Purification method of semiconductor grade propylene glycol methyl ether acetate

Abstract

The invention discloses a preparation method of semiconductor grade propylene glycol methyl ether acetate, which comprises the following steps: taking industrial grade propylene glycol methyl ether acetate as a raw material; comprising the following steps in sequence: molecular sieve dehydration, multi-stage rectification purification, particle pretreatment, molecular distillation, cation pretreatment, anion exchange resin treatment, cation exchange resin treatment and final nanofiltration treatment, so as to obtain particles (gt) of which the weight content is greater than or equal to 99.99%, the chromaticity APHA is less than or equal to 10, the moisture is less than or equal to 105 ppm, the acidity is less than or equal to 100 ppm, each single metal ion is less than 0.1 ppb, each single non-metal ion is less than 100 ppb; 0.2 [mu] m > lt; the high-purity propylene glycol methyl ether acetate with the purity of 5 pcs / mL meets the SEMI-C12 standard, and the process is continuous, relatively low in cost and easy to implement.

Description

[0001] This application is a divisional application of the Chinese patent application with the invention name “A method for preparing semiconductor-grade propylene glycol methyl ether acetate”, application number 2022103188021, and application date March 29, 2022. Technical Field

[0002] The invention relates to the technical field of preparation of high-purity electronic chemicals, and in particular to a method for preparing semiconductor-grade propylene glycol methyl ether acetate. Background Art

[0003] Propylene glycol methyl ether acetate (PGMEA) is a high-grade solvent, which has both ether bonds and carbonyl groups in its molecules. The carbonyl groups form an ester structure and contain alkyl groups. In the same molecule, there are both non-polar parts and polar parts. The functional groups of these two parts not only restrict and repel each other, but also play their own inherent roles. Therefore, it has a certain solubility for both non-polar substances and polar substances. Therefore, it is often used in semiconductor manufacturing processes such as liquid crystal displays and photoresists, for example, as a cleaning agent. Since the purity and cleanliness of chemicals will directly affect the yield, electrical properties and long-term reliability of semiconductors, these processes have extremely high requirements for the purity and cleanliness of chemicals, and with the continuous development of high-end photolithography processing technology, these chemicals are required to meet the SEMI-C12 standard requirements formulated by the International Semiconductor Equipment and Materials Organization. At present, some people have proposed the following route: using industrial-grade propylene glycol methyl ether acetate as raw material, first through distillation, molecular sieve dehydration, then through resin deacidification, cation and anion exchange resin to remove metal ions and non-metal ions, and finally ultrafiltration. However, this plan is result-oriented, that is, index requirements are proposed for each step, and then each step is repeated until the index is reached. The continuity is poor, the cost is too high, and it is difficult to be suitable for industrial application. Summary of the invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and to provide an improved method for purifying propylene glycol methyl ether acetate, which can continuously and at a relatively low cost obtain semiconductor-grade propylene glycol methyl ether acetate that meets the SEMI-C12 standard.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing semiconductor-grade propylene glycol methyl ether acetate, the preparation method uses industrial-grade propylene glycol methyl ether acetate as a raw material, and comprises the following steps performed in sequence:

[0006] (1) Dehydrating the raw materials using molecular sieves;

[0007] (2) processing the raw material after the treatment in step (1) in a first extractive distillation tower, a second extractive distillation tower and a third extractive distillation tower in sequence;

[0008] Wherein, the first extractive distillation tower produces propylene glycol methyl ether acetate from the bottom of the tower, the second extractive distillation tower produces propylene glycol methyl ether acetate from the side line, and the third extractive distillation tower produces propylene glycol methyl ether acetate from the bottom of the tower, and the first extractive distillation tower, the second extractive distillation tower, and the third extractive distillation tower each independently use one of butyl acetate, 1,2-propylene glycol, and isopropanol as an extractant, and they are different from each other;

[0009] (3) passing the raw material treated in step (2) through a filter element to remove particulate matter and dehydrating it again through a molecular distillation tower;

[0010] (4) removing metal ions from the raw material treated in step (3) through an organic silicone-modified polyacrylonitrile membrane;

[0011] (5) The raw material treated in step (4) is sequentially subjected to a gel styrene-based anion exchange resin for removing anions, a modified polytetrafluoroethylene membrane for removing cations, and a nanofiltration treatment for removing particulate matter to obtain purified propylene glycol methyl ether acetate.

