Glass article with easy-to-clean coating

Abstract

A glass article with an easy-to-clean coating. The present disclosure provides a coated glass article having improved ease of cleaning. Provided is a coated glass article provided with a glass substrate and an easy-to-clean coating layer on the glass substrate, the coating layer containing a cerium oxide, and the contact angle of water on the surface of the coating layer being 60-130 DEG inclusive. The coating improves the removability of dirt such as water droplets adhering to the surface. The glass substrate may be tempered glass.

Description

[0001] This application is a divisional application. The application number of the parent application is: 202180058180.7, the application date is: August 20, 2021, and the name of the invention is: Glass article with easy-to-clean coating. Technical Field

[0002] The invention relates to a glass article with an easy-to-clean coating. Background Art

[0003] On the surface of various substrates, a film called an easy-to-clean coating is sometimes formed. The easy-to-clean coating makes it easy to remove dirt attached to the surface of the substrate. The easy-to-clean coating typically contains a fluorine-containing organic compound. A representative substrate for forming the easy-to-clean coating is a glass substrate. On the surface of the glass substrate, for example, a commercially available coating liquid containing a silicon alkoxide containing a fluoroalkyl group is applied to form the easy-to-clean coating.

[0004] Patent Document 1 discloses a technique of providing an adhesion promoter layer between a glass substrate and an easy-to-clean coating. Specifically, the adhesion promoter layer is a silicon mixed oxide layer, which improves the sustainability of the easy-to-clean property.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application No. 2014-522433 Summary of the invention

[0008] Problems to be solved by the invention

[0009] Conventional easy-to-clean coatings utilize the high water repellency of fluorinated organic compounds to suppress the adhesion of dirt. However, according to the research of the present inventors, there is room for improvement in the easy-to-clean property of fluorinated organic compounds.

[0010] The object of the present invention is to provide a coated glass article which has improved cleanability.

[0011] Means for solving problems

[0012] The present invention provides a glass article with a coating, which comprises a glass substrate and an easy-to-clean coating on the glass substrate.

[0013] The coating comprises cerium oxide,

[0014] The contact angle of water on the surface of the coating layer is 60° or more and 130° or less.

[0015] Effects of the Invention

[0016] According to the present invention, a coated glass article having improved easy-to-clean properties can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic cross-sectional view illustrating the progress of evaporation of water droplets on a hydrophilic surface.

[0018] Figure 2 Schematic cross-sectional view for explaining the progress of evaporation of water droplets on a surface to which water repellency is imparted by a fluorine-containing organic compound.

[0019] Figure 3 This is a diagram showing the results of observing the coated glass article produced in Example 1 using a scanning electron microscope (SEM).

[0020] Figure 4 This is a diagram showing the results of SEM observation of the coated glass article produced in Example 2.

[0021] Figure 5 This is a diagram showing the results of SEM observation of the coated glass article produced in Example 4.

[0022] Figure 6 This is a diagram showing the results of SEM observation of the coated glass article produced in Example 5.

[0023] Figure 7 This is a diagram showing the observation results of the dirt adhesion test / tap water performed in Example 10.

[0024] Figure 8 This is a diagram showing the observation results of the dirt adhesion test / tap water performed in Example 11.

[0025] Fig. 9 This is a diagram showing the observation results of the dirt adhesion test / tap water performed in Comparative Example 4.

[0026] Fig.10 This is a diagram showing the results of the dirt adhesion test / tap water observation performed in Comparative Example 5.

[0027] Fig.11A This is a diagram showing the observation results of the dirt adhesion test / hand soap before running water washing performed in Example 12.

[0028] Fig. 11B This is a diagram showing the observation results of the dirt adhesion test / hand soap running water washing performed in Example 12.

[0029] Fig. 12A This is a diagram showing the results of the dirt adhesion test / observation before washing with running water using hand soap performed in Comparative Example 6.

[0030] Fig. 12B This is a diagram showing the results of the dirt adhesion test / observation after washing with running water using a hand soap performed in Comparative Example 6.

[0031] Fig.13A This is a diagram showing the results of the dirt adhesion test / observation before washing with running water using hand soap performed in Comparative Example 7.

[0032] Fig. 13B This is a diagram showing the results of the dirt adhesion test / observation after washing with running water using a hand soap performed in Comparative Example 7. DETAILED DESCRIPTION

[0033] The following description of the embodiments of the present invention is not intended to limit the present invention to a specific embodiment. In this specification, "main component" refers to a component whose content is 50% or more, especially 60% or more, based on the mass basis. "Substantially not containing" means that the content is less than 1%, more specifically less than 0.1%, based on the mass basis. "Substantially flat" means that when observing with SEM, no concavities or convexities with a height or depth of more than 500nm are observed except for the particles and particulate convexities on the surface. "Normal temperature" is used as a term to indicate a temperature in the range of 5 to 35°C, especially 10 to 30°C.

[0034] The coated glass article provided by this embodiment comprises a glass substrate and an easy-to-clean coating on the glass substrate.

[0035] The coating comprises cerium oxide,

[0036] The contact angle of water on the surface of the coating layer is 60° or more and 130° or less.

[0037] The coated glass article provided by the present embodiment can be provided, for example, by the following manufacturing method, that is, comprising:

[0038] a step of applying a coating liquid containing cerium oxide as a solid component or a coating liquid containing chelated cerium ions on a glass substrate to form a coating film on the glass substrate; and

[0039] a step of drying the coating to form an easy-to-clean coating, and

[0040] The cerium oxide mentioned above includes CeO2.

[0041] Heretofore, the premise for easy-to-clean coatings is that the size of the water contact angle reaches the scale of easy-to-clean properties. Therefore, the coating materials used are organic materials that can achieve large contact angles, represented by fluorinated organic compounds. However, in reality, on surfaces that are given water repellency by fluorinated organic compounds, scattered dirt tends to remain as the water droplets attached to the surface evaporate. The dirt is a substance formed by the particles or solutes contained in the attached water droplets gathering in a spot-like manner in a trace area. The distribution of dirt is often observed on the surface of glass without a coating. Dirt that remains in a ring shape on the hydrophilic glass surface is sometimes called a "coffee ring". Dirt that remains concentrated in spots or rings is easy to be noticed, and sometimes cannot be easily removed depending on the degree of its concentration.

