JPS63191825A - Production of fluoropolyether - Google Patents

Abstract

PURPOSE:To make it possible to produce a fluoropolyether of a high degree of polymerization very easily under mild conditions, by polymerizing a fluoroalkylene oxide in the presence of an anionic polymerization catalyst and a fluoroketone compound. CONSTITUTION:A fluoropolyether is produced by polymerizing a fluoroalkylene oxide (e.g., tetrafluoroethylene oxide) in the presence of an anionic polymerization catalyst (e.g., potassium fluoride) and a fluoroketone compound (e.g., a compound of the formula). According to the above process, a polymer of a degree of polymerization of at least 7, further, at least 9 can be obtained. Further, the polymerization can be performed under very mild conditions,for example, those including -50-50 deg.C and 0.1-10atm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of polymerizing fluoroalkylene oxide to obtain a fluoropolyether with a high degree of polymerization.

[Prior art and problems to be solved by the invention] Fluoropolyether obtained by polymerizing fluoroalkylene oxide has excellent heat resistance and chemical resistance, and is also lubricating with mineral oil. Due to its excellent properties, it is used as a fluorine thread lubricant. Such fluorine thread lubricating oil is desired to have a high boiling point since it is sometimes used in a low-pressure atmosphere such as in a vacuum pump, and is preferably a fluoropolyether with a high degree of polymerization.

Therefore, methods for obtaining fluoropolyethers with a high degree of polymerization are being studied. For example, Journal of Fluorine Chemistry (Journal of Fluorine Chemistry)
n@Ch@mlstry) Volume 25 (1984), pages 241-253, describes that hexafluoropropylene oxide was polymerized using potassium fluoride as a catalyst. The composition of the obtained polymer is
Hexafluoropropylene oxide dimer 3%, 3
10 units of mer, 27% of tetramers, 30 units of pentamers, 9% of hexamers
It has been shown that As described above, according to the above method, only a hexamer polymer can be obtained at most, and a fluoropolyether with a very high degree of polymerization cannot be obtained.

In addition, the journal Otsumaro'mol, Ra Science Chemistry (J, Maaro'mol@cularS
cienco-chemistry) Volume A8 (197
4) pages 499 to 520, it is shown that the trimer of cesium alcoholade hexafluoropropylene oxide is polymerized from hexafluoropropylene oxide, but this method is also complicated and is expected to be difficult. There was a problem in that it was not possible to obtain a polymer with a high enough content.

[Means for solving the problem] [The inventor has
As a result of extensive research into the synthesis of fluoropolyethers with a high degree of polymerization, we have found that 7%
The inventors have discovered that the above object can be achieved by polymerizing AI oloalkylene oxide, and have completed the present invention.

That is, the present invention is a method for producing a fluoropolyether, which is characterized by polymerizing a fluoroalkylene oxide in the presence of an anionic polymerization catalyst and a fluoroketone compound.

As the fluoroalkylene oxide used in the present invention, known compounds can be employed without any restrictions.

Generally, the fluoroalkylene oxide preferably used in the present invention is a compound having 2 to 5 carbon atoms.

Specifically, tetrafluoroethylene oxide, hexafluoropropylene oxide, and 2.2.3.3-tetramero. Oxetane, No4-7 #Oroisobutylene oxide, etc.+7)/''-Fluoroalkylene oxide is preferably used.

As the anionic polymerization catalyst used in the present invention, any known catalyst used in general anionic polymerization can be used without any restriction. For example, alkali metal fluorides such as sodium fluoride, potassium fluoride, cesium fluoride, and rubidium fluoride; tetraalkyls such as tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, and tetrabutylammonium fluoride. Ammonium fluoride: Examples include alkali metal alkoxides such as sodium polyfluoroalkoxide, potassium polyfluoroalkoxide, and cesium polyfluoroalkoxide. Among these, the alkali metal alkoxide can be obtained by reacting a fluoroalkylka-AI-dylfluoride with an alkali metal heptadide or tetraalkylammonium fluoride gold. Therefore, instead of using the alkali metal alkoxide described above, a fluoroalkylcarbonyl fluoride and an alkali metal fluoride or a tetraalkylammonium fluoride can also be used together. The above-mentioned fluoroalkyl car-nyl fluoride includes dimer to hexamer of hexafluoropropylene oxide, hexafluoropropylene oxide,
Fluorodelopylcargenyl fluoride, perfluorologtyrylcal? Nyl fluoride, ω-hydrono-fluoro-a alkyl carbinyl fluoride, ω-chloroperfluoroalkyl carbinyl fluoride, ogideryl fluoride, par77L/oQmao = A/
y A/, t 54 do, perfluorosuccinyl fluoride, perfluoroglutaryl fluoride, perfluoroazibonyl fluoride, ogideryl fluoride with 2 to 6 hexafluoropropylene oxide
Compounds subjected to individual addition polymerization can be mentioned.

