A method for recovering photoresist stripping waste solution
By employing centrifugal separation, bentonite-based magnetic separation, and vacuum distillation, the problems of high energy consumption and low purity in the recovery process of photoresist stripping waste liquid have been solved, achieving efficient and environmentally friendly resource recovery and obtaining high-purity recovery liquid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANQING XINXIANGRUI CHEM CO LTD
- Filing Date
- 2025-05-28
- Publication Date
- 2026-07-21
AI Technical Summary
The existing technology for recycling photoresist stripping waste liquid has high energy consumption and low product purity, resulting in low resource utilization and serious environmental pollution.
By employing centrifugal separation, bentonite-based magnetic separation, and vacuum distillation, high-molecular solid impurities and metal ions are first removed, and then incinerated to obtain a high-purity recovery liquid.
It achieves the production of high-concentration recovery liquid with a purity of over 99.4% and a metal impurity content of less than 0.1 ppm, simplifying the process, reducing equipment footprint, and lowering environmental pollution.
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Figure BDA0005424320790000051 
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of waste liquid treatment technology, specifically relating to a method for recycling photoresist stripping waste liquid. Background Technology
[0002] In recent years, with the rapid development of my country's economy, more and more electronic products have appeared in the public eye, mainly including LCD displays and chips. In the production process of modern electronic products, factories use a large amount of photoresist to develop circuit boards. After completing the task of protecting the chip, the photoresist is stripped. The photoresist stripping process involves transferring the photoresist, which has certain strength, adhesion, and high charge density, from the chip to a stripping solution, where it dissolves in an organic solvent.
[0003] Stripping fluid, a wet electronic chemical, is mainly composed of organic solvents and a small amount of water. Organic solvents are important chemical materials with wide applications in coatings, electrochemicals, adhesives, paints, and cleaning agents. Stripping fluid is frequently used to remove photoresist in the stripping process of electronic product manufacturing, but this generates a large amount of difficult-to-manage waste stripping fluid. Photoresist waste stripping fluid contains large amounts of photoresist, water, and organic solvents, with a high content of organic solvents. If these photoresist, water, and organic solvents are not properly treated, they can lead to a large amount of pollutants entering the air or soil, generating many harmful substances and causing significant environmental pollution. Simultaneously, organic solvents can seriously harm water bodies and cause various environmental problems, as well as generate harmful gases such as carbon monoxide, and contribute to the greenhouse effect caused by nitrogen oxides and sulfides in industry.
[0004] Organic solvents refer to solvents with a certain degree of toxicity, good compatibility with environmental media, and recyclability. Currently, waste stripping liquids mainly contain organic solvents such as N-methylformamide (NMF), diethylene glycol monomethyl ether (MDG), diethylene glycol monobutyl ether (BDG), and mixtures of organic amines and alcohol ethers, as well as water. These organic waste liquids are difficult to treat due to their high concentration, complex composition, difficulty in degradation, and harm to human health. With the development of technology, more and more researchers have discovered that photoresist waste stripping liquids contain many high-value organic solvents that can be recycled. The recycling of these organic solvents can maximize resource utilization. At the same time, the production cost of stripping liquid is high, and the recycled waste stripping liquid can reduce production costs. Therefore, removing organic solvents from photoresist waste stripping liquids can reduce pollutant emissions and achieve resource recycling.
[0005] Analysis of the organic solvents contained in the waste stripping liquid revealed the following drawbacks in terms of recycling: (1) Due to the complexity and uncertainty of the molecular structure of organic solvents, some organic solvents are difficult to separate or degrade. (2) Some separation processes require high energy consumption and are not efficient, thus resulting in low recovery rate of organic solvents and low purity of recovered products in the waste stripping liquid. Summary of the Invention
[0006] This invention provides a method for recycling photoresist stripping waste liquid, which can solve the problems of high energy consumption and low product purity in the existing photoresist stripping waste liquid recycling process.
[0007] The objective of this invention can be achieved through the following technical solutions:
[0008] A method for recycling photoresist stripping waste liquid includes the following steps:
[0009] S1. The photoresist stripping waste liquid is centrifuged to remove high molecular solid impurities from the photoresist stripping waste liquid, and a pretreated stripping waste liquid is obtained.
