JPS6343419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel fluorine-containing polyether and its production method and use.

The novel random halogen-containing polyether of the present invention has (a) a repeating unit represented by the formula: -(CH ₂ CF ₂ CF ₂ O)-, (b) a repeating unit represented by the formula: -(CHFCF ₂ CF ₂ O)- unit, and (c) formula: - (CF ₂ CF ₂ CF ₂ O) - Contains 2 to 200 repeating units in total, and at least 1 repeating unit (b) and (c) in total It is a compound containing

The halogen-containing polyether of the present invention has the following formula, for example: -(CH ₂ CF ₂ CF ₂ O)n- () [where n represents a number from 2 to 200]. ] It can be easily produced by fluorinating a fluorine-containing polyether having a repeating unit represented by the following.

Fluorinated polyether (), 160-300
This can be carried out by reacting fluorine gas at a temperature of 180 to 250°C. Fluorination is also possible at temperatures lower than the above temperature range, but in such a low temperature range, fluorination can be done more efficiently by reacting polyether () with fluorine gas under ultraviolet irradiation. can be done. In the post-reaction, hydrogen fluoride is inevitably produced, so it is resistant to fluorine and hydrogen fluoride under the reaction conditions, and has a wavelength of 200 nm to 400 nm, at least 300 nm to
It is necessary to protect the ultraviolet light source with a material that can transmit the required amount of light with a wavelength of 400 nm. Therefore, glasses such as quartz glass windows, which are often used in ordinary photoreactions, cannot be used in this reaction because they are corroded by hydrogen fluoride.

The light transmitting material suitably used in the present invention includes single crystal sapphire, tetrafluoroethylene/hexafluoropropylene copolymer,
Examples include transparent melt-moldable fluororesins such as tetrafluoroethylene/perfluoropropyl vinyl ether copolymer, tetrafluoroethylene/ethylene copolymer, chlorotrifluoroethylene polymer, and vinylidene fluoride polymer. It will be done.

From an industrial standpoint, single-crystal sapphire is expensive and difficult to secure in a large area, so fluorine-based resins are preferred.

When irradiating the inside of the reactor with ultraviolet rays, the surface of a transparent glass material such as quartz glass can be coated with the above-mentioned resin, and when irradiating from the outside of the reactor, a film of the above-mentioned resin can be coated. It may be used as a light transmission window. To make windows pressure resistant,
Of course, it is also possible to use these films by laminating them on a quartz plate, for example.

Light can be emitted by direct irradiation into the reaction solution, or may be irradiated through the gas phase.

The wavelength of light that can be used is 200nm to 400nm,
Preferably it is 250 nm to 350 nm.

In the fluorination reaction using ultraviolet rays, the reaction temperature is not a very important reaction condition, and it is sufficient to select a temperature that allows stirring of the reaction solution necessary for the reaction to proceed smoothly. The reaction temperature is mainly determined by the molecular weight of the raw material polyether (). in general,
Since the pour point and viscosity of the product decrease as the fluorination reaction progresses, the reaction temperature can be decreased accordingly. Practically 0 to 120℃,
Preferably reaction temperatures from room temperature to 100°C are employed.

In either fluorination method, fluorine gas may be blown into the reaction solution or may be passed through the gas phase. Furthermore, fluorine gas may be used after being diluted with an appropriate inert gas (eg, carbon dioxide, nitrogen, etc.).

As the reaction mode, both a flow type and a batch type can be adopted.

Polyether () is also a new compound, 2,
It can be produced by ring-opening polymerization of 2,3,3 tetrafluorooxetane. The manufacturing method will be explained below.

When carrying out the ring-opening polymerization, a polymerization initiator is generally used. Polymerization initiators include those that generate active halogen anions in aprotic solvents, such as alkali metal halides;
Alternatively, a compound exhibiting strong Lewis acidity is preferably used.

The amount of initiator used is not particularly limited, but
Usually 0.001 to 30 mol%, preferably 0.01 to 30 mol% based on the amount of 2,2,3,3-tetrafluorooxetane
10 mol% may be employed.

