JPH09277422A - Reflector and reflecting member using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance stability in high temp. and high humidity environment and to keep high reflectivity over a long period of time of a specific time or more by forming a reflector consisting of a transparent polymeric film, an oxide layer of indium and tin and a silver membrane layer and having a reflecting surface on the side of the transparent polymeric film. SOLUTION: A reflector consisting of a transparent polymeric film 10, an oxide layer 20 mainly consisting of indium and tin and a silver membrane layer 30 and having a reflecting surface on the side of the transparent polymeric film 10 is formed. Therefore, a reflecting plate stable even in high temp. and high humidity environment can be obtained. By using this reflecting plate, a reflecting member having wet heat resistance having reflectivity of 90% or more even after exposed to environment of temp. of 80 deg.C and relative humidity of 90% for 500hr can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector using silver stabilized by an oxide layer mainly composed of indium and tin, and more specifically, a silver whose reflectance is hardly reduced even in a high temperature and high humidity environment. The present invention relates to a reflector having excellent environment resistance.

[0002]

2. Description of the Related Art Silver is a metal having the highest reflectance in the visible light region, and is considered to have excellent performance as a reflecting member. Other examples of the reflector material include aluminum, but the practically highest reflectance is 90%. Therefore, in using silver as a reflector 90
% Or more is a standard for practical performance. However, since silver itself is an unstable metal, it is known that when it is left in a high temperature and high humidity atmosphere for a long time, the color changes and the reflectance decreases. For example, a conventional silver reflector is used at 80 ° C and a relative humidity of 90.
When the moisture and heat resistance test is performed under the condition of%, many dot-like white spots occur and the reflectance also decreases. Therefore, various alloys have been attempted to make silver invariable, but the reflectance is lower than the original value of silver, and the value as a reflecting member cannot be fully utilized.

[0003]

Therefore, the stability of a reflector using silver is improved in a high temperature and high humidity environment.
As a result of intensive research on a method of maintaining a high reflectance over a long period of time or more, an amorphous oxide layer mainly composed of indium and tin, that is, amorphous ITO formed by a sputtering method in a high oxygen concentration atmosphere. (Indium
Tin Oxide) thin film layer is used between the transparent polymer film and the silver thin film layer to significantly improve the weather resistance of the reflector using silver, and by laminating the reflector to a metal plate, The present invention has been achieved by finding that a reflector that is easy to handle can be obtained.

That is, the present invention has been made to solve the above-mentioned problems, and (1) At least,
A transparent polymer film (A), an oxide layer (B) mainly composed of indium and tin, and a constitution ABC composed of a silver thin film layer (C) is used as a reflector having a transparent polymer film side as a reflecting surface, and the temperature is 80 ° C. A reflector having a reflectance of 90% or more even after 500 hours in a relative humidity of 90%, (2)
Oxide layer consisting mainly of indium and tin (B)
Is a thin film layer which is amorphous and has a specific resistance of 1 × 10 ⁻² Ω · cm or more formed by a sputtering method in a high oxygen concentration atmosphere, and (3) a transparent polymer film ( A) is polyethylene terephthalate (1)
Alternatively, the adhesive layer (D) and the support (E) are provided on the silver thin film layer (C) of the reflector according to (2) or (4) (1) to (3). In addition, the present invention relates to a reflecting member having the structure ABCDE.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, the present invention is a reflector comprising a transparent polymer film 10, an oxide layer 20 mainly composed of indium and tin, and a silver thin film layer 30. Further, as shown in FIG. 2, the silver thin film layer 30 of the reflector is formed.
It is a reflective member having an adhesive layer 40 and a support 50 provided thereon.

