JPH0255478B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel and objective compositions containing diether compounds having oxyalkylene groups. In recent years, from the perspective of energy conservation, there has been increasing interest in equipment such as turbines or absorption chillers that utilize cold sources. As is well known, lower halogenated hydrocarbons (hereinafter abbreviated as FHC) containing fluorine and halogens other than fluorine are used as the working medium of these devices, and polyalkylene glycol dicarbonate is used as an absorbent for this medium. (Lower) alkyl ethers, dimethylformamide, and tetrahydrofurfuryl alkyl ethers are often used. (Unexamined Japanese Patent Publication No. 56-79175
(Refer to Publications, etc.) As these factors, first of all, FHC
It has low toxicity and nonflammability, and has favorable dissolution characteristics, absorption characteristics, and heat transfer characteristics when FHC is combined with the above-mentioned absorbent. On the other hand, as is well known, due to its inherent properties, FHC, typified by monofluorodichloromethane, decomposes and deteriorates, causing various product deteriorations. Various stabilizers have been proposed to suppress this deterioration. (Unexamined Japanese Patent Publication No. 56-13697,
However, when using FHC as a working medium and the above-mentioned compounds as an absorbent in an absorption refrigerating machine as described above, for example, when FHC is used as a propellant or Unlike when used as a detergent, 100 to 200
Because it is exposed to high temperature ranges such as °C, it is difficult to prevent decomposition of FHC itself, decomposition of the absorbent itself, and contamination, and there is a problem of corrosion of metal parts that come into contact with the absorbent due to these factors. death,
Moreover, this caused delays in the practical application of cold energy utilization turbines and absorption chillers. In view of the above points, the present inventors have made extensive studies to solve the drawbacks seen in the prior art as described above. Even if FHC is absorbed into this and exposed to the high temperature range mentioned above for a long period of time, the decomposition of FHC is significantly suppressed, and furthermore, the decomposition and contamination of the polyalkylene glycol di(lower) alkyl ether are suppressed. The present invention was achieved by discovering that the composition can be used as an absorbent as described above, and that the corrosion of metals welded together can be prevented. That is, the present invention provides a compound represented by the general formula (1) R ₁ O-(RO-) _o R ₂ ...(1) [where R ₁ and R ₂ are each the same or different carbon number 1 to 4]
an alkyl group R: an alkylene group having 1 to 4 carbon atoms; n: the number of repeating units; a positive number of 2 to 10; ] and a composition for a working medium comprising at least one compound from the group of cyclic ether compounds represented by formulas (2) to (8). [Here, R ₃ to _{R 9} each represent the same or different hydrocarbon group having 1 to 8 carbon atoms. ] In the compound of general formula (1) constituting the composition of the present invention, R ₁ and R ₂ represent an alkyl group having 1 to 4 carbon atoms, specifically methyl, ethyl, n-propyl, Isopropyl, n-butyl, isobutyl,
Represents a sec-butyl or tert-butyl group, R ₁
and R ₂ may be the same or different. Further, R is preferably an ethylene or propylene 1,2-butylene group, and n indicates the number of repeating units of the oxyalkylene group, and is a positive number of 2 or more and 10 or less.
The oxyalkylene groups constituting the compound represented by general formula (1) may be the same or may contain two or more types of the above alkylene groups. These compounds include diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, polyethylene glycol with up to 10 repeating units, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol with up to 10 repeating units, Examples include dimethyl, diethyl, di(n-,iso)propyl, methylethyl, ether, etc., such as ethylene propylene glycol, diethylene propylene glycol, and diethylene dipropylene glycol. These ethers may be produced by any known method and may be used as one or more compounds to constitute the composition of the present invention. In the compounds represented by general formulas (2) to (8) constituting the composition of the present invention, R ₃ to R ₉ are hydrogen atoms, methyl, ethyl, n-propyl, isopropyl n-, sec. Indicates aromatic groups such as alkyl groups such as - and tert-butyl groups, allyl groups such as phenyl, tolyl, and various xylyl groups, and these may be the same or different in a single compound. . To give more detailed examples of these cyclic ethers, the compounds represented by the general formula (2) include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, etc. Examples of the compound represented by the formula (4) include oxetane, oxetane in which R ₄ is a methyl, ethyl, propyl, butyl group, etc.; compounds represented by the formula (4) include tetrahydrofuran, R ₅ is methyl, ethyl, propyl,
Examples of substituted tetrahydrofurans represented by formula (5) include butyl and phenyl groups, substituted furans in which R ₆ is a methyl, ethyl, propyl, butyl group, etc. Examples of compounds include 1,4-dioxane, R ₇ is methyl,
Substituted 1,4 which is ethyl, propyl, butyl group etc.
-Dioxanes, compounds represented by formula (7) include 1,3-dioxane, R ₈ is methyl, ethyl,
Substituted 1,3-dioxanes such as propyl and butyl groups, compounds represented by formula (8) include 1,
Examples include 3-dioxolane and substituted 1,3-dioxolanes in which R ₉ is a methyl, ethyl, propyl, butyl group or the like. These are 1 type or 2
More than one compound may be used to constitute the composition of the present invention. In the composition of the present invention, per 100 parts by weight of the compound represented by the general formula (1), the general formula (2) to
The amount of the compound represented by (8) is preferably 0.001 to 10 parts by weight, preferably 0.001 to 5 parts by weight. As mentioned above, since this composition is mainly used as an absorbing liquid for the working medium of cold energy utilization turbines or absorption chillers, other components such as lubricants and viscosity modifiers are added to this absorbent. etc. may be added as long as they do not significantly reduce the effects of the composition of the present invention. When using the composition of the present invention as the above-mentioned absorbent for a working medium, any known
Even if FHC is used, the effect of the composition of the present invention is not reduced, and these FHCs include, for example, monofluoromonochloromethane, monofluorodichloromethane, monofluorotrichloromethane, difluoromonochloromethane, difluorodichloromethane, and trifluoromonobromomethane. , difluorotetrachloroethane, difluoromonobromomonochloroethane, trifluoromonochloroethane, trifluorotrichloroethane, tetrafluoromonochloroethane, tetrafluorodichloroethane, and pentafluoromonochloroethane. I can do it. As mentioned above, the composition of the present invention has been described, but the characteristics of the composition are further listed as follows: (a) Specific polyalkylene glycol di(lower)
Even if a cyclic ether compound as mentioned above is present in the alkyl ether and FHC is absorbed into it,
Over a long period of time, FHC is stabilized in a high temperature range that has hitherto been unpredictable. (b) Since the cyclic ether is always present in the polyalkylene glycol di(lower) alkyl ether, the dialkyl ether itself is prevented from deteriorating, and its life as an absorbent, which is the main use of the composition of the present invention, is extended. do. (c) As a result of the effects of (a) and (b), the composition of the present invention containing FHC and the metal can be used for a long time at 100 to 200
Corrosion of this metal is suppressed even when it comes into contact at high temperatures such as 0.degree. C. Therefore, if the composition of the present invention is used as an absorbent as described above, the life of, for example, an absorption refrigerator, etc. will be significantly extended. etc. can be given. Hereinafter, the present invention will be explained in more detail by describing Examples and Comparative Examples, but the present invention is not limited thereto. In the following description, parts and % indicate parts by weight and % by weight unless otherwise specified. Examples 1 to 7 A test piece made of steel, copper, and aluminum with a size of 0.8 x 13 x 80 mm was 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 tube was placed in a 130 mm hard glass test tube, and the test tube was placed in a stainless steel autoclave. 0.4 part of a composition consisting of tetraethylene glycol dimethyl ether and a specified cyclic ether in a weight ratio of 200:1 was placed in the above autoclave at 16.1 parts.
The test piece was placed in the test tube containing the test piece, and the test piece was immersed in this mixed solution. Next, the air in the autoclave was sufficiently replaced with nitrogen, immersed in a dry ice-methanol mixture, and cooled to -20 to -30°C. After that, 20 parts of FHC was press-fitted, and the autoclave was heated to a constant temperature with hot air circulation. It was left standing in a tank and a heating test was conducted at a predetermined temperature and for a predetermined number of days. After the test, the autoclave was taken out from the thermostat, allowed to cool to room temperature, and the test pieces were taken out from the test tubes, and the results of surface changes and corrosion rates after post-treatments such as washing were tested using known methods. The appearance, pH, acid content, Cl ^- ion concentration, and purity of the composition according to the present invention that was present in the tube were measured, and the results are shown in Table 1.

