Substrate with coating film, method for forming coating film, and method for manufacturing substrate with coating film

Abstract

An insertion member (13) is inserted into a through hole (9) of a substrate (7), and the substrate (7) is subjected to electrostatic spray coating to form a coating film (8) on the substrate (7). The specific resistance of the insertion member (13) is 2.0 × 105 Ωcm or less, the thickness (T1) of the insertion member (13) is smaller than the thickness (T2) of the substrate (7), and the difference between the outer diameter (A1) of the insertion member (13) and the inner diameter (A2) of the through hole (9) is 8.0 mm or less.

Description

[Technical Field]

[0001] The present invention relates to a substrate with a coating film, a method for forming a coating film, and a method for producing a substrate with a coating film. [Background technology]

[0002] Electrostatic coating using electrostatic spraying is a well-known technique for forming a coating film on a substrate (see Patent Document 1). For example, Patent Document 1 describes setting the radius of curvature of the corners of a flat substrate to a predetermined value or greater. Furthermore, Patent Document 2 describes electrostatic spray coating on a substrate in a state where a conductive frame of a predetermined width is provided around the entire periphery of the substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-244209 [Patent Document 2] Japanese Patent Application Publication No. 10-249266 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are cases where a substrate with a coating film formed with a through hole is used, such as glass for an in-vehicle display with a through hole formed in the start button area, etc. When a coating film is formed on such a substrate with a coating film by electrostatic spraying, the thickness of the coating film may become non-uniform.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a substrate with a coating film, a method for forming a coating film, and a method for manufacturing a substrate with a coating film, which are capable of improving the uniformity of a coating film on a substrate having a through hole formed therein. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the coated substrate of the present disclosure comprises a glass plate having a thickness of 0.3 mm or more and 3.0 mm or less, and an anti-glare film provided on the surface of the glass plate, wherein the glass plate has a through hole having an inner diameter of 10 mm or more and 100 mm or less, and the absolute value of ΔSc, which is the difference in coating area ratio Sc between a position 0.21 mm radially outward from the inner peripheral edge of the through hole and a position midway between the inner peripheral edge of the through hole and the edge farthest from the through hole, is less than 0.48%.

[0007] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a coating film forming method, which includes inserting an insertion member into a through hole formed in a substrate that penetrates the substrate in a thickness direction, and forming a coating film on the substrate by electrostatic spray coating on the substrate and the insertion member, wherein the resistivity of the insertion member is 2.0 × 10 5 The thickness of the insertion member is smaller than the thickness of the substrate, and the difference between the outer diameter of the insertion member and the inner diameter of the through hole is 8.0 mm or less.

[0008] In order to solve the above-mentioned problems and achieve the objectives, the method for manufacturing a substrate with a coating film according to the present disclosure is a method for manufacturing a substrate with a coating film by forming the coating film on the substrate using the coating film forming method. [Effects of the Invention]

[0009] According to the present invention, it is possible to improve the uniformity of the coating film on a substrate having through holes formed therein. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an in-vehicle display according to this embodiment. [Figure 2] FIG. 2 is a schematic front view of a portion of a substrate with a coating according to this embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4]FIG. 4 is a schematic diagram illustrating a method for producing a substrate with a coating film according to this embodiment. [Figure 5] FIG. 5 is a schematic diagram showing the dimensional difference between the substrate and the insertion member according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments, and when there are multiple embodiments, the present invention also includes configurations that are made by combining the respective embodiments. Furthermore, numerical values ​​include the range of rounding.

[0012] (In-car display) FIG. 1 is a schematic diagram showing an in-vehicle display according to this embodiment. As shown in FIG. 1, an in-vehicle display 2 is provided in front of a steering shaft 1 in the front portion of a vehicle cabin. The in-vehicle display displays, for example, a car navigation screen 3, various meters such as a speedometer 4, and a start button 5. A car navigation system is an automobile route guidance system that displays the current position and traveling direction of a vehicle on a map on a screen using pre-entered route information and GPS satellites, etc. The in-vehicle display 2 has a coated substrate 6 according to this embodiment as the glass plate of the display surface. Note that the coated substrate 6 is not limited to being used as the glass plate of an in-vehicle display surface and may be used for any purpose.

[0013] (Coated substrate) Fig. 2 is a schematic front view of a portion of a substrate with a coating according to this embodiment, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2.

