Transparent article with Anti-fog film for security camera, and security camera

Abstract

To provide a transparent article with an anti-fog film suitable for a security camera.SOLUTION: The present invention provides a transparent article with an anti-fog film for a security camera, comprising a transparent substrate and an anti-fog film disposed on the surface thereof, wherein the anti-fog film comprises at least one selected from the group consisting of a silane coupling agent and a crosslinked structure derived from a silane coupling agent, a water absorbent polymer, a polyether-modified siloxane and a diol having 2-8 carbon atoms.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a transparent article with an anti-fog film for a security camera and a security camera.

Background Art

[0002] An anti-fog film may be formed on a transparent substrate typified by a glass plate in order to impart anti-fog properties. For example, Patent Document 1 discloses an anti-fog film containing a polyvinyl acetal resin which is a water-absorbing polymer and a silica component such as colloidal silica.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the study by the present inventor, the conventional anti-fog film is not suitable for maintaining the imaging function of a security camera whose demand is expanding. Therefore, an object of the present invention is to provide a transparent article with an anti-fog film suitable for use in a security camera.

Means for Solving the Problems

[0005] Hereinafter, in this specification, the description that the QR code is a registered trademark is omitted. <​​​​In a test in which the anti-fog film is immersed in 25°C water for 24 hours, removed from the water, exposed to water vapor generated from 90°C to 100°C water placed 60 mm vertically downward from the anti-fog film for 30 seconds, and the information of a QR code placed 110 mm downward in the same direction from the anti-fog film can be read using a camera from the side opposite to the side on which the anti-fog film is formed, the test determines whether the information of a QR code with a size of 40 mm square can be read. We provide transparent articles with anti-fog coatings for security cameras. Here, the QR code is a two-dimensional code that encodes the string "Rank:B" as the information, in accordance with the Japanese Industrial Standard (JIS) X 0510:2018, with a symbol size of 21x21 modules and error correction level H.

[0007] From another perspective, the present invention is It comprises a transparent substrate and an anti-fogging film on the surface of the transparent substrate, The anti-fogging film comprises a water-absorbing polymer, When the anti-fog film was immersed in 25°C water for 24 hours, removed from the water, and exposed for 30 seconds to water vapor generated from 90°C to 100°C water placed 60 mm vertically below the anti-fog film, a transparent continuous film was formed on the surface of the anti-fog film exposed to the water vapor. We provide transparent articles with anti-fog coatings for security cameras.

[0008] From another perspective, the present invention is It comprises a transparent substrate and an anti-fogging film on the surface of the transparent substrate, The anti-fogging film comprises at least one selected from the group consisting of a silane coupling agent and a crosslinked structure derived from a silane coupling agent, a water-absorbing polymer, a polyether-modified siloxane, and a diol having 2 to 8 carbon atoms. We provide transparent articles with anti-fog coatings for security cameras.

[0009] From yet another perspective, the present invention is Camera and, A transparent article with an anti-fog film for a security camera according to the present invention, disposed in front of the lens of the camera, and A security camera is provided.

Effect of the Invention

[0010] According to the present invention, a transparent article with an anti-fog film suitable for maintaining the imaging function of a security camera is provided.

Brief Description of the Drawings

[0011] [Figure 1] It is a cross-sectional view showing an example of a transparent article with an anti-fog film according to the present embodiment. 并 [Figure 2] It is a cross-sectional view showing another example of a transparent article with an anti-fog film according to the present embodiment. [Figure 3] It is a schematic diagram showing an example of a security camera according to the present embodiment. [Figure 4] It is a schematic diagram showing another example of a security camera according to the present embodiment. [Figure 5A] It is a schematic diagram for explaining the outline of high-temperature steam evaluation. [Figure 5B] It is another schematic diagram for explaining the outline of high-temperature steam evaluation. [Figure 6A] It is an example of a QR code used for high-temperature steam evaluation (size 10 mm × 10 mm, recorded information "Rank: SSS"). [Figure 6B] It is an example of a QR code used for high-temperature steam evaluation (size 15 mm × 15 mm, recorded information "Rank: SS"). [Figure 6C] It is an example of a QR code used for high-temperature steam evaluation (size 20 mm × 20 mm, recorded information "Rank: S"). [Figure 6D] It is an example of a QR code used for high-temperature steam evaluation (size 30 mm × 30 mm, recorded information "Rank: A"). [Figure 6E] It is an example of a QR code used for high-temperature steam evaluation (size 40 mm × 40 mm, recorded information "Rank: B"). 合

Best Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate, but the present invention is not limited to the following embodiments. In this specification, the "main component" means the component with the highest content rate. Also, for a plate-like article, the "main surface" means two surfaces facing opposite sides with a predetermined interval called thickness therebetween.

