JPS5962302A - Gas selective separating element - Google Patents

Abstract

PURPOSE:To provide a membrane material which consists of >=1 kinds of one of fluoroolefin and vinyl ether and >=two kinds of the other, is balanced between the coefft. of sepn. (PO2/PN2) and the permeation rate of O2 and can sustain the performance thereof. CONSTITUTION:A titled gas separating element consists of at least a terpolymer consisting of 1 kind of fluoroolefin and two kinds of vinyl ether or two kinds of fluoroolefin and 1 kind of vinyl ether. If such copolymer, which is at least a terpolymer is used, the balance between the permeability coefft. of O2 and the coefft. of sepn. of N2 is good, and the performance thereof is stably maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a separation element having permselectivity for mixed gases, particularly when producing oxygen-enriched air from air by a membrane separation method. This relates to a separation element with excellent transparency.

Oxygen-enriched air with an oxygen concentration of 30 to 50% is required, for example, for blast furnace ventilation, combustion assistance, petroleum protein processing, waste liquid treatment, exhalation in medical care, and the like. Conventionally, oxygen-enriched air has been obtained by producing high-purity oxygen by cryogenic liquefaction distillation and then mixing with air to obtain the desired oxygen concentration.

However, in such methods, high-purity oxygen is generally contained in a pressure vessel, so there is a risk of handling the pressure vessel, or the necessity of a pressure regulator to keep the mixed gas concentration constant, and the complexity of its operation. There were various problems such as.

On the other hand, as a method of obtaining 60 to 50 cm of oxygen-enriched air,
There is a membrane separation method.

This method provides direct oxygen-enriched air, is operationally simple, and is economically advantageous.

Organopolysiloxane-polycarbonate copolymers are conventionally known as such separation membranes (Japanese Patent Laid-Open No.
0-41958).

The oxygen permeation rate of this element is 10-7 to 10-8 kat.
Although fn/tn'12・sec・cm Hg is large, the oxygen separation coefficient (Poz/PII2) is 2.0 to 2.4.
There is a limit to the oxygen concentration of oxygen-enriched air that can be obtained. On the other hand, fluorine-containing resins such as polyethylene terephthalate, polyethylene, polycarbonate, and tetrafluoroethylene-hexafluoropropylene copolymers have oxygen separation coefficients of 6 to 6.
5, but the oxygen permeation rate is 10-"~10-0-
12 (L-/cm2・sec・anHg), so it is difficult to expect that a sufficient flow rate of oxygen-enriched air can be obtained.

In view of this point, the present inventor has determined that the separation coefficient (PO2/PN2
) and oxygen permeation rate are balanced and whose performance is stable and long-lasting.As a result of various studies and examinations, we have developed compounds selected from a specific group into ternary or higher-compound compounds. By obtaining a copolymer of and dissolving it in a solvent to make a casting film, etc.
This is a headline about what an excellent gas separation element can do.

Thus, the present invention provides a gas selection comprising at least a terpolymer containing at least one fluoroolefin and at least two vinyl ethers, or at least two fluoroolefins and at least one vinyl ether. The present invention provides a separation element.

The minimum basic composition of the copolymer constituting the device of the present invention is at least ternary, consisting of one type of fluoroolefin and two types of vinyl ether, or at least ternary, consisting of two types of fluoroolefins and one type of vinyl x-frucD. It is a copolymer.

As the fluoroolefin/vinyl ether copolymer, conventional coating materials (Japanese Patent Publication No. 55-44085, Japanese Unexamined Patent Publication No. 55-25411, Japanese Patent Publication No. 45-11
Publication No. 309) or elastomer (Special Publication No. 59-'2)
No. 4277), but its existence as a functional element for gas separation is completely unknown.

When the minimum ternary copolymer of the present invention is adopted, the oxygen permeability coefficient and oxygen/nitrogen separation coefficient are better balanced than the binary copolymer, and the strength is also stable due to its performance. I can sustain power 5. By using multiple fluoroolefins or vinyl ethers,
A good synergistic effect on gas permeability is obtained.

Examples of the fluoroolefins used in the present invention include trifluorochloroethylene, tetrafluoroethylene, vinylidene fluoride, trifluoroethylene, hexafluoropropylene, (-fluorohexyl vinyl nitrate, 71/ , perfluoropropyl vinyl ether, and the like.

Examples of the vinyl ether include n-butyl vinyl ether, isophyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, n-octyl vinyl ether, and hydroxy vinyl ether.

The respective content ratios in these ternary or higher copolymers are strictly determined depending on the type of each compound used and the copolymerization system, but generally 40 to 60 mol of fluoroolefin and 4 to 60 mol of vinyl ether are used. It is appropriate to adopt it.

If these combined amounts deviate from the above range, the separation coefficient and oxygen permeation rate will become insufficient, which is not preferable.

And within the above range, fluoroolefin 45 to 55
Morti and vinyl ether 45 are particularly preferred since they also provide long-term stability.

