JP6043889B1 - Painted metal plate - Google Patents

Abstract

An object of the present invention is to provide a coated metal plate having excellent stain resistance, no interference pattern, and excellent design. A coated metal plate is substantially composed of a metal plate having an average surface roughness Ra (metal plate) of 0.40 μm or less and at least one surface of the metal plate. (3.5 ≦ x <6.8) and a coating film having an average thickness t of 0.2 μm or more and 3.0 μm or less. The average thickness t of the coating film and the average surface roughness Ra (coating film) of the coating film satisfy the following formula (1). Ra (coating film) ≧ 0.03 / t + 0.15 (1) [Selection] None

Description

  The present invention relates to a painted metal plate.

  For conventional door materials such as elevators, operation panels, and the like, stainless steel plates having improved design properties by etching, coloring, surface treatment, and the like are used. These stainless steel plates are required to be resistant to fingerprints, high contamination resistance, high scratch resistance, and the like. Therefore, usually, a coating film made of resin, wax, oil or the like is formed on the surface of the stainless steel plate.

  However, when a coating film made of a resin is formed on the surface of a stainless steel plate, cracks and whitening occur in the coating film due to changes over time, and the design properties are easily impaired. Also, wax and oil had to be repainted regularly.

  Then, forming the coating film which consists of inorganic materials on the surface of a stainless steel plate is examined (for example, patent document 1). A coating film made of an inorganic material is advantageous in that it hardly changes over time and has high hardness.

  On the other hand, in recent years, the design of stainless steel sheets has been increased, and it has been demanded to provide a more delicate pattern on the surface of stainless steel sheets. For example, a method of increasing the design property by reducing the polishing depth of a stainless steel plate is employed.

JP 2009-1685 A

  Here, when a coating film made of an inorganic material is formed on the surface of a metal plate such as a stainless steel plate, the light reflected on the surface of the metal plate easily interferes with the light reflected on the surface of the coating, color unevenness, coloring, etc. (Hereinafter also referred to as “interference pattern”). In particular, in a metal plate with high surface smoothness, an interference pattern is likely to occur because the amount of light regularly reflected on the surface is large and the coating film surface and the metal plate surface are likely to be parallel.

  As a technique for suppressing the interference pattern, it is conceivable to increase the thickness of the coating film formed on the surface of the metal plate. However, in this case, there is a problem that the texture (metal feeling or the like) derived from the metal plate is easily lost and the design property is easily impaired. Moreover, in order to suppress an interference pattern, although it is also considered that an aggregate is included in a coating film, also in this case, the transparency of the coating film is likely to be lowered and the designability is easily impaired.

  In view of such a situation, the present invention has been made. That is, an object of the present invention is to provide a coated metal plate having excellent stain resistance, no interference pattern, and excellent design.

The present invention provides the following coated metal plates.
[1] A _{metal plate} having an average surface roughness Ra _{(metal plate)} of 0.40 μm or less and a composition formula K ₂ O.xSiO ₂ (3. 3) formed on at least one surface of the metal plate. 5 ≦ x <6.8), and having an average thickness t of 0.2 μm to 3.0 μm, the average thickness t of the coating film and the coating film A coated metal plate in which the average surface roughness Ra _{(coating film)} satisfies the following formula (1).
Ra _{(coating film)} ≧ 0.03 / t + 0.15 (1)

[2] The coated metal plate according to [1], wherein the average thickness t of the coating film and the average surface roughness Ra _{(coating film)} of the _{coating film} further satisfy the following formula (2).
Ra _{(coating film)} ≧ 0.08 / t + 0.12 (2)

  ADVANTAGE OF THE INVENTION According to this invention, the coating metal plate which was excellent in stain resistance, an interference pattern does not arise, and was excellent in the designability is obtained.

The present invention relates to a metal plate having a relatively smooth surface, that is, a metal plate having an average surface roughness Ra _{(metal plate)} of 0.40 μm or less, and a coating film made of an inorganic material formed on the metal plate. And a painted metal plate. The said metal coating plate is applicable to the door material of an elevator, an operation panel, the outer plate | plate of household appliances, furniture, furniture, a building material etc., for example.

  As described above, it has been studied to form a coating film made of an inorganic material on the surface of the metal plate for the purpose of increasing the contamination resistance of the metal plate. However, when a coating film made of an inorganic material is formed on the surface of the metal plate with high surface smoothness, the light reflected on the surface of the metal plate and the light reflected on the surface of the coating film easily interfere with each other, and an interference pattern is likely to occur. On the other hand, when the thickness of the coating film is increased and the interference pattern is suppressed, the texture derived from the metal plate is likely to be impaired, and the design property is likely to be lowered.

On the other hand, the present inventors satisfy the predetermined relationship between the average thickness t of the coating film formed on the surface of the metal plate and the average surface roughness Ra _{(coating film)} of the coating film. It was found that an interference pattern hardly occurs even when the thickness is thin, and a coated metal plate excellent in design is obtained. Specifically, when the average thickness t of the coating film and the average surface roughness Ra _{(coating film)} of the _{coating film} satisfy the following formula (1), an interference pattern is hardly generated.
Ra _{(coating film)} ≧ 0.03 / t + 0.15 (1)
In addition, the average thickness t of a coating film is 0.2 micrometer or more and 3.0 micrometers or less.

The reason why the interference pattern hardly occurs when the average thickness t of the coating film and the average surface roughness Ra _{(coating film)} of the _{coating film} satisfy the above formula (1) is as follows. As the thickness t of the coating film formed on the metal plate is thinner, the light reflected on the surface of the metal plate and the light reflected on the surface of the coating film are more likely to interfere with each other, and an interference pattern is more likely to occur. Therefore, in the coated metal plate of the present invention, the coating film is formed so that the surface roughness Ra _{(coating film)} of the surface of the coating film increases as the thickness t of the coating film decreases. When the coating film surface has moderate unevenness, the direction of light reflected on the coating film surface and the direction of light reflected on the metal plate surface and emitted from the coating film surface are likely to vary. As a result, the light reflected on the coating film surface and the light reflected on the metal plate surface are less likely to interfere with each other, and an interference pattern is less likely to occur.

Here, it is preferable that the average thickness t of the coating film and the average surface roughness Ra _{(coating film)} of the _{coating film} further satisfy the following formula (2). When the average thickness t of the coating film and the average surface roughness Ra _{(coating film) of the coating film} satisfy the formula (2), an interference pattern is hardly generated.
Ra _{(coating film)} ≧ 0.08 / t + 0.12 (2)

However, if the average surface roughness Ra _{(coating film) of the coating film} is excessively large, the glossiness and the like of the coated metal plate may be lost and the designability may be deteriorated. Therefore, the upper limit value of the average surface roughness Ra _{(coating film)} of the _{coating film} is preferably 0.8 μm, and more preferably 0.4 μm.

Moreover, although the average thickness t of a coating film should just be 0.2 micrometer or more and 3.0 micrometers or less, it is more preferable that it is 0.2-1.0 micrometer. When the average thickness t of the coating film becomes excessively thick, the texture derived from the metal plate tends to be impaired in the coated metal plate. On the other hand, if the average thickness t of a coating film is 3.0 micrometers or less, the light transmittance of a coating film will become favorable and it will become easy to obtain the coating metal plate with high design property. In addition, when the coating film has the above average surface roughness Ra _{(coating film)} , when the average thickness t of the coating film is 0.2 μm or more, the coating film is easily formed on the surface of the metal plate without any gaps. The corrosion resistance of the metal plate tends to be good.

The average surface roughness Ra _{(metal plate) of} the _{metal plate} and the average surface roughness Ra _{(coating layer)} of the _coating surface are values measured according to JIS B0601: 2001, respectively, and are known surfaces. It can be measured by a roughness measuring machine or the like. Moreover, the average thickness t of a coating film is measured by cutting out a coating metal plate arbitrarily and observing a cross section. Specifically, after embedding a test piece cut out from a coated metal plate with a resin, an appropriate cross section is prepared by polishing or the like. Furthermore, a highly accurate observation cross section is produced by ion milling or the like. And about arbitrary 10 places, it observes by SEM and TEM, and let the average of 10 thickness be the average thickness t.