[0014] As shown in FIGS. 2 and 3 , the coated substrate 6 according to this embodiment has a substrate 7 and a coating film 8. The coating film 8 is formed on the surface of the substrate 7. Furthermore, a through hole 9 is formed in the coated substrate 6. The through hole 9 penetrates the coated substrate 6 in the thickness direction. In this embodiment, the coated substrate 6 has a two-layer structure of the substrate 7 and the coating film 8, but is not limited to this two-layer structure, and a layer other than the substrate 7 and the coating film 8 may also be formed. The other layer may be formed between the substrate 7 and the coating film 8, or may be formed on the back surface of the substrate 7 opposite the coating film 8, or may be further formed on the surface of the coating film 8.

[0015] (substrate) The substrate 7 is, for example, a glass plate. Examples of glass plates include soda lime glass, borosilicate glass, crystallized glass, and quartz glass. In this embodiment, the substrate 7 is flat, but is not limited to a flat plate shape and may be curved. The material of the substrate 7 is not limited to glass, and may be, for example, an acrylic plate, a transparent plate mainly composed of polyester such as a PET plate, or polycarbonate.

[0016] The thickness of the substrate 7 is preferably, for example, 0.3 mm to 3.0 mm, and more preferably 1.0 mm to 1.5 mm. When the thickness of the substrate 7 is 0.3 mm or more, the strength can be appropriately maintained, and when the thickness is 3.0 mm or less, an increase in weight can be suppressed.

[0017] (Through hole) As shown in FIG. 2, the shape of the through hole 9 is preferably, for example, circular when viewed from the front, but is not limited to circular and various shapes such as polygons can be applied. In the case of a circular through hole 9, the inner diameter (diameter) A2 of the through hole 9 is preferably, for example, 10 mm to 100 mm, and more preferably 20 mm to 60 mm. When the inner diameter (diameter) A2 of the through hole 9 is 10 mm or more, a finger can be passed through the through hole 9 without touching the substrate 6, and when it is 100 mm or less, accidental pressing can be prevented. Note that if the through hole 9 is not circular, the inner diameter (diameter) A2 of the through hole 9 may refer to the length of a straight line connecting any point on the inner circumference of the through hole 9, the center point of the through hole 9, and another any point on the inner circumference of the through hole 9.

[0018] (paint film) The coating film 8 is, for example, an anti-glare (AG) film, and has a plurality of concave and convex shapes on its surface. By forming minute concave and convex shapes on the surface of the substrate, it is possible to diffusely reflect external light, reduce glare, and improve the visibility of the display. Furthermore, the coating film 8 is not limited to an anti-glare film, and may be a film with any function. For example, the coating film 8 may be an anti-reflection (AR) film. The material of the coating film 8 is arbitrary, and examples thereof include a silica-based matrix. As will be described in detail later, the coating film 8 is formed on the substrate 7 by an electrostatic coating method.

[0019] (electrostatic coating method) In this embodiment, a coating film 8 is formed on a substrate 7 having through holes 9 formed therein by electrostatic coating, thereby producing a substrate 6 with a coating film. Electrostatic coating methods include, for example, electrostatic spray coating, in which paint is sprayed using an electrostatic spray gun, and electrostatic atomization, which utilizes the repulsion of the electrically charged paint itself. In this embodiment, an embodiment in which the electrostatic spray coating method is applied will be described. The paint for the anti-glare film may contain particles. Examples of particles that can be used include metal oxide particles, metal particles, pigment particles, and resin particles.

[0020] Materials for metal oxide particles include Al2O3, SiO2, SnO2, TiO2, ZrO2, ZnO, CeO2, and Sb-containing SnO XExamples of materials for metal particles include Ag, Ru, AgPd, RuAu, etc. Examples of materials for pigment particles include inorganic pigments (titanium black, carbon black, etc.) and organic pigments. Examples of materials for resin particles include acrylic resin, polystyrene, melamine resin, etc.

[0021] Examples of the shape of the particles include scale-like, spherical, elliptical, needle-like, plate-like, rod-like, conical, cylindrical, cubic, rectangular, diamond-like, star-like, irregular shape, etc. The other particles may exist in an independent state, may be connected in a chain form, or may be aggregated.

[0022] The particles may be solid particles, hollow particles, or particles with holes such as porous particles. Examples of scaly particles include scaly silica (SiO2) particles, scaly alumina (Al2O3) particles, scaly titania (TiO2), and scaly zirconia (ZrO2). Preferred other particles include silica particles such as spherical silica particles, rod-shaped silica particles, and needle-shaped silica particles.

[0023] FIG. 4 is a schematic diagram illustrating a method for producing a coated substrate according to this embodiment. As shown in FIG. 4, in the electrostatic coating method of this embodiment, an electrostatic coating device 10 equipped with an electrostatic coating gun is used to charge and spray the paint. The paint droplets 14 sprayed from the electrostatic coating gun are negatively or positively charged and are therefore attracted by electrostatic attraction toward the grounded substrate 7. As a result, they adhere more efficiently to the substrate 7 than when sprayed without being charged. One type of anti-glare treatment method may be performed alone, or two or more types may be combined.

[0024] In the present invention, the coating conditions for electrostatic spray coating on substrate 7 are not particularly limited, and various conditions can be applied. For example, when substrate 7 is a glass plate and a rotary atomization electrostatic spray gun is used, typically, the following conditions are suitable: applied voltage is −90 kV to −30 kV, bell rotation speed is 15 krpm to 70 krpm, paint discharge rate is 5 mL to 1000 mL / min, and the distance between the electrostatic spray gun and the substrate is 100 mm to 600 mm.

[0025] When forming a coating film 8 on a substrate 7 having through holes 9 formed therein by electrostatic coating, there is a risk that the coating film 8 may not be formed to a uniform thickness due to factors such as the concentration of the electric field of the electrostatic spray coating around the periphery of the through holes 9. In contrast, in this embodiment, an insertion member 13 is disposed inside the through holes 9 to suppress unevenness in the thickness of the coating film 8. An electrostatic coating device 10 having an insertion member 13 will be specifically described below.

[0026] (Electrostatic coating equipment) The electrostatic coating apparatus 10 forms a coating film 8 on a substrate 7 to produce a coated substrate 6. As shown in FIG. 4 , the electrostatic coating apparatus 10 includes an electrostatic spray gun 11, a conductive base 12, and an insertion member 13. The electrostatic spray gun 11 can be, for example, a rotary atomization electrostatic spray gun. The electrostatic spray gun 11 sprays droplets 14 of paint. The conductive base 12 is a conductive member and is grounded (earthed) via a grounding cable. The material of the conductive base 12 is not particularly limited, but metal, carbon, conductive resin, and the like are preferred. Stainless steel may be used as the metal for the conductive base 12. Alternatively, an insulating base such as glass covered with a metal film such as aluminum foil or coated with a metal such as copper by vapor deposition can also be used as the conductive base 12. When producing the coated substrate 6, the substrate 6 is placed on the conductive base 12.

[0027] (insertion member) 5 is a schematic diagram showing the dimensional difference between the substrate and the insertion member according to this embodiment. The insertion member 13 is a member that is placed in the through-hole 9 of the substrate 7 when forming the coating film 8 on the substrate 7. When forming the coating film 8 on the substrate 7, the substrate 7 and the insertion member 13 are placed on the surface 121 of the conductive pedestal 12, as shown in FIG. 5. That is, the surface 121 of the conductive pedestal 12 and the back surface 71 of the substrate 7 are in contact, and the surface 121 of the conductive pedestal 12 and the back surface 131 of the insertion member 13 are in contact.

[0028] The insert 13 has a resistivity of 1.0×10 14 Ωcm or less, and preferably the resistivity is 2.0×10 5 The insert member 13 has a resistivity of 1.0×10 14 When the resistivity is Ωcm or less, the coating film 8 can be formed uniformly.

[0029] The material of the insert member 13 is arbitrary, but is preferably a conductive material with low resistivity, and therefore preferably contains metal. It is more preferable that the metal is exposed on the outermost surface of the insert member 13, and it is particularly preferable that the entire surface is made of metal. Examples of metals that can be used include aluminum (Al), stainless steel, copper, silver, and gold, with stainless steel being more preferable. The insert member 13 may also contain rubber, for example, as long as the resistivity requirement is met. Examples of rubber that can be used include natural rubber and synthetic rubber, with natural rubber being more preferable.

