Glassware with Easy Clean coating

Abstract

To provide a glass article with a coating which includes an easy-to-clean coating with its own abrasion resistance improved.SOLUTION: A glass article with a coating comprises a glass substrate and an easy-to-clean coating on the glass substrate. The coating includes zirconium oxide, and the contact angle of water on the surface of the coating is 60° to 130° inclusive. The absolute value of the difference in visible light transmittance in the glass article before and after an abrasion resistance test of the coating carried out under the conditions of 500 reciprocating movements in accordance with the EN 1096-2:2001 abrasion resistance test is 0.7% or less except when No. 0000-grade steel wool is used instead of a felt pad.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a glass article with an easy-clean coating.

Background Art

[0002] A film called an easy-to-clean coating (Easy to clean coating) may be formed on the surface of various substrates. The easy-to-clean coating makes it easier to remove dirt adhering to the surface of the substrate. The easy-to-clean coating typically contains a fluorine-containing organic compound. A typical substrate on which the easy-to-clean coating is formed is a glass substrate. A commercially available coating solution containing a fluoroalkyl group-containing silicon alkoxide is applied to the surface of the glass substrate to form an easy-to-clean coating.

[0003] Patent Document 1 discloses a technique of providing an adhesion promoter layer between a glass substrate and an easy-to-clean coating. The adhesion promoter layer is specifically a silicon mixed oxide layer, which improves the durability of the easy-to-clean properties.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As disclosed in Patent Document 1, in order to improve the durability of the effect, particularly the abrasion resistance, of an easy-to-clean coating that suppresses the adhesion of dirt with a fluorine-containing organic compound to a practical level, a layer that promotes adhesion is required between the easy-to-clean coating and the glass substrate.

[0006] The present invention aims to provide coated glass articles equipped with an Easy Clean coating that has improved wear resistance. [Means for solving the problem]

[0007] The present invention The device comprises a glass substrate and an easy-clean coating on the glass substrate. The coating comprises zirconium oxide, The water contact angle on the surface of the coating is 60° or more and 130° or less. We provide coated glass articles. [Effects of the Invention]

[0008] According to the present invention, a coated glass article having improved wear resistance is provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view illustrating the process of evaporation of water droplets on a hydrophilic surface. [Figure 2] This is a schematic cross-sectional view illustrating the progression of water droplet evaporation on a surface that has been given water-repellent properties by a fluorine-containing organic compound. [Figure 3] This figure shows the results of observing the coated glass articles prepared in Example 1 using a scanning electron microscope (SEM). [Figure 4] This figure shows the results of observing the coated glass article prepared in Comparative Example 1 using a scanning electron microscope (SEM). [Modes for carrying out the invention]

[0010] The following description of embodiments of the present invention is not intended to limit the invention to any particular form. In this specification, “main component” means a component that is present in a mass of 50% or more, and especially 60% or more. “Substantially absent” means that the component is present in a mass of less than 1%, and even less than 0.1%. “Substantially flat” means that no irregularities of a height or depth of 500 nm or more are observed on the surface when observed with a scanning electron microscope (SEM). “Room temperature” is used as a term to mean a temperature in the range of 5 to 35°C, and especially 10 to 30°C.

[0011] The coated glass article provided by this embodiment is The device comprises a glass substrate and an easy-clean coating on the glass substrate. The coating comprises zirconium oxide, The water contact angle on the surface of the coating is between 60° and 130°.

[0012] Zirconium oxide has been found to be useful as a component of an easy-clean coating with good wear resistance. Zirconium oxide has superior heat resistance compared to fluorine-containing organic compounds. Moreover, the easy-clean coating according to this embodiment may also have the characteristic of being easy to clean.

[0013] Until now, the ease of cleaning of easy-clean coatings has been based on the premise that a high water contact angle is the measure of their cleanability. Therefore, the coating materials used have been organic materials that can achieve a high contact angle, such as fluorine-containing organic compounds. However, in reality, surfaces that have been given water repellency by fluorine-containing organic compounds tend to have scattered stains remaining as water droplets that adhere to them evaporate. These stains are formed when fine particles or solutes contained in the attached water droplets gather in small areas in a spot-like manner. Even on glass surfaces where no coating has been applied, uneven distribution of stains is often observed. Stains that remain in a ring shape on hydrophilic glass surfaces are sometimes called "coffee rings." Stains that remain concentrated in spots or rings are easily noticeable, and depending on the degree of concentration, they may not be easy to remove.

[0014] The mechanism by which the dirt remains in a ring shape can be understood from Figure 1. A water droplet 10 adhering to the hydrophilic surface 21 of the glass substrate 20 shrinks as the evaporation of water progresses and eventually disappears. While evaporation is progressing, the water droplet 10 tends to shrink while maintaining the contact area with the hydrophilic surface 21. As a result, the central part of the water droplet 10 shrinks more than the peripheral part. Along with this shrinkage, a flow 31 is generated inside the shrinking water droplet 11 near the surface 21 of the substrate 20, moving from the center to the peripheral part 11p. Due to this minute flow 31, the foreign matter and precipitated solute fine particles contained in the water droplet 11 gather at the peripheral part 11p and precipitate in a ring shape.

[0015] The mechanism by which dirt remains as spots can be understood from Figure 2. Water droplets 10 adhering to the water-repellent surface 22 of the glass substrate 20 shrink as the evaporation of water progresses and eventually disappear. On the surface 22, which has been given water repellency by a fluorine-containing organic compound, water droplets 10 tend to shrink while maintaining a high contact angle with the surface 22. As a result, inside the water droplet 10 that is shrinking into smaller droplets 11, a flow 32 is generated near the surface 22 of the substrate, moving from the periphery towards the center 11c. Due to this minute flow 32, fine particles contained in the water droplets gather in the center 11c and precipitate as spots.

