Vehicle window glass with shielding layer, and method for manufacturing vehicle window glass with shielding layer

Abstract

This vehicle window glass with a shielding layer comprises a vehicle window glass and a shielding layer that is provided on a main surface of the vehicle window glass and that includes an inkjet ink cured film, wherein the inkjet ink cured film includes a first part in which a graph that has a vertical axis representing a common logarithm logT of a light transmittance T (%) and that has a horizontal axis representing a distance d (mm) along the surface direction has a slope of 0.001-0.0225 / mm.

Description

Vehicle window glass with shielding layer and method for manufacturing vehicle window glass with shielding layer

[0001] This disclosure relates to a vehicle window glass with a shielding layer and a method for manufacturing a vehicle window glass with a shielding layer. This application claims priority to Japanese Patent Application No. 2024-069795, filed in Japan on April 23, 2024, the contents of which are incorporated herein by reference.

[0002] A vehicle window glass with a shielding layer is known, in which a shielding layer is provided on a main surface of the vehicle window glass. The shielding layer is provided, for example, in a strip-like shape in the peripheral region of the main surface for the purpose of protecting a sealant that attaches and holds the vehicle window glass to a vehicle body from light. A common method for forming a shielding layer on a vehicle window glass is to apply a paste-like colored ink containing glass frit to the vehicle window glass by screen printing, followed by baking. Another known method involves spraying the ink by airbrush printing, as described in Patent Document 1, for example.

[0003] For vehicle window glass with a shielding layer, there is also a known technique for making the inner peripheral edge of the shielding layer less noticeable. For example, Patent Document 1 describes that an obscuration band (shielding layer) has a fade-out region in which light transmittance increases toward the inside of the vehicle window glass. Patent Document 1 also suggests that ink spraying can produce a smoother change in light transmittance in the fade-out region than screen printing.

[0004] Special Publication No. 2010-506793

[0005] In recent years, in response to high demands for the design of the shielding layer, there has been a demand for a technology for forming a shielding layer including a portion in which the light transmittance changes more minutely along the surface direction. However, in the ink spray method described in Patent Document 1, atomized ink is scattered over a relatively wide area with a single spray operation, and therefore there is a limit to how finely the change in light transmittance in the fade-out region can be adjusted.

[0006] In view of the above, one aspect of the present disclosure aims to provide a vehicle window glass with a shielding layer, which has a shielding layer including a portion in which the light transmittance changes more minutely in the plane direction than in conventional techniques, and a method for manufacturing a vehicle window glass with a shielding layer.

[0007] A vehicle window glass with a shielding layer according to one aspect of the present disclosure comprises: a vehicle window glass; and a shielding layer provided on a main surface of the vehicle window glass, the shielding layer including an inkjet ink cured film, wherein the inkjet ink cured film includes a first portion in which the slope of a graph, with the vertical axis representing the common logarithm log T of light transmittance T (%) and the horizontal axis representing the distance d (mm) along the surface direction, is 0.001 / mm or more and 0.0225 / mm or less.

[0008]

[0013] Furthermore, a vehicle window glass with a shielding layer according to one aspect of the present disclosure includes a vehicle window glass and a shielding layer provided on a main surface of the vehicle window glass, the shielding layer including an inkjet ink cured film, the inkjet ink cured film including a first portion having a thickness gradient in a surface direction of 0.0001 μm / mm or more and 0.15 μm / mm or less.

[0009] Furthermore, a method for manufacturing a vehicle window glass with a shielding layer according to an aspect of the present disclosure includes forming an inkjet ink film on a main surface of the vehicle window glass by inkjet printing, and curing the inkjet ink film to obtain a shielding layer including a cured inkjet ink film, wherein the cured inkjet ink film includes a first portion in which the slope of a graph, with the common logarithm log T of light transmittance T (%) as the vertical axis and the distance d (mm) along the surface direction as the horizontal axis, is 0.001 / mm or more and 0.0225 / mm or less.

[0010] According to one aspect of the present disclosure, it is possible to provide a vehicle window glass with a shielding layer, which has a shielding layer including a portion in which the light transmittance changes more minutely in the plane direction than in conventional techniques, and a method for manufacturing a vehicle window glass with a shielding layer.

[0011] 1 is a plan view of a vehicle window glass with a shielding layer according to an embodiment of the present disclosure; FIG. 2 is an enlarged view of a portion I in FIG. 1; FIG. 3 is an enlarged view of a shielding layer formed using screen printing according to conventional technology; FIG. 4 is a result of Experimental Example 1, where (a) is a photograph of an inkjet ink film of an example, and (b) is a photograph of an ink film of a comparative example; FIG. 5 is a result of Experimental Example 2, a graph showing the common logarithm logT of measured values ​​of light transmittance versus the distance from the printing start position; and FIG. 6 is a result of Experimental Example 2, a graph showing measured values ​​of film thickness versus the distance from the printing start position.

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, and descriptions thereof may be omitted.

