Metal corrosion inhibitory composition and gas supply method using the same

Abstract

The present invention provides a composition for suppressing corrosion of iodine-containing gas plant equipment, etc., which is relatively simple and has few equipment constraints, and a method for supplying the composition. [Solution] A composition comprising an iodoperfluoroalkyl and a non-corrosive gas which may contain carbon dioxide, The carbon dioxide content in the noncorrosive gas is 50% by volume or less of the total amount of the noncorrosive gas. The non-corrosive gas is one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixture of two or more gases. A metal corrosion inhibitory composition and a method for supplying it are used.

Description

[Technical Field]

[0001] Iodine-containing compounds such as iodoperfluoroalkyls are widely used industrially in applications such as chemical raw materials, refrigerants, fumigants, fire extinguishing agents, and cover gases during alloy casting. The present invention relates to a composition for suppressing corrosion of plant equipment and the like by iodine-containing gas, and a method for supplying the composition. [Background technology]

[0002] Iodine is a brownish-yellow, highly sublimable element that not only discolors products but is also extremely corrosive, causing metals to corrode even in trace amounts in the gas, making it difficult to handle (Patent Document 1). On the other hand, iodine-containing compounds that are gaseous at room temperature include, for example, iodoperfluoroalkyls, which are widely used industrially in applications such as chemical raw materials, refrigerants, fumigants, fire extinguishing agents, and cover gases during alloy casting (Non-Patent Literature 1). However, it is known that iodoperfluoroalkyls release iodine due to factors such as slight light exposure or storage conditions (Patent Document 2, Non-Patent Document 2). Therefore, measures such as coating the inside with a resin such as Teflon (registered trademark) are necessary to prevent corrosion of the equipment. However, in complex or high-temperature equipment, it is technically impossible to coat minute areas, and preventing iodine-induced corrosion has been difficult due to issues such as coating costs and heat resistance.

[0003] In Japan, the losses due to corrosion of various facilities are enormous, reportedly reaching 2% of GDP. In particular, corrosion-related problems in various plant facilities are unavoidable, and requests for maintenance and other measures are made. It is necessary to understand the corrosion mechanism, the corrosion characteristics of various materials, the factors influencing corrosion, corrosion management, and corrosion prevention measures, and to address each facility individually (Non-Patent Document 3).

[0004] In particular, with regard to metal structures used in piping, chemical reaction equipment, etc., corrosion of metal is not simply a matter of the amount of metal corroded, but rather the corrosion can progress deeply from the surface to the interior of the metal structure, potentially leading to damage or other problems. Therefore, careful attention must be paid to their management.

[0005] In particular, when corrosive gases containing halogens such as chlorine, bromine, fluorine, and iodine are generated, it is important to avoid or suppress the events that cause their generation, but from a plant maintenance perspective, it is also necessary to suppress corrosion when such events do occur. Non-patent document 3 lists several points to note regarding corrosion caused by chlorine gas, including that halogen gases severely corrode metals at high temperatures, and that metal chlorides are generally highly volatile, so the corrosion products do not form a protective film, resulting in a high corrosion rate.

[0006] Furthermore, Non-Patent Document 4 states that while stainless steel used in plant equipment is considered to have good corrosion resistance, it is not foolproof, and even stainless steel can corrode due to various factors such as the breakdown of the passivation film and environments where passivation is not possible. In particular, Non-Patent Document 4 presents a comparison table of metal corrosion resistance performance, showing evaluation results of corrosion performance using various catalysts for various materials including cast iron, brass, stainless steel (SUS304), and aluminum. Among these, the high corrosiveness of halogens or halogen-containing compounds such as hydrogen chloride (gas), hydrochloric acid, chlorides, bromine, and iodine can be observed. However, fluorine is not highly corrosive depending on the material. Furthermore, although not a halogen, carbon dioxide (CO2) is considered to have virtually no corrosive properties.

[0007] Thus, measures against corrosion of manufacturing equipment, piping, etc., are necessary during the manufacturing process of halogens, particularly iodine-containing compounds such as iodoperfluoroalkyls, as well as during storage and use after manufacturing. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2021-075509 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2002-047240 [Non-Patent Literature]

[0009] [Non-Patent Literature 1] Website of Tosoh Finechem Corporation (URL: https: / / www.tosoh-finechem.co.jp / product / cf3i). [Non-Patent Literature 2] Chemical Physics Letters, 325, 2000. pp 399-404. [Non-Patent Literature 3] JCW Technical Document dated April 1, 2005 (Regarding Corrosion Resistance of Main Materials), Japan Cast Iron Cover and Drainage Appliance Manufacturers Association. [Non-Patent Literature 4] Takada Technical Report, Technical Description "Corrosion and Its Preventive Measures in Various Plant Facilities" Vol. 33, pp 40-52, (2023). [Summary of the Invention] [Problem to be Solved by the Invention]

[0010] An object of the present invention is, in view of the above background art, to provide a composition for suppressing corrosion of plant facilities and the like caused by iodine-containing gas, which is relatively simple and has few facility constraints, and a method for supplying the same. [Means for Solving the Problem]

[0011] The present inventors have conducted intensive studies to solve the above problem. As a result, they found that iodine causes corrosion by being ionized through one-electron reduction on a metal surface to form a metal iodide. While dilution with an inorganic gas such as nitrogen is effective for suppressing this corrosion, they also found that if the gas contains carbon dioxide, the interaction between carbon dioxide and iodine promotes corrosion. The present inventors have found that, in a composition containing an iodine-containing compound such as iodoperfluoroalkyl and a non-corrosive gas, by controlling the content of carbon dioxide to a predetermined concentration or lower, corrosion of metals used in plant equipment, piping and the like caused by iodine liberated from the iodine-containing compound is suppressed, and thus completed the present invention.

