JPS59189904A - Gas separating permselective membrane and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain a novel gas separating permselective membrane comprising a polymer based on polyurea containing silicon in the main chain thereof and to provide a process for preparing the same. CONSTITUTION:A polymer comprising polyurea, which is obtained by reacting diamine represented by formula, for example, 2-12C, pref, 6-13C alicyclic diamine or polysiloxane-containing diamine and a compound having at least two dissocyanate groups, for example, 4-15C, pref., 6-13C dissocyanate, is formed on a microporous support to form a membrane comprising polyurea. The total thickness of the membrane and the support is at least 100Angstrom , usually, 300- 4,000Angstrom and selectivity of oxygen to nitrogen (oxygen permeation amount/nitrogen permeation amount) is, for example, 4.0-7.1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application The present invention relates to a novel selectively permeable membrane for gas separation made of a polymer mainly composed of polyurea containing silicon in its main chain.

PRIOR ART Various membranes have been proposed for use in separating oxygen and carbon dioxide from the atmosphere, that is, oxygen-enriching membranes, but among them, the one with the largest oxygen permeability coefficient is 6 x 10.
It is a silicone rubber that is cc (STP), C/crd, elemental, and Mycelia G. However, silicone rubber has a separation coefficient (
Oxygen permeation rate/nitrogen permeation rate) α is as low as 2.0, and it is difficult to form a thin film.

Therefore, it was proposed to manufacture a thin film of 0.1 μm or less by spreading a solution of a polysiloxane-polycarbonate copolymer, which is a polysiloxane and a polycarbonate block copolymer, on the water surface (Japanese Patent Laid-Open No. 51-89
(See Publication No. 564). However, the permeability coefficient of this membrane is 2×
1O-80C (STP)・Hen/ci・SecIlmll
g than silicone rubber, and the separation coefficient (α) is also 2.
It was as low as 2.

Recently, a membrane has been proposed that has a separation coefficient (α) of 3 or more and can be formed into a thin film of 10 μm or less by crosslinking amino-modified silicone oil with acid p-lide (Japanese Patent Laid-Open No. 57-105203). (see official bulletin). However, this membrane also had a relatively small separation coefficient (α) and did not have sufficient permeation performance.

OBJECTS OF THE INVENTION An object of the present invention is to provide a membrane with a high separation coefficient (-) and an excellent oxygen permeability coefficient.

Composition of the invention The present invention is represented by the following general formula (A) R4R.

A selectively permeable membrane for gas separation formed from a polymer made of polyurea obtained by the reaction of a diamine represented by the above with a compound having at least two incyanate groups, and a microporous support for the above reaction. This is a method for producing a selectively permeable membrane for gas separation using a membrane.

Here, p and q in formula (A) may be the same or different, and are an integer of 2 to 1O, preferably an integer of 3 to 8. When p and q are 1, the polymer is unstable due to the raw materials, making it difficult to obtain a good polymer, and when p and q are 11 or more, the film forming property becomes poor, which is not preferable. Further, R, , R, in formula (A) are each independently a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, preferably all hydrogen atoms are methyl groups.

Further, R, , R4, R, and R6 may be the same or different (a hydrocarbon group having 1 to 1 o carbon atoms. The hydrocarbon group may be substituted or unsubstituted, saturated or unsubstituted. It means a saturated aliphatic, alicyclic, or aromatic hydrocarbon group, and preferred examples include methyl, ethyl, various propyl groups, various butyl groups, vinyl groups, allyl groups, propenyl groups, phenyl groups, and benzyl groups. Number of carbon atoms in groups, etc.: 1~
7 hydrocarbon group, etc., particularly preferably carbon, number 1 or 2
Examples include alkyl groups and phenyl groups.

Ro in formula (A) K is an aromatic hydrocarbon group having a total number of carbon atoms of 6 to 14 or a fullkylene group having a total number of carbon atoms of 2 to 1 o, which may be bonded through a different atom, and preferably bonded through a different atom. It is an aromatic hydrocarbon group having 6 to 12 carbon atoms in total or an alkylene group having 2 to 6 carbon atoms, which may be If the total number of carbon atoms is 14 or more, the permeability decreases, which is not preferable. Preferred specific examples include (), (()).

Examples include -CH, S'e, +CH2+ (n is 2 to 5). Particularly preferably minutes.

-CH, CH, -.

In the present invention, other diamine components can be copolymerized together with the diamine component represented by the general formula rA). Such diamines have 2 to 2 carbon atoms.
It is advantageous to use aliphatic diamines having a strength of 12, preferably 6 to 100, alicyclic diamines having 6 to 13 carbon atoms, aromatic diamines having 6 to 13 carbon atoms, polysiloxane-containing diamines. Specific examples of these include aliphatic diamines such as ethylene diamine, tetramethylene diamine, hexamethylene diamine, and decamethylene diamine: cyclohexane diamine.

