KR101462997B1 - Recovery and reuse method of display panel material - Google Patents

Abstract

In order to recover ITO from the waste liquid crystal display device, before the ITO is dissolved in the strongly acidic solution, the metallic organic and inorganic materials are dissolved by using the acidic solution to increase the purity of the ITO and the dispersion agent is added to the strongly acidic solution, . A method of recovering and reusing a display panel material according to the present invention comprises the steps of: side-cutting a sealing region between an upper plate and a lower plate constituting the display panel using a knife to separate the upper plate and the lower plate; Removing the injected liquid crystal between the upper plate and the lower plate; Removing the polarizing film attached to the top plate; Dissolving and removing the color filter from the top plate using an alkaline solution; Dissolving the recovered residual material in the acidic solution after removing the color filter to remove metallic inorganic and organic materials; Dissolving the remaining ITO in the first strongly acidic solution into which the dispersant has been added; Adding a reducing agent to the first strongly acidic solution to reduce and precipitate ITO precursor particles; And a step of centrifugally separating and washing the precipitated ITO precursor particles to recover and heat-treat the ITO precursor particles.

Description

A method of recovering and reusing a display panel material,

The present invention relates to a method for recovering and reusing a display panel material, and more particularly, to a method for recovering a glass substrate and an ITO material from a display panel that is discarded after use, thereby enabling to be regenerated and reused.

Flat panel display devices including liquid crystal display devices are widely used in various electronic devices, and the manufacture and use of electronic devices continue to increase due to the development of personal electronic devices.

However, there is a problem that the resources that can support the increasing trend of the manufacture and use of such electronic devices are depleted or insufficient, and there is an increasing interest in the recycling of electronic devices that are discarded after use. In particular, in the situation where the life cycle of electronic devices is shortened due to rapid technological development, disposal of unused electronic devices is not preferable from the viewpoints of environmental protection and efficient use of resources.

Conventional recycling methods for display panels including liquid crystal display devices are mainly based on recycling viewpoints. Products containing a liquid crystal display device are crushed and powdered, and then dissolved to dissolve all the elements. There is a way to recycle each element.

However, this method causes environmental pollution by using a strong acid etching solution in the dissolving process and complicates the process of "crushing-sorting-dissolving-separating-recycling ", causing contamination and waste water generation.

To improve this, a method of reusing indium-tin-oxide (ITO) after separating the environmentally friendly without breaking the liquid crystal display device has been developed. This is a method of reusing ITO in its original composition without dissolving indium and tin separately as in the conventional method.

1 is a diagram showing a configuration of a conventional liquid crystal display device.

1, the liquid crystal display device 1 includes a lower plate 3, an upper plate 5, and a liquid crystal layer 17 formed therebetween. The lower plate 3 is vertically and horizontally arranged, A gate line 11 and a data line 13 which define a pixel of the liquid crystal display panel 10 are arranged.

The gate lines 11 and the data lines 13 are electrically connected to external driving elements (not shown) through the pads 12 and 14 formed in the non-display area of the lower substrate 3. In each pixel, as the scanning signal is applied through the gate line 11, the TFT 15 is switched to apply the image signal input through the data line 13 to the liquid crystal layer 17. [

A sealing region 7 to which a sealing material 22 is applied is formed on the outer side of the lower plate 3 and the upper plate 5 so that the lower plate 3 and the upper plate 5 are bonded together by the sealing material 22.

In order to reuse the liquid crystal display device thus formed, the lower plate 3 and the upper plate 5 of the liquid crystal display device are separated, the color filter of the upper panel is dissolved to separate ITO from the glass substrate, or the display panel is immersed in a hydrochloric acid solution The ITO is dissolved in hydrochloric acid while the temperature is being heated.

The ITO which dissolves the color filter and separates and collects the ITO after heat treatment is mixed with a large amount of impurities. In the process of heat treatment thereof, there is a limitation in removing impurities.

Also, when ITO is recovered by dissolving in hydrochloric acid, the larger the panel size, the more hydrochloric acid is required to put the panel, and thus the operator's working environment is more exposed to the risk. In addition, when ITO is recovered with hydrochloric acid, particle coarsening may occur due to intergranular aggregation in the re-precipitation process of ITO.

SUMMARY OF THE INVENTION The present invention has been made in view of the above technical background, and it is an object of the present invention to provide a method for recovering a high quality ITO material from a waste liquid crystal display device.

Another object of the present invention is to provide an ITO material recovery method capable of reducing the use of environmental pollutants and reducing the use of hazardous materials in a work process.

In order to solve the above problems, the present invention proposes a method of dissolving metallic organic and inorganic materials using an acidic solution to dissolve ITO in a strongly acidic solution to increase the purity of ITO, and adding a dispersant to the strongly acidic solution, .