[0012] In the present invention, when it is mentioned that a certain device is used to perform a certain treatment to obtain a certain effect, for example, it is mentioned that a molecular sieve is used to dehydrate a raw material, it means that its main function is to dehydrate the raw material, and does not mean that its function is limited to this.

[0013] According to some specific aspects of the present invention, in step (1), the molecular sieve uses a 3 angstrom or 4 angstrom aluminosilicate molecular sieve.

[0014] According to some preferred aspects of the present invention, in step (2), the fillers used in the first extractive distillation tower, the second extractive distillation tower, and the third extractive distillation tower are respectively carbon fiber reinforced polytetrafluoroethylene fillers, the number of plates is 20-30, the reflux ratio is 2-8, the tower top temperature is 75-110°C, the tower side line temperature is 95-155°C, and the tower bottom temperature is 115-190°C.

[0015] According to some preferred aspects of the present invention, when the extractant is butyl acetate, the tower top temperature is 95-110°C, the tower side line temperature is 110-135°C, and the tower bottom temperature is 130-150°C.

[0016] According to some preferred aspects of the present invention, when the extractant is 1,2-propylene glycol, the tower top temperature is 100-110°C, the tower side line temperature is 140-155°C, and the tower bottom temperature is 180-190°C.

[0017] According to some preferred aspects of the present invention, when the extractant is isopropanol, the tower top temperature is 75-88°C, the tower side line temperature is 95-106°C, and the tower bottom temperature is 115-125°C.

[0018] According to some preferred aspects of the present invention, when the extractant is butyl acetate, the reflux ratio is 2-4, the number of plates is 22-26, and the feed port is located at the 11th to 13th plates.

[0019] According to some preferred aspects of the present invention, when the extractant is 1,2-propylene glycol, the reflux ratio is 2-3, the number of plates is 20-22, and the feed port is located at the 10th-11th plate.

[0020] According to some preferred aspects of the present invention, when the extractant is isopropanol, the reflux ratio is 2-3, the number of plates is 23-25, and the feed port is located at the 13th to 15th plate.

[0021] According to some preferred aspects of the present invention, in step (2), the first extractive distillation tower and the second extractive distillation are carried out under reduced pressure, the extractant used in the second extractive distillation is 1,2-propylene glycol or butyl acetate, the extractant used in the third extractive distillation tower is isopropanol or butyl acetate, and the first extractive distillation tower uses one of butyl acetate, 1,2-propylene glycol and isopropanol as the extractant.

[0022] In the present invention, the first extractive distillation tower and the second extractive distillation tower respectively realize light removal and heavy removal, and the third extractive distillation tower realizes reforming distillation.

[0023] According to some preferred aspects of the present invention, in step (3), the filter element is arranged in the particle pretreatment tank, and a multi-stage filter element connected in series can be arranged, and the material of each stage of the filter element is nylon, and the pore size is 10-40 μm.

[0024] According to some preferred aspects of the present invention, in step (3), the process parameters of the molecular distillation tower are: pressure of 0.01-0.012 MPa, temperature of 140-150° C., and reflux ratio of 2-5.

[0025] According to some preferred aspects of the present invention, in step (4), the pressure of the raw material treated in step (3) passing through the organic silicone modified polyacrylonitrile membrane is controlled to be 1-5 MPa and the flow rate is controlled to be 80-500 L / h.

[0026] In some preferred embodiments of the present invention, the organosilicone-modified polyacrylonitrile membrane is selected from Evonik's PuraMemPerformance series.

[0027] According to some preferred aspects of the present invention, in step (5), the pressure of the material passing through the gel styrene-based anion exchange resin is controlled to be 0.1-0.5 MPa and the flow rate is 60-90 L / h.

[0028] In some preferred embodiments of the present invention, the gel styrene-based anion exchange resin is selected from DuPont Amberlite IRA402Cl, DuPont Amberlite IRA96RF, DuPont Amberlite FPA98Cl, Lanxess Lewatit1072, and the like.

