JPS596905A - Selective gas permeable membrane - Google Patents

Abstract

PURPOSE:To attain to enhance coefficient of oxygen permeation and coefficient of oxygen and nitrogen separation, by selecting a polymer of fluoroalkyl acrylate and/or fluoroalkyl methacrylate as a membrane material. CONSTITUTION:A polymer constituting a selective gas permeable membrane is obtained by polymerizing fluoroalkyl acrylate and/or fluoroalkyl methacrylate. In this case, one kind or more of a compound selected from compounds shown by general formula I (wherein R is H or CH3, R1 is 1-16C alkyl group containing three or more fluorine atoms) is pref. polymerized. Further pref., said membrane is obtained by polymerizing one kind or more compound selected from compounds shown by general formula II (wherein R1 is H or CH3, X is H or F, m is 1-6 and n is 2-6). Air is passed through thus obtained permeable membrane to be capable of obtaining oxygen enriched air.

Description

[Detailed description of the invention] The present invention relates to a selectively permeable membrane.

More specifically, the present invention facilitates thin film production.

Moreover, it has mechanical strength as a thin film and is related to a selective gas permeable membrane with a large permeability coefficient, and is particularly suitable for obtaining oxygen-enriched air with a high oxygen concentration using the membrane from air. This relates to a selective gas permeable ARK used for.

Conventionally, there have been methods for separating mixtures using membranes, but these methods mainly involve liquids using reverse osmosis membranes and ultrafiltration membranes. On the other hand, with regard to the separation of mixed gases by membranes, the selectivity and permeation amount were insufficient, so there was no effort left.
On the contrary, the application of the gas permeation phenomenon in films has been mainly focused on gas barrier films for packaging.However, in recent years, the use of membranes mainly composed of polymers has been used to improve gas permeability depending on the type of gas. Many proposals have been made for gas fractionation and concentration that take advantage of these differences.In industry, air is a mixed gas that is highly desired to be separated. Oxygen, which accounts for approximately -0% of the air's components, is necessary for humans to survive.

It goes without saying that gas is an indispensable gas, but it is also used in industrial applications such as internal combustion engines, the steel industry, the food industry, and the food industry.
It is a very important gas used in medical equipment, waste treatment, etc. Therefore, there is a strong desire for a method of efficiently, inexpensively, and easily separating oxygen from air.

In membrane separation methods, it is difficult to obtain air with a high purity oxygen concentration through one stage of membrane separation, and several attempts have been made to obtain oxygen-enriched air with a certain consistency. A typical method is a method using a membrane containing organopolysiloxane as a main component. However, membranes whose main component is organopolysiloxane have a high oxygen permeability coefficient, but a small separation coefficient between oxygen and nitrogen, which limits the oxygen concentration of the oxygen-enriched air that can be obtained.
Several other proposals have been made, but in all of them, the oxygen permeation number is 17. It was too small and difficult to put into practical use. A membrane with a high discharge permeability coefficient and high separation coefficient was desired, and the present inventors investigated membranes made of various polymers (hereinafter referred to as polymers) and arrived at the present invention. Ta. That is, we have discovered that enriched air with a high oxygen concentration can be efficiently obtained by using a membrane made of a polymer of fluoroalkyl acrylate and/or fluoroalkyl methacrylate. 0 In other words, the object of the present invention is to provide oxygen-permeable membrane L! when passing air through a permeable membrane to obtain oxygen-enriched air. 1. Another object of the present invention is to provide a selective gas permeable membrane having a high separation coefficient between oxygen and planted trees.

Embodiments of the present invention will be described in detail below. The polymer constituting the selective gas permeable membrane of the present invention can be obtained by polymerizing fluoroalkyl acrylate and/or fluoroalkyl methacrylate. Preferably, the general formula cfE, r-<. . □, (only: H1 mourning is O
H3, R :), 01~. containing 3 or more cumulative atoms. 1+ is OH3, x : H, F,
It can be obtained by polymerizing one or more compounds selected from the compounds represented by jQ=/~7, n-J~4).

Here are some more specific compounds.

Trifluoromethyl ester, trifluoroethyl ester of acrylic acid and methacrylic acid.

Perfluoroethyl ester, perfluoropropyl ester, perfluorobutyl ester.

Perfluoropentyl ester, perfluoroethyl ester, perfluoroheptyl ester, perfluorooctyl ester, perfluorononyl ester, perfluorodecyl ester, perfluorolauryl ester, perfluorobalmityl ester, perfluorostearyl ester, perfluorohydro These include chiralkyl ester, perfluoro-7cetyl alkyl ester, and the like.

There are no particular restrictions on the polymerization method for the above compound, and generally well-known polymerization methods can be used. Examples include radical polymerization using an initiator, ionic polymerization, polymerization using a Ziegler catalyst, or polymerization initiated by radiation irradiation, ultraviolet irradiation, etc., but radical polymerization is usually carried out because it is simple. Further, any method such as bulk polymerization, solution polymerization using a solvent, suspension polymerization, or emulsion polymerization may be used. There are no particular restrictions on the polymerization conductivity, and there are no particular restrictions on the polymerization pressure.

There is no particular restriction on the degree of polymerization of the obtained polymer, as long as it is at least the degree of polymerization at which film-forming properties are exhibited. Desirably, the degree of polymerization is 700 or more.

For the preparation of the membrane, generally well-known methods are applied. It is obtained by casting it using a molten metal, evaporating the melt, and then peeling it off. The thickness of the membrane is adjusted by the concentration of the polymer solution and the thickness of the cast solution. Alternatively, the polymer solution is cast onto a porous support using a doctor knife, and the melt is evaporated.

1. In general, specific shapes of membranes are known, such as flat membrane, tubular, hollow fiber, and filament, but the present invention can be applied to any of these shapes.

As mentioned above, the selective gas permeable membrane of the present invention has a large permeable membrane V, and in particular, when obtaining oxygen-enriched air from air using the membrane of the present invention, it is difficult to use the conventional selective gas permeable membrane. It has a large separation coefficient between oxygen and nitrogen as well as a large oxygen permeability coefficient, and exhibits excellent performance.

The selective gas permeable membrane of the present invention can be used to separate natural gas or threatening helium, to decompose and recover produced gas from synthesis gas, to decompose and recover raw material gas, to remove radioactive noble gas from nuclear reactor exhaust gas, and to produce hydrogen gas from petroleum waste gas after price removal. recovery, removal of popular pollutants such as sulfur gas and valuable hydrogen gas, etc. In particular, as mentioned above, it is suitably used for concentrating oxygen in the air, supplying oxygen-enriched air to combustion systems, supplying oxygen-enriched air to medical equipment, and purifying rivers. It can be used for supply, etc.

The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples.

In addition, the transmission coefficient is ts3arm/Cn126 see
It is expressed in units of ecnHg, and the separation coefficient is, for example, in the case of oxygen and nitrogen, the separation coefficient α (PO2/PN2) =
This is the oxygen permeability coefficient/nitrogen permeability coefficient.

Example / Add water/θθml f to a 3θθml four-loaf flask, add 0.7 part of polyvinyl alcohol, and while blowing away element 9 (stir to dissolve). Add 2, @2, 3.3 to it.
- 3θ parts of tetrafluoropropyl methacrylate and 0.0 parts of dodecyl mercaptan. Add 5 parts of hydroxide and 6.75 parts of lauroyl peroxide. Then, it is polymerized at θ°C for a period of time. After polymerization, filter the polymer and wash the water.
Vacuum dry at C for 9 hours. The yield of the obtained polymer was 2 y. The polymer/θy obtained here is dissolved in acetone 907. Pour the solution into glass root soil for 5 minutes.
It was cast to a thickness of θμ and air-dried. The membrane was then peeled off and an air permeation test was performed. The permeability coefficient of oxygen is -I
J%x/θ-9cr713- (:m/6n2. II
e e・mHg and α(PO2/PN2 )
-3,11.

ExamplesExamples/of! The same conditions were used except that 30 parts of perfluorononyl methacrylate was used instead of 30 parts of 2,3.3-tetrafluoropropyl methacrylate. The yield of the obtained polymer was 7F. Further, a film was formed in the same manner as in Example/, and an air permeation test was conducted. The permeability coefficient of oxygen is /, θg×/θ−8crn” c
rn/cm2* s e c 1Hg, α(PO
2/PN2)=3.7.

Example 3 The experiment was carried out under the same conditions as in Example 1, except for the 3θ portion of 2,2,3,3-tetrafluoropropyl methacrylate.

The yield of the obtained polymer was 2/3F. Further, a film was formed in the same manner as in Example/, and an air permeation test was conducted. Oxygen a-excess coefficient if, ri, 5? jx/θ−173
m(yIH/ff7p' 8 e Q mouth Hg,
α(PO2/PN2)-J, J.

Examples 1 to 2 were carried out under the same conditions except that the compounds shown in Table 1 were used in place of 30 parts of 2.2,3.3-tetrafluoropropyl methacrylate in Example 1. The yield of the obtained polymer is shown in Table/.

The results of an air permeation test are also shown in Table/.

Claims (1)

[Scope of Claims] (C) A selective gas permeable membrane comprising a polymer of fluoroalkyl acrylate and/or fluoroalkyl methacrylate. R H or OH3, R1 is a carbon number containing 3 or more fluorine atoms/~/
or OH3, X represents H or F, m++=/-4, n=-2 to 6; 0
2. The selective gas permeable membrane according to claim 1, characterized in that the selective gas permeable membrane is made of a polymer of: