Propylene glycol monomethyl ether acetate composition

Abstract

This propylene glycol monomethyl ether acetate composition contains propylene glycol 1-monomethyl ether 2-acetate, and has an absorbance of 0.030 or less at 259 nm as measured after the propylene glycol monomethyl ether acetate composition has been submitted to the following test. (Test) The propylene glycol monomethyl ether acetate composition is heated to 80°C in a container made of borosilicate glass in a nitrogen atmosphere, and kept in that condition for 275 hours.

Description

Propylene glycol monomethyl ether acetate composition

[0001] The present invention relates to propylene glycol monomethyl ether acetate compositions.

[0002] Propylene glycol monomethyl ether acetate (hereinafter also referred to as "PMA") is known as an organic solvent used in various applications, such as chemical solutions in semiconductor device manufacturing. PMA is produced, for example, by carrying out a direct esterification reaction between propylene glycol monomethyl ether (hereinafter also referred to as "PM") and acetic acid under predetermined conditions (see, for example, Patent Document 1).

[0003] Chinese Patent Application Publication No. 1515537

[0004] It has been found that when PMA obtained by the method described in Patent Document 1 is stored for a long period of time, its absorption of light in the short wavelength region tends to increase. Thus, the technology described in Patent Document 1 has room for improvement from the viewpoint of preventing an increase in short wavelength light absorption after long-term storage.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a propylene glycol monomethyl ether acetate composition that is less likely to exhibit an increase in short wavelength light absorption even after long-term storage.

[0006] The present inventors have found that the above-mentioned problems can be solved by a propylene glycol monomethyl ether acetate composition having an absorbance of a predetermined value or less after a predetermined test, or a propylene glycol monomethyl ether acetate composition having a predetermined composition after the test, and have thus completed the present invention.

[0007] That is, the present invention encompasses the following aspects: [1] A propylene glycol monomethyl ether acetate composition containing propylene glycol 1-monomethyl ether 2-acetate, wherein the propylene glycol monomethyl ether acetate composition has an absorbance at 259 nm of 0.030 or less, measured after subjecting the propylene glycol monomethyl ether acetate composition to the following test: (Test) The propylene glycol monomethyl ether acetate composition is heated to 80°C in a nitrogen atmosphere in a borosilicate glass container and maintained therein for 275 hours. [2] A propylene glycol monomethyl ether acetate composition containing propylene glycol 1-monomethyl ether 2-acetate, wherein, when the propylene glycol monomethyl ether acetate composition is subjected to the following test and then subjected to gas chromatography analysis under the following conditions, the sum of the area ratio of the peak appearing in the relative retention time range of 0.64 to 0.72 and the area ratio of the peak appearing in the relative retention time range of 1.63 to 1.66, when the relative retention time of the peak of propylene glycol 1-monomethyl ether 2-acetate is set to 1.00, is 800 ppm or less. (Test) The propylene glycol monomethyl ether acetate composition is heated to 80°C in a nitrogen atmosphere in a borosilicate glass container and maintained for 275 hours. (Gas Chromatography Analysis Conditions) Analytical column: a column with a stationary phase of polyethylene glycol, length 30 m x inner diameter 0.25 mm x film thickness 0.25 μm Heating conditions: held at 50°C for 10 minutes, then heated to 250°C at 5°C / min Sample introduction temperature: 250°C Carrier gas: nitrogen Column gas flow rate: 1.0 mL / min Detector and detection temperature: hydrogen flame ionization detector, 250°C Control mode: column flow rate Split ratio: 50:1 Injection volume: 2.0 μL

[0008] According to the present invention, it is possible to provide a propylene glycol monomethyl ether acetate composition that is unlikely to increase in short wavelength light absorption even after long-term storage.