[0016] Surprisingly, it has been found that on a coating containing a predetermined oxide and having a water contact angle of 60° or more and 130° or less, the dirt exposed with the evaporation of water droplets tends not to concentrate. In other words, on this coating, after the evaporation of water droplets, the tendency for dirt derived from the water droplets to adhere to specific sites in a biased manner is alleviated. Also, it has been confirmed that the dirt adhering relatively widely on this coating is easier to remove compared to the dirt adhering in a concentrated manner. The glass article with a coating according to the present embodiment can have an easy-cleaning property improved by alleviating the uneven distribution of the adhering dirt. On a surface imparted with water repellency by a fluorine-containing organic compound, even if the water contact angle is about the same as above, the dirt may remain in spots. Furthermore, the glass article with a coating according to the present embodiment also makes it easier to wash away the adhered organic substances. Oxides that can contribute to the improvement of the easy-cleaning property include, in addition to zirconium oxide, oxides of rare earth elements such as yttrium and cerium.

[0017] According to the study by the present inventors, the water repellency by zirconium oxide can reach 62° or more, 65° or more, 70° or more, and in some cases 72° or more, as indicated by the water contact angle. A contact angle of this degree can be achieved by a surface treatment using a water repellent that is an organic substance. The water repellent that is an organic substance usually decomposes in the process of heating up to about 300°C. In contrast, zirconium oxide can exist stably even when heated to a higher temperature.

[0018] In this embodiment, the contact angle of water on the surface of the coating after exposing the glass article to heat treatment at 760°C for 4 minutes can be 60° or more and 130° or less. The contact angle of water after exposure to heat treatment can reach 62° or more, 65° or more, 70° or more, and in some cases, even 72° or more. However, in this embodiment, since the contact angle of water on the surface of the coating may temporarily decrease immediately after heat treatment depending on the components of the coating, it may be measured after a lapse of time from the heat treatment. It may take dozens of days for the contact angle to recover. Therefore, the above contact angle may be, for example, measured after exposing the glass article to heat treatment at 760°C for 4 minutes and further storing it in the atmosphere at room temperature for 40 days.

[0019] Hereinafter, the glass substrate and the coating that constitute the coated glass article of this embodiment will be described. Subsequently, the characteristics that can be achieved by this embodiment and the uses of the article will also be described, and finally, the manufacturing method of this embodiment will be described.

[0020] (Glass Substrate) There is no particular limitation on the type of glass that constitutes the glass substrate. The glass substrate may be composed of various glasses such as soda-lime glass, borosilicate glass, aluminosilicate glass, alkali-free glass, and quartz glass. The glass substrate may have SiO2 as the main component. The glass substrate may contain oxides of alkali components (alkali metal elements) represented by sodium and potassium. There are also no special restrictions on the size and shape of the glass substrate. The glass substrate may be a glass plate, a glass container, a glass lid, a glass tube, a glass valve, a glass lens, or other shaped bodies. The glass container may be, for example, a glass vial, a glass ampule, or a glass bottle, but may also have other shapes such as trays and petri dishes. As long as the glass lid functions as a lid, its shape is not limited, and it may have a shape that can be used as a lid for cooking utensils, for example.

[0021] The glass substrate may include a dealkalization layer on the coating side surface. Including a dealkalization layer suppresses the diffusion and transfer of alkaline components of the glass from the glass substrate to the coating. In this embodiment, the dealkalization layer refers to a silica-rich layer formed by a dealkalization reaction on the surface of the glass substrate and subsequent densification.

[0022] A glass substrate containing a dealkalization layer on the coated surface can be manufactured, for example, by the float process, a continuous manufacturing method for glass plates. In the float process, glass raw materials melted in a float furnace are formed into plate-shaped glass ribbons on the molten metal in the float bath. The resulting glass ribbons are then slowly cooled in an annealing furnace and cut into glass plates of a predetermined size. In this embodiment, the case in which molten tin is used as the molten metal will be described. Here, in the glass plate, the surface that was in contact with the molten tin during the molding process in the float bath is called the bottom surface. The surface opposite the bottom surface, which is not in contact with the molten tin, is called the top surface.

[0023] First, at least the bottom surface is subjected to a dealkalization treatment. Dealkalization here refers to bringing an oxidizing gas that reacts with alkaline components into contact with the surface of the glass plate to extract the alkaline components from the glass. The extracted alkaline components react with the oxidizing gas, and as a result, a protective film is formed on at least the bottom surface of the glass plate.

[0024] As the oxidizing gas, for example, sulfur dioxide (SO2 gas) can be used. SO2 reacts with the components of the glass to form an alkali sulfate such as sodium sulfate on the surface of the glass plate. This alkali sulfate forms a protective film. The oxidizing gas used here may be a gas other than SO2 that can form a protective film by reacting with the alkaline components in the glass. Gases that have a strong dealkalization effect, such as hydrogen fluoride gas, are undesirable because they do not form a protective film and etch the glass surface, creating irregularities on the glass surface. In addition, air, nitrogen, argon, or other inert gases may be used as the carrier gas. The oxidizing gas may also contain water vapor.

[0025] Next, densification occurs in the area where the protective film has formed. Specifically, protons (H) replace the alkaline components that have been removed by dealkalization. + ) and oxonium ion (H3O + Under various conditions such as those described above, moisture in the atmosphere penetrates the glass, and silanol groups (≡Si-OH) are formed in the areas where a protective film is formed. Then, these silanol groups undergo dehydration condensation to form siloxane bonds (≡Si-O-Si≡). In this embodiment, the state in which the number of siloxane bonds increases due to such dehydration condensation is referred to as "densification." Since the surface of a glass plate with an increased number of siloxane bonds becomes more difficult to etch, the degree of densification can be determined by measuring the etching rate.

