Isopropanol container, method for producing same, and method for managing quality of isopropanol container

Abstract

Provided is an isopropanol container in which isopropanol is stored in a container, the oxygen content in the container being 0.001-0.100 mol ppm relative to the isopropanol, and the content of acetone, which is an impurity in the isopropanol, being 10-200 ppb by mass. Also provided are a method for producing an isopropanol container and a method for managing the quality of an isopropanol container.

Description

Technical Field

[0001] The present disclosure relates to an isopropyl alcohol container in which isopropyl alcohol is contained in a container, a method for manufacturing the container, and a method for quality management of the isopropyl alcohol container. Background Art

[0002] Isopropyl alcohol (also called 2-propanol) is an organic solvent used in various applications, and is particularly used as a cleaning liquid or drying liquid in the manufacturing process of semiconductor devices. In recent years, in the process of seeking higher performance of semiconductor devices, the miniaturization and high integration of components and wiring have continued to develop, and isopropyl alcohol used as a cleaning liquid or drying liquid is also required to be highly purified with very few metal impurities.

[0003] For example, Patent Document 1 states that if isopropyl alcohol, which has increased impurities due to long-term storage, is used for cleaning in the manufacturing process of semiconductor devices, residues from impurities in the isopropyl alcohol may remain on the surface of the semiconductor device after cleaning and drying, which may be the main cause of defects in the semiconductor device. It can be seen from this that the impact of the quality of isopropyl alcohol used as a cleaning liquid or a drying liquid on the yield of semiconductor devices cannot be ignored, and there is a strong demand for improving the quality of isopropyl alcohol.

[0004] It is also known that organic impurities such as acetone exist as impurities in isopropyl alcohol, and when the dissolved oxygen concentration in isopropyl alcohol is high, the content of organic impurities in isopropyl alcohol increases (for example, see Patent Documents 2 or 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 tower in the distillation process when producing isopropyl alcohol. In addition, Patent Document 3 proposes a method of removing dissolved oxygen by bubbling an inert gas such as nitrogen into isopropyl alcohol.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2020 / 071307

[0008] Patent Document 2: International Publication No. 2018 / 135408

[0009] Patent Document 3: Japanese Patent Application Publication No. 2014-201524

[0010] Patent Document 4: International Publication No. 2020 / 009225 Summary of the invention

[0011] Problems to be solved by the invention

[0012] According to the method described in Patent Document 2 or 3, high-purity isopropyl alcohol with reduced dissolved oxygen concentration can be produced. The produced isopropyl alcohol is stored in a storage tank and then filled into a container such as an ISO (International Organization for Standardization) tank container or a canister can before being shipped as a product. Patent Document 4 describes sealing high-purity nitrogen gas in a container.

[0013] Isopropyl alcohol filled in containers such as ISO tank containers and storage tanks may need to be stored for several tens of days to several months before it can be used as a cleaning liquid or drying liquid in the manufacturing process of semiconductor devices. The inventors of the present application have conducted research and found that even when isopropyl alcohol with a low dissolved oxygen concentration produced by the above method is filled in a container and nitrogen with a low oxygen concentration is sealed, if the isopropyl alcohol in the container is analyzed after a period of several tens of days to several months, the content of organic impurities such as metal impurities and acetone may increase, and it cannot be used for semiconductor cleaning purposes.

[0014] Therefore, an object of the present disclosure is to provide an isopropyl alcohol container capable of suppressing an increase in the content of metal impurities and organic impurities such as acetone even after long-term storage, and a method for producing the same.

[0015] Means for solving problems

[0016] The inventor of the present application has repeatedly conducted in-depth research to solve the above-mentioned problem. First, the container with the increased content of organic impurities such as metal impurities and acetone was confirmed. As a result, it can be seen that even if the isopropyl alcohol supplied from the same storage tank is filled in the container and sealed with the same nitrogen, the content of organic impurities such as metal impurities and acetone sometimes also increases. The dissolved oxygen concentration in the isopropyl alcohol batch used at this time and the oxygen concentration of the nitrogen used for sealing were also confirmed, but they were not the oxygen concentration that would cause problems. In addition, it was also confirmed that even if the isopropyl alcohol with the same degree of dissolved oxygen concentration was filled in the same container and the nitrogen with the same degree of oxygen concentration was sealed and kept for a long time, the increase in the content of organic impurities such as metal impurities and acetone in the isopropyl alcohol was also suppressed. According to these situations, about the container used, it was also confirmed that there was no damage to the container. On the other hand, if the container with the high content of organic impurities such as metal impurities and acetone is confirmed, it can be seen that the oxygen concentration of the gas phase in the container and the chromium content in the isopropyl alcohol are high.

[0017] Based on the above findings, it is presumed that the reason why the content of organic impurities such as acetone and chromium increases during long-term storage is that the oxygen concentration immediately after filling becomes high for some reason, and the content of organic impurities such as acetone and chromium increases during long-term storage due to the oxygen in the container. It is also known that the increase in the content of organic impurities such as acetone during long-term storage over time can be suppressed by setting the oxygen concentration of the gas in the container after filling with isopropyl alcohol and sealing an inert gas such as nitrogen to a predetermined concentration or less, thereby completing the present invention.

[0018] Specific means for solving the above-mentioned problems include the following embodiments.

[0019] <1> An isopropyl alcohol storage body, wherein isopropyl alcohol is stored in a container.

[0020] The oxygen content in the container is 0.001 to 0.100 mol pp m relative to the isopropanol.

[0021] The content of acetone as an impurity in the isopropyl alcohol is 10 to 200 ppb on a mass basis.

[0022] <2> The isopropyl alcohol container according to <1>, wherein a content of chromium as an impurity in the isopropyl alcohol is 0.01 to 2.50 ppt on a mass basis.

[0023] <3> The isopropyl alcohol storage container according to <1> or <2>, wherein the volume of the container is in the range of 1,000 to 1,500,000 L.

[0024] <4> The isopropyl alcohol storage container according to <3>, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

[0025] <5> A method for producing an isopropyl alcohol container, the method comprising: storing isopropyl alcohol in a container;

[0026] When isopropyl alcohol is contained in the container, the oxygen concentration of the gas in the container is set to 0.1 to 10 ppm on a volume basis.

[0027] <6> The method for producing an isopropyl alcohol container according to <5>, wherein the concentration of dissolved oxygen in the isopropyl alcohol contained in the container is 0.001 to 0.050% relative to the saturated solubility of oxygen at 25° C. in the atmosphere.

[0028] <7> The method for producing an isopropyl alcohol container according to <5> or <6>, wherein the content of acetone as an impurity in the isopropyl alcohol contained in the container is 10 to 200 ppb on a mass basis.

