JP6954754B2 - Lens with water-repellent anti-reflective coating and its manufacturing method - Google Patents

Description

The present invention relates to a lens with a water-repellent antireflection film and a method for manufacturing the same.

A technique for improving water repellency by coating the surface of a lens with water repellency is known. For example, the following patent document discloses an invention in which a water-repellent film of an organic compound is formed on the lens surface.

Japanese Unexamined Patent Publication No. 2006-284855 Japanese Unexamined Patent Publication No. 2014-6349 International Publication No. 2008/05/3712

However, in the configuration in which the water-repellent film of the organic compound is formed on the surface of the antireflection film of the inorganic compound formed on the lens surface, the water-repellent film is easily peeled off, and the durability of the water-repellent film is inferior. there were. The above-mentioned patent documents do not disclose a preferable film structure for improving the adhesion and durability of the water-repellent film formed on the surface of the inorganic compound.

The present invention has been made based on the above awareness of the problems, and an object of the present invention is to provide a lens with a water-repellent antireflection film having improved adhesion and durability of the water-repellent film, and a method for manufacturing the same.

The lens with a water-repellent antireflection film of the present invention has a water-repellent antireflection film in which an antireflection film, an undercoat film and a water-repellent film are laminated in this order on the surface of a glass lens, and the antireflection film is SiO _2. , MgF ₂ , ZrO ₂ , Al ₂ O ₃ , TIO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and low consisting of _{a single layer selected from Nb 2} O ₅ or a mixed layer containing two or more materials. The structure is such that the refractive index layer and the high refractive index layer are alternately laminated, the uppermost layer is formed of SiO ₂ of the low refractive index layer, and the base film is SiO ₂ , ZrO ₂ , Al ₂ O. _{It is formed of a single layer selected from 3} , TiO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O ₅ or a mixed layer containing two or more kinds, and has a density of 80% or more and 100% or less. thickness is at 1nm or 200nm or less, the water-repellent film, said the surface of the underlying film is formed of an organic compound containing a perfluoropolyether group, Ri thickness der than 50nm or less 5 nm, the underlayer The density of the antireflection film is equal to or higher than the density of the uppermost layer of the antireflection film .

Further, in the present invention, the base film is preferably formed of _{SiO 2.}

Further, in the present invention, the surface of the glass lens is preferably aspherical.

Further, in the method for manufacturing a lens with a water-repellent antireflection film of the present invention, on the surface of the glass lens, in a first film forming chamber in which the substrate heating temperature is 200 ° C. or higher and 350 ° C. or lower. A single layer selected from SiO ₂ , MgF ₂ , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O ₅ or a mixed layer containing two or more materials. The glass lens on which the antireflection film is formed is installed in the first step of forming one or more layers to form an antireflection film and in a second film forming chamber separate from the first film forming chamber. At this time, the substrate heating temperature is lower than the substrate heating temperature in the first step, and is kept under reduced pressure in the second film forming chamber set to 250 ° C. or lower, and the underlying film and the substrate are heated. It has a second step of continuously forming a water-repellent film, and in the second step _{, SiO 2} , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ti ₃ O ₅ , Ta on the surface of the antireflection film. _{2 O 5,} and to form the base film with a mixed layer comprising a single layer or two or more materials selected from Nb ₂ O _5, this time, the base film, thinner than the antireflection film a step of, on the surface of the underlying film is perforated and forming the water-repellent film with an organic compound having a perfluoropolyether group, and wherein the.

Further, in the present invention, it is preferable to form the undercoat film by an ion beam assist method or a sputtering method.

Further, in the present invention, it is preferable that the base film is formed with a film thickness of 1 nm or more and 200 nm or less, and the water repellent film is formed with a film thickness of 5 nm or more and 50 nm or less.

Further, in the present invention, it is preferable that the _{base film is formed of SiO 2.}

According to the present invention, it is possible to provide a lens with a water-repellent antireflection film having excellent adhesion and durability of the water-repellent film, and a method for manufacturing the same.

