JP2019162866A - Transparent member, imaging device and manufacturing method of transparent member - Google Patents

Abstract

To provide a transparent member with a hydrophilic film having a high reliability formed thereon, capable of maintaining a hydrophilic property for a long period of time even in storage at product packaging and in exposure to an outdoor environment.SOLUTION: A transparent member 10 includes a substrate 16, a porous layer 14, and a hydrophilic polymer layer 15 in this order. The transparent member 10 is characterized in that: the porous layer 14 includes a silica particle 11 and a binder 12; and the hydrophilic polymer layer 15 includes a polymer containing an amphoteric ion hydrophilic group and has a thickness of 1 nm or more and 20 nm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydrophilic transparent member and an imaging device using the same as a protective cover.

  In recent years, surveillance cameras have been installed in various places such as stores, hotels, banks, and stations for the purpose of crime prevention. The surveillance camera is installed by a method such as attaching to a ceiling, an outer wall, a support column or the like via an installation component, or embedding.

  The surveillance camera body is provided with a transparent protective cover that does not interfere with imaging in order to protect it from the surrounding environment. For the protective cover, a resin material such as polycarbonate or acrylic having excellent transparency and impact resistance is used. In the case of a surveillance camera installed outdoors, if water drops such as rain or condensation adhere to the protective cover, the image may be distorted or blurred, so a hydrophilic film is provided on the protective cover to prevent water drops from sticking. Technology is widely used.

  Patent Document 1 discloses a technique in which a hydrophilic film including a porous film including metal oxide particles and a hydrophilic polymer film formed on the porous film is provided on a base material. . Further, Patent Document 2 proposes a hydrophilic film in which silica and zwitterionic polymer are unevenly distributed on the film surface by applying and curing a coating agent composed of a polymerizable monomer, an initiator, silica and a zwitterionic polymer. ing. It is described that a film having high hydrophilic performance and mechanical strength can be obtained by segregating silica and zwitterionic polymer on the surface layer of the polymer film.

International Publication No. 2006/011605 JP 2017-61598 A

  Generally, the camera body and the protective cover of a surveillance camera are stored and shipped in the same package. While being stored in the same package, siloxane-based contaminants contained in the degassing of the camera body, especially rubber parts, adhere to the hydrophilic film surface of the protective cover, making it hydrophilic. There is a problem of deteriorating. FIG. 4 shows the relationship between the amount of siloxane on the film surface and the contact angle. It can be seen that as the amount of siloxane adhering to the film surface increases, the contact angle increases and the hydrophilicity cannot be maintained.

  In addition, after the surveillance camera is installed outdoors, the hydrophilic film may be altered or decomposed by being exposed to sunlight or rain for a long time, or hydrophobic organic pollutants floating outdoors may be adsorbed. There is also a problem that the hydrophilicity deteriorates by doing so.

  Therefore, the protective cover is required to exhibit hydrophilicity over a long period of time from when the product is unpacked and installed outdoors.

  As a countermeasure against hydrophilic deterioration during packaging and storage, it is conceivable to provide a protective cover for protecting the surface until immediately before installation. However, in addition to the cost increase, in the case of a protective cover having a hemispherical curved surface, the labor and cost for providing the protective cover are further increased.

  Therefore, it is preferable that the hydrophilic film provided on the protective cover can maintain hydrophilicity in both the packing storage environment and the outdoor environment. However, in the configuration of Patent Document 1, siloxane-based contaminants adhere to the hydrophilic polymer on the surface during packaging storage, and the hydrophilicity at the time of installation in an outdoor environment cannot be guaranteed. In addition, the hydrophilic films proposed in Patent Documents 1 and 2 maintain hydrophilicity for a long period of time because the polymer on the surface of the film that develops hydrophilicity is altered and decomposed by sunlight and rain in the outdoor environment. Can not do it.

  This invention is made | formed in view of the said subject, and provides the transparent member which has a hydrophilic coating film which can maintain hydrophilicity over a long period of time in both a packing storage environment and an outdoor environment.

  The transparent member according to the present invention is a transparent member comprising a base, a porous layer, and a hydrophilic polymer layer in this order, and the porous layer includes silica particles and a binder, and the hydrophilic The polymer layer includes a polymer having a zwitterionic hydrophilic group and has a layer thickness of 1 nm or more and 20 nm or less.

  An imaging apparatus according to the present invention is an imaging apparatus including an optical system and an image sensor that acquires an image through the optical system in a space surrounded by a casing and a transparent member. The transparent member includes a porous layer and a hydrophilic polymer layer in this order on the outer surface, and the porous layer includes silica particles and a binder, and the hydrophilic polymer layer includes an amphoteric ion. It includes a polymer having a hydrophilic group, and has a layer thickness of 1 nm or more and 20 nm or less.

