Display panel recycling method

Abstract

The present invention relates to a method for recycling a display panel, the method comprising the steps of: crushing the display panel to form a first processed object, the display panel comprising a substrate comprising polyimide (PI), a first layer comprising a metal, and a second layer comprising polyethylene terephthalate (PET); separating polyethylene glycol terephthalate from the first treated material to form a second treated material; and separating the polyimide from the second treated material to form a third treated material.

Description

Technical Field

[0001] The present invention relates to a method for recycling a display panel, and more particularly to a method for recycling a flexible display panel. Background Art

[0002] With the advent of the information age, the demand for a variety of image media is increasing, and related technologies are also developing. With the rapid growth of display panel production and demand, the product cycle is gradually shortening.

[0003] In the process of manufacturing display panels, defective panels and dummy panels may be produced, and in the process of using display panels, panels with expired life may be produced. When the defective panels are disposed of by landfill or incineration, environmental pollution and resource loss may be caused. Summary of the invention

[0004] An object of the present invention is to provide a method for recycling a display panel.

[0005] However, the purpose of the present invention is not limited to the above-mentioned purpose, and the present invention can be expanded in many ways without departing from the concept and technical field of the present invention.

[0006] In order to achieve the above-mentioned purpose of the present invention, a method for recycling a display panel according to an embodiment of the present invention may include the following steps: crushing the display panel to form a first processed object, wherein the display panel includes a substrate, a first layer and a second layer, the substrate includes polyimide (PI), the first layer includes metal, and the second layer includes polyethylene terephthalate (PET); separating the polyethylene terephthalate from the first processed object to form a second processed object; and separating the polyimide from the second processed object to form a third processed object.

[0007] In one embodiment, the substrate may include a first base substrate and a buffer layer, the first base substrate may include the polyimide, and the buffer layer may be formed on the first base substrate and include silicon oxide.

[0008] In one embodiment, the buffer layer may include silicon dioxide (SiO 2 ).

[0009] In one embodiment, the step of forming the third treated product may include: immersing the second treated product in an alkaline solution; applying ultrasonic waves to the second treated product to form a fifth reactant; and recovering the polyimide from the fifth reactant.

[0010] In one embodiment, the alkaline solution may include at least one selected from the group consisting of sodium hydroxide (NaOH) and potassium hydroxide (KOH).

[0011] In one embodiment, the fifth reactant may be formed by the following Chemical Formula 1.

[0012] <Chemical Formula 1>

[0013] SiO 2 +2NaOH → Na 2 SiO 3 +H 2 O

[0014] In one embodiment, the fifth reactant may be formed by the following Chemical Formula 2.

[0015] <Chemical Formula 2>

[0016] SiO 2 +2KOH→K 2 SiO 3 +H 2 O

[0017] In one embodiment, the concentration of the alkaline solution may be 3 wt.% to 20 wt.%.

[0018] In one embodiment, in the step of forming the fifth reactant, the ultrasonic wave may be applied to the second reactant for 30 minutes to 40 minutes.

[0019] In one embodiment, the step of forming the second treated material may include the following steps: applying physical impact to the first treated material to form a first reactant; recovering the second treated material; and immersing the first reactant in an acidic solution to separate by specific gravity into the second layer and the second treated material.

[0020] In one embodiment, after performing the step of specific gravity separation, the method for recycling the display panel may further include a step of recovering the polyethylene terephthalate included in the second layer.

[0021] In one embodiment, the step of forming the second treated product may include the following steps: depolymerizing the first treated product to form a second reactant; and filtering the second reactant to recover the second treated product as a solid.

[0022] In one embodiment, the depolymerization may be performed using a solvent including at least one selected from the group consisting of glycol, methanol, and water.

[0023] In one embodiment, the method for recycling a display panel may further include the following step after the step of forming the third reactant: reducing the temperature of a liquid obtained by filtering the second reactant to recover the polyethylene terephthalate.

[0024] In one embodiment, the step of forming the second treated product may include the following steps: immersing the first treated product in dimethyl sulfoxide (DMSO) to form a third reactant; heat-treating the third reactant to form a fourth reactant; and filtering the fourth reactant to recover the second treated product as a solid.