[0026] By the method described above, a dealkalized layer is formed on at least the bottom surface. The top surface may also be treated to form a dealkalized layer. Furthermore, even if an oxidizing gas is sprayed only on the bottom surface, some of the sprayed oxidizing gas may seep over to the top surface, treating it and forming a dealkalized layer on the top surface as well.

[0027] In this embodiment, the dealkalization layer on the coated surface of the glass substrate may be a dealkalization layer formed on the bottom surface or a dealkalization layer formed on the top surface. The formation of a dealkalization layer on the coated surface of the glass substrate suppresses the diffusion and transfer of alkaline components from the glass substrate to the coating.

[0028] If a dealkalization layer is also formed on the top surface, the thickness of the dealkalization layer on the top surface will be greater than the thickness of the dealkalization layer formed on the bottom surface. This is because the formation of a dealkalization layer is suppressed on the bottom surface because the reaction between SO2 gas and the glass components is suppressed due to the presence of a tin oxide diffusion layer within its surface. In this embodiment, the dealkalization layer on the coating side surface may be the dealkalization layer formed on the top surface. In this case, the diffusion and transfer of the alkaline components of the glass from the glass substrate to the coating is further suppressed.

[0029] As described above, the glass substrate may be a glass plate. The glass plate may be flat, but may also have a curved shape imparted by a bending process. The thickness of the glass plate is not particularly limited, but is, for example, within the range of 0.5 mm to 12 mm. The glass plate may be treated to be suitable for use as window glass in buildings, vehicles, etc. The glass plate may be subjected to, for example, tempering treatment. In other words, the glass substrate such as a glass plate may be tempered glass. Known tempering treatments include air-cooled tempering, which involves heating and then rapidly cooling to create a compressive stress layer on the surface, and chemical tempering, which involves ion exchange of alkali metal ions to create a compressive stress layer on the surface. The glass plate may be integrated with another glass plate by lamination and / or multi-layering.

[0030] Many of the glass plate processing methods described above involve heating the glass plate. For example, the bending process of glass plates includes a step of heating and softening the glass plate. In addition to strengthening processes, lamination and multi-layer processing may also involve heating the glass plate to high temperatures, depending on the type of resin film sandwiched between the glass plates or the type of sealant used to seal the space between the glass plates. After these heating processes, the water repellency of organic Easy Clean coatings is greatly reduced, and their Easy Clean properties are also impaired. For this reason, coating formation had to be carried out after processing that involved heating the glass plate. Such process limitations can hinder the efficiency of mass production. For example, uniformly applying a coating liquid to a curved surface is significantly more difficult than applying it to the surface of a flat plate. The process of applying the coating liquid to flat strip-shaped glass before it is cut and processed to have individual curved surfaces can be carried out much more efficiently.

[0031] The problem of reduced water repellency due to heating processes occurs not only in glass plates but in glass substrates in general. In contrast, according to this embodiment, since water repellency is achieved without relying on organic substances, the reduction in water repellency due to heating can be suppressed. Therefore, in the method according to this embodiment, after forming the coating, the glass substrate on which the coating has been formed can be heated to perform various treatments on the glass substrate. Examples of these treatments for glass plates include at least one selected from the group consisting of heating bending (heat bending), air cooling strengthening, chemical strengthening, lamination, multi-layer processing, and film formation, particularly heating bending and / or air cooling strengthening. That is, in this embodiment, the glass substrate may be a glass plate that has undergone at least one treatment selected from the group consisting of heating bending and air cooling strengthening. The temperature applied to the above heat treatments is usually no higher than about 760°C.

[0032] Conventionally, glass plates were cut into a predetermined shape, then subjected to a heat bending treatment and / or air cooling strengthening treatment, and subsequently, a coating liquid for forming the Easy Clean coating was applied to the main surface of the glass plate. As a result, some of the coating liquid adhered to the edge surface of the glass plate, and at least a portion of the coating was formed on the edge surface as well. In contrast, according to this embodiment, the coating liquid is applied to the main surface of a flat glass plate to form the Easy Clean coating, and then at least one treatment selected from the group consisting of heat bending treatment and air cooling strengthening treatment can be performed on the glass plate. The glass plate provided by this embodiment may have a coating on at least one of its main surfaces, and no coating on the edge surface of the glass plate. A locally thick coating may be formed on the edge surface where the coating liquid tends to accumulate. Therefore, being able to avoid this has advantages in terms of ensuring the aesthetic appearance of the product. In addition to this improvement in quality, it is possible to continuously apply the coating treatment to a large area of ​​glass plate before cutting, which contributes to reducing the cost of the final product.

[0033] (coating) EasyClean coating contains zirconium oxide. The coating may contain zirconium oxide in amounts of 5 mol% or more, 8 mol% or more, and even 9 mol% or more, and may also contain it as a main component. The coating may be a film that is substantially free of components other than zirconium oxide. The coating may have a surface in which zirconium oxide is exposed.

[0034] The EasyClean coating may further contain inorganic compounds other than zirconium oxide. Examples of inorganic compounds other than zirconium oxide include oxides of rare earth elements. The inorganic compounds may also be other than oxides, such as nitrides or carbides.

[0035] The Easy Clean coating may further contain oxides of rare earth elements. Oxides of rare earth elements, like zirconium oxides, can function as water-repellent materials. The coating may contain 10 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% or more of oxides of rare earth elements. The coating may also be a film mainly composed of zirconium oxide and oxides of rare earth elements.

