JPS60132621A - Gas separation membrane - Google Patents

Abstract

PURPOSE:To obtain a gas separation membrane high in the transmission coefficient and separation factor of oxygen, by using polysiloxane having a fluorine- containing group in the main chain or its crosslinked polymer. CONSTITUTION:Polysiloxane obtained by the dehydro-condensation reaction of a compound represented by formula is used as a stock material. Similar polysiloxane may be obtained by other synthetic methods. This polysiloxane is dissolved in a solvent such as toluene or xylene and, if crosslinking is performed later, a crosslinking reaction catalyst is added to said solvent and a membrane is formed so as to adjust the thickness thereof to 1-50mum according to a usual membrane preparing method. In order to enhance the strength of the membrane, the formed membrane is crosslinked before use. Crosslinking reaction is performed at a room temp. 150 deg.C for 30min-20hr. The crosslinking reaction catalyst is used so as to be added to polysiloxane in an amount of 1-10wt%.

Description

[Detailed description of the invention] The present invention relates to gas separation membranes.

Conventionally, gas separation membranes were used to concentrate oxygen from rough air, and then burn it.
It is used for medical purposes, fermentation, etc.

As this gas separation membrane, for example, polysiloxane containing a fluoroalkyl group in the side chain is known (Japanese Unexamined Patent Publication No.
6-6121). This gas separation membrane was created for the purpose of improving the heat resistance and other properties of conventional gas separation membranes, but its oxygen permeability coefficient and separation coefficient are small, making it impractical.

An object of the present invention is to provide a gas separation membrane with a large oxygen permeability coefficient and separation coefficient.

The gist of the present invention resides in a gas separation membrane made of a polysiloxane containing a fluoroalkylene group or a fluorooxyalkylene group in its main chain or a crosslinked product thereof.

The above fluoroalkylene group usually has the formula 2Cl1F211
- (In the formula, 11 represents an integer of 1-15.) A fluorooxyalkylene group usually represents the formula: ) is a group represented by

Just 1 flll of gas according to the present invention! Porgysan, which is a raw material for the membrane, can be prepared by a known method (see Japanese Patent Application Publication No. 58-92594) and is usually prepared by the following formula: (wherein R1 and R2 have different carbon numbers l to
By fully polymerizing a compound represented by 15 alkyl groups or fluoroalkyl or fluorooxy having 2 to 15 carbon atoms, a compound represented by formula: (wherein R1 is the same as above) can be synthesized by formula (a). What is the reaction formula for the compound represented by the formula: (wherein R1, R2 and Rf are the same as above)? i-1, then 1C1 contained in this compound is converted to 10H group to obtain a compound represented by the formula: (in the formula, R1, R2 is the same as %3), and this The compound represented by formula (d) can be obtained by polymerizing in the same manner as the compound represented by formula (a).

2) The reaction rate when reacting the compound represented by (a) with the compound represented by formula (b) is as shown in formula (a) in order to increase the separation coefficient between oxygen and nitrogen of the gas separation membrane. Preferably, the amount of the compound is 50 mol% or more.

In addition to the compound represented by the above formula (b), formula: 3 (wherein R3 is -H, (CH2)y CH=CH2 (where r is an integer between θ and 3), -(CH2)s00ccH
=CH2 (However, S is an integer from 1 to 5.), -(CH
2) szo゛00CC=CH2 (However, S is the same as in nrs.), -
The compound represented by QC8R2g +1 (s Id, if3 same 1:, .), -0OCs R2s ++ (however, S is the same as above) is referred to as the compound represented by formula (b). It can also be incorporated into polysiloxane in a similar manner.

Since the compound represented by formula (e) has the functional &, it can be used to completely crosslink the polysiloxane, thereby increasing the mechanical strength of the gas separation membrane. Formula (C)
The compound represented by formula (a) is usually used in an amount of 15 mol% or less relative to the compound represented by formula (a).

Polymerization of compounds represented by formula (a) having less than 10 H groups is usually carried out using a dehydration condensation reaction.

This dehydration condensation reaction can be carried out in the presence of a catalyst without a solvent, or can be carried out using benzene, toluene, or the like as a solvent. When carrying out the reaction without a solvent, it is convenient to remove the produced water under reduced pressure, and when using a solvent, it is convenient to carry out the reaction while removing the produced water by azeotroping with the solvent.

Examples of the catalyst include para-toluenesulfonic acid, trifluoroacetic acid/tetramethylguanidine salt, and 2-ethylhexanoic acid/tetramethylguanidine salt.

The reaction temperature is usually 50 to 150°C.

A compound having an 10H group at the end and a compound having -C1 at the end are usually dehydrochlorinated and reacted.

Is this dehydrochlorination reaction usually absent? It is carried out using a dioxane or an ether such as dioxane as a solvent.

When carrying out the reaction without a solvent, it is convenient to carry out the reaction while removing the generated hydrogen chloride by passing an inert gas such as nitrogen into the reaction system, or by reducing the pressure of the reaction mixture as in the dehydration reaction above. It is. The reaction temperature is usually lo
~ioo'c.

The reaction for converting -C1 to 10H group is usually carried out using saturated water of a weak alkali such as NaHC0 or KHCO3.
This is carried out by adding a compound having -Cg to the bath solution.

Usually, the reaction temperature is 10~80''c1 reaction time is several minutes~5
It's time.

The polysiloxane prepared by the above preparation method is usually dissolved in a solvent such as Toluev, xylene, hexafluorometa-xylene, trichlorotrifluoroethane, tetrachlorodifluoroethane, hexachlorohexafluorobutane, etc., and the polysiloxane is later crosslinked. In some cases, crosslinking reaction catalysts such as peroxides and organic metal salts are added, and thin films are usually prepared by methods such as bar coater method, spin coater method, Langmuir method, dip method, etc.
A film can be formed on a smooth plate such as a polytetrafluoroethylene or a porous support such as a polytetrafluoroethylene porous material so that the film thickness is usually 1 to 50 μm. Normally, polysiloxane that has been formed into a film on a smooth plate such as glass or metal is crosslinked to increase its strength, then peeled off from the plate and fixed on a suitable support. A film formed on a support may be used together with the support after crosslinking if the strength is to be increased.

The gas separation membrane according to the present invention means not only polysiloxane or a crosslinked membrane thereof as described above, but also a composite membrane formed by coating or laminating these membranes.

The above crosslinking reaction is usually carried out at room temperature to
The crosslinking reaction is carried out at a temperature of 0"C for 30 minutes to 20 hours. The crosslinking reaction catalyst such as peroxide or organic metal salt is usually used in a weight ratio of 1 to 10 to the polysiloxane. Preferred conditions for the reaction are exemplified by the functional properties of polysiloxanes.

l) The reaction between hydroxyl groups is carried out using a total catalyst such as zinc octylate or dibutyltin dilaurate at a reaction temperature of 50 to 150°C.

2) Hydrogen and vinyl groups are mixed at 50 to 150°C without a catalyst.

1 1 1 1 3) Methyl groups and vinyl groups are formed at room temperature to 150°C using a peroxide catalyst or radiation.

4) Hydroxyl groups and alkoxyl groups are prepared in the same manner as in 1) above.

(In the formula, R4 represents an alkyl group.) 5) Carphonic acid esters are mixed at room temperature to 150°
This is done by hydrolyzing with water at C.

In formula 1, R4 is the same as above. ) Next, we will show preparation examples in which polysiloxanes were prepared, and test examples and comparative examples of gas separation membranes prepared from the polysiloxanes obtained.

Preparation Examples 1 to 7 Sila 7-ol 10yVcl shown in Table 1: ] (Moz
CF3 C0OH Tetramethylguanidine 40
．． Add 01f gold and add 20 mm l with vigorous stirring.
The silanol was washed under reduced pressure at 80°C for 8 hours.Then, the product was diluted with ethyl ether and 50 ml
Add this solution to a saturated water bath of NaHCO3 at 10%
Polymerization was stopped by dropping the mixture into 0++14. The organic layer was separated from the water washed layer, and diethyl ether in the organic layer was distilled off using an evaporator. The resulting residue was washed with water and dried under reduced pressure to obtain a rubbery substance.