[0013] As disclosed in Patent Document 1, a water-absorbing polymer is often blended in an anti-fog film. As the content of the water-absorbing polymer increases, the anti-fog property of the film can be expected to improve. On the other hand, as the content of the water-absorbing polymer increases, the wear resistance of the film usually decreases. For this reason, as disclosed in Patent Document 1, an inorganic component that compensates for the decrease in wear resistance, typically a silica component such as colloidal silica, is often added to the anti-fog film. A transparent article with an anti-fog film that realizes high wear resistance as well as anti-fog property is suitable for use as an automobile window glass. In contrast, a high level of wear resistance is not required for a transparent article used with a security camera. It is appropriate to develop a transparent article with an anti-fog film for a security camera from a different perspective from that of a transparent article with an anti-fog film for an automobile.

[0014] Regarding a transparent article with an anti-fog film for a security camera, it should be emphasized that the anti-fog film does not inhibit the imaging function of the security camera even when it is exposed to a harsh environment for a long time. The transparent article with an anti-fog film according to this embodiment is obtained by further consideration from such a perspective, and can exhibit a function of transmitting light without scattering it at a high level even when the anti-fog film is exposed to a harsh environment.

[0015] Figure 1 is a cross-sectional view showing a transparent article with an anti-fog film according to this embodiment. The transparent article with an anti-fog film 1 comprises a plate-shaped transparent substrate 10, i.e., a transparent substrate, and an anti-fog film 11 formed on the surface of the transparent substrate 10. The anti-fog film 11 is formed on at least a portion of the surface of the transparent substrate 10, for example, on the main surface of the transparent substrate 10. The anti-fog film 11 may be formed on both main surfaces 10a and 10b of the plate-shaped transparent substrate 10, or, as shown in Figure 1, it may be formed on only one main surface 10a.

[0016] [Transparent base material] The transparent substrate 10 only needs to be transparent, and there are no particular restrictions on its shape or material. The transparent substrate 10 may be made of glass or resin. The transparent substrate 10 is, for example, a glass plate or a resin plate. Representative transparent substrates 10, namely glass plates and resin plates, will be described below.

[0017] (Glass plate) The glass composition constituting the glass plate is not particularly limited and may be soda-lime glass, aluminosilicate glass, borosilicate glass, alkali-free glass, or even multi-component glass such as C glass or E glass. Multi-component glass contains SiO2 as the main component and further contains at least one oxide selected from the group consisting of B2O3, Al2O3, MgO, CaO, Li2O, Na2O, and K2O. However, the glass plate may be made of silica glass.

[0018] The glass plate may be float glass. Float glass is formed by the so-called float process. In float glass, one main surface is in contact with molten tin during formation in the float tank, causing tin to diffuse onto that main surface. As a result, float glass has a surface layer on one main surface, called the bottom surface, where tin has diffused, and this surface layer is not present on the other main surface, called the top surface. From another perspective, in float glass, the tin concentration on one main surface is higher than the tin concentration on the other main surface. However, the glass plate may also be formed by a manufacturing method other than the float process, such as the overflow downdraw method.

[0019] When float glass is used as a transparent substrate, it is desirable to form the anti-fogging film on the bottom surface of the float glass. Therefore, in Figure 1, when the transparent substrate 10 is float glass, the main surface 10a may be the top surface, but it is preferably the bottom surface. The bottom surface has more hydroxyl groups than the top surface, making it suitable as the surface for forming an anti-fogging film with excellent water resistance.

[0020] The thickness of the glass plate is, for example, 0.5 to 7.0 mm, or it may be 0.5 to 5.0 mm. When impact resistance is important, the thickness of the glass plate, if it is not tempered glass, is preferably 3.5 mm or more. However, in the case of tempered glass, a thickness of 1.8 mm or more is sufficient for the glass plate to have sufficient impact resistance. Tempered glass may be air-cooled tempered glass or chemically tempered glass.

