JP3353075B2 - Glass plate recycling method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recycling a glass plate by removing a conductive film from a glass substrate having a film such as an insulating film and a conductive film formed on the surface of the glass plate, and to use the method for carrying out the method. Related to the device.

[0002]

Liquid crystal glass substrate constituting the Related Art The liquid crystal panel, for example, the Si-based insulating film formed on a glass plate, further ITO (I ndium T in O xide ) thereon film, chromium film, aluminum film, MT the (M olybdenun T antalum) film or the like of the conductive film is produced by forming a predetermined pattern by a method such as sputtering.

FIG. 4 is a schematic cross-sectional view showing the structure of a liquid crystal panel provided with a compensating liquid crystal cell. In the figure, reference numeral 11 denotes a liquid crystal cell for display, and a liquid crystal cell for compensation 12 for converting, for example, a blue-white display into a black-and-white display having a high contrast is disposed opposite to the liquid crystal cell. The display liquid crystal cell 11 is formed by forming a patterned (not shown) conductive film on one surface of a glass plate 13.
Liquid crystal glass substrates 15, 15 on which
It has a structure in which conductive films 14 and 14 are arranged to face each other with 16 interposed therebetween. Illustration of other structures is omitted. The compensating liquid crystal cell 12 has a structure in which a liquid crystal 16 is sandwiched between substrates 17 and 17. And these display liquid crystal cells
Polarizing plates 18, 18 are opposed to each other with the 11 and the compensating liquid crystal cell 12 interposed therebetween.

[0004] As for the liquid crystal glass substrate for a liquid crystal panel as described above, only a liquid crystal glass substrate which meets a predetermined quality standard is used for the liquid crystal panel. Since this quality standard is generally high, the yield of the liquid crystal glass substrate is low, and for example, a pinhole,
Most defective products having defects such as dirt and mask defects have been discarded. However, in order to effectively use resources and reduce the production cost of liquid crystal panels, it is very important to reuse expensive glass plates.

Therefore, as a conventional method of removing the conductive film for the purpose of recycling the glass plate, there is a method of dissolving and peeling the conductive film with an acid or an alkaline chemical.

[0006]

However, these chemicals also react radically with the glass material, deteriorating the surface condition such as the roughness of the glass surface due to the etching phenomenon, and can be used as a liquid crystal glass substrate. Often difficult. Therefore, in the end, they were discarded without being recycled. The present invention has been made in view of such circumstances, and by conducting electrolytic peeling of a conductive film formed on one surface of a glass plate, it is possible to regenerate the glass plate without deteriorating its surface state. An object of the present invention is to provide a method for regenerating a glass plate and an apparatus used for the method.

[0007]

According to a first aspect of the present invention, there is provided a method for regenerating a glass sheet, wherein the glass sheet is regenerated by removing the conductive film from a glass substrate having a conductive film formed on one surface of the glass plate. In the method, in the presence of an electrolytic solution, a predetermined voltage is applied between an anode in contact with the conductive film and a cathode in contact with the conductive film through a pad, whereby the conductive film is electrolytically separated. It is characterized by doing.

[0008] A method for regenerating a glass sheet according to a second invention is characterized in that, in the first invention, a voltage equal to or higher than the equilibrium electrode potential of the metal constituting the conductive film is applied to the electrode pair.

A method for regenerating a glass plate according to a third invention is characterized in that, in the first invention, a salt solution which is conductive and does not damage the glass plate is used as the electrolytic solution.

According to a fourth aspect of the present invention, there is provided an apparatus for regenerating a glass plate by removing the conductive film from a glass substrate having a conductive film formed on one surface of the glass plate. An electrode pair having an anode adapted to be brought into contact with the cathode and a cathode having a pad at the tip, a means for applying a predetermined voltage between the anode and the cathode of the electrode pair, and a means for supplying an electrolytic solution to the pad. It is characterized by having.

[0011]

The present inventors have studied various methods for peeling the conductive film without damaging the surface of the glass plate, and have tried a method using electrolysis. As a result, a good effect was obtained. FIG. 1 is a schematic diagram showing this principle. That is, the conductive film M is connected to the anode, and the coiled counter electrode K is connected to the cathode. Then, a direct current is applied between the conductive film M and the counter electrode K, and the potential of the anode with respect to the counter electrode K is maintained at a potential higher than the equilibrium electrode potential of the metal forming the conductive film M, so that the electrons inside the metal are transferred to the anode. It is guided and travels through an external circuit to the counter electrode K, where it is consumed by the electron acceptor reaction. Thereby, dissolution of the metal forming the conductive film M proceeds.

Here, the electrode reaction at the anode (conductive film M) is represented by M = M ^{n +} + ne ⁻ , and the equilibrium electrode potential E _{M / M} ^{n + at} that time is E _{M / M} ^{n +} = E _{M / M} ^{n +} ° + RT / nF · (ln a M n +) _{^{where, a M n +; M n}} + of the activity of ^{_{E M / M n + °;}} a M = a M n + = equilibrium electrode potential (standard electrode potential) in the case of 1 a _M The activity of M. As is clear from the above equation, the equilibrium electrode potential is a
Depends on _M ^{n +,} but not on the hydrogen ion concentration of the electrolyte. That is, the conductive film can be dissolved by applying a voltage higher than the equilibrium electrode potential to the device system without using an acid or an alkali agent.