[0025] In one embodiment, the method for recycling a display panel may further include the following step after the step of forming the third reactant: reducing the temperature of a liquid obtained by filtering the fourth reactant to recover the polyethylene terephthalate.

[0026] In one embodiment, the method for recycling a display panel may further include the following steps after the step of forming the third processed object: recovering metal from the third processed object. The step of recovering the metal may include the following steps: immersing the third processed object in an acidic solution to form metal ions; and reducing the metal ions.

[0027] In one embodiment, the acidic solution may be aquaregia.

[0028] In one embodiment, the metal may include silver (Ag).

[0029] In one embodiment, the step of forming the first processed product may be a step of forming waste materials having a size less than a predetermined size.

[0030] The method for recycling a display panel according to an embodiment of the present invention includes the following steps: crushing a display panel to form a first processed object, wherein the display panel includes a substrate, a first layer and a second layer, the substrate includes polyimide (PI), the first layer includes a metal, and the second layer includes polyethylene terephthalate (PET); separating the polyethylene terephthalate from the first processed object to form a second processed object; and separating the polyimide from the second processed object to form a third processed object. Accordingly, the incineration cost can be reduced, and the resources included in the waste panel can be reused, thereby contributing to environmental, social and corporate governance (ESG) activities.

[0031] Furthermore, the display panel recycling method may further include a step of recovering metal from the third processed product after forming the third processed product, thereby recovering and reusing valuable metals.

[0032] However, the effects of the present invention are not limited to the above effects, and various extensions can be achieved without departing from the concept and technical field of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a front view of a display panel according to an embodiment.

[0034] Figure 2 It is along Figure 1 Cross-sectional view taken along line I-I'.

[0035] Figure 3 It is used to describe the Figure 2 FIG. 1 is a diagram of a substrate in a display panel.

[0036] Figure 4 It is used to describe the Figure 2 A diagram of the first layer in the display panel.

[0037] Figure 5 is a flowchart for illustrating a method for reusing a display panel according to an embodiment of the present invention.

[0038] Figures 6 to 11 It is used to illustrate Figure 5 FIG. 1 is a diagram showing a method for reusing a display panel.

[0039] Description of Reference Numerals

[0040] SUB: Substrate EL: First layer

[0041] PRO: Second layer OB1: First processed object

[0042] OB2: Second processed object OB3: Third processed object

[0043] ME: Metal SC1, ..., SCn: Scrap DETAILED DESCRIPTION

[0044] Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals are used for the same components in the drawings, and repeated descriptions of the same components will be omitted.

[0045] Figure 1 is a front view of a display panel according to an embodiment.

[0046] Reference Figure 1The display panel PA may have a variety of planar shapes. For example, the display panel PA may have a rectangular shape. However, the present invention is not limited thereto. For example, the display panel PA may have a variety of shapes such as a circular shape and an elliptical shape. In addition, the corners of the display panel PA may have an angular shape, or may also have a curved shape.

[0047] For example, the display panel PA may be a flexible display device. In this case, at least one area of ​​the display panel PA can be deformed. In detail, the display panel PA may be folded, bent, or folded. However, the present invention is not limited thereto. For example, the display panel PA may be a rigid display device.

[0048] In an embodiment, the display panel PA may include a display area DA and a non-display area NDA.

[0049] The display area DA may be an area where an image is displayed. To this end, pixels may be arranged in the display area DA. For example, the display panel PA may be an organic light-emitting display device including an organic light-emitting diode. However, the present invention is not limited thereto. The display panel PA may include multiple types of pixels.

[0050] The display area DA may have various planar shapes, such as rectangular, circular, elliptical, etc. However, the present invention is not limited thereto.

[0051] A plurality of pixels may be arranged in the display area DA according to a variety of arrangement structures. For example, a plurality of pixels may be arranged to be spaced apart from each other along a first direction. Alternatively, the plurality of pixels may also be arranged to be spaced apart from each other along a second direction. The second direction may intersect with the first direction. However, the present invention is not limited thereto.

[0052] The display area DA may be defined on at least one surface of the display panel PA. For example, the display area DA may be defined on the front surface of the display panel PA. Optionally, the display area DA may also be defined on the rear surface or the side surface of the display panel PA. The side surface may intersect with the front surface (or the rear surface). The side surface may be defined by a first direction and a third direction. The third direction may intersect with the first direction and the second direction. Optionally, the side surface may be defined by the second direction and the third direction. However, the present invention is not limited thereto.

[0053] The non-display area NDA may be an area where no image is displayed. That is, the plurality of pixels may not be arranged in the non-display area NDA. Circuit structures (e.g., wiring, pads, drive circuits, etc.) for driving the plurality of pixels may be arranged in the non-display area NDA. The non-display area NDA may include a black ink layer so that the circuit structures, etc. are not visible from the outside of the display panel PA. However, the present invention is not limited to this. For example, the ink layer may be omitted, and the circuit structures may also be arranged at other locations.

[0054] The non-display area NDA may be adjacent to the display area DA. For example, the non-display area NDA may surround the display area DA. However, the present invention is not limited thereto. For example, the non-display area NDA may also be located only on one side of the display area DA.

[0055] Figure 2 It is along Figure 1 Cross-sectional view taken along line I-I'. Figure 3 It is used to describe the Figure 2 FIG. 1 is a diagram of a substrate in a display panel. Figure 4 It is used to describe the Figure 2 A diagram of the first layer in the display panel.

[0056] Reference Figure 1 and Figure 2 , the display panel PA may include a substrate SUB, a circuit wiring layer TFT, a light emitting layer EL, an encapsulation layer TFE and a protection layer PRO.

[0057] For example, the display panel PA may be a flexible display. In this case, the substrate SUB and the encapsulation layer TFE included in the display panel PA may contain a substance having a flexible property.

[0058] In one embodiment, the substrate SUB may include a material having flexible properties. For example, the substrate SUB may include a polymer organic matter, plastic, etc. Specifically, the substrate SUB may include polyethersulfone (PES: polyethersulphone), polyacrylate (PAR: polyacrylate), polyetherimide (PEI: polyetherimide), polyethylene naphthalate (PEN: polyethylenenaphthalate), polyethylene terephthalate (PET: polyethyleneterephthalate), polyphenylene sulfide (PPS: polyphenylenesulfide), polyarylate (PAR: polyarylate), polyimide (PI: polyimide), polycarbonate (PC: polycarbonate), cellulose triacetate (CTA: cellulosetriacetate), cellulose acetate propionate (CAP: celluloseacetatepropionate), etc. These may be used alone or in combination with each other. However, the present invention is not limited thereto.

[0059] Reference Figure 3 For example, the substrate SUB may have a multi-layer structure. For example, the substrate SUB may include a first base substrate BS1, a buffer layer BFR, and a second base substrate BS2.

[0060] For example, the first base substrate BS1 and the second base substrate BS2 may include the same material. In one embodiment, the first base substrate BS1 and the second base substrate BS2 may include polyimide (PI). The physical properties of the polyimide may not change within a range of about -273 degrees to about 400 degrees.

[0061] However, the present invention is not limited thereto. Figure 2 In the above description, the substrate SUB includes two base substrates, but the substrate SUB may include only one base substrate. For example, one of the first base substrate BS1 and the second base substrate BS2 may be omitted.

[0062] The buffer layer BFR may prevent impurities from penetrating into the transistor. In addition, the buffer layer BFR may uniformly form the active pattern by adjusting a speed at which heat is provided during a crystallization process (eg, a process for forming an active pattern included in the transistor).

[0063] In one embodiment, the buffer layer BFR may be disposed on the first base substrate BS1 .

[0064] For example, the buffer layer BFR may include an inorganic material. In one embodiment, the buffer layer BFR may include silicon nitride (SiN x ), silicon oxide (SiO x ), silicon oxynitride (SiO x N y ) and the like. These may be used alone or in combination with each other. However, the present invention is not limited thereto. In one embodiment, the buffer layer BFR may include silicon dioxide (SiO 2 ).

[0065] Compared with a rigid display (e.g., a display including a glass substrate), the flexible display may be difficult to support other structures. Therefore, the flexible display can be manufactured by sequentially forming a first base substrate BS1, a buffer layer BFR, a second base substrate BS2, and other structures on a carrier substrate (e.g., a glass substrate) and then removing the carrier substrate.

