JPS60150806A - Preparation of polyimide hollow yarn membrane - Google Patents

Abstract

PURPOSE:To prepare a hollow yarn membrane having high permeating rate for H2 and high degree of separation of H2 from CO by prepd. a hollow yarn from a mixture of >=2 kinds of polyimide having different structure. CONSTITUTION:Polyimide unit A (Formula I ) consisting of biphenyl tetracarboxylic dianhydride and 4,4'-diaminophenyl ether and polyimide unit B (Formula II) consisting of biphenyl tetracarboxylic dianhydride and 3,5-diaminobenzoic acid are mixed in (90-75):(10-25)(A/B) proportion, and the polyimides mixture is dissolved in a phenolic compd. to obtain 12-15% concn., and a hollow yarn membrane is obtd. from the soln. The phenolic compd. to be used for the solvent is one having <=ca.100 deg.C m.p., and <=ca.300 deg.C b.p. under normal pressure, specifically, phenol, or cresol, but halogenated phenol is particularly preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyimide hollow fiber membrane for hydrogen-carbon dioxide separation.

More specifically, the present invention relates to a polyimide hollow fiber comprising biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether (Japanese Patent Application Laid-Open No. 57-167414
By adding a polyimide consisting of biphenyltetracarboxylic dianhydride and 3,5-diaminobenzoic acid to (see the above publication), the hydrogen permeation rate is high and the degree of hydrogen-carbon monoxide separation is high. The present invention was achieved by discovering that hollow fiber membranes can be manufactured.

That is, 1 the present invention substantially comprises the following formula with a repeating unit represented by .

The repeating unit represented by 0 0 is: (B)=90:10~7
Polyimide i composed of a ratio of 5:25 (molar ratio)
It is characterized in that it is dissolved in a thunol compound to form a dope solution with a concentration of 12 to 15, extruded through a hollow fiber nozzle, and coagulated in a coagulation bath made of a polar solvent. The present invention relates to a method for producing a polyimide hollow fiber membrane for hydrogen-carbon dioxide separation.

The polyimide hollow fiber membrane obtained by the method of the present invention is related to a method for producing a hollow fiber membrane having excellent chemical resistance and heat resistance, high hydrogen permeation rate, and high hydrogen-carbon monoxide separation performance. It is.

In addition, in this specification, what is imidization rate?

It is a value measured and calculated by infrared absorption spectrum analysis, and indicates the percentage (coefficient) of all bonds that can be imide bonds in the polymer chain of a polyimide polymer. .

In this invention, polyimide is a polymer having an imidization ratio of 90 or higher.

The polyimide used in this invention is generally composed of repeating units represented by the formula (~: (B)
=90:10-75:25C molar ratio) is suitable. (B)/(A)-10/90 (molar ratio) or less is undesirable because the hydrogen permeation rate is low;
(A) =25/75 (molar ratio) or more, the uniformity of the polymer solution becomes unstable and spinning becomes difficult. The hydrogen permeation performance of the obtained hollow fibers was also inconsistent and inappropriate.

Further, the dope solution used in this invention is a solution in which an aromatic polyimide composed of two repeating units represented by the above general formula in a specific ratio is dissolved in a solvent containing a phenolic compound as a main component, The concentration of aromatic polyimide in the dope is preferably 12 to 15 wt%. If the concentration is lower than this, the shape of the obtained hollow fiber membrane will be non-uniform.

can be used.

The aromatic polyimide has the following components: 3.3', 4.4'-biphenyltetracarboxylic acid component, 2,3.3', 4'
- By polymerization reaction and imidization reaction (imide cyclization reaction) from a biphenyltetracarboxylic acid component such as a biphenyltetracarboxylic acid component and 4゜4'-diaminodiphenyl ether and 1,3-diaminobenzoic acid as an aromatic diamine component. can get.

The method for producing the aromatic polyimide used in the method of this invention includes, for example, combining a biphenyltetracarboxylic acid component and an aromatic diamine component with N-methylpyrrolidone, pyridi>/, N,N-dimethylacetamide, N,N
-dimethylformamide.

Dissolve approximately equimolar amounts in an organic polar solvent such as dimethyl sulfoxide, tetramethylurea, phenol, or cresol, and store the solution at about 80°C or lower, especially at O~60. f, (may be used), tertiary amine compounds such as trimethylamine, triethylamine, pyridine, acetic anhydride,
Add an imidization accelerator such as thionyl chloride, carposi, i, or mido and imidize at 5 to 150°C, or sludge the polyamic acid solution to 100 to 300° C. without adding an imidization accelerator. °C, preferably 120-250 °C
A preferred method is to heat the polyimide to a polymer G imidization rate of 90% or more to precipitate and isolate a powdery aromatic polyimide.

