JP3397435B2 - Purification method of fluorinated inert liquid - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for obtaining a fluorine-based inert liquid which produces less hydrogen fluoride when heated and used.

[0002]

2. Description of the Related Art Fluorine-based inert liquids are chemically and thermally stable, have good electrical insulation and thermal conductivity, and are nontoxic, so they are used for electrical insulation of transformers and the like. Used for liquids, liquids for electronic parts, liquids for reliability tests, liquids for vapor phase soldering, etc. However, there is a problem that hydrogen fluoride is generated when the fluorine-based inert liquid is used in a heated state. Hydrogen fluoride is highly corrosive and highly toxic, and causes problems in terms of corrosion of equipment materials, deterioration of electrical insulation, and safety for the human body.

Therefore, conventionally, a method for purifying a fluorine-based inert liquid has been proposed. For example, a method of purifying by distillation or gas chromatography, a method of refluxing an aqueous solution of an alkali metal hydroxide such as an aqueous solution of sodium hydroxide and a secondary amine such as diisobutylamine, and a fluorine-based inert liquid for a long time (special characteristics Kaisho 58-96061
JP-A-2-36155), a method of heat-treating a specific fluorine-based inert liquid (JP-A-2-36155), and the like. However, in any of the above methods, it is difficult to sufficiently reduce the generation of hydrogen fluoride, and there has been a demand for a method of obtaining a fluorine-based inert liquid having excellent stability.

[0004]

Therefore, the present inventors have found that
We have continued our research for the purpose of obtaining a fluorine-based inert liquid that produces less hydrogen fluoride when heated.

[0005]

As a result, it has been found that the above object can be achieved by contacting a fluorine-based inert liquid with water or steam at a temperature above 100 ° C. and up to 400 ° C. Has been completed.

That is, the present invention is a method for purifying a fluorine-based inert liquid, which comprises contacting the fluorine-based inert liquid with water or steam at a temperature of more than 100 ° C. and up to 400 ° C.

As the fluorine-based inert liquid to be purified in the present invention, known ones can be used without any limitation. In general, a compound in which all the hydrogen atoms of an organic compound having a carbon-hydrogen bond are replaced by fluorine atoms, or, when the organic compound having a carbon-hydrogen bond contains an unsaturated bond, substitution by a fluorine atom and an unsaturated bond A compound obtained by addition of a fluorine atom to
Those that are liquid at room temperature are preferable.

Specific examples thereof include compounds such as perfluoroalkanes, perfluoroethers and perfluorotertiary amines. Particularly, perfluoro tertiary amines are preferable because they have a large effect according to the present invention. Examples of such a fluorine-based inert liquid include perfluoroalkanes such as perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, perfluorononane, and perfluoromethylcyclohexane.Perfluoroethers include perfluorodibutyl ether and perfluoro ( 2-butyltetrahydrofuran), perfluoro (2-propyltetrahydropyran), and the like, as perfluoro tertiary amines, perfluorotrihexylamine, perfluorotripentylamine, perfluorotributylamine,
Perfluorotripropylamine, perfluoro (N,
N-dimethylhexylamine), perfluoro (N, N
-Dimethylcyclohexylamine), perfluorotriethylamine and the like. These may be used alone or as a mixture of two or more kinds. Also,
A fluorine-based inert liquid which has been previously neutralized, washed with water, distilled or purified by a known method may be used.

As a method for producing the fluorine-based inert liquid, any conventionally known method can be used without any limitation. For example, an electrolytic fluorination method, a direct fluorination method using fluorine gas, a fluorination method using a high-valent metal fluoride such as cobalt trifluoride, or a polymerization or co-polymerization of a monomer in which hydrogen atoms are substantially entirely replaced with fluorine atoms. A method of polymerizing, a method of appropriately combining these, or the like is suitably adopted.

A feature of the present invention is that these fluorine-based inert liquids are contacted with water or steam at a temperature of more than 100 ° C. and up to 400 ° C.

The water used in the present invention may be industrial water, sea water or the like, but it is preferable to use clean water such as ion exchange water, distilled water or tap water. Further, the steam used is not particularly limited, and steam generated by an ordinary boiler or pressurized steam can be used. Furthermore, if the pressure at the time of contact is normal pressure,
It goes without saying that the above-mentioned water is vaporized to become steam. The amount of water or water vapor used is not particularly limited, but is preferably in the range of 0.01 to 50 mol per 1 mol of the fluorine-based inert liquid used,
It is more preferably in the range of 30 mol.

