JPH0617226A - Specular reflection plate having excellent workability and flawing resistance - Google Patents

Abstract

PURPOSE:To improve workability and flawing resistance by regulating the roughness of a steel sheet coated with a resin of a polyester system, etc., and controlling the film thickness of an aluminum film and amorphous oxide film to be formed thereon. CONSTITUTION:The resin film layer of the polyester resin system or fluororesin system is formed on the steel sheet and the center line average height of the surface is adjusted to be <=0.05mum. The aluminum film Ra of 0.01 to 0.2mum thickness is formed as a first layer on the surface of the org.-coated steel sheet formed with such resin film layer. The amorphous oxide film of 0.1 to 1.27mum thickness is formed on the aluminum film as a second layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a specular reflector having excellent workability and scratch resistance. More specifically, the present invention relates to a surface-treated steel sheet having a mirror surface that can retain the mirror surface even after processing.

[0002]

2. Description of the Related Art Mirror surface materials are widely used as headlights for automobiles and reflectors for lighting equipment, but their characteristics are required to have reflectance and sharpness. Currently, molded products are batch processed. Is manufactured by. In the past, there have been many reports on techniques relating to a mirror surface, a reflector, or a thin plate material having gloss. The features and problems of aluminum (Al) or metal deposition and ion plating are listed below.

(1) A method for treating a plastic molded article with a metallic luster (Japanese Patent Laid-Open No. 58-118831). (Characteristics) The surface of the plastic molded product is plasma-treated, and then a base coat coating film, a metal plating coating, and a top coat coating film are sequentially formed (hereinafter,
"Prior art 1"). (Problem) Prior art 1 is for a molded product,
The productivity is inferior because it has to be produced by batch processing.

(2) A method for forming a decorative material having a glittering metallic luster surface (Japanese Patent Laid-Open No. 60-67653). (Characteristics) A paint is applied to the surface of the material to make it smooth, and after this paint is dried, a metal is deposited on this surface by vapor deposition plating or ion plating. It is characterized by applying a low paint (hereinafter referred to as "Prior Art 2"). (Problem) The paint is soft and inferior in scratch resistance. In addition, it deteriorates due to aging and the glossiness is unstable.

(3) A method for surface treatment of an illumination light reflector (Japanese Patent Laid-Open No. 144606/55). (Characteristics) An oxide and boride film is vapor-deposited on the main body of the illuminating lamp reflection plate made of aluminum and an aluminum alloy, using oxides and borides as targets for sputtering (hereinafter, referred to as “Prior Art 3”). ")). (Problem) In the prior art 3, since the film thickness is 1 μm, sufficient reflectance cannot be obtained and workability deteriorates.

(4) Multilayer coating reflector (Japanese Patent Publication Sho 58-
27103 publication). (Feature) Resin layer, metal vacuum coating layer on the substrate,
A light-transmissive resin layer or a light-transmissive inorganic substance is sequentially formed, and either one or both of the resin layer and the light-transmissive resin layer on the substrate is a high aryl silicone resin. (Hereinafter, referred to as "Prior Art 4"). (Problem) Even if resin is coated on the substrate,
If the surface roughness is large, good reflectivity and image clarity cannot be obtained, so it is necessary to define the surface roughness of the base before the metal coating.

(5) Reflector (Japanese Patent Publication No. 58-33100). (Characteristics) A high aryl silicon resin layer, a vacuum coating layer of a bright metal, and a vacuum coating layer of a light-transmissive crystalline ceramic are sequentially formed on the substrate surface (hereinafter referred to as "prior art 5"). . (Problem) Since crystalline ceramics are harder than amorphous ceramics, they are not suitable for molding after coating.

