JP2003344604A - Defogging film on optical substrate and method for forming its film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the constitution of a defogging film on various types of optical substrate having a defogging effect and an antireflecting effect. <P>SOLUTION: In an antireflecting film on an optical component using a plastic substrate, the material of at least first layer is constituted of a transparent film synthesized by one type or more selected from the group consisting of TiO2, SiO2, ZrO2 and Cr2O3. Its substantial film thickness is in a range of 10 to 500 Å, the second layer is constituted of the film of MgF2 or SiO2 with a central wavelength λ<SB>0</SB>and optical film thickness of a range of 1/8 to 1/2 λ<SB>0</SB>, and the third layer is constituted of the film of SiO2 or MgF2 and its film thickness of 50 to 300 Å. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antifogging film for an optical substrate and a method for forming the film, and more particularly to a light guide plate used for a mobile phone, a personal digital assistant (PDA), a personal computer, a word processor, a camera, a copying machine, or the like. The present invention relates to an anti-fog film used for optical parts including lenses for optical devices such as facsimiles and laser beam printers, prisms, and various mirrors such as curved mirrors set on the road shoulders and a film forming method thereof.

[0002]

2. Description of the Related Art As prior art of this type before the present invention was made, if it were provisionally proposed, JP-A-11-109105 and JP-A-2
000-329904. These are technologies that have both a low reflection function and an anti-fog function, but the former form hygroscopicity by the sol-gel method (wet type), on which a hydrolyzed product of metal alkoxide is formed, and then moisture absorption on it. Forming a film. This creates an optical article that has both optical characteristics and anti-fog characteristics.

On the other hand, the latter is T1O having a photocatalytic function.
There is a technique for producing an optical component that uses No. 2 and has an outermost surface made of a low refractive index material having hydrophilicity and has both an antireflection function and an antifogging property.

[0004]

[Problems of the prior art] However, regarding the film treatment of the optical component having both the conventional low reflection property and anti-fogging property, it is necessary to carry out the wet treatment such as the sol-gel method for the film treatment of the optical component in the former. Therefore, it is difficult to control the refractive index and the film thickness, sufficient characteristics cannot be obtained, and a problem arises in production stability.

In the latter case, the antifogging effect due to superhydrophilicity is taken into consideration, but T1O2 has an optical constant of n≈.
Since it is as large as 2.3, it is necessary to form a dielectric film having a low refractive index on the upper part, but even if a normal SiO2 film is formed as a top coat, TiO2 is completely covered, so the catalytic effect is killed. However, if a gas is introduced or a film is formed at a low degree of vacuum, an uneven film having cracks and pinholes is formed.

However, in this case, the mechanical properties of the film are obviously deteriorated to form a so-called messy film, the adhesiveness is lowered, and the film is likely to be scratched.
Further, in recent field tests, it has become clear that the photocatalytic function of TiO2 is not sufficient to sufficiently exert the antifogging effect.

In addition, a method of repelling water by providing a water repellent film such as Teflon (registered trademark) is also known, but it is not perfect because small water droplets may adhere. There is also a method of attaching a surface active agent, but there is a problem in that it has a problem in durability and needs to be treated daily.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to solve the above problems and provide an antifogging film structure for various optical substrates having an antifogging effect and an antireflection effect, and the film formation thereof. There is a way to advocate.

Further, the present invention relates to a road reflecting mirror installed at an intersection or a place where visual confirmation is difficult, and particularly exhibits a function of preventing fog on the mirror surface of the mirror body and preventing dew condensation.

That is, the mirror surface anti-fog function of the conventional mirror body is mainly provided with a heat storage device filled with an antifreeze liquid or the like on the back side thereof, but this has the drawback of impairing the heat storage effect of the heat storage device. It was also high, and it was difficult to evenly arrange it on the back surface of the mirror body, and it was difficult to form a gap, and eventually dew condensation was generated as spots on the surface of the reflecting mirror. The purpose is to propose an antifogging film applicable to the above and a film forming method thereof.

[0011]

[Means for Solving the Problem] Thus, one of the features of the present invention.
One is an antireflection film for an optical component using a plastic substrate, and at least the material of the first layer is TiO2, SiO.
2, ZrO2, Cr2O3, or one or two or more kinds of transparent films synthesized, and the actual film thickness is in the range of 10Å to 500Å, and the second layer is MgF2.
Or SiO2, having a central wavelength λ ₀ and an optical film thickness of ⅛λ ₀ to ½λ ₀ , and a third layer made of SiO2 or MgF2 having a film thickness of 50Å
~ 300Å, MgF2 above 0 ℃ ~ 90 ℃
That is, by forming a film on the substrate held by the substrate, it is made porous and hygroscopic.

Another feature of the present invention is to provide a low reflection film structure composed of an inorganic dielectric film on the surface of a substrate made of a thin film material such as glass or plastic with a hygroscopic film such as polyacrylic acid interposed therebetween. It is provided.

Another feature of the present invention is that the hygroscopic film described above is formed by a sol-gel method, and the inorganic dielectric film thereon is formed by a vacuum deposition method, an ion plating method, a sputtering method, or the like. Is Rukoto.

Another feature of the present invention is that the low-reflectance film structure of the above-mentioned inorganic dielectric film is composed of at least a first layer material selected from TiO2, SiO2, ZrO2 and Cr2O3. Of the transparent film, the substantial film thickness of which is in the range of 10Å to 500Å, the second layer is composed of MgF2 or SiO2, and the central wavelength is λ _0, and the optical film thickness is 1 / 8λ ₀ to 1 / 2λ
It is composed of ₀ .

Another feature of the present invention is that the first layer and the second layer shown above are superposed and the first optical substrate main body is further superposed one to several times.

Another feature of the present invention is the above antireflection film, wherein the material of the first layer is TiO2, SiO2,
It is composed of one or two or more kinds of synthesized transparent films selected from ZrO2 and Cr2O3, the substantial film thickness thereof is in the range of 10Å to 500Å, the second layer is composed of MgF2 or SiO2, and the central wavelength is λ _0. And the optical film thickness is 1 / 8λ ₀ to 1 / 2λ ₀ , and the third layer is SiO 2.
2 or MgF2 and its film thickness is 50Å ~ 300
It is in the range of Å.

Another feature of the present invention is that the first layer and the second layer described above are superposed and the first optical substrate main body is superposed by one to several layers.

Another feature of the present invention is that the second layer in the above 6 is constituted by an optical film thickness of SiO 2 or MgF 2/4 λ ₀ .

Another feature of the present invention is that the above-mentioned substrate is a plastic plate, which is a methacrylic resin such as acryl or a cyclic polyolefin resin such as polycarbonate.

Another feature of the present invention is an antireflection film for an optical component using a plastic substrate, wherein the material of at least the first layer is TiO2, SiO2, ZrO2, Cr.
It is composed of one or more kinds of synthetic transparent films selected from 2O3 and has a substantial film thickness of 10Å to 500.
In the range of Å, the second layer is composed of MgF2 or SiO2, and has a central wavelength λ ₀ and an optical film thickness of 1 / 8λ
It is configured by a film formation including a configuration of ₀ to 1 / 2λ ₀ .

Further, the present invention has other excellent objects, features, and effects of the invention, which will be clarified in the following description of the embodiments.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 of the present invention will be described below with reference to the drawings.

The present invention broadens the antireflection property of the antireflection film by forming the multilayer film as described above, and greatly improves the antireflection property for light in a wide wavelength region including the visible light region and the near infrared light region. It was possible to improve.

In this case, the two layers of the above-mentioned first multilayer film are constituted by the optical film thickness of SiO 2 or MgF 21 / 4λ ₀ , which means that the durability of the prevention film can be improved particularly. In this case, the above MgF2 is 50
When a film is formed on a substrate kept at ℃, it is porous and has the effect of maintaining hygroscopicity. Eventually, when it is used as a light base, the hygroscopicity causes so-called The excellent antifogging effect and antireflection effect were obtained without causing "condensation".