[0029] <8> The method for producing an isopropyl alcohol container according to any one of <5> to <7>, wherein a content of chromium as an impurity in the isopropyl alcohol contained in the container is 0.01 to 2.50 ppt on a mass basis.

[0030] <9> The method for producing an isopropyl alcohol container according to any one of <5> to <8>, wherein the volume of the container is in the range of 1,000 to 1,500,000 L.

[0031] <10> The method for producing an isopropyl alcohol container according to <9>, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

[0032] <11> A method for producing an isopropyl alcohol container, the method comprising: storing isopropyl alcohol in a container;

[0033] The isopropyl alcohol is stored in a volume that accounts for 2 to 98% of the volume of the container.

[0034] When isopropyl alcohol is contained in the container, the oxygen concentration of the gas in the container is set to 0.1 to 10 ppm on a volume basis.

[0035] <12> The method for producing an isopropyl alcohol container according to <11>, wherein a concentration of dissolved oxygen in the isopropyl alcohol contained in the container is 0.001 to 0.050% relative to the saturated solubility of oxygen at 25° C. in the atmosphere.

[0036] <13> The method for producing an isopropyl alcohol container according to <11> or <12>, wherein the content of acetone as an impurity in the isopropyl alcohol contained in the container is 10 to 200 ppb on a mass basis.

[0037] <14> The method for producing an isopropyl alcohol container according to any one of <11> to <13>, wherein a content of chromium as an impurity in the isopropyl alcohol contained in the container is 0.01 to 2.50 ppt on a mass basis.

[0038] <15> The method for producing an isopropyl alcohol container according to any one of <11> to <14>, wherein the volume of the container is in the range of 1,000 to 1,500,000 L.

[0039] <16> The method for producing an isopropyl alcohol container according to <15>, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

[0040] <17> A method for producing an isopropyl alcohol container, the method comprising: storing the isopropyl alcohol contained in a first container in a second container.

[0041] When isopropyl alcohol is stored in the second container, the oxygen concentration of the gas in the second container is set to 0.1 to 10 ppm on a volume basis.

[0042] <18> The method for producing an isopropyl alcohol container according to <17>, wherein the dissolved oxygen concentration in the isopropyl alcohol contained in the second container is 0.001 to 0.050% relative to the saturated solubility of oxygen at 25° C. in the atmosphere.

[0043] <19> The method for producing an isopropyl alcohol container according to <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 on a mass basis.

[0044] <20> The method for producing an isopropyl alcohol container according to any one of <17> to <19>, wherein a content of chromium as an impurity in the isopropyl alcohol contained in the second container is 0.01 to 2.50 ppt on a mass basis.

[0045] <21> The method for producing an isopropyl alcohol container according to any one of <17> to <20>, wherein the volume of the container is in the range of 1,000 to 1,500,000 L.

[0046] <22> The method for producing an isopropyl alcohol container according to <21>, wherein the container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

[0047] <23> A quality management method for an isopropyl alcohol container, the method comprising: storing isopropyl alcohol in a container;

[0048] The dissolved oxygen concentration in the isopropyl alcohol is set to 0.001 to 0.050% relative to the saturated solubility of oxygen at 25° C. in the atmosphere, and the oxygen concentration of the gas in the container is set to 0.1 to 10 ppm on a volume basis.

[0049] Effects of the Invention

[0050] According to the disclosure, an isopropyl alcohol storage body capable of suppressing the increase in the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage can be provided. In particular, the manufacturing method of the disclosure can also 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 storage body of the disclosure can be stored for a long period of time of 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. DETAILED DESCRIPTION

[0051] In this specification, unless otherwise specified, the expression "A to B" using numerical values ​​A and B means "A or more and B or less." In the expression, when only numerical value B is given a unit, the unit also applies to numerical value A.

[0052] In the following description, unless otherwise specified, "%", "ppm", "ppb" and "ppt" (including examples) indicating concentrations are based on mass. In addition, "vol%" and "volppm" (including examples) indicating concentrations are based on volume fractions, and "molppm" is based on molar fractions.

[0053] <Isopropyl alcohol container>

[0054] The isopropyl alcohol storage body (hereinafter, also referred to as "storage body") of the present disclosure is characterized in that it is a storage body in which isopropyl alcohol is stored in a container, the oxygen content in the container is 0.001 to 0.100 molppm relative to the isopropyl alcohol, and the content of acetone as an impurity in the isopropyl alcohol is 10 to 200 ppb. The interior of the storage body is composed of a portion filled with isopropyl alcohol (hereinafter, this portion is also referred to as "liquid phase") and a space portion not filled with isopropyl alcohol (hereinafter, this portion is also referred to as "gas phase").

[0055] By making such a storage body, 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 long-term storage of several dozen days to several months can be achieved. The reason is not necessarily clear, but the inventors of the present application speculate as follows.

[0056] In the case of the presence of oxygen in isopropanol, oxygen reacts with isopropanol and produces acetone as a byproduct.Therefore, it is believed that by filling the isopropanol with low dissolved oxygen concentration in a container and enclosing inert gases such as nitrogen, the content of organic impurities such as acetone in the isopropanol in the container can be suppressed to increase.But, in the case of the piping used for transferring liquid from a storage tank to a container, the piping used for enclosing nitrogen, etc., there is a very small gap, etc., sometimes minus a small amount of oxygen.In addition, containers such as ISO tank containers are mostly returned after the isopropanol inside is consumed, and are filled with isopropanol and shipped again in the same container.Usually, after fully cleaning the container, the filling of isopropanol is carried out, but it is believed that the cleaning at this time can cause oxygen to remain in the container.

[0057] In the above case, even if it is assumed that isopropyl alcohol with low dissolved oxygen concentration is filled in a container and inert gases such as nitrogen are sealed, a large amount of oxygen is also present in the storage body. A certain amount of oxygen will dissolve in isopropyl alcohol, so it is inferred that if 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. In addition, due to the reaction of oxygen and isopropyl alcohol, hydrogen peroxide is also produced as a byproduct in addition to acetone, and hydrogen peroxide also reacts with isopropyl alcohol. Therefore, it is inferred that due to long-term storage, the content of organic impurities such as acetone increases until the oxygen in the storage body is almost consumed. In addition, the interior of containers such as ISO tank containers is composed of stainless steel, etc., and as a result, chromium is usually contained in stainless steel. It is inferred that due to the influence of oxygen in the container and hydrogen peroxide produced as a byproduct, the chromium contained in the stainless steel is dissolved in a very small amount, and the content of chromium in the isopropyl alcohol also increases. It is also presumed that the chromium eluted into the isopropyl alcohol acts as a catalyst when oxygen and the isopropyl alcohol react, thus promoting an increase in the content of organic impurities such as acetone during storage.