[0013] [Vehicle Window Glass with Shielding Layer] Fig. 1 is a plan view of a vehicle window glass 1 with a shielding layer according to one embodiment of the present disclosure, as viewed from the vehicle interior side. In the embodiment shown in Fig. 1 , a shielding layer 20 is formed in the peripheral region of the vehicle interior surface of the vehicle window glass 10, but the shielding layer 20 may be formed in a region other than the peripheral region of the main surface of the vehicle window glass 10. Fig. 1 also shows a component 30 to be attached to the main surface of the vehicle window glass 10. The component 30 shown in Fig. 1 is a bracket for a rain sensor. The shielding layer 20 may also be provided in a component attachment region including a region to which the component 30 is bonded. That is, the shielding layer 20 may be provided in the peripheral region and / or the component attachment region of the vehicle window glass 10.

[0014] Examples of the component 30 to be attached to the main surface of the vehicle window glass 10 include a bracket for attaching information acquisition devices such as a sensor, a camera, or a communication device, and an attachment base such as a mirror base for attaching a rearview mirror.

[0015] <Vehicle Window Glass> The vehicle window glass used in this embodiment is not particularly limited as long as it is a window glass included in a vehicle such as an automobile or a railway vehicle, but is preferably a window glass for an automobile. The vehicle window glass 10 shown in Fig. 1 is a windshield for an automobile. The vehicle window glass 10 is not limited to a windshield, and may be a rear window, a side window, a roof window, etc.

[0016] The vehicle window glass 10 may be a single-pane glass consisting of a single glass plate. Alternatively, the vehicle window glass 10 may be a laminated glass formed by bonding together a plurality of glass plates, for example, a vehicle interior glass plate and a vehicle exterior glass plate bonded together via an interlayer film. In either the single-pane glass or laminated glass, the glass plate used may be soda-lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, borosilicate glass, or the like. The glass plate forming method is not particularly limited, but a float method is preferred. The glass plate may be untempered or may be tempered glass that has been subjected to air-cooling or chemical tempering treatment.

[0017] The vehicle window glass is preferably transparent, but may be a glass plate that is colored to such an extent that transparency is not impaired. The shape of the glass plate is not particularly limited to a rectangular shape, and may be processed into various shapes. Furthermore, the glass plate used for the vehicle window glass may be bent and curved.

[0018] When the vehicle window glass 10 is a laminated glass, the material of the interlayer film disposed between the plurality of glass sheets is not particularly limited. Preferred materials for the interlayer film are thermoplastic resins such as ethylene vinyl acetal and polyvinyl butyral.

[0019] When the vehicle window glass 10 is a single-pane glass, its thickness may be 0.2 mm or more and 5 mm or less. When the vehicle window glass 10 is a laminated glass, the overall thickness of the vehicle window glass 10 (including the thickness of the interlayer film) may be 2.3 mm or more and 8 mm or less. Each of the multiple glass plates constituting the laminated glass may have a thickness of 0.5 mm or more and 3.5 mm or less. The thicknesses of the multiple glass plates may be the same or different from one another.

[0020] <Shielding Layer> The shielding layer 20 is provided on a main surface of the vehicle window glass 10. In the embodiment shown in Fig. 1 , the shielding layer 20 is provided on the vehicle interior surface of the vehicle window glass 10. The surface of the vehicle window glass 10 on which the shielding layer 20 is provided is not particularly limited, but it is preferably provided on the vehicle interior surface. Furthermore, when the vehicle window glass 10 is laminated glass, the vehicle exterior surface of the vehicle exterior glass plate is defined as a first surface, the vehicle interior surface of the vehicle exterior glass plate is defined as a second surface, the vehicle exterior surface of the vehicle interior glass plate is defined as a third surface, and the vehicle interior surface of the vehicle interior glass plate is defined as a fourth surface, and the shielding layer 20 is preferably formed on the second surface and / or the fourth surface, more preferably on the fourth surface.

[0021] The shielding layer 20 is a layer that has a light-blocking function, particularly a function of blocking ultraviolet and / or visible light. The region where the shielding layer 20 is provided has reduced transparency, i.e., low light transmittance. The shielding layer 20 can, for example, prevent the sealant (adhesive) that attaches and holds the vehicle window glass 10 to the vehicle body from being deteriorated by ultraviolet light. The shielding layer 20 can also make the sealant, the component 30 such as a bracket, the equipment supported by the component 30, and the conductive layer of the antenna, etc., less visible from outside the vehicle.

[0022] The shielding layer 20 may be a dark color such as black, gray, or dark brown. The shielding layer 20 may be a color conforming to CIE 1976 (L) standardized by the International Commission on Illumination (CIE). ＊ a ＊ b ＊ ) Lightness index L in color space (CIELAB) ＊ The color may have a value of 0 or more and 30 or less. This allows the shielding layer 20 to fully exhibit the above-described function of shielding light.

