JP2022078665A - Optical member and method for manufacturing optical member - Google Patents

Abstract

To prevent a reduction in anti-reflection effect after absorption of moisture of a member having anti-reflection properties and anti-fogging properties.SOLUTION: A member comprises a porous layer on a substrate, and the porous layer has a first area, a second area, and a third area in order from a substrate side. The first area includes first particles; the third area includes second particles different in shape from the first particles; the second area includes the first particles and the second particles. The average porosity of the second area is larger than the average porosity of the first area. The average porosity of the third area is larger than the average porosity of the second area.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical member having excellent anti-fog performance and optical performance, and a method for manufacturing the optical member.

When the surface of a transparent substrate such as glass or plastic falls below the dew point temperature, fine water droplets adhere to the surface of the substrate and the transmitted light is scattered and the transparency is impaired, resulting in a so-called "cloudy" state. Become. Therefore, particularly transparent members are often required to have anti-fog performance as well as optical performance such as light reflection prevention.

In Patent Document 1, a porous structure in which metal oxide fine particles are bonded with a binder is provided on a base material, and moisture in the atmosphere is adsorbed in the porous structure to prevent light reflection and antifogging. The optical components that realize the above are disclosed.

Japanese Unexamined Patent Publication No. 2013-105846

When water is adsorbed on the voids of the porous structure, the air in the voids is replaced with water, so that the refractive index increases. Therefore, when the member of Patent Document 1 is exposed to an environment where anti-fog performance is required and the porous structure adsorbs moisture, the refractive index increases. Then, it changes from the optically designed state without absorbing moisture, and the antireflection performance is significantly deteriorated.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide a member having anti-fog property and a method for manufacturing the member, in which deterioration of antireflection performance due to moisture absorption is suppressed.

The member according to the present invention is a member provided with a porous layer on a base material, and the porous layer comprises a first region, a second region, and a third region in order from the base material side. The first region is the first particle, the third region is the second particle having a shape different from that of the first particle, and the second region is the first particle and the second particle. The particles are each contained, and the average porosity of the second region is larger than the average porosity of the first region and smaller than the average porosity of the third region.

According to the present invention, it is possible to realize a member having anti-fog performance and a method for manufacturing the member, in which deterioration of anti-reflection performance due to moisture absorption is suppressed.

(A) is a schematic view showing one embodiment of the optical member according to the present invention, and (b) is an enlarged view of a porous layer. (A) is a diagram showing a member in which only a porous layer is formed on a base material, and (b) is a diagram showing a member in which a thin-film deposition film layer is formed between the porous layer and the base material. It is one embodiment of the optical member which concerns on this invention, and is the schematic of the member which has the surface antireflection layer. It is one embodiment of the optical member which concerns on this invention, and is the schematic of the member which has the base antireflection layer. It is one embodiment of the optical member which concerns on this invention, and is the schematic of the member which has a hydrophilic polymer layer. It is a schematic diagram which shows the structural example of the image pickup apparatus of this invention. It is a figure which shows the reflectance characteristic before and after water absorption of Example 1. FIG. It is a figure which shows the reflectance characteristic before and after water absorption of the comparative example 1. FIG.

Hereinafter, embodiments according to the present invention will be described, but the present invention is not limited to these embodiments unless otherwise specified.

[Optical member]
FIG. 1A shows a schematic diagram showing one form of the member of the present invention.

The member 100 of the present invention has a porous layer 20 on the base material 10 in order from the base material side, which includes a first region 21, a second region 22, and a third region 23. It has anti-fog performance and anti-reflection layer performance. Although the figure shows a configuration in which the porous layer 20 is provided on one side of the base material 10, the porous layers 20 may be provided on both sides of the base material 10 depending on the application.

The member 100 of the present invention can be used in a wide range of applications such as window glass, mirrors, lenses, and transparent films by appropriately selecting the base material 10. In particular, it is suitable for applications such as optical lenses for imaging systems and projection systems, optical mirrors, optical filters, eyepieces, flat covers and dome covers for outdoor cameras and surveillance cameras, face shields and mouse shields.

(Base material)
As the material of the base material 10, glass, resin, or the like can be used. The shape is not limited, and may be a flat surface, a curved surface, a concave surface, a convex surface, or a film shape.

Inorganic glass containing zirconium oxide, titanium oxide, tantalum oxide, niobium oxide, hafnium oxide, lanthanum oxide, gadolinium oxide, silicon oxide, calcium oxide, barium oxide, sodium oxide, potassium oxide, boron oxide, aluminum oxide, etc. Glass can be used. The glass substrate can be molded by grinding and polishing, molding, float molding and the like.

As the resin, polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose, acrylic resin, polycarbonate, cycloolefin polymer, polyvinyl alcohol and the like can be used.

For the purpose of improving the strength and flatness of the base material 10, and improving the adhesion of the film in contact with the base material 10, the surface of the base material 10 is cleaned or polished, and functional layers such as an adhesive layer and a hard coat layer are provided. It may be provided.

(Porous layer)
FIG. 1B shows an enlarged view of the porous layer 20. The first region contains the first particle 24, the third region contains the second particle 25 having a different shape from the first particle, and the second region contains the first particle 24 and the second particle. Contains both of 25. The term "different shapes" here includes similar figures with different sizes. FIG. 1B shows a case where the first particle 24 is a spherical particle and the second particle 25 is a chain-shaped particle.

Voids are formed between the particles contained in the porous layer 20, and three-dimensionally communicate with each other to connect with the outside air. Due to such a porous structure, when the humidity of the external environment of the member becomes high, the moisture contained in the air that has entered the voids of the porous layer 20 is condensed and adsorbed, and anti-fog property can be exhibited. Further, since the voids contained in the porous layer 20 communicate with each other, it is possible to adsorb moisture by utilizing the entire voids contained in the layer, and high anti-fog performance can be exhibited.

In the porous layer 20 of the member according to the present invention, the average porosity of the second region 22 is larger than the average porosity of the first region 21 and smaller than the average porosity of the front third region 23. .. Among the porous layers 20, the third region 23 has the largest average porosity and mainly plays a role of adsorbing water. Therefore, if only the anti-fog performance is required for the porous layer 20, it is sufficient to have only the third region, but if the anti-fog performance is required in addition to the anti-fog performance, the third region is required. It is not enough. The reason will be explained below.

As shown in FIG. 2A, consider a case where a porous layer 220 having a large porosity is directly formed on the base material 10 for anti-fog. The refractive index of the base material 10 made of glass or resin is about 1.5, while the refractive index of the porous layer 220 provided for anti-fog is about 1.2 to 1.3. When the difference in refractive index is large as described above, light reflection _R1 occurs at the interface between the base material 10 and the porous layer 220.