4.4'-Diaminodicyclohexylmethane.

Alicyclic diamines such as hyherazine; metaphenylenediamine, paraphenylenediamine 4.4'-diaminodiphenylmethane, 4.4'-diaminophenyl ether,
3.4'-diaminodiphenyl ether, N, N'
- Aromatic cyamiso such as diphenylmetaphenylenediamine, N,N'-dimethylmephenylenediamine; polysiloxane-containing diamines such as bis(aminopropyl)tetramethyldisiloxane, bis(7minobrovir)octamethyltetrasiloxane, etc. be able to. These can be used alone or in combination of two or more.

The diisocyanate used in the present invention is not particularly limited, but diincyanates having 4 to 15 carbon atoms, particularly preferably 6 to 13 carbon atoms are used, and specific examples include toluylene diisocyanate, phenyl diincyanate, 4. Aromatic diincyanates such as 4'-diphenylmethane diisocyanate and xylylene diincyanate, aliphatic diincyanates such as hexamethylene diincyanate, cyclohexyl isocyanate,
Alicyclic diisocyanates such as isophone diincyanate can be mentioned. These can be used alone or in combination of two or more.

In addition, a trifunctional or higher functional incyanate may be partially mixed with the diisocyanate.

In order to form the film of the present invention from the diincyanate component and the diamine component, for example, both may be polymerized on a microporous support to form a thin film of polyurea on the support. However, a preferred method is a method in which a solution of the diamine component is applied onto a microporous support membrane, which will be described later, and a diincyanate component is reacted therewith. The coating method may be any method such as dipping method, 1 μm coating method, wick coating method, spray coating method, etc., but the thickness of the applied diamine component is preferably 0.01 to 2 μm, preferably Q, 02 to IBM,
More preferably, the coating conditions should be controlled so that the coating thickness is 0.05 to 0.7 JJn. 1. If the coating thickness of the diamine layer is smaller than the above lower limit (i.e. 0.01 μm), the final thickness obtained The active layer of the composite membrane becomes too thin and its mechanical strength decreases. Furthermore, if the coating thickness is greater than 2 μm, the active layer becomes too thick and tends to impair the air permeability of the composite membrane.

Preferably, such diamines are soluble, especially in water,
Methanol, ethanol, improper tool, methylceramyl alcohol, dioxane.

Ethylene glycol, diethylene glycol.

Triethylene glycol, glycerin or a mixed solvent of two or more of these ico, i1! /lo.

It is preferable that it is soluble in m1 or more, preferably 0.51/100v1 or more.

A solution of the diamine compound of the present invention, which is dissolved in at least 0.1% in at least one solvent selected from these solvent groups, is applied to or impregnated into the microporous membrane VC.

A vitreous porous material is used as a base material for such a membrane.

Examples include sintered gold, ceramics, and organic polymers such as lulose ester, polystyrene, vinyl butyral, polysulfone, and vinyl chloride.

Polysulfonate has particularly good performance as the base material of the present invention, and polyvinyl chloride is also effective. The manufacturing method of polysulfone porous substrate is described in the U.S. Bureau of Salt Water Report (O8W Report) 43591.
c is also listed.

Such substrates generally have a surface pore size of about 100 to 10
A coating in the range of 0.00 oz.+--m is preferred, but is not limited to this, and the surface moisture content will depend on the final coating. These substrates can be used in either symmetrical or asymmetrical structures, but those with asymmetrical structures are preferable. However, these base materials are JjS
Air permeability measured by P 8117 device is 20~
3000 seconds, more preferably 50 to 1000 seconds. When the permeability is 20 seconds or less, defects tend to occur in the resulting composite membrane, and selectivity tends to decrease. Moreover, if the time is 30 oO seconds or more, only a composite membrane with low air permeability can be obtained.

Moreover, it is advantageous for the substrate C (microporous membrane) to have a pore size of 1 μm or less, preferably 0.5 μm or less as the maximum bottle pore diameter.

A polyurea thin film is formed on the substrate by bringing the substrate coated with the diamine described above into contact with a diisocyanate compound.

The composite membrane of the present invention can be obtained by bringing the diamine described above into contact with the diisocyanate compound solution described above on the microporous membrane. The solvent used to dissolve the diincyanate compound is one that is inert to the incyanate, dissolves it, does not substantially dissolve the diamine compound and the base material, and is capable of dissolving the formed polyurea. Preferably, those that do not dissolve or hardly dissolve. An example is n-hexane.

