JPH07116079B2 - Method for producing high quality isopropyl alcohol - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel isopropyl alcohol, and more specifically, it contains fine particles and metal ions which can be preferably used in the fields of electronic materials, medicines and the like as much as possible. Not related to a method for producing high quality isopropyl alcohol.

[0002]

2. Description of the Related Art Generally, isopropyl alcohol has been widely used as a solvent, a cleaning agent, an extractant, etc., but in the fields of electronics industry, electric precision equipment manufacturing, medicine, etc. Is required. Currently, it is said to be grades for electronic materials,
The so-called “high-quality isopropyl alcohol” generally used is isopropyl alcohol 99.
It is referred to as 99% or more and water content 0.01% or less, but according to the knowledge of the present inventor, it contains about 0.1 ppm or more as a metal content of metal compound impurities, and is mainly organic. 20 to 10 fine particles of material
About 0 / ml is contained.

When the commercially available high-quality isopropyl alcohol as described above is used, for example, in the manufacture of IC semiconductors, there often arises a problem that defective products such as irregular shapes and defective characteristics occur.

According to the studies by the present inventors, the cause of these problems is that among the metal compound impurities,
In particular, it became clear that iron, copper and sodium had a great influence. These ions remain attached to electronic materials,
Diffusion in the material leads to detrimental semiconductor properties. Above all, sodium ions have great mobility and are easily diffused in the semiconductor material, so that special attention must be paid. Also, the presence of fine particles has a particularly large effect,
It has been found that the shape of the IC semiconductor is apt to cause a characteristic defect.

As a method for producing high-quality isopropyl alcohol, a conventional purification method generally used is distillation means. Vapor of isopropyl alcohol is taken out from the upper part of the distillation column, introduced into a cooler, and liquefied there. Part of it is refluxed to the distillation column, and the rest is sent to the storage tank as product. By applying such a distillation means, in principle, most metal compound impurities and fine particles should be removed.

Therefore, if fine particles or metal compound impurities are mixed in isopropyl alcohol after distillation, it is mixed from dirt adhering to the filling container; liquid transfer operation such as filling,
It was considered to be due to contamination from the atmosphere during transportation or use. Therefore, in order to prevent such contamination of fine particles and the like, measures such as cleaning the filling container, performing a liquid transfer operation such as filling, or using a crane room as the place of use and using a sealed container have been made. However, the purpose has not been achieved yet.

The reason is that satisfactory results have not been obtained because fine particles and metal compound impurities are mixed even during the production, and a considerable amount of fine particles and the like are already present in the isopropyl alcohol itself which has undergone the purification process. Is. That is, in the actual refining, isopropyl alcohol before distillation, which is scattered by boiling in the distillation column, becomes fine mist and moves to the cooler, or when the distillation is finished at reduced pressure, the cooler, the pipe A gas containing fine particles or impurities such as the atmosphere enters the line or the storage tank and comes into contact with the distillate, so that a considerable amount of fine particles or metal compound impurities are mixed as described above.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing high-quality isopropyl alcohol in which fine particles are effectively removed and the content of metal ions is remarkably reduced. The isopropyl alcohol obtained by this method has 5 or less fine particles having a diameter of 1 μm or more in 1 ml of a solvent, iron ion of 0.05 ppm or less, copper ion of 0.02 ppm or less and sodium ion of 0.02 ppm or less. Is of high quality.

[0009]

That is, according to the present invention,
Crude isopropyl alcohol was added to a diameter of 0.
Using a process comprising a rectification device sealed with a high-purity inert gas in which the presence of fine particles of 5 μ or more is 350 particles / liter or less, and a filter having a filtration surface with a pore size of 1 μ or less, a reflux ratio of 0.5 It is characterized in that it is distilled as described above, and the effluent is filtered, the number of particles having a diameter of 1 μ or more is 5 particles / milliliter or less, iron ion is 0.05 ppm or less, copper ion is 0.02 ppm or less, and sodium. Provided is a method for producing high-quality isopropyl alcohol having ions of 0.02 ppm or less.

In the present invention, the crude isopropyl alcohol used as a starting material is isopropyl alcohol obtained from a usual synthetic process without any limitation. Particularly, isopropyl alcohol which is commercially available as a solvent grade or a grade for electronic industry is preferably used. Of course, isopropyl alcohol recovered after being used for cleaning electronic materials and the like can also be used.