Transparent polymer film (A) in the present invention
Polyethylene terephthalate is used as the material. There is no critical limitation on the thickness of the film,
150 μm is preferably used. The optical property of the polymer film used is that the linear transmittance of light with a wavelength of 550 nm is 8
It is preferably 5% or more and has a haze value of 7% or less. More preferably, the light transmittance for light in the wavelength range of 500 to 700 nm is 85% or more and the haze value is 7% or less. If the light transmittance is lower than this, the total reflectance of the reflective film will not reach the desired value. Further, in order to obtain a reflector having an appropriate diffuse reflectance, the haze value of the transparent polymer film may be adjusted.

Those skilled in the art can improve the adhesion etc. by subjecting the surface of the transparent polymer film to chemical cleaning treatment, surface roughening treatment, glow discharge treatment, corona discharge treatment, etc. before forming the silver thin film. Would be easy to understand.

Indium Tin Oxide (ITO), which is mainly composed of indium and tin, is a kind of transparent conductive film. It is widely used because of its excellent conductivity and transparency, and the fact that it is easy to form an electrode pattern by etching. The specific resistance of the ITO film is usually about 5 × 10 ⁻⁵ to 1 × 10 ⁻³ Ω · cm, and the transmittance is 80 to 90%.

The thickness of the ITO layer is preferably 1 nm to 200 nm, more preferably 10 nm to 100 nm.
If the thickness is less than 1 nm, the adhesion between the transparent polymer film and the silver thin film cannot be sufficiently improved. On the other hand, the film thickness is 200
If the thickness is much thicker than nm, the reflectance as a reflector is lowered by the absorption of the ITO thin film layer, and the adhesion to the transparent polymer film is lowered, which is not preferable. In addition,
It is also preferable to optimize the film thickness by optical calculation.

As a method for forming the ITO layer, a vacuum vapor deposition method,
Any conventionally known physical vapor deposition method such as a sputtering method or an ion plating method can be adopted. Among them, the sputtering method can be preferably used because the oxygen content in the film can be easily controlled. Usually, the ITO film is formed by a reactive sputtering method using argon as a sputtering gas and oxygen as a reactive gas. There is an argon / oxygen partial pressure ratio that minimizes the electrical resistivity of the ITO film,
Generally, when forming an ITO film, the argon / oxygen partial pressure ratio is controlled to a value that minimizes its specific resistance.
A low resistance ITO film is obtained. However, according to the knowledge of the present inventors, an ITO film formed at a conventional argon / oxygen partial pressure ratio that minimizes electrical resistivity contains many structural defects such as oxygen defects, and is chemically and physically Is an unstable and brittle film. In order to have excellent environment resistance, the ITO film needs to be a stable amorphous material with few structural defects.

To obtain such an ITO film, the present inventors set the partial pressure ratio of argon / oxygen, which is a sputtering gas in the sputtering method, to be larger than that of argon / oxygen which minimizes the specific resistance. And specific resistance 1 × 10 ^-2 Ω
It was found that it is preferable to form an ITO film of cm or more. By setting the oxygen partial pressure to a value higher than the minimum specific resistance, a stable amorphous ITO film having few structural defects such as oxygen defects can be obtained.

In the sputtering method, an indium-tin alloy or indium-tin oxide is used as a target, an inert gas such as argon is used as a sputtering gas, oxygen is used as a reactive gas, and the pressure is usually 0.1 to 20 m.
A direct current (DC) or radio frequency (RF) magnetron sputtering method can be used under the conditions of Torr and a substrate temperature of 20 to 150 ° C. during film formation.

The composition of the transparent amorphous ITO thin film influences the electrical characteristics and transparency, but usually the tin content is about 3 to 50% by weight with respect to indium, and the number of oxygen atoms is about 1.3 to 1 atom of indium. It is about 1.8 times.

Transparent amorphous IT formed by the above method
The atomic composition of the O thin film layer is determined by Auger electron spectroscopy (AE
S), inductively coupled plasma method (ICP), Rutherford backscattering method (RBS), etc. Further, these film thicknesses can be measured by observation in the depth direction of Auger electron spectroscopy, cross-section observation by a transmission electron microscope, or the like. Also, I
The crystallinity of the TO film can be determined by an X-ray diffraction method (XRD) or an electron beam diffraction method.

