JPH0125726B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for stabilizing lower aliphatic halogenated hydrocarbons containing fluorine and halogens other than fluorine. Lower aliphatic halogenated hydrocarbons containing fluorine and halogens other than fluorine (hereinafter referred to as fluorocarbons)
is known to easily react with alcoholic hydroxyl groups and decompose. Lower aliphatic halogenated hydrocarbons containing only fluorine are stable against alcoholic hydroxyl groups, but other fluorocarbons decompose through the following reaction to produce aldehydes and ketones. CCl ₃ F + CH ₃ OH → CHCl ₂ F + HCHO + HCl. Generally, Freon is often used in combination with an alcoholic hydroxyl group. For example, alcohol is added to a solvent to increase solubility, and to a propellant to dissolve a water-soluble active ingredient. Furthermore, in polyurethane foaming using fluorocarbons as a foaming agent, the fluorocarbons come into contact with polyol, which is a raw material for polyurethane. In addition, there are many opportunities for fluorocarbons to come into contact with alcoholic hydroxyl groups. When decomposition of fluorocarbons occurs, for example, in aerosol products, it causes odor and coloration of the liquid due to oxidized alcohol, or corrosion of containers due to hydrogen halides, and in polyurethane foaming, it causes the inactivity of amine catalysts. This decreases the expansion ratio and causes undesirable problems such as an increase in the viscosity of the raw material polyol and a yellowish-brown coloring of the product.
For this reason, various stabilizers for fluorocarbons have been developed. For example, JP-A-53-82708 proposes a stabilizer system that combines vinyltoluene and t-butylcatechol. That is, the general formula

A combination of vinyltoluene and t-butylcatechol, a divalent phenol, in which R ₁ and R ₂ are hydrogen atoms and R ₃ is a methyl group, has already been developed. However, according to research by the present inventors, R ₁ in the above general formula is a hydrocarbon group having 1 to 3 carbon atoms, which has a greater stabilizing effect when combined with phenols than a hydrogen atom. I knew it would improve. Furthermore, as a result of repeated studies, it was found that the phenol compound to be combined is not limited to divalent phenols, but also, for example, monovalent phenols can similarly exhibit an unprecedented stabilizing effect. Also, in this general formula, R ₂ and
Regarding R ₃ , it was also discovered that hydrogen or a hydrocarbon group having 1 to 3 carbon atoms is advantageous, and the present invention was completed. That is, the present invention is based on the general formula