The rectification apparatus used in the present invention may be a normal distillation column having a reflux mechanism. In the present invention, in combination with the effluent filtration step described below, the number of fine particles is 5 particles / milliliter or less, and iron ion is 0.05 ppm or less, copper ion is 0.02 ppm or less, and sodium ion is 0.02 ppm. To reduce to
It is necessary to operate at a reflux ratio of 0.5 or more, preferably 1 or more. It is possible to control such ultratrace impurities, especially metal compounds, by controlling the reflux ratio,
This is a very specific fact. In order to further improve the rectification efficiency, it is also preferable to increase the number of stages of the distillation column, and it is preferable that the equivalent number of stages is 3 or more.

It is an important condition that the clean gas used for the seal contains 350 particles / liter or less, more preferably 35 particles / liter or less, of fine particles having a diameter of 0.5 μm or more. The numerical value of this condition has a critical significance, and as will be apparent from Examples described later, when sealing with a gas containing more than 350 particles / liter having a diameter of 0.5 μ or more, Whereas in the present invention, it is not possible to obtain high quality isopropyl alcohol having 5 or less fine particles having a diameter of 1 μm or less in 1 ml, 3
When it is 50 or less, the high quality isopropyl alcohol of the present invention can be easily obtained. Also,
It is preferable that the clean gas used for the seal does not contain various ionic compounds and high-boiling substances, and it is desirable that the clean gas is 0.1 ppm or less.

However, in the case of ordinary gas, ionic compounds and high-boiling substances are often contained only in a small amount, which is not a problem, and when the clean gas contains a considerable amount of water, Since the water tends to be transferred to the obtained solvent, it is preferable to use it after drying with a desiccant such as silica gel, anhydrous calcium chloride, and molecular sieve. In addition, clean gas must not adversely affect the equipment. Specifically, carbon dioxide gas, helium, air, nitrogen, or the like that has been treated so as to satisfy the above conditions is used as a clean gas for sealing.

Conventionally, it was considered that solid impurities, that is, fine particles, could be completely removed from the solvent by rectification. However, in the purification of isopropyl alcohol, there is a fact that a minute amount of fine particles still exists in the distillate for unknown reasons. Therefore, in the present invention, a step of filtering with a filter having a specific filtering surface is essential. That is, the filter used for filtering the distillate has a pore size of 1 μm or less in view of its filtering performance. Moreover, it is desirable that the material is not attacked by isopropyl alcohol. Specific examples of such a filter include a Teflon 0.45 μ membrane filter and the like.

[0015]

DETAILED DESCRIPTION OF THE INVENTION A method for producing high-quality isopropyl alcohol according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a process drawing of the high quality isopropyl alcohol of the present invention. In FIG. 1, the rectification step comprises a distillation column 1, a cooler 4 for cooling the isopropyl alcohol vapor into a liquid, a tank 5 for receiving the liquid discharged from the cooler, and a line connecting these. The distillation column 1 has a heater 2 at the bottom for vaporizing isopropyl alcohol.
A can liquid outlet 3 for taking out impurities concentrated and separated by distillation and a feed port 8 for raw crude isopropyl alcohol are provided in the middle. A reflux line 6 for returning liquid isopropyl alcohol to the top of the column and a distillate withdrawing line 7 are provided below the tank 5. The distillate extraction line 7 has a filter 9 for filtering the distillate.
Through the purified liquid storage tank 11. The purified solvent is taken out from the take-out port 10 of the purified liquid storage tank 11.

In the above-mentioned manufacturing process, the distillate is filtered by the filter 9 so that a small amount of fine particles are mixed. Further, since it is sealed with a clean gas and is shielded from the gas such as the atmosphere in all the steps, a high quality state is maintained without newly mixing fine particles or metal compound impurities.

In the manufacturing process, the clean gas is sealed by forming a pressure equalizing line shown by a broken line in FIG. 1 by the clean gas obtained by the filter 12. The pressure equalization line is
This is to prevent each device in the rectification step from being pressurized or depressurized as much as possible to maintain smooth operation. As a matter of course, gas flows in and out in order to equalize the pressure with the outside air, but the filter 12 is provided to always keep the gas in the pressure equalizing line clean. Filter 1
No. 2 is not particularly limited as long as it is a filter that can obtain a gas in which fine particles having a diameter of 0.5 μ or more are 350 particles / liter or less.

