JP2020148806A - Antireflection film with coating film - Google Patents

Abstract

To provide an antireflection film with a coating film that is excellent in antireflection performance and durability and suppresses film absorption.SOLUTION: An antireflection film with a coating film includes an antireflection film provided on a surface of a substrate and a coating film provided on a surface of the antireflection film. The antireflection film has a multilayer laminated structure in which at least a low refractive index layer and a high refractive index layer are laminated. An outermost low refractive index layer provided on an outermost layer of the antireflection film on a side distant from the substrate is formed by an a-th layer made of MgF2., a b-th layer formed by a physical vapor deposition method without assist, and c-th layer made of SiO2 formed by the physical vapor deposition method with assist in order nearer to the substrate. The coating film is an antifouling film or a hydrophilic film consisting of one kind of compound or a mixture containing two or more kinds selected from a group of a fluorine organic compound, a fluorosilane compound, and a silane compound.SELECTED DRAWING: Figure 1

Description

The present invention relates to an antireflection film with a coating film.

A technique for preventing dirt adhesion by coating the surface of an optical component with an antifouling film or a hydrophilic film is known. This technique is widely used for lenses used in harsh outdoor environments, such as interchangeable lenses for single-lens reflex cameras, lenses for in-vehicle cameras, and lenses for surveillance cameras. On the other hand, an antireflection film is usually provided on the surface of the optical component. Therefore, it is conceivable to provide an antireflection film with a coating film on the surface of the optical component, in which the surface of the antireflection film is coated with an antifouling film or a hydrophilic film. The antireflection film with a coating film is required to have excellent antireflection performance and durability.

The basic design of the antireflection film includes HL, M2HL, 2M2HL and the like. H, M, and L mean the relative high refractive index in the antireflection film, H is a high refractive index layer, M is an intermediate refractive index layer, and L is a low refractive index layer. is there. The number before the alphabet means the phase film thickness of each refractive index layer. However, when the phase film thickness of the refractive index layer is 1, the description of the number 1 is omitted. Conventionally, MgF ₂ and SiO ₂ are known as low refractive index materials having high durability and excellent antireflection performance. Generally, MgF ₂ is used as the outermost layer for the antireflection film that requires higher antireflection performance, and SiO ₂ is used as the final layer for the antireflection film that requires higher durability.

In recent years, an antireflection film with a coating film having an antifouling film made of a fluorine-containing organic compound on the surface of the antireflection film whose outermost layer is MgF ₂ has been proposed (see, for example, Patent Document 1). However, this antireflection film with a coating film has a problem that the adhesion between the MgF ₂ layer and the antifouling film is low.

Therefore, in order to improve the adhesion between the antireflection film and the antifouling film, it is conceivable to provide a layer capable of improving the adhesion to the antifouling film on the outermost layer of the antireflection film. For example, Patent Document 2, as the outermost layer of the antireflection film, the SiO ₂ layer was deposited by vacuum evaporation on the surface of MgF ₂ layer, with an antifouling film made of a fluororesin on the surface coating An antireflection film with a film is disclosed. In the case of this antireflection film with a coating film, since SiO ₂ and the fluororesin are chemically bonded, the SiO ₂ layer, which is the outermost layer of the antireflection film, and the antifouling film are firmly adhered to each other. However, since the SiO ₂ layer is not dense, this antireflection film with a coating film has a problem that it has low wear resistance and is easily scratched.

Therefore, a method of densifying the SiO ₂ layer by forming a film of the SiO ₂ layer provided on the surface of the MgF ₂ layer by an ion-assisted vapor deposition method can be considered.

JP-A-2009-92746 International Publication No. 2013/118622

However, when the SiO ₂ layer deposited by ion-assisted deposition, F ₂ from MgF ₂ layer by the charged particles is eliminated, film absorption occurs accordingly. The antireflection film with a coating film having increased film absorption impairs the optical performance of the optical component, for example, when it is provided on an image pickup lens or the like as an optical component.

From the above, it is an object of the present invention to provide an antireflection film with a coating film which is excellent in antireflection performance and durability and suppresses film absorption.

Therefore, the inventors of the present invention have come up with the following inventions as a result of diligent studies to solve the above-mentioned problems.

