JPH07252634A - Alkali resistant metallic plate and production thereof - Google Patents

Abstract

PURPOSE:To provide a ceramic coated metallic plate applicable even in alkaline atmosphere and excellent in decorativeness and alkali resistance. CONSTITUTION:The variation of color due to interference color is imparted by forming a titanium oxide layer provided with the property of high refractive index and 0.03-5mum in thickness on a metallic plate and simultaneously, the property of the titanium oxide layer excellent in alkali resistant is utilized and therefor, the titanium oxide layer is formed on the metallic plate such as stainless steel. For example, a coil type stainless steel 370mm wide, 300mm long and 0.3mm thick, on which titanium oxide is coated by 0.06mum in thickness by sputtering, shows light blue having high freshness and is free from change in color tone in immersion test in 2wt.% NaOH aq. solution and the deterioration of the film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic-coated metal plate having excellent decorativeness and alkali resistance, which can be used as an interior decoration member, a building material, an automobile or the like in an alkaline environment.

[0002]

2. Description of the Related Art With the development of electronics technology, dry processes such as physical vapor deposition and chemical vapor deposition have begun to be applied to the surface modification of metallic materials.

Due to such technological progress, it is possible to obtain a metal material coated with ceramics, which cannot be obtained by a conventional wet process such as plating, and which is provided with functions such as weather resistance, abrasion resistance and decorativeness. Has become.

However, it is not suitable for mass production, the running cost is high, the equipment is expensive, and the like, and there are many problems in terms of cost. It is still difficult to replace.

In the field of decoration, for example, TiN, which has a high-class appearance in view of the high-class trend in the world,
The golden decorative coating of is an example of successful industrialization.

In the decorative coating, in addition to the above-described TiN gold color, so far, a color utilizing a material color such as TiC black, or a color of a transparent ceramic coating such as an oxide of aluminum or silicon is colored by light interference. There are so-called color coating decoration materials (for example, Japanese Patent Application Nos. 54-66385 and 54-85214).

However, the ceramic coating materials used for these conventional decorative coating materials have a problem that they have poor alkali resistance.

Particularly, in the case of a decorative material used for a floor or the like, it is an essential condition to maintain excellent decorative properties even when the floor is washed.

On the other hand, a vinyl chloride resin or the like is often used in combination with the metal substrate for the floor material, but since the vinyl chloride resin is weak against acid, an alkaline detergent is often used for the floor cleaning.

The conventional ceramic coating material has a problem that when it is cleaned with an alkaline detergent, the color tone of the coating material is changed, the film is cracked, the film is peeled off, and the decorative property is significantly impaired.

For example, when the surface of the gold coating film of TiN is cleaned with an alkaline detergent, the color changes to a blackish gold color, and when the light yellow coating film of aluminum oxide is similarly cleaned, There was a problem that the film was dissolved and the underlying metal was exposed.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems that conventional decorative coating materials are inferior in alkali resistance, and enables them to be used in a wide range of fields such as interior materials, building materials and automobiles. A metal plate having excellent alkalinity and a method for producing the same are provided.

[0013]

SUMMARY OF THE INVENTION The present invention is
It was discovered that the thin film titanium oxide formed by the dry process is superior in alkali resistance to bulk titanium oxide, and by forming the titanium oxide layer on the metal substrate, the ceramic coating film is inferior in alkali resistance. For the first time, it is possible to overcome the conventional drawbacks.

That is, a titanium oxide layer having a high refractive index is formed on a metal substrate, and a color variation due to an interference color is imparted based on the thickness of the titanium oxide layer, or the titanium oxide layer is formed. By using a property that the titanium oxide layer is excellent in alkali resistance while obtaining a transparent color tone without utilizing interference colors by making it thick.
On a metal substrate such as stainless steel, preferably 0.03-5 μ
m, and more preferably 0.03 to 10 from the viewpoint of manufacturing cost.
The present invention provides a ceramic-coated metal plate having a 0.2 μm-thick titanium oxide layer and excellent in decorativeness and alkali resistance.

Further, the metal plate of the present invention can be formed on a metal substrate in the form of
A titanium oxide layer having a thickness of 03 to 5 μm can be formed by ion plating and / or sputtering.

Further, by forming a portion of the titanium oxide layer close to the base substrate by ion plating and forming a portion close to the surface layer by sputtering, the adhesion to the substrate is excellent, and the stoichiometric composition of the surface layer portion of the film. It is possible to manufacture a high quality film with a strictly controlled ratio.

That is, the excellent decorativeness disclosed in the present invention is obtained by forming a titanium oxide layer having a high refractive index on a metal substrate in a film thickness range in which an interference effect is exerted. It utilizes that the color tone changes greatly.

