阅读说明：本技术 利用废液晶显示屏制备ito透明导电玻璃的方法 (Method for preparing ITO transparent conductive glass by using waste liquid crystal display screen ) 是由 杜岩岩 陈正 彭玲 徐军 于 2020-07-07 设计创作，主要内容包括：本发明属于ITO玻璃技术领域,具体公开了一种利用废液晶显示屏制备ITO透明导电玻璃的方法,包括以下步骤：a将从废旧液晶显示屏中提取的粗铟进行电解精炼,制备得到高纯金属铟；b通过化学液相共沉淀法将高纯金属铟制备成ITO纳米粉体,然后将ITO纳米粉体压制、烧结成ITO靶材；c通过真空磁控溅射法将ITO靶材沉积到玻璃基板表面,制成ITO导电玻璃。本发明通过合理的配方设计和工艺条件控制,使得导电玻璃产品透光率大于91％,电阻率小于9×10<Sup>-4</Sup>Ω·cm。本发明的方法不仅适合工业生产,且真正实现了金属铟从回收到再利用的循环经济。(The invention belongs to the technical field of ITO glass, and particularly discloses a method for preparing ITO transparent conductive glass by using a waste liquid crystal display screen, which comprises the following steps of a, carrying out electrolytic refining on crude indium extracted from a waste liquid crystal display screen to prepare high-purity metal indium, b, preparing the high-purity metal indium into ITO nano powder by a chemical liquid-phase coprecipitation method, then, pressing and sintering the ITO nano powder into an ITO target material, c, depositing the ITO target material on the surface of a glass substrate by a vacuum magnetron sputtering method to prepare the ITO conductive glass, wherein reasonable formula design and process condition control are adopted, so that the light transmittance of a conductive glass product is larger than 91%, and the resistivity of the conductive glass product is smaller than 9 × 10 ‑4 Omega cm. The method of the invention is not only suitable for industrial production, but also really realizes the recycling economy from the recovery to the reuse of the metal indium.)

1. The method for preparing the ITO transparent conductive glass by utilizing the waste liquid crystal display screen is characterized by comprising the following steps of:

a, performing electrolytic refining on crude indium extracted from a waste liquid crystal display screen to prepare high-purity metal indium;

b, preparing high-purity metal indium into ITO nano powder by a chemical liquid-phase coprecipitation method, and then pressing and sintering the ITO nano powder into an ITO target material;

and c, depositing the ITO target on the surface of the glass substrate by a vacuum magnetron sputtering method to prepare the ITO conductive glass.

2. The method for preparing ITO transparent conductive glass using waste liquid crystal display panel as claimed In claim 1, wherein In the step a, the electrorefining uses crude indium as anode, pure indium sheet as cathode, and In₂(SO₄)₃、H₂SO₄The system is used as an electrolyte, NaCl is used as a supporting electrolyte, gelatin is used as an additive, and during electrolysis, the pH value is 2-2.5, the temperature is 30-40 ℃, and the current density is 50-60 A.m^-2The voltage is 2-3V, and the electrolysis time is 2-3 hours.

3. The method for preparing the ITO transparent conductive glass by using the waste liquid crystal display screen according to claim 2, wherein the step a is specifically as follows: dissolving crude indium in H with mass fraction of 50%₂SO₄In solution, prepare In³⁺In with a mass concentration of 50-80 g/L₂(SO₄)₃Taking the solution as electrolyte, adding NaCl and gelatin into the electrolyte to ensure that the concentration of NaCl is 80-90 g/L and the concentration of gelatin is 0.5g/L, and then using 1mol/LH₂SO₄And adjusting the pH value of the electrolyte to 2-2.5 with 6mol/LNaOH solution, and carrying out electrolytic refining when the temperature of the electrolyte is constant-temperature water bath is 30-40 ℃ to obtain high-purity metal indium.

4. The method for preparing ITO transparent conductive glass using a liquid crystal display screen according to claim 1, wherein in step b, the chemical liquid-phase co-precipitation method comprises: adding metallic indium to concentrated HNO₃Is completely dissolved In the solution to prepare In³⁺An indium salt solution with a mass concentration of 280-320 g/L according to In₂O₃/SnO₂The mass ratio is 9: 1, weighing corresponding amount of SnCl₄·5H₂Adding O into the indium salt solution to prepare a mixed salt solution; and then simultaneously adding a precipitator and a dispersant into the mixed salt solution for reaction, stopping the reaction when the pH value is 8 to obtain a mixture, adding a surface modifier into the mixture, sequentially carrying out magnetic stirring and ultrasonic dispersion, filtering, washing, drying, calcining, cooling, grinding and screening the precipitate to obtain the ITO nano powder.