[0010] S2. Add bentonite-based adsorbent material to the pretreated stripping waste liquid, stir, and then perform magnetic separation by a magnet to obtain purified stripping waste liquid.
[0011] S3. The purified stripping waste liquid is subjected to vacuum distillation to obtain the recovered stripping liquid and high-boiling substances.
[0012] S4. Incinerate the high-boiling-point substances and recover the stripping liquid for testing.
[0013] First, the photoresist stripping waste liquid is centrifuged to remove high molecular solid impurities. Then, bentonite-based adsorbent material is added to remove water and metal ions from the pretreated stripping waste liquid by utilizing its excellent water absorption and metal ion adsorption properties. This reduces the corrosion of equipment by metal ions during subsequent distillation and also helps to obtain high-purity recycled stripping liquid.
[0014] In some embodiments, the main components of the photoresist stripping waste liquid in S1 are N-methylformamide (NMF) and diethylene glycol methyl ether (MDG), and it also includes water and metal ion impurities.
[0015] In some embodiments, the water content of the photoresist stripping waste liquid in S1 is 1-10%.
[0016] In some implementations, the centrifugal separation process in S1 is a rotary drum sedimentation centrifugation method.
[0017] In some embodiments, the amount of bentonite-based adsorbent in S2 is 2-10% of the mass of the pretreated stripping waste liquid.
[0018] In some embodiments, S3 uses a purification column for vacuum distillation. The purification column is a sieve plate column with a top pressure of 10-12 kPa, a top temperature of 90-120°C, and a bottom temperature of 130-160°C.
[0019] In some embodiments, the raw materials for preparing the bentonite-based adsorbent material include unsaturated siloxane-modified magnetic bentonite, methacrylic acid, allyl hydroxamic acid, potassium persulfate, and N,N'-methylenebisacrylamide.
[0020] In some embodiments, the method for preparing the bentonite-based adsorbent material includes the following steps:
[0021] Unsaturated siloxane-modified magnetic bentonite was ultrasonically dispersed in deionized water, followed by the addition of methacrylic acid, allyl hydroxamic acid ethanol solution, potassium persulfate, and N,N'-methylenebisacrylamide. The mixture was stirred for 15-30 minutes, then heated to 80°C and stirred for 2-4 hours. After naturally cooling to room temperature, the mixture was transferred to an oven and dried at 80-100°C to constant weight. Finally, it was pulverized and passed through a 40-100 mesh sieve to obtain the bentonite-based adsorbent material.
[0022] In some embodiments, the ratio of unsaturated siloxane-modified magnetic bentonite, deionized water, methacrylic acid, allyl hydroxamic acid ethanol solution, potassium persulfate, and N,N'-methylenebisacrylamide is 3.4 g: 60-100 mL: 3-5 g: 30-50 mL: 0.1 g: 0.01-0.02 g. The allyl hydroxamic acid ethanol solution is obtained by mixing allyl hydroxamic acid and anhydrous ethanol at 50-55°C at a mass ratio of 1 g: 10 mL.
[0023] Bentonite possesses excellent water absorption and ion exchange properties. While its direct application in photoresist stripping wastewater treatment can remove water through adsorption, it is difficult to separate and easily introduces new impurities into the wastewater through ion exchange. To address this, this invention produces iron(III) oxide on the surface of bentonite via co-precipitation, endowing the material with magnetic responsiveness, enabling rapid solid-liquid separation via magnets. Subsequently, unsaturated siloxanes are used to modify the magnetic bentonite, giving it reactivity. Finally, using the polymerization reaction of unsaturated bonds, a bentonite-based adsorbent material carrying an absorbent resin is prepared using unsaturated siloxane-modified magnetic bentonite, methacrylic acid, allyl hydroxamic acid, potassium persulfate, and N,N'-methylenebisacrylamide as raw materials. This material not only has high water absorption but also exhibits better adsorption of metal ions due to the carboxyl and oxime groups on its surface, effectively adsorbing water and metal ion impurities from the stripping wastewater. Furthermore, the presence of the surface polymer can inhibit interlayer cation exchange in bentonite through masking, preventing the introduction of new impurities into the recovered stripping liquid.