[0012] That is, the present invention relates to the following inventions. [1] A composition comprising: an iodoperfluoroalkyl; and a non-corrosive gas that may contain carbon dioxide, wherein the content of carbon dioxide in the non-corrosive gas is 50% by volume or less based on the total amount of the non-corrosive gas, and the non-corrosive gas is one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixed gas of two or more thereof, which is a metal corrosion-inhibiting composition. [2] The metal corrosion-inhibiting composition according to item [1], wherein the iodoperfluoroalkyl is one or more compounds selected from the group consisting of CF3I, C2F5I, C3F7I, CF2I2, and C2F4I2. [3] The content of iodine atoms in the composition is 1×10 -5 % by weight to 20% by weight based on the total amount of the composition, which is the metal corrosion composition according to item [1]. [4] The metal corrosion-inhibiting composition according to item [1] or [3], wherein the iodoperfluoroalkyl is CF3I, and the non-corrosive gas is nitrogen and / or dry air. [5] A method for supplying a gas consisting of a composition comprising: an iodoperfluoroalkyl; and a non-corrosive gas that may contain carbon dioxide, wherein the content of carbon dioxide in the non-corrosive gas is 50% by volume or less based on the total amount of the non-corrosive gas, the non-corrosive gas is one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixed gas of two or more thereof, and the composition is supplied to a site where iodoperfluoroalkyl is reacted or used, which is the supply method. [6] The method of supply according to item [5], wherein the iodoperfluoroalkyl is one or more compounds selected from the group consisting of CF3I, C2F5I, C3F7I, CF2I2, and C2F4I2. [7] The iodine atom content in the composition is 1 × 10 -5 The supply method described in item [5], wherein the amount is between % by weight and 20% by weight. [8] The supply method according to item [5] or item [7], wherein the iodoperfluoroalkyl is CF3I and the noncorrosive gas is nitrogen and / or dry air. [Effects of the Invention]

[0013] The present invention relates to the production and use of iodoperfluoroalkyls, and the metals that may come into contact with them. A composition and a method for supplying the corrosion of the material can be provided. [Brief explanation of the drawing]

[0014] [Figure 1] This shows the test appearance (immediately after setup), after the iodine source and test specimen have been placed in the test container and the internal gas has been replaced with the gas used for the test. The test specimen in the figure is made of SUS304, with the left side of the figure showing the result after replacing the gas with CO2 100%, and the right side showing the result after replacing the gas with N2 100%. [Figure 2] The image shows the appearance one day after the start of the test. The test specimens in the figure are made of SUS304, with the left side showing specimens replaced with 100% CO2 and the right side showing specimens replaced with 100% N2. [Figure 3] The image shows the appearance 5 days after the start of the test. The test specimens in the figure are made of SUS304, with the left side showing specimens replaced with 100% CO2 and the right side showing specimens replaced with 100% N2. [Figure 4] The image shows a photograph of the surface of a SUS304 test specimen immediately before the start of the test (top row), and then photographs of the surface of the test specimen after 5 days under CO2 and N2 conditions. The left side of the image shows the specimen after 5 days under CO2 100% at room temperature (middle left row), after 5 days under CO2 100% at 60°C (bottom left row), and the right side shows the specimen after 5 days under N2 100% at room temperature (middle right row), after 5 days under N2 100% at 60°C (bottom right row). [Figure 5]The top row shows a photograph of the surface of a SUS304 test specimen immediately before the start of the test. The middle row shows photographs of different parts of the surface of the specimen after 20 days in CO2 100% and N2, and the bottom row shows photographs of different parts of the surface of the specimen after 20 days in N2 100%. [Figure 6] The top row shows a photograph of the surface of a SUS430 test specimen immediately before the start of the test. The middle row shows photographs of different parts of the surface of the specimen after 5 days in CO2 100% and N2, and the bottom row shows photographs of different parts of the surface of the specimen after 5 days in N2 100%. [Figure 7] The top row shows a photograph of the surface of a SUS316 test specimen immediately before the start of the test. The middle row shows photographs of different parts of the surface of the test specimen after 5 days under CO2 100% conditions, and the bottom row shows photographs of different parts of the surface of the test specimen after 5 days under N2 100% conditions. [Figure 8] This is a 3D image of the surface condition of a SUS304 test specimen after testing, analyzed using a laser microscope manufactured by Keyence Corporation. The left side of the figure shows the specimen after being replaced with 100% CO2, and the right side shows the specimen after being replaced with 100% N2, at 60°C for 20 days. [Figure 9] This is a 3D image of the surface condition of a SUS430 test specimen after testing, analyzed using a laser microscope manufactured by Keyence Corporation. The left side of the figure shows the specimen after being replaced with 100% CO2, and the right side shows the specimen after being replaced with 100% N2, at 60°C for 5 days. [Figure 10] This is a 3D image of the surface condition of a SUS316 test specimen after testing, analyzed using a laser microscope manufactured by Keyence Corporation. The left side of the figure shows the specimen after being replaced with 100% CO2, and the right side shows the specimen after being replaced with 100% N2, at 60°C for 5 days. [Modes for carrying out the invention]

[0015] The present invention will be described in detail below.

[0016] <Metal corrosion inhibitory composition> The metal corrosion inhibitory composition of the present invention comprises an iodoperfluoroalkyl group and a non-corrosive gas which may contain carbon dioxide. The carbon dioxide content in this non-corrosive gas containing carbon dioxide is 50% by volume or less of the total amount of the non-corrosive gas. The non-corrosive gas component is one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixture of two or more gases. It is a composition.