  Moreover, the manufacturing method of the transparent member concerning this invention is a manufacturing method of the transparent member provided with a base material, a porous layer, and a hydrophilic polymer layer in this order, Comprising: A silica particle and a binder on a base material A step of applying a dispersion containing the components and curing to form a porous layer; and applying and curing a solution containing a polymer having zwitterionic hydrophilic groups on the porous layer, and having a thickness of 1 nm to 20 nm Forming a hydrophilic polymer layer having a layer thickness of.

  ADVANTAGE OF THE INVENTION According to this invention, the transparent member which formed the highly reliable hydrophilic film which can maintain hydrophilic property for a long period of time also at the time of product packaging storage and the outdoor environment exposure can be provided.

It is a schematic diagram which shows the cross section of the thickness direction of one Embodiment of the transparent member of this invention. It is a mimetic diagram showing one embodiment of an imaging device of the present invention. It is a schematic diagram which shows the structural example of the imaging device of this invention. It is a figure which shows the relationship between the amount of siloxane of a film | membrane surface, and a contact angle.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments, and can be appropriately modified without departing from the gist of the present invention.

≪Transparent material≫
FIG. 1 is a schematic view showing a cross section in the thickness direction (normal direction relative to the surface of a substrate), which is an embodiment of a transparent member according to the present invention. In the figure, the transparent member 10 of the present invention has a porous layer 14 and a hydrophilic polymer layer 15 in this order on a substrate 16. In the present invention, “transparent” means a characteristic having a transmittance for visible light of 50% or more.

  The porous layer 14 includes a plurality of silica particles (silicon oxide particles) 12 and a binder 11 interposed between the plurality of silica particles 12. The plurality of silica particles 12 are fixed to each other by a binder 11 and are porous by voids 13 formed between the silica particles 12 or between the binders 11. The void 13 communicates three-dimensionally from the surface of the porous layer 14.

With such a configuration, the transparent member according to the present invention maintains hydrophilicity with the hydrophilic polymer layer 15 at the time of installation in the packaging storage environment and in the outdoor environment, and the usage period after installation in the outdoor environment is The porous layer 14 can maintain hydrophilicity.
Hereinafter, each layer will be described in detail.

<Hydrophilic polymer layer>
The hydrophilic polymer layer 15 is a film for ensuring the hydrophilicity of the surface of the transparent member at the time of packaging and when installed outdoors.

  In order to prevent siloxane-based contaminants from adhering to the hydrophilic surface of the transparent member in the packaging environment, the hydrophilic polymer layer 15 includes a polymer having zwitterionic hydrophilic groups. Due to the presence of the zwitterionic hydrophilic group, the hydrophilicity of the surface is further increased and the electrical resistance is lowered, so that contaminants are less likely to be charged and adhered. As a result, high hydrophilicity can be maintained during long-term storage.

  As the zwitterionic hydrophilic group, a sulfobetaine group, a carbobetaine group, or a phosphorcholine group can be suitably used.

  The hydrophilic polymer layer 15 exhibits hydrophilicity when installed outdoors, but is decomposed by sunlight and rain while exposed to the outdoor environment, and the hydrophilicity deteriorates. If the hydrophilic polymer layer 15 is thick, water droplets adhere to the surface due to the deterioration of hydrophilicity, and a clear image cannot be obtained through the transparent member.

  Therefore, in the present invention, the hydrophilic polymer layer 15 is formed thin so as to be decomposed in a short time in an outdoor environment. Since the porous layer 14 made of silica particles has high hydrophilicity and excellent self-cleaning performance, the decomposed hydrophilic polymer is removed from the surface of the porous layer 14. Therefore, in the transparent member set outdoors, the porous layer made of silica particles is finally exposed on the surface, and the hydrophilicity is maintained.

  The layer thickness of the hydrophilic polymer layer 15 is preferably 1 nm or more and 20 nm or less. When the layer thickness is smaller than 1 nm, the layer is formed in an island shape, and thus the siloxane-based contaminant cannot be sufficiently prevented from adsorbing to the surface. If the layer thickness of the hydrophilic polymer layer 15 is larger than 20 nm, it takes time until the porous layer made of silica particles is exposed in an outdoor environment, and during that time, the zwitterionic hydrophilic group is decomposed and the hydrophilic polymer layer is decomposed. The surface of 15 is hydrophobized and cannot maintain hydrophilicity. In addition, the layer thickness of the hydrophilic polymer layer 15 here is the thickness of the portion formed on the air side with respect to the outermost surface particles constituting the porous layer. A specific measurement method will be described later.

  The polymer forming the hydrophilic polymer layer 15 is not particularly limited, but a material that is easily decomposed in an outdoor environment is preferable, and an acrylic polymer having low light resistance is particularly preferable.

