JP2002248450A - Method for dividing substrate of liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method for dividing a substrate of a liquid crystal panel in which the divided substrate is suitable for recycling. SOLUTION: The method for dividing the substrate of the liquid crystal panel comprises the liquid crystal separating step to run current to an electrode on the inner face side of the substrate using an energizing electrode, in such a state that the liquid crystal panel is soaked in a non-conducting liquid such as water and thereby divide a pair of substrates into individual ones and eluate or disperse a liquid crystal into the liquid such as ethanol by soaking the substrate with a liquid crystal deposit in the liquid and separate the liquid crystal from the substrate and the resin film separation step to separate a resin film from the substrate by boiling the substrate with the attached resin film in the water. Consequently, the recovery of the material through the described steps is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique used in the fields of, for example, recovering materials from discarded liquid crystal panels and regenerating processing in a liquid crystal panel assembly line. And a method of dividing into substrates.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been widely used in information processing devices such as personal computers, portable electronic devices such as portable telephones and portable information terminals, and household electric appliances. 3 to 5 are views showing an example of this type of liquid crystal display device, particularly showing an example of a transmission type color liquid crystal panel.
3 is an overall schematic configuration diagram, FIG. 4 is a sectional view taken along line AA in FIG. 3, and FIG. 5 is an enlarged view of a main part in FIG.

As shown in FIG. 3, in this liquid crystal panel 10, polarizing plates 13 and 14 made of a resin film are adhered to the outer surfaces of a pair of substrates 11 and 12 disposed opposite to each other. In addition, as shown in FIG. 4, indium tin oxide (hereinafter, abbreviated as ITO) is provided on the inner surfaces (surfaces facing each other) of each of the pair of substrates 11 and 12.
Transparent electrodes 15 and 16 are formed, and alignment layers 17 and 18 made of a resin such as polyimide are formed thereon. The pair of substrates 11 and 12 is a spacer 1
The substrates 9 and 9 are bonded together with an adhesive 20 therebetween, and a liquid crystal 21 is sealed in a space surrounded by the pair of substrates 11 and 12 and the adhesive 20.

More specifically, as shown in FIG. 5, a pixel electrode (transparent electrode 15) is formed on the inner surface of one of the substrates 11 on which the backlight is disposed, and an alignment layer 17 is formed thereon. ing. On the inner surface of the other substrate 12, a black matrix 22 for shielding light between pixels and R (red), G
(Green) and B (blue) color filters 23
Are formed, and the common electrode (transparent electrode 16) and the alignment layer 18 are formed in this order after being planarized by the overcoat layer 24.

[0005]

By the way, with the expansion of applications of liquid crystal display devices, liquid crystal panels discarded from liquid crystal panel manufacturing factories, and liquid crystals used in electronic devices and electric appliances discarded in the market. Increasing panel waste has become a social issue. However, at present, these waste liquid crystal panels are buried as they are, or only buried after incineration, and it has been difficult to say that sufficient measures are taken from the viewpoint of effective use of resources and lack of disposal sites.

Therefore, as a method of treating a waste liquid crystal panel,
For example, a method has been proposed in which a waste liquid crystal panel is put into a fluidized bed in which a heated solid heat medium is caused to flow to decompose and remove resins such as filters and polarizing plates and collect a glass substrate (Japanese Patent Application Laid-Open No. 2000-2000). -51829). Further, a method has been proposed in which a waste liquid crystal panel is directly sheared and crushed into glass cullet and then decomposed in a high-temperature non-ferrous smelting furnace (see Japanese Patent Application Laid-Open No. 2000-84531). However, in these methods, resins such as polarizing plates and liquid crystals are decomposed, and in the latter technique, a glass substrate is used as a substitute for silica stone. Was not. Also,
These methods use high-temperature processing and require large-scale processing equipment. Therefore, simpler processing methods are required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to divide a pair of substrates constituting a liquid crystal panel by a simple method, and at the same time, it is suitable for recycling substrates. It is an object of the present invention to provide a method for dividing a substrate of a liquid crystal panel.