  In the coated metal plate of the present invention, the coating film may be formed on only one surface of the metal plate, or may be formed on both surfaces. Moreover, the coating film may be formed only in the one part area | region of the metal plate, and may be formed in all the area | regions of one side or both surfaces of a metal plate.

Moreover, it is preferable that the average value of the coating film coverage per 1 mm ² (hereinafter, also referred to as “average coating film coating rate”) of any 10 places having the coating film of the coated metal plate is 95% or more, It is particularly preferable that the metal plate is formed without a gap. In addition, the shape of the area (1 mm ² ) for specifying the coating film coverage is not particularly limited, and may be any shape such as a rectangular shape such as a square or a rectangle, or a circular shape. is there. The average coating film coverage is specified by the following method.

Si element distribution is measured at any 10 locations (1 mm ² region) out of regions where a coating film is formed by SEM (scanning electron microscope) / EDS (energy dispersive X-ray spectroscopy). . Subsequently, the obtained Si distribution image is binarized by image processing software. In binarization, a region where Si is increased even a little is treated as a region where the coating film exists, based on the Si detection value of the coating film non-formed part (metal plate). Then, from the obtained binarized image, the number of pixels in the area where Si is increasing (area where the coating film exists) is divided by the total number of pixels to calculate the coating film coverage. And let the average value of these coating-film coverage be an average coating-film coverage.

Here, the metal plate should just be a metal plate whose average surface roughness Ra _{(metal plate)} is 0.40 micrometer or less, More preferably, average surface roughness Ra _{(metal plate)} is 0.05-0. 35 μm. As such a metal plate, for example, austenitic stainless steel such as SUS304 or SUS316 or ferritic stainless steel such as SUS430 can be used. In applications where mechanical strength is required, materials obtained by cold hardening austenitic and ferritic stainless steel, martensitic stainless steel plates such as SUS410 and SUS420, and precipitation strengthened stainless steel plates such as SUS631 are used. It is preferable to use it. In addition to the stainless steel plate, copper, carbon steel, iron-nickel alloy, various plated steel plates, and aluminum plates may be used.

  These metal plates may be subjected to surface processing according to a conventional method. For example, the metal plate may have a smooth surface finish such as a BA finish or a mirror finish, and may have been subjected to a linear polishing process such as an HL finish for design and functionality. May be. Further, it may be subjected to curved polishing such as vibration polishing, or may be subjected to dot-like uneven processing. Further, it may be colored by various methods such as oxidation coloring or sputtering coloring.

On the other hand, the coating film is substantially composed of a composition represented by the composition formula K ₂ O · xSiO ₂ (3.5 ≦ x <6.8), and is composed of potassium silicate (K ₂ O · nSiO ₂ (2 ≦ n ≦ 4) and colloidal silica (SiO ₂ ) can be applied and dried to form a film, wherein the compositional formula K ₂ O · xSiO ₂ represents the element in the coating film. In the coating film, SiO ₂ usually forms a siloxane bond, whereas potassium becomes a potassium ion and a silicate ion that is not bonded to a siloxane bond. It exists with electrical attraction.

The ratio of silicon oxide (SiO ₂ ) to potassium oxide (K ₂ O) represented by x in the above composition formula may be 3.5 or more and less than 6.8, but 3.8 or more and 5.2. The following is more preferable. When the value represented by x is less than 3.5, potassium ions are excessively eluted on the surface of the coating film, and a white flower phenomenon occurs in which the eluted potassium ions react with carbon dioxide in the atmosphere to form carbonates. It becomes easy. On the other hand, when the value represented by x is 6.8 or more, it is necessary to mix a large amount of colloidal silica at the time of coating film formation. As a result, the film-forming property is lowered and the film may not have sufficient strength. In addition, the composition of the said coating film can be adjusted with the mixing ratio etc. of potassium silicate and colloidal silica. The composition of the coating film can be confirmed by EDS, XRF, EPMA, etc., and the chemical bonding state of Si can be confirmed by XPS, IR, or the like.

In the coated metal plate of the present invention, since the coating film is composed of a composition represented by the composition formula K ₂ O · xSiO ₂ (3.5 ≦ x <6.8), the stain resistance is high. The reason is guessed as follows. In the coating film comprising the above composition, potassium is slightly eluted on the surface. And a potassium ion hydrates with the water | moisture content in air | atmosphere, and draws the water | moisture content in air | atmosphere. As a result, the entire surface of the coated metal plate is covered with a thin water film. Therefore, even if oil stains such as sebum and oil-based ink adhere to the surface of the coated metal plate, the stains will float on the water film, and the stains can be easily removed by wiping or the like.

  In general, when time passes after the dirt adheres to the surface of the coated metal plate, some components of the dirt may impregnate the coating film or the metal plate, and it may be difficult to remove the dirt. On the other hand, in the coated metal plate according to the present invention, since a water film having a sufficient thickness exists on the surface, the dirt component hardly penetrates into the coated metal plate. Furthermore, since the coating film has high hydrophilicity, water easily penetrates between the surface of the coated metal plate and the dirt. Therefore, it becomes possible to remove the dirt adhering to the surface of the painted metal plate by wiping with water or the like. The hydrophilicity of the coating film is considered to be expressed by the high hydration property of potassium ions slightly eluted on the surface of the coating film and the hydrophilicity of the silanol group.

  Here, the said coating film is obtained by apply | coating the liquid mixture of potassium silicate and colloidal silica on a metal plate by the method mentioned later, and making it dry. The potassium silicate and colloidal silica for forming the coating film may be general reagents or industrial chemicals. Examples of commercially available potassium silicate products include “A potassium silicate” and “2K potassium silicate” manufactured by Nippon Chemical Industry Co., Ltd., “No. 2 potassium silicate” manufactured by Fuji Chemical Co., Ltd., “ Snowtex K2 "etc. are included. On the other hand, examples of commercially available colloidal silica include “Adelite AT” manufactured by ADEKA, “Snowtex” manufactured by Nissan Chemical Co., Ltd., and “Silica Doll” manufactured by Nippon Chemical Industry Co., Ltd. Moreover, you may add a solvent, a leveling agent, an antifoamer, etc. to the liquid mixture for coating-film formation with potassium silicate and colloidal silica as needed.

The application method of the liquid mixture for forming the coating film is not limited as long as the coating film can be formed so that the average thickness t of the coating film and the average surface roughness Ra _{(coating film) of the coating film} satisfy the formula (1). . However, it is easy to level the mixed solution simply by applying the mixed solution on the metal plate by a general coating method (for example, roll coating method, curtain flow coating method, bar coating method, spraying method, etc.). It is difficult to obtain a coating film in which the thickness t and the average surface roughness Ra _{(coating film)} satisfy the above formula (1).

Here, as an example of a technique for obtaining a coating film satisfying the above formula (1), there is a method in which an atomizing spray method is employed, and the mixed liquid is applied and dried in a plurality of times. According to the atomizing spray method, it is possible to control (atomize) the particle size of the mixed solution emitted from the spray discharge nozzle smaller than in the conventional spray method, and the mixed solution has landed (applied) on the steel plate. Leveling can be suppressed. Further, since the amount of coating per coating can be reduced, the thickness can be easily controlled (thinned), and the number of repetitions of coating and drying can be increased. And by repeating small amount application and drying of a liquid mixture, average surface roughness Ra _{(coating film)} becomes large gradually, and the _{coating film} which satisfy | fills above-mentioned Formula (1) is formed.