[0029] According to some preferred aspects of the present invention, in step (5), the pressure of the material passing through the modified polytetrafluoroethylene membrane is controlled to be 0.1-0.5 MPa, and the flow rate is 60-90 L / h.

[0030] In some preferred embodiments of the present invention, the modified polytetrafluoroethylene membrane is selected from Purasol SN / SP series of Intec, Ionkleen SL series of Pall, and Nylonpolar Solvent Purifier of Cobite.

[0031] According to some preferred aspects of the present invention, in step (5), the nanofiltration treatment uses a hollow fiber nanofiltration membrane as a filter membrane, and the hollow fiber nanofiltration membrane is made of polytetrafluoroethylene and has a pore size of less than or equal to 0.04 μm.

[0032] In some embodiments of the present invention, the nanofiltration treatment may be carried out by connecting multiple stages of hollow fiber nanofiltration membranes in series.

[0033] In some embodiments of the present invention, the method for preparing semiconductor-grade propylene glycol methyl ether acetate can be carried out using the following production system:

[0034] The production system comprises a molecular sieve tank, a first extracting and rectifying tower, a second extracting and rectifying tower, a third extracting and rectifying tower, a particle pretreatment tank, a molecular distillation tower, a first cation exchange tank provided with an organic silicone modified polyacrylonitrile membrane, an anion exchange tank provided with a gel styrene-based anion exchange resin, a second cation exchange tank provided with a modified polytetrafluoroethylene membrane, and a nanofiltration treatment tank, which are connected in sequence.

[0035] In the present invention, after being treated by the purification method of the present invention, high-purity propylene glycol methyl ether acetate with a weight content of ≥99.99%, a color APHA ≤10, a moisture content of ≤105ppm, an acidity of ≤100ppm, each single metal ion <0.1ppb, each single non-metal ion <100ppb, and a particle size (>0.2μm) <5pcs / mL can be produced.

[0036] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0037] The present invention is based on the defects existing in the existing preparation process of high-purity propylene glycol methyl ether acetate, and innovatively combines multiple purification steps and arranges them in a specific order, so that each purification process can maximize its purification function while reducing the impurities that may be additionally introduced during the treatment process, and when they are inevitably introduced, they can still be removed with the help of existing purification processes without the need to add new equipment; in fact, the inventors of the present invention accidentally discovered during the study of the preparation process of high-purity propylene glycol methyl ether acetate that based on the characteristics of propylene glycol methyl ether acetate itself, new impurities will inevitably be introduced after molecular sieve dehydration. Although distillation purification followed by molecular sieve dehydration is beneficial to dehydration, it leads to a sharp increase in the content of metal cations and particulate matter, and it is difficult to effectively and maximally remove them by relying on existing ion exchange resins and filtration treatments. , not only does it cause a very high load on the subsequent ion exchange and filtration separation, which reduces the service life of these equipment to a certain extent, but also the treatment effect is not good. Based on this, the inventors of the present invention propose to pre-dehydrate the molecular sieve, first dehydrate the molecular sieve and then carry out multi-stage extraction distillation, respectively remove light, remove heavy and reforming distillation, and based on a large amount of practice, propose an extractant suitable for multi-stage distillation, and then pre-treat the preliminary separation of particulate matter, reduce the processing pressure of the subsequent filter element, give play to the precision advantage of subsequent nanofiltration treatment, and introduce molecular distillation method for dehydration again, and then combine the pretreatment of propylene glycol methyl ether acetate with organic silicone modified polyacrylonitrile membrane, thereby greatly reducing the pressure of subsequent cation removal, which can better achieve high cost performance, and the organic silicone modified polyacrylonitrile membrane is more suitable for the treatment of propylene glycol methyl ether acetate than other membranes, and has a longer service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a process flow chart of the method for preparing semiconductor-grade propylene glycol methyl ether acetate in an embodiment of the present invention;

[0039] Among them, 1. molecular sieve tank; 2. first extraction distillation tower; 3. second extraction distillation tower; 4. third extraction distillation tower; 5. particle pretreatment tank; 6. molecular distillation tower; 7. first cation exchange tank; 8. anion exchange tank; 9. second cation exchange tank; 10. nanofiltration treatment tank. DETAILED DESCRIPTION

