JPH05249306A - Mirror for automobile - Google Patents

Abstract

PURPOSE:To provide the mirror for automobiles having excellent scratching flaw resistance, surface hardness and adhesion strength with a synthetic resin substrate having flexibility. CONSTITUTION:This mirror for automobile is constituted by providing an org. hard coat layer contg. inorg. particulates on the synthetic resin substrate, providing a first layer consisting of SiO2 and having 0.05 to 0.50lambda0 optical film thickness (lambda0 is a wavelength to be the center of design) thereon, then providing a second layer consisting of ZrO2 and Cr and having 40 to 70% reflectivity as a reflection layer thereon, a 3rd layer consisting of the SiO2 and having 0.10 to 0.50lambda0 optical film thickness thereon and further, a fourth layer consisting of a refractive index material of 1.60 to 2.20 refractive index and having 0.00 to 0.50lambda0 optical film thickness when the reflection is desired to be further enhanced. As a result, the synthetic resin mirror for automobiles which has the excellent adhesion strength and scratching flaw resistance of the mirror coats and is more flexible than glass substrate is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an automobile door mirror,
The present invention relates to a reflecting mirror used for side mirrors and room mirrors.

[0002]

2. Description of the Related Art Conventionally, glass substrates have been used for automobile door mirrors, side mirrors and room mirrors. However, it is desirable to apply a mirror coat on a synthetic resin substrate in terms of weight reduction, improvement of safety, and flexibility of the substrate. An example of applying a mirror coat on a synthetic resin substrate is, for example, JP-A-58-58.
For 224302, a film of SiO ₂ or SiO is formed on the surface of the substrate, and a metal film of Al, Cr or the like is formed thereon,
Further disclosed is a method of forming a protective layer thereon.

[0003]

However, when a mirror coat containing a metal film is formed on a synthetic resin substrate,
It is difficult to obtain sufficient hardness and adhesion, and especially when used for door mirrors and side mirrors, it lacks durability.

The object of the present invention is therefore to obtain a sufficient surface hardness,
Scratch resistance, adhesion of mirror coat film, heat resistance, weather resistance,
An object is to provide an automobile mirror having excellent flexibility.

[0005]

The present invention has been made to solve the above problems, that is, the present invention provides (1) an organic hard coat layer containing inorganic fine particles on the surface of a synthetic resin substrate. The optical film made of SiO ₂ having a refractive index of 1.43 to 1.47 is provided on the substrate in order from the base material side, and the optical film thickness is 0.05λ _{0 to} 0.50λ ₀ (λ ₀ is the center of the design. The wavelength of the first layer).

ZrO _{2 obtained} by simultaneously vapor-depositing ZrO ₂ and Cr
And a second layer of Cr having a reflectance of 40 to 70%.

SiO having a refractive index of 1.43 to 1.47
_A third layer having an optical thickness of _{2 of} 0.10λ _{0 to} 0.50λ ₀ .

The optical film thickness of the refractive index substance having a refractive index of 1.60 to 2.20 is 0.00λ _{0 to} 0.50.
The fourth layer of λ ₀ .

A mirror for an automobile, characterized in that it is constructed by using a reflecting mirror obtained by providing. And (2) A mirror for an automobile, wherein the surface of the third layer or the fourth layer, which is the outermost layer of the reflecting mirror, is treated with an organosilicon compound.

The automotive mirror of the present invention will be described in detail below.

As the synthetic resin substrate to be used, a synthetic resin such as diethylene glycol bisallyl carbonate resin, polycarbonate resin, urethane resin or the like can be used, but in order to improve scratch resistance and durability, the synthetic resin substrate is used. An organic hard coat layer is provided. The organic hard coat layer used in the present invention contains inorganic fine particles as its component, and contributes not only to improving the surface hardness and scratch resistance of the substrate but also to greatly improving the adhesion between the substrate and the mirror coat. It is a thing.

As the inorganic fine particles contained as a component of the organic hard coat layer, fine particles of metal oxides or semi-metal oxides can be used, and examples thereof include silicon oxide, aluminum oxide, zinc oxide, titanium oxide, and oxides. Examples thereof include zirconium, tin oxide, cerium oxide, antimony oxide and the like. These may be used alone or in the form of mixed or composite fine particles. Among them, SiO ₂ fine particles are particularly preferable because the quality of the obtained hard coat layer is high.