[0023] The light transmittance of the shielding layer 20 is preferably 30% or less, more preferably 20% or less, even more preferably 10% or less, still more preferably 3% or less, particularly preferably 1% or less, and may be 0.3% or less. The light transmittance of the cured ink-jet ink film described below is also preferably 30% or less, more preferably 20% or less, even more preferably 10% or less, still more preferably 3% or less, particularly preferably 1% or less, and may be 0.3% or less. Note that the light transmittance in this specification may be the light transmittance of ultraviolet light and / or visible light, which can be measured using, for example, a spectrophotometer, and may preferably be the total light transmittance of visible light.

[0024] The shielding layer 20 in this embodiment includes a cured inkjet ink film, and is preferably made of a cured inkjet ink film. The "cured inkjet ink film" is a film formed by curing an inkjet ink film formed on the vehicle window glass 10 by inkjet printing. Curing the inkjet ink film may include drying and / or baking the inkjet ink film.

[0025] The ink used in inkjet printing, i.e., inkjet ink (described in detail later), has a low viscosity, so that even if only a small amount of ink is applied to the vehicle window glass 10, it can immediately spread in the surface direction after application to form a thin, continuous ink film. "Continuous" means that the vehicle window glass 10 is completely covered over the entire area where the shielding layer 20 is provided. A continuous film is a so-called solid film. A continuous inkjet ink cured film can be obtained by curing the continuous inkjet ink film.

[0026] The thickness of the cured inkjet ink film may be preferably 0.1 μm or more and 15 μm or less, more preferably 1 μm or more and 15 μm or less. As such, the cured inkjet ink film is thinner than films formed by conventional methods such as screen printing, and therefore does not create an unnatural appearance such as the shielding layer 20 appearing raised. Furthermore, when the vehicle window glass 10 is laminated glass and the shielding layer 20 is formed inside the laminated glass, for example, even when the shielding layer 20 is formed on the second surface and / or the third surface of the laminated glass, the step at the boundary between the region where the shielding layer 20 is disposed and the region where the shielding layer 20 is not disposed is small, thereby reducing light scattering near the boundary.

[0027] The continuous inkjet ink cured film described above is different from the discontinuous film formed by conventional screen printing, which is composed of scattered, spaced-apart dot-like film portions. A continuous film appears smooth without graininess when observed by a normal method, which makes a good impression on the observer and is therefore preferable in terms of design.

[0028] Inkjet printing ejects minute ink droplets onto a printing surface from nozzles arranged at narrow intervals in the width direction perpendicular to the printing direction. Because the volume of ejected ink droplets can be adjusted for each nozzle, the amount of ink deposited on the printing surface can be varied for each minute region. Therefore, by slightly changing the amount of ink ejected in the printing direction, it is possible to gradually change the light transmittance and / or film thickness of the cured inkjet ink film in the printing direction, i.e., with a small gradient. Such changes in the light transmittance and / or film thickness of the cured inkjet ink film can appear virtually stepless to the naked eye. With conventional ink spraying methods, ink is dispersed over a relatively wide area with each spray, making it difficult to gradually change the amount of ink deposited on the printing surface in a predetermined direction, and thus difficult to finely adjust the light transmittance and / or film thickness of the shielding layer 20. Therefore, the inkjet ink cured film formed using inkjet printing allows for a wider range of adjustment of the light transmittance and / or film thickness of the shielding layer 20, enabling a variety of designs not possible with conventional methods.

[0029] Furthermore, a configuration formed by inkjet printing has manufacturing advantages over conventional ink spraying methods. In the ink spraying method, atomized ink is sprayed from a nozzle toward a surface to be printed, which makes it easy for the ink to scatter and makes it difficult to control the extent to which the ink spreads. Therefore, it is difficult to print the ink accurately in the target area, i.e., without leaving any residue and without spilling over. While masking or other techniques can be used to accurately print the ink in the target area, this would significantly complicate the manufacturing process. The shielding layer 20 including the film obtained by inkjet printing according to this embodiment can be formed using a simpler process than conventional techniques.

[0030] Fig. 2 shows an enlarged view of portion I in Fig. 1. As shown in Fig. 1 and Fig. 2, the shielding layer 20 may include a first portion 21 whose light transmittance gradually changes in one direction and a second portion 22 whose light transmittance is uniform. The first portion 21 is also called a gradually changing light transmittance portion, and the second portion 22 is also called a uniform light transmittance portion.

[0031] In this specification, the side closer to the edge of the vehicle window glass 10, i.e., the side closer to the peripheral edge, is referred to as the outer side of the vehicle window glass, and the side closer to the central region of the vehicle window glass 10 is referred to as the inner side. As shown in Figures 1 and 2 , the first portion 21 forms an inner portion of the shielding layer 20, and the second portion 22 forms an outer portion of the shielding layer 20. The inner edge of the first portion 21 constitutes the inner edge of the shielding layer 20. The outer edge of the first portion 21 is in contact with the inner edge of the second portion 22. It is preferable that there is no gap between the first portion 21 and the second portion 22, that is, the first portion 21 and the second portion 22 are formed continuously. In the embodiment shown in Figure 1 , the outer edge of the second portion 22 overlaps the edge of the vehicle window glass 10, but this overlap is not necessarily required, and a region without a shielding layer may be formed outside the second portion 22.

