Solvent composition and method for cleaning articles using the same

Abstract

To provide a solvent composition that prevents rust from occurring in a cleaning object or a cleaning device and contains 1-chloro-2,3,3-trifluoro-1-propene.SOLUTION: A solvent composition contains 1-chloro-2,3,3-trifluoro-1-propene and nitromethane, and the content of the nitromethane is 0.6-3 mass% relative to the total mass of the solvent composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a solvent composition and a method for cleaning articles using the same, as well as a cleaning solvent combination product comprising the solvent composition. [Background technology]

[0002] In the manufacturing process, assembly process, and final finishing process of articles such as precision metal processing parts, optical parts, electronic parts, semiconductor manufacturing equipment, and plated parts, dirt such as oil and dust adhering to the articles is removed by cleaning with an organic solvent. As the organic solvent used for such cleaning, fluoroolefin organic solvents are used which are non-flammable, have little effect on the human body, and have low global warming potential and ozone depletion potential (Patent Documents 1 to 4). Although fluoroolefin organic solvents have little impact on the global environment, they are known to be easily decomposed. For example, Patent Documents 1 to 3 describe additives that can stabilize 1-chloro-2,3,3-trifluoro-1-propene (hereinafter, sometimes referred to as "HCFO-1233yd"), which is a type of fluoroolefin organic solvent.

[0003] In addition, since fluoroolefin-based organic solvents are expensive, for example, when cleaning items using a cleaning device equipped with a steam tank, the organic solvent vaporized in the steam tank is cooled and collected for reuse. On the other hand, if moisture in the air gets mixed in during cooling, rust will form on the object to be cleaned or the cleaning device. Patent Document 4 describes an additive that can suppress rust formation even when water gets mixed in a cleaning solution containing 1-chloro-3,3,3-trifluoro-1-propene, a type of fluoroolefin-based organic solvent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 122801 [Patent Document 2] International Publication No. 2017 / 122802 [Patent Document 3] International Publication No. 2017 / 122803 [Patent Document 4] JP 2018-9113 A Summary of the Invention [Problem to be solved by the invention]

[0005] Although 1-chloro-3,3,3-trifluoro-1-propene has advantages such as a small impact on the global environment, the boiling point is low at 39°C for the Z isomer and 21°C for the E isomer, so the steam cleaning temperature cannot be set high, and in order to obtain an efficient cleaning effect in steam cleaning, the use of a fluoroolefin-based organic solvent with a higher boiling point is required. HCFO-1233yd has a high boiling point of 48 to 54°C, and when performing steam cleaning, cleaning can be performed at a higher temperature, so the cleaning effect is high, but since the temperature is high, measures against rust generation due to water mixed into the cleaning solution become more important. However, since the physical properties of fluoroolefin-based organic solvents differ depending on the type, no additives that can suppress the generation of rust on the object to be cleaned were known regardless of the type of fluoroolefin-based organic solvent used. Therefore, the object of the present invention is to provide a solvent composition containing HCFO-1233yd in which the generation of rust on the object to be cleaned or the cleaning device is suppressed. [Means for solving the problem]

[0006] As a result of intensive research aimed at solving the above problems, the present inventors discovered that the addition of nitromethane to a solvent composition containing HCFO-1233yd inhibits the generation of rust, and thus completed the present invention. That is, the present invention provides the following solvent composition and a method for cleaning articles using the same, as well as a combination cleaning solvent product containing the solvent composition. [1] A solvent composition comprising 1-chloro-2,3,3-trifluoro-1-propene and nitromethane, A solvent composition, wherein the content of the nitromethane is 0.6 to 3 mass % based on the total mass of the solvent composition. [2] The solvent composition according to [1] above for cleaning an article. [3] The solvent composition according to [2], wherein the article comprises at least one metal selected from the group consisting of iron, copper, aluminum, and alloys thereof, and / or a ceramic of an oxide, nitride, or carbide. [4] A method for cleaning an article, comprising the steps of: providing a solvent composition comprising 1-chloro-2,3,3-trifluoro-1-propene and nitromethane; immersing the article in the solvent composition in a cleaning bath; Including, The content of the nitromethane is 0.6 to 3 mass % based on the total mass of the solvent composition. [5] The method according to [4], wherein the cleaning bath includes a hot bath and a cold bath, and the immersion step includes a step of immersing the article in the solvent composition in the hot bath, and then a step of immersing the article in the solvent composition in the cold bath. [6] The method according to [4] or [5], further comprising the step of generating vapor of the 1-chloro-2,3,3-trifluoro-1-propene from the solvent composition and exposing the article after the immersion step to the vapor. [7] The method according to [6], further comprising the steps of: cooling the vapor to recover the 1-chloro-2,3,3-trifluoro-1-propene; and separating and removing water, if any, contained in the recovered 1-chloro-2,3,3-trifluoro-1-propene. [8] The method according to any one of [4] to [7], wherein the article comprises at least one metal selected from the group consisting of iron, copper, aluminum, and alloys thereof, and / or a ceramic of an oxide, nitride, or carbide. [9] The method according to any one of [4] to [8] above, further comprising the step of replenishing the cleaning tank with a replenishing solution containing 1-chloro-2,3,3-trifluoro-1-propene.