Since the inorganic fine particles have poor film-forming properties by themselves, they are used together with various compounds capable of forming a film by polymerizing or condensing with them. Examples of the compound include γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4
-Epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane,
Organosilicon compounds such as methyltrimethoxysilane, ethyltrimethoxysilane, dimethyldimethoxysilane or their partial hydrolysates, or their corresponding halides, 1,6-hexanediol diglycidyl ether, glycerol polyglycidyl ether, etc. A polyfunctional epoxy compound, a polyhydric alcohol such as 1,6-hexanediol, a polyvalent carboxylic acid such as azelaic acid or a carboxylic acid anhydride, and other coupling agents may be used alone or in combination.

If necessary, additives such as a curing catalyst, an ultraviolet absorber, a flow control agent and an antioxidant can be added.

The organic hard coat layer is formed by applying and curing a coating solution comprising a mixture of the above-mentioned components or a mixture diluted with a solvent if necessary, by an existing method. That is, the coating method should be selected from flow coating, spray coating, dipping coating, spinner coating, etc. depending on the shape, size, and production amount of the mirror. Further, since the adhesion between the substrate and the organic hard coat layer is improved, the substrate can be previously subjected to chemical etching or dry etching, if necessary.

In the present invention, the synthetic resin substrate obtained as described above is coated with SiO ₂ as the first layer as a mirror coat.
Form the layers. This SiO ₂ film is provided to further improve the adhesion to the organic hard coat layer and the surface hardness. If this film thickness is less than 0.05λ ₀ (where λ ₀ is the wavelength at the center of the design), sufficient surface hardness cannot be obtained and 0.50.
If it is thicker than λ ₀ , the heat resistance will decrease, so 0.05
λ ₀ ~0.50λ ₀ is appropriate. Further, the adhesion can be improved by treating the surface of the organic hard coat layer by RF plasma treatment or the like before providing the first layer. Then a second layer is formed by binary co-evaporation of ZrO ₂ and Cr. When the ratio in each film is due to electron gun heating,
It can be changed by adjusting the amount of emission current. However, in order to form a mirror coat, it is important that the reflectance of the second layer is 40 to 70%, and it is necessary to form the film while measuring the reflectance. Also,
By performing the simultaneous vapor deposition, the film strength is dramatically improved as compared with the Cr single film.

Not only the durability up to the second layer is not yet obtained, but also the reflection characteristics are almost flat. Therefore, in the present invention, the third layer and the fourth layer are provided thereon as protective films.
When a reflection characteristic higher than the reflectance obtained by the second layer is desired, a third layer and a fourth layer are provided to form a reflection increasing film, and the thickness is 40 to 70.
% Is sufficient, only the third layer is used as a protective film. Furthermore, by adjusting the film thickness of these layers, the reflection characteristics can be freely changed, and colored reflected light can be obtained.

For each film formation, ordinary resistance heating,
The film can be formed by various methods such as a vacuum vapor deposition method using electron gun heating and a sputtering method.

In the present invention, the above mirror coat surface is provided with
Reacts an organosilicon compound having a group represented by SiCl, SiOH, SiNH ₂ , SiNHSi, etc., which can react with the surface of the third layer or the fourth layer, and has an alkyl group, a perfluoroalkyl group or the like as a water-repellent group. By letting
Adds water repellency.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 (Preparation, coating and curing of hard coat liquid) 108 parts by weight of γ-glycidoxypropyltrimethoxysilane and isopropanol dispersion were carried out at room temperature in a nitrogen stream in a flask equipped with a stirrer. Colloidal silica ("OSCAL-1432" manufactured by Catalysts & Chemicals Co., Ltd. Si with a solid content concentration of 30%
230 parts by weight (including fine particles of O ₂ ) and 220 parts by weight of isopropanol were sequentially added, and 52 parts by weight of 0.05N hydrochloric acid was added dropwise over 30 minutes while cooling and stirring so that the liquid temperature did not exceed 25 ° C. Subsequently, a flow control agent (“L-7604” manufactured by Nippon Unicar Co., Ltd.) 0.1
By weight, a white translucent liquid was obtained. Then, this liquid was filtered through a 1 μm membrane filter three times to obtain a hard coat liquid.

A plate of diethylene glycol bisallyl carbonate resin (diameter 10c, which was previously immersed in a 4% aqueous sodium hydroxide solution for 10 minutes, washed thoroughly with water and dried in this solution)
m, thickness 2 mm) was dipped and pulled up at a speed of 20 cm per minute to apply the hard coat liquid. This flat plate was heat-cured at 80 ° C. for 1 hour and at 125 ° C. for 1.5 hours to form an organic hard coat layer.