[0040] The above scheme is further described below in conjunction with specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions adopted in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0041] Unless otherwise specified in the following examples, all raw materials can be purchased from commercial sources or prepared by conventional methods in the art. 3 angstrom molecular sieve was purchased from Langfang Naco New Materials, model 3A molecular sieve; 4 angstrom molecular sieve was purchased from Shanghai Youxin Molecular Sieve Company, model 4A molecular sieve;

[0042] The test results of industrial grade propylene glycol methyl ether acetate are shown in Table 1 below:

[0043] Table 1

[0044]

[0045]

[0046] Example 1

[0047] like Figure 1The process route shown in the example provides a method for preparing semiconductor-grade propylene glycol methyl ether acetate, which comprises: passing industrial-grade propylene glycol methyl ether acetate with a weight content of 99.0% through a molecular sieve tank 1 (the molecular sieve used is a 3 angstrom molecular sieve) at a flow rate of 120 L / h, and removing moisture through the molecular sieve; the dehydrated propylene glycol methyl ether acetate enters a first extractive distillation tower 2 (to remove light components), and its filler model is carbon fiber reinforced polytetrafluoroethylene filler (purchased from Haiyan New Century Petrochemical Equipment Co., Ltd., C-PTFE04), and the reduced pressure operation (0.08-0.1 MPa), and the extractant is vinegar Butyl ester, reflux ratio is 3, number of plates is 24, feed port is at the 12th plate, tower bottom temperature is 140±0.5℃; there is a side line in the middle of the tower, the temperature is controlled at 126℃±2.0℃; the tower top temperature is 106±3.0℃; the tower bottom liquid enters the second extractive distillation tower 3 to remove the heavy components, the extractant is 1,2-propylene glycol, the operating pressure is 0.08MPa, the reflux ratio is 2, the number of plates is 20, the feed port is at the 10th plate, the tower top temperature is 105±1℃, the tower bottom temperature is 186±1℃, the tower side line temperature is 146±2.0℃, and the side line produces high-purity propylene glycol Methyl ether acetate; the propylene glycol methyl ether acetate after extraction enters the third extractive distillation tower 4 for reforming distillation, the reflux ratio of the distillation tower is 2, the number of plates is 24, the feed port is at the 14th plate, the extractant is isopropanol, the bottom temperature is 120±1°C, the side line temperature is 100±2°C, the top temperature is 80±3°C, the flow rate is controlled at 300L / h, and the high-purity propylene glycol methyl ether acetate extracted from the bottom of the tower enters the particle pretreatment tank (nylon filter element, secondary filter element, pore sizes are 10 and 40μm respectively) 5, the flow rate is controlled at 100L / h, and the propylene glycol methyl ether acetate after particle pretreatment enters the molecular distillation The propylene glycol methyl ether acetate is treated in a distillation tower 6 at a pressure of 0.01-0.012 MPa, a temperature of 144-146°C, and a reflux ratio of 3; the obtained propylene glycol methyl ether acetate enters a first cation exchange tank (equipped with an organic silicone modified polyacrylonitrile membrane, the organic silicone modified polyacrylonitrile membrane is specifically used for PuraMemperformance of Evonik) 7, at a pressure of 4 MPa and a flow rate of 100 L / h; the propylene glycol methyl ether acetate treated with the organic silicone modified polyacrylonitrile membrane enters an anion exchange tank (equipped with a gel styrene-based anion exchange resin, the resin is DuPont Amberlite IRA402C) 8, and the flow rate is controlled to be 90 L / h; the propylene glycol methyl ether acetate treated with the anion exchange resin enters a second cation exchange tank 9 (equipped with a modified polytetrafluoroethylene membrane, the membrane is Pall Ionkleen SLABDG1UPW), at a flow rate of 70 L / h and a pressure of 0.2MPa, the propylene glycol methyl ether acetate treated by the cation exchange filter element enters the nanofiltration treatment tank 10 (the filter element adopts a hollow fiber nanofiltration membrane made of polytetrafluoroethylene, and the treatment accuracy is carried out in a step-by-step order, using 40, 10, 5, 3, 2nm five-stage filtration) for treatment to obtain the purified propylene glycol methyl ether acetate. .

