JPH0127050B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition with improved stability of a halogenated hydrocarbon mixture containing a fluorinated hydrocarbon. As is well known, lower halogenated hydrocarbons (hereinafter abbreviated as FHC) containing fluorine and halogens other than fluorine are used as propellants for aerosols, and as cleaning agents in the electrical/electronic industry, resin industry, and precision machinery industry. It is widely used as a component of Furthermore, these FHCs have recently begun to be used in combination with absorbents as refrigerants for absorption refrigerators, or as working media for turbines that utilize cold sources. Factors contributing to FHC's use in these applications include its low toxicity, nonflammability, solubility, heat conductivity, and excellent absorption properties. It was easy to decompose even under normal usage conditions, and there were problems with stability. This decomposition is mainly caused by dehydrohalogenation, and it is also known that decomposition is accelerated by contact of FHC with hydroxyl group-containing compounds, temperature rise, contact with metals or metal compounds, etc. Corrosion of the metals that make up the structure was also a problem. Specifically, in the case of aerosol products, FHC is usually used in combination with an alcohol solvent, but as soon as it decomposes, the container corrodes and the product quality deteriorates. Furthermore, industrial cleaning agents such as those mentioned above are usually used as a mixture with alcohol, ketone, or chlorinated hydrocarbons, but the same decomposition as mentioned above and accompanying corrosion occur, resulting in a deterioration of product quality and even damage to the objects to be cleaned. This will also lead to contamination.
When used as a refrigerant in an absorption chiller or as a turbine working medium, it is generally used at an operating temperature of 100 to 200°C, using an absorbent such as polyethylene glycol dimethyl ether, dimethyl formamide, or tetrahydrofurfuryl alkyl ether. , and in some cases aerosols;
The possibility of decomposition is greater than when used as a cleaning agent, and at the same time corrosion of the metal material may occur, significantly reducing the functionality of the device, which is extremely serious. For the above reasons, when FHC is used for the above purposes, a compound that suppresses the above-mentioned decomposition, a so-called stabilizer, is added to FHC, and various compounds have been proposed as this stabilizer. Examples of these stabilizers include examples in which an aromatic nitro compound is used as one component in combination with various unsaturated compounds or heterocyclic compounds (Japanese Patent Publication No. 13697/1983), and examples in which an amine compound is used ( Examples using furan compounds (Japanese Patent Publication No. 40-13724), examples using phosphite esters (Japanese Patent Publication No. 55-48277), examples using dialkyl pentaerythritol diphosphite (Japanese Unexamined Patent Publication No. 56-70082). Although these compounds generally achieve their purpose as stabilizers, they are not necessarily sufficient in long-term stabilizing effects, decomposition suppressing effects at high temperatures, metal corrosion preventing effects, etc., and they do not have stabilizing effects for all uses. It's not something you have. Taking the above points into consideration, the present inventors have developed a method that does not have the above-mentioned drawbacks and improves the stability of FHC for virtually all of the above-mentioned applications.
As a result of searching for a stabilizer that is sufficiently effective against corrosion of metal materials such as aluminum, copper, and zinc, we found that if a polyoxyalkylene compound with a specific molecular weight is added as a stabilizer to a mixture containing FHC, The inventors have discovered that the above objects can be achieved and have arrived at the present invention. That is, the present invention is a fluorinated hydrocarbon composition characterized by containing a polyoxyalkylene compound represented by the following general formula. R ₁ O(-RO)- _o R ₂ [where R ₁ and R ₂ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
Further, R represents an alkylene group having 1 to 4 carbon atoms. n is a positive number indicating the average number of repetition units, R ₁ , R ₂
If both are hydrogen atoms, it is a positive number of 4 to 150, and in other cases, it is a positive number of 20 to 150. ] As mentioned above, the compound represented by the above general formula is
It is a specific polyoxyalkylene or a derivative in which one or both of its terminals are replaced with a specific substituent, and the average degree of condensation is 4 or more and 150 or less if both terminals are hydrogen atoms, and at least one terminal is hydrogen atoms. When substituted with the above substituent, the number is preferably 20 or more and 150 or less. If it is less than 4 or 20, the reason is not clear, but as mentioned above, the effect that satisfies the purpose of the present invention will not be realized, and if it exceeds 150, the above compound will not be effective.
Solubility in FHC etc. decreases, both of which are unfavorable. Specific examples of the R group constituting the above-mentioned polyoxyalkylene include ethylene and propylene groups. This polyoxyalkylene may be composed of one or more of the above-mentioned alkylene groups, and the copolyalkylene may be a block or random copolymer. When R ₁ and/or R ₂ described above is an alkyl group having 1 to 4 carbon atoms, examples of the hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, butyl, and the like. One or more terminal groups of the polyoxyalkylene may be present in the same polymer. As described above, polyoxyalkylene or the compound represented by the above general formula in which one or two of its terminal hydrogen atoms are substituted with a specific alkyl group may be produced by any method, and any known method may be used. It can be used. In the case of compounds in which two of the above hydrogen atoms are substituted with specific substituents, after adding the specified alkylene oxide to the alcohol,
