JPH04173750A - Method for stabilizing 1,1-dichloro-2,2,2-trifluoroethane - Google Patents

Abstract

PURPOSE:To stabilize the title compound by adding phenols to the title compound, thereby suppressing the generation of 1-chloro-2,2, 2-trifluoroethane which is a decomposition product of the title compound. CONSTITUTION:Phenols such as 2,6-di-tert. butyl-p-cresol, p-cresol, eugenol, isoeugenol, thymol, p-methoxyphenol or tert. butylcatechol are added to 1,1- dichloro-2,2,2-trifluoroethane (R123) at an amount of 0.0005-10wt.%, preferably 0.01-5wt.% based on R123. Thereby, generation of 1-chloro-2,2,2-trifluoroethane which is a decomposition product of R123 and is suspected as a carcinogenic substance is suppressed to provide a stabilized R123 which is usable for foaming agent, refrigeration medium, aerosol and solvent, etc., as a substitute for trichlorofluoromethane.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention stabilizes t,i-dichloro-2,2,2-1-lifluoroethane C (hereinafter referred to as R123),
The present invention relates to a method for suppressing the generation of l-chloro-2,2,2-trifluoroethane (hereinafter referred to as R133a), which is a decomposition product.

[Prior Art] Conventionally, trichlorofluoromethane (hereinafter referred to as R11) has been used in polyurethane foaming, turbo chillers, cleaning, etc.
has been used. However, fully halogenated hydrocarbons have been pointed out to pose environmental problems to the ozone layer, and there is an urgent need to develop alternative substances.

R123 is considered to be a promising substitute for R11.

Although R123 has excellent stability, it is said that when various compounds coexist, the stability decreases and various decomposition products are produced. Coexisting substances that promote decomposition include, for example, alcohol is added to solvents to increase solubility, contact with washing machines and materials to be washed, contamination components such as oil, and moisture contamination. can be given. On the other hand, in propellants, alcohol is added for the purpose of dissolving water-soluble active ingredients, and container materials are also included.

In addition, when foaming polyurethane used as a foaming agent, R123 comes into contact with polyol, which is a polyurethane raw material, a catalyst, a foam stabilizer, and a foaming machine. When used as a refrigerant for a centrifugal refrigerator or the like, examples include materials constituting the refrigerator and lubricating oil.

When decomposition of R123 occurs, for example, in aerosol products, it causes odor and coloring of the liquid due to oxidized alcohol, or corrosion of the container due to hydrogen halide, which is a decomposition product, and in polyurethane foaming, it causes damage to the catalyst. Decrease in expansion ratio due to inactivation, increase in the viscosity of the raw material polyol, yellowing of the product, corrosion of the machine due to hydrogen halide which is a decomposition product in refrigerators, machine failure due to deterioration of lubricating oil, etc. cause undesirable problems. Furthermore, a major problem is that R133a is generated as a result of the decomposition of R123.

[Problems to be Solved by the Invention] R133a produced as a result of the decomposition of R123 is suspected of being carcinogenic, and from the standpoint of safety, it is extremely important to suppress its occurrence.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have repeatedly investigated stabilizers for R123, and as a result, the present inventors have discovered that phenols can exhibit a remarkable effect of suppressing the production of R133a. The present invention has now been completed.

That is, the present invention relates to a method for suppressing the generation of R133a from R123, which is characterized by containing a phenol.

Phenols in the present invention include phenols containing various substituents other than hydroxyl groups, such as alkyl groups, alkenyl groups, alkoxy groups, carboxyl groups, carbonyl groups, and halogens. For example, 2,6-G-t-
Butyl-p-cresol, 0-cresol, ■-cresol, p-cresol, thymol, p-t-butylphenol, 0-methoxyphenol, m-methoxyphenol, p-methoxyphenol, eugenol, isoeugenol, butylhydroxyanisole, These include monovalent phenols such as phenol and xylenol, and divalent phenols such as t-butylcatechol, 2.5-di-t-amylhydroquinone, and 2.5-di-t-butylhydroquinone.

The content of the stabilizer in the present invention is not particularly limited, but is suitably 0.0005 to 10 wt%, preferably 0.001 to 5 wt%, based on R123.

In addition, 0.001 to 5 wt of other stabilizers such as epoxy compounds, hydrocarbons containing a nitro group, hydrocarbons such as α-methylstyrene and p-isopropenyltoluene may be added to the stabilizer of the present invention. It is also possible to add up to %.

[Examples] Hereinafter, the present invention will be specifically explained using Examples, but the present invention is not limited to these Examples.

Table 1 shows the results as a polyurethane blowing agent. The following mixed solution was prepared as a sample, and polyol EL-7
50ED 100 parts by weight (manufactured by Asahi Olin Co., Ltd.) Catalyst Dabco 33LV 2 parts by weight (manufactured by Sankyo Air Products Co., Ltd.) Foam stabilizer 5H-1932 parts by weight (manufactured by Toshi Silicone Co., Ltd.) Pure water 4 parts by weight R123 (C
40 parts by weight of HC12CF3) A predetermined amount of a stabilizer is mixed with this, sealed in a pressure-resistant glass container, maintained at a temperature of 90° C. in a hot air circulation thermostat, and subjected to a heating test for 3 days. After the heating test, the decomposition product R133a
The effect of suppressing R133a generation can be measured by analyzing the amount of R133a generated using gas chromatography.

Table 1 On the other hand, Table 2 shows the results as a refrigerant. Prepare the following mixed solution as a sample, and add a stabilizer to this: 50 parts by weight of lubricating oil 4GS (manufactured by Nippon Sun Oil Co., Ltd.), 100 parts by weight of R123 (CHCl, CF,) metals (SS41. Cu, Al). Mix a fixed amount, seal it in a pressure-resistant metal container, and maintain it at a temperature of 130°C in a hot air circulation type constant temperature bath.
A heating test is conducted for 14 days. After the heating test, the R133a generation suppressing effect can be measured by analyzing the amount of R133a, which is a decomposition product, generated using gas chromatography.

Table 2 [Effects of the Invention] R123 stabilized according to the method of the present invention can be used as a blowing agent, refrigerant, aerosol, or solvent, and has an excellent effect of suppressing the generation of R133a.

Claims (2)

[Claims] (1) 1 characterized by containing phenols
, 1,-dichloro-2,2,2-trifluoroethane. (2) Contains phenols, 1,1-dichloro-
1, which is a decomposition product of 2,2,2-trifluoroethane
By suppressing the generation of -chloro-2,2,2-trifluoroethane, 1,1,-dichloro-2,2,2-
How to stabilize trifluoroethane.