In order to reduce the light reflection generated at the interface between the base material 10 and the porous layer 220, the refractive index of the porous layer 220 and the refractive index of the base material 10 are intermediate between the porous layer 220 and the base material 10. The configuration of FIG. 2 (b) in which the layer 221 having the refractive index of is provided is conceivable. The difference in the refractive index between the porous layer 220 and the layer 221 and the difference in the refractive index between the base material 10 and the porous layer 220 are set to the same level, and the film thickness of the layer 221 is an integral multiple of λ / 4 of the wavelength λ to be reduced. do. With such a configuration, it is possible to reduce the reflected light due to the interference between the reflected light _R1 at the interface between the layer 221 and the base material 10 and the reflected light _R2 at the interface between the porous layer 220 and the layer 221.

However, the configuration of FIG. 2B has the following problems. When the optical member is exposed to a high humidity environment and the porous layer 220 adsorbs (absorbs) moisture, the air in the voids is replaced with water, so that the refractive index of the porous layer 220 increases. When the layer 221 is a layer having a small porosity such as a thin-film deposition film, the refractive index of the layer 221 hardly changes even if moisture is absorbed, so that the difference in the refractive index between the porous layer 220 and the layer 221 is based on the porous layer 220. It is smaller than the difference in refractive index from the material 10. Then, the intensity balance between the reflected light R ₁ and the reflected light R ₂ is lost, and the reflected light cannot be sufficiently reduced due to interference.

Therefore, the layer 221 is a porous layer 221'adjusted to be at an intermediate level between the porosity of the porous layer 220 and the porosity of the base material 10, and the porous layer 221'is also absorbed moisture to absorb moisture. It was found that a new problem arises when trying to reduce the difference in refractive index due to the above.

When the porous layer 220 is formed on the porous layer 221'after the porous layer 221'is formed, a dense region having a small porosity is formed at the interface between the porous layer 221'and the porous layer 220, and the moisture content is reduced. The movement is blocked. Therefore, the water adsorbed by the porous layer 220 cannot move to the porous layer 221'and stays in the porous layer 220. If only the refractive index of the porous layer 220 that adsorbs water increases and the refractive index of the porous layer 221'does not change, the reflected light at each interface is for the same reason as in the case where the layer 221'is a vapor deposition film. The intensity balance of the light is lost, and the reflected light cannot be sufficiently reduced.

The dense regions formed at the interface between the porous layer 221'and the porous layer 220 are particles on the surface of the coating liquid where drying first begins when the coating liquid is dried when forming the porous layer 221'. It is thought that this is due to the dense aggregation of the particles. Therefore, in the present invention, as shown in FIG. 1 (b), a first region is located between the first region 21 corresponding to the porous layer 221'and the third region 23 corresponding to the porous layer 220. A second region 22 including the particles 24 and the second particles 25 is provided.

In the second region, the coating liquid for forming the first region 21 is applied to the base material, and the coating liquid for forming the third region 23 is applied before the coating liquid dries. It can be formed by applying. Since the second region 22 contains both the first particle 24 and the second particle 25, the porosity is between the porosity of the first region 21 and the porosity of the third region, which is a dense region. Can be suppressed from being formed. A coating liquid for forming the first region 21 is applied to the base material, and a coating liquid containing the first particles and the second particles is applied before the coating liquid dries. The second region may be formed by applying a coating liquid for forming the third region 23 before drying.

If there is no dense region between the first region 21 and the third region 23 that hinders the movement of water, the water adsorbed on the third region 23 will pass through the second region 22 to the first region. Move to 21. The refractive index of the first region 21 and the second region 22 also increases due to water adsorption, as in the third region 23. As a result, even when the porous layer 20 adsorbs moisture, the difference in the refractive index between the first region 21 and the third region 23 and the difference in the refractive index between the third region 23 and the base material 10 are about the same. Therefore, the intensity of the light reflected at each interface is about the same, so that the antireflection performance can be maintained.

From the viewpoint of anti-fog and anti-reflection, the porosity of the first region is preferably 10% or more and 30% or less, and the porosity of the third region is preferably 40% or more and 60% or less. Here, the porosity means the ratio of the total area of the voids included in the region in an arbitrary region in the cross section of the porous layer.

The porosity can be calculated by the following method. First, the porous layer 20 is sliced at an arbitrary position along the film thickness direction, and an observation image by a scanning transmission electron microscope (STEM) is acquired. Image processing is performed on the acquired image using image Pro PLUS (manufactured by Media Cybernetics), and the void portion and the non-void portion are binarized to calculate the total area of the void portion in each region. Then, the ratio of the area occupied by the voids in each region of the porous layer is calculated and used as the porosity. The porosity is preferably calculated for a region of 150 nm × 150 nm or more including each region in the cross section of the porous layer 20.

FIG. 1B shows a case where the first particle 24 is a spherical particle and the second particle 25 is a chain-shaped particle, and the average porosity of the third region is the average of the first region. If it can be larger than the porosity, it is not limited to this. For example, the first particle 24 and the second particle 25 may both be spherical particles, and the particle diameter of the second particle 25 may be larger than that of the first particle 24. For the first particle 24, it is preferable to select a shape and a particle diameter so that the number of pores formed between the particles is smaller than that of the second particle 25.

The first particle 24 and the second particle 25 can be used alone or in combination by appropriately selecting from various shapes such as spherical, chain, disk, elliptical, rod, needle, and square, respectively. Spherical or chain-like is particularly preferable because it has excellent film-forming properties and can increase the porosity while obtaining sufficient film hardness. Further, a plurality of types of particles having different shapes may be mixed and used.

A chain-shaped particle is an aggregate of particles in which a plurality of particles are connected in a chain shape (also referred to as a bead shape) in a straight line or while bending. The shape of the particles forming the chain-like particles may be in a state where individual particles can be clearly observed, or they may be fused with each other and lose their shape, and even if they become a film, the chain-like structure is maintained. Will be done. Therefore, it is possible to widen the voids between the particles as compared with the case where particles having other shapes are used, and it is possible to form a porous layer having a large pore volume.

When spherical, disc-shaped, or elliptical particles are used for the first particle 24 or the second particle 25, the average particle diameter thereof is preferably 5 nm or more and 100 nm or less. When the average particle size is 5 nm or more, cracks tend to be less likely to occur because the compressive stress at the time of film formation can be released. When the average particle size is 100 nm or less, light scattering due to the size of the particles is unlikely to occur, and a highly transparent film can be easily obtained. A more preferable average particle size is 10 nm or more and 60 nm or less.

When chain-shaped, rod-shaped, or needle-shaped particles are used for the first particle 24 or the second particle 25, the average minor axis is preferably 5 nm or more and 40 nm or less, and more preferably 8 nm or more and 30 nm or less. preferable. When the average minor axis is 5 nm or more and 40 nm or less, reliability deterioration and scattering due to uptake of moisture and chemical substances in the atmosphere are less likely to occur. The major axis / minor axis ratio is preferably 3 or more and 12 or less, and more preferably 4 or more and 10 or less. When the major axis / minor axis ratio is in this range, it becomes easy to increase the pore volume, and at the same time, it becomes easy to suppress light scattering and obtain high transparency.