[0030] The shape of the insert member 13 can be various depending on the shape of the through hole 9. When the shape of the through hole 9 is circular, the insert member 13 is preferably, for example, a disk. In the case of a circular insert member 13, the outer diameter (diameter) A1 of the insert member 13 is preferably, for example, 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 60 mm or less. When the outer diameter (diameter) A1 of the insert member 13 is within this range, the insert member 13 is appropriately positioned within the through hole 9, allowing the coating film 8 to be formed uniformly. Note that when the insert member 13 is not circular, the outer diameter (diameter) A1 of the insert member 13 may refer to the length of a straight line connecting any point on the outer periphery of the insert member 13, the center point of the insert member 13, and another any point on the outer periphery of the insert member 13.

[0031] Here, as shown in FIG. 5, the thickness of the insert member 13 is defined as thickness T1. Thickness T1 is the vertical distance between the back surface 131 and the front surface 132 of the insert member 13. Furthermore, the thickness of the substrate 7 is defined as thickness T2. Thickness T2 is the vertical distance between the back surface 71 and the front surface 72 of the substrate 7. In this case, thickness T1 of the insert member 13 is smaller than thickness T2 of the substrate 7. Furthermore, the difference D between thickness T2 of the substrate 7 and thickness T1 of the insert member 13 is preferably 0.1 mm or more and less than 0.7 mm, more preferably 0.2 mm or more and 0.6 mm or less, and even more preferably 0.3 mm or more and 0.5 mm or less. When the difference D between thickness T1 and thickness T2 is within this range, the coating film 8 can be formed uniformly.

[0032] Furthermore, the difference between the outer diameter A1 of the insert member 13 and the inner diameter A2 of the through hole 9 shown in FIG. 5 is 8.0 mm or less, preferably 0 mm to 4 mm, and more preferably 1 mm to 3 mm. Furthermore, when forming the coating film 8 on the substrate 7, it is preferable that the outer peripheral edge 133 of the insert member 13 and the inner peripheral edge 73 of the through hole 9 are not in contact with each other but are spaced apart. In other words, a gap is formed between the inner peripheral edge 73 of the through hole 9 of the substrate and the outer peripheral edge 133 of the insert member 13, and the total length of the gap along the radial direction of the insert member 13, or the first length, corresponds to the difference between the outer diameter A1 and the inner diameter A2 and is 8.0 mm or less. For example, as shown in FIG. 5, in a cross section passing through the center 130 of the insert member 13 and perpendicular to the surface 72 of the substrate 7, there are two gaps between the inner peripheral edge 73 of the through hole 9 and the outer peripheral edge 133 of the insert member 13. The total length of the gaps along the radial direction is the sum of the length L1 of one gap and the length L2 of the other gap, and this first length is 8.0 mm or less. Note that the first length is not limited to passing through the center 130 of the insertion member 13.

[0033] (Coating film formation method) As shown in Fig. 4, in the coating film forming method, first, a substrate 7, which is an object to be coated, is placed on an earthed conductive base 12. The substrate 7 has a through hole 9 penetrating through the thickness direction. In one example of this embodiment, the substrate 7 is a glass plate, and the through hole 9 has a circular shape. In addition, in one example of this embodiment, the inner diameter of the through hole 9 is 10 mm or more and 100 mm or less.

[0034] Next, the insert member 13 is placed on the inner periphery of the through hole 9 of the substrate 7. In one example of this embodiment, the insert member 13 is a metal or rubber disk, and the difference between the outer diameter A1 of the insert member 13 and the inner diameter A2 of the through hole 9 is 8.0 mm or less.

[0035] Next, paint droplets 14 are sprayed from the electrostatic spray gun 11 toward the substrate 7 and the insert member 13. This makes the grounded substrate 7 the positive electrode and the electrostatic spray gun 11 the negative electrode, creating an electrostatic field between the substrate 7 and the electrostatic spray gun 11, which negatively charges the droplets 14 and causes coating. The charged droplets 14 fly along the electric field lines and are applied to the positive substrate 7.

[0036] As described above, the coating film forming method according to this embodiment is a method for forming a coating film by inserting an inserting member 13 into the inner periphery of a through hole 9 formed in a substrate 7 that penetrates the substrate 7 in the thickness direction, and then electrostatically spray coating the substrate 7 and the inserting member 13. 5 The thickness T1 of the insertion member 13 is smaller than the thickness T2 of the substrate 7, and the difference between the outer diameter A1 of the insertion member 13 and the inner diameter A2 of the through-hole 9 is 8.0 mm or less.