It can be produced by a known method such as reacting a terminal hydrogen atom with an alkyl halide. Examples of the compounds represented by the above general formula include polyethylene glycols, polypropylene glycols, polybutylene glycols, polyethylene polypropylene glycols, polyethylene glycol mono (or di) ethers, polypropylene glycol mono (or di) ethers, Examples include polyethylene polypropylene glycol mono (or di) ethers. These compounds are used as one or more compounds as a stabilizer which is a component of the composition of the present invention. The FHC constituting the composition of the present invention is a halogenated hydrocarbon in which one or more atoms of fluorine and/or bromine are substituted, such as dichloromonofluoromethane, monochlorodifluoromethane, monochloromonofluoromethane, and trichloromonofluoromethane. , dichlorodifluoromethane, monochlorotrifluoromethane, halogen-substituted methane such as monobromotrifluoromethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, dichlorotetrafluoroethane, monochlorotetrafluoroethane, monochloropentafluoroethane, monochlorotrifluoroethane, mono Examples include halogen-substituted ethane such as bromomonochlorodifluoroethane. Since the composition of the present invention is used for substantially the purposes described above, it may further contain other components. The other components listed above vary depending on the application, and when used as a propellant for aerosol products, they are often lower aliphatic alcohols such as methanol, ethanol, and propanols, and when used as a propellant for various industrial cleaning agents. They are lower alcohols, ketones, or other halogenated hydrocarbons, and in the case of working media or refrigerants for absorption refrigerators as described above, they are often used in combination with absorbents as described above. The content of the above-mentioned other components based on the total composition is often 5 to 80% by weight. The content of the compound represented by the above general formula constituting the composition of the present invention is preferably 0.001% by weight or more and 10% by weight or less, and 0.01 to 5.0% by weight, based on FHC alone or the composition containing other components. A range of 0.01 to 1.0% by weight is particularly effective. If a composition with the above composition is used for the above-mentioned purposes, in addition to preventing the decomposition of FHC itself in the conventional method, (a) iron, aluminum, copper, etc.
Corrosion of metal materials such as zinc is significantly suppressed. (b) The prevention of decomposition of FHC itself is more pronounced in a wider temperature range than in known methods, specifically from -50 to 250°C, and is particularly effective at high temperatures such as 100 to 200°C. Appear. As mentioned above, the composition of the present invention is often composed of FHCs, a specific glycol derivative stabilizer represented by the above general formula, and in some cases other components, but depending on the use, Further, if necessary, any other components may be included in an amount of about 10 to 30% by weight. Examples will be described below to explain the present invention in more detail, but the present invention is not limited thereto. Examples 1 to 4 Test pieces made of steel, copper, and aluminum with a size of 0.8 x 13 x 180 mm were placed with a copper wire ring interposed to prevent contact between the pieces, and the inner diameter was 20 mm and the length was 20 mm.
The test piece was placed in a 130 mm hard glass test tube, and a composition consisting of 30 parts of fluorinated halogenated hydrocarbon, 0.9 parts of water, and 0.15 parts of a prescribed stabilizer was added to the test tube, and the test piece was immersed in this composition. The test tube was placed in an autoclave, sealed, placed in a hot air circulation thermostat, and heated at 50°C for 10 days. After completing the prescribed heating, the autoclave was taken out and cooled to room temperature. After opening, the test piece was taken out. After this heating test, the surface change of the test piece was observed, and the Cl ^- ion concentration in the composition was measured.
These results are shown in Table 1. Comparative Example 1 In the method described in Example 1, no stabilizer was added,
A heating test was conducted and the results are shown in Table 1. Examples 7 to 12 Test tubes containing the same test pieces as in Examples 1 to 6 were placed in an autoclave with a pressure resistance of 100 Kg/cm ² . 4 parts of a mixture of tetraethylene glycol dimethyl ether and a prescribed stabilizer at a weight ratio of 200:1 was placed in an autoclave, and 16.1 parts of the test tube contained in the test piece was placed in the autoclave and sealed. Next, after completely replacing the air in the autoclave with nitrogen, the autoclave was immersed in a dry ice-methanol mixture, and 20 parts of monochlorodifluoromethane (R-22) was charged at an internal temperature of -20 to -30°C, and the autoclave and the above were heated. A composition according to the invention was present in a test tube. This autoclave was placed in a hot air circulation constant temperature bath and heated at 200°C for 10 days, and then the autoclave was cooled to room temperature. The test pieces taken out were post-treated using a well-known method, surface changes were observed, and the erosion rate was calculated.
Further, the appearance, pH, acid content, Cl ^- ion concentration, and purity of the residual liquid of the composition present in the test tube after opening the autoclave were measured. These results are shown in Table 2. Comparative Example 2 A heating test was conducted using the methods described in Examples 5 to 8 without adding any stabilizer, and the results are shown in Table 2.

【table】

[Table] Erosion rate: Unit μ/year Surface change
○ No change
Minus (weight increase)
+ Overall judgment (discoloration area, degree of discoloration) within 10% of the test piece

〃
〃 20% 〃

〃
〃 Less than 30%

＋＋＋＋ 〃
〃 30% or more

Claims (1)

[Scope of Claims] 1. A fluorinated hydrocarbon composition characterized by containing a polyoxyalkylene compound represented by the following general formula. R ₁ O(-RO)- _o R ₂ "Here, R ₁ and R ₂ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
Further, R represents an alkylene group having 1 to 4 carbon atoms. n is a positive number indicating the average number of repetition units, R ₁ , R ₂
If both are hydrogen atoms, it is a positive number of 4 to 150, and in other cases, it is a positive number of 20 to 150.