Here, the average particle diameter of the particles is the average ferret diameter. This average ferret diameter can be measured by image processing as observed by a transmission electron microscope image. As the image processing method, a commercially available image processing such as image Pro PLUS (manufactured by Media Cybernetics) can be used. In a predetermined image region, if necessary, contrast adjustment is performed, the average ferret diameter of each particle is measured by particle measurement, and the average value can be calculated and obtained.

The first particle 24 and the second particle 25 may be particles of a single metal oxide containing silicon oxide or zirconium oxide as main components, respectively, and some of the elements may be Al, Ti, Zn, or the like. It may be replaced with another element such as Zr or B, or an organic group may be bonded. Particles containing silicon oxide as a main component are particularly preferable in that the refractive index of the porous layer 20 is lowered and the chemical stability is excellent.

In order to increase the strength (scratch resistance) of the porous layer 20, it is preferable to bond the particles to each other. Examples of the method of binding the particles to each other include a method of physically binding the particles using a binder and a method of treating the surface of the particles to chemically bond the particles to each other. As the binder, either an organic binder or an inorganic binder can be used, but a chemically stable inorganic binder is preferable, and a silicon oxide compound is particularly preferable. A preferred example of a silicon oxide compound is a silicon oxide oligomer obtained by hydrolyzing and condensing a silicic acid ester.

The average pore diameter of the pores contained in the porous layer 20 is preferably a value obtained by measuring the pore distribution by the nitrogen gas adsorption method of 3 nm or more and 50 nm or less. When the average pore diameter is 3 nm or more, air and moisture are smoothly transferred in the porous layer 20, and it is possible to exhibit sufficient anti-fog performance. When the average pore diameter is 50 nm or less, there are few pores having a pore diameter of more than 100 nm, which causes light scattering, so that high transparency can be realized. A more preferable pore diameter is 5 nm or more and 20 nm or less.

The amount of voids contained in the porous layer 20 can be determined as the pore volume by the nitrogen gas adsorption method. The pore volume is preferably 0.1 cm3 / g or more and 1.0 cm3 / g or less. When the pore volume is 0.1 cm 3 / g or more, the porous layer 20 can retain a sufficient amount of water to obtain anti-fog property. When the pore volume is 1.0 cm3 / g or less, sufficient scratch resistance can be obtained without reducing the hardness of the skeleton. A more preferable pore volume is 0.3 cm3 / g or more and 0.6 cm3 / g or less.

Of the porous layer 20, the third region 23 exposed to the external environment mainly plays a role of adsorbing water, and therefore has a void capable of adsorbing the amount of water required according to the application. Is desired. Therefore, the thickness of the third region 23 may be set according to the required anti-fog performance. The thicker the third region, the higher the anti-fog performance. However, when the porous layer 30 is formed from an inorganic material, cracking due to stress occurs if the film thickness becomes too thick, so that it is 0.2 μm or more and 2 μm or less. Thickness is preferred. More preferably, it is 0.2 μm or more and 1.5 μm or less.

The thickness of each of the first region 21 and the second region 22 may be determined according to the optical design. The first region 21 may be an integral multiple of λ / 4 of the wavelength λ to be reduced, but is preferably 50 nm or more and 150 nm or less. Within this range, the reflection of the wavelength λ of visible light can be reduced under the interference condition.

The physical thickness of each region can be measured from an image obtained by thinning the laminated film on the optical member with an electron beam processing device so that the cross section is exposed and using a scanning transmission electron microscope (STEM). can.

(Surface antireflection layer)
In order to further enhance the antireflection effect of the member, as shown in FIG. 3, it is also preferable to provide a surface antireflection layer 30 on the porous layer 20 to reduce the reflection generated at the interface between the air and the porous layer 20. ..

The surface antireflection layer 30 has antireflection performance that suppresses reflection at the light input / exit interface of the member, and moisture permeability that enables the movement of moisture between the outside and the porous layer 20. The surface antireflection layer 30 is a laminated body of a plurality of layers having different refractive indexes from each other, and a high refractive index layer, a medium refractive index layer, and a low refractive index layer are appropriately combined according to the optical design. In order to reduce the difference in refractive index between the surface antireflection layer 30 and air and suppress reflection, a low refractive index layer is provided on the outermost surface of the surface antireflection layer 30. The surface antireflection layer 30 is preferably formed by a vapor deposition method.

In the present invention, a layer having a refractive index of 1.8 or more is referred to as a high refractive index layer, a layer having a refractive index of 1.4 or more and less than 1.8 is referred to as a medium refractive index layer, and a layer having a refractive index of less than 1.4 is referred to as a low refractive index layer. In the present invention, "transparency" refers to a state in which the transmittance of visible light is 70% or more, and indicates a value (nd) at the sodium _d line (wavelength 589.3 nm) as the refractive index.

The low refractive index layer includes silicon oxide (SiO ₂ , nd = _1.46 ), magnesium fluoride (MgF ₂ , nd = _1.38 ), calcium fluoride (CaF ₂ , nd = _1.43 ). A film containing an inorganic material such as the above can be used.

For the medium refractive index layer, a film containing an inorganic material such as aluminum oxide (Al ₂ O ₃ , nd = _1.77 ), silicon oxide, and calcium fluoride can be used.

Zirconium oxide (ZrO ₂ , nd = _2.13 ), titanium oxide (TiO ₂ , nd = _2.52 to 2.72), and tantalum oxide (Ta ₂ O ₅ , _nd =) are used for the high refractive index layer. 2.17), films containing inorganic materials such as niobium oxide (Nb ₂ O ₅ , nd = _2.32 ) and hafnium oxide (Hf ₂ O ₅ , nd = _1.91 ). The high refractive index layer may contain two types selected from these metal oxides, or may be mixed with other metal oxides to adjust the refractive index.

The thickness of each layer contained in the antireflection layer 30 is preferably 10 nm or more and 200 nm or less. By setting the thickness of each layer within this range, it is possible to reduce the reflection of visible light in a wide wavelength range. In order to suppress the reflectance in a wide wavelength range, the number of layers is preferably 2 or more, and more preferably 3 or more.

Since the surface antireflection layer 30 has moisture permeability, moisture can be transferred between the outside and the porous layer 20, and the moisture is retained in the porous layer 20 or retained in the porous layer 20 depending on the humidity. It is possible to repeatedly exert anti-fog properties by releasing the generated moisture to the outside air. In order to give the surface antireflection layer 30 moisture permeability, it is preferable to form each layer so as to include pores. The layer having pores in the film can be formed by appropriately adjusting the vapor deposition conditions such as the introduction pressure of the film-forming gas at the time of vapor deposition, the temperature of the substrate, and the angle of the vapor-deposited substance flying to the substrate. Of these, non-heated vapor deposition or orthorhombic vapor deposition, in which vapor deposition is performed without heating, is preferable.

The index of refraction of a film depends on the composition and density of the film. For example, the refractive index nd of magnesium fluoride ( _{MgF 2} ) in the true density state is _1.38 , but when 30% of pores are present in the film, nd is reduced to 1.27. do. This is because the presence of air with _nd = 1.0 in the pores in the membrane lowers the refractive index of the membrane as a whole. As described above, in the case of a layer having the same composition, the denser the film, the higher the refractive index, and the lower the density, the lower the refractive index. Then, by forming each layer constituting the antireflection layer as a film having a low density including pores, it is possible to make a film through which moisture easily permeates.