[0021] (Resin plate) The resin material constituting the resin plate is not particularly limited and includes, for example, acrylic resins such as methacrylic resin (PMMA), polycarbonate (PC), acrylonitrile / styrene resin (AS), acrylonitrile / butadiene / styrene resin (ABS), cycloolefin polymer (COP), vinyl chloride (PVC), triacetylcellulose (TAC), polyethylene terephthalate (PET), and urethane. The thickness of the resin plate is, for example, 0.5 to 7.0 mm, and may be 0.5 to 5.0 mm. When the resin is acrylic resin, the thickness of the resin plate is preferably 2.0 to 3.0 mm. When the resin is polycarbonate, the thickness of the resin plate is preferably 1.0 to 2.0 mm.

[0022] (Shape of the transparent substrate, etc.) As shown in Figure 1, the transparent substrate 10 may be a flat plate with a flat main surface. However, the main surface of the transparent substrate may be curved. For example, the transparent substrate may be a flat transparent substrate that has been bent. The transparent substrate may also be a molded body with a curved surface that is formed directly from molten material without going through a flat transparent substrate. An example of such a molded body is shown in Figure 2.

[0023] The main surfaces of the transparent substrate 20 shown in Figure 2 are both curved, with one main surface 20a being concave and the other main surface 20b being convex. An anti-fog film 21 is formed on the surface of the concave main surface 20a. Main surface 20a faces the lens of a security camera (not shown). The transparent substrate 20 has a dome shape, and the interior of the dome can be used as a space to house the lens of the security camera (see Figure 4). In other words, the transparent substrate 20 has a concave surface that faces the space to house the lens of the security camera.

[0024] An undercoat may be formed on the main surface of the transparent substrate. In this case, the undercoat will be interposed between the surface of the transparent substrate and the anti-fogging film. The undercoat is not particularly limited, but may be, for example, a barrier film that prevents the leaching of alkali metals from the glass. The barrier film may be composed of, for example, a silica film.

[0025] When an anti-fogging film is formed on only one main surface of a transparent substrate, a film other than the anti-fogging film may be formed on the other main surface. Examples of such films include anti-reflective films, water-repellent films, hydrophilic films, and colored films.

[0026] [Anti-fogging film] The film thickness of the anti-fogging films 11 and 21 is not limited to a specific value, but is 0.1 to 10 μm, preferably 0.5 to 5.0 μm, and particularly preferably 0.8 to 2.0 μm.

[0027] The anti-fogging films 11 and 21 include, for example, a silane coupling agent and / or a crosslinked structure derived from a silane coupling agent, a water-absorbing polymer, a polyether-modified siloxane, and a diol having 2 to 8 carbon atoms. Each component is described below.

[0028] (Superabsorbent polymer) Examples of superabsorbent polymers include at least one selected from the group consisting of urethane resins, epoxy resins, acrylic resins, polyvinyl acetal resins, and polyvinyl alcohol resins. Examples of urethane resins include polyurethane resins composed of polyisocyanate and polyol. Examples of polyols include acrylic polyols and polyoxyalkylene polyols. Examples of epoxy resins include glycidyl ether epoxy resins, glycidyl ester epoxy resins, glycidylamine epoxy resins, and cyclic aliphatic epoxy resins. A preferred epoxy resin is a cyclic aliphatic epoxy resin. Below, polyvinyl acetal resin (hereinafter simply referred to as "polyvinyl acetal"), which is a preferred superabsorbent polymer, will be described.

[0029] Polyvinyl acetal can be obtained by condensing polyvinyl alcohol with an aldehyde to form an acetal. The acetalization of polyvinyl alcohol can be carried out using known methods such as precipitation using an aqueous medium in the presence of an acid catalyst, or dissolution using a solvent such as alcohol. Acetalization can also be carried out in parallel with the saponification of polyvinyl acetate. The degree of acetalization is preferably 2-40 mol%, more preferably 3-30 mol%, particularly 5-20 mol%, and in some cases 5-15 mol%. The degree of acetalization can be, for example, 13 It can be measured based on 1C nuclear magnetic resonance spectroscopy. Polyvinyl acetals with an acetalization degree within the above range are suitable for forming anti-fogging films with good water absorption and water resistance.

[0030] The average degree of polymerization of polyvinyl alcohol is preferably 200 to 4500, and more preferably 500 to 4500. A high average degree of polymerization is advantageous for forming an anti-fogging film with good water absorption and water resistance, but if the average degree of polymerization is too high, the viscosity of the solution may become too high, which may hinder film formation. The degree of saponification of polyvinyl alcohol is preferably 75 to 99.8 mol%.