(Formation of Mirror Coat) The substrate manufactured as described above is set on a rotating dome provided in a vacuum chamber, the substrate temperature is 60 ° C., and the degree of vacuum is 8 × 10 ⁻⁶ Torr.
Exhaust until. Then, Ar gas was introduced so that the pressure became 4 × 10 ⁻⁴ Torr, and RF plasma treatment was performed at an output of 400 W for 1 minute. After the treatment, vapor deposition was carried out by heating with an electron gun to form a mirror coat with the film constitution shown below.

The sequential first layer from the substrate side ... SiO ₂ optical film thickness (refractive index 1.46) 0.
25λ _o 2nd layer: A film having a reflectance (at λ _o ) of 50% is formed by binary vapor deposition of ZrO ₂ and Cr. 3rd layer: SiO ₂ (refractive index: 1.46) has an optical film thickness of 0.
Lamination was performed at 40λ _o . After that, when the surface was treated with dimethyldichlorosilane, the contact angle was 30 ° (before treatment), but was increased to 100 ° (after treatment), and the water repellent effect was obtained. λ _o is the design center wavelength of 520
nm. The color of the reflection was blue.

(Test and evaluation results) a) Scratch resistance: A load of 1 kg was applied with # 0000 steel wool and 10 reciprocating surfaces were rubbed, and the degree of scratching was visually evaluated in the following stages.

A: There are no scratches in the area of 1 cm × 3 cm.

B: 1 to 10 scratches are formed within the above range.

C: 10 to 100 scratches are formed within the above range.

D: Countless scratches are left, but a smooth surface remains.

E: No smooth surface remains due to scratches on the surface.

B) Adhesion: A cross-cut tape test was conducted according to JIS D-0202. That is, using a knife, make cuts on the surface of the substrate at intervals of 1 mm, and
100 squares are formed. Next, after strongly pressing the cellophane adhesive tape (“Cellotape” manufactured by Nichiban Co., Ltd.) on it, it was pulled by 90 degrees from the surface and peeled off. The result was.

Adhesion is controlled by constant temperature and humidity (60 ° C. 98% R
It is evaluated every other day after it is put in H), and it is 50 squares.
% Was expressed as the number of days after which it was separated.

The results are shown in Table 1 together with Examples 1 and 2 and Comparative Example.

Example-2 Up to the second layer was formed on the substrate with an organic hard coat obtained in Example 1 in the same manner as in Example 1, and the third layer and the fourth layer were sequentially formed from the substrate side to the third layer. SiO ₂ (refractive index 1.46) has an optical film thickness of 0.
20λ _o 4th layer ... SiO (refractive index 1.72) with an optical film thickness of 0.2
Laminated at 0λ _o . λ _o was set to 500 nm. The color of the reflection was blue. Furthermore, the reflectance is 350 to 800 according to the first embodiment.
The increase was about 10% in nm.

Comparative Example The same procedure as in Example 1 was carried out except that the second layer was formed on the synthetic resin substrate used in Example 1 before the organic hard coat was applied and was made of only Cr having a reflectance of 5%.

[0036]

[Table 1]

[0037]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain an automobile mirror made of a synthetic resin, which is excellent in adhesion and scratch resistance of a mirror coat and which is more flexible than a glass substrate.

The present invention can be used as a reflecting mirror such as an automobile door mirror, a rearview mirror, a side mirror, a curve mirror, or a decorative mirror.

Claims (2)

[Claims] 1. An organic hard coat layer containing inorganic fine particles is provided on the surface of a synthetic resin substrate, and an optical layer made of SiO ₂ having a refractive index of 1.43 to 1.47 is sequentially formed on the organic hard coat layer. The first layer having a film thickness of 0.05λ _{0 to} 0.50λ ₀ (λ ₀ is a wavelength that is the center of design). Consisting ZrO ₂ and Cr for 2-way simultaneous deposition of ZrO ₂ and Cr, the reflectance is 40 to 70
% Second layer. S having a refractive index of 1.43 to 1.47
The optical film thickness of iO ₂ is 0.10λ _{0 to} 0.50λ
Third layer of ₀ . The optical film thickness of the refractive index substance having a refractive index of 1.60 to 2.20 is 0.00λ _{0 to} 0.50.
The fourth layer of λ ₀ . A mirror for an automobile, which is configured by using a reflecting mirror obtained by providing the. 2. A mirror for an automobile, wherein the surface of the third layer or the fourth layer, which is the outermost layer of the reflecting mirror of claim 1, is treated with an organic silicon compound.