[0009] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0010] <Propylene glycol monomethyl ether acetate composition> The propylene glycol monomethyl ether acetate composition according to the first aspect of this embodiment (hereinafter also referred to as the "first PMA composition") is a propylene glycol monomethyl ether acetate composition containing propylene glycol 1-monomethyl ether 2-acetate (hereinafter also referred to as "PGMEA"), and the propylene glycol monomethyl ether acetate composition has an absorbance at 259 nm of 0.030 or less, measured after being subjected to the following test. (Test) The propylene glycol monomethyl ether acetate composition is heated to 80°C in a nitrogen atmosphere in a borosilicate glass container and maintained for 275 hours. Because the first PMA composition has this configuration, it is less likely to experience an increase in short-wavelength light absorption, even after long-term storage. Furthermore, a propylene glycol monomethyl ether acetate composition according to a second aspect of this embodiment (hereinafter also referred to as a "second PMA composition") is a propylene glycol monomethyl ether acetate composition containing PGMEA, and when the propylene glycol monomethyl ether acetate composition is subjected to the following tests and then subjected to gas chromatography analysis (hereinafter also referred to as "GC analysis") under the following conditions, when the relative retention time of the peak of propylene glycol 1-monomethyl ether 2-acetate is taken as 1.00, the sum of the area ratio of a peak appearing in a relative retention time range of 0.64 to 0.72 (the substance corresponding to this peak will be referred to as "component X" hereinafter) and the area ratio of a peak appearing in a relative retention time range of 1.63 to 1.66 (the substance corresponding to this peak will be referred to as "component Y" hereinafter) is 800 ppm or less. (Test) The propylene glycol monomethyl ether acetate composition is heated to 80° C. in a borosilicate glass vessel under a nitrogen atmosphere and maintained at this temperature for 275 hours.(Gas Chromatography Analysis Conditions) Analytical column: Column with polyethylene glycol stationary phase, length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm Heating conditions: Hold at 50°C for 10 minutes, then heat to 250°C at 5°C / min Sample introduction temperature: 250°C Carrier gas: Nitrogen Column gas flow rate: 1.0 mL / min Detector and detection temperature: Flame ionization detector, 250°C Control mode: Column flow rate Split ratio: 50:1 Injection volume: 2.0 μL The second PMA composition having the above configuration also does not easily exhibit an increase in short-wavelength light absorption, even after long-term storage. In this specification, unless otherwise specified, the following description of the propylene glycol monomethyl ether acetate composition applies to both the first PMA composition and the second PMA composition. That is, when referring to the "PMA composition of this embodiment," both the first PMA composition and the second PMA composition are included unless otherwise specified.

[0011] The present inventors have found that when conventionally commercially available PMA (commercially available PMA) is used after long-term storage, for example, when used in semiconductor device manufacturing, the quality of the resulting semiconductor devices varies. Based on this finding, the present inventors conducted extensive research and found that commercial PMA tends to exhibit increased UV absorption after long-term storage compared to before storage. This increased absorption of short-wavelength light tends to cause problems, such as competitive absorption of exposure light and interference with the exposure process, when used as a solvent for semiconductor device manufacturing after long-term storage. Based on these findings, the present inventors have concluded that if the absorbance at 259 nm measured for a PMA composition that has undergone accelerated testing is below a predetermined value, an increase in short-wavelength light absorption is unlikely, even after long-term storage, and the above-mentioned problems can be avoided. From the above viewpoint, the absorbance at 259 nm of the first PMA composition, measured after the above test, is 0.030 or less, preferably 0.028 or less, and more preferably 0.026 or less. From the same viewpoint, the absorbance at 259 nm of the second PMA composition, measured after the above test, is also preferably 0.030 or less, more preferably 0.028 or less, and even more preferably 0.026 or less. The absorbance can be measured based on the method described in the Examples below. The absorbance can be adjusted to the above range, for example, by adjusting the total amount of component X and component Y, described below, to a preferred range, or by adjusting the dissolved oxygen, described below, to a preferred range.

[0012] Furthermore, as a result of extensive investigations, the present inventors have found that commercially available PMA products tend to contain an increased amount of several impurities after long-term storage compared to before said storage. Focusing on those impurities whose content has increased significantly, the inventors confirmed the level of UV absorption of each impurity and determined that the influence of component X and component Y is relatively large. Based on these investigations, the present inventors have concluded that if the total amount of component X and component Y measured by GC analysis of a PMA composition that has undergone an accelerated test is equal to or less than a predetermined value, an increase in short-wavelength light absorption is unlikely to occur even after long-term storage, and the above-mentioned problems can be avoided. From the above viewpoint, when the second PMA composition is subjected to the above test and then subjected to the above GC analysis, the sum of the area ratio of the peak appearing in the relative retention time range of 0.64 to 0.72 and the area ratio of the peak appearing in the relative retention time range of 1.63 to 1.66, where the relative retention time of the peak of propylene glycol 1-monomethyl ether 2-acetate is taken as 1.00, is 800 ppm or less, preferably 750 ppm or less, and more preferably 700 ppm or less. From the same viewpoint as above, when the first PMA composition is subjected to the above test and then subjected to the above GC analysis, this sum is preferably 800 ppm or less, more preferably 750 ppm or less, and even more preferably 700 ppm or less. This sum can be measured based on the method described in the Examples below. This sum can be adjusted to the above range, for example, by adjusting the contents of acetic acid, propionic acid, and formic acid, as described below, to their respective preferred ranges, as well as by adjusting the dissolved oxygen content, as described below, to their preferred ranges.

