μm or more, the color tone of the gloss adjusting coating film itself (for example, the light yellow color exhibited by polyvinylidene fluoride) may become strong, and the design of the coated metal plate may be insufficient. Paint costs are higher. The film thickness of the gloss-adjusting coating film is represented by the average value of the distances from the bottom surface to the surface at a plurality of locations (for example, any 10 locations) of the gloss-adjusting coating film.

The arithmetic mean roughness of the gloss-adjusting coating film can be realized by a known method. An example of the method for realizing the arithmetic mean roughness includes crystallization of the topcoat base resin in the gloss adjusting coating film under the above condition 1, and the gloss adjusting coating film under the above condition 2. Includes adding gloss adjusting agent particles to the surface of the gloss adjusting coating film, transferring the uneven shape to the surface of the gloss adjusting coating film, and grinding the surface of the gloss adjusting coating film.

In the case of the above condition 1, the crystallization of the topcoat base resin is carried out by using a resin having crystallization as the topcoat base resin and preparing the gloss adjusting coating film under the condition that the topcoat base resin is crystallized. It is possible to realize it. For example, the crystallization can be carried out by the method described in Patent Document 1 using a fluororesin as the topcoat base resin.

Usually, a part of the molecular chain of a crystalline polymer forms a crystal structure in the process of cooling from the melting temperature to the crystallization temperature or lower. For example, in polyvinylidene fluoride, crystals (spherulite) having a large crystal grain size (particle size: 0.1 to several tens of μm) called α crystals are generated and grow in the crystallization temperature range. In the crystallization temperature range, the time required for the formation of α crystals having a particle size of about 10 μm is, for example, about 1 second. Therefore, by producing the gloss-adjusting coating film by slow cooling, the time of staying in the crystallization temperature range during cooling becomes longer, and many large α crystals are generated in the coating film.

However, when a gloss-adjusting coating film is produced by quenching, the α crystals in the coating film are small and the number of crystal grains is small because the time for staying in the crystallization temperature range is short. In addition to α crystals, crystals with a small particle size (1 μm or less) called β crystals are likely to be generated. In the gloss-adjusting coating film composed of polyvinylidene fluoride, the phases of α-crystal, β-crystal and amorphous portion may be present depending on the cooling rate in the production thereof. Further, the crystal grows even in the above crystallization temperature range, for example, at room temperature, but the growth rate is extremely slower than the growth rate in the above crystallization temperature range, and the crystal grain size produced is usually less than 1 μm.

In the case of the above condition 1, the volume of the coating film shrinks due to the crystallization of the resin in the gloss adjusting coating film in the manufacturing process, and unevenness is formed on the surface thereof. When the spherulite is large and the number of spherulites is increased, the area of the uneven portion becomes large, and the arithmetic mean roughness can be sufficiently increased. In order to obtain a low-gloss surface in the gloss-adjusting coating film, unevenness due to α crystals having a large size is preferable. The unevenness formed by β-crystals has a small height, and a surface with a desired low mirror glossiness may not be obtained.

As described above, the gloss adjusting coating film satisfying the above condition 1 is composed of, for example, a fluororesin-containing topcoat base resin and contains spherulites of the topcoat base resin. It is preferable that the average value of the sizes of the spherulites is 10 μm or more from the viewpoint of sufficiently increasing the arithmetic mean roughness, and the spherulites in the gloss-adjusting coating film when the gloss-adjusting coating film is viewed in a plan view. It is preferable that the area ratio of the above is 50% or more from the above viewpoint.

FIG. 1 is a photographic image showing an example of spherulite in the gloss-adjusting coating film, which is taken by magnifying the gloss-adjusting coating film having the spherulite at a magnification of 2000 times with an electron microscope. As shown in FIG. 1, the spherulites can be individually confirmed from the appearance by, for example, a radial pattern. The size of the spherulite may be the length of a portion of the spherulite that represents the size, and is represented by, for example, the maximum diameter. Further, the area ratio can be obtained by defining an arbitrary range including a plurality of (for example, 5 or more) spherulites as a measurement region.

The size of the spherulite and the area ratio can be measured and determined based on an enlarged image of the surface of the gloss adjusting coating film, for example, by observation with an optical microscope or an electron microscope.

In the case of the above condition 2, the particle size of the gloss adjusting agent particles and the content in the gloss adjusting coating film can be appropriately determined within the range in which the effect in the present embodiment can be obtained. For example, the average particle size of the gloss adjusting agent particles is preferably 2.8 to 15 μm, more preferably 3 to 10 μm in terms of number average particle size from the viewpoint of achieving a desired arithmetic average roughness. ..

Further, the content of the gloss adjusting agent particles in the gloss adjusting coating film is preferably 0.01 to 5% by volume, more preferably 0.5 to 3.0% by volume from the above viewpoint. The content may be more than 5% by volume, but when it exceeds 5% by volume, the gloss lowering effect is substantially constant. Further, the gloss adjusting agent particles can be appropriately selected from known particles as long as the effect in the present embodiment can be obtained, and may be one kind or more. Examples thereof include inorganic substances such as silica and calcium carbonate. material, and an acrylic resin or urethane resin, benzo grayed Anamin resins, styrene resins, polyethylene resins, polypropylene resins, a resin material such as fluorine resin, include.

When the particle size of the gloss adjusting agent particles is large or the content of the gloss adjusting agent particles is large, the ductility of the gloss adjusting coating film changes over time for the same reason as described in the colored coating film. However, in the present embodiment, since the colored coating film has sufficient ductility, the ductility of the gloss adjusting coating film is low within the range in which the desired function of the gloss adjusting coating film is exhibited. May be good.

Further, under the above condition 2, the uneven shape can be transferred to the surface of the gloss adjusting coating film by a known method. For example, a desired uneven surface is inverted and formed on the surface of the gloss adjusting coating film. By pressing the pressing member having the surface to be formed, it is possible to form a desired uneven surface shape by transfer. The pressing of the pressing member is preferably performed on the surface of the gloss adjusting coating film equal to or higher than the glass transition temperature of the topcoat base resin, and the temperature of the gloss adjusting coating film is set to the glass transition point while the pressing member is pressed. It is preferable to lower the temperature below the temperature and then peel the pressing member from the gloss adjusting coating film.

Further, under the above condition 2, the surface of the gloss adjusting coating film can be ground by a known method, for example, mechanical grinding such as sander polishing and shot blasting.

The gloss-adjusting coating film may further contain components (additives) other than the topcoat base resin and the gloss-adjusting agent particles as long as the effects of the present embodiment can be obtained. Examples of such additives include colored pigment particles and extender pigment particles. These pigment particles may be the same as or different from those in the colored coating. The content of the pigment particles as the additive in the gloss adjusting coating film is preferably 30% by volume or less from the viewpoint of storage stability of the gloss adjusting coating film used for producing the gloss adjusting coating film.

The coated metal plate may further have a film other than the colored coating film and the gloss adjusting coating film as long as the effects of the present embodiment can be obtained. Examples of such other films include chemical conversion coatings, undercoats and intermediate coatings.

The chemical conversion treatment film is arranged directly on the metal plate, that is, between the metal plate and the colored coating film, for the purpose of improving the adhesion and corrosion resistance of the coated metal plate. The chemical conversion treatment film is a layer on a metal plate, and is composed of a composition adhered to the surface of the metal plate by pre-coating treatment. Examples of chemical conversion coatings include non-chromate coatings and chromate coatings. Both are rust-preventive films.

The non-chromate film is preferable from the viewpoint of enhancing corrosion resistance and reducing the burden on the environment in the manufacture and use of the coated metal plate, and the chromate film is preferable from the viewpoint of enhancing corrosion resistance.

Examples of the non-chromate coating include Ti-Mo composite coating, fluoroacid coating, phosphate coating, resin coating, resin and silane coupling agent coating, silica coating, silica and silane coupling agent coating. Includes coatings, zirconium coatings, zirconium and silane coupling agent coatings.

The amount of adhesion of the non-chromate film can be appropriately determined according to the type. For example, the adhesion amount of the Ti-Mo composite film is 10 to 500 mg / m ² in terms of total Ti and Mo, and the adhesion amount of the fluoroacid-based film is 3 to 100 mg / m 2 in terms of fluorine or total metal elements. The ^{amount of adhesion of the phosphate film is m 2} , the amount of adhesion of the phosphate film is 0.1 to 5 g / m ² in terms of phosphorus element, and the amount of adhesion of the resin-based film is 1 to 500 mg / m ² in terms of resin. The adhesion amount of the resin and the silane coupling agent-based film is 0.1 to 50 mg / m ² in terms of Si, and the adhesion amount of the silica-based film is 0.1 to 200 mg / m ² in terms of Si. There, the adhesion amount of the silica and silane coupling agent-based coating is 0.1 to 200 mg / ^{m 2} in terms of Si, adhesion quantity of the zirconium-based coating is 0.1-100 mg / ^{m 2} in terms of Zr The amount of the zirconium and silane coupling agent-based film adhered is preferably ^{0.1 to 100 mg / m 2 in terms of Zr.}

Examples of the chromate-based film include a coating-type chromate-treated film and a phosphoric acid-chromic acid-based treated chromate rust preventive film. The amount of adhesion of these chromate-based coatings is preferably ^{20 to 80 g / m 2 in terms of chromium element.}

The undercoat coating film is arranged between the metal plate and the colored coating film from the viewpoint of enhancing the adhesion and corrosion resistance of the coated metal plate to the colored coating film. The undercoat coating film is formed on the surface of a metal plate or, if the chemical conversion treatment film is produced, the surface of the chemical conversion treatment film.

