JPH11236662A - Production of multilayered film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve wear resistance of a thin film by vapor depositing silicon dioxide as a vapor in an oxygen atmosphere. SOLUTION: It is preferable that a high refractive index layer having >=1.8 refractive index consists of ITO and that the oxygen partial pressure is <=7.0×10<-3> Pa in the vapor deposition process of silicon dioxide. The base body of the multilayered film is a plastic material, the surface where the multilayered film is to be formed is coated with a hard film, and the multilayered film is preferably an antirefllection film. The structure and optical film thickness of each layer in the multilayered film are controlled as follows (wherein λ is the designed wavelength ranging from 450 to 550 nm): from the base body side, the first layer: ZrO2 with 0.05 to 0.15 λ; the second layer: SiO2 with 0.05 to 0.15 λ; the third layer: TiO2 with 0.32 to 0.44 λ; the fourth layer: ITO with 0.05 to 0.15 λ and the fifth layer: SiO2 with 0.15 to 0.35 λ. Thereby, an optical filter having excellent wear resistance can be produced without changing devices while maintaining the latitude for the structure of the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multilayer film suitable for producing an antireflection film or the like which requires abrasion resistance, scratch resistance and adhesion resistance.

[0002]

2. Description of the Related Art In recent years, thin film formation techniques have been advanced, and optical interference filters represented by antireflection have been widely used. Of these optical interference filters, for example, eyeglass lenses and VDT filters require maintenance such as wiping off dirt, and are required to have a film strength such as abrasion resistance, scratch resistance and adhesion resistance. In particular, when the base material is plastic, there is a problem that the heat resistance of the base material is low, so that the heating of the substrate during film formation is limited, and it is difficult to form a high-strength thin film.

Many studies have been made on these film strength problems, and techniques have been improved, but in particular, the abrasion resistance was insufficient.

(1) Generally, silicon dioxide is widely used as an outermost layer of a multilayer film as a low refractive index material having high hardness and excellent scratch resistance. Although the silicon dioxide film can also enhance abrasion resistance as a protective layer, it is greatly affected by its optical thickness, film strength and adhesion of the previous layer.

(2) JP-A-3-134157 proposes a method of forming an oxygen compound of zirconium and boron on the outermost layer, but has a problem that it is difficult to adjust the amount of oxygen introduced during the film formation. .

(3) Japanese Patent Application Laid-Open No. 2-39101 proposes a method of alternately forming a film of titanium dioxide and silicon dioxide, but the material for forming the film is limited.

(4) JP-A-62-178901, JP-A-62-215202, JP-A-62-2601
No. 02 proposes to provide a hard coat layer having abrasion resistance on a substrate and coat zirconium oxide, silicon dioxide, titanium oxide, and silicon dioxide.
The wear resistance of the multilayer film containing TO is insufficient.

(5) Japanese Patent Application Laid-Open No. Hei 6-34801 proposes that all oxide layers be formed by a thin film forming method using plasma, but an expensive apparatus such as an ion gun is required. Become.

[0009]

SUMMARY OF THE INVENTION The present invention does not have the above-mentioned problems and improves the wear resistance of a thin film.

[0010]

According to the present invention, in order to solve the above-mentioned problems, the outermost layer is a layer made of silicon dioxide,
A method for producing a multilayer film having a substrate in which a layer in contact therewith is a high refractive index layer having a refractive index of 1.8 or more, wherein the silicon dioxide is vacuum-deposited in an oxygen atmosphere using silicon dioxide as an evaporant. Manufacturing method of membrane. I suggest.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The outermost layer of silicon dioxide (S
The film formation of iO _x : x = 1.8 to 2.1) is a thin film manufacturing method characterized by using silicon dioxide as an evaporant and performing vapor deposition while introducing oxygen. Preferably 4.0 × 10 ^-3 Pa
The oxygen partial pressure (pressure obtained by subtracting the in-machine vacuum pressure before oxygen introduction from the in-machine vacuum pressure after oxygen introduction) is
7.0 × 10 ⁻³ Pa or less, more than 0, more preferably 4.0 ×
Oxygen is introduced so as to be 10 ^-3 Pa or less and more than 0, and vapor deposition is performed. It is conceivable that the outermost layer of silicon dioxide is deposited in an oxygen atmosphere to make the silicon dioxide film rough, and that the adhesion of the film to the front layer is increased or that it functions as a cushion for the front layer. On the other hand, if the oxygen partial pressure is too high, the silicon dioxide film itself becomes weak, and abrasion resistance cannot be obtained, and the film tends to be thin (a state in which the film is worn down due to abrasion).

The substance called a high refractive index layer having a refractive index of 1.8 or more of the present invention includes ZrO ₂ , Y ₂ O ₃ , Yb ₂ O ₃ , and Sr.
b ₂ O ₃ , Sb ₂ O ₅ , SnO ₂ , In ₂ O ₃ , ITO (In ₂
Mixture of O ₃ and SnO ₂ ), Ta ₂ O ₅ , CeO ₂ , Mg
O, HfO ₂ , Pr ₂ O ₃ , Pr ₆ O ₁₁ , Bi ₂ O ₃ , Cr ₂
O ₃ , Eu ₂ O ₃ , Fe ₂ O ₃ , La ₂ O ₃ , MoO ₃ , Nd ₂
O ₃ , PbO, Sm ₂ O ₃ , Sc ₂ O ₃ , ZnO, CaF ₂ ,
Examples include SmF ₃ , ZnS, Ge, and Si. In particular, when the high refractive index layer is made of ITO, the present invention tends to be effective in improving abrasion resistance.