[0013] The PMA composition of this embodiment can be used for industrial purposes, including, but not limited to, inks, thinners, pharmaceuticals and agricultural chemicals, plasticizers, surfactants, polymeric materials, lubricants, adhesives, cleaners, electronic materials, and paints. Electronic materials include, but are not limited to, liquid crystal displays (LCDs) and semiconductor devices. The PMA composition of this embodiment is preferably used in the manufacture of semiconductor devices because it is less likely to increase short-wavelength light absorption even after long-term storage. Specific examples of applications related to the manufacture of semiconductor devices include, but are not limited to, cleaning solutions (e.g., treatment solutions for cleaning substrate surfaces after resist stripping), prewetting solutions (e.g., treatment solutions used before resist coating to reduce resist solvent consumption), resist solvents (e.g., treatment solutions for dissolving photosensitizers and resins), developers (e.g., treatment solutions for removing soluble resins after exposure of negative resists), and stripping solutions (e.g., treatment solutions used to remove hardened resists after etching). From the viewpoint of preventing product defects in the manufacture of semiconductor devices, the PMA composition of the present embodiment is preferably used as a resist solvent, a pre-wet liquid, a solvent for an edge rinse (rinse for removing resist from the outer periphery of a wafer) and a back rinse (rinse for removing resist from the back surface of a wafer) used during resist coating, a developer used during negative resist development, a rinse liquid used during rinsing of a negative resist after development, a cleaning liquid or rinse liquid used for removing resist after etching, and the like.

[0014] (Propylene glycol 1-monomethyl ether 2-acetate) PGMEA in the PMA composition of this embodiment can be identified and quantified, for example, by the following gas chromatography (hereinafter also referred to as "GC") analysis. (Gas Chromatography Analysis) Analytical column: Column with polyethylene glycol stationary phase, length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm Heating conditions: Hold at 50°C for 10 minutes, then heat to 250°C at 5°C / min Sample introduction temperature: 250°C Carrier gas: Nitrogen Column gas flow rate: 1.0 mL / min Detector and detection temperature: Hydrogen flame ionization detector, 250°C Control mode: Column flow rate Split ratio: 50:1 Injection volume: 2.0 μL The content of PGMEA in the PMA composition of this embodiment can be determined appropriately depending on the application of the PMA composition of this embodiment, and is not particularly limited. However, from the viewpoint of use in applications requiring high purity, the peak area ratio to the total peak area of ​​the chart obtained as a result of GC analysis is preferably 99.89% or more, more preferably 99.90% or more. In this embodiment, the "total peak area" refers to the sum of the areas of all peaks appearing in the chart obtained as a result of GC analysis. In this embodiment, "all peaks" can be specified as meaning all peaks that appear when the analysis is continued and stopped from a relative retention time of 0.14 to 2.95, assuming that the relative retention time of the PGMEA peak is 1.00.

[0015] (Acetic Acid) The PMA composition of this embodiment may or may not contain acetic acid. The acetic acid content in the PMA composition of this embodiment is preferably 3 ppm or more, based on 100% by mass of the PMA composition of this embodiment, from the viewpoint of productivity. From the viewpoint of suppressing an increase in short-wavelength light absorption even after long-term storage, it is preferably 58 ppm or less. That is, the acetic acid content is preferably 3 ppm or more and 58 ppm or less, more preferably 3 ppm or more and 50 ppm or less, and even more preferably 3 ppm or more and 40 ppm or less, based on 100% by mass of the PMA composition of this embodiment. The content can be measured based on the method described in the Examples below. The content can be adjusted to the above-mentioned range, for example, by appropriately adding acetic acid after performing the base treatment described below. The content can also be adjusted to the above-mentioned range, for example, by appropriately changing the base treatment conditions (e.g., treatment time, etc.) or by adjusting the amount of distillate in step (e) described below.

[0016] (Propionic Acid) The PMA composition of this embodiment may or may not contain propionic acid. From the viewpoint of suppressing an increase in short-wavelength light absorption even after long-term storage, the propionic acid content in the PMA composition of this embodiment is 30 ppm or less, preferably 25 ppm or less, and more preferably 20 ppm or less, based on 100% by mass of the PMA composition of this embodiment. The content can be measured based on the method described in the Examples below. The content can be adjusted to the above-mentioned range, for example, by performing the base treatment described below and then appropriately adding propionic acid. The content can also be adjusted to the above-mentioned range, for example, by appropriately changing the base treatment conditions (e.g., treatment time, etc.) or by adjusting the distillate amount in step (e) described below.

[0017] (Formic Acid) The PMA composition of this embodiment may or may not contain formic acid. From the viewpoint of suppressing an increase in short-wavelength light absorption even after long-term storage, the content of formic acid in the PMA composition of this embodiment is preferably 10 ppm or less, more preferably 5 ppm or less, and even more preferably below the detection limit (2 ppm or less), relative to 100% by mass of the PMA composition of this embodiment. The content can be measured based on the method described in the Examples below. The content can be adjusted to the above-mentioned range, for example, by performing the base treatment described below and then appropriately adding formic acid. The content can also be adjusted to the above-mentioned range, for example, by appropriately changing the conditions of the base treatment (e.g., treatment time, etc.) or by adjusting the amount of distillate in step (e) described below.

[0018] (Sum of Contents of Acetic Acid, Propionic Acid, and Formic Acid) In this embodiment, from the viewpoint of suppressing an increase in short-wavelength light absorption even after long-term storage, the sum of the contents of acetic acid, propionic acid, and formic acid in the PMA composition of this embodiment is 5 ppm to 60 ppm, preferably 5 ppm to 55 ppm, and more preferably 5 ppm to 50 ppm, based on 100% by mass of the PMA composition of this embodiment. The above contents can be measured based on the method described in the Examples below. The above contents can be adjusted to the above range, for example, by performing the base treatment described below and then appropriately adding acetic acid, propionic acid, and / or formic acid. The above contents can also be adjusted to the above range, for example, by appropriately changing the conditions of the base treatment (e.g., treatment time, etc.) or by adjusting the amount of distillate in step (e) described below.