In order not to fog the member, it is necessary to keep the relative humidity near the surface of the member 100% or less. Since the amount of water retained in the porous layer 20 is finite, it is desired that the porous layer 20 starts absorbing moisture at a relative humidity as close to 100% as possible.

Moisture near the surface of the member passes through the surface antireflection layer 30 and is adsorbed on the porous layer 20. For example, when the pores of the surface antireflection layer 30 are made smaller than the pores of the porous layer 20, it is higher when the moisture moves in the surface antireflection layer 30 in order to move in the porous layer 20. Pressure is required. That is, in order for water to diffuse into the porous layer 20 through the surface antireflection layer 30, the relative pressure (relative humidity) of water must be higher than that of the porous layer 20 alone. By laminating the surface antireflection layer 30 having a smaller void than the porous layer 20 on the porous layer 20 in this way, the adsorption of water starts at a higher relative humidity than the porous layer 20 alone. , The anti-fog property can be further improved.

Further, assuming that the adsorption of water to the voids follows the Kelvin equation, the humidity at the time when the condensation of water progresses in the porous medium and the adsorption starts, moves to the high humidity side as the voids become larger. Since the voids contained in the surface antireflection layer 30 are sufficiently smaller than the voids contained in the porous layer 20, the surface antireflection layer 30 starts to adsorb moisture even in a low humidity environment where adsorption does not start in the porous layer 20. .. For example, when the contact angle of the surface antireflection layer 30 with water is 10 degrees and the pore diameter is 3 nm, it is expected that the adsorption of water starts from a relative humidity of 50%.

As described above, the surface antireflection layer 30 starts adsorbing water in a lower humidity environment than the porous layer 20, and as the humidity becomes higher, the water adsorbed on the surface antireflection layer 30 becomes the porous layer 20. Moving. As a result, the optical member according to the present invention can exhibit anti-fog performance in a wide humidity range.

Since the surface antireflection layer 30 according to the present invention has a small amount of water that can be retained by itself, the refractive index does not change significantly even if water is adsorbed. Therefore, it is possible to exhibit antireflection performance even in a high humidity environment.

(Background antireflection layer)
In order to further enhance the antireflection effect, as shown in FIG. 4, a base antireflection layer 40 is provided between the porous layer 20 and the base material 10, and is generated at the interface between the porous layer 20 and the base material 10. A configuration that reduces reflection is also preferable.

The base antireflection layer 40 includes a single film having a refractive index between the porous layer 20 and the base material 10, a high refractive index layer, a medium refractive index layer, a low refractive index layer, and the like, which have different refractive indexes from each other. It is preferable to provide a laminated body in which a plurality of layers are combined. By utilizing the interference in the background antireflection layer 40, it is possible to reduce the reflection not only in the wavelength λ but also in a wider wavelength range. For each of the high refractive index layer, the medium refractive index layer, and the low refractive index layer, the film exemplified for the surface antireflection layer can be used. The base antireflection layer 40 can be formed by a vacuum film forming method such as a thin film deposition method or a sputtering method, or a wet film forming method using a sol-gel liquid or a dispersion liquid of particles.

A configuration including the surface antireflection layer 30 in addition to the base antireflection layer 40 is also preferable because the antireflection effect is enhanced.

(Manufacturing method of parts)
Hereinafter, a method for manufacturing the member of FIG. 4 will be described.

The method for manufacturing a member 100 according to the present invention includes a step of forming a porous layer 20 on a base material 10.

A wet film forming method is used in the step of forming the porous layer 20. When the porous layer 20 is formed by the wet method, a coating liquid containing a metal oxide precursor and metal oxide particles synthesized by a sol-gel method or the like is formed on a substrate to form a coating film from 15 ° C. to 200 ° C. It can be formed by drying at ° C. The coating liquid containing a metal oxide precursor and metal oxide particles is not limited, and a coating liquid containing polymer particles may be used.

The solvent that can be used in the coating liquid for forming the porous layer 20 may be any solvent as long as the raw material is uniformly dissolved and the reactant does not precipitate. For example, water can be used. In addition, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methylpropanol, 1-pentanol, 2-pentanol, cyclopentanol, 2-methylbutanol, 3-methylbutanol. , 1-hexanol, 2-hexanol, 3-hexanol, 4-methyl-2-pentanol, 2-methyl-1-pentanol, 2-ethylbutanol, 2,4-dimethyl-3-pentanol, 3-ethyl Monohydric alcohols such as butanol, 1-heptanol, 2-heptanol, 1-octanol, 2-octanol. Divalent or higher alcohols such as ethylene glycol and triethylene glycol can be used. In addition, ether alcohols such as methoxyethanol, ethoxyethanol, propoxyethanol, isopropoxyethanol, butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, dimethoxyethane, Ethers such as diglyme, tetrahydrofuran, dioxane, diisopropyl ether, dibutyl ether and cyclopentylmethyl ether can be used. Also, esters such as ethyl formate, ethyl acetate, n-butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, and propylene glycol monomethyl ether acetate. Various ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone can be used. Further, an aprotic polar solvent such as N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, or ethylene carbonate can be used. It is also possible to mix and use two or more kinds of solvents selected from these.

The porous layer 20 is formed for the purpose of improving the wettability between the coating liquid and the coated surface, increasing the thickness uniformity of the layer, and improving the adhesion between the porous layer 20 and the coated surface. Additives can be added to the coating liquid for this purpose. Examples of the additive include a surfactant, a leveling agent, an adhesion accelerator, an acid catalyst and the like, and the amount of the additive is preferably 2 parts by weight or less with respect to the solid component forming the porous layer 20.

As a method for forming the porous layer 20 by using a coating liquid containing a metal oxide precursor and metal oxide particles, a spin coating method, a spray method, a blade coating method, a roll coating method, a slit coating method, and printing are performed. Examples include the method and the dip coat method. When manufacturing a member having a three-dimensionally complicated shape such as a concave surface, the spin coating method or the spray method is suitable from the viewpoint of the uniformity of the film thickness.

In the first region 21, the second region 22, and the third region 23, the surface of the coating film dries after the coating liquid containing the first particles 24 is applied to form a coating film. It can be formed by previously applying a coating solution containing the second particles 25. The time from applying the coating liquid containing the first particles 24 to forming the coating film to applying the coating liquid containing the second particles 25 depends on the type and temperature of the solvent and the second region. Although it depends on the thickness and the like, it is preferably within 2 minutes, more preferably within 1 minute.

The thickness and porosity of the first region 21 and the third region 23 can be controlled by controlling the content and viscosity of the individual component of the coating liquid forming each region and the coating conditions. The thickness and porosity of the second region 22 can be controlled by the drying conditions after the coating liquid containing the first particles 24 is applied. For example, if the drying time is short, the second region 22 becomes thick, and if it is long, the second region 22 becomes thin.