[0042] The mechanism by which dirt is retained in a ring can be achieved through Figure 1 To understand. The water droplet 10 attached to the hydrophilic surface 21 of the glass substrate 20 shrinks as the evaporation of water progresses and eventually disappears. During the period of evaporation, the water droplet 10 tends to shrink while maintaining the contact area with the hydrophilic surface 21. Therefore, the central part of the water droplet 10 shrinks significantly compared to the peripheral part. Along with this shrinkage, a flow 31 from the central part to the peripheral part 11p is generated inside the shrinking water droplet 11 near the surface 21 of the substrate 20. Due to this tiny flow 31, foreign matter contained in the water droplet 11 and particles as precipitated solutes gather at the peripheral part 11p and precipitate in a ring shape.

[0043] Dirt passes through the mechanism of spot retention Figure 2 It is understandable. The water droplet 10 attached to the water-repellent surface 22 of the glass substrate 20 shrinks as the evaporation of water progresses and eventually disappears. On the surface 22 to which water repellency is imparted by a fluorine-containing organic compound, the water droplet 10 tends to shrink while maintaining a large contact angle with the surface 22. Therefore, inside the water droplet 10 that shrinks into a smaller water droplet 11, a flow 32 from the peripheral portion toward the central portion 11c is generated near the surface 22 of the substrate. Due to this tiny flow 32, the particles contained in the water droplet gather in the central portion 11c and precipitate in a spot shape.

[0044] Surprisingly, it was found that on a coating containing cerium oxide and having a contact angle of water of 60° or more and 130° or less, especially 70° or more and 110° or less, there is a tendency that dirt exposed with the evaporation of water droplets does not concentrate. In other words, on the coating, after the evaporation of the water droplets, the tendency of dirt from the water droplets to attach to a specific part is alleviated. It is also confirmed that dirt attached relatively spread out on the coating is easier to remove than dirt attached in a concentrated manner. The coated glass article of the present embodiment alleviates the bias of attached dirt, thereby being able to have improved easy cleaning properties. On a surface that is water-repellent using a fluorine-containing organic compound in a manner that makes the contact angle of water the same as 60° to 130° as above, dirt remains in a spotty form. In view of this, it can be considered that not only the contact angle, but also cerium oxide contributes to the easy cleaning property of the present embodiment. In addition, the coated glass article of the present embodiment is also easy to wash off the attached organic matter. It can be considered that cerium oxide also contributes to improving the easy cleaning property of the attached organic matter.

[0045] Cerium oxide is different from aluminum oxide, silicon oxide, etc., and can function as a water-repellent material. According to the research of the inventors, the water repellency of cerium oxide can reach 75° or more, 80° or more, and further 85° or more, as indicated by the contact angle of water. Such a contact angle was previously achieved by surface treatment using a water-repellent agent as an organic substance. The water-repellent agent as an organic substance usually decomposes during heating to about 300°C, but cerium oxide will stably exist even if heated to a higher temperature.

[0046] In the present embodiment, the contact angle of water on the surface of the coating after the glass article is exposed to 760°C and 4 minutes of heat treatment can be 60° or more and 130° or less, particularly 70° or more and 110° or less. The contact angle of water exposed to heat treatment can reach 75° or more, 80° or more, and further 85° or more. However, in the present embodiment, the contact angle of water on the surface of the coating is sometimes temporarily reduced just after heat treatment, so it can be a value measured after being placed for a period of time after heat treatment. The recovery of the contact angle sometimes takes tens of days. Therefore, the above-mentioned contact angle can be, for example, a value measured after the glass article is exposed to 760°C and 4 minutes of heat treatment and then kept in the atmosphere at room temperature for 40 days.

[0047] Hereinafter, the glass substrate and the coating layer constituting the coated glass article of the present embodiment will be described, then the characteristics achievable by the present embodiment and the uses of the article will be described, and finally the manufacturing method of the present embodiment will be described.

[0048] (Glass substrate)

[0049] There is no particular restriction on the type of glass constituting the glass substrate. The glass substrate can be composed of various glasses such as soda-lime glass, borosilicate glass, aluminosilicate glass, alkali-free glass, quartz glass, etc. The glass substrate can have SiO2 as the main component. There is no particular restriction on the size and shape of the glass substrate. The glass substrate can be a glass plate, a glass container, a glass cover, a glass tube, a glass bulb, a glass lens, and other formed bodies. The glass container is, for example, a glass vial, a glass ampoule, a glass bottle, and may also have other shapes such as a tray, a dish, etc. As long as the glass cover functions as a cover, its shape is not limited, for example, it can have a shape that can be used as a cover for a cooking utensil.

[0050] The glass plate can be in the form of a flat plate, but can also have a curved shape imparted by a bending process. The thickness of the glass plate is not particularly limited, for example, in the range of 0.5 to 12 mm. The glass plate can be treated in a manner suitable for use as window glass for buildings, vehicles, etc. The glass plate can be subjected to a strengthening treatment, for example. In other words, the glass plate can be a strengthened glass. As a strengthening treatment, it is known to have air-cooled strengthening in which a compressive stress layer is produced on the surface by rapid cooling after heating, and chemical strengthening in which a compressive stress layer is produced on the surface by ion exchange of alkali metal ions. The glass plate can be integrated with other glass plates by lamination and / or double-layer processing. On the surface of the glass plate, a coating can be formed in order to impart or control properties other than water resistance. As a coating, Low-E film, conductive film, reflection suppression film, colored film, etc. can be exemplified. The colored film is, for example, a ceramic coating. The ceramic coating is formed for the purpose of imparting decorative properties, making a local area non-transparent, etc.

[0051] In the above-mentioned treatment of the glass plate, the glass plate is often heated. For example, the bending process of the glass plate includes a process of heating the glass plate to soften it. Not only the strengthening process, but also the lamination process and the double-layer process may heat the glass plate to a high temperature depending on the resin film sandwiched between the glass plates or the type of sealing material used to seal the space between the glass plates. If these heatings are performed, the water resistance of the easy-to-clean coating based on organic matter will be greatly reduced, and the easy-to-clean property will also be impaired. Therefore, it is necessary to form the coating after the treatment accompanied by the heating of the glass plate. Such process restrictions sometimes hinder the efficiency of mass production. For example, when the coating liquid is uniformly applied to the curved surface, it is quite difficult compared to the coating on the surface of the flat plate. The process of applying the coating liquid to the flat ribbon-shaped glass that has been cut and processed to have a curved surface can be implemented quite efficiently.

[0052] The problem of reduced water resistance due to treatment accompanied by heating is not limited to glass plates, but occurs in all glass substrates. In contrast, according to the present embodiment, since water resistance is manifested independently of organic matter, the reduction of water resistance accompanied by heating can be suppressed. Therefore, in the method of the present embodiment, various treatments of the glass substrate can be performed by heating the glass substrate with the coating after the coating is formed. If various treatments are exemplified for the glass plate, at least one of the following is selected from the group consisting of bending treatment accompanied by heating (heating bending treatment), air cooling strengthening treatment, chemical strengthening treatment, laminating treatment, double-layer processing treatment, and film formation treatment, in particular, heating bending treatment and / or air cooling strengthening treatment. That is, in the present embodiment, the glass substrate can be a glass plate that has been subjected to at least one treatment selected from the group consisting of heating bending treatment and air cooling strengthening treatment. The temperature applicable to the above heat treatment is usually up to about 760°C or less.

[0053] In the past, after cutting a glass plate into a given shape, a heating bending process and / or an air-cooling strengthening process were performed, and then a coating liquid for forming an easy-to-clean coating was applied to the main surface of the glass plate. Therefore, a part of the coating liquid adheres to the end surface of the glass plate, and a coating is also formed on at least a part of the end surface. In contrast, according to this embodiment, a coating liquid can be applied to the main surface of a flat glass plate to form an easy-to-clean coating, and then the glass plate is subjected to at least one treatment selected from the heating bending process and the air-cooling strengthening process. The glass plate provided by this method can be a glass plate having a coating on at least one of its main surfaces and having no coating on the end surface of the glass plate. A thick coating is sometimes formed locally on the end surface where the coating liquid is easily retained. Therefore, it is advantageous to avoid this problem in terms of ensuring the beauty of the product. Since it is not only possible to improve the quality in this way, but also possible to continuously apply the coating process to a large area of ​​the glass plate before cutting, it helps to reduce the cost of the final product.

[0054] (coating)

[0055] The easy-to-clean coating contains cerium oxide. The coating may contain 10% or more and 30% or more of cerium oxide by mass, and further may contain cerium oxide as the main component. The coating may be a film that does not substantially contain any component other than cerium oxide. The coating may have a surface that exposes cerium oxide. Cerium oxide preferably contains CeO2, i.e., an oxide of tetravalent cerium. Compared with Ce2O3, i.e., an oxide of trivalent cerium, CeO2 is an ideal component from the viewpoint of improving easy-to-clean properties. However, Ce2O3 may also be contained in the coating as cerium oxide. For example, when a compound containing trivalent cerium is used as a source of cerium oxide and a portion thereof is oxidized to tetravalent cerium, the coating contains not only CeO2 but also trivalent cerium as the remainder in the form of Ce2O3.

[0056] The easy-to-clean coating on a substrate such as glass usually has a multilayer structure of a metal oxide layer providing a base and an outer coating of an organic compound. In order to firmly bond with the metal oxide layer, the outer coating is often formed using a hydrolysis polycondensate of a hydrolyzable organosilicon compound. The hydrolyzable organosilicon compound is an organic compound suitable for improving water resistance, and is typically a compound containing a fluoroalkyl group. In contrast, in the present embodiment, the coating may not substantially contain a hydrolysis polycondensate of a hydrolyzable organosilicon compound. In addition, the coating may not substantially contain a fluorine-containing organic compound, particularly a compound containing a fluoroalkyl group.

[0057] The coating can be a single-layer film or a multilayer film composed of multiple layers, but a single-layer film is advantageous in reducing mass production costs. The easy-to-clean coating of the present embodiment can provide easy cleaning even if it is a single-layer film. In the case of a multilayer film, the coating preferably has a layer containing cerium oxide as the top layer of the multilayer film. In other words, in the present embodiment, a base layer can be sandwiched between the glass substrate and the coating. The base layer is, for example, a metal oxide layer, specifically, a coating whose mass-based content of cerium oxide is lower than that of the surface layer, and further, a layer that does not substantially contain cerium oxide. The base layer may include at least one selected from silicon oxide, aluminum oxide, zirconium oxide and titanium oxide. An example of an ideal base layer is a layer with silicon oxide as the main component. The base layer itself can be multilayer. As a base layer of a multilayer film, for example, a Low-E film can be used.

[0058] The easy-to-clean coating of this embodiment can provide a water contact angle of 60° or more, 65° or more, 70° or more, 75° or more, more specifically 80° or more, 85° or more, or optionally 90° or more. The upper limit of the water contact angle is not particularly limited, for example, 130° or less, 120° or less, 110° or less, 105° or less, more specifically 100° or less, or 95° or less. The water contact angle can be measured by dropping 4 mg (about 4 μL) of pure water onto the surface of the coating.

[0059] The easy-to-clean coating of the present embodiment does not lose its water repellency even when heated to a high temperature, such as 500° C., more specifically 760° C. For example, after a glass article is exposed to a heat treatment at 760° C. for 4 minutes, the coating of the present embodiment can provide a water contact angle of 60° or more, 65° or more, 70° or more, 75° or more, more specifically 80° or more, 85° or more, and optionally 90° or more, and 130° or less, 120° or less, 110° or less, 105° or less, more specifically 100° or less, or 95° or less.