The yields of each preparation example were 83%, 98%, and 82%9.
They were 7%, 90%, 88% and 90%.

Next, IH and 1 of the polysiloxane obtained in Preparation Example 1
The results of nuclear magnetic resonance analysis (NMR) of 9p are shown. The solvent was acetone-d6, and (CH+1)43 was used as an internal standard in the case of 'HNMR, and CF3 C00Hft was used as an external standard in the case of 1''FNMR.

From the above NMR results and synthesis method, it can be seen that the polymer prepared in Preparation Example 1 has a structural unit represented by the formula: %Formula % (1).

Gas separation membrane samples were prepared by dissolving each of the polymers obtained in the above preparation examples in a 1:1 mixed solvent of toluene and meta-xylene hexafluoride to a concentration of 10% by weight, and stirring well. Of these, 1011Il was obtained by stretching polytetrafluoroethylene with a porosity of 60%,
It was prepared by coating on a porous body with pores having a minor axis of 0.1 to 1 μm and a major axis of 1-1θ using a spin coater rotating at 2000 revolutions per minute.

Preparation Examples 8 to 12 Nisilane, also shown in Table 1, was added dropwise to the silanol shown in Table 1 at 80° C. in a nitrogen stream with vigorous stirring (however, the total amount of silanol and silane was 101).

After the dropwise addition was completed, the reaction was carried out at 90 to 100°C in a nitrogen stream for 12 hours with vigorous stirring. Thereafter, after cooling to room temperature, the product was dissolved in diethyl ether, and the bath solution was thoroughly washed with a saturated hydrogen solution of Na HC03 and then with water, and the organic layer was separated, and diethyl ether was extracted from the organic layer. I was a tameo.

The same CF3COO used in Preparation Examples 1 to 7 was added to the above residue.
Add 0.01 g of H.tetramethylguanidine salt,
Polymerization was carried out for 8 hours at ioo°C under reduced pressure of 0 Ml Hg. Then, the product is 1.1.2-1-! I owl 1
2.2-) It was dissolved in 50 d of refluoroethane, and this solution was dropped into 100 d of a saturated aqueous solution of Na HC03 to terminate the polymerization. Thereafter, the product was washed and dried in the same manner as in Preparation Examples 1 to 7 to obtain a rubbery substance.

The yields of each preparation example were 93%, 93%, and 9%, respectively.
They were 9%, 99%, 87% and 86%.

Preparation Example 13 'A Preparation Example 1 to a total of 101 of the two types of silanols shown in Table 1
Copolymerization was carried out in the same manner as in 7. After the polymerization was completed, the product was dissolved in 1.1.2-trichloro-1,2,2-1-lifluoroethane, and washed and dried in the same manner as in Preparation Examples 1 to 7.

Gas separation membrane samples were also prepared in the same manner as in 1i'i Preparation Examples 1-7.

Preparation Examples 14-15 A total of 9y of the two types of silanols shown in Table 1 were reacted with vinyl silane, followed by polymerization, washing and drying in the same manner as in Preparation Examples 8-12.

The gas separation membrane sample was prepared by dissolving the above-obtained polymer in a mixed solvent of toluene and meta-xylene hexafluoride (l = 1) to a concentration of 10% by weight, and then adding dicumyl peroxide to the solution. Added 5% by weight to the combined material,
A film was formed in the same manner as above, and after drying, it was heated at 110° C. for 16 hours under a reduced pressure of 20 flHg for crosslinking.

Preparation Example 16 Vinylsilane kmfM Example 8 to silanol shown in Table 1
12, and then also in Preparation Examples 8 to 12.
Polymerization, washing and drying were carried out in the same manner as above.