[0019] (PM) The PMA composition of this embodiment may contain propylene glycol monomethyl ether (PM). From the viewpoint of suppressing an increase in short-wavelength light absorption even after long-term storage, the PM content in the PMA composition of this embodiment is preferably 4.0 ppm or less, relative to 100% by mass of the PMA composition of this embodiment, and more preferably below the detection limit (2 ppm or less) in the GC analysis. The content can be measured based on the method described in the Examples below. The content can be adjusted to the above-mentioned range, for example, by azeotropic dehydration after esterification, followed by distillative purification, or the like.

[0020] (Component X) From the viewpoint of suppressing an increase in short-wavelength light absorption even after long-term storage, when the PMA composition of the present embodiment is subjected to the above test and then subjected to the above GC analysis, the content of component X, i.e., the area ratio of the peak appearing in the relative retention time range of 0.64 to 0.72, where the relative retention time of the peak of propylene glycol 1-monomethyl ether 2-acetate is taken as 1.00, is preferably 700 ppm or less, more preferably 650 ppm or less, and even more preferably 600 ppm or less. The area ratio can be measured based on the method described in the Examples below. The area ratio can be adjusted to the above range, for example, by adjusting the sum of the contents of formic acid, acetic acid, and propionic acid to the above range and / or adjusting the dissolved oxygen of the PMA composition to the below-described range.

[0021] (Component Y) From the viewpoint of suppressing an increase in short-wavelength light absorption even after long-term storage, when the PMA composition of the present embodiment is subjected to the above test and then subjected to the above GC analysis, the content of component Y, i.e., the area ratio of the peak appearing in the relative retention time range of 1.63 to 1.66, where the relative retention time of the peak of propylene glycol 1-monomethyl ether 2-acetate is set to 1.00, is preferably 105 ppm or less, more preferably 103 ppm or less, and even more preferably 100 ppm or less. The area ratio can be measured based on the method described in the Examples below. The area ratio can be adjusted to the above range, for example, by adjusting the sum of the contents of formic acid, acetic acid, and propionic acid to the above range and / or adjusting the dissolved oxygen of the PMA composition to the below-described range.

[0022] (Dissolved Oxygen) From the viewpoint of suppressing an increase in short-wavelength light absorption even after long-term storage, the dissolved oxygen (%) in the PMA composition of this embodiment is preferably 40.0% or less, more preferably 35.0% or less, and even more preferably 30.0% or less, relative to the saturated dissolved oxygen amount in water at atmospheric pressure and 25°C. The dissolved oxygen (%) in the PMA composition of this embodiment can be determined as follows. That is, the saturated dissolved oxygen amount (mg / L) in water is measured in advance using a diaphragm-type galvanic cell oxygen sensor under conditions of atmospheric pressure of 101.3 kPa, room temperature of 25°C, and stirring, and this is taken as 100% saturation. Separately, the dissolved oxygen in the PMA composition is measured using a diaphragm-type galvanic cell oxygen sensor under conditions of atmospheric pressure of 101.3 kPa, room temperature of 25°C, and stirring, and the dissolved oxygen (%) in the PMA composition can be calculated as a ratio (%) to the 100% saturation. More specifically, the dissolved oxygen (%) can be measured using an organic solvent-compatible DO meter (model: B-506S) and an organic solvent DO measuring device (model: MA-300G-SL) manufactured by Iijima Electronics Co., Ltd., with the PMA composition filled in a measurement tank, using a stirrer (a PTFE (polytetrafluoroethylene) stirrer, cross-shaped, manufactured by Flon Industries, model: FK-10) and a stirrer (an ultra-thin digital stirrer manufactured by Kenis, model: KK) while stirring at a rotation speed of 1100 to 1400 rpm. The organic solvent-compatible DO meter can be span calibrated (calibration method: air calibration) at atmospheric pressure and 25 ° C. before starting measurement. The dissolved oxygen (%) can be adjusted to the above-mentioned range, for example, by adjusting the air / nitrogen ratio in step (f) described below.

[0023] <Method for Producing PMA Composition> The method for producing the PMA composition of this embodiment is not particularly limited, but the following method (hereinafter also referred to as "Production Method A") is preferred. Production Method A preferably includes the steps of: (a) obtaining a first product containing PGMEA; (b) distilling the first product to obtain a second product; (c) treating the second product with a base to obtain a third product; (d) desalting the third product to obtain a fourth product; (e) distilling the fourth product under reduced pressure to remove high-boiling components and obtain a fifth product from the top of the column; and (f) distilling the fifth product under reduced pressure to remove low-boiling components, and then supplying a gas having a predetermined air / nitrogen ratio to the bottom of the distillation column to obtain a sixth product, the PMA composition, from the bottom of the column. The amounts of formic acid, acetic acid, propionic acid, and dissolved oxygen in the PMA composition can be adjusted by steps (c), (e), and (f). The above production method may further include a step (g) of adding formic acid, acetic acid, and / or propionic acid to the product obtained through the step (f) to obtain a PMA composition, in order to adjust the amounts of formic acid, acetic acid, and propionic acid in the PMA composition.