The alkali metal halide used as the polymerization initiator is not particularly limited, but for example, potassium fluoride, cesium fluoride, potassium iodide, potassium bromide, etc. are preferably used. When an alkali metal halide is used as an initiator, the product generally has the formula: A(CH ₂ CF ₂ CF ₂ O)nCH ₂ CF ₂ COF (1) where A is F, Br or I, n is 0~200
represents an integer of ]. The acid fluoride end group of this compound can be easily converted into a corresponding acid, alkali salt, ester, or amide by well-known reaction methods such as hydrolysis and esterification.

At the same time as the alkali metal fluoride as the polymerization initiator, for example, the formula: RfCOF or When using an acyl fluoride compound as shown in the formula (1), A in the formula (1) becomes the formula: RfCF ₂ O- or (However, Rf is a perfluoroalkyl group having 1 to 10 carbon atoms, and Rf' is a perfluoroalkyl group having 1 to 10 carbon atoms or the formula: In the group represented by , t represents an integer of 0 to 50. ) It is possible to synthesize a compound having a repeating unit represented by the formula: -CH ₂ CF ₂ CF ₂ O-.

Furthermore, when an acyl fluoride called FCH ₂ CF ₂ COF obtained by ring-opening of 2,2,3,3-tetrafluorooxetane is used at the same time as cesium fluoride, polymerization can be performed using an alkali metal fluoride alone. A polymer having the same structure as that obtained in the above case is obtained. This method is effective when trying to obtain a low molecular weight oligomer while controlling the molecular weight distribution.

In addition, as can be seen from the above explanation, the relatively volatile low molecular weight products contained in the polymerization product are recovered by distillation after the polymerization reaction is completed, and then used again at the same time as the alkali metal fluoride. can be reused as a polymerization initiator.

Moreover, as mentioned above, instead of using an acyl fluoride compound from the beginning, for example, a fluorine-containing epoxide that reacts with an alkali metal fluoride to form an acyl fluoride is used, and this is mixed with 2,2,
It can be reacted with 3,3-tetrafluorooxetane. For example, by reacting hexafluoropropylene oxide with cesium fluoride in an aprotic solvent, the formula: [In the formula, t represents an integer from 0 to 50] A compound is synthesized, and 2, 2,
It is also possible to charge 3,3-tetrafluorooxetane to synthesize a compound similar to that obtained when the above-mentioned acyl fluoride is used alone.

On the contrary, 2,2,3,3
-For example, by introducing hexafluoropropylene oxide into a ring-opening polymerized system of tetrafluorooxetane. [In the formula, A is the same as formula (1), x is an integer from 2 to 200,
y represents an integer from 0 to 50. ] Compounds can also be synthesized.

As can be understood from the above explanation, theoretically, 2,2,3,3-tetrafluorooxetane and an epoxy compound capable of ring-opening polymerization using the same initiator system, such as hexafluoropropylene oxide, can be alternately used. Alternatively, a bifunctional acyl fluoride such as oxalic acid fluoride (FOC/COF) can be combined with an alkali metal fluoride at the same time as 2,2,3,3 -When used as a heavy initiator for tetrafluorooxetane, FOCCF ₂ CH ₂ (OCF ₂ CF ₂ CH ₂ )zOCF ₂ CF ₂ O
(CH ₂ CF ₂ CF ₂ O)wCH ₂ CF ₂ COF (3) [In the formula, z and w each represent an integer from 0 to 200] A bifunctional polymer whose terminals are each an acyl fluoride. is obtained.

Typically, on interaction with an alkali metal fluoride in an aprotic solvent, ~COF+MF~ _CF2O ^- M ⁺ (4) where M is an alkyl metal species. ] All acyl fluoride compounds that form an equilibrium amount of fluoroalkoxy anions as shown in formula (4) can be used in the presence of an alkali metal fluoride.
It can be said that it serves as a ring-opening polymerization initiator for 2,2,3,3-tetrafluorooxetane, and can form the terminal end of the ring-opening polymer in the form of an alkoxy group of ~CF ₂ O-.

Antimony pentafluoride (SbF ₅ ) is preferably used as the Lewis acidic initiator.

The ring-opening reaction of 2,2,3,3-tetrafluorooxesotane is usually carried out in the liquid phase, and the reaction solvent, other than the Lewis acid initiator, is an aprotic solvent such as diglyme, triglyme or tetraglyme. Polyethylene glycol dimethyl ethers are preferably used. When acetonitrile or CH ₃ OCH ₂ CH ₂ OCH ₃ (glyme) is used as a solvent, the reaction is slow or does not occur at all, but by using a small amount of a macrocyclic polyether compound such as 18-crown ether-6, Allows for smooth reaction. Acetonitrile and glyme have a low boiling point, so they are advantageous in that they can be easily distilled and separated from the target product at the end of the reaction.