【table】

[Table] Comparative Examples 1 and 2 In the method described in Examples 1 to 7, a heating test was conducted using only tetraethylene glycol dimethyl ether without adding any cyclic ether, and the results are shown in Table 1. Comparative Examples 3 and 4 In the method described in Examples 1 to 7, a known low-temperature FHC stabilizer was added in place of the cyclic ether, and a heating test was conducted, and the results are shown in Table 1. Examples 8 to 11 In the method described in Examples 1 to 7, a heating test was conducted at 200°C for 10 days using the colorless, transparent, precipitate-free diethers shown in Table 2 instead of tetraethylene glycol dimethyl ether. The results are shown in Table 3.

【table】

[Table] * Erosion rate - Same as footnote in Table 1 ** Surface change - Comparative examples 5 and 6 Same as above In the method described in Examples 1 to 7, methyl alcohol and acetone were used instead of tetraethylene glycol dimethyl ether. A heating test was conducted at 170°C for 30 days, and the results are shown in Table 4. Looking at the results in Table 4, it is understood that the stabilizing effect of the cyclic ether compound constituting the composition of the present invention is particularly effective for certain diethers.

[Table] * Same as footnote in Table 1 ** Same as footnote in Table 2 *** Indicates purity before testing

Claims (1)

[Scope of Claims] 1 Compound represented by general formula (1) R ₁ O-(RO-) _o R ₂ ...(1) [Here, R ₁ and R ₂ each have the same or different carbon number 1 ~4
an alkyl group R: an alkylene group having 2 to 4 carbon atoms; n: the number of repeating units; a positive number of 2 to 10; '' and a composition for a working medium used as an absorbent for lower halogenated hydrocarbons in an absorption refrigerator, comprising at least one compound from the group of cyclic ether compounds represented by general formulas (2) to (8). . “Here, R ₃ to _{R 9} each represent the same or different hydrocarbon groups having 1 to 8 carbon atoms.