[0058] Therefore, it is speculated that by keeping the oxygen content in the container within a predetermined range when isopropyl alcohol is stored in the container and an inert gas such as nitrogen is filled in the gas phase, an 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, thereby achieving long-term storage of several tens of days to several months.

[0059] (Oxygen content in the container)

[0060] In the storage body of the present disclosure, the oxygen content in the container needs to be set to 0.001 to 0.100 molppm 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 molppm, more preferably 0.001 to 0.010 molppm relative to isopropyl alcohol.

[0061] The oxygen content in the container can be obtained by measuring the oxygen content in the gas phase of the container and the dissolved oxygen content in the isopropyl alcohol in the liquid phase and calculating the total amount thereof. Furthermore, the oxygen content can be obtained as a molar fraction relative to the isopropyl alcohol based on the calculated oxygen content and the amount of isopropyl alcohol in the container.

[0062] Here, as for the oxygen content in the gas phase, the gas phase can be sampled, the oxygen content in the sample can be measured using a known oxygen analysis method, and then calculated based on the oxygen content in the sample and the volume and internal pressure of the gas phase of the storage body. Examples of known oxygen analysis methods include gas chromatography (GC) using a pulse discharge photoionization detector, polarography, and optical oxygen analysis (an analysis method that utilizes the luminescence phenomenon and quenching phenomenon of fluorescent substances).

[0063] In addition, regarding the amount of dissolved oxygen in the isopropyl alcohol in the liquid phase, the isopropyl alcohol in the liquid phase can be sampled, and the amount of oxygen in the sample can be measured using polarography or optical oxygen analysis (an analysis method that utilizes the luminescence phenomenon and quenching phenomenon of fluorescent substances), and then calculated based on the amount of dissolved oxygen in the sample and the volume of isopropyl alcohol in the storage body.

[0064] (Content of acetone as an impurity in isopropyl alcohol)

[0065] In the storage body of the present disclosure, the content of acetone as an impurity in isopropyl alcohol is 10 to 200 ppb. By making the content of acetone in isopropyl alcohol within the above range, the stored isopropyl alcohol can be suitably used as a cleaning liquid or drying liquid for semiconductor devices. From the perspective of reducing the impact on the device when the stored 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, and more preferably 10 to 100 ppb.

[0066] Here, the content of acetone in isopropyl alcohol can be measured by sampling the isopropyl alcohol in the liquid phase of the storage body and then using a gas chromatography-mass spectrometry (GC-MS) method.

[0067] (Content of chromium as an impurity in isopropyl alcohol)

[0068] As described above, it is presumed that the chromium dissolved in isopropyl alcohol plays a catalytic role 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 chromium content in isopropyl alcohol is preferably 0.01 to 2.50 ppt, more preferably 0.01 to 1.00 ppt.

[0069] Here, the chromium content in isopropyl alcohol can be measured by sampling the isopropyl alcohol in the liquid phase of the storage body and then using an inductively coupled plasma mass spectrometry (ICP-MS) method.

[0070] (Isopropyl alcohol)

[0071] The isopropyl alcohol contained in the container is not particularly limited as long as it is isopropyl alcohol having the above-mentioned acetone content after being contained in the container. From the viewpoint of reducing the influence on the semiconductor device when the contained isopropyl alcohol is used as a cleaning liquid or a drying liquid, the purity of the isopropyl alcohol is preferably 99.99% or more, and more preferably 99.9999% or more. In addition, from the viewpoint of suppressing the increase in the content of organic impurities such as acetone during long-term storage, the isopropyl alcohol preferably satisfies the conditions of dissolved oxygen concentration, acetone content, and chromium content shown below.

[0072] The dissolved oxygen concentration in isopropyl alcohol is preferably 0.001 to 0.050%, and more preferably 0.001 to 0.025%, relative to the saturated solubility of oxygen at 25° C. in the atmosphere. The dissolved oxygen concentration in isopropyl alcohol can be obtained by measuring the amount of dissolved oxygen in the liquid phase of the storage body by the above-mentioned method, measuring the oxygen partial pressure corresponding to the dissolved oxygen present in isopropyl alcohol at 25° C. in the atmosphere, dividing the measured oxygen partial pressure by the oxygen partial pressure at 25° C. in the atmosphere, and then converting it into a percentage.

[0073] Here, the so-called atmosphere refers to an air composition of 1 atmosphere. In addition, the so-called oxygen partial pressure at 25°C in the atmosphere refers to the oxygen partial pressure in the air at 25°C and 1 atmosphere, which is 21 kPa. In addition, in the present disclosure, the so-called oxygen saturation solubility at 25°C in the atmosphere refers to the oxygen concentration when the dissolved oxygen reaches equilibrium in an atmosphere of 1 atmosphere and an oxygen partial pressure of 21 kPa.

[0074] The value of the saturated solubility of oxygen in isopropanol varies from document to document. For example, according to the reference (Sato Ten et al., "Solubility of Oxygen in Organic Solvents and Calculation of the Hansen Solubility Parameters of Oxygen", Industrial & Engineering Chemistry Research (Ind. Eng. Chem. Res.), 2014, Vol. 53, pp. 19831-19337), the saturated solubility of oxygen in isopropanol at 25° C. under an atmosphere of 101.3 kPa of oxygen partial pressure is 7.78×10 -4 When the dissolved oxygen concentration in isopropyl alcohol is 0.001 to 0.050% relative to the saturated solubility of oxygen at 25° C. in the atmosphere, the dissolved oxygen concentration in isopropyl alcohol can be calculated to be 0.9 to 43.5 ppb.

[0075] The content of acetone contained as an impurity in isopropyl alcohol is preferably 10 to 200 ppb, more preferably 10 to 100 ppb. The content of acetone in isopropyl alcohol can be measured by the same method as the method for measuring acetone in the liquid phase of the storage body.

[0076] The content of chromium in the metal impurities contained in isopropyl alcohol is preferably 0.01 to 2.50 ppt, more preferably 0.01 to 1.00 ppt. The content of chromium in isopropyl alcohol can be measured by the same method as the method for measuring chromium in the liquid phase of the storage body.

[0077] As the isopropyl alcohol stored in the container, isopropyl alcohol obtained by a known production method can be used. As known production methods, acetone reduction method, VebaChemie method as a gas phase method of a fixed bed catalytic method, Deutsche Texaco method as a gas-liquid mixed phase method of a fixed bed catalytic method, direct hydration method, etc. can be cited. Among these production methods, direct hydration method is preferred from the perspective of obtaining high-purity isopropyl alcohol and easy purification.

[0078] As a method for purifying the isopropyl alcohol obtained by the above method, a known method can be used. Specifically, there can be mentioned a method of purifying the isopropyl alcohol by distillation, a method of filtering the isopropyl alcohol with a filter, a method of combining these methods, etc. When used as a cleaning liquid or drying liquid for semiconductor devices, it is necessary to prepare isopropyl alcohol of high purity and free of particles, etc. As a purification method, a method combining distillation and filtration is preferably used.

[0079] (Container for storage body)

[0080] As a container for storing isopropyl alcohol, a container known as a container for storing organic liquid medicine can be used without particular limitation. The volume of these containers is, for example, in the range of 10 to 1,500,000 L. As the container, specifically, there can be cited a storage tank (volume: 18 to 200 L), an intermediate bulk container (IBC) (volume: 1,000 to 2,000 L), a tank truck (volume: 2,000 to 4,000 L), an ISO tank container (volume: 13,000 to 26,000 L), a storage tank (volume: 100,000 to 1,500,000 L), etc. In particular, as the container of the present disclosure, a container (intermediate bulk container, tank truck, ISO tank container, storage tank, etc.) with a volume in the range of 1,000 to 1,500,000 L is preferred. In the case of the container with a large internal volume, when an inert gas such as nitrogen is sealed after filling the container with isopropyl alcohol, oxygen often remains in the gas phase. In this regard, by managing the oxygen content in the container within a predetermined range as in the present disclosure, it is possible to suppress the increase in the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage, and it is possible to control the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage, thereby enabling long-term storage of several dozen days to several months.

[0081] From the viewpoint of the effect of suppressing the increase of impurities in the isopropyl alcohol contained in the container, the material of the liquid contact part of the container with the isopropyl alcohol is preferably at least one selected from the group consisting of resin (polyolefin resin, fluororesin, etc.), glass, and metal (stainless steel, hastelloy, inconel, monel, etc.), and more preferably stainless steel. As stainless steel, for example, 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%) can be cited.

[0082] As mentioned above, it is inferred that the chromium dissolved in the isopropanol plays a catalytic role when oxygen reacts with the isopropanol. When using stainless steel such as SUS304 as the material of the container, in order to suppress the dissolution of metal components such as chromium into the isopropanol, it is preferred to implement a passivation treatment of forming a passivation layer on the stainless steel surface in advance. By implementing a passivation treatment in advance to the liquid contact portion with the isopropanol, the content of the metal impurities in the isopropanol can be suppressed to increase in storage, filling or transportation procedures. As the passivation treatment, known methods can be used.

[0083] The amount of isopropyl alcohol stored in the container may be appropriately determined by comprehensively considering the storage purpose, etc. Considering the volatility of isopropyl alcohol, transportation costs, etc., it is preferred that the isopropyl alcohol be stored in a range of 2 to 98% of the volume of the container, and more preferably in a range of 80 to 98%.

[0084] <Method for manufacturing storage body>

[0085] The manufacturing method of the storage body of the present disclosure is characterized in that when isopropyl alcohol is stored in the container, the oxygen concentration of the gas in the container is set to 0.1 to 10 volppm. By such a manufacturing method, the content of metal impurities such as chromium and organic impurities such as acetone during long-term storage can be controlled, and a storage body capable of long-term storage for tens of days to several months can be manufactured. 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 stored 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.

[0086] In addition, there is also a case where the isopropyl alcohol is temporarily stored in a storage tank (first container) and further stored in an ISO tank container (second container). When the isopropyl alcohol is stored in the second container, by implementing the above-mentioned production method of the present disclosure, the content of metal impurities such as chromium and organic impurities such as acetone in the isopropyl alcohol stored in the second container can be controlled during long-term storage, and long-term storage of several dozen days to several months can be achieved.

[0087] Hereinafter, as an example of the production method of the present disclosure, a method of storing isopropyl alcohol that has undergone a purification step in a storage tank and further storing the stored isopropyl alcohol in an ISO tank container will be described.

[0088] (Storage of isopropyl alcohol in a storage tank)

[0089] In the manufacturing method of the present disclosure, the storage tank is connected to: a liquid delivery line for delivering isopropyl alcohol from the purification process to the storage tank; and a gas supply line for supplying an inert gas 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.

[0090] As the inert gas, a stable inert gas such as nitrogen or argon can be used. Nitrogen is preferably used because an industrially high-purity inert gas can be obtained 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 further preferably 0.1 volppm or less.

[0091] In the manufacturing method of the present disclosure, from the viewpoint of suppressing the increase of impurities in isopropyl alcohol, the material of the delivery pipe used in the liquid delivery line and the gas supply line is preferably the same as the material of the above-mentioned container. Specifically, stainless steel or fluororesin (PFA, PTFE, etc.) is preferred. As stainless steel, for example, SUS304, SUS304L, SUS316, SUS316L, etc. can be cited. As mentioned above, the stainless steel can be passivated in advance.

[0092] Before initially delivering isopropyl alcohol to the storage tank, it is preferred to replace the gas phase in the storage tank with an inert gas, measure the oxygen concentration in the inert gas when filled with the inert gas, and after confirming that the oxygen concentration is 0.1 to 10 volppm, store the isopropyl alcohol in the storage tank.

[0093] When isopropyl alcohol is stored in the storage tank via the liquid feeding line, the dissolved oxygen concentration, acetone content, and chromium content in isopropyl alcohol are preferably within the same preferred ranges as those of the dissolved oxygen concentration of isopropyl alcohol in the storage body described above.

[0094] The amount of isopropyl alcohol stored in the storage tank is preferably 2 to 98% of the volume.

[0095] Next, an inert gas is sealed into the gas phase in the storage tank containing isopropyl alcohol. The internal pressure of the gas phase in the storage tank after the inert gas is sealed is not particularly limited, but is preferably 0.0001 to 0.30 MPa.

[0096] After sealing the inert gas, the gas phase in the storage tank is sampled and the oxygen concentration is measured. If the oxygen concentration is 0.1 to 10 volppm, it can be used as the storage body of the present disclosure. When the oxygen concentration of the gas phase is not within the above range, the gas phase is replaced by supplying an inert gas until the oxygen concentration of the gas phase is within the above range, thereby manufacturing the storage body of the present disclosure. Alternatively, the stored isopropyl alcohol is discharged, the storage tank is cleaned, the airtightness of the piping (liquid delivery line, gas supply line, other equipment) is confirmed, and the isopropyl alcohol is stored again, thereby manufacturing the storage body of the present disclosure.

[0097] The temperature when isopropyl alcohol is stored in the container is not particularly limited, and may be appropriately set generally within the range of -20 to 50°C from the viewpoint of suppressing an increase in the impurity content during long-term storage.

[0098] (Storage of isopropyl alcohol in storage tanks into ISO tank containers)

[0099] Next, a method for manufacturing the storage body of the present disclosure by storing isopropyl alcohol in a storage tank in an ISO tank container will be described.

[0100] As an ISO tank container, a used ISO tank container may be reused. In this case, it is preferable to pre-clean the ISO tank container with isopropyl alcohol before storing the isopropyl alcohol.

[0101] Generally, the storage tank and the ISO tank container are not connected and are independent of each other. Therefore, in order to deliver isopropyl alcohol from the storage tank to the ISO tank container, a delivery pipe of a liquid delivery line for delivering isopropyl alcohol in the storage tank and a gas supply line for supplying inert gas to the ISO tank container are connected to the ISO tank container.

[0102] The connection between the ISO tank container and the delivery pipes of the liquid delivery line and the gas supply line can be made by a known method. In order to connect to the delivery pipes of the liquid delivery line and the gas supply line, the ISO tank container is provided with a joint. The joint provided in the delivery pipes of the liquid delivery line and the gas supply line is connected to the joint provided in the ISO tank container. Examples of the joint include a rod-type joint, a quick fluid joint, and the like. A flexible hose can be used for the liquid delivery line and the gas supply line.

[0103] The main reason for the increase in oxygen concentration of isopropyl alcohol filled in the ISO tank container is that air is mixed into the pipeline when the joint provided in the ISO tank container is connected to the joint provided in the delivery pipe of the liquid delivery line and the gas supply line, or when the connection of the joint is not airtight and there is a gap, etc., and oxygen is dissolved in the isopropyl alcohol in the container. Therefore, it is preferable to provide an exhaust line for a vent in the gas supply line, purge the line by pressurizing an inert gas, and fully replace the atmosphere in the gas supply line and the ISO tank container until the oxygen concentration reaches a predetermined range.

[0104] Preferably, before the ISO tank container is filled with isopropyl alcohol, residual isopropyl alcohol in the ISO tank container is discharged to the outside of the ISO tank container by pressurizing with an inert gas from a gas supply line.

[0105] Then, the isopropyl alcohol in the storage tank is delivered to the ISO tank container via the delivery line. At this time, the amount of isopropyl alcohol stored in the ISO tank container is preferably 2 to 98% of the volume.

[0106] Next, an inert gas is sealed into the gas phase in the ISO tank container filled with isopropyl alcohol. The internal pressure of the gas phase in the ISO tank container after the inert gas is sealed 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.

[0107] After the inert gas is sealed, the gas phase in the ISO tank container is sampled and the oxygen concentration is measured. If the oxygen concentration is 0.1 to 10 volppm, it can be used as the storage body of the present disclosure. If the oxygen concentration of the gas phase is not within the above range, the inert gas is supplied to replace the gas phase until the oxygen concentration of the gas phase is within the above range, thereby manufacturing the storage body of the present disclosure. Alternatively, the stored isopropyl alcohol is discharged, the ISO tank container is cleaned, the airtightness of the piping (liquid delivery line, gas supply line, other equipment) is confirmed, and the isopropyl alcohol is stored again, thereby manufacturing the storage body of the present disclosure. For the discharged isopropyl alcohol, the dissolved oxygen concentration, acetone content, and chromium content are analyzed. If they are all within the preferred range, it can be used as isopropyl alcohol for storage in the ISO tank container again. On the other hand, if it is not within the preferred range, it can be used as isopropyl alcohol stored in the ISO tank container after purification using a known purification method.

[0108] In the above, a method of delivering isopropyl alcohol in a storage tank to an ISO tank container has been described, but the production method of the present disclosure is not limited to this method, and a storage tank or the like can also be used as the container.

[0109] The pre-washing of the storage tank can be implemented by the following steps. That is, it can be implemented by the following method: isopropyl alcohol is filled into the container from the liquid delivery line in a manner of 1 to 10% of the volume, and pre-washing is performed. After the pre-washing, the residual isopropyl alcohol in the container is discharged to the outside of the container by pressurizing the inert gas from the gas supply line. The pre-washing is not limited to one time, and can be performed multiple times.

[0110] In addition, pre-washing of intermediate bulk containers, tank trucks, and ISO tank containers can be implemented using the following steps. First, pure water that has passed through a filter is supplied to the container and filled until it overflows from the container, thereby performing pure water washing. After standing for 15 minutes, the pure water in the container is discharged to the outside of the container by pressurizing the inert gas from the gas supply line. Isopropyl alcohol is filled into the container from the liquid supply line in a manner that becomes 1 to 10% of the volume, and pre-washing is performed. After pre-washing, the residual isopropyl alcohol in the container is discharged to the outside of the container by pressurizing the inert gas from the gas supply line. Pre-washing is not limited to one time and can be performed multiple times. However, in the case where the container is filled with only isopropyl alcohol and sealed with inert gas after multiple pre-washing of the container, it is not necessary to perform pure water washing and pre-washing of the container.

[0111] <Quality management method of storage body>

[0112] As described above, it is presumed that if oxygen exists in the gas phase of the storage body, the content of metal impurities such as chromium and organic impurities such as acetone will increase due to long-term storage until the oxygen in the storage body is almost consumed. Therefore, by measuring the oxygen concentration in the gas phase of the storage body and the dissolved oxygen concentration in the isopropyl alcohol in the liquid phase, and managing them in a manner that they are within a specified range, 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, and long-term storage of dozens of days to several months can be achieved.

[0113] When the oxygen concentration in the gas phase of the storage body is not within the range of 0.1 to 10 volppm, or when 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 saturated solubility of oxygen at 25°C in the atmosphere, the following method is performed as a quality control method. First, the isopropyl alcohol in the container is discharged and the container is purged with an inert gas. At this time, it is confirmed that there is no leakage at the joint between the container and the delivery pipe. Next, the oxygen concentration in the gas phase of the container is measured, and it is confirmed that the oxygen concentration is within the range of 0.1 to 10 volppm, and then the container is filled with the isopropyl alcohol purified by the above method again. After filling, the following conditions are confirmed: the oxygen concentration in the gas phase of the container is measured, and the oxygen concentration is within the range of 0.1 to 10 volppm; and the dissolved oxygen concentration in the isopropyl alcohol in the container is measured, and the dissolved oxygen concentration is 0.001 to 0.050% relative to the saturated solubility of oxygen at 25°C in the atmosphere.

[0114] Through the above steps, the oxygen concentration of the isopropyl alcohol storage body can be managed. The above storage body can suppress the increase of organic impurities and chromium content in the isopropyl alcohol during storage or transportation. The isopropyl alcohol in the above storage body can be stored for a long time and can be appropriately used as a cleaning liquid or drying liquid for semiconductor devices.

[0115] It should be noted that the isopropyl alcohol in the storage body can suppress not only the increase in the acetone content among the organic impurities but also the increase in the content of organic acids and the like.

[0116] Example

[0117] Hereinafter, the present invention will be described in detail using Examples, but the present invention is not limited to these Examples.

[0118] <Oxygen content in isopropyl alcohol container>

[0119] The calculation of the oxygen content in the gas phase of the isopropyl alcohol storage body is carried out as follows. First, an optical oxygen concentration meter (manufactured by PreSens, Fibox 4trace (sensor: Pst6)) is 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 calibrate them in advance. Next, the value of the internal pressure of the gas phase of the storage body is confirmed by the pressure gauge installed in the storage body, and the gas phase of the storage body is pressurized to the optical oxygen concentration meter according to the internal pressure of the gas phase of the storage body, and purged for 1 minute to measure the oxygen concentration of the gas phase of the storage body. Finally, the oxygen content of the gas phase of the storage body is calculated according to the formula (oxygen concentration of the gas phase of the storage body × (atmospheric pressure + internal pressure) ÷ atmospheric pressure × molar volume of gas × volume of the gas phase).

[0120] In addition, the calculation of the oxygen content in the liquid phase of the storage body is implemented as follows. First, use an optical oxygen concentration meter (manufactured by PreSens, Fibox 4trace (sensor: Pst6)) 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 calibrate them in advance. Next, the liquid phase of the storage body is pressurized to the optical oxygen concentration meter by the internal pressure of the gas phase of the storage body, and a 1-minute purge is performed to measure the oxygen concentration in the liquid phase of the storage body. Finally, the oxygen content in the liquid phase of the storage body is calculated according to the formula (oxygen concentration in the liquid phase of the storage body ÷ molar mass of oxygen × weight of the liquid phase).

[0121] The total amount of oxygen in the gas phase and liquid phase of the container was taken as the oxygen content in the container. The molar fraction of the oxygen content in the container relative to isopropyl alcohol was calculated using the formula (oxygen content in the container÷weight of the liquid phase×molar mass of isopropyl alcohol).

[0122] <Acetone content in isopropyl alcohol container>

[0123] The acetone content in the isopropyl alcohol storage body was measured using GC-MS (gas chromatography-mass spectrometry) under the following measurement conditions using selected ion detection (SIM). A standard curve for acetone content based on the same measurement conditions was prepared in advance, and the acetone content in the sample to be measured was determined based on the standard curve and converted into the amount of isopropyl alcohol in the storage body as the acetone content in the isopropyl alcohol storage body.

[0124] -Measurement conditions-

[0125] Apparatus: GCMS-QP2010 Ultra (manufactured by Shimadzu Corporation)

[0126] Chromatographic column: CP-WAX 52CB (60m×0.25mm, 0.50μm)

[0127] Carrier gas: Helium

[0128] Carrier gas flow rate: 0.98mL / min

[0129] Inlet temperature: 150℃

[0130] Column temperature: 75°C

[0131] Detector temperature: 230°C

[0132] Injection mode: split flow method

[0133] Split ratio: 1 to 10

[0134] SIM mode setting ion: m / Z = 43

[0135] <Chromium content in isopropyl alcohol container>

[0136] With regard to the metal impurities contained in isopropanol, ICP-MS (inductively coupled plasma mass spectrometer) is used to quantify in the following manner. About 500mL isopropanol is collected in an eggplant-shaped flask, after being concentrated and dried using a rotary evaporator, about 25mL of 0.1N nitric acid is divided and reclaimed twice. For the 0.1N nitric acid solution recovered, ICP-MS (Agilent Technologies, Agilent8900) is used to quantify the metal dissolution amount. At this time, the ratio of the weight of the isopropanol before concentration and the weight of the 0.1N nitric acid solution after recovery is calculated to calculate the concentration ratio, and the metal impurity amount converted into unit isopropanol weight.

[0137] <Example 1>

[0138] The isopropyl alcohol that has undergone the purification process is stored in a storage tank using the following method. First, before the isopropyl alcohol is sent to the storage tank, the gas phase in the storage tank is replaced with nitrogen via a gas supply line. The purity of the nitrogen used at this time is more than 99.999%, and the oxygen concentration is less than 5 volppm. After the gas phase replacement, the oxygen content in the storage body is measured, and the oxygen concentration of the gas phase in the storage tank is less than 1 volppm. Then, the isopropyl alcohol that has undergone the purification process is stored in the storage tank via a liquid delivery line. The storage amount of the isopropyl alcohol stored in the storage tank is 80% of the internal volume. Then, nitrogen is sealed into the gas phase in the storage tank containing the isopropyl alcohol via a gas supply line. The internal pressure of the gas phase in the storage tank after the nitrogen is sealed is 0.0005MPa.

[0139] After nitrogen was sealed into the gas phase of the storage tank to form an isopropyl alcohol storage body, the oxygen content in the storage body was measured. The results showed that the oxygen concentration in the gas phase of the storage body was 1.0 volppm, the dissolved oxygen concentration of isopropyl alcohol in the storage body was 0.024% relative to the saturated solubility of oxygen at 25°C in the atmosphere, and the molar fraction of the oxygen content in the storage body relative to the isopropyl alcohol was 0.040 molppm. In addition, the acetone content in the storage body was 10 ppb and the chromium content was 0.19 ppt.

[0140] The storage body manufactured in this manner was stored at a temperature range of 15 to 30°C for 30 days. After storage, the oxygen content in the storage body was measured, and the oxygen concentration in the gas phase of the storage body was 0.7 volppm, the dissolved oxygen concentration of isopropyl alcohol in the container was 0.016% relative to the saturated solubility of oxygen at 25°C in the atmosphere, and the molar fraction of the oxygen content in the storage body relative to the isopropyl alcohol was 0.027 molppm. In addition, the acetone content in the storage body was 46 ppb, and the chromium content was 0.64 ppt.

[0141] <Comparative Example 1>

[0142] The isopropyl alcohol that has undergone the purification process is stored in a storage tank using the following method. First, the isopropyl alcohol that has undergone the purification process is stored in the storage tank via a liquid delivery line. The storage amount of the isopropyl alcohol stored in the storage tank is set to 80% of the internal volume. Next, nitrogen is sealed into the gas phase portion in the storage tank containing the isopropyl alcohol via a gas supply line. The purity of the nitrogen used at this time is 99.999% or more, and the oxygen concentration is 5 volppm or less. The internal pressure of the gas phase portion in the storage tank after the nitrogen is sealed is 0.0005 MPa.

[0143] The storage body produced in this manner was stored for 51 days in a temperature range of 15 to 30° C. The storage conditions of the storage body are shown in Table 1, and the oxygen content, acetone content, and chromium content in the storage body before and after the storage are shown in Table 2.

[0144] <Example 2>

[0145] The isopropyl alcohol in the storage tank is stored in the ISO tank container by the following method. First, the joints provided in the delivery pipes of the liquid delivery line and the gas supply line connected to the storage tank are connected to the joints of the ISO tank container. The pipeline is purged for 5 minutes by pressurizing the nitrogen in the exhaust line for the vent in the gas supply line. The purity of the nitrogen used at this time is 99.999% or more, and the oxygen concentration is 5 volppm or less. In addition, it is confirmed that there is no leakage at the joint part of the delivery pipe. After the gas phase replacement, it is confirmed that the oxygen concentration in the gas supply line is 1 volppm or less. Then, before the isopropyl alcohol is delivered to the ISO tank container, the residual isopropyl alcohol in the ISO tank container is discharged to the outside of the ISO tank container by pressurizing the nitrogen from the gas supply line. After the isopropyl alcohol is discharged, it is confirmed that the oxygen concentration in the gas phase in the ISO tank container is 1 volppm or less. Then, the isopropyl alcohol in the storage tank is stored in the ISO tank container via the liquid delivery line. The storage amount of isopropyl alcohol stored in the ISO tank container was set to 87% of the internal volume. Then, nitrogen was sealed into the gas phase of the ISO tank container storing isopropyl alcohol through the gas supply line. The internal pressure of the gas phase of the ISO tank container after the nitrogen was sealed was 0.07 MPa.

[0146] The storage body produced in this manner was stored for 20 days in a temperature range of 15 to 30° C. The storage conditions of the storage body are shown in Table 1, and the oxygen content, acetone content, and chromium content in the storage body before and after the storage are shown in Table 2.

[0147] <Comparative Example 2>

[0148] The isopropyl alcohol in the storage tank is stored in the ISO tank container by the following method. First, the joints provided in the delivery pipes of the liquid delivery line and the gas supply line connected to the storage tank are connected to the joints of the ISO tank container. However, the pipelines are not purged by nitrogen pressurization. Then, before the isopropyl alcohol is delivered to the ISO tank container, the residual isopropyl alcohol in the ISO tank container is discharged to the outside of the ISO tank container for 1 minute by nitrogen pressurization from the gas supply line. The purity of the nitrogen used at this time is 99.999% or more, and the oxygen concentration is 5 volppm or less. Then, the isopropyl alcohol in the storage tank is stored in the ISO tank container via the liquid delivery line. The storage amount of isopropyl alcohol stored in the ISO tank container is set to 87% of the internal volume. Then, nitrogen is sealed into the gas phase part of the ISO tank container storing isopropyl alcohol via the gas supply line. The internal pressure of the gas phase part in the ISO tank container after the nitrogen is sealed is 0.06MPa.

[0149] The storage body produced in this manner was stored for 21 days in a temperature range of 15 to 30° C. The storage conditions of the storage body are shown in Table 1, and the oxygen content, acetone content, and chromium content in the storage body before and after the storage are shown in Table 2.

[0150] <Example 3>

[0151] The isopropyl alcohol in the storage tank is stored in the storage tank using the following method. First, the joints provided in the delivery pipes of the liquid delivery line and the gas supply line connected to the storage tank are connected to the joints of the storage tank. The isopropyl alcohol is filled into the storage tank in a manner of 1 to 10% of the volume via the liquid delivery line, and pre-washing and cleaning are performed. After the pre-washing and cleaning, the residual liquid of the isopropyl alcohol in the storage tank is discharged to the outside of the container by nitrogen pressurization from the gas supply line. The pre-washing and cleaning is implemented three times. The purity of the nitrogen used at this time is more than 99.999%, and the oxygen concentration is less than 5 volppm. In addition, it is confirmed that there is no leakage at the joint part of the delivery pipe. After the pre-washing and cleaning, it is confirmed that the oxygen concentration in the storage tank is less than 1 volppm. Next, the isopropyl alcohol in the storage tank is stored in the storage tank via the liquid delivery line. The storage amount of isopropyl alcohol stored in the storage tank is set to 82% of the internal volume. Next, nitrogen is sealed into the gas phase part in the storage tank containing isopropyl alcohol via the gas supply line. The internal pressure of the gas phase in the tank after sealing with nitrogen was 0.20 MPa.

[0152] The storage body produced in this manner was stored for 59 days in a temperature range of 15 to 30° C. The storage conditions of the storage body are shown in Table 1, and the oxygen content, acetone content, and chromium content in the storage body before and after the storage are shown in Table 2.

[0153] <Comparative Example 3>

[0154] The isopropyl alcohol in the storage tank is stored in the storage tank using the following method. First, the joints provided in the delivery pipes of the liquid delivery line and the gas supply line connected to the storage tank are connected to the joints of the storage tank. The isopropyl alcohol is filled into the storage tank in a manner of 1 to 10% of the volume via the liquid delivery line, and pre-washing and cleaning are performed. After the pre-washing and cleaning, the residual isopropyl alcohol in the storage tank is discharged to the outside of the container by pressurizing with nitrogen from the gas supply line. The pre-washing and cleaning is implemented 3 times. The purity of the nitrogen used at this time is 99.999% or more, and the oxygen concentration is 5 volppm or less. In addition, it is confirmed that there is no leakage at the joint part of the delivery pipe. After the pre-washing and cleaning, it is confirmed that the oxygen concentration in the storage tank is 1 volppm or less. Next, the isopropyl alcohol in the storage tank is stored in the storage tank via the liquid delivery line. The storage amount of isopropyl alcohol stored in the storage tank is set to 82% of the internal volume. Next, nitrogen was sealed into the gas phase of the tank containing isopropyl alcohol through a gas supply line to adjust the internal pressure of the tank to 0.05 MPa, and nitrogen having an oxygen concentration of 1000 volppm was further sealed to adjust the internal pressure of the gas phase of the tank to 0.20 MPa.

[0155] The storage body produced in this manner was stored for 59 days in a temperature range of 15 to 30° C. The storage conditions of the storage body are shown in Table 1, and the oxygen content, acetone content, and chromium content in the storage body before and after the storage are shown in Table 2.

[0156] <Example 4>

[0157] The isopropyl alcohol in the storage tank is stored in the ISO tank container by the following method. First, the joints provided in the delivery pipes of the liquid delivery line and the gas supply line connected to the storage tank are connected to the joints of the ISO tank container. The pipeline is purged for 5 minutes by pressurizing the nitrogen in the exhaust line for the vent in the gas supply line. The purity of the nitrogen used at this time is 99.999% or more, and the oxygen concentration is 5 volppm or less. In addition, it is confirmed that there is no leakage at the joint part of the delivery pipe. After the gas phase replacement, it is confirmed that the oxygen concentration in the gas supply line is 1 volppm or less. Then, before the isopropyl alcohol is delivered to the ISO tank container, the residual isopropyl alcohol in the ISO tank container is discharged to the outside of the ISO tank container by pressurizing the nitrogen from the gas supply line. After the isopropyl alcohol is discharged, it is confirmed that the oxygen concentration in the gas phase in the ISO tank container is 1 volppm or less. Then, the isopropyl alcohol in the storage tank is stored in the ISO tank container via the liquid delivery line. The storage amount of isopropyl alcohol stored in the ISO tank container was set to 87% of the internal volume. Then, nitrogen was sealed into the gas phase of the ISO tank container storing isopropyl alcohol through the gas supply line. The internal pressure of the gas phase of the ISO tank container after the nitrogen was sealed was 0.05 MPa.

[0158] The storage body produced in this manner was stored for 98 days in a temperature range of 15 to 30° C. The storage conditions of the storage body are shown in Table 1, and the oxygen content, acetone content, and chromium content in the storage body before and after the storage are shown in Table 2.

[0159] <Example 5>

[0160] The following method is used to store the isopropyl alcohol in the storage tank in the ISO tank container. First, the joints provided in the delivery pipes of the liquid delivery line and the gas supply line connected to the storage tank are connected to the joints of the ISO tank container. The pipeline is purged for 5 minutes by pressurizing the nitrogen in the exhaust line for the vent in the gas supply line. The purity of the nitrogen used at this time is 99.999% or more, and the oxygen concentration is 5 volppm or less. In addition, it is confirmed that there is no leakage at the joint part of the delivery pipe. After the gas phase replacement, it is confirmed that the oxygen concentration in the gas supply line is 5 volppm or less. Then, before the isopropyl alcohol is delivered to the ISO tank container, the residual isopropyl alcohol in the ISO tank container is discharged to the outside of the ISO tank container by pressurizing the nitrogen from the gas supply line. After the isopropyl alcohol is discharged, it is confirmed that the oxygen concentration in the gas phase in the ISO tank container is 5 volppm or less. Then, the isopropyl alcohol in the storage tank is stored in the ISO tank container via the liquid delivery line. The storage amount of isopropyl alcohol stored in the ISO tank container was set to 87% of the internal volume. Then, nitrogen was sealed into the gas phase of the ISO tank container storing isopropyl alcohol through the gas supply line. The internal pressure of the gas phase of the ISO tank container after the nitrogen was sealed was 0.05 MPa.

[0161] The storage body produced in this manner was stored for 35 days in a temperature range of 15 to 30° C. The storage conditions of the storage body are shown in Table 1, and the oxygen content, acetone content, and chromium content in the storage body before and after the storage are shown in Table 2.

[0162] [Table 1]

[0163]

[0164] [Table 2]

[0165]

[0166] ※1: The upper row indicates the value at the start of storage, and the lower row indicates the value at the end of storage.

[0167] ※2: Dissolved oxygen concentration in isopropyl alcohol relative to the saturated solubility of dissolved oxygen at 25°C (%)

[0168] ※3: The molar fraction of oxygen content in the container relative to isopropyl alcohol (molppm)

[0169] As shown in Table 2, for the storage bodies of Examples 1 to 5 in which the oxygen content in the storage body is set to 0.001 to 0.100 molppm relative to isopropyl alcohol and the content of acetone as an impurity in isopropyl alcohol is set to 10 to 200 ppb on a mass basis, the increase in the acetone content and the chromium content after long-term storage for several tens of days to several months is suppressed compared to the storage bodies of Comparative Examples 1 to 3.

Claims

1. An isopropyl alcohol storage body, which is an isopropyl alcohol storage body in which isopropyl alcohol is stored in a container, The oxygen content in the container is 0.001 to 0.100 mol pp m relative to the isopropanol, The content of acetone as an impurity in the isopropyl alcohol is 10 to 200 ppb on a mass basis.

2. The isopropyl alcohol storage container according to claim 1, wherein: The content of chromium as an impurity in the isopropyl alcohol is 0.01 to 2.50 ppt on a mass basis.

3. The isopropyl alcohol storage container according to claim 1 or 2, wherein: The volume of the container is in the range of 1000 to 1500000L.

4. The isopropyl alcohol storage container according to claim 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 storage body, the method comprising: storing isopropyl alcohol in a container; When isopropyl alcohol is contained in the container, the oxygen concentration of the gas in the container is set to 0.1 to 10 ppm on a volume basis.

6. 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 saturated solubility of oxygen at 25° C. in the atmosphere.

7. 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 on a mass basis.

8. 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 on a mass basis.

9. 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 1000 to 1500000L.

10. 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.

11. A method for producing an isopropyl alcohol storage body, the method comprising: storing isopropyl alcohol in a container; The isopropyl alcohol is stored in a volume that accounts for 2 to 98% of the volume of the container. When isopropyl alcohol is contained in the container, the oxygen concentration of the gas in the container is set to 0.1 to 10 ppm on a volume basis.

12. 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 saturated solubility of oxygen at 25° C. in the atmosphere.

13. 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 on a mass basis.

14. 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 on a mass basis.

15. 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 1000 to 1500000L.

16. 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.

17. A method for producing an isopropyl alcohol container, the method comprising: storing the isopropyl alcohol contained in a first container in a second container. When isopropyl alcohol is stored in the second container, the oxygen concentration of the gas in the second container is set to 0.1 to 10 ppm on a volume basis.

18. 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% with respect to the saturated solubility of oxygen at 25° C. in the atmosphere.

19. 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 on a mass basis.

20. 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 on a mass basis.

21. The method for producing an isopropyl alcohol container according to claim 17 or 18, wherein: The volume of the container is in the range of 1000 to 1500000L.

22. The method for producing an isopropyl alcohol container according to claim 21, wherein: The container is an intermediate bulk container, a tank truck, an ISO tank container, or a storage tank.

23. A quality management method for an isopropyl alcohol container, the method comprising: storing isopropyl alcohol in a container; The dissolved oxygen concentration in the isopropyl alcohol is set to 0.001 to 0.050% relative to the saturated solubility of oxygen at 25° C. in the atmosphere, and the oxygen concentration of the gas in the container is set to 0.1 to 10 ppm on a volume basis.

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