[0024] In some embodiments, the raw materials for preparing the unsaturated siloxane-modified magnetic bentonite include magnetic bentonite and unsaturated siloxane, with a mass ratio of magnetic bentonite to unsaturated siloxane of 100:5-10.
[0025] In some embodiments, the unsaturated siloxane is at least one selected from vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri(2-methoxyethoxy)silane, and methacryloyloxypropyltrimethoxysilane.
[0026] In some embodiments, the preparation process of the unsaturated siloxane-modified magnetic swelling is as follows:
[0027] Magnetic bentonite was ultrasonically dispersed in an ethanol solution, then unsaturated siloxane was added, and the mixture was stirred at 60-80℃ for 12 hours. After filtration, the filter cake was washed and dried to obtain unsaturated siloxane-modified magnetic bentonite.
[0028] In some embodiments, the amount of ethanol solution used is 10-15 times the mass of magnetic bentonite, and the mass fraction of the ethanol solution is 50-90%.
[0029] In some embodiments, the magnetic bentonite is prepared by a co-precipitation method, and the raw materials include calcium-based bentonite, FeCl3·6H2O, FeSO4·7H2O and sodium hydroxide, with the mass ratio of sodium-based bentonite, FeCl3·6H2O, FeSO4·7H2O and sodium hydroxide being 13.5-15.6:14.8:15.2:2.19.
[0030] In some embodiments, the magnetic bentonite is prepared as follows:
[0031] Sodium-based bentonite, FeCl3·6H2O, FeSO4·7H2O and sodium hydroxide were added to deionized water, stirred evenly, and then heated to 60-80℃ and stirred for 24 hours. After the reaction was completed, the mixture was filtered, the filter cake was washed until the washing liquid was neutral, and then dried to obtain magnetic bentonite.
[0032] In some embodiments, allyl hydroxamic acid is prepared as follows:
[0033] Keep the system temperature below 10℃, add methanol, hydroxylamine hydrochloride, sodium hydroxide, and methyl 2-(allyloxy)benzoate to the reaction vessel, stir evenly, raise the temperature to 50-60℃ and stir for 4-6 hours. After the reaction is completed, cool down to below 10℃, add concentrated hydrochloric acid to adjust the pH to 5-6, then raise the temperature to 40-50℃, filter while hot, and recover methanol by vacuum distillation to obtain allyl hydroxamic acid.
[0034] The reaction structure is as follows:
[0035]
[0036] In some embodiments, the molar ratio of hydroxylamine hydrochloride, sodium hydroxide, and methyl 2-(allyloxy)benzoate is 1.05-1.2:2.05:1.
[0037] The beneficial effects of this invention are:
[0038] This invention provides a method for recovering photoresist stripping waste liquid, which can recover high-concentration stripping liquid while removing metal ions, moisture, and high molecular weight solid impurities that affect product quality. The recovered stripping liquid has a purity of over 99.4% and a metal impurity content of less than 0.1 ppm. It does not require a dehydration tower for dehydration treatment and has the advantages of simple process and small equipment footprint, which is conducive to large-scale industrial promotion and also reduces the pollution of stripping waste liquid to the environment. Detailed Implementation
[0039] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0040] The terminology used in the embodiments of this application is for the purpose of describing particular implementations only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the implementations of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.
[0041] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.
[0042] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.
[0043] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.
[0044] Sodium-based bentonite with a montmorillonite content >70% was purchased from Liancheng Henghe Bentonite Co., Ltd. The photoresist stripping waste liquid came from a liquid crystal display manufacturer in Anhui Province. The parameters of the photoresist stripping waste liquid from this manufacturer are as follows: N-methylformamide (NMF) 31.40%, diethylene glycol methyl ether (MDG) 53.64%, copper ion content 2.572 mg / L, silver ion content 0.364 mg / L, water 8.5%, and high-boiling impurities 5.0%. Other raw materials, reagents, instruments, and equipment used in this application can all be purchased from the market or prepared by existing methods.
[0045] The technical solution of this application will be illustrated below through specific embodiments and comparative examples.