The temperature at which the fluorine-based inert liquid is brought into contact with water or water vapor may be in the range of more than 100 ° C to 400 ° C. When the contact temperature is 100 ° C. or lower, the effect of the present invention is poor, and when it is higher than 400 ° C., the decomposition of the fluorine-based inert liquid increases, which is not preferable. When the contact temperature is high, the effect of suppressing the generation of hydrogen fluoride is great, but since the decomposition of the fluorine-based inert liquid also occurs, the temperature is 260 ° C to 34 ° C.
It is more preferably in the range of 0 ° C. In particular, the temperature at which the fluorine-based inert liquid is brought into contact with water or steam is 30
The range of 0 ° C. to 330 ° C. is particularly preferable because the amount of loss due to the purification of the fluorine-based inert liquid is minimized and the effect of suppressing hydrogen fluoride generation is large. However, when the adsorbent described below is used in combination with water or steam, the contact temperature can be lowered by about 30 ° C, and a particularly preferable temperature range can be set to 270 ° C to 300 ° C.

As a heating method, any conventionally known method can be used without limitation, and heating may be performed using a heater or a heating furnace with electricity, fuel, steam, a heat medium or the like as a heat source.

The contact time is not particularly limited, but generally it may be selected from the range of 0.01 seconds to 100 hours. According to the present invention, a sufficient effect can be obtained in an extremely short time, and the yield may decrease due to contact for a long time.
More preferably 0.1 to 15 seconds, and particularly preferably 0.1.
5 to 7 seconds.

The method of contacting may be any of pressure, normal pressure, batch type, continuous type, countercurrent type, cocurrent type and the like. Further, they may be contacted in a liquid state, a gas state, or a gas-liquid mixed state. When contacting in a liquid state or a gas-liquid mixed state, a method of contacting while stirring with a pump, a stirrer, blowing nitrogen gas, steam or the like is preferable. When they are brought into contact with each other in a gas state, it is preferable to use a filler in order to sufficiently mix the vaporized fluorine-based inert liquid and water vapor. As a filler,
A commercially available Raschig ring made of stainless steel or nickel may be used. According to the present invention, since a sufficient effect can be obtained in a short time, the mode of continuously contacting in a gaseous state under normal pressure is preferably adopted from the viewpoint of safety, cost, manpower and productivity.

As the material of the apparatus, metal materials such as iron, stainless steel, nickel, monel and hastelloy and non-metal materials such as silicon carbide, carbon and alumina can be used, but nickel, monel and carbon are preferably used. .

Further, when the fluorine-based inert liquid is brought into contact with water or water vapor, the effect of the present invention can be enhanced by carrying out in the presence of an adsorbent. As the adsorbent, it is preferable to use activated carbon, silica, alumina, natural clay minerals such as allophane and zeolite, and synthetic zeolite. Among these, activated carbon, silica, alumina, and allophane can further enhance the effect of the present invention. Therefore, it is preferably used. Furthermore, activated carbon and allophane are most preferred.

The type of activated carbon is not particularly limited, and plant-based, coal-based, petroleum-based activated carbon or the like can be used. In particular, plant-based carbon derived from wood, charcoal, and coconut shell charcoal, and coal-based activated carbon derived from bituminous coal and lignite are preferably used. As the shape of the activated carbon, powdered coal, crushed coal, granulated coal or the like can be used.

Allophane is an amorphous clay mineral which is a naturally occurring hydrous silicate of aluminum (nSiO ₂ Al ₂ O ₃ mH ₂ O), and commercially available ones can be used.

The type of silica is not particularly limited, and amorphous silica, crystalline silica, soluble silica, silica hydrate and the like can be used.

The type of alumina is not particularly limited, and amorphous alumina, crystalline alumina, alumina hydrate and the like can be used.

The adsorbent may be in the form of powder, granules or granules without particular limitation. The particle size of the adsorbent is preferably small from the viewpoint of contact efficiency with the fluorine-based inert liquid, and it is preferable to select an adsorbent having an average particle size of less than 9 mm. Practically, 0.3 to 5 mm is suitable.

