Edge cleaning agent recycling system and method

Abstract

This invention provides a system and method for recovering edge cleaning agents. The method includes: a reboiler removal step, in which waste edge cleaning agent containing PGME and PGMEA is stirred and evaporated to obtain a reboiler-free recovery liquid; a primary ion removal step, in which the main ions in the reboiler-free recovery liquid are removed to produce a primary deionized recovery liquid; a low-boiling point removal step, in which low-boiling point substances including water in the primary deionized recovery liquid are removed to obtain a low-boiling point removal recovery liquid; a fractionation step, in which the low-boiling point removal recovery liquid is distilled to remove a mixture containing PGMEA to obtain a fractionated recovery liquid containing PGME; a rectification step, in which the fractionated recovery liquid is distilled to remove organic impurities to obtain a rectification recovery liquid; a flash boiling step, in which the rectification recovery liquid is flash boiled to remove metal ions to obtain a flash boiling recovery liquid; a filtration step, in which the flash boiling recovery liquid is filtered to remove particles larger than nanometers to produce a filtered recovery liquid; and a further ion removal step, in which the remaining ions in the filtered recovery liquid are removed to produce electronic-grade regenerated PGME. The system and method of this invention can produce electronic-grade regenerated PGME with a purity of 99.99 wt% or higher.

Description

Technical Field

[0001] This invention relates to a system and method for recycling edge cleaning agents, and more particularly to a recycling system and method for recovering waste edge cleaning agents and producing PGMEs that meet electronic grade specifications. Prior Technology

[0002] In microelectronics manufacturing processes, during spin coating of photoresist, excess photoresist is thrown to the edge of the wafer due to centrifugal force. Most of the photoresist is removed from the wafer, but a small portion remains. Because the relative velocity of the airflow at the wafer edge is very high, the residual photoresist solidifies more quickly, accumulating to form raised edges. Furthermore, due to surface tension, a small amount of photoresist may even flow along the wafer edge to the back side, causing contamination.

[0003] Therefore, if the photoresist protruding at the edge is not removed, the robotic arm that receives the wafer may not be able to pick it up accurately, which will affect the precision and consistency of the photoresist pattern in subsequent processes. Therefore, it is necessary to use an edge cleaning agent to remove the photoresist protruding at the edge of the wafer.

[0004] The main components of the edge bead remover (EBR) are propylene glycol monomethyl ether (PGME) and propylene glycol monomethyl ether acetate (PGMEA).

[0005] Currently, in applications, waste edge cleaning agents after wafer cleaning often contain impurities such as water, organic matter, metal ions, and particulate matter. The current methods for treating waste edge cleaning agents mostly involve incineration to recover energy or distillation to produce industrial-grade solvents. These industrial-grade solvents are frequently used as diluents in the coatings industry.

[0006] Specifically, the current process for recycling waste edge cleaning agents into industrial-grade solvents typically uses two distillation units. The first unit removes substances with boiling points higher than PGMEA from the bottom, while the second unit removes substances with boiling points lower than PGME from the top, thus obtaining industrial-grade solvents. However, this method cannot remove organic impurities with boiling points between PGMEA (146°C) and PGME (120°C). In particular, waste edge cleaning agents from the electronics industry contain many organic compounds that are difficult to separate from PGMEA using distillation. Therefore, the purity of the recovered solvent product is affected, and it can only be used to produce industrial-grade solvents with lower utilization value, making it impossible to reuse it in electronic-grade edge cleaning agents.

[0007] In addition to purity requirements, electronic-grade edge cleaning agents also have high requirements for moisture content, metal element content, and particle count. Therefore, it is not possible to recycle waste edge cleaning agents into edge cleaning agents that meet the specifications of the electronics industry using only two distillation units.

[0008] Therefore, if we can overcome the technical hurdles in recycling waste edge cleaning agents in the electronics industry and manufacture recycled solvents that meet the specifications of the electronics industry for reuse, it will enhance the utilization value of recycled solvents and help promote the development of a circular economy. Summary of the Invention

[0009] In view of this, the purpose of the present invention is to provide a system and method for recycling edge cleaning agents, which can recover edge cleaning agents from waste and produce them in accordance with electronic grade PGME specifications.