The film structure of the undercoat coating film is made of resin. Examples of the resin include the completely fluorinated resin, the partially fluorinated resin, the polyester resin, the modified silicon resin, the acrylic resin, the epoxy resin, the phenoxy resin, the urethane resin and the vinyl chloride resin.

The undercoat coating film may further contain additives such as rust preventive pigment particles, colored pigment particles, metallic pigment particles, pearl pigment particles, and extender pigment particles. Examples of the rust preventive pigment particles include particles of non-chromic rust preventive pigments such as modified silica, vanazine salt, magnesium hydrogen phosphate, magnesium phosphate, zinc phosphate, and aluminum polyphosphate, and chromic acid. It contains particles of chromium-based rust preventive pigments such as strontium, zinc chromate, barium chromate, and calcium chromate.

Examples of the colored pigment particles include titanium oxide, chromium oxide, carbon black, iron black, iron oxide yellow, titanium yellow, red iron oxide, navy blue, cobalt blue, cerulean blue, ultramarine blue, cobalt green, molybdenum red, quinacridone red, and resole. Red B, Brilliant Scarlet G, Pigment Scarlet 3B, Brilliant Carmine 6B, Lake Red C, Lake Red D, Permanent Red 4R, Bordeaux 10B, Fast Yellow G, Fast Yellow 10G, Para Red, Watching Red, Benzgin Yellow, Benzgin Orange, Bonn Maroon L, Bon Maroon M, Brilliant Fast Scarlet, Vermilion Red, Phtalocyanin Blue, Phtalussin Green, Fast Sky Blue, Aniline Black, CoAl, CoCrAl, CoCrZnMgAl, CoNiZnTi, CoCrZnTi, NiSbTi, CrSbTi, FeCrZnNi, MnSbTi, FeCr, FeCrNi, Particles of FeNi, FeCrNiMn, FeZn, CoCr, MnCo, and SnZnTi are included.

Examples of the metallic pigment particles include Al flakes, resin-coated Al flakes, metal oxide-coated Al flakes, Ni flakes, Cu flakes, and stainless steel flakes. Examples of the pearl pigment particles include titanium oxide-coated mica, iron oxide-coated mica, and titanium oxide-iron oxide-coated mica. Examples of the extender pigment particles include particles of barium sulfate, titanium oxide, silica and calcium carbonate.

The content of the pigment particles in the undercoat coating film can be appropriately determined within the range in which the effect in the present embodiment can be obtained. For example, the content of the rust preventive pigment in the undercoat coating film can be determined. , 10 to 70% by volume is preferable.

The intermediate coating film is used between the undercoat coating film and the colored coating film, or between the colored coating film and the gloss adjusting coating film, from the viewpoint of enhancing the adhesion and corrosion resistance between the coating films on the coated metal plate. Or both of these are placed.

The film structure of the intermediate coating film is also made of resin. Examples of the resin include the completely fluorinated resin, the partially fluorinated resin, the polyester resin, the modified silicon resin, the acrylic resin, the epoxy resin, the phenoxy resin, the urethane resin and the vinyl chloride resin. Similar to the undercoat coating film, the intermediate coating film may further contain the additive as appropriate within the range in which the effect in the present embodiment can be obtained. The additive is, for example, the same as that described for colored coatings.

For example, if an intermediate coating film containing pearl pigment (for example, titanium oxide-coated mica) particles is arranged between the gloss-adjusting coating film and the low-brightness colored coating film, the color tone peculiar to the pearl pigment is applied to the coated metal plate. And can give a feeling of brilliance. Further, for example, by adding large particle size pigment particles having a particle size of about several tens of μm to the intermediate coating film, irregularities are formed at the interface between the intermediate coating film and the upper layer thereof. Adhesion can be further enhanced, and low glossiness can be further enhanced by the formation or development of irregularities on the surface of the coated metal plate.

When the above-mentioned coating film is arranged as the above-mentioned other film, the thickness of the colored coating film and the thickness of the gloss-adjusting coating film can be determined in consideration of the presence of the above-mentioned coating film. .. For example, when the coated metal plate has an undercoat coating film, a colored coating film, and a gloss adjusting coating film, which will be described later, the thickness of the colored coating film is 10 to 35 μm from the viewpoint of designability, corrosion resistance, and processability over time. The thickness of the gloss adjusting coating film is preferably 3 to 10 μm from the above viewpoint.

The coated metal plate can be produced based on a known method for producing a coating film. For example, the coated metal plate includes a step of forming a film of a paint (colored paint) for the colored coating film on the metal plate, and a step of curing the film of the colored paint to produce a colored coating film. The step of forming a film of the paint (gloss adjusting paint) for the gloss adjusting coating film on the colored coating film and the gloss adjusting coating film having the above arithmetic average roughness by curing the film of the gloss adjusting paint. It can be produced by a method including the step of producing the above.

The preparation of the above-mentioned paint, its application, and the curing of the film by the application can all be carried out based on a known method.

The coating material is a liquid composition containing a material for a coating film. The paint is prepared, for example, by dispersing the materials of the respective coating films described above in a solvent. 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 paint may further contain other additives of the solvent. Examples of such additives include curing agents, curing catalysts and hydrophilizing agents.

The curing agent crosslinks the base resin with each other when the paint is cured (baked). The curing agent can be appropriately selected from known cross-linking agents, curing agents, and the like, depending on the type of the base resin, the baking conditions, and the like. Examples of curing agents include melamine compounds, isocyanate compounds and both. Examples of melamine compounds include imino-based, methylol imino-based, methylol-based or fully alkyl-based melamine compounds. The isocyanate compound may be aromatic, aliphatic or alicyclic, and examples thereof include m-xylene diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate and block compounds thereof.

The curing catalyst is a component that promotes curing of the film or cross-linking of the base resin, and can be appropriately selected from known components having such a catalytic action. The content of the curing catalyst in the coating material can be appropriately determined within a range in which sufficient storage stability of the coating material can be obtained, and is, for example, 10 to 30% by volume.

The above-mentioned hydrophilic agent is suitable as an additive for the gloss-adjusting coating film, and may be contained in the gloss-adjusting coating film in an amount of, for example, 30% by volume or less from the viewpoint of preventing rain streak stains on the gloss-adjusting coating film. Examples of the hydrophilizing agent include a partially hydrolyzed condensate of tetraalkoxysilane.

The coating material can be applied by a known method such as roll coating, curtain flow coating, spray coating, and dipping coating. The amount of the paint applied is appropriately adjusted according to the desired thickness of the coating film. It should be noted that the coating of at least the upper coating of the two coatings that directly overlap is applied by a non-contact coating method such as curtain flow coating or spray coating (so-called wet-on-wet coating in which there is no contact with the object to be coated). Since it is possible to cure the film of the lower paint at the same time as the curing of the film of the upper paint at the same time, apply the paint for the upper coating. It is possible to omit the step of curing the lower coating film before.

For example, when the gloss adjusting coating film is placed directly on the colored coating film, a film of the coloring paint is formed, then a film of the gloss adjusting paint is formed by a non-contact coating method, and then the color coating film is formed. It is possible to cure (by heating) the film and the film of the gloss adjusting paint that overlaps it.

The film of the paint can be cured by a known method of baking the paint on a metal plate by heating. For example, a metal plate coated with a coloring paint is heated so that its reaching temperature reaches 200 to 260 ° C, and a metal plate coated with a gloss adjusting paint has a reaching temperature of 200 to 260 ° C. It is heated.

The step of producing the gloss-adjusting coating film can be appropriately determined according to the above-mentioned conditions 1 and 2. For example, if the gloss-adjusting coating film satisfies the condition 1, the gloss-adjusting coating material containing a fluororesin can be used. It may be a crystallization step in which the cured film is cooled from a temperature equal to or higher than the melting temperature of the fluororesin to a temperature lower than the crystallization temperature at a cooling rate of 10 ° C./sec or less, or a gloss-adjusting coating material satisfying Condition 2. If there is, it may be a step of curing the film of the gloss adjusting paint containing the gloss adjusting agent particles, or it may be an embossing step of transferring unevenness to the film of the cured gloss adjusting paint, or it may be a cured gloss. It may be a grinding step of grinding a film of the adjusting paint.

The crystallization step may be performed immediately after the film of the gloss adjusting paint is cured by heating, or after the cured film having a temperature lower than the melting temperature is heated to a temperature equal to or higher than the melting temperature. You may. The crystal structure of the fluororesin substantially disappears at a temperature equal to or higher than the melting point temperature of the fluororesin.

