JP2000128580A - Dip coating method for glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a yield and to uniformly form a coating film. SOLUTION: A back plate 2 is affixed and joined via liquid to the rear surface of a glass substrate 1 so as to project from the bottom end face of the glass substrate 1 and the entire part thereof is immersed into a coating liquid and is pulled up, by which the coating film is formed on the surface of the glass substrate 1. The coating liquid sticking to the surface of the glass substrate 1 transfers the bottom end face from the surface of the glass substrate 1 and flows down on the bottom end surface 20 of the exposed back surface 2 and, therefore, the accumulating of the liquid at the edges of the glass substrate 1 and the increasing the film thickness of these portions are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a coating film on the surface of a glass substrate using a dipping coating method. The dip coating method of the present invention is most suitable for forming a coating film on a thin glass substrate used for an anti-glare mirror of an automobile or the like.

[0002]

2. Description of the Related Art An anti-glare mirror is used as an interior mirror of an automobile in order to reduce glare caused by lights of a following vehicle. Various types of anti-glare mirrors are known. Recently, anti-glare mirrors utilizing electrochromism have been developed.

The anti-glare mirror has a first glass substrate on which a transparent conductive film such as ITO, an electrochromic (EC) layer, and a light reflection layer are formed in this order, and a first glass substrate covering the light reflection layer. And a second glass substrate bonded to the second glass substrate. Then, when the EC layer is energized, the EC layer is colored, the incident light from the surface of the second glass substrate is partially absorbed and then emitted from the second glass substrate.

When manufacturing such an EC anti-glare mirror, it is necessary to first form various thin films on a glass substrate. For example, a transparent conductive film is formed by a sputtering method, and an EC layer such as tungsten oxide is formed. Generally, it is formed by a dip coating method. For example, in order to form a tungsten oxide film on a glass substrate surface using a dip coating method, the glass substrate is gripped with a clip or the like, and immersed in a coating solution in which a tungsten alkoxide or a tungsten organic complex is dissolved in a solvent, and gradually. By pulling up, a coating film is formed on the surface of the glass substrate. Then, the tungsten alkoxide film is hydrolyzed by the moisture in the air, or the solvent is dried and then baked, so that the tungsten alkoxide film is made of tungsten oxide.
A C film can be formed.

In the dip coating method, various methods have been proposed in order to make the thickness of the coating film formed uniform. For example, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open Publication No. H11-15064 discloses a method in which a printed board is horizontally immersed in a coating liquid, and when the board is pulled up, the printed board is inclined to improve liquid drainage.
Further, Japanese Patent Application Laid-Open No. 2-244792 discloses a method of improving the liquid drainage property by inclining a printed circuit board in contact with the surface of the coating liquid when pulling up from the coating liquid.

[0006] In the case of these printed boards and the like, the boards are immersed in a coating solution in a horizontal state.
In the case of a glass substrate or the like of an anti-glare mirror, it is general that the glass substrate is immersed in a coating liquid in a vertical state.

[0007]

In the case of an EC film or the like of a glass substrate for an anti-glare mirror, if the film thickness is not uniform, the anti-glare performance will be locally different. Is extremely important. However, when the glass substrate is immersed in the coating liquid in a vertical state and pulled up, the fluidity of the coating liquid flowing down to the lower end of the glass substrate is hindered at the edge, and the coating liquid collects at the edge and the film thickness at the lower end Is thicker. As described above, when the EC film at the lower end portion is thick, the color development at the time of energization becomes large in that portion, and there is a problem that the antiglare effect becomes locally non-uniform. Therefore, the lower end of the EC film having a large thickness must be cut off and used, but in this case, the yield is low.

When the upper end of the glass substrate is gripped and immersed with a clip or the like, it may be difficult to immerse the gripped portion in the coating liquid, and in this case, the portion must be cut off. In addition, the pulling speed may be unstable at the start of the pulling, so that the thickness of the coating film becomes uneven. Then, a suction cup is adsorbed on the back side of the glass substrate,
It may be possible to raise it. However, since the glass substrate of the anti-glare mirror is thin, the portion adsorbed by the suction cup is deformed, and a coating film is formed in that state. Therefore, it is known that when the suction cup is removed, the coating film in the portion where the glass substrate is deformed is deformed, and when used as an anti-glare mirror, there is a problem that a color pattern is formed in the color of the portion.