[0008]

In order to achieve the above object, a method of dividing a liquid crystal panel substrate according to the present invention comprises dividing a pair of substrates of a liquid crystal panel having a pair of opposed substrates into individual substrates. A method of dividing a pair of substrates into individual substrates by passing a current to electrodes formed on inner surfaces of a pair of substrates constituting the liquid crystal panel while the liquid crystal panel is immersed in a liquid. It is characterized by doing. As a specific method, a pair of energizing electrodes is provided inside a container containing a liquid, and one energizing electrode is brought into contact with or near one end of the pair of substrates, and the other energizing electrode is connected to a pair of substrates. May be brought into contact with or close to the other end of the electrode so that current flows through the electrode by using the one energizing electrode and the other energizing electrode.

According to the method for dividing a substrate of a liquid crystal panel of the present invention, an expansion force acts on the inner surfaces of the substrates by flowing a current to the electrodes on the inner surfaces of the pair of substrates in the liquid, so that the peripheral portions of the pair of substrates are formed. Is applied in the direction in which the substrate opens outward, so that the connection between the substrates is broken, and the substrate can be divided into two substrates.
By performing this operation, the liquid crystal is exposed on the substrate.For example, in the next step, if the substrate is immersed in a solvent capable of dissolving the liquid crystal, the liquid crystal elutes into the solvent, and the solution is dissolved. By separating, the liquid crystal and the substrate can be separated. Alternatively, even when a liquid that does not dissolve the liquid crystal is used, the liquid crystal and the substrate can be separated by immersing the substrate in the liquid and dispersing the liquid crystal in the liquid.

Therefore, in the case of the substrate dividing method of the present invention, a fluidized bed is not required, and a large-scale processing facility is not required unlike a conventional processing method using a shear crusher or a non-ferrous smelting furnace. The processing of the liquid crystal panel can be performed by a simple method. Moreover, according to the present method, processing after dividing the substrate can be easily performed.

More specifically, a plate-shaped electrode is used as the one energizing electrode, a pair of substrates is mounted on the plate-shaped electrode, and a rod-shaped electrode is used as the other energizing electrode. Alternatively, a method of arranging the rod-shaped electrode at substantially the center of the upper side of the pair of substrates can be adopted.

In this method, if a flat electrode is placed on the bottom of the container, the end faces of the pair of substrates and the current-carrying electrodes can be easily brought into contact simply by placing the pair of substrates on the flat electrode. If a rod-shaped electrode is arranged at the approximate center of the upper sides of the pair of substrates as the other current-carrying electrode, current flows intensively at the approximate center of the substrate, so that a large expansion force is generated at the central portion of the substrate. It works, and the substrate can be divided more reliably.

It is desirable to use a non-conductive liquid as the liquid. A liquid having a certain degree of conductivity may be used, but in that case, the current escapes into the liquid, and the substrate cannot be divided unless the applied voltage is increased. The term "non-conductive liquid" as used herein refers to a liquid that does not have conductivity enough to allow a current to flow sufficiently through the electrodes when a certain voltage is applied to the electrodes in the liquid and to divide the pair of substrates. That is. Various liquids can be used as the non-conductive liquid, but it is preferable to use water from the viewpoint of easy post-treatment.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a flowchart showing the overall operation procedure of a method for recovering materials from a liquid crystal panel, including a method for dividing a liquid crystal panel substrate according to the present embodiment. For example, a method of collecting a material from a liquid crystal panel as shown in FIGS. 3 to 5 will be described with reference to this flowchart. Here, the liquid crystal panel to be processed is a liquid crystal panel after mounting components such as a driver LSI and an FPC for driving and control have been removed, and liquid crystal is sealed between a pair of glass substrates. , A resin film such as a polarizing plate or a retardation plate is adhered to the outer surface.