When the multilayer film is an anti-reflection film,
The film configuration is, for example, in order from the substrate side First layer: ZrO_Two Second layer: SiO_Two Third layer: TiO_Two 4th layer: ITO  Fifth layer: SiO_Two It is preferred that With this configuration, the wavelength is 500-600
The reflectance at nm can be suppressed to 0.5% or less.
In addition, ZrO_TwoBecause there is a layer, the hard
This is preferable because the adhesion to the coat is excellent.

The film thickness may be any thickness as long as visible light can be prevented from being reflected. In the film configuration, an optical film thickness (optical film thickness = refractive index of thin film × physical film thickness) is required. For example, in order from the base material side: First layer: 0.05 to 0.15λ Second layer: 0.05 to 0.15λ Third layer: 0.32 to 0.44λ Fourth layer: 0.05 to 0.15λ Fifth layer: 0.15 to 0.35λ preferable. Here, λ is a design wavelength, and 450 to 550
In the range of nm.

At this time, the surface resistance value can be reduced to 10 ¹⁰ Ω / □ or less by ITO, and it is very preferable to install a ground because static electricity can be cut off.

As the base material of the multilayer film, a glass flat plate, a plastic flat plate, a plastic sheet, a film, or the like is preferably used. Is preferably used. When a plastic substrate is used, the heat-resistant temperature of the substrate is about 120 ° C., so that heating during vapor deposition is limited. The present invention is below the heat resistant temperature of the substrate,
This is effective for improving the wear resistance when so-called low-temperature deposition is performed. The plastic mentioned here may be any known plastic. In particular, in the case of an optical filter used by being attached to the front of a display device, a transparent or translucent filter is preferably used. Also, to improve the contrast of the display screen and make the screen easier to see,
Those having about 40 to 70% or having selective permeation for color are preferably used. Further, a gray-based color that does not impair the color of the display screen is more preferable.

When a plastic substrate is used as the substrate, a hard coat is preferably applied to the substrate on the side on which the multilayer film is to be formed in order to prevent the surface from being damaged and to improve the adhesion resistance of the deposited film. Is preferably used. The hard coat may be applied not only on the surface of the substrate on which the multilayer film is formed but also on the opposite surface, that is, on both the front and back surfaces of the substrate. As the hard coat, a heat-curable organopolysiloxane-based hard coat or an ultraviolet-curable acrylic hard coat is preferably used, and more preferably, a hard coat having a refractive index equivalent to the refractive index of the substrate is used. Interference fringes are difficult to see. For example, an organic silane compound and silicon oxide, aluminum oxide,
A hard coat containing fine particles of at least one inorganic compound selected from titanium oxide, zirconium oxide, cerium oxide, tin oxide, beryllium oxide and titanium oxide is preferably used.

The multilayer film of the present invention comprises an anti-reflection filter,
It is preferably used for optical devices such as spectacle lenses, camera lenses, copiers, facsimiles, and laser beam printers.

[0019]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 As a substrate, a commercially available polymethacrylate plate (manufactured by Mitsubishi Rayon Co., Ltd., trade name "Acrylite" LN-084, gray-colored, about 2 mm thick) was used. As described in Example 1 of JP-A-59-114501, a hard coat paint was prepared by hydrolyzing vinyltriethoxysilane with glacial acetic acid and by coating metatriethoxysilane with glacial acetic acid. Used as a mixture. Sodium acetate as a curing agent was added to the mixed solution to obtain a paint.

The paint is applied to the surface (front and back) of the substrate by about 2 μm.
m and cured by heating at 90 ° C. for 2 hours.

Next, the plastic substrate provided with the hard coat was set in a vapor deposition machine, and set at a set temperature of 80 ° C. and 3 × 10
After evacuation to ⁻³ Pa, oxygen gas was introduced, and oxygen plasma was generated by a high-frequency plasma generator to clean the substrate surface. Subsequently, a film was formed in the following order from the substrate side by an electron beam method.

(1) First layer: a layer containing zirconium oxide as a main component, an optical film thickness (nd) of about 40 nm (about 0.08λ; λ =
(500 nm), degree of vacuum 9 × 10 ⁻³ Pa (introduced oxygen) (2) Second layer: layer mainly composed of silicon dioxide, optical thickness (nd) about 40 nm (about 0.08λ; λ = 500 nm) , vacuum 3 × 10 ^-3 Pa (3) third layer: a layer composed mainly of titanium oxide, an optical film thickness (nd) of about 180 nm (about 0.36λ; λ = 500nm), vacuum 9 × 10 ^-3 Pa (oxygen introduction) (4) Fourth layer: a layer mainly composed of ITO, a refractive index of 1.98, an optical film thickness (nd) of about 30 nm (about 0.06λ; λ = 500 n)
m), degree of vacuum 9 × 10 ⁻³ Pa (introducing oxygen), in a high-frequency oxygen plasma atmosphere (5) Fifth layer: a layer containing silicon dioxide as a main component, optical thickness (nd) about 120 nm (about 0. 24λ; λ = 500 nm), degree of vacuum 4 × 10 ⁻³ Pa (oxygen introduction) The characteristics of the optical filter prepared by the above method and conditions were evaluated.