The present invention has been made in view of such circumstances, and has as its object to improve the yield and form a uniform coating film.

[0010]

According to a first aspect of the present invention, there is provided a method of dip coating a glass substrate, wherein a back plate projects from the lower end surface of the glass substrate on the back surface of the surface to be coated of the glass substrate. And bonding the glass substrate together with the back plate, immersing the glass substrate with the back plate in the coating liquid from the lower end surface, and gradually lifting the glass substrate together with the back plate from the upper end surface to form a coating film on the surface to be coated. And a step of separating the glass substrate and the back plate.

According to a second aspect of the present invention, there is provided a method of dip coating a glass substrate, wherein the back plate has a thickness in contact with a lower end surface of the glass substrate below the glass substrate. It has a plate part.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method for dip coating a glass substrate according to the first aspect, the glass substrate and the back plate are bonded and bonded via a liquid. That is, by interposing a liquid between the glass substrate and the back plate, the glass substrate and the back plate are bonded and bonded by the surface tension of the liquid.

According to this bonding method, the glass substrate can be bonded and bonded on the entire back surface thereof, so that the glass substrate is hardly deformed as compared with a case where the glass substrate is fixed by suction with a suction cup. Therefore, if the present invention is applied to the case where an EC film is formed on the glass substrate of the anti-glare mirror, it is possible to prevent a problem that a circular pattern is generated in the color development at the time of anti-glare. Note that, in addition to sticking and joining with a liquid, suction with a suction cup and the like can be used together. In this case, since the suction pressure may be very weak, there is no problem that a circular pattern is generated.

The liquid for fixing the glass substrate and the back plate is not limited as long as it does not become an impurity of the coating liquid, and one or more components used in the coating liquid such as a solvent for the coating liquid can be used. . In particular, it is desirable to fix using the coating liquid itself. If the coating liquid itself is used as the liquid, the composition of the coating liquid does not change even if the coating is performed continuously, so that a stable coating can be performed continuously.

[0015] In the dip coating method of the present invention, the back plate is attached and bonded so as to protrude from the lower end surface of the glass substrate. That is, when pulled up from the coating liquid, a part of the back plate that is in contact with the back surface of the glass substrate extends downward and is exposed, and the surface to be coated and the lower end surface of the glass substrate and a part of the surface of the exposed back plate are exposed. Is continuous while bending. Therefore, when pulled up from the coating liquid, the coating liquid on the surface to be coated is
It travels from the surface to be coated to the bottom surface of the glass substrate,
Then, the surface of the exposed back plate smoothly flows down, so that the flow is not hindered at the edge at the lower end of the surface to be coated and does not accumulate at the edge. As a result, the coating liquid adhered to the surface to be coated has a uniform thickness, and a coating film can be formed uniformly.

In order to reliably perform the above-described operation, it is desirable that the lower end surface of the glass substrate and a partial surface of the back plate are continuous without any gap. If there is a gap, the flow of the coating liquid is hindered at that portion, so that the coating liquid may accumulate on the lower end surface of the glass substrate. In this sense, it is desirable that the glass substrate and the back plate are closely adhered and bonded at least at the lower end of the glass substrate.
In order to securely attach and bond the glass substrate and the back plate, it is preferable that both the attaching surfaces are smooth and configured so as to abut without any gap.

Although a part of the back plate exposed below the glass substrate can provide a certain effect even if it is a part of the entire length of the lower end of the glass substrate, it may be provided including the entire length of the lower end of the glass substrate. preferable. Thus, the coating liquid can be prevented from accumulating over the entire length of the edge portion at the lower end of the glass substrate, and the coating film can be reliably and uniformly formed. The glass substrate and the back plate may be bonded and bonded one to one, or a plurality of glass substrates may be bonded and bonded to one back plate. The back plate may be made of any material as long as it can be attached and bonded to the glass substrate with a liquid and does not contaminate the coating liquid, and a metal plate such as aluminum or stainless steel, a glass plate, or the like can be used.

That is, in the dip coating method according to the first aspect, a coating film can be formed on the entire surface of the glass substrate to be coated, and a uniform coating film can be formed without accumulation of edge portions. it can. Therefore, the entire glass substrate can be used as an anti-glare mirror or the like, and the yield is high. Further, since the thickness of the back plate can be reduced, the entire volume can be reduced even when the glass substrate and the back plate are attached and bonded. Therefore, when immersing in the coating liquid and lifting, the relative speed difference between the lifting speed and the descending speed of the liquid surface is small, and the effect on the coating can be almost negligible. Thereby, the trouble of adjusting the lifting speed can be omitted, and a coating film of stable quality can be formed. Further, since the entire thickness can be reduced even when the glass substrate and the back plate are attached and bonded, the width of the dipping tank can be reduced, and dip coating can be performed with a small amount of coating liquid.

When the thickness of the glass substrate is large, the coating liquid accumulates on the lower end surface of the glass substrate, and it may be difficult to move to the surface of the back plate. Therefore, it is desirable that the back plate has a thick plate portion below the glass substrate and in contact with the lower end surface of the glass substrate. As a result, the flow of the coating liquid is smoothly performed, and the coating liquid can be more reliably prevented from accumulating at the edge of the glass substrate.

The thickness of the thick plate portion is not particularly limited as long as its surface height does not exceed the height of the surface of the glass substrate to be coated. However, it is desirable that the thickness of the thick plate portion be as thick as possible. It is particularly desirable to have a structure that is flush with the surface to be coated. This allows the coating liquid to flow more smoothly.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. In the present embodiment, the dip coating method of the present invention is used to form a tungsten oxide film on the glass substrate of the anti-glare mirror. (Example 1) First, a glass substrate on which an ITO film is formed by sputtering is prepared. As shown in FIG. 1, the glass substrate 1 is formed in a predetermined rearview mirror shape, has a plate thickness of about 1.1 mm, and has a surface of 1500 to 3 mm.
A 500 ° ITO film 10 is formed.

Next, a back plate 2 made of glass having a thickness of about 1.1 mm and having substantially the same shape as the glass substrate 1 is prepared, and a support plate 3 made of a glass plate having a thickness of about 1.1 mm is attached to one end of the back plate 2. From the top. Then, an appropriate amount of an alcohol solution of tungsten alkoxide is dropped on the back surface of the glass substrate 1 where the ITO film 10 is not formed,
The surfaces of the back plate 2 to which the support plate 3 is not bonded are pressed together. At this time, the glass substrate 1 and the back plate 2 are vertically shifted, and the lower end surface 20 of the back plate 2 is placed below the glass substrate 1.
To be expressed. As a result, the glass substrate 1 and the back plate 2 are bonded and bonded by the surface tension of the alcohol solution of tungsten alkoxide.

Next, as shown in FIG. 2, a dip tank 4 containing an alcohol solution (coating liquid) of tungsten alkoxide having the same composition as that used for the bonding between the glass substrate 1 and the back plate 2 is prepared. The support plate 3 is gripped from above by the clip 5, and the clip 5 is suspended from a dipping device (not shown), and the whole of the glass substrate 1 and the back plate 2 bonded and bonded is immersed in the dip tank 4.

Then, the clip 5 is lifted by driving the dipping device, and the glass substrate 1 and the back plate 2 adhered and joined.
From the dip tank 4. At this time, the glass substrate 1 is firstly pulled up, and after the entire glass substrate 1 is pulled up, the lower end surface 20 of the back plate 2 is pulled up. Then, the coating liquid 11 attached to the surface of the ITO film 10 of the glass substrate 1 flows down from the lower end surface of the glass substrate 1 to the lower end surface 20 of the back plate 2 as shown in FIG. A coating film made of an alcohol solution of tungsten alkoxide is applied to the surface of the ITO film 10 with a uniform thickness without being accumulated at the lower edge portion.

The coating film is hydrolyzed with moisture in the air, and after drying the alcohol, the glass substrate 1 and the back plate 2 are separated and baked under a predetermined condition, whereby the ITO film 10 of the glass substrate 1 is formed. A tungsten oxide film is uniformly formed on the surface. Therefore, according to the dip coating method of this embodiment, the ITO film 10
A tungsten oxide film having a uniform thickness on the surface of the substrate. Therefore, the entire glass substrate 1 can be used as it is for manufacturing the anti-glare mirror without performing a step such as excision. Further, the total thickness of the glass substrate 1 and the back plate 2 is about 2.2 mm, so that the width of the dip tank 4 can be reduced, and the amount of the coating liquid in the dip tank 4 may be small. Therefore, the yield of the coating liquid is extremely high.