[0017] In this invention, a metal corrosion-inhibiting composition refers to an agent that inhibits metal corrosion caused by iodine released from an iodine-containing compound. Iodine ionizes on the metal surface through one-electron reduction, forming metal iodides and causing corrosion. The presence of carbon dioxide accelerates this corrosion. Generally, dilution with inorganic gases such as nitrogen is effective in suppressing metal corrosion caused by iodine released from iodine-containing compounds. However, this invention presents a new problem: metal corrosion caused by iodine released from iodine-containing compounds is accelerated by carbon dioxide. It is necessary to control the concentration of carbon dioxide, which may be present in the inorganic gas, to below a predetermined amount. By deriving a means to solve this problem, it was found that this can be used as an agent to suppress metal corrosion caused by iodine released from iodine-containing compounds.

[0018] In particular, when iodine (I2) generated from iodine-containing compounds corrodes metals, the corrosion is accelerated by carbon dioxide (CO2). Furthermore, in industrial fields such as chemical plants, high-temperature operation is expected, which could further accelerate the corrosion, making corrosion suppression important. Furthermore, in piping, chemical equipment, etc., not only surface corrosion but also corrosion progressing deep from the metal surface into the interior, even if only in small quantities, can cause damage to the piping, chemical equipment, etc., and should be constantly monitored. For this reason, it is important to prevent corrosion from progressing as much as possible, or in other words, to suppress corrosion.

[0019] In the present invention, iodoperfluoroalkyl is one or more compounds selected from the group consisting of CF3I, C2F5I, C3F7I, CF2I2, and C2F4I2. The inventors of this invention have found that iodine released from iodine-containing compounds ionizes on metal surfaces through one-electron reduction, forming metallic iodides and causing corrosion. They also discovered that the presence of carbon dioxide accelerates this corrosion. Therefore, this invention addresses the problem of suppressing corrosion caused by iodine-containing compounds from which iodine is released, and proposes an invention to solve this problem. Therefore, the target iodoperfluoroalkyl is one or more compounds selected from the group consisting of CF3I, C2F5I, C3F7I, CF2I2, and C2F4I2, and more preferably CF3I or other iodoperfluoroalkyl produced in the manufacturing process of CF3I.

[0020] In the present invention, a non-corrosive gas is a gas used to suppress metal corrosion by diluting the iodine released from an iodine-containing compound, in order to suppress corrosion caused by the iodine-containing compound from which iodine is released. Specifically, from the viewpoint of gas composition, it is preferable to use one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixture of two or more gases. Of these, nitrogen or dry air is preferred from the viewpoint of economy.

[0021] Furthermore, since carbon dioxide accelerates this metal corrosion, it is preferable that the gas contains no carbon dioxide or that it makes up 50% or less of the total volume of non-corrosive gas. In addition, if carbon dioxide is present in the gas, considering the burden of removing the carbon dioxide and the challenges related to removal treatment, and based on ease of acquisition and economic efficiency, the ranges of 0.0001 to 50% by volume, 0.001 to 50% by volume, 0.01 to 50% by volume, 0.001 to 30% by volume, 0.0001 to 30% by volume, 0.0001 to 20% by volume, 0.001 to 20% by volume, and 0.01 to 20% by volume are preferable.

[0022] Further, the metal corrosion inhibiting composition of the present invention - The iodoperfluoroalkyl contained in the composition is CF3I, and - the non-corrosive gas contained in the composition is nitrogen and / or dry air, is preferable.

[0023] In the present invention, the content of iodine atoms in the metal corrosion inhibiting composition is 1×10 -5 wt% to 20 wt%, preferably 1×10 -4 wt% to 20 wt%, 1×10 -3 wt% to 20 wt%, 1×10 -5 wt% to 10 wt%, 1×10 -4 wt% to 10 wt%, 1×10 -3 wt% to 10 wt%, 1×10 -5 wt% to 5 wt%, 1×10 -4 wt% to 5 wt%, 1×10 -3 wt% to 5 wt%, 1×10 -4 wt% to 1 wt%, 1×10 -3 wt% to 1 wt% is preferred.

[0024] <Method for supplying metal corrosion inhibiting composition> The method for supplying a metal corrosion inhibiting composition of the present invention is a method for delivering a gas consisting of a composition containing iodoperfluoroalkyl and a non-corrosive gas which may contain carbon dioxide, wherein the content of carbon dioxide in the non-corrosive gas contained in the composition is 50% by volume or less of the total amount of the non-corrosive gas, the non-corrosive gas is one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixed gas of two or more thereof, and the composition is supplied to a site where iodoperfluoroalkyl is reacted or used, relating to said delivery method.

[0025] In the present invention, the metal corrosion inhibiting composition refers to an agent that suppresses metal corrosion caused by iodine liberated from an iodine-containing compound, as described above.

[0026] In the present invention, iodoperfluoroalkyl is one or more compounds selected from the group consisting of CF3I, C2F5I, C3F7I, CF2I2, and C2F4I2, and more preferably CF3I or other iodoperfluoroalkyls produced in the manufacturing process of CF3I.

[0027] Iodoperfluoroalkyls are supplied to the sites where they are reacted or used, i.e., the reaction sites, and also to designated storage or retention locations within those sites. Iodine-containing compounds such as iodoperfluoroalkyls have applications as chemical raw materials, refrigerants, fumigants, fire extinguishing agents, and cover gases during alloy casting. Therefore, iodoperfluoroalkyls are supplied to the sites where these materials are synthesized and used, i.e., factories. As for the supply method, the metal corrosion inhibitory composition manufactured by the present invention can be supplied directly via piping or the like. Alternatively, the metal corrosion inhibitory composition can be temporarily filled into a cylinder or the like, and then the cylinder or the like can be moved to the location where the material for the intended use is synthesized or used.

[0028] In the present invention, a non-corrosive gas is a gas used to suppress metal corrosion by diluting the iodine released from an iodine-containing compound, in order to suppress corrosion caused by the iodine-containing compound from which iodine is released. Specifically, from the viewpoint of gas composition, it is preferable to use one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixture of two or more gases. Of these, nitrogen or dry air is preferred from the viewpoint of economy.