[0037] As described above, in the coating film forming method according to this embodiment, under the predetermined conditions described above, the insert member 13 is inserted into the inner periphery of the through hole 9 in the substrate 7, and electrostatic spray coating is performed on the substrate 7 and the insert member 13. This suppresses the concentration of the electric field of the electrostatic spray coating at the periphery of the through hole 9 in the substrate 7, compared to when the predetermined conditions described above are not met or when the insert member 13 is not inserted into the inner periphery of the through hole 9 in the substrate 7. As described above, according to this embodiment, the unevenness of the electric field between the periphery of the through hole 9 and other parts is reduced, so the thickness of the coating film 8 at the periphery of the through hole 9 in the substrate 7 approaches the thickness of the coating film 8 in other parts. This makes it possible to improve the uniformity of the coating film 8 on the substrate 7 having the through hole 9 formed therein.

[0038] Furthermore, through-hole 9 has a circular shape, and an inner diameter A2 (diameter) of through-hole 9 of 10 mm or more allows a finger to pass through the through-hole without touching substrate 6, and an inner diameter A2 (diameter) of 100 mm or less prevents accidental pressing. Therefore, it is preferable that the inner diameter A2 (diameter) of through-hole 9 is 10 mm or more and 100 mm or less.

[0039] The substrate 7 is preferably a glass plate having a thickness T2 of 0.3 mm or more and 3.0 mm or less. A thickness T2 of 0.3 mm or more of the substrate 7 maintains appropriate strength, while a thickness of 3.0 mm or less prevents weight increase. Therefore, the thickness T2 of the substrate 7 is preferably 0.3 mm or more and 3.0 mm or less.

[0040] The difference D between the thickness T2 of the substrate 7 and the thickness T1 of the insert member 13 is preferably 0.1 mm or more and less than 0.7 mm. When the difference D between the thickness T1 and the thickness T2 is within this range, the coating film 8 can be formed uniformly. Therefore, it is desirable that the difference D be 0.1 mm or more and less than 0.7 mm.

[0041] The coating film 8 is preferably an anti-glare film having an uneven surface. Since the uniformity of the coating film 8 on the substrate 7 provided with the through-holes 9 is improved, the difference in anti-glare properties between different parts of the substrate 7 is reduced. As a result, it is possible to obtain uniform anti-glare properties over the entire substrate 7.

[0042] In a preferred embodiment, the insertion member 13 contains a metal, and therefore the uniformity of the coating film 8 on the substrate 7 having the through hole 9 is improved compared to when an insertion member 13 made of a material other than metal is inserted into the through hole 9 of the substrate 7.

[0043] The method for producing a coated substrate is a method for producing a coated substrate 6 by forming a coating film 8 on a substrate 7 using the coating film formation method described above. Therefore, the thickness of the coating film 8 around the periphery of the through-hole 9 of the coated substrate 6 approaches the thickness of the coating film 8 in other parts, making it possible to improve the uniformity of the coating film 8 of the coated substrate 6.

[0044] The coated substrate 6 is preferably provided in an in-vehicle display 2. The in-vehicle display 2 is particularly required to have uniform antiglare properties over the entire substrate 7, and therefore the coated substrate 6 formed by the above-described manufacturing method is suitable.

[0045] The coated substrate 6 includes a glass plate (substrate 7) having a thickness of 0.3 mm to 3.0 mm and an anti-glare film (coating 8) formed on the surface of the glass plate. The glass plate has a through hole 9 having an inner diameter of 10 mm to 100 mm. The absolute value of ΔSc, which is the difference in coating area ratio Sc between a position 0.21 mm radially outward from an inner peripheral edge 73 of the through hole 9 and a midpoint between the inner peripheral edge 73 of the through hole 9 and the edge farthest from the through hole 9, is less than 0.48%. This reduces the non-uniformity of the electric field between the peripheral edge of the through hole 9 and other positions, so that the thickness of the coating 8 at the peripheral edge of the through hole 9 on the glass plate (substrate 7) approaches the thickness of the coating 8 at other positions. This makes it possible to improve the uniformity of the coating 8 on the glass plate (substrate 7) having the through hole 9.

[0046] (Example) Next, examples will be described. It should be noted that the embodiment may be modified as long as the effects of the invention are achieved. In Examples 1 to 9 of Table 1 below, a glass plate with a through hole was used as the substrate, and an Al or rubber disk was used as the insert member. Electrostatic coating was applied to the substrate and the insert member to form a coating film on the substrate, and then the substrate was dried in the atmosphere. A more detailed description will be given below.