In the case of a Lewis acid initiator, a dimer or trimer of hexafluoropropylene can be used as a solvent, although no particular solvent is required.

Although the reaction temperature may vary depending on the type of initiator and solvent, a temperature of -80 to 100°C is usually used, preferably a reaction temperature of -30 to 50°C.

The reaction product can be recovered by conventional methods. For example, solid products can be washed with water to remove solvent and initiator residues and then filtered, and volatile products can be recovered by rectification.

As mentioned above, the reaction product is A(CH ₂ CF ₂ -
It has the structure CF ₂ O) nCH ₂ CF ₂ COF, and the acyl fluoride at the end has high reaction activity as is well known, and is chemically valuable in itself. Something active is required.
For example, the above-mentioned acyl fluoride compound can be converted into a compound of the formula: X( _{CH 2 CF 2} CF ₂ O) nCH ₂ CF ₃ It can be converted to the compound shown as: Polyethers whose terminal ends have been chemically inert can meet the above-mentioned requirements.

During fluorination with fluorine gas in the presence of ultraviolet light, the terminal becomes -OCH ₂ CF ₂ COF or -OCH ₂ -
When using a polyether () which is CF ₂ COOH, at the stage where most of the hydrogen is replaced with fluorine, the terminal becomes -OCF ₂ CF ₂ COF -
There is a product that is OCF ₂ CF ₃ . When the introduction of fluorine is stopped, the inside of the reaction system is replaced with nitrogen gas, and the ultraviolet irradiation is continued, all of the -OCF ₂ -
The CF ₂ COF end is converted to -OCF ₂ CF ₃ . Therefore, in the fluorination reaction in the presence of light, when trying to obtain a chemically stable terminal product, it is necessary to use a terminal-stabilized polyether without using a terminal-stabilized polyether () in advance. () can be obtained.

Additionally, fully fluorinated polyether is
It is obtained by carrying out a thorough fluorination reaction, but if the fluorination reaction is stopped before then, the product naturally contains completely fluorinated polyether and some hydrogen. It becomes a mixture of fluorine polyether.

It is difficult to separate and purify completely fluorinated polyether from such a mixture using conventional distillation methods. However, by using a polar solvent such as acetone, it is possible to easily separate the two. That is, when the above mixed product is mixed with a polar solvent, the completely fluorinated polyether is separated into a lower layer, and liquid-liquid separation can be easily performed.

The main chain of the new fluorine-containing polyether () of the present invention is extremely stable both thermally and chemically, and can be expected to be used in the same way as conventional perfluoropolyethers, and can be used in a variety of applications depending on its properties. It can be applied to For example, compounds with terminal acyl fluoride groups are used as intermediates for synthesizing fluorine-containing compounds, those converted to terminal carboxyl groups are used as fluorine-containing surfactants, etc., and terminal-stabilized polyethers are used as heat-resistant As a chemical-resistant oil, it can be used as a solvent, heat medium, lubricating oil, vacuum pump oil, various modifiers, etc.

In particular, when fully fluorinated polyether is used as a vacuum pump oil during plasma etching of silicon with tetrafluoromethane, its viscosity remains unchanged even after continuous use for one month, and stability is required. It can be a suitable material for this field.

Next, the present invention will be specifically explained with reference to Reference Examples and Examples.

Reference example 1 In a 200ml glass tube with a rotor flow valve,
50ml well-dried diglyme, cesium fluoride
0.15 g and 50 g of 2,2,3,3-tetrafluoroxetane were charged and kept under stirring at room temperature for 15 hours. The reaction mixture was poured into 1000 ml of water, and the precipitated solid material was separated with a glass filter, washed with methanol, and vacuum dried to obtain 45 g of white powder. Melting point: 78℃. Decomposition temperature: 316℃.

Elemental analysis: C H F Measured value (%) 27.6 1.51 58.0 Calculated value (%) 27.7 1.55 58.4 NMR: δ (ppm) = 4.62 (CH ₂ ) (internal standard:
TMS).

δ (ppm) = -7.2 (-C F ₂ O-), -41.1 (CH ₂ C F ₂ ) (external standard: TFA) (the lower magnetic field side than the standard is +).

