KR-20260065794-A - Method for preparing purified aqueous isopropyl alcohol solution

KR20260065794AKR 20260065794 AKR20260065794 AKR 20260065794AKR-20260065794-A

Abstract

A method for producing a purified aqueous isopropyl alcohol solution from a low-moisture waste liquid of isopropyl alcohol containing toluene as an impurity, comprising a low-boiling point distillation process in which the low-moisture waste liquid of isopropyl alcohol is supplied to a raw material feed end of a distillation column, and simultaneously extracts an effluent containing toluene from the top of the distillation column and extracts a bottom effluent containing isopropyl alcohol and water from the bottom of the distillation column, wherein the water content in the liquid phase at the raw material feed end of the distillation column is adjusted to be 70 mass% or more and 95 mass% or less.

Inventors

호사카 스케
야마시타 요시아키
도쿠나가 다카시

Assignees

가부시키가이샤 도쿠야마

Dates

Publication Date: 20260511
Application Date: 20240809
Priority Date: 20230907

Claims (9)

A method for preparing a purified aqueous isopropyl alcohol solution from a low-moisture waste liquid of isopropyl alcohol containing toluene as an impurity, The low-boiling point distillation process comprises supplying the above isopropyl alcohol low-moisture waste liquid to the raw material feed end of a distillation column, extracting an effluent containing toluene from the top of the distillation column, and simultaneously extracting a bottom effluent containing isopropyl alcohol and water from the bottom of the distillation column. A method for producing a purified aqueous isopropyl alcohol solution by adjusting the water content in the liquid phase at the raw material feed end of the distillation column to be 70 mass% or more and 95 mass% or less.
In paragraph 1, A method for preparing a purified aqueous isopropyl alcohol solution, wherein the above isopropyl alcohol low-water content waste liquid is a waste liquid recovered from a semiconductor manufacturing apparatus having a rinse section of a semiconductor substrate.
In paragraph 1 or 2, A method for producing a purified aqueous isopropyl alcohol solution, wherein the water content in the liquid phase at the raw material feed end of the distillation column is adjusted to be 80 mass% or more and 93 mass% or less.
In paragraph 1 or 2, A method for preparing a purified aqueous isopropyl alcohol solution, wherein the above isopropyl alcohol low-water content waste liquid has a toluene content of 1 ppm or more and 2000 ppm or less as a mass ratio to isopropyl alcohol.
A method for producing purified isopropyl alcohol from a purified isopropyl alcohol aqueous solution obtained by the method for producing a purified isopropyl alcohol aqueous solution according to claim 1 or 2, wherein A method for producing purified isopropyl alcohol, comprising a dehydration process for dehydrating the above-mentioned purified isopropyl alcohol aqueous solution.
In paragraph 5, A process for generating an azeotropic mixture by distilling the above-mentioned purified aqueous isopropyl alcohol solution to extract an azeotropic mixture of isopropyl alcohol and water as an effluent, and A method for producing purified isopropyl alcohol, comprising a dehydration process including adding an azeotropic agent to the above-mentioned azeotropic mixture of isopropyl alcohol and water, distilling the mixture, and dehydrating by extracting a liquid containing isopropyl alcohol.
In paragraph 5, The above purified isopropyl alcohol is a semiconductor solution, and the method for manufacturing purified isopropyl alcohol.
In Paragraph 7, A method for manufacturing purified isopropyl alcohol, the above semiconductor solution being a rinse solution for a semiconductor substrate.
In paragraph 6, A second low-boiling point distillation process for low-boiling point distilling the above-mentioned dehydrated azeotropic mixture and extracting a distillate containing isopropyl alcohol, and A method for producing purified isopropyl alcohol, further comprising a high-boiling point distillation process of distilling a culling liquid containing isopropyl alcohol and extracting an effluent containing isopropyl alcohol.

Description

Method for preparing purified aqueous isopropyl alcohol solution The present invention relates to a method for preparing an aqueous solution of purified isopropyl alcohol and a method for preparing purified isopropyl alcohol. Isopropyl alcohol (hereinafter also abbreviated as 'IPA') has the property of dissolving both water and organic solvents, so it is widely used as a solvent for paints and inks, as well as as a raw material for various synthetic materials. In addition, high-purity IPA is used in large quantities in the rinsing section of semiconductor substrates equipped with semiconductor manufacturing equipment, and its usage is expected to increase in the future. The manufacturing cost of high-purity IPA is high, and in the rinsing section of semiconductor substrates where it is used in large quantities, it has been a factor in increasing costs. In addition, used IPA waste liquid is generally disposed of by combustion, but since this process emits carbon dioxide, which is identified as a cause of global warming, it is desirable to reduce the amount of waste from the perspective of environmental conservation. Accordingly, there is a growing demand to recover, purify, and reuse IPA waste liquid discharged from such industrial facilities (see, for example, Patent Document 1). Meanwhile, the rinse section of the semiconductor substrate is generally installed adjacent to the downstream end of the cleaning section of the semiconductor substrate. Since the cleaning solution used in the cleaning section is generally ultrapure water or a high-water content solution, the rinse section flushes out moisture attached to the surface of the semiconductor substrate from the cleaning section. Therefore, the IPA waste liquid recovered from the rinse section tends to become a low-water content composition containing a small amount of water. In addition, IPA is used in large quantities in the developing section and the pre-wet section, and water is also frequently used in various parts of the semiconductor manufacturing device. Therefore, in semiconductor manufacturing devices equipped with a rinse section, it is common for low-water content IPA waste liquid to be discharged; for example, in Patent Document 2, the water content in the low-water content IPA waste liquid is assumed to be about 5 mass%. On the other hand, toluene is used in the cleaning or rinsing sections of semiconductor manufacturing equipment, and it is also widely used as a solvent for solids, such as as a solvent component for photoresist materials used in the developing section or as a solvent component for adhesives used in various parts. In addition, compounds containing toluenesulfonyl groups are frequently used in substrate treatment agents, and toluene can be generated when these compounds decompose. For this reason, trace amounts of toluene may also be mixed into the recovered IPA waste liquid. Accordingly, low-moisture IPA waste liquid containing toluene as an impurity (hereinafter also abbreviated simply as "low-moisture IPA waste liquid") can be recovered from industrial equipment such as semiconductor manufacturing equipment equipped with a rinsing unit, and purification treatment of the low-moisture IPA waste liquid is carried out. In general, distillation is a conventional purification method for organic solvents, and for example, Patent Document 3 proposes purifying low-moisture IPA waste liquid, which may contain toluene as an impurity with a water content of 5 to 15%, by applying a purification process using distillation. [Prior Art Literature] [Patent Literature] [Patent Document 1] Patent Publication No. 2017-144410 [Patent Document 2] Patent Publication No. 2014-55120 [Patent Document 3] Specification of Chinese Patent Application Publication No. 112999679 [Fig. 1] This is a schematic diagram showing a representative example of a low-boiling point distillation process. [Figure 2] This is a graph showing the effect of water concentration on the relative volatility α of toluene relative to IPA. Hereinafter, embodiments of the present invention will be described with reference to the drawings. Method for preparing purified IPA aqueous solution (IPA low-moisture wastewater) In this embodiment, the liquid to be distilled is an IPA low-moisture waste liquid containing toluene as an impurity. IPA low-moisture waste liquid is often discharged from the manufacture of paints and inks and various industrial facilities that use them. The recovered waste liquid can be applied without limitation, but the most suitable for purification is the waste liquid recovered from a semiconductor manufacturing device equipped with a rinsing unit for a semiconductor substrate. In particular, the waste liquid recovered from the rinsing unit is suitable for application as it is easy to form a low-moisture composition. In addition, a developer, pre-wet liquid, etching liquid, cleaning liquid, stripping liquid, and drying liquid discharged from a semiconductor m