[0066] Refer again Figure 2 A circuit wiring layer TFT may be arranged on the substrate SUB. For example, the circuit wiring layer TFT may include transistors, data lines, gate lines, power lines, etc. constituting each of the plurality of pixels. Optionally, the circuit wiring layer TFT may also include control lines, etc.

[0067] Reference Figure 2 and Figure 4 A light emitting layer EL may be disposed on the circuit wiring layer TFT. The light emitting layer EL may include a first electrode EL1, a light emitting material layer EML, and a second electrode EL2. Electrons and holes flowing in from the first electrode EL1 and the second electrode EL2 may be combined in the light emitting material layer EML to generate light.

[0068] A first electrode EL1 may be disposed on the substrate SUB. For example, the first electrode EL1 may be an anode.

[0069] For example, the first electrode EL1 may include a highly reflective metal. The highly reflective metal may include silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), etc. These may be used alone or in combination with each other. However, the present invention is not limited thereto. In one embodiment, the first electrode EL1 may include silver (Ag).

[0070] However, the present invention is not limited thereto. For example, in the display panel (eg, Figure 1In the case where the display panel PA) has a back-light emitting structure, the first electrode EL1 may include a conductive oxide. For example, the first electrode EL1 may include a conductive oxide. The conductive oxide may include indium tin oxide, indium zinc oxide, zinc oxide, indium oxide, indium gallium oxide, aluminum oxide zinc oxide, etc. These may be used alone or in combination with each other. However, the present invention is not limited thereto.

[0071] A light emitting material layer EML may be disposed on the first electrode EL1. For example, the light emitting material layer EML may include an organic light emitting material.

[0072] The light-emitting layer EL may further include a functional layer FUN. The functional layer FUN may be an auxiliary layer that assists the light emission of the light-emitting layer EL. For example, the functional layer FUN may include a first functional layer FU1, a second functional layer FU2, a third functional layer FU3, and a fourth functional layer FU4. For example, the first functional layer FU1 may be a hole injection layer HIL, the second functional layer FU2 may be a hole transport layer HTL, the third functional layer FU3 may be an electron transport layer ETL, and the fourth functional layer FU4 may be an electron injection layer EIL. However, the present invention is not limited thereto. For example, the type, quantity, arrangement order, etc. of the auxiliary layers included in the functional layer FUN may be changed in various ways.

[0073] A second electrode EL2 may be disposed on the light emitting material layer EML. For example, the second electrode EL2 may be a cathode. Here, the first functional layer FU1 and the second functional layer FU2 may be stacked between the first electrode EL1 and the light emitting material layer EML, and the third functional layer FU3 and the fourth functional layer FU4 may be stacked between the light emitting material layer EML and the first electrode EL1.

[0074] For example, the second electrode EL2 may include the highly reflective metal. However, the present invention is not limited thereto. For example, in the case where the display panel has the back-light emitting structure, the second electrode EL2 may include the highly reflective metal. In one embodiment, the second electrode EL2 may include silver (Ag).

[0075] Refer again Figure 2 , an encapsulation layer TFE may be arranged on the light emitting layer EL.

[0076] As described above, the light emitting layer EL may include the organic light emitting substance. The organic light emitting substance may be deteriorated by moisture or oxygen. To prevent this, the light emitting layer EL may be covered by an encapsulation layer TFE.

[0077] In the case of the flexible display, the encapsulation layer TFE may include a substance having the flexible property.

[0078] For example, the encapsulation layer TFE may have a single-layer structure. For example, the encapsulation layer TFE may be an inorganic film of a single-layer structure. The encapsulation layer TFE including the inorganic film may have high mechanical strength. For example, the inorganic film may include silicon nitride (SiN x ), silicon oxynitride (SiO x N y ) etc. These can be used alone or in combination with each other. As another example, the encapsulation layer TFE can also be an organic film of a single-layer structure. For example, the organic film can include acrylate etc. The upper surface of the encapsulation layer TFE including the organic film can be flat.

[0079] However, the present invention is not limited thereto. As another example, the encapsulation layer TFE may have a multilayer structure. For example, the encapsulation layer TFE may include at least one inorganic film and at least one organic film. The sealing property of the encapsulation layer TFE having the multilayer structure may be greater than the sealing property of the encapsulation layer TFE having the single-layer structure (for example, the property of preventing foreign matter from entering the light-emitting layer EL).