[0036] The oxide of the rare earth element may be at least one selected from the group consisting of cerium oxide, lanthanum oxide, and yttrium oxide. The oxide of the rare earth element may be cerium oxide. Cerium oxide, like zirconium oxide, is a preferred material that can impart appropriate water repellency. According to our studies using X-ray diffraction, the combination of zirconium oxide and cerium oxide is suitable for use in easy-clean coatings because the zirconium oxide can cooperate with the cerium oxide without impairing its crystallinity. An easy-clean coating containing cerium oxide along with zirconium oxide attracts organic components more easily than a coating containing only zirconium oxide. This is because cerium oxide does not easily form hydrogen bonds with water molecules due to its unique electron orbitals. In addition, the attracted organic components have adsorption capacity. Therefore, it is expected that by mixing cerium oxide into the easy-clean coating, stable water repellency will be achieved, and the easy-clean function will be provided.

[0037] The coating may contain 10 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% or more of cerium oxide. The coating may also be a film mainly composed of zirconium oxide and cerium oxide. Preferably, the cerium oxide contains CeO2, i.e., tetravalent cerium oxide. CeO2 is a desirable component from the viewpoint of improving ease of cleaning compared to Ce2O3, i.e., trivalent cerium oxide. However, the coating may also contain Ce2O3 as cerium oxide. For example, if a compound containing trivalent cerium is used as a source of cerium oxide and a portion of it is oxidized to tetravalent cerium, the remaining trivalent cerium will be included in the coating as Ce2O3 along with the CeO2. In this specification, the content and other ratios or proportions of cerium oxide in the coating will be calculated by converting all cerium oxide to CeO2, in other words, assuming that all cerium exists in the tetravalent state.

[0038] In the Easy Clean coating, the molar ratio of cerium oxide to zirconium oxide (cerium oxide / zirconium oxide) is not particularly limited, but may be 0.01 or more, 0.1 or more, 0.5 or more, 0.75 or more, 1 or more, or 50 or more, 30 or less, 20 or less, or 15 or less.

[0039] Easy-clean coatings on substrates such as glass typically have a multilayer structure consisting of a metal oxide layer providing a base and an organic compound overcoat layer. The overcoat layer is often composed of hydrolyzable organosilicon polycondensates to strongly bond with the metal oxide layer, which acts as an adhesive layer. Hydrolyzable organosilicon compounds are organic compounds suitable for improving water repellency, typically fluoroalkyl group-containing compounds. In contrast, in this embodiment, the coating may not substantially contain hydrolyzable organosilicon polycondensates. Furthermore, the coating may not substantially contain fluorine-containing organic compounds, particularly fluoroalkyl group-containing compounds.

[0040] The coating may be a single layer or a multi-layered film, but a single layer is advantageous for reducing mass production costs. The Easy Clean coating of this embodiment can provide easy cleaning even as a single layer. In the case of a multi-layered film, it is desirable that the coating includes a layer containing zirconium oxide as the uppermost layer of the multi-layered film.

[0041] In other words, in this embodiment, a base layer may be further included between the glass substrate and the coating. The inclusion of a base layer suppresses the diffusion and transfer of alkaline components of the glass from the glass substrate to the coating. The base layer may be, for example, a metal oxide layer, and more specifically, a layer in which the mass-based content of zirconium oxide is lower than that of the surface coating, or even a layer that is substantially free of zirconium oxide. The base layer may contain at least one selected from the group consisting of silicon oxide and aluminum oxide. A desirable example of a base layer is a layer mainly composed of silicon oxide (SiO2). The base layer itself may consist of multiple layers.

[0042] The substrate layer may be amorphous. Because Easy Clean Coating is crystalline, alkaline components of the glass easily diffuse from the glass substrate to the coating. However, if the substrate layer is amorphous, the diffusion of alkaline components from the glass substrate to the coating is further suppressed due to the absence of grain boundaries.

[0043] The thickness of the underlying layer is, for example, in the range of 10 to 400 nm. The thickness of the underlying layer may be 10 nm or more, 20 nm or more, or even 30 nm or more, and may be 350 nm or less, 300 nm or less, or even 250 nm or less.

[0044] The underlayer may be a layer that can function as a low-emission film (Low-E film), a conductive film, a reflection-suppressing film, a colored film, etc.

[0045] Low-E films are, for example, laminated films including a conductive layer. Low-E films have a laminated structure in which a color-adjusting layer and a conductive layer are laminated in order from the main surface side of a glass substrate. The color-adjusting layer is, for example, a layer mainly composed of at least one selected from the oxides of silicon, aluminum, zinc, and tin. The color-adjusting layer may be a layer mainly composed of tin oxide. The thickness of the color-adjusting layer is, for example, 25 nm to 90 nm, and particularly 35 nm to 70 nm. The color-adjusting layer may be composed of two or more layers with different refractive indices. Two layers with different refractive indices are, for example, a first color-adjusting layer mainly composed of tin oxide and a second color-adjusting layer mainly composed of silicon oxide, in order from the glass substrate side such as a glass plate. However, the lamination order of the first and second color-adjusting layers is not particularly limited. The conductive layer is a layer whose main component is at least one selected from, for example, indium tin oxide (ITO), zinc aluminum oxide, antimond-doped tin oxide (SnO2:Sb), and fluorine-doped tin oxide (SnO2:F). The conductive layer may be a layer whose main component is fluorine-doped tin oxide (SnO2:F). The thickness of the conductive layer is, for example, 100 nm to 350 nm, and particularly 120 nm to 260 nm.

[0046] The EasyClean coating of this embodiment can provide a water contact angle of 60° or more, 62° or more, 70° or more, 75° or more, and in some cases, 80° or more. The upper limit of the water contact angle is not particularly limited, but for example, it is 130° or less, 120° or less, 110° or less, 100° or less, and furthermore 95° or less, 90° or less, and especially 85° or less. The water contact angle can be measured by dropping 4 mg (approximately 4 μL) of purified water onto the surface of the coating.