Hydrocarbon solvents such as n-hebutane, n-octane, cyclohexane, n-nonane, n-decane, n-1'7'cane, halogenated hydrocarbon solvents such as carbon tetrachloride, trifluorotrifluoroethylene, etc. Can be mentioned. The suitable concentration of the diisocyanate compound in the solvent may vary depending on the type of the compound, the solvent, the substrate, and other conditions, but the optimum value can be determined through experimentation.

ρ) and generally about o, i to 5.01, preferably 0.
A sufficient effect can be exhibited at 5 to 3.0% by weight.

Such interfacial reaction between the polyhumic compound and the polyfunctional WQ compound is carried out at room temperature to about 10°C, preferably from 20 to 50°C.
This can be carried out at a temperature of 2 seconds to 1°, preferably 10 seconds to 5 minutes. This interfacial reaction can be carried out so that it is mainly concentrated on the surface of the membrane.

In this way, a composite membrane having a thin membrane of a polycondensate having permselectivity on the surface of a microporous substrate is obtained.

The thickness of the permselective membrane in the membrane is not strictly defined, but the total thickness is at least 100 onguest p-
(usually 300 to 4000 Å) can have a thickness of l=+−,4.

The membrane of the present invention may be in any form such as a flat membrane or a hollow fiber.
Flat membranes can be put to practical use in the form of so-called plate-and-frame type and spiral type modules, tubular modules or, in the case of hollow fibers, hollow fiber type modules with an IC membrane inside or outside the fibers.

Effects The selectively permeable membrane for gas separation of the present invention can be used, for example, in the following applications by utilizing its excellent gas permeability, but is not necessarily limited to these applications.

For example, it can be incorporated into devices that produce oxygen-enriched air from air to improve the combustion efficiency of engines, heating equipment, etc., and can also be used as cleaner oxygen-enriched air, as nursery boxes for premature babies, and as treatment equipment for people with respiratory disorders. Alternatively, the artificial lung can be used as an artificial gill.

The present invention will be described below with reference to Examples.
It is not limited to these.

"In the middle part of the example" indicates parts by weight.

Reference Example 1 A dense VC woven Dacron tea woven fabric (basis weight xsoy/m') was fixed on a glass plate. Then,
12.5 wt% of polysulfone and 12.5 yt% of methylcellosolve were placed on the nonwoven fabric.

and the remainder dimethylformamide to a thickness of approximately 0.
．． A nonwoven fabric-reinforced porous polysulfone membrane was obtained by casting into a 2μ no-form and immediately gelling the polysulfone layer in a water bath at room temperature.

The porous polysulfone layer obtained in this way has a thickness of about 40 to 70μ, has an asymmetric structure, and has many micropores of about 50 to 600A on its surface, as shown in electron micrographs. It was discovered by g. In addition, these porous substrates have an air permeability of 15 by JIS P 8117 equipment.
It was 0 to 300 seconds.

Example 1 1 part of bis(7minobyldimethylsilyl)benzene was dissolved in a mixed solution of 49.5 parts of water and 49.5 parts of ethanol. After immersing the polysulfone microporous membrane obtained in Reference Example 1 in this solution for 5 minutes, the membrane was pulled out of the solution, held vertically, and drained for 10 minutes at room temperature. mosquito(
1fjjt% n-hexane solution of 4,4'-diphenylmethane diisocyanate 106
After being immersed in td for 3 minutes, it was air-dried at room temperature for 1 day.

Table 1 shows the results of measuring the gas permeability of this membrane using a Seikaken type gas permeability meter manufactured by Rika Seiki Kogyo ■.

Example 2 Bis(aminopropyldimethylsilyl)benzene 0.5
part was dissolved in a mixed solution of 50 parts of water and 50 parts of ethanol. The porous membrane was immersed in this solution as in Examples 1 and 1 and drained.
%g) to -P-nadecane-1 solution I o orttl
After immersing it in the solution for 3 minutes, it was further immersed in the n-hexane solution for 30 minutes.
Dipped for seconds, removed and air dried.

The performance of this membrane is shown in Table 1.

Example 3 A membrane was obtained in exactly the same manner as in Example 2, except that hexamethylene diincyanate was used in place of inhorn di-insifinit in Example 2. The performance of this test is shown in Table 11C.

Table 1

Claims (1)

[Claims] l) The following general formula prisoners R and R. A selectively permeable membrane for gas separation formed from a polymer consisting essentially of a polyurea obtained by reacting a diamine represented by the following with a compound having at least two incyanate groups. 2) The following general formula ( A) R4R. The diamine component represented by
1. A method for producing a selectively permeable membrane for gas separation, which comprises polymerizing a compound having two of these on a microporous support to form a polyurea membrane substantially made of polyurea on the support.