JPS6412249B2 - - 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. _CCl3F + _CH3OH → _CHCl2F +H CHO+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 coloring of the liquid due to oxidized alcohol, or corrosion of the container due to hydrogen halide, and in polyurethane foaming, it causes the failure of amine catalysts. Activation lowers the expansion ratio, causing undesirable problems such as increased viscosity of the raw material polyol and yellowish brown coloring of the product. For this reason, various stabilizers for fluorocarbons have been developed. For example, in Japanese Patent Publication No. 39-23099, α-methylstyrene is used, and in Japanese Patent Publication No. 47-625, P-methylstyrene is used.
Isopropenyltoluene has been proposed as such a stabilizer. However, these stabilizers were not necessarily sufficient, as is clear from the comparative examples described below. The present inventors have conducted various studies on novel stabilizers in order to solve the above-mentioned inconveniences associated with the decomposition of fluorocarbons by alcoholic hydroxyl groups, and as a result, the general formula

Contains a hydrocarbon compound (hereinafter referred to as compound A) represented by the formula (R ₁ , R ₂ and R ₃ are hydrogen or a hydrocarbon group having 1 to 3 carbon atoms) and a monovalent phenol. It has been found that by using this method, fluorocarbons can be stabilized even more than conventional stabilizers. That is, the present invention relates to a method for stabilizing fluorocarbons against alcoholic hydroxyl groups, which is characterized by containing the compound A and monovalent phenols. Compound A in the present invention may be exemplified by known or well-known compounds, but usually readily available α-methylstyrene, P-isopropenyltoluene, P-isopropenyl-o-xylene, vinyltoluene, etc. are selected. It will be done. As can be seen from the Examples described below, α-methylstyrene and the like in which R ₁ is a methyl group are more preferably selected than vinyltoluene and the like in which R ₁ is hydrogen. Furthermore, as monovalent phenols, phenols containing various substituents such as alkyl groups, alkenyl groups, alkoxy groups, carboxyl groups, carbonyl groups, and halogens in addition to hydroxyl groups are also effective. for example,
2,6-di-t-butyl-p-cresol, O,
m,p-cresol, thymol, p-t-butylphenol, o,m,p-methoxyphenol,
These include eugenol, isoeugenol, butylhydroxyanisole, phenol, and xylenol. 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 for Compound A,
0.001-6.0%, preferably 0.05-2.0%, 0.0005-1% for monovalent phenols, preferably
0.001-0.5% is appropriate. The stabilizer of the present invention is
It can be added in advance to fluorocarbons or alcohol, or to a mixture of fluorocarbons and alcohol. It is also possible to add further 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 period of 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 to these Examples. Examples 1 to 14 and Comparative Examples 1 to 12 The following mixtures were prepared as samples: 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 the 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 fluorocarbon decomposes, 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 according to JIS K-
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. The pH before the heating test was 11.4, and the chromaticity was Gardner 1 or less (APHA 10).

【table】

【table】

[Table] Reference example Stabilizer used in Example 1 (vinyltoluene/2,6-di-t-butyl-p-cresol)
After stirring 146 g of sample mixture and 262 g of crude MDI (methylene diisocyanate) at a liquid temperature of 20°C for 5 seconds, they were poured into a wooden box (20 cm x 20 cm x 20 cm).
The reactivity (gel time) was measured and was 33 seconds. Instead of the sample mixture containing the stabilizer used in Example 1, the sample mixture containing the stabilizer (vinyltoluene/t-butylcatechol) used in Comparative Example 13 was used.
The gel time was measured in the same manner as above except that 146 g was used, and it was 40 seconds.

Claims (1)

[Claims] 1 General formula [Formula] (R ¹ is hydrogen, R ² and R ³ are hydrogen or carbon number 1
A method for stabilizing chlorofluorocarbons against alcoholic hydroxyl groups, the method comprising containing a hydrocarbon compound represented by (-3 hydrocarbon groups) and a monovalent phenol.