[0047] The Easy Clean coating of this embodiment retains its water-repellent properties even when heated to high temperatures, such as 500°C, or even 760°C. The coating of this embodiment can provide a water contact angle of 60°C or higher, 62°C or higher, 70°C or higher, 75°C or higher, and possibly 80°C or higher, and 130°C or lower, 120°C or lower, 110°C or lower, 100°C or lower, and further 95°C or lower, 90°C or lower, and especially 85°C or lower, even after exposing a glass article to a heat treatment at 760°C for 4 minutes. Before and after heat treatment, the water contact angle may be within a range of any combination of the lower and upper limits exemplified above, for example, between 62°C and 85°C.

[0048] Although the detailed reasons are unclear, the water repellency of the Easy Clean coating in this embodiment may temporarily decrease after being heated at high temperatures. Also, immediately after film formation, the measured values ​​may be unstable and low. However, even in these cases, simply exposing the coating to the atmosphere and storing it at room temperature will gradually increase the water contact angle, and it will stabilize to the contact angle described above. According to the inventors' research, the period required for recovery and stabilization is approximately 30 to 40 days. Therefore, it is desirable to measure the contact angle after heat treatment at high temperatures after storing the coating in the atmosphere at room temperature for a predetermined period of time.

[0049] Easy Clean coatings may contain organic components. These organic components may be organic compounds or organic groups bonded to oxides or other elements that constitute the film. The content of organic components in the coating is not particularly limited, but may be 0.01% or more by mass, more preferably 0.1% or more, 10% or less, and more preferably 1% or less. Coatings that have not been subjected to high-temperature heat treatment may contain a relatively high content of organic components. However, the coating may not contain substantially any organic components.

[0050] The film thickness of the Easy Clean coating is, for example, between 2 nm and 1000 nm, more specifically between 5 nm and 500 nm, and more particularly between 10 nm and 300 nm. The coating film thickness may be 15 nm or more, more specifically 20 nm or more, and may be 100 nm or less, or even 50 nm or less. If the Easy Clean coating is too thick, cracks that can cause peeling are more likely to occur, so if crack prevention is to be reliably prevented, the coating film thickness may be 30 nm or less.

[0051] The surface of the Easy Clean coating may be substantially flat.

[0052] Furthermore, if the glass substrate is a glass plate, the Easy 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 desirable to form the coating on only one main surface of the glass plate.

[0053] (characteristic) The water repellency that the glass article of this embodiment can provide is as described above. In addition, the glass article of this embodiment may have the following abrasion resistance, for example. The glass article may have an absolute difference of 0.7% or less in visible light transmittance before and after an abrasion resistance test on an Easy Clean coating conducted under the conditions of 500 back-and-forth cycles (Class A) in accordance with the abrasion resistance test of EN1096-2:2001, except that steel wool of grade No. 0000 was used instead of a felt pad.

[0054] The absolute difference in visible light transmittance of the glass article before and after the abrasion resistance test using steel wool may be 0.6% or less, 0.5% or less, or even 0.4% or less. There is no particular lower limit to the absolute value of the difference in visible light transmittance, but for example, it is 0.01% or more.

[0055] Furthermore, the glass articles of this embodiment may have the following abrasion resistance: The absolute value of the difference in visible light transmittance before and after an abrasion resistance test on an Easy Clean coating, conducted in accordance with the EN1096-2:2001 abrasion resistance test using a felt pad, except that the condition of 10,000 reciprocations was adopted instead of the condition of 500 reciprocations (Class A), may be 0.22% or less, and even 0.1% or less.

[0056] Furthermore, the glass article of this embodiment may have, for example, the following optical properties: The visible light transmittance may be 65% or more, 70% or more, 80% or more, and even 85% or more. The upper limit of the visible light transmittance is not particularly limited, but for example it is 95%. The haze rate is, for example, 10% or less, preferably 5% or less, even more preferably 3% or less, and particularly preferably 2% or less. According to this embodiment, a haze rate of 1% or less, and even more preferably 0.5% or less, can also be achieved.

[0057] The preferred ranges for visible light transmittance and haze rate are as follows. The ranges in parentheses are even more preferred. Visible light transmittance: 80~95% (85~95%) Haze rate: 5% or less (4% or less)

[0058] (Use of the item) The coated glass articles according to this embodiment can be used for various purposes, but are particularly suitable for use as glass articles in environments where water droplets adhere. Water droplets are usually supplied from natural water such as rain and fog, or from tap water. Specifically, the coated glass articles according to this embodiment may be articles that fall under at least one selected from the group consisting of building glass, transport equipment glass, store glass, furniture glass, home appliance glass, signage glass, mobile device glass, and solar cell glass. The coated glass articles according to this embodiment may be articles that fall under at least one selected from the group consisting of window glass, roof glass, bathroom glass, mirror, store glass, mobile device glass, and solar cell glass. Window glass is, for example, window glass of a building or transport equipment, and roof glass is similar. Buildings are not limited to houses and buildings, but also include greenhouses, arcades, and other structures fixed to the land. Transport equipment includes vehicles, ships, and aircraft. Vehicles are, for example, automobiles or railway cars. Bathroom glass is, for example, glass partitions and glass doors for bathrooms. Mirrors include, for example, bathroom and vanity mirrors. Commercial glass includes, for example, display windows, counters, tables, glass doors for refrigerated or frozen cases, and display cases for food, etc. Mobile device glass includes, for example, glass that covers the display area of ​​mobile devices such as smartphones and tablet PCs, and in some cases, glass that constitutes the casing of the mobile device. Solar cell glass includes, for example, cover glass placed on the light incidence side of solar cells. In particular, tempered glass is often used in each of the above applications when it is necessary to ensure safety for the human body.

[0059] In the applications described above, the Easy Clean coating according to this embodiment may also provide other functions such as anti-glare and anti-fogging, in addition to its Easy Clean properties. The Easy Clean coating according to this embodiment may have at least one function selected from the group consisting of anti-glare and anti-fogging.

[0060] (Manufacturing method) Next, the manufacturing method of the glass article of this embodiment will be described. However, the glass article of this embodiment may be manufactured by a method other than the manufacturing method described below.

[0061] The manufacturing method of this embodiment comprises the steps of applying a coating liquid containing zirconium oxide to a glass substrate to form a coating film on the glass substrate, and drying the coating film. Note that the "zirconium oxide" as a solid component does not need to exist as a complete oxide, as long as it is a component that can supply zirconium oxide to the coating; it also includes zirconium hydroxide, zirconium hydroxide, etc., which can supply zirconium oxide after dehydration condensation.

[0062] This manufacturing method may further comprise a step of preparing a coating solution. The coating solution may contain a polar solvent, particularly a lower alcohol having 5 or fewer carbon atoms. The lower alcohol may be methanol and / or ethanol. The step of preparing the coating solution may include dissolving a zirconium compound in a polar solvent. Therefore, the zirconium compound may be a compound that dissolves in a polar solvent.

[0063] The prepared coating solution is applied to a glass substrate. The coating solution can be applied by known methods such as spin coating, bar coating, spray coating, nozzle flow coating, and roll coating.

[0064] The manufacturing method of this embodiment may further include a step of subjecting the coating film to at least one treatment selected from washing and drying.

[0065] When the coating solution contains a rare earth element oxide, such as cerium oxide, along with zirconium oxide, the manufacturing method of this embodiment comprises the steps of applying the coating solution containing zirconium oxide and cerium oxide to a glass substrate to form a coating film on the glass substrate, and drying the coating film. Cerium oxide includes CeO2. Note that "cerium oxide" does not need to exist as a complete oxide, as long as it is a component that can supply cerium oxide to the coating, and also includes ceric acid hydroxide, cerium hydroxide, etc., which can supply cerium oxide after dehydration condensation.

[0066] In this case, the step of preparing the coating solution may further include hydrolyzing a cerium compound containing trivalent cerium. The hydrolyzable cerium compound is preferably a compound that dissolves in a polar solvent, and specifically, it is preferable to select it from water-soluble cerium compounds. The cerium compound may be, for example, at least one selected from the group consisting of cerium halides and cerium nitrate. Examples of cerium halides are cerium(III) chloride and cerium(III) bromide. As exemplified herein, including cerium(III) nitrate, preferred cerium compounds are compounds of trivalent cerium. However, the cerium compound is not limited to these, and may also contain tetravalent cerium. The oxidation of trivalent cerium to tetravalent cerium may take time. Therefore, if the coating solution contains zirconium oxide and cerium oxide, the manufacturing method of this embodiment may further include a step of holding at least one selected from the coating solution and the wet coating film for a predetermined time. This process can be carried out, for example, by holding at least one selected from the prepared coating solution and the wet coating film at a temperature of 5 to 80°C for 0.5 to 48 hours. This process causes the coating solution or coating film to undergo "aging," so to speak, and the proportion of tetravalent cerium increases. The coating solution is preferred as the target for aging. For example, as the conversion to tetravalent cerium progresses in the coating solution, a color change due to tetravalent cerium will be observed. A coating solution containing only trivalent cerium will be colorless unless other materials that cause coloration are present. As tetravalent cerium is generated, the coating solution may typically first turn brownish, and then further turn yellowish. To generate a sufficient amount of tetravalent cerium during the holding period, it is desirable to maintain the pH of the coating solution so that it does not become too low.

[0067] The process of tetravalent cerium formation can be monitored using absorption spectra from the ultraviolet to the visible region. For example, the ultraviolet absorption edge of the coating solution shifts to longer wavelengths as tetravalent cerium is formed. If aging is continued until this absorption edge is located above, for example, 350 nm, and especially above 360 ​​nm, a sufficient amount of tetravalent cerium will be generated to form the Easy Clean coating.

[0068] The manufacturing method of this embodiment may further include a step of performing a heat-inducing treatment on the glass substrate after forming an Easy Clean coating on the glass substrate. The heat-inducing treatment is at least one selected from the group consisting of the examples described above, and is particularly a heat bending treatment and / or an air-cooling strengthening treatment. However, the glass substrate of this embodiment can also be used without undergoing such treatment.

[0069] The manufacturing method in this embodiment can also be carried out as a method comprising the steps of applying a coating liquid containing chelated zirconium ions onto a glass substrate to form a coating film on the glass substrate, and drying the coating film. To chelate the zirconium ions, general chelating agents such as EDTA and acetylacetone can be used without particular limitation.

[0070] When the coating solution contains zirconium oxide and cerium oxide, the manufacturing method in this embodiment can also be carried out as a method comprising the steps of applying the coating solution containing chelated zirconium ions and chelated cerium ions onto a glass substrate to form a coating film on the glass substrate, and drying the coating film. For chelation, general chelating agents such as EDTA and acetylacetone can be used without particular limitation. The cerium ions in the coating solution may be trivalent cerium. Chelated trivalent cerium ions are more likely to be oxidized to tetravalent cerium in the drying step after the coating solution is applied, and further in the heat treatment step.

[0071] (Other manufacturing methods) The glass articles with the Easy Clean coating of this embodiment are not limited to those manufactured by the liquid-phase film formation method exemplified above. [Examples]

[0072] The present invention will be described in more detail below with reference to examples, but these examples are not intended to limit the present invention to any particular form. In the following examples, a glass plate was used as the glass substrate.

[0073] (Heat treatment before measurement) Glass articles with EasyClean coating underwent heat treatment before their properties were evaluated. The heat treatment was performed by heating them in an electric furnace set to 760°C for 4 minutes, then removing them from the furnace, wrapping them in ceramic wool, and cooling them to room temperature at a rate that did not cause thermal cracking. After heat treatment, the coated glass articles were left in ambient air at room temperature for at least 7 days, after which their properties were evaluated.

[0074] (Water contact angle) The water contact angle was measured using a contact angle measuring instrument (DMs-401, manufactured by Kyowa Interface Science Co., Ltd.) by dropping 4 mg of purified water onto the coating surface.

[0075] (Abrasion resistance) The abrasion resistance test of the Easy Clean coating using steel wool was conducted in accordance with the EN1096-2:2001 abrasion resistance test, except that grade No. 0000 steel wool was used instead of a felt pad. Specifically, an abrasion testing machine (Shinto Kagaku Co., Ltd., Haydon Tribostation Type 32) was used, and the steel wool was pressed against the Easy Clean coating surface while applying a load of 4N, and the test was performed by 500 reciprocations (Class A). The steel wool was attached to the head of the abrasion testing machine. The size of the part of the head that contacts the film under test was 20 x 20 mm. Steel wool with dimensions of 140 mm (length) x 270 mm (width) and a thickness of 75 mm (TRUSCO Nakayama Co., Ltd., TSW0000-200) was attached to the head. The amount of steel wool was adjusted so that it was approximately 0.2 g when converted to a 20 x 20 mm size with a thickness of 75 mm. The wear testing machine was set up so that the head would move at a speed of 6000 mm / min over a distance of 100 mm one way.

[0076] An abrasion resistance test of the Easy Clean coating using a felt pad was also conducted. This abrasion resistance test was conducted in accordance with the EN1096-2:2001 abrasion resistance test, except that a condition of 10,000 reciprocations was adopted instead of the condition of 500 reciprocations (Class A). Specifically, an abrasion testing machine (Haydon Tribostation Type 32, manufactured by Shinto Kagaku Co., Ltd.) was used, and the felt pad was pressed against the Easy Clean coating surface while applying a load of 4N, and the test was performed by reciprocating 10,000 times. The felt pad was attached to the head of the abrasion testing machine. The size of the part of the head that contacted the film under test was 15 mm in diameter. The density of the felt pad was 0.5 g / cm³. 3 The wear testing machine was set up so that the head would move at a speed of 6000 mm / min over a distance of 100 mm one way.

[0077] The visible light transmittance was measured before and after the abrasion resistance test using the method described below, and the difference was calculated. The difference was calculated by subtracting the measurement value before the abrasion resistance test from the measurement value after the abrasion resistance test.

[0078] (Optical properties) Visible light transmittance was determined from the visible ultraviolet absorption spectrum measured with a spectrophotometer (Hitachi, Model 330). Haze rate was measured using a haze meter (Suga Test Instruments, Model HZ-V3).

[0079] (film thickness) The film thickness of the Easy Clean coating was measured by cross-sectional SEM observation. If the glass article had an underlayer (SiO2 layer), the thickness of the underlayer was also measured by cross-sectional SEM observation.

[0080] (Dirt adhesion test) Tap water was sprayed onto the coating surface of a coated glass object with its main surface facing vertically. The coated glass object was then held at room temperature for 10 minutes to allow the water droplets adhering to the coating surface to evaporate. After that, light from an LED light source was incident on the edge of the glass plate, and the coating surface was observed.

[0081] <Example 1> 3.33 g of cerium(III) nitrate hexahydrate (Ce(NO3)3·6H2O) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 98%), 2.48 g of diacetoxydirconium(IV) oxide (C4H6O5Zr) (manufactured by Tokyo Chemical Industry Co., Ltd., 20%), 67.2 g of acetylacetone, and 60 g of propylene glycol were dissolved in 267.0 g of a mixed solvent mainly composed of ethanol (manufactured by Futaba Chemical Co., Ltd., Fine Etah A-10) to obtain a coating solution. In the coating solution, the molar ratio of CeO2 to ZrO2 was 3.5:1. Next, the coating solution was aged by continuous stirring at 40°C for more than 15 hours. After aging, the coating solution exhibited a pale yellow color.

[0082] High-transparency glass (OptiWhite®, manufactured by Nippon Sheet Glass Co., Ltd.: 3 mm thick, hereinafter referred to as "OPW") was used as the glass substrate. This glass plate was cut into 10 cm squares, washed, and dried. The aged coating solution was spray-applied to the glass plate. The coated glass article was subjected to the drying treatment described above. The coated glass article after drying was subjected to the heat treatment described above. This obtained the coated glass article of Example 1.

[0083] <Example 2> As the glass substrate, a glass with a silicon oxide (SiO2) layer formed on it (Pilkington OptiShower: SiO2 layer thickness 15 nm, hereinafter referred to as "OPS") was used, and a coating was formed on the SiO2 layer. Except for this, the coated glass article of Example 2 was obtained in the same manner as in Example 1.

[0084] <Example 3> The formulation of the coating solution was adjusted so that the molar ratio of CeO2 to ZrO2 was 6:1. OPS was used as the glass substrate, and the coating was formed on the SiO2 layer. Except for this, the coated glass article of Example 3 was obtained in the same manner as in Example 1.

[0085] <Example 4> The formulation of the coating solution was adjusted so that the molar ratio of CeO2 to ZrO2 was 9.3:1. OPS was used as the glass substrate, and the coating was formed on the SiO2 layer. Except for these steps, the coated glass article of Example 4 was obtained in the same manner as in Example 1.

[0086] <Example 5> The formulation of the coating solution was adjusted so that the molar ratio of CeO2 to ZrO2 was 1:1. OPS was used as the glass substrate, and the coating was formed on the SiO2 layer. Except for this, the coated glass article of Example 5 was obtained in the same manner as in Example 1.

[0087] <Example 6> The formulation of the coating solution was adjusted so that the molar ratio of CeO2 to ZrO2 was 0:1. In other words, the coating solution of Example 6 contained substantially no CeO2. OPS was used as the glass substrate, and the coating was formed on the SiO2 layer. Except for this, the coated glass article of Example 6 was obtained in the same manner as in Example 1.