The amorphous ITO film referred to in the present invention means that it is crystalline in the X-ray diffraction pattern by the θ-2θ method, and 2θ = 30 ° to 31 ° of In ₂ O ₃
(222) peak and In ₂ at 2θ = 35 ° to 36 °
It shows substantially no O ₃ (400) peak.

Ti, W, Cu, V, and Z having a film thickness of about 0.1 to 5 nm are provided between the amorphous ITO thin film layer and the silver thin film layer.
The use of a trace amount metal layer such as n is a preferable mode for suppressing the photodegradation of the silver thin film layer.

The silver thin film layer referred to in the present invention is preferably formed by using a vacuum such as a vacuum vapor deposition method or a sputtering method. In the vacuum deposition method, silver is melted by resistance heating or electron beam heating in a crucible,
The vapor pressure is increased to form a thin film on the desired substrate. Examples of the sputtering method include a high-frequency sputtering method, a direct-current sputtering method, a high-frequency magnetron sputtering method, a direct-current magnetron sputtering method, and an electron cyclotron resonance sputtering method. In the sputtering method, a solid silver target is usually used as a sputtering gas by introducing argon gas into a vacuum container at about 1 to 10 mTorr, but krypton or neon may be used. The purity of the target silver is not particularly limited, but is preferably 99.9% or more, and more preferably 99.99% or more.

The thickness of the silver thin film layer is 70 nm to 300 nm.
Is more preferable, and more preferably 100 nm to 200 nm. If the thickness is much smaller than 70 nm, the thickness of silver is not sufficient, so that there is transmitted light and the reflectance is lowered. On the other hand, if the film thickness exceeds 300 nm and is too thick, the reflectance does not increase and the film tends to be saturated, and the adhesion of the silver layer to the polymer film decreases, which is not preferable.

After forming the silver thin film layer, for the purpose of further protecting the silver thin film layer and improving the slipperiness of the film, a metal such as Inconel, chromium, nickel, titanium, aluminum, molybdenum, or tungsten, or a metal of an alloy thereof. It is effective to stack layers of 10 nm to 30 nm.
As those skilled in the art understand.

For measuring the film thickness of the metal layer, there are a stylus roughness meter, a repetitive reflection interferometer, a microbalance, a crystal oscillator method and the like. In the crystal oscillator method, the film thickness is measured during film formation. Since it is possible, it is suitable for obtaining a desired film thickness. Also,
There is also a method in which the conditions for film formation are determined in advance, a film is formed on a sample substrate, the relationship between the film formation time and the film thickness is examined, and the film is controlled by the film formation time.

The adhesive (including a pressure-sensitive adhesive) used in the present invention is an adhesive which is adhered with the aid of heat or a catalyst, and specifically, polyester adhesive, acrylic adhesive, melamine adhesive. A general adhesive such as an adhesive, a silicone adhesive, a phenol adhesive, an epoxy adhesive, or a cyanoacrylate adhesive can be used. For example, a cyanoacrylate-based adhesive has excellent quick-release properties and strength, and thus can be used for efficient production of a reflector. These adhesives are roughly classified into a thermosetting type, a hot-melt type, and a two-component mixing type depending on the bonding method, and a thermosetting type or a hot-melt type which can be continuously produced is preferably used. The thickness of the adhesive layer is not particularly limited, but is usually 0.5 μm to 50 μm, preferably 1 μm to 20 μm.
It is a degree.

In the present invention, the polymer film (A) on which the amorphous ITO layer and the silver thin film layer are formed and the support (E)
Adhesion with is carried out by the steps of coating the silver thin film layer with an adhesive, drying, and laminating with a support (plate-shaped molding) with a roller. The adhesive coating method includes the type of adhesive used, viscosity, coating amount, coating speed,
The bar coat method is selected in consideration of the surface condition to be obtained,
The roll coating method, the Mayer bar coating method, the reverse coating method, the gravure coating method, the die coating method and the like can be mentioned, but the gravure coating method and the reverse coating method are widely used.