[Electrolysis in liquid (substrate dividing step)] A liquid crystal panel is constructed by instantaneously applying a high-voltage current from a pair of energizing electrodes provided at both ends of the liquid crystal panel in a non-conductive liquid. The connecting portion (the portion connected by the adhesive) between the two glass substrates to be broken is broken and divided into two, and the inner surface (the surface to which the transparent electrode, the alignment film, the liquid crystal, etc. are attached)
Exposure of the side facilitates subsequent processing such as liquid crystal recovery and indium recovery (step S in FIG. 1).
1).

More specifically, as shown in FIG. 2, the inside of a container 2 provided with a plate-like current-carrying electrode 1 at the bottom is filled with a non-conductive liquid L such as water, oleic acid or kerosene. The liquid crystal panel 10 is fixed upright on the current-carrying electrode 1. On the other hand, a rod-shaped energizing electrode 3 that is paired with the energizing electrode 1 at the bottom is fixed to the center of the upper side of the liquid crystal panel 10. At this time, the non-conductive liquid L is placed in the container 2 in such an amount that the liquid crystal panel 10 is completely immersed and at least the tip of the rod-shaped energizing electrode 3 is immersed. The electrodes 1 and 3 for energization may be fixed to the liquid crystal panel 10 by any method, but it is necessary that the electrodes 1 and 3 are brought into contact with or close to at least the transparent electrode on the inner surface of the glass substrate.

When a high-voltage DC current (for example, about several tens kV for a liquid crystal panel of about 5 to 6 inches, several tens of A to 500 A at about 1 μS) is applied to the current-carrying electrodes 1 and 3, the current is increased. 10 flows instantaneously through the transparent electrodes exposed at both ends. At that time, an expansion force acts on the inner surface side of the glass substrate, and a force is applied in a direction in which the peripheral portions of the pair of glass substrates open outward, so that the connection portion fixed with the adhesive is broken, and the two glass substrates are broken. Divided. Note that the polarity of the high voltage applied to the energizing electrodes 1 and 3 may be either positive or negative. In addition, it is desirable to pass current to the transparent electrodes on both glass substrates at the same time, but it is necessary to pass current to at least the transparent electrodes on one of the glass substrates. From the viewpoint of crushing the liquid crystal panel, it is desirable to use oils (such as oleic acid and kerosene) from which current does not easily escape from the viewpoint of crushing the liquid crystal panel, but consider the ease of subsequent processing of the liquid crystal panel 10. It is desirable to use water.

In the present embodiment, a pair of current-carrying electrodes consisting of a flat electrode and a rod-shaped electrode is used as a specific means for energizing the electrodes on the inner surfaces of the pair of substrates. Obtainable. That is, the end faces of the pair of substrates and the energizing electrode can be easily brought into contact with each other simply by placing the pair of substrates on the plate-like energizing electrode, and the rod-shaped energizing electrode is placed on the upper side of the pair of substrates. Since the current flows intensively through the electrodes at the center of the substrate, a large expansion force acts at the center of the substrate, and the substrate can be divided more reliably, which is a method with less failures. .

[Step of recovering liquid crystal from panel (liquid crystal separation step)] Next, the liquid crystal adhering to the liquid crystal panel is eluted into a solvent to separate the liquid crystal from the substrate. The liquid crystal is recovered by performing a distillation operation (step S2 in FIG. 1). Or,
The liquid crystal may be separated from the substrate by dispersing the liquid crystal in the liquid, and then the liquid crystal alone may be separated and recovered from the liquid in which the liquid crystal is dispersed.