The antireflection film with a coating film according to the present invention is an antireflection film with a coating film provided on the surface of the antireflection film provided on the surface of the base material, and the antireflection film is at least low. The outermost low refractive index layer provided on the outermost layer of the antireflection film on the side farther from the base material has a multilayer laminated structure in which a refractive index layer and a high refractive index layer are laminated, and the outermost low refractive index layer is provided in order from the side closer to the base material. , MgF ₂ , layer b formed by a physical vapor deposition method without assist, and layer c made of SiO ₂ formed by a physical vapor deposition method with assist. The film is characterized by being an antifouling film or a hydrophilic film composed of one compound selected from the group of fluorine-based organic compounds, fluorosilane-based compounds, and silane-based compounds, or a mixture containing two or more kinds.

In the antireflection film with a coating film of the present invention, the outermost low refractive index layer of the antireflection film is formed by a layer a made of MgF _{2 in} order from the side closer to the base material and a physical vapor deposition method without assistance. It is composed of a three-layer structure consisting of the b-layer formed therein and the c-th layer made of SiO ₂ formed by a physical vapor deposition method accompanied by an assist. Therefore, the antireflection film with a coating film of the present invention is excellent in antireflection performance and durability, and can suppress film absorption.

It is a schematic cross-sectional view which shows the antireflection film with a coating film which concerns on this invention. It is a graph which shows the reflection characteristic of the antireflection film with a coating film of Example 1.

Hereinafter, embodiments of the antireflection film with a coating film according to the present invention will be described in detail. However, the antireflection film with a coating film used in the following description is merely one aspect, and should not be construed as being limited to the following aspects.

1. 1. Configuration of Antireflection Film with Coating Film The antireflection film with coating film according to the present invention includes an antireflection film provided on the surface of the base material and a coating film provided on the surface of the antireflection film. An antireflection film with a film, the antireflection film has a multilayer laminated structure in which at least a low refractive index layer and a high refractive index layer are laminated, and is provided on the outermost layer of the antireflection film on the side far from the base material. The outermost low refractive index layer formed is a layer a made of MgF ₂ , a layer b formed by a physical vapor deposition method without assist, and a physical vapor deposition method with assist, in order from the side closer to the substrate. The coating film is composed of a c-th layer made of SiO ₂ formed by, and contains one kind of compound selected from the group of fluorine-based organic compounds, fluorosilane-based compounds, and silane-based compounds, or two or more kinds. It is characterized by being an antifouling film or a hydrophilic film composed of a mixture.

The antireflection film 1 with a coating film shown in FIG. 1 includes a coating film 3 on the surface of the antireflection film 2 provided on the surface of the optical element base material 11. Hereinafter, the antireflection film 2 and the coating film 3 will be described in order.

(1) Antireflection film The antireflection film 2 is provided on the surface of the optical element base material 11 and plays a role of reducing the reflection of incident light on the surface of the optical element base material 11. The antireflection film 2 has at least a multilayer laminated structure in which a low refractive index layer and a high refractive index layer are laminated. The antireflection film 2 adopts such a multilayer structure because the antireflection effect can be easily exhibited. In the antireflection film 2, the low refractive index layer 4 having a refractive index of 1.2 or more and 1.7 or less and the high refractive index layer 5 having a refractive index of 1.8 or more and 2.6 or less may be alternately laminated. preferable. Further, the antireflection film 2 may further include an intermediate refractive index layer having a refractive index between the low refractive index layer 4 and the high refractive index layer 5.

FIG. 1 shows an antireflection film 2 having a multi-layer laminated structure. The layer structure of the antireflection film 2 can be appropriately changed in consideration of the required quality. Hereinafter, the number of layers of the antireflection film 2 is referred to as N. N is an integer of 3 or more, but 5 or more is preferable in order to surely obtain the above-mentioned antireflection effect. On the other hand, although the upper limit of N is not particularly defined, N is preferably 15 or less in consideration of the market demand for the antireflection film 2.

The antireflection film 2 shown in FIG. 1 has a multi-layered structure in which four layers of low refractive index layers 4 and three layers of high refractive index layers 5 are alternately laminated to provide a total of seven layers. That is, the first layer, the third layer, the fifth layer, and the seventh layer are the low refractive index layer 4, and the second layer, the fourth layer, and the sixth layer are counted from the side closest to the optical element base material 11. The high refractive index layer 5. Each of the low refractive index layer 4 and the high refractive index layer 5 may be composed of one optical thin film or may be composed of two or more optical thin films. For example, when the low refractive index layer 4 having a refractive index of 1.5 is composed of three optical thin films, the refractive index is 1.5 when the three optical thin films are laminated.