[0048] Comparative Example 1

[0049] The method is basically the same as Example 1, except that the operation of removing moisture through the molecular sieve is transferred to after the third extractive distillation tower and before the particle pretreatment tank treatment.

[0050] Example 2

[0051] like Figure 1The process route shown in this example provides a method for preparing semiconductor-grade propylene glycol methyl ether acetate, which comprises: passing industrial-grade propylene glycol methyl ether acetate with a weight content of 99.0% through a molecular sieve tank at a flow rate of 120L / h, and the molecular sieve adopts a 4-angstrom molecular sieve to remove moisture through the molecular sieve; the dehydrated propylene glycol methyl ether acetate enters a first extractive distillation tower 2 (to remove light components), and its filler model is carbon fiber tetrafluoro filler (its source is the same as in Example 1), and a reduced pressure operation (0.08-0.1MPa ), the extractant is isopropanol, the reflux ratio is 2, the number of plates is 24, the feed port is at the 14th plate, the tower bottom temperature is 120±1.0℃; there is a side line in the middle of the tower, and the temperature is controlled at 100℃±2.0℃; the tower top temperature is 80±3.0℃; the tower bottom liquid enters the second extractive distillation tower 3 to remove the heavy components, the extractant is 1,2-propylene glycol, the operating pressure is 0.08MPa, the reflux ratio is 2, the number of plates is 20, the feed port is at the 10th plate, and the tower top temperature is 105±1℃, The tower bottom temperature is 186±1°C, the tower side line temperature is 146±2.0°C, and high-purity propylene glycol methyl ether acetate is produced from the side line; the produced propylene glycol methyl ether acetate enters the third extractive distillation tower 4 for reforming and distillation, the reflux ratio of the distillation tower is 2, the extractant is butyl acetate, the number of plates is 22, the feed port is at the 12th plate, the tower bottom temperature is 140±1°C, the side line temperature is 120±2°C, the tower top temperature is 100±3°C, the flow rate is controlled to be 100L / h, and the high-purity propylene glycol methyl ether produced from the bottom of the tower is 100L / h. The acetate enters the particle pretreatment tank 5 (nylon filter element, secondary filter element, pore sizes of 10 and 40 μm respectively), and the flow rate is controlled at 100 L / h. The propylene glycol methyl ether acetate after particle pretreatment enters the molecular distillation tower 6 for treatment, with a pressure of 0.1-0.12 MPa, a temperature of 144-146° C., and a reflux ratio of 4; the obtained propylene glycol methyl ether acetate enters the first cation exchange tank (with an organic silicone modified polyacrylonitrile membrane, the organic silicone modified polyacrylonitrile membrane specifically used is Evonik PuraMem performance) 7, the pressure is 4MPa, the flow rate is 90L / h, the treated propylene glycol methyl ether acetate enters the anion exchange tank (equipped with a gel styrene-based anion exchange resin, the resin uses DuPont Amberlite IRA96RF) 8, the flow rate is controlled to be 80L / h, the propylene glycol methyl ether acetate treated with the anion exchange resin enters the second cation exchange tank 9 (equipped with a modified polytetrafluoroethylene membrane, the membrane uses Yinggete's PurasolSN / SP filter element), the flow rate is 70L / h, the pressure is 0.2MPa, the propylene glycol methyl ether acetate treated with the cation exchange filter element enters the nanofiltration treatment tank 10 (the filter element uses a hollow fiber nanofiltration membrane made of polytetrafluoroethylene, the processing accuracy is carried out in a step-by-step increasing order, and 40, 10, 5, 3, 2nm five-stage filtration is used) to obtain the purified propylene glycol methyl ether acetate.