That is, according to one aspect of the present invention, there is provided a method of recovering and reusing a display panel material, comprising: cutting a sealing region between a top plate and a bottom plate constituting the display panel using a knife to separate the top plate and the bottom plate; Removing the injected liquid crystal between the upper plate and the lower plate; Removing the polarizing film attached to the top plate; Dissolving and removing the color filter from the top plate using an alkaline solution; Dissolving the recovered residual material in the acidic solution after removing the color filter to remove metallic inorganic and organic materials; Dissolving the remaining ITO in the first strongly acidic solution into which the dispersant has been added; Adding a reducing agent to the first strongly acidic solution to reduce and precipitate ITO precursor particles; And a step of centrifugally separating and washing the precipitated ITO precursor particles to recover and heat-treat the ITO precursor particles.

Here, the acid solution is sulfuric acid or nitric acid, and the first strongly acidic solution is preferably hydrochloric acid.

The centrifuging, washing, recovering, and heat-treating may include a step of adding the ITO precursor recovered in the organic compound solution of indium or tin before the heat treatment, and evaporating the solvent while mixing.

Further, in order to produce the ITO ink material, the step of heat-treating may further include the step of dispersing the heat-treated ITO in an ink solution containing an organic solvent, a binder and an additive.

A method of recovering and reusing a display panel material according to the present invention includes the steps of separating a polyimide film from the lower plate using a strong alkaline solution; Dissolving ITO exposed under the polyimide film in a second strongly acidic solution; And separating SiN _x , SiO _x , Si and metal from the lower plate in which the ITO is dissolved, so that the ITO and the glass substrate of the lower plate can be reused.

According to another aspect of the present invention, there is provided a method of recovering and reusing a display panel material, comprising: cutting a sealing region between a top plate and a bottom plate constituting the display panel using a knife to separate the top plate and the bottom plate; Removing the injected liquid crystal between the upper plate and the lower plate; Removing the polarizing film attached to the top plate; Dissolving and removing the color filter from the top plate using an alkaline solution; Dissolving the recovered residual material in the acidic solution after removing the color filter to remove metallic inorganic and organic materials; Dissolving the remaining ITO in the strongly acidic solution after removing the metallic inorganic and organic materials; Introducing a dispersant into the strongly acidic solution; Adding a reducing agent to the strongly acidic solution to reduce and precipitate ITO precursor particles; And a step of centrifugally separating and washing the precipitated ITO precursor particles to recover and heat-treat the ITO precursor particles.

According to the present invention, purity is improved by removing metallic organic or inorganic substances before dissolving ITO with a strongly acidic solution, and a dispersant is added to a strongly acidic solution dissolving ITO, whereby a high-quality ITO material having fine particles can be obtained.

In addition, when ITO is dissolved in strongly acidic solution, since the powder rather than the panel is dissolved, the amount of strongly acidic solution to be used by using a container smaller than that of dissolving the panel can be reduced, It is possible to work in a safer space.

1 is a diagram showing a configuration of a conventional liquid crystal display device.
2 illustrates a method of separating upper and lower plates of a liquid crystal display device used in a method of collecting a display panel material according to an embodiment of the present invention.
3 is a flowchart showing a method of collecting a display panel blank according to an embodiment of the present invention.
4 is a flowchart illustrating a method of separating ITO in a method of collecting a display panel blank according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions.

Hereinafter, a method of recovering and reusing a display panel material according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 illustrates a method of separating upper and lower plates of a liquid crystal display device used in a method of collecting a display panel material according to an embodiment of the present invention.

As shown in Fig. 2, the liquid crystal display comprises a lower plate, an upper plate, and a liquid crystal layer 170 formed therebetween.

The lower substrate includes a glass substrate 30 and a thin film transistor 40 formed thereon. A protective film 60 is formed on the top of the thin film transistor 40 and an ITO transparent electrode 70 is formed on the protective film 60. [

The top panel also includes a glass substrate 50 and a color filter 80 formed thereon. A common electrode 110 made of ITO is formed on the color filter 80. A polarizing plate 120 is attached to the opposite surface of the glass substrate 50.

A thin film transistor is not formed in the sealing region, and a sealing material 220 such as epoxy is filled instead of the liquid crystal layer 170.

In the method for recovering the display panel material according to the embodiment of the present invention, a fine knife is inserted into the side of the edge sealing area of the liquid crystal display device, the sealing material 220 is inserted to separate the upper plate and the lower plate of the liquid crystal display device, Cut along the site. Thus, the upper and lower plates can be separated without cutting the glass substrates 30 and 50 of the upper and lower plates.

3 is a flowchart showing a method of collecting a display panel blank according to an embodiment of the present invention.

As shown in FIG. 3, the upper and lower plates are separated by cutting the epoxy 220 which holds the upper and lower plates using a knife in the lateral direction (S310).