The amount of the adsorbent used is not particularly limited, but is 0.05 to 20 per 100 parts by weight of the fluorine-based inert liquid.
It is preferable to select from 0.1 to 10 parts by weight, more preferably 0.1 to 10 parts by weight. The contact method may be such that the fluorine-based inert liquid and water or steam are brought into contact with each other while dispersing the adsorbent, or the fluorine-based inert liquid and water or steam are introduced into the column packed with the adsorbent. Then, the fluorine-based inert liquid may be brought into contact with water or steam. The adsorbent may be subjected to a pretreatment, if necessary, before use.

When the adsorbent is used, the amount of water or water vapor to be brought into contact with the fluorine-based inert liquid is in the range of 10 to 30 mol per 1 mol of the fluorine-based inert liquid used. It is particularly preferable because the adsorbent can be used for a long period of time with little deterioration of the agent.

Hydrofluoric acid is generated by bringing the fluorine-based inert liquid into contact with water or steam. Therefore, it is preferable to neutralize the fluorine-based inert liquid with an alkaline aqueous solution. As the alkaline aqueous solution, an aqueous solution of alkali metal or alkaline earth metal such as sodium hydroxide, potassium hydroxide, calcium hydroxide, or ammonia water may be used. Further, the effect of the present invention can be further enhanced by bringing the alkaline aqueous solution into contact with the alkaline aqueous solution under the conditions that the alkaline concentration is 5 to 50 wt%, the temperature is 70 to 100 ° C., and the contact time is 5 to 50 hours. Further, in order to use iron or SUS as a container material by contacting the fluorine-based inert liquid with the alkaline aqueous solution, the alkali concentration of the alkaline aqueous solution is preferably 5 to 20% by weight. Further, the fluorine-based inert liquid may be brought into contact with water or water vapor, and then the fluorine-based inert liquid and water or water vapor may be directly introduced into the alkaline aqueous solution.

After bringing the fluorine-based inert liquid into contact with water or water vapor, the fluorine-based inert liquid and water are separated regardless of the neutralization operation. Since the fluorine-based inert liquid is insoluble in water and has a larger specific gravity than water, it can be easily separated by allowing it to stand. Since water is dissolved in the separated fluorine-based inert liquid, it is preferable to carry out dehydration operation using a conventionally known distillation operation or dehydration agent.

[0027]

EFFECTS OF THE INVENTION According to the present invention, by contacting a fluorine-based inert liquid with water or steam at a temperature of more than 100 ° C. and up to 400 ° C. It is possible to obtain a fluorine-based inert liquid with extremely low generation. In addition, the effect that the electrical insulation of the fluorine-based inert liquid is unlikely to decrease for a long period of time is also recognized.

The reason for this is not clear, but the present inventors presume as follows. That is, the fluorine-based inert liquid contains an extremely small amount of by-products even after performing distillation or a known purification method, and these by-products are gradually decomposed to cause fluorination. Although hydrogen is generated, it is considered that most of the by-products are decomposed by carrying out the method of the present invention, which increases the stability of the fluorine-based inert liquid.

The fluorinated product purified according to the present invention is particularly required to have inertness and stability as a liquid for electric insulation, a liquid for electronic parts, a liquid for reliability test, a liquid for vapor phase soldering and the like. It can be used suitably for the purpose.

[0030]

EXAMPLES The following examples are given to more specifically describe the present invention, but the present invention is not limited to these examples. Hereinafter, the fluorine-based inert liquid is abbreviated as IL.

Example 1 Using hydrofluoric acid anhydride and tripentylamine as raw materials, the concentration of the latter was set to 10% by weight, and electrolytic fluorination was carried out using a nickel electrolytic cell (electrode area 15 dm ² , current 30 A, capacity 6 L). I went. While continuously supplying anhydrous hydrofluoric acid and tripentylamine, the produced fluorinated product was intermittently withdrawn from the lower portion of the electrolytic cell. This was contacted with 50% fluorine gas at 130 ° C., and then contacted with 5% aqueous sodium hydroxide solution at room temperature to neutralize hydrogen fluoride and fluorine gas. Further, vacuum distillation was performed to obtain perfluorotripentylamine as IL.

Inner diameter 15.8 filled with Ni Raschig rings
mm, 400 mm long Ni reactor was heated to the temperature shown in Table 1 by an electric ribbon heater (effective heating part capacity 72 cm ³ , reaction pressure was normal pressure), and perfluorotripentylamine and water were metered from each side. Continuously supplied. The amount of perfluorotripentylamine supplied was calculated from the equation (1), and is shown in Table 1.
The contact time was adjusted so that the contact time at the predetermined temperature was as shown in. The water supply amount was calculated from the equation (2), and a predetermined amount was supplied.