The starting temperature for cooling the film in the crystallization step is a temperature equal to or higher than the melting temperature of the fluororesin, and more preferably a temperature from the melting temperature to the melting temperature + 20 ° C. Further, the cooling end temperature of the film is a temperature equal to or lower than the crystallization temperature of the fluororesin, and more preferably a temperature from the crystallization temperature to a crystallization temperature of −20 ° C. Further, the cooling rate for cooling the film is 10 ° C./sec or less, more preferably 6 ° C./sec or less. The cooling rate is, for example, an average value of the cooling rates from the cooling start temperature to the cooling end temperature. The actual cooling rate is preferably within the range of ± 2 ° C./sec of the average value from the viewpoint of appropriately controlling the crystallization of the fluororesin.

For example, when the fluororesin is polyvinylidene fluoride, the melting point of polyvinylidene fluoride is 180 ° C. and the crystallization temperature is 130 ° C., so that the cured film is at least 180 ° C. to 130 ° C. in the crystallization step. Slowly cool at a rate of 10 ° C./sec or less between the temperatures up to. The coated metal plate cooled in the crystallization step is usually cooled to room temperature. The above-mentioned cooling may be performed up to room temperature, and the cooling after the above-mentioned cooling end temperature may be performed at a speed higher than the above-mentioned cooling rate.

The cooling of the film in the crystallization step can be appropriately selected from known methods within a range satisfying the above cooling rate. Examples of cooling methods include cooling in a normal temperature atmosphere, blowing cold air (air cooling), blowing a low-temperature liquid such as water or immersing it in the cooling liquid (water cooling), and cooling by contact with a low-temperature solid. (For example, contact with a cooling roll or cooling plate).

The embossing step can be performed by pressing the surface of an object (pressing member) having an inverted concavo-convex shape, which is a reversal of a desired concavo-convex shape, against the surface of the cured film. The pressing member can be made of a known material such as metal or glass.

The pressing of the pressing member is preferably performed on the film when the temperature of the film is equal to or higher than the melting temperature of the fluororesin, from the viewpoint of accurately transferring the desired uneven shape to the surface thereof. .. The starting temperature of pressing is more preferably a melting temperature + 20 ° C. or higher. Further, the pressing of the pressing member is released after the temperature of the film becomes equal to or lower than the melting temperature of the fluororesin (the pressed pressing member is separated from the film), but the transferred uneven shape is heated by heat. It is preferable from the viewpoint of preventing deformation. The pressing release end temperature is more preferably a temperature of the melting temperature of −20 ° C. or lower.

For example, when the fluororesin is polyvinylidene fluoride, the melting temperature is 180 ° C. Therefore, when the temperature of the film is 200 ° C. or higher (for example, 200 ° C.), the pressing member is pressed against the film and 160 ° C. or lower. After cooling to (for example, 160 ° C.), the pressing member is separated from the film. Further, the cooling rate for cooling the film is 10 ° C./sec or less, and more preferably 5 ° C./sec or less for the above reason.

The grinding step can be performed by a known method such as mechanical polishing or shot blasting. It is preferable that the grinding step is performed on the film cooled to room temperature from the viewpoint of preventing the film from being deformed due to a cause other than grinding.

The method for producing a coated metal plate may further include steps other than the above-mentioned steps as long as the effects of the present embodiment can be obtained. Examples of the other steps include a chemical conversion treatment step of forming a chemical conversion treatment film, a step of forming an undercoat coating film, and a step of forming an intermediate coating film.

In the chemical conversion treatment step, an aqueous chemical conversion treatment liquid for forming a chemical conversion treatment film 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 spray method, and after the coating, the metal is applied. This can be done by drying the board without washing it 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. for 2 to 10 seconds at the ultimate temperature of the metal plate.

The step of forming the undercoat coating film can be performed by applying a coating material for the undercoat coating film (undercoat coating film) and curing the film thereby. The undercoat paint may contain the above solvent and the above additives, if necessary. The undercoat paint is prepared by uniformly mixing and dispersing the above-mentioned materials. The undercoat paint is applied to the metal plate by, for example, the above-mentioned known method for the topcoat paint in a coating amount capable of obtaining a dry film thickness of 1 to 10 μm (preferably 3 to 7 μm). The coating film of the paint is produced by being baked onto the metal plate by heating the metal plate at a temperature of 180 to 260 ° C., for example, at the temperature reached by the metal plate.

Similar to the step of forming the undercoat coating film, the step of forming the intermediate coating film can also be performed by applying a coating material for the intermediate coating film (intermediate coating film) and curing the film thereby. The intermediate coating material may also contain the above solvent and the above additives, if necessary, in addition to the material of the intermediate coating film. The intermediate coating material is also prepared by uniformly mixing and dispersing the above-mentioned materials. The intermediate coating paint is preferably applied, for example, by the above-mentioned known method in a coating amount of 3 to 20 μm (preferably 5 to 15 μm). The coating film of the paint is produced by being baked onto the metal plate by heating the metal plate at a temperature of 180 to 260 ° C., for example, at the temperature reached by the metal plate.

The coated metal plate has sufficient ductility and designability even though the colored coating film contains pigment particles, and therefore has sufficient processability. Further, since the coated metal plate has a gloss adjusting coating film, it has sufficiently low gloss. The reason will be explained below.

Generally, when the coated metal plate is molded, tensile stress acts on the coating film of the coated metal plate, and the coating film is stretched. This stretching causes constriction, deformation, and extension at a certain point at the beginning, and the region (constriction deformed portion) deformed in this way expands (propagates) in the tensile direction.

In the constricted deformation portion, the molecular chains of the fluororesin constituting the coating film, which were randomly oriented before the constriction deformation, are oriented in the tensile direction due to tensile stress. Therefore, when a certain amount of tensile stress is applied to the constricted deformed portion, even if a further tensile stress is applied, the already oriented molecular chain is not easily extended any more. Therefore, the "parts that have not yet been constricted (molecular chains that are not oriented)" around the constricted deformed portion are constricted and deformed.

The propagation of the orientation of the molecular chains is the elongation and deformation of the resin coating film. In other words, the high ductility of the resin coating film is due to the propagation of the above orientation of the molecular chain proceeding throughout the coating film without breaking the molecular chain. The stress required for the orientation of the molecular chains is higher in the crystallized resin than in the amorphous resin. This is because the binding force between the regularly folded crystal molecular chains is high.

Here, in the case of a resin coating film (for example, a clear coating film) that does not contain pigment particles, although there is a slight difference in deformation resistance depending on the crystal state of the resin, the coating film is stretch-deformed due to tensile stress. The ductility is high. On the other hand, the pigment particles are extremely hard as compared with the resin and do not deform due to elongation.

Therefore, in the case of a resin coating film containing pigment particles and the resin is a crystalline resin, the resin constituting the coating film crystallizes (amorphous portions are reduced) and deformation resistance is increased. It becomes even larger, and voids are likely to be created between the oriented molecular chain and the pigment particles. Therefore, stress is concentrated on the voids generated in the constricted deformed portion, and the voids grow, resulting in breakage of the coating film. That is, the ductility of the coating film is low.

Of the voids generated in the constricted deformed portion, when the size of the voids initially generated is a size that cannot be ignored with respect to the thickness of the constricted deformed portion of the coating film (about 3 to 5 μm), stress is applied to the voids. Concentrate and the void grows. The size of the voids generated at the initial stage is considered to be equivalent to the particle size of the pigment particles in the coating film, and the size of the voids at the initial stage is sufficiently smaller than the thickness of the constricted deformed portion of the coating film. In this case, it is considered that the stress concentration in the voids does not substantially occur.

That is, if the particle size of the pigment particles in the coating film exceeds a certain threshold, the above stress concentration occurs in the voids, and if the content of the pigment particles in the coating film exceeds a certain threshold, the above stress concentration occurs. Since the small voids are sufficiently densely packed, the action is similar to that of the large voids, and the voids grow and coalesce due to stress concentration, and the above-mentioned coating film is liable to break. That is, the ductility of the coating film is low. In the present embodiment, as a result of examining the above threshold value, it was found that the threshold value of the particle size of the pigment particles is 3 μm and the threshold value of the content of the pigment particles is 1% by volume.

As described above, the coated metal plate of the present embodiment has a colored coating film, and although the colored coating film is sufficient for exhibiting designability, a specific amount of pigment particles having a small particle size is contained. Contains only the following: Therefore, the colored coating film exhibits sufficient ductility during processing of the coated metal plate, and cracking of the colored coating film due to the stress concentration is prevented. Therefore, in the coated metal plate, even if the gloss adjusting coating film is cracked, sufficient corrosion resistance is exhibited, and further, the design property of the colored coating film and the low gloss property of the gloss adjusting coating film are exhibited.

Conventional fluororesin paints for exterior building materials usually exceed these threshold values. For example, a gloss adjuster pigment is added to a general paint for the purpose of adjusting the gloss of the coating film surface. In order to impart irregularities to the surface of the coating film, the gloss adjusting agent pigment has an average particle size of about 5 to 30 μm, and the content in the coating film is generally more than 1% by volume.

Further, the pigment particles generally have a property of aggregating in the coating material, and the agglomerated particles of the pigment particles bring about large voids in the constricted deformed portion. When the present inventors allowed a paint having a pigment particle particle size of 3 μm or less to stand, it was confirmed that agglomerated particles having a particle size of more than 3 μm were present in the paint, and the content thereof was a dry coating film. It was confirmed that the content was 1% by volume or more. As described above, it has been found that the processability of the conventional fluororesin-based coated metal plate for exterior building materials may be extremely lowered over time.