In the gravure coating method, a gravure roll, a part of which is immersed in an adhesive, is rotated, and a film fed by a backup roll is brought into contact with the gravure roll to which the adhesive is attached to coat the film. The coating amount can be adjusted by controlling the number of rotations of the roll and the viscosity of the adhesive. The reverse coating method is also a method similar to the gravure coating method, but the amount of adhesive adhered to the coating roll is adjusted by the metering roll installed in contact with it. The drying temperature and the laminating temperature of the coated adhesive vary depending on the kind of the adhesive, but when the general adhesive listed above is used, it is usually around 100 ° C. If the temperature is too high, the polyethylene terephthalate film is deteriorated, which is not preferable.

The adhesive strength between the transparent polymer film (A) having the silver thin film layer (C) formed by the above adhesive and the support (E) is 100 g / cm or more as measured by 180 degree peel strength. Is desirable. If the adhesion strength is not reached, when the sheet is processed into a practical shape as a reflecting member, the transparent polymer film on which the silver thin film layer is formed is likely to float above the metal plate as the support.

The support includes aluminum, aluminum alloy,
Examples of the metal plate include stainless steel, steel-zinc alloy, and steel. Each of these metals has advantages and can be used as follows. Aluminum is lightweight and excellent in workability, and has high thermal conductivity and can effectively dissipate heat to the atmosphere. Therefore, it can be suitably used for a copying machine in which a reflector plate is heated by light emission from a lamp. Aluminum alloys are lightweight and have high mechanical strength, and thus can be suitably used. Stainless steel has high mechanical strength, and
Since it has excellent corrosion resistance, it can be suitably used. Steel-zinc alloy, that is, brass or brass, is suitable for use because it has high mechanical strength and is easy to solder. It goes without saying that a plastic plate can be used. The thickness of the support is preferably 0.1 to 1 mm. Thus, the reflectance of the produced reflector is typically 93% or more for light having a wavelength of 550 nm, and more specifically, 93% or more in the range of 500 nm to 750 nm.

[0026]

The present invention will be described below with reference to examples. The reflectance, resistivity, and crystallinity in the examples and comparative examples were evaluated by the following methods. 1) Reflectance The reflectance was measured by installing a 150φ integrating sphere on a Hitachi automatic recording spectrophotometer (U-3400). The reflectance from the side not on the metal surface, that is, from the polymer film side, that is, the specular reflectance + diffuse reflectance was measured. 2) Specific Resistance The specific resistance r [Ω · cm] was calculated by the product of the sheet resistance R [Ω / □] and the film thickness t [cm], r = R × t. The sheet resistance value was determined by the 4-terminal method, and the film thickness was determined by a stylus roughness meter. 3) Crystallinity Crystallinity is 2θ by taking an X-ray pattern by the θ-2θ method.
= 30 ° to 31 ° In ₂ O ₃ (222) peak and 2θ = 35 ° to 36 ° In ₂ O ₃ (400) peak.

Example 1 A polyethylene terephthalate (PET) film (A4100 manufactured by Toyobo Co., Ltd .: thickness 25 μm) was formed by a DC magnetron sputtering method using indium oxide and tin oxide (composition ratio In ₂ O ₃ : SnO ₂ = 8).
The target is a sintered body of 0:20 WT%) and the purity is 99.
Purity 99.5% with 5% argon as sputter gas
Of oxygen was used as a reactive gas to form an ITO film having a thickness of 70 nm. At this time, the oxygen partial pressure was set to 0.1 mTorr (oxygen concentration 5%) with respect to the total pressure of 2 mTorr to create a high oxygen concentration atmosphere. The film was taken out of the sputtering device and the specific resistance of the ITO thin film was calculated to be 4.5 x 1
It was 0 ^-2 Ω · cm. The crystallinity was examined by X-ray diffractometry and it was found to be amorphous. Repeat the above operation I
TO was formed on a polyethylene terephthalate film, and this time without removing it from the vacuum device, the purity was 99.
Using 9% silver as a target, argon having a purity of 99.5% as a sputtering gas, and further depositing silver to a thickness of 150 nm to obtain a reflector.