<Porous layer>
The porous layer 14 has a structure in which the silica particles 12 are fixed by a binder, and voids are included between the silica particles 12. The porosity of the porous layer 14 is preferably 40% or more and 55% or less. When the porosity of the porous layer 14 is 40% or more, hydrophobic organic contaminants drifting outdoors in an outdoor exposure environment can be sufficiently taken into the porous interior, and the hydrophilicity of the surface can be maintained. If the porosity of the porous layer 14 is 55% or less, the haze of the hydrophilic film is small and high transparency can be obtained. Furthermore, in order to maintain the hydrophilicity over a long period of time, the layer thickness d is preferably 200 nm or more and 2000 nm or less in order to ensure the capacity of the voids for taking in organic contaminants.

  Here, the porosity v is a value representing the ratio of the volume of the voids included in the porous layer 14 to the porous layer 14. A method for evaluating the porosity will be described later.

[Silica particles]
The average particle diameter of the silica particles 12 is preferably 10 nm or more and 60 nm or less. When the average particle size of the silica particles 12 is smaller than 10 nm, it is difficult to achieve a desired porosity because the voids formed between the particles are too small, and hydrophobic organic contaminants floating outdoors are placed inside the porous body. There is a tendency that it cannot be fully captured. If most of the organic contaminants adhere to the surface, they become hydrophobic, making it difficult to maintain hydrophilicity in the outdoor environment. Moreover, when the average particle diameter of the silica particles 12 exceeds 60 nm, the size of the voids 13 formed between the particles increases, and scattering due to the voids 13 and the silica particles 12 tends to occur.

  Here, the average particle diameter of the silica particles 12 is an average ferret diameter. The average ferret diameter can be measured by performing image processing on an observation image acquired from a transmission electron microscope image. As the image processing method, commercially available image processing such as image Pro PLUS (manufactured by Media Cybernetics) can be used. In a predetermined image area, after adjusting the contrast appropriately as necessary, the average ferret diameter of each particle can be measured by using commercially available particle measurement software to obtain the average value.

  Solid silica particles or hollow silica particles can be used as the silica particles 12, but chain silica particles are particularly preferable in that the porosity can be increased without generating large voids. You may mix and use a chain-like silica particle, a solid silica particle, and a hollow silica particle.

  The silica particles 12 contain SiO2 as a main component, but may further contain metal oxides such as Al2O3, TiO2, ZnO2, and ZrO2 in the particles. However, if 30% or more of the silanol (Si—OH) groups on the surface of the silica particles 12 are modified with an organic group or the like or complexed with another metal, the hydrophilicity is lost. The porous layer 14 made of such silica particles has low hydrophilicity, and the self-cleaning property is also lowered.

  Therefore, in order to express good hydrophilicity in the porous layer 14, it is preferable to use silica particles in which silanol (Si—OH) groups remain in 70% or more of the particle surface, and 90% or more of the particle surface. It is more preferable to use silica particles in which silanol groups remain.

[binder]
The binder 13 can be appropriately selected depending on the wear resistance, adhesion, and environmental reliability of the film, but has high affinity with the silica particles 12 and can improve the wear resistance of the porous layer. A silica (SiO2) binder is preferred. Among the silica binders, a silicate hydrolysis condensate is particularly preferable.

  2 mass% or more and 30 mass% or less are preferable with respect to the porous layer 14, and, as for content of the binder 11, 3 mass% or more and 20 mass% or less are more preferable. If the content of the binder 11 is 2% by mass or more and 30% by mass or less, the silica particles 12 can be fixed so as not to be peeled off, and it is necessary to sufficiently incorporate organic contaminants into the porous interior. A high porosity can be realized.

<Base material>
As a material of the base material 16, a transparent acrylic resin, a polycarbonate resin, a resin such as a polyester resin, glass, or the like can be used. The shape of the base material 16 is not limited and may be a plate shape or a film shape, and may be a flat plate shape or a shape having a curved surface, a concave surface or a convex surface, for example, a hemispherical dome. It may be a shape or the like.

<Manufacturing method>
Next, an example of the method for producing a transparent member according to the present invention will be described.

  The method for producing a transparent member of the present invention includes (i) a step of forming a porous layer on a substrate, and (ii) a step of forming a hydrophilic polymer layer in this order. Hereinafter, each process will be described.

(I) Step of forming porous layer The step of forming porous layer 14 may use either a dry method or a wet method, but it is preferable to use a wet method that can easily create porous layer 14. .

  As the dry method, the porous layer 14 is formed by using a vapor deposition method or a sputtering method, and forming the film by increasing the pressure in the vacuum furnace or by forming the film with the incident angle inclined from the vertical direction of the substrate. be able to.

  As the wet method, a method of applying / drying a dispersion of silica particles 12 and a binder solution in order, or a method of applying / drying a dispersion containing both silica particles 12 and a binder component can be used. A method of applying a dispersion liquid containing both silica particles and a binder component is preferable in that the composition inside the porous layer 14 becomes uniform.