[0031] Examples of aldehydes to be condensed with polyvinyl alcohol include aliphatic aldehydes such as formaldehyde, acetaldehyde, butyraldehyde, hexylcarbaldehyde, octylcarbaldehyde, and decylcarbaldehyde. Other examples include benzaldehyde; 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, and other alkyl-substituted benzaldehydes; chlorobenzaldehyde and other halogen-substituted benzaldehydes; substituted benzaldehydes in which hydrogen atoms are substituted by functional groups other than alkyl groups such as hydroxyl, alkoxy, amino, and cyano groups; and aromatic aldehydes such as naphthaldehyde and anthraldehyde, which are condensed aromatic ring aldehydes. Aromatic aldehydes with strong hydrophobicity are advantageous in forming water-absorbing films with a low degree of acetalization and excellent water resistance. The use of aromatic aldehydes is also advantageous in forming highly absorbent films while retaining a large number of hydroxyl groups. It is preferable that the polyvinyl acetal contains an acetal structure derived from an aromatic aldehyde, particularly benzaldehyde.

[0032] The content of the water-absorbing polymer in the anti-fogging film is, for example, 45 to 95% by mass, preferably 55 to 85% by mass, and more preferably 65 to 80% by mass. The water-absorbing polymer may also be the main component of the anti-fogging film.

[0033] (Polyether-modified siloxane) A polyether-modified siloxane is a compound having a polyether chain as at least one selected from molecular chains bonded to the ends of the siloxane main chain and molecular chains bonded as side chains to the siloxane main chain. A siloxane is a compound with a siloxane bond (Si-O-Si) as its backbone. The constituent units of the polyether chain are not particularly limited, but examples include ethylene oxide and propylene oxide. The polyether chain may contain only one type of constituent unit, or it may contain two or more types.

[0034] Polyether-modified siloxanes may also be polyether-modified silicones. Silicones are polymers with a siloxane bond (Si-O-Si) backbone. Examples of polyether-modified silicones include BYK-345, BYK-347, and BYK-349 from Bic Chemie, and TSF-4440 from Momentive.

[0035] The content of polyether-modified siloxane in the anti-fogging film is, for example, 2 to 30% by mass, preferably 5 to 25% by mass, and more preferably 8 to 20% by mass.

[0036] (Diol) Diols having 2 to 8 carbon atoms, in other words, diols having 2 to 8 carbon atoms, may include, for example, at least one selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, and hexanediol. The diol may also be a diol having 2 to 6 carbon atoms. Preferred diols include at least one selected from the group consisting of butanediol, propylene glycol, and dipropylene glycol. The anti-fogging film may contain propylene glycol and / or dipropylene glycol as particularly preferred diols.

[0037] The content of C2-C8 diols in the anti-fogging film is, for example, 0.01-30% by mass, preferably 0.05-20% by mass, and more preferably 0.1-10% by mass.

[0038] (Silane coupling agents and crosslinked structures derived therefrom) Examples of silane coupling agents include silicon compounds having a hydrolyzable group represented by the following formula (I). Silicon compounds having a hydrolyzable group represented by formula (I) may be used alone or in combination of two or more.

[0039] RL-SiY 3-n X n (I)

[0040] In equation (I), n represents an integer between 1 and 3.

[0041] X is a hydrolyzable group or a halogen atom. Examples of hydrolyzable groups include at least one selected from alkoxy groups, acetoxy groups, alkenyloxy groups, and amino groups. Preferred alkoxy groups include alkoxy groups having 1 to 4 carbon atoms (methoxy group, ethoxy group, propoxy group, butoxy group). A preferred halogen atom is chlorine.

[0042] Y is an alkyl group having 1 to 3 carbon atoms. Preferred alkyl groups are methyl and ethyl groups.

[0043] L is a hydrocarbon group. The hydrocarbon group is preferably an alkylene group. The number of carbon atoms in the hydrocarbon group is, for example, 1 to 10, preferably 1 to 6, and more preferably 1 to 3. Preferred examples of hydrocarbon groups are methylene, ethylene, n-propylene, isopropylene, vinylene, and propenylene.

[0044] R is a substituent, or a hydrocarbon group which may have a substituent. The number of carbon atoms in this hydrocarbon group is not particularly limited, for example, 4 to 12, but may be 3 or less. The substituent may be a reactive functional group. The reactive functional group is at least one selected from the group consisting of epoxy groups, amino groups, mercapto groups, isocyanate groups, acrylic groups, and methacrylic groups, and preferably at least one selected from the group consisting of epoxy groups and amino groups. The epoxy group may be included as part of the glycidyl ether group. Silane coupling agents having an epoxy group may be described as "epoxysilane". The amino group may be a primary amino group, a secondary amino group, or a tertiary amino group, but preferably a primary amino group and a secondary amino group. Silane coupling agents having an amino group may be described as "aminosilane".