Moreover, the method of reducing the quantity of the non-volatile components (potassium silicate and colloidal silica) in the liquid mixture apply | coated on a metal plate, and repeatedly apply | coating and drying a liquid mixture is also mentioned. When the amount of the non-volatile component in the mixed solution is small, the substantial coating film forming component per coating can be reduced. Thereby, it becomes easy to control (thin) the thickness, and the number of repetitions of application and drying can be increased. Then, by repeating such application and drying of the mixed solution, the average surface roughness Ra _{(coating film)} gradually increases, and a coating film satisfying the above-described formula (1) is formed. In this case, the amount of non-volatile components in the mixed solution is appropriately selected according to the desired thickness t of the coating film and the average surface roughness Ra _{(coating film)} , but for example 4% by mass with respect to the total amount of the mixed solution Less than.

  Moreover, the drying time and drying temperature of a liquid mixture are suitably selected according to the quantity and kind of solvent which are contained in a liquid mixture.

When the atomizing spray method is adopted, the number of coatings depends on the adjustment of the coating amount (spray time) per coating and the average thickness t and average surface roughness Ra _{(coating film)} of the target coating film. Usually, it is preferably about 2 to 20 times, more preferably about 4 to 12 times.

  As an example of a method of forming the above-mentioned coating film by the atomizing spray method, there is a method of reciprocating the atomizing spray gun perpendicularly to the traveling direction of the metal plate while conveying the metal plate at a low speed by a conveyor or the like. . According to this method, it is possible to form a coating film efficiently and continuously.

Furthermore, after apply | coating a liquid mixture by the roll coat method, the method of further overcoating a liquid mixture by the atomization spray method is also employable. Conventionally, it is difficult to obtain an average surface roughness Ra _{(coating film)} satisfying the above formula (1) with a desired coating film thickness t by a roll coating alone, but surface roughness can be obtained by overcoating by an atomizing spray method. Can be given. According to this method, it is possible to form a coating film on the surface of the metal plate without any gap due to the uniform coating property that is a feature of roll coating. Therefore, according to the method, a coated metal plate having high corrosion resistance can be easily obtained.

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

  A coated metal plate was prepared by the following method, and for each, the contamination resistance of the surface and the presence or absence of interference patterns were confirmed. In addition, the metal plates AF shown in the following Table 1 were used for the metal plate.

[Preparation of mixture]
Potassium silicate (made by Fuji Chemical Co., Ltd., trade name: No. ₂ potassium silicate, K ₂ O · nSiO ₂ , n = 3.61) and colloidal silica (made by Nippon Chemical Industry Co., Ltd., trade name: Silica Doll) in terms of solid content The mixture was mixed at a mass ratio of 100: 13.3. The concentration of nonvolatile components (potassium silicate and colloidal silica) at this time was 3% by mass.

[Application of liquid mixture]
The mixed solution was applied to the metal plates A to F by the method shown in Table 2 (roll coating method, spray coating method, and / or atomizing spray method). Table 2 shows the number of times of application of the mixed solution by each method.
Moreover, the average thickness t of the obtained coating film was measured as follows. First, a coated metal plate was cut out, and the cut test piece was embedded in resin and then polished to produce a cross section. Further, a high-precision observation cross section was produced by ion milling or the like, and arbitrary 10 locations were observed with an SEM. And the average of the measured thickness of 10 places was made into average thickness t. Moreover, average surface roughness Ra _{(coating film)} of the obtained coating film was measured using a surface roughness measuring machine Surfcom 130A manufactured by Tokyo Seimitsu Co., Ltd. in accordance with JIS B0601: 2001. The measured values are shown in Table 2. Moreover, it was evaluated whether the average thickness t of a coating film and the average surface roughness Ra _{(coating film)} of a _{coating film} satisfy | fill following formula (1) or Formula (2), respectively. In the evaluation of Table 2, when the formula (1) or (2) was satisfied, it was marked as ◯, and when it was not satisfied, it was marked as x.
Ra _{(coating film)} ≧ 0.03 / t + 0.15 (1)
Ra _{(coating film)} ≧ 0.08 / t + 0.12 (2)

[Evaluation]
The coated metal plates obtained in each Example and Comparative Example were checked for the presence or absence of interference patterns and subjected to an oil-based ink removal test (contamination resistance). The results are shown in Table 2.