Gas separation membrane samples were prepared using the same procedure as in Preparation Examples 14-15.

Test Example For each gas separation membrane sample prepared above, the time required for a constant volume of nitrogen and oxygen to permeate was determined according to ASTM D14114.
Measurement was carried out under the following conditions according to the V Method, and the oxygen permeability coefficient and separation coefficient were calculated from the results using the equations described below. The results are shown in Table 1.

Measurement conditions Gas used: Standard mixed gas of 79% nitrogen and 21% oxygen by volume.

Test pressure: Secondary pressure: 5 Kg/Cd (absolute pressure), secondary pressure: 1 Kg/Cd (absolute pressure).

Gas permeation jii: 4cco Test time 2. Time required for the above permeation (seconds).

Gas separation membrane area: 185CJ Gas separation membrane thickness: The value obtained by weighing the polymer superimposed on the support and dividing this value by the polymer adhesion area and polymer specific gravity.

Calculation formula for permeability coefficient and minute M coefficient (in the formula, K is permeation coefficient, Q is gas permeation amount, L is film thickness, S
is the membrane area, T is the time, ΔP is the pressure of the gas on the primary side and the secondary side (however, it indicates partial pressure filtration) (in the formula, α is the separation coefficient, K
O2 represents the permeability coefficient of fluorine, and KH2 represents the permeability coefficient of nitrogen. ) KOHO,01N was added to Comparative Example 10f, and ring-opening polymerization was performed at 120°C for 14 hours while stirring in a nitrogen stream. after that,
1,1,2-trichloro-1,1,2-trichloro-1,1,2-trichloro-1,1,2-trichloro-1,1,2-trichloro-1,1,2-trichloro-
1゜2.2-Trifluoroethane is eluted and a rubbery polymer 9. :Mt-obtained.

The gas separation membrane sample contained this polymer in 1. ．． 1.2- t'
) 80% by weight of a 1:1 mixture of chloro-1,2,2-trifluoroethane and meta-xylene hexafluoride.
% by weight, and the rest was prepared in the same manner as in Preparation Examples 1 to 14. Thereafter, the same test as above was conducted, and the results shown in Table 1 were obtained.

In the above table, the silanol represented by (su～he) and the silane represented by (XD～(X
) and silanes (x1) to (xill), only the substituents: R1, R2 or R3 and 11 are abbreviated.

(i) R1 and R2: CH:4.5s=6(If
) R1 and R2: CH2CH2CF2CF2C
F3.11=6(iii) R1 and R2: CH2
CH2CF2CF3.11 = 8 (iV) R1 and R2: CH2CF2(CF2), CF3, x1=
6MRI and R”: CH2CH2(CF2)8
CF3, "1=4(Vi) R' and R":
CH2CH2CH20CH2CF2 CF3, c4F7
．． 11=6 (Vlll) R1o LUR2: CH2CH2CF2
CF2CF<::2, n=4 one year R1 and R2: CH2CH2CF2CF2C
F Yuni, 11=2 18 mol%, 11=4 16 mol%
, n = 626 mol%, n = 8 28 mol%, x1 = 10 15 mol%, iris = 125 mol%, 11 = 142 mol% mixture silanol (x) CH2CH2CF3 ■ CH2CH2CF: + Sv0H CH.

1 “C, JS〆4 C horse (XI) R”: cI(3 (X:l) R”: CH2CH2(CF2)5 C
F': (CF,.

(x river) R3: to H2cl (, CF2 to CF20
2 Patent applicant for CFOC3F7 and above Daikin Industries, Ltd.

Claims (1)

[Claims] 1. A gaseous S film made of polysiloxane reed or a crosslinked product thereof containing a fluoroalkylene X-t or fluorooxyalkylene group in the main chain. 2. The gas separation membrane according to claim 1, wherein the fluoroalkylene group is a group represented by the following formula: % formula % (in the formula, 11 represents an integer of 1 to 15). 8. The fluorooxyalkylene group is a group represented by the formula: A gas separation membrane according to claim 1.