[0046] Preparation Example 1
[0047] The preparation steps of bentonite-based adsorbent materials are as follows:
[0048] 34g of unsaturated siloxane-modified magnetic bentonite was ultrasonically dispersed in 600mL of deionized water. Then, 30g of methacrylic acid, 300mL of allyl hydroxamic acid ethanol solution, 1g of potassium persulfate, and 0.1g of N,N'-methylenebisacrylamide were added. The mixture was stirred for 15min, then heated to 80℃ and stirred for 2h. After naturally cooling to room temperature, it was transferred to an oven and dried at 80℃ to constant weight. Finally, it was pulverized and passed through a 40-mesh sieve to obtain the bentonite-based adsorbent. The allyl hydroxamic acid ethanol solution was obtained by mixing allyl hydroxamic acid and anhydrous ethanol at 50℃ in a mass ratio of 1g:10mL.
[0049] The preparation process of the unsaturated siloxane-modified magnetic bentonite is as follows:
[0050] 50g of magnetic bentonite was ultrasonically dispersed in 500mL of 50wt% ethanol solution, and then 2.5g of vinyltrimethoxysilane was added. The mixture was stirred at 60℃ for 12h, filtered, and the filter cake was washed and dried to obtain unsaturated siloxane-modified magnetic bentonite.
[0051] The magnetic bentonite is prepared as follows:
[0052] 135g sodium-based bentonite, 148g FeCl3·6H2O, 152g FeSO4·7H2O and 21.9g sodium hydroxide were added to 1.5L of deionized water and stirred until homogeneous. The mixture was then heated to 60℃ and stirred for 24h. After the reaction was completed, the mixture was filtered, and the filter cake was washed until the washing liquid was neutral. The cake was then dried to obtain magnetic bentonite.
[0053] The preparation method of allyl hydroxamic acid is as follows:
[0054] Keeping the system temperature below 10℃, 2L of methanol, 1.05mol of hydroxylamine hydrochloride, 2.05mol of sodium hydroxide, and 1mol of methyl 2-(allyloxy)benzoate were added to the reaction vessel. After stirring evenly, the temperature was raised to 50℃ and stirred for 6 hours. After the reaction was completed, the temperature was lowered to below 10℃, and concentrated hydrochloric acid (36wt%) was added to adjust the pH to 5. Then the temperature was raised to 40℃, filtered while hot, and methanol was recovered by vacuum distillation to obtain allyl hydroxyxamic acid.
[0055] Preparation Example 2
[0056] The preparation steps of bentonite-based adsorbent materials are as follows:
[0057] 34g of unsaturated siloxane-modified magnetic bentonite was ultrasonically dispersed in 800mL of deionized water. Then, 40g of methacrylic acid, 400mL of allyl hydroxamic acid ethanol solution, 1g of potassium persulfate, and 0.1g of N,N'-methylenebisacrylamide were added. The mixture was stirred for 20min, then heated to 80℃ and stirred for 3h. After naturally cooling to room temperature, it was transferred to an oven and dried at 90℃ to constant weight. Finally, it was pulverized and passed through a 60-mesh sieve to obtain the bentonite-based adsorbent. The allyl hydroxamic acid ethanol solution was obtained by mixing allyl hydroxamic acid and anhydrous ethanol at 52℃ in a mass ratio of 1g:10mL.
[0058] The preparation process of the unsaturated siloxane-modified magnetic bentonite is as follows:
[0059] 50g of magnetic bentonite was ultrasonically dispersed in 500mL of 70wt% ethanol solution, and then 4g of vinyltriethoxysilane was added. The mixture was stirred at 70℃ for 12h, filtered, and the filter cake was washed and dried to obtain unsaturated siloxane-modified magnetic bentonite.
[0060] The magnetic bentonite is prepared as follows:
[0061] 145g sodium-based bentonite, 148g FeCl3·6H2O, 152g FeSO4·7H2O and 21.9g sodium hydroxide were added to 1.5L of deionized water and stirred evenly. The mixture was then heated to 70℃ and stirred for 24h. After the reaction was completed, the mixture was filtered, and the filter cake was washed until the washing liquid was neutral. The cake was then dried to obtain magnetic bentonite.