[0060] Although the details of the reason are unclear, the water resistance of the easy-to-clean coating of the present embodiment is temporarily reduced after heating at high temperature. In addition, there are cases where the measured values ​​are unstable and show low values ​​just after film formation. However, even in these cases, as long as it is exposed to the atmosphere and stored at room temperature, the contact angle of water will slowly increase and then stabilize, showing the above-mentioned degree of contact angle. According to the research of the inventors, the time required for recovery and stabilization is roughly about 30 to 40 days. Therefore, the measurement of the contact angle after heat treatment at high temperature is preferably measured after being stored in the atmosphere at room temperature for a given period.

[0061] The easy-to-clean coating may contain an organic component. The organic component may be an organic compound or an organic group bonded to an oxide or the like constituting the film. The content of the organic component in the coating is not particularly limited, but may be 0.01% or more, more specifically 0.1% or more, and may be 10% or less, more specifically 1% or less, on a mass basis. A coating that has not been exposed to a high-temperature heat treatment may contain a relatively high content of organic components. However, the coating may also contain substantially no organic components.

[0062] The organic groups contained in the easy-to-clean coating may include epoxy groups. Epoxy groups are preferred functional groups suitable for use in the manufacturing examples described below. As described below, epoxy groups react with other components, specifically with acids, and are consumed, but epoxy groups added in excess may remain in the coating. Epoxy groups remaining in the coating act as crosslinking agents, particularly during heat treatment, and may affect the structure of the film.

[0063] The easy-to-clean coating may contain inorganic compounds other than cerium oxide. As oxides other than cerium oxide, silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, ruthenium oxide, and oxides of rare earths other than cerium can be exemplified. Cerium oxide is easy to obtain and cheap among rare earth oxides. The coating may not contain oxides of rare earths other than cerium oxide. Inorganic compounds may be, for example, nitrides, carbides, etc. in addition to oxides.

[0064] The thickness of the easy-to-clean coating is, for example, 2 to 1000 nm, particularly 5 to 500 nm. The coating may have a thickness of 7 nm or more, more preferably 10 nm or more, and may be 300 nm or less, more preferably 200 nm or less.

[0065] The easy-to-clean coating may have a dense structure, but may also have pores inside. The porosity of the coating may be, for example, 20% or more, 25% or more, 30% or more, or 40% or more as appropriate, and may be 85% or less, 70% or less, 60% or less, or 50% or less as appropriate. A coating with an appropriate porosity can have excellent optical properties. Specifically, by controlling the porosity, interference colors that may be generated by the coating can be eliminated, and visible light transmittance and reflectivity can be improved.

[0066] The easy-to-clean coating may have a plurality of particles on its surface. The particles may be cerium oxide particles. In other words, a portion of the cerium oxide contained in the coating may be contained as particles in the form of particles exposed on the surface of the film. The surface of the coating may be substantially flat. As described above, whether it is substantially flat or not is determined based on the flatness of the surface after the particles are removed, that is, after the concave-convex portions imparted by the particles are removed. The particle size of the cerium oxide particles may be in the range of 100 nm to 1.5 μm, and further, in the range of 250 nm to 1 μm. The particle size of the particles may be measured by SEM observation. In the surface of the coating, particles having the above-mentioned particle size may exist at a density in the range of 1 to 100, and further, in the range of 2 to 20, in a 5 μm square film surface. The presence of particles may contribute to the improvement of water repellency by the expansion of tiny concave-convex portions.

[0067] The crystallite size of the cerium oxide fine particles contained in the easy-to-clean coating layer is not particularly limited, and may be, for example, in the range of 1 to 100 nm, and more specifically, in the range of 2 to 20 nm.

[0068] It should be noted that, when the glass substrate is a glass plate, the easy-to-clean coating may be formed on only one main surface of the glass plate or on both main surfaces of the glass plate. However, in order to prevent a decrease in visible light transmittance, it is preferred to form the coating on only one main surface of the glass plate.

[0069] (characteristic)

[0070] The water resistance that the glass article of this embodiment can provide is as described above. In addition, the glass article of this embodiment can also have the following optical properties, for example. The visible light transmittance can be 65% or more, 70% or more, 80% or more, and more specifically, 85% or more. The upper limit of the visible light transmittance is not particularly limited, and is, for example, 95%. The visible light reflectance can be 20% or less, 15% or less, 10% or less, and more specifically, 8% or less. The lower limit of the visible light reflectance is not particularly limited, and is, for example, 2%. Here, the visible light reflectance is the visible light reflectance for the surface on which the coating is formed, in other words, it is the reflectance of the visible light that passes through the coating from the outside of the glass article and reaches the glass substrate. The turbidity rate is, for example, 20% or less, preferably 10% or less, more preferably 5% or less, and particularly preferably 4% or less. According to this embodiment, even a turbidity rate of 1% or less, and more specifically 0.5% or less can be achieved.

[0071] Preferred ranges of visible light transmittance, visible light reflectance, and haze ratio are shown below. The ranges in parentheses are more preferred.

[0072] Visible light transmittance: 80~95% (85~95%),

[0073] Turbidity rate: less than 5% (less than 4%),

[0074] Visible light reflectance of the surface of the glass substrate on which the coating is formed: 2 to 20% (2 to 8%).