[0080] A protective layer PRO may be arranged on the encapsulation layer TFE. For example, the protective layer PRO may include a polymer substance. For example, the protective layer PRO may include polymethyl methacrylate (PMMA: polymethylmethacrylate), polyvinylidene chloride (PVDC: polyvinylidene chloride), polyvinylidene fluoride (PVDF: polyvinylidene fluoride), polystyrene (PS: polystyrene), polyacrylate (PAR: polyacrylate), polyetherimide (PEI: polyetherimide), polyethylene naphthalate (PEN: polyethylene naphthalate), polyethylene terephthalate (PET: polyethylene terephthalate); polyphenylene sulfide (PPS: polyphenylenesulfide), polyarylate (PAR: polyarylate), polyimide (PI: polyimide), polycarbonate (PC: polycarbonate), ethylene-vinyl alcohol copolymer (ethylenevinylalcoholcopolymer), etc. These can be used alone or in combination with each other. However, the present invention is not limited to this. In one embodiment, the protection layer PRO may include polyethylene terephthalate (PET).

[0081] The protective layer PRO can protect the light-emitting layer EL from moisture or oxygen. However, the present invention is not limited thereto. Figure 2 The case where the protective layer PRO is arranged only on the encapsulation layer TFE (i.e., above the display panel PA) is shown, but the protective layer PRO may also be arranged below the display panel PA. In this case, the protective layer PRO may play a role of supporting the components included in the display panel PA. The protective layer PRO may be provided in a film form.

[0082] Without removing the polyethylene terephthalate (PET), it may be difficult to decompose other parts of the display panel PA. However, the polyethylene terephthalate (PET) may be difficult to be thermally decomposed due to viscosity, color, etc. Figure 5 , Figure 7 , Figure 8 and Fig. 9 The method for separating and recovering the polyethylene terephthalate (PET) will be described later.

[0083] In reference Figures 1 to 4 In the manufacturing process of the display panel PA described above, a defective panel or a dummy piece remaining after the display panel PA is manufactured may be generated. The defective panel, dummy piece or display panel PA at the end of its service life (hereinafter referred to as "waste panel") may include various resources such as valuable metals. In the case of incineration of the waste panel, environmental pollution, increased processing costs, and resource loss may occur.

[0084] Below, refer to Figures 5 to 11 , the method for recycling the discarded panels is specifically described.

[0085] Figure 5 is a flowchart for illustrating a method for reusing a display panel according to an embodiment of the present invention. Figures 6 to 11 This is a diagram for explaining a method for recycling a display panel.

[0086] Reference Figure 5 In one embodiment, a method 1 for recycling a display panel (i.e., a waste panel) may include the following steps: forming a first processed object OB1 by crushing a display panel PA (S100); separating polyethylene terephthalate (PET) from the first processed object OB1 to form a second processed object OB2 (S200); separating polyimide (PI) from the second processed object OB2 to form a third processed object OB3 (S300); and recovering metal ME from the third processed object OB3 (S400).

[0087] exist Figure 5In the embodiment, for the sake of convenience, the method 1 for recycling the display panel PA is shown starting from the step (S100) of crushing the display panel PA, but the method 1 for recycling the display panel may further include a pre-processing process. The pre-processing process may be a process of separating PCB, cables, etc. from the waste panel.

[0088] Reference Figure 2 , Figure 5 and Figure 6 , the first processed object OB1 can be formed by crushing the display panel PA (S100).

[0089] In one embodiment, the display panel PA may include a substrate SUB including polyimide (PI), a first layer including metal ME, and a second layer including polyethylene terephthalate (PET). Figure 2 The second layer may correspond to the light emitting layer EL. Figure 2 Corresponds to the protection layer PRO.

[0090] As described above, one of the first electrode EL1 or the second electrode EL2 included in the light emitting layer EL may include a metal ME. That is, the first layer may include a metal ME. For example, the metal ME may be a valuable metal. Specifically, the valuable metal may include silver (Ag), molybdenum (Mo), aluminum (Al), zinc (Zn), tin (Sn), indium (In), titanium (Ti), copper (Cu), etc. In addition, the protective layer PRO may include polyethylene terephthalate (PET).