It is a schematic diagram of the lens with the water-repellent antireflection film of this embodiment. It is a partially enlarged schematic diagram of the lens with the water-repellent antireflection film of the first embodiment. It is a partially enlarged schematic diagram of the lens with the water-repellent antireflection film of the second embodiment. 6 is a graph showing the relationship between the number of reciprocating repetitions of Example 9 (with a base film (SiO ₂ )) and Comparative Example 1 (without a base film) and the contact angle. 6 is a graph showing the relationship between the number of reciprocating repetitions of Example 9 (base film SiO ₂ ) and Comparative Example 2 (base film MgF _{2) and the contact angle.} It is a graph which shows the relationship between the number of reciprocating repetitions of Reference Example 1 (base film (SiO ₂ ): density 100%) and Comparative Example 3 (base film (SiO _{2): density 65%), and a contact angle.}

Hereinafter, embodiments for carrying out the present invention (hereinafter, simply referred to as “the present embodiment”) will be described in detail.

The present inventors have diligently studied an undercoat film for a water-repellent film of an organic compound, and have improved the adhesion and durability of the water-repellent film. That is, the lens with the water-repellent antireflection film of the present embodiment includes the following characteristic portions (1) to (3).

(1) A water-repellent antireflection film in which at least a base film and a water-repellent film are laminated in this order is provided on the surface of the glass lens.
(2) The base film is _{a single layer selected from SiO 2} , ZrO ₂ , Al ₂ O ₃ , TIO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O ₅ or a mixture containing two or more kinds. Formed in layers. The density of the base film is 70% or more and 100% or less. The film thickness of the base film is 1 nm or more and 200 nm or less.
(3) The water-repellent film is formed of an organic compound containing a perfluoropolyether group. The film thickness of the water-repellent film is 5 nm or more and 50 nm or less.

FIG. 1 is a schematic view of the lens with a water-repellent antireflection film of the present embodiment. The lens 1 with a water-repellent antireflection film shown in FIG. 1 includes a glass lens 2 as a substrate and a water-repellent antireflection film 3 formed on the surface of the glass lens 2 on the light incident side. ..

The glass lens 2 is not particularly limited, but is, for example, a glass lens for a surveillance camera or an in-vehicle camera. Further, the surface of the glass lens 2 on which the water-repellent antireflection film 3 is formed is, for example, an aspherical surface. The glass lens 2 in FIG. 1 is, for example, a meniscus lens having a negative power, but may be a meniscus lens having a positive power, a biconvex lens, a biconcave lens, or the like.

As shown in (1) above, the water-repellent antireflection film 3 includes at least an undercoat film and a water-repellent film. Further, the undercoat film has the characteristic portion of the above (2), and the water-repellent film has the characteristic portion of the above (3), respectively. Optically, the entire water-repellent antireflection film 3 exerts an antireflection effect.

Hereinafter, the water-repellent antireflection film 3 will be described in more detail.

<First Embodiment>
As shown in FIG. 2, the water-repellent antireflection film 3 of the first embodiment is laminated in the order of the antireflection film 4, the base film 5, and the water-repellent film 6 from the surface of the glass lens 2.

The antireflection film 4 is selected from SiO ₂ , MgF ₂ , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O _{5 on the surface of the glass lens 2.} It is composed of a single layer or a mixed layer containing two or more kinds of materials having one or more layers. All of these inorganic compounds constituting the antireflection film 4 are transparent oxides.

The antireflection film 4 is adjusted so that the reflectance is lower than that of the glass lens 2 alone. Specifically, the refractive index and the film thickness of each layer are determined so that the entire lens provided with the antireflection film 4, the base film 5, and the water repellent film 6 has a desired spectral reflectance. Therefore, the antireflection film 4 may be a single layer as long as it is a film having a refractive index lower than that of the glass lens 2. Further, in the case of a multilayer film, a structure in which low refractive index layers and high refractive index layers are alternately laminated can be used. At this time, the high refractive index layer may be higher than the refractive index of the glass lens 2. The antireflection film 4 is composed of, for example, 1 to 15 layers, preferably 1 to 10 layers. The number of layers, the material, and the film thickness of the antireflection film 4 can be variously selected based on the wavelength region in which the reflectance is suppressed.

Although the film thickness of the antireflection film 4 is not limited, the film thickness (total thickness) of the antireflection film 4 is about 50 nm to 500 nm.

The base film 5 formed on the surface of the antireflection film 4 shown in FIG. 2 is located on the outermost layer of the antireflection film 4. In the first embodiment shown in FIG. 2, the base film 5, the antireflection film 4, and the water repellent film 6 are combined and adjusted so as to satisfy a desired reflectance characteristic as a whole.