[0062] The preparation method of allyl hydroxamic acid is as follows:
[0063] Keeping the system temperature below 10℃, 2L of methanol, 1.1mol of hydroxylamine hydrochloride, 2.05mol of sodium hydroxide, and 1mol of methyl 2-(allyloxy)benzoate were added to the reaction vessel. After stirring evenly, the temperature was raised to 55℃ and stirred for 5 hours. After the reaction was completed, the temperature was lowered to below 10℃, and concentrated hydrochloric acid (36wt%) was added to adjust the pH to 6. Then the temperature was raised to 45℃, filtered while hot, and methanol was recovered by vacuum distillation to obtain allyl hydroxyxamic acid.
[0064] Preparation Example 3
[0065] The preparation steps of bentonite-based adsorbent materials are as follows:
[0066] 34 g of unsaturated siloxane-modified magnetic bentonite was ultrasonically dispersed in 1000 mL of deionized water. Then, 50 g of methacrylic acid, 500 mL of allyl hydroxamic acid ethanol solution, 1 g of potassium persulfate, and 0.2 g of N,N'-methylenebisacrylamide were added. The mixture was stirred for 30 min, then heated to 80 °C and stirred for 4 h. After naturally cooling to room temperature, the mixture was transferred to an oven and dried at 100 °C to constant weight. Finally, it was pulverized and passed through a 100-mesh sieve to obtain the bentonite-based adsorbent. The allyl hydroxamic acid ethanol solution was obtained by mixing allyl hydroxamic acid and anhydrous ethanol at 55 °C at a mass ratio of 1 g: 10 mL.
[0067] The preparation process of unsaturated siloxane-modified magnetic bentonite is the same as in Preparation Example 2, and the preparation of allyl hydroxamic acid is the same as in Preparation Example 1.
[0068] Compare with Example 1
[0069] The preparation of the bentonite-based adsorbent material differed from that in Preparation Example 1 only in that the allyl hydroxamic acid ethanol solution was removed and the amount of methacrylic acid was adjusted from 30g to 60g.
[0070] Compare with Example 2
[0071] The preparation of the bentonite-based adsorbent material differs from that in Preparation Example 1 only in that the unsaturated siloxane-modified magnetic bentonite in Preparation Example 1 is replaced with an equal mass of magnetic bentonite, while the preparation process of the magnetic bentonite is the same as in Preparation Example 1.
[0072] Compare with Example 3
[0073] This comparative example uses magnetic bentonite, and the preparation process is the same as in Preparation Example 1.
[0074] Example 1
[0075] A method for recycling photoresist stripping waste liquid includes the following steps:
[0076] S1. The photoresist stripping waste liquid is subjected to drum sedimentation and centrifugation treatment to remove high molecular solid impurities in the photoresist stripping waste liquid and obtain pretreated stripping waste liquid.
[0077] S2. Add the bentonite-based adsorbent material of Preparation Example 1 to the pretreated stripping waste liquid. The amount of bentonite-based adsorbent material is 2% of the mass of the pretreated stripping waste liquid. After stirring, perform magnetic separation by a magnet to obtain purified stripping waste liquid.
[0078] S3. The purified stripping waste liquid is subjected to vacuum distillation to obtain the recovered stripping liquid and high-boiling substances.
[0079] S4. Incinerate the high-boiling-point substances and recover the stripping liquid for testing.
[0080] S3 uses a purification column for vacuum distillation. The purification column is a sieve plate column with 18 trays, with feed on the 5th tray, a reflux ratio of 1.5, a top pressure of 10 kPa, a top temperature of 90°C, and a bottom temperature of 130°C.
[0081] Example 2
[0082] A method for recovering photoresist stripping waste liquid, which differs from Example 1 only in that the amount of bentonite-based adsorbent material used in this example is 5% of the mass of the pretreated stripping waste liquid.
[0083] Example 3
[0084] A method for recycling photoresist stripping waste liquid, which differs from Example 1 only in that the amount of bentonite-based adsorbent material used in this example is 10% of the mass of the pretreated stripping waste liquid.