[0088] <Comparative Example 1> The formulation was adjusted so that the molar ratio of CeO2 to ZrO2 in the coating solution was 1:0. In other words, the coating solution of Comparative Example 1 substantially contained no ZrO2. Except for this, the coated glass article of Comparative Example 1 was obtained in the same manner as in Example 1.

[0089] <Comparative Example 2> The formulation of the coating solution was adjusted so that the molar ratio of CeO2 to ZrO2 was 1:0. In other words, the coating solution of Comparative Example 2 substantially contained no ZrO2. OPS was used as the glass substrate, and the coating was formed on the SiO2 layer. Except for this, the coated glass article of Comparative Example 2 was obtained in the same manner as in Example 1.

[0090] For each of the examples and comparative examples, the water contact angle, visible light transmittance, etc., were measured using the method described above. The results are shown in Table 1. Table 1 also shows the measured values ​​on the surface of the glass substrate without coating, as reference examples 1 and 2.

[0091] [Table 1]

[0092] In the abrasion resistance test using steel wool, the absolute value of the difference in visible light transmittance in the example was 0.7% or less. In contrast, the absolute value of the difference in visible light transmittance in the comparative example was greater than 0.7%. The reason the difference in visible light transmittance was positive in the comparative example is that at least a portion of the coating peeled off after the abrasion resistance test, causing an increase in visible light transmittance. In the abrasion resistance test using felt pads, although individual data is omitted, the absolute value of the difference in visible light transmittance in the example was 0.22% or less, which was lower than the same absolute value (greater than 0.22%) in the comparative example.

[0093] Furthermore, in Examples 1-6, the water contact angle on the surface of the coating after heat treatment was in the range of 60° to 130°. Reflecting the higher water contact angle than that of the glass surface, the stain adhesion test results showed that in Examples 1-6 and Comparative Examples 1-2, the traces of water droplets were less noticeable than in Reference Examples 1-2. In Reference Examples 1-2, because no coating was formed, water easily adhered to the surface, resulting in traces of water droplets or water runoff over a wide area, giving a whitish appearance.

[0094] Furthermore, a comparison between Example 1 and Example 2 shows that using a glass substrate with an SiO2 layer formed as a base layer improves the water contact angle compared to when the coating is directly formed on the surface of the glass substrate. This is thought to be because the amorphous SiO2 layer suppresses the diffusion of alkaline components from the glass substrate to the coating. Unlike conventional Easy Clean coatings that use fluorine-containing organic compounds, the coating according to this embodiment can have good abrasion resistance even without forming an adhesion promoter layer underneath it (Example 1). In the coating according to this embodiment, the base layer functions not as an adhesion promoter layer, but as a diffusion prevention layer. This diffusion prevention layer suppresses the penetration of alkaline components diffusing from the glass substrate into the coating during heat treatment, and can contribute to maintaining the water repellency of the surface (Example 2).

[0095] For Example 1 and Comparative Example 1, the coating surface was observed using a scanning electron microscope (SEM) after the heat treatment described above. The results are shown in Figure 3 (Example 1) and Figure 4 (Comparative Example 1). No cracks were observed on the surface of the coating in Example 1. On the other hand, cracks were observed on the surface of the coating in Comparative Example 1. When the surfaces of the coatings in each example were observed in the same manner, all surfaces were substantially flat and no cracks were observed. [Explanation of Symbols]

[0096] 10,11 water droplets 20 Base material 21 Hydrophilic surface 22 Water-repellent surface 31,32 Tiny flow

Claims

1. The device comprises a glass substrate and an easy-clean coating on the glass substrate. The coating comprises zirconium oxide and rare earth element oxides. The water contact angle on the surface of the coating is 60° or more and 130° or less. The content of the rare earth element oxide in the coating is equal to or greater than the content of the zirconium oxide. Coated glass articles.

2. The absolute value of the difference in visible light transmittance before and after an abrasion resistance test on the coating, performed under the condition of 500 back-and-forth cycles in accordance with the abrasion resistance test of EN1096-2:2001, except that steel wool of grade No. 0000 was used instead of a felt pad, is 0.7% or less. A coated glass article according to claim 1.

3. The content of the oxide of the rare earth element in the coating is 10 mol% or more. A coated glass article according to claim 1 or 2.

4. The contact angle of the coated glass article after being subjected to a heat treatment at 760°C for 4 minutes is 60° or more and 130° or less. A coated glass article according to any one of claims 1 to 3.

5. The coating contains 5 mol% or more of zirconium oxide, A coated glass article according to any one of claims 1 to 4.

6. The glass substrate and the coating further comprise an underlayer, A coated glass article according to any one of claims 1 to 5.

7. The thickness of the underlying layer is in the range of 10 to 400 nm. The coated glass article according to claim 6.

8. The underlayer mainly contains SiO2, A coated glass article according to claim 7.

9. The underlying layer is amorphous, A coated glass article according to claim 7 or 8.

10. The glass substrate includes a dealkalization layer on the coated surface, A coated glass article according to any one of claims 1 to 5.

11. The glass substrate is tempered glass, A coated glass article according to any one of claims 1 to 10.

12. At least one selected from the group consisting of building glass, transport glass, store glass, furniture glass, home appliance glass, signage glass, mobile device glass and solar cell glass, A coated glass article according to any one of claims 1 to 11.

13. The coating has at least one function selected from the group consisting of anti-glare and anti-fogging. A coated glass article according to any one of claims 1 to 12.

14. The coated glass article according to any one of claims 1 to 13, wherein the coating substantially does not contain a fluoroalkyl group-containing compound.

15. The coated glass article according to any one of claims 1 to 14, wherein the coating is a single layer film.

16. The coated glass article according to any one of claims 1 to 15, wherein the film thickness of the coating is 10 nm or more and 300 nm or less.

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