[0052] Example 3

[0053] like Figure 1The process route shown in the example provides a method for preparing semiconductor-grade propylene glycol methyl ether acetate, which comprises: passing industrial-grade propylene glycol methyl ether acetate with a weight content of 99.0% through a molecular sieve tank 1 at a flow rate of 120 L / h, wherein the molecular sieve is a 3 angstrom molecular sieve, and removing moisture through the molecular sieve; the dehydrated propylene glycol methyl ether acetate enters a first extractive distillation tower 2, wherein the filler model is a carbon fiber reinforced polytetrafluoroethylene filler (its source is the same as in Example 1), and a reduced pressure operation (0.08-0.1 MPa) is performed. , the extractant is 1,2-propylene glycol, the reflux ratio is 2, the number of plates is 20, the feed port is at the 10th plate, the bottom temperature is 186±1.0℃; there is a side line in the middle of the tower, the temperature is controlled at 146℃±2.0℃; the top temperature is 105±3.0℃; the bottom liquid enters the second extractive distillation tower 3, the extractant is butyl acetate, the operating pressure is 0.08MPa, the reflux ratio is 3, the number of plates is 22, the feed port is at the 12th plate, the top temperature is 106±3℃, and the bottom temperature is The tower bottom temperature is 120±1℃, the side line temperature is 100±2℃, the tower top temperature is 80±3℃, the control flow rate is 100L / h, and the high-purity propylene glycol methyl ether acetate is extracted from the tower bottom. The ester enters the particle pretreatment tank (nylon filter element, secondary filter element, pore sizes of 10 and 40 μm respectively) 5, and the flow rate is controlled to be 90 L / h. The propylene glycol methyl ether acetate after particle pretreatment enters the molecular distillation tower 6, with a pressure of 0.1-0.12 MPa, a temperature of 144-146°C, and a reflux ratio of 4; the obtained propylene glycol methyl ether acetate enters the first cation exchange tank (with an organic silicone modified polyacrylonitrile membrane, the organic silicone modified polyacrylonitrile membrane is specifically Evonik PureMem performance)7, the pressure is 4MPa, the flow rate is 80L / h, the treated propylene glycol methyl ether acetate enters the anion exchange tank (equipped with a gel styrene-based anion exchange resin, the resin uses DuPont Amberlite FPA98Cl)8, the flow rate is controlled to be 70L / h, the propylene glycol methyl ether acetate treated with the anion exchange resin enters the second cation exchange tank 9 (equipped with a modified polytetrafluoroethylene membrane, the membrane uses Pall Ionkleen SL ABDG1UPW, the flow rate is 70L / h, the pressure is 0.2MPa, the propylene glycol methyl ether acetate treated with the cation exchange filter element enters the nanofiltration treatment tank 10 (the filter element uses a hollow fiber nanofiltration membrane made of polytetrafluoroethylene, the processing accuracy is carried out in a step-by-step increasing order, and a five-stage filtration of 40, 10, 5, 3, and 2nm is used to obtain the purified propylene glycol methyl ether acetate.

[0054] Performance Testing

[0055] Table 2 below shows the test results of propylene glycol methyl ether acetate obtained in Examples 1-3 and Comparative Example 1.

[0056] Among them, the product mass content is analyzed by gas chromatography, the water weight content is analyzed by Karl Fischer moisture meter, the anion is analyzed by liquid ion chromatography (IC), and the metal ion weight content is analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The particles are tested by laser particle tester, the color is tested by colorimetry, and the acidity is tested by titration.

[0057] Table 2

[0058]

[0059]

[0060] It can be seen from the above table that the propylene glycol methyl ether acetate purified by the method of the present invention meets the SEMI-C12 standard, while in Comparative Example 1, after replacing the operating steps of distillation and molecular sieve dehydration, the content of some cations is difficult to reduce and does not meet the SEMI-C12 standard.

