JPH0756008A - Optical element and its production - Google Patents

Abstract

PURPOSE:To make it possible to form films by simple production process and to obtain the optical element having excellent appearance, optical characteristics and corrosion resistance and good durability by forming a gold film on a thin film of titanium. CONSTITUTION:This optical element consists of the titanium film which is formed on a base material and has 0.2 to 20nm thickness and the gold film which is formed thereon, consists of gold or an alloy essentially consisting of the gold and has 30 to 200nm thickness. As a result, the optical element having the excellent appearance, reflectivity and durability is obtd. and is used for extremely wide applications. Further, the gold film is formed by a vacuum vapor deposition method on the base material with good adhesion so that the film maintains the sufficient reflectivity without peeling in spite of a change with lapse of time. In addition, the continuous and succeeding vapor deposition of the titanium and the gold is possible and the easy film formation is possible. Particularly, the vapor deposited gold film is formed on the transparent base material consisting of glass or methacrylic resin with the good adhesion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical element having a metal film such as various reflection mirrors and optical disks.

[0002]

2. Description of the Related Art As an optical element having a metal film, there are various copying mirrors, facsimiles, laser beam printers, various reflection mirrors for cameras, optical information recording media such as optical disks, and they are widely used. These have a metal film formed on a base material, and aluminum has been widely used as a material for the metal film.

However, since aluminum is active, problems such as corrosion are likely to occur, and there is a strong potential demand for adopting a durable material for the metal film. On the other hand, gold is extremely stable and can be said to be an ideal material from the viewpoint of corrosion resistance. In addition, the gold thin film has excellent optical properties and a high-grade appearance, and for these reasons, it is an extremely promising material as a reflective film material. For these reasons, some optical elements using gold as a reflection film have begun to be used.

[0004]

However, it is generally difficult for gold to form a film on a substrate in a state of good adhesion, and it peels off due to aging, or the gold agglomerates into particles and has a sufficient reflectance. Or it is difficult to maintain the required metallic luster. On the other hand, a technique of subjecting a base material to a surface treatment, forming a metal oxide vapor deposition layer and a metal vapor deposition layer on the base material, and forming a gold vapor deposition layer thereon (Japanese Patent Publication No. 62-50551). ), A method of increasing the adhesion by selecting a specific material as the base material can be considered, but if this is done, the manufacturing process becomes complicated and the range of application is restricted.

Further, when gold is formed as a reflective film on a transparent base material and the reflection from the base material side is utilized, the undercoat layer is provided without damaging the appearance and reflectance peculiar to gold. It was necessary and extremely difficult at present. In addition, as a transparent substrate, glass having SiO2 as a main component, which has very excellent characteristics, and a resin having a methylmethacrylate as a polymerization component have particularly poor adhesion to a gold thin film and form gold on the surface. Then it was difficult to use.

The present invention has been made on the basis of the above background, and an object of the invention is to form a film of gold on a base material with good adhesion and not peel off due to aging, and the gold is in a particulate form. A film can be formed by a simple manufacturing process without being subjected to surface treatment on the base material, formation of an undercoat layer, selection of a specific base material, etc. A method for producing an optical element capable of forming a gold vapor deposition film with good adhesion, particularly to a transparent substrate such as glass or methacrylic resin, and a high-class appearance,
An optical element having excellent optical characteristics such as reflectance and excellent durability that is extremely stable and corrosion resistant.

[0007]

The above-mentioned problems can be solved by the present invention. That is, the optical element of the present invention has a titanium film having a thickness of 0.2 nm or more and less than 20 nm formed on a base material, and a gold film or an alloy containing gold as a main component, having a thickness of 30 nm or more formed on the titanium film. It is characterized by comprising a gold film having a thickness of less than 200 nm.

