JPS5851996B2 - Stabilization method for 1,1,2↓-trichloro↓-1,2,2↓-trifluoroethane solvent - Google Patents

Description

Detailed Description of the Invention The present invention uses 112-trichloro-122-trifluoroethane (hereinafter referred to as Freon 113) and 1,1,2-trichloro-1,2,2-trifluoroethane-based mixed solvent (hereinafter referred to as Freon 113). The present invention relates to a method for stabilizing a Freon 113-based mixed solvent (referred to as a mixed solvent based on Freon 113), and more specifically, its purpose is to prevent the decomposition of the solvent and to prevent corrosion of metal materials.

The Freon 113-based mixed solvent of the present invention is one that has been modified by mixing with various organic solvents within a range that does not impair the solvent properties of Freon 113. Specific examples of organic solvents that can be mixed with Freon 113 include: Examples include methanol, ethanol, impropatol, acetone, methylene chloride, and the like.

Freon 113 and Freon 113-based mixed solvents are excellent as low-toxic and nonflammable solvents, and are useful for cleaning films and magnetic tapes, cleaning electronic and electrical equipment such as printed circuit boards, relays, and motors, lenses, watches, etc. It is widely used for a variety of purposes, including cleaning optical and precision equipment, degreasing solvents for plastic processing, and dry cleaning solvents.

In addition to the above-mentioned low toxicity and non-flammability, this solvent also has the properties of high stability, and under normal usage conditions, trichlorethylene, tetrachloroethylene, 1,1.
The addition of stabilizers required with chlorinated solvents such as 1-1-lichloroethane is not required.

However, it is known that if the solvent coexists with water at a saturation solubility or higher in contact with metal materials such as iron, aluminum, copper, brass, etc., its stability cannot be maintained over a long period of time.

For example, as an object containing a large amount of water is cleaned, the amount of water in the solvent gradually increases, and especially when the solvent comes into contact with the metal material, the metal material acts as a catalyst to increase the amount of water in the solvent. A hydrolysis reaction occurs, and the acid produced at that time corrodes metal materials.

Therefore, when the solvent is used together with the metal material in the presence of water, it is first required to improve its stability.

On the other hand, as stabilizers for lower aliphatic fluorinated chlorinated hydrocarbons, primary and secondary alkyl amines (Special Publications
-13724 Publication), a mixture of propylene oxide and nitromethane (Japanese Patent Publication No. 45-124 ss)
, halogenated benzene (Japanese Patent Publication No. 45-32048), benzimidazoles (Japanese Patent Publication No. 45-35319), or mixtures of epoxides and olefins (Japanese Patent Publication No. 49-37031).

However, these were not necessarily satisfactory in terms of sufficiently stabilizing the solvent in the presence of water.

Therefore, the present inventors conducted various studies in accordance with the above objectives, and as a result, it was discovered that a surprising stabilizing effect can be exerted by adding a combination of nitromethane and acrylic ester to Freon 113 or Freon 113-based mixed solvent. This is the heading that led to the present invention.

The details of the present invention will be explained below.

In the present invention, acrylic esters used together with nitromethane include methyl acrylate, ethyl acrylate, n-butyl acrylate, and the like.

Furthermore, the present invention is characterized in that nitromethane and acrylic acid ester are used in combination, and when each is used alone, the stabilizing effect is small or no stabilizing effect can be exerted. In the present invention, the amount of stabilizer added to the solvent is 0.01 to 2.00% by weight, preferably 0.10 to 1.00% by weight of nitromethane, and 0.0% by weight of the acrylic ester based on the solvent. .001-0.300% by weight
, preferably 0.003 to 0.050% by weight.

If the amount added is less than the above-mentioned amount, the stabilizing effect will not be observed, and if it is used in a large amount, the properties of the solvent will be impaired, which is not preferable.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 7, Comparative Examples 1 to 5 Water added with nitromethane and acrylic ester 0
．． Freon 113 containing 3% by weight (saturated solubility above ground)
(1) in a sample bottle with a capacity of 100 m1, and sufficiently layered test pieces of iron, aluminum, copper, and brass (dimensions 40 x 4
After immersing the tube (0x2 mm), the tube was sealed and left at room temperature.

The number of days for discoloration to appear on the test piece was observed, and changes in the appearance of the test solution after 15 days and the state of corrosion of the Test 1 test piece were evaluated as follows.

◎: No change ○: Slight discoloration △: Small corrosion ×: Severe corrosion Also, in iron piece tests where corrosion is severe, the amount of increase in acid content (acid amount) in the test liquid is used as an auxiliary means to judge the stabilizing effect. was also measured.

The test results are shown in Table 1.

In addition, in Comparative Example 1, when no stabilizer is added, Comparative Examples 2-
5 shows the results when the amount of nitromethane or acrylic ester added was varied.

From these results, it is clear that by adding nitromethane and acrylic acid ester in combination, a greater stabilizing effect is exerted than when each is added alone.

Examples 8 to 13, Comparative Examples 6 to 8 0.3% by weight of water to which nitromethane and methyl acrylate were added as acrylic ester (saturation solubility or higher)
A stability test was conducted in the same manner as in Examples 1 to 7 for the Freon 113 mixed solvent containing the following.

The results are shown in Table 2.

In addition, Comparative Examples 6 to 8 are the results when no stabilizer was added.

As is clear from Table 2, the stability of the Freon 113-based mixed solvent was greatly improved by adding nitromethane and methyl acrylate in combination.

Examples 14-21, Comparative Examples 9-12 0.3% by weight of water to which nitromethane and methyl acrylate were added as acrylic ester (saturation solubility or higher)
Freon 113 or Freon 113-based mixed solvent 2 containing
007711 was placed in a glass eggplant flask (with an internal volume of 300 m) equipped with a reflux condenser, a sufficient layer of iron, aluminum, copper, or brass was placed in the gas phase and liquid phase of the test liquid, and the mixture was heated at approximately 55°C for 48 hours. The mixture was heated to reflux for an hour.

After the test was completed, the corrosion status of the test piece was evaluated in the same manner as in Examples 1 to 7, and for the iron piece test, changes in the appearance of the test liquid and increase in acid content in the test liquid were also investigated.

The results are shown in Table 3.

In addition, Comparative Examples 9 to 12 are the results when no stabilizer was added.

As is clear from Table 3, the combined addition of nitromethane and methyl acrylate stabilizes Freon 113 or Freon 113-based mixed solvents in a heated state, and stabilizes not only the liquid phase but also the gas phase. It can be seen that corrosion of metal pieces is also greatly suppressed.

Claims (1)

[Claims] 1 1,1.2-t-lichloro1.2.2-1,1.2- characterized by adding a combination of nitromethane and acrylic ester to a trifluoroethane solvent
Method for stabilizing trichloro-1,2,2-trifluoroethane solvent.