[0010] An edge cleaning agent recycling system, comprising: The reboiler removal unit is configured to receive waste edge cleaning agent containing propylene glycol methyl ether and propylene glycol methyl ether acetate, and to stir and evaporate it to separate the reboiler, thereby obtaining a reboiler-free recovery liquid; The primary ion removal unit, connected to the reboiler removal unit, is configured to receive the reboiler removal recovery liquid and remove the main portion of the ions therein by ion exchange to produce a primary deionized recovery liquid; A low-boiling-point substance removal unit, connected to a primary ion removal unit, is configured to receive the primary ion removal recovery liquid and separate it using distillation, a high-gravity rotating bed, or evaporative permeation to remove low-boiling-point substances, thereby obtaining a low-boiling-point substance-free recovery liquid, wherein the low-boiling-point substances include water; The fractionation unit, connected to the low-boiling-point removal unit, is configured to receive the low-boiling-point removal recovery liquid and distill it to separate the mixture containing propylene glycol methyl ether acetate, thereby obtaining a fractionated recovery liquid containing propylene glycol methyl ether. A distillation unit, connected to a fractionation unit, is configured to receive the fractionated recovery liquid and distill it to separate organic impurities, thereby obtaining a distillation recovery liquid; The flash boiling unit, connected to the distillation unit, is configured to receive the distillation recovery liquid and flash boil it to separate metal ions, thereby obtaining the flash boil recovery liquid; A filtration unit, connected to the flash boiling unit, is configured to receive the flash boiling recovery liquid and filter it to remove particles larger than nanometers, thereby generating a filtrate recovery liquid; and An advanced ion removal unit, connected to the filtration unit, is configured to receive the filtrate recovery liquid and remove the remaining ions therein by ion exchange to produce electronic-grade regenerated propylene glycol methyl ether.

[0011] In one embodiment of the edge-washing agent recovery system of the present invention, the filtration unit includes: A micron-sized filtration unit, connected to the flash boiling unit, is configured to receive the flash boiling recovery liquid and filter it to remove particles larger than microns, thereby producing a primary filtration recovery liquid; and The nanofiltration unit, connected to the microfiltration unit and the advanced ion removal unit, is configured to receive the primary filtration recovery liquid and filter it to remove particles larger than the nanometer size, thereby generating the filtration recovery liquid.

[0012] In one embodiment of the edge-washing agent recycling system of the present invention, the weight ratio of propylene glycol methyl ether and propylene glycol methyl ether acetate in the waste edge-washing agent is between 4:1 and 1:1, and the total content of propylene glycol methyl ether and propylene glycol methyl ether acetate in the waste edge-washing agent is less than 99 wt%.

[0013] In one embodiment of the edge-washing agent recycling system of the present invention, the content of propylene glycol methyl ether in the electronic-grade recycled propylene glycol methyl ether is 99.99 wt% or more.

[0014] In one embodiment of the edge-washing agent recovery system of the present invention, the water content in the electronic-grade recycled propylene glycol methyl ether is less than 100 ppm, the content of cationic impurities is less than 1.5 ppb, and the content of organic impurities is less than 100 ppm. In each milliliter of electronic-grade regenerated propylene glycol methyl ether, the number of particulate impurities larger than 0.2 μm is less than 5, the number of particulate impurities larger than 0.1 μm is less than 20, and the number of particulate impurities larger than 0.05 μm is less than 100.

[0015] The present invention also provides a method for recycling edge cleaning agent, comprising the following steps: The reboiler removal step involves stirring and evaporating the waste edge cleaning agent containing propylene glycol methyl ether and propylene glycol methyl ether acetate to separate the reboiler, thereby obtaining a reboiler-free recovery solution. The primary ion removal step utilizes ion exchange to remove the majority of ions from the reboiler waste recovery solution, thereby producing a primary deionized recovery solution. The low-boiling-point substance removal step involves separating the primary deionization recovery solution using distillation, a high-gravity rotating bed, or evaporative permeation to remove low-boiling-point substances, thereby obtaining a low-boiling-point substance-free recovery solution, wherein the low-boiling-point substances include water. In the fractionation step, the recovered liquid, excluding low-boiling components, is distilled to separate the mixture containing propylene glycol methyl ether acetate (h), thereby obtaining a fractionated recovered liquid containing propylene glycol methyl ether; The distillation step involves distilling the fractionated recovery liquid to separate organic impurities, thereby obtaining the distillation recovery liquid (i); The flash boiling step involves flash boiling the distillation recovery liquid to separate metal ions, thereby obtaining the flash boiled recovery liquid. The filtration step involves filtering the flash-boiling recovery liquid to remove particles larger than the nanometer size, thereby producing a filtrate recovery liquid; and The advanced ion removal step uses ion exchange to remove the remaining ions in the filtrate to produce electronically regenerated propylene glycol methyl ether.

[0016] In one embodiment of the edge-washing agent recovery method of the present invention, the filtration step further includes: The micron-filtration step filters the flash-boiling recovery liquid to remove particles larger than micrometers, thereby producing a primary filtration recovery liquid; and The nanofiltration step involves filtering the primary filtration recovery liquid to remove particles larger than the nanometer size, thereby generating the filtration recovery liquid.

[0017] In one embodiment of the edge-washing agent recycling method of the present invention, the weight ratio of propylene glycol methyl ether and propylene glycol methyl ether acetate in the waste edge-washing agent is between 4:1 and 1:1, and the total content of propylene glycol methyl ether and propylene glycol methyl ether acetate in the waste edge-washing agent is less than 99 wt%.

[0018] In one embodiment of the edge-washing agent recycling method of the present invention, the content of propylene glycol methyl ether in the electronic-grade recycled propylene glycol methyl ether is 99.99 wt% or more.

[0019] In one embodiment of the edge-washing agent recovery method of the present invention, the water content in the electronic-grade recycled propylene glycol methyl ether is less than 100 ppm, the content of cationic impurities is less than 1.5 ppb, and the content of organic impurities is less than 100 ppm. In each milliliter of electronic-grade regenerated propylene glycol methyl ether, the number of particulate impurities larger than 0.2 μm is less than 5, the number of particulate impurities larger than 0.1 μm is less than 20, and the number of particulate impurities larger than 0.05 μm is less than 100.

[0020] The recycled PGME produced by the edge cleaning agent recovery system and method of the present invention has a purity of 99.99 wt% or higher, a water content of 100 ppm or less, a cationic impurity content of less than 1.5 ppb, and an organic impurity content of less than 100 ppm. Furthermore, in each milliliter of recycled PGME, the number of particulate impurities larger than 0.2 μm is 5 or less, the number of particulate impurities larger than 0.1 μm is 20 or less, and the number of particulate impurities larger than 0.05 μm is 100 or less. It has extremely high purity and extremely low impurity content, meets electronic grade specifications, can be sold as electronic grade recycled PGME, and has extremely high economic value.

[0021] Furthermore, in addition to producing electronic-grade recycled PGME, it can also recycle PGMEA into industrial-grade or panel-grade solvents, further increasing the overall output value. Simple Explanation of the Diagram

[0022] Figure 1A is a schematic diagram of the front half of a washing agent recovery system according to an embodiment of the present invention; Figure 1B is a schematic diagram of the rear half of a washing agent recovery system according to an embodiment of the present invention; and Figure 2 is a flowchart of the steps of a method for recycling edge cleaning agent according to an embodiment of the present invention. Implementation

[0023] The advantages and features of the invention, as well as its implementation, will become clearer from the embodiments described below with reference to the accompanying drawings. However, the invention is not limited to the following embodiments, but can be implemented in various different forms.

[0024] Without causing contradiction, the technical features of any embodiment described in this specification can be applied to other embodiments of the present invention.

[0025] In this specification, the terms "bottom of the tower" and "top of the tower" refer to the relative concepts of the relatively heavier, less volatile products and the relatively lighter, more volatile products after separation in each unit. Although the separated "bottom products" and "top products" are usually located at the relative bottom and relative top of the unit, the use of "bottom of the tower" and "top of the tower" in this specification is only intended to describe the relative relationship of the heavier / lighter or more volatile products after separation, and is not intended to describe their location.

[0026] To achieve the aforementioned objectives, referring to Figures 1A and 1B, the present invention provides an edge cleaning agent recycling system for reprocessing waste edge cleaning agent into propylene glycol methyl ether that meets electronic grade specifications. The system includes, in sequence: a reboiler removal unit 1, a primary ion removal unit 2, a low-boiler removal unit 3, a fractionation unit 4, a distillation unit 5, a flash boiling unit 6, a micron filtration unit 7, a nano filtration unit 8, and an advanced ion removal unit 9.

[0027] The edge-washing agent recycling system of the present invention is divided into Figures 1A and 1B only for the convenience of diagram configuration, and does not mean that the recycling system of the present invention must be divided into the front and back halves shown in Figures 1A and 1B. In practice, the various units of the recycling system of the present invention are sequentially connected.

[0028] Edge cleaning agents are chemicals commonly used in lithography processes. Their main components are propylene glycol methyl ether (PGME) and propylene glycol methyl ether acetate (PGMEA). Primarily used in semiconductor manufacturing, their main function is to remove residues and / or unevenness at the edges of photoresist coatings, thereby ensuring the precision and quality of the photoresist pattern. This helps prevent unwanted contamination and improves the precision and consistency of the wafer manufacturing process.

[0029] After the edge washing process is completed, the used waste edge washing agent contains not only the main components PGME and PGMEA, but also impurities from the semiconductor substrate, such as metal ions, organic matter, reboiling substances and low-boiling substances. Therefore, the following will describe in detail the implementation of removing the above-mentioned impurities through the edge washing agent recycling system and method of the present invention to obtain electronic-grade regenerated PGME.

[0030] Referring to FIG1A, which is a schematic diagram of the first half of the edge-washing agent recovery system according to an embodiment of the present invention, the first five units of the edge-washing agent recovery system are shown, namely, reboiler removal unit 1, primary ion removal unit 2, low-boiling substance removal unit 3, fractionation unit 4, and distillation unit 5.

[0031] First, the reboiler removal unit 1 receives waste washing agent a containing PGME and PGMEA, and stirs and evaporates it to separate the reboiler c at the bottom of the column, thereby obtaining the reboiler-free recovery liquid b at the top of the column.

[0032] The weight ratio of PGME to PGMEA in waste edge cleaning agent a is between 4:1 and 1:1, and the total content of PGME and PGMEA in waste edge cleaning agent a is less than 99 wt%.

[0033] Reboilers c mainly consist of substances with boiling points above 200°C, such as long-chain, cyclic organic compounds, and reboilers containing chromogenic functional groups (such as N, S, etc.). Therefore, under normal pressure operation, the operating temperature range of the reboiler removal unit 1 can be between 145°C and 200°C, preferably between 160°C and 190°C.

[0034] On the other hand, the operating pressure range of the reboiler removal unit 1 can be between 0.1 bar and 1 bar. For example, if the operating pressure is 1 bar, the operating temperature range is preferably between 115°C and 155°C; if the operating pressure is 0.1 bar, the operating temperature range can be between 80°C and 173°C, preferably between 60°C and 80°C.

[0035] Specifically, the reboiler removal unit 1 can be a stirred evaporator, or it can be a distillation column, a thin film evaporator, a multi-effect evaporator, a scraped evaporator, etc., but it is not limited to these, as long as it can separate the reboiler c in the waste edge cleaning agent a from other components.

[0036] Subsequently, the primary ion removal unit 2 is connected to the reboiler removal unit 1, receives the reboiler removal recovery liquid b, and removes the main part of the ions in it by ion exchange to produce the primary ion removal recovery liquid d.

[0037] In the primary ion removal unit 2, the ions that are removed are, for example, potassium, sodium, calcium, magnesium, boron, etc., and the main part accounts for about 50 to 90 wt% of all ions in the waste washing agent a, preferably 70 to 90 wt%.

[0038] Specifically, the primary ion removal unit 2 can be an ion exchange resin device (e.g., a column, fixed bed, fluidized bed, etc.), which may include cation exchange resin and / or anion exchange resin. Preferably, a set of cation exchange resin and anion exchange resin is used together, wherein the cation exchange resin utilizes hydrogen ions (H+). [, + The ion exchange resin uses hydroxide ions (OH-) to exchange for anions in the water, while the anion exchange resin uses hydroxide ions (OH-) to exchange for anions, thereby reducing the ion concentration in the waste washing agent a.

[0039] When the resin in the ion exchange resin device adsorbs a large number of ions, its exchange capacity will gradually decrease. At this time, it is necessary to use strong acid or strong base to regenerate the resin and return it to its original state.

[0040] Subsequently, the low-boiling matter removal unit 3 is connected to the primary ion removal unit 2, receives the primary deionized recovery liquid d and separates it to remove the low-boiling matter f at the top of the column, thereby obtaining the low-boiling matter-removed recovery liquid e at the bottom of the column.

[0041] In the low-boiling-point removal unit 3, the low-boiling-point substances f to be removed mainly consist of organic compounds with boiling points below PGME, i.e., substances with boiling points below 110°C, which mainly include water, and in some cases may also include acetone. Therefore, the operating pressure range in the low-boiling-point removal unit 3 can be between 1 bar and 1.2 bar, and the operating temperature range can be between 95°C and 130°C, preferably between 110°C and 120°C.

[0042] Specifically, the low-boiling matter removal unit 3 can be a distillation column, a high-gravity rotating bed, or an evaporation permeation system, but is not limited to these, as long as it can separate the low-boiling matter f from other components in the primary deionization recovery liquid d.

[0043] The principle of a high-gravity rotating bed is to use the centrifugal force generated by high-speed rotation to simulate an environment exceeding the acceleration due to gravity, thereby enhancing mass transfer and separation processes. Therefore, it can be used for gas-liquid separation, solid-liquid separation, and liquid-liquid separation, and can reduce the size of the equipment.

[0044] Evaporative permeation is a membrane separation technology that combines membrane permeation and evaporation processes. It is mainly used to separate liquid mixtures, especially azeotropes or liquid mixtures with similar boiling points that are difficult to separate by conventional methods such as distillation. Therefore, it is particularly suitable for this invention.

[0045] The evaporation-permeation process includes the following stages: Permeation stage: The mixed liquid flows through one side of a selective semipermeable membrane, where specific components (usually small molecules or highly hydrophilic components) permeate, while other components are blocked; Evaporation stage: Low pressure or vacuum is usually maintained on the other side of the membrane, so the permeated substances evaporate into the gas phase after entering the other side of the membrane; Condensation and collection stage: The gas phase evaporated on the low-pressure side of the membrane can be condensed back into the liquid phase and collected.