Further, between the application of the coating liquid for forming the first region 21 and the application of the coating liquid for forming the third region 23, the coating containing the first particles and the second particles is included. The second region 22 may be formed by adding a step of applying the working liquid. The coating liquid containing the first particles and the second particles and the coating liquid for forming the third region 23 are applied before the surface of the film composed of the coating liquid previously applied is dried. In this case, the thickness of the second region can be adjusted by the thickness of the coating film of the coating liquid containing the first particles 24 and the second particles 25.

After the coating liquid containing the first particles 24 and the coating liquid containing the second particles 25 are applied onto the substrate 10, drying and / or curing is performed. Drying and curing are performed to remove the solvent and to promote the reaction of the binder itself or the reaction between the binder and the particles. From the viewpoint of suppressing the influence of the residual solvent and the generation of cracks in the layer, the drying and / or curing temperature is preferably 15 ° C. or higher and 200 ° C. or lower, and more preferably 60 ° C. or higher and 150 ° C. or lower. The drying and / or curing time is preferably 5 minutes or more and 24 hours or less, and more preferably 15 minutes or more and 5 hours or less.

As described above, silicon oxide particles are preferably dispersed in the coating liquid used for forming the porous layer 20 because it is easy to manufacture and has relatively high stability. Hereinafter, a case where the coating liquid for forming the porous layer 20 is formed by using a liquid in which silicon oxide particles are dispersed will be described in detail. The following describes both the coating liquid containing the first particle 24 and the coating liquid containing the second particle 25.

The coating liquid used for forming the porous layer 20 can be adjusted by mixing a liquid in which silicon oxide particles are dispersed, a binder solution containing a binder component, a solvent, and the like.

The liquid in which the silicon oxide particles are dispersed can be adjusted by a method of adding water or a solvent to a dispersion liquid of spherical or chain-shaped silicon oxide particles prepared by a wet method such as a hydrothermal synthesis method to dilute the liquid. Alternatively, a method of substituting the solvent of the dispersion liquid of silicon oxide particles prepared by a wet method with a desired solvent by distillation or ultrafiltration, or an ultrasonic or bead mill for silicon oxide particles synthesized by a dry method such as fumed silica. It can be prepared by a method of dispersing in water or a solvent with a method such as. When chain-shaped silicon oxide particles are used, particles having a shape such as a perfect circle, an ellipse, a disk, a rod, a needle, or a square may be appropriately mixed and used in addition to the chain. The ratio at which particles having a shape other than the chain shape can be mixed with the entire particles can be appropriately determined in consideration of the refractive index of the substrate and the film to be laminated.

A silicon oxide compound is preferable as the binder added to bond the silicon oxide particles to each other. A preferred example of a silicon oxide compound is a silicon oxide oligomer obtained by hydrolyzing and condensing a silicic acid ester.

The amount of the silicon oxide compound added to the coating liquid is preferably 1% by mass or more and 30% by mass or less, and more preferably 4% by mass or more and 20% by mass or less with respect to the silicon oxide particles from the viewpoint of scratch resistance and antifogging property. preferable.

There are several possible methods for adding the silicon oxide oligomer to the dispersion of silicon oxide particles. For example, a method of mixing a silicon oxide oligomer solution prepared in advance in water or a solvent with a dispersion of silicon oxide particles, or a method of mixing a raw material of a silicon oxide oligomer with a dispersion of silicon oxide particles and then converting the solution into a silicon oxide oligomer. Be done.

The silicon oxide oligomer can be prepared by adding water, an acid or a base to a silicate ester such as methyl silicate or ethyl silicate and hydrolyzing and condensing it in a solvent or a dispersion. As the acid to be added to the siliceous ester, hydrochloric acid, nitric acid, methanesulfonic acid, trifluoroacetic acid, trifluoromethanesulfonic acid, phosphoric acid, p-toluenesulfonic acid and the like can be used. The base may be selected from ammonia and various amines in consideration of solubility in a solvent and reactivity of a silicic acid ester. When preparing the binder solution, it is also possible to heat it at a temperature of 80 ° C. or lower.

The weight average molecular weight of the silicon oxide condensate contained in the binder solution is preferably 500 or more and 3000 or less in terms of polystyrene. When the weight average molecular weight is less than 500, cracks are likely to occur after curing, and the stability as a coating liquid is lowered. Further, when the weight average molecular weight exceeds 3000, the viscosity increases and the voids inside the binder tend to be non-uniform, so that large voids are likely to occur.

When the silicon oxide particles are chemically bonded to each other, a method of binding the silicon oxide particles to each other via a silanol group having enhanced activity can be used. Specific examples thereof include a method of treating the surface of the silicon oxide particles with a strong acid and the like, and a method of adhering a silanol group to the surface of the silicon oxide particles.

The solvent that can be used for the dispersion liquid of the silicon oxide particles may be any solvent as long as the raw material is uniformly dissolved and the reactant does not precipitate. The above-mentioned monohydric alcohols, divalent or higher alcohols, ether alcohols, ethers, esters, ketones, aprotonic polar solvents and the like can be used. In addition, various aliphatic or aliphatic hydrocarbons such as n-hexane, n-octane, cyclohexane, cyclopentane, cyclooctane, and various aromatic hydrocarbons such as toluene, xylene, and ethylbenzene. Alternatively, various chlorinated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, tetrachloroethane can also be used. Further, two or more kinds of solvents selected from these can be mixed and used.

[Second Embodiment]
Depending on the application, such as when a member provided with the surface antireflection layer 30 is incorporated into an apparatus and used, the metal oxide film of the surface antireflection layer 30 is exposed to the atmosphere, and siloxane-based organic substances adhere to the surface of the layer and come into contact with water. The corners may be high. When the contact angle of water on the surface of the surface antireflection layer 30 becomes high, water droplets are formed on the surface of the member when the amount of water exceeding the amount of water that can be retained by the member is present on the surface, which causes fogging.

Therefore, in this embodiment, as shown in FIG. 5, a hydrophilic polymer layer 50 is provided on the surface of the member in contact with air (the surface of the antireflection layer 40) to suppress an increase in the contact angle of the member surface with water.

(Hydrophilic polymer layer)
The hydrophilic polymer layer 50 can be used without particular limitation as long as it is a compound containing a hydrophilic functional group, but a polymer having a hydrophilic group of an amphoteric ion is particularly preferable. Due to the presence of the hydrophilic groups of zwitterions, the hydrophilicity of the surface is further increased and the electrical resistance is lowered, so that the contaminants are less likely to be charged and adhered. As a result, it becomes possible to maintain high hydrophilicity for a long period of time. Due to the presence of the hydrophilic polymer layer on the surface of the optical member, the water that could not be retained by the optical member does not become water droplets on the surface of the optical member but becomes a water film, so that the occurrence of fogging can be suppressed.

As the amphoteric ion hydrophilic group, any one selected from the group of sulfobetaine group, carbobetaine group, phosphorcholine group, sulfone group, phosphonate group and carboxylic acid anhydride can be preferably used. Further, the organic skeleton of the polymer having a hydrophilic group of zwitterions is not particularly limited.