The amount of the anionic polymerization catalyst mentioned above can be used within a wide range, but considering the speed of the polymerization reaction and the degree of polymerization, it is 0.00% per mole of fluoroalkylene oxide.
0.01 to 0.2 mol, preferably 0.001 to 0.00 mol.
It is in the range of 1 mole.

Next, as the fluoroketone compound used in combination with the above-mentioned anionic polymerization catalyst, known compounds in which part or all of the hydrogen atoms of a ketone compound having one or more carnonyl groups are replaced with fluorine can be employed without any restriction. Among these various fluoroketone compounds, in the present invention, when a compound whose infrared absorption spectrum of the carbonyl group present in the fluoroketone compound appears at 17853 or less is used, particularly fluoroketone compounds with a high degree of polymerization are used. This is preferred because polyether can be obtained.

Fluoroketone compounds preferably used in the present invention are represented by the following general formulas (1) and (II).

R4+X -R2SeC+R, -XChiR4(1) [However,
R1 and R4 are the same or different alkyl groups or aryl groups, or groups in which some or all of the hydrogen atoms of these groups are substituted with fluorine atoms.
5 is the same or different fluoroalkylene group, X is an oxygen atom or a sulfur atom, m is O or 1, and n is an integer of 1 or more. (However, when and m are O at the same time, at least one of R and R is an alkyl group or an aryl group in which some or all of the hydrogen atoms are substituted with fluorine atoms.) In formulas (I) and (II), the number of carbon atoms in the alkyl groups represented by R1 and R4 is not particularly limited, but is preferably in the range of 1 to 1o from the viewpoint of easy availability. Further, as the aryl group represented by R1 and R4, a phenyl group is the most easily available. The general formulas (1) and (I
In [), the number of carbon atoms of the fluoroalkylene group represented by R2, R3 and R5 is not particularly limited, but for the same reason as above, the number of carbon atoms may be in the range of 2 to 5. preferable.

In the present invention, the following are specific examples of fluoroketone compounds that can be particularly suitably employed. For example, CH,0CF2CF2CCF2CF20CH3°C
2H50CF2CF2CCF2CF2QC2 pull.

Just C, Hl, 0CF2CF, CCF2CF2QC2B5゜HCF2CF, CH20CF2CF2CCF2CF20
CH2CF2CF2H.

H(CF20F2)2CH20CF2CF2CCF2C
F20CH2(CF2CF2)2H.

can.

In the present invention, from the viewpoint of the degree of polymerization of the obtained fluoropolyether, the fluoroketone compound represented by the general formula (1) is preferred, and in particular, a compound in which L and m are 1 and X is an oxygen atom is preferred. is preferred.

The amount of the fluoroketone compound used is not particularly limited, but in order to increase the degree of polymerization of the fluoro 4-riether,
0.1 in weight ratio to fluoroalkylene oxide
It is preferable to select from the range of 0.5 to 20, more preferably 0.5 to 0.

The polymerization reaction of fluoroalkylene oxide in the present invention is preferably carried out in an aprotic organic solvent. As the non-7'eg) organic solvent, any known solvent used in the polymerization of fluoroalkylene oxide can be used without any restriction.

For example, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, acetone, acetonitrile, propionitrile, adiponitrile, tetrahydro-7rane, dioxane, benzonitrile, nitroethane,
Dimethyl sulfoxide, tetramethylene sulfo 7, etc. can be used. These aprotic organic solvents are
0.0 in weight ratio to fluoroalkylene oxide
It is preferable to use it in the range of 5 to 2.

The polymerization reaction of fluoroalkylene oxide is carried out at -50°C to 50°C, preferably -35°C while stirring the reaction medium.
It is preferable to carry out the reaction while maintaining the reaction temperature at ~10°C and the pressure of the fluoroalkylene oxide in the range of 0.11N10 atm, preferably 0.5-3 atm.