In a preferred embodiment of the present invention, the ratio of the film thickness of titanium to gold or an alloy containing gold as a main component is calculated as follows: (film thickness of gold or an alloy containing gold as a main component) / (film thickness of titanium) With ≧ 2, it is possible to use light that is incident from the base material side and reflected.

In a more preferred embodiment of the present invention, glass containing SiO2 as a main component or resin containing methyl methacrylate as a polymerization component can be used as the substrate.

In the method for producing an optical element of the present invention, a base material is loaded into a vacuum container, a predetermined vacuum degree is set, and then titanium is vapor-deposited on the base material to a film thickness of 0.2 nm or more and less than 20 nm. Then, gold or an alloy containing gold as a main component is vapor-deposited on the titanium vapor-deposited film to a film thickness of 30 nm or more and less than 200 nm.

The method for producing the optical element according to the present invention may be performed by sputtering in addition to the above-mentioned vacuum vapor deposition method. In the vacuum deposition method, usually, an evaporation source is arranged in the lower part of a vacuum container, and a resin substrate for an optical disk is arranged so as to face the upper part thereof, and metal particles of the evaporation source are evaporated by electron beam heating or resistance heating. ,
This is a method of depositing this on the surface of the substrate to form a metal film on the surface. Further, a sputtering method, for example, a plasma sputtering method, in a vacuum container, a sputtering source in which a metal target such as aluminum is placed above the magnet, and a substrate facing the sputtering source are respectively arranged.
An inert gas is introduced into the vacuum container, and a magnetic field formed near the surface of the metal target and an applied electric field generate plasma between the resin substrate for the optical disk and the metal target, and the metal target is sputtered by this plasma. Then, metal particles are deposited on the surface of the substrate to form a metal film on the surface.

In the present invention, the titanium film has a thickness of 0.
It is 2 nm or more and less than 20 nm. Here, when titanium is not formed or when the thickness is less than 0.2 nm, 20
If it is more than nm, sufficient adhesion cannot be obtained. further,
The thickness of the gold film is 30 nm or more and less than 200 nm. If the thickness is less than 30 nm, the appearance peculiar to gold cannot be obtained and sufficient reflectance cannot be obtained. On the contrary, when the gold film thickness is 200 nm or more, the adhesiveness is lowered.

Further, in the present invention, the ratio of the film thickness of titanium to gold or an alloy containing gold as a main component is set to (film thickness of gold or an alloy containing gold as a main component) / (film thickness of titanium) ≧ 2 Then, even when looking at the metal film from the base material side, it has an appearance peculiar to gold and has excellent optical characteristics. Therefore, it can be used as an optical element that uses light reflected by incident light from the base material side. On the other hand, it is particularly useful. Here, when the film thickness ratio is less than 2, the appearance peculiar to gold is impaired and the reflectance is lowered. However,
This is not the case when the reflected light from the metal film side is used.

As the base material, an inorganic material such as multi-component glass or quartz glass, or a polymethylmethacrylate resin (PMMA, including homopolymers and copolymers of methyl methacrylate in this specification), deuterium PMMA,
Polycarbonate resin, polystyrene resin, deuterated polystyrene resin, poly-4-methylpentene-1,
It is applicable to transparent resins such as silicone polymers. In a preferred embodiment of the present invention, particularly, the effect of improving the adhesiveness is remarkable because glass containing SiO2 as a main component,
And a resin containing methyl methacrylate as a polymerization component. Since these have extremely excellent optical characteristics, an extremely good optical element can be obtained. Here, as the resin having methyl methacrylate as a polymerization component, a polymethylmethacrylate resin is particularly preferable, and a copolymer containing a polymethylmethacrylate or a methylmethacrylate unit can be used. As the copolymerization component with methyl methacrylate, for example, methyl acrylate,
Examples thereof include acrylic acid esters such as ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, cyclohexyl methacrylate, benzyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and the like, and methacrylic acid esters such as low hygroscopic methacrylate. Furthermore, polymethacrylimide or the like can also be used.