[0047] [Substrate (glass plate)] In all of Examples 1 to 9 shown in Table 1 below, Dragontrail (trade name, registered trademark) manufactured by AGC Inc. was used as the glass plate substrate. Substrate (glass) type A in Table 1 refers to this Dragontrail. The glass plate had a rectangular shape, measuring 100 mm in length, 100 mm in width, and 1.3 mm or 1.1 mm in thickness. The through-hole was circular and had an inner diameter of 40 mm. After opening a through-hole in the center of the substrate, the substrate was scrubbed and washed with baking soda, then rinsed with ion-exchanged water, and air-dried.

[0048] [Table 1]

[0049] [Insert] In Examples 1 to 9, the insert is an Al or rubber disc. The resistivity is 1.0×10 -8 Ωcm, 1.0 x 10 2 Ωcm, 2.0 x 10 5 The outer diameters of the inserts are 30 mm, 32 mm, 38 mm, and 40 mm. The thicknesses of the inserts are 1.0 mm and 2.0 mm.

[0050] [Dimensional difference between board and insert] The hole diameter difference is the difference between the inner diameter (diameter) of the through hole in the substrate and the outer diameter (diameter) of the insertion member, and is also the first length mentioned above. The hole diameter differences are 0 mm, 2 mm, 8 mm, and 10 mm. Furthermore, the thickness of the insertion member is smaller than the thickness of the substrate. Therefore, the thickness difference obtained by subtracting the thickness of the insertion member from the thickness of the substrate is 0.1 mm, 0.3 mm, and -0.7 mm. Note that -0.7 mm means that the insertion member is thicker than the substrate.

[0051] [Electrostatic spray method] As explained in the embodiment with reference to Fig. 4, a glass plate serving as a substrate was placed on a conductive pedestal, and an insertion member was inserted into the through-hole of the glass plate. The conductive pedestal was a metal plate made of stainless steel (SUS304) and measured 490 mm in length, 300 mm in width, and 3 mm in thickness. The conductive pedestal was grounded, and the glass plate and insertion member were in contact with the conductive pedestal, so they were also grounded.

[0052] Next, electrostatic coating was performed by spraying droplets of paint onto the glass plate and insert member using a rotary atomization electrostatic spray device (Mighty Robot Bell 21, model: Mighty21, product number, etc., manufactured by CFT Ransberg Co., Ltd.). Specifically, while the glass plate, insert member, and conductive base were transported at a constant speed on a chain conveyor, paint at a temperature within a range of 23±2°C was applied to the glass plate by electrostatic spray coating, and the glass plate was then dried in the air.

[0053] [Paint ingredients] The paint used in the electrostatic coating (coated sample α in Table 1) is a mixture of the following components. Solmix (registered trademark) AP11 (manufactured by Japan Alcohol Sales Co., Ltd.): 98.3378 wt% Tetraethoxysilane (silica solids concentration 28.84%): 0.6533 wt% KBM3066 (Shin-Etsu Silicone Co., Ltd.): 0.0385 wt% Water: 0.7186wt% 10% nitric acid: 0.0373 wt% SLV: 0.2145wt% SLV is a dispersion of scaly silica particles made by crushing and dispersing Sunlovely LFS HN150 manufactured by AGC Si-Tech Co., Ltd., with an average particle size of 185 nm, an average aspect ratio (average particle size / average thickness) of 80, and a silica solids concentration of 5 wt%. The 5 wt% silica solids concentration is calculated by dividing the weight of silica particles by the combined weight of water and silica particles.

[0054] [Painting conditions] The coating conditions were as follows: The glass plate was grounded and therefore had a potential of 0, and the potential of the electrostatic spray gun was −60 kV, so the potential difference between the electrostatic spray gun and the glass plate was 60 kV. Painting room conditions: Temperature is kept within the range of 23±2℃, humidity is kept within the range of 55±10% Distance between electrostatic spray gun and glass plate: 330 mm Potential difference between electrostatic spray gun and glass plate: 60 kV Shape air volume: 100L / min Paint discharge flow rate: 29mL / min Bell rotation speed: 35kpm Conveying speed: 7.7 m / min (4 passes)