As a method for producing aromatic polyimide, the logarithmic viscosity (30°C, 051i'/10
0m/! Add a large amount of acetone or alcohol to a polyamic acid solution with a solvent content of 0.5 or more to precipitate polyamic acid powder, or remove the solvent by evaporation from the polyamic acid solution. A precipitant or the like is added to precipitate and isolate the polyamic acid powder, and the polyamic acid powder is heated to 150 to 300°C and imidized until the imidization rate of the polymer is 90% or more to produce polyimide. An example of a method for producing is to add a nyltetracarboxylic acid component and an aromatic diamine to a melt of a phenolic compound at 120 to 4 oooC.
An aromatic polyimide can also be produced by polymerization and imidization in one stage, particularly at 150 to 300°C. This one
In the step method, the polyimide composition of polyimide and a phenolic compound that can be used in the method of this invention is
obtained directly.

This reaction mixture is optimal because it can be used as a dope solution for the IT hollow fiber system.

fd, 3 as the biphenyltetracarboxylic acid component used in each of the above-mentioned aromatic polyimide manufacturing methods.
．． 3', 4,4'-biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as 87BPDA), 2
, 39 4'-biphenyltetracarboxylic dianhydride is preferred, but 2.3.3', 4'- or 3. v
7-+, 4'-biphenyltetracarboxylic acid or 2.3.3S 4' = cleaved U 3.3', 4.4'
- Salts of biphenyltetracarboxylic acids or esterified derivatives thereof. The biphenyltetracarboxylic acid component may be a mixture of the above biphenyltetracarboxylic acids.

[, as a tetracarboxylic acid component, pyromellityl,
bis(3,4-dicarboxyphenyl)thioether,
butanetetracarboxylic acid or their acid anhydrides,
Tetracarboxylic acids such as salts or esterified derivatives may be contained in a proportion of 10 mol or less, particularly 5 mol or less, based on the total tetracarboxylic acid components.

The solvent in which the aromatic polyimide is dissolved in the method of this invention is a solvent containing a phenolic compound as a main component, and
Solvents that are 00% phenolic compounds are preferred, but
In addition to phenolic compounds, other solvents that are compatible with phenolic compounds.

For example, carbon disulfide, dichloromethane, trichloromethane, nitrobenzene, 0-dichlorobenzene, etc.
A mixed solvent containing less than 30 parts by weight, particularly 30 parts by weight or less, may be used.

Mention may be made of the phenolic compounds used in the method of the invention.

In particular, as a halogenated phenol, the general formula R is hydrogen or an alkyl group having 1 to 3 carbon atoms, and x is...
), and its melting point is approximately 10
0° C. or lower and whose boiling point is about 300° C. or lower at normal pressure is optimal because it has excellent ability to dissolve biphenyltetracarboxylic acid-based aromatic polyimides.

In the method of this invention, the halogenated phenols include 2, for example, 3-chlorophenol, 4-chlorophenol (sometimes abbreviated as hala-chlorophenol PCP), 3-bromophenol, 4-bromophenol,
2-chloro-4-diromo-4-hydroxytoluene, 2
-bromo-5-hydroxytoluene, 3-bromo-5-
Examples include hydroxytoluene, 3-bromo-6-hydroxytoluene, and 4-bromo-2-hydroxytoluene.

In the method of this invention, as described in the production of aromatic polyimide, the biphenyltetracarboxylic acid component and the aromatic diamine component are used.

1 at 120-400℃ in a melt of a phenolic compound.
When producing aromatic polyimide by polymerization and imidization in stages, the polymerization reaction mixture can be immediately converted into a polyimide composition for hollow fiber spinning by simply adjusting the polyimide concentration or viscosity as necessary. It can be used as a dope solution.

However, in the production of aromatic polyimide, when the polyimide is separated as a powder, the polyimide composition used in the present invention is prepared by mixing the polyimide powder in a solvent containing a phenolic compound as a main component. Disperse, mix and heat the dispersion sufficiently to completely dissolve the polyimide powder.

It is preferably within the range of 12 to 15% by weight. Further, the polyimide composition is prepared at a temperature of 0-1, which is the temperature at which the dope solution is formed into a hollow fiber body for spinning hollow fibers.
50° C., especially in the range from 20 to 120° C., the rotational viscosity is at least 500 centipoise, especially from 10 to 120° C.
It is preferable that the composition becomes a uniform liquid composition with a size of about 100,000 poise and can be used as a dope solution.

In the method of the invention, the aromatic polyimide composition described above is used as a dope for spinning hollow fibers.

The dope liquid is extruded from a hollow fiber nozzle to form a large number of unsolidified hollow fibers.

Polyimide hollow fibers are continuously produced by coagulating the hollow fibers in a coagulation liquid made of a polar solvent.

In the method of the present invention, the hollow fiber nozzle for forming the hollow fibers of the polyimide composition (dope solution) may be formed by extruding the hollow fibers from the dope solution of the polymer solution composition.

Any type of hollow fiber nozzle may be used.

For example, a tube-in-Oliace nozzle
e in orifice-type), segmented arc nozzle
c type), etc. In this invention, a tube-in-orifice type nozzle is preferred as a nozzle for hollow fibers. This tube-in-orifice (outer diameter 0.15-1.6mm, inner diameter 0.05-1.6mm)
4 wings) protrude, and the gap (annular part) between the inner circumferential surface of the opening of the orifice 2 and the outer circumferential surface of the tube 3
The dope liquid 16 is pushed out from the tube 3 at the same time by back pressure.
A gas or liquid (also referred to as core liquid) 20 is supplied from the inner hole to form a hollow fiber body.

In the method of the present invention, a method for forming hollow fibers with a polymer solution composition (dope solution) is, for example, by filtering and defoaming the dope solution at 20 to 200°C, particularly 30 to 150°C, and performing the above-mentioned method. Supplied to a nozzle head tank with a hollow fiber nozzle, the dope solution in the nozzle head tank has a concentration of about 0.1-20! /ca.

In particular, a back pressure of 0.2-10 Kp/crl (gauge pressure) is applied, and the temperature is about 20-150°C from the hollow fiber nozzle.

In particular, a method of extruding the dope at a discharge temperature of 30 to 120° C. to form hollow fibers of the dope can be mentioned.

In this invention, when extruding the hollow fiber as described above, gas is introduced from the tube inside the hollow fiber nozzle into the inside of the hollow fiber that is being extruded. -c ′-, 'to'
Needless to say, it must be a polar solvent that has excellent compatibility with the solvent (solvent containing a phenolic compound as a main component) of the liquid (pure liquid).

Examples of the coagulating liquid that can be used in the present invention include:

An ethanol-water mixed solvent is suitable.

In this invention, immediately after extruding and molding a hollow fiber from a hollow fiber nozzle, the unsolidified hollow fiber is immersed in a coagulating liquid while being stretched slightly under tension and solidified. is preferred.

Further, in the present invention, after the hollow fiber body is coagulated in a coagulation liquid to an extent that the hollow fiber form can be maintained.

First, it is wound around guide rolls, tension rolls, etc., the direction of the hollow fiber is changed, and the fiber is sent to the ninth step.

In this invention, the above-mentioned hollow fiber state that has been temporarily solidified is
After further immersing the hollow in the coagulation solution several times and thoroughly washing it with an inert solvent, the inert solvent is removed.

':1;'2. For example, hollow fibers can be produced by immersing them in water or by placing them in an appropriate manner.

That is, as shown in FIG. 1, a polyimide composition (dope solution) 16 is added to a spinning nozzle head 1 having a tube-in-orifice type nozzle (/cl+), and the discharge temperature is set to 20 to 150°C. The dope liquid is heated as shown in FIG. The dope liquid is extruded into a hollow fiber shape from the annular gap between the holes to form a hollow fiber body 4 of the dope liquid, and while the hollow fiber body 4 is stretched by applying a tensile force, the coagulation liquid 17 in the first coagulation tank 6 is The hollow filament body 4 is immersed in the liquid and temporarily solidified 9. Then, the hollow fiber body 4 is
Wrap it around guide roll 5.7.

The coagulated hollow fiber 14 is stored in an inert solvent 19 for storage.
The water is supplied to the storage tank 13 filled with water and stored.

Note that the guide rolls 5, 7. It is part of the second coagulation tank 11.

The polyimide hollow fiber membrane produced by the method of this invention has excellent chemical resistance and heat resistance, and has hydrogen-carbon oxide separation ability (P'
H2/P'co) 40 or more, and the hydrogen permeation rate (p
,) 1-5eC-tynH to 5 X 10-6J/c
Indicates 1 or more.

Reference Examples 1 to 5 z,3',4.4'-biphenyltetracarboxylic dianhydride (BPDA) approximately 40 mmol 4.4'-diaminodiphenyl ether (DADE) 32 mmol, 3
．． 5 