As is clear from the above description, the coated metal plate of the present embodiment includes a metal plate, a colored coating film arranged on the metal plate, and a gloss adjusting coating film arranged on the colored coating film. The colored coating film contains a fluorine resin and a base resin constituting the film structure of the colored coating film, and pigment particles containing colored pigment particles and dispersed in the colored coating film. contains. The thickness of the colored coating film is 50 μm or less, the content of the pigment particles in the colored coating film is 12% by volume or less, and the content of the colored pigment particles in the colored coating film is 12% by volume or less. The content of particles having a particle size of more than 3 μm in the colored coating film having a particle size of 2% by volume or more is 1% by volume or less, and either the following condition 1 or condition 2 is satisfied. Therefore, according to the present embodiment, it is possible to provide a fluororesin-based coated metal plate having sufficient workability, designability and low gloss even after long-term storage.
[Condition 1] The gloss-adjusting coating film is composed of a topcoat base resin containing a fluororesin, and also contains spherulites that form irregularities on the surface of the gloss-adjusting coating film of the topcoat base resin. Moreover, the arithmetic mean roughness of the surface of the gloss adjusting coating film is 50 nm or more.
[Condition 2] The gloss-adjusting coating film contains a topcoat base resin constituting the film structure, and does not contain spherulites forming irregularities on the surface of the gloss-adjusting coating film of the topcoat base resin. Moreover, the arithmetic mean roughness of the surface of the gloss adjusting coating film is 200 nm or more.

Under the above condition 2, the gloss adjusting coating film contains the topcoat base resin constituting the film structure and the gloss adjusting agent particles dispersed in the gloss adjusting coating film, and the average of the gloss adjusting agent particles. The particle size of 2.8 to 15 μm and the content of the gloss adjusting agent particles in the gloss adjusting coating film of 0.5 to 3.0% by volume facilitates the gloss adjusting coating film using the gloss adjusting agent. It is even more effective from the viewpoint of producing.

Further, under the above condition 1, the gloss adjusting coating film is composed of a topcoat base resin containing a fluororesin and contains spherulites of the topcoat base resin, and the average value of the sizes of the spherulites is 10 μm. As described above, the fact that the area ratio of the spherulites in the gloss-adjusting coating film when the gloss-adjusting coating film is viewed in a plan view is 50% or more means that the gloss-adjusting coating film contains pigment particles during processing. It is even more effective from the viewpoint of preventing cracking.

Further, the content of the fluororesin in the topcoat base resin is 50 to 85% by mass, which is more effective from the viewpoint of achieving sufficient low gloss due to the spherulites in the gloss adjusting coating film. .. If it is less than 50% by mass, the amount of fluororesin spherulite produced is small, and the particle size or area ratio of the spherulite is insufficient. On the other hand, if it exceeds 85% by mass, the concentration of the fluororesin in the fluorine coating material is excessive, which may reduce the long-term storage stability of the coating material, which is disadvantageous in terms of cost.

Further, the content of the fluororesin in the base resin is 70 to 85% by mass, which is more effective from the viewpoint of achieving sufficient weather resistance and processability of the coated metal plate. If it is less than 70% by mass, the amount of the acrylic resin component that is harder than that of the fluororesin is increased, so that the initial processability and the processability with time of the colored coating film are lowered. Further, when it exceeds 85% by mass, the concentration of the fluororesin in the fluorine coating material is excessive, so that the long-term storage stability of the coating material may be lowered, which is disadvantageous in terms of cost and the effect of improving the weather resistance is small.

Further, the fact that the pigment particles further contain the gloss adjusting agent particles and the content of the gloss adjusting agent particles in the colored coating film is 0.2 to 1.0% by volume means that the coloring pigment particles and the gloss adjusting agent particles are contained. The designability is realized by coexistence with, and it is more effective from the viewpoint of realizing such a specific designability of the coated metal plate.

Further, the fact that the average particle size of the colored pigment particles is 2.0 μm or less is from the viewpoint of increasing the content of the colored pigment particles (up to 5% by volume) and from the viewpoint of improving the processability after storage of the coated metal plate. The fact that the average particle size of the colored pigment particles is 0.5 μm or less is from the viewpoint of increasing the content of the colored pigment particles (up to 10% by volume) and after storage of the coated metal plate. It is even more effective from the viewpoint of improving the workability of the particles.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

[Manufacturing of painted original plates 1 to 4]
A 55% molten Al—Zn alloy plated steel sheet having a plate thickness of 1.0 mm and a double-sided adhesion amount of 150 g / m ^{2 was alkali degreased.} This is referred to as a coating original plate 1.

A chromate-based rust preventive treatment liquid (“Surf Coat NRC300” manufactured by Nippon Paint Surf Chemicals Co., Ltd.) is applied to the surface of the original coating plate 1, and the original coating plate 1 after application is dried at 100 ° C. without washing with water to convert to chromium. Chromate rust preventive treatment with an adhesion amount of 20 mg / m ² was performed. This is used as the coating original plate 2.

An epoxy resin-based paint containing the following components in the following amount is applied to the surface of the coated original plate 2 after the above chromate rust prevention treatment so that the ultimate temperature of the plated steel plate in the coated original plate 2 becomes 200 ° C. The coated original plate 2 after the above coating was heated to obtain a plated steel plate having a chromate-based coating film having a dry film thickness of 5 μm. This is referred to as a coating original plate 3. The following clear paint is "NSC680" manufactured by Nippon Paint Industrial Coatings Co., Ltd.
Strontium chromate 15% by volume
Barium sulfate 5% by volume
Silica 1% by volume
Clear paint remaining

A non-chromate rust preventive treatment liquid containing the following components in the following amount is applied to the surface of the original coating plate 1, and the original coating plate 1 after application is dried at 100 ° C. without washing with water, and is 10 mg / m in terms of Ti. Non-chromate rust preventive treatment of the amount of adhesion of ^{2 was performed.}
Hexafluorotitanate 55g / L
Hexafluorozirconium acid 10 g / L
Amino Methyl Substituted Polyvinyl Phenol 72g / L
Water residue

Next, the following epoxy resin-based paint containing the following components in the following amounts is applied to the surface of the coated original plate 1 after the non-chromate rust prevention treatment, and the ultimate temperature of the plated steel plate in the coated original plate 1 is 200 ° C. The coating original plate 1 after coating was heated so as to obtain a plated steel plate having a chromate-free coating film having a dry film thickness of 5 μm. This is referred to as a coating original plate 4. The following clear paint is "NSC680" manufactured by Nippon Paint Industrial Coatings Co., Ltd.
Phosphate mixture 15% by volume
Barium sulfate 5% by volume
Silica 1% by volume
Clear paint remaining

[Preparation of clear paints 1 to 8]
Fluororesin-based clear paint "Dick Flow C" manufactured by Nippon Paint Industrial Coatings Co., Ltd. is designated as clear paint 1. The clear paint 1 is a blended paint of polyvinylidene fluoride and an acrylic resin, and the weight ratio of polyvinylidene fluoride and the acrylic resin is 85:15. The melting temperature of the resin component in the clear paint 1 is 180 ° C., and the crystallization temperature is 130 ° C.

In addition, polyvinylidene fluoride (Arkema's "Kynar500" and "KYNAR" are registered trademarks of the same company), acrylic resin (ROHM and Haas's "Paraloid B-44" and "Paraloid" are registered trademarks of the same company) and paint solvents. The components (isophorone) were mixed to obtain clear paints 2 to 8. The weight ratios of polyvinylidene fluoride and acrylic resin in the clear paints 2 to 8 are 40:60, 50:50, 60:40, 70:30, 80:20, 85:15, and 90:10, respectively. The melting temperature of the resin components in the clear coating materials 2 to 8 is 180 ° C., and the crystallization temperature is 130 ° C.

[Preparation of silica particles 1 to 7]
The following silicas 1 to 7 were prepared respectively.
Silica 1 ("SO-E6" manufactured by Admafine Co., Ltd., average particle size: 2.0 μm)
Silica 2 ("Silicia 710" manufactured by Fuji Silysia Chemical Ltd., average particle size: 2.8 μm)
Silica 3 ("Silicia 350" manufactured by Fuji Silysia Chemical Ltd., average particle size: 4.0 μm)
Silica 4 ("Silicia 770" manufactured by Fuji Silysia Chemical Ltd., average particle size: 6.0 μm)
Silica 5 ("Silicia 380" manufactured by Fuji Silysia Chemical Ltd., average particle size: 9.0 μm)
Silica 6 ("ZA-20" manufactured by Ryumori Co., Ltd., average particle size: 15 μm)
Silica 7 (Micron "TS-10-034P" average particle size: 20 μm)

[Preparation of pigment particles 1 to 8]
Titanium oxide (“R-930” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) was prepared. The average particle size can be confirmed by magnified observation with a microscope or the like, or an image analysis method, a Coulter method (for example, Beckman Coulter's precision particle size distribution measuring device "Multisizer 4"), or dynamic light. It can be measured by a scattering method (for example, manufactured by Shimadzu Corporation, nanoparticle size distribution measuring device “SALD-7500 nano”) or the like.