[10] A combined cleaning solvent product comprising the solvent composition according to any one of [1] to [3] above and a replenisher containing 1-chloro-2,3,3-trifluoro-1-propene. Effect of the Invention

[0007] According to the present invention, by adding nitromethane to a solvent composition containing HCFO-1233yd, even if water is mixed into the solvent composition, it is possible to suppress the occurrence of rust on the object to be cleaned or the cleaning equipment. Therefore, the vaporized HCFO-1233yd can be safely cooled and collected without worrying about rust occurring on the object to be cleaned or the cleaning equipment. In particular, since the possibility of rust occurring due to moisture contained in the cleaning agent is higher for iron-based objects to be cleaned than for other metal materials, the above-mentioned solvent composition is particularly effective in preventing rust on iron-based materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention will now be described in further detail. The term "solvent composition" as used herein refers to a composition containing a solvent and an additive. The solvent composition of the present invention contains HCFO-1233yd and nitromethane. The use of the solvent composition is not particularly limited, and the solvent composition can be used, for example, as a cleaning agent for cleaning articles.

[0009] The HCFO-1233yd is a type of fluoroolefin organic solvent, and has Z isomer (hereinafter, sometimes referred to as "HCFO-1233yd(Z)") and E isomer (hereinafter, sometimes referred to as "HCFO-1233yd(E)") as positional isomers. The boiling point of HCFO-1233yd(Z) is about 54°C, and the boiling point of HCFO-1233yd(E) is about 48°C. The solvent composition of the present invention may employ any of HCFO-1233yd(Z), HCFO-1233yd(E), and mixtures thereof. For example, when the solvent composition is used as a cleaning agent, if HCFO-1233yd(Z) having a high boiling point is employed, the steam cleaning temperature can be increased, and it is expected that the cleaning effect of oil and the like will be enhanced. For this reason, it is preferable to use HCFO-1233yd(Z) having a high boiling point as the main component of the cleaning agent.

[0010] The content of the HCFO-1233yd is not particularly limited, but may be, for example, about 97% by mass or more, and preferably about 98% by mass or more, based on the total mass of the solvent composition. The content of the HCFO-1233yd may be, for example, about 99.4% by mass or less, and preferably about 99.3% by mass or less, based on the total mass of the solvent composition.

[0011] The nitromethane is a type of nitroalkane that can be used as a solvent additive. When the nitromethane is added to a solvent composition containing the HCFO-1233yd, even if water is mixed into the solvent composition, the effect of suppressing rust generation in the object to be cleaned or the cleaning device is exhibited. Such an advantageous effect is not exhibited in any combination of solvent and additive, but is particularly exhibited in the relationship between the HCFO-1233yd and the nitromethane. The content of the nitromethane is not particularly limited as long as the rust generation suppression effect is exhibited, but may be, for example, about 0.6% by mass or more with respect to the total mass of the solvent composition, and preferably about 0.7% by mass or more. The content of the nitromethane may be, for example, about 3% by mass or less with respect to the total mass of the solvent composition, and preferably about 2% by mass or less. The nitromethane is known to be flammable or explosive. Furthermore, when the solvent composition of the present invention is used as a cleaning agent for steam cleaning, it has been confirmed by experiments that in many cases, although there are differences depending on the conditions of use, a part of the HCFO-1233yd evaporates during the steam cleaning, and the nitromethane concentration increases by about 1 mass%. In particular, it has been specifically confirmed that the nitromethane concentration in the steam tank of a horizontal three-tank cleaning device increases due to the evaporation loss of HCFO-1233yd. Therefore, by adjusting the content of nitromethane taking into consideration such an increase in concentration, it is possible to effectively suppress the generation of rust caused by water mixed in the cleaning agent while maintaining safety.

