JPS62227423A - Gas separating membrane - Google Patents

Abstract

PURPOSE:To prepare a gas separating membrane of high selectivity and permeability by using a copolymer mainly consisting of amine component having siloxane structure and polyisocyanate component. CONSTITUTION:Amine component and polyisocyanate shown in Formula I and Formula II are reacted. In said process, amine component shown in Formula II should be less than 45mol% of the whole. Provided component shown in Formula II is too much, permeation speed is increased and selectivity is lowered, and membrane properties can be controlled by adding quantity of component. As polyisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate or the like is used. 10ppm-10wt% of diamine component solution is coated on a porous substrate, and then 10ppm-10wt% of polyisocyanate component solution is contacted to manufacture a separating membrane.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a separation membrane having selective permeability for gas-compounds, and which has a separation membrane that has a permeability of 4.
Regarding the minute lll11 membrane.

The #L element exists in the air at a concentration of about 21 g, but if air with increased oxygen concentration is supplied, it can be used to improve combustion efficiency in boilers and automobile engines, use low-grade fuels, etc. It is useful as breathing air for people with respiratory disorders.

A convenient method for separating oxygen from the air is the membrane separation method. However, with the membrane separation method, it is difficult to completely separate oxygen and nitrogen from the air in one stage of separation, and what is actually being carried out is the production of so-called oxygen-enriched air with increased agricultural production. Among those currently in practical use, the high oxygen concentration that can be obtained by passing through the membrane once is approximately 4
It is 0chi. The approximately 40% oxygen-enriched air is used for breathing air, etc.

In order to use the membrane separation method to outperform enriched air with a relatively low oxygen concentration, it is necessary to select a membrane that has good separation properties between hydrogen and nitrogen, but in general, membranes that have good separation properties are used. tends to have a lower oxygen permeability, so in reality t
It is necessary to select a membrane material that has a well-balanced permeability for 1N cords, nitrogen, monomers, and oxygen. On the other hand, since the rate of oxygen permeation through a membrane is inversely proportional to the thickness of the membrane, it is also essential to be able to form a membrane with an extremely thin thickness in order to increase the rate of permeation.

From this point of view, for example, polymethylpentene and poly2,6-dimethylphenylene ether are selected as membrane materials that have good separation properties and relatively high oxygen permeability.
Various proposals have been made to form ultra-thin films (for example, see Japanese Patent Laid-Open Nos. 57-71605 and % 51-89564).

However, all of these membranes have a flat membrane shape, and are not limited to hollow fiber membranes that can increase the membrane area per module volume.

The present inventor has previously proposed a method for fabricating membrane materials that can easily produce ultra-F4 membranes in the form of flat membranes or hollow fiber membranes (Japanese Unexamined Patent Publication No. 58-193701). -19370
(See Publication No. 3).

In such a membrane, the dimethylsiloxane content in the membrane structure can be changed from high to low oxygen/nitrogen selectivity, and the permeation rate of the fR element also changes accordingly. It changes from small to large.

Although it is well known that the properties of membranes can be varied, it is possible to obtain relatively high concentrations of oxygen-enriched air at an efficient rate, i.e., to improve the oxygen/nitrogen separation properties. High (
There are few membrane materials that are suitable for achieving a higher balance between high oxygen permeability and high oxygen permeability. The present invention was arrived at as a result of intensive studies to obtain a membrane with well-balanced separation characteristics and oxygen permeability. and a compound 0H30 represented by the following formula (If)
H1 (n Proverbs 1.2 or 3) H3 IH3 (Ml) A mixture of an amine component and a polyisocyanate in which the compound represented by the formula (Il) accounts for 45 mol or less of the total It is a gas separation membrane mainly formed from components.

In the fourth method, which is approximately 40 cm, the separation characteristics of the membrane required when attempting to separate oxygen-enriched air with a relatively high oxygen concentration from air in one stage, that is, the separation of oxygen and phoneme. The selectivity expressed as the ratio of permeability coefficients should be 2.5 or more, but this is the case when separation proceeds under ideal conditions, and in reality there is a driving force of 1!1II on both sides of the membrane.
In) of pressure to let! 'Separation deteriorates due to the ratio of P pressures or concentration polarization generated on the membrane surface.

Therefore, a membrane that is more selective than the ideal state is required.