[0025]

Embodiment 1 In practicing the present invention, lamination of optical films
The method is different from the conventional configuration and method, and as described above,
Uses a very thin selected optical substrate for the layer and almost 1 for the second layer
/ 4λ ₀It is intended to form a film having an optical film thickness close to.

Furthermore, by providing an extremely thin third layer as the top coat, the usual Scotch tape test (JI
S standard No. With K-5400), it was possible to obtain a low antireflection film having an adhesion strength that does not peel.

More specifically, the first layer is TiO 2.
Adhesion with a plastic substrate is ensured by using an oxide of 2, SiO2, ZrO2, Cr2O3, or one or a mixture of two or more thereof.

More specifically, the known optical film is generally 1
It is said that unless a film thickness of / 4λ ₀ , 1 / 2λ ₀ , 1 / 8λ _0, etc. is set, an optical design cannot be realized and a low reflection film structure cannot be formed.

In this respect, according to the study by the inventors of the present invention, it was found that when the film thickness of the first layer is more than 700Å, the strain of the film becomes large and peeling from the acrylic substrate occurs.

Therefore, it is desirable that the thickness of 50 Å to 300 Å is optimum, and at this thickness, the above first layer, which is considered not to be a "low reflection film" in general optical theory, has a thickness of 50 Å to 300 Å. In that case, a low-reflection film was constructed sufficiently, which made it possible to obtain an anti-reflection film that satisfied both properties of adhesion and low-reflection film, and that was excellent in moisture resistance and abrasion resistance. We were able to propose the film forming method.

Specifically, referring to the drawings, a TiO2 film is formed on the acrylic substrate washed in FIG. 1 by the first layer vacuum deposition method to a thickness of about 150Å, and if necessary, a top layer of about 50Å to 300Å is provided. As a result, as the second layer, MgF
2 was formed into about 1/4 λ ₀ .

Then, on the antireflection film formed in the first embodiment, as shown in FIG. 2, an S of about 150 Å is formed as a protective film for the third layer.
An iO2 film was formed.

As a result, such an antireflection film is shown in [Table 1]. As described above, the reflectance was 0.2% or less at the central wavelength of 550 nm.

Also, in the Scotch tape peeling test by the cross cut, the adhesion between the acrylic substrate and the first layer was sure, and the number of drops was 0.

On the cleaned acrylic substrate, a TiO2 film of about 150 Å was formed in the same manner as in Example 1, and a SiO2 film of about ¼λ ₀ was formed as a second layer. The antireflection film formed as a result is [Table 2] As described above, the reflectance was 0.2% or less at the central wavelength of 550 nm.

In the scotch tape peeling test using the cross cut as described above, the number of people who dropped out was 0, and it was proved that the adhesiveness was reliable.

When the MgF2 film was formed as the second layer, when the film was formed at a low temperature, the second layer became porous,
It turned out to be absorbent.

[0038]

[Embodiment 2] In another embodiment of the present invention, glass or plastic is used as a substrate, and an absorptive film (for example, polyacrylic acid) having a thickness of about 1 to 5 μm is formed thereon.
A hygroscopic film was formed by a method such as sol-gel method. Furthermore, an AR film (low-reflection film) composed of an inorganic oxide on it
Was deposited. As a result, it forms a dense film with the moisture absorption film on the substrate. The refractive index and the film pressure of the structure that allows the AR structure are selected from inorganic oxides.

As described above, microcracks of several μm to several tens of μm are generated in the moisture absorbing film due to the difference in humidity during film formation, and the effect that the lower moisture absorbing film and the air layer on the surface are connected is generated. As a result, the antifogging effect can be exhibited while maintaining the AR effect.

[0040]

Second Embodiment In this first embodiment, a transparent coating film of polyacrylic oxygen is formed to a thickness of about 5 μm by a sol-gel method using glass as a substrate. Next, as shown in FIG. 2, in the vacuum deposition apparatus, the first layer is Tio2, the second layer is MgF2, and the third layer is Si.
o 2 was formed into a film. In this case, the substrate temperature is from room temperature to 200
The temperature is about ° C, which is selected depending on the conditions of the substrate.