Then, particles having an average particle size or larger were removed from the titanium oxide by classification. In this way, pigment particles 1 which are colored pigment particles were obtained.

Instead of titanium oxide "R-930", an iron-chromium composite oxide ("BLACK6350" manufactured by Asahi Kasei Kogyo Co., Ltd., average particle size: 0.5 μm) was used, and the above average particle size (0.5 μm) was used. Pigment particles 2, which are colored pigment particles, were obtained in the same manner as in the preparation of pigment particles 1 except that the classification treatment was performed. Further, instead of titanium oxide "R-930", an iron-zinc composite oxide ("BROWN4123" manufactured by Asahi Kasei Kogyo Co., Ltd., average particle size: 1.8 μm) was used, and the above average particle size (1.8 μm) was used. ), The pigment particles 3 which are colored pigment particles were obtained in the same manner as in the preparation of the pigment particles 1. Further, instead of titanium oxide "R-930", carbon black ("AUSTIN BLACK325" made by CoalFillers, average particle size: 5.5 μm) is used, and the pigment is used except for the classification treatment with the above average particle size (5.5 μm). Pigment particles 4, which are colored pigment particles, were obtained in the same manner as in the preparation of the particles 1.

In addition, instead of titanium oxide "R-930", each of silicas 2 to 5 is used, and the classification treatment is performed with the average particle size (2.8 μm, 4.0 μm, 6.0 μm and 9.0 μm), respectively. Obtained each of the pigment particles 5 to 8 which are the gloss adjusting agent particles in the same manner as in the preparation of the pigment particles 1.

[Preparation of colored paints 1 to 6]
The following components were mixed in the following amounts and the resulting mixture was filtered through a 500 mesh filter to remove aggregated particles from the mixture. In this way, the colored paint 1 was obtained.
Pigment particles 1 15.0% by volume
Clear paint 1 Remaining

Colored paints 2 and 4 are similar to the preparation of colored paint 1 except that the amount of pigment particles 1 is changed to 12.0% by volume, 10.0% by volume, 7.5% by volume and 5.0% by volume, respectively. Each of ~ 6 was obtained.

Further, the colored paint 2 was allowed to stand in an environment of 28 ° C. for 30 days. This is referred to as colored paint 3. When the particle size distribution of the pigment particles 1 in the colored paint 3 was measured by a nanoparticle size distribution measuring device "SALD-7500 nano" manufactured by Shimadzu Corporation, the amount of the pigment particles 1 was 10.0% by volume. The amount of agglomerated particles of titanium oxide having an average particle size of 3.5 μm, which is the agglomerates, was 2.0% by volume, and it was confirmed that a part of the pigment particles 1 was agglomerated.

[Preparation of colored paints 7-14]
Colored paints 7 to 9, 11 and 12, respectively, were obtained in the same manner as in the preparation of the colored paints 1, 2 and 4 to 6, except that the pigment particles 2 were used instead of the pigment particles 1. Further, the pigment particles 2 are used instead of the pigment particles 1, and the colored paint is prepared in the same manner as in the preparation of the colored paint 1 except that the amount of the pigment particles 2 is changed to 2.0% by volume and 1.0% by volume, respectively. 13 and 14 respectively were obtained.

Further, the colored paint 9 was allowed to stand in an environment of 28 ° C. for 30 days. This is referred to as the colored paint 10. When the particle size distribution of the pigment particles 2 in the colored paint 10 was measured by a nanoparticle size distribution measuring device "SALD-7500 nano" manufactured by Shimadzu Corporation, the amount of the pigment particles 2 was 8.5% by volume. The amount of agglomerated particles of the iron-chromium-based composite oxide having an average particle size of 4.0 μm, which is the agglomerates, was 1.5% by volume, and it was confirmed that a part of the pigment particles 2 was agglomerated. ..

[Preparation of colored paints 15 to 22]
Colored paints 15, 16 and 18 to 20, respectively, were obtained in the same manner as in the preparation of the colored paints 1, 2 and 4 to 6, except that the pigment particles 3 were used instead of the pigment particles 1. Further, the pigment particles 3 are used instead of the pigment particles 1, and the colored paint is prepared in the same manner as in the preparation of the colored paint 1 except that the amount of the pigment particles 3 is changed to 2.0% by volume and 1.0% by volume, respectively. 21 and 22 respectively were obtained.

Further, the colored paint 16 was allowed to stand in an environment of 28 ° C. for 30 days. This is referred to as colored paint 17. When the particle size distribution of the pigment particles 3 in the colored paint 17 was measured with a nanoparticle size distribution measuring device "SALD-7500 nano" manufactured by Shimadzu Corporation, the amount of the pigment particles 3 was 10.0% by volume. The amount of agglomerated particles of the iron-zinc-based composite oxide having an average particle size of 6.0 μm, which was the agglomerates, was 2.0% by volume, and it was confirmed that a part of the pigment particles 3 was agglomerated.

[Preparation of colored paints 23 to 26]
Colored paints 23 and 24 were obtained in the same manner as in the preparation of the colored paints 5 and 6, except that the pigment particles 4 were used instead of the pigment particles 1. Further, the pigment particles 4 are used instead of the pigment particles 1, and the colored paint is prepared in the same manner as in the preparation of the colored paint 1 except that the amount of the pigment particles 4 is changed to 2.0% by volume and 1.0% by volume, respectively. 25 and 26 were obtained respectively.

[Preparation of colored paints 27-36]
The following components were mixed in the following amounts and the resulting mixture was filtered through a 500 mesh filter to remove aggregated particles from the mixture. In this way, the colored paint 27 was obtained.
Pigment particles 2 8.5% by volume
Pigment particles 5 12.0% by volume
Clear paint 1 Remaining

Same as the preparation of the colored paint 27 except that the amount of the pigment particles 5 is changed to 10.0% by volume, 7.5% by volume, 5.0% by volume, 2.0% by volume and 1.0% by volume, respectively. Each of the colored paints 28 to 32 was obtained.

Colored paints 33 and 34 were obtained in the same manner as in the preparation of the colored paint 32, except that the pigment particles 1 and the pigment particles 3 were used instead of the pigment particles 2. Further, the colored paints 35 and 36 were obtained in the same manner as in the preparation of the colored paint 27 except that the amount of the pigment particles 5 was changed to 0.5% by volume and 0.2% by volume, respectively.

[Preparation of colored paints 37 to 46]
Colored paints 37 to 46 were obtained in the same manner as in the preparation of the colored paints 27 to 36 except that the pigment particles 6 were used instead of the pigment particles 5.

[Preparation of colored paints 47-51]
Colored paints 47 to 51 were obtained in the same manner as in the preparation of the colored paints 30 to 32, 35 and 36, except that the pigment particles 7 were used instead of the pigment particles 5.

[Preparation of colored paints 52 to 56]
The colored paints 52 to 56 were obtained in the same manner as in the preparation of the colored paints 47 to 51 except that the pigment particles 8 were used instead of the pigment particles 7.

The compositions of the pigment particles of the colored paints 1 to 56 are shown in Tables 1 and 2.

[Preparation of colored paints 57 to 63]
Each of the colored paints 57 to 63 was obtained in the same manner as in the preparation of the colored paint 5 except that the clear paints 2 to 8 were used instead of the clear paint 1.

[Preparation of gloss adjusting paints 1 to 25]
Clear paint 1 and silica 1 and 3 to 7 as gloss adjusting agent particles were mixed in the amounts shown in Table 3 below to obtain gloss adjusting paints 1 to 25, respectively.

[Preparation of gloss adjusting paints 26 to 33]
Only clear paints 1 to 8 were prepared, and these were used as gloss adjusting paints 26 to 33.

Table 3 shows the contents of the gloss adjusting agent particles in the gloss adjusting paints 1 to 25.

[Manufacturing of painted metal plate 1]
The colored paint 1 is applied to the surface of the coated original plate 3, the coated original plate 3 coated with the colored paint 1 is heated so that the reaching temperature of the plated steel sheet reaches 250 ° C., and then immersed in water at 30 ° C. for cooling. Then, it was taken out of water, the water was wiped off with gauze, and the mixture was dried at 30 ° C. for 1 hour. In this way, a colored metal plate having a colored coating film having a thickness of 25 μm with the colored paint 1 was produced on the surface of the coating original plate 3.

The gloss adjusting paint 11 is applied to the surface of the colored metal plate, the colored metal plate coated with the gloss adjusting paint 11 is heated so that the reaching temperature of the plated steel plate reaches 250 ° C., and then immersed in water at 30 ° C. Then, it was taken out of the water, the water was wiped off with a gauze, and the mixture was dried at 30 ° C. for 1 hour. In this way, the coated metal plate 1 having the coating original plate 3, the colored coating film, and the gloss adjusting coating film having a thickness of 5 μm by the gloss adjusting paint 11 was produced in this order.

The arithmetic mean roughness Ra of the surface (of the gloss-adjusting coating film) of the coated metal plate 1 was measured using an electron microscope and found to be 340 nm.