As such a filter, for example,
0.3μ or 0.1μ HEPA filter (High
Efficiency Particulate Air Filter). In addition, the distillation column 1 is designed to increase the efficiency of separation by distillation.
Those having as many stages as possible are preferable, and those having a corresponding number of stages of 3 or more are particularly preferable. The reflux ratio, that is, the ratio of the amount returned through the reflux line 6 and the amount taken out through the liquid withdrawing line 7 is preferably as large as possible in order to improve the distillation separation effect, and is 0.5 or more, and more preferably 1 or more. Is preferred. The feed port 8 is preferably provided at least one stage below the uppermost stage, and particularly preferably at least three stages below in the case of a multistage distillation column having about 30 stages as shown in the examples. This is because if the feed port 8 is provided too high, the distillation effect will be reduced and impurities will not be mixed into the distillate.

[0019]

EFFECTS OF THE INVENTION According to the present invention, since all the steps such as the rectification device, the cooler, the pipeline, and preferably the storage tank are sealed with a clean gas, the fine particles mixed in the distillate are used. Is reduced and the life of the filter used for filtering the distillate is maintained for a long time. Thus, high quality isopropyl alcohol can be obtained which can be suitably used in the fields of electronic materials and medicine.

[0020]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

< Example 1 > As shown in FIG. 1, a mantle heater 50 was set.
A 0 ml round-bottomed flask was used as a can, and a 30-stage glass Aldershaw distillation column equipped with a condenser and a device for adjusting the reflux ratio at the top and 0.45 in the middle of the distillation line.
A μ membrane filter (manufactured by Toyo Roshi Kaisha, Ltd., Teflon) was provided, and then a purified liquid storage tank was installed.

Further, as shown in FIG. 1, a pressure equalizing line is provided and a HEPA filter (High Efficie) having a pore size of 0.3 μm is provided.
ncy Particulate Air Filter) and a silica gel drying cylinder were installed to make the gas in the pressure equalization line a clean gas. This clean gas was measured by a microscope method (10 liters of gas was filtered through a 0.4 μ Nyuclear membrane filter (manufactured by Nyuclear Co., Ltd.), and the number of particles on the filter was determined by a scanning microscope (magnification: 1000 times)).
The number of fine particles having a diameter of 0.5 μ or more was 35 particles / liter or less.

Isopropyl alcohol containing the impurities shown in Table 1 was put in a 500 ml can and heated with a mantle heater to carry out total reflux for 30 minutes. After that, the same liquid was supplied from the upper 5 stages at 240 ml / Ar, and the distillate amount was 2
Purification was carried out for 8 hours under the condition of 40 ml / Ar reflux ratio of 1.1 without extraction of a can. The metal ions (Fe, Cu, Na) in the liquid after purification were determined by the atomic absorption method, and the fine particles were 0.45μ membrane filter (Toyo filter paper filtration area 3
(2 mmφ), 1 liter of the liquid was filtered, and the liquid before purification of the used liquid in which particles of 1 μ or more on the filter were counted with a scanning electron microscope magnification of 1000 was analyzed by the same method. It was shown to.

Table 1

<Comparative Example 1> HEPA filter for obtaining clean gas (see FIG. 1)
12) was removed and the same procedure as in Example 1 was performed. The results are shown in Table 2.

Table 2

[Brief description of drawings]

FIG. 1 is a process drawing showing a typical process for producing a high quality isopropyl alcohol of the present invention.

[Explanation of symbols]

 1 Distillation Tower 2 Heater 3 Can Liquid Extraction Port 4 Cooler 5 Tank 6 Reflux Line 7 Distillation Liquid Extraction Line 8 Raw Material Liquid Field Port 9 Filter 10 Extraction Port 11 Purified Liquid Storage Tank 12 Filter

Claims (1)

[Claims] 1. A rectification device in which crude isopropyl alcohol is sealed with a high-purity inert gas in which the presence of fine particles having a diameter of 0.5 μ or more is 350 particles / liter or less throughout the whole process, and a pore diameter of 1 μ or less. Characterized in that it is distilled at a reflux ratio of 0.5 or more and the distillate is filtered by using a step comprising a filter having a filtration surface of 5 particles / ml or less of 1 μm or more in diameter, and Iron ion is 0.0
A method for producing high-quality isopropyl alcohol having 5 pppm or less, copper ion of 0.02 ppm or less, and sodium ion of 0.02 ppm or less.