[0045] Compounds in which X in formula (I) is an alkoxyl group are called silicon alkoxides. In formula (I), n is preferably 2 or 3. That is, the silane coupling agent is preferably a bifunctional silicon alkoxide having a reactive functional group represented by RL-SiY1X2 in formula (I) or a trifunctional silicon alkoxide having a reactive functional group represented by RL-SiX3 in formula (I).

[0046] Preferred examples of difunctional silicone alkoxides having reactive functional groups are glycidoxyalkylalkyldialkoxysilanes and aminoalkylalkyldialkoxysilanes. Examples of glycidoxyalkylalkyldialkoxysilanes are 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane. Examples of aminoalkylalkyldialkoxysilanes are N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane and N-2-(aminoethyl)-3-aminopropylethyldiethoxysilane.

[0047] Preferred specific examples of trifunctional silicon alkoxides having reactive functional groups are glycidoxyalkyltrialkoxysilanes and aminoalkyltrialkoxysilanes. Examples of glycidoxyalkyltrialkoxysilanes are 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane (GPTMS), and 3-glycidoxypropyltriethoxysilane. Examples of aminoalkyltrialkoxysilanes are 3-aminopropyltrimethoxysilane (APTMS), 3-aminopropyltriethoxysilane (APTES), 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 3-(N-phenyl)aminopropyltrimethoxysilane, hydrochloride of N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltriethoxysilane.

[0048] In this embodiment, as the silane coupling agent, at least one selected from the group consisting of difunctional silicone alkoxides having reactive functional groups and trifunctional silicone alkoxides having reactive functional groups may be used, or multiple types may be used. Preferably, a trifunctional silicone alkoxide having reactive functional groups can be used as the silane coupling agent. As the trifunctional silicone alkoxide having reactive functional groups, at least one selected from the group consisting of glycidoxyalkyltrialkoxysilanes and aminoalkyltrialkoxysilanes may be used, or multiple types may be used. Preferably, 3-glycidoxypropyltrimethoxysilane (GPTMS) and 3-aminopropyltriethoxysilane (APTES) can be used as the trifunctional silicone alkoxide having reactive functional groups.

[0049] In the anti-fogging film, the silane coupling agent reacts with other components at least partially to form a cross-linked structure. Other components include organic components such as water-absorbing polymers and hydroxyl groups on the substrate surface.

[0050] A particularly preferred combination of silane coupling agents is the combined use of an epoxy group-containing silane coupling agent (epoxysilane) and an amino group-containing silane coupling agent (aminosilane). The epoxysilane and aminosilane should be added in a mass ratio of, for example, 1:3 to 3:1, and especially 1:2 to 2:1.

[0051] The content of the silane coupling agent in the anti-fogging film is, for example, 2 to 35% by mass, preferably 5 to 30% by mass, and more preferably 8 to 25% by mass.

[0052] (Other ingredients) In addition to the components mentioned above, the anti-fogging film may also contain, as appropriate, ultraviolet absorbers, infrared absorbers, leveling agents (surface modifiers), light stabilizers, etc. However, it is desirable that these components be added in an amount of 20% by mass or less, more preferably 10% by mass or less, and particularly 5% by mass or less of the anti-fogging film. Since high abrasion resistance is not required, colloidal silica and other silica fine particles may or may not be included in the anti-fogging film. The silica fine particle content in the anti-fogging film may be, for example, 10 to 60% by mass, but may be limited to less than 5% by mass, more preferably less than 3% by mass, and particularly less than 1% by mass. The content of oxide fine particles including silica fine particles may also be as described above for silica fine particles. The anti-fogging film may or may not contain oxide fine particles, represented by silica fine particles. However, even if silica fine particles are not included, the anti-fogging film may contain siloxane components contained in polyether-modified siloxanes, silane coupling agents, etc.

[0053] [Characteristics of transparent articles with anti-fog coatings] The anti-fog film according to this embodiment can transmit transmitted light without scattering at a high level, even in harsh environments for anti-fog films, such as after being in contact with water for a long period of time. To achieve this function, it is desirable that the anti-fog film has transparency, water absorption, water resistance, and hydrophilicity. Anti-fog films that do not have sufficient water resistance may have their components leached out when in contact with moisture for a long time. Furthermore, if the anti-fog film is hydrophilic enough that excess water is retained on its surface as a continuous film when its own water absorption reaches a saturation point, transmitted light can be transmitted without excessive scattering.