[0046] Evaporation permeation is characterized by high separation efficiency and does not require heating the entire liquid to its boiling point, which reduces energy consumption and allows for more efficient separation of azeotropes or mixtures with similar boiling points, making it particularly suitable for this invention.

[0047] Subsequently, the fractionation unit 4 is connected to the low-boiling matter removal unit 3, receives the low-boiling matter removal recovery liquid e and distills it to separate the mixture h containing PGMEA at the bottom of the column, thereby obtaining the fractionation recovery liquid g containing PGME at the top of the column.

[0048] The main purpose of fractionation unit 4 is to separate PGMEA from PGME. PGMEA has a boiling point of 146°C, while PGME has a boiling point of 120°C. Therefore, the operating pressure range in fractionation unit 4 can be between 0.1 bar and 1.2 bar, and the operating temperature range can be between 55°C and 155°C.

[0049] When the operating pressure is between 0.1 bar and 0.15 bar, the operating temperature range is 55 to 100°C; when the operating pressure is between 1 bar and 1.2 bar, the operating temperature range is 115 to 155°C.

[0050] The main purpose of the edge cleaning agent recycling system of the present invention is to recycle PGME and reprocess it into electronic-grade recycled PGME. This is because waste edge cleaning agents in the electronics industry contain many organic substances that are difficult to separate from PGMEA by distillation, mainly including ethyl lactate, propylene glycol ethyl ether, 2-heptanone, cyclopentanone, cyclohexanone, etc.

[0051] The boiling points of these organic compounds are close to those of PGMEA or they readily form azeotropes with PGMEA. After the liquid mixture boils, the proportions of these organic compounds and PGMEA components in the vapor and liquid phases are approximately the same, making them impossible to separate by simple distillation.

[0052] Therefore, the main purpose of fractionation unit 4 is to separate PGME from the mixture containing PGMEA and organic compounds that are difficult to separate from PGMEA, so as to carry out subsequent purification of PGME.

[0053] In the mixture h containing PGMEA at the bottom of the column after being removed by fractionation unit 4, the content of PGMEA is between approximately 98.5 wt% and 99.5 wt%. Although current technology cannot regenerate PGMEA into electronic grade, it can still be further regenerated into secondary industrial grade solvents or panel grade solvents to increase the overall output value.

[0054] Subsequently, the distillation unit 5 is connected to the fractionation unit 4 to receive the fractionation recovery liquid g and distill it to separate the organic impurities j at the bottom of the column, thereby obtaining the distillation recovery liquid i at the top of the column.

[0055] The main purpose of distillation unit 5 is to separate organic impurities j, which typically contain 1-ethoxy-2-propanol and small amounts of ethyl lactate, 2-heptanone, cyclohexanone, etc. Its atmospheric boiling point is between 133°C and 155°C, and its boiling point at 0.1 bar is between 70°C and 90°C.

[0056] Therefore, the operating pressure range in distillation unit 5 can be between 0.1 bar and 1.2 bar, and the operating temperature range can be between 55°C and 145°C. For example, when the operating pressure is between 0.1 bar and 0.5 bar, the operating temperature range can be between 55°C and 100°C; when the operating pressure range is between 1 bar and 1.2 bar, the operating temperature range can be between 125°C and 145°C.

[0057] Specifically, the fractionation unit 4 and the rectification unit 5 can be distillation columns, fractionation columns, or rectification columns, but are not limited to these, as long as they can separate the target components based on the boiling point.

[0058] The separation mechanisms used in the distillation columns of the reboiler removal unit 1 and the low-boiler removal unit 3, the fractionation unit 4, or the rectification unit 5 are all based on the vapor-liquid phase equilibrium (VLE) principle. The temperature, pressure, number of trays, and feed position in the distillation device are adjusted so that each component is discharged from the bottom and top of each unit to achieve the separation effect.

[0059] Next, referring to FIG2, which is a schematic diagram of the latter half of a washing agent recovery system according to an embodiment of the present invention, the last four units of the washing agent recovery system are shown, namely, the flash boiling unit 6, the micron filtration unit 7, the nano filtration unit 8, and the advanced ion removal unit 9.

[0060] After obtaining the distillation recovery liquid i, the flash boiling unit 6 is connected to the distillation unit 5, receives the distillation recovery liquid i and flash boils it, and separates the metal ions k from the bottom of the column by extracting the mist from the top of the column, ensuring that only the vapor phase solvent can pass through, thereby obtaining the flash boiling recovery liquid m from the top of the column.

[0061] The operating pressure and temperature in the flash boiling unit 6 vary depending on the flash boiling method. For example, when flash boiling is achieved by lowering the pressure to change the boiling point, the operating pressure range in the flash boiling unit 6 can be from 0.05 bar to 0.1 bar, and the operating temperature range can be room temperature or above room temperature. When flash boiling is achieved by using a closed system combined with heating, the operating temperature range in the flash boiling unit 6 can be between 120°C and 150°C. Furthermore, since the vapor generated during flash boiling accumulates in the closed flash boiling unit 6, the operating pressure range can be slightly positive, for example, between 1 bar and 1.5 bar.