The IR chart of this compound is shown in FIG.

From these results, it was confirmed that the product was a polymer having a -CH ₂ CF ₂ CF ₂ O- skeleton. Average molecular weight is 1.5× from GPC
It turned out to be 10 ⁴ .

Reference Example 2 A 1 liter flask connected to a dry ice condenser and a dropping funnel was sufficiently replaced with dry nitrogen gas, and 200 ml of dry diglyme and cesium fluoride were added.
Add 4.2g of perfluoro 2-propoxypropionic acid fluoride 166 while stirring in an ice bath.
g and kept for 30 minutes. 650 g of 2,2,3,3-tetrafluorooxetane was added dropwise over 5 hours. After the addition was completed, the ice bath was replaced with a 25°C water bath and kept for 15 hours. The homogeneous liquid was distilled under reduced pressure to obtain 725 g of liquid (60-200°C/1 mmHg).

This is the result of GC/MS, NMR and IR analysis. (a is an integer from 1 to 10) It turned out to be a mixture of the following.

Reference Example 3 A 300 ml flask connected to a dry ice condenser and a dropping funnel was sufficiently purged with dry nitrogen gas, 50 ml of dry diglyme and 0.2 g of cesium fluoride were charged, and the flask was heated in an ice bath with stirring.
26.0 g of 3-trifluoropropionic acid fluoride was added and kept for 30 minutes. 130 g of 2,2,3,3-tetrafluorooxetane was added dropwise over 3 hours.
After the addition was completed, the ice bath was replaced with a water bath and kept for 12 hours. 30g of methanol was added dropwise and kept for 30 minutes.
The reaction mixture was poured into 2 liters of water, thoroughly stirred, and the lower layer was separated using a separating funnel (yield: 150 g).

As a result of analysis, this was found to be a mixture of F(CH ₂ CF ₂ CF ₂ O)bCH ₂ CF ₂ COOCH ₃ (b is an integer from 0 to 9).

Reference example 4 Hexafluoropropylene dimer [(CF ₃ ) ₂ CFCF=
Mixture of 30 parts by weight of CFCF ₃ and 70 parts by weight of (CF ₃ ) ₂ C=CFCF ₂ CF ₃ ] 150 g and antimony pentafluoride
0.3g of 2,2,3,3-tetrafluorooxetane was slowly added dropwise while stirring.
It was kept at -50 to 0°C for 5 hours. The low boiling fraction was removed under reduced pressure to obtain 50 g of a waxy product. melting point 52
℃.

As a result of analysis, this was found to have the structure -CH ₂ CF ₂ CF ₂ O-.

Reference example 5 100 ml of well-dried diglyme and 1.0 g of potassium fluoride were placed in a 500 ml glass flask.
While stirring, 130 g of 2,2,3,3-tetrafluorooxetane was slowly added dropwise in an ice bath, and the mixture was kept for 15 hours. The same post-treatment as in Reference Example 1 was carried out to obtain 120 g of polymer.

As a result of analysis, this was found to have the structure -CH ₂ CF ₂ CF ₂ O-. Average molecular weight is GPC
Therefore, it was 1.0×10 ⁴ .

Reference example 6 50ml of dry diglyme and 15g of potassium iodide
32.5 g of 2,2,3,3-tetrafluorooxetane was slowly added dropwise while stirring, and the mixture was kept for 24 hours. 10 g of methanol was added dropwise, kept for 30 minutes, and washed thoroughly with water to obtain 30 g of an oily product.

As a result of analysis, this was found to be a mixture of I(CH ₂ CF ₂ CF ₂ O)cCH ₂ CF ₂ COOCH ₃ (c is an integer from 0 to 5).

Reference Example 7 A 100 ml flask connected to a dry ice condenser and a dropping funnel was charged with 30 ml of dry diglyme and 1.2 g of cesium fluoride, and stirred in a bath cooled to -30°C. Next, 10 g of perfluoropropionic acid fluoride was charged in a gaseous state, and after the completion of the charging, the bath temperature was raised to 0°C and 2,2,3,3-tetrafluorooxetane was added.
50g was added dropwise over 20 hours. After finishing dropping,
The bath temperature was gradually raised to 20° C., stirring was continued for another 5 hours, and then poured into 50 g of methanol, stirred, and further washed with a large amount of water to obtain 47 g of an oily product.