  The dispersion of the silica particles 12 is a solution in which the silica particles 12 are dispersed in a solvent, and the content of the silica particles 12 is preferably 2% by mass or more and 10% by mass or less. In order to improve the dispersibility of the silica particles 12, a silane coupling agent or a surfactant may be added to the dispersion of the silica particles 12. However, when these compounds react with most of the silanol groups on the surface of the silica particles 12, the bond between the silica particles 12 and the binder 11 is weakened, and the wear resistance of the porous layer 14 is reduced. The hydrophilicity of the layer 14 tends to decrease. Therefore, 10 mass parts or less are preferable with respect to 100 mass parts of silica particles, and, as for additives, such as a silane coupling agent and surfactant, 5 mass parts or less are more preferable.

  As the binder solution, it is preferable to use a silica binder solution having a strong binding force with the silica particles 12. The silica binder solution is mainly composed of a silicate hydrolysis condensate produced by adding water, an acid or a base to a silicate ester such as methyl silicate or ethyl silicate in a solvent and hydrolyzing and condensing the solution. It is preferable.

  What acid or base is used may be appropriately selected in consideration of solubility in a solvent and reactivity with a silicate ester. The acid used for the hydrolysis reaction is preferably hydrochloric acid or nitric acid, and the base is preferably ammonia or various amines. The silica binder solution can also be prepared by neutralizing and condensing a silicate such as sodium silicate in water and then diluting with a solvent. Acids that can be used for the neutralization reaction are hydrochloric acid, nitric acid and the like. When preparing the binder solution, it is possible to heat at a temperature of 80 ° C. or lower.

  When a silica binder is used as the binder 11, a trifunctional silane alkoxide substituted with an organic group such as methyltriethoxysilane or ethyltriethoxysilane can be added for the purpose of improving solubility and coating properties. The addition amount of the trifunctional silane alkoxide is preferably 10 mol% or less of the entire silane alkoxide. When the addition amount exceeds 10 mol%, the organic group inhibits hydrogen bonding between silanol groups inside the binder, and the wear resistance tends to decrease.

  When using a dispersion containing both silica particles 12 and a binder component, the dispersion of silica particles 12 and the binder solution described above may be prepared in advance and then mixed. Or you may prepare a dispersion liquid by the method of adding the component of the binder 11 to the dispersion liquid of the silica particle 12, and making it react. When a dispersion containing silica particles 12 and a silica binder component is obtained using the latter method, the dispersion can be prepared by adding ethyl silicate, water, and an acid catalyst to the dispersion of silica particles 12 and reacting them. is there. A method in which a binder solution is prepared in advance and then mixed is preferable in that the reaction of the binder component can be controlled and the reaction can be performed while confirming the reaction state.

  The amount of the binder in the dispersion containing the silica particles 12 and the silica binder component is preferably 5 parts by mass or more and 35 parts by mass or less, and more preferably 10 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the silica particles.

  The solvent that can be used in the silica particle dispersion or the silica binder solution may be any solvent in which the raw materials are uniformly dissolved or dispersed and the reactant is not precipitated. For example, 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-ethylbutanol Monohydric alcohols such as 1-heptanol, 2-heptanol, 1-octanol and 2-octanol; dihydric or higher alcohols such as ethylene glycol and triethylene glycol; methoxyethanol, ethoxyethanol, propoxyethanol, isopropoxy Etano , Butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ether alcohols such as 1-propoxy-2-propanol, dimethoxyethane, diglyme, tetrahydrofuran, dioxane, diisopropyl ether, dibutyl ether, cyclopentyl Ethers such as methyl ether; 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, propylene glycol monomethyl ether acetate; n- Various aliphatic or alicyclic types such as hexane, n-octane, cyclohexane, cyclopentane, cyclooctane Hydrogen fluorides; various aromatic hydrocarbons such as toluene, xylene, ethylbenzene; various ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone; chloroform, methylene chloride, carbon tetrachloride, tetrachloroethane And various kinds of chlorinated hydrocarbons such as N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, and an aprotic polar solvent such as ethylene carbonate. Two or more kinds of solvents selected from these exemplified solvents can also be mixed and used.

  Examples of the method for applying the dispersion of silica particles 12 and the solution of the silica binder component or a mixture thereof include spin coating, blade coating, roll coating, slit coating, printing, and dip coating. It is done. When manufacturing a transparent member having a three-dimensionally complicated shape such as a concave surface, the spin coating method is preferable from the viewpoint of film thickness uniformity.

  After applying a dispersion of silica particles and a solution of silica binder, or a mixture thereof, a drying and curing process is provided to improve the abrasion resistance by suppressing the amount of solvent remaining in the porous layer. The porous layer 14 is preferably formed. The drying and curing steps are steps for accelerating the removal of the solvent, the reaction of the silica binder component, or the reaction between the silica binder component and the silica particles 12. The temperature in the drying and curing step is preferably 20 ° C. or higher and 200 ° C. or lower, and more preferably 60 ° C. or higher and 150 ° C. or lower. If the temperature of the drying and curing step is 20 ° C. or higher and lower than 200 ° C., the solvent remains and the wear resistance does not decrease, the curing of the binder 11 proceeds excessively, and the binder 11, that is, the porous layer 14, Cracks are not likely to occur.