[0024] (Step (a)) In step (a), a first product containing PGMEA is obtained. Step (a) may include an operation for producing PGMEA based on a conventionally known method. The method for producing PGMEA is not particularly limited, but examples thereof include the method described in Chinese Patent Application Publication No. 1515537. Specifically, PGMEA can be produced by carrying out a direct esterification reaction between PM and acetic acid. The first product may contain raw materials, catalysts, by-products, etc. that can be used in the reaction for producing PGMEA.

[0025] (Step (b)) In step (b), the first product is distilled to obtain a second product. The specific distillation procedure is not particularly limited, and examples thereof include atmospheric distillation and reduced pressure distillation, and such distillation may be performed repeatedly. In this step, raw materials, catalysts, by-products, etc. that may be contained in the first product and that can be used in the reaction to produce PGMEA can be removed. The distillation conditions are not particularly limited, and the distillation can be performed with reference to the conditions described in Chinese Patent Application Publication No. 1515537, for example. The amounts of PM, formic acid, acetic acid, and propionic acid that may be contained in the second product may be greater than 4 ppm, greater than 10 ppm, greater than 58 ppm, and greater than 30 ppm, respectively, based on the second product being 100% by mass.

[0026] In step (c), the second product is subjected to a base treatment to obtain a third product. The conditions for the base treatment are preferably conditions that can reduce the amounts of formic acid, acetic acid, and propionic acid contained in the second product, and are not particularly limited. For example, the base treatment may be performed using Kyoward 500 (registered trademark) manufactured by Kyowa Chemical Industry Co., Ltd. In this case, the amounts of PM, formic acid, acetic acid, and propionic acid that may be contained in the third product can be adjusted by, for example, adjusting the amount of Kyoward 500 used and the treatment time. Kyoward 500, etc., used in the base treatment can be removed by filtration using a PTFE membrane filter or the like.

[0027] (Step (d)) In step (d), the third product is subjected to a desalting treatment to obtain a fourth product. The specific operation of the desalting treatment is not particularly limited, and examples thereof include flash distillation or water washing, and such treatments may be repeated. In this step, various salts that may be contained in the third product can be removed. The distillation conditions are not particularly limited, and the distillation can be carried out, for example, by supplying the third product at a linear velocity (LV) of 55 to 65 m / Hr to a flash drum heated to about 65 to 75°C under a reduced pressure (absolute pressure in the system during distillation; the same applies hereinafter) of 2.5 to 3.5 kPa.

[0028] (Step (e)) In step (e), the fourth product is distilled under reduced pressure to remove high-boiling components, thereby obtaining a fifth product from the top of the column. The specific operation of the vacuum distillation is not particularly limited, and vacuum distillation may be performed repeatedly. In this step, impurities having relatively high boiling points that may be contained in the fourth product can be removed. The distillation conditions are not particularly limited, but for example, the distillation can be performed by using a distillation column with approximately 20 theoretical plates, performing total reflux at a reduced pressure of 1.5 to 2.5 kPa and a column bottom temperature of 35 to 45°C, feeding the fourth product from the bottom of the column at a linear velocity of 25 to 35 m / Hr, and distilling 85 to 96% of the fifth product from the top of the column at a reflux ratio of 1 / 1.

[0029] (Step (f)) In step (f), the fifth product is distilled under reduced pressure to remove low-boiling components, and a gas having a predetermined air / nitrogen ratio is supplied to the bottom of the distillation column to obtain a PMA composition as a sixth product from the bottom. The gas supply conditions are not particularly limited as long as they can reduce the amount of dissolved oxygen in the PMA composition to a desired value. For example, the amount of dissolved oxygen tends to decrease by reducing the air / nitrogen ratio (i.e., the oxygen / nitrogen ratio) of the gas supplied. The air / nitrogen ratio can also be controlled as the oxygen partial pressure at the bottom of the distillation column, and the oxygen partial pressure is preferably 5.0 kPa or less, more preferably 4.0 kPa or less, and even more preferably 3.0 kPa or less. The distillation conditions are not particularly limited, and can be carried out, for example, using a distillation column having about 20 theoretical plates, at a reduced pressure of 1.5 to 2.5 kPa and a column bottom temperature of 45 to 55°C, by supplying a gas prepared to a predetermined air / nitrogen ratio from the column bottom at a linear velocity of 0.017 to 0.019 m / Hr, and removing a predetermined amount of low-boiling point components from the column top at a reflux ratio of 1 / 1. In step (f), the amount of water contained can also be adjusted by adjusting the reflux ratio and the amount of effluent from the column top.