5. The method for preparing ITO transparent conductive glass using liquid crystal display screen according to claim 4, wherein the precipitant is ammonia; the dispersant is sodium silicate solution; the surface modifier is polyvinylpyrrolidone, and the addition amount of the polyvinylpyrrolidone is 5-7% of the mass of the metal indium.

6. The method for preparing ITO transparent conductive glass by using the waste liquid crystal display screen according to claim 1, wherein in the step b, the sintering temperature is 1200-1500 ℃, and the time is 30-48 h.

7. The method for preparing the ITO transparent conductive glass by using the waste liquid crystal display screen according to claim 1, wherein in the step c, the vacuum magnetron sputtering method comprises the following steps: placing the glass substrate in a vacuum chamber, keeping the distance between the ITO target and the glass substrate at 20-25 mm, and injecting oxygen and argon, wherein the flow of the argon accounts for 95% -99% of the total gas; controlling sputtering pressure 2 x 10^-1～5*10^-1Pa, sputtering power of 250-500W; the temperature of the glass substrate is 350-450 ℃ during coating.

8. The method for preparing ITO transparent conductive glass by using a waste liquid crystal display screen according to claim 7, wherein the glass substrate has a silica barrier layer, the thickness of the glass substrate is 0.4-0.7 mm, the thickness of the silica barrier layer is 60-90 nm, and the thickness of the ITO target deposited on the surface of the glass substrate is 120-150 nm.

Technical Field

The invention belongs to the technical field of ITO glass, and particularly relates to a method for preparing ITO transparent conductive glass by using a waste liquid display screen.

Background

Indium Tin Oxide (ITO) transparent conductive glass has good electrical and optical properties, is an indispensable material in flat panel displays, and is widely used in flat panel display devices such as electroluminescent displays (ELDs), Electroluminescent Color Displays (ECDs), Liquid Crystal Displays (LCDs), and the like. Indium tin oxide is an n-type semiconductor material composed of In₂O₃And SnO₂The weight ratio of the components is usually 9: 1. wherein the metal indium is a liquid crystal displayAs an important raw material of the conductive coating on the ITO glass of the display, the consumption of indium by the liquid crystal panel accounts for 65 percent of the global indium yield, and the consumption of indium is increased with the increase of the annual liquid crystal panel yield. However, indium is a scarce metal, with limited reserves in the crust and very dispersed, with no separate deposits. The development of recycled indium is very important due to the lack of exploitable indium mineral resources.

At present, regenerated indium on the market is almost from ITO waste targets, is limited by process conditions and recovery cost, and the indium recovered from waste liquid displays is very little. Different from the waste ITO target material, the indium recovered from the waste liquid display ITO panel has low content and complex impurity types, and the impurity elements have great influence on the preparation and the recycling of high-purity indium. However, the indium content in the waste liquid crystal display panel is much higher than that in the mineral reserve, and if the indium in the waste liquid crystal display can be recycled, the method is an important means for effectively meeting the huge market demand in the future. At present, most of crude indium recovered from waste liquid displays has high impurity content, the purity cannot meet the requirement of practical application, the required procedures for next application are complex and various, the process conditions are not easy to control, and the key performance, reproducibility, qualification rate and the like of the obtained product cannot easily achieve the expected targets, so that the technical method for reasonably recycling the recovered crude indium at the present stage is rare.

Disclosure of Invention

The invention aims to solve the problem that crude indium recovered from a waste liquid crystal display screen is difficult to continue to be applied at present.

In order to solve the technical problems, the invention provides the following technical scheme: a method for preparing ITO transparent conductive glass by using a waste liquid display screen is characterized by comprising the following steps:

a, performing electrolytic refining on crude indium extracted from a waste liquid crystal display screen to prepare high-purity metal indium;

b, preparing high-purity metal indium into ITO nano powder by a chemical liquid-phase coprecipitation method, and then pressing and sintering the ITO nano powder into an ITO target material;

and c, depositing the ITO target on the surface of the glass substrate by a vacuum magnetron sputtering method to prepare the ITO conductive glass.