[0055] [Measurement of coating coverage ratio] After the coating film was formed on the substrate, the coating coverage area ratio Sc of the coating film in the periphery of the through-hole and in the general area other than the periphery was measured under the following conditions. Measuring equipment: Keyence VK-100 laser microscope The measurement conditions are as follows. Grayscale photography at 500x magnification (measurement window 0.21mm long, 0.28mm wide) Measurement location: The peripheral area of ​​the through-hole was located 0.21 mm radially outward from the inner periphery of the through-hole, and the general area was located midway between the inner periphery of the through-hole and the edge of the substrate farthest from the through-hole. Image processing method: Measurement was performed in laser light intensity mode using a Keyence VK-H1XV shape analysis application. The upper limit of the threshold was set at the peak end position of the first peak, and the area of ​​the coating film was analyzed.

[0056] [Evaluation results] The difference in coating area percentage Sc (%), ΔSc (%), was calculated and the evaluation was based on ΔSc. ΔSc is the value obtained by subtracting the coating area percentage Sc in the general area from the coating area percentage Sc in the area surrounding the through-hole. The evaluation in Table 1 was classified as double circle, circle, triangle, or cross using the absolute value of ΔSc as follows: When the absolute value of ΔSc is 0 or more and less than 2.4, it is marked with a double circle. When the absolute value of ΔSc is 2.4 or more and less than 4.8, a circle is marked. When the absolute value of ΔSc is between 4.8 and 7.2, it is defined as a triangle. If the absolute value of ΔSc was greater than 7.2, it was marked as X. Double circles, circles, and triangles were rated as passing, and crosses were rated as failing. The contents of Examples 1 to 9 are briefly explained below.

[0057] [Example 1] The glass substrate was Dragontrail (trade name, registered trademark) manufactured by AGC Inc. The dimensions of the glass plate were 100 mm long, 100 mm wide, and 1.3 mm thick. A circular through-hole with an inner diameter of 40 mm was drilled in the center of the glass plate, which was then scrubbed with baking soda, rinsed with ion-exchanged water, and allowed to air-dry. The glass plate was placed on a conductive base made of stainless steel (SUS304). A disk-shaped insert member with an inner diameter of 40 mm and a thickness of 1 mm was placed in the center of the through-hole in the glass plate. The insert member was made by wrapping a disk-shaped natural rubber plate with an outer diameter of 40 mm and a thickness of 1 mm with 0.15 g of aluminum foil manufactured by Nippon Foil Co., Ltd. The glass plate, insert member, and conductive base were transported at a constant speed on a chain conveyor, and a paint at a temperature within a range of 23±2°C was applied to the glass plate using an electrostatic spray coating method. The glass plate was then dried in the atmosphere.

[0058] [Examples 2 to 6] Examples 2 to 6 were performed under the conditions shown in Table 1. Examples 2 to 6 differ in some respects from Example 1. For example, in Example 2, the thickness of the substrate is 1.1 mm, which is different from Example 1, but the other conditions are the same. Also, in Example 3, the outer diameter of the insertion member is 38 mm, which is different from Example 1, but the other conditions are the same.

[0059] [Examples 7 to 9] Example 7 differs from Example 1 in that electrostatic coating was performed without using an insert member, but the other conditions were the same. Example 8 differs from Example 1 in that the outer diameter of the insert member was 30 mm, but the other conditions were the same. Example 9 differs from Example 1 in that the resistivity of the insert member was 1.0 x 10 2 The test results are shown in Table 1.

[0060] [Evaluation results] In Table 1, Examples 1 to 6 correspond to Examples, and Examples 7 to 9 correspond to Comparative Examples. As shown in Table 1, it can be seen that the evaluation results for coating area ratio were pass for Examples 1 to 6. On the other hand, it can be seen that the evaluation results for coating area ratio were fail for Examples 7 to 9. This will be explained in detail below.

[0061] In Example 3, the hole diameter difference, which is the difference between the inner diameter of the through hole in the substrate and the outer diameter of the insert member, is 2 mm, and the thickness of the insert member is smaller than the thickness of the substrate, resulting in the highest evaluation result for the coating area ratio. Furthermore, in Examples 1 to 4, Al is used for the insert member, while in Examples 5 and 6, rubber is used for the insert member. Considering that the evaluation results for the coating area ratio were acceptable in Examples 1 to 6, it can be seen that both Al and rubber can be used as materials for the insert member.

