JPH08240701A - Optical thin film - Google Patents

Abstract

PURPOSE: To form a reflection preventing film or the like having excellent adhesibility on a substrate of a synthetic resin containing polycarbonate. CONSTITUTION: A titanium oxide film such as TiO film has excellent adhesibility to the synthetic resin containing polycarbonate and further has a property hardly permeating an organic solvent or moisture. Then, the reflection preventing film 10 using the TiO film 11 as a 1st layer is formed on the surface of the substrate B1 of the synthetic resin containing polycarbonate. The reflection preventing film excellent in adhesibility and environmental resistance is can be obtained even when the substrate B1 is not heated while forming respective thin films 11-16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical thin film of a synthetic resin optical component used in an optical system of an optical device such as a camera, a copying machine, a facsimile and a laser beam printer.

[0002]

2. Description of the Related Art In optical devices such as cameras, copying machines, facsimiles, and laser beam printers, by using as many synthetic resin optical parts as possible in these optical systems, the cost of parts can be reduced, the weight can be reduced, and the productivity can be improved. Efforts are being made to promote the improvement of

When the optical component is made of glass and an optical thin film such as an antireflection film is provided on the surface of the optical component, the glass substrate (optical component) is heated to 200 ° C. or higher and a single layer or a plurality of layers are formed by a vacuum deposition method. Generally, a thin film of a layer is formed. By this method, the adhesion to the substrate is good and the optical characteristics are excellent, and the adhesion and the optical characteristics are deteriorated even in an environment of high temperature and high humidity. It is possible to obtain a high-quality optical thin film that is free from the risk of

However, since the softening temperature of the optical parts made of synthetic resin is lower than that of glass parts (about 110 ° C. or less), it is possible to heat the above-mentioned high temperature during the thin film formation. For this reason, the adhesion of the optical thin film to the substrate (optical component made of synthetic resin) is insufficient, and the surface hardness of the optical thin film is low, causing many problems such as being easily scratched, resulting in poor practicality. .

As a method for improving the adhesion when the film is formed at a low temperature, an antireflection film having a SiOx (silicon oxide) layer having good adhesion to a synthetic resin and high hardness as a first layer in contact with a substrate (See Japanese Patent Publication No. 53-000306) or non-polar synthetic resin (fluorine-based plastic or olefin-based plastic) on the surface of which a metal oxide containing an oxide such as zirconium, nickel or titanium as a main component is laminated ( JP-A-3-260052) has been developed.

[0006]

However, according to the above-mentioned conventional technique, the one having the SiOx layer as the first layer in contact with the substrate is effective for the substrate made of polymethylmethacrylate (acrylic). In the case where the substrate is polycarbonate (PC) or a mixture of polycarbonate and polystyrene, etc., in a high temperature and high humidity environment (for example, at a temperature of 7
When the temperature is 0 ° C or higher and the humidity is 85% or higher), the adhesiveness is significantly deteriorated. Therefore, it is unsuitable for synthetic resin optical parts containing polycarbonate.

A laminate of metal oxides containing an oxide such as zirconium or nickel as a main component was developed for an optical component made of a nonpolar synthetic resin. It is difficult to apply to a synthetic resin optical component containing a polycarbonate having a carbonyl group in the inside and therefore showing a high polarity.

The present invention has been made in view of the problems of the above-mentioned conventional techniques, and has high adhesion to a synthetic resin substrate containing polycarbonate and sufficient environmental resistance. It is intended to provide an optical thin film.

[0009]

In order to achieve the above object, the optical thin film of the present invention has a multilayer film consisting of a plurality of thin films laminated on a substrate containing polycarbonate, and Then, the first layer in contact with the substrate is a titanium oxide film.

The final layer farthest from the surface of the substrate is preferably a silicon oxide film.

[0011]

[Function] A titanium oxide film such as a TiO film or a Ti ₂ O ₃ film has excellent adhesiveness especially to a synthetic resin containing polycarbonate, and has a property that an organic solvent or water hardly penetrates. . Therefore, by using a titanium oxide film as the first layer of an optical thin film such as an antireflection film or a half mirror having a synthetic resin containing polycarbonate as a substrate, sufficient adhesion to the substrate and high temperature and high humidity can be achieved. To realize a high-quality optical thin film in which the adhesiveness is not significantly deteriorated even in an environment. The optical thin film can obtain sufficient adhesion and environment resistance even if the substrate is formed without heating.

Further, if the final layer of the optical thin film is a silicon oxide film which is hard and has a property of hardly permeating an organic solvent or water, it has an advantage that it is hard to be damaged by mechanical stimulation such as friction. The environment resistance is further improved.