[0054] (Transparency / Non-diffusiveness of transmitted light) The transparent article with an anti-fog coating according to this embodiment can transmit light without excessive scattering. Specifically, the transparent article with an anti-fog coating may have a haze rate of, for example, 5% or less, moreover 3% or less, particularly 1% or less, and in some cases 0.4% or less. The haze rate is specified in JIS K 7136:2018.

[0055] (Water resistance / hydrophilic) The transparent article with an anti-fog film according to this embodiment can achieve both water resistance and hydrophilicity. These properties can be evaluated by a method called high-temperature water vapor evaluation, which is described in detail in the Examples section. In this method, high-temperature and excessive water vapor is supplied to the anti-fog film with the film facing vertically downward. When exposed to this water vapor, a transparent continuous film of water is formed on the surface of the anti-fog film, which is hydrophilic and has excellent water resistance, in the portion directly exposed to the water vapor. Whether it is a "transparent continuous film" can be determined by visually confirming that the film maintains continuity as a film rather than water droplets, and that the film is not cloudy. Cloudiness of the film can occur due to whitening of the film due to insufficient water resistance, or due to condensation on the film surface due to insufficient anti-fog properties. On the surface of a film with insufficient hydrophilicity, water is not retained as a continuous film but is dispersed and adheres as water droplets. In films with insufficient water resistance, whitening of the film can be observed upon contact with high-temperature water vapor, and elution of film components or film defects may occur. The hydrophilicity of a surface is generally evaluated by the contact angle of water. However, this evaluation method only involves dropping a very small amount of water droplets onto the film, and therefore does not adequately reproduce harsh environments. Furthermore, the transparent continuous film may cover 80% or even 90% or more of the surface of the anti-fogging film exposed to water vapor.

[0056] To evaluate the film in more detail or in a more stepwise manner, an information reading evaluation using QR codes can be performed. Details of this evaluation method will be described later in the Examples section. In this evaluation method, the transparent article with the anti-fog film according to this embodiment can exhibit good hydrophilicity to the extent that a QR code "A" with a size of preferably 30 mm square, a QR code "S" with a size of more than 20 mm square, an even more preferably QR code "SS" with a size of 15 mm square, and a particularly preferably QR code "SSS" with a size of 10 mm square can be read, even after being immersed in water at room temperature for 24 hours.

[0057] [Formation of anti-fogging film] An anti-fogging film can be formed by applying a coating solution for forming the anti-fogging film to the surface of a transparent substrate and then heating the transparent substrate coated with the coating solution. The solvent used to prepare the coating solution and the method of application can be conventionally known materials and methods. Examples of application methods include spin coating, roll coating, spray coating, dip coating, flow coating, screen printing, and brush coating. The coating film may be dried as appropriate before heating.

[0058] The heating temperature of the transparent substrate on which the coating film is formed is not particularly limited, but is, for example, 100 to 180°C, and the heating time is, for example, 5.0 minutes to 1.0 hour.

[0059] [Security camera] Figures 3 and 4 show examples of security cameras equipped with transparent articles 1 and 2 with anti-fog coatings according to this embodiment. The security cameras 51 and 52 shown in Figures 3 and 4 comprise cameras 31 and 41, housings 30 and 40 for fixing the cameras, and transparent articles 1 and 2 with anti-fog coatings. Light incident on the lenses of cameras 31 and 41 from the outside passes through the transparent articles 1 and 2 with anti-fog coatings. The anti-fog coatings are formed on the side facing cameras 31 and 41. [Examples]

[0060] The present invention will be described in more detail below with reference to examples. First, the evaluation method for transparent articles with anti-fog coatings obtained from each example or comparative example will be explained.

[0061] (Water immersion test) A transparent object with an anti-fog coating was immersed in a plastic container holding pure water at room temperature (approximately 25°C) and kept in this state for 24 hours. After that, the transparent object with the anti-fog coating was removed and allowed to dry by standing it upright in a holder. The following visual evaluation and high-temperature steam evaluation were performed on the dried sample.

[0062] • Appearance evaluation The condition of the film surface was evaluated visually to determine which of the following categories it fell into. G: No change compared to before the exam. F: Slight bleaching is observed. NG: Albinism is observed. Y: Membrane elution is observed.