A protective film such as a UV-curable resin is formed on the formed metal film as long as it does not impair the reflected light from the base material side and the reflected light from the metal film side. It doesn't matter.

[0016]

The present invention having the above construction operates as follows. The reason why the adhesion is improved by the present invention is not known in detail, but titanium forms a very dense film even when formed into a thin film, and when formed as a base film, increases the contact area with the base material. Work. Van der Waals force is one of the adhesive force development mechanism,
This is generally stronger when the contact area is larger. From these, it can be explained that the adhesion is improved by forming titanium as the underlayer.

Furthermore, since gold and titanium have a good compatibility,
Even if these are mixed, it is difficult to damage the appearance unique to gold,
It is presumed that good results were obtained. Further, the adhesion of a metal film generally largely depends on the film thickness, which is understood to be due to film stress. In the present invention, it is not clear why the film thickness is in the above-described range, but the film stress may have some effect. In any case, good characteristics as an optical element are exhibited within the above-mentioned film thickness range.

[0018]

EXAMPLES The present invention will be described in more detail below with reference to examples.
In Examples and Comparative Examples, titanium (hereinafter abbreviated as Ti)
Film formation and film thickness measurement of gold and its alloy (hereinafter abbreviated as Au) were performed by the following methods.

[Metal film forming method] -Film forming method: Vacuum evaporation method-Evaporation method: Electron beam heating (Ti), resistance heating (Au) -Vacuum degree during film formation: 1 x 10 ^-5 torr-Film forming speed : 0.05 to 0.20 nm / sec (Ti), 0.8 to 1.
2nm / sec (Au)

[Film Thickness Measuring Method] Measurement by Crystal Vibration Type Film Thickness Sensor Evaluation of the manufactured samples was carried out by the following methods for appearance inspection, reflectance, and adhesive force.

[Appearance] Visual observation is performed from the substrate side to see if the appearance is unique to gold.

[Reflectance] The reflectance was measured by a spectrophotometer by the 5 degree specular reflection method. The result shows the value at a wavelength of 780 nm. Further, as a reference, Au was formed to a thickness of 70 nm on a glass substrate (using a slide glass) under the above conditions (Comparative Example 1 below), and the amount of light reflected from the substrate side was set to 100 and expressed as a relative value.

[Adhesiveness] A cellophane tape was attached to a metal film and slowly peeled off, and whether or not the film remained was used as a measure of the adhesiveness. (Using Nichiban cellophane tape) Adhesive force was measured immediately after film formation and at 60 ° C and 60% RH.
Both after the accelerated deterioration test (48 hours and 96 hours).

Example 1 A slide glass having a plate thickness of 1.2 mm (hereinafter abbreviated as SiO2)
A sample was prepared by forming Ti 1 nm and Au 70 nm on the substrate, and evaluated by the above method. The evaluation results are summarized in Table 1.

Example 2 Polymethylmethacrylate (hereinafter referred to as PMM) having a plate thickness of 1.2 mm
Abbreviated as A: Mitsubishi Rayon Acrylite L) Ti on the substrate
Samples were prepared by forming 1 nm and 70 nm Au, respectively, and evaluated by the above method. Table 1 shows the evaluation results.
Are shown together.

Example 3 A sample was prepared by forming Ti 1 nm and Au 150 nm on a PMMA substrate having the thickness of 1.2 mm (same as in Example 2) and evaluated by the above method. The evaluation results are summarized in Table 1.

Example 4 A sample was prepared by forming Ti 10 nm and Au 70 nm on a PMMA substrate (same as in Example 2) having a plate thickness of 1.2 mm, and evaluated by the above method. The evaluation results are summarized in Table 1.

Example 5 A sample was prepared by forming Ti 3 nm, an alloy of Au and copper (abbreviated as Cu) in a ratio of 9: 1 of 70 nm on a PMMA substrate having the thickness of 1.2 mm (same as in Example 2). It was produced and evaluated by the above method. The evaluation results are summarized in Table 1.