More specifically, the liquid crystal panel having the liquid crystal exposed by electro-fracture and being divided into two parts is immersed in a solvent, and the liquid crystal attached to the liquid crystal panel is eluted into the solvent. Examples of the solvent include pentane, hexane, benzene, hydrocarbons such as toluene, alcohols such as methanol, ethanol, propanol and butanol, ethers such as diethyl ether and diisopropyl ether,
Any solvent having solubility in liquid crystals, such as an organic solvent such as ketones such as acetone, can be used. The solvent is preferably one having a relatively low boiling point so as not to raise the distillation temperature too much, and ethanol is preferably used in consideration of the solubility, properties and cost of the liquid crystal. At this time, dissolution of the liquid crystal in the solvent can be promoted by applying ultrasonic waves or stirring the solvent.

After the solvent from which the liquid crystal has sufficiently eluted is separated from the substrate, the solvent is heated under normal pressure or reduced pressure, and the solvent is distilled off to remove the solvent as the distillate and the liquid crystal as the residue. Can be separated. The liquid crystal separated and recovered by this operation can be reused through post-treatments such as impurity removal and rectification. Alternatively, processing such as decomposition can be performed. On the other hand, the solvent can be reused as it is when recovering the liquid crystal in this step.

Alternatively, when a liquid that hardly dissolves liquid crystal, such as water, is used, the liquid crystal panel, which is divided into two by electro-crushing and exposes the liquid crystal, is immersed in water, and the liquid crystal attached to the liquid crystal panel is dispersed in water. Let it. At this time, if the liquid crystal panel is simply immersed in water, a small amount of liquid crystal is dispersed and floats like an oil on the surface of water, and most of the remaining liquid crystal remains on the substrate. Therefore, if ultrasonic treatment or stirring is performed using an ultrasonic cleaner to promote the dispersion of the liquid crystal in water, the liquid crystal is dispersed in water to form an emulsion state and become emulsified. In this way, the liquid crystal is removed from the substrate.

When the above separation method using water is performed,
For the recovery of liquid crystal from a liquid mixture of water and liquid crystal, in addition to the method using distillation, the air separation method that blows air from under the container and selectively floats only the liquid crystal using the difference in wettability is also applied. It is possible. Therefore, ethanol or water is optimal as the liquid used in this step.

Although most of the liquid crystal is recovered in this step, the liquid crystal panel is divided into two in the previous electrocrushing step, and when the non-conductive liquid and the liquid crystal come into contact with each other, depending on the type of the non-conductive liquid. In some cases, the liquid crystal may be eluted or dispersed in the non-conductive liquid. In such a case, the non-conductive liquid may be recovered, and a distillation operation may be performed in the same manner as in this step to recover the liquid crystal from the non-conductive liquid. Thereby, the recovery rate of the liquid crystal can be improved.

[Removing Step of Film from Liquid Crystal-Removed Substrate (Resin Film Separating Step)] A liquid crystal panel having a resin film such as a polarizing plate or a retardation plate adhered to its surface is boiled in a liquid such as water. Thereby, the resin film and the glass substrate are separated (Step S3 in FIG. 1).

The resin films used for polarizing plates, retardation plates, etc. are polyvinyl alcohol (PVA), triacetyl cellulose (TAC), polycarbonate (PC).
, And one side thereof is coated with an adhesive, and is attached to a glass substrate. Therefore, the glass substrate in a state where the liquid crystal on the inner surface side is removed and the resin film is stuck on the outer surface side is immersed in water, and this is heated to perform a boiling treatment. By this processing, the resin film is peeled off from the glass substrate, and each can be collected.

Further, by adding a surfactant to the water used for the boiling treatment, the resin film can be surely peeled off in a shorter time. As this surfactant,
A cationic surfactant such as dodecyl ammonium acetate (DAA), an anionic surfactant such as sodium dodecyl sulfate (SDS), or a nonionic surfactant can be used. As the liquid used for the boiling treatment, in addition to water, an alcohol or a hydrocarbon that can dissolve the adhesive can be used, but water is considered to be the easiest to handle.

[Step of Dissolving ITO from Substrate (Step of Extracting Indium)]
A transparent electrode made of an O film is formed, and the ITO film is dissolved using an acid to separate the solution from the glass substrate (Step S4 in FIG. 1). As shown in FIGS. 4 and 5, the transparent electrode is covered with an alignment layer, but the alignment layer can be removed simultaneously with the peeling of the resin film in the [resin film peeling step] of the previous step. There is. In that case, since the transparent electrode is exposed, dissolution starts from the surface of the ITO film. Alternatively, even if the alignment layer is not successfully removed in the resin film peeling step of the previous step, the ITO film is exposed at the cracked portion of the alignment layer because a large number of cracks are generated in the glass substrate in the [electrolyte crushing step]. Then, dissolution starts from this part.

Then, the obtained acidic solution is collected, and the acidic solution is contacted with a cation-exchange-type extractant containing a phosphate group or a mixed solution to which a hydrophobic organic solvent is further added. Indium can be extracted. This method is disclosed in Japanese Patent Application Laid-Open No. 2000-128531, and the like. Through the above steps, various materials can be collected from the waste liquid crystal panel.

When the present method is applied to the color liquid crystal panel shown in FIG. 5, the glass substrate on the backlight side is almost recovered as a single unit, but the other glass substrate has undergone the above steps. Alone, the color filters and the like still remain on the glass substrate. The amount of color filters etc. is very small and does not pose a major problem in the reuse of glass, but if removal is necessary, polishing,
It can be removed by a method such as chemical treatment.

In the method of recovering material from a liquid crystal panel according to the present embodiment, the liquid crystal panel can be divided into two substrates by submerged electrolysis, and the liquid crystal exposed here is dissolved and the solution is distilled. The liquid crystal can be recovered by the above process, the resin film can be peeled off from the substrate in the next boiling treatment, and indium, which is one component of the ITO film, can be recovered by acid treatment and solvent extraction. Therefore, in the present method, since the liquid crystal, the glass substrate, and the resin film can be collected as materials, these members can be easily recycled. In addition, large-scale processing equipment such as a conventional processing method using a fluidized bed or using a shear crusher or a non-ferrous smelting furnace is not required, and processing can be performed by a simpler method.

The technical scope of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the spirit of the present invention. For example, the shape and arrangement of the electrodes in the electrocrushing step, the materials of various solvents (liquids) used in the processing in each step, the processing conditions, and the like are not limited to the above-described embodiments, and can be appropriately selected. Then, with respect to the liquid crystal separation step, the film peeling step, the indium extraction step, and the like after the substrate dividing step, it is optional whether or not to carry out all these steps, and the specific method of these steps is described in the above embodiment. Changes are possible without being limited to the method. Further, the form of the liquid crystal panel to be processed is not limited to those shown in FIGS.
Various liquid crystal panels can be processed irrespective of monochrome, transmission type / reflection type, passive matrix type / active matrix type, and the like.

[0033]

EXAMPLES The present inventors tried to actually recover materials from a liquid crystal panel using the method of the above embodiment. We report on the results. First, the notebook computer was disassembled and a liquid crystal display section having a size of about 6 inches was taken out. Further, components for driving and control were removed, and only the liquid crystal panel with the polarizing film attached was taken out.

Next, a container having a disc-shaped copper-made current-carrying electrode provided at the bottom is prepared, and a liquid crystal panel is supported on several vinyl wires on the current-carrying electrode, and stands vertically between the wires. At the same time, the rod-shaped iron current-carrying electrode was fixed almost in contact with the upper end of the liquid crystal panel. Then, the container was filled with water to such an extent that the tip of the rod-shaped electrode was immersed. Then, when a high voltage of about 48 kV was instantaneously applied between the pair of energizing electrodes, the liquid crystal panel was divided into two substrates.

Next, each of the substrates divided into two by the above-mentioned electro-crushing is immersed in a container filled with ethanol, and the container is subjected to ultrasonic treatment with an ultrasonic cleaner to remove the liquid crystal adhered to each substrate in ethanol. Eluted. Next, after separating the ethanol solution from the substrate, the ethanol solution is heated above the boiling point of ethanol by a reduced-pressure evaporator, and ethanol is distilled out by distillation, while the liquid crystal remains, and the ethanol and the liquid crystal are separated. I was able to. Further, since a small amount of liquid crystal was also eluted in the water used in the electrolysis, water was distilled off by distilling the solution, but the liquid crystal remained, and the liquid crystal could be recovered.

When each of the two divided substrates is immersed in a container filled with water and subjected to ultrasonic treatment with an ultrasonic cleaner, the liquid crystal is dispersed in water to be emulsified and emulsified. A mixed liquid was obtained. After the mixture was separated from the substrate, the mixture was heated to a temperature equal to or higher than the boiling point of water by a reduced-pressure evaporator and distilled. As a result, water was distilled out, while liquid crystals remained, and water and liquid crystals could be separated.

Next, each substrate which had been divided into two by electro-crushing and from which liquid crystal had been recovered with ethanol was placed in a container filled with water, which was heated to boil the water. Then
After about 30 minutes, the polarizing film attached to the substrate was peeled off and separated from the glass substrate, and each could be recovered. In addition, when a surfactant of dodecyl ammonium acetate was added to the boiling water, it was confirmed that the polarizing film was peeled off in about 5 minutes in a shorter time than when no surfactant was added.

[0038]

As described above in detail, according to the method for dividing a substrate of a liquid crystal panel of the present invention, a large-scale processing facility is not required unlike the conventional method, and the substrate can be divided by a simpler method. Can be performed. Moreover, according to the present method, processing after dividing the substrate can be easily performed.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a procedure of an operation of a method for recovering material from a liquid crystal panel according to an embodiment of the present invention.

FIG. 2 is a view showing a state of electro-crushing, which is one step of the material recovery method.

FIG. 3 is a perspective view illustrating an example of a liquid crystal display device (an example of a transmissive color liquid crystal panel).

FIG. 4 is a sectional view taken along the line AA in FIG. 3;

FIG. 5 is an enlarged view of a main part of FIG.

[Explanation of Signs] 1,3 Current-carrying electrode 2 Container 10 Liquid crystal panel 11,12 Substrate 13,14 Polarizer 15,16 Transparent electrode 21 Liquid crystal L Non-conductive liquid

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 FA18 HA01 HA02 HA12 HA16 HA18 MA20 2H090 JB02 JC13 LA01 LA06 LA09 LA15 4D004 AA24 BA06 CA02 CA44 CC03 4G075 AA37 CA13 CA51 EC21 EE01

Claims (5)

[Claims] 1. A substrate dividing method for dividing a pair of substrates of a liquid crystal panel having a pair of substrates disposed opposite to each other into individual substrates, wherein the liquid crystal panel is immersed in a liquid in the liquid crystal panel. A method of dividing a pair of substrates into individual substrates by passing a current through electrodes formed on inner surfaces of the pair of substrates. 2. A pair of energizing electrodes are provided in a container containing the liquid, and one energizing electrode is brought into contact with or close to one end of the pair of substrates, and the other energizing electrode is connected to the pair of substrates. Contact or approach the other end of the substrate,
2. The method according to claim 1, wherein a current is applied to the electrodes using the one energizing electrode and the other energizing electrode. 3. 3. A plate-like electrode is used as said one current-carrying electrode, said pair of substrates is placed on said plate-like electrode, and a rod-like electrode is used as said other current-carrying electrode. 3. The method according to claim 1, wherein the electrodes are arranged substantially at the center of the upper sides of the pair of substrates. 4. The method according to claim 1, wherein a non-conductive liquid is used as the liquid. 5. The method according to claim 4, wherein water is used as the non-conductive liquid.