IL supply rate (g / sec) = (V / S) (1 / c + 1) (273 / T + 273) (M / 22.4) (1) Water supply rate (g / sec) = (V / S) (c / c + 1) (273 / T + 273) (18 / 22.4) (2) where V: Effective heating part capacity (l) S: Contact time (sec) c: Water / IL supply Ratio (molar amount) T: Contact temperature (° C) M: Molecular weight of IL The gaseous product discharged from the reactor is liquefied by passing through a Teflon-made reflux device, and then placed in a Teflon-made receiver located at the bottom. Pentylamine and acidic water of hydrofluoric acid were recovered. Then, perfluorotripentylamine and hydrofluoric acid acid water were neutralized with an 8% NaOH aqueous solution, and liquid was separated using a separating funnel to obtain purified perfluorotripentylamine. The recovery rate in Table 1 is
Percentage of purified perfluorotripentylamine weight recovered per weight of perfluorotripentylamine fed per unit time.

100 g of the purified perfluorotripentylamine was placed in a 200 ml eggplant-shaped flask having a reflux condenser placed above to heat the solution, and boiled under atmospheric pressure for 48 hours. The liquid temperature was 217 ° C. During this time, 80 ml / m
Nitrogen gas at an in flow rate was blown into the solution for 48 hours, and the generated hydrogen fluoride was absorbed in 100 ml of a 0.01 mol / l potassium hydroxide aqueous solution. The concentration of fluorine ions contained in this potassium hydroxide aqueous solution is measured with an ion chromatograph analyzer (Model IC100, manufactured by Yokogawa-Hokushin Electric Co., Ltd.) to determine the amount of hydrogen fluoride generated, and the amount of hydrogen fluoride generated per unit weight of IL. It was The results are also shown in Table 1. The amount of hydrogen fluoride generated during boiling for 48 hours is called the amount of HF generated.

For reference, Table 1 shows the results of determining the HF generation amount of perfluorotripentylamine when the temperature deviated from the temperature specified in the present invention. It was marked as 1. In addition, Comparative Example No. No. 2 is a comparative example No. when water was not supplied. 3 is the result of obtaining the HF generation amount of perfluorotripentylamine before purification according to the present invention.

[0036]

[Table 1]

Example 2 As IL, IL was 300 ° C. in the same manner as in Example 1 except that perfluorotributylamine, perfluorotriethylamine, perfluorohexane, perfluorodecalin, perfluorodibutylether, and perfluoro (2-butyltetrahydrofuran) were used. After contacting with a 5-fold molar amount of water for 5 seconds for neutralization and separation, the amount of HF generated was determined. The results are shown in Table 2. In Table 2, the amount of hydrogen fluoride generated during boiling for 48 hours using IL as it is without contacting with water at 300 ° C. is also shown as the amount of HF before purification. did.

[0038]

[Table 2]

Example 3 As IL, perfluorotripropylamine (bp.130
(C) was used, and in the same manner as in Example 1, under the temperature conditions shown in Table 3, the mixture was contacted with a 5-fold molar amount of water for 5 seconds, neutralized and separated, and then the amount of HF generated was determined. The results are shown in Table 3.
In addition, Table 3 also shows the results of determining the HF generation amount of perfluorotripropylamine before purification as a comparative example.

[0040]

[Table 3]

Example 4 Under the conditions shown in Table 4, 20 times the molar amount of IL was used under the same conditions as in Example 1 except that perfluorotripentylamine was used as IL and an adsorbent was used as the packing material of the reactor. After contacting with water for 5 seconds, neutralizing and separating, then HF
The amount generated was measured. The results are shown in Table 4.

The adsorbent used was activated carbon (trade name "Shirasagi KL", crushed charcoal made from wood, manufactured by Takeda Pharmaceutical Co., Ltd., average particle size 1 m.
m), allophane (trade name "SECARD KW", made by Shinagawa White Brick, average particle size 2 mm), silica (trade name "Wakogel", manufactured by Wako Pure Chemical Industries, average particle size 3 mm), alumina (basic activated alumina, Wako Pure Chemical Industries, average particle size 2m
m).

For reference, Table 4 also shows the results when an adsorbent was used without supplying water.

[0044]

[Table 4]

Example 5 Example 1 was repeated except that perfluorotripentylamine was used as IL, and activated carbon (trade name “Shirasagi KL”, crushed charcoal made from wood, manufactured by Takeda Chemical Co., Ltd., average particle size 1 mm) was filled in the reactor. In the same manner as above, IL was brought into contact with 280 ° C. and 20 times the molar amount of water for 5 seconds to recover IL and water. The IL was then separated from the water using a separatory funnel. This IL was put in an SUS container equipped with a stirrer together with an alkaline aqueous solution, and brought into contact with each other while stirring at a stirring speed of 300 rpm under the conditions shown in Table 5. After separating IL from the alkaline aqueous solution, the amount of HF generated was determined. The results are shown in Table 5.

[0046]

[Table 5]

Example 6 600 g of perfluorotripentylamine and 50 g of water were placed in a 1 L autoclave equipped with a stirrer, and heated at a temperature of 300 ° C. for 3 hours under pressure with stirring at a stirring speed of 100 rpm. After lowering the temperature to room temperature,
IL and water were collected, neutralized and separated to obtain IL. The recovery rate was 96.1%. The amount of HF generated was measured and found to be 0.28 mg / kg.

Example 7 In the same manner as in Example 1, except that perfluorotributylamine was used as IL, the IL was brought into contact with water at 300 ° C. and a 5-fold molar amount for 5 seconds to recover IL and water. Then, IL was separated from water using a separating funnel to obtain purified perfluorotributylamine. The purified perfluorotributylamine was placed in a round bottom flask equipped with a reflux condenser at the top and the solution was heated to 100 ° C. for 10 days.

The volume resistivity and the dielectric breakdown voltage of the purified perfluorotributylamine before and after heating for 10 days were measured according to JIS except that the respective measurement temperatures were 25 ° C.
It measured based on C2101. Before measurement, dehydration with silica gel and filtration with a 0.2 μm membrane filter were performed. The volume resistivity and the dielectric breakdown voltage are 5.4 × 10 ¹⁵ each before heating at 100 ° C for 10 days.
Ω cm, value of 58 kV, after heating 5.2 × 10 ¹⁵ Ω respectively
The values were cm and 55 kV.

On the other hand, as a comparative example, perfluorotributylamine before purification was heated to 100 ° C. for 10 days, and the volume resistivity and dielectric breakdown voltage of perfluorotributylamine before and after heating were measured in the same manner as above.
The volume resistivity and dielectric breakdown voltage are 4.7 x 1 before heating.
0 ¹⁵ Ω cm, 55 kV, 2.3 × 10 after heating
The value was ¹³ Ω cm and 35 kV.

Example 8 The same procedure as in Example 7 was carried out except that perfluorotripentylamine was used as IL, and the perfluorotripentylamine before and after contact with water at 300 ° C. was heated for 10 days before and after heating at 100 ° C., respectively. The volume resistivity and dielectric breakdown voltage of perfluorotripentylamine were measured.
The results are shown in Table 6.

[0052]

[Table 6]

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C07C 43/12 C07C 43/12 209/84 209/84 211/15 211/15 (72) Inventor Masahiro Shirai Mikage, Tokuyama City, Yamaguchi Prefecture Town No. 1 Tokuyama Co., Ltd. (56) Reference JP-A 1-254632 (JP, A) JP-A 2-71802 (JP, A) JP-A 3-11023 (JP, A) JP-A 7-267884 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 17/38 C07C 41/34 C07C 209/84 C07B 63/00

Claims (3)

(57) [Claims] 1. A fluorinated inert liquid is heated at a temperature exceeding 100.degree.
A method for purifying a fluorine-based inert liquid, which comprises contacting with water or steam at a temperature of up to 00 ° C. 2. A fluorine-based inert liquid is heated at a temperature exceeding 100.degree.
A method for purifying a fluorine-based inert liquid, which comprises contacting with water or steam in the presence of an adsorbent at a temperature of up to 00 ° C. 3. A fluorine-based inert liquid is heated at a temperature of more than 100.degree.
A method for purifying a fluorine-based inert liquid, which comprises contacting with water or steam at a temperature up to 00 ° C. and then contacting with an aqueous alkali solution.