Comparative Example 1 A sample was prepared by forming 70 nm of Au on a SiO 2 substrate (same as in Example 1) having a plate thickness of 1.2 mm and evaluated by the above method. The evaluation results are summarized in Table 1.

Comparative Example 2 A sample was prepared by forming Au 70 nm on a PMMA substrate having the thickness of 1.2 mm (the same as in Example 2) and evaluated by the above method. The evaluation results are summarized in Table 1.

Comparative Example 3 A sample was prepared by forming Ti 30 nm and Au 100 nm on a PMMA substrate having the thickness of 1.2 mm (same as in Example 2) and evaluated by the above method. The evaluation results are summarized in Table 1.

Comparative Example 4 A sample was prepared by forming Ti 5 nm and Au 20 nm on a PMMA substrate (same as in Example 2) having a plate thickness of 1.2 mm, and evaluated by the above method. The evaluation results are summarized in Table 1.

Comparative Example 5 A sample was prepared by forming Ti 5 nm and Au 300 nm on a PMMA substrate (same as in Example 2) having a plate thickness of 1.2 mm, and evaluated by the above method. The evaluation results are summarized in Table 1.

Comparative Example 6 A sample was prepared by forming Ti 20 nm and Au 30 nm on a 1.2 mm thick PMMA substrate (same as in Example 2) and evaluated by the above method. The evaluation results are summarized in Table 1.

[0035]

[Table 1]

(Note) * 1 Appearance (visual inspection from the board side) ○ ・ ・ ・ There is almost no difference from gold only △ …… It can be distinguished from gold only, but it has an appearance unique to gold × …… What is gold? Completely different * 2 Reflectivity (%) Relative value with Comparative Example 1 as 100 (wavelength 780 nm) * 3 Adhesion measurement Cellophane tape peeling test (using Nichiban cellophane tape) ○ …… No peeling △ …… Partial peeling ×… … Peeling off the entire surface

As shown in Table 1, as a result of the evaluation, Example 1
The samples of Nos. 5 to 5 are excellent in appearance, reflectance, adhesion and durability, and extremely good results are obtained. In Comparative Examples 1 to 6, all could not be satisfied.

[0038]

As described above, according to the present invention, it is possible to obtain an optical element excellent in appearance, reflectance and durability, and it is expected to be used in a very wide range of applications. Furthermore, by the method for manufacturing an optical element according to the present invention,
It is possible to form a film with good adhesion of gold on a substrate by a vacuum deposition method, maintain sufficient reflectance without peeling due to aging, and continuously deposit titanium and gold. A film can be easily formed by using the method, and in particular, a gold vapor deposition film can be formed with good adhesion to a transparent base material such as glass or methacrylic resin.

Claims (4)

[Claims] 1. A thickness of 0.2 nm or more formed on a substrate 2
An optical element comprising a titanium film having a thickness of less than 0 nm and a gold film having a thickness of 30 nm or more and less than 200 nm formed on the titanium film and made of gold or an alloy containing gold as a main component. 2. A film thickness ratio between titanium and gold or an alloy containing gold as a main component is set to (film thickness of gold or an alloy containing gold as a main component) / (thickness of titanium) ≧ 2, The optical element according to claim 1, wherein light is incident from the material side and reflected light is used. 3. The optical element according to claim 1, wherein a glass containing SiO2 as a main component or a resin containing methyl methacrylate as a polymerization component is used as the base material. 4. A substrate is loaded into a vacuum vessel, the degree of vacuum is set to a predetermined value, and then titanium is vapor-deposited on the substrate to a film thickness of 0.2 nm or more and less than 20 nm. Then, gold is vapor-deposited on the titanium. A method for producing an optical element, comprising depositing a film having a thickness of 30 nm or more and less than 200 nm on the film.