[0030] (Step (g)) In step (g), formic acid, acetic acid, and / or propionic acid can be added to the product obtained through step (f) to adjust the amount of formic acid, acetic acid, and / or propionic acid in the PMA composition. The amount of formic acid, acetic acid, and / or propionic acid added is not particularly limited, but can be determined, for example, based on the difference between the formic acid content C1, acetic acid content C2, and propionic acid content C3 in the desired PMA composition and the formic acid content C1', acetic acid content C2', and propionic acid content C3' in the product obtained through step (f). Each content can be measured based on the method described in the Examples below.

[0031] The present embodiment will be described in more detail below based on examples, but the present embodiment is not limited to these examples.

[0032] [Comparative Example 1] (Step (a)) A first product containing PGMEA was synthesized by referring to the method described in Chinese Patent Application Publication No. 1515537. That is, PGMEA was synthesized by carrying out a direct esterification reaction between PM and acetic acid.

[0033] (Step (b)) Next, the first product containing PGMEA was introduced into a distillation column and subjected to atmospheric distillation. That is, at a reflux ratio of 1 / 4, a fraction containing unreacted raw materials was first distilled off, and then a fraction containing PGMEA was recovered.

[0034] Next, the fraction containing PGMEA obtained by atmospheric distillation was introduced into a distillation column and subjected to reduced pressure distillation. That is, the degree of vacuum in the distillation column was set to 21.3 kPa, the temperature in the distillation column was controlled to 110 ° C or less, the reflux ratio was set to 1 / 4, and the fraction at the top of the column (temperature 98-100 ° C) was recovered as the second product. The content of PGMEA in the obtained second product was 99.83% as the peak area ratio to the total peak area of ​​the chart obtained as a result of GC analysis. Furthermore, the amount of formic acid contained in the second product was below the detection limit (below the detection limit in HPLC analysis), taking the second product as 100% mass. The amounts of PM, acetic acid, and propionic acid contained in the second component were below the detection limit (below the detection limit in GC analysis), 60 ppm, and 150 ppm, respectively, taking the second product as 100% mass.

[0035] The content of formic acid in the second product was measured and confirmed by liquid chromatography analysis (HPLC analysis) under the following conditions. (Liquid Chromatography Analysis) Analytical apparatus: LC1260 Infinity II manufactured by Agilent Technologies Analytical column: TSKgel ODS-100V (5 μm, 250 × 4.6 mm I.D.) manufactured by Tosoh Corporation Detector and detection temperature: Differential refractive index detector, 35°C Column oven: 40°C Eluent: 0.1 wt% aqueous phosphoric acid solution Flow rate: 1.0 mL / min Injection amount: 20 μL In the above HPLC analysis, the content of formic acid was calculated by the absolute calibration curve method. In the following examples and comparative examples, the amount of formic acid was confirmed in the same manner as above.

[0036] The contents of PGMEA, PM, acetic acid and propionic acid in the second product were measured and confirmed by GC analysis under the following conditions. (Gas Chromatography Analysis) Analytical apparatus: Nexis GC-2030 manufactured by Shimadzu Corporation Analytical column: DB-WAX manufactured by Agilent Technologies (a column having a stationary phase of polyethylene glycol, a length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 0.25 μm) Heating conditions: After holding at 50° C. for 10 minutes, the temperature was increased to 250° C. at 5° C. / min Sample introduction temperature: 250° C. Carrier gas: nitrogen Column gas flow rate: 1.0 mL / min Detector and detection temperature: hydrogen flame ionization detector, 250° C. Control mode: column flow rate Split ratio: 50:1 Injection amount: 2.0 μL In the above GC analysis, the content of PGMEA was calculated as the area percentage of the PGMEA peak relative to the total peak area of ​​the chart obtained as a result of GC analysis. The PM content was calculated as the percentage of the PM peak area relative to the total peak area in the chart obtained as a result of GC analysis. The contents of acetic acid and propionic acid were calculated by the absolute calibration curve method using GC analysis. In the following examples and comparative examples, the amounts of PGMEA, PM, acetic acid, and propionic acid were confirmed in the same manner as above.

[0037] (Step (c)) To the second product (100% by mass) obtained above, 0.7% by mass of Kyoward 500 (registered trademark) manufactured by Kyowa Chemical Industry Co., Ltd. was added, and the mixture was stirred for 60 minutes to remove formic acid, acetic acid, and propionic acid. The mixture was filtered through a PTFE membrane filter (model: T020A047A, pore size: 0.20 μm) manufactured by ADVANTEC to obtain a third product.

[0038] (Step (d)) Next, the third product was introduced into a distillation column and subjected to flash distillation. That is, the third product was supplied to a flash drum heated to about 70°C under a reduced pressure of 3 kPa at a linear velocity (LV) of 59 m / Hr, and 90 mass% (based on 100 mass% of the third product) was distilled from the top of the flash drum to obtain a fourth product.

[0039] (Step (e)) Next, the fourth product was introduced into a distillation column and subjected to reduced pressure distillation. That is, using a distillation column having about 20 theoretical plates, the degree of vacuum in the distillation column was set to 2.0 kPa, the temperature of the bottom of the distillation column was controlled to 40° C., the reflux ratio was set to 1 / 1, the fourth product was supplied from the bottom of the column at a linear velocity of 30 m / Hr, and a 96 mass% fraction was recovered from the top of the column as the fifth product.

[0040] (Step (f)) Next, the fifth product was introduced into a distillation column and subjected to reduced pressure distillation. That is, using a distillation column with approximately 20 theoretical plates, the degree of vacuum in the distillation column was set to 2.0 kPa, and the temperature at the bottom of the distillation column was controlled to 50°C. An air / nitrogen mixed gas with an oxygen partial pressure of 10.6 kPa was supplied from the bottom of the column at a linear velocity of 0.018 m / Hr, and the reflux ratio was set to 1 / 1. 10% by mass of low-boiling point components were distilled off from the top of the column, and the sixth product (PMA composition of Comparative Example 1) was recovered from the bottom of the column. The obtained PMA composition was subjected to HPLC analysis and GC analysis under the same conditions as above. The content of formic acid contained in the obtained PMA composition was below the detection limit as a peak area ratio relative to the total peak area in the chart obtained as a result of HPLC analysis. The contents of PGMEA, PM, acetic acid, and propionic acid contained in the obtained PMA composition were 99.90 area%, below the detection limit, 35 ppm, and 25 ppm, respectively, as peak area ratios relative to the total peak area in the chart obtained from GC analysis. The results are shown in Table 1. In the following examples and comparative examples, the contents of PGMEA, PM, formic acid, acetic acid, and propionic acid were also confirmed in the same manner as above.

[0041] (Dissolved oxygen measurement) The saturated dissolved oxygen amount (mg / L) of water was measured in advance using a diaphragm-type galvanic cell oxygen sensor under conditions of atmospheric pressure 101.3 kPa, room temperature 25 ° C, and stirring (rotation speed 1300 rpm), and this was taken as 100% saturation. Separately, using a diaphragm-type galvanic cell oxygen sensor, the dissolved oxygen in the PMA composition was measured under conditions of atmospheric pressure 101.3 kPa, room temperature 25 ° C, and stirring (rotation speed 1300 rpm), and calculated as a ratio (%) to the 100% saturation. That is, the dissolved oxygen (%) was measured using an organic solvent compatible DO meter (model: B-506S) and an organic solvent DO measuring device (model: MA-300G-SL) manufactured by Iijima Electronics Co., Ltd. The dissolved oxygen (%) contained in the PMA composition was measured and found to be 59.9% of the saturated dissolved oxygen content (mg / L) of water measured under conditions of atmospheric pressure of 101.3 kPa, room temperature of 25°C, and stirring. The results are shown in Table 1. In the following examples and comparative examples, the dissolved oxygen (%) was also confirmed in the same manner as above.

[0042] (Accelerated Test) The PMA composition was then subjected to the following test: The PMA composition was placed in a 110 mL borosilicate glass container, nitrogen was sealed inside, and the container was heated in an incubator (product name "ST-110B1", manufactured by ESPEC) and maintained at 80°C for 275 hours.

[0043] (Absorbance after accelerated test) The PMA composition after the above test was subjected to absorbance measurement as follows. That is, absorbance measurement was carried out at 259 nm using a spectrophotometer (model: U-3900) manufactured by Hitachi High-Tech Fielding Corporation, using a quartz cell with an optical path length of 1 cm. The absorbance at 259 nm of the PMA composition of Comparative Example 1 after the above test was 0.033. The results are shown in Table 1. In the following examples and comparative examples, the absorbance after the heating test was also confirmed in the same manner as above.

[0044] (GC Analysis After Accelerated Test) The PMA composition after the test was subjected to GC analysis under the same conditions as above. Comparing GC Chart A obtained in the GC analysis before the test with GC Chart B obtained in the GC analysis after the test, the components that increased were examined. The components that affected the absorbance were found to be (i) component X, which corresponds to the peak appearing at a relative retention time of 0.64 to 0.72, and (ii) component Y, which corresponds to the peak appearing at a relative retention time of 1.63 to 1.66. Since the substance of component X could not be identified, it was evaluated using the following method. Specifically, the PMA composition obtained after the accelerated test of Comparative Example 1 was distilled to prepare a PMA composition in which the content of impurities other than (i) above was significantly reduced. By comparing the results of the absorbance measurement with those of the PMA composition before distillation, it was determined that (i) above is a substance that has a relatively greater impact on the absorption of short-wavelength light than the other impurities. Analysis of (ii) above revealed that it was 2-acetoxy-1-propanol, and therefore it was evaluated using the following method. That is, a sample of (ii) above was synthesized from 1,2-propanediol and acetic acid, and subjected to absorbance measurement, which determined that (ii) above is a substance that has a relatively greater effect on the absorption of short-wavelength light than other impurities. After the test, the contents of PGMEA, component X, and component Y contained in the PMA composition were 99.77 area%, 751.7 area ppm, and 114.3 area ppm, respectively, as peak area ratios relative to the total peak area of ​​GC Chart B. The results are shown in Table 1, along with the total contents of component X and component Y.