[0063] • Evaluation of anti-fogging properties using high-temperature steam (high-temperature steam evaluation) As shown in Figure 5A, a transparent item 1 with an anti-fog coating was held horizontally above a stainless steel insulated cup 80 containing boiling water 70, with the surface of the anti-fog coating 11 facing the insulated cup 80. The temperature of the water 70 was maintained at 90-100°C while steam was being supplied. The distance D1 between the anti-fog coating and the water surface was 60 mm. The internal space of the insulated cup 80 was cylindrical with an opening diameter of 64 mm, and the volume of water 70 was approximately 130 cc. The transparent item 1 with the anti-fog coating was held on the insulated cup 80 for 30 seconds to supply high-temperature steam to the anti-fog coating 11. After that, as shown in Figure 5B, the insulated cup 80 was removed and replaced with a cardboard backing 95 printed with a predetermined QR code 90. The distance D2 between the anti-fog coating 11 and the cardboard backing 95 was 110 mm. In this state, the QR code 90 was photographed from above by the camera 100 through the transparent item 1 with an anti-fog coating, and it was confirmed whether the information contained in the QR code 90 could be read. The distance D3 between the transparent substrate 10 and the lens 101 of the camera 100 was set to 80 mm. The removal of the insulated cup 80, i.e., the cessation of the supply of high-temperature steam, and the photography of the QR code were carried out within 30 seconds.

[0064] Five types of QR codes, as shown in Figures 6A to 6E, were used to identify the smallest QR code from which information could be read, and that QR code was used as the evaluation result. The size of the QR codes used and the information they contained are as follows. For example, if the QR code SSS was read, the text information "Rank:SSS" would be displayed. QR code "SSS": 10mm x 10mm, information "Rank: SSS" (Figure 6A) QR code "SS": 15mm x 15mm, information "Rank: SS" (Figure 6B) QR code "S": 20mm x 20mm, information "Rank: S" (Figure 6C) QR code "A": 30mm x 30mm, information "Rank: A" (Figure 6D) QR code "B": 40mm x 40mm, Information "Rank: B" (Figure 6E)

[0065] If none of the QR codes could be read, the result was "X," and if the film dissolved or peeled off due to contact with high-temperature steam, the result was "Y."

[0066] The QR code "SSS" shown in Figure 6A was encoded as information according to the specifications of JIS X 0510:2018, with a 25x25 module symbol size and error correction level H. The QR codes "SS" to "B" shown in Figures 6B to 6E were encoded as information according to the specifications of JIS X 0510:2018, with a 21x21 module symbol size and error correction level H. Note that each string consists of half-width characters (1-byte code), not full-width characters.

[0067] The camera used was a Sony Xperia XZ2 smartphone (model name: SO-03K, OS: Android® (ver. 10)). The QR code reading function of the LINE® app (ver. 11.7.2) was used to read the QR code.

[0068] (Example 1) (Preparation of the coating solution) Polyvinyl acetal resin-containing solution (Sekisui Chemical Co., Ltd. "Eslec KX-5", solids content 8% by mass, degree of acetalization 9 mol%, containing acetal structure derived from benzaldehyde) 48.2% by mass, polyether-modified siloxane (Bic Chemie Co., Ltd. "BYK-345") 0.5% by mass, 3-aminopropyltriethoxysilane (APTES, Shin-Etsu Silicone Co., Ltd. "KBE-903") 1.0% by mass, 3- A coating solution was prepared by adding 0.7% by mass of glycidoxypropyltrimethoxysilane (GPTMS, "KBM-403" manufactured by Shin-Etsu Silicone Co., Ltd.), 20.0% by mass of propylene glycol, 18.5% by mass of purified water, 11.0% by mass of alcohol solvent ("Neoethanol P-7" manufactured by Daishin Chemical Co., Ltd.), 0.1% by mass of hydrochloric acid, and 0.01% by mass of leveling agent ("KP-341" manufactured by Shin-Etsu Silicone Co., Ltd.) to a glass container and stirring.

[0069] (Formation of an anti-fog film) A coating solution was applied to the bottom surface of a float glass (size: 50mm x 50mm, thickness: 1.1mm) that had been pre-cleaned by alkaline cleaning, using a spin coating method (1500 rpm, 10 seconds) to form a coating film. Next, the float glass with the coated film was heated at 100°C for 30 minutes to obtain a transparent article with an anti-fog coating.

[0070] (Examples 2-8) In preparing the coating solution, a transparent article with an anti-fogging film was obtained in the same manner as in Example 1, except that the raw materials and quantities listed in Table 1 were used. In Example 2, the amount of alcohol solvent was increased by the amount of epoxysilane that was reduced. In Example 3, the amount of alcohol solvent was decreased by the amount of polyether-modified siloxane that was increased. BYK-347, 349, and 3455 are polyether-modified silicones manufactured by Bic Chemie, and TSF-4440 is a polyether-modified silicone manufactured by Momentive Performance Materials.

