JP2002258230A - Method for separating liquid crystal from substrate and liquid crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for separating liquid crystal from a substrate which can separate the liquid crystal by using a simple method and recycle the liquid crystal. SOLUTION: In the method for separating the liquid crystal from the substrate, the substrate that the liquid crystal sticks is immersed in a liquid such as ethanol and water, etc., the liquid crystal is eluted or dispersed in the liquid, and the liquid crystal and the substrate are separated by separating an eluate or a mixture and the substrate after a current flows in an electrode on a side of an inner surface of the substrate by using a conducting electrode in an immersed state of a liquid crystal panel in a non-conductive liquid such as water, etc., and a pair of substrates are separated into respective substrates. The liquid crystal can be recovered by distilling the collected eluate or mixture.

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, material recovery from a discarded liquid crystal panel, and regeneration processing in a liquid crystal panel assembly line. And a method for separating a liquid crystal and a substrate from the substrate.

[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, the liquid crystal is decomposed by these methods, so that it is impossible to recover the liquid crystal, and it is not a very appropriate method for studying a technique for reusing the liquid crystal in the future. In addition, these methods use a high-temperature treatment, and require large-scale treatment equipment. Therefore, a simpler treatment method is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to separate a liquid crystal from a substrate constituting a liquid crystal panel by a simple method, and to recycle the liquid crystal. An object is to provide a suitable liquid crystal separation method.

[0008]

In order to achieve the above object, a method for separating liquid crystal from a substrate according to the present invention is a method for separating liquid crystal from a substrate to which liquid crystal has adhered, comprising a solvent capable of dissolving liquid crystal. The liquid crystal is eluted in a solvent by immersing the substrate having the liquid crystal adhered therein, and the liquid crystal and the substrate are separated by separating the solution and the substrate.

According to the method of the present invention, the liquid crystal can be eluted in the solvent by immersing the substrate having the liquid crystal in the solvent capable of dissolving the liquid crystal. The liquid crystal and the substrate can be easily separated.

In the method of the present invention, it is preferable to apply ultrasonic waves to the solvent or stir the solvent while the substrate having the liquid crystal adhered is immersed in the solvent. By adding this kind of operation, the dissolution of the liquid crystal in the solvent can be promoted, and the liquid crystal can be separated more efficiently.
Although various solvents can be used as the solvent, it is preferable to use ethanol in view of the solubility, properties, cost and the like of the liquid crystal.

In another liquid crystal separation method of the present invention, a liquid crystal is dispersed in a liquid by immersing a substrate having the liquid crystal in the liquid, and the liquid crystal dispersed liquid is separated from the substrate. And a substrate. In this method, it is desirable to apply ultrasonic waves to the liquid or to stir the liquid while the substrate to which the liquid crystal is attached is immersed in the liquid.

According to this method, even when a liquid that does not dissolve the liquid crystal is used, the liquid crystal is dispersed in the liquid if the substrate to which the liquid crystal is attached is immersed in the liquid. , The liquid crystal and the substrate can be easily separated. At this time, if ultrasonic waves are applied to the liquid or the liquid is stirred, the dispersion of the liquid crystal is promoted, and the liquid crystal can be separated more efficiently. Although various liquids can be used as the liquid, it is preferable to use water from the viewpoint of ease of post-treatment.
Further, high-purity water is desirable among water.

Furthermore, in the method of the present invention, the liquid crystal and the solvent, or the liquid crystal and the liquid used for dispersion can be separated by distilling the solution in which the liquid crystal has been eluted or dispersed. There are various liquids usable in the method of the present invention, such as water and organic solvents. In any case, a liquid having a boiling point lower than that of the liquid crystal is selected. Therefore, by this distillation operation, the solvent serving as a distillate and the liquid crystal serving as a residue can be separated. The separated liquid crystal can be reused through post-processing such as impurity removal and rectification, or subjected to processing such as decomposition. On the other hand, by performing this distillation operation, the solvent can be reused.

A liquid crystal according to the present invention is characterized by being obtained by using the above-described method for separating a liquid crystal from a substrate according to the present invention. In general, liquid crystal is an expensive material among constituent materials of a liquid crystal display device. However, according to the present invention, the liquid crystal can be reused and a low-cost liquid crystal can be provided.

[0015]

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 an operation procedure of the entire liquid crystal panel material recovery method including the liquid crystal separation method from a 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.
The liquid crystal panel to be processed here is one after mounting components such as a driver LSI and a FPC for driving and control are 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.