[0075] (Purpose of the item)

[0076] The coated glass article of the present embodiment can be used for various purposes, and is particularly suitable for use as a glass article in an environment where water droplets adhere. The water droplets are usually supplied by natural water such as rain and fog, or tap water. Specifically, the coated glass article of the present embodiment may be an article corresponding to at least one selected from building glass, transport aircraft glass, store glass, furniture glass, household appliance glass, sign glass, mobile device glass, and solar cell glass. The coated glass article of the present embodiment may also be an article corresponding to at least one selected from window glass, roof glass, bathroom glass, mirror, store glass, mobile device glass, and solar cell glass. The window glass is, for example, the window glass of a building or a transport aircraft, and the roof glass is the same. The building is not limited to houses and buildings, and also includes greenhouses, arcades, or other structures fixed to the ground. The transport aircraft includes vehicles, ships, and aircraft. The vehicle is, for example, an automobile or a railway vehicle. The bathroom glass is, for example, the glass partition and glass door of a bathroom. The mirror is, for example, the mirror in a bathroom and a washstand. The store glass is, for example, the display window, counter, table, glass door of a refrigerator or a freezer, and the display cabinet for food and the like. The mobile device glass is, for example, the glass covering the display portion of a mobile device such as a smartphone or a tablet PC, and in some cases, the glass constituting the housing of the mobile device. The solar cell glass is, for example, the cover glass disposed on the light incident side of a solar cell. Especially in the case where safety for the human body needs to be ensured, tempered glass is often used in the above-mentioned various uses.

[0077] (Manufacturing method)

[0078] Next, the manufacturing method of the glass article of the present embodiment will be described. However, the glass article of the present embodiment may also be a glass article manufactured by a method other than the following manufacturing method.

[0079] The manufacturing method of the present embodiment includes a step of coating a coating liquid containing cerium oxide as a solid component on a glass substrate to form a coating film on the glass substrate, and a step of drying the coating film. The cerium oxide contains CeO2. It should be noted that the "cerium oxide" as the solid component only needs to be a component capable of supplying cerium oxide to the coating, and does not need to exist in the form of a complete oxide, and also includes cerium oxyhydroxide (日文:セリウム酸水酸化物) and cerium hydroxide that can supply cerium oxide after dehydration condensation.

[0080] The manufacturing method may further include a step of preparing a coating liquid. The coating liquid may contain a polar solvent, in particular a lower alcohol having a carbon number of 5 or less as a solvent. The lower alcohol may be methanol and / or ethanol. The step of preparing the coating liquid may include an operation of hydrolyzing a cerium compound containing trivalent cerium. The cerium compound capable of hydrolysis is preferably a compound dissolved in a polar solvent, specifically, it can be selected from water-soluble cerium compounds. The cerium compound may be, for example, at least one selected from cerium halides and cerium nitrates. Cerium halides are, for example, cerium (III) chloride and cerium (III) bromide. Including cerium (III) nitrate, as shown in the example here, the preferred cerium compound is a trivalent cerium compound. However, it is not limited thereto, and the cerium compound may also contain tetravalent cerium.

[0081] In a general sol-gel method, an acid or a base is added to the coating liquid in order to promote the hydrolysis of the metal compound. In the manufacturing method of the present embodiment, an acid or a base may also be added. However, a more preferred additive is an organic compound that acts as an acid scavenger, specifically an organic compound containing an epoxy group, especially a water-soluble epoxide. A water-soluble epoxide is a compound containing an epoxy group whose solubility in water at 20°C is 1g / 100ml or more. The water-soluble epoxide may be a monofunctional epoxide or a polyfunctional epoxide. Monofunctional water-soluble epoxides may be, for example, epoxy-containing alkanes such as propylene oxide (1,2-propylene oxide) and 1,2-butylene oxide, and may also be lauryl alcohol EO adduct glycidyl ether, phenol EO adduct glycidyl ether, and the like. Polyfunctional water-soluble epoxides may be, for example, glycerol polyglycidyl ether, polyglycerol diglycidyl ether, and sorbitol polyglycidyl ether.

[0082] As mentioned above, in the manufacture method of the present embodiment, the cerium compound is preferably hydrolyzed in the presence of a water-soluble epoxide. If the cerium compound is hydrolyzed in the presence of a water-soluble epoxide, the acid produced by the hydrolysis of the cerium compound is consumed, and the hydrolysis reaction is promoted. In addition, if the coating liquid to which the water-soluble epoxide is excessively added is used, it is easy to generate tetravalent cerium from trivalent cerium. This phenomenon is believed to be due to the stability improvement of tetravalent cerium in the region with high pH.

[0083] The prepared coating liquid is applied to the glass substrate. The coating liquid can be applied by a known method such as spin coating, bar coating, spray coating, nozzle flow coating, or roll coating.

[0084] The manufacturing method of the present embodiment may also include a step of applying at least one treatment selected from cleaning and drying to the coating. In the coating that is still in a wet state after coating, while containing cerium oxide, it also contains organic compounds contained in the coating liquid, such as water-soluble epoxides and ring-opening reaction products thereof. At least a portion of the organic compounds in the coating in a wet state is removed from the coating by a treatment as cleaning and / or drying, especially cleaning. The solvent used in the cleaning is suitable for an organic solvent, and is particularly suitable for a polar organic solvent with a carbon number of 5 or less. An example of a preferred cleaning is to use lower alcohols and ketones in sequence. Here, the lower alcohol is an alcohol with a carbon number of 5 or less as described above. The preferred ketone is a ketone with a carbon number of 7 or less, 5 or less, and further, 3 or less. By removing the organic compound, pores are formed in the dried coating, and micro-concave-convex can be formed on its surface. The porosity and the size of the micro-concave-convex can be controlled by the amount of organic compound added or other methods. The manufacturing method illustrated above is particularly suitable for forming an easy-to-clean coating with a desired porosity and micro-concave-convex.

[0085] The oxidation of the above-mentioned trivalent cerium to tetravalent cerium sometimes takes time. Therefore, the manufacturing method of the present embodiment may further include a step of maintaining at least one selected from the coating liquid and the coating film in a wet state for a given time. This step can be implemented, for example, by maintaining at least one selected from the prepared coating liquid and the coating film in a wet state at a temperature of 5 to 80° C. for 0.5 to 48 hours. By this step, the coating liquid or the coating film advances the so-called "aging", and the ratio of tetravalent cerium becomes higher. As the object of aging, the coating liquid is preferably used. For example, for the coating liquid, as the conversion to tetravalent cerium advances, coloration caused by tetravalent cerium is observed. A coating liquid containing only trivalent cerium is colorless if it does not contain other materials that are the cause of coloration. As the tetravalent cerium is generated, the coating liquid is typically first colored in a brown color system, and then can be further colored in a yellow color system. During the maintenance period, in order to generate a sufficient amount of tetravalent cerium, it is best to maintain the pH of the coating liquid so that it does not become too low. In order to control the pH, for example, the amount of water-soluble epoxide added that functions as an acid scavenger can be appropriately adjusted.

