JPS6250398A - Method for stabilizing solvent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for stabilizing u, 1,2-dichloro-1-fluoroethane (hereinafter referred to as Freon 141).

Freon 141 is nonflammable, has low toxicity, and has excellent ability to dissolve oily substances, so it is useful as a cleaning agent for various articles. For example, semiconductor materials such as silicone wafers and silicon chips, semiconductors such as RC and LSI, electronic and electrical equipment such as printed wiring boards, relay switches, micromotors, and liquid crystal cells, bearings,
As a degreasing agent for precision instruments such as lenses and springs, conventional chlorinated solvents such as trichlorethylene and 1,1,1-trichloroethane, and 11112-)IJ dichloro1゜2.
2-) It can be used as an alternative to fluorine-based solvents such as IJ fluoroethane.

(Prior art) Freon 141 is a new solvent in the industrial world, and has a nine-molecule structure and decomposition behavior that is different from conventional chlorine-based solvents and fluorine-based solvents that do not contain fluorine or hydrogen atoms. Friend, almost nothing is known about its stability or stability ratio method.

(Problems to be Solved by the Invention) Freon 141 has higher stability than conventional chlorine-based m-agents, and stabilization is not necessarily required under general usage conditions. Under certain conditions, such as over a long period of time, its stability may become a problem. 3 Patent M When the required quality level is high, such as when cleaning child equipment or parts of precision equipment, the stability of the cleaning solvent needs to be even more stringent.

(Elaborative Means for Solving the Problems) The present inventors have conducted various studies in an attempt to improve the stability of Freon 141, especially its stability under an oxidizing atmosphere, and as a result, they have found a method and have developed the present invention. Reach friend.

That is, the present invention provides Freon 14 characterized in that phenols or pyrroles are added to Freon 141.
This is the first stabilization method.

Desirable phenols in the present invention include phenol, cresol, xylenol, propylphenol, thymol, ineugenol, 5-methyl-4-inglobylphenol, tert-butyl phenol, and methoxyphenol.

As virols, d,N-methylpyrrole and N-ethylpyrrole are m-1L.

These phenols and pyrroles may be used alone, but it is also possible to use two or more types in combination. Further, it is also possible to use in combination with stabilizers added for other reasons such as light stabilizers and metal anticorrosive agents.

The amount added to Freon 141 is usually 1 to 0.1 weight, preferably 1 to 50 to the entire composition.
The weight is p-. If it is less than 1% by weight, the effect is not sufficient, and if it is more than 0.1% by weight, it is unnecessary and uneconomical.

Friend, the method of the present invention is also applicable and effective to mixed solvents containing Freon 141 as a main component. The mixed solvent of Freon 141 referred to here refers to the mixed solvent of Freon 141 with methanol, ethanol, isopropyl alcohol, Alcohols such as tert-butanol, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, hydrocarbons such as cyclohexane, chlorine-ratio hydrocarbons such as methyl chloroform, etc. .

(Example) The present invention will be explained below using examples. In addition, the stability tests described in the Examples were conducted in accordance with the first method.

Stability test samples 200x were placed in a 72-meter tube equipped with a reflux condenser and an oxygen inlet tube.
Place in a hard glass-backed Erlenmeyer flask. Add to this a well-polished, thoroughly washed, and dried mild steel piece (JIS-
Immerse one piece of G-Ro1415PCC-B, 2X6X20Ill) into the sample, and add another piece of the same quality (2X1!1X20
(1) is suspended in the vapor phase above the sample liquid surface. The tip of the oxygen introduction tube is immersed in the liquid, and water-saturated oxygen bubbles are passed through it at a rate of 10 to 12 bubbles per minute at 150W.
Heat with a frosted light bulb and cool water 1:? so that the sample condenses at less than half the height of the reflux condenser tube. ! -Adjust. 4
After 8 hours, the sample is cooled to room temperature. Measure the pH and acidity of the sample solution using the following method.

pH: Add 50 cc of neutral distilled water to 50 cc of P, mix vigorously for about 3 minutes, let stand to separate the aqueous layer, and measure the pH of the aqueous layer with a glass electrode pH meter.

Acidity: Weigh 100 grams of the sample into a 250 cc Erlenmeyer flask, use bromothymol blue as an indicator, and measure 0.
Titrate with a methanol solution of 0.1N caustic soda, and convert the acid content in the 5 samples to the amount of HCL from the amount of diluted caustic soda required for neutralization, and calculate the acidity level.

Examples and Comparative Example 1 Stability tests were conducted on Freon 141 to which the stabilizers shown in Table 1 were added. The results are shown in Table 1. The abbreviations of stabilizers shown in Table 1 are defined as follows.

BHT: 2,6-tert-butyl-4-methylphenol BHA: 3-tert-butyl-4-human/anisole MPP: 5-1-f-4-isopropyl-phenol NMP: N-methylvirol Table 1 Examples and Comparative Example 2 Stability tests were conducted on Freon 141 containing 18.8% ethanol by weight, to which the stabilizers shown in Table 2 were added. The results are shown in Table 2.

Table 2 Experimental Example and Comparative Example 6 Incubanol 16,8% ffi, Nitromethane 1
．． A stability test was conducted on a mixture of Freon 141 containing zero weight tri and added with the stabilizer gold shown in Table 5.

The results are shown in Table 3.

Table 3 Examples and Comparative Example 4 Stability tests were conducted on Furo/141 containing 10 weight solutions of benzotriazole to which the stabilizers shown in Table 4 were added. The results are shown in Table 4.

Table 4 Examples and Example 5 Nitromethane 1% by weight 2-(2'-hydroxy-
A stability test was conducted on Freon 141 containing 10% by weight of 5'-methylphenyl)-benzotriazole to which the stabilizer shown in Table 5 was added. The results are shown in Table 5.

Table 5 (Effects of the Invention) As described above, the present invention has a remarkable effect of stabilizing Freon 141 or a solvent mainly composed of Freon 141 even under severe conditions such as an oxidizing atmosphere, and is suitable for industrial use. Give a meaningful way.

Claims (1)

[Claims] 1,2 characterized by adding phenols or pyrroles to 1,2-dichloro-1-fluoroethane
- Method for stabilizing dichloro-1-fluoroethane.