Further, the base film 5 formed on the surface of the antireflection film 4 functions as a base for the water repellent film 6. The base film 5 is _{a single layer selected from SiO 2} , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O ₅ or a mixed layer containing two or more of them. It is formed. In comparison with the inorganic compounds constituting the antireflection film 4, MgF ₂ that can be used as the antireflection film 4 cannot be used in the base film 5. As will be shown in an experiment described later, _{it is known that when MgF 2} is used as the base film 5, the degree of adhesion between the base film 5 and the water-repellent film 6 is lowered, and excellent durability cannot be obtained. In the present embodiment, the base film 5 is preferably formed of _{SiO 2 among the above-mentioned materials.}

The base film 5 has a density of 70% or more and 100% or less. When the "dense density" is 100%, it means that the base film 5 has no void portion. If there are voids, the density will decrease accordingly. The density of the base film 5 is preferably 80% or more and 100% or less.

The film thickness of the base film 5 is 1 nm or more and 200 nm or less from the viewpoint of the water-repellent property and the antireflection effect of the water-repellent film 6, and is preferably formed thinner than the antireflection film 4. The film thickness of the base film 5 is preferably 1 nm or more and 100 m or less, more preferably 1 nm or more and 50 nm or less, and further preferably 1 nm or more and 20 nm or less.

The water-repellent film 6 formed on the surface of the base film 5 is an organic compound containing a perfluoropolyether group. The organic compound containing a perfluoropolyether group has excellent water repellency and oil repellency. The organic compound containing a perfluoropolyether group is not particularly limited, and for example, a perfluoropolyether-modified silane can be presented.

The film thickness of the water-repellent film 6 is formed to be 5 nm or more and 50 nm or less from the viewpoint of the water-repellent property of the water-repellent film 6. As described above, the water-repellent film 6 is a thin film and is coated on the surface of the base film 5. The film thickness of the water repellent film 6 is preferably 5 nm or more and 20 m or less.

<Second Embodiment>
As shown in FIG. 3, the water-repellent antireflection film 3 of the second embodiment is laminated on the surface of the glass lens 2 in the order of the base film 5 and the water-repellent film 6. The second embodiment is a configuration in which the antireflection film 4 shown in the first embodiment is removed.

For the film configurations of the base film 5 and the water-repellent film 6, refer to the above description of the first embodiment.

In the second embodiment shown in FIG. 3, the base film 5 is preferably formed of a material having a refractive index lower than that of the glass lens 2. The base film 5 is preferably formed of _{SiO 2.}

In FIG. 2, an arbitrary pretreatment coating (not shown) is provided between the surface of the glass lens 2 and the antireflection film 4, or between the surface of the glass lens 2 and the base film 5 in FIG. May be applied.

As described above, in the first embodiment and the second embodiment, the material, film thickness, and density of the base film 5 are defined, and the material and film thickness of the water-repellent film 6 are defined. As described above, the undercoat film 5 has a high density and has a wide bonding surface with the water-repellent film 6. That is, the base film 5 in the present embodiment has a large number of binding molecules per unit area and has high binding properties. Therefore, a dehydration condensation reaction appropriately occurs between the water-repellent film 6 and the hydroxyl group of the base film 5, and a strong covalent bond is formed between the base film 5 and the water-repellent film 6. Further, the water-repellent film 6 is formed of a thin film, and the degree of bonding of the entire water-repellent film 6 can be increased.

As described above, in the present embodiment, the adhesion of the water-repellent film 6 can be enhanced, and as shown in the rubbing test described later, the peeling of the water-repellent film 6 can be suppressed, and high durability can be obtained. ..

Further, as shown in the first embodiment, the material, the density, and the film thickness are defined without directly forming the water-repellent film 6 of the organic compound on the surface of the antireflection film 4 of the inorganic compound. A water-repellent film 6 is formed through the ground film 5. As a result, the adhesion and durability of the water-repellent film 6 can be improved, and an excellent antireflection effect can be obtained.

<Manufacturing method of lens with water-repellent anti-reflection film>
First, a method for manufacturing a lens with a water-repellent antireflection film according to the first embodiment shown in FIG. 2 will be described. In the first embodiment shown in FIG. 2, the manufacturing process can be divided into a first process and a second process.