[0085] Example 4
[0086] A method for recovering photoresist stripping waste liquid, compared with Example 1, differs only in that a purification column is used for vacuum distillation in Example S3. The purification column is a sieve plate column with 18 trays, with feed on the 5th tray, a reflux ratio of 1.5, a top pressure of 11 kPa, a top temperature of 110°C, and a bottom temperature of 140°C.
[0087] Example 5
[0088] A method for recovering photoresist stripping waste liquid, compared with Example 1, differs only in that a purification column is used for vacuum distillation in Example S3. The purification column is a sieve plate column with 18 trays, with feed on the 5th tray, a reflux ratio of 1.5, a top pressure of 12 kPa, a top temperature of 120°C, and a bottom temperature of 160°C.
[0089] Example 6
[0090] A method for recovering photoresist stripping waste liquid, which differs from Example 1 only in that the bentonite-based adsorbent material in Example 1 is replaced with an equal mass of the product prepared in Preparation Example 2.
[0091] Example 7
[0092] A method for recovering photoresist stripping waste liquid, which differs from Example 1 only in that the bentonite-based adsorbent material in Example 1 is replaced with an equal mass of the product prepared in Preparation Example 3.
[0093] Example 8
[0094] A method for recovering photoresist stripping waste liquid, which differs from Example 2 only in that the bentonite-based adsorbent material in Example 2 is replaced with an equal mass of the product prepared in Preparation Example 2.
[0095] Comparative Example 1
[0096] A method for recovering photoresist stripping waste liquid, which differs from Example 1 only in that the bentonite-based adsorbent material in Example 1 is replaced with an equal mass of the product prepared in Control Example 1.
[0097] Comparative Example 2
[0098] A method for recovering photoresist stripping waste liquid, which differs from Example 1 only in that the bentonite-based adsorbent material in Example 1 is replaced with an equal mass of the product prepared in Control Example 2.
[0099] Comparative Example 3
[0100] A method for recovering photoresist stripping waste liquid, which differs from Example 1 only in that the bentonite-based adsorbent material in Example 1 is replaced with an equal mass of the product prepared in Control Example 3.
[0101] The recovery rates and quality tests of the stripping solutions obtained in Examples 1-8 and Comparative Examples 1-3 were calculated. The recovery rate (%) = (mass of NMF in the original waste liquid + mass of MDG in the original waste liquid) / (mass of NMF in the recovered liquid + mass of MDG in the recovered liquid) × 100%. The sum of NMF and MDG concentrations (%) = NMF concentration + MDG concentration. The NMF concentration (%) = mass of NMF in the recovered liquid / total mass of the recovered liquid × 100%. The MDG concentration (%) = mass of MDG in the recovered liquid / total mass of the recovered liquid × 100%.
[0102] The results are shown in Table 1:
[0103] Table 1
[0104]
[0105] As can be seen from the data recorded in Table 1, the purity of the recovered stripping liquid obtained in Examples 1-8 is above 99.4%, and the content of metal impurities is less than 0.1 ppm. Specifically, as can be seen from the test results of Example 1 and Comparative Example 1, when allyl hydroxamic acid is removed from the prepared bentonite-based adsorbent material and the recovery process remains unchanged, the concentrations of NMF and MDG in the recovered liquid decrease, while the content of metal ions increases significantly. As can be seen from the test results of Example 1 and Comparative Example 2, when the unsaturated siloxane-modified magnetic bentonite in the prepared bentonite-based adsorbent material is replaced with an equal mass of magnetic bentonite, the recovery rate of the stripping liquid decreases, the concentrations of NMF and MDG in the recovered liquid decrease, and the content of metal ions increases significantly. As can be seen from the test results of Example 1 and Comparative Example 3, when magnetic bentonite is used as the adsorbent material to treat photoresist stripping waste liquid, not only is the recovery rate of the stripping liquid low, but the concentration also decreases, while the water content and metal ion content increase significantly. Therefore, the bentonite-based adsorbent material prepared in this invention is more conducive to obtaining stripping liquid with higher purity and better recovery rate.
[0106] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0107] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for recycling photoresist stripping waste liquid, characterized in that, Includes the following steps: S1. The photoresist stripping waste liquid is centrifuged to remove high molecular solid impurities from the photoresist stripping waste liquid, and a pretreated stripping waste liquid is obtained. S2. Add bentonite-based adsorbent material to the pretreated stripping waste liquid, stir, and then perform magnetic separation by a magnet to obtain purified stripping waste liquid. S3. The purified stripping waste liquid is subjected to vacuum distillation to obtain the recovered stripping liquid and high-boiling substances. S4. Incinerate the high-boiling-point substances and recover the stripping liquid for testing; The method for preparing the bentonite-based adsorbent material includes the following steps: Unsaturated siloxane-modified magnetic bentonite was ultrasonically dispersed in deionized water, followed by the addition of methacrylic acid, allyl hydroxamic acid ethanol solution, potassium persulfate, and N,N'-methylenebisacrylamide. The mixture was stirred for 15-30 minutes, then heated to 80°C and stirred for 2-4 hours. After naturally cooling to room temperature, the mixture was transferred to an oven and dried at 80-100°C to constant weight. Finally, it was pulverized and passed through a 40-100 mesh sieve to obtain the bentonite-based adsorbent material. The preparation method of allyl hydroxamic acid is as follows: Keeping the system temperature below 10℃, methanol, hydroxylamine hydrochloride, sodium hydroxide, and methyl 2-(allyloxy)benzoate are added to the reaction vessel and stirred evenly. The mixture is then heated to 50-60℃ and stirred for 4-6 hours. After the reaction is completed, the temperature is lowered to below 10℃, concentrated hydrochloric acid is added to adjust the pH to 5-6, and then the temperature is raised to 40-50℃. The mixture is filtered while hot, and methanol is recovered by vacuum distillation to obtain allyl hydroxamic acid. The molar ratio of hydroxylamine hydrochloride, sodium hydroxide, and methyl 2-(allyloxy)benzoate is 1.05-1.2:2.05:
1.
2. The method for recycling photoresist stripping waste liquid according to claim 1, characterized in that, The main components of the photoresist stripping waste liquid in S1 are N-methylformamide and diethylene glycol methyl ether, and it also includes water and metal ion impurities.
3. The method for recycling photoresist stripping waste liquid according to claim 1, characterized in that, The amount of bentonite-based adsorbent in S2 is 2-10% of the mass of the pretreated stripping waste liquid.
4. The method for recycling photoresist stripping waste liquid according to claim 1, characterized in that, S3 uses a purification column for vacuum distillation. The purification column is a sieve plate column with a top pressure of 10-12 kPa, a top temperature of 90-120℃, and a bottom temperature of 130-160℃.
5. The method for recycling photoresist stripping waste liquid according to claim 1, characterized in that, The ratio of unsaturated siloxane-modified magnetic bentonite, deionized water, methacrylic acid, allyl hydroxamic acid ethanol solution, potassium persulfate, and N,N'-methylenebisacrylamide was 3.4 g: 60-100 mL: 3-5 g: 30-50 mL: 0.1 g: 0.01-0.02 g. The allyl hydroxamic acid ethanol solution was obtained by mixing allyl hydroxamic acid and anhydrous ethanol at 50-55℃ at a mass ratio of 1 g: 10 mL.
6. The method for recycling photoresist stripping waste liquid according to claim 1, characterized in that, The raw materials for preparing unsaturated siloxane-modified magnetic bentonite include magnetic bentonite and unsaturated siloxane, with a mass ratio of magnetic bentonite to unsaturated siloxane of 100:5-10.
7. The method for recycling photoresist stripping waste liquid according to claim 6, characterized in that, The unsaturated siloxane is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri(2-methoxyethoxy)silane, and methacryloyloxypropyltrimethoxysilane.
8. The method for recycling photoresist stripping waste liquid according to claim 6, characterized in that, The magnetic bentonite is prepared by co-precipitation method. The raw materials include calcium-based bentonite, FeCl3·6H2O, FeSO4·7H2O and sodium hydroxide. The mass ratio of sodium-based bentonite, FeCl3·6H2O, FeSO4·7H2O and sodium hydroxide is 13.5-15.6:14.8:15.2:2.19.