[Manufacturing of painted metal plates 2-5, 58-64]
Each of the coated metal plates 2 to 5, 58 to 64 was produced in the same manner as in the production of the coated metal plate 1 except that the colored paints 2 to 5 and 57 to 63 were used instead of the colored paint 1. Ra of the coated metal plates 2 to 5 was 335 nm, 339 nm, 340 nm and 342 nm, respectively. The Ras of the coated metal plates 58 to 64 were 347 nm, 352 nm, 347 nm, 341 nm, 356 nm, 343 nm and 358 nm, respectively.

[Manufacturing of painted metal plates 6 and 7]
A painted metal plate is used in place of the colored paint 1, except that the amount of the gloss adjusting paint 11 applied is adjusted to produce a gloss adjusting coating film having a thickness of 10 μm in the same manner as in the production of the painted metal plate 1. 6 was prepared. Further, in the same manner as in the production of the coated metal plate 1, the coated metal plate was produced by using the colored paint 6 instead of the colored paint 1 and adjusting the coating amount of the colored paint 6 to produce a colored coating film having a thickness of 35 μm. 7 was prepared. Ra of the coated metal plates 6 and 7 was 347 nm and 337 nm, respectively.

[Manufacturing of painted metal plates 8 to 57]
Instead of the colored paint 1, each of the colored paints 7 to 32, 34 to 42, and 44 to 56 was used, and the coating amount of the colored paint was adjusted to prepare a colored coating film having a thickness of 22 μm. In the same manner as in the production, each of the coated metal plates 8-33, 35-43 and 45-57 was produced. Further, in the same manner as in the production of the coated metal plate 1, a colored coating film having a thickness of 35 μm was produced by using each of the colored paints 33 and 43 instead of the colored paint 1 and adjusting the coating amount of the colored paint. Each of the painted metal plates 34 and 44 was prepared.

Ra of the coated metal plates 8 to 15 was 335 nm, 331 nm, 350 nm, 329 nm, 345 nm, 345 nm, 341 nm and 335 nm, respectively. The Ra of the coated metal plates 16 to 23 was 334 nm, 333 nm, 398 nm, 348 nm, 339 nm, 327 nm, 342 nm and 342 nm, respectively.

Ra of the coated metal plates 24 to 27 was 341 nm, 335 nm, 335 nm and 341 nm, respectively. The Ras of the coated metal plates 28 to 37 were 338 nm, 336 nm, 331 nm, 341 nm, 358 nm, 336 nm, 328 nm, 336 nm, 331 nm and 340 nm, respectively. The Ras of the coated metal plates 38 to 47 were 340 nm, 346 nm, 332 nm, 338 nm, 331 nm, 336 nm, 348 nm, 331 nm, 336 nm and 340 nm, respectively.

The Ra of the coated metal plates 48 to 52 was 428 nm, 397 nm, 350 nm, 345 nm and 334 nm, respectively. The Ras of the coated metal plates 53 to 57 were 687 nm, 412 nm, 370 nm, 368 nm and 352 nm, respectively.

[Manufacturing of painted metal plates 65-67]
Each of the painted metal plates 65 to 67 was produced in the same manner as in the production of the coated metal plate 5 except that the coated original plates 1, 2 and 4 were used instead of the coated original plate 3. Ra of the coated metal plate 65-67 was 329 nm, 351 nm and 349 nm, respectively.

[Manufacturing of painted metal plates 68 to 92]
Painted metal plates 68 to 75 were obtained in the same manner as in the production of the painted metal plate 5 except that each of the gloss adjusting paints 1 to 8 was used instead of the gloss adjusting paint 11.

Further, instead of the gloss adjusting paint 11, each of the gloss adjusting paints 9 to 13 was used, and the amount of the gloss adjusting paint applied was adjusted to prepare a gloss adjusting coating film having a thickness of 6 μm. In the same manner as above, painted metal plates 76 to 80 were obtained.

Further, the coated metal plates 81 to 86 were obtained in the same manner as in the preparation of the coated metal plate 6 except that each of the gloss adjusting paints 14 to 19 was used instead of the gloss adjusting paint 11.

Further, instead of the gloss adjusting paint 11, each of the gloss adjusting paints 20 to 22 was used, and the amount of the gloss adjusting paint applied was adjusted to prepare a gloss adjusting coating film having a thickness of 15 μm. In the same manner as above, painted metal plates 87 to 89 were obtained.

Further, instead of the gloss adjusting paint 11, each of the gloss adjusting paints 23 to 25 was used, and the amount of the gloss adjusting paint applied was adjusted to prepare a gloss adjusting coating film having a thickness of 20 μm. In the same manner as above, painted metal plates 90 to 92 were obtained.

Ra of the coated metal plates 68 to 75 was 255 nm, 231 nm, 173 nm, 713 nm, 548 nm, 341 nm, 211 nm and 147 nm, respectively.

The Ras of the coated metal plates 76 to 80 were 3524 nm, 2093 nm, 1086 nm, 345 nm and 198 nm, respectively.

Ra of the coated metal plates 81 to 86 was 7358 nm, 4926 nm, 2501 nm, 345 nm, 221 nm and 131 nm, respectively.

Ra of the coated metal plates 87 to 89 was 3003 nm, 231 nm and 150 nm, respectively.

Ra of the coated metal plates 90 to 92 was 5198 nm, 253 nm and 162 nm, respectively.

[Manufacturing of painted metal plates 93 to 104]
A coated metal plate was produced in the same manner as in the production of the coated metal plate 5 except that the gloss adjusting paint 26 was used instead of the gloss adjusting paint 11. Next, as a step of adjusting the gloss of the coated metal plate, the coated metal plate 93 was produced by heating and cooling the plated steel plate under condition 1. The above condition 1 is a condition in which the coated metal plate is heated until the temperature reaches 200 ° C., and the coated metal plate is cooled to 30 ° C. at a rate of 700 ° C./sec by immersing it in water at 30 ° C.

The average particle size Rcg of the resin crystals on the surface of the produced gloss-adjusting coating film was determined by magnifying observation of 5000 times with an electron microscope and found to be 1.0 μm. Further, in the produced gloss-adjusting coating film, the area of the spherulite region was determined for a photographic image in which the area ratio Scg of the resin crystal when viewed in a plan view was magnified 5000 times using an electron microscope. When this was calculated by dividing by the observation area, it was 1.0%. Further, when Ra of the coated metal plate 93 was determined by three-dimensional measurement (three-dimensional electron microscopy) with an electron microscope, it was 11 nm.

Further, each of the coated metal plates 94 to 104 was produced in the same manner as the production of the coated metal plate 93 except that the cooling in the gloss adjusting step of the coated metal plate was performed under each of the conditions 2 to 12 instead of the condition 1.

Condition 2 is a step of adjusting the gloss of the colored metal plate by heating the coated metal plate until the temperature reaches 200 ° C. and spraying water at 30 ° C. only on the back surface of the colored metal plate at a rate of 80 ° C./sec. The condition is that the metal is cooled to 40 ° C. and then immersed in water at 30 ° C. to cool to 30 ° C. Condition 3 is a step of adjusting the gloss of the colored metal plate by heating the coated metal plate to a temperature of 200 ° C. and blowing cold air at 20 ° C. on both sides of the colored metal plate at a rate of 10 ° C./sec. It is a condition of cooling to 40 ° C. and then immersing in water at 30 ° C. to cool to 30 ° C. Condition 4 is a step of adjusting the gloss of the colored metal plate by heating the coated metal plate to a temperature of 200 ° C. and blowing cold air at 20 ° C. only on the back surface of the colored metal plate at a speed of 6 ° C./sec. The condition is that the metal is cooled to 40 ° C. and then immersed in water at 30 ° C. to be cooled to 30 ° C. Condition 5 is a step of adjusting the gloss of the colored metal plate by heating the coated metal plate to a temperature of 200 ° C. and bringing a 30 ° C. steel plate (thickness 20 mm) into close contact only with the back surface of the colored metal plate. The condition is that the mixture is cooled to 40 ° C. at a rate of 2 ° C./sec and then immersed in water at 30 ° C. to cool to 30 ° C.

Condition 6 is 1 ° C./sec by heating the painted metal plate to a temperature of 200 ° C. and allowing the colored metal plate to cool in an atmosphere of 30 ° C. as a step of adjusting the gloss of the colored metal plate. It is a condition of cooling to 40 ° C. at a rate and then cooling to 30 ° C. by immersing in water at 30 ° C. The above conditions 7 to 9 are the same as the conditions 6 except that the heating temperature (cooling start temperature by cooling) in the gloss adjusting step is changed from 200 ° C. to 180 ° C., 150 ° C. and 120 ° C., respectively. The above conditions 10 to 12 are the same as the condition 6 except that the end temperature of cooling by cooling is changed from 40 ° C. to 160 ° C., 130 ° C. and 120 ° C., respectively.

The cooling conditions 1 to 12 are shown in Table 4.