In order to enhance the adhesion between the hydrophilic polymer layer 50 and the surface antireflection layer 30, it is preferable to select the chemical composition of the surface antireflection layer 30 in contact with the hydrophilic polymer layer 50. For example, in order to react with the silanol group of the silane coupling agent contained in the solution for forming the hydrophilic polymer layer 50, it is preferable to use silicon oxide on the surface of the surface antireflection layer 30 for forming the hydrophilic layer. ..

Generally, in order to improve the antireflection performance of the multilayer film, it is preferable to lower the refractive index of the layer in contact with air. However, the compound used for forming the hydrophilic polymer layer 50 is generally a silane coupling agent or a hydrophilic polymer, and many compounds have a refractive index of more than 1.4. Therefore, in order to suppress the adhesion of siloxane-based organic substances to the surface and maintain hydrophilicity without affecting the antireflection performance of the surface antireflection layer 30, the layer thickness of the hydrophilic polymer layer 50 is 1 nm or more. It is preferably 20 nm or less.

With such a thick hydrophilic polymer layer, by designing the refractive index and film thickness of each antireflection layer, it is possible to realize high antireflection performance even if the hydrophilic layer is formed. ..

The layer thickness of the hydrophilic polymer layer can be measured by the following method using an X-ray photoelectron spectrometer. The surface of the member is irradiated with an X-ray beam, and the concentration of the element derived from the hydrophilic polymer is measured from the intensity of the detected photoelectron peak. The element derived from the hydrophilic polymer can be measured, for example, using sulfur if the hydrophilic group of the hydrophilic polymer is a sulfobetaine group, phosphorus if it is a phosphorcholine group, or nitrogen if it is a carbobetaine group. Subsequently, an arbitrary predetermined region on the surface of the member is etched with an ion beam for a certain period of time, and then the etched region is irradiated with an X-ray beam to measure the element concentration derived from the hydrophilic polymer. The element concentration derived from the hydrophilic polymer is measured and the etching set is repeated a plurality of times, and the groove depth D from the surface is physically measured. From the number of etchings and the groove depth D, the layer thickness at which the hydrophilic polymer layer 50 is etched can be calculated in one etching step.

Under the etching conditions for which the layer thickness to be etched in one etching step is calculated, etching and hydrophilicity are performed until the element derived from the hydrophilic polymer cannot be detected in the hydrophilic polymer layer 50 formed on the surface of the optical element. Repeatedly measure the element concentration derived from the sex polymer. In the present invention, the layer thickness of the hydrophilic polymer layer 50 is obtained by multiplying the number of etchings at the time when the detection intensity of the element derived from the hydrophilic polymer disappears by the layer thickness etched in one etching step.

The hydrophilic polymer layer 50 is a solution containing a compound containing a hydrophilic functional group, which is subjected to a spin coating method, a blade coating method, a roll coating method, a slit coating method, a printing method, a dip coating method, or the like to prevent reflection. It can be fed on top of the layer and cured to form.

As the compound containing a functional group having hydrophilicity, a polymer having a hydrophilic group of zwitterion is particularly preferable. As a preferable main chain structure of the hydrophilic polymer, an acrylic resin, a methacrylic resin, a polyurethane resin, a polyimide resin, a polyamide resin, an epoxy resin, a polystyrene resin, a polyester resin, or the like can be used. ..

Solvents for hydrophilic polymer solutions include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol and propylene glycol, ketones such as acetone and methyl ethyl ketone, ethers such as diethyl ether and tetrahydrofuran, benzene and toluene. A hydrophilic polymer to be used from among aromatic hydrocarbon compounds such as xylene, aliphatic hydrocarbon compounds such as n-hexane, alicyclic hydrocarbon compounds such as cyclohexane, and acetate esters such as methyl acetate and ethyl acetate. It is preferable to select and use a solvent having high compatibility with the above.

[Third Embodiment]
FIG. 6 is an example of a preferred embodiment of the image pickup apparatus according to the present invention, and shows a configuration of a single-lens reflex digital camera to which a lens barrel (interchangeable lens), which is an example of the optical device of the present invention, is coupled. ..

The optical device of the present invention refers to a device including an optical system including a member according to the present invention in which a porous layer is formed on a transparent base material such as binoculars, a microscope, a semiconductor exposure device, and an interchangeable lens. Alternatively, it refers to a device that generates an image by light passing through the member of the present invention.

Further, the image pickup apparatus of the present invention refers to an electronic device including a camera system such as a digital still camera or a digital video camera, or an image pickup element that receives light that has passed through a member of the present invention such as a mobile phone. In some cases, a modular form mounted on an electronic device, for example, a camera module may be used as an image pickup device.

In FIG. 6, the camera body 320 and the lens barrel 310, which is an optical device, are coupled, and the lens barrel 310 is a so-called interchangeable lens that can be attached to and detached from the camera body 320.

The light from the subject passes through an optical system including a plurality of lenses 312 and 313 arranged on the optical axis of the photographing optical system in the housing 311 of the lens barrel 310, and is received by the image pickup element. The member according to the present invention is preferably used for, for example, the lens 312 in the housing, which is most prone to fogging, but may be used for any of the lenses constituting the optical system.

Here, the lens 313 is supported by the inner cylinder 314, and is movably supported with respect to the outer cylinder of the lens barrel 311 for focusing and zooming.

During the observation period before shooting, the light from the subject is reflected by the main mirror 322 in the housing 321 of the camera body, passes through the prism 323, and then the shot image is projected to the photographer through the finder lens 324. The main mirror 322 is, for example, a half mirror, and the light transmitted through the main mirror is reflected by the sub mirror 325 in the direction of the AF (autofocus) unit 326, and the reflected light is used for distance measurement, for example. Further, the main mirror 322 is attached to and supported by the main mirror holder 327 by adhesion or the like. At the time of photographing, the main mirror 322 and the sub mirror 325 are moved out of the optical path via a drive mechanism (not shown), the shutter 328 is opened, and the image pickup element 329 is formed with an image of the captured light incident from the lens barrel 310. Further, the aperture 315 is configured so that the brightness and the depth of focus at the time of shooting can be changed by changing the aperture area.

As shown in FIG. 6, by using the member according to the present invention, it is possible to suppress the occurrence of fogging in the optical system due to changes in the external environment, and a clear image can be obtained.

Hereinafter, examples and comparative examples according to the present invention will be described. However, the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

(1) Preparation of Silicon Oxide Particle Dispersion 1 for Forming First Region of Porous Layer 1-methoxy-2-propanol (hereinafter, PGME) dispersion of spherical silicon oxide particles (Nissan Chemical Industry Co., Ltd.) PGM-ST, average particle size 12 nm, solid content concentration 30% by mass,) 1-ethoxy-2-propanol of spherical silicon oxide particles with a solid content concentration of 5.5% by mass by adding 1-ethoxy-2-propanol to 370 g. -Propanol dispersion 2018.2 g was prepared.