[Submerged Electro-Crushing Step (Substrate Splitting Step)] A liquid crystal panel is constructed by instantaneously applying a high-voltage current from a pair of conducting 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 flat conducting 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 current-carrying electrode 3 that is paired with the current-carrying electrode 1 at the bottom is fixed to the center of the upper part 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 they need to be brought into contact with or close to 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, about several tens 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. For the non-conductive liquid L, it is desirable to use oils (such as oleic acid and kerosene) from which a current hardly escapes from the viewpoint of crushing the liquid crystal panel 10. Considering this, it is desirable to use water.

[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 so much, and ethanol is desirable in view 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 easily separated. The liquid crystal separated and recovered by this operation can be reused after further post-treatments such as impurity removal and rectification.
Thereby, a low-cost liquid crystal can be obtained. 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. According to the present embodiment, it is possible to separate and recover the liquid crystal and the solvent by such a simple method.

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. It is desirable to use high-purity water as the water used in this case.

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 for recovering materials from a waste liquid crystal panel according to the present embodiment, the liquid crystal panel can be divided into two substrates by submerged electrolysis, and dissolution or dispersion of the exposed liquid crystal and a distillation operation can be performed. 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. Also, using a fluidized bed,
Unlike a conventional processing method using a shear crusher or a non-ferrous smelting furnace, large-scale processing equipment is not required, and the 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, regarding the substrate dividing step other than the liquid crystal separation step, the film peeling step, the indium extraction step, etc., it is also possible to arbitrarily select whether or not to carry out all of these steps. Modifications are possible without being limited to the method of morphology (electrocrushing, boiling, etc.). Further, the form of the liquid crystal panel to be processed is not limited to those shown in FIGS. 3 to 5 and various liquid crystal panels are used regardless of color / monochrome, transmission type / reflection type, passive matrix type / active matrix type, and the like. Can be processed.

Further, in the above-described embodiment, an example in which the liquid crystal separation method of the present invention is used for the purpose of recovering material from a discarded liquid crystal panel has been described. The liquid crystal separation method of the present invention can also be used in a case where the liquid crystal is removed from one adhered substrate for reproduction.

[0034]

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 energizing electrode provided at the bottom is prepared, and a liquid crystal panel is supported on several vinyl wires on the energizing electrode, and is vertically set 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 substrate 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.

Each of the two divided substrates was immersed in a container filled with water, and the container was subjected to an ultrasonic treatment using an ultrasonic cleaner. 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 of the substrates which had been divided into two by electrocrushing 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.

[0039]

As described above in detail, according to the method for separating liquid crystal from a substrate of the present invention, it is possible to carry out the separation of liquid crystal by a simple method. Moreover, the liquid crystal can be recovered by subjecting the solution in which the liquid crystal is eluted or the liquid in which the liquid crystal is dispersed to a distillation operation, which is a preferable method from the viewpoint of recycling the liquid crystal. In addition, liquid crystal is an expensive material among the constituent materials of the liquid crystal display device. However, according to the present invention, the liquid crystal can be reused and a low-cost liquid crystal can be provided.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a procedure of an operation of a method for collecting materials 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 symbols]

 1,3 energizing electrode 2 container 10 liquid crystal panel 11,12 substrate 13,14 polarizing plate 15,16 transparent electrode 21 liquid crystal L non-conductive liquid

Claims (8)

[Claims] 1. A method for separating a liquid crystal from a substrate having a liquid crystal attached thereto, wherein the liquid crystal is eluted into the solvent by immersing the substrate having the liquid crystal attached therein in a solvent capable of dissolving the liquid crystal. A method for separating liquid crystal from a substrate, comprising separating the liquid crystal and the substrate by separating the solution and the substrate. 2. The method according to claim 1, wherein ethanol is used as the solvent. 3. A method of separating the liquid crystal from a substrate to which the liquid crystal has adhered, wherein the liquid crystal is dispersed in the liquid by immersing the substrate with the liquid crystal in the liquid, and the liquid crystal is dispersed. A method for separating liquid crystal from a substrate, wherein the liquid crystal and the substrate are separated by separating a liquid and the substrate. 4. The method according to claim 3, wherein water is used as the liquid. 5. The method according to claim 1, wherein ultrasonic waves are applied to the solvent or the liquid while the substrate to which the liquid crystal is attached is immersed in the solvent or the liquid. A method for separating liquid crystal from a substrate according to claim 1. 6. The method according to claim 1, wherein the solvent or the liquid is agitated in a state where the substrate to which the liquid crystal adheres is immersed in the solvent or the liquid. A method for separating liquid crystal from a substrate as described in the above. 7. The liquid crystal and the solvent or the liquid crystal and the liquid are further separated by performing a distillation operation on a solution in which the liquid crystal is eluted or a liquid in which the liquid crystal is dispersed. 7. The method for separating liquid crystals from a substrate according to any one of the above items 6. 8. A liquid crystal obtained by using the method for separating a liquid crystal from a substrate according to claim 1. Description: