JPS586206A - Production of plyimide semipermeable membrane - Google Patents

Abstract

PURPOSE:To produce a semipermeable membrane which has high liquid permeability and can be used effectively for sepn. of gases as well by adding arom. hydrocarbons or their deriv. to a dope soln. prepd. by dissolving arom. polyimide in a phenolic solvent and filming the soln. CONSTITUTION:The arom. polyimide such as the one expressed by the fomula obtd. by condensation polymn. reaction and imidating reaction of a biphenyl tetracarboxylic acid component and an arom. diamine component is dissolved in a solvent such as phenol halide, and further, benzene, toluene, xylene, naphthalene, chlorobenzene, chloronaphthalene, anisole, acetophenone, nitrobenzene, dimethyl phthalate, etc. are added as swelling agents, and with the resultant soln. as a dope soln., it is made into a film, whereby a polyimide film is obtained. This semipermeable membrane has particularly high water permeability, and is used for selective sepn. of gaseous mixtures of H2 and CO, O2 and N2, H2 and N2, CO2 and CH4, etc. In the formula, R is the bivalent residual groups excluding the amino groups of arom. diamine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a Bolioid semipermeable membrane OII.

Conventionally, cellulose acetate-based semipermeable membranes have been well known as semipermeable membranes, and their manufacturing methods have been well known.

A dope solution is prepared by dissolving cellulose acetate in an acetone-formamide mixed solvent or a solution of a metal salt dissolved in the solvent, the O dope solution is formed into a thin film, and the solvent is poured from one side of the thin film. There is a known method of manufacturing a semipermeable membrane by partially evaporating the membrane and then immersing the membrane in cold water.

However, cellulose acetate-based semipermeable membranes are heat resistant.

Chemical resistance, microbial resistance, pH resistance, compaction resistance, chlorine resistance, etc. are not satisfactory as they show insufficient properties.

Therefore, aromatic boria-based semipermeable membranes, aromatic polyimide semipermeable membranes, etc. have been proposed as semipermeable membranes with good heat resistance, chemical resistance, and compaction resistance. In particular, the aromatic wheel polyind semipermeable membrane is expected to be a heat-resistant semipermeable membrane with excellent chemical resistance, mechanical properties, etc.

However, as a known method for producing a semipermeable semipermeable membrane, first, a solution of polyazuzucic acid obtained by a polycondensation reaction of tetracarboxylic dianhydride and an aromatic diamine is prepared, and then A method of forming a liquid thin film with a liquid, coagulating the thin film in a coagulating liquid, and finally imidizing the semipermeable film of polyanthic acid to produce a semipermeable polyester film, or While forming a thin film with the solution, the imidization is partially stopped, the thin film is coagulated in a coagulating solution, and finally the semipermeable polyanthuic acid-imide membrane is heated to complete the imidization. A method for manufacturing a polyimide semipermeable membrane, further comprising coagulating a liquid thin film of polyazuclic acid while imidizing it in a coagulation solution containing an ionizing agent, and heating the obtained coagulated membrane. The method is known round. In a known method for manufacturing a semipermeable membrane,
Because it requires the operations of film formation from a solution of boric acid, coagulation, and imidization, it is a complex method that requires very good control.9Polyindo semipermeable membrane with stable quality and excellent performance It has the disadvantage that it cannot be stably produced.

In addition, the polyindo semipermeable membrane obtained by the above-mentioned known method is
Performances such as water transport overspeed, Il, and salt rejection rate, which will be described later, were also not particularly satisfactory.

The present inventors have discovered that an aromatic polyimide semipermeable membrane can be produced through very simple steps and operations, and that an aromatic polyimide semipermeable membrane with excellent performance can be obtained. As a result of intensive research on the method, it was discovered that a nine-aromatic polyimide obtained from a biphenylnato dicarboxylic acid component and an aromatic diane component can be dissolved in a phenolic solvent, and the composition of the solution can be used for film formation. By using it as a dope.