[0029] Furthermore, since carbon dioxide accelerates this metal corrosion, it is preferable that the gas contains no carbon dioxide or that it makes up 50% or less of the total volume of non-corrosive gas. In addition, if carbon dioxide is present in the gas, considering the burden of removing the carbon dioxide and the challenges related to removal treatment, and based on ease of acquisition and economic efficiency, the ranges of 0.0001 to 50% by volume, 0.001 to 50% by volume, 0.01 to 50% by volume, 0.001 to 30% by volume, 0.0001 to 30% by volume, 0.0001 to 20% by volume, 0.001 to 20% by volume, and 0.01 to 20% by volume are preferable.

[0030] Furthermore, the metal corrosion inhibitory composition in the present invention is • The iodoperfluoroalkyl contained in the composition is CF3I, • The non-corrosive gas contained in the composition is nitrogen and / or dry air. It is preferable.

[0031] In the present invention, the iodine atom content in the metal corrosion inhibitory composition is 1 × 10¹⁶ of the total amount of the composition. -5 Preferably % by weight to 20% by weight, 1 × 10 -4 Weight%~20weight%, 1×10 -3 Weight%~20weight%, 1×10 -5 Weight%~10weight%, 1×10 -4 Weight%~10weight%, 1×10 -3 Weight%~10weight%, 1×10 -5 wt%~5wt%, 1×10 -4 wt%~5wt%, 1×10 -3 wt%~5wt%, 1×10 -4 wt%~1wt%, 1×10 -3 A range of % by weight to 1% by weight is preferred.

[0032] The metal corrosion-inhibiting composition of the present invention can suppress the corrosion of metals, and the target metal is not particularly limited as long as the effects of the present invention are observed. In particular, it can contribute to the suppression of rust even in the presence of corrosive gases on steels that are resistant to rust, such as stainless steel.

[0033] For example, it is preferably used in equipment that uses stainless steel, which is an alloy steel that has corrosion resistance due to the inclusion of a certain amount or more of chromium, nickel, etc., in iron. Examples of stainless steels include martensitic stainless steels such as SUS410, ferritic stainless steels such as SUS430, austenitic stainless steels such as SUS304, SUS316, and SUS316L, austenitic-ferritic stainless steels (duplex) such as SUS329, and precipitation-hardening stainless steels such as SUS631. Among these, austenitic materials such as SUS304, which has a composition of 18%Cr-8%Ni and is widely used in chemical plant equipment, and SUS316, which has a composition of 18Cr-12Ni-2.5Mo and has excellent corrosion resistance to seawater, are preferred, as are ferritic materials such as SUS430, which has a composition of 18%Cr and is versatile for use in building interiors, household appliances, and home appliances. [Examples]

[0034] Examples of the present invention are shown below, but the present invention is not limited to these examples.

[0035] The conditions for the corrosion test and the materials used were as follows. <Materials used> Iodine source: Spheroidal iodine, Fujifilm Wako Pure Chemical Industries, Ltd., Reagent grade Test specimens: SUS304(B), 2.0mm x 10mm x 40mm, manufactured by Standard Test Piece Co., Ltd.; SUS430(B), 2.0mm x 10mm x 40mm, manufactured by Standard Test Piece Co., Ltd.; SUS316(B), 2.0mm x 10mm x 40mm, manufactured by Standard Test Piece Co., Ltd.

[0036] <Testing Method> The corrosion caused by iodine released when a portion of an iodine-containing compound decomposes was simulated as shown below. • Test container An iodine source, placed on a plastic dish, was set aside at the bottom of a 30 mL glass vial (with a plastic lid), and the test specimen was placed upright inside the container. The glass vial was then capped and sealed with sealing tape. The test specimens and iodine source were placed in the test container at room temperature without protection from light. Furthermore, tests were also conducted at 60°C for 5 or 20 days for 100% CO2 and 100% N2. • Gas filling method The test specimen and iodine source were placed in a test container, and various gases used in the test were injected under conditions of being exposed to the atmosphere, replacing the internal gas. At this time, the partial pressure of iodine was 400 ppm by volume (400 μL of volatilized iodine gas per liter).

[0037] Figures 1 to 10 show the appearance of the test setup. Figure 1: The test specimens were prepared immediately after being replaced with the specified gas as described in the gas filling method above. In the figure, all test specimens are made of SUS304 stainless steel; the one on the left is filled with carbon dioxide (CO2), and the one on the right is filled with nitrogen (N2). Figure 2: The test containers were left at room temperature without light protection for one day immediately after preparation. Visual inspection of the surface of the SUS304 test specimens revealed that the specimen filled with carbon dioxide (CO2) showed some discoloration on its surface, while the specimen filled with nitrogen (N2) showed little change. Figure 3: The test containers were left at room temperature without light protection for 5 days immediately after preparation. Visual inspection of the surface of the SUS304 test specimens revealed that the entire surface of the specimen filled with carbon dioxide (CO2) was discolored, while the specimen filled with nitrogen (N2) was only partially discolored. Figure 4: Surface photographs of SUS304 test specimens after being left in a test container at room temperature or 60°C without light protection for 5 days immediately after preparation. Figure 5: Surface photograph of a SUS304 test specimen after being left in a test container at 60°C and without light protection for 20 days immediately after preparation. Figure 6: Surface photograph of a test container that was replaced with a specified gas using the gas filling method described above, with a test specimen made of SUS430, and subjected to a 5-day test at 60°C without light shielding. Figure 7: Surface photograph of a test container that was replaced with a predetermined gas using the gas filling method described above, with a test specimen made of SUS316, and subjected to a 5-day test at 60°C without light shielding. Figure 8 is a 3D image of the surface condition of the SUS304 test specimen after the test shown in Figure 5, analyzed using a laser microscope manufactured by Keyence Corporation. Figure 9 is a 3D image of the surface condition of the SUS430 test specimen after the test shown in Figure 6, analyzed using a laser microscope manufactured by Keyence Corporation. Figure 10 is a 3D image of the surface condition of the SUS316 test specimen after the test shown in Figure 7, analyzed using a laser microscope manufactured by Keyence Corporation.