  The solvent remaining in the porous layer is preferably 3.0 mg / cm 3 or less.

  In the case where the dispersion of silica particles 12 and the silica binder solution are sequentially applied, the dispersion of silica particles 12 is applied and the firing process is performed once, and then the silica binder solution is applied and the drying and curing processes are performed. The porous layer 14 can also be formed.

  In order to make the porous layer 14 have a desired film thickness, the above-described coating process and drying and curing processes may be alternately repeated a plurality of times.

(Ii) Step of forming hydrophilic polymer layer The step of forming the hydrophilic polymer layer 15 on the porous layer 14 includes a spin coating method, a blade coating method, a roll coating method, a slit coating, and a solution containing the hydrophilic polymer. It is a process of applying and curing by a method such as a printing method, a printing method or a dip coating method.

  As a preferable main chain structure possessed by 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 of the hydrophilic polymer solution 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, and aromatics such as benzene, toluene and xylene. High compatibility with hydrophilic polymers to be used among aliphatic hydrocarbon compounds, aliphatic hydrocarbon compounds such as n-hexane, alicyclic hydrocarbon compounds such as cyclohexane, and acetates such as methyl acetate and ethyl acetate It is preferable to select and use a solvent.

≪Imaging device≫
2A and 2B are schematic diagrams showing an embodiment of the imaging apparatus of the present invention. FIG. 2A is a fixed point observation type surveillance camera, and FIG. 2B is a swivel type capable of pan / tilt / zoom drive. Is a surveillance camera. The imaging apparatus shown in FIG. 2 has a transparent member 10 according to the present invention that functions as a protective cover in the apparatus main body 30, and the apparatus main body 30 includes an optical system that acquires video data. In addition, the transparent member (protective cover) 10 covers at least the optical system of the apparatus main body 30 and protects against dust and impact from the outside. The protective cover 2 in FIG. 2A has a flat box shape, and the protective cover 2 in FIG. 2B has a hemispherical dome shape, but the shape of the protective cover is not limited thereto.

  FIG. 3 shows a configuration example of an imaging apparatus according to the present invention. The imaging device 30 has a space surrounded by the transparent member 10 and the housing 36, and includes an optical system 31, an image sensor 32, a video engine 33, a compression output circuit 34, and an output unit 35 in the space. Yes.

  An image acquired through the transparent member 10 is guided to an image sensor 32 by an optical system (lens) 31, converted into an analog video signal (electric signal) by the image sensor 32, and output. The video analog signal output from the image sensor 32 is converted into a video digital signal by the video engine 33, and the video digital signal output from the video engine 33 is compressed into a digital file by the compression output circuit 34. The video engine 33 may perform processing for adjusting image quality such as luminance, contrast, color correction, and noise removal in the process of converting the video analog signal into the video digital signal. The signal output from the compression output circuit 34 is output from the output unit 35 to an external device via wiring.

  The transparent member 10 is installed so that the surface on which the porous layer 14 and the hydrophilic polymer layer 15 are provided is on the outside. With such a configuration, while protecting against dust and impact from the outside, water droplets adhering to the surface of the transparent member 10 due to changes in the external environment are made into a liquid film, and distortion of images acquired by the image sensor 32 is suppressed. be able to.

  Further, the imaging device 30 includes a pan / tilt for adjusting the angle of view, a controller for controlling imaging conditions, a storage device for storing the acquired video data, a transfer unit for transferring the data output from the output unit 35 to the outside, and the like. An imaging system can be configured.

  Hereinafter, the specific manufacturing method of the transparent member concerning this invention is demonstrated.

(Preparation of coating solution)
First, the coating liquid used for manufacture of the transparent member concerning this invention is demonstrated.

(1) Preparation of silica particle dispersion 2-propanol (IPA) dispersion of chain silica particles (IPA-ST-UP, Nissan Chemical Industries, Ltd., average particle size 12 nm, solid content concentration 15% by mass) To 00 g, 142.50 g of 1-ethoxy-2-propanol was added. Thereafter, IPA was concentrated and removed with a rotary evaporator to prepare a silica particle dispersion A (solid content concentration 5.0 mass%).

(2) Preparation of silica binder solution 13.82 g of ethanol and nitric acid aqueous solution (concentration 3%) were added to 12.48 g of ethyl silicate and stirred at room temperature for 10 hours to obtain a silica binder solution (solid content concentration 11.5% by mass). Was prepared.