They discovered that the drawbacks of the above-mentioned known methods could be solved all at once, and have already filed a patent application for the invention in Japanese Patent Application No. 111816-216 (1-i).

That is, the invention relates to 1 mi or 2 or more types of polyimides having 10% or more of repeating units represented by the general formula (where Il is a divalent residue excluding the amine group of aromatic cyaine). However, by using a polyimide composition dissolved in a molten liquid of a phenolic compound, a liquid thin film of the polyimide composition is formed, and then the thin film is immersed in a coagulating liquid to be solidified. This is a method for manufacturing a polyind semipermeable membrane in terms of percentage.

The method of the invention described above does not require any imidization process during or after film formation, which is required in known methods that use a solution of poly-7sicic acid as a dope solution. The operation is extremely simple,
The feature is that these operations can be controlled stably.

The polyimide semipermeable membrane obtained by the method of the above-mentioned invention is superior in terms of water supply continuity, salt rejection rate, and compaction resistance compared to the polyimide semipermeable membrane obtained by conventionally known methods. In addition, heat resistance, chemical resistance, mechanical properties, etc. are better than those of conventionally known O semipermeable membranes.

Furthermore, in the known method of using boria-based citric acid OS solution as a dope solution, the storage stability of the O-doped 11IO was poor, but in the method of the invention described above, very stable polyimide and 7-Nol-based Since the composition with the compound is used as a dope.

Another advantage is that the composition has excellent storage stability.

The inventors of the present invention conducted various studies to further improve the above-mentioned invention. By forming a film with a certain amount of
When a semipermeable membrane is manufactured, the semipermeable membrane exhibits significantly superior liquid permeation performance compared to the semipermeable membrane manufactured by the above-mentioned method of the invention, and can also be advantageously used for gas separation. They found that it is possible to do this and completed the present invention.

That is, the present invention.

(1) One or more of the above polyimides
~30 parts by weight; (b) 60 to 95 parts by weight of a phenolic solvent; and (c) 2 parts of a swelling agent made of an aromatic hydrocarbon or a derivative thereof that does not dissolve the above polyimide at 50°C by more than S weight%. ~40 parts by weight.

A method for producing a polyimide semipermeable membrane, which comprises forming a liquid thin film of the polyimide composition using a solution of the polyimide composition containing the polyimide composition, and then immersing the thin film in a coagulating liquid to coagulate it. It consists of .

The polyimide used in the present invention is represented by the general formula 0 (where R is the divalent residue of the aromatic diamine represented by the general formula 11. Aromatic polyindo having repeating units in the polymer main chain at a ratio of 90% or more, preferably 95% or more of the total structural units, and is soluble in a melt of a phenolic compound. It is.

The above aromatic polyimide is 3.3', 4.4'-
biphenyltetracarboxylic acid component, 2,3.3',
a biphenyltetracarboxylic acid component such as a 4'-biphenyltetracarboxylic acid component, and general formula 11. N-R-NO
It is obtained by a polycondensation reaction and an imidization reaction (indocyclization reaction) with an aromatic diamine component represented by . The manufacturing method and manufacturing conditions are disclosed in Japanese Unexamined Patent Publication No. 56-
Since it is described in Japanese Patent No. 21602, detailed description of ζζ will not be given.

The phenolic solvent used in the method of the present invention includes:
(with a melting point of about 100°C or less, preferably 80°C or less),
Its boiling point is approximately 300°C or less at normal pressure.

Preferably, phenolic compounds having a temperature of 280° C. or lower are preferred.2 For example, monohydric phenols such as phenol, o-, m- or p-cresol, 3,5-xylenol, carvacrol, and thymol.

Alternatively, a halogenated phenol obtained by substituting the water volume of the -valent phenol with a halogen can be preferably mentioned.

411, the halogenated phenol has the general formula (round shape, in the above general formula, v R1 is hydrogen or an alkyl group having 1 to 3 carbon atoms, and x is a halogen atom)
A halogenated phenol compound having a melting point of about 100°C or less, preferably 80°C or less, and a boiling point of about 300°C or less, preferably 280°C or less at normal pressure has a low solubility in polyimide. It is optimal because it is excellent.

In the method of the present invention, as the halogenated phenol, 2
For example, 3-chlorophenol (metachlorophenol), 4-chlorophenol (halachlorphenol),
3-bromophenol, 4-fromphenol, 2-1
0-4-hydroxytoluene, 2-chloro-5-hydroxytoluene, 3-chloro-6-hydroxytoluene, 4-chloro-2-hydroxytoluene, 2-10mu-
4-Hydroxytoluene! -fromu-5-hydroxytoluene, 3-bromo-5-hydroxytoluene,
3-7' Romo-6-hydroxytoluene.

Examples include 4-bromo-2-hydroxytoluene.

In the method of the present invention, the polyimide composition further contains 50
A swelling agent consisting of an aromatic hydrocarbon 4 or a derivative thereof that does not dissolve more than 5 weight of the polyimide at ℃ is included. A compound that dissolves more than 5 weight of the polyimide at 50°C is not suitable for use in the present invention because it cannot provide the excellent groove permeability exhibited by the semipermeable membrane obtained by the method of the present invention. Typical examples of agents *a consisting of aromatic hydrocarbons or derivatives thereof that can
It is difficult to mention benzene compounds having IK substituents. Regarding the type and number of substituents.

As long as the substituted benzene compound exists stably, does not substantially react with the phenolic solvent and the polyimide compound, and has sufficient compatibility with the mixture thereof for practical use), especially There is no @i.

Specific examples of substituents include lower alkyl groups (carbon numbers 1 to .), lower alkoxy groups (carbon numbers 1 to group, a phenyl group having a substituent.

Examples include a phenoxy group and a phenoxy group having a substituent. 7-talin, and-2-seno, 2-methylnaphthalene for use in the present invention.

Aromatic hydrocarbons such as diphenyl and p-terphenyl,
Coolbenzene, 0-dichlorobenzene, 1,2.
4-) Halogenated aromatic hydrocarbons such as lychlorobenzene and α-chlornaphthalene, anisole, EO aromatic ethers such as diphenyl ether, arytophenone, l,
Mention may be made of aromatic ketones such as 2-benzanthraquinone, nitrobenzene, etc. (D nitrated aromatic hydrogen esters, aromatic carboxylic acid esters such as dimethyl phthalate, etc.), which are used as swelling agents in the method of the present invention. It is suitable to use koji 6゜9, benzene compounds having IIK substituents, such as phenol, 4-chlorophenol, 2-chlorophenol, 3-/lorphenol, 3-7'romophenol, 4-bromophenol, 2-chloro-4-hydroxytoluene.

2-chloro-5-hydroxytoluene, B-/amil-
6-Hydroxytoluene, 4-chloro-2-hydroxytoluene, 2--j rom-4- and doroΦcitoluene, 2-
Brome-5-human xytoluene/l 3-from-5
Compounds like -hydroxytoluene, 3-bromo-6-hydroxytoluene, and 4-7'romo-3-hydroxytoluene! It is possible to dissolve more than 5% of the above-mentioned polyimide in Ioc, and these do not sufficiently exhibit the swelling effect required by the method of the present invention, and therefore, the semipermeable membrane cannot be obtained by the method of the present invention. It cannot be used as a swelling agent in the process of the present invention because it cannot provide the characteristically excellent permeation performance.

For example, non-aromatic hydrocarbons such as formamide, dichloromethane, chloroform, cyclohexanone, octatool, etc. and their haze conductors cannot be used as swelling agents because they do not exhibit a swelling effect in real INK.