[0038] As shown in Figures 4 and 5, a visual inspection of the SUS304 test specimens revealed that the specimens filled with carbon dioxide (CO2) showed a clear overall discoloration of the entire surface compared to those left at room temperature, and some deep corrosion marks were observed in certain areas. Furthermore, as shown in Figure 5, the surfaces of all three different locations on the sample filled with carbon dioxide (CO2) are rough, clearly indicating that corrosion is progressing. In contrast, the samples filled with nitrogen (N2) showed only slight discoloration compared to those left at room temperature. Furthermore, while there are some areas where corrosion has progressed slightly in the nitrogen (N2)-filled section, it is clear that overall the corrosion has not progressed significantly. Furthermore, the 3D image (Figure 8) of the surface condition of the SUS304 test specimens after the test, as shown in Figure 5, was analyzed using a laser microscope. The results were similar to those observed visually in Figure 5, with deep corrosion marks observed in the specimen placed in carbon dioxide (CO2). In contrast, the specimen placed in nitrogen (N2) had a uniform surface with almost no corrosion marks.

[0039] As shown in Figure 6, a visual inspection of the surface of the SUS430 test specimen revealed that the specimen filled with carbon dioxide (CO2) showed a clear discoloration across the entire surface compared to the specimen left at room temperature before the test. This is attributed to corrosion. In contrast, the sample filled with nitrogen (N2) showed almost no discoloration compared to the surface condition of the test specimen before the test, while the sample placed at 60°C showed almost no discoloration. The 3D image (Figure 9) of the surface condition of the SUS430 test specimens after the test, as shown in Figure 6, was analyzed using a laser microscope. The results were similar to those observed visually in Figure 6. The specimen placed in carbon dioxide (CO2) had an uneven surface, indicating that corrosion had roughened the surface and made it uneven. In contrast, the specimen placed in nitrogen (N2) had a uniform surface with almost no signs of corrosion.

[0040] As shown in Figure 7, a visual inspection of the surface of the SUS316 test specimen revealed that the specimen filled with carbon dioxide (CO2) showed a clear discoloration across the entire surface compared to the specimen left at room temperature before the test. This is attributed to corrosion. In contrast, the sample filled with nitrogen (N2) showed almost no discoloration compared to the surface condition of the test specimen before the test, while the sample placed at 60°C showed almost no discoloration. The 3D image (Figure 10) of the surface condition of the SUS316 test specimen after the test, as shown in Figure 7, was analyzed using a laser microscope and showed similar findings to the visual observation in Figure 7. The specimen placed in carbon dioxide (CO2) had an uneven surface, indicating that corrosion had roughened the surface and made it uneven. In contrast, the specimen placed in nitrogen (N2) had a uniform surface with almost no signs of corrosion. As described above, metal corrosion caused by I2 is accelerated by the presence of carbon dioxide (CO2), and further accelerated at high temperatures.

[0041] The following gases were used in the test. • Example 1; Nitrogen gas Example 2; Dry air (0.041% by volume of carbon dioxide) • Example 3: Gas containing 20% ​​carbon dioxide and 80% nitrogen by volume • Example 4; Gas containing 50% by volume of carbon dioxide and 50% by volume of nitrogen • Example 5: Nitrogen gas (stored at 60°C for 20 days) • Example 6: Nitrogen gas (stored at 60°C for 5 days) • Example 7: Nitrogen gas (stored at 60°C for 5 days) • Comparative Example 1; Carbon Dioxide Gas Comparative Example 2: Carbon dioxide gas (stored at 60°C for 20 days) Comparative Example 3: Carbon dioxide gas (stored at 60°C for 5 days) Comparative Example 4: Carbon dioxide gas (stored at 60°C for 5 days)

[0042] Example 1 A SUS304 test piece (2.0 mm x 10 mm x 40 mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30 mL glass vial, and the atmosphere was set to nitrogen gas containing 400 ppm by volume of iodine. The surface of the test specimens was visually inspected at room temperature immediately after preparation, after 1 day, after 5 days, and after acetone washing. The following changes were observed. • The surface of the test specimen after the test container had been left for one day showed little change compared to immediately after preparation. • After leaving the test container for 5 days, the surface of the test specimen showed only partial discoloration compared to immediately after preparation. • After leaving the test container for 5 days, the test specimen was washed with acetone and dried, but the surface only showed partial discoloration, becoming whitish in some areas, compared to immediately after preparation. The weight change of the test specimen was measured. The difference between the weight before the test (5.8875g) and the weight after the test (5.8859g) was a decrease of 0.0016g (equivalent to 0.03%). When the volume of the test specimen was measured, it remained at 1.8 mm × 10 mm × 40 mm both before and after the test, and no increase or decrease in volume was observed. From the above results, although slight corrosion was observed in the test specimen in Example 1, the weight difference after removing the corroded portion was negligible, and no volume reduction was observed. This indicates that the corrosion resistance of the test specimen was good under the atmospheric conditions of Example 1.

[0043] Example 2 A SUS304 test piece (2.0 mm x 10 mm x 40 mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30 mL glass vial, and the atmosphere was set to dry air containing 400 ppm by volume of iodine. The surface of the test specimens was visually inspected at room temperature immediately after preparation, after 1 day, after 5 days, and after acetone washing. The following changes were observed. • The surface of the test specimen after leaving the test container for one day had become slightly whiter compared to immediately after preparation. • After leaving the test container for 5 days, the surface of the test specimen showed only partial discoloration compared to immediately after preparation. • After leaving the test container for 5 days, the test specimen was washed with acetone and dried, but the surface only showed partial discoloration, becoming whitish in some areas, compared to immediately after preparation. The weight change of the test specimen was measured. The difference between the weight before the test (5.8598g) and the weight after the test (5.888g) was a decrease of 0.0010g (equivalent to 0.02%). When the volume of the test specimen was measured, it remained at 1.8 mm × 9.9 mm × 40 mm both before and after the test, indicating no increase or decrease in volume. From the above results, although slight corrosion was observed in the test specimen in Example 2, the weight difference after removing the corroded portion was negligible, and no volume reduction was observed. This indicates that the corrosion resistance of the test specimen was good under the atmospheric conditions of Example 2.