(3) Preparation of silica particle coating solution 3.26 g of the silica binder solution prepared in (2) after 50.00 g of the silica particle dispersion prepared in (1) was diluted with 65.67 g of 1-ethoxy-2-propanol. And stirred at room temperature for 10 minutes. Then, it stirred at 50 degreeC for 1 hour, and prepared the silica particle coating liquid B. Particle size distribution measurement by dynamic light scattering method (Zetasizer Nano ZS manufactured by Malvern) confirmed that chain silica particles having a single diameter of 15 nm and a long diameter of 95 nm are dispersed in the silica particle coating solution B. did. The binder content of the prepared silica particle coating solution is 13% by mass.

(4) Preparation of hydrophilic polymer coating liquid A 20 g of LAMBIC-771W (manufactured by Osaka Organic Chemical Industry Co., Ltd.), which is an aqueous solution of an acrylic polymer having a sulfobetaine group, is diluted by adding 80 g of pure water, and at room temperature for 10 minutes. Stir.

(5) Preparation of hydrophilic polymer coating liquid B To 12 ml of 2-propanol, 2.0 g (19.4 mmol) of dimethylaminoacetic anhydride and 4.2 g (17.8 mmol) of glycidoxypropyltrimethoxysilane were added. The mixture was refluxed at 60 ° C. for 4 hours, and the solvent was removed to obtain a transparent viscous liquid.

(6) Preparation of hydrophilic polymer coating liquid C 1 g of 1-methoxy-2-propanol was diluted with 1 g of KPP-05 (manufactured by Koshin Chemical Co., Ltd.), an acrylic UV curable paint having a sulfo group, and diluted. And stirred for 10 minutes at room temperature.

(7) Preparation of primer coating solution 0.1 g of 3- (2-aminoethylamino) propyltrimethoxysilane (A0774, manufactured by Tokyo Chemical Industry Co., Ltd.), which is an amino silane, was added to 1-methoxy-2-propanol (Kanto Chemical). (Special grade) 100 g was added and stirred at room temperature for 10 minutes.

(Evaluation method of transparent member)
Next, the evaluation method of the transparent member produced using the said coating liquid is demonstrated.

(8) Measurement of film thickness of porous layer Using a spectroscopic ellipsometer (VASE, manufactured by JA Woollam Japan), measurement was performed in the wavelength range of 380 nm to 800 nm to determine the film thickness of the porous layer.

(9) Measurement of porosity of porous layer Using a spectroscopic ellipsometer (VASE, manufactured by JA Woollam Japan), the wavelength was measured from 380 nm to 800 nm, and the refractive index of the porous layer was determined from the analysis. From the refractive index of the porous layer obtained by the measurement, the refractive index of silica of 1.46, and the refractive index of air of 1.00, the porosity of the porous layer was calculated using Equation 1.
(Formula 1) Porosity = 100 × (1.46-porous refractive index) / (1.00-1.46)

(10) Measurement of water contact angle Using a fully automatic contact angle meter (DM-701, manufactured by Kyowa Interface Science Co., Ltd.), the contact angle was measured when 2 μl of pure water droplets were contacted at 23 ° C. and 50% RH. . The contact angle of the transparent member immediately after production was measured and used as the initial value.

(11) Long-term storage test The produced transparent member was sealed with 10 g of silicone rubber (Shin-Etsu Chemical KE-931-U) as a siloxane-based contaminant source in an aluminum laminated bag laminated on the inside with aluminum. The aluminum laminate bag in which the sample was sealed was kept in an environment at a temperature of 60 ° C. for 300 hours with a constant temperature and humidity tester (Espec Corp. PL-2KP). The contact angle with respect to water of the transparent member after the test was measured in the same manner as in (9).

(12) Outdoor exposure test A transparent member that has not been stored for a long time was put into a xenon weather meter (Super Xenon Weather Meter CX75 manufactured by Suga Test Instruments Co., Ltd.). The light irradiation intensity was set at 180 W / m2, light irradiation and water discharge were performed for 18 minutes, and light irradiation alone was performed for 1 hour and 42 minutes as one cycle. After that, 150 cycles were added and a total of 300 cycles were tested for a total of 600 hours and evaluated again. The contact angle of the transparent member after the test was measured in the same manner as (9). In this outdoor exposure test, 100 hours is considered to correspond to one year of actual outdoor exposure.

(13) Layer thickness of hydrophilic polymer layer Using an X-ray photoelectron spectrometer (Quantera II manufactured by ULVAC-PHI Co., Ltd.), from the detection intensity under beam conditions of 100 μm, 25 W, 15 kV, derived from the hydrophilic polymer on the surface of the porous layer Elemental concentrations were measured. The element derived from the hydrophilic polymer is measured using, for example, sulfur when the hydrophilic group of the hydrophilic polymer is a sulfobetaine group or a sulfo group, phosphorus when it is a phosphorcholine group, and nitrogen when it is a carbobetaine group. Thereafter, the same analysis was repeated 40 times while etching a 2 mm × 2 mm square region for 15 seconds with an Ar ion beam having an acceleration voltage of 100 V, and the detection intensity of the element derived from the hydrophilic polymer was measured. When the depth of the groove from the surface after 40 times of etching was measured, it was confirmed that the depth was about 40 nm, and it was found that etching was performed to a depth of 1 nm in one etching process. Therefore, etching was performed a plurality of times from the surface of the hydrophilic polymer layer, and a value obtained by multiplying the number of times of etching when the detection intensity of the element derived from the hydrophilic polymer disappeared by 1 nm was defined as the layer thickness of the hydrophilic polymer layer.