The Nth layer, which is the outermost layer of the antireflection film 2, is a low refractive index layer 4. Hereinafter, the low refractive index layer 4 provided on the outermost layer will be referred to as “outermost low refractive index layer 6”. In FIG. 1, the low refractive index layer 4 of the seventh layer is the outermost low refractive index layer 4. The outermost low refractive index layer 6 is composed of a first layer 6a made of MgF ₂ , a bth layer 6b formed by a physical vapor deposition method without assist, and a physical body with assist, in order from the side closer to the optical element base material 11. It has a three-layer structure with a third layer 6c made of SiO ₂ formed by a vapor deposition method.

In the antireflection film 1 with a coating film according to the present invention, the outermost low refractive index layer 6 of the antireflection film 2 has the above-mentioned three-layer structure of the a layer 6a, the b layer 6b and the c layer 6c. Therefore, the antireflection performance and durability are excellent, and the film absorption can be suppressed. Hereinafter, the first layer to the Nth layer of the antireflection film 2 will be described in detail in order from the side closest to the optical element base material 11. The "physical vapor deposition method with assist" will be described later.

First layer to N-1 layer: The N-1 layer is the N-1th layer counted from the side closer to the optical element base material 11, and is the Nth layer, the outermost low refractive index layer 6. It is the layer directly below. In FIG. 1, the first to N-1 layers are the low refractive index layers 4 of the first layer, the third layer, and the fifth layer, and the second layer, counting from the side closer to the optical element base material 11. It is a high refractive index layer 5 of the 4th layer and the 6th layer. Each layer from the first layer to the N-1 layer can improve the adhesion between the optical element base material 11 and the coating film 3 and can impart an antireflection effect, which hinders the optical performance of the optical element base material 11. As long as it does not, there are no particular restrictions on the materials used. For example, each layer from the first layer to the N-1 layer is selected from the group of Al ₂ O ₃ , SiO ₂ , Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , ZrO ₂ , and La ₂ O _3. It preferably consists of seeds or a mixture of two or more. This is because it is suitable as a material for imparting an antireflection function without impairing the optical performance of the optical element base material 11.

Each layer from the first layer to the N-1 layer is formed by using a physical vapor deposition method such as a vacuum vapor deposition method, an ion plating method, or a sputtering method.

Nth layer: The Nth layer is a low refractive index layer 4 provided on the outermost layer of the antireflection film 2, that is, the outermost low refractive index layer 6. The Nth layer is formed by the layer a 6a made of MgF ₂ , the layer b 6b formed by the physical vapor deposition method without assist, and the physical vapor deposition method with assist in order from the side closer to the optical element base material 11. It has a three-layer structure of a third layer 6c made of SiO ₂ . Hereinafter, the ath layer 6a, the bth layer 6b, and the cth layer 6c will be described.

Layer a 6a: The layer a 6a is a layer made of MgF ₂ provided directly above the N-1 layer. MgF ₂ is a material having particularly high antireflection performance among known low refractive index materials.

The layer a 6a is formed by a physical vapor deposition method without assistance. Examples of the physical vapor deposition method include a vacuum vapor deposition method, an ion plating method, and a sputtering method. If the layer a 6a is formed by a physical vapor deposition method accompanied by an assist, fluorine desorption of MgF ₂ may occur, which is not preferable.

Layer b 6b: Layer b 6b is a layer formed by a physical vapor deposition method without assistance. As will be described later, the b-layer 6b plays a role of protecting the a-layer 6a from being affected when the c-layer 6c is formed by a physical vapor deposition method accompanied by an assist.

The b-layer 6b is preferably a layer made of an oxide or a composite oxide selected from the group of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , and La ₂ O ₃ . This is because it is suitable as a material for imparting an antireflection function without impairing the optical performance of the optical element base material 11. Further, the layer b 6b is more preferably made of SiO ₂ because it has high durability and excellent antireflection performance.

Layer c 6c: Layer c 6c is a layer made of SiO ₂ formed by a physical vapor deposition method accompanied by assistance. Since the c-th layer 6c was formed by a physical vapor deposition method accompanied by an assist, the layer c is densified and has excellent durability. Further, since the c-th layer 6c is a layer made of SiO ₂ , it has excellent adhesion to the coating film 3 formed on the c-th layer 6c, as will be described later.