[0071] (Comparative Examples 1-10) In preparing the coating solution, a transparent article with an anti-fogging film was obtained in the same manner as in Example 1, except that the raw materials and quantities listed in Table 2 were used. Note that "A-80" (Rapizol A-80) used in Comparative Example 10 is a product name manufactured by NOF Corporation. In Comparative Examples 1 to 6, the amount of alcohol solvent was increased by the amount of the component that was omitted.

[0072] The results of the water immersion test are shown in Tables 1 and 2.

[0073] [Table 1]

[0074] [Table 2]

[0075] In each example, the transparent articles with anti-fog coatings received a high-temperature steam evaluation of "SSS" to "S" after the water immersion test. In all examples, when the supply of high-temperature steam was stopped, a continuous film of water of uniform thickness formed on the surface of the transparent articles with anti-fog coatings, and neither whitening of the film itself nor fogging due to condensation was observed, ensuring the transparency of the articles with anti-fog coatings. In each example, the transparent continuous film that received an evaluation of "SSS" to "S" covered more than 90% of the surface of the anti-fog coating exposed to steam, more specifically, substantially all of the surface. In contrast, in Comparative Examples 7 to 9, the anti-fog coatings dissolved after the water immersion test. In Comparative Examples 1 to 6 and 10, when the supply of high-temperature steam was stopped, fogging due to condensation was observed, or large water droplets were dispersed and attached to the surface of the anti-fog coatings. As a result, even the largest QR codes could not be read in these comparative examples.

[0076] Furthermore, to confirm the effect of diol on the anti-fogging film, the following evaluations were performed on Examples 1, 7, and 8. The results are shown in Table 3.

[0077] [Table 3]

[0078] (Initial state) In the initial state after the anti-fogging film was formed, the appearance was evaluated in the same manner as described above, and the haze rate was also measured.

[0079] (Repeated anti-fogging test) In the initial state after the anti-fog film was formed, high-temperature steam was supplied to the anti-fog film in the same manner as in the high-temperature steam evaluation. Then, the transparent item with the anti-fog film was removed and placed upright in a holder to dry. After drying, the sample was again supplied with high-temperature steam to the anti-fog film, and this drying process was repeated until high-temperature steam was supplied to the anti-fog film 10 times. Subsequently, the appearance evaluation and high-temperature steam evaluation were performed in the same manner as above. In the high-temperature steam evaluation, QR code scanning was performed immediately after the 10th steam supply (excluding the 11th steam supply).

[0080] (Alcohol abrasion test) 0.5 cc of an alcohol solvent primarily composed of ethanol (Fine Etter A-10, manufactured by Futaba Chemical Co., Ltd.) was dropped onto a 25 mm wide nonwoven fabric cloth (Bencot M-3II, manufactured by Asahi Kasei Corporation) and allowed to soak in the solvent. This cloth was then set up for a reciprocating abrasion test along with a transparent object coated with an anti-fog film. A load of 400 g was applied to the cloth, and it was moved back and forth 20 times over a length of 30 mm. Subsequently, visual evaluation and high-temperature steam evaluation were performed in the same manner as described above.

Claims

1. It includes a transparent substrate and an anti-fog film on the surface of the transparent substrate. The anti-fog film contains a water-absorbing polymer. When the anti-fog film is immersed in water at 25°C for 24 hours, taken out of the water, and exposed to the water vapor generated from water at 90°C to 100°C placed 60 mm vertically downward from the anti-fog film for 30 seconds, in order for a transparent continuous film to be formed on the surface of the anti-fog film exposed to the water vapor, it further includes a component for improving the hydrophilicity of the surface and a cross-linked structure derived from a silane coupling agent for improving the water resistance of the anti-fog film. A transparent article with an anti-fog film for a security camera.

2. The transparent substrate is float glass, and the anti-fog film is formed on the bottom surface of the float glass. The transparent article with an anti-fog film for a security camera according to Claim 1.

3. The transparent substrate has a concave surface in contact with the space for accommodating the lens of the security camera. The transparent article with an anti-fog film for a security camera according to Claim 1.

4. A camera, and a transparent article with an anti-fog film for a security camera according to any one of Claims 1 to 3, disposed in front of the lens of the camera. A security camera.

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