(First step)
In the first step, the antireflection film 4 is formed on the surface of the glass lens 2. At this time, the substrate heating temperature in the film forming chamber (hereinafter referred to as the first film forming chamber) is set to 200 ° C. or higher and 350 ° C. or lower and maintained under reduced pressure. The substrate heating temperature refers to the heating temperature for the glass lens 2. In the present embodiment, since the substrate is the glass lens 2, the heating temperature can be raised to 200 ° C. or higher. Further, in the present embodiment, it is preferable to set the substrate heating temperature to 250 ° C. or higher and 350 ° C. or lower.

_{In the first step, SiO 2} , MgF ₂ , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ti _{3 while} being held under reduced pressure in the first film forming chamber in which the substrate heating temperature is set as described above. One _{or more layers of a single layer selected from O 5} , Ta ₂ O ₅ , and Nb ₂ O ₅ or a mixed layer containing two or more kinds of materials are formed to form an antireflection film 4.

After forming the antireflection film 4, the lens with the antireflection film is taken out from the first film forming chamber.

(Second step)
Next, a lens with an antireflection film is installed in a film forming chamber (hereinafter referred to as a second film forming chamber) different from the first step. In the second step, the substrate heating temperature in the second film forming chamber is 250 ° C. or lower, and the pressure is reduced. At this time, it is preferable to set the substrate heating temperature in the second step to a temperature lower than the substrate heating temperature in the first step. In this embodiment, it is preferable to set the substrate heating temperature to 100 ° C. or lower. Further, the substrate heating temperature can be set to room temperature (25 ° C.). A more preferable range of the substrate heating temperature is in the range of room temperature to 100 ° C.

In the second step, on the surface of the antireflection film 4, a single layer selected from _{SiO 2} , ZrO ₂ , Al ₂ O ₃ , TIO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O _{5 or} The base film 5 is formed with a mixed layer containing two or more kinds of materials. At this time, it is preferable to form the base film 5 with a film thickness of 1 nm or more and 200 nm or less. The film thickness of the base film 5 is more preferably 1 nm or more and 100 m or less, still more preferably 1 nm or more and 50 nm or less, and even more preferably 1 nm or more and 20 nm or less.

Further, it is preferable that the undercoat film 5 is formed by an ion beam assist method (Ion-beam Assisted Deposition: IAD) or a sputtering method. In the ion beam assist method, gas ions are irradiated to the surface of a glass lens, which is a substrate, with an ion gun during vacuum deposition. By the ion beam assist method, the adhesion of the antireflection film 4 to the surface can be improved, and the density of the base film 5 is 70% or more and 100% or less (preferably 80% or more and 100% or less). It can be adjusted easily and appropriately. The ion beam assist method can also be applied when the antireflection film 4 is vapor-deposited.

Subsequently, in the second step, the perfluoropoly is maintained under reduced pressure in the same second film forming chamber (the substrate heating temperature is 250 ° C. or lower, preferably 100 ° C. or lower), which is the same as the film formation of the undercoat film 5. A water-repellent film 6 made of an organic compound having an ether group is formed. At this time, the water-repellent film 6 can be vapor-deposited by an electron beam method (EB) or a resistance heating vapor deposition method.

Further, the water-repellent film 6 is preferably formed with a film thickness of 5 nm or more and 50 nm or less, and more preferably formed with a film thickness of 5 nm or more and 20 nm or less.

After the second step is completed, the lens 1 with the water-repellent antireflection film is taken out from the second film forming chamber. Then, a dehydration condensation reaction is appropriately caused between the hydroxyl group of the base film 5 and the water-repellent film 6, and the mixture is stored in the air for a predetermined time until a strong covalent bond is formed.

In the method for manufacturing the lens 1 with the water-repellent antireflection film of the second embodiment shown in FIG. 3, only the above-mentioned second step needs to be performed.

In the method for manufacturing the lens 1 with the water-repellent antireflection film in the present embodiment, the undercoat film is held under reduced pressure in the same film forming chamber (second film forming chamber) in which the substrate heating temperature is set to 250 ° C. or lower. 5 and the water-repellent film 6 are formed. As a result, the cleanliness of the surface of the base film 5 can be improved, and when the water-repellent film 6 is formed, the surface of the base film 5 can be kept in a state of having unbonded elements.