Example 2 A polyester hot melt adhesive (Soken Chemical SK Dyne 5273) was applied to the silver-formed surface of the reflector obtained in Example 1 to a thickness of 5 μm. Next, this film was applied to a brass plate (J
It was adhered to IS2 type) by thermal lamination to obtain a reflection member.

(Comparative Example 1) A polyethylene terephthalate (PET) film (A4100 manufactured by Toyobo Co., Ltd .: thickness of 25 μm) was obtained by a DC magnetron sputtering method with a purity of 9
Using 9.9% silver as a target and argon having a purity of 99.5% as a sputtering gas, silver was laminated to a thickness of 150 nm to obtain a reflector.

Comparative Example 2 On the silver-formed surface of the reflector obtained in Comparative Example 1, a polyester hot melt adhesive (Soken Kagaku SK Dyne 5273) was applied in a thickness of 5 μm. Next, this film was applied to a brass plate (J
It was adhered to IS2 type) by thermal lamination to obtain a reflection member. The samples prepared in the above Examples and Comparative Examples are
Installed in a constant temperature and humidity container at 80 ° C and 90% relative humidity,
After 500 hours, a visual inspection was performed on the state of occurrence of white spots on the reflecting surface, and the reflectance was measured. The results are shown in (Table 1). The reflectance shown is a value at a wavelength of 550 nm.

[0031]

[Table 1] * Number of white spots of φ1 mm or more generated in a 10 cm square sample

[0032]

EFFECT OF THE INVENTION Amorphous film having a specific resistance of 1 × 10 ⁻² Ω · cm or more formed by sputtering in a high oxygen concentration atmosphere between a transparent polymer film (A) and a silver thin film layer (C). By using the oxide layer (B) mainly composed of indium and tin, it was possible to obtain a stable reflection plate even in a high temperature and high humidity environment. Further, by using the reflection plate, it is possible to provide a reflection member having moist heat resistance, which maintains a reflectance of 90% or more even after being exposed to an environment of a temperature of 80 ° C. and a relative humidity of 90% for 500 hours.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a reflector of the present invention.

FIG. 2 is a sectional view showing an example of a reflecting member according to the present invention.

[Explanation of symbols]

 10 Transparent Polymer Film 20 Oxide Layer Mainly Made of Indium and Tin 30 Silver Thin Film Layer 40 Adhesive Layer 50 Support

Front page continuation (72) Inventor Satoshi Kawamoto 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Shin Fukuda 1190, Kasama-cho, Sakae-ku, Yokohama, Kanagawa Mitsui Toatsu Chem. (72) Inventor Nobuhiro Fukuda 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemicals, Inc.

Claims (4)

[Claims] 1. Reflection having a transparent polymer film (A), an oxide layer (B) mainly composed of indium and tin, and a transparent polymer film side of a constitution ABC composed of a silver thin film layer (C) as a reflective surface. Body, temperature 80
A reflector having a reflectance of 90% or more even after 500 hours in an atmosphere of 90 ° C. and 90% relative humidity. 2. The oxide layer (B) mainly composed of indium and tin is an amorphous thin film layer having a specific resistance of 1 × 10 ⁻² Ω · cm or more formed by a sputtering method in a high oxygen concentration atmosphere. The reflector according to claim 1. 3. The reflector according to claim 1, wherein the transparent polymer film (A) is polyethylene terephthalate. 4. A reflective member having a structure ABCDE, in which an adhesive layer (D) and a support (E) are provided on the silver thin film layer (C) of the reflector according to claim 1.