Further, since the glass substrate 1 is bonded to the back plate 2 with a large area, distortion of the glass substrate 1 at the time of coating is prevented, and unevenness such as a suction pattern occurs when used as an anti-glare mirror. No defects. Embodiment 2 In Embodiment 1, when the thickness of the glass substrate 1 is increased, the coating liquid may not flow down to the lower end surface 20 of the back plate 2 exposed below the glass substrate 1. Therefore, in this embodiment, as shown in FIG. 4, a base 21 made of a glass plate is adhered to the lower end surface 20 of the back plate 2,
The surface of the base 21 is configured to be continuous with the surface of the ITO film 10.

In this embodiment, when the coating liquid is pulled out of the dipping tank 4, the coating liquid is transferred from the ITO film 10 to the base 21.
Runs down smoothly onto the surface of the surface. Therefore, even if the glass substrate 1 is thick, the coating liquid does not accumulate at the edge of the lower end of the glass substrate 1, and the tungsten oxide film can be formed with a uniform thickness as a whole. (Embodiment 3) In the above embodiment, the glass substrate and the back plate
In this embodiment, a plurality of back plates are provided on one support plate, and a glass substrate is bonded to each back plate.

That is, as shown in FIGS. 5 and 6, a support plate 3 made of a plate material made of an aluminum alloy is prepared, and a plurality of back plates 2 are placed on the surface of the support plate 3 at intervals in the vertical and horizontal directions. Fix the glass substrate 1 on each back plate 2
In the same manner as in Example 1. Then, the entire support plate 3 is immersed in the coating liquid in the dip tank 4 by suspending the upper portion of the support plate 3 and then gradually pulled up.
Then, the coating liquid adhering to the surface of each glass substrate 1 flows down the surface of the glass substrate 1 and then along the lower end surface of the glass substrate 1, and then the surface of the back plate 2 exposed below each glass substrate 1. Flow down. Therefore, the coating liquid does not accumulate on the lower edge portion of each glass substrate 1, and a tungsten oxide film having a uniform thickness is formed on the surface of each glass substrate 1.

[0029]

According to the dip coating method of the present invention, a coating film having a uniform thickness can be formed on the entire glass substrate. Eliminating the man-hour to cut off the no longer needed portion and improving the yield.

Further, according to the dip coating method of the present invention, a coating film having a uniform thickness can be formed on the entire glass substrate even when a thick glass substrate is used.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state of a glass substrate before being immersed in a dip tank in one embodiment of the present invention.

FIG. 2 is an explanatory perspective view showing a state in which a glass substrate is about to be immersed in a dip tank in one embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a state of a glass substrate after being lifted from a dipping tank in one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a state of a glass substrate before being immersed in a dipping bath in a second embodiment of the present invention.

FIG. 5 is an explanatory perspective view showing a state in which a glass substrate is about to be immersed in a dipping tank in a third embodiment of the present invention.

FIG. 6 is a sectional view of a main part showing a state of a glass substrate before being immersed in a dipping bath in a third embodiment of the present invention.

[Explanation of symbols]

1: glass substrate 2: back plate 3: support plate 4: dip tank 5: clip 10: I
TO film 20: Lower end surface 21: Base (thick plate)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiro Oshima 3-260 Toyota, Oguchi-cho, Niwa-gun, Aichi Prefecture Inside Tokai Rika Electric Works, Ltd. 4G059 AA01 AB01 AC05 EA01 EA03 EB05 GA01 GA04 GA12

Claims (2)

[Claims] 1. A step of bonding a back plate to a back surface of a surface to be coated of a glass substrate via a liquid so as to protrude from a lower end surface of the glass substrate, and bonding the glass substrate together with the back plate to the lower end surface. A step of dipping the glass substrate together with the back plate from the upper end surface to form a coating film on the surface to be coated, and a step of separating the glass substrate and the back plate. ,
A dip coating method for a glass substrate, comprising: 2. The method according to claim 1, wherein the back plate has a thick plate portion below the glass substrate and in contact with a lower end surface of the glass substrate.