(14) Evaluation If the contact angle is less than 30 °, the formation of water droplets on the surface of the transparent member can be sufficiently suppressed. Therefore, in any of the initial value, the long-term storage test, and the outdoor exposure test of 300 hours and 600 hours, if the contact angle to water is less than 30 °, only the contact angle to water after A evaluation and 600 hours of outdoor exposure test Was 30 ° or more, it was evaluated as B. If the contact angle to water in any of the initial value, long-term storage test, and 300-hour outdoor exposure test was 30 ° or more, it was rated as C.

(Example 1)
In Example 1, an appropriate amount of a primer coating solution was dropped onto a polycarbonate substrate (nd = 1.58, νd = 30.2) having a diameter (φ) of 50 mm and a thickness of 4 mm, and spin coating was performed at 1500 rpm for 30 seconds. . Then, it heated at 90 degreeC for 10 minute (s) in the hot air circulation oven, and was made to dry. By forming a layer made of the primer coating solution on the base material before forming the porous layer, the adhesion between the base material and the porous layer can be enhanced.

  Subsequently, an appropriate amount of silica particle coating solution was dropped and spin coating was performed at 2000 rpm for 20 seconds, and then a series of steps of heating at 90 ° C. for 10 minutes in a hot air circulating oven was repeated 10 times to form a porous layer. . Further, an appropriate amount of hydrophilic polymer coating solution A was dropped on the porous layer, and spin coating was performed at 3500 rpm for 30 seconds. Then, it heated at 80 degreeC for 15 minute (s) in the hot air circulation oven (drying and hardening process). Finally, it was dipped in pure water and pulled up, and then the pure water adhering to the substrate was removed from the substrate by blowing dry air to obtain a transparent member with a hydrophilic film.

(Example 2)
A transparent member with a hydrophilic coating was prepared in the same manner as in Example 1 except that the hydrophilic polymer coating solution prepared by adjusting the amount of pure water to 20 g when using the hydrophilic polymer coating solution A was used. did.

(Example 3)
A transparent member with a hydrophilic coating was prepared in the same manner as in Example 1 except that the hydrophilic polymer coating solution prepared by adjusting the amount of pure water to 300 g was used when preparing the hydrophilic polymer coating solution A. did.

Example 4
When preparing the silica particle coating solution, 1-pentanol was used as a dilution solvent for the silica particle dispersion. The number of repetitions of the heating step after spin-coating the silica coating solution was 18 times. Other processes were the same as in Example 1 to produce a transparent member with a hydrophilic film.

(Example 5)
In Example 5, methyl lactate was used as a diluent solvent for the silica particle dispersion when preparing the silica particle coating solution. A transparent member with a hydrophilic film was produced in the same manner as in Example 1 except that the number of repetitions of the heating step after applying the chain silica coating solution by spin coating was changed to 5.

(Example 6)
Example 6 was prepared in the same manner as in Example 1 except that the hydrophilic polymer coating solution B was used, and a transparent member with a hydrophilic film was prepared.

(Example 7)
A transparent member with a hydrophilic coating was prepared in the same manner as in Example 1 except that the number of repetitions of the heating step after applying the silica coating solution by the spin coating method was two.

(Comparative Example 1)
A transparent member with a hydrophilic film consisting only of a porous layer was produced without performing the steps after the step of applying the hydrophilic polymer coating solution of Example 1 by a spin coating method.

(Comparative Example 2)
When preparing the silica particle coating solution, 2-methoxyethanol was used as a dilution solvent for the silica particle dispersion. Further, LAMBIC-771W was used as the hydrophilic polymer coating solution as it was without being diluted with pure water when preparing the hydrophilic polymer coating solution A. Other than that was carried out similarly to Example 1, and produced the transparent member with a hydrophilic film.

(Comparative Example 3)
After forming a porous layer in the same manner as in Example 1, an appropriate amount of hydrophilic polymer coating liquid C was dropped on the porous layer, and spin coating was performed at 3000 rpm for 30 seconds. Then, it heated at 80 degreeC for 10 minute (s) in the hot air circulation oven (drying process). Then, using a UV irradiation device spot cure (manufactured by USHIO INC.), Irradiation was performed for 10 s at a UV intensity of 100 mW / cm ² (curing step) to produce a transparent member with a hydrophilic film.

  Table 1 shows the evaluation results for Examples 1 to 7 and Comparative Examples 1 to 3.