Next, the film thicknesses of the ath layer 6a, the bth layer 6b, and the cth layer 6c will be described. When the phase film thicknesses of the first layer 6a, the bth layer 6b, and the cth layer 6c are Qa, Qb, and Qc, it is preferable to satisfy the following conditional expression (1).
0.7 <Qa + Qb + Qc <1.3 ... (1)

In the conditional expression (1), the total of the phase film thickness Qa of the layer a 6a, the phase film thickness Qb of the layer b 6b, and the phase film thickness Qc of the layer c 6c is in the range of 0.7 to 1.3. It means that it fits in. By satisfying the above conditional expression (1), the antireflection film 2 can surely obtain excellent antireflection performance. When Qa + Qb + Qc is 0.7 or less or 1.3 or more, the antireflection film 2 may not be able to obtain excellent antireflection performance, which is not preferable.

Further, it is preferable to satisfy the conditional expression (2).
0.5 ≤ Qa / (Qa + Qb + Qc) <1 ... (2)

In the above conditional expression (2), the ratio of the phase film thickness Qa of the layer a 6a to the total phase film thickness (Qa + Qb + Qc) of the layer a 6a, the layer b 6b, and the layer c 6c is 0.5 or more and less than 1. It means that it falls within the range of. By satisfying the above conditional expression (2), the outermost low refractive index layer 6 can obtain excellent optical characteristics. When Qa / (Qa + Qb + Qc) is less than 0.5, the phase film thickness Qa of the ath layer 6a becomes relatively small, and the outermost low refractive index layer 6 cannot secure excellent optical characteristics. It is not preferable because it may occur. On the other hand, when Qa / (Qa + Qb + Qc) is 1, the outermost low refractive index layer 6 is composed of only the ath layer 6a and the bth layer 6b and the cth layer 6c are not present, so that the coating film 3 is sustained. I can't get sex.

The b-layer 6b has a physical film thickness of 2 nm or more because it plays a role of protecting the a-layer 6a from being affected when the c-layer 6c is formed by a physical vapor deposition method accompanied by assistance. Is preferable. If the physical film thickness of the b-layer 6b is less than 2 nm, the a-layer 6a may not be protected, which is not preferable. There is no particular upper limit to the physical film thickness of the b-layer 6b, but if it becomes excessively thick, the above conditional expression (2) may not be satisfied, so 50 nm or less is preferable.

Further, the physical film thickness of the c-th layer 6c is preferably 2 nm or more in order to ensure durability. If the physical film thickness of the c-th layer 6c is less than 2 nm, durability may not be obtained, which is not preferable. There is no particular upper limit to the physical film thickness of the c-th layer 6c, but if it becomes excessively thick, the above conditional expression (2) may not be satisfied, so 40 nm or less is preferable.

(2) Coating film The coating film 3 is an antifouling film or a hydrophilic film, and both can adopt the same configuration. The antifouling film is a film having water repellency and oil repellency for preventing contamination of the surface of the optical element base material 11 and contamination adhesion such as dirt. The hydrophilic film is a film having hydrophilicity for preventing fogging on the surface of the optical element base material 11.

The coating film 3 is formed on the surface of the outermost low refractive index layer 6 of the antireflection film 2 described above, and is a compound selected from the group of fluorine-based organic compounds, fluorosilane-based compounds, and silane-based compounds. It consists of a mixture containing two or more kinds. The refractive index of the coating film 3 made of the above compound or mixture is in the range of 1.4 or more and 1.8 or less.

The functional group of the compound or mixture constituting the coating film 3 and SiO ₂ constituting the cth layer 6c of the outermost low refractive index layer 6 are chemically bonded. For example, when the coating film 3 is an antifouling film made of an organic compound having a hydroxy group, the hydroxy group and SiO ₂ are bonded by a dehydration condensation reaction. Further, when the coating film 3 is a hydrophilic film made of an organic compound having a silanol group, the silanol group and SiO ₂ are bonded by a silanol reaction. As a result, since the coating film 3 and the cth layer 6c of the outermost low refractive index layer 6 are firmly adhered to each other, the antireflection film 1 with a coating film can obtain excellent durability.

The physical film thickness of the coating film 3 is 2 nm or more and 50 nm or less in order to ensure water repellency and oil repellency without impairing the optical performance of the optical element base material 11 and the antireflection performance of the antireflection film 2. Is preferable. If the physical film thickness of the coating film 3 is less than 2 nm, the film thickness cannot be made uniform, and water repellency and oil repellency cannot be stably obtained, which is not preferable. On the other hand, if the physical film thickness of the coating film 3 exceeds 50 nm, the material of the coating film 3 becomes particles and causes scattering, which is not preferable.