[0062] Specifically, the flash boiling unit 6 can be a flash boiling tower, but it is not limited to this, as long as it can separate the metal ions k from other components in the distillation recovery liquid i.

[0063] Subsequently, the micron filtration unit 7 is connected to the flash boiling unit 6, receives the flash boiling recovery liquid m, and filters it to remove particles larger than micron size, thereby producing the primary filtration recovery liquid o.

[0064] Subsequently, the nano-filtration unit 8 is connected to the micro-filtration unit 7, receives the primary filtration recovery liquid o, and filters it to remove particles larger than the nanometer size, thereby generating filtration recovery liquid p.

[0065] In another embodiment, the micron filter unit 7 and the nano filter unit 8 can be integrated into a single filter unit to directly remove particles larger than nanometers (including particles larger than micrometers) from the flash boiling recovery liquid m to produce the filtered recovery liquid p. However, considering the lifespan of the filter device, using the micron filter unit 7 and the nano filter unit 8 separately to remove particles of different sizes in stages is a more ideal configuration.

[0066] Specifically, the micron filter unit 7 and the nano filter unit 8 can be a filter membrane device, a fiber filter or a ceramic filter, etc., but are not limited to these, as long as they can filter particles of the target size.

[0067] Subsequently, the advanced ion removal unit 9 is connected to the nanofiltration unit 8, receives the filtered recovery liquid p, and removes the remaining ions by ion exchange to generate electron-grade regenerated PGME r.

[0068] The remaining portion refers to the ions removed accounting for 10 to 50 wt% or 10 to 30 wt% of all ions in waste edge cleaning agent a.

[0069] Specifically, the advanced ion removal unit 9 can be an ion exchange membrane (IEM) and / or a chelating resin. The ion exchange membrane can include a cation exchange membrane and an anion exchange membrane, which allow cations and anions to pass through the cation exchange membrane and anion exchange membrane respectively under the drive of an electric field.

[0070] Both ion-exchange resins and ion-exchange membranes can remove most types of ions, such as common ions like potassium, sodium, calcium, magnesium, and boron. In contrast, chelating resins can chelate specific ions, such as the commercially available 3M™ Metal Ion Purifier APP resin.

[0071] It should be noted that the target metal ions removed by the advanced ion removal unit 9 are generally no different from those of the primary ion removal unit 2 and the flash boiling unit 6; only when the advanced ion removal unit 9 is a chelating resin and has a more specific selectivity for the target metal ions removed, will the target metal ions removed by the advanced ion removal unit 9 differ from those of the primary ion removal unit 2 and the flash boiling unit 6.

[0072] The purpose of setting up the primary ion removal unit 2 and the advanced ion removal unit 9 in sequence is as follows: Since the primary ion removal unit 2 can withstand a higher ion concentration, is expected to have a longer service life and is relatively inexpensive, it is used first to remove the main part of the ions in the waste edge cleaning agent a, reducing the ion concentration to below a certain standard; while since the advanced ion removal unit 9 can withstand a lower ion concentration, is expected to have a shorter service life and is relatively expensive, its goal is to remove the remaining small amount of ions after the primary ion removal unit 2 and subsequent separation processes, so that the final regenerated PGME produced meets the electronic grade standard.

[0073] Additionally, referring to Figure 3, which is a flowchart of a method for recovering edge cleaning agent according to an embodiment of the present invention, the method sequentially includes: a reboiler removal step S1, a primary ion removal step S2, a low-boiling-point removal step S3, a fractionation step S4, a rectification step S5, a flash boiling step S6, a micron filtration step S7, a nanofiltration membrane step S8, and an advanced ion removal step S9.

[0074] First, in the reboiler removal step S1, the waste washing agent containing PGME and PGMEA is stirred and evaporated to separate the reboilers at the bottom of the column, thereby obtaining the reboiler-free recovery liquid at the top of the column.

[0075] Subsequently, in the initial ion removal step S2, ions in the main part of the reboiler recovery liquid are removed by ion exchange to produce an initial deionized recovery liquid.

[0076] Subsequently, in the low-boiling matter removal step S3, the primary deionization recovery liquid is separated by distillation, high-gravity rotating bed or evaporative permeation to remove the low-boiling matter at the top of the column, thereby obtaining the low-boiling matter-removed recovery liquid at the bottom of the column.

[0077] Subsequently, in the fractionation step S4, the low-boiling-point recovery liquid is distilled to separate the PGMEA-containing mixture at the bottom of the column, thereby obtaining the PGME-containing fractionated recovery liquid at the top of the column.