[0013]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an antireflection film 10 which is an optical thin film according to the first embodiment. It consists of a six-layer thin film laminated by a vacuum deposition method on the surface of a substrate B ₁ injection-molded with polycarbonate in the shape of a lens. Having a multilayer film of
A first layer which is formed on the _first surface is a TiO film 11 is a titanium oxide film having a thickness of 5 nm, the second layer thickness 166n
m SiO film 12, the third layer is a 12 nm thick TiO film 1
The third and fourth layers have a SiO ₂ film 14 with a thickness of 21 nm, the fifth layer has a TiO film 15 with a thickness of 106 nm, and the sixth layer has a thickness of 84 nm.
Is a SiO ₂ film 16 which is a silicon oxide film.

The thin films 11 to 16 of the respective layers are formed by introducing oxygen gas into the vacuum chamber to obtain pressures of 1.33e to 2P.
A predetermined evaporation source is heated and evaporated by an electron beam heating method in a vacuum atmosphere of a, and the substrate B ₁ is heated without heating. The thickness of each layer is controlled by reflectance photometry with monochromatic light. Adopted the law.

FIG. 2 is a graph showing the results of measuring the spectral reflectance of the antireflection film 10. As can be seen from this graph, the antireflection film 10 has a reflectance of 1% or less in the wavelength range of 400 to 700 nm and has extremely excellent optical characteristics.

Further, the adhesiveness with the adhesive tape was tested after leaving it in a high temperature and high humidity durability tank having a temperature of 70 ° C. and a humidity of 85% for 100 hours. As a result, the adhesiveness with the substrate B ₁ was extremely good. It has been found that both the optical characteristics and the environmental resistance are sufficient as an antireflection film for optical parts such as camera lenses.

In this embodiment, since the first layer formed on the surface of the substrate is a TiO film having excellent adhesion to the polycarbonate substrate, it is sufficient to form the substrate without heating. Adhesion can be obtained. In addition, since the titanium oxide film such as the TiO film has a property of hardly permeating an organic solvent or water, it is possible to avoid the deterioration of the adhesiveness under the environment of high temperature and high humidity.

Furthermore, since the final layer (sixth layer) of the antireflection film is a SiO ₂ film, it is possible to prevent moisture and organic solvent from entering the inside of the antireflection film, and as described above, the environment resistance is improved. It is estimated that it will greatly improve.

In addition, since the surface layer is a SiO ₂ film having high hardness, it has an advantage that it is not easily scratched by external mechanical stimuli such as friction.

For comparison, the antireflection film 20 shown in FIG. 3 was manufactured and its spectral reflectance was measured. The measurement result is shown in FIG.

The antireflection film 20 of FIG. 3 is formed on the same polycarbonate substrate B _{2 as} in the first embodiment by the same vacuum deposition method as in the first embodiment, and has a film thickness of 170 nm.
Of the first SiO 2 film 21 and Ti of 15 nm thickness
A second layer made of an O film 22, a third layer made of a SiO ₂ film 23 having a film thickness of 30 nm, and a TiO film 24 having a film thickness of 120 nm.
And a fifth layer made of a SiO ₂ film 25 having a film thickness of 87 nm.

As shown in FIG. 4, the antireflection film 20 has a reflectance of 1% or less in the wavelength range of 400 to 700 nm, but is used in a high temperature and high humidity durability tank having a temperature of 70 ° C. and a humidity of 85%.
When the adhesiveness of the adhesive tape was tested after standing for 00 hours, the antireflection film was peeled off from the substrate B ₂ , and deterioration of the adhesiveness was confirmed. Therefore, it is not preferable to use it as an antireflection film for optical parts such as a camera lens.

The reason why the adhesion is deteriorated by the environment resistance test is presumed to be that the first layer contacting the substrate is the SiO film and the adhesion to the substrate is lower than that of the TiO film.

FIG. 5 shows an antireflection film 30 which is an optical thin film according to the second embodiment. It is formed by vacuum deposition on the surface of a substrate B ₃ which is injection molded of polycarbonate in a lens shape. The first layer consists of a thin film of layers
Using Ti as a target, Ar was introduced into the vacuum chamber up to 0.7 Pa, and then O ₂ was introduced into the vacuum chamber at a flow rate of 5 sccm to form a titanium oxide film 31 with a thickness of 16 nm formed by the high frequency magnetron sputtering method. Yes, the second layer is
A SiO ₂ film 32 having a film thickness of 29 nm was formed by high-frequency magnetron sputtering by introducing Ar to a pressure of 0.7 Pa in a vacuum chamber with SiO ₂ as a target, and the third layer was a titanium oxide film of the first layer. The titanium oxide film 33 has a film thickness of 58 nm and is formed in the same manner as 31, and the fourth layer is the SiO ₂ film 3 formed in the same manner as the _second SiO ₂ film 32.
4, the fifth layer is a titanium oxide film 35 having a film thickness of 45 nm formed in the same manner as the titanium oxide film 31 of the first layer, and the sixth layer is the SiO ₂ film 32 of the second layer. The SiO ₂ film 36 having a film thickness of 91 nm is formed in the same manner as in. The film thicknesses of the thin films 31 to 36 of the respective layers were controlled by calculating the sputtering time backward from the sputtering rate. FIG. 6 shows the result of measuring the spectral reflectance of the antireflection film 30 thus obtained.