(3) Optical Element Base Material The optical element base material 11 may be any lens classified as a lens used in an imaging device or an observation device, and the type thereof is not particularly limited. Examples of the optical element base material 11 include optical lenses such as cameras and telescopes, beam splitters, and prism lenses.

The optical element base material 11 may be a glass material or a plastic material. When a glass material is used for the optical element base material 11, the type is not particularly limited, and non-alkali glass, soda lime glass, aluminosilicate glass and the like can be used.

(4) Effect of Antireflection Film with Coating Film As described above, in the antireflection film 1 with a coating film, the outermost low refractive index layer 6 is composed of the ath layer 6a, the bth layer 6b, and the cth layer 6c. It has a three-layer structure, and a coating film 3 is provided on the outermost low refractive index layer 6.

Since the ath layer 6a of the outermost low refractive index layer 6 is made of MgF ₂ and the cth layer 6c is made of SiO _{2, the} antireflection film 1 with a coating film realizes excellent antireflection performance. Can be done.

Then, the c layer 6c directly below the coated film 3 comprising the outermost layer of the antireflection film 2 is to become the SiO _2, and the compound or mixture constituting the SiO ₂ and the covering layer 3 is chemically bonded, The c-th layer 6c and the coating film 3 are firmly adhered to each other. Since the c-th layer 6c is densified by being formed by a physical thin-film deposition method accompanied by an assist, it is a layer having excellent durability. Further, the b-layer 6b provided directly below the c-layer 6c is formed by a physical thin-film deposition method without assistance, and is therefore in a sparser state than the c-layer 6c. Therefore, the b-th layer 6b can act as a stress relaxation layer. From these facts, the antireflection film 1 with a coating film can realize excellent durability. If there is no layer b 6b between the layer c 6c made of dense SiO ₂ and the layer a 6a made of MgF _2, there is no layer acting as a stress relaxation layer, so that the coating film The antireflection film 1 with attachment cannot realize excellent durability.

Further, since the b-layer 6b is formed by the physical vapor deposition method without assist, unlike the case where the layer b 6b is formed by the physical vapor deposition method with assist, fluorine desorption does not occur in MgF ₂ of the layer a 6a. The occurrence of membrane absorption is suppressed. From the above, the antireflection film 1 with a coating film can suppress film absorption.

2. 2. Method for manufacturing antireflection film with coating film (1) Formation of antireflection film The antireflection film 2 includes an N-layer multilayer structure in which a low refractive index layer 4 and a high refractive index layer 5 are laminated. Hereinafter, the first layer to the N-1 layer and the outermost low refractive index layer 6 which is the Nth layer will be described separately. The outermost low refractive index layer 6 will be described separately for the ath layer 6a, the bth layer 14b, and the cth layer 14c.

Formation of first layer to N-1 layer: Each layer from the first layer to the N-1 layer is composed of the above-mentioned Al ₂ O ₃ , SiO ₂ , Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , ZrO. _{2. A} film is formed by a physical vapor deposition method such as a vacuum vapor deposition method, an ion plating method, or a sputtering vapor deposition method using La ₂ O ₃ or the like. Since it is possible to apply a method known among those skilled in the art to these physical vapor deposition methods and it is not necessary to adopt special film forming conditions, detailed description thereof will be omitted. The vapor deposition process for forming any of the first layer to the N-1 layer may or may not be accompanied by an assist.

The "physical vapor deposition method with assist" in the present invention means an "ion beam assist method" or a "plasma assist method". The ion beam assist method is a method in which a chemical reaction is assisted by an irradiated ion beam during film formation by a physical vapor deposition method. The plasma assist method is a method in which a chemical reaction is assisted by electrons emitted by a plasma gun during film formation by a physical vapor deposition method. Specifically, the reaction is promoted by generating high-density plasma in the chamber and ionizing the vapor-deposited material molecules and the introduced gas molecules. By performing the ion beam assist method or the plasma assist method, it is possible to improve the film density, adhesion and the like. Since a known method can be applied to the assist, it is considered that no special explanation is required, and a detailed explanation is omitted.