The Rcg of the coated metal plate 94 was 3.0 μm, the Scg was 50%, and the Ra was 36 nm. The Rcg of the coated metal plate 95 was 10 μm, the Scg was 80%, and the Ra was 87 nm. The Rcg of the coated metal plate 96 was 15 μm, the Scg was 85%, and the Ra was 98 nm. The Rcg of the coated metal plate 97 was 15 μm, the Scg was 90%, and the Ra was 110 nm. The Rcg of the coated metal plate 98 was 20 μm, the Scg was 90%, and the Ra was 120 nm.

The Rcg of the coated metal plate 99 was 20 μm, the Scg was 90%, and the Ra was 120 nm. In each of the coated metal plates 100 and 101, Rcg was 1.0 μm, Scg was 10%, and Ra was 23 nm.

The Rcg of the coated metal plate 102 was 1.5 μm, the Scg was 10%, and the Ra was 29 nm. The Rcg of the coated metal plate 103 was 10 μm, the Scg was 50%, and the Ra was 54 nm. The Rcg of the coated metal plate 104 was 20 μm, the Scg was 90%, and the Ra was 120 nm.

[Manufacturing of painted metal plates 105-111]
Each of the coated metal plates 105 to 111 was produced in the same manner as in the production of the coated metal plate 98 except that each of the gloss adjusting paints 27 to 33 was used instead of the gloss adjusting paint 26. Ra of the coated metal plate 105-111 was 41 nm, 56 nm, 84 nm, 103 nm, 112 nm, 124 nm and 137 nm, respectively.

[Manufacturing of painted metal plate 112]
The gloss adjusting paint 26 is applied to the surface of the coating original plate 3 before the colored coating material 5 is applied, heated so that the ultimate temperature of the plated steel sheet reaches 250 ° C., and then immersed in water at 30 ° C. for cooling, and then. , Removed from water, wiped off water with gauze, and dried at 30 ° C. for 1 hour. In this way, an undercoat film having a thickness of 10 μm was prepared. A colored coating film and a gloss adjusting coating film are produced on the surface in the same manner as in the production of the coated metal plate 5, and a coated metal plate 112 having a coating original plate, an undercoat coating film, a colored coating film and a gloss adjusting coating film in this order is formed. Made. Ra of the painted metal plate 112 was 341 nm.

[Manufacturing of painted metal plate 113]
The gloss adjusting paint 26 is applied to the surface of the colored metal plate before the gloss adjusting paint 11 is applied, heated so that the reaching temperature of the plated steel sheet reaches 250 ° C., and then immersed in water at 30 ° C. for cooling. Then, it was taken out from the water, the water was wiped off with a gauze, and the mixture was dried at 30 ° C. for 1 hour. In this way, an intermediate coating film having a thickness of 10 μm was prepared. A gloss-adjusting coating film was produced on the surface in the same manner as in the production of the coated metal plate 5, and a coated metal plate 113 having a coating original plate, a colored coating film, an intermediate coating film, and a gloss-adjusting coating film in this order was produced. Ra of the painted metal plate 113 was 346 nm.

[Manufacturing of painted metal plate 114]
The colored paint 5 is applied to the surface of the coated original plate 3, the coated original plate 3 coated with the colored paint 5 is heated so that the reaching temperature of the plated steel sheet reaches 250 ° C., and then immersed in water at 30 ° C. for cooling. Then, it was taken out of the water, the water was wiped off with a gauze, and the mixture was dried at 30 ° C. for 1 hour. In this way, a colored metal plate having a colored coating film having a thickness of 25 μm with the colored paint 5 was produced on the surface of the coating original plate 3.

The gloss adjusting paint 26 is applied to the surface of the colored metal plate, and the coated metal plate coated with the gloss adjusting paint 26 is heated so that the reaching temperature of the plated steel plate reaches 250 ° C., and the gloss adjusting coating thickness is 5 μm. I got a painted metal plate. The colored metal plate after heating at 250 ° C. is cooled to 200 ° C. by air cooling, and a satin-finished roll having a surface roughness Ra of 250 nm is pressed against the surface of the gloss-adjusting coating film which is still slightly soft, and the satin-finished roll is pressed on the surface of the coating film. The unevenness of was transferred. The temperature of the coated metal plate when it was separated from the coated metal plate after being pressed by the satin roll was 160 ° C.

Next, the metal plate after the uneven transfer was immersed in water at 30 ° C. for further cooling, then taken out of the water, wiped off with gauze, and dried at 30 ° C. for 1 hour. In this way, the painted metal plate 114 was produced. Ra of the painted metal plate 114 was 261 nm.

[Manufacturing of painted metal plate 115]
A projection material (nylon resin beads with an average particle size of 400 μm) was applied to the surface of the coated metal plate 93 using a blasting device (“Pneumatic Blaster SCM-1ADE-401” manufactured by Fuji Seisakusho Co., Ltd.) at a discharge pressure of 0.2 MPa. The surface was roughened by spraying with the air of the above, thus producing a coated metal plate 115. Ra of the painted metal plate 115 was 542 nm.

[Evaluation]
(1) Initial workability Each of the coated metal plates 1 to 115 is bent by 4T and subjected to a salt spray test specified by JIS K5600-7-1 for 500 hours to check the corroded state of the bent portion. It was evaluated according to the following criteria. The evaluation of "○" below is considered to have long-term outdoor durability at this level.
◎: No abnormality such as rust and blisters ○: 1, 2 places, minute blisters or rusts ×: Rust occurs on the entire processed part (There is a problem in practical use)

(2) Workability after storage Each of the coated metal plates 1 to 115 is allowed to stand in an environment of 60 ° C. for 7 days, then subjected to the above 4T bending process, and a salt spray test specified by JIS K5600-7-1. The corrosion state of the processed portion subjected to the above bending was evaluated according to the following criteria. The above-mentioned standing condition is a condition that reproduces the crystallization and ductility decrease of the fluororesin due to long-term storage at room temperature.
◎: No abnormality such as rust and blisters ○: 1, 2 places, minute blisters or rusts ×: Rust occurs on the entire processed part (There is a problem in practical use)

(3) Color tone Each of the coated metal plates 1 to 115 and the reference coated metal plate having the same clear paint resin component and pigment particles are measured by JISZ8722 5 (spectrophotometric method), and the color difference is obtained. It was. If the color difference is 1.5 or less, it is considered as a pass.

The reference coated metal plate has a coating original plate 3 and a colored coating film arranged on the surface thereof, and the colored coating film is a coating film made of any of clear paints 1 to 8 and has 10 volumes. %% Colored pigment particles and 1.5% by volume of gloss adjusting agent particles (Silysia 4, "Silicia 770" manufactured by Fuji Silysia Chemical Ltd., average particle size: 6.0 μm). The configuration of the standard coated metal plate is one of the typical coating film configurations of the conventional fluororesin-coated metal plate for exterior building materials. The thickness of the colored coating film on the standard coated metal plates for the coated metal plates 1 to 7 and 58 to 115 is 25 μm, and the thickness of the colored coating film on the standard coated metal plates for the coated metal plates 8 to 57 is 25 μm. It is 22 μm.

(4) Gloss The mirror gloss (G60) of each of the coated metal plates 1 to 115 at 60 degrees defined by JIS K5600-4-7 was measured. For exterior applications, 40 or less can be passed.

The configurations, physical properties and evaluation results of the coated metal plates 1 to 115 are shown in Tables 5 to 9.

[Workability]
As is clear from Tables 5 to 9, the initial workability is good in any of the coated metal plates. Immediately after production, the fluororesin does not crystallize over time, and the colored coating film is in a state of extremely high ductility. Therefore, regardless of the particle size and content of the pigment particles in the colored coating film. , It is considered that the colored coating film of any of the coated metal plates has high ductility.

However, a coated metal plate (painted metal plate) in which the total content of pigment particles in the colored coating film is more than 12% by volume, or the content of particles having a particle size of more than 3 μm is more than 1% by volume. In 1, 3, 8, 11, 16, 18, 24-26, 28-31, 38-42, 48, 49, 53 and 54), the workability after storage is insufficient. This is because the fluororesin constituting the colored coating film progresses with storage, and the voids formed in the colored coating film during the bending process grow due to stress concentration, which is a corrosion factor that crosses the colored coating film. It is probable that the passage was formed.

On the other hand, if the average particle size of the pigment particles in the colored coating film is 2.0 μm or less and the content of the fluororesin in the base resin in the colored coating film is 70% by mass or more, the processability after storage is also good. It is enough. And, in particular, as is clear from the coated metal plates 4 to 7, 10, 12 to 15, 21 to 23, 33 to 37, 47, 52, and 61 to 115, the smaller the average particle size of the pigment particles, the more. Alternatively, the lower the content of the pigment particles, the lower the content of the relatively large particles of the pigment particles is, or the higher the content of the fluororesin in the base resin in the colored coating film. It can be seen that the workability after storage becomes better. It is considered that when the content of the fluororesin was high, the content of the acrylic resin having a lower ductility than the crystallized fluororesin was relatively low.

[Color tone]
As is clear from Tables 5 to 9, when the content of the colored pigment in the colored coating film is 2.0% by volume or more, the color difference from the standard coated metal plate is 1.5 or less, which is the desired design. It can be seen that sex is expressed. However, as is clear from the coated metal plates 15, 23 and 27, when the content is less than 2% by volume, the color difference from the reference plate is larger than 1.5. It is considered that this is because the color hiding property by the colored pigment particles in the colored coating film is insufficient and the color tone of the base is strongly transparent.