[0045] Example 1 The PMA composition of Example 1 was obtained in the same manner as in Comparative Example 1, except that the amount of distillate from the top of the column in step (e) in Comparative Example 1 was changed to 95 mass% and the oxygen partial pressure of the air / nitrogen mixed gas supplied from the bottom of the column in step (f) was set to 0.0 kPa. This PMA composition was subjected to the same tests as in Comparative Example 1, and then subjected to the same gas chromatography analysis and absorbance measurement as in Comparative Example 1. Details of the analysis results are shown in Table 1.

[0046] Example 2 The PMA composition of Example 2 was obtained in the same manner as in Comparative Example 1, except that the amount of distillate from the top of the column in step (e) in Comparative Example 1 was changed to 92 mass% and the oxygen partial pressure of the air / nitrogen mixed gas supplied from the bottom of the column in step (f) was changed to 1.1 kPa. This PMA composition was subjected to the same tests as in Comparative Example 1, and then subjected to the same gas chromatography analysis and absorbance measurement as in Comparative Example 1. Details of the analysis results are shown in Table 1.

[0047] (Example 3) The PMA composition of Example 3 was obtained in the same manner as in Comparative Example 1, except that the amount of distillate from the top of the column in step (e) in Comparative Example 1 was changed to 90 mass% and the oxygen partial pressure of the air / nitrogen mixed gas supplied from the bottom of the column in step (f) was changed to 2.1 kPa. This PMA composition was subjected to the same tests as in Comparative Example 1, and then subjected to the same gas chromatography analysis and absorbance measurement as in Comparative Example 1. Details of the analysis results are shown in Table 1.

[0048] Example 4 The PMA composition of Example 4 was obtained in the same manner as in Comparative Example 1, except that the amount of distillate from the top of the column in step (e) in Comparative Example 1 was changed to 85 mass% and the oxygen partial pressure of the air / nitrogen mixed gas supplied from the bottom of the column in step (f) was changed to 2.1 kPa. This PMA composition was subjected to the same tests as in Comparative Example 1, and then subjected to the same gas chromatography analysis and absorbance measurement as in Comparative Example 1. Details of the analysis results are shown in Table 1.

[0049] Example 5 The PMA composition of Example 5 was obtained in the same manner as in Comparative Example 1, except that the amount of distillate from the top of the column in step (e) in Comparative Example 1 was changed to 95 mass% and the oxygen partial pressure of the air / nitrogen mixed gas supplied from the bottom of the column in step (f) was changed to 4.2 kPa. This PMA composition was subjected to the same tests as in Comparative Example 1, and then subjected to the same gas chromatography analysis and absorbance measurement as in Comparative Example 1. Details of the analysis results are shown in Table 1.

[0050] (Comparative Example 2) A PMA composition of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the amount of distillate from the top of the column in step (e) in Comparative Example 1 was changed to 90 mass%. This PMA composition was subjected to the same tests as in Comparative Example 1, and then subjected to the same gas chromatography analysis and absorbance measurement as in Comparative Example 1. Details of the analysis results are shown in Table 1.

[0051]

Claims

1. A propylene glycol monomethyl ether acetate composition containing propylene glycol 1-monomethyl ether 2-acetate, wherein the absorbance at 259 nm, measured after subjecting the propylene glycol monomethyl ether acetate composition to the following test, is 0.030 or less. (Test) The propylene glycol monomethyl ether acetate composition is heated to 80° C. in a borosilicate glass container under a nitrogen atmosphere and held for 275 hours.

2. A propylene glycol monomethyl ether acetate composition containing propylene glycol 1-monomethyl ether 2-acetate, wherein when the propylene glycol monomethyl ether acetate composition is subjected to gas chromatography analysis under the following conditions after being subjected to the following test, the sum of the area ratio of the peak appearing in the range of relative retention time of 0.64 to 0.72 and the area ratio of the peak appearing in the range of relative retention time of 1.63 to 1.66 is 800 ppm or less when the relative retention time of the peak of propylene glycol 1-monomethyl ether 2-acetate is set to 1.

00. (Test) The propylene glycol monomethyl ether acetate composition is heated to 80° C. in a borosilicate glass container under a nitrogen atmosphere and held for 275 hours. (Conditions for gas chromatography analysis) Analysis column: A column with a polyethylene glycol stationary phase, length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm Temperature rising condition: Hold at 50° C. for 10 minutes, then raise the temperature to 250° C. at 5° C. / min Sample introduction temperature: 250° C. Carrier gas: Nitrogen Gas flow rate of the column: 1.0 mL / min Detector and detection temperature: Flame ionization detector, 250° C. Control mode: Column flow Split ratio: 50:1 Injection volume: 2.0 μL

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