[0086] The process of tetravalent cerium generation can be monitored by using the absorption spectrum from the ultraviolet region to the visible region. For example, the absorption end of the coating liquid in the ultraviolet region moves to the long wavelength region as tetravalent cerium is generated. If the aging is continued until the absorption end exists in a region of, for example, 350 nm or more, especially 360 nm or more, tetravalent cerium is generated in an amount sufficient for the generation of an easy-to-clean coating.

[0087] It should be noted that the preferred amount of the water-soluble epoxide to be added varies depending on its type, etc. When the water-soluble epoxide is propylene oxide, the mixing ratio of cerium (III) contained in the cerium compound and propylene oxide can be in the range of 1:10 to 1:90, 1:15 to 1:80, more specifically 1:20 to 1:70, and particularly 1:25 to 1:50 in terms of molar ratio.

[0088] After the hydrolysis of the cerium compound, an organic compound containing an epoxy group such as a water-soluble epoxide can be further supplied. The organic compound containing an epoxy group can also be supplied to the film as a cleaning agent of the film. The supply of the organic compound containing an epoxy group after the hydrolysis can contribute to the initial stabilization of the contact angle of water after film formation. In addition, it can also contribute to the improvement of the contact angle of water after heat treatment.

[0089] The manufacturing method of this embodiment may further include a step of subjecting the glass substrate to a treatment accompanied by heating after forming the easy-to-clean coating on the glass substrate. The treatment accompanied by heating is at least one selected from the above examples, in particular, a heating bending treatment and / or an air cooling strengthening treatment. However, the glass substrate of this embodiment may also be used without receiving such treatment.

[0090] The manufacturing method of the present embodiment can also be implemented as a method having a process of forming a coating film on a glass substrate by applying a coating liquid containing chelated cerium ions on a glass substrate and a process of drying the coating film. In order to chelate the cerium ions, general chelating agents such as EDTA and acetylacetone can be used without particular restrictions. The cerium ions in the coating liquid can be trivalent cerium. In the drying process after applying the coating liquid and then in the heat treatment process, at least a part of the trivalent cerium ions that have been chelated is easily oxidized to tetravalent. The manufacturing method utilizing chelation does not need to be based on the effect of an acid scavenger such as a water-soluble epoxide, and except for this point, it can be implemented in the same manner as the above-mentioned method.

[0091] (Other manufacturing methods)

[0092] The glass article with the easy-to-clean coating of the present embodiment is not limited to the glass article manufactured by the liquid phase film forming method exemplified above, but can also be manufactured by a reduced pressure film forming method represented by a sputtering method, for example.

[0093] Hereinafter, the present invention will be described in further detail using examples. However, the following examples are not intended to limit the present invention to specific embodiments.

[0094] First, the method of measuring the characteristics will be described.

[0095] (Porosity)

[0096] The optical parameters of the film were obtained by spectral analysis of the reflected light using an ellipsometer (DVA-FL, manufactured by Mizojiri Optical Co., Ltd.). At this time, the laminated structure of the glass plate with the coating was set to glass plate (refractive index 1.52) / coating (refractive index 2.2; porosity 0), and the refractive index and film thickness of the coating were calculated by fitting, and the porosity was calculated.

[0097] (Optical properties)

[0098] The visible light transmittance and visible light reflectance were determined from visible and ultraviolet absorption spectra measured using a spectrophotometer (manufactured by Hitachi, Ltd., Model 330), and the turbidity was measured using a turbidity meter (manufactured by Suga Testing Instruments, Model HZ-V3).

[0099] (Contact angle of water)

[0100] Using a contact angle measuring machine (DMs-401 manufactured by Kyowa Interface Science Co., Ltd.), 4 mg of purified water was dripped onto the coating surface to measure the contact angle of water. However, the contact angle of water was measured after the coating was formed and placed in the atmosphere at room temperature for 20 days. The contact angle of water after heat treatment was measured when the glass plate with the coating was placed in the atmosphere at room temperature for 40 days after heat treatment.

[0101] (Heat Treatment)

[0102] The coated glass plate was heated in an electric furnace set at 760°C for 4 minutes, taken out of the furnace, wrapped with ceramic wool and cooled to room temperature at a cooling rate that would not cause thermal cracks. After the heat treatment, the water contact angle and other parameters were also measured.

[0103] (Dirt adhesion test / tap water)

[0104] With the main surface of the coated glass plate in a vertical position, tap water was sprayed onto the coating surface. The glass plate was then kept in an atmosphere at 70°C for 10 minutes to evaporate the water droplets attached to the coating surface. Thereafter, light from an LED light source was irradiated from the end surface of the coated glass plate to observe the coating surface.

[0105] (Dirt Adhesion Test / Hand Sanitizer)

[0106] After dripping a commercially available hand soap (trade name: Kirei Kirei Medicated Foam Hand Soap manufactured by Lion) diluted with water to a concentration of 20% by mass onto the coating surface of the coated glass plate, the glass plate was changed in a manner such that the main surface was oriented in a vertical direction so that the liquid droplets flowed down along the coating surface. Thereafter, tap water was flowed over the surface for 5 seconds to confirm the extent to which the traces of the liquid droplets became lighter. The coating surface was observed in the same manner as above by irradiating light from an LED light source from the end face of the coated glass plate.