[0012] In one embodiment, the solvent composition of the present invention is used for cleaning an article. The article to be cleaned (i.e., the object to be cleaned) is not particularly limited, and may contain, for example, at least one metal selected from the group consisting of iron, copper, aluminum, and alloys thereof, and / or ceramics of oxides, nitrides, or carbides. Materials mainly containing iron (iron-based materials) are more susceptible to rust caused by water than metal materials mainly containing other metals, so the rust generation suppression effect of the solvent composition of the present invention is particularly useful in cleaning articles formed from iron-based materials. Furthermore, the surface of the cleaning tank of the cleaning device may also usually contain metals of iron-based materials. For example, a corrosion-resistant metal such as stainless steel is usually used for the cleaning device, but rust may occur due to continuous use over a long period of time. If the solvent composition of the present invention is used, cleaning work can be performed without worrying about rust generation, even if the object to be cleaned or the cleaning device contains metals of iron-based materials.

[0013] The solvent composition of the present invention can also be used in co-solvent cleaning. In co-solvent cleaning, solvents that are strong at cleaning specific soiling substances, such as hydrocarbons, glycol ethers, and higher alcohols, are used in the cleaning process, but these solvents have poor drying properties, so soiling substances may remain on the surface. If such a solvent is mixed with the solvent composition of the present invention and used in the cleaning process, the remaining of soiling substances can be suppressed. That is, in one embodiment, the solvent composition of the present invention further contains an additional cleaning component, and the additional cleaning component may be at least one selected from the group consisting of, but is not limited to, hydrocarbons, glycol ethers, and higher alcohols. The solvent composition of the present invention can also be used in the rinsing process of co-solvent cleaning. For example, by performing steam cleaning using the solvent composition of the present invention, it is possible to respond to fields where high cleanliness is required.

[0014] The solvent composition of the present invention may further contain any additive or stabilizer commonly used in the art, as long as it does not impair the object of the present invention. The stabilizer may be any one commonly used in the art, without any particular limitation. For example, the stabilizer may be at least one selected from the group consisting of ethers (such as tert-butyl methyl ether and dioxane), nitroalkanes (such as nitroethane), ketones (methyl ethyl ketone), epoxy compounds, phenols, imidazoles, amines, phosphorus compounds, sulfur compounds, hydrocarbons, and alcohol compounds. Without being bound by a particular theory, it is presumed that, for example, phenols and hydrocarbons suppress the decomposition of HCFO-1233yd by their antioxidant effect. It is presumed that the epoxy compounds suppress further decomposition of HCFO-1233yd by acidic substances by capturing acidic substances and chlorine ions generated by the decomposition of a part of HCFO-1233yd, and that the amines suppress further decomposition of HCFO-1233yd by acidic substances by neutralizing the acidic substances. From these facts, it is expected that by using two or more kinds of stabilizers as necessary, a synergistic stabilizing effect by each stabilizer can be obtained. The content of the stabilizer is not particularly limited, but may be, for example, about 0.5 mass% or less based on the total mass of the solvent composition. By adding a small amount, for example, the decomposition suppression effect of the HCFO-1233yd is exerted without reducing the cleaning effect of the HCFO-1233yd.

[0015] In another aspect, the present invention also relates to a method of cleaning an article, the method comprising: providing a solvent composition comprising HCFO-1233yd and nitromethane; immersing the article in the solvent composition in a cleaning bath; In one embodiment, the cleaning bath includes a hot bath and a cold bath, and the immersion step may include a step of immersing the article in the solvent composition in the hot bath (e.g., about 30 to about 50°C) and then a step of immersing the article in the solvent composition in the cold bath (e.g., about 20 to about 30°C). In the hot bath, for example, ultrasonic waves may be applied to the article to improve cleaning efficiency. The immersion in the cold bath serves the role of rinsing in addition to cooling the article.

[0016] In one embodiment, the method further includes a step of generating steam of the HCFO-1233yd from the solvent composition and exposing the article after the immersion step to the steam. This step is called steam cleaning, and is carried out in a steam atmosphere vaporized in a steam tank. Since the temperature of the article is below the boiling point of the HCFO-1233yd as a result of the immersion step, the HCFO-1233yd condenses on the surface of the article and flows down when exposed to the steam. In this manner, the article is cleaned.

[0017] The method for cleaning an article of the present invention may further include any cleaning or drying step commonly used in the art, as long as it does not impair the object of the present invention. For example, when a large amount of oil stains are attached to the article (object to be cleaned), the method of the present invention may include a step of roughly cleaning the article with a hydrocarbon solvent as a pretreatment. In addition, when the object to be cleaned is difficult to dry due to a complex structure, the method of the present invention may include a step of subjecting the object to hot air drying or vacuum drying as a posttreatment.