[Formula] (R ₁ is a hydrocarbon group having 1 to 3 carbon atoms. R ₂ and R ₃ are hydrogen or a hydrocarbon group having 1 to 3 carbon atoms.) The present invention relates to a method for stabilizing fluorocarbons against alcoholic hydroxyl groups, which is characterized by containing fluorocarbons and phenols. Compound A in the present invention may be exemplified by known or well-known compounds, but usually α-methylstyrene, P-isopropenyltoluene, P-isopropenyl-o-xylene, P-isopropyl-α-ethylstyrene, etc. is selected. Furthermore, as the phenols, phenols containing various substituents such as an alkyl group, an alkenyl group, an alkoxy group, a carboxyl group, a carbonyl group, and a halogen in addition to a hydroxyl group are also effective. For example, 2.6-di-t-butyl-P-cresol, O, m, p-cresol, thymol, p-t-butylphenol, o, m, p-methoxyphenol, eugenol, isoeugenol, butylated hydroxyanisole, phenol, Monovalent phenol such as xylenol or t-butylcatechol, 2.5
-di-t-amylhydroquinone, 2.5-di-t
- Divalent phenols such as butylhydroquinone. In the present invention, fluorocarbons refer to lower aliphatic halogenated hydrocarbons having 1 to 4 carbon atoms and containing fluorine and halogens other than fluorine, particularly fluorocarbons having 1 to 2 carbon atoms.
It is a lower aliphatic halogenated hydrocarbon. Halogens other than fluorine include chlorine and bromine. Specific examples of CFCs include trichlorofluoromethane, dichlorodifluoromethane, dichloromonofluoromethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, dichlorotetrafluoroethane, monochlorotetrafluoroethane, bromochlorodifluoromethane, and bromotrifluoromethane. . Among them, fluorocarbons with the same or smaller number of fluorine atoms as chlorine and/or bromine, such as trichlorofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, and tetrachlorodifluoroethane, are particularly easy to decompose and are The invention achieves these high stabilities. Compounds containing alcoholic hydroxyl groups that decompose CFCs include methanol, ethanol,
There are various polyols for producing polyurethane by reacting with monohydric or polyhydric alcohols such as propanol, ethylene glycol, propylene glycol, and glycerin, and polyisocyanates. Examples of polyols include:
Ethylene oxide, compounds with two or more OH groups such as glycols, alkanolamines, glycerin, and sugars, or compounds containing active hydrogen atoms such as ethylenediamine.
Polyether polyols made by reacting epoxides such as propylene oxide, epichlorohydrin, and butylene oxide, and polyester polyols made by reacting polybasic acids such as adipic acid and phthalic acid with polyhydric alcohols such as ethylene glycol, diethylene glycol, and propylene glycol. be. It also includes other compounds and polyols for polyurethane obtained by reaction methods. The amount of stabilizer added in the present invention is not particularly limited, but in compound A,
0.001-6.0%, preferably 0.05-2.0%, 0.0005-1% for phenols, preferably 0.001
~0.5% is appropriate. The stabilizer of the present invention can be added in advance to fluorocarbons or alcohol, or to a mixture of fluorocarbons and alcohol. It is also possible to further add other stabilizers to the stabilizer system of the present invention. The fluorocarbons stabilized according to the method of the present invention are effective, for example, on the storage stability of polyols containing fluorocarbons as blowing agents. Normally, when polyurethane foam is formed by reacting polyisocyanates and polyols, the fluorocarbons and polyols are often mixed in advance and stored for a long time. In this case, if the stabilized fluorocarbon of the present invention is used, decomposition of the fluorocarbon during storage can be suppressed without adversely affecting polyurethane foam formation. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited only to these Examples. Examples 1-28 and Comparative Examples 1-7. Prepare the following mixture as a sample: N,N,N',N'-tetrakis-2-hydroxypropylethylenediamine 100 parts by weight Triethylenediamine (DABCO 33LV)
2 〃 Water 4 〃 Freon 11 (CCl ₃ F) 40 〃 Mix this with a specified amount of stabilizer, put it in a pressure-resistant glass container, maintain the temperature at 90℃ in an air bath, and conduct a heating test for 72 hours. Let's do it. When chlorofluorocarbons decompose, hydrogen chloride is generated, so the degree of decomposition can be determined by examining the pH, and the stabilizing effect can be measured by the degree of increase in chromaticity. After the above heating test, the chromaticity of the sample liquid was determined by JISK-
Measure according to 6901. That is, the chromaticity is expressed in Gardner by comparison with a standard solution. Also, add 30 ml of isopropyl alcohol aqueous solution (volume ratio of isopropyl alcohol/pure water = 10/6) to 5 g of sample solution.
Add, mix and measure the pH. In addition, the pH before the heating test was 11.4, and the chromaticity was Gardner 1 or less (APHA 10).

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[Table] Reference example Sample mixture containing stabilizer used in Example 1 above
After stirring 146 g and 262 g of crude MDI (methylene diisocyanate) at a liquid temperature of 20° C. for 5 seconds, they were placed in a wooden box (20 cm x 20 cm x 20 cm), and the reactivity (gel time) was measured, which was 33 seconds. Example 1
The gel time was measured in the same manner as above, except that 146 g of the stabilizer-containing sample mixture used in Comparative Example 1 was used instead of the stabilizer-containing sample mixture used in Comparative Example 1, and the gel time was 40 seconds.

Claims (1)

[Claims] 1 General formula [Formula] (R ₁ is a hydrocarbon group having 1 to 3 carbon atoms. R ₂ and R ₃ are hydrogen or a hydrocarbon group having 1 to 3 carbon atoms.) 1. A method for stabilizing chlorofluorocarbons against alcoholic hydroxyl groups, the method comprising containing the hydrocarbon compound and phenols shown above.