Furthermore, in the present invention, among these copolymers, trifluorochloroethylene and tetrafluoroethylene are used as the fluoroolefins, and n-butyl vinyl ether and iso-butyl vinyl ether are used as the vinyl ethers. Ethylene chloride/ethylene tetrafluoride/ia-butyl vinyl ether, ethylene chloride trifluoride/n-
Butyl vinyl ether A terpolymer of 2-iso-butyl vinyl ether provides the most favorable results as a polymer in the present invention in terms of separation coefficient, oxygen permeation rate, and long-term stability.

In fact, the means for producing the copolymer according to the present invention is not particularly limited, and for example, emulsion polymerization, solution polymerization, bulk polymerization, suspension polymerization, etc. can be adopted, but the stability of the polymerization reaction operation, Emulsion polymerization in an aqueous medium or solution polymerization using alcohols such as t-butanol, esters, saturated halogenated hydrocarbons containing one or more fluorine atoms, etc. as a solvent for ease of separation of coalescence, etc. is preferably adopted. The process of the present invention can be carried out in batch, semi-continuous, continuous, etc. operations.

Further, the degree of polymerization of the copolymer according to the present invention is usually 100 to 1.
It is appropriate to adopt 0,000, preferably about 500 to 5,000.

A thin film as a separation element is formed from the copolymer thus obtained. The thickness of the thin film is usually 0005~500
μ, preferably about 0.01 to 100 μ is appropriate.

There are no particular limitations on the means for forming such a thin film, and any known means may be employed as appropriate. For example, cast molding is a suitable example, as described in U.S. Pat. Methods such as gently lifting the material may also be adopted.

The former method involves adjusting the concentration and viscosity of the casting solution and, in some cases, stretching the solution on the water surface; the latter method involves controlling the pulling speed of the glass plate or support film. Furthermore, it becomes possible to control the film thickness as appropriate.

Next, the present invention will be explained by examples.

Example 1 Contents *260 cr: t-butanol 101 in a stainless steel autoclave with a stirrer (pressure resistance 25 mm/6n2)
fSn-butyl vinyl ether? , iso-butyl vinyl ether 1&5f, potassium carbonate cL6, and azobisisobutyronitrile (AIBN) [1058r], and dissolved air was removed by solidification and degassing with liquid nitrogen.

Next, 31.4 r of ethylene trifluoride chloride is introduced into the autoclave and the temperature is gradually raised. When the temperature inside the autoclave reaches 65℃, the pressure is 18 KSI/o.
Indicates n'-G. Thereafter, the reaction was continued under stirring for 55 hours, and when the pressure decreased to 1.7 Kg10n2-G, the autoclave was cooled with water to stop the reaction.

After reaching room temperature, purge unreacted monomers and open the autoclave. 100CC of the obtained polymer solution
Dissolve potassium carbonate in acetone and pass through a 6G glass filter. The P solution is gradually poured into stirred methanol to precipitate a polymer, which is then washed with methanol and dried under reduced pressure at 60° C. to recover the polymer. Polymer yield is 5.1r ;% IJ Mama-1 degree 2
The monomer reaction rate was 60.1% by weight, and the average polymerization rate was 77.6 r/4-h. Intrinsic viscosity ([η] of the obtained tt polymer at 30°C in tetrahydrofuran
) is t 04 dt/i/, the thermal decomposition temperature (Td ) is 224°C, the glass transition temperature (Tg) is 14°C, and fc
. GELNOKU-MIE SHOTE CHROMATOGRAPH-1-(GP
O) The average intermolecular distance (Mω) with ■ was 500,000, and the molecular number distribution i was 12.3.

Example 2 1 t-phytol was added to the autoclave used in Example 1.
01f, in-phthyl vinyl ether 26,9, potassium carbonate 0. 6 S', AIB'N O. 058
2, and repeat solidification and degassing with liquid nitrogen 2 1 pl to remove dissolved air in the system. Thereafter, 15.8F of trifluorochloroethylene and then 1119F of tetrafluoroethylene were introduced into the autoclave, and the temperature was gradually raised. When the temperature inside the autoclave reached 65°C, the pressure was increased to 1 cL3. Ky/ctn2-G is shown. After that, 5
The reaction continued under stirring for 5 hours, and the pressure increased to /, 4 K17
When the temperature drops to cm2-G, the autoclave is cooled with water to stop the reaction.

After reaching room temperature, unreacted monomers are removed and the autoclave is opened.
Dissolve in cc of acetone and filter out potassium carbonate using a 3G glass filter. The P solution is gradually poured into stirred methanol to precipitate a polymer, which is then washed with methanol and dried under reduced pressure at 60° C. to recover the polymer. Polymer yield was 52. Of, the polymer concentration is 24.
2% by weight, monomer reaction rate 5a8%, average polymerization rate 71
．． It was 0ri/jh. [η] of the obtained polymer in tetrahydrofuran at 30°C is 11s dt/y, T
d was 220°C, and Tg was 13°C. The iω determined by GPO was 550,000, and the molecular value distribution was 2.3.

Example 6 The terpolymer obtained in Example 1 was dissolved in ethyl acetate, cast on a scratch-free glass plate using an applicator, dried, and peeled off from the glass surface to form a transparent film. I got it. Table 1 shows the measurement results of the gas permeability of this film.

Example 4 A film was formed using the terpolymer obtained in Example 2 in the same manner as in Example 4, and the gas permeability was measured.

The results are shown in Table 1.

Ratio 4ji; , tetrafluoroethylene/1so-butyl vinyl ether (ratio 11111J3), and trichlorinated ethylene/ethyl vinyl ether (comparative example 4) (2) Equimolar di-element copolymers were synthesized and formed into films to obtain films. The measurement results of the gas permeability of the film are summarized in Table 1.

Table 1 Example 3 57 1.02X 10''-'
2.56 X 10 10 Five? 8U4501.
06X10'2.50X10-1' 4.24 Comparative Example 1 57 1.15X 10'' 3.3
X 10-10 A5 & 243 [L48X
1091.17X10-1O4,11/3562.1
1X10'6.59X10"-1"3.2# 44
1124 x 10'048 dissolve. This is polyacrylonitrile/N-vinyl-
Using an ultrafiltration membrane made of 2-pyrrolidone copolymer (bore diameter of surface active layer 50 to 100A, membrane thickness including non-woven lining 200μ, membrane area 100cn+2), the tear overpressure was 1.5 Kg/tm. ”-G under pressure. After filtration, it is dried at room temperature to obtain a predetermined composite membrane.

The thickness of the thin film broken on the porous support membrane was calculated from the weight and was 2.4 μm. As a result of measuring the gas permeability of this composite membrane by the pressurization method, the oxygen permeation rate QO2g=
The oxygen/nitrogen separation coefficient α was 5.3×10 −3 3/'nt”h atm and 4.0.

Example 6 The terpolymer of trifluorochloroethylene/tetrafluoroethylene/1so-butyl vinyl ether obtained in Example 2 was formed into a composite membrane in the same manner as in Example 5, and its gas permeability was determined by the pressure method. As a result of measurement, Qo2-51×10″′3,
α=42.

-r-Series Sales Ichisha Mesho": April 1981 70th 11'8'l Agency" (Government? 1.'Sugi'f'll Tue yH (
31, Display of matter A'1 111j
G 9 G 9 'Ishishi 2, famous phrase of invention.

Gas selective separation element: i, l] Elbow 1-1, elbow 1-1, borrowed old '1 which relationship. 1.15 m 21
No. Koubunshiouyouginyutsukenkyu: No. 5'ir (', 15 Polymer Applied Technology Research 2;'■Gai Ito Yoshikazu Chairman Italy 11J' EIJ 7J・'19th generation' 1) 1 person 6, on the 1st floor Increased number of inventions None 7. Subject of amendment (1) Claims column of Specification 1 (2) Allowance for the invention of Akekino Contents (1) As shown in the attached sheet (2) Delete "Perfluoro..., xylvinyl ether, perfluorobrobyl vinyl ether" in the 5th to 4th lines from the bottom of the 5th section of the specification.

5311 Paper 2 + 'I+'l''a'lClaim 1, at least one kind of fluoroolefins and at least two kinds of vinyl ethers, ?j: L, < at least two kinds of fluoroolefins and at least two kinds of vinyl ethers? A gas selective separation element comprising at least one ternary copolymer.

2. Element 7- of claim (1), wherein the content ratio of the fluoroolefin is /lO to GO mol'4.

The trick is that the fluoroolefin is trifluoroethylene chloride,
Tetrafluor (IL ethylene, -vinylidene fluoride.

The element according to range (1) or (2), which is difluorinated propylene hexafluoride.

・1. Vinyl ether is 11-butyl vinyl ether,
Isophthyl vinyl ether, ethyl vinyl ether, xyl vinyl ether.

11--Octyl vinyl ether and hydroxyvinyl ether according to claim (1).

Claims (1)

[Scope of Claims] 1 Consists of at least a ternary copolymer containing at least one fluoroolefin and at least two vinyl ethers, or at least two fluoroolefins and at least one vinyl ether Gas selective separation element. 2. The element according to claim (1), wherein the content of the fluoroolefin is 40 to 60 mol. (5) Claims (1) in which the fluoroolefins are trifluorochloroethylene, tetrafluoroethylene, tetrafluoroethylene, vinylidene fluoride, trifluoroethylene, hexafluoropropylene, perfluoropropyl vinyl ether, perfluoropropyl vinyl ether ) or (2) element. 4. Hinyl ether n1 n-butyl vinyl ether, iso-butyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, n-octyl vinyl ether, hydroxy vinyl ether, the range of 8 desired (
1) element.