In order to reduce the viscosity of the fluoroalkylene oxide polymer produced in the reaction medium, hexafluoropropylene, /J? -Fluorinated organic compounds such as fluorocitadiene, perfluorobutane, perfluorohexane, and trichlorotrifluoroethane can also be used.

The high polymer of fluoroalkylene oxide obtained by the method of the present invention is separated from the reaction medium by conventional operations and then fractionated by distillation.

The fluoroalkylene oxide polymer obtained in this way has its terminal acid fluoride group contacted with water to form a carboxylic acid group, and then reacted with fluorine gas to replace the cyclocarpic acid group with fluorine. . Alternatively, it is also possible to synthesize a higher molecular weight fluoropolyether by decomposing the acid fluoride group in the presence of ultraviolet light and utilizing the coupling between carbon radicals generated at the time.

In addition, by converting the acid fluoride group of a fluoroalkylene oxide polymer into an Is/N acid, and then thermally decomposing it in ethylene glycol and sodium carbonate, a fluoroether compound in which the acid fluoride group was replaced with hydrogen was produced. Can be synthesized. In addition, diester groups are produced by the reaction of acid fluoride groups with alcohols, nysamide groups are produced by the reaction with amines, nitrile groups are produced by the reaction with phosphorus pentoxide, and vinyl ether groups are produced by thermal decomposition in the presence of potassium carbonate. It is possible to synthesize high polymer derivatives of fluoroalkylene oxides having functional groups of .

〔effect〕

As understood from the above explanation, by polymerizing fluoroalkylene oxide in the presence of an anionic polymerization catalyst and a fluoroketone compound, the degree of polymerization can be increased to 7.
As described above, 9 or more fluoropolyethers can be obtained. Moreover, the method of the present invention allows the polymerization reaction to be carried out under extremely mild conditions, for example, at a temperature of 150 to 50°C and a pressure of 0.
．． Another feature is that it can be carried out under conditions of 1 to 10 atm.

Therefore, the method of the present invention is a method for very easily obtaining fluoropolyethers with a high degree of polymerization, which cannot be obtained by conventional methods, and has great industrial value.

〔Example〕

The present invention will be explained in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 1.5 dimethoxyperfluoro-3-pentanone (cal/nil IR/absorption spectrum 1775 (!!11-'
), 10 parts by weight of tetraethylene glycol dimethyl ether, and 0.5 parts by weight of potassium fluoride were placed in a stainless steel autoclave, and while stirring at a temperature of 0°C, 20 parts by weight of hexafluoropropylene oxide was added to 1.5 atm. It was introduced under pressure for 8 hours. After the reaction, a layer consisting of 1,5-dimethoxyperfluoro-3-pentanone and tetraethylene glycol dimethyl ether and a layer of fluoropolyether, which is a polymer of hexafluoropropylene oxide, were separated. The amount of fluoropolyether obtained was 19 parts by weight. When this polymer was analyzed by gas chromatography, it was found that there was almost no dimer or trimer of hexafluoropropylene oxide.

Therefore, we decided to distill this polymer, take a portion of the fraction, hydrolyze the acid fluoride groups with an excess aqueous sodium hydroxide solution, and then back-titrate the excess sodium dispersion with sulfuric acid. Then, the average degree of polymerization of the fluoropolyether was calculated. The results are shown in Table 1. Incidentally, when these fractions were analyzed by F-nuclear magnetic resonance spectroscopy and H-nuclear magnetic resonance spectroscopy, it was found that they consisted only of fluoro-lyether.

Table 1 Comparative Example 1 10 parts by weight of tetraethylene glycol dimethyl ether/L and 0.5 parts by weight of potassium fluoride were placed in a stainless steel autoclave, and while stirring at a temperature of 0°C, 20 parts by weight of hexafluoropropylene oxide was added. 1.5
The mixture was introduced at a pressure of ATM over a period of 8 hours. The average degree of polymerization of the obtained fluoropolyethyl was determined to be 2.9 by the same operation as in Example 1. Analysis by gas chromatography revealed that hexafluoropropylene oxide dimer was 32%, trimer 57%, and tetramer 1 (1
, 1% pentamer. In this comparative example, due to the presence of 1,5-dimethoxyperfluoro-3-pentanone,
It is clear that a highly polymerized product can be obtained.

