JP7477730B1 - Isopropyl alcohol container, manufacturing method thereof, and quality control method for isopropyl alcohol container - Google Patents

Abstract

The present invention provides an isopropyl alcohol container in which isopropyl alcohol is contained in a container, the oxygen content in the container being 0.001 to 0.100 mol ppm relative to the isopropyl alcohol, and the content of acetone as an impurity in the isopropyl alcohol being 10 to 200 ppb by mass. Also provided are a method for producing the isopropyl alcohol container, and a method for quality control of the isopropyl alcohol container.

Description

The present disclosure relates to an isopropyl alcohol container in which isopropyl alcohol is contained, a method for manufacturing the container, and a method for quality control of the isopropyl alcohol container.

Isopropyl alcohol (also known as 2-propanol) is an organic solvent used for a variety of purposes, particularly as a cleaning or drying liquid in the manufacturing process of semiconductor devices. In recent years, as semiconductor devices have become more highly functional, elements and wiring have become finer and more highly integrated, and there is a growing demand for highly purified isopropyl alcohol with extremely low levels of metal impurities to be used as a cleaning or drying liquid.

For example, Patent Document 1 describes that if isopropyl alcohol that has had an increase in impurities due to long-term storage is used for cleaning purposes in the manufacturing process of semiconductor devices, residues derived from impurities in the isopropyl alcohol may remain on the surface of the semiconductor device after cleaning and drying, which may cause defects in the semiconductor device. As can be seen from this, the impact of the quality of isopropyl alcohol used as a cleaning liquid or drying liquid on the yield of semiconductor devices can no longer be ignored, and there is a strong demand for improving the quality of isopropyl alcohol.

In addition, organic impurities such as acetone are present in isopropyl alcohol, and it is known that when the dissolved oxygen concentration in isopropyl alcohol is high, the content of organic impurities in isopropyl alcohol increases (see, for example, Patent Documents 2 and 3). As a method for reducing the dissolved oxygen concentration in isopropyl alcohol, Patent Document 2 proposes a method of controlling the oxygen partial pressure in the gas phase of a distillation column in the distillation process during the production of isopropyl alcohol. In addition, Patent Document 3 proposes a method of removing dissolved oxygen by blowing an inert gas such as nitrogen into isopropyl alcohol and bubbling it.

International Publication No. 2020/071307 International Publication No. 2018/135408 JP 2014-201524 A International Publication No. 2020/009225

According to the methods described in Patent Documents 2 and 3, high-purity isopropyl alcohol with a reduced dissolved oxygen concentration can be produced. The produced isopropyl alcohol is stored in a storage tank, and then filled into containers such as ISO (International Organization for Standardization) tank containers and canisters before being shipped and delivered as a product. Patent Document 4 describes sealing high-purity nitrogen gas in the container.

Isopropyl alcohol filled in containers such as ISO tank containers and canisters may take several tens of days to several months to be used as a cleaning liquid or drying liquid in the manufacturing process of semiconductor devices. As a result of the inventors' investigations, it was found that even when isopropyl alcohol with a low dissolved oxygen concentration produced by the above method is filled into a container and sealed with nitrogen gas with a low oxygen concentration, when the isopropyl alcohol in the container is analyzed after an interval of several tens of days to several months, the content of metal impurities and organic impurities such as acetone increases, and it may be unusable for semiconductor cleaning applications.

Therefore, the objective of the present disclosure is to provide an isopropyl alcohol container in which the increase in the content of metal impurities and organic impurities such as acetone is suppressed even after long-term storage, and a method for manufacturing the same.

The present inventors have conducted intensive research to solve the above problems. First, when a container with a high content of metal impurities and organic impurities such as acetone was checked, it was found that even if the container was filled with isopropyl alcohol supplied from the same storage tank and sealed using the same nitrogen gas, the content of metal impurities and organic impurities such as acetone may be high. The dissolved oxygen concentration in the lot of isopropyl alcohol used at that time and the oxygen concentration of the nitrogen gas used for sealing were also checked, but neither of them were problematic oxygen concentrations. It was also confirmed that the increase in the content of metal impurities and organic impurities such as acetone in isopropyl alcohol may be suppressed even if the same container is filled with isopropyl alcohol with the same dissolved oxygen concentration, sealed using nitrogen gas with the same oxygen concentration, and stored for a long period of time. From these findings, it was confirmed that there was no damage to the container used. On the other hand, when a container with a high content of organic impurities such as metal impurities and acetone was checked, it was found that the oxygen concentration in the gas phase of the container and the content of chromium in the isopropyl alcohol were high.

From these findings, it was speculated that the increase in the content of organic impurities such as acetone and chromium during long-term storage was caused by some reason that the oxygen concentration increased immediately after filling, and the oxygen in the container increased the content of organic impurities such as acetone and chromium during long-term storage. It was then discovered that the increase over time in the content of organic impurities such as acetone during long-term storage can be suppressed by keeping the oxygen concentration of the gas in the container below a predetermined concentration after filling it with isopropyl alcohol and sealing in an inert gas such as nitrogen, and this led to the completion of the present invention.

Specific means for solving the above problems include the following embodiments.
<1> An isopropyl alcohol container in which isopropyl alcohol is contained in a container,
The oxygen content in the container is 0.001 to 0.100 mol ppm relative to the isopropyl alcohol;
The isopropyl alcohol container, in which the content of acetone as an impurity in the isopropyl alcohol is 10 to 200 ppb by mass.

<2> An isopropyl alcohol container described in <1>, in which the content of chromium as an impurity in the isopropyl alcohol is 0.01 to 2.50 ppt by mass.

<3> An isopropyl alcohol container described in <1> or <2>, wherein the volume of the container is in the range of 1,000 to 1,500,000 L.

<4> An isopropyl alcohol container described in <3>, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

<5> A method for producing an isopropyl alcohol container in which isopropyl alcohol is contained in a container, comprising:
A method for producing an isopropyl alcohol container, comprising: storing isopropyl alcohol in the container; and adjusting the oxygen concentration of the gas in the container to 0.1 to 10 ppm on a volume basis.

<6> A method for manufacturing an isopropyl alcohol container described in <5>, wherein the dissolved oxygen concentration in the isopropyl alcohol contained in the container is 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C under atmospheric conditions.

<7> A method for producing an isopropyl alcohol container described in <5> or <6>, wherein the content of acetone as an impurity in the isopropyl alcohol contained in the container is 10 to 200 ppb by mass.

<8> A method for manufacturing an isopropyl alcohol container described in any one of <5> to <7>, wherein the content of chromium as an impurity in the isopropyl alcohol contained in the container is 0.01 to 2.50 ppt by mass.

<9> A method for producing an isopropyl alcohol container described in any one of <5> to <8>, wherein the volume of the container is in the range of 1,000 to 1,500,000 L.