(1) Confirmation of interference pattern The presence or absence of the interference pattern was visually evaluated under a standard light source. As the standard light source device, trade name: Macbeth Judge II manufactured by X-Rite was used. The reference light was TL84. The interference pattern was evaluated according to the following criteria.
○: No occurrence (effect on design: none)
△: Slightly generated (effect on design: minor)
×: Significant occurrence (influence on design: yes)

(2) Oil-based ink removal test (contamination resistance)
It drew with the oil-based marker (The product made from Teranishi Chemical Industry, brand name: Magic ink (trademark) No. 700 black) on the coating metal plate obtained by the Example and the comparative example. Then, after 1 minute and 1 hour from the drawing, the oil-based ink in the drawing part was wiped off with a cloth impregnated with water (product name: Bencott M3-II), and traces of the oil-based ink after wiping with water were removed. The degree was evaluated. The trace of oil-based ink was evaluated according to the following criteria.
A: No trace (removal rate 100%)
A: There is very little trace (removal rate 90% or more to less than 100%)
Δ: Traces (removal rate 5% to less than 90%)
X: Almost no removal (removal rate less than 5%)

As shown in Table 2, when the average thickness t and the average surface roughness Ra _{(coating film)} of the _{coating film} do not satisfy the above formula (1) (when the evaluation is x), an interference pattern occurs. On the other hand (No. 2, 3, 18, 24, and 25), when the expression (1) is satisfied (when the evaluation is ◯), the interference pattern is hardly generated (No. 4 to 12, 14-16, 19-23, and 26). It is presumed that the light reflected on the surface of the metal plate and the light reflected on the surface of the coating film are less likely to interfere with each other by forming sufficient irregularities on the surface of the coating film. In particular, when the average thickness t and average surface roughness Ra _{(coating film)} of the _{coating film} satisfy the above formula (2) (when the evaluation is ◯), no interference pattern was generated (No .7-12, 14-16, 21-23, and 26). However, when the average thickness t of the coating film exceeded 3.0 μm, the texture derived from the metal plate was lost (No. 26). Further, even when the surface roughness Ra _{(metal plate) of the metal plate} exceeds 4.0 μm, no interference pattern was generated even if the surface roughness after coating did not satisfy the above-mentioned formula (1) (No. 13). ).

Moreover, when a coating film was not formed, the oil-based ink trace was not able to be removed in the oil-based ink test (No. 1). On the other hand, oil-based ink could be removed in any case by forming a coating film (No. 2-16, and 18-26). However, with regard to the composition constituting the coating film, when x in the composition formula K ₂ O · xSiO ₂ was less than 3.5, white flower was generated and the design property of the coated metal plate was lowered (No. 16). On the other hand, when x was 6.8 or more, film formation was not possible (No. 17). Furthermore, when the average thickness of the coating film was less than 0.2 μm, the coating film coverage was as low as 92%, and the corrosion resistance was reduced (No. 25).

  The coated metal plate of the present invention is excellent in stain resistance, has no interference pattern, and is excellent in design. Therefore, the coated metal plate can be applied to door materials and operation panels for elevators, outer plates for home appliances, furniture, furniture, various interior building materials, and the like.

Claims (2)

A _{metal plate} having an average surface roughness Ra _{(metal plate)} of 0.40 μm or less;
It consists of a composition substantially formed by the composition formula K ₂ O · xSiO ₂ (3.5 ≦ x <6.8) formed on at least one surface of the metal plate, and the average thickness t is 0.00. A coating film of 2 μm or more and 3.0 μm or less;
Have
The average thickness t of the coating film and the average surface roughness Ra _{(coating film)} of the _{coating film} satisfy the following formula (1).
Painted metal plate.
Ra _{(coating film)} ≧ 0.03 / t + 0.15 (1) The average thickness t of the coating film and the average surface roughness Ra _{(coating film)} of the _{coating film} further satisfy the following formula (2).
The coated metal plate according to claim 1.
Ra _{(coating film)} ≧ 0.08 / t + 0.12 (2)