In a separate container, slowly add 54 g of 0.01 mol / l dilute hydrochloric acid to a solution of 62.6 g of ethyl silicate and 36.8 g of 1-ethoxy-2-propanol, and stir at room temperature for 90 minutes, then 1 at 40 ° C. After heating for a period of time, a silicon oxide oligomer solution having a solid content concentration of 11.8% by mass was prepared.

To the obtained 1-ethoxy-2-propanol dispersion of spherical silicon oxide particles, 94.1 g of a silicon oxide binder solution was slowly added, and then the mixture was stirred at room temperature for 2 hours to prepare a silicon oxide particle coating solution 1.

By measuring the particle size distribution of the coating liquid by a dynamic light scattering method (Zetasizer Nano ZS manufactured by Malvern), it was confirmed that spherical silicon oxide particles having an average particle diameter of 15 nm were dispersed.

(2) Preparation of Silicon Oxide Particle Dispersion 2 for Forming the Third Region of the Porous Layer 2-Propanol (IPA) Dispersion of Chain Silicon Oxide Particles (IPA-ST- manufactured by Nissan Chemical Industry Co., Ltd.) IPA was distilled off while adding 1-propanol-2-propanol to 500 g (UP, average particle size 12 nm, solid content concentration 15% by mass), and 1-chain silicon oxide particles having a solid content concentration of 17.3% by mass were distilled off. 433.3 g of propoxy-2-propanol dispersion was prepared.
In a separate container, 54 g of 0.01 mol / l dilute hydrochloric acid was slowly added to a solution of 62.6 g of ethyl silicate and 36.8 g of 1-propanol-2 propanol, and the mixture was stirred at room temperature for 90 minutes. Then, the mixture was heated at 40 ° C. for 1 hour to prepare a silicon oxide oligomer solution having a solid content concentration of 11.8% by mass.

After slowly adding 25.4 g of the silicon oxide oligomer solution to the 1-propanol dispersion of the chain silicon oxide particles, the mixture was stirred at room temperature for 2 hours to prepare a silicon oxide particle coating solution 2.

By measuring the particle size distribution of the coating liquid by a dynamic light scattering method (Zetasizer Nano ZS manufactured by Malvern), it was confirmed that chain silicon oxide particles having a single diameter of 11 nm and a major diameter of 77 nm were dispersed.

(3) Measurement of film thickness and vacancies After coating a carbon film and Pt-Pd film on the antireflection layer formed on the substrate, it is sliced in an electron beam processing device (FIB-SEM; Nova600 manufactured by FEI) and scanned. Observation with a scanning electron microscope (STEM; Hitachi S-5500) was carried out. The film thickness of each layer was measured from the obtained secondary electron images. The presence or absence of the second region is obtained by binarizing the obtained secondary electron image, and the porosity is changed by calculating the area occupied by the pores from the substrate side to the surface side. Can be determined by finding.

(4) Measurement of refractive index The change in the polarization state of the incident light and the reflected light was measured with a spectral ellipsometer in the wavelength range of 380 nm to 800 nm, and the refractive index was calculated. _Nd is shown as a representative value of the refractive index. The film thickness measured in (3) was used to calculate the refractive index.

(5) Anti-fog property evaluation Using an anti-fog property evaluation device (AFA-2 manufactured by Kyowa Interface Science Co., Ltd.), the transparent substrate held at 25 ° C. is cooled to 15 ° C. to create an atmosphere of 70% RH at 25 ° C. It was left to stand, and a transmission image was recorded every second for up to 300 seconds. The compression anti-fog index was analyzed from the transmission image, and the time-varying plot of the compression anti-fog index was plotted.

From the obtained plot, the time until the compressed anti-fog index started to decrease from the initial value was read, and the anti-fog property was evaluated according to the following criteria. The longer it takes for the compression anti-fog index to start to decrease from the initial value, the better the anti-fog property. A 40 mm square, 3 mm thick flat glass (S- _BSL7 manufactured by OHARA Corporation, nd = 1.52) on which no porous layer is formed begins to become cloudy in 68 seconds.

(6) Reflectance evaluation Absolute reflectance with a wavelength of 380 nm to 780 nm is measured using a reflectance measuring device (USPM-RU manufactured by Olympus Co., Ltd.), and the average value (average reflectance) of the reflectance with a wavelength of 400 to 700 nm is obtained. The judgment was made according to the following criteria. The smaller the average reflectance before and after water absorption, the better the reflection performance.

(Example 1)
An appropriate amount of silicon oxide particle dispersion 1 is dropped onto a 40 mm square, 3 mm thick flat glass (S- _BSL7 manufactured by O'Hara Co., Ltd., nd = 1.52) and spin-coated at 4000 rpm for 12 seconds to form a coating film. Formed. Then, before the coating film composed of the silicon oxide particle dispersion liquid 1 was dried, an appropriate amount of the silicon oxide particle dispersion liquid 2 was subsequently dropped and spin-coated at 1500 rpm for 30 seconds to form a coating film. Then, it was heated at 140 ° C. for 30 minutes using a hot air circulation oven to cure the coating film, thereby producing a member having a porous layer.

(Example 2)
An appropriate amount of the silicon oxide particle dispersion 1 was added dropwise, and a member having a porous layer was obtained in the same manner as in Example 1 except that spin coating was performed at 4000 rpm for 16 seconds.

(Example 3)
A member having a porous layer was produced in the same manner as in Example 1 except that the coating liquid for forming the porous layer was applied by the following procedure.

An appropriate amount of the silicon oxide particle dispersion 1 was added dropwise, and spin coating was performed at 5000 rpm for 20 seconds. Subsequently, an appropriate amount of a liquid obtained by mixing a silicon oxide particle dispersion 1 and a silicon oxide particle dispersion 2 at a ratio of 10: 1 was added dropwise, spin-coated at 5000 rpm for 10 seconds, and an appropriate amount of silicon oxide particle dispersion 2 was added dropwise at 1500 rpm for 30 seconds. Spin coated.

(Example 4)
After forming the porous layer, a surface antireflection layer composed of a combination of a layer containing silicon oxide, a layer containing titanium oxide, and a layer containing magnesium fluoride is formed based on a design considering antireflection performance. A member was obtained by forming a porous layer in the same manner as in Example 1 except for the above.

When forming the surface antireflection layer, the temperature of the base material, the ultimate vacuum pressure, and the pressure at the time of forming each layer were adjusted so that a desired refractive index could be obtained. For film formation of each layer, silicon oxide pellets (SiO2E model manufactured by Canon Optron Co., Ltd.), pellets containing titanium oxide (manufactured by Nichia Corporation), and magnesium fluoride pellets (manufactured by Rare Metals Co., Ltd.) MgF ₂ ) was used. Table 1 shows the refractive index and the film thickness of each of the surface antireflection layers.