[0091] In one embodiment, the first processed object OB1 may be formed by pulverizing the display panel PA. The first processed object OB1 may be waste materials SC1, SC2, ..., SCn having a side size of about 1 cm or less. For example, each of the length LE1 of the first side and the length LE2 of the second side of the first waste material SC1 may be about 1 cm or less. The length LE1 of the first side and the length LE2 of the second side may be the same or different from each other.

[0092] Reference Figure 5 and Figure 7 , the step (S200) of forming the second processed object OB2 may be the step (S210) of forming the second processed object according to one embodiment. The step (S210) of forming the second processed object OB2 according to one embodiment may include the following steps: forming a first reactant by applying a physical impact to the first processed object OB1 (S212); immersing the first reactant in an acidic solution to separate the first reactant into the second layer and the second processed object OB2 by specific gravity (S214); recovering the second processed object OB2 (S216); and recovering polyethylene terephthalate (PET) included in the second layer (S218).

[0093] For example, the physical impact may be provided by an impeller. The impeller may be a component that increases the pressure and flow of a fluid. That is, if the impeller rotates while applying the physical impact, the first processed object OB1 may be decomposed into the second layer and the second processed object OB2.

[0094] For example, 100 g of approximately 1 cm 2 A sample of 1.5-1.5 m / s was placed in a 1 L reactor and physically impacted using an upward impeller. The stirring speed was about 700 RPM and the reaction time was about 30 minutes. As a result, more than 95% of the sample was decomposed into the second layer and the second processed product OB2.

[0095] In order to separate and recover the second layer and the second processed product OB2, the first reactant may be immersed in the acidic solution for gravity separation (S214). For example, immersing the first reactant in the acidic solution may mean that the surface of the acidic solution is higher than the upper surface of the first reactant. For example, the acidic solution may be sulfuric acid (H 2 SO 4 For example, the concentration of the sulfuric acid solution may be about 30 wt.% to about 40 wt.%.

[0096] The second layer and the second processed object OB2 can be easily separated and recycled by the specific gravity separation (S216, S218). For example, the polyethylene terephthalate (PET) with a relatively small specific gravity can float, while the second processed object OB2 with a relatively large specific gravity can sink. Therefore, the polyethylene terephthalate (PET) and the second processed object OB2 separated by the specific gravity can be easily separated and recycled.

[0097] For example, the specific gravity of polyethylene terephthalate (PET) is about 1.38 g / cm 3 The specific gravity of the polyimide (PI) is about 1.42 g / cm 3 Since the second treated object OB2 includes polyimide (PI) and the metal ME, the specific gravity of the second treated object OB2 may be greater than the specific gravity of the polyimide (PI).

[0098] In addition, the specific gravity of the sulfuric acid may be about 1.83 g / cm 3 The specific gravity of the sulfuric acid solution having a concentration of about 30 wt.% to about 40 wt.% may be about 1.215 g / cm 3 to about 1.299 g / cm 3The concentration of the sulfuric acid solution can be adjusted by mixing with water. As a result of using the sulfuric acid solution having a concentration of about 30 wt. % to about 40 wt. %, the polyethylene terephthalate (PET) and the second treated product OB2 are clearly separated.

[0099] In the case where the concentration of the sulfuric acid solution is less than about 30 wt. %, the sample all sinks or only a portion floats, so that it may be difficult to separate and recover polyethylene terephthalate (PET) and the second treated product OB2 from the sample.

[0100] In contrast, in the case where the concentration of the sulfuric acid solution is greater than about 40 wt. %, the sample may all float, and it may be difficult to separate and recover the polyethylene terephthalate (PET) and the second treated product OB2 from the sample.

[0101] Reference Figure 5 and Figure 8 The step (S200) of forming the second processed product OB2 may also be the step (S220) of forming the second processed product according to another embodiment. The step (S220) of forming the second processed product OB2 according to another embodiment includes the following steps: depolymerizing the first processed product OB1 to form a second reactant (S222); recovering the second processed product OB2 as a solid by filtering the second reactant (S224); and recovering polyethylene terephthalate (PET) by reducing the liquid obtained by filtering the second reactant (S226).

[0102] The depolymerization may refer to a process of breaking polymer chains by solvolysis to prepare monomers or oligomers.