Alternatively, it is possible to utilize the color tone of the metal substrate as it is without using the interference color by forming a titanium oxide layer in a film thickness range where the interference effect does not act on the metal substrate.

[0019]

Next, the alkali resistance of the metal plate of the present invention will be described.

Conventionally, the alkali resistance of thin film ceramics has not been sufficiently studied.

According to the Data Handbook, the alkali resistance of bulk ceramics is described as follows (Revised 3rd edition, Chemical Handbook Basic Edition I, The Chemical Society of Japan, p80 (1984)).

Al ₂ O ₃ : Insoluble in alkaline aqueous solution SiO ₂ : Insoluble in alkaline aqueous solution TiO ₂ : Insoluble in alkaline aqueous solution

However, as a result of carrying out an alkali resistance test using various ceramic-coated metal plates by dry coating, the inventors found that the alkali resistance of the thin film-like ceramics formed by dry coating and having a thickness of 5 μm or less is that of bulk ceramics. It was discovered that, unlike the characteristics, the titanium oxide film has excellent alkali resistance.

The alkali resistance test method, sample preparation method, and evaluation method will be described below.

<Alkali immersion test method> NaOH solution immersion solution: concentration 2 wt%, NaOH solution, 200 CC (using distilled water) Immersion time: one week Temperature: room temperature

Commercially available alkaline detergents have a pH of 11 to 11.
However, in this test, a stronger alkaline aqueous solution was used to perform a test in which the alkali resistance applicable range was widened.

Immersion in a commercial floor cleaning alkaline detergent (stock solution) pH: 12 Immersion time: one week Temperature: room temperature

<Sample preparation method> Film formation method: Film formation by a batch type high frequency magnetron sputtering apparatus (however, TiN and TiC used an ion plating apparatus) Film type: oxide-based Al ₂ O ₃ , SiO ₂ , TiO ₂ , TiAlO,
Nb ₂ O ₃ Nitride-TiN, ZrN Carbide-TiC (film thickness is 0.1 μm each) Substrate: SUS304 BA 0.3 mm thickness (3 after film formation)
It was cut to a size of 5 mm square and used for the test)

<Evaluation method of color tone change and film deterioration before and after immersion> 1. By visual judgment, observe the state of film deterioration such as film cracking and peeling. Color tone measurement by L ^* , a ^* , b ^* color system Here, "L ^* , a ^* , b ^* color system" is a color coordinate used by the International Commission on Illumination and has the following sensation. Indicates chromaticity. L ^* : Black ← − side, + side → White a ^* : Green ← − side, + side → Red b ^* : Blue ← − side, + side → Yellow (Measure three different points using a commercially available colorimeter. Then, the average value was obtained) 3. The color difference ΔE before and after the test was calculated, and the change in color tone was evaluated. The color difference ΔE was calculated by the following formula.

[0030]

[Equation 1] ΔE = [(ΔL) ² + (Δa) ² + (Δb) ² ] ^1/2

(ΔL, Δa, and Δb are differences in color tone before and after immersion)

Table 1 shows the above results. In addition, Table 2 shows the evaluation criteria of the color difference value.

As shown in Table 1, in the titanium oxide coating material, the color difference before and after the immersion in alkali was 1.3, and the evaluation judgment of the change in color tone was "slightly different".

Furthermore, the titanium oxide coating material did not show any deterioration such as cracking or peeling of the film.

On the other hand, in the coating materials other than titanium oxide, the color difference was 1.4 or more, the change in color tone was "perceptible to another color system", or the deterioration of the film was observed.

As the metal substrate, stainless steel, titanium,
Copper, steel, aluminum, etc. are used. In the present invention, the substrate is not particularly limited to these metals. However,
Of these, aluminum is an amphoteric metal that is soluble in both acid and alkali.

Therefore, aluminum is indispensable for the alkali resistance treatment even when it is used in an alkaline environment even in a bare material.

In the present invention, a ribbon-shaped or coil-shaped large-area substrate (for example, 370 mm × 300 m) is preferably selected so that it can be used particularly for building materials and automobiles.

The film thickness of titanium oxide is preferably in the range of 0.03 to 5 μm. The reason is that if the thickness is less than 0.03 μm, it is not enough to protect the metal substrate, and the maximum thickness is limited to 5 μm from the viewpoint of cost. This is because the adverse effect of causing cracking of the film also occurs during processing.

The titanium oxide film may be used in a film thickness range in which the interference effect acts or in a film thickness range in which the interference effect does not act, depending on the application.

For example, as the substrate, SUS304 BA
When SB is used in the range of 0.03 to 1.5 μm, a decorative metal substrate making the best use of the interference color is obtained, and in the range of more than 1.5 μm, the interference color is avoided and the metal A transparent decorative metal plate that takes advantage of the color tone of the plate can be obtained.