FIG. 3 shows the surface SE of the anti-fog film with AR of the present invention.
FIG. 4 is an M (scanning electron micrograph) image magnified 25 times, from which a micro rack of 0.2 to 0.5 m can be observed.

The engineering reflection characteristic at this time has a low reflection characteristic as shown in FIG. 5, and the transmission characteristic is also good as shown in FIG. This is 100% humidity RH
It was found that no clouding occurs even in high humidity, and micro-cracks are generated on the substrate due to a slight difference in humidity during film formation, so that the atmosphere absorbing effect and the AR effect may both occur. Do you get it.

As described above, as the product of the present invention, it is possible to prevent the fogging of glass, glasses and lenses due to a sudden change in humidity.

That is, although the above-mentioned moisture absorbing film can be used alone as an anti-fog film, it will be saturated in 10 to 20 seconds in a 100% RH atmosphere (a state immediately after hot water is put in a cup). With the configuration of the above embodiment, about 1 to 2 minutes is held. Therefore, glasses, cameras, CDs, DVDs
The engineering parts such as can sufficiently prevent fogging even under severe temperature changes and high humidity.

7 and 8 are SEM images of the present invention, which are porous and have cracks in some places as seen in FIG. 8, which results in the absorption effect similar to the above. And the SiO2 on the surface causes a hydrophilic effect.

[0046]

[Third Embodiment] In FIG. 9, (3) is a road reflector main body, which is a mirror body (1) having a convex mirror surface, a back plate connected around the rear surface of the mirror body, and a back plate. It is composed of a mounting bracket provided on the back surface of the plate, and a column (2) connected to the mounting bracket and holding the mirror body.

Then, the optical system substrate obtained in the above embodiment is attached to the surface of the mirror body (1) by an appropriate means. Thus, the road mirror having such a configuration was installed in a cold region in winter, and the occurrence of dew condensation was observed for several days. No dew condensation occurred, and good results were obtained. This is due to the result of forming a low-humidity film by using MgF2 for the second layer of the base, or due to the constitution in which the antifogging film is provided.

[0048]

INDUSTRIAL APPLICABILITY In general, the present invention is applicable to a wide variety of optical system devices including road reflectors, in which the occurrence of so-called dew condensation is prevented, and a large optical system base having an antifogging effect is obtained. is there. Further, even if an acrylic substrate, which has been conventionally incapable of forming a film with adhesive strength, it becomes possible to provide an optical multi-layer film on a plastic substrate such as acrylic, which has excellent optical characteristics. Now it can be applied to prisms, LCD substrates, etc. In particular, weight reduction due to plastic optical parts for mobile phones and laptops,
The cost can be reduced.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional explanatory view for explaining an example of forming an anti-fog film on an optical system substrate according to the present invention.

FIG. 2 is an enlarged cross-sectional explanatory view for explaining a configuration using a moisture absorption film.

FIG. 3 is a surface S of an antifogging film with an AR that is an embodiment of the present invention.
EM, photo substitute drawing

[Figure 4] 2.5 billion enlarged photo substitute drawings

FIG. 5 is a graph of the same engineering reflection characteristics showing low reflection characteristics.

FIG. 6 shows the same transmission characteristics

FIG. 7 is a SEM photograph substitute drawing in which an example of the present invention is porous.

[Fig. 8] Substitute drawing of the same enlarged photograph

FIG. 9 is an example of a case where the present invention is applied to a road reflector.