(6) Method for manufacturing a reflecting mirror (Japanese Patent Laid-Open No. 52-9454)
Issue). (Characteristics) A high-purity aluminum film and a transparent protective film containing silicon oxide or silicon oxide as a single compound or as a compound are sequentially formed by dry coating on an aluminum or aluminum alloy substrate having a smooth surface by mechanical polishing. It is characterized (hereinafter referred to as "Prior Art 6"). (Problem) In Prior Art 6, since the aluminum film is about 3 μm, the workability after coating is deteriorated.

(7) Method for manufacturing a reflecting mirror (Japanese Patent Laid-Open No. 52-10741)
Issue). (Characteristics) Heat-resistant paint is applied to the surface of the base material to form a base film, on which a transparent protective film containing aluminum film, silicon oxide or silicon oxide alone or as a compound is sequentially formed by dry coating. (Less than,
"Prior art 7"). (Problem) In the prior art 7, since the aluminum film has a thickness of about 3 μm, the adhesion to the base is poor and the workability after coating deteriorates.

(8) Lighting device (Japanese Patent Publication No. 60-30041)
. (Characteristics) A transparent inorganic protective film is formed on the reflecting surface of the reflector installed in the high-intensity discharge lamp, and the film thickness is t = (4.48 ~
5.76) /n±0.05 μm (n is the refractive index of the transparent inorganic protective film) and is formed with a film thickness t (hereinafter referred to as “Prior Art 8”). (Problem) The refractive index of the transparent inorganic protective material is about 1.4 to 2.0, and the film thickness at this time is 2.0 to 4.1 μm. With this film thickness, workability deteriorates, and therefore it cannot be molded after coating.

[0011]

In the above-mentioned prior art, mirror finishing after molding is possible, but in batch processing of molded products, the application is limited to a small one such as a reflector. Therefore, an object of the present invention is to solve the above problems of the prior art,
It is intended to provide a moldable specular reflector which is excellent in workability, scratch resistance, reflection and sharpness.

[0012]

In order to solve the above-mentioned problems, the inventors of the present invention made an organic coated steel sheet coated with a polyester resin-based or fluororesin-based coating material in terms of material, and made the center of the surface thereof. By defining the line average roughness Ra and selecting the specific first layer and second layer on the coating surface, it is possible to obtain a mirror surface material that is inexpensive and has excellent sharpness, reflection, scratch resistance and processability. We obtained the finding that we can obtain it.

The present invention has been made on the basis of the above-mentioned findings, and is a polyester resin system in which a steel sheet is used as a base and the roughness of at least one surface thereof is a center line average roughness Ra of 0.05 μm or less, Alternatively, as a first layer formed on the surface of at least one of the organic coated steel sheet formed with a fluororesin-based resin coating layer and the organic coated steel sheet, 0.01
an aluminum film having a thickness in the range of μm to 0.2 μm, and formed on the surface of the aluminum film,
It is characterized in that it comprises an amorphous oxide film having a film thickness in the range of 0.1 μm to 1.2 μm as the second layer.

Next, the present invention will be described specifically and in detail with reference to the drawings. First, the thickness of the aluminum (Al) coating and the thickness of the amorphous oxide coating will be described. In Fig. 1, an organic coated steel sheet having a center line average roughness Ra (hereinafter referred to as "Ra") of 0.011 µm is coated with 0.005 to 1.0 µm Al by a vacuum deposition method, and its reflectance is measured. It is a thing. The reflectance is 100 on an alumina white plate.
%, And it was determined by relative comparison with this. When the thickness of Al film is as thin as 0.005 μm or 0.008 μm,
The reflectance was as low as 50% and 70%, respectively. on the other hand,
A good reflectance of 80% or more was obtained when the Al film thickness was 0.01 μm or more, and 85% or more when the Al film thickness was 0.05 μm or more. However, the Al film thickness is 0.2 μm
Above 80%, although it showed a good reflectance of 85% or more,
As the thickness of the Al film increased, the surface became cloudy and the image clarity deteriorated. One of the main causes of this white turbidity phenomenon is that as the thickness of the Al film becomes thicker, the deposition time becomes longer, and the surface of the Al film is heated by the radiant heat generated from the molten Al in the heated deposition crucible, and It is conceivable that the coating film of the coated steel sheet will deteriorate. Therefore, the film thickness of the Al film as the first layer needs to be within the range of 0.01 μm to 0.2 μm.

The thickness of the amorphous oxide film is 0.
When the film thickness is less than 1 μm, it has no effect as a protective film for the Al film and the reflectance is lowered. On the other hand, if it exceeds 1.2 μm, cracks will occur during processing, which is not suitable. Therefore, the thickness of the amorphous oxide film as the second layer is 0.
It is desirable that the thickness is in the range of 1 μm to 1.2 μm, preferably 1 μm or less. The amorphous oxide film in the present invention can form a transparent film SiO ₂ , Al ₂ O ₃ , MgO, Ti
O ₂ is preferred. For the evaluation of the workability, Erichsen processing was performed by 8 mm extrusion so that the mirror surface side became the concave portion, the surface of the concave portion was observed, and the presence or absence of cloudiness and cracks was evaluated.

The coating of the first layer and the second layer is performed by a vacuum deposition method which is a dry plating method, an ion plating method and a sputtering method. It is desirable to use an appropriate process from the viewpoint of productivity and adhesion.

Next, the base material coated with Al and the limitation on the surface roughness thereof will be described. FIG. 2 is a diagram showing the effect of surface roughness on the reflectance after Al coating. The surface roughness of the base material is JIS B O601 with a stylus roughness meter.
The center line average roughness Ra defined in Section 1 was used for evaluation. The reflectance is Ra
Is smaller, Ra is improved, and a reflectance of 80% or more is obtained in a roughness region where Ra is 0.10 μm or less. This satisfies the reflectance required as a reflector. Furthermore, Ra decreases
In the roughness region of 0.005 μm or less, a good reflectance of 83 to 90% was exhibited.

On the other hand, the image clarity after coating with Al can also be organized by Ra. FIG. 3 is a diagram showing the effect of Ra on the image clarity. Here, the sharpness is evaluated by reflecting a plate having a black-and-white striped pattern drawn at regular intervals through a test plate for measuring the sharpness, and identifying the reflected black-and-white striped pattern. did. With respect to the evaluation points, a commercially available mirror was 5, and a cold-rolled steel sheet with Ra of 0.3 μm was 1, and a 5-level sensitive evaluation was performed according to the difficulty of identification. The higher the evaluation point, the better the sharpness. It can be seen that when Al is coated on a base material having a different surface roughness, Ra is 0.005 μm or less and good image clarity is exhibited. This finding is based on previous reports (eg
1-177363), the present invention is characterized by coating an organic coated steel sheet with Al, and can provide a mirror surface material having excellent image clarity.

Therefore, in order to obtain a good image clarity with a reflectance of 80% or more, it is necessary that the organic coated steel sheet has Ra of 0.05 μm or less. In order to obtain an organic coated steel sheet having a surface roughness Ra of 0.05 μm or less, for example, a bright-finished steel sheet is used as a base, and the coating film is formed into three layers. A normal coated steel sheet has two coating layers, but such an organic coated steel sheet has a surface roughness Ra of 0.1 after coating.
Since it exceeds μm, it is not possible to obtain a specular reflector having excellent image clarity as in the present invention. As a base for the organic coated steel sheet (painted steel sheet), SPCD steel sheet for drawing specified in JIS G 3141 is suitable, but SPCC steel sheet may be used for applications where workability is not required so much. As the organic material formed on the surface of the base steel sheet, it is desirable to use a polyester resin-based or fluororesin-based coating material having good workability. Further, a steel plate laminated with a film of polyethylene, vinyl chloride, polyolefin, polyethylene terephthalate, polytetrafluoroethylene, or the like can also be used.