As a result of analysis by NMR, IR and GC-MS, the product is CF ₃ CF ₂ CF ₂ O (CH ₂ CF ₂ CF ₂ O)
It was found to be a mixture of dCH ₂ CF ₂ COOCH ₃ (d is an integer from 1 to 8).

Reference Example 8 10 ml of dry diglyme was added to a 30 ml flask connected to a dry ice condenser and a dropping funnel.
1.2 g of cesium fluoride and 2.0 g of 2,2,3-trifluoropropionic acid fluoride were added, and the mixture was stirred in a water bath for 1 hour. Then, under stirring 2, 2,
10.0 g of 3,3-tetrafluorooxetane was added dropwise over 3 hours. After the dropwise addition was completed, stirring was continued for an additional 15 hours. The water bath was then replaced with an ice bath,
After hexafluoropropylene oxide was blown into the system at a flow rate of 10 ml/min for 2 hours, the reaction was continued for an additional 2 hours. The reaction solution was treated with methanol and washed with water to obtain 18.0 g of an oily substance.

Analysis shows that the product is (e is an integer of 2 to 9, f is an integer of 0 to 3).

Reference Example 9 Using 10 g of perfluoroacetone instead of perfluoropropylene acid fluoride, 2,2,
Repeat the same procedure as in Reference Example 8 except for reacting with 50 g of 3,3-tetrafluorooxetane.
53 g of oily product were obtained.

As a result of analysis, the product is (CF ₃ ) ₂ CFO (CH ₂ CF ₂ CF ₂ O)
It was found to be a mixture of gCH ₂ CF ₂ COOCH ₃ (g is an integer from 1 to 8).

Reference example 10 Obtained in reference example 2 50.0g of hexafluoropropylene dimer 10
ml and 1.2 g of antimony pentafluoride, and heated at 50°C for 1 hour. During the reaction, infrared analysis of the gas phase detected a large amount of carbon monoxide. IR analysis of the reaction solution confirmed that the absorption at 1890 cm ^-1 , which is the specific absorption of -COF, had completely disappeared. After washing with hydrochloric acid, alkali and water, it was dried and distilled under reduced pressure to obtain 43.8 g of a liquid. Boiling point 100-200℃/1mmHg.

This is the result of the analysis, (a is an integer from 1 to 10).

Example 1 In a steel reactor with a capacity of 100 ml, 3.00 g of a white powder of polyfluorofluorinated polyether having the formula: F(CH ₂ CF ₂ CF ₂ O)nCH ₂ CF ₂ COOH (average of n = 25) was put into a steel reactor with a capacity of 100 ml. was heated in fluorine oil while stirring, gradually increasing the temperature from 140℃ to 200℃, and then introducing a fluorine/nitrogen (20/80) mixed gas for 3 hours.
The flow rate was 100ml/min. After cooling while purging with nitrogen, 2.05 g of a viscous liquid reaction product was taken out. The reaction product contains repeating units shown as (CH ₂ CF ₂ CF ₂ O)p-(CHFCF ₂ CF ₂ O)q (p:q=7:3) from the results of IR, NMR and elemental analysis. It turned out to be a mixture of compounds.

Example 2 5.20 g of fluorine-containing polyether represented by the formula: F(CH ₂ CF ₂ CF ₂ O)nCH ₂ CF ₂ COOH (average of n = 25) was placed in a steel reactor with a capacity of 100 ml.
Gradually raise the temperature from 140℃ to 200℃ while stirring, 4.5
Fluorine/nitrogen (20/80) mixture gas over time
The flow rate was 100ml/min. 2.48 g of liquid reaction product was taken out while purging with nitrogen. The reaction product is
From the results of IR, NMR, and elemental analysis, it is a mixture of compounds containing repeating units shown as (CF ₂ CF ₂ CF ₂ O)q-(CHFCF ₂ CF ₂ O)r (q:r=5:1) I found out.

Example 3 In a photoreactor using tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA) as a light transmitting material, 2,2,3,3
- 4.90 g of polymerization reaction product of tetrafluorooxetane [F(CH ₂ CF ₂ CF ₂ O)nCH ₂ CF ₂ COOH (average of n = 24)] was added and heated to 100°C in an oil bath in a nitrogen stream. .