Next, the residual liquid crystal 170 injected between the upper and lower plates is removed (S320). The remaining liquid crystals can be removed in a noncontact manner using a cleaning process.

The upper plate is taken out in a cold atmosphere, and the polarizing film 120 and the adhesive (not shown) are removed from the upper plate by the thermal expansion-contraction difference (S330).

Next, the glass substrate 50, which is a valuable resource to be reused, and the ITO layer 110 are separated from the top plate.

4 is a flowchart illustrating a method of separating ITO from a top plate in a method of recovering a display panel blank according to an embodiment of the present invention.

As shown in FIG. 4, first, the color filter 80 is dissolved using an alkaline solution (S341).

The solution remaining after dissolving and removing the culry filter 80 has other metallic organic and inorganic substances besides ITO. Therefore, when ITO is precipitated in such a state, the purity of the reused ITO material may be lowered. In order to solve this problem, in the embodiment of the present invention, metallic organic or inorganic substances including copper (Cu) are removed using an acidic solution such as sulfuric acid or nitric acid (S342).

Next, ITO having improved purity is dissolved by using a strongly acidic solution such as hydrochloric acid (S343). At this time, a dispersant is previously dissolved in the strongly acidic solution dissolving ITO. Alternatively, it is also possible to first dissolve ITO in a strongly acidic solution and add a dispersant to the solution.

The purity is improved by removing metallic organic and inorganic substances before dissolving ITO with a strongly acidic solution, and a dispersant is added to a strongly acidic solution dissolving ITO, whereby a high-quality ITO material having fine particles can be obtained.

Meanwhile, according to the embodiment of the present invention, when ITO is dissolved in a strongly acidic solution, since the powder rather than the panel is dissolved, the amount of the strongly acidic solution to be used by using the container smaller than that of dissolving the panel can be reduced, It is possible to work in a safer space such as a hood or the like.

The reducing agent is then added to the strongly acidic solution in which ITO is dissolved in this manner to reduce and precipitate ITO precursor particles (S344).

As described above, the ITO precursor particles precipitated by reduction are fine and uniform particles due to the effect of the dispersing agent.

On the contrary, when the dispersant was not added, the ITO precursor precipitated and precipitated when the reducing agent was added, and there was no dispersion effect even after the addition of the dispersant. This is because the ITO precursor particles precipitated by the reducing agent adhere to neighboring ITO precursor particles which are simultaneously deposited on the sides, and become heavier and precipitate.

Nanoparticles containing ITO precursor particles are very high in surface energy, so they go to a reaction to reduce the surface by spontaneous reaction to lower it, resulting in agglomeration of the particles and heavy weight. Once agglomerated nanoparticles do not penetrate the agglomerated particle surface even after the addition of the dispersant, there is no dispersion effect. Even if some of them are mechanically awakened, the dispersion effect is much lower than that of dispersing first.

However, when the dispersant is added before the reducing agent is added, the reducing agent is added to the ITO precursor to prevent the ITO precursor from adhering to the adjacent ITO precursor particles since the previously introduced dispersant surrounds the ITO precursor, thereby preventing the aggregation. No development was observed, and they were uniformly dispersed for a long period of time.

Precipitated ITO precursor particles are recovered by centrifugation and washing, and the ITO precursor particles are heat-treated at a temperature of 200-1300 ° C to produce an ITO nano powder material (S345). At this time, the heat treatment atmosphere can be maintained in a normal atmosphere, vacuum, oxygen, nitrogen, argon, helium, hydrogen, or a mixed atmosphere thereof.

On the other hand, the ratio of In: Sn may vary depending on the precipitation conditions of the ITO precursor, and in this case, appropriate treatment can be performed to control the composition ratio in the heat treatment process.

That is, before the ITO precursor is heat-treated, an appropriate amount of the In organic compound or the Sn organic compound is put into an environment-friendly solvent such as ethanol, and the ITO precursor precipitated in the solution is added thereto and mixed to evaporate the solvent. In or Sn is allowed to enter the ITO precursor, and then the ITO nanoparticles can be heat-treated so that the In: Sn ratio can be adjusted to a desired ratio (for example, 9: 1).

Since the ITO precursor state is before the crystal grains are formed, the In or Sn components injected later can be sufficiently coordinated with them and crystallized together later in the crystallization.

 The ITO ink material can be produced by dispersing the prepared ITO nano powder material in an ink solution containing an organic solvent, a binder and additives.

As a dispersant is added to a strongly acidic solution to obtain a finely divided ITO material, a dispersant is present on the ITO surface even after the heat treatment, so that a high quality ITO ink having good dispersibility can be produced even when the ITO ink is produced.

Meanwhile, in the method of recovering and reusing the display panel material according to the embodiment of the present invention, the glass substrate and ITO used in the lower plate as well as the upper plate of the liquid crystal display device can be recovered and reused.