Here, the unbonded element reacts with the gas in the atmosphere at the moment when it is released to the atmosphere and loses its binding property. That is, the antireflection film 4 formed in the first film forming chamber in the first step is exposed to the atmosphere when it is transferred to another second film forming chamber in the second step. Therefore, the unbonded elements on the surface of the antireflection film 4 are bonded to the gas component in the atmosphere, and the bondability is lost. On the other hand, in the present embodiment, after the base film 5 is formed, the water repellent film 6 is formed while being held under reduced pressure in the same film forming chamber as it is. As described above, in the present embodiment, the undercoat film 5 and the water-repellent film 6 are continuously formed while being held under reduced pressure. Therefore, when the water-repellent film 6 is formed, the surface of the base film 5 is in a state of having unbonded elements and having a high bondability.

Further, in the present embodiment, the undercoat film 5 has a high density of 70% or more and 100% or less, and in combination with the above-mentioned highly bondable state having an unbonded element, the undercoat film 5 and the water-repellent film 6 A strong covalent bond can be formed.

Further, in the configuration shown in FIG. 2 in which the antireflection film 4, the base film 5, and the water repellent film 6 are formed, the first step and the second step are divided into separate film forming chambers as described above. It is necessary to make a film. This is because it is necessary to change the substrate heating temperature between the first step and the second step. In the first step, it is necessary that the substrate heating temperature is high in order to increase the strength of the antireflection film 4. In the present embodiment, since the glass lens 2 is used for the substrate, it has durability against the substrate heating temperature, and the substrate heating temperature can be increased to effectively increase the strength of the antireflection film 4. On the other hand, in the second step, in order to obtain the good water-repellent properties of the water-repellent film 6, it is necessary to lower the substrate heating temperature below the substrate heating temperature in the first step, or to keep the temperature at room temperature without heating. be. At this time, if the same first film forming chamber as in the first step is used, it takes a very long time to lower the substrate heating temperature, and the manufacturing efficiency is lowered. Therefore, in the present embodiment, good water repellency is obtained by changing the film forming chamber at the time of transition from the first step to the second step and lowering the substrate heating temperature of the second film forming chamber in the second step. It becomes possible to obtain the characteristics. As described above, it is possible to manufacture a lens 1 with a water-repellent antireflection film having excellent antireflection effect and water-repellent effect as well as excellent adhesion and durability of the water-repellent film 6.

Hereinafter, this embodiment will be described in more detail with reference to Examples and Comparative Examples. In the experiment, Examples 1 to 9 and Comparative Example 1 to Comparative Example 3 shown below were produced.

[Example 1]
In Example 1, the materials shown in Table 1 below are used, and the first step and the second step are performed at the substrate heating temperature shown in Table 1 to obtain the density, film thickness, and refractive index shown in Table 1. A lens with a water-repellent antireflection film was obtained. The refractive index nd of the glass lens (refractive index at the d line (588 nm)) was 1.85135. The refractive index nd of the glass lens is the same in Examples 2 to 9 and Comparative Examples 1 to 3. Here, the density was determined from the ratio of the known refractive index of the material to the refractive index of the film containing the formed voids (refractive index of the film in vacuum). The refractive index of the vacuum film was determined by measuring the reflectance during film formation using an optical film thickness meter in a vacuum-held film forming chamber and converting it into a refractive index. In the experiment, a vapor deposition machine (SGC-22SA) manufactured by Showa Vacuum Co., Ltd. was used. The density may also be measured by high resolution Rutherford backscattering analysis (HR-RBS: High Resolution Backscattering Spectrometry). The refractive index of each layer was obtained by converting from the reflectance of the film (corresponding to the refractive index of the film in the atmosphere). Specifically, the reflectance of the substrate taken out into the atmosphere was measured with a microscope-type spectrophotometer (USPM-RU3) manufactured by Olympus Corporation, and converted into a refractive index. The refractive index is at a wavelength of 550 nm. Further, the film thickness can be measured using, for example, a cross-sectional TEM photograph. The above-mentioned measurements of the density, the refractive index, and the film thickness are the same in Examples 2 to 9 and Comparative Examples 1 to 3.

In Example 1, the substrate heating temperature in the first step was set to 250 ° C., and antireflection films were alternately laminated up to 7 layers of _{SiO 2} and Ta ₂ O _5. Further, in the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{As the base film, a film made of SiO 2} having a density of 100% and a film thickness of 20 nm was formed. Further, a film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film.

[Example 2]
In Example 2, the materials shown in Table 2 below are used, and the first step and the second step are performed at the substrate heating temperature shown in Table 2 to have the density, film thickness, and refractive index shown in Table 2. A lens with a water-repellent antireflection film was obtained.

In Example 2, the substrate heating temperature in the first step was set to 200 ° C., and the antireflection film _{was alternately laminated with Al 2} O ₃ and _{a composite material of ZrO 2} and TiO ₂ up to 6 layers, and the 7th layer was formed. Was set to SiO ₂ . Further, in the second step, the substrate heating temperature was set to 100 ° C. _{As the base film, a film made of SiO 2} having a density of 80% and a film thickness of 10 nm was formed. Further, a film made of fluoroalkyl ether having a film thickness of 10 nm was formed on the water-repellent film.

[Example 3]
In Example 3, the materials shown in Table 3 below are used, and the first step and the second step are performed at the substrate heating temperature shown in Table 3 to obtain the density, film thickness, and refractive index shown in Table 3. A lens with a water-repellent antireflection film was obtained.

In Example 3, the substrate heating temperature in the first step was set to 350 ° C., and the antireflection film _{was laminated with SiO 2} and TiO ₂ alternately up to 9 layers. Further, in the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{As the base film, a film made of SiO 2} having a density of 100% and a film thickness of 100 nm was formed. Further, a film made of fluoroalkyl ether having a film thickness of 20 nm was formed on the water-repellent film.

[Example 5]
In Example 5, the materials shown in Table 5 below are used, and the first step and the second step are performed at the substrate heating temperature shown in Table 5, and the density, film thickness, and refractive index shown in Table 5 are obtained. A lens with a water-repellent antireflection film was obtained.

In Example 5, the substrate heating temperature in the first step was set to 250 ° C., and the antireflection film was formed of one layer of _{SiO 2.} Further, in the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{As the base film, a film made of SiO 2} having a density of 100% and a film thickness of 20 nm was formed. Further, a film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film.

[ Reference Example 1 ]
In Reference Example 1 , the materials shown in Table 6 below are used, and the second step is performed at the substrate heating temperature shown in Table 6, and a water-repellent antireflection film having the density, film thickness, and refractive index shown in Table 6 is applied. I got a lens with a lens.

In Reference Example 1 , the first step was not performed. In the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{As the base film, a film made of SiO 2} having a density of 100% and a film thickness of 20 nm was formed. Further, a film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film.

[ Reference example 2 ]
In Reference Example 2 , the materials shown in Table 7 below are used, and the first step and the second step are performed at the substrate heating temperature shown in Table 7, and the denseness, film thickness, and refractive index shown in Table 7 are obtained. A lens with a water-repellent antireflection film was obtained.

In Reference Example 2 , the substrate heating temperature in the first step was set to 250 ° C., and the antireflection film _{was alternately laminated with SiO 2} and Nb ₂ O 5 up to 7 layers. Further, in the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{A film made of ZrO 2} having a density of 80% and a film thickness of 5 nm was formed on the undercoat film. Further, a film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film.

[Example 8]
In Example 8, the materials shown in Table 8 below are used, and the first step and the second step are performed at the substrate heating temperature shown in Table 8 to have the density, film thickness, and refractive index shown in Table 8. A lens with a water-repellent antireflection film was obtained.

In Example 8, the substrate heating temperature in the first step was set to 250 ° C., and antireflection films were alternately laminated up to 7 layers of _{SiO 2} and Ti ₃ O _5. Further, in the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{As the base film, a film made of Al 2} O ₃ having a density of 100% and a film thickness of 10 nm was formed. Further, a film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film.

[Example 9]
In Example 9, the materials shown in Table 9 below were used, and the second step was performed at the substrate heating temperature shown in Table 9, and a water-repellent antireflection film having the density, film thickness, and refractive index shown in Table 9 was applied. I got a lens with a lens.

In Example 9, the substrate heating temperature in the first step was set to 220 ° C., and antireflection films were alternately laminated up to 7 layers of _{SiO 2} and Ta ₂ O _5. In the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{As the base film, a film made of SiO 2} having a density of 80% and a film thickness of 20 nm was formed. Further, a film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film.

[Comparative Example 1]
In Comparative Example 1, the materials shown in Table 10 below are used, and the first step and the second step are performed at the substrate heating temperature shown in Table 10 to have the density, film thickness, and refractive index shown in Table 10. A lens with a water-repellent antireflection film was obtained.

In Comparative Example 1, the substrate heating temperature in the first step was set to 220 ° C., and the antireflection film _{was alternately laminated with SiO 2} and Ta ₂ O ₅ up to 7 layers. Further, in the second step, the substrate heating temperature was set to 25 ° C. (no heating). A film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film. No undercoat was formed.

[Comparative Example 2]
In Comparative Example 2, the materials shown in Table 11 below were used, and the second step was performed at the substrate heating temperature shown in Table 11, and a water-repellent antireflection film having the density, film thickness, and refractive index shown in Table 11 was applied. I got a lens with a lens.

In Comparative Example 2, the substrate heating temperature in the first step was set to 220 ° C., and the antireflection film _{was alternately laminated with SiO 2} and Ta ₂ O ₅ up to 7 layers. In the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{A film made of MgF 2} having a density of 80% and a film thickness of 20 nm was formed on the undercoat film. Further, a film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film.

[Comparative Example 3]
In Comparative Example 3, the materials shown in Table 12 below were used, and the second step was performed at the substrate heating temperature shown in Table 12, and a water-repellent antireflection film having the density, film thickness, and refractive index shown in Table 12 was applied. I got a lens with a stick.

In Comparative Example 3, the substrate heating temperature in the first step was set to 220 ° C., and the antireflection film _{was alternately laminated with SiO 2} and Ta ₂ O ₅ up to 7 layers. In the second step, the substrate heating temperature was set to 25 ° C. (no heating). _{As the base film, a film made of SiO 2} having a density of 65% and a film thickness of 20 nm was formed. Further, a film made of fluoroalkyl ether having a film thickness of 15 nm was formed on the water-repellent film.

[Rubbing tester]
The following friction tester was used for the rubbing test.
Manufacturer: Syncron Co., Ltd. Product name: Triple friction tester

[Rubbing test conditions]
The conditions for the rubbing test were specified as follows.
Head: Lens wipe (Dasper)
Rubbing load: 1.0 kg
Rubbing area: 1.0 cm ²
Sliding distance: 4 cm

[Measurement of contact angle]
In the experiment, the surface of each sample was repeatedly rubbed under the above conditions using the above friction tester. Then, the contact angle of each sample was measured after the rubbing test. For the measurement of the contact angle, 0.8 μl of pure water was dropped on the sample surface, and the contact angle θ was determined. In the experiment, each rubbing test was performed three times to obtain the average value of the contact angle θ. The contact angles shown in FIGS. 4 to 6 are all average values.

[Rubbing test results with and without base film (SiO _2)]
In the experiment, the above-mentioned rubbing test was performed using Example 9 and Comparative Example 1 to determine the relationship between the number of reciprocating repetitions and the contact angle. The experimental results are shown in FIG.

As shown in FIG. 4, in _{Example 9 having the base film (SiO 2} ), a contact angle of about 110 ° or more could be stably obtained up to about 7,000 reciprocating repetitions. On the other hand, in _{Comparative Example 1 having no base film (SiO 2} ), when the number of reciprocating repetitions exceeds about 3000 times, the contact angle sharply decreases, and when the number of reciprocating repetitions reaches about 5000 times, the contact angle becomes It was found to drop to about 70 °.

From this experimental result, it is possible to improve the adhesion of the water-repellent film by forming a laminated structure of the base film / water-repellent film without forming the water-repellent film directly on the antireflection film, and it is suitable for the rubbing test. On the other hand, it was found that high durability can be obtained.

[Rubbing test results with the base film (SiO ₂ ) and the base film (MgF _2)]
Next, the above rubbing test was performed using Example 9 and Comparative Example 2 to determine the relationship between the number of reciprocating repetitions and the contact angle. The experimental results are shown in FIG.

In Example 9 having the base film (SiO ₂ ), a contact angle of about 110 ° or more could be stably obtained up to about 7,000 reciprocating repetitions. On the other hand, in _{Comparative Example 2 having the base film (MgF 2} ), the contact angle was already only about 85 ° at the stage before the rubbing test, and when the number of reciprocating repetitions was about 100, the contact angle was about 53. The contact angle dropped sharply to °.

From the results of this experiment, it was found that the base film _{of MgF 2} cannot be used as the base layer of the water-repellent film. As the base film, a material having a hydroxyl group and causing a dehydration condensation reaction at the time of bonding with a water-repellent film such as _{SiO 2 is preferable. Specifically, the base film is made of SiO 2} , ZrO ₂ , Al _{2 or the like.} A single layer selected from O ₃ , TiO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O ₅ or a mixed layer containing two or more kinds was prepared.