Example 2 1.5-jethoxyperfluoro-3-pentanone (IR absorption spectrum of force/l/♂yl 177551) 60
Parts by weight, triethylene glycol dimethyl ether 10
Parts by weight and 1 part by weight of potassium fluoride were placed in a stainless steel autoclave and heated to -10°C at 8! While stirring under
1.40 parts by weight of hexafluoropropylene oxide.
The mixture was introduced at a pressure of 5 atm over a period of 8 hours. After the reaction, 38 parts by weight of fluoropolyether was obtained. The average degree of polymerization of this polymer was measured in the same manner as in Example 1 and was 10.
．． It was 2. Gas chromatographic analysis revealed that 2-4 is a low polymer of cyhexafluorozolopylene oxide.
There was almost no mass.

Example 3 1,5-dimethoxyperfluoro-3-pentanone 60
10 parts by weight of tetraethylene glycol dimethyl ether containing 1 mmol/11 parts by weight of cesium alkoxide dimer of hexafluoropropylene oxide were placed in a stainless steel autoclave, and 40 parts by weight of hexafluoropropylene oxide was added to 1 mmol/11 parts by weight at a temperature of -10°C. ．．
The reaction was carried out under 5 atm OEE power for 16 hours. After the reaction was completed, 37 parts by weight of fluoropolyether was recovered. The average degree of polymerization measured by the same method as in Example 1 was 12.4.

Comparative Example 2 1,5-dimethoxy/Chu7/ from the reaction medium of Example 3
L/Oc! A hexafluoropropylene oxide reaction was carried out in the same manner as in Example 3 except for -3-pentanone. After the reaction was completed, 40 parts by weight of hexafluorozorobile/oxide was recovered. The average degree of polymerization measured by the same method as in Example 1 was 6.0.

Example 4 1,5-dimethoxyperfluoro-3-pe/thanone 60
Part by weight, tetraethylene glycol dimethyl ether/L
/10 parts by weight of cesium fluoride, 0.5 parts by weight of cesium fluoride, and 5 parts by weight of malonyl fluoride were placed in a stainless steel autoclave, and 100 parts by weight of hexafluoropropylene oxide was added over 16 hours at a temperature of -10°C. a
The mixture was introduced and reacted under a pressure of tm. As a result, 7 parts by weight of dimers to tetramers of hexafluoropropylene oxide and 96 parts by weight of a dibasic acid obtained by addition polymerization of hexafluoropropylene oxide from both ends of malonyl 7/I/olide.
Parts by weight were obtained. The average degree of polymerization of hexafluoropropylene oxide measured by the same method as in Example 1 was 15.1.

Example 5 1,5-dimethoxy-perfluoro-3-pentanone 2
01 amount9. 2.2.3.3 1 part by weight of Δ-fluorobutyryl fluoride, 0.5 parts by weight of tetramethylammonium fluoride, and 5 parts by weight of diethylene glycol dimethyl ether were placed in a stainless steel autoclave and heated at -74°C. - Add 15 parts by weight of tetrafluorooxetane and gradually raise the temperature to 3at.
The reaction was carried out for 24 hours at a pressure of less than m. After the reaction is completed, 2.
13 parts by weight of an addition polymer of 2.3.3-tetrafluorooxetane was recovered. The average degree of polymerization of 2,2,3,3-tetrafluorooxetane measured by the same method as in Example 1 was 12.5.

Examples 6 to 8 30 parts by weight of various fluoroketones shown in Table 2, 10 parts by weight of tetraethylene glycol dimethyl ether, and 1 part by weight of potassium fluoride were placed in a stainless steel autoclave, and the tetrafluoroketones were heated at -15°C. 20 parts by weight of ethylene oxide was added to 4 parts by weight under a pressure of 1 to 3 atm.
The reaction was allowed to proceed for 8 hours.

As a result, about 18 parts by weight of each fluoropolyether, which is a polymer of tetrafluoroethylene oxide, was obtained. The average degree of polymerization of each fluoropolyether measured by the same method as in Example 1 is shown in Table 2.

Claims (1)

[Claims] (1) A method for producing a fluoropolyether, which comprises polymerizing a fluoroalkylene oxide in the presence of an anionic polymerization catalyst and a fluoroketone compound.