In the step a, the electrolytic refining uses crude indium as an anode, pure indium sheets as a cathode and In₂(SO₄)₃、H₂SO₄The system is used as an electrolyte, NaCl is used as a supporting electrolyte, gelatin is used as an additive, and during electrolysis, the pH value is 2-2.5, the temperature is 30-40 ℃, and the current density is 50-60 A.m^-2The voltage is 2-3V, and the electrolysis time is 2-3 hours.

The method for preparing the ITO transparent conductive glass by using the waste liquid crystal display screen comprises the following steps: dissolving crude indium in H with mass fraction of 50%₂SO₄In solution, prepare In³⁺In with a mass concentration of 50-80 g/L₂(SO₄)₃Taking the solution as electrolyte, adding NaCl and gelatin into the electrolyte to ensure that the concentration of NaCl is 80-90 g/L and the concentration of gelatin is 0.5g/L, and then using 1mol/LH₂SO₄And adjusting the pH value of the electrolyte to 2-2.5 with 6mol/LNaOH solution, and carrying out electrolytic refining when the temperature of the electrolyte is constant-temperature water bath is 30-40 ℃ to obtain high-purity metal indium.

In the step b, the chemical liquid-phase coprecipitation method comprises the following steps: adding metallic indium to concentrated HNO₃Is completely dissolved In the solution to prepare In³⁺An indium salt solution with a mass concentration of 280-320 g/L according to In₂O₃/SnO₂The mass ratio is 9: 1, weighing corresponding amount of SnCl₄·5H₂Adding O into the indium salt solution to prepare a mixed salt solution; and then simultaneously adding a precipitator and a dispersant into the mixed salt solution for reaction, stopping the reaction when the pH value is 8 to obtain a mixture, adding a surface modifier into the mixture, sequentially carrying out magnetic stirring and ultrasonic dispersion, filtering, washing, drying, calcining, cooling, grinding and screening the precipitate to obtain the ITO nano powder.

In the method for preparing the ITO transparent conductive glass by using the waste liquid crystal display screen, the precipitator is ammonia water; the dispersant is sodium silicate solution; the surface modifier is polyvinylpyrrolidone, and the addition amount of the polyvinylpyrrolidone is 5-7% of the mass of the metal indium.

In the method for preparing the ITO transparent conductive glass by using the waste liquid crystal display screen, in the step b, the sintering temperature is 1200-1500 ℃, and the time is 30-48 hours.

In the step c, the vacuum magnetron sputtering method comprises the following steps: placing the glass substrate in a vacuum chamber, keeping the distance between the ITO target and the glass substrate at 20-25 mm, and injecting oxygen and argon, wherein the flow of the argon accounts for 95% -99% of the total gas; controlling sputtering pressure 2 x 10^-1～5*10^-1Pa, sputtering power of 250-500W; the temperature of the glass substrate is 350-450 ℃ during coating.

According to the method for preparing the ITO transparent conductive glass by using the waste liquid crystal display screen, the glass substrate is provided with the silicon dioxide barrier layer, the thickness of the glass substrate is 0.4-0.7 mm, the thickness of the silicon dioxide barrier layer is 60-90 nm, and the thickness of the ITO target deposited on the surface of the glass substrate is 120-150 nm.

Compared with the prior art, the invention has the beneficial effects that:

compared with the prior art, the method has the advantages that the selectivity of purifying the metal indium by adopting an electrolytic method is high, the purity of the deposited metal indium is high, the reaction condition for preparing the ITO nano powder by adopting a chemical liquid-phase coprecipitation method is mild, the process is easy to control, the powder dispersibility is good, the repeatability of the sputtering process of the adopted vacuum magnetron sputtering method is good, the light transmittance of the product is high, and the electric conductivity of the product is good^-4Omega cm, solves the technical difficulties of low light transmittance, poor conductivity and the like of products caused by a plurality of complex problems of substandard purity of metal indium, agglomeration effect of nano powder, difficult control of ITO coating conditions and the like. The method technology and the process condition adopted by the invention are easy to realize industrialization, and compared with the prior indium recycling technology of the waste liquid crystal display, the method really realizes the purpose of metal indiumRecycling economy from recovery to reuse.

Detailed Description

The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.