[0032] In the embodiment shown in Fig. 2, the transparency of the first portion 21 gradually improves toward the inside of the shielding layer 20 (in the direction away from the peripheral edge of the vehicle window glass 10), i.e., the light transmittance increases. This makes it possible to make the inner edge of the shielding layer 20 less noticeable. Window glass is originally transparent and allows people to see the scenery outside the vehicle through the window glass, so when dark-colored materials come into people's field of vision, they tend to feel strange or uncomfortable. However, the shielding layer 20 of this embodiment reduces such strange or uncomfortable feeling. Furthermore, the gradual change in light transmittance in the inner portion of the shielding layer 20 also improves design.

[0033] The shielding layer 20 includes a cured ink-jet ink film formed by inkjet printing, and the cured ink-jet ink film includes a first portion 21 and a second portion 22. In other words, both the first portion 21 and the second portion 22 include the cured ink-jet ink film. By having the first portion 21 include, and preferably be made of, the light transmittance of the first portion 21 can be gradually increased from the outside to the inside of the vehicle window glass 10 with an even more subtle change or an even smaller gradient. This gives the shielding layer 20 an appearance in which the layer near the inner edge naturally fades toward the inside, thereby improving the effect of reducing the strange or uncomfortable feeling described above.

[0034] Furthermore, since the first portion 21 is a cured inkjet ink film, it can be a continuous film. That is, the first portion 21 is formed as a continuous film with a subtle or small gradient change in light transmittance. Such a continuous film is different from the discontinuous film obtained when conventional screen printing is used. For reference, FIG. 3 shows a conventional shielding layer 20' formed using screen printing. The shielding layer 20' shown in FIG. 3 includes a uniform light transmittance portion 2' having a uniform light transmittance and a gradually changing light transmittance portion 1' having a gradually changing light transmittance along one direction. However, the gradually changing light transmittance portion 1' is formed from dot-like film portions spaced apart from each other. In the case of a discontinuous film made up of scattered dot-like film portions according to the conventional technology, the light transmittance also changes in a direction perpendicular to the direction from the outside to the inside (hereinafter referred to as the outside-inside direction). As a result, the appearance of the gradually changing light transmittance portion 1' may appear grainy both in the outside-inside direction and in the direction perpendicular to the outside-inside direction. In contrast, the first part 21 of the shielding layer 20 in this embodiment does not cause or can suppress changes in light transmittance in a direction perpendicular to the outside-inside direction, so the above-mentioned granular feeling is suppressed and the impression of a smooth change in light transmittance is obtained.

[0035] Furthermore, in the case of a configuration in which the shielding layer 20 is obtained by baking the ink, distortion may occur in the vehicle window glass 10 near the boundary between the region where the shielding layer 20 is disposed and the region where the shielding layer 20 is not disposed, i.e., near the inner edge of the shielding layer 20, due to the difference in thermal expansion coefficient between adjacent regions depending on whether the shielding layer 20 is present or not. According to this embodiment, in the first portion 21, which is the inner part of the shielding layer 20, the amount of ink attached gradually decreases toward the inside, and the thickness of the inkjet ink cured film gradually decreases, so that the above-mentioned distortion can be suppressed. Furthermore, by forming the inkjet ink cured film as a continuous film, the thermal expansion coefficient also changes smoothly in the outward and inward directions in the first portion 21, so that the distortion prevention effect can be further improved.

[0036] The slope of a graph (hereinafter also referred to as (ΔlogT / Δd)) in which the light transmittance of the first portion 21 is T (%), log T is the vertical axis, and the distance d (mm) along the surface direction is the horizontal axis is 0.001 / mm or more and 0.0225 / mm or less. In this specification, log represents common logarithm. The slope of the graph may be preferably 0.002 / mm or more and 0.0225 / mm or less, more preferably 0.005 / mm or more and 0.0225 / mm or less. In this manner, in the first portion 21, logT changes minutely with a predetermined slope with respect to the distance d (mm) along the surface direction. This provides an appearance in which the shielding layer 20 fades out near the inner edge, i.e., gradually and naturally disappears as it approaches the inside. This further improves the aforementioned effect of reducing the sense of incongruity or discomfort. Furthermore, the aforementioned effect of preventing distortion of the vehicle window glass is further improved. The slope of a graph in which the vertical axis represents log T in the plane direction and the horizontal axis represents the distance d along the plane direction may be the slope (Δlog T / Δd) in the direction from the outside to the inside or from the inside to the outside of the vehicle window glass 10, as shown in Figures 1 and 2. The slope (Δlog T / Δd) in the plane direction may be a measured value preferably within a range of 5 mm or less, more preferably 1 mm or less.