(Comparative Example 1)
Magnesium fluoride is deposited as a base film on a 40 mm square, 3 mm thick flat glass (S- _BSL7 manufactured by O'Hara Co., Ltd., nd = 1.52) by a vapor deposition method, and then a silicon oxide particle dispersion liquid is formed. An appropriate amount of 2 was added dropwise and spin-coated at 1500 rpm for 30 seconds. Then, it was heated at 140 ° C. for 30 minutes using a hot air circulation oven and cured to prepare a member having a porous layer. The magnesium fluoride undercoat is a layer provided to reduce the difference in refractive index between the base material and the porous layer to reduce reflection.

(Comparative Example 2)
A member having the porous layer was produced in the same manner as in Comparative Example 1 except that the surface antireflection film was subsequently formed after the porous layer was formed. The surface antireflection film was a thin-film vapor deposition film having multiple layers shown in Table 1, as in Example 4.

(Evaluation of Examples 1 to 3 and Comparative Examples 1 and 2)
Table 2 shows the configurations and evaluation results of the members produced in Examples 1 to 4, and Table 3 summarizes the configurations and evaluation results of the members produced in Comparative Examples 1 and 2.

In the anti-fog evaluation, the members produced in Comparative Examples 1 and 2 were fogged at 102 [sec], whereas the members of Examples 1 to 4 were not fogged at less than 110 [sec] and were prevented from fogging. It was confirmed that it was excellent in cloudiness. It can be seen that the glass base material has anti-fog property because it causes fogging in 68 seconds in the anti-fog property evaluation.

From the results of Examples 1 to 3 and Comparative Example 1, the configuration of Comparative Example 1 in which the base layer is provided for antireflection is the average reflectance due to water absorption as compared with the configuration of Examples 1 to 3 according to the present invention. It turns out that becomes high. The reflection characteristics measured before and after water absorption for each of the members of Example 1 and Comparative Example 1 are shown in FIGS. 7 and 8. The average reflectance difference before and after water absorption in Example 1 was 1.53%, the average reflectance difference before and after water absorption in Comparative Example 1 was 1.65%, and Example 1 was superior in antireflection characteristics. rice field.

Both the members of Example 4 and Comparative Example 2 have a surface antireflection layer formed on the porous layer. In each case, it was confirmed that the antireflection characteristics are enhanced by combining with the antireflection layer. However, although the average reflectance before water absorption was the same in Example 4 and Comparative Example 2, there was a large difference in the average refractive index after water absorption, and Example 4 was superior in antireflection characteristics. It was confirmed that. The average reflectance difference before and after water absorption in Example 4 was 0.73%, and the average reflectance difference before and after water absorption in Comparative Example 2 was 1.03%.

From the above results, it was confirmed that the member according to the present invention is excellent in anti-fog property and anti-reflection property before and after moisture absorption.

The member of the present invention can be used for general purposes such as window glass, mirrors, lenses, transparent shields, and transparent films. Further, it can be used as an optical component such as an optical lens of an imaging system or a projection system, an optical mirror, an optical filter, an eyepiece, a flat surface cover or a dome cover for an outdoor camera or a surveillance camera.

100 member 10 base material 20 porous layer 21 first region 22 second region 23 third region 24 first particle 25 second particle 30 surface antireflection layer 40 base antireflection layer 50 hydrophilic polymer layer 310 Lens lens barrel 320 Camera body 312, 313 Lens 328 Shutter 329 Image pickup element

Claims (23)

A member having a porous layer on a base material,
The porous layer has a first region, a second region, and a third region in order from the substrate side.
The first region is the first particle, the third region is the second particle having a shape different from that of the first particle, and the second region is the first particle and the second particle. Includes each,
The average porosity of the second region is larger than the average porosity of the first region.
A member characterized in that the average porosity of the third region is larger than the average porosity of the second region. The member according to claim 1, wherein the porosity of the first region is 10% or more and 30% or less, and the porosity of the third region is 40% or more and 60% or less. The member according to claim 1 or 2, wherein the thickness of the third region is 0.2 μm or more and 2 μm or less. The member according to any one of claims 1 to 3, wherein the thickness of the first region is 50 nm or more and 150 nm or less. The member according to any one of claims 1 to 4, wherein the average pore diameter of the pores contained in the porous layer is 3 nm or more and 50 nm or less. The member according to any one of claims 1 to 5, wherein the pore volume of the pores contained in the porous layer is 0.1 cm ³ / g or more and 1.0 cm ³ / g or less. The member according to any one of claims 1 to 6, wherein the first particle is a spherical silicon oxide particle, and the second particle is a chain-shaped silicon oxide particle. The member according to claim 7, wherein the spherical silicon oxide particles have an average particle diameter of 5 nm or more and 100 nm or less, and the chain-shaped silicon oxide particles have an average minor diameter of 5 nm or more and 40 nm or less. One of claims 1 to 8, wherein a laminate of a plurality of layers having different refractive indexes is provided between the surface of the porous layer and / or between the porous layer and the substrate. The member described in. The laminated body is selected from a low refractive index layer having a refractive index of less than 1.4, a medium refractive index layer having a refractive index of 1.4 or more and less than 1.8, and a high refractive index layer having a refractive index of 1.8 or more. The optical member according to claim 9, wherein the optical member includes at least two types of layers. The optical member according to any one of claims 1 to 10, wherein the member has a hydrophilic polymer layer on a surface in contact with air. The optical member according to claim 11, wherein the hydrophilic polymer layer is a polymer having a hydrophilic group of zwitterions. The twelfth claim is characterized in that the hydrophilic group of the amphoteric ion is any one selected from the group of sulfobetaine group, carbobetaine group, phosphorcholine group, sulfone group, phosphonate group and carboxylic acid anhydride. The optical member described. The optical member according to any one of claims 11 to 13, wherein the hydrophilic polymer layer has a thickness of 1 nm or more and 20 nm or less. An optical device having a housing and an optical system composed of a plurality of lenses in the housing.
An optical device, wherein the lens is the member according to any one of claims 1 to 14. An image pickup device including a housing, an optical system composed of a plurality of lenses in the housing, and an image pickup element that receives light that has passed through the optical system.
The image pickup apparatus, wherein the lens is the member according to any one of claims 1 to 14. A method for manufacturing a member having a porous layer on a base material.
A step of supplying a first coating liquid containing the first particles onto the substrate to form a first coating film, and a step of forming the first coating film.
A step of supplying a second coating liquid containing the second particles having a shape different from that of the first particles onto the substrate to form the second coating film.
Including
A method for manufacturing a member, wherein the second coating film is formed after the first coating film is formed and before the first coating film is dried. The method for manufacturing a member according to claim 17, wherein the first coating liquid contains spherical silicon oxide particles, and the second coating liquid contains chain-shaped silicon oxide. The method for manufacturing a member according to claim 17 or 18, wherein the first coating liquid and the second coating liquid contain a binder component. The method for manufacturing a member according to claim 19, further comprising a step of forming a laminate of a plurality of layers having different refractive indexes from each other between the base material and the porous layer by a thin-film deposition method. The member according to claim 17 to 20, which comprises a step of forming a laminated body of a plurality of layers having different refractive indexes on the surface of the porous layer by a vapor deposition method. Method. 17. The method for manufacturing the described member. 22. The method for manufacturing the described member.

Images