[Low gloss]
As is clear from Tables 5 to 9, when the gloss adjusting coating film contains a gloss adjusting agent pigment, embossing transfer is performed on the surface of the gloss adjusting coating film, or the surface is ground by a blasting treatment. It can be seen that the higher the arithmetic average roughness Ra of the gloss adjusting coating film, the lower the mirror surface gloss G60 tends to be, and when Ra is 200 nm or more, G60 is 40 or less.

More specifically, the coated metal plates 1 to 69, 71 to 74, 76 to 79, 81 to 85, 87, 88, 90, 91, 112 and 113 are all gloss adjusting agent particles (gloss adjusting agent particles) in the gloss adjusting coating film. Since the average particle size of the silica particles) is 2.8 μm or more and the content of the gloss adjusting agent particles in the gloss adjusting coating is 0.5% by volume or more, the surface roughness Ra of the gloss adjusting coating is increased. The glossiness is 320 nm or more, and the 60-degree mirror surface glossiness G60 is 40 or less, which is a sufficiently low glossiness. Further, the coated metal plates 114 and 115 show a sufficiently low gloss property such that the surface roughness of the gloss adjusting coating film is 200 nm or more and the 60 degree mirror surface gloss G60 is 40 or less.

When pigment particles having a particle size of more than 5.5 μm (aggregated particles of pigment particles 3, pigment particles 7, and pigment particles 8) are contained in the colored coating film, the larger the particle size of these pigment particles, the more. As the blending amount was larger, the surface roughness of the coated metal plate was further slightly increased, and the 60-degree mirror surface gloss G60 was further slightly reduced. It is considered that this is because the unevenness of the colored coating film is improved by the pigment particles having a large particle size, and this unevenness also contributes to the improvement of the unevenness of the surface of the gloss adjusting coating film.

In each of the coated metal plates 93 to 111, the gloss adjusting coating film is composed of only fluororesin. In these coated metal plates, the higher the arithmetic mean roughness Ra of the gloss adjusting coating film, the lower the mirror surface gloss G60 tends to be, and it can be seen that when Ra is 50 nm or more, G60 is 40 or less.

In addition, the lower the cooling rate after baking during the production of the gloss-adjusting coating film, the higher the average particle size and area ratio of the fluororesin crystals tend to be. It is considered that this is because the cooled fluororesin can stay in the crystallization temperature range for a long time by lowering the cooling rate, and a sufficient time for the crystals (spherulite) to grow is secured.

Further, the higher the content of the fluororesin in the topcoat base resin in the gloss adjusting coating film, the higher the average particle size and surface area ratio of the fluororesin crystals tend to be. It is considered that this is because the higher the content of the fluororesin forming the spherulite, the easier the growth of the spherulite, and the larger and more spherulite is formed.

As is clear from the coated metal plates 95 to 99, 103, 104, 106 to 111, the gloss is adjusted by setting the average particle size of the fluororesin spherulites to 10 μm or more and the area ratio of the spherulites to 50% or more. The surface roughness Ra of the coating film can be 50 nm or more, and the 60-degree mirror surface gloss G60 is 40 or less, which is a sufficiently low gloss property.

On the contrary, as is clear from the coated metal plates 93 and 94, when the cooling rate is high, the temperature of the fluororesin becomes lower than the crystallization temperature during the crystal growth, and the crystal growth stops. As a result, it can be seen that a sufficient size and number of irregularities are not formed on the surface of the gloss adjusting coating film.

Further, when the cooling start temperature at the time of producing the gloss adjusting coating film is higher than the melting point of the fluororesin, crystallization proceeds to the extent that sufficient unevenness is formed. It is considered that this is because the molecular chains of the fluororesin can move freely before crystallization, which makes it easier to form a crystal structure in the subsequent cooling step.

On the other hand, as is clear from the comparison of the coated metal plates 99 to 101, when the cooling start temperature is equal to or lower than the melting point of the fluororesin, both the average particle size and the surface ratio of the crystals are insufficient. The reason for this is considered as follows. That is, when the reheating temperature is equal to or lower than the melting point, the arrangement structure of the fluororesin is a state in which α crystal, β crystal, and amorphous portion are mixed. Since crystal structures with large interactions are mixed, the barrier to recombining this sequence is large, and a large particle size spherulite structure is formed even if it stays in the crystallization temperature range for a long time in the subsequent slow cooling step. It is probable that it did not reach the point.

Further, when the cooling end temperature is equal to or lower than the crystallization temperature of the fluororesin, sufficiently large crystals grow, whereas when the cooling end temperature is equal to or higher than the crystallization temperature (for example, the coated metal plate 102), the crystals grow. Both the average particle size and the surface ratio of the above are insufficient. The reason for this is considered as follows. That is, when the cooling end temperature is equal to or higher than the crystallization temperature, the formation of large particle size crystals has not progressed sufficiently at the end of cooling, and the state of insufficient crystal formation is preserved by the subsequent quenching. it is conceivable that.

The coated metal plate of the present invention can impart designability by colored pigment particles even if it is a fluororesin-based coating film, can realize low glossiness, and exhibits high processability even after storage. Therefore, further spread of fluororesin-based coated metal plates is expected, especially as a material for exterior building materials.

Claims (4)

In a coated metal plate having a metal plate, a colored coating film arranged on the metal plate, and a gloss adjusting coating film arranged on the colored coating film.
The colored coating contains a base resin constituting the film structure of the colored coating with a fluorine-containing resins and acrylic resins, and pigment particles dispersed in a prior SL colored coating,
The pigment particles are selected from the group consisting of organic coloring pigment particles, inorganic coloring pigment particles, composite oxide fired pigment particles, metallic pigment particles, pearl pigment particles, and a combination thereof, on average. Contains colored pigment particles with a particle size of 2.0 μm or less,
The thickness of the colored coating film is 50 μm or less, and the thickness is 50 μm or less.
The content of the fluororesin in the base resin is 50 to 85% by mass.
The content of the pigment particles in the colored coating film is 2 to 12 % by volume.
The content of the colored pigment particles in the colored coating film is 2 to 12 % by volume.
The content of particles having a particle size of more than 3 μm in the colored coating film is 1% by volume or less.
The gloss-adjusting coating film is composed of a topcoat base resin containing a fluororesin and an acrylic resin, and also contains spherulites that form irregularities on the surface of the gloss-adjusting coating film of the topcoat base resin. , The arithmetic average roughness of the surface of the gloss adjusting coating film is 50 nm or more.
The content of the fluororesin in the topcoat base resin is 50 to 85% by mass.
The average value of the spherulite sizes is 10 μm or more, and the area ratio of the spherulites in the gloss-adjusting coating film when the gloss-adjusting coating film is viewed in a plan view is 50% or more.
Painted metal plate. In a coated metal plate having a metal plate, a colored coating film arranged on the metal plate, and a gloss adjusting coating film arranged on the colored coating film.
The colored coating contains a base resin constituting the film structure of the colored coating with a fluorine-containing resins and acrylic resins, and pigment particles dispersed in a prior SL colored coating,
The pigment particles are selected from the group consisting of organic coloring pigment particles, inorganic coloring pigment particles, composite oxide fired pigment particles, metallic pigment particles, pearl pigment particles, and a combination thereof, on average. Contains colored pigment particles with a particle size of 2.0 μm or less,
The thickness of the colored coating film is 50 μm or less, and the thickness is 50 μm or less.
The content of the fluororesin in the base resin is 50 to 85% by mass.
The content of the pigment particles in the colored coating film is 2 to 12 % by volume.
The content of the colored pigment particles in the colored coating film is 2 to 12 % by volume.
The content of particles having a particle size of more than 3 μm in the colored coating film is 1% by volume or less.
The gloss-adjusting coating film contains the topcoat base resin constituting the film structure and the first gloss-adjusting agent particles dispersed in the gloss-adjusting coating film, and the surface of the gloss-adjusting coating film. The arithmetic mean roughness of is 200 nm or more,
The first gloss modifier particles are composed of silica particles, calcium carbonate particles, acrylic resin particles, urethane resin particles, benzoguanamine resin particles, styrene resin particles, polyethylene resin particles, polypropylene resin particles, fluororesin particles, and a combination thereof. Particles with an average particle size of 2.8 to 15 μm selected from the group.
The content of the first gloss adjusting agent particles in the gloss adjusting coating film is 0.5 to 3.0% by volume.
Painted metal plate. The coated metal plate according to claim 1 or 2 , wherein the content of the fluororesin in the base resin is 70 to 85% by mass. The pigment particles are selected from the group consisting of silica particles, calcium carbonate particles, acrylic resin particles, urethane resin particles, benzoguanamine resin particles, styrene resin particles, polyethylene resin particles, polypropylene resin particles, fluororesin particles, and combinations thereof. The second gloss modifier particles, which are particles having a particle size of 3 μm or less, are further contained.
The content of the second gloss adjusting agent particles in the colored coating film is 0.2 to 1.0% by volume.
The coated metal plate according to any one of claims 1 to 3.

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