Further, the film thickness of titanium oxide is 0.03 to 0.
The range of 2 μm is more preferable. This is because it is preferable that the film thickness of titanium oxide is as thin as possible from the viewpoint of the manufacturing cost constraint caused by the productivity problem of the dry process, and the film thickness of the titanium oxide is the minimum in the range of 0.03 to 0.2 μm. This is because it is possible to provide a limited variety of colors.

That is, the interference color of the titanium oxide layer has a thickness of about 0.1 μm per cycle, the color tone changes periodically, and the color gradually becomes darker as the thickness is increased by repeating the cycle and the image clarity is improved. This is because the color variation of the cycle can be kept to a minimum if the film thickness is 0.2 μm.

The titanium oxide coated metal plate was prepared by
Use a dry process. Conventionally, as an example of coating a metal oxide, there is a method of dissolving a metal alkoxide or chelate in an alcohol solution and thermally decomposing it.

In this thermal decomposition coating method,
Although the environmental barrier property is improved to some extent, the produced film becomes a porous film peculiar to the process, and sufficient environmental resistance is not obtained.

Further, since it is difficult to control the film thickness, it is difficult to produce a desired interference color depending on the film thickness.

Other methods for producing a metal oxide include a spray method, a roll coating method, a spin coating method, etc., but the control of the film thickness is a bottleneck in all of them.

The dipping / pulling-up method is suitable from the viewpoint of the uniformity of the film thickness, but in this case, the film thickness is affected by the viscosity of the solution and the type of the substrate, and there is still a problem in controlling the film thickness. It was

In the present invention, by using the dry process, a metal substrate which has not been obtained in the past can be obtained.

Titanium oxide coating uses ion plating and / or sputtering as a dry process.

This is because, in the ceramic coated metal plate, the adhesion at the interface between the ceramic film and the metal substrate becomes a problem, but in the ion plating, the vapor deposition particles are ionized and collide with the substrate with high energy. This is because a film having good adhesion can be coated with good productivity.

Alternatively, in order to improve the quality of the titanium oxide film, it is necessary to strictly control the stoichiometric composition ratio of titanium and oxygen, and the sputtering easily coats the film having the intended stoichiometric composition ratio. Because you can.

In particular, in order to obtain an interference color having a high sharpness, it is preferable that the light absorption of the film is small, and for that purpose, a film having less oxygen deficiency of titanium oxide is preferable. If the oxygen deficiency is large, the absorption is large and the color of the film becomes dark.

Therefore, in the case of coating with titanium oxide, in order to improve the adhesion to the metal substrate, the layer close to the metal substrate is first subjected to ion plating, and then the stoichiometric composition ratio of titanium and oxygen is strictly controlled. However, in order to obtain an intended high quality film, it is more preferable to perform the remaining layer by sputtering.

In this case, the thickness of the lower layer formed by ion plating is not particularly limited, but 0.01 μm is sufficient from the viewpoint of the covering.

Further, when using both ion plating and sputtering, it is desirable that the lower layer and the upper layer of titanium oxide be continuously coated in the same chamber.

This is because when the vacuum is broken after the lower layer is formed and the sample is taken out into the atmosphere and then the upper layer is formed, the gas components in the atmosphere, particularly oxygen gas and water remain between the upper layer and the lower layer. This is because the interface between the upper layer and the lower layer separates and the quality of the film deteriorates.

In addition, the temperature of the metal substrate is raised and lowered by the operation of performing the upper layer and the lower layer in separate chambers, and internal stress is generated in the film, and cracks are generated in the coating layer because the internal stress is repeatedly increased and relaxed. This is because the adhesiveness is lowered between the metal substrate and the lower layer.

The present invention will be specifically described below with reference to examples.

[0060]

[Example 1] A substrate cleaning mechanism, ion plating,
Using a continuous coil coating facility in which sputtering devices are arranged in series, a width of 370 mm, a length of 300 m,
A coil-shaped austenitic stainless steel having a thickness of 0.3 mm is first coated with 0.01 μm thick titanium oxide by ion plating, and then sputtered to a thickness of 0.
It was coated with titanium oxide having a thickness of 05 μm.

Prior to coating, the substrate was subjected to ion bombardment treatment with argon gas in the cleaning room. The coating conditions are shown below.

<Coating conditions> ○ Fabrication process: ion plating and sputtering ○ Substrate: SUS304 BA SB 0.3 mm thick

[0063]

[Table 1]

[0064]

[Table 2]

The color tone of the obtained coating sample was blue with high freshness. Similarly, samples with different thicknesses of titanium oxide in the range of 0.06 to 5 μm were prepared,
An immersion test was performed for one week using a 2% concentration aqueous NaOH solution.