[0020]

Next, the present invention will be described with reference to examples. Using a base material on which a polyester resin-based or fluororesin-based coating film having a centerline average roughness Ra shown in Table 1 is formed, a surface layer of the polyester resin-based or fluororesin-based coating film is used as a first layer. An Al film having a film thickness shown in 1 is formed, and then a second layer is formed on the surface of the Al film as a second layer.
An amorphous oxide film having a film thickness as shown in (1) was formed, and Specimens of specular reflectors (hereinafter referred to as "specimens of the present invention") Nos. 1 to 17 within the scope of the present invention were prepared. A coated steel plate was used as the base material to be coated. As the base of the coated steel sheet, SPCD steel sheet or SPCC steel sheet for drawing specified in JIS G 3141 was used. The coating of the Al film as the first layer and the amorphous oxide film as the second layer was carried out by a vacuum deposition method which is a dry plating method, an ion plating method or a sputtering method. Then, the reflectance, sharpness and workability of each of the samples of the present invention were examined. The results are also shown in Table 1.

For comparison, a specimen of a specular reflector whose Ra value or the thickness of the Al coating or the amorphous oxide coating is outside the scope of the present invention (hereinafter referred to as "comparative specimen") No .
1-10 were prepared. Specimen Nos. 11 and 12 of the specular reflector having the crystalline oxide film formed thereon as the second layer and outside the scope of the present invention were prepared. Then, the reflectance, sharpness and workability of each of the comparative specimens were examined. The results are also shown in Table 1.

[0022]

[Table 1]

As is clear from Table 1, the organic coated steel sheet has Ra of 0.05 μm or less, and the Al coating has a thickness of 0.
Specimen No. 1 of the present invention in the range of 01 μm to 0.20 μm
It can be seen that good reflectance and sharpness can be obtained in the range of -17. In addition, it can be seen that, in Sample Nos. 1 to 17 of the present invention, the oxide film is amorphous and the film thickness is in the range of 0.1 μm to 1.2 μm, and good workability is obtained.

On the other hand, the comparative sample No. 1 is Ra
Of more than 0.05 μm, the reflectance and image clarity were poor.

The specimen No. 2 for comparison has an Al film thickness of 0.
Since it was less than 01 μm, the reflectance was poor.

The sample No. 3 for comparison has an Al film thickness of 0.
The image clarity was poor because it exceeded 2 μm.

Comparative specimens Nos. 4, 6 and 10 are unsuitable as a protective film because the amorphous oxide film has a thickness of less than 0.1 μm and thus has poor scratch resistance. The reflectance was also low.

Specimens for comparison Nos. 5, 7, 8 and 9 are
Since the thickness of the amorphous oxide film exceeds 1.2 μm, the workability was poor.

The comparative specimens Nos. 11 and 12 were inferior in workability because the oxide film was crystalline.

[0030]

As described above, according to the present invention, it is possible to obtain a moldable mirror-reflecting plate which is excellent in workability, scratch resistance, reflectivity and sharpness, and is industrially useful. Is brought about.

[Brief description of drawings]

FIG. 1 is a graph showing the influence of the thickness of an aluminum film on the reflectance.

FIG. 2 is a graph showing the influence of the centerline average roughness Ra of the base material on the reflectance after aluminum coating.

FIG. 3 is a graph showing the influence of the centerline average roughness Ra of the base material on the image clarity after aluminum coating.

Claims (1)

[Claims] 1. An organic coated steel sheet having a steel sheet as a base, and a polyester resin-based or fluororesin-based resin coating layer having a center line average roughness Ra of 0.05 μm or less on at least one surface thereof. And 0.01 as a first layer formed on at least one surface of the organic coated steel sheet.
an aluminum film having a thickness in the range of μm to 0.2 μm, and formed on the surface of the aluminum film,
A specular reflector excellent in workability and scratch resistance, which comprises an amorphous oxide film having a film thickness in the range of 0.1 μm to 1.2 μm as a second layer.