[0018] The cleaning apparatus to which the solvent composition of the present invention and the method for cleaning an article of the present invention are applied is not particularly limited, and may be, for example, a vertical two-tank cleaning apparatus in which the space above the cleaning tank is utilized as the steam tank, or a horizontal three-tank cleaning apparatus equipped with the hot bath (sometimes called an immersion tank), the cold bath, and the steam tank. In general, a pipe through which cooling water flows is installed at the opening of the steam tank to prevent the steam generated in the steam tank from leaking out of the steam tank. When the steam of the HCFO-1233yd attempts to pass through the opening, it is cooled by the cooling water and condenses, so that the HCFO-1233yd is recovered as a liquid. The recovered HCFO-1233yd can be returned to the cleaning tank after passing through a water separator and reused. At this time, moisture in the air may be mixed into the cooled HCFO-1233yd, but not all of the moisture can be removed by the water separator. Even in such a case, since the solvent composition of the present invention contains the nitromethane, it is possible to suppress the occurrence of rust on the object to be cleaned or the cleaning apparatus. In addition, the horizontal three-tank cleaning equipment may be configured such that when the solvent composition overflows from the cold bath, it flows into the hot bath (immersion bath) and the steam bath. In such a case, the recovered HCFO-1233yd can be returned to the cold bath, thereby allowing the clean solvent to be efficiently reused.

[0019] In another aspect, the present invention also relates to a combination cleaning solvent product, the combination product including a solvent composition containing HCFO-1233yd and nitromethane, and a replenisher liquid containing HCFO-1233yd. When cleaning is performed with the solvent composition using a cleaning device equipped with a steam tank, it is difficult to completely recover the HCFO-1233yd vaporized in the steam tank. In addition, the boiling point of the nitromethane (100 to 103°C) is higher than that of the HCFO-1233yd, and since azeotropy does not occur at the temperature during steam cleaning, the concentration of the nitromethane tends to increase in the cleaning agent that is accumulated in a liquid state at the lower part of the steam tank. In many cases, the nitromethane concentration increases by about 1% by mass, but then often returns to a steady state, but it is dangerous if the concentration of the nitromethane becomes too high. Therefore, when the concentration of the nitromethane increases more than necessary, the concentration of the nitromethane can be maintained within an appropriate range by the replenisher liquid.

[0020] The replenishment liquid is periodically used to maintain the amount of the solvent composition evaporated by steam cleaning at an appropriate level. The composition of the replenishment liquid may be the same as that of the solvent composition, may contain only HCFO-1233yd without nitromethane, or may be intermediate therebetween (containing nitromethane but in a smaller amount than that in the solvent composition). That is, the replenishment liquid may further contain the nitromethane, and the content of the nitromethane may be the same as or lower than that in the solvent composition. It is desirable to determine the type of replenishment liquid to be used after performing experiments on cleaning operations using an actual cleaning device.

[0021] The method of using the replenishment liquid is not particularly limited, and for example, the replenishment liquid may be added to the cleaning tank (or the cooling tank if one exists) or to the steam generation portion of the steam tank.

[0022] The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to these examples. EXAMPLES

[0023] [Test Example 1] As a pretreatment for the test, a SPCC cold-rolled steel plate (15 mm x 50 mm) was immersed in an alkaline degreaser (Dipsol degreaser LC-34), brushed, washed, and then rinsed with water and thoroughly dried to remove any dirt such as moisture or oil. This was used as the sample plate for the subsequent tests.

[0024] In a sealable container, put HCFO-1233yd (AGC, AMOLEA (R) AS-300) and various additives were added to the container at the concentrations shown in Table 1 or Table 2 below. The container was tightly closed with a lid, and the container was thoroughly mixed by inverting 100 times (180 degree rotation) at a speed of 2 times per second to prepare a test liquid (solvent composition).

[0025] A screw cap bottle (screw cap bottle; No. 7, 100 mL) was prepared as a test container. 40 mL of the prepared test solution was placed in this bottle, and 5 g of ion-exchanged water was added. The lid of this test container was tightly closed, and the contents were mixed well by inverting 100 times.