The antireflection film 30 according to this embodiment has a reflectance of 1% or less over the entire visible region, and particularly, the wavelength 41
In the range of 0 to 680 nm, it is an antireflection film of extremely high performance with a reflectance of 0.5% or less. Also, the temperature is 70 ° C and the humidity is 8
After being left in a 5% high temperature and high humidity durable layer for 100 hours, an adhesion test was performed using an adhesive tape, and the adhesion to the substrate was good, and the optical system of cameras and videos, and the anti-reflection of eyeglass lenses, etc. It has been found to be suitable as a membrane.

FIG. 7 shows a half mirror 40, which is an optical thin film according to the third embodiment, which comprises a substrate B ₄ injection-molded in a flat plate form of a mixture of polycarbonate and polystyrene, and a surface thereof formed by a vacuum deposition method. It consists of 5 layers of thin film laminated, and the first layer has a pressure of 1.33e ~ 2 in the vacuum chamber.
It is a Ti ₂ O ₃ film 41 which is a titanium oxide film formed to a film thickness of 136 nm while controlling the pressure to be Pa, and the second layer contains oxygen gas so that the pressure in the vacuum chamber becomes 1.33e to 2Pa. introducing a SiO ₂ film 42 which is formed into a film having a thickness of 78 nm, Ti ₂ third layer which is formed into a film having a thickness of 51nm in the same way as Ti ₂ O ₃ film 41 of the first layer O ₃ film 43, and the fourth layer is formed by the same method as the second layer SiO ₂ film 42.
The SiO ₂ film 44 having a film thickness of 0 nm is
The layer is 89 nm in the same manner as the Ti ₂ O ₃ film 41 of the first layer.
Is a Ti ₂ O ₃ film 45 having a film thickness of.

The thin films 41 to 45 of each layer are formed by heating a predetermined evaporation source by an electron beam heating method to form a substrate B.
No. ₄ was performed without heating, and the reflectance photometry with monochromatic light was used to control the film thickness. The result of measuring the spectral reflectance of the antireflection film 40 thus obtained is shown in FIG.

The half mirror 40 according to the present embodiment has an average reflectance in the entire visible region of about 50%, is left in a high temperature and high humidity durability tank having a temperature of 70 ° C. and a humidity of 85% for 100 hours, and then adheres with an adhesive tape. As a result, it was found that the half mirror had good adhesion to the substrate and excellent durability.

A half mirror 50 shown in FIG. 9 for comparison.
Was manufactured and its spectral reflectance was measured. The half mirror 50 shown in FIG. 9 is composed of a substrate B _{5 obtained} by injection-molding a mixture of polycarbonate and polystyrene into a square plate shape, and a thin film of 6 layers formed on the surface thereof by a vacuum deposition method. The first layer is a vacuum chamber. Of the SiO film 51 having a film thickness of 5 nm by introducing oxygen gas so that the pressure becomes 1.33e to 2Pa.
The second layer is a Ti ₂ O ₃ film 52 formed to a film thickness of 136 nm by controlling the pressure in the vacuum chamber to 1.33e to 2Pa, and the third layer has a pressure in the vacuum chamber of 1.33e to 2Pa. SiO ₂ film 5 formed by introducing oxygen gas into the film to a thickness of 75 nm
The third and fourth layers are a Ti ₂ O ₃ film 54 having a film thickness of 51 nm formed by the same method as the Ti ₂ O ₃ film 52 of the second layer, and the fifth layer is a SiO ₂ film 53 of the third layer. A SiO ₂ film 55 having a film thickness of 80 nm was formed by the same method, and the sixth layer was the second layer of Ti.
_The Ti ₂ O ₃ film 56 is formed to have a film thickness of 89 nm by the same method as the ₂ O ₃ film 52, and the first layer SiO film 51 is formed by heating the evaporation source by a resistance heating method and leaving Thin film 52-5
All of the film formations of No. 6 were performed by heating the evaporation source by the electron beam heating method.

FIG. 10 shows the result of measuring the spectral reflectance of the half mirror 50 thus obtained. Although the half mirror 50 has an average reflectance of 50% in the entire visible range, the half mirror 50 was left in a high temperature and high humidity durability tank having a temperature of 70 ° C. and a humidity of 85% for 100 hours, and then an adhesive tape adhesiveness test was conducted. The film peeled from the substrate. It is considered that this is because the first layer in contact with the base body 50 is the SiO film 51 having lower adhesion than titanium oxide.