[0037] Furthermore, the thickness gradient of the first portion 21 in the surface direction is 0.0001 μm / mm or more and 0.15 μm / mm or less. The thickness gradient may be preferably 0.001 μm / mm or more and 0.15 μm / mm or less, more preferably 0.002 μm / mm or more and 0.15 μm / mm or less. The thickness gradient is the rate of change in thickness (μm) per mm along the surface direction. The thickness gradient may be the absolute value of the slope of a graph with thickness (μm) as the vertical axis and distance d (mm) along the surface direction as the horizontal axis. In this way, the film thickness of the first portion 21 varies minutely with a predetermined gradient, resulting in an appearance in which the shielding layer 20 fades out near the inner edge, i.e., an appearance in which the shielding layer gradually and naturally disappears as it approaches the inside, further improving the aforementioned effect of reducing discomfort or discomfort. Furthermore, the aforementioned effect of preventing distortion of the vehicle window glass is further improved. The thickness gradient in the plane direction may be a thickness gradient in a direction from the outside to the inside or from the inside to the outside of the vehicle window glass 10, as shown in Figures 1 and 2. The thickness gradient in the plane direction may be a measured value preferably within a range of 5 mm or less, more preferably 1 mm or less.

[0038] The shielding layer 20 may contain a film obtained by a means other than inkjet printing in addition to the inkjet ink cured film, but is preferably made of the inkjet ink cured film. In this case, it is particularly preferable that the first portion 21, whose light transmittance gradually changes, is made of the inkjet ink cured film.

[0039] [Method for manufacturing vehicle window glass with a shielding layer] One embodiment of the present disclosure is a method for manufacturing the above-mentioned vehicle window glass with a shielding layer 1. Specifically, the method for manufacturing a vehicle window glass with a shielding layer includes: (a) forming an inkjet ink film (uncured film) on a main surface of the vehicle window glass by inkjet printing; and (b) curing the inkjet ink film to obtain a shielding layer including a cured inkjet ink film, wherein the cured inkjet ink film includes a first portion in which the slope of a graph, with the common logarithm log T of light transmittance T (%) as the vertical axis and the distance d (mm) along the surface direction as the horizontal axis, is 0.001 / mm or more and 0.0225 / mm or less.

[0040] <(a) Inkjet ink film formation> In the manufacturing method according to this embodiment, first, an inkjet ink film is formed on the main surface of the vehicle window glass. An inkjet printing device is used to form the inkjet ink film. The printing method of the inkjet printing device is not particularly limited, and may be a piezo type, thermal type, bubble type, or electrostatic actuator type, but a piezo type is preferred because it is easy to control the amount of ink ejected and there is a high degree of freedom in selecting the ink.

[0041] The inkjet printing apparatus used in this embodiment has a resolution of 120 dpi or more and 2400 dpi or less. The volume of ink droplets ejected from the inkjet printing apparatus is 2 pL or more and 240 pL or less. The thickness of the inkjet ink film, and thus the thickness of the inkjet ink cured film, can be controlled by changing one or more of the resolution, the volume of the ink droplets, the viscosity of the ink used, and the diameter of the particles contained in the ink.

[0042] <<Inkjet Ink>> The ink used in the inkjet ink film formation step may be either an inorganic ink or an organic ink, as long as it is an ink that can be printed by the inkjet method. In either the case of an inorganic ink or an organic ink, the viscosity of the inkjet ink used may be preferably from 1 mPa·s to 50 mPa·s, and more preferably from 1.5 mPa·s to 30 mPa·s. Ink having a viscosity within the above range makes it easier for adjacent ink droplets to bond together after deposition to form a continuous inkjet ink film of an appropriate thickness, which in turn makes it easier to form a continuous inkjet ink cured film of an appropriate thickness.

[0043] The inorganic ink contains, in addition to glass frit, an inorganic material powder, specifically a metal oxide powder, as a pigment. The inorganic ink is printed on a vehicle window glass to form an ink film, which is then cured by baking to form a cured inkjet ink film.

[0044] Specific examples of pigments contained in inorganic ink include CuO.Cr ２ O ３(Black), CoO・Cr ２ O ３ (Black), Fe ２ O ３ (Brown), TiO ２ (White), CoO・Al ２ O ３ (Blue), NiO・Cr ２ O ３ Among these, it is preferable to contain a black pigment.

[0045] The pigment for forming a black ceramic layer is preferably an oxide of at least one metal selected from the group consisting of Cu, Fe, Co, Ni, Cr, Si, Mn, Al, and Zn, more preferably a composite oxide pigment containing two or more of these metals, and more preferably Cu(Cr,Mn) ２ O ４ , CuCrO ４ , Cr ２ O ３ : Fe ２ O ３ , Cr ２ O ３ : Fe ２ O ３ :CoO, (Fe, Mn) (Mn, Fe) ２ O ４ , (Co, Fe) (Fe, Cr) ２ O ４ , (Co, Fe, Mn) (Fe, Cr, Mn) ２ O ４ , (Co, Fe) (Ni, Cr) ２ O ４ and (Cu, Fe, Mn) (Fe, Mn, Al) ２ O ４ More preferred is at least one composite oxide pigment selected from the group consisting of:

[0046] In addition to the glass frit and pigment, the inorganic ink may further contain a filler. Examples of fillers include crystallization accelerators and so-called low-expansion fillers. The addition of a crystallization accelerator is preferable when increasing the crystallized region of the cured inkjet ink film. The crystallized region is formed by heat-treating the inkjet ink film formed by inkjet printing at a temperature higher than the crystallization temperature of the glass frit when it is baked. When a crystallization accelerator is included, the crystallization accelerator acts as a crystal nucleus, and crystallization begins at a temperature lower than the crystallization temperature, thereby increasing the crystallized region. The type of crystallization accelerator varies depending on the composition of the glass frit. For example, when the glass frit contains Bi, a bismuth silicate-based crystallization accelerator is preferable. Furthermore, when the crystalline phases have similar patterns, crystallization may be promoted even if the compositions are different.

[0047] Examples of low expansion fillers include cordierite, zircon, alumina, titania, zirconium phosphate, silica, and forsterite. One of these may be used alone, or two or more may be mixed together. Among these, it is more preferable to use at least one selected from the group consisting of cordierite, zircon, and silica. The inorganic ink may further contain an oxidizing agent. Conventionally known oxidizing agents can be used, and specific examples include CeO ２ , MnO ２ etc.

[0048] The D90 of particles contained in the inorganic ink (hereinafter referred to as contained particles) may preferably be less than 3 μm, more preferably 2 μm or less. D90 is the 90% cumulative particle diameter based on area. When the D90 of the contained particles is within the above range, a relatively thin inkjet ink film, and ultimately an inkjet ink cured film, can be obtained. Furthermore, the surface roughness Ra of the inkjet ink cured film obtained after curing can also be reduced. The contained particles include glass frit and pigment.

[0049] The organic ink is an ink that contains a resin in addition to a pigment, and optionally contains a dispersant, a solvent, etc. The organic ink is printed on a vehicle window glass to form an inkjet ink film, which is then cured by heat and / or light to form a cured inkjet ink film.

[0050] The pigment contained in the organic ink may be any of organic pigments, organic dyes, and inorganic pigments, and may be used alone or in combination of two or more. The pigment is preferably at least one pigment selected from the group consisting of carbon black, graphite, and metal oxides, and more preferably carbon black.

[0051] The resin may be any of a thermoplastic resin, a photocurable resin, and a thermosetting resin, with thermosetting resins and photocurable resins being preferred. Specific examples of resins include polyurethane resins, phenolic resins, epoxy resins, urea melamine resins, silicone resins, phenoxy resins, methacrylic resins, acrylic resins, polyarylate resins, polyester resins, polyolefin resins, polystyrene resins, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, polyvinyl acetate, polyvinylidene chloride, polycarbonate, polyethylene terephthalate, polyethersulfone, acrylonitrile-butadiene-styrene (ABS) resins, transparent ABS resins, celluloses, and polyacetals, among other known resins. The resin may be a homopolymer resin or a copolymer of a monomer of the homopolymer resin and a copolymerizable monomer. The above resins may be used alone or in combination of two or more.

[0052] When the resin contains a photocurable resin, the organic ink may further contain a photopolymerization initiator. The photocurable resin is preferably an acrylic resin.

[0053] Furthermore, when the resin contains a thermosetting resin, the thermosetting temperature of the organic ink may be preferably 100° C. or higher and 500° C. or lower, more preferably 150° C. or higher and 400° C. or lower. As the thermosetting resin, an acrylic resin, a silicone resin, or the like is preferred.

[0054] Examples of dispersants include cellulose derivatives, organic acids, and terpene compounds. The organic acid may be, for example, an unsaturated carboxylic acid polymer. The dispersants may be used alone or in combination of two or more. Examples of solvents include known solvents such as water, alcohols, esters, ketones, aromatic hydrocarbon solvents, and aliphatic hydrocarbon solvents. Examples of alcohols that can be used include isopropyl alcohol, methanol, and ethanol. Examples of esters that can be used include ethyl acetate. Examples of ketones that can be used include methyl ethyl ketone. Examples of aromatic hydrocarbon solvents that can be used include toluene, xylene, Solvesso™ 100, and Solvesso™ 150. Examples of aliphatic hydrocarbon solvents that can be used include hexane. Examples of solvents that can be used alone or in combination of two or more.

[0055] <(b) Curing of Inkjet Ink Film> After the inkjet ink film has been formed on the main surface of the vehicle window glass as described above, the inkjet ink film is cured. The curing method is determined depending on the ink used in inkjet printing. When the ink is an inorganic ink, curing can be performed by baking. In this case, the inkjet ink film may be dried before curing. The baking temperature of the inkjet ink film may be preferably 550°C or higher and 800°C or lower, more preferably 570°C or higher and 750°C or lower. The inkjet ink film can be baked, for example, by using a heating furnace such as an IR furnace on the vehicle window glass on which the inkjet ink film has been formed. When baking is performed, the manufacturing method according to this embodiment may include a step of cooling the vehicle window glass on which the cured inkjet ink film has been formed after baking.

[0056] Furthermore, when the ink is an organic ink, curing can be carried out by applying light and / or heat. When the ink is an organic ink, the curing method is determined depending on the type of resin contained in the organic ink. Curing using light can be, for example, curing by ultraviolet irradiation. Light can be applied using, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, or an LED having a wavelength range effective for curing the resin, and heat can be applied using, for example, an IR lamp, a hot air heating oven, or an induction heating device.

[0057] When the vehicle window glass with a shielding layer is curved glass, the manufacturing method for the vehicle window glass with a shielding layer according to this embodiment may include a bending step of curving the vehicle window glass. This bending step may be performed before or after the (a) inkjet ink film forming step. Furthermore, it may be performed before or after the (b) inkjet ink film curing step, or may be performed during the inkjet ink film curing step.

[0058] The bending process may be performed by gravity forming or press forming. The bending process may be a single-bend process in which the vehicle window glass 10 is bent in only one direction, or a compound-bend process in which the vehicle window glass 10 is bent in two directions perpendicular to each other. The radius of curvature of the curved vehicle window glass obtained through the bending process may be 500 mm or more and 100,000 mm or less.

[0059] Furthermore, when the vehicle window glass 10 is laminated glass and the shielding layer 20 is formed inside the laminated glass, for example, on the second and / or third surfaces, the lamination step of laminating multiple glass sheets together via an interlayer film is performed after the (b) inkjet ink film curing step. When the vehicle window glass 10 is laminated glass and the shielding layer 20 is provided on a surface other than the second and / or third surface, the lamination step can be performed before the (a) inkjet ink film forming step. Furthermore, the bending step described above may be performed before or after the lamination step. However, if the bending step is performed after the lamination step, there is a risk that the interlayer film will peel off from the glass sheets, so it is preferable to perform the bending step before the lamination step.

[0060] Experimental Examples 1 and 2 are shown below. The following inks and glass samples were used in the experiments.

[0061] <Ink> Inkjet ink IJ1 (Torrecid, SA, for tempered glass), black inorganic ink Spray ink SP1 (Daiso Industries Co., Ltd., spray can), black organic ink <Glass sample> Flat green glass (AGC Inc.), 100 mm long x 100 mm wide x 3.5 mm thick

[0062] [Experimental Example 1] Example 1-1 is an example, and Example 1-2 is a comparative example.

[0063] <Sample Preparation> (Example 1-1) A 90 mm x 90 mm target area for ink film formation was set at a position spaced from the periphery of one main surface of a glass sample. Inkjet ink IJ1 was printed at a constant density in this target area for ink film formation using an inkjet printing device (Digital LAB Ceramic, manufactured by THIEME GmbH & Co. KG). Figure 4(a) shows a portion of a photograph of an inkjet ink film 20a formed on a glass sample 100.

[0064] Example 1-2 As an alternative to airbrush printing, spray ink SP1 stored in a spray can was sprayed onto the same ink film formation target area as in Example 1-1 without masking, etc. Figure 4(b) shows a portion of a photograph of the ink film 20a' formed on the glass sample 100.

[0065] In the sample of Example 1-1 shown in Figure 4(a), inkjet printing allowed for the formation of an ink film 20a that roughly matched the ink film formation target area FT. In contrast, as shown in Figure 4(b), the edge of the ink film 20a' obtained by spraying in Example 1-2 did not follow the boundary of the ink film formation target area FT, with some overflowing and some unpainted areas. It was found that it was difficult to accurately form an ink film in the desired area without masking.

[0066] [Experimental Example 2] Examples 2-1 to 2-3 are all examples of the present invention.

[0067] <Sample Preparation> (Examples 2-1 and 2-2) Using an inkjet printing apparatus (Digital LAB Ceramic, manufactured by THIEME GmbH & Co. KG), inkjet ink IJ1 was printed on one of the main surfaces of two glass samples with a printing width of 200 mm in an area extending from the printing start position to 125 mm along the printing direction, so as to form a gradation in which the color gradually becomes lighter along the printing direction, thereby forming a continuous, i.e., solid, inkjet ink film. The inkjet ink film was dried at 120°C for 15 minutes and then baked at 670°C to form a cured inkjet ink film.

[0068] Example 2-3 A sample was prepared in the same manner as in Examples 2-1 and 2-2, except that a solution (50% by volume) of the inkjet ink IJ1 diluted with a cleaning solvent specifically for inkjet printing (manufactured by Torrecid, SA) was used instead of the inkjet ink IJ1.