Used in the method of the present invention (Xun Polyindo 2 (b)
The amount of each component contained in the liquid polyindo composition consisting of a phenolic solvent and (C) a swelling agent, that is, Dogue's solution, is from e(1)'' to 30 parts by weight (preferably 11 s).
~zs 1 part)! (b) 95-go parts by weight (preferably 9!-5o parts by weight): (e) It is necessary that the relative ratio is within the range of 2-40 parts by weight (preferably 5-30 parts by weight). However, a composition having a relative ratio outside this range is not preferred because it is difficult to obtain a semipermeable membrane having excellent permeability as the object of the present invention.

As described above, the present invention provides a method for manufacturing a semipermeable membrane using a polyimide composition prepared by adding a specific amount of a swelling agent to polyimide and a phenolic solvent as a dope solution. The semi-permeable membrane obtained by the production method of the invention has excellent heat resistance, chemical resistance, mechanical properties, etc. of the semi-permeable membrane produced using a polyimide composition made of polyamide ζ and a phenolic solvent as a dope liquid. In addition to maintaining the same level of water permeability, there is a significant improvement in water permeability. The semipermeable membrane obtained by the production method of the present invention is also suitable for use in selectively separating a desired gas from a mixture of various gases.

Examples of combinations of gases constituting such a gas mixture include hydrogen and carbon monoxide, oxygen and nitrogen, hydrogen and nitrogen, carbon dioxide and methane, helium and methane, and helium and nitrogen. I can do it.

When carrying out the method of the present invention, when phenolic IIFIII4 is used as a reaction solvent for the polyimide synthesis reaction, a phenolic solvent with a chemical composition of 2 and a viscosity of 2 is added to the reaction mixture as necessary. After adjusting the strength, add a swelling agent and mix uniformly.

Used as a polyimide composition for film formation. However, in the case where polyimide is isolated as a powder in the production of polyimide, the polyimide composition used in the present invention is prepared by mixing and dispersing polyimide powder in a melt of a phenolic compound (solvent). Then, the mixed dispersion liquid is sufficiently heated to completely dissolve the polyimide powder, and then a swelling agent is added and mixed uniformly to prepare a film-forming dope liquid.

In the method of the present invention, a composition containing two or more kinds of polyimides represented by the above general formula can be used as the polyimide composition, and furthermore, a composition containing two or more kinds of polyimides represented by the above general formula and other aromatic polyimides can be used. It is also possible to use a composition containing polyimide.

In particular, in the method of the present invention, the logarithmic viscosity is 0.8 to 7.
Special KO39-4 high molecular weight polyimide represented by the above general formula and a logarithmic viscosity of 0.2 or more (including polyimide shown by the above general formula or other low molecular weight aromatic polyimide).

A polyimide composition containing K11ll in a melt of a phenolic compound, the above-mentioned high molecular weight polyimide (6)
The weight ratio (mu/l) of and low molecular weight polyimide (to) is 0
．． 5-20. It is preferable to manufacture a semipermeable membrane using a polyimide composition having a specific KO,I of ~1m because it has excellent water permeability and allows the manufacture of a semipermeable membrane. As the low molecular weight polyimide (2), in addition to the low molecular weight O polyimide represented by the general formula described above, other low molecular weight aromatic polyimides such as 3.3', 4
．． Examples of the polyimide include a polyimide obtained from a 4'-benzophenone tetracarboxylic acid component and an aromatic cyanine component, which has a relatively low molecular weight and can be dissolved in a melt of a hexaphenol compound.

As mentioned above, a mulberry polyimide composition containing two or more types of polyimide can be easily prepared by mixing the liquid products of each polyimide composition. It may also be prepared by adding another polyimide (powder, etc.) to the product and making it scale.

In the method of the invention, the polyimide composition is.

It is preferred that the chain degree of all the polyindos contained is greater than or equal to 5% by weight, particularly from 6 to 30% by weight, and more preferably from 8 to 50% by weight, based on the total composition. In addition, the polyimide composition has a film forming temperature of 0 to 120°C, and a lI# of 5 to 120°C.
Within the range of 100T:Q:).