Next, while stirring with a magnetic stirrer,
Fluorine/nitrogen mixed gas (mixture ratio
20/80), ultraviolet irradiation was performed from the top of the reactor using a high-pressure mercury lamp (Toshiba H400PL, 312.5-577 nm) (distance 10 cm).

The flow of the fluorine/nitrogen mixed gas was stopped after 15 hours, and nitrogen was continued to flow at a rate of 50 ml/min for another 12 hours while continuing to irradiate with light. After the reaction was completed, the light irradiation was stopped and the mixture was cooled to obtain 5.90 g of an oily substance. Pour point:-
55℃.

Elemental analysis C H F Measured value (%) 21.7 0.01 68.7 Calculated value (%) 21.5 0 69.1 In addition, changes over time in infrared spectroscopic analysis are shown in Figures 2-4. Figure 2 is a chart 2 hours after the start of the photofluorination reaction, Figure 3 is a chart at the end of the reaction, and Figure 4 is a chart at the end of the reaction.
The figure shows a chart after the decarbonylation reaction.

From the above analysis, it was determined that the oily substance was a mixed composition of F(CF ₂ CF ₂ CF ₂ O)nCF ₂ CF ₃ (average of n = 23. The number of n was determined from the integral value of NMR). I understand.

Example 4 In the same reactor as Example 3, (Average of n = 7) 6.9 g of the mixture represented by the formula (average of n = 7) was added to the reactor while stirring with a magnetic stirrer and flowing a fluorine/nitrogen mixed gas (mixing ratio 20/80) at a flow rate of 50 ml/min. Low-pressure mercury lamp (manufactured by Ushio Electric) from the top
Ultraviolet rays were irradiated using UL2-IQ, 10W, 184.9-546.1nm) as a light source (distance 5cm).

After 19 hours, the reaction was stopped, and after replacing with nitrogen, 7.0 g of a reaction product was obtained.

Analysis results (Average of m+n=7, m:n=1:4) It turned out to be a compound.

Example 5 In the same reactor as Example 3, the formula (Average of n = 7) Add 2.6 g of the mixed composition represented by, and while stirring,
While flowing a fluorine/nitrogen mixed gas (mixing ratio 20/80) at a flow rate of 50 ml/min, ultraviolet rays were irradiated from the top of the reactor using a high-pressure mercury lamp as a light source. After 11 hours, the reaction was stopped, and after replacing with nitrogen, 3.3 g of a liquid product was obtained.

Analysis results It was found that (average of n = 7).

Example 6 The formula: F(CH ₂ CF ₂ CF ₂ O) ₂ was placed in a photoreactor (inner volume: 100 ml) with a SUS condenser connected and a chlorotrifluoroethylene polymer (PCTFE) film attached to the 30φ upper window. ―
After charging 10.0 g of a liquid represented by CH ₂ CF ₂ COF and cooling it in a water bath, while flowing a fluorine/nitrogen mixed gas (20/80) at a flow rate of 50 ml/min under stirring in a nitrogen stream, (Light source: high pressure mercury lamp). The condenser was cooled with dry ice.
After flowing for 15 hours, the atmosphere was replaced with nitrogen, the product was fractionated, and F
9.8 g of (CF ₂ CF ₂ CF ₂ O) ₂ CF ₂ CF ₃ was obtained.

Example 7 Using ethylene/tetrafluoroethylene copolymer (ETFE) instead of PCTFE as a window film
A similar experiment was carried out using the same apparatus as in Example 5 using a film manufactured by F.
_{( CF2CF2CF2O} ) _2CF2CF3 was obtained with _a yield _of 80% _.

Example 8 A similar experiment was carried out using the same equipment as in Example 6, using a polyvinylidene fluoride film instead of PCTFE as a window film.
( _{CF2CF2CF2O ) CF2CF3} was obtained with _a yield _of 28%.

Example 9 A polymeric composition of 2,2,3,3-tetrafluorooxetane [F(CH ₂ CF ₂ CF ₂ O)
Add nCH ₂ CF ₂ COF, average of n = 22] 130.0g,
The polymer was liquefied by circulating a heating medium at 80°C through the jacket in a nitrogen stream.