Formation of layer a 6a: The layer a 6a is formed by a physical vapor deposition method in the same manner as the formation of the first layer to the N-1 layer described above, but basically ion beam assist or plasma assist is performed. Absent. Since the concept of the physical vapor deposition method is the same as described above, duplicate description will be omitted.

Formation of b-layer 6b: The b-layer 6b is formed by a physical vapor deposition method in the same manner as the formation of the first layer to the N-1 layer described above, but ion beam assist or plasma assist is not performed. Since the concept of the physical vapor deposition method is the same as described above, duplicate description will be omitted.

Since ion beam assist or plasma assist is not performed during the film formation of the b-layer 6b, it is possible to prevent fluorine desorption in the MgF ₂ layer which is the a-layer 6a. Therefore, the film absorption in the layer a 6a can be suppressed.

Formation of layer c 6c: The layer a 6a is formed by a physical vapor deposition method in the same manner as the formation of the first layer to the N-1 layer described above, but it is essential to perform ion beam assist or plasma assist. Is. Since the concept of the physical vapor deposition method and the assist is the same as described above, duplicate description will be omitted.

(2) Formation of Coating Film The coating film 3 can be produced by a known method. For example, the antifouling film is impregnated with a fluorine-based organic compound (having one or more groups among a perfluoropolyether group containing a fluoroorganic group, a perfluoroalkylene group, a perfluoroalkyl group, etc.) as an antifouling agent. A film can be formed by a resistance heating method or a vacuum vapor deposition method using the metal tablet. At this time, there are no particular restrictions on the heating conditions and the vapor deposition conditions, and a known method can be used.

Further, the hydrophilic film can be formed by spin coating or dip coating using a hydrophilic solution diluted with water or a highly volatile solvent. The hydrophilic membrane may be dried at a temperature of about 80 ° C. or higher and 100 ° C. or lower using an oven or the like in order to dry quickly.

The embodiment described above is one aspect of the antireflection film 1 with a coating film according to the present invention, and can be changed without departing from the spirit of the present invention. Hereinafter, a more specific description will be given in the examples.

3. 3. Production method and measurement method used in Examples and Comparative Examples The examples and comparative examples will be described below. In this example and the comparative example, an antireflection film 1 with a coating film in which the coating film 3 is an antifouling film or a hydrophilic film is formed on the surface of the optical element base material 11. First, a method for forming the antireflection film 2, a method for forming the coating film 3, and a method for measuring the antireflection film 1 with a coating film will be described.

(1) Method for forming an antireflection film The antireflection film 2 was formed as follows. After cleaning the optical element base material 11 with an ultrasonic automatic washing machine, a first layer to an N-1 layer are formed on the surface of the optical element base material 11 by a vacuum vapor deposition method using a vacuum vapor deposition apparatus manufactured by Optran. The low refractive index layer 4 and the high refractive index layer 5 were alternately formed. Subsequently, the a layer 6a, the b layer 6b, and the c layer 6c are sequentially formed on the N-1 layer by a physical vapor deposition method (PVD) or an ion beam assist method (IAD) without assistance. By doing so, the outermost refractive index layer 6 which is the Nth layer was formed.

(2) Specific film forming method of coating film After the optical element base material 11 on which the antireflection film 2 is formed is washed with an automatic ultrasonic cleaning machine, a coating film is formed on the outermost surface of the antireflection film 2. An antifouling film or a hydrophilic film was formed. The coating film 3 was formed by any of a vacuum vapor deposition method by resistance heating, a dipping method, and a spin coating method. In the vacuum vapor deposition method by resistance heating, a vacuum vapor deposition apparatus SGC-22 manufactured by Showa Vacuum Co., Ltd. was used. After forming the coating film 3, the coating film 3 was adjusted to a desired physical film thickness by performing a cleaning treatment with an ultrasonic automatic cleaning machine to remove the excess layer.

(3) Measurement method of antireflection film with coating film For the obtained antireflection film 1 with coating film, haze measurement, reliability test, abrasion resistance test and spectral reflectance measurement are performed as follows. went.

Haze measurement: With respect to the obtained antireflection film 1 with a coating film, the presence or absence of film absorption was confirmed using a haze meter NDH7000 manufactured by Nippon Denshoku Co., Ltd. If there is almost no film absorption and it can be sufficiently used as an optical member, it is judged as ○, and if it has little film absorption and its spectral characteristics are inferior but it can be used as an optical member, it is judged as △, and there is a lot of film absorption. When it cannot be used as an optical member, it is determined to be × (see Table 4 below).