[0026] The test vessel containing the test liquid and ion-exchanged water was left to stand, and after the test liquid and water were completely separated, the sample plate was placed in the test vessel. The separated water was collected at the top (about 10% of the height of the entire solution in the test vessel), but the sample plate was completely immersed in the test liquid. Ultrasonic waves were applied for 1 minute to degas the sample plate, and the surface of the test plate was thoroughly wetted with the test liquid. The immersed sample plate was left in a thermostatic chamber at 20°C, and the presence or absence of rust that developed on the surface of the sample plate over time was visually observed and judged as follows. The results are shown in Tables 1 and 2. ○: No rust △: The test liquid changes color ×: Rust present

[0027] [Table 1]

[0028] [Table 2]

[0029] When the sample plate was washed with HCFO-1233yd alone, rust occurred due to the influence of moisture mixed in the test liquid (Comparative Example 1). On the other hand, when nitromethane was added in combination with HCFO-1233yd, rust did not occur even if moisture was mixed in the test liquid (Examples 1 to 7). Such an advantageous effect was not observed in the test liquid containing other additives (Comparative Examples 4 to 15).

[0030] [Test Example 2] Except for using the stabilizer-containing solvent compositions of Examples 8 to 11 (Table 3) as the test liquid, the presence or absence of rust that developed over time on the surface of the sample plate was visually observed in the same manner as in Test Example 1. The results are shown in Table 3.

[0031] [Table 3]

[0032] Even when the solvent compositions of Examples 8 to 11, which further contain various stabilizers, were used, rust did not occur. In general, when HCFO-1233yd is stored at a temperature lower than the boiling point, it may be decomposed and generate halogen ions such as chloride ions, but the solvent compositions of these Examples contain stabilizers, so that the generation of such halogen ions can be suppressed. The halogen ions can generate acids and cause metal corrosion, so the solvent compositions of Examples 8 to 11 have the additional effect of suppressing not only the generation of rust but also the corrosion of metals.

[0033] From the above, it was found that by adding nitromethane to a solvent composition containing HCFO-1233yd, the occurrence of rust on the object to be cleaned or the cleaning equipment can be suppressed even if water is mixed into the solvent composition. Therefore, the vaporized HCFO-1233yd can be safely cooled and collected without worrying about the occurrence of rust on the object to be cleaned or the cleaning equipment.

Claims

1. A solvent composition comprising 1-chloro-2,3,3-trifluoro-1-propene and nitromethane, A solvent composition, the content of which is 0.6 to 3 mass% based on the total mass of the solvent composition (however, excluding a solvent composition containing a hydrocarbon having a boiling point of 60 to 100°C, a solvent composition containing an alcohol having a boiling point of 100°C or lower and having 2 to 4 carbon atoms, and a solvent composition containing at least one selected from 1,1-dichloro-2,2,3,3,3-pentafluoropropane and 1,3-dichloro-1,1,2,2,3-pentafluoropropane).

2. The solvent composition of claim 1 for cleaning an article.

3. 3. The solvent composition of claim 2, wherein the article comprises at least one metal selected from the group consisting of iron, copper, aluminum, and alloys thereof, and / or a ceramic of an oxide, nitride, or carbide.

4. 1. A method of cleaning an article, comprising the steps of: preparing a solvent composition containing 1-chloro-2,3,3-trifluoro-1-propene and nitromethane (excluding solvent compositions containing a hydrocarbon having a boiling point of 60 to 100° C., solvent compositions containing an alcohol having a boiling point of 100° C. or less and having 2 to 4 carbon atoms, and solvent compositions containing at least one selected from 1,1-dichloro-2,2,3,3,3-pentafluoropropane and 1,3-dichloro-1,1,2,2,3-pentafluoropropane); immersing the article in the solvent composition in a cleaning bath; Including, The content of the nitromethane is 0.6 to 3 mass % based on the total mass of the solvent composition.

5. 5. The method of claim 4, wherein the cleaning bath comprises a hot bath and a cold bath, and the immersing step comprises immersing the article in the solvent composition in the hot bath and thereafter immersing the article in the solvent composition in the cold bath.

6. The method according to claim 4 or 5, further comprising the step of generating vapor of the 1-chloro-2,3,3-trifluoro-1-propene from the solvent composition and exposing the article after the immersion step to the vapor.

7. The method according to claim 6, further comprising the steps of cooling the vapor to recover the 1-chloro-2,3,3-trifluoro-1-propene, and separating and removing water, if any, contained in the recovered 1-chloro-2,3,3-trifluoro-1-propene.

8. 8. The method of any one of claims 4 to 7, wherein the article comprises at least one metal selected from the group consisting of iron, copper, aluminum, and alloys thereof, and / or a ceramic of an oxide, nitride, or carbide.

9. The method of any one of claims 4 to 8, further comprising the step of replenishing the cleaning tank with a replenishment solution comprising 1-chloro-2,3,3-trifluoro-1-propene.

10. A cleaning solvent combination product comprising the solvent composition of any one of claims 1 to 3 and a replenisher comprising 1-chloro-2,3,3-trifluoro-1-propene.

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