[0107] (Example 1)

[0108] 0.168 g of cerium (III) chloride heptahydrate (manufactured by Simga Aldrich, 99.9%) was dissolved in 2 mL of anhydrous methanol (manufactured by Simga Aldrich) to obtain a colorless and transparent cerium (III) chloride solution. The solution contained 9.6% by mass of cerium (III) chloride. Then, 1.75 g of the cerium (III) chloride solution was mixed with 0.859 g of propylene oxide (manufactured by TIC, ≥99.0%) to obtain a stock solution. In the stock solution, the molar ratio of Ce to propylene oxide was 1:33.0. 2.609 g of the stock solution was diluted with 2.37 g of ethanol (manufactured by Kanto Chemical Co., Ltd., 99.5%) to obtain a coating solution. In the coating solution, the concentration of CeCl3 was 0.075 mmol / L. Then, the coating solution was stirred continuously overnight at room temperature for aging. During aging, the coating solution changed from colorless and transparent to white turbidity, brown, and then light yellow. It was confirmed from the evaluation of the visible ultraviolet absorption spectrum of the coating liquid during aging that at least a part of the trivalent cerium ions were oxidized to tetravalent cerium ions.

[0109] Cut high-transmittance glass (Optiwhite (registered trademark, Japanese: Optiwhite) 3mm thick, manufactured by Nippon Sheet Glass Co., Ltd.) into 10 cm squares, clean and dry them to prepare glass substrates. Apply the matured coating liquid to the glass substrate. Use a spin coater (manufactured by Mikasa Co., Ltd., 1H-360S model) to apply the coating under the conditions of a substrate rotation speed of 1000 rpm and a rotation retention time of 10 seconds after coating. Wash the wet film obtained by applying the coating liquid with isopropyl alcohol and then with acetone. Keep the cleaned wet film in an electric dryer set at 60°C to obtain a coated glass plate.

[0110] (Example 2)

[0111] A coated glass plate was obtained in the same manner as in Example 1 except that cleaning was performed with a 38% ethanol solution of cyclohexene oxide (manufactured by Fujifilm Corporation, 95%) instead of cleaning with acetone.

[0112] (Example 3)

[0113] A coated glass plate was obtained in the same manner as in Example 1 except that the molar ratio of Ce to propylene oxide in the stock solution of Example 1 was 1:65.7.

[0114] (Example 4)

[0115] A CeO 2 film was formed on the surface of the glass substrate used in Example 1 by magnetron sputtering using a CeO 2 target, thereby obtaining a coated glass plate.

[0116] (Example 5)

[0117] To 268.8 g of a mixed solvent mainly composed of ethanol (Fineeter A-10 manufactured by Futaba Chemicals Co., Ltd.), 4.04 g of cerium (III) nitrate hexahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, followed by the addition of 67.2 g of acetylacetone (manufactured by Tokyo Chemical Industry Co., Ltd.) and 60 g of propylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the mixture was stirred in a thermostatic bath at 40° C. for 24 hours to obtain a coating liquid.

[0118] A cleaned high-transmittance glass (Optiwhite (registered trademark) 3 mm thick, manufactured by Nippon Sheet Glass Co., Ltd.) of 20 cm × 30 cm was prepared as a glass substrate. The coating liquid was applied to the glass substrate by spraying. After air drying, it was dried in an oven set at 250°C for 10 minutes, and then fired in a muffle furnace set at 760°C for 4 minutes to obtain a glass plate with a coating.

[0119] In Example 5, unlike Examples 1 to 3, the coating liquid was not aged. However, in Example 5, since cerium was chelated by acetylacetone, cerium was oxidized to generate tetravalent cerium during the 10-minute drying and 4-minute calcination. The generation of tetravalent cerium can be confirmed by analyzing the coating film by X-ray photoelectron spectroscopy (XPS), for example.

[0120] (Example 6)

[0121] A coated glass plate was obtained in the same manner as in Example 5 except that the spin coating method was performed so as to form a thinner coating layer than in Example 5.

[0122] (Example 7)

[0123] A coated glass plate was obtained in the same manner as in Example 5 except that the spin coating method was performed so as to form a thinner coating layer than in Example 6.

[0124] (Example 8)

[0125] A coated glass plate was obtained in the same manner as in Example 5 except that a glass plate having a SiO 2 layer formed thereon (OptiShower manufactured by Pilkington; SiO 2 layer thickness: 15 nm) was used as the glass substrate and a coating layer was formed on the SiO 2 layer.

[0126] (Example 9)

[0127] A glass plate with a coating was obtained in the same manner as in Example 5 except that a glass plate with a Low-E film formed thereon was used as a glass substrate and a coating was formed on the Low-E film. The Low-E film is a multilayer film in which a SnO2 layer with a thickness of 25 nm, a SiO2 layer with a thickness of 25 nm, and a SnO2 layer doped with fluorine with a thickness of 340 nm are stacked in order from the glass plate side. The Low-E film is a film formed by a known method using a CVD method.

[0128] (Comparative Example 1)

[0129] A coated glass plate was obtained in the same manner as in Example 1 except that the molar ratio of Ce to propylene oxide in the stock solution of Example 1 was 1:6.7.

[0130] (Comparative Example 2)

[0131] A coated glass plate was obtained in the same manner as in Example 1 except that the molar ratio of Ce to propylene oxide in the stock solution of Example 1 was 1:0, that is, except that propylene oxide was not added.

[0132] (Comparative Example 3)

[0133] The glass substrate used in Example 1 was used as it is. That is, the glass plate itself without coating was used in Comparative Example 3. It should be noted that the contact angle of water in this Comparative Example was measured after the glass plate was washed and placed in the atmosphere at room temperature for 20 days, and after the aforementioned heat treatment and placed in the atmosphere at room temperature for 40 days.

[0134]

[0135] Pink interference colors were observed in Example 4, but no interference colors due to coating were observed in other examples. In Example 1, the contact angle of water just after film formation was less than 70 °, but slowly increased. Different from this, in Example 2, a contact angle of more than 70 ° was measured just after film formation. In addition, in each example, the contact angle of water was also measured after 100 days of film formation and heat treatment, and as a result, the measured values ​​were all more than 70 ° and stable in any case. It should be noted that the storage until the 100th day was also implemented in the atmosphere at room temperature.