The color tone before and after the test was measured using a commercially available color difference meter according to the L *, a *, b * display and the color difference ΔE.
It was calculated. The results are shown in Table 3.

It can be seen that the color difference before and after the test is extremely small and there is almost no change in color tone. Further, no deterioration such as cracking or peeling of the film due to the test was observed at all.

Further, when the bending workability before and after the alkali resistance test was examined, 180 mm of 9 mmφ and 6 mmφ were obtained.
No cracking or peeling of the film was found in the degree bending test, and all samples passed the evaluation.

Further, a cleaning test was actually conducted using these stainless steels coated with titanium oxide. The coated stainless steel was placed on the floor, and a commercially available alkaline detergent for floor cleaning was applied and rubbed with a cleaning brush.

No film deterioration such as cracking or peeling of the film and change of color tone was observed. The pH of the alkaline detergent
Was 12.

[0071]

[Embodiment 2] Between the coil unwinding mechanism and the winding mechanism, a substrate cleaning mechanism, ion plating,
Using a continuous coil coating facility in which sputtering devices are arranged in series, a coiled aluminum 0.3 mm thick material having a width of 370 mm and a length of 300 m is first coated with titanium oxide having a thickness of 0.01 μm by ion plating, Subsequently, 0.18 μm thick titanium oxide was coated by sputtering.

Prior to coating, the substrate was subjected to ion bombardment treatment with argon gas in the cleaning room. The coating conditions are shown below.

<Coating conditions> ○ Fabrication process: ion plating and sputtering ○ Substrate: Al 0.3 mm thick

[0074]

[Table 3]

[0075]

[Table 4]

The color tone of the obtained titanium oxide was reddish purple with high freshness. Similarly, the thickness of titanium oxide is 0.5
Samples of 0 μm and 1.00 μm were prepared and the concentration was 2%
Immersion test was carried out for 1 week using the above NaOH aqueous solution.

Since aluminum dissolves in alkali, before the test, the non-coated portion of the substrate, that is, the back surface and the edge portion of the coated surface were sealed with an epoxy resin and subjected to an alkali resistance treatment, and then tested.

The color tones before and after the test were measured and calculated according to L *, a *, b * display and color difference ΔE using a commercially available color difference meter. The results are shown in Table 4.

The color tone of the interference color is influenced by the color tone of the substrate. Therefore, the difference between the values in Table 1 and Table 4 is due to the difference between the stainless steel and aluminum substrates.

It can be seen that the color difference before and after the test is extremely small and there is almost no change in color tone. Further, no deterioration such as cracking or peeling of the film due to the test was observed at all.

The bending workability before and after the alkali resistance test was examined.
No cracking or peeling of the film was found in the degree bending test, and all samples were evaluated as acceptable.

Further, a cleaning test was actually conducted using the aluminum coated with titanium oxide. The coated stainless steel was placed on the floor, and a commercially available alkaline detergent for floor cleaning was applied and rubbed with a cleaning brush. No film deterioration such as cracking or peeling of the film and change of color tone was observed.
The pH of the alkaline detergent was 12.

[0083]

[Table 5]

[0084]

[Table 6]

[0085]

[Table 7]

[0086]

[Table 8]

[0087]

As described above, according to the present invention, a titanium oxide film having a high refractive index is formed on a metal substrate to obtain a decorative material having a color variation due to an interference color. By coating the titanium oxide having excellent alkali resistance, it was possible to obtain a decorative metal plate in which the coating film did not deteriorate even after cleaning with an alkaline detergent.

As a result, it can be used in a wide range of fields such as interior / exterior decorative building materials, interior materials, and automobiles.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Naoto Ono, 3434 Shimada, Hikari-shi, Shimada, Nippon Steel Stock Company, Ltd. Inside the Hikari Steel Works (72) Inventor Isao Isoh 2-6-3 Otemachi, Chiyoda-ku, Tokyo Shin Nippon Steel Co., Ltd.

Claims (4)

[Claims] 1. An alkali-resistant metal plate excellent in decorativeness, comprising a metal substrate coated with a titanium oxide layer having a thickness of 0.03 to 5 μm. 2. The alkali-resistant metal plate having excellent decorativeness according to claim 1, wherein the titanium oxide layer is formed by a dry process. 3. A method for producing an alkali-resistant metal plate having an excellent decorative property, which comprises forming a titanium oxide layer having a thickness of 0.03 to 5 μm on a metal substrate by ion plating and / or sputtering. 4. The method for producing an alkali-resistant metal plate having excellent decorativeness according to claim 3, wherein a portion of the titanium oxide layer near the base substrate is formed by ion plating, and a portion near the surface layer is formed by sputtering.