JPH0482845A - Purification of perfluorocarbon - Google Patents

Abstract

PURPOSE:To quickly and smoothly remove non-condensing substances such as air dissolved in a liquid perfluorocarbon using simple procedure and simple apparatus by subjecting a liquid perfluorocarbon layer to agitation treatment or vibration treatment. CONSTITUTION:A liquid layer l of a perfluorocarbon is subjected to agitation treatment with a magnetic stirrer 3, etc., and/or vibration treatment with ultrasonic vibrator, etc. In the above process, the evaporation of the perfluorocarbon is prevented e.g. by covering the liquid layer 1 with a layer 2 of a liquid insoluble in the perfluorocarbon and having a thickness of >=2mm. The non- condensing substance such as air dissolved in the perfluorocarbon liquid can smoothly and quickly be removed by a simple process using a simple apparatus. A perfluorocarbon having high purity to be usable as it is in practical use such as thermal medium, insulation oil and cleaning liquid can be produced in high treating efficiency and purification degree by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for purifying perfluorocarbon with excellent processing efficiency.

Conventional technologies and issues CFCs, which are used in various technical fields as heat carriers, insulating oils, cleaning fluids, etc., have been pointed out as substances that deplete the ozone layer, and as alternatives to them are sought after, perfluorocarbons have been proposed. There is.

However, since gases such as air are dissolved in perfluorocarbon in an amount of several tens of milliliters per 100 ml, it is difficult to obtain a high-purity product that can be used practically as a heat medium in heat pipes, etc., unless it is thoroughly degassed and purified. In the same way as in the case of fluorocarbons, it takes several times as many processing steps or processing time to treat non-condensable substances such as air until bubbles no longer appear using the freezing method or equilibrium vapor pressure method, and it takes about 500 m
There was a problem in that it took several hours to purify perfluorocarbon No. 1. Furthermore, even if the purified liquid was distilled and injected into the heat pipe, the heat pipe that had been injected with 5 to 30% of the original fraction did not show satisfactory thermal resistance, which did not occur in the case of fluorocarbons. This phenomenon occurred, and there was a problem that the conventional method could not sufficiently purify the product.

Means for Solving the Problems The present inventors have conducted extensive research to overcome the above-mentioned problems, and have unexpectedly discovered that the object can be achieved by a stirring process, etc., and have accomplished the present invention.

That is, the present invention provides a method for purifying perfluorocarbon, which is characterized by subjecting a liquid layer of perfluorocarbon to a stirring treatment or a vibration treatment.

By stirring or vibrating the perfluorocarbon liquid layer, non-condensable substances such as air dissolved in the perfluorocarbon liquid can be smoothly and quickly removed. The reason for this is unknown, just as conventional methods do not yield sufficient purified products even when treated until no bubbles of non-condensable substances are produced.

Exemplification of Components of the Invention The target of the present invention is perfluorocarbon. Among them, C1F 2n+2 type having an average molecular weight of 100 to 1000 and a boiling point of 30 to 300°C. Less than 1% by weight of foreign elements such as oxygen, nitrogen, and hydrogen,
In particular, it may be contained in an amount of 0.1% by weight or less. Such perfluorocarbons are commercially available, for example, under the trade name "Fluorinert" (3M).

Purification is carried out by stirring or vibrating the perfluorocarbon liquid layer 1, as illustrated in the accompanying drawings. At this time, it is preferable to take measures to prevent the perfluorocarbon from volatilizing, such as spinning (a method of providing a liquid layer 2 insoluble in the perfluorocarbon liquid layer 1 on top of the perfluorocarbon liquid layer 1). The perfluorocarbon liquid layer 1 is stirred through a stirrer 3. In the figure, 4 is a container, 5 is a branch pipe,
6 is the cook.

The liquid (2) used above may be one that is insoluble in perfluorocarbon, particularly has a solubility of 11,000 pp or less, and has a specific gravity lighter than the perfluorocarbon so that it is located in the upper layer. Water is generally used. Although the amount of liquid used depends on the surface area based on the shape of the container, etc., it is generally preferred that a layer with a thickness of at least 2 mm be formed on the liquid layer of perfluorocarbon.

In the present invention, there is no particular limitation on the method of stirring treatment or vibration treatment. The purpose can be sufficiently achieved by stirring treatment using a magnetic cooler or the like, or vibration treatment using an ultrasonic vibration method or the like. Note that image processing of stirring and vibration may be added. Further, by adding pressure reduction treatment by suction or the like during the treatment, the treatment time can be shortened. The treatment temperature may be determined as appropriate within the range from above the freezing temperature of the perfluorocarbon to below the boiling point. In the case of high-temperature treatment, the above-mentioned volatilization prevention liquid used as necessary has a higher boiling point than perfluorocarbon.

The perfluorocarbon purified by the method of the present invention can be used as a high-purity product as it is, for example, as a heating medium, insulating oil, etc.
It may be put to practical use as a cleaning liquid or the like, or it may be further distilled and put to practical use. Further, in order to further improve the purity, other purification methods such as freezing method and equilibrium vapor pressure method may be used in combination.

Effects of the Invention According to the present invention, the liquid layer of perfluorocarbon is stirred,
Non-condensable substances such as air dissolved in perfluorocarbon liquid can be removed smoothly and quickly with simple operations such as applying vibration or vibration, improving processing efficiency and purity. Are better.

Example 1 Average molecular weight 340, boiling point 56 in a 500 ml flask
Fluorinert (tetradecafluorohexane) 1 °C
00 ml and 70 ml of water were placed, and under the arrangement of a magnetic stirrer, stirring was started at room temperature with a water layer formed on top of the Fluorinert liquid layer based on its light specific gravity, and the stirring process was performed for 20 minutes to purify. I got the liquid.

Example 2 A purified liquid was obtained according to Example 1, degassed twice by freezing with liquid nitrogen, and then distilled to obtain a purified liquid consisting of a distillate.

Example 3 A purified liquid was obtained in the same manner as in Example 1, except that instead of the stirring method using a magnetic stirrer, the treatment was performed using a vibration method using an ultrasonic vibrator for 10 minutes.

Example 4 A purified liquid was obtained according to Example 3 except that water was not used.

Example 5 A purified liquid was obtained according to Example 3, which was degassed twice by freezing with liquid nitrogen, and then distilled to obtain a purified liquid consisting of a distillate.

Comparative Example 1 100 ml of the same Fluorinert as in Example 1 was degassed six times by freezing with liquid nitrogen to obtain a purified liquid.

Comparative Example 2 Fluorinert 100ml same as Example 1 was heated to -20°C.
A purified liquid was obtained by degassing using the equilibrium vapor pressure method at a vacuum degree of 30 Torr.

20ml of the purified liquid obtained in the evaluation test example and comparative example was prepared with an outer diameter of 15.88
A copper pipe with an inner diameter of 14.3 mm and a length of 840 mm and an internal groove was vacuum injected at a vacuum level of 8 XIO" Torr and sealed to form a heat pipe.
The thermal resistance at 0W was investigated.

The results are shown in the table.

The table also shows the processing time required to obtain purified liquids in Examples and Comparative Examples.

[Brief explanation of the drawing]

The accompanying drawings are explanatory diagrams illustrating the method of the present invention. 1: Perfluorocarbon liquid layer 2: Insoluble liquid layer 3: Magnetic stirrer 4: Container 5: Branch pipe 6: Cook

Claims (1)

[Claims] 1. A method for purifying perfluorocarbon, which comprises subjecting a liquid layer of perfluorocarbon to stirring or vibration treatment.