Currently, when separating air using membranes, in order to reduce the energy required for separation (actually, the cost of driving the pump to generate pressure), the pressure is often reduced on the permeate side of the membrane, and the degree of pressure reduction in this case is , the selectivity of the membrane is at least 3.5, preferably 150-200 i'')? due to the 11 @ power of the pump, etc. Under such operating conditions, when attempting to draw about 40 g of oxygen-enriched air, the selectivity of the membrane is at least 3.5, preferably 3.7 or more.A material with such selectivity and high tR elemental permeability is required, and practically, the I!I!2 elemental permeability coefficient is at least 5X. 10
"cc(STP)'(m/7"SeC" cmH
g.

Preferably 7 X 10” cc (8TP)
・1-set for ex/, ・cmHg or more is required.

The essential point of this membrane material is that it can be made into a 4iVcs membrane, and when made into a thin membrane, the thickness of the separation membrane is 0.
A thickness of 2 μm or less, preferably 0.1 μm or less is suitably used.

The amine component used to form such a 111 film is a mixture of at least two types of compounds, one of which is an amine compound (referred to as amine component (1)).
is represented by the following formula (formula (I) below. Here, n represents 1.2 or 3.

The larger n is used, the higher the permeability but the lower the selectivity.

Part IIIm can be formed from such a diamine and polyisocyanate alone, and 8 of the polyisocyanate used can be formed.
It is possible to change the performance of the membrane formed by converting 1 [2], but in general, these have high selectivity for oxygen/nitrogen but only low permeability for elements. do not have.

Therefore, in order to increase oxygen permeability, a diamine (referred to as amine component ([)) represented by the following formula (formula (I) below) is used as a copolymerization component.

OH1 ■ H2N-0H20)12-NH-(5i (O-
The gist of the present invention is to add 8i 0H3)3...(11 straight OH2).

By adding this, the permeation rate can be increased. In other words, as the amine component (Ill) increases, the oxygen permeation rate increases5.On the other hand, the selectivity decreases, but the membrane properties can be easily controlled by changing the addition of the amine component (Ill), and the oxygen/nitrogen selection It is easy to find the optimal balance between performance and oxygen permeability.

The amount of the amine component (Ill) depends on the type of amine component (I), the type of polyinsyanate used, and the required film properties, but it is usually 4% of the total amine component.
5 moles or less, preferably 40 moles or less, but still 5 moles or more, preferably 10 moles or more of the total amine component.

The polyisocyanate component used in the present invention has at least two incyanate groups in the molecule. For example, examples of the aromatic polyisocyanate include a compound represented by the following formula (compound represented by In, the following formula bond) and a compound represented by the following formula iVl, specifically, 4.4'
-diphenylmethane diisocyanate, 4,4'-diphenyl needle diisocyanate, 3,4'-diphenyl ether diisocyanate, toluylene diisocyanate, and phenylene diisocyanate. Further, examples of the alicyclic polyisocyanate include inphorone diisocyanate and cyclohexyl diisocyanate, and examples of the aliphatic polyisocyanate include hexamethylene diisocyanate and tetramethylene diisocyanate.

Among these, aromatic polyisocyanates having high reactivity with diamine components are preferred, and aromatic diincyanates are preferred, and compounds represented by the formula (Shu), especially 4.4
'-Diphenylmethane incyanate, 4,4'-diphenyl ether diisocyanate, and 3,4'-diphenyl ether diisocyanate are preferred because of their well-balanced transmission properties.

Therefore, as a preferable configuration for the subject of the present invention, the following formula (VIl&(2)...(■)-N-(IH2
0H2-N-0-N-I mo-N-0-...song (■
) 0H1 ((1M) 10 (■)) is 0.45 or less.

The membrane of the present invention can be produced by polymerizing the diamine component and polyincyanate component in a solvent to form a polymer solution, and then casting it onto a flat plate such as a glass plate to remove the solvent, or by coating it on a porous support. Although it can also be obtained by removing the solvent by removing the solvent, the unique feature of the composition of the uninvented membrane is that polymerization and thin film formation can be carried out simultaneously on the porous support.

1- That is, (1) On the porous support, - firstly, the diamine component ft is applied, and then the polyincyanate component ft is applied.
A solution having a small amount of water and capable of forming an interface with the above solution is applied and brought into contact with the solution, and then the porous 1
(2) Reverse the order of application of the above 2 m solution to form a layer Ii film on the support.