According to the present invention, a conductive sheet is used to remove a conductive film by applying a predetermined voltage to the electrode pair and electrolytically peeling off the conductive film, thereby regenerating the glass sheet without damaging the surface thereof. It is possible to use.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 2 is a schematic plan view showing an embodiment of the glass sheet recycling method according to the present invention, and FIG. 3 is a schematic enlarged sectional view taken along the line III-III. 1 is a liquid crystal glass substrate having a conductive film 2 formed on the surface of a glass plate 3. A rectangular rod-shaped electrode pair 4 is provided on the liquid crystal glass substrate 1, and one electrode made of carbon is provided.
4a is connected to the anode, and the other electrode 4b made of carbon and provided with a sponge 4d as a pad at the tip is connected to the cathode. Here, the conductive film 2 is in contact with the electrode 4a,
There is no direct contact with the electrode 4b due to the presence of the sponge 4d. The electrodes 4a and 4b are held close to each other so as to provide a space 4c therebetween.
Is connected to the tank 7 through a pipe 5 provided with
An electrolytic solution is stored in the tank 7, and the electrolytic solution is supplied to the space 4c by the pump 6. Such an electrode pair 4 can be moved horizontally on the liquid crystal glass substrate 1 by a driving mechanism (not shown).

In the apparatus of the present invention having the above-described structure, when the electrolytic solution is supplied from the tank 7 to the sponge 4d provided at the tip of the electrode 4b via the pipe 5 and the pair of electrodes 4, and a predetermined voltage is applied. Conductive film 2 in contact with anode (electrode 4a)
And the electrode 4b connected to the cathode conducts, where electrolysis occurs, and the conductive film 2 dissolves and peels off due to the anodic dissolution phenomenon.

Example 1. Using a 5% aqueous solution of sodium sulfate at 20 to 30 ° C. as an electrolytic solution, applying a voltage of 6 V to the electrode pair 4 and scanning at a speed of 3 to 4 cm / s to form a conductive film As No. 2, the glass plate 3 on which a chromium film was formed was regenerated. As a result, the chromium film was dissolved and the transparent glass plate 3 could be recovered. Glass plate 3 before and after electrolysis
The results of measuring the surface roughness (Rmax) are shown before and after electrolysis.
It is 0.02 μm, and there is no change before and after electrolysis, and it can be seen that the glass plate 3 that can withstand reuse can be recovered.

Example 2 Using an aqueous solution of 2.5% magnesium chloride as an electrolytic solution, the ITO film formed on the glass plate 3 was subjected to electrolytic peeling in the same manner as in Example 1 except for the following conditions.
The ITO film was dissolved and the transparent glass plate 3 could be recovered.

EXAMPLE 3.8 Using an aqueous solution of 3.8% potassium nitrate as an electrolytic solution, the MT film formed on the glass plate 3 was subjected to electrolytic peeling.
The other conditions were the same as in Example 1. As a result, the MT film was dissolved and the transparent glass plate 3 could be recovered.

Example 4. Using an aqueous solution of 10% sodium nitrate as an electrolyte, the aluminum film formed on the glass plate 3 was subjected to electrolytic peeling under the same conditions as in Example 1 except that the aluminum film was dissolved. Then, the transparent glass plate 3 could be collected.

According to the method of the present invention, in addition to the above, electrolytic peeling can be performed with a conductive film. Needless to say, another conductive solution that does not damage the glass material can be used as the electrolytic solution. As a result of various studies, it has been found that a solution of salts such as phosphates, sulfates, and nitrates is suitable. The material of the electrode pair 4 is not limited to carbon, and the pad is not limited to the sponge 4d. By using the method of the present invention,
Defective products such as pinholes, stains, and defective masks that occur when a conductive film is formed on the surface of a glass substrate in the process of manufacturing a liquid crystal panel can be recycled. It is also possible to recycle a glass substrate for a component having a different conductive film patterning.

[0021]

As described above, the method for regenerating a glass sheet according to the present invention and the apparatus used for carrying out the method are as follows.
The present invention has excellent effects, such as being able to recycle a glass plate without damaging its surface, and greatly contributing to improvement in yield, effective use of resources, and cost reduction.

[Brief description of the drawings]

FIG. 1 is a schematic view showing the principle of the method of the present invention.

FIG. 2 is a schematic plan view showing the configuration of an apparatus used for carrying out a method for recycling a glass sheet according to the present invention.

FIG. 3 is a schematic enlarged sectional view taken along line III-III of FIG.

FIG. 4 is a schematic cross-sectional view illustrating a structure of a liquid crystal panel including a compensation liquid crystal cell.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal glass substrate 2 conductive film 3 glass plate 4 electrode pair 5 pipe 6 pump 7 tank

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-341118 (JP, A) JP-A-3-166400 (JP, A) JP-A-53-137078 (JP, A) JP-A-6-136 157053 (JP, A) JP-A-58-52498 (JP, A) JP-A-6-321581 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25F 5/00 C25F 3 / 00 G02F 1/1333 500 H01L 23/50

Claims (4)

(57) [Claims] 1. A method for regenerating a glass plate by removing the conductive film from a glass substrate having a conductive film formed on one surface of a glass plate, wherein the glass plate is brought into contact with the conductive film in the presence of an electrolytic solution. A method for regenerating a glass sheet, wherein a predetermined voltage is applied between an anode that has been made and a cathode that is brought into contact with the conductive film via a pad, whereby the conductive film is electrolytically peeled off. 2. The method for regenerating a glass sheet according to claim 1, wherein a voltage equal to or higher than an equilibrium electrode potential of a metal forming the conductive film is applied to the electrode pair. 3. The method for regenerating a glass sheet according to claim 1, wherein a salt solution that is conductive and does not damage the glass sheet is used as the electrolytic solution. 4. An apparatus for regenerating a glass plate by removing the conductive film from a glass substrate having a conductive film formed on one surface of a glass plate, wherein the anode is brought into contact with the conductive film; A glass plate comprising: an electrode pair having a cathode having a pad at a tip thereof; a unit for applying a predetermined voltage between an anode and a cathode of the electrode pair; and a unit for supplying an electrolytic solution to the pad. Playback device.