[0069] [Measurement] <Transmittance> For the cured inkjet ink film of each example, the visible light transmittance T (%) was measured from the printing start position along the printing progression direction using a spectrophotometer (UH4150 ultraviolet-visible-near-infrared spectrophotometer, manufactured by Hitachi, Ltd.). Specifically, the measurement value obtained by aligning one side of a 25 mm × 25 mm square measurement area with a position 25 mm forward from the printing start position in the printing progression direction was defined as the measurement value at a distance of 25 mm from the printing start position. Thereafter, measurements were taken every time the measurement area was moved 25 mm. Fig. 5 shows a graph plotting the common logarithm logT of the measured visible light transmittance T (%) against the distance d (mm) from the printing start position at each measurement point.

[0070] <Film Thickness> In each example, the thickness of the cured inkjet ink film was measured from the printing start position along the printing progression direction using a surface roughness measuring instrument (SURFCOM NEX 001 DX-12, manufactured by Tokyo Seimitsu Co., Ltd.) Figure 6 shows a graph in which the measured film thickness of the cured inkjet ink film is plotted against the distance from the printing start position to each measurement point.

[0071] FIG. 5 shows that inkjet printing formed cured ink films whose visible light transmittance gradually changed along the surface direction. Furthermore, in Example 2-1, (Δlog T / Δd) was 0.0080 / mm, in Example 2-2, (Δlog T / Δd) was 0.0081 / mm, and in Example 2-3, (Δlog T / Δd) was 0.0087 / mm. Furthermore, FIG. 6 shows that inkjet ink cured films whose film thickness gradually changed along the surface direction were formed. Furthermore, in Example 2-1, cured ink films whose thickness gradient was approximately 0.00812 μm / mm, in Example 2-2, approximately 0.00737 μm / mm, and in Example 2-3, approximately 0.00778 μm / mm were formed.

[0072] Although the present disclosure has been described above based on the embodiments, the present disclosure is not limited to these embodiments. Furthermore, the above embodiments can be variously changed, modified, substituted, added, deleted, or combined within the scope of the claims, and these also fall within the technical scope of the present disclosure.

[0073] REFERENCE SIGNS LIST 1 Vehicle window glass with shielding layer 10 Vehicle window glass 20 Shielding layer 20a Inkjet ink film (uncured film) 21 First part 22 Second part 30 Part 100 Glass sample

Claims

1. A vehicle window glass with a shielding layer, comprising: a vehicle window glass; and a shielding layer provided on a main surface of the vehicle window glass, the shielding layer including a cured ink-jet ink film, wherein the cured ink-jet ink film includes a first portion in which the slope of a graph, with the common logarithm logT of light transmittance T (%) as the vertical axis and the distance d (mm) along the surface direction as the horizontal axis, is 0.001 / mm or more and 0.0225 / mm or less.

2. The vehicle window glass with a shielding layer according to claim 1, wherein the log T of the cured inkjet ink film gradually increases in a direction away from the peripheral edge of the vehicle window glass.

3. The vehicle window glass with a shielding layer according to claim 1 or 2, wherein the thickness of the inkjet ink cured film is 0.1 μm or more and 15 μm or less.

4. The vehicle window glass with a shielding layer according to claim 1 or 2, wherein the inkjet ink cured film further includes a second portion having uniform light transmittance in the surface direction.

5. The vehicle window glass with a shielding layer according to claim 1 or 2, wherein the light transmittance of the inkjet ink cured film is 30% or less.

6. A vehicle window glass with a shielding layer according to claim 1 or 2, wherein the thickness gradient in the surface direction of the first portion is 0.0001 μm / mm or more and 0.15 μm / mm or less.

7. A vehicle window glass with a shielding layer according to claim 1 or 2, wherein the shielding layer is provided in the peripheral region and / or the component mounting region of the vehicle window glass.

8. A vehicle window glass with a shielding layer, comprising: a vehicle window glass; and a shielding layer provided on a main surface of the vehicle window glass, the shielding layer including an inkjet ink cured film, wherein the inkjet ink cured film includes a first portion having a thickness gradient in the surface direction of 0.0001 μm / mm or more and 0.15 μm / mm or less.

9. A method for manufacturing a vehicle window glass with a shielding layer, comprising: forming an inkjet ink film on a main surface of the vehicle window glass by inkjet printing; and curing the inkjet ink film to obtain a shielding layer comprising a cured inkjet ink film, wherein the cured inkjet ink film comprises a first portion having a slope of 0.001 / mm or more and 0.0225 / mm or less when graphed with the common logarithm logT of light transmittance T (%) as the vertical axis and the distance d (mm) along the surface direction as the horizontal axis.

10. The method for manufacturing a vehicle window glass with a shielding layer according to claim 9, wherein the inkjet printing is carried out using ink having a viscosity of 1 mPa·s or more and 50 mPa·s or less.

11. The method for manufacturing a vehicle window glass with a shielding layer according to claim 9 or 10, wherein the inkjet printing is carried out using an inorganic ink containing particles with a D90 of less than 3 μm.

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