Reliability test: The reliability test (high temperature test and high temperature and high humidity test) was carried out by putting the obtained antireflection film 1 with a coating film into an SH constant temperature bath manufactured by ESPEC. The conditions for each test are as follows. Then, the appearance of the antireflection film 1 with a coating film was visually observed. If there is no change in the appearance of the sample before and after the test, it is judged as ○, and if defects such as cracks occur only around the sample after the test, it is judged as △, and the entire surface of the sample is defective after the test. In that case, it was determined to be × (see Table 4).
High temperature test: Test temperature 85 ° C, holding time 240 hours High temperature and high humidity test: Test temperature 60 ° C, humidity 90%, holding time 240 hours

Abrasion resistance test: The obtained antireflection film 1 with a coating film was subjected to an abrasion resistance test as follows. First, using the antireflection film 1 with a coating film as a sample, 100 g of eight kinds of test powders (Kanto loam mud) described in JIS Z 8901 were immersed in a slurry dissolved in 1 L of water. Then, with the sample immersed in the slurry, the sample was worn 1000 times back and forth with a clean paper loaded with a load of 200 gf or 500 gf using a brush by a wear tester Tribogear Type 14 (Shinto Kagaku Co., Ltd.). Then, the appearance of the sample was visually observed. If there was no change in the appearance of the sample before and after the test, it was judged as ○, if there were several noticeable scratches, it was judged as △, and if there were many noticeable scratches, it was judged as × (Table 4). reference).

Spectral reflectance measurement: The spectral reflectance of the obtained antireflection film 1 with a coating film was measured by a reflection spectral film thickness meter FE-3000 manufactured by Otsuka Electronics Co., Ltd. Then, the angle of incidence of the incident light on the central portion of the antireflection film 1 with a coating film was set to 0 °, and the wavelength range of the incident light was changed within the range of 350 nm or more and 850 nm or less. When the reflectance was 1% or less over the entire wavelength range of 400 nm and 700 nm or less, it was judged as ◯, and when the reflectance was more than 1%, it was judged as x (see Table 4).

Hereinafter, Examples and Comparative Examples will be described.

In Examples 1 to 13, a glass material made of any one of TAC8, TAF1, FCD1 and BK7 was used as the optical element base material 11. Then, the low refractive index layer 4 and the high refractive index layer 5 forming the first layer to the N-1 layer were alternately formed on the surface of the optical element base material 11. Subsequently, the a layer 6a, the b layer 6b, and the c layer 6c are sequentially formed on the N-1 layer by a physical vapor deposition method (PVD) or an ion beam assist method (IAD) without assistance. By doing so, the outermost refractive index layer 6 which is the Nth layer was formed. Then, the antireflection film 1 with a coating film was produced by forming an antifouling film or a hydrophilic film as the coating film 3 on the surface of the outermost refractive index layer 6 of the antireflection film 2. Tables 1 to 3 show specific layer configurations of the antireflection film 1 with a coating film of each embodiment. In the column of "deposited material" in each table, for example, the description "ZrO ₂ + TiO ₂ " means that it is a mixed oxide of ZrO ₂ and TiO ₂ . Further, in the column of "deposition method" in each table, the description "PVD" means that the film was formed by the physical vapor deposition method without assistance, and the description "IAD" means that the film was formed by the ion beam assist method. Means that. The outermost refractive index layer 6 is not affected by the materials constituting each of the first to N-1 layers and the film forming method of each layer. Therefore, a specific description regarding the layer structure of the first layer to the N-1 layer will be omitted.

Comparative example

In Comparative Examples 1 to 4, TAC8 was used as the optical element base material 11. Then, on the surface of the optical element base material 11, the low refractive index layer 4 and the high refractive index layer 5 constituting the first layer to the N-1 layer are alternately arranged in exactly the same manner as in Examples 1 to 13. A film was formed. Subsequently, on the N-1 layer, one of the a layer 6a, the b layer 6b, and the c layer 6c is performed by a physical vapor deposition method (PVD) or an ion beam assist method (IAD) without assistance. By forming a layer or two layers, the outermost refractive index layer 6 which is the Nth layer was formed. Table 3 shows a specific layer structure of the antireflection film 1 with a coating film of each comparative example.