[0136] In Examples 2 and 3, the absorption end of the absorption spectrum of the coating liquid shifted to the long wavelength side during aging, similarly to Example 1. On the other hand, in Comparative Examples 1 and 2, no shift of the absorption end to the long wavelength side was observed during aging.

[0137] For Examples 1, 2, 4 and 5, the surface of the coating was observed using SEM after the heat treatment. The results are shown in Figure 3 (Example 1), Figure 4 (Example 2), Figure 5 (Example 4) and Figure 6 (Example 5). The surfaces of the coatings of Examples 1 and 2 are substantially flat, but the cerium oxide particles present on the surfaces impart microscopic irregularities. Figure 4 ) on the film surface, it can be confirmed that there is more Figure 3 ) More cerium oxide particles.

[0138] In Examples 8 and 9, which used a glass plate having a SiO2 layer or the like formed as a base layer, the contact angle of water was lower than that of Example 5, in which a coating layer was directly formed on the surface of the glass plate. This is considered to be because the diffusion and migration of the glass component from the glass plate to the coating layer was suppressed.

[0139] The crystallite size of the cerium oxide after the heat treatment was measured by X-ray diffraction and was 4.85 nm for Example 1 and 2.10 nm for Example 2. It is considered that the added epoxy group-containing organic compound (cyclohexene oxide) in Example 2 inhibited the growth of crystallites.

[0140] (Example 10)

[0141] The coated glass plate prepared in Example 1 (before heat treatment) was subjected to a dirt adhesion test / tap water. The results are shown in Figure 7 middle.

[0142] (Example 11)

[0143] The coated glass plate prepared in Example 4 (before heat treatment) was subjected to a dirt adhesion test / tap water. The results are shown in Figure 8 middle.

[0144] (Comparative Example 4)

[0145] The glass plate of Comparative Example 3 (before heat treatment), i.e., the glass plate without coating, was subjected to a dirt adhesion test / tap water. The results are shown in Fig. 9 middle.

[0146] (Comparative Example 5)

[0147] The surface of the glass substrate used in Example 1 is coated with an antifouling coating agent. Specifically, a coating agent is prepared by diluting "OPTOOL DSX-E" manufactured by Daikin Industries with a solvent ("Novec7200" manufactured by 3M Company) to 0.1% by mass, spraying the coating agent onto the surface of the glass substrate, and drying the coating agent to obtain a glass plate with a coating. It should be noted that "OPTOOL DSX-E" contains a fluoroalkyl-containing compound as a water-repellent component at a concentration of 20% by mass. The contact angle of water on the surface of the obtained coating is 93°. A dirt adhesion test / tap water is performed on the coated glass plate. The results are shown in Fig.10 middle.

[0148] (Example 12)

[0149] The coated glass plate prepared in Example 4 (before heat treatment) was subjected to a dirt adhesion test / hand washing liquid. The observation results before washing with tap water are shown in FIG. Fig.11A The observation results after cleaning are shown in Fig. 11B middle.

[0150] (Comparative Example 6)

[0151] The glass plate of Comparative Example 3 (before heat treatment), i.e., the glass plate without coating, was subjected to the dirt adhesion test / hand washing liquid. The observation results before washing with tap water are shown in FIG. Fig. 12A The observation results after cleaning are shown in Fig. 12B middle.

[0152] (Comparative Example 7)

[0153] The coated glass plate prepared in Comparative Example 5 was subjected to a dirt adhesion test / hand washing liquid. The observation results before washing with tap water are shown in FIG. Fig.13A The observation results after cleaning are shown in Fig. 13B middle.

[0154] In Comparative Example 4, ring-shaped dirt was observed ( Fig. 9 ), spotty dirt was observed in Comparative Example 5 ( Fig.10 ). Since these dirt is concentrated in a specific part of the coating surface, it can be observed clearly. On the other hand, in Examples 10 and 11, the concentration of dirt remaining with the evaporation of water droplets is alleviated and difficult to identify ( Figure 7 and 8 ). The remaining dirt in Examples 10 and 11 can be easily removed by wiping with cotton cloth, but the dirt in Comparative Examples 4 and 5 remains even after wiping with cotton cloth.

[0155] On the glass surface of Comparative Example 6 and the fluorine-containing organic compound-based coating of Comparative Example 7, the dirt caused by organic matter (surfactants contained in hand soap, etc.) could not be washed away by running tap water alone ( Fig. 12A and 13A )( Fig. 12B and 13B On the other hand, in Example 12, the dirt caused by the attachment of organic matter was only caused by the flow of tap water. Fig.11A ) is basically removed ( Fig. 11B ).

Claims

1. A coated glass article comprising a glass substrate and an easy-to-clean coating on the glass substrate, The coating layer contains cerium oxide as a main component, wherein the main component refers to a component having a content of 50% or more by mass. The coating does not contain fluorine-containing organic compounds, The contact angle of water on the surface of the coating layer is greater than 85° and less than or equal to 130°.

2. The glass article according to claim 1, wherein The coating is not a coating comprising any at least one other metal cation of Ca, Y, K, Li, Mg, Sr or Gd.

3. The glass article according to claim 1, wherein: The coating layer contains substantially no components other than cerium oxide.

4. The glass article according to claim 1, wherein: A base layer is interposed between the glass substrate and the coating layer. The glass article according to claim 1 , wherein the visible light transmittance thereof is in the range of 65% or more.

6. The glass article according to claim 1, wherein: The thickness of the coating is in the range of 5 nm to 500 nm.

7. The glass article according to claim 1, wherein: The glass substrate is tempered glass.

8. The glass article according to claim 1, which corresponds to at least one selected from the group consisting of building glass, conveyor glass, store glass, furniture glass, home appliance glass, signboard glass, mobile device glass, and solar cell glass.

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