  As shown in Table 1, when the thickness of the hydrophilic polymer layer having a zwitterionic hydrophilic group is 1 nm or more and 20 nm or less, the contact angle with water in any of the initial, long-term storage test, and 300-hour outdoor exposure test is It was confirmed that it was less than 30 ° and hydrophilicity was maintained. Furthermore, if the thickness of the porous layer is 200 nm or more, the contact angle with water is less than 30 ° in any of the initial, long-term storage tests, and 300 hours and 600 hours of outdoor exposure tests. Was confirmed to be maintained. On the other hand, in Comparative Example 1 in which a hydrophilic polymer layer was not formed on the surface of the porous layer, the contact angle with water after a long-term storage test was 57 °, and the hydrophilicity could not be maintained. Further, in Comparative Example 2 in which the film thickness and porosity of the porous layer and the film thickness of the hydrophilic polymer are outside the scope of the present invention, the contact angle after the outdoor exposure test exceeds 30 °, and the hydrophilicity is maintained. I could not. In Comparative Example 3 where the hydrophilic group of the hydrophilic polymer was not an amphoteric ionic hydrophilic group, the contact angle with water after a long-term storage test was 35 °, and the hydrophilicity could not be maintained.

DESCRIPTION OF SYMBOLS 10 Transparent member 11 Silica particle 12 Binder 13 Void 14 Porous layer 15 Hydrophilic polymer layer 16 Base material

Claims (19)

A transparent member comprising a base material, a porous layer, and a hydrophilic polymer layer in this order,
The said porous layer contains a silica particle and a binder, The said hydrophilic polymer layer contains the polymer which has an amphoteric ion hydrophilic group, and has a layer thickness of 1 nm or more and 20 nm or less, The transparent member characterized by the above-mentioned.   The transparent member according to claim 1, wherein the zwitterionic hydrophilic group is any one of a sulfobetaine group, a carbobetaine group, and a phosphorcholine group.   The transparent member according to claim 1 or 2, wherein the porous layer has a thickness of 200 nm to 2000 nm and a porosity of 40% to 55%.   The transparent member according to any one of claims 1 to 3, wherein an average particle diameter of the silica particles is 10 nm or more and 60 nm or less.   The transparent member according to any one of claims 1 to 4, wherein the binder is a silica binder.   The transparent member according to any one of claims 1 to 5, wherein a material of the base material is any one of an acrylic resin, a polycarbonate resin, and a polyester resin. An imaging apparatus comprising an optical system and an image sensor that acquires an image via the optical system in a space surrounded by a housing and a transparent member,
The transparent member includes a porous layer and a hydrophilic polymer layer in this order on the outer side surface, and the porous layer includes silica particles and a binder,
The hydrophilic polymer layer includes a polymer having a zwitterionic hydrophilic group and has a layer thickness of 1 nm or more and 20 nm or less.   The imaging apparatus according to claim 7, wherein the zwitterionic hydrophilic group is any one of a sulfobetaine group, a carbobetaine group, and a phosphorcholine group.   The imaging device according to claim 7 or 8, wherein the porous layer has a layer thickness of 200 nm to 2000 nm and a porosity of 40% to 55%.   10. The imaging device according to claim 7, wherein an average particle diameter of the silica particles is 10 nm or more and 60 nm or less.   The imaging device according to claim 7, wherein the binder is a silica binder.   The imaging device according to claim 7, wherein the transparent member has a flat plate shape or a dome shape. A method for producing a transparent member comprising a substrate, a porous layer, and a hydrophilic polymer layer in this order,
A step of applying a dispersion containing silica particles and a binder component on a substrate and curing to form a porous layer;
Applying a solution containing a hydrophilic polymer having an amphoteric ionic hydrophilic group on the porous layer and curing to form a hydrophilic polymer layer having a layer thickness of 1 nm or more and 20 nm or less;
The manufacturing method of the transparent member characterized by having.   The method for producing a transparent member according to claim 13, wherein the zwitterionic hydrophilic group is any one of a sulfobetaine group, a carbobetaine group, and a phosphorcholine group.   15. The transparent member according to claim 13, wherein the porous layer is formed so that the layer thickness of the porous layer is 200 nm or more and 2000 nm or less, and the porosity is 40% or more and 55% or less. Production method.   The method for producing a transparent member according to any one of claims 13 to 15, wherein the silica particles are chain silica having an average particle diameter of 10 nm or more and 60 nm or less.   The method for producing a transparent member according to any one of claims 13 to 16, wherein the binder component is a silicate hydrolysis condensate.   18. The transparent member according to claim 13, wherein an amount of the binder contained in the dispersion is 5 parts by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the silica particles. Production method.   19. The method according to claim 13, further comprising a step of applying and drying a primer coating solution containing an amino-based silane on the substrate before the step of forming the porous layer. The manufacturing method of the transparent member of claim | item.

Images