The diamine component #4 is the diamine component that is mixed with ethanol, inpropyl alcohol, methyl seronluc,
-A can be easily obtained by dissolving it in a solvent such as dioxane, ethylene glycol, diethylene glycol, glycerin, or triethylene glycol, or a mixed solvent of two or more of these. The 4 degree of diamine component is 1 (j ppm to 10 wt %, preferably
uppm to 5 wt%.

On the other hand, the polyisocyanate component solution contains the compound n-
Hexane, n-hebutane, n-octane, cyclohexane, n-decane, n-tetradecane, hequinadecene, benzene, toluene, medium silane, carbon tetrachloride or truffle p
Prepared by dissolving in #IA4 such as Rotriclo C1-f-tyrene or a mixed solvent of two or more of these,
Its concentration is between 1 ppm and 10 ft, preferably between 50 ppm and 5 wt.

Since it is necessary for both compounds to cause a reaction at the interface, the selection of solvents for each compound should be made in a combination that has an interface-forming property suitable for the reaction. However, even if there is some degree of mutual compatibility between the two, such a combination is acceptable as long as an interface is actually formed and an interfacial reaction is achieved.

The porous support supports the selectively permeable 4J membrane and provides strong r'c
There is no particular limitation as long as it is something that can be reinforced and hung.

As a base material for such a support, glass porous material, sintered gold 4
s Ceramics, etc.: 11 (includes popular polymers such as Isogashina, cellulose ester, polystyrene, vinyl butyral, polysulfone, polyvinyl chloride, polyester, polyacrylonitrile + 14 lyamide, etc.).

Among them, boria and sulfone films exhibit particularly excellent performance as the base material of the present invention, and polyacrylonitrile and:! The f-aromatic boria ξ-do is also valid. The manufacturing method of the polysulfone porous 'i base material is described in the U.S. Salt Water Bureau report (03
It is also described in W a, eport) 4359.

In general, the size of the pores on the surface of the shrine is approximately 50~
1(J(300A, preferably(Eng.100-1(IIJU)
Those between A and A are preferable, but the surface pore size varies between 50A and IU11θOA depending on the purpose of the final membrane. Uro. These substrates can be used in either symmetrical structure or asymmetrical structure, but it is preferable to use a non-two-part structure. is 20 to 3000 seconds, more preferably 50 to
A paper of 1000 pieces is used. If the air permeability is less than 20 seconds, the composite membrane obtained using it is likely to have defects (the selectivity tends to decrease). The air permeability will be low.

In addition, the size of the pores of the base material is 1 μm as the maximum pore diameter.
Hereinafter, it is preferably 0.5 μm or less.

The shape of the support may vary depending on the desired shape of 4 pA, and specific examples include flat plate, tube, and hollow fiber shapes. The thickness of the support is not limited, but is usually 10μm to 10R1, preferably 504μm.
m~10U 0μm.

The method of applying each solution to the support varies depending on the shape of the porous support and the type of solvent used, but typical methods include the dipping method, the --/l/fuf ink method,
Examples include a wick coach ink method and a spray coating method.

For example, when the porous support is in the form of a flat film, the method for forming the film is to dip the support into one solution, take it out of the solution, drain the liquid, and then form an interface with the solution. One method is to form an interface between the two solutions on the support by immersing it in the other solution where the support is available, thereby forming a film through an interfacial reaction. Immersion can be done by patch method or continuous method.1
When the support is a hollow fiber, as in the case of a flat membrane, it is immersed in the reaction solution in order so that the reaction solution does not enter the inside of the hollow fiber to form a W on the outside of the hollow fiber support. Alternatively, a membrane can be formed by sequentially flowing the reaction solution inside the hollow fiber support. This method of forming a single layer on the inner surface of the hollow fibers is advantageous in terms of membrane handling, since an extremely thin membrane with a small mechanical angle of 111 degrees can be handled without touching the membrane after it has been formed.

After film formation, unreacted compounds or solvents can be washed with low-boiling fish skin/or low-viscosity π solvent or water. Moreover, heat treatment can also be performed to complete the reaction. The temperature JX is carried out at a temperature that does not cause deformation of the support or membrane, usually in the range of 50 to 200°C, and preferably for a time of 1 to 120 minutes.

The performance of the roasted membrane is as described above as the inherent performance of the membrane, and the selectivity of I'll element/desired element is at least 3.
．． 5, preferably 3.7 or more, with an enzyme permeability coefficient of at least 5
l-concentrated cml (g 1 preferably 7 X IU
” cc(STP) ・cpr/ crIt-sec
・More than cmHg, b.