[0103] In one embodiment, the depolymerization may include ethanol decomposition using glycol as a solvent, methane decomposition using methanol, hydrolysis using water, etc. However, the present invention is not limited thereto. For example, as long as the method can recover polyethylene terephthalate (PET) from the waste panel, the depolymerization is not limited.

[0104] For example, the filtration may be performed by a filter having a predetermined pore size. The pore size may be such that the second processed object OB2, which is the solid, cannot pass through.

[0105] Reference Figure 5 and Fig. 9, the step (S200) of forming the second processed object OB2 may also be the step (S230) of forming the second processed object according to another embodiment. The step (S230) of forming the second processed object OB2 according to another embodiment includes the following steps: immersing the first processed object OB1 in dimethyl sulfoxide (DMSO) to form a third reactant (S232); heat-treating the third reactant to form a fourth reactant (S234); filtering the fourth reactant to recover the second processed object OB2 as a solid (S236); and lowering the temperature of the liquid obtained by filtering the fourth reactant to recover the polyethylene terephthalate (PET) (S238).

[0106] For example, the heat treatment temperature may be about 190° C. In the case where the heat treatment temperature is lower than about 190° C., the polyethylene terephthalate (PET) may not be dissolved. Accordingly, the polyethylene terephthalate (PET) may not be separated and recovered.

[0107] Reference Figure 5 and Fig.10 In one embodiment, the polyimide (PI) may be separated from the second processed object OB2 to form a third processed object OB3 (S300).

[0108] In one embodiment, the step of forming the third processed object OB3 (S300) may include the following steps: immersing the second processed object OB2 in an alkaline solution (S302); applying ultrasound to the second processed object OB2 to form a fifth reactant (S304); and recovering the polyimide (PI) from the fifth reactant (S306).

[0109] In one embodiment, the alkaline solution may be sodium hydroxide (NaOH), potassium hydroxide (KOH), etc. However, the present invention is not limited thereto. For example, the alkaline solution may be any solution that can provide -OH groups.

[0110] In one embodiment, the concentration of the alkaline solution may be about 3 wt.% to about 20 wt.%. According to the toxic substance standard, when the concentration of the alkaline solution is greater than about 5 wt.%, it may be classified as a toxic substance. In order to prevent classification as the toxic substance, the concentration of the alkaline solution may be less than about 5 wt.%.

[0111] In one embodiment, the ultrasonic wave may be applied to the second object OB2 for about 30 minutes to about 40 minutes. As the ultrasonic wave is applied, the substrate (e.g., Figure 2 Swelling may occur in the substrate SUB). As described above, the substrate may include a buffer layer (e.g., Figure 3 A buffer layer BFR) is provided, and the buffer layer may include silicon oxide (eg, silicon dioxide).

[0112] In one embodiment, the fifth reactant may be formed by the following chemical formula (chemical formula 1 or chemical formula 2). In other words, the substrate (in detail, the buffer layer) included in the second processed object OB2 may be peeled off while the swelling phenomenon occurs by the alkaline solution. Therefore, the substrate may be easily separated from the second processed object OB2.

[0113] <Chemical Formula 1>

[0114] SiO 2 +2NaOH → Na 2 SiO 3 +H 2 O

[0115] <Chemical Formula 2>

[0116] SiO 2 +2KOH→K 2 SiO 3 +H 2 O

[0117] Reference Figure 5 and Fig.11 In one embodiment, the metal ME can be recovered from the third processed object OB3 (S400). The step of recovering the metal ME (S400) can include the following steps: immersing the third processed object OB3 in an acidic solution to form metal ions (S402); and reducing the metal ions (S404).

[0118] In one embodiment, the metal ME may be a valuable metal. For example, the metal ME may include silver (Ag), etc. However, the present invention is not limited thereto.

[0119] In one embodiment, the acidic solution may be aqua regia. The aqua regia may refer to a strong acid obtained by mixing concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of about 3:1. However, the present invention is not limited thereto. As long as it is an etchant for extracting precious metals, the acidic solution may not be limited.

[0120] For example, the metal ions can be reduced by various methods. For example, the metal ions can be reduced and recovered into metal ME by electrolysis, ion reduction method, etc.

[0121] Reference Figures 5 to 11 The polyethylene terephthalate (PET) and the polyimide (PI) can be recycled by the display panel recycling method 1. Therefore, the high-value molecular resources can be recycled.