The rotational viscosity is at least 30 centipoise or higher.
100 to 100,000 poise, further soo to 100
It becomes a uniform liquid composition of about 0.00 poise.

It is preferable to use it as a dope solution for film formation.

In the method of the present invention, the above-mentioned polyimide composition is heated if necessary and used as a dope solution for film formation, and the dope solution of the polyimide composition is used to form a liquid thin film (for example, a flat film shape, a hollow fiber shape). , a tubular thin film) is then formed.
The thin film is immersed in a coagulating liquid and coagulated to produce a polyindo semipermeable membrane.

In the method of the present invention, it is preferable to use a suitable filter to remove solids from the liquid polyimide composition or to sufficiently defoam it to obtain a dope solution for film formation.

A method for forming a liquid thin film from a dope solution of a polyimide composition can be carried out by a method similar to the conventionally known casting film forming method. A method in which the dope solution of the polyimide composition is cast onto the surface of the roll and then a doctor blade is used to form a liquid thin film of uniform thickness. The polyimide composition was then extruded into a thin film form from a tape die and rolled onto the roll surface. A continuous film forming method such as continuous film formation can be adopted. In the Honjitsu 9110 method, the temperature of the dope solution of the polyimide composition during film formation is determined by the relationship between the rotational viscosity of the polyimide composition and temperature. Should be, but preferably O-1
20℃, especially! The temperature range is preferably about 1-Zoo°C, and the optimum temperature range is 10 to 50°C.

Further, the thickness of the liquid thin film formed as described above is preferably 10 to 500 microns, particularly 20 to 200 microns.

The liquid thin film formed by K as described above can be obtained by applying a phenolic solvent and a swelling agent to one side of the liquid thin film while forming the liquid thin film, or after forming the liquid thin film. O is suitable because, when partially evaporated, an asymmetrical thin film is effectively formed through primary solidification.

The method of partially evaporating the 7-enol solvent, etc. from one side of a liquid thin film is to evaporate a portion of the 7-enol solvent, etc. from one side of the liquid thin film on the lithographic plate or roll circumferential surface.
Gas at 0 to 100°C, especially 5 to 90°C, at least once
A preferred method is to spray for more than a second, especially for 5 seconds to 30 minutes, and for KIO seconds to 20 minutes, but the liquid thin film on the periphery of the plano plate or roll is heated to reduce the concentration to 2% in a reduced pressure atmosphere for at least several seconds. 10 seconds to 30 minutes, then another 30 seconds to 20 minutes
A method of leaving it for a minute may also be used.

In the method of the present invention, the coagulating liquid used to coagulate the polyimide liquid thin film formed as described above may be any liquid that is freely mixed with the phenolic solvent and has compatibility. 2 For example, lower alcohols such as methanol, ethanol, propatool, acetone,
Ketones such as methyl ethyl ketone, diethyl ketone, methyl propyl ketone, tetrahydrofuran, dioxane.

Ethers such as ethylene glycol monomethyl ether, dimethyl acedodate, dimethyl formamide, dimethyl sulfokylede, etc.
Examples include liquid mixtures of water and the alcohols, ketones, ethers, and amides. %, as a coagulating liquid, the mixing ratio (relative to the unit amount of water used) is 0.1-
10. In particular, water and alcohols, water and ethers, water and ketones, or water and amides and O
A mixed solution is preferred.

What is the method of coagulating a liquid thin film with the above-mentioned coagulating liquid?

Any known method may be used to form a thin film.

Same as the base material on which the thin film is formed (cast).

Said 0III! It is preferable to immerse in a solid liquid, and the temperature of the coagulating liquid is lso℃ or less, especially -10 to 30℃
, more preferably about -5 to 20°C, and furthermore, the temperature of the thin film immersed in the coagulation liquid is 60°C or less, especially θ to 50°C.
It is preferable that the temperature is about ℃. The time for which the thin film is immersed in the coagulation solution as described above depends on the type of polyamide composition.

It depends on the type of coagulation liquid and other conditions.

Generally, the time may be about 0.1 to 20 hours, or about 0.5 to 10 hours.

The membrane solidified from the liquid thin film as described above already has a porous layer that has sufficient properties as a semipermeable membrane, but it is also coated with methyl alcohol, ethyl alcohol, flobyl alcohol, etc. KO for about 0.5-10 hours at 50°C in lower alcohols, and/or about 0.5-10 hours at 0-50°C in ion-exchanged water.
It is preferable to carry out a post-treatment in which the remaining phenolic solvent and the like in the coagulated film are washed out by immersion for a period of time.

If necessary, the aforementioned coagulated film was heated at 5o-150°C.

Particularly: 1 to 12
Thermogeography may be performed by immersion for 0 minutes, especially for 5 to 60 minutes. Generally, when the above-mentioned heat treatment with hot water is performed, the salt rejection rate of the resulting semipermeable membrane is improved.

Thermal stability is also improved.

Next, reference examples (polyimide synthesis examples), Example II, and comparative examples will be shown.

In the Examples and Comparative Examples, the water transport speed Fl was determined by equipping a reverse osmosis membrane testing device with a semipermeable membrane and supplying a 0.1 weight x concentrated sodium chloride aqueous solution.

The water transport overrate when performing reverse osmosis operation at 20°C under a pressure of 40 (/-) is expressed in units -/II/·day.

Eliminate salt in the reverse osmosis operation described above.

The sodium chloride rejection rate is calculated from the ratio of the sodium chloride concentration C in the permeated water (C/Co) to the IJum paleness coefficient (C/Co) using the following formula.

Sub-(1,--) The imidization rate is considered to be 100% when all bonding moieties (bonding moieties between monomers) that can form imide bonds in the molecular chain form imide bonds, and when there is no ind bond at all (for example, amide bonds), the imidization rate is 100%. - When there is only an acid bond), the imidization rate is 0%. In other words, the imidization rate is the percentage of imide bonds present in all the bonds between monomers of the polyelectrode polymer. Imidization rate measurement company.

This was done using infrared absorption spectroscopy.

[Reference example 1-2 (polyimide production by two-stage method)] 1st
40 mmol of the tetracarboxylic dianhydride shown in the table and 40 mmol of the aromatic diamine shown in Table 1 together with dimethylacedoide 180F.

It was placed in a nine-separable flask equipped with a stirrer and a nitrogen gas inlet tube, and wL elementary gas was being passed through it.

Polymerization temperature of 20°C and polymerization times shown in Table 1.

After condensation polymerization to produce polyamic acid, the polymerization solution was cooled to 10°C or lower, and dimethylacedoide 1802. Acetic anhydride! ! 4G 19 moles.

After adding 240i mol of pyridine and stirring thoroughly to make the polymerization solution uniform, the temperature of the polymerization solution was gradually raised to about 3o''cK and held for about 20 minutes to precipitate polyimide from the polymerization solution in powder form. , furthermore, the polymerization solution is 70~8
Heat o'cK and maintain at that temperature for 30 minutes or more to complete imidization.

The polymerization solution containing the polyind powder obtained as described above was poured into a large amount of methanol.

The polyimide powder was collected by filtration, thoroughly washed with methanol, and then dried under reduced pressure to obtain a polyimide powder.

The bolicarbonate powder has an imidization rate and a logarithmic viscosity (concentration: 0.5 f/) OO-solvent, solvent; I(
2 Chlorphenol and Ortskruphenol and 043
Mixed liquid with a volume ratio of 110 m constant temperature s so °C> m.

It was as shown in Table 1.

[Reference Example 3 (Manufacture of polyimide by one-stage method)] To the same separable 72 Sco as in Reference Example 1, s and s' were added.

4.4'-biphenyltetracarboxylic dianhydride 2゜electromol, 4.4'-diammediphenyl ether 2
0Z9 -Chlorphenol) was introduced at 80F, and the two reaction solutions were heated from room temperature to 180C in a trench for 40 minutes while flowing nitrogen gas, and then the reaction solutions were kept at 180K for 4 hours to reduce the condensation. Polymerization and indification were carried out in one stage to obtain a viscous polyimide solution. Table 1 shows the imidization rate and logarithmic viscosity of polyimide in the polyimide solution.

[Reference Example 4 (Manufacture of polyimide by one-stage method)] In a separable flask similar to that used in Reference Example 1, 3.3
',4.4'-Biphenyltetracarboxylic dianhydride 2
0 mol, 4.4'-diaonodiphenyl ether tS < rimole, 4 rimole of 2,6-diamitubiridine, and 7 mol of hivacrol were added to the solution, and the reaction solution was brought to room temperature while flowing nitrogen gas. From 1110C1 to 4
The temperature was raised for 0 minutes, and the reaction solution was further maintained at 180° C. for 6 hours to carry out polycondensation and conversion into I and D in one step to obtain a viscous polyimide solution. Polyimide in polyindo solution.

The imidization rate and logarithmic viscosity are shown in Table 1.

The xllo monomer OIK and abbreviations indicate the following compounds, respectively.

8-BPDA; L3'lL4'-biphenyltetracarboxylic dianhydride DADI: 4,4'-cya-based nodiphenyl ether m-DADI; metathia Z nodiphenyl sulfone (s
, s'-diaminodiphenylsulfone) 2,6-DAP; 2,6-dia Z nobilidine
1 Table 1 B-BPDA DADIC li8! I
ss%sha 1.102 Same as above m-DADI pi
ii)1. So fdJI O. II3 f
dJI on DADW 1.7
Q [Examples 1 to 3] 10f of the 9-bolyide powder obtained in Reference Example 1, 80f of parachlorophenol, and the swelling agent iot shown in Table 2 were placed in a separable flask equipped with a stirrer, and the mixture was heated to 80~
It was dissolved at 90° C., and the solution was filtered and purified using a pressure filter. The filter of the filter is composed of two pieces of filter paper (N126) with a retained particle size of 3μ, a 400 Messier wire mesh, and a 100 Messier gourd wire mesh.

Each polyimide solution purified by K as described above is heated, and if necessary, the pressure is reduced to sufficiently degas the polyimide solution, and then the polyimide solution is used as a dope solution for film formation to prepare clean glass. A liquid thin film with a uniform thickness of about 100μ is formed by casting on a plate at room temperature using a doctor blade, and hot air at 6G°C is applied to the surface of the thin film using a hot air dryer for 30 minutes.
The thin film was partially dried by spraying for only seconds, and finally, the partially dried liquid thin film was immersed in a water-methanol coagulation solution (water/methanol wkl, temperature: about 0 to 3°C). The immersion was continued for about 4 hours to solidify the film. Thereafter, the solidified round thin membrane was immersed in methanol for 4 hours or more, and then in ion-exchanged water for 4 hours or more to remove residual solvent to obtain a semipermeable membrane.

[Example 4] Nine polyide powder obtained in Reference Example 2! of and parachlorophenol 70F and nitrobenzene 10F were placed in a separable flask equipped with a stirrer, and the subsequent operations were the same as in Examples 1 to 3 (except for blowing hot air at 60°C onto the thin film surface). was carried out for 1 minute instead of 30 seconds) to obtain a semipermeable membrane.

[Comparative Example 1] A semipermeable membrane was obtained by performing the same operation as in Examples 1 to 3 except that the same amount of parachlorophenol was added instead of the swelling agent.

[Comparative Example 2] A semipermeable membrane was obtained by carrying out the same operations as in Examples 1 to 3, except that the same amount of formide was used instead of the swelling agent.

[Comparative Example 3] Parachlor 7 instead of nitrobenzene (swelling agent)! !
A semipermeable membrane was obtained by performing the same operation as in Example 4 except that the same amount of Nor was added.

Table 2 shows the water transport rates and salt rejection rates of the semipermeable membranes obtained in Examples 1 to 4 and Comparative Examples 1 to 3.

Table 2 1 #10-Diquarbenzey 60 0
．． 1 0.45 94.82 Same as above Enylzur 60 0.5 0.64 82.43 Same as above Nitrobenzene 80 0.5 1.23
78.840 Example 2 Same as above 601.0 0.4
8 9 & IIn Example 1 Parachlorphenomyl 60
0.5 0.10 9:4.12 Same as above Formua Kendo 80 0.5 0.12 97.23
Reference example 2 Barak CI A/7 gnoh60 1.
0 0.0! i 98.5 [Example 5] Put 100 t of the polymerization solution obtained in Reference Example 3 into a separable flask, and add a lot of Schiff X Nylethe # (swelling agent) to it.
A homogeneous solution was obtained by adding and stirring at 90°C. This solution was then filtered in the same manner as in Examples 1 to 3,
A semipermeable membrane was obtained in the same manner.

[Example 6] A semipermeable membrane was obtained by carrying out the same operation as in Example 5, except that the polymerization solution used was replaced with the polymerization solution obtained in Reference Example 4.

[Comparative Example 4] A semipermeable membrane was obtained by performing the same operation as in Example 5 except that the same amount of parachlorophenol was added instead of the swelling agent.

[Comparative Example 5] A semipermeable membrane was obtained by carrying out the same operation as in Example 6 except that the same amount of parachlorophenol was added instead of the swelling agent.

Table 3 shows the water supply overrate and salt rejection rate of the semipermeable membranes obtained in Examples SS and Comparative Examples 4 and 5.

3rd Table 5 □ 3-power footrest 601 0.8172.1561-
4 Same as above @0 1 0.75 85.3 Comparative example
(Alternative substance) 4 Reference 3 Parachlorophenol 60
1 0.13 93. Os 1 Yu 4 Same as above
60 October 94.5 [Example 7] The semipermeable membrane obtained in Example 1 was immersed in methanol, then in n-hexane for a day and night, dried in air for about 2 hours, and further heated to GC at 100°C. Heat treatment was performed for about 2 hours.

The heat-treated semipermeable membrane was set in a stainless steel cell with a membrane area of 1465 mm, and 1 c of hydrogen gas was added to the cell at 14/c.
dK was introduced under pressure, and the rate at which hydrogen gas permeated through the membrane was measured using a flow meter.9. - Carbon oxide was measured in the same way.9. In addition, the measurement temperature is.

A constant temperature bath was used to maintain a constant pressure of 30''CK. From the obtained pressure measurements, the permeability and resolution were calculated according to the linear equation.

Through this measurement, the hydrogen O permeability was determined to be 1. I X 1G
-'-/-・sec・cxgHy, and the degree of separation is 13
The results were obtained.

Beautiful woman for patent Ube Industries Co., Ltd. Kanesha Agent: Patent attorney Takao Yanagawa

Claims (1)

[Claims] (1) Bolioid oxllt having 90% or more of the repeating units represented by the general formula (the wings are 9 divalent residues excluding the amino group of aromatic diamine) or 5 ~so parts by weight; Φ) 60 to 95 parts by weight of a phenolic solvent; and (c) a swelling agent made of an aromatic hydrocarbon or a derivative thereof that does not dissolve more than the weight of the O-boli compound at 50°C. 2 to 40 parts by weight. A method for producing a polyimide composition, comprising forming a liquid thin film of the polyimide composition using a solution of the polyimide composition containing the polyimide composition, and then immersing the thin film in a coagulating liquid to coagulate the polyimide composition. .