Next, while stirring with a magnetic stirrer,
Fluorine/nitrogen mixed gas (mixing ratio 1/1) was passed from the side of the reactor through a single crystal sapphire window plate at a flow rate of 200 ml/min using a high-pressure mercury lamp (Toshiba H100PL, 312.5-577 nm). , irradiated with ultraviolet light (distance between lamp and window plate 5 cm). Further, during the reaction, the temperature of the heating medium was controlled so that the internal temperature was 100 to 120°C.

After 50 hours, stop the fluorine gas and turn on only nitrogen at 100 hrs.
It was passed under light irradiation for an additional 24 hours at a flow rate of ml/min.

After completion, 158 g of oily product were obtained at room temperature.

As a result of the analysis, it was confirmed that the product was F(CF ₂ CF ₂ CF ₂ O)nCF ₂ CF ₃ (average of n = 22).

Example 10 1.5 kg of polymer composition F (CH ₂ CF ₂ CF ₂ O) n CH ₂ CF ₂ COF (average of n = 25) and heated to 100°C in an oil bath in a nitrogen stream.

Next, while stirring with a magnetic stirrer,
Fluorine 1l/min and nitrogen 1l/min were thoroughly mixed and introduced into the system, and a high-pressure mercury lamp (Toshiba
Ultraviolet rays were irradiated using H400PL). During the reaction, the temperature of the oil bath was controlled to prevent the temperature inside the reactor from rising to 120°C. After 100 hours, the fluorine was stopped, and only nitrogen was passed through at a flow rate of 2 l/min for 50 hours, and then cooled to room temperature. After the reaction was completed, 1.8 kg of an oily composition of F(CF ₂ CF ₂ CF ₂ O)nCF ₂ CF ₃ (average n=25) was obtained. This was rectified under reduced pressure of 0.05 Torr to obtain 1.2 kg of a fraction at 180-220°C.
The kinematic viscosity at 40°C was measured to be 65cst.

Example 11 After the oil rotary pump was directly connected and thoroughly cleaned with a solvent, the oil obtained in Example 10 was applied to it, and a test plasma generator using a mixed gas of Freon 14 and water and oxygen was operated. . No abnormality was observed in the motor current value even after 30 days of operation.

As a result of extracting the oil and examining it, the viscosity was 65 cst at 40°C, and no significant change was observed compared to the oil's 65 cst before injection. Furthermore, the IR and NMR analysis results of the oil after use showed no change compared to before use.

[Brief explanation of the drawing]

Figure 1 is an IR chart of the polymer obtained in Reference Example 1, Figures 2 and 3 are IR charts showing changes over time in infrared spectroscopy during fluorination in Example 3, and Figure 4 is an IR chart of the polymer obtained in Example 3. This is an IR chart after the decarbonylation reaction of the polymer obtained in Example 3.

Claims (1)

[Claims] 1 (a) A repeating unit represented by the formula: -(CH ₂ CF ₂ CF ₂ O) -, (b) a repeating unit represented by the formula: -(CHFCF ₂ CF ₂ O), and (c) A random compound containing a total of 2 to 200 repeating units represented by the formula: -(CF ₂ CF ₂ CF ₂ O) - and at least one repeating unit (b) and (c) in total. Fluorine polyether. 2. The random fluorine-containing polyether according to claim 1, which comprises only the repeating unit (c). 3 A fluorine-containing polyether consisting of 2 to 200 repeating units represented by the formula: -(CH ₂ CF ₂ CF ₂ O) - is fluorinated with fluorine to obtain the formula (a): -(CH ₂ CF ₂ CF ₂ O) -, (b) a repeating unit with the formula: -(CHFCF ₂ CF ₂ O) -, and (c) a repeating unit with the formula: -(CF ₂ CF ₂ CF ₂ O) - A method for producing a random fluorine-containing polyether, which comprises obtaining a compound containing 2 to 200 repeating units in total and at least one repeating unit (b) and (c) in total. 4 (a) A repeating unit with the formula: -(CH ₂ CF ₂ CF ₂ O) -, (b) A repeating unit with the formula: -(CHFCF ₂ CF ₂ O) -, and (c) A repeating unit with the formula: - (CF ₂ CF ₂ CF ₂ O) - consisting of a random fluorine-containing polyether containing 2 to 200 repeating units in total and at least one repeating unit (b) and (c) in total vacuum pump oil. 5. The vacuum pump oil according to claim 4, comprising a fluorine-containing polyether consisting only of the repeating unit (c).