[0122] Without removing the substrate (e.g., Figure 1 In the case of a substrate SUB), the recovery efficiency of the metal ME may be reduced. For example, in the case of incinerating the substrate, the polyimide (PI) needs to be heated to about 500°C or more to be thermally decomposed, which may consume excessive fuel costs. In addition, in the case of removing the substrate by laser or the like, removing the polyimide (PI) may consume excessive time, and the larger the area and the larger the volume to be processed, the more processing time may be required.

[0123] However, according to the display panel recycling method 1 of an embodiment of the present invention, the substrate can be easily separated by the swelling phenomenon caused by the alkaline solution. Accordingly, the processing cost of the waste panel can be reduced, the polyimide (PI) can be reused, and the recovery efficiency of the metal ME can also be improved.

[0124]

Industrial Applicability

[0125] The method of reusing a display panel according to an exemplary embodiment of the present invention may be applied to a process of reusing a display device included in a computer, a laptop computer, a mobile phone, a smart phone, a smart tablet, a PMP, a PDA, an MP3 player, etc.

[0126] The above description is made with reference to exemplary embodiments of the present invention, but anyone having ordinary knowledge in the technical field should be able to understand that various modifications and changes can be made to the present invention without departing from the scope of the idea and concept of the present invention described in the claims.

Claims

1. A method for recycling a display panel, comprising the following steps: The display panel is crushed to form a first processed object, wherein: The display panel includes a substrate, a first layer and a second layer, the substrate includes a first base substrate and a buffer layer, the base substrate includes polyimide, the buffer layer is formed on the first base substrate and includes silicon dioxide, the first layer includes metal, and the second layer includes polyethylene terephthalate; separating the polyethylene terephthalate from the first processed product to form a second processed product; and The polyimide is separated from the second processed product to form a third processed product.

2. The method for recycling a display panel according to claim 1, characterized in that: The step of forming the third processed object comprises the following steps: immersing the second treated object in an alkaline solution; applying ultrasonic waves to the second treated product to form a fifth reactant; and The polyimide is recovered from the fifth reactant.

3. The method for recycling a display panel according to claim 2, characterized in that: The alkaline solution includes at least one selected from the group consisting of sodium hydroxide and potassium hydroxide.

4. The method for recycling a display panel according to claim 2, wherein: The concentration of the alkaline solution is 3 wt.% to 20 wt.%.

5. The method for recycling a display panel according to claim 2, characterized in that: In the step of forming the fifth reactant, The ultrasonic wave is applied to the second treatment object for 30 minutes to 40 minutes.

6. The method for recycling a display panel according to claim 1, characterized in that: The step of forming the second processed object comprises the following steps: Applying physical impact to the first processing material to form a first reactant; Immersing the first reactant in an acidic solution to separate by specific gravity into the second layer and the second treated product; recovering the second processed product; as well as The polyethylene terephthalate included in the second layer is recovered.

7. The method for recycling a display panel according to claim 1, characterized in that: The step of forming the second processed object comprises the following steps: Depolymerizing the first reactant to form a second reactant; filtering the second reactant to recover the second treated product as a solid, Wherein, after the step of forming the second reactant, the method further comprises the following steps: The polyethylene terephthalate is recovered by subjecting the liquid obtained by filtering the second reactant to a reduction reaction.

8. The method for recycling a display panel according to claim 7, characterized in that: The depolymerization is performed using a solvent including at least one selected from the group consisting of glycols, methanol, and water.

9. The method for recycling a display panel according to claim 1, characterized in that: The step of forming the second processed object comprises the following steps: The first treated product is immersed in dimethyl sulfoxide to form a third reactant; thermally treating the third reactant to form a fourth reactant; and filtering the fourth reactant to recover the second treated product as a solid, Wherein, after the step of forming the third reactant, the method further comprises the following steps: The polyethylene terephthalate is recovered by lowering the temperature of the liquid obtained by filtering the fourth reactant.

10. The method for recycling a display panel according to claim 1, characterized in that: After the step of forming the third processed product, the method further includes the step of recovering metal from the third processed product. Wherein, the step of recovering the metal comprises the following steps: immersing the third treated object in an acidic solution to form metal ions; and The metal ions are reduced.

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