Next, with respect to the obtained antireflection film 1 with a coating film of Examples 1 to 13 and Comparative Examples 1 to 4, the haze measurement, the reliability test, the abrasion resistance test and the abrasion resistance test were carried out by the above-mentioned methods. Spectral reflectance measurement was performed. The results are shown in Tables 1 to 4. Regarding the spectral reflectance measurement, FIG. 2 shows a graph showing the reflection characteristics of the antireflection film 1 with a coating film of Example 1.

[Evaluation]
As shown in Table 1, the antireflection film 1 with a coating film of Examples 1 to 13 has a haze measurement, a reliability test (high temperature test, high temperature and high humidity test), an abrasion resistance test, and a spectral reflectance. The measurement results were all good. The shape of the graph showing the reflection characteristics of Examples 2 to 13 has the same reflectance as the shape of the graph showing the reflection characteristics of Example 1 shown in FIG. 2 over the entire wavelength range of 400 nm and 700 nm or less. It was less than 1%. From the above results, it is clear that the antireflection film 1 with a coating film of Examples 1 to 13 can suppress film absorption and is excellent in durability and antireflection performance.

On the other hand, the antireflection film 1 with a coating film of Comparative Examples 1 to 4 had good results of spectral reflectance measurement. However, the antireflection films 1 with a coating film of Comparative Examples 1 to 4 did not have good results in haze measurement, reliability test, and abrasion resistance test. From the above results, it is clear that the antireflection film 1 with a coating film of Comparative Examples 1 to 4 cannot suppress film absorption or is not excellent in durability and antireflection performance.

The antireflection film with a coating film according to the present invention can suppress film absorption and is excellent in durability and antireflection performance. Therefore, optical lenses, eyeglass lenses, binoculars, cameras such as in-vehicle cameras and surveillance cameras, etc. Alternatively, it is suitable for lenses, beam splitters, prisms and the like of other optical devices.

1 Anti-reflection film with coating film 2 Anti-reflection film 3 Coating film 4 Low refractive index layer 5 High refractive index layer 6 Outermost low refractive index layer 6a Outermost low refractive index layer a layer 6b Outermost low refractive index Layer b of layer 6c Layer c of outermost low refractive index layer 11 Base material

Claims (8)

An antireflection film with a coating film provided on the surface of the antireflection film provided on the surface of the base material.
The antireflection film has at least a multilayer laminated structure in which a low refractive index layer and a high refractive index layer are laminated.
The outermost low refractive index layer provided on the outermost layer of the antireflection film on the side farther from the base material is the layer a made of MgF _{2 in} order from the side closer to the base material, and a physical vapor deposition method without assistance. The b-layer formed by the above and the c-th layer made of SiO ₂ formed by a physical vapor deposition method accompanied by an assist.
The coating film is characterized by being an antifouling film or a hydrophilic film composed of one compound selected from the group of fluoroorganic compounds, fluorosilane compounds, and silane compounds, or a mixture containing two or more of them. Anti-reflection film with a coating film. The antireflection with a coating film according to claim 1, wherein when the phase film thicknesses of the ath layer, the bth layer, and the cth layer are Qa, Qb, and Qc, the following conditional expression (1) is satisfied. film.
0.7 <Qa + Qb + Qc <1.3 ... (1) The coating according to claim 1 or 2, wherein when the phase film thicknesses of the ath layer, the bth layer, and the cth layer are Qa, Qb, and Qc, the following conditional expression (2) is satisfied. Anti-reflection film with film.
0.5 ≤ Qa / (Qa + Qb + Qc) <1 ... (2) The antireflection film with a coating film according to any one of claims 1 to 3, wherein the physical film thickness of the b-layer is 2 nm or more. The antireflection film with a coating film according to any one of claims 1 to 4, wherein the physical film thickness of the c-th layer is 2 nm or more. The b-layer is any one of claims 1 to 5, which is composed of an oxide or a composite oxide selected from the group of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , and La ₂ O _3. The antireflection film with a coating film described in 1. As the low refractive index layer and the high refractive index layer other than the outermost low refractive index layer constituting the antireflection film, Al ₂ O ₃ , SiO ₂ , Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , The antireflection with a coating film according to any one of claims 1 to 6, further comprising one or more layers composed of one or a mixture of two or more selected from the group of ZrO ₂ and La ₂ O _3. film. The antireflection film with a coating film according to any one of claims 1 to 7, wherein the physical film thickness of the coating film is 2 nm or more and 50 nm or less.

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