Film thickness i10.2μm11 for practical use as a 4-layer membrane
Hereinafter, preferably U, 1 μm or less is used. The membrane of the present invention can be used for layer separation of various gases by utilizing its excellent selectivity and permeability.

I Samurai has a relatively high 17J degree #1 in air separation
．． It can be used as a treatment device for people with respiratory illnesses, in devices to improve the combustion efficiency of combustion engines, etc., and for other industrial applications, such as hydrogen and hydrogen. Separation of backbone monoxide It is possible to efficiently concentrate helium from natural gas and to separate sulfur dioxide or carbon dioxide from exhaust gas.

Furthermore, the membrane of the present invention can also be used as a pervaporation membrane for dividing an ethanol aqueous system. It's not something you can do.

In the examples, "part" represents the amount of IL.

Example 1 Polyethylene terefu clay)'A non-dl cloth (basis weight m18
Polysulfone (ude
1350 (1) Section 15, N-methylpyrrolidone 85
A solution consisting of S% was cast to a thickness of 300 μm, and the polysulfone layer was immediately gelled in a water bath at room temperature to obtain a nonwoven polysulfone membrane with porous injection.

Separately, bis(3-7minoprovir)hexamethyl) I
J siloxane (compound of formula (1+ -2) 70 mol% BL-hy3- (2-7 minoethyl,/propyl)
Amine component consisting of 30 moles of torus (trimethylsiloxy) (1,1 part ethylene glycol 99.9
A bath solution was prepared in which the nonwoven fabric-reinforced porsulfone support membrane was immersed for 10 minutes. After pulling it up, the liquid was drained using a rubber roller, and it was immersed in a hexadecene solution of 4,4'-diphenylmethane diisocyanate (U, υ5 wt4) for 3 minutes and reacted.

A composite membrane was obtained by immersing it in water, rinsing it with water, and then air-drying it.

The performance of this membrane was measured using a gas permeability measuring device using gas shimatogelahui, using the method of sending pure oxygen and pure nitrogen to the thin membrane side and crushing the permeated side with helium.

The results are shown in Table 1.

Implementation 912-3 Comparison 11-3 Izunemo amine component had the composition shown in Table 1 (+, 1
A wt% solution of 2+ lene glycol was prepared in the same manner as in Example 1, using a compound shown in Table 1 as the incyanate component, and Q5 wt hexademane lip fluid, and its performance was determined.

The results are shown in Cloth-1.

Example 4 Polysulfone (udel 3500) 20 its
A solution consisting of 57 parts of N-methylpyrrolidone, 3 parts of lithium chloride, and 20jf5 of 2-methoxyethanol was discharged through an annular slit using water as the core, and the solution was allowed to penetrate into the water.
Outer diameter 900 μm 1 inner diameter 60
A hollow fiber membrane module was obtained by solidifying 44 parts of the polysulfone hollow fiber support having a diameter of 0 .mu.n1 on a polycarbonate pipe with an image binder.

Separately, an amine component consisting of 75 mol% of 1,000-samethyltrisiloxane and 25 mol% of 3-(2-7minoethylaminoprobyl)tris(trimethylsiloxy)silane was added to bis(3-7minoprovil) by 0.1 wt%. The solution was dissolved in ethylene glycol m solution at a concentration of , introduced into the inside of the hollow support, and after the liquid was drained, a 25 υppm octadecene solution of 4,4'-diphenyl ether diisocyanate was also sent inside. After transferring for 3 minutes + tl, a hexane solution was poured into the inner pocket 1 for washing, and the inner pocket 1 was washed once, and then thoroughly air-dried to obtain a hollow fiber composite membrane.

Like our flat membrane with permeability, measured at equal pressure L? ,
: Toc, the oxygen permeability (KO2) is 24X]0'c
c/7-sec ・cmHg, selection 1% (KO2
7KN2) was 3.8.

Claims (1)

[Claims] 1. A compound represented by the following formula (I) and the following formula (II)
Compounds represented by ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・( I
) (n=1, 2 or 3) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ・・・・・・(II) A mixture with the compound represented by formula (II) accounting for 45 mol% of the total A gas separation membrane mainly formed from the following amine components and polyisocyanate components. 2. The polyisocyanate component according to claim 1, wherein the polyisocyanate component is selected from 4,4'-diphenylmethane diisocyanate, 4,4''-diphenyl ether diisocyanate and 3,4'-diphenyl ether diisocyanate. Gas separation membrane.