[Rubbing test results due to differences in the density of the base film (SiO _2)]
In the experiment , the above-mentioned rubbing test was performed using Reference Example 1 and Comparative Example 3, and the relationship between the number of reciprocating repetitions and the contact angle was determined. The experimental results are shown in FIG.

As shown in FIG. 6, in Reference Example 1 _{having a base film (SiO 2} ) having a density of 100%, a contact angle of about 105 ° or more could be obtained even if the number of reciprocating repetitions exceeded 20000. .. On the other hand, in _{Comparative Example 3 having a base film (SiO 2} ) having a density of 65%, when the number of reciprocating repetitions exceeds about 7,000, the contact angle sharply decreases and the number of reciprocating repetitions reaches about 10,000. It was found that the contact angle was reduced to about 90 °.

From the results of this experiment, the base film as the base layer of the water-repellent film needs to have a high density, and the density was set to 70% or more and 100% or less based on this example.

The lens with a water-repellent antireflection film of the present invention has excellent adhesion and durability of the water-repellent film. Therefore, it can be preferably applied to a glass lens for a surveillance camera or an in-vehicle camera, which requires high water repellency on the lens surface.

1 Lens with water-repellent anti-reflection film 2 Glass lens 3 Water-repellent anti-reflection film 4 Anti-reflection film 5 Undercoat film 6 Water-repellent film

Claims (7)

A water-repellent antireflection film in which an antireflection film, a base film, and a water-repellent film are laminated in this order is provided on the surface of the glass lens.
The antireflection film is a single layer or two or more kinds selected from _{SiO 2} , MgF ₂ , ZrO ₂ , Al ₂ O ₃ , TIO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O _5. It has a structure in which low refractive index layers and high refractive index layers composed of a mixed layer containing a material are alternately laminated, and the uppermost layer is formed of SiO ₂ of the low refractive index layer .
The base film is _{a single layer selected from SiO 2} , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O _5, or a mixed layer containing two or more of them. It is formed and has a density of 80% or more and 100% or less and a film thickness of 1 nm or more and 200 nm or less.
The water-repellent film, said the surface of the underlying film is formed of an organic compound containing a perfluoropolyether group, Ri thickness der than 50nm or less 5 nm,
A lens with a water-repellent antireflection film, characterized in that the density of the base film is equal to or higher than the density of the uppermost layer of the antireflection film. The lens with a water-repellent antireflection film according to claim 1, wherein the base film is _{formed of SiO 2.} The lens with a water-repellent antireflection film according to claim 1 or 2, wherein the surface of the glass lens is aspherical. On the surface of the glass lens, in the first film forming chamber in which the substrate heating temperature was 200 ° C. or higher and 350 ° C. or lower, SiO ₂ , MgF ₂ , ZrO ₂ , Al ₂ O ₃ , TiO ₂ and The first step of forming an antireflection film by forming one or more layers of a single layer selected from Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O _{5 or a mixed layer containing two or more kinds of materials.} When,
The glass lens on which the antireflection film is formed is installed in a second film forming chamber different from the first film forming chamber, and at this time, the substrate heating temperature is set to the substrate heating temperature in the first step. It has a second step of continuously forming an undercoat film and a water-repellent film while keeping the temperature under reduced pressure in a second film forming chamber having a temperature lower than 250 ° C.
In the second step, a single layer selected from _{SiO 2} , ZrO ₂ , Al ₂ O ₃ , TIO ₂ , Ti ₃ O ₅ , Ta ₂ O ₅ , and Nb ₂ O ₅ is formed on the surface of the antireflection film. Alternatively, a step of forming the base film with a mixed layer containing two or more kinds of materials, and at this time, forming the base film thinner than the antireflection film.
A method for producing a lens with a water-repellent antireflection film, which comprises a step of forming the water-repellent film with an organic compound having a perfluoropolyether group on the surface of the base film. The method for manufacturing a lens with a water-repellent antireflection film according to claim 4, wherein the base film is formed by an ion beam assist method or a sputtering method. The water-repellent reflection according to claim 4 or 5, wherein the base film is formed with a film thickness of 1 nm or more and 200 nm or less, and the water-repellent film is formed with a film thickness of 5 nm or more and 50 nm or less. A method for manufacturing a lens with a protective film. The method for manufacturing a lens with a water-repellent antireflection film according to any one of claims 4 to 6, wherein the base film is _{formed of SiO 2.}

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