Referring to FIG. 3, after the remaining liquid crystal is removed in step S320, the polyimide film is separated from the lower plate using a strong alkaline solution, and the exposed ITO is dissolved by using a strongly acidic solution.

At this time, the dispersant is already dissolved in the strongly acidic solution before dissolving ITO, and the subsequent steps are as described above with reference to steps S344 and S345 of FIG.

Further, the glass substrate of the lower plate can be reused by separating SiN _x , SiO _x , Si and metal materials from the lower plate after ITO is dissolved.

While the invention has been described in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the appended claims are intended to embrace all such modifications and variations as fall within the true spirit of the invention.

Claims (8)

As a method for recovering and reusing a display panel material,
Cutting the sealing region between the upper plate and the lower plate constituting the display panel using a knife to separate the upper plate and the lower plate;
Removing the injected liquid crystal between the upper plate and the lower plate;
Removing the polarizing film attached to the top plate;
Dissolving and removing the color filter from the top plate using an alkaline solution;
Dissolving the recovered residual material in the acidic solution after removing the color filter to remove metallic inorganic and organic materials;
Dissolving the remaining ITO in the first strongly acidic solution into which the dispersant has been added;
Adding a reducing agent to the first strongly acidic solution to reduce and precipitate ITO precursor particles; And
And recovering and recovering the ITO precursor particles by centrifugation, washing, and heat treatment;
The centrifuging, washing, recovering and heat-
And evaporating the solvent while mixing the ITO precursor recovered in the organic compound solution of indium or tin before the heat treatment, and mixing the evaporated solvent. The method according to claim 1,
A method for recovery and reuse of display panel material which is sulfuric acid or nitric acid. The method according to claim 1, wherein the first strongly acidic solution comprises:
Method of recovery and reuse of display panel material which is hydrochloric acid. delete As a method for recovering and reusing a display panel material,
Cutting the sealing region between the upper plate and the lower plate constituting the display panel using a knife to separate the upper plate and the lower plate;
Removing the injected liquid crystal between the upper plate and the lower plate;
Removing the polarizing film attached to the top plate;
Dissolving and removing the color filter from the top plate using an alkaline solution;
Dissolving the recovered residual material in the acidic solution after removing the color filter to remove metallic inorganic and organic materials;
Dissolving the remaining ITO in the first strongly acidic solution into which the dispersant has been added;
Adding a reducing agent to the first strongly acidic solution to reduce and precipitate ITO precursor particles; And
And recovering and recovering the ITO precursor particles by centrifugation, washing, and heat treatment;
After the heat treatment step,
Further comprising the step of dispersing the heat-treated ITO in an ink solution containing an organic solvent, a binder and an additive. As a method for recovering and reusing a display panel material,
Cutting the sealing region between the upper plate and the lower plate constituting the display panel using a knife to separate the upper plate and the lower plate;
Removing the injected liquid crystal between the upper plate and the lower plate;
Removing the polarizing film attached to the top plate;
Dissolving and removing the color filter from the top plate using an alkaline solution;
Dissolving the recovered residual material in the acidic solution after removing the color filter to remove metallic inorganic and organic materials;
Dissolving the remaining ITO in the first strongly acidic solution into which the dispersant has been added;
Adding a reducing agent to the first strongly acidic solution to reduce and precipitate ITO precursor particles; And
And recovering and recovering the ITO precursor particles by centrifugation, washing, and heat treatment;
Separating the polyimide film from the lower plate using a strong alkaline solution;
Dissolving ITO exposed under the polyimide film in a second strongly acidic solution; And
Separating SiN _x , SiO _x , Si and metal from the bottom plate from which the ITO is dissolved;
Further comprising the steps of: The method according to claim 6,
And the second strongly acidic solution is charged with a dispersant. As a method for recovering and reusing a display panel material,
Cutting the sealing region between the upper plate and the lower plate constituting the display panel using a knife to separate the upper plate and the lower plate;
Removing the injected liquid crystal between the upper plate and the lower plate;
Removing the polarizing film attached to the top plate;
Dissolving and removing the color filter from the top plate using an alkaline solution;
Dissolving the recovered residual material in the acidic solution after removing the color filter to remove metallic inorganic and organic materials;
Dissolving the remaining ITO in the strongly acidic solution after removing the metallic inorganic and organic materials;
Introducing a dispersant into the strongly acidic solution;
Adding a reducing agent to the strongly acidic solution to reduce and precipitate ITO precursor particles; And
Centrifuging and washing the ITO precursor particles that have been reduced and precipitated, recovering and recovering the ITO precursor particles;
≪ / RTI >
The centrifuging, washing, recovering and heat-
And evaporating the solvent while mixing the ITO precursor recovered in the organic compound solution of indium or tin before the heat treatment, and mixing the evaporated solvent.

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