[0044] Example 3 A SUS304 test piece (2.0 mm x 10 mm x 40 mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30 mL glass vial, and the atmosphere was purged with a gas containing 20% ​​by volume carbon dioxide and 80% by volume nitrogen, followed by an atmosphere containing 400 ppm by volume iodine. The surface of the test specimens was visually inspected at room temperature immediately after preparation, after 1 day, after 5 days, and after acetone washing. The following changes were observed. • The surface of the test specimen after leaving the test container for one day had become slightly whiter compared to immediately after preparation. • After leaving the test container for 5 days, the surface of the test specimen showed only partial discoloration compared to immediately after preparation. • After leaving the test container for 5 days, the test specimen was washed with acetone and dried, but the surface only showed partial discoloration, becoming whitish in some areas, compared to immediately after preparation. The weight change of the test specimen was measured. The difference between the weight before the test (5.8831g) and the weight after the test (5.8816g) was a decrease of 0.0015g (equivalent to 0.03%). When the volume of the test specimen was measured, it remained at 1.8 mm × 9.9 mm × 40 mm both before and after the test, indicating no increase or decrease in volume. From the above results, although slight corrosion was observed in the test specimen in Example 3, the weight difference after removing the corroded portion was negligible, and no volume reduction was observed. This indicates that the corrosion resistance of the test specimen was good under the atmospheric conditions of Example 3.

[0045] Example 4 A SUS304 test piece (2.0 mm x 10 mm x 40 mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30 mL glass vial, and the vial was purged with a gas containing 50% by volume of carbon dioxide and 50% by volume of nitrogen, followed by an atmosphere containing 400 ppm by volume of iodine. The surface of the test specimens was visually inspected at room temperature immediately after preparation, after 1 day, after 5 days, and after acetone washing. The following changes were observed. • The surface of the test specimen after leaving the test container for one day had become slightly whiter compared to immediately after preparation. • After leaving the test container for 5 days, the surface of the test specimen showed only partial discoloration compared to immediately after preparation. • After leaving the test container for 5 days, the test specimen was washed with acetone and dried, but the surface only showed partial discoloration, becoming whitish in some areas, compared to immediately after preparation. The weight change of the test specimen was measured. The difference between the weight before the test (5.8829g) and the weight after the test (5.8819g) was a decrease of 0.0010g (equivalent to 0.02%). When the volume of the test specimen was measured, it remained at 1.8 mm × 9.9 mm × 40 mm both before and after the test, indicating no increase or decrease in volume. From the above results, although slight corrosion was observed in the test specimen in Example 4, the weight difference after removing the corroded portion was negligible, and no volume reduction was observed. This indicates that the corrosion resistance of the test specimen was good under the atmospheric conditions of Example 4.

[0046] Example 5 A SUS304 test piece (1.9mm x 9.9mm x 39.9mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30mL glass vial, and the atmosphere was set to a nitrogen gas atmosphere containing 400 volume ppm of iodine. The test specimens were prepared at room temperature, then left at 60°C for 20 days, and the surface of the specimens was visually inspected after washing with acetone. The following changes were observed. • The test container showed only a slight discoloration, appearing whitish in some areas, compared to immediately after preparation in Example 1. When the weight change of the test specimen was measured, the difference between the weight before the test (6.1641g) and the weight after the test (6.1297g) was a decrease of 0.0344g (equivalent to 0.56%). When the volume of the test specimen was measured, it remained at 1.9 mm × 9.9 mm × 39.9 mm both before and after the test, indicating no increase or decrease in volume. Furthermore, the surface of the test specimen was analyzed using a Keyence laser microscope. The arithmetic mean roughness was 0.66 μm, the root mean square roughness was 0.88 μm, and the maximum depth was 20.06 μm. Here, the arithmetic mean roughness represents the average degree of surface irregularity, and the root mean square roughness represents the variation in depth, i.e., the standard deviation. Both values, including the maximum depth, are large when corrosion is severe. From the results above, in Example 5, slight corrosion was observed in the test specimen compared to before preparation. However, as shown in Figure 5, there were areas on the surface where corrosion had not progressed, and overall, the progression of corrosion was more suppressed or slower than in an atmosphere containing carbon dioxide (CO2). Furthermore, although the weight difference after removing the corroded portion decreased compared to before preparation, no volume reduction was observed. However, from the surface observations in Figures 4 and 5 and the surface analysis using a laser microscope in Figure 8, it can be seen that the corrosion resistance of the test specimen under the atmospheric conditions of Example 5 was better than that of Comparative Example 2. In other words, it is clear that a 100% nitrogen atmosphere has the effect of suppressing the progression of metal corrosion compared to an atmosphere containing carbon dioxide (CO2).

[0047] Example 6 A SUS430 test piece (1.8 mm × 10.1 mm × 40.1 mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30 mL glass vial, and the atmosphere was set to nitrogen gas containing iodine at 400 volume ppm. The test specimens were prepared at room temperature, then left at 60°C for 5 days, and the surface of the specimens was visually inspected after washing with acetone. The following changes were observed. When the weight change of the test specimen was measured, the difference between the weight before the test (5.7164g) and the weight after the test (5.6930g) was a decrease of 0.0234g (equivalent to 0.41%). When the volume of the test specimen was measured, it remained at 1.8 mm × 10.1 mm × 40.1 mm both before and after the test, indicating no increase or decrease in volume. Furthermore, the surface of the specimen was analyzed using a Keyence laser microscope. The arithmetic mean roughness was 0.70 μm, the root mean square roughness was 0.92 μm, and the maximum depth was 17.63 μm. From the above results, slight corrosion was observed in the test specimen in Example 6 compared to before preparation. However, as shown in Figure 6, the overall progression of corrosion was more suppressed or slower than in the atmosphere containing carbon dioxide (CO2). Furthermore, although the weight difference after removing the corroded portion decreased compared to before preparation, no volume reduction was observed. However, from the surface observation in Figure 6 and the surface analysis by laser microscopy in Figure 9, it can be seen that the corrosion resistance of the test specimen under the atmospheric conditions of Example 6 was better than that of Comparative Example 3. In other words, it is clear that a 100% nitrogen atmosphere has the effect of suppressing the progression of metal corrosion compared to an atmosphere containing carbon dioxide (CO2).

[0048] Example 7 A SUS316 test piece (1.9mm x 9.9mm x 40.0mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30mL glass vial, and the atmosphere was set to a nitrogen gas atmosphere containing 400 volume ppm of iodine. The test specimens were prepared at room temperature, then left at 60°C for 5 days, and the surface of the specimens was visually inspected after washing with acetone. The following changes were observed. When the weight change of the test specimen was measured, the difference between the weight before the test (6.0072g) and the weight after the test (5.9800g) was a decrease of 0.0272g (equivalent to 0.45%). When the volume of the test specimen was measured, it remained at 1.9 mm × 9.9 mm × 40.0 mm both before and after the test, indicating no increase or decrease in volume. Furthermore, the surface of the specimen was analyzed using a Keyence laser microscope. The arithmetic mean roughness was 1.00 μm, the root mean square roughness was 1.32 μm, and the maximum depth was 19.03 μm. From the results above, slight corrosion was observed in the test specimens in Example 7 compared to before preparation. However, as shown in Figure 7, the overall progression of corrosion was more suppressed or slower than in the atmosphere containing carbon dioxide (CO2). Furthermore, although the weight difference after removing the corroded portion decreased compared to before preparation, no volume reduction was observed. However, from the surface observation in Figure 7 and the surface analysis by laser microscopy in Figure 10, it can be seen that the corrosion resistance of the test specimen under the atmospheric conditions of Example 7 was better than that of Comparative Example 4. In other words, it is clear that a 100% nitrogen atmosphere has the effect of suppressing the progression of metal corrosion compared to an atmosphere containing carbon dioxide (CO2).

[0049] Comparative Example 1 A SUS304 test piece (2.0 mm x 10 mm x 40 mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30 mL glass vial, and the atmosphere was set to carbon dioxide containing 400 volume ppm of iodine. The surface of the test specimens was visually inspected at room temperature immediately after preparation, after 1 day, after 5 days, and after acetone washing. The following changes were observed. • The surface of the test specimen after leaving the test container for one day had turned whitish compared to immediately after preparation. • The surface of the test specimen after the test container had been left for 5 days had turned black compared to immediately after preparation. • After leaving the test container for 5 days, the test specimen was washed with acetone and dried. The surface of the specimen had turned whitish overall compared to when it was immediately after preparation. The weight change of the test specimen was measured. The difference between the weight before the test (5.8840g) and the weight after the test (5.8805g) was a decrease of 0.0035g (equivalent to 0.06%). When the volume of the test specimen was measured, it remained at 1.8 mm × 10.0 mm × 40 mm both before and after the test, indicating no increase or decrease in volume.

[0050] Comparative Example 2 A SUS304 test piece (1.9mm x 9.9mm x 39.9mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30mL glass vial, and the atmosphere was set to carbon dioxide gas containing iodine at 400 volume ppm. The test specimens were prepared at room temperature, then left at 60°C for 60 days. After washing with acetone, the surface of the specimens was visually inspected. The following changes were observed. Compared to the test container immediately after preparation in Comparative Example 1, the entire surface of the test container was discolored, and a clear pattern resembling corrosion had appeared. The weight change of the test specimen was measured. The difference between the weight before the test (6.1400g) and the weight after the test (6.0994g) was a decrease of 0.0406g (equivalent to 0.66%). When the volume of the test specimen was measured, it remained at 1.9 mm × 9.9 mm × 39.9 mm both before and after the test, indicating no increase or decrease in volume. Furthermore, the surface of the specimen was analyzed using a Keyence laser microscope. The arithmetic mean roughness was 2.20 μm, the root mean square roughness was 3.53 μm, and the maximum depth was 61.23 μm. From the above results, it was observed that the test specimen in Comparative Example 2 showed considerable corrosion compared to before preparation. Furthermore, the weight difference after removing the corroded portion was considerably reduced compared to before preparation, indicating a volume reduction. This indicates that under the atmospheric conditions of Comparative Example 2, the corrosion resistance of the test specimen was more advanced compared to Example 5. Furthermore, the results in Figure 5 clearly show that corrosion has progressed considerably at all points on the surface of the test specimen. Considering the difference in weight and volume of the test specimen before and after the test, it is thought that corrosion progresses from the metal surface under the conditions of this test, and the extent of this corrosion is clearly shown in the surface images (Figures 4 and 5) and the surface analysis results by laser microscopy (Figure 8).

[0051] Comparative Example 3 A SUS430 test piece (1.8 mm × 10.1 mm × 40.1 mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30 mL glass vial, and the atmosphere was set to carbon dioxide gas containing iodine at 400 volume ppm. The test specimens were prepared at room temperature, then left at 60°C for 5 days, and the surface of the specimens was visually inspected after washing with acetone. The following changes were observed. The weight change of the test specimen was measured. The difference between the weight before the test (5.7113g) and the weight after the test (5.6811g) was a decrease of 0.0302g (equivalent to 0.53%). When the volume of the test specimen was measured, it remained at 1.8 mm × 10.1 mm × 40.1 mm both before and after the test, indicating no increase or decrease in volume. Furthermore, the surface of the specimen was analyzed using a Keyence laser microscope. The arithmetic mean roughness was 1.39 μm, the root mean square roughness was 1.72 μm, and the maximum depth was 20.27 μm. From the above results, it was observed that the test specimen in Comparative Example 2 showed considerable corrosion compared to before preparation. Furthermore, the weight difference after removing the corroded portion was considerably reduced compared to before preparation, indicating a volume reduction. This indicates that under the atmospheric conditions of Comparative Example 2, the corrosion resistance of the test specimen was more advanced compared to Example 6. Furthermore, the results in Figure 6 clearly show that corrosion has progressed considerably at all points on the surface of the test specimen. Considering the difference in weight and volume of the test specimen before and after the test, it is thought that corrosion progresses from the metal surface under the conditions of this test, and the extent of this corrosion is clearly shown in the surface image (Figure 6) and the surface analysis results by laser microscopy (Figure 9).

[0052] Comparative Example 4 A SUS316 test piece (1.9 mm × 10.0 mm × 40.0 mm, manufactured by Standard Test Piece Co., Ltd.) was placed in a 30 mL glass vial, and the atmosphere was set to carbon dioxide gas containing iodine at 400 volume ppm. The test specimens were prepared at room temperature, then left at 60°C for 5 days, and the surface of the specimens was visually inspected after washing with acetone. The following changes were observed. When the weight change of the test specimen was measured, the difference between the weight before the test (6.0060g) and the weight after the test (5.9779g) was a decrease of 0.0281g (equivalent to 0.47%). When the volume of the test specimen was measured, it remained at 1.9 mm × 10.0 mm × 40.0 mm both before and after the test, indicating no increase or decrease in volume. Furthermore, the surface of the specimen was analyzed using a Keyence laser microscope. The arithmetic mean roughness was 2.55 μm, the root mean square roughness was 3.26 μm, and the maximum depth was 36.31 μm. From the above results, it was observed that the test specimen in Comparative Example 4 showed considerable corrosion compared to before preparation. Furthermore, the weight difference after removing the corroded portion was considerably reduced compared to before preparation, indicating a volume reduction. This indicates that under the atmospheric conditions of Comparative Example 4, corrosion progressed more rapidly compared to Example 7. Furthermore, the results in Figure 7 clearly show that corrosion has progressed considerably at all points on the surface of the test specimen. Considering the difference in weight and volume of the test specimen before and after the test, it is thought that corrosion progresses from the metal surface under the conditions of this test, and the extent of this corrosion is clearly shown in the surface image (Figure 7) and the surface analysis results by laser microscopy (Figure 10).

[0053] From the above results, the test specimens in Comparative Examples 1-4 showed significantly more corrosion compared to the Examples. The weight difference after removing the corroded portion also decreased significantly compared to the Examples. However, no volume reduction was observed. From this, it can be seen that corrosion progressed on the test specimens under the atmospheric conditions of Comparative Examples 1-4. Although there was almost no change in the volume of the test specimens before and after the experiment, similar to the Examples, this is because, although corrosion progressed on the surface in this test, there was almost no change in volume even after removing the corroded portion, and only the weight changed. In fact, changes in the surface condition were confirmed by measurement using a laser microscope. However, these tests were conducted over periods of 5 and 20 days, and it is clear that significant corrosion would occur in plant equipment and other facilities operating over several years or more. Therefore, as shown in the examples, the fact that almost no weight difference was observed during this test period, demonstrating a corrosion-inhibiting effect, indicates that it is beneficial for the maintenance and management of manufacturing equipment. [Industrial applicability]

[0054] The present invention provides a composition and supply method that suppresses the corrosion of metals that may come into contact with iodoperfluoroalkyls during their production and use, and is industrially useful.

Claims

1. A composition comprising an iodoperfluoroalkyl group and a non-corrosive gas that may contain carbon dioxide, The carbon dioxide content in the noncorrosive gas is 50% by volume or less of the total amount of the noncorrosive gas. The non-corrosive gas is one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixture of two or more gases. Metal corrosion inhibitory composition.

2. Iodoperfluoroalkyl is CF ３ I, C ２ F ５ I, C ３ F ７ I, CF ２ I ２ , and C ２ F ４ I ２ The corrosion inhibiting composition for metals according to claim 1, which is one or more compounds selected from the group consisting of:

3. The iodine atom content in the composition is 1 × 10⁻¹⁶ of the total amount of the composition. －５ The metal corrosion composition according to claim 1, wherein the concentration is between % by weight and 20% by weight.

4. Iodoperfluoroalkyl is CF ３ The metal corrosion inhibitory composition according to claim 1 or claim 3, wherein the non-corrosive gas is nitrogen and / or dry air.

5. A method for supplying a gas comprising a composition containing an iodoperfluoroalkyl and a non-corrosive gas that may contain carbon dioxide, The carbon dioxide content in the noncorrosive gas is 50% by volume or less of the total amount of the noncorrosive gas. The non-corrosive gas is one gas selected from the group consisting of nitrogen, dry air, helium, neon, and argon, or a mixture of two or more gases. The composition is supplied to the site where the iodoperfluoroalkyl is reacted or used. Supply method.

6. Iodoperfluoroalkyl, CF ３ I, C ２ F ５ I, C ３ F ７ I, CF ２ I ２ , and C ２ F ４ I ２ The supply method according to claim 5, wherein the compound is one or more compounds selected from the group consisting of the following.

7. The iodine atom content in the composition is 1 × 10 －５ The supply method according to claim 5, wherein the amount is between % by weight and 20% by weight.

8. Iodoperfluoroalkyl is CF ３ The supply method according to claim 5 or 7, wherein I is and the non-corrosive gas is nitrogen and / or dry air.

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