[0061] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0062] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A method for purifying semiconductor-grade propylene glycol methyl ether acetate, the method using industrial-grade propylene glycol methyl ether acetate as raw material, characterized in that: The purification method consists of the following steps: (1) Dehydrating the raw materials using molecular sieves; (2) processing the raw material after the treatment in step (1) in a first extractive distillation tower, a second extractive distillation tower and a third extractive distillation tower in sequence; Wherein, the first extractive distillation tower produces propylene glycol methyl ether acetate from the bottom of the tower, the second extractive distillation tower produces propylene glycol methyl ether acetate from the side line, and the third extractive distillation tower produces propylene glycol methyl ether acetate from the bottom of the tower, and the first extractive distillation tower, the second extractive distillation tower, and the third extractive distillation tower each independently use one of butyl acetate, 1,2-propylene glycol, and isopropanol as an extractant, and they are different from each other; (3) passing the raw material treated in step (2) through a filter element to remove particulate matter and dehydrating it again through a molecular distillation tower; (4) removing metal ions from the raw material treated in step (3) through an organic silicone-modified polyacrylonitrile membrane; (5) The raw material treated in step (4) is sequentially subjected to a gel styrene-based anion exchange resin for removing anions, a modified polytetrafluoroethylene membrane for removing cations, and a nanofiltration treatment for removing particulate matter to obtain purified propylene glycol methyl ether acetate.

2. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to claim 1, characterized in that: In step (1), the molecular sieve uses a 3 angstrom or 4 angstrom aluminosilicate molecular sieve.

3. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to claim 1, characterized in that: In step (2), the fillers used in the first extractive distillation tower, the second extractive distillation tower, and the third extractive distillation tower are respectively carbon fiber reinforced polytetrafluoroethylene fillers, the number of plates is 20-30, the reflux ratio is 2-8, the tower top temperature is 75-110°C, the tower side line temperature is 95-155°C, and the tower bottom temperature is 115-190°C.

4. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to claim 3, characterized in that: When the extractant is butyl acetate, the tower top temperature is 95-110°C, the tower side line temperature is 110-135°C, and the tower bottom temperature is 130-150°C; When the extractant is 1,2-propylene glycol, the tower top temperature is 100-110°C, the tower side line temperature is 140-155°C, and the tower bottom temperature is 180-190°C; When the extractant is isopropanol, the tower top temperature is 75-88°C, the tower side line temperature is 95-106°C, and the tower bottom temperature is 115-125°C.

5. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to claim 3, characterized in that: When the extractant is butyl acetate, the reflux ratio is 2-4, the number of plates is 22-26, and the feed port is located at the 11th to 13th plate; When the extractant is 1,2-propylene glycol, the reflux ratio is 2-3, the number of plates is 20-22, and the feed port is located at the 10th-11th plate; When the extractant is isopropanol, the reflux ratio is 2-3, the number of tower plates is 23-25, and the feed port is located at the 13th to 15th tower plate.

6. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to any one of claims 1 to 5, characterized in that: In step (2), the first extractive distillation tower and the second extractive distillation tower are operated under reduced pressure, the extractant used in the second extractive distillation tower is 1,2-propylene glycol or butyl acetate, the extractant used in the third extractive distillation tower is isopropanol or butyl acetate, and the first extractive distillation tower uses one of butyl acetate, 1,2-propylene glycol and isopropanol as the extractant.

7. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to claim 1, characterized in that: In step (3), the filter element is arranged in the particle pretreatment tank, and a multi-stage filter element is arranged in series, and the material of each stage of the filter element is nylon, and the pore size is 10-40 μm.

8. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to claim 1, characterized in that: In step (3), the process parameters of the molecular distillation tower are: pressure of 0.01-0.012 MPa, temperature of 140-150° C., and reflux ratio of 2-5.

9. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to claim 1, characterized in that: In step (4), the pressure of the raw material treated in step (3) passing through the organic silicone modified polyacrylonitrile membrane is controlled to be 1-5 MPa and the flow rate is controlled to be 80-500 L / h.

10. The method for purifying semiconductor-grade propylene glycol methyl ether acetate according to claim 1, characterized in that: In step (5), the pressure of the material passing through the gel styrene-based anion exchange resin is controlled to be 0.1-0.5MPa, and the flow rate is 60-90L / h; and / or, in step (5), the pressure of the material passing through the modified polytetrafluoroethylene membrane is controlled to be 0.1-0.5MPa, and the flow rate is 60-90L / h; and / or, in step (5), the nanofiltration treatment uses a hollow fiber nanofiltration membrane as a filter membrane, the material of the hollow fiber nanofiltration membrane is polytetrafluoroethylene, and the pore size is less than or equal to 0.04μm.

Images