FIG. 11 shows a half mirror 60 which is an optical thin film according to the fourth embodiment. This is a substrate B ₆ in which a polycarbonate is injection-molded into a flat plate shape, and a film is formed on the surface thereof by a vacuum deposition method. The first layer consists of 6 layers of thin film, and the first layer controls the vacuum chamber to a pressure of 1.33e-2Pa.
The TiO film 61 having a film thickness of 23 nm and the second layer were formed by introducing oxygen gas so that the pressure in the vacuum chamber was 1.33 e to 2 Pa, and the SiOx film 6 having a film thickness of 81 nm.
The second and third layers are formed by the same method as the first layer TiO film 61.
TiO film 63 formed to a thickness of 8 nm, the fourth layer is a SiOx film 64 formed to a thickness of 86 nm by the same method as the SiOx film 62 of the second layer, and the fifth layer is a first layer. TiO film 61
TiO film 6 formed to a film thickness of 59 nm by the same method as
The fifth and sixth layers are formed by the same method as the second layer SiOx film 62.
SiOx, which is a silicon oxide film formed to a thickness of 7 nm
The film 66.

The thin films 61 to 66 of each layer were formed by heating a predetermined evaporation source by a resistance heating method, and the film thickness of each layer was controlled by a reflectance photometry method using monochromatic light.
The result of measuring the spectral reflectance of the half mirror 60 thus obtained is shown in FIG. The half mirror 60 according to the present embodiment has an average reflectance of 45% over the entire visible range. In addition, a high temperature and high humidity durability tank with a temperature of 70 ° C and a humidity of 85%
When the adhesive tape was tested for adhesion after being left to stand for 00 hours, the adhesion to the substrate was good. Furthermore, a mixed solution of methanol and ether was dipped in a lens cleaning paper and a load of 500 g was applied to rub the surface 50 times, but no change such as scratches or film peeling was observed on the surface of the half mirror, and mechanical stimulus It was found that the durability was also sufficient.

For comparison, a half mirror similar to the half mirror of this embodiment is formed on an acrylic substrate and the temperature is 70 ° C.
After leaving it in a high temperature and high humidity durability tank having a humidity of 85% for 100 hours, an adhesive tape adhesiveness test was conducted, and it was observed that the film was peeled from the substrate. It is presumed that titanium oxide does not have good adhesion to the acrylic substrate.

[0035]

Since the present invention is configured as described above, it has the following effects.

It is possible to realize an optical thin film such as an antireflection film or a half mirror, which has high adhesion to a synthetic resin substrate containing polycarbonate, has sufficient environmental resistance, and is inexpensive.

By using such a synthetic resin optical component, weight saving and cost reduction of various optical devices can be greatly promoted.

[Brief description of drawings]

FIG. 1 is a diagram showing a film structure of an antireflection film according to a first example.

FIG. 2 is a graph showing the results of measuring the spectral reflectance of the antireflection film of FIG.

FIG. 3 is a diagram showing a film configuration of a comparative example of the first embodiment.

FIG. 4 is a graph showing the results of measuring the spectral reflectance of the antireflection film of FIG.

FIG. 5 is a diagram showing a film configuration of an antireflection film according to a second example.

6 is a graph showing the results of measuring the spectral reflectance of the antireflection film of FIG.

FIG. 7 is a diagram showing a film structure of a half mirror according to a third embodiment.

8 is a graph showing the results of measuring the spectral reflectance of the half mirror of FIG.

FIG. 9 is a diagram showing a film configuration of a comparative example of the third embodiment.

10 is a graph showing the results of measuring the spectral reflectance of the half mirror of FIG.

FIG. 11 is a diagram showing a film configuration of a half mirror according to a fourth example.

12 is a graph showing the results of measuring the spectral reflectance of the half mirror of FIG.

[Explanation of symbols]

11, 13, 15, 22, 24, 61, 63, 65
TiO film 12, 21, 51 SiO film 14, 16, 23, 25, 32, 34, 36, 42, 4
4, 53, 55 SiO ₂ film 31, 33, 35 titanium oxide film 41, 43, 45, 52, 54, 56 Ti ₂ O ₃ film 62, 64, 66 SiOx film

Claims (4)

[Claims] 1. A multilayer film comprising a plurality of thin films laminated on a substrate containing polycarbonate, wherein the first layer of the plurality of thin films in contact with the substrate is a titanium oxide film. An optical thin film characterized by. 2. The optical thin film according to claim 1, wherein the final layer farthest from the surface of the substrate is a silicon oxide film. 3. The optical thin film according to claim 1, wherein the multilayer film is an antireflection film. 4. The optical thin film according to claim 1, wherein the multilayer film is a half mirror.