Table 1 shows the results of the evaluation of surface hardness, adhesion resistance and abrasion resistance. Excellent results were obtained for all tests.

FIG. 1 shows the spectral reflectance characteristics at this time. It had excellent antireflection properties with a reflectance of 0.2% or less at 500 to 600 nm.

Example 2 The fifth layer of silicon dioxide in Example 1 was formed at a degree of vacuum of 1.1.
The deposition was performed in an atmosphere of × 10 ^-2 Pa (introducing oxygen).

The characteristics of the optical filter prepared according to the method and conditions were evaluated.

Table 1 shows the results of the evaluation of surface hardness, adhesion resistance and abrasion resistance. The surface hardness and adhesion are shown in Example 1.
Although the same properties as those obtained were obtained, thinning of the film occurred in the abrasion resistance test.

FIG. 2 shows the spectral reflectance characteristics at this time. Excellent reflectance characteristics were obtained as in Example 1.

COMPARATIVE EXAMPLE 1 The fifth layer of silicon dioxide in Example 1 was formed at a degree of vacuum of 3 × 1.
Vapor deposition was performed at 0 ^-3 Pa (without introducing oxygen).

The characteristics of the optical filter prepared according to the method and conditions were evaluated.

Table 1 shows the results of evaluation of surface hardness, adhesion resistance and abrasion resistance. The surface hardness and the adhesion were similar to those of Examples 1 and 2, but film abrasion occurred in the abrasion resistance test.

FIG. 3 shows the spectral reflectance characteristics at this time. Excellent reflectance characteristics were obtained in the same manner as in Examples 1 and 2.

[0034]

[Table 1]

The test methods and judgments of surface hardness, adhesion resistance and abrasion resistance are as follows.

(1) Surface Hardness Five reciprocal surfaces were rubbed with # 0000 steel wool while applying a load of about 1.0 kg / cm ² to evaluate the degree of scratches. In the judgment, the number of scratches is 10 or less: ○, 11 to 20: Δ, 21 or more: X.

(2) Adhesion Resistance 100 cross hatches are cut in a grid pattern at intervals of about 1 mm with a feather single-edged razor. Thereafter, a cellophane tape (Nichiban) was attached to the grid-like surface, and the tape was peeled in a direction at 90 degrees from the surface. This was repeated three times. Judgment: No peeling: Good, Peeling: Bad.

(3) Abrasion Resistance Tap water was moistened to the polyester knitted fabric, and the surface was rubbed while applying a load of 2.0 kg. The appearance after rubbing 2000 times and 4000 times was evaluated. Similarly, the appearance when rubbing 2,000 times with NaOH (10%) water instead of tap water was evaluated. Judgment is normal: ○, thin film (interference color changes due to rubbing of film):
△, film baldness (film peeled): ×

[0039]

According to the method for producing a thin film of the present invention, it is possible to produce an optical filter having excellent abrasion resistance while maintaining the flexibility of the film constitution without changing the apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a spectral reflectance characteristic of an optical filter according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating spectral reflectance characteristics of an optical filter according to a second embodiment of the present invention.

FIG. 3 is a view showing a spectral reflectance characteristic of an optical filter of Comparative Example 1 of the present invention.

Claims (7)

[Claims] 1. A method for producing a multilayer film having a substrate in which an outermost layer is a layer made of silicon dioxide and a layer in contact with the outermost layer is a high refractive index layer having a refractive index of 1.8 or more. And vacuum-depositing silicon dioxide as an evaporant. 2. The method according to claim 1, wherein the high refractive index layer is made of ITO. 3. The method according to claim 1, wherein the partial pressure of oxygen in the vacuum deposition of silicon dioxide is 7.0 × 10 ⁻³ Pa or less.
Or the method for producing a multilayer film according to item 2. 4. The method for producing a thin film according to claim 1, wherein the base material of said multilayer film is plastic. 5. The method for producing a multilayer film according to claim 1, wherein a hard coat is applied to a surface of the substrate on which a multilayer film is formed. 6. The method according to claim 1, wherein said multilayer film is an antireflection film.
The production method according to any one of the above. 7. The film structure and the optical film thickness of the multilayer film (design wavelength is λ and the range is 450 to 550 nm) in order from the substrate side. First layer: ZrO ₂ , 0.05 to 0.15λ. Second layer: SiO ₂ , 0.05 to 0.15λ Third layer: TiO ₂ , 0.32 to 0.44λ Fourth layer: ITO , 0.05-0.15λ Fifth layer: SiO ₂ , 0.15-0.35λ.