[0062] In Example 7, the evaluation result was unacceptable, demonstrating the importance of performing electrostatic coating while the insert member is inserted into the through-hole of the substrate. Of all Examples 1 to 9, Example 8 had the largest hole diameter difference, at 10 mm, between the inner diameter of the through-hole of the substrate and the outer diameter of the insert member. The evaluation result for the coating area ratio in Example 8 was unacceptable, demonstrating that the uniformity of the coating film on the substrate can be improved by reducing the hole diameter difference to a small value, such as 8 mm or less as in Example 4. In Example 9, the thickness of the insert member was greater than the thickness of the substrate, resulting in a failure in the evaluation result for the coating area ratio. This demonstrates that the uniformity of the coating film on the substrate can be improved by reducing the thickness of the insert member to the thickness of the substrate.

[0063] Although the embodiments of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments. [Explanation of symbols]

[0064] 2. In-vehicle displays 6. Coated substrate 7. Circuit Board 8 Paint film 9 Through holes 10 Electrostatic painting equipment 11 Electrostatic spray gun 12 Conductive base 13 Insert 14 droplets 72 Surface 73 Inner edge 130 center 133 outer edge A1 outer diameter A2 inner diameter T1, T2 thickness

Claims

1. A coating film forming method comprising: inserting an insert member into an inner peripheral side of a through hole of a substrate having a through hole penetrating in a thickness direction, and performing electrostatic spray coating on the substrate and the insert member, The resistivity of the insert member is 2.0×10 ５ Ωcm or less, the thickness of the insert is less than the thickness of the substrate; the through hole and the insert member have a circular shape; The difference between the outer diameter of the insertion member and the inner diameter of the through hole is 8.0 mm or less. Paint film formation method.

2. A method for forming a coating film, comprising inserting an insert member into an inner peripheral side of a through hole of a substrate having a through hole penetrating in a thickness direction, and applying electrostatic spray coating to the substrate and the insert member, thereby forming a coating film on the substrate, The resistivity of the insertion member is 2.0×10 5 Ωcm or less, the thickness of the insert is less than the thickness of the substrate; A gap is formed between the inner peripheral edge of the through hole and the outer peripheral edge of the insertion member. Paint film formation method.

3. A coating film forming method comprising: inserting an insert member into an inner peripheral side of a through hole of a substrate having a through hole penetrating in a thickness direction; and applying electrostatic spray coating to the substrate and the insert member, thereby forming a coating film on the substrate, The resistivity of the insertion member is 2.0×10 5 Ωcm or less, the thickness of the insert is less than the thickness of the substrate; In any cross section that passes through the inner peripheral edge of the through hole and the outer peripheral edge of the insertion member and is perpendicular to the surface of the substrate, The total gap between the inner peripheral edge of the through hole and the outer peripheral edge of the insertion member is 8.0 mm or less. Paint film formation method.

4. The inner diameter of the through hole is 10 mm or more and 100 mm or less. The method for forming a coating film according to claim 1.

5. The difference between the outer diameter of the insertion member and the inner diameter of the through hole is 1 mm or more and 3 mm or less. The method for forming a coating film according to claim 1 or 4.

6. The substrate is a glass plate having a thickness of 0.3 mm or more and 3.0 mm or less. The method for forming a coating film according to any one of claims 1 to 5.

7. The difference between the thickness of the substrate and the thickness of the insertion member is 0.1 mm or more and less than 0.7 mm. The method for forming a coating film according to any one of claims 1 to 6.

8. The coating film is an anti-glare film having an uneven surface. The method for forming a coating film according to any one of claims 1 to 7.

9. The insert member contains a metal. The method for forming a coating film according to any one of claims 1 to 8.

10. A substrate with a coating film is manufactured by forming the coating film on the substrate using the coating film forming method according to any one of claims 1 to 9. Method for producing a coated substrate.

11. The coated substrate is provided in an in-vehicle display. A method for producing a coated substrate according to claim 10.

12. A glass plate having a thickness of 0.3 mm or more and 3.0 mm or less; an anti-glare film provided on the surface of the glass plate, The glass plate has a through hole having an inner diameter of 10 mm or more and 100 mm or less, the through hole has a circular shape; a position 0.21 mm away from the inner peripheral edge of the through hole radially outward; the absolute value of ΔSc, which is the difference in coating area ratio Sc between the inner peripheral edge of the through hole and the intermediate portion between the edge farthest from the through hole, is less than 0.48%; Coated substrate.

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