[Explanation of symbols]

1 Mirror 2 props 3 Reflector body

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 1/10 G02B 1/10 A G02F 1/1335 Z F term (reference) 2H091 FA37X FA50X FB06 LA02 LA12 LA30 MA10 2K009 AA05 AA06 BB02 BB14 BB24 CC03 CC06 CC24 DD02 DD04 DD07 DD08 EE02 4F100 AA06B AA06C AA20A AA20B AA20C AA21A AA22A AA27A AG00D AK01D AK25D AK25E AK45D BA04 BA07 BA08 BA10A BA10D EH462 EH662 GB41 GB90 JA20A JA20B JA20C JD15E JG05A JG05B JG05C JL07 JN01A JN06A JN06B JN06C YY00A YY00B YY00C 4G059 AA11 AC21 EA01 EA04 EA05 EA09 EB03 EB04 FA15 FB06 GA02 GA04 GA16 4K029 AA09 AA11 BA42 BA43 BA46 BA48 BB02 BC00 BC07 BD00 CA01 CA03 CA05 EA01

Claims (10)

[Claims] 1. An antireflection film for an optical component using a plastic substrate, wherein at least the first layer material is TiO 2.
2, SiO2, ZrO2, Cr2O3 is composed of one or two or more kinds of synthesized transparent films, and its substantial film thickness is in the range of 10Å to 500Å, and the second layer is composed of MgF2 or SiO2, Center wavelength λ
₀ and the optical film thickness is 1 / 8λ ₀ to 1 / 2λ ₀ , the third layer is SiO2 or MgF2, and the film thickness is in the range of 50Å to 300Å.
An antifogging film on an optical system substrate and a method for forming the film, wherein the film is made porous on the substrate held at 90 ° C. to have hygroscopicity. 2. A low reflection film structure made of an inorganic dielectric film is provided on the surface of a substrate made of a thin film material such as glass or plastic through a hygroscopic film such as polyacrylic acid. Anti-fogging film on optical system substrate and method for forming the film. 3. The moisture absorption film according to claim 2 is formed by a sol-gel method, and the inorganic dielectric film thereon is formed by a vacuum deposition method, an ion plating method, a sputtering method, or the like. Anti-fogging film on optical system substrate and method for forming the film. 4. The inorganic dielectric film according to claim 2 has a multi-layer structure of low reflection film, and at least the material of the first layer is TiO2, S.
It is composed of one or more kinds of synthesized transparent films selected from iO2, ZrO2 and Cr2O3, and its substantial film thickness is in the range of 10Å to 500Å, and the second layer is composed of MgF2 or SiO2 and has a central wavelength. λ
An antifogging film on an optical system substrate and a film forming method thereof, which is characterized in that the optical film thickness is set to ₀ and the optical film thickness is set to 1 / 8λ ₀ to 1 / 2λ ₀ . 5. An optical system substrate according to claim 3, wherein the first layer and the second layer are superposed and the first optical substrate main body is further superposed one to several times. Anti-fog film and film forming method. 6. The antireflection film according to claim 3, wherein:
The material of the first layer is TiO2, SiO2, ZrO2, Cr2
It is composed of one or more kinds of synthetic transparent films selected from O3 and has a substantial film thickness of 10Å to 500Å
, The second layer is composed of MgF2 or SiO2, and has a center wavelength λ
₀ and an optical film thickness of 1 / 8λ ₀ to 1 / 2λ ₀ , a third layer made of SiO 2 or MgF 2, and the film thickness is in the range of 50Å to 300Å Anti-fogging film and its forming method. 7. An optical system substrate according to claim 3, wherein the first layer and the second layer are superposed on each other and the first optical substrate body is further superposed by one to several layers. Anti-fogging film and its forming method. 8. The second layer according to claim 3, wherein the second layer is Si.
An antifogging film on an optical system substrate and a method for forming the same, which is constituted by an optical film thickness of O 2 or MgF 2/4 λ ₀ . 9. A plastic plate as the substrate according to any one of claims 1 to 7, which is a methacrylic resin such as acryl or a cyclic polyolefin resin such as polycarbonate. Film and its forming method. 10. An antireflection film for an optical component using a plastic substrate, wherein at least the material of the first layer is TiO.
2, SiO2, ZrO2, Cr2O3 is composed of one or two or more kinds of synthesized transparent films, and its substantial film thickness is in the range of 10Å to 500Å, and the second layer is composed of MgF2 or SiO2, An antireflection film for a plastic optical substrate, which is characterized in that it is formed by a film formation having a central wavelength λ ₀ and an optical film thickness of ⅛λ ₀ to ½λ ₀ .