[0078] Subsequently, in the distillation step S5, the fractionated recovery liquid is distilled to separate the organic impurities at the bottom of the column, thereby obtaining the distilled recovery liquid at the top of the column.

[0079] Subsequently, in the flash boiling step S6, the distillation recovery liquid is flash boiled to separate the metal ions at the bottom of the column, thereby obtaining the flash boiled recovery liquid at the top of the column.

[0080] Subsequently, in the micron filtration step S7, the flash boiling recovery liquid is filtered to remove particles larger than micron size, thereby producing a primary filtration recovery liquid.

[0081] Subsequently, in the nanofiltration step S8, the primary filtration recovery liquid is filtered to remove particles larger than the nanometer size, thereby generating filtration recovery liquid p.

[0082] In another embodiment, the micron filtration step S7 and the nanofiltration step S8 can be integrated into the same step. However, as mentioned above, it is more ideal to remove particles of different sizes through the micron filtration step S7 and the nanofiltration step S8 respectively.

[0083] Finally, in the advanced ion removal step S9, the remaining ions in the filtrate are removed by ion exchange to generate electron-grade regenerated PGME r.

[0084] In each step of the edge-washing agent recycling method of the present invention, the same design as that in the corresponding unit of the edge-washing agent recycling system of the present invention can be adopted, for example, the same operating temperature, operating pressure, specific device used, target object, and processing mechanism, etc., so it will not be described in detail again.

[0085] The edge cleaning agent recovery system and method of the present invention have the following advantages:

[0086] (1) The regenerated PGME produced has a PGME content of ≥99.99 wt%, a water content of ≤100 ppm, a cationic impurity content of ≤1.5 ppb, and an organic impurity content of ≤100 ppm; furthermore, in each milliliter of regenerated PGME, the number of particulate impurities larger than 0.2 μm is ≤5, the number of particulate impurities larger than 0.1 μm is ≤20, and the number of particulate impurities larger than 0.05 μm is ≤100; it has extremely high purity and extremely low impurity content, meets electronic grade specifications, can be sold as electronic grade regenerated PGME, and has extremely high economic value; and

[0087] (2) In addition to recycling PGME in waste edge cleaning agent into electronic grade PGME, it can also recycle PGMEA in it into industrial grade or panel grade solvent, further enhancing the utilization value of recycled solvent and overall output value.

[0088] The effects of this invention are not limited to those described above, and those skilled in the art will clearly understand from the claims that other unmentioned effects are present.

[0089] 1: Reboiler removal unit 2: Primary ion removal unit 3: Low-boiling-point substance removal unit 4: Fractionation Unit 5: Distillation Unit 6: Flash Boiling Unit 7: Micron Filter Unit 8: Nano Filter Unit 9: Advanced ion removal unit a: Waste edge cleaning agent b: Reboiler residue recovery liquid c: Reboiler d: Primary deionization recovery solution e: Recovery liquid for removing low-boiling-point substances f: Low-boiling-point substances g: Fractionated recovery liquid h: A mixture containing propylene glycol methyl ether acetate i: Distillation recovery liquid j: Organic impurities k: Metal ions m: Flash boiling recovery liquid o: Micron-filtered recovery liquid p: Nanofiltration recovery liquid r: Electronic-grade recycled propylene glycol methyl ether S1: Reboiler removal step S2: Initial Ion Removal Steps S3: Low-boiling-point substance removal step S4: Fractionation Steps S5: Distillation Steps S6: Flash Boiling Step S7: Micron Filtration Steps S8: Nanofiltration Steps S9: Advanced Ion Removal Steps

Claims

1. A system for recycling edge cleaning agents, comprising: A reboiler removal unit is configured to receive waste edge cleaning agent containing propylene glycol methyl ether and propylene glycol methyl ether acetate, and to stir and evaporate it to separate the reboiler, thereby obtaining a reboiler-free recovery liquid; a primary ion removal unit is connected to the reboiler removal unit and is configured to receive the reboiler-free recovery liquid and remove the main ions therein by ion exchange to produce a primary deionized recovery liquid; a low-boiling-point removal unit is connected to the primary ion removal unit and is configured to receive the primary deionized recovery liquid and to separate it by distillation, a high-gravity rotating bed, or evaporative permeation to remove low-boiling-point substances, thereby obtaining a low-boiling-point-free recovery liquid, wherein the low-boiling-point substances include water; a fractionation unit is connected to the low-boiling-point removal unit and is configured to receive the low-boiling-point-free recovery liquid and to distill it to separate the mixture containing propylene glycol methyl ether acetate, thereby obtaining a fractionated recovery liquid containing propylene glycol methyl ether; A distillation unit, connected to the fractionation unit, is configured to receive the fractionation recovery liquid and distill it to separate organic impurities, thereby obtaining a distillation recovery liquid; a flash boiling unit, connected to the distillation unit, is configured to receive the distillation recovery liquid and flash boil it to separate metal ions, thereby obtaining a flash boiling recovery liquid; a filtration unit, connected to the flash boiling unit, is configured to receive the flash boiling recovery liquid and filter it to remove particles larger than nanometers, thereby producing a filtrate recovery liquid; and an advanced ion removal unit, connected to the filtration unit, is configured to receive the filtrate recovery liquid and remove the remaining ions therein by ion exchange to produce electronic-grade regenerated propylene glycol methyl ether.