<10> A method for manufacturing an isopropyl alcohol container described in <9>, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

<11> A method for producing an isopropyl alcohol container in which isopropyl alcohol is contained in a container, comprising:
The isopropyl alcohol is contained in the container so that the volume of the container is 2 to 98%, and the oxygen concentration of the gas in the container is adjusted to 0.1 to 10 ppm on a volume basis.

<12> A method for manufacturing an isopropyl alcohol container described in <11>, wherein the dissolved oxygen concentration in the isopropyl alcohol contained in the container is 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C under atmospheric conditions.

<13> A method for producing an isopropyl alcohol container described in <11> or <12>, wherein the content of acetone as an impurity in the isopropyl alcohol contained in the container is 10 to 200 ppb by mass.

<14> A method for manufacturing an isopropyl alcohol container described in any one of <11> to <13>, wherein the content of chromium as an impurity in the isopropyl alcohol contained in the container is 0.01 to 2.50 ppt by mass.

<15> A method for producing an isopropyl alcohol container described in any one of <11> to <14>, wherein the volume of the container is in the range of 1,000 to 1,500,000 L.

<16> A method for producing an isopropyl alcohol container described in <15>, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

<17> A method for producing an isopropyl alcohol container in which isopropyl alcohol contained in a first container is contained in a second container, comprising:
A method for producing an isopropyl alcohol container, comprising: storing isopropyl alcohol in the second container; and adjusting the oxygen concentration of the gas in the second container to 0.1 to 10 ppm on a volumetric basis.

<18> A method for manufacturing an isopropyl alcohol container described in <17>, wherein the dissolved oxygen concentration in the isopropyl alcohol contained in the second container is 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C under atmospheric conditions.

<19> A method for producing an isopropyl alcohol container described in <17> or <18>, wherein the content of acetone as an impurity in the isopropyl alcohol contained in the second container is 10 to 200 ppb by mass.

<20> A method for manufacturing an isopropyl alcohol container described in any one of <17> to <19>, wherein the content of chromium as an impurity in the isopropyl alcohol contained in the second container is 0.01 to 2.50 ppt by mass.

<21> The method for producing an isopropyl alcohol container according to any one of <17> to <20>, wherein the first container and the second container have a volume in the range of 1000 to 1500000 L.

<22> The method for producing an isopropyl alcohol container according to <21>, wherein the first container and the second container are an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

<23> A quality control method for an isopropyl alcohol container in which isopropyl alcohol is contained in a container, comprising:
The quality control method for an isopropyl alcohol container, in which the dissolved oxygen concentration in the isopropyl alcohol is 0.001 to 0.050% relative to the oxygen saturation solubility at 25 ° C. in the atmosphere, and the oxygen concentration of the gas in the container is 0.1 to 10 ppm by volume.

According to the present disclosure, it is possible to provide an isopropyl alcohol container capable of suppressing an increase in the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage. In particular, the manufacturing method of the present disclosure can be applied to the case where isopropyl alcohol is stored in a container with a large internal volume such as an ISO tank container or a storage tank. The isopropyl alcohol container of the present disclosure can be stored for a long period of time, for several tens of days to several months, and the stored isopropyl alcohol can be suitably used as a cleaning liquid or drying liquid for semiconductor devices, and has high industrial applicability.

In this specification, unless otherwise specified, the notation "A-B" using numerical values A and B means "greater than or equal to A and less than or equal to B." In such notations, when a unit is assigned only to numerical value B, the unit is also applied to numerical value A.

In the following description, unless otherwise specified, the concentrations "%", "ppm", "ppb", and "ppt" are all based on mass, including in the examples. In addition, the concentrations "vol%" and "volppm" are all based on volume fraction, including in the examples, and "molppm" is all based on molar fraction.

<Isopropyl alcohol container>
The isopropyl alcohol container (hereinafter also simply referred to as "container") of the present disclosure is a container in which isopropyl alcohol is contained, characterized in that the oxygen content in the container is 0.001 to 0.100 mol ppm relative to the isopropyl alcohol, and the content of acetone as an impurity in the isopropyl alcohol is 10 to 200 ppb. The inside of the container is composed of a portion filled with isopropyl alcohol (hereinafter also referred to as the "liquid phase portion") and a space portion not filled with isopropyl alcohol (hereinafter also referred to as the "gas phase portion").

By using such a container, the increase in the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage is suppressed, making it possible to store the material for a long period of time, from several tens of days to several months. The reason for this is not entirely clear, but the inventors speculate as follows.

When oxygen is present in isopropyl alcohol, it reacts with the isopropyl alcohol, producing acetone as a by-product. For this reason, it was thought that filling a container with isopropyl alcohol with a low concentration of dissolved oxygen and sealing in an inert gas such as nitrogen gas would suppress the increase in the content of organic impurities such as acetone in the isopropyl alcohol in the container. However, if there is a very small gap in the piping for transferring the liquid from the storage tank to the container or the piping for sealing in the nitrogen gas, a very small amount of oxygen may be mixed in. In addition, containers such as ISO tank containers are often returned after the isopropyl alcohol inside is consumed, and the same container is filled with isopropyl alcohol and reshipped. Usually, the container is thoroughly washed before filling with isopropyl alcohol, but it is thought that oxygen may remain in the container due to the washing at that time.

In such a case, even if the container is filled with isopropyl alcohol with a low dissolved oxygen concentration and an inert gas such as nitrogen gas is sealed in, a relatively large amount of oxygen will be present in the container. Since a certain amount of oxygen dissolves in isopropyl alcohol, it is presumed that when the dissolved oxygen reacts with isopropyl alcohol and is consumed, the oxygen in the gas phase in the container dissolves in isopropyl alcohol and reacts with isopropyl alcohol. Then, the reaction between oxygen and isopropyl alcohol produces hydrogen peroxide as a by-product in addition to acetone, and the hydrogen peroxide also reacts with isopropyl alcohol. For this reason, it is presumed that the content of organic impurities such as acetone will increase until the oxygen in the container is almost consumed due to long-term storage. In addition, the inside of a container such as an ISO tank container is made of stainless steel, and stainless steel usually contains chromium. It is presumed that the chromium contained in the stainless steel will be dissolved, albeit in very small amounts, due to the influence of the oxygen in the container and the by-product hydrogen peroxide, and the content of chromium in the isopropyl alcohol will also increase. It is speculated that the chromium dissolved in the isopropyl alcohol acts as a catalyst when oxygen reacts with isopropyl alcohol, and that this promotes an increase in the content of organic impurities such as acetone during storage.

Therefore, by storing isopropyl alcohol in a container and filling the gas phase with an inert gas such as nitrogen gas, the oxygen content in the container is set within a specified range, and it is presumed that the increase in the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage can be suppressed, and the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage can be controlled, making it possible to store the alcohol for long periods of time ranging from several tens of days to several months.

(Oxygen content in container)
In the container of the present disclosure, the oxygen content in the container needs to be 0.001 to 0.100 mol ppm relative to isopropyl alcohol. From the viewpoint of the effect of suppressing the increase in the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage, the oxygen content in the container is preferably 0.001 to 0.050 mol ppm relative to isopropyl alcohol, and more preferably 0.001 to 0.010 mol ppm.

The oxygen content in the container can be determined by measuring the amount of oxygen in the gas phase of the container and the amount of oxygen dissolved in the isopropyl alcohol in the liquid phase and calculating the total amount. The oxygen content can then be calculated as a molar fraction relative to isopropyl alcohol from the calculated oxygen content and the amount of isopropyl alcohol in the container.

Here, the amount of oxygen in the gas phase can be calculated by sampling the gas phase, measuring the amount of oxygen in the sample using a known oxygen analysis method, and then calculating the amount of oxygen in the sample and the volume and internal pressure of the gas phase of the container. Known oxygen analysis methods include gas chromatography (GC) using a pulse discharge photoionization detector, polarographic methods, and optical oxygen analysis (analysis methods that utilize the luminescence and quenching phenomena of fluorescent substances).

In addition, the amount of dissolved oxygen in the isopropyl alcohol in the liquid phase can be calculated by sampling the isopropyl alcohol in the liquid phase and measuring the amount of oxygen in the sample using a polarographic method or optical oxygen analysis method (an analytical method that utilizes the luminescence and quenching phenomena of fluorescent substances), and then calculating the amount of dissolved oxygen in the sample from the amount of dissolved oxygen in the sample and the volume of isopropyl alcohol in the container.

(Acetone content as an impurity in isopropyl alcohol)
In the container of the present disclosure, the content of acetone as an impurity in isopropyl alcohol is 10 to 200 ppb. By setting the content of acetone in isopropyl alcohol to the above range, the contained isopropyl alcohol can be suitably used as a cleaning liquid or drying liquid for semiconductor devices. From the viewpoint of reducing the influence on the device when the contained isopropyl alcohol is used as a cleaning liquid or drying liquid for semiconductor devices, the content of acetone in isopropyl alcohol is preferably 10 to 200 ppb, more preferably 10 to 100 ppb.

Here, the acetone content in the isopropyl alcohol can be measured by sampling the isopropyl alcohol in the liquid phase of the container and then using gas chromatography-mass spectrometry (GC-MS).

(Chromium content as an impurity in isopropyl alcohol)
As described above, it is presumed that the chromium dissolved in isopropyl alcohol acts as a catalyst when oxygen reacts with isopropyl alcohol. From the viewpoint of suppressing the increase in the content of organic impurities such as acetone during long-term storage and controlling the content of organic impurities, the content of chromium in isopropyl alcohol is preferably 0.01 to 2.50 ppt, more preferably 0.01 to 1.00 ppt.

Here, the chromium content in the isopropyl alcohol can be measured by sampling the isopropyl alcohol in the liquid phase of the container and then using inductively coupled plasma mass spectrometry (ICP-MS).

(Isopropyl alcohol)
The isopropyl alcohol contained in the container is not particularly limited as long as it has the above-mentioned acetone content after being contained in the container. From the viewpoint of reducing the influence on the device when the contained isopropyl alcohol is used as a cleaning liquid or drying liquid for a semiconductor device, the purity of the isopropyl alcohol is preferably 99.99% or more, more preferably 99.9999% or more. In addition, from the viewpoint of the effect of suppressing the increase in the content of organic impurities such as acetone during long-term storage, it is preferable that the isopropyl alcohol satisfies the following conditions of dissolved oxygen concentration, acetone content, and chromium content.

The dissolved oxygen concentration in isopropyl alcohol is preferably 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C under atmospheric conditions, and more preferably 0.001 to 0.025%. The dissolved oxygen concentration in isopropyl alcohol can be determined by measuring the amount of dissolved oxygen in the liquid phase of the container using the method described above, measuring the oxygen partial pressure corresponding to the dissolved oxygen present in isopropyl alcohol at 25°C under atmospheric conditions, and dividing the measured oxygen partial pressure by the oxygen partial pressure at 25°C under atmospheric conditions and converting it to a percentage.

Here, "atmosphere" refers to an air composition at 1 atmosphere. The oxygen partial pressure at 25°C under atmosphere refers to the oxygen partial pressure in air at 25°C and 1 atmosphere, which is 21 kPa. In this disclosure, the oxygen saturation solubility at 25°C under atmosphere refers to the oxygen concentration when the dissolved oxygen is in equilibrium in an atmosphere at 1 atmosphere and with an oxygen partial pressure of 21 kPa.

The oxygen saturation solubility in isopropyl alcohol varies depending on the literature. For example, according to a reference (Sato Ten et al., "Solubility of Oxygen in Organic Solvents and Calculation of the Hansen Solubility Parameters of Oxygen", Industrial and Engineering Chemistry Research (Ind. Eng. Chem. Res.), 2014, Vol. 53, pp. 19831-19337), the oxygen saturation solubility in isopropyl alcohol at 25° C. under an atmosphere of oxygen partial pressure of 101.3 kPa is 7.78×10 ⁻⁴ mol/mol. When the dissolved oxygen concentration in isopropyl alcohol is 0.001 to 0.050% relative to the oxygen saturation solubility at 25° C. in the atmosphere, the dissolved oxygen concentration in isopropyl alcohol can be calculated to be 0.9 to 43.5 ppb.

The content of acetone contained as an impurity in isopropyl alcohol is preferably 10 to 200 ppb, and more preferably 10 to 100 ppb. The content of acetone in isopropyl alcohol can be measured by a method similar to the method for measuring acetone in the liquid phase of the container.

Of the metal impurities contained in isopropyl alcohol, the chromium content is preferably 0.01 to 2.50 ppt, and more preferably 0.01 to 1.00 ppt. The chromium content in isopropyl alcohol can be measured by a method similar to the method for measuring chromium in the liquid phase of the container.

The isopropyl alcohol contained in the container may be isopropyl alcohol obtained by a known manufacturing method. Known manufacturing methods include the acetone reduction method in which acetone is reduced, the Veba Chemie method, which is a gas-phase method of a fixed bed catalyst method, the Deutsche Texaco method, which is a gas-liquid mixed phase method of a fixed bed catalyst method, and the direct hydration method. Among these manufacturing methods, the direct hydration method is preferred because it can obtain high-purity isopropyl alcohol and is easy to purify.

As a purification method for the isopropyl alcohol obtained by the above method, a known method can be adopted. Specifically, a method of purifying isopropyl alcohol by distillation, a method of filtering isopropyl alcohol through a filter, a combination of these, etc. can be mentioned. When using it as a cleaning solution or drying solution for semiconductor devices, it is necessary to obtain isopropyl alcohol that is high in purity and does not contain fine particles, etc., and it is preferable to adopt a method of combining distillation and filtration as a purification method.

(Container of storage body)
As the container for containing isopropyl alcohol, a container known as a container for containing an organic chemical liquid can be used without any particular limitation. The volume of these containers is, for example, in the range of 10 to 1,500,000 L. Specific examples of such containers include canisters (volume: 18 to 200 L), intermediate bulk containers (IBCs) (volume: 1,000 to 2,000 L), tank trucks (volume: 2,000 to 4,000 L), ISO tank containers (volume: 13,000 to 26,000 L), and storage tanks (volume: 100,000 to 1,500,000 L). In particular, as the container of the present disclosure, a container having a volume in the range of 1,000 to 1,500,000 L (intermediate bulk containers, tank trucks, ISO tank containers, storage tanks, etc.) is preferable. In such a container with a large internal volume, oxygen often remains in the gas phase when an inert gas such as nitrogen gas is sealed in after isopropyl alcohol is filled in the container. In this regard, by controlling the oxygen content in the container within a predetermined range as in the present disclosure, an increase in the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage is suppressed, and the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage can be controlled, making it possible to store the product for a long period of time ranging from several tens of days to several months.

From the viewpoint of suppressing the increase of impurities in the isopropyl alcohol contained in the container, the material of the container in contact with the isopropyl alcohol is preferably at least one selected from the group consisting of resins (polyolefin resins, fluororesins, etc.), glass, and metals (stainless steel, Hastelloy, Inconel, Monel, etc.), and more preferably stainless steel. Examples of stainless steel include austenitic stainless steels such as SUS304 (Cr content: 18-20%, Ni content: 8-10.5%), SUS304L (Cr content: 18-20%, Ni content: 9-13%), SUS316 (Cr content: 16-18%, Ni content: 10-14%), and SUS316L (Cr content: 16-18%, Ni content: 12-15%).

As described above, it is presumed that the chromium dissolved in the isopropyl alcohol acts as a catalyst when oxygen reacts with the isopropyl alcohol. When stainless steel such as SUS304 is used as the material for the container, it is preferable to perform a passivation treatment to form a passive layer on the surface of the stainless steel in order to prevent metals such as chromium from dissolving into the isopropyl alcohol. By performing a passivation treatment on the part that comes into contact with the isopropyl alcohol, it is possible to prevent the content of metal impurities in the isopropyl alcohol from increasing during the storage, filling, or transportation process. A known method can be used for the passivation treatment.

The amount of isopropyl alcohol to be contained in the container may be determined appropriately taking into consideration the purpose of the container, etc. Taking into consideration the volatility of isopropyl alcohol and transportation costs, it is preferable to contain isopropyl alcohol in the range of 2 to 98% of the container's volume, and more preferably in the range of 80 to 98%.

<Method of Manufacturing Container>
The method for producing a container according to the present disclosure is characterized in that the oxygen concentration of the gas in the container when isopropyl alcohol is contained in the container is 0.1 to 10 volppm. This manufacturing method makes it possible to control the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage, and makes it possible to produce a container that can be stored for a long period of several tens of days to several months. From the viewpoint of controlling the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage, the oxygen concentration of the gas in the container when isopropyl alcohol is contained in the container is preferably 0.1 to 5 volppm, more preferably 0.1 to 1 volppm, and even more preferably 0.1 to 0.5 volppm.

In some cases, isopropyl alcohol is first stored in a storage tank (first container) and then stored in an ISO tank container or the like (second container). By carrying out the manufacturing method of the present disclosure described above when storing isopropyl alcohol in the second container, it is possible to control the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage of the isopropyl alcohol stored in the second container, making it possible to store the isopropyl alcohol for a long period of time, from several tens of days to several months.

Below, as an example of the manufacturing method of the present disclosure, we will explain a method in which isopropyl alcohol that has undergone a purification process is stored in a storage tank, and the stored isopropyl alcohol is further stored in an ISO tank container.

(Storage of isopropyl alcohol in a storage tank)
In the manufacturing method of the present disclosure, a liquid delivery line for delivering isopropyl alcohol from the refining process to the storage tank and a gas supply line for supplying an inert gas to the storage tank are connected to the storage tank. Isopropyl alcohol is stored in the storage tank via the liquid delivery line, and the inert gas is sealed in the storage tank via the gas supply line.

As the inert gas, a stable inert gas such as nitrogen gas or argon gas can be used, and it is preferable to use nitrogen gas because high-purity inert gas is available industrially at low cost. The purity of the inert gas is preferably 99.999% or more. The oxygen concentration in the inert gas is preferably 5 volppm or less, more preferably 0.5 volppm or less, and even more preferably 0.1 volppm or less.

In the manufacturing method of the present disclosure, from the viewpoint of suppressing the increase of impurities in isopropyl alcohol, it is preferable that the material of the transfer pipe used in the liquid delivery line and the gas supply line is the same as the material of the container described above. Specifically, it is preferable that it is stainless steel or fluororesin (PFA, PTFE, etc.). Examples of stainless steel include SUS304, SUS304L, SUS316, SUS316L, etc. The stainless steel can be subjected to a passivation treatment as described above.

Before initially pumping isopropyl alcohol into the storage tank, it is preferable to replace the gas phase in the storage tank with an inert gas, measure the oxygen concentration in the inert gas when the tank is filled with inert gas, and confirm that the oxygen concentration is 0.1 to 10 vol ppm before placing the isopropyl alcohol into the storage tank.

When isopropyl alcohol is stored in a storage tank via a liquid delivery line, the dissolved oxygen concentration, acetone content, and chromium content in the isopropyl alcohol are preferably within the same preferred ranges as the dissolved oxygen concentration of the isopropyl alcohol in the container described above.

The amount of isopropyl alcohol contained in the storage tank is preferably 2-98% of the volume.

Next, an inert gas is sealed in the gas phase of the storage tank containing the isopropyl alcohol. The internal pressure of the gas phase of the storage tank after the inert gas is sealed is not particularly limited, but is preferably 0.0001 to 0.30 MPa.

After the inert gas is sealed in, the gas phase in the storage tank is sampled to measure the oxygen concentration. If the oxygen concentration is 0.1 to 10 vol ppm, the container of the present disclosure can be produced. If the oxygen concentration in the gas phase is not within the above range, the container of the present disclosure can be produced by supplying an inert gas to replace the gas phase until the oxygen concentration in the gas phase falls within the above range. Alternatively, the container of the present disclosure can be produced by discharging the stored isopropyl alcohol, cleaning the inside of the storage tank, checking the airtightness of the piping (liquid delivery line, gas supply line, and other equipment), and storing isopropyl alcohol again.

The temperature at which isopropyl alcohol is stored in the container is not particularly limited, but it is usually set appropriately within the range of -20 to 50°C from the viewpoint of preventing an increase in the impurity content during long-term storage.

(Storage of isopropyl alcohol in a storage tank into an ISO tank container)
Next, a method for producing the container of the present disclosure by storing isopropyl alcohol in a storage tank into an ISO tank container will be described.

As an ISO tank container, a used ISO tank container may be reused. In such a case, it is preferable to co-wash the ISO tank container with isopropyl alcohol before storing isopropyl alcohol.

Normally, the storage tank and the ISO tank container are not connected and are independent of each other. Therefore, in order to transfer isopropyl alcohol from the storage tank to the ISO tank container, a transfer line for transferring the isopropyl alcohol in the storage tank and a transfer pipe for a gas supply line for supplying inert gas to the ISO tank container are connected to the ISO tank container.

A known method can be used to connect the ISO tank container to the transfer pipes of the liquid delivery line and the gas supply line. The ISO tank container is provided with fittings for connecting to the transfer pipes of the liquid delivery line and the gas supply line. Fittings provided on the transfer pipes of the liquid delivery line and the gas supply line are connected to the fittings provided on the ISO tank container. Types of fittings include lever-type fittings and quick fluid fittings. Flexible hoses may be used for the liquid delivery line and the gas supply line.

One of the reasons for the increase in the oxygen concentration of isopropyl alcohol filled in an ISO tank container is that when connecting the fittings on the ISO tank container to the fittings on the transfer pipes of the liquid delivery line and gas supply line, or when the fittings are not sealed and there are gaps, air may get mixed into the line and oxygen may dissolve in the isopropyl alcohol in the container. Therefore, it is preferable to provide a vent exhaust line in the gas supply line, purge the line by pressurizing with an inert gas, and sufficiently replace the atmosphere in the gas supply line and ISO tank container until the oxygen concentration reaches a predetermined range.

Before filling the ISO tank container with isopropyl alcohol, it is preferable to discharge the remaining isopropyl alcohol in the ISO tank container outside the ISO tank container by pressurizing it with inert gas from the gas supply line.

Then, the isopropyl alcohol in the storage tank is pumped into the ISO tank container via the liquid supply line. At this time, the amount of isopropyl alcohol contained in the ISO tank container is preferably 2 to 98% of the volume.

Next, an inert gas is sealed in the gas phase inside the ISO tank container filled with isopropyl alcohol. After the inert gas is sealed in, the internal pressure of the gas phase inside the ISO tank container is preferably 0.01 to 0.30 MPa, more preferably 0.02 to 0.12 MPa, and even more preferably 0.02 to 0.07 MPa.

After the inert gas is sealed in, the gas phase in the ISO tank container is sampled to measure the oxygen concentration. If the oxygen concentration is 0.1 to 10 vol ppm, the container of the present disclosure can be obtained. If the oxygen concentration in the gas phase is not within the above range, the container of the present disclosure can be produced by supplying an inert gas to replace the gas phase until the oxygen concentration in the gas phase is within the above range. Alternatively, the container of the present disclosure can be produced by discharging the isopropyl alcohol contained therein, cleaning the inside of the ISO tank container, checking the airtightness of the piping (liquid transfer line, gas supply line, and other equipment), and re-accommodating the isopropyl alcohol. The discharged isopropyl alcohol is analyzed for its dissolved oxygen concentration, acetone content, and chromium content. If all of these are within the preferred ranges, it can be used as isopropyl alcohol to be accommodated in the ISO tank container again. On the other hand, if the oxygen concentration is not within the preferred range, it can be purified by a known purification method and then used as isopropyl alcohol to be accommodated in the ISO tank container.

The above describes a method for transferring isopropyl alcohol from a storage tank to an ISO tank container, but the manufacturing method disclosed herein is not limited to these aspects, and it is also possible to use a canister or the like as a container.

Co-washing of canisters can be carried out by the following procedure. That is, co-washing is carried out by filling the container with isopropyl alcohol from the liquid supply line so that it accounts for 1-10% of the container's volume, and after co-washing, the remaining isopropyl alcohol in the container is discharged from the container by pressurizing it with inert gas from the gas supply line. Co-washing may be carried out multiple times, not just once.

In addition, the co-washing cleaning of intermediate bulk containers, tank trucks, and ISO tank containers can be performed in the following procedure. First, pure water passed through a filter is supplied into the container, and the container is filled with pure water until it overflows, and then the pure water is washed. After leaving it for 15 minutes, the pure water in the container is discharged from the container by pressurizing the inert gas from the gas supply line. The container is filled with isopropyl alcohol from the liquid supply line to 1 to 10% of the volume, and after the co-washing, the remaining isopropyl alcohol in the container is discharged from the container by pressurizing the inert gas from the gas supply line. The co-washing cleaning may be performed multiple times, not just once. However, if the container is filled with only isopropyl alcohol and sealed with inert gas after the co-washing cleaning of the container multiple times, the pure water cleaning and co-washing cleaning of the container are not necessarily performed.

<Quality control method for container>
As described above, if oxygen is present in the gas phase of the container, it is presumed that the content of metal impurities such as chromium and organic impurities such as acetone will increase until the oxygen in the container is almost consumed due to long-term storage. Therefore, by measuring the oxygen concentration in the gas phase of the container and the dissolved oxygen concentration in the isopropyl alcohol in the liquid phase and managing them to be within a predetermined range, the increase in the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage is suppressed, and the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage can be controlled, making it possible to store the container for a long period of time from several tens of days to several months.

If the oxygen concentration in the gas phase of the container is not within the range of 0.1 to 10 vol ppm, or if the dissolved oxygen concentration in the isopropyl alcohol in the liquid phase is not within the range of 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C in air, the following quality control method is performed. First, the isopropyl alcohol in the container is discharged and the container is purged with an inert gas. At that time, it is confirmed that there are no leaks in the joint between the container and the transfer tube. Next, the oxygen concentration in the gas phase of the container is measured to confirm that the oxygen concentration is within the range of 0.1 to 10 vol ppm, and then the container is filled again with isopropyl alcohol purified by the above method. After filling, the oxygen concentration in the gas phase of the container is measured to confirm that the oxygen concentration is within the range of 0.1 to 10 vol ppm, and the dissolved oxygen concentration in the isopropyl alcohol in the container is measured to confirm that the dissolved oxygen concentration is within the range of 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C in air.

By the above procedure, the oxygen concentration of the isopropyl alcohol container can be controlled. The container can suppress an increase in the organic impurities and chromium content in the isopropyl alcohol even during storage or transportation. The isopropyl alcohol in the container can be stored for a long period of time and can be suitably used as a cleaning liquid or drying liquid for semiconductor devices.

In addition, the isopropyl alcohol in the container can suppress the increase in the content of organic impurities, including not only acetone but also organic acids.

The present invention will be described in detail below using examples, but the present invention is not limited to these examples.

<Oxygen content in isopropyl alcohol container>
The oxygen content of the gas phase of the isopropyl alcohol container was calculated as follows. First, an optical oxygen concentration meter (PreSens, Fibox 4 trace (sensor: Pst6)) was used to measure nitrogen with a purity of 99.999% or more and an oxygen concentration of 1 volppm or less, and nitrogen with an oxygen concentration adjusted to 1000 volppm, and was calibrated in advance. Next, the value of the internal pressure of the gas phase of the container was confirmed from the pressure gauge installed in the container, and the gas phase of the container was pumped to the optical oxygen concentration meter by the internal pressure of the gas phase of the container, and purging was performed for 1 minute, and the oxygen concentration of the gas phase of the container was measured. Finally, the amount of oxygen in the gas phase of the container was calculated from the formula (oxygen concentration of the gas phase of the container x (atmospheric pressure + internal pressure) ÷ atmospheric pressure x molar volume of gas x volume of gas phase).

The amount of oxygen in the liquid phase of the container was calculated as follows. First, an optical oxygen concentration meter (PreSens, Fibox 4 trace (sensor: Pst6)) was used to measure nitrogen with a purity of 99.999% or more and an oxygen concentration of 1 volppm or less, and nitrogen with an oxygen concentration adjusted to 1000 volppm, and calibration was performed in advance. Next, the liquid phase of the container was pumped to the optical oxygen concentration meter by the internal pressure of the gas phase of the container, purging was performed for 1 minute, and the oxygen concentration of the liquid phase of the container was measured. Finally, the amount of oxygen in the liquid phase of the container was calculated from the formula (oxygen concentration in the liquid phase of the container ÷ molar mass of oxygen × weight of the liquid phase).

The oxygen content in the container was determined as the sum of the oxygen amounts in the gas phase and liquid phase of the container. The molar fraction of the oxygen content in the container relative to isopropyl alcohol was calculated using the formula (oxygen content in container ÷ weight of liquid phase × molar mass of isopropyl alcohol).

<Acetone content in isopropyl alcohol container>
The acetone content in the isopropyl alcohol container was measured using GC-MS (gas chromatography-mass spectrometry) with the selected ion detection method (SIM) under the measurement conditions shown below. A calibration curve for the acetone content under the same measurement conditions was created in advance, and the acetone content in the measured sample was determined based on the calibration curve, and converted into the amount of isopropyl alcohol in the container to determine the acetone content in the isopropyl alcohol container.
-Measurement condition-
Apparatus: GCMS-QP2010 Ultra (Shimadzu Corporation)
Column: CP-WAX 52CB (60 m x 0.25 mm, 0.50 μm)
Carrier gas: Helium Carrier gas flow rate: 0.98 mL/min Injection port temperature: 150° C.
Column temperature: 75 ° C.
Detector temperature: 230°C
Injection mode: split method Split ratio: 1:10
SIM mode set ion: m/Z=43

<Chromium content in isopropyl alcohol container>
Metal impurities contained in isopropyl alcohol were quantified using ICP-MS (inductively coupled plasma mass spectrometry) as follows. Approximately 500 mL of isopropyl alcohol was collected in an eggplant-shaped flask, concentrated and dried using a rotary evaporator, and then collected in two portions using approximately 25 mL of 0.1 N nitric acid. The amount of metal elution from the collected 0.1 N nitric acid solution was quantified using ICP-MS (Agilent Technologies, Agilent 8900). At this time, the concentration factor was calculated from the ratio of the weight of isopropyl alcohol before concentration to the weight of the 0.1 N nitric acid solution after collection, and converted into the amount of metal impurities per weight of isopropyl alcohol.

Example 1
The isopropyl alcohol that had undergone the purification process was accommodated in the storage tank by the following method. First, before the isopropyl alcohol was sent to the storage tank, the inside of the storage tank was subjected to gas-phase substitution with nitrogen through a gas supply line. The purity of the nitrogen used at this time was 99.999% or more, and the oxygen concentration was 5 volppm or less. After the gas-phase substitution, the oxygen content in the container was measured, and the oxygen concentration in the gas phase part in the storage tank was 1 volppm or less. Next, the isopropyl alcohol that had undergone the purification process was accommodated in the storage tank through a liquid sending line. The amount of isopropyl alcohol accommodated in the storage tank was 80% of the internal volume. Next, nitrogen was sealed in the gas phase part of the storage tank containing the isopropyl alcohol through a gas supply line. The internal pressure of the gas phase part in the storage tank after nitrogen sealing was 0.0005 MPa.

Nitrogen was sealed in the gas phase of the storage tank to create an isopropyl alcohol container, and the oxygen content in the container was measured. The oxygen concentration in the gas phase of the container was 1.0 vol ppm, the dissolved oxygen concentration of the isopropyl alcohol in the container was 0.024% relative to the oxygen saturation solubility at 25°C in the atmosphere, and the molar fraction of the oxygen content in the container relative to the isopropyl alcohol was 0.040 mol ppm. The acetone content in the container was 10 ppb, and the chromium content was 0.19 ppt.

The container thus manufactured was stored for 30 days at a temperature range of 15 to 30°C. After storage, the oxygen content in the container was measured, and the oxygen concentration in the gas phase of the container was 0.7 volppm, the dissolved oxygen concentration of the isopropyl alcohol in the container was 0.016% relative to the oxygen saturation solubility at 25°C in the atmosphere, and the molar fraction of the oxygen content in the container relative to the isopropyl alcohol was 0.027 molppm. The acetone content in the container was 46 ppb, and the chromium content was 0.64 ppt.

<Comparative Example 1>
The isopropyl alcohol that had undergone the purification process was accommodated in the storage tank by the following method. First, the isopropyl alcohol that had undergone the purification process was accommodated in the storage tank through a liquid transfer line. The amount of isopropyl alcohol accommodated in the storage tank was 80% of the internal volume. Next, nitrogen was sealed in the gas phase of the storage tank containing isopropyl alcohol through a gas supply line. The purity of the nitrogen used at this time was 99.999% or more, and the oxygen concentration was 5 vol ppm or less. The internal pressure of the gas phase of the storage tank after nitrogen sealing was 0.0005 MPa.

The container thus manufactured was stored for 51 days at a temperature range of 15 to 30° C. The storage conditions of the container are shown in Table 1, and the oxygen content, acetone content, and chromium content in the container before and after storage are shown in Table 2.

Example 2
The isopropyl alcohol in the storage tank was accommodated in the ISO tank container by the following method. First, the joints provided on the liquid supply line connected to the storage tank and the transfer pipe of the gas supply line were connected to the joints of the ISO tank container. The inside of the line was purged for 5 minutes by applying nitrogen pressure to the exhaust line for venting in the gas supply line. The purity of the nitrogen used at this time was 99.999% or more, and the oxygen concentration was 5 volppm or less. It was also confirmed that there was no leakage in the joints of the transfer pipe. After the gas phase substitution, it was confirmed that the oxygen concentration in the gas supply line was 1 volppm or less. Next, before the isopropyl alcohol was delivered to the ISO tank container, the remaining liquid of isopropyl alcohol in the ISO tank container was discharged outside the ISO tank container by applying nitrogen pressure from the gas supply line. After the isopropyl alcohol was discharged, it was confirmed that the oxygen concentration in the gas phase part in the ISO tank container was 1 volppm or less. Next, the isopropyl alcohol in the storage tank was accommodated in the ISO tank container via the liquid supply line. The amount of isopropyl alcohol contained in the ISO tank container was 87% of the internal volume. Next, nitrogen was sealed into the gas phase of the ISO tank container containing isopropyl alcohol through a gas supply line. The internal pressure of the gas phase of the ISO tank container after nitrogen sealing was 0.07 MPa.

The containers thus manufactured were stored for 20 days at a temperature range of 15 to 30° C. The storage conditions of the containers are shown in Table 1, and the oxygen content, acetone content, and chromium content in the containers before and after storage are shown in Table 2.

<Comparative Example 2>
The isopropyl alcohol in the storage tank was accommodated in the ISO tank container by the following method. First, the joints provided on the liquid transfer line connected to the storage tank and the transfer pipe of the gas supply line were connected to the joints of the ISO tank container. However, purging of the lines by nitrogen pressure was not performed. Next, before the isopropyl alcohol was transferred to the ISO tank container, the remaining liquid of isopropyl alcohol in the ISO tank container was discharged outside the ISO tank container for 1 minute by nitrogen pressure from the gas supply line. The purity of the nitrogen used at this time was 99.999% or more, and the oxygen concentration was 5 vol ppm or less. Next, the isopropyl alcohol in the storage tank was accommodated in the ISO tank container via the liquid transfer line. The amount of isopropyl alcohol accommodated in the ISO tank container was 87% of the internal volume. Next, nitrogen was sealed in the gas phase part of the ISO tank container containing isopropyl alcohol via the gas supply line. The internal pressure of the gas phase part of the ISO tank container after nitrogen sealing was 0.06 MPa.

The containers thus manufactured were stored for 21 days at a temperature range of 15 to 30° C. The storage conditions of the containers are shown in Table 1, and the oxygen content, acetone content, and chromium content in the containers before and after storage are shown in Table 2.

Example 3
The isopropyl alcohol in the storage tank was accommodated in the canister can by the following method. First, the joints provided on the liquid supply line connected to the storage tank and the transfer pipe of the gas supply line were connected to the joints of the canister can. The canister can was filled with isopropyl alcohol through the liquid supply line so that the volume was 1 to 10% to perform co-washing. After the co-washing, the remaining liquid of isopropyl alcohol in the canister was discharged outside the container by nitrogen pressure from the gas supply line. The co-washing was performed three times. The purity of the nitrogen used at this time was 99.999% or more, and the oxygen concentration was 5 vol ppm or less. It was also confirmed that there was no leakage in the joints of the transfer pipe. After the co-washing, it was confirmed that the oxygen concentration in the canister was 1 vol ppm or less. Next, the isopropyl alcohol in the storage tank was accommodated in the canister can by the liquid supply line. The amount of isopropyl alcohol accommodated in the canister can was 82% of the internal volume. Next, nitrogen was sealed into the gas phase of the canister containing the isopropyl alcohol via a gas supply line. The internal pressure of the gas phase in the canister after the nitrogen sealing was 0.20 MPa.

The container thus manufactured was stored for 59 days at a temperature range of 15 to 30° C. The storage conditions of the container are shown in Table 1, and the oxygen content, acetone content, and chromium content in the container before and after storage are shown in Table 2.

<Comparative Example 3>
The isopropyl alcohol in the storage tank was accommodated in the canister can by the following method. First, the joints provided on the liquid supply line connected to the storage tank and the transfer pipe of the gas supply line were connected to the joints of the canister can. The canister can was filled with isopropyl alcohol through the liquid supply line so that the volume was 1 to 10% to perform co-washing. After the co-washing, the remaining liquid of isopropyl alcohol in the canister was discharged outside the container by nitrogen pressure from the gas supply line. The co-washing was performed three times. The purity of the nitrogen used at this time was 99.999% or more, and the oxygen concentration was 5 vol ppm or less. It was also confirmed that there was no leakage in the joints of the transfer pipe. After the co-washing, it was confirmed that the oxygen concentration in the canister was 1 vol ppm or less. Next, the isopropyl alcohol in the storage tank was accommodated in the canister can by the liquid supply line. The amount of isopropyl alcohol accommodated in the canister can was 82% of the internal volume. Next, nitrogen was sealed into the gas phase of the canister containing isopropyl alcohol through a gas supply line, and the internal pressure in the canister was set to 0.05 MPa. Further, nitrogen with an oxygen concentration of 1000 vol ppm was sealed in, and the internal pressure in the gas phase of the canister after the nitrogen sealing was set to 0.20 MPa.

The container thus manufactured was stored for 59 days at a temperature range of 15 to 30° C. The storage conditions of the container are shown in Table 1, and the oxygen content, acetone content, and chromium content in the container before and after storage are shown in Table 2.

Example 4
The isopropyl alcohol in the storage tank was accommodated in the ISO tank container by the following method. First, the joints provided on the liquid supply line connected to the storage tank and the transfer pipe of the gas supply line were connected to the joints of the ISO tank container. The line was purged for 5 minutes by applying nitrogen pressure to the exhaust line for venting in the gas supply line. The purity of the nitrogen used at this time was 99.999% or more, and the oxygen concentration was 5 volppm or less. It was also confirmed that there was no leakage in the joints of the transfer pipe. After the gas phase substitution, it was confirmed that the oxygen concentration in the gas supply line was 1 volppm or less. Next, before the isopropyl alcohol was delivered to the ISO tank container, the remaining liquid of isopropyl alcohol in the ISO tank container was discharged outside the ISO tank container by applying nitrogen pressure from the gas supply line. After the isopropyl alcohol was discharged, it was confirmed that the oxygen concentration in the gas phase part in the ISO tank container was 1 volppm or less. Next, the isopropyl alcohol in the storage tank was accommodated in the ISO tank container via the liquid supply line. The amount of isopropyl alcohol contained in the ISO tank container was 87% of the internal volume. Next, nitrogen was sealed into the gas phase of the ISO tank container containing isopropyl alcohol through a gas supply line. The internal pressure of the gas phase of the ISO tank container after nitrogen sealing was 0.05 MPa.

The containers thus manufactured were stored for 98 days at temperatures ranging from 15 to 30° C. The storage conditions for the containers are shown in Table 1, and the oxygen content, acetone content, and chromium content in the containers before and after storage are shown in Table 2.

Example 5
The isopropyl alcohol in the storage tank was accommodated in the ISO tank container by the following method. First, the joints provided on the liquid supply line connected to the storage tank and the transfer pipe of the gas supply line were connected to the joints of the ISO tank container. The inside of the line was purged for 5 minutes by applying nitrogen pressure to the exhaust line for venting in the gas supply line. The purity of the nitrogen used at this time was 99.999% or more, and the oxygen concentration was 5 volppm or less. It was also confirmed that there was no leakage in the joints of the transfer pipe. After the gas phase substitution, it was confirmed that the oxygen concentration in the gas supply line was 5 volppm or less. Next, before the isopropyl alcohol was delivered to the ISO tank container, the remaining liquid of isopropyl alcohol in the ISO tank container was discharged outside the ISO tank container by applying nitrogen pressure from the gas supply line. After the isopropyl alcohol was discharged, it was confirmed that the oxygen concentration in the gas phase part in the ISO tank container was 5 volppm or less. Next, the isopropyl alcohol in the storage tank was accommodated in the ISO tank container via the liquid supply line. The amount of isopropyl alcohol contained in the ISO tank container was 87% of the internal volume. Next, nitrogen was sealed into the gas phase of the ISO tank container containing isopropyl alcohol through a gas supply line. The internal pressure of the gas phase of the ISO tank container after nitrogen sealing was 0.05 MPa.

The containers thus manufactured were stored for 35 days at a temperature range of 15 to 30° C. The storage conditions of the containers are shown in Table 1, and the oxygen content, acetone content, and chromium content in the containers before and after storage are shown in Table 2.

As shown in Table 2, the containers of Examples 1 to 5, in which the oxygen content in the container was 0.001 to 0.100 mol ppm relative to isopropyl alcohol and the content of acetone as an impurity in isopropyl alcohol was 10 to 200 ppb by mass, showed a suppressed increase in the acetone content and chromium content after long-term storage of several tens of days to several months, compared to the containers of Comparative Examples 1 to 3.

Claims (23)

An isopropyl alcohol container in which isopropyl alcohol is contained in a container,
The oxygen content in the container is 0.001 to 0.100 mol ppm relative to the isopropyl alcohol;
The isopropyl alcohol container, in which the content of acetone as an impurity in the isopropyl alcohol is 10 to 200 ppb by mass. The isopropyl alcohol container according to claim 1, wherein the content of chromium as an impurity in the isopropyl alcohol is 0.01 to 2.50 ppt by mass. The isopropyl alcohol container according to claim 1 or 2, wherein the volume of the container is in the range of 1,000 to 1,500,000 L. The isopropyl alcohol container of claim 3, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank. A method for producing an isopropyl alcohol container in which isopropyl alcohol is contained in a container,
A method for producing an isopropyl alcohol container, comprising: storing isopropyl alcohol in the container; and adjusting the oxygen concentration of the gas in the container to 0.1 to 10 ppm on a volume basis. The method for producing an isopropyl alcohol container according to claim 5, wherein the dissolved oxygen concentration in the isopropyl alcohol contained in the container is 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C under atmospheric conditions. The method for producing an isopropyl alcohol container according to claim 5 or 6, wherein the content of acetone as an impurity in the isopropyl alcohol contained in the container is 10 to 200 ppb by mass. The method for producing an isopropyl alcohol container according to claim 5 or 6, wherein the content of chromium as an impurity in the isopropyl alcohol contained in the container is 0.01 to 2.50 ppt by mass. The method for producing an isopropyl alcohol container according to claim 5 or 6, wherein the volume of the container is in the range of 1,000 to 1,500,000 L. The method for producing an isopropyl alcohol container according to claim 9, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank. A method for producing an isopropyl alcohol container in which isopropyl alcohol is contained in a container,
The isopropyl alcohol is contained in the container so that the volume of the container is 2 to 98%, and the oxygen concentration of the gas in the container is adjusted to 0.1 to 10 ppm on a volume basis. The method for producing an isopropyl alcohol container according to claim 11, wherein the dissolved oxygen concentration in the isopropyl alcohol contained in the container is 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C under atmospheric conditions. The method for producing an isopropyl alcohol container according to claim 11 or 12, wherein the content of acetone as an impurity in the isopropyl alcohol contained in the container is 10 to 200 ppb by mass. The method for producing an isopropyl alcohol container according to claim 11 or 12, wherein the content of chromium as an impurity in the isopropyl alcohol contained in the container is 0.01 to 2.50 ppt by mass. The method for producing an isopropyl alcohol container according to claim 11 or 12, wherein the volume of the container is in the range of 1,000 to 1,500,000 L. The method for producing an isopropyl alcohol container according to claim 15, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank. A method for producing an isopropyl alcohol container in which isopropyl alcohol contained in a first container is contained in a second container,
A method for producing an isopropyl alcohol container, comprising: storing isopropyl alcohol in the second container; and adjusting the oxygen concentration of the gas in the second container to 0.1 to 10 ppm on a volumetric basis. The method for producing an isopropyl alcohol container according to claim 17, wherein the dissolved oxygen concentration in the isopropyl alcohol contained in the second container is 0.001 to 0.050% relative to the oxygen saturation solubility at 25°C under atmospheric conditions. The method for producing an isopropyl alcohol container according to claim 17 or 18, wherein the content of acetone as an impurity in the isopropyl alcohol contained in the second container is 10 to 200 ppb by mass. The method for producing an isopropyl alcohol container according to claim 17 or 18, wherein the content of chromium as an impurity in the isopropyl alcohol contained in the second container is 0.01 to 2.50 ppt by mass. The method for producing an isopropyl alcohol container according to claim 17 or 18, wherein the volume of the first container and the second container is in the range of 1000 to 1500000 L. 22. The method for producing an isopropyl alcohol container according to claim 21, wherein the first container and the second container are an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank. A quality control method for an isopropyl alcohol container in which isopropyl alcohol is contained in a container, comprising:
The quality control method for an isopropyl alcohol container, in which the dissolved oxygen concentration in the isopropyl alcohol is 0.001 to 0.050% relative to the oxygen saturation solubility at 25 ° C. in the atmosphere, and the oxygen concentration of the gas in the container is 0.1 to 10 ppm by volume.