2. The edge-washing agent recovery system as described in claim 1, wherein, The filtration unit includes: a micron filtration unit connected to the flash boiling unit, configured to receive the flash boiling recovery liquid and filter it to remove particles larger than micron size, thereby generating a primary filtration recovery liquid; and a nano filtration unit connected to the micron filtration unit and the advanced ion removal unit, configured to receive the primary filtration recovery liquid and filter it to remove particles larger than nano size, thereby generating the filtration recovery liquid.

3. The edge-washing agent recovery system as described in claim 1, wherein, The weight ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the waste edge cleaning agent is between 4:1 and 1:1, and the total content of propylene glycol methyl ether and propylene glycol methyl ether acetate in the waste edge cleaning agent is less than 99 wt%.

4. The edge-washing agent recovery system as described in claim 1, wherein, The propylene glycol methyl ether content in this electronic-grade recycled propylene glycol methyl ether is above 99.99 wt%.

5. The edge-washing agent recovery system as described in claim 1, wherein, In this electronic-grade regenerated propylene glycol methyl ether, the water content is less than 100 ppm, the cationic impurity content is less than 1.5 ppb, and the organic impurity content is less than 100 ppm. Furthermore, in each milliliter of this electronic-grade regenerated propylene glycol methyl ether, the number of particulate impurities with a size greater than 0.2 μm is less than 5, the number of particulate impurities with a size greater than 0.1 μm is less than 20, and the number of particulate impurities with a size greater than 0.05 μm is less than 100.

6. A method for recovering edge-washing agents, comprising the following steps: a reboiler removal step, wherein waste edge-washing agent containing propylene glycol methyl ether and propylene glycol methyl ether acetate is stirred and evaporated to separate the reboiler, thereby obtaining a reboiler-free recovery solution; a primary ion removal step, wherein the main ions in the reboiler-free recovery solution are removed by ion exchange to produce a primary deionized recovery solution; a low-boiling-point removal step, wherein the primary deionized recovery solution is separated by distillation, a rotating bed under high gravity, or evaporative permeation to remove low-boiling-point substances, thereby obtaining a low-boiling-point-free recovery solution, wherein... The low-boiling-point substance includes water; the fractionation step involves distilling the low-boiling-point substance recovery liquid to separate the mixture containing propylene glycol methyl ether acetate, thereby obtaining a fractionated recovery liquid containing propylene glycol methyl ether; the rectification step involves distilling the fractionated recovery liquid to separate organic impurities, thereby obtaining a rectified recovery liquid; the flash boiling step involves flash boiling the rectified recovery liquid to separate metal ions, thereby obtaining a flash boil recovery liquid; the filtration step involves filtering the flash boil recovery liquid to remove particles larger than nanometers, thereby producing a filtered recovery liquid; and the advanced ion removal step involves removing the remaining ions in the filtered recovery liquid by ion exchange to produce electronically regenerated propylene glycol methyl ether.

7. The method for recovering the edge-washing agent as described in claim 6, wherein, The filtration step further includes: a micron filtration step, in which the flash-boiling recovery liquid is filtered to remove particles larger than micron size, thereby producing a primary filtration recovery liquid; and a nanofiltration step, in which the primary filtration recovery liquid is filtered to remove particles larger than nano size, thereby producing the filtration recovery liquid.

8. The edge-washing agent recycling method as described in claim 6, wherein the weight ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the waste edge-washing agent is between 4:1 and 1:1, and the total content of propylene glycol methyl ether and propylene glycol methyl ether acetate in the waste edge-washing agent is 99 wt% or less.

9. The method for recovering the edge-washing agent as described in claim 6, wherein, The propylene glycol methyl ether content in this electronic-grade recycled propylene glycol methyl ether is above 99.99 wt%.

10. The method for recovering the edge-washing agent as described in claim 6, wherein, In this electronic-grade regenerated propylene glycol methyl ether, the water content is less than 100 ppm, the cationic impurity content is less than 1.5 ppb, and the organic impurity content is less than 100 ppm. Furthermore, in each milliliter of this electronic-grade regenerated propylene glycol methyl ether, the number of particulate impurities with a size greater than 0.2 μm is less than 5, the number of particulate impurities with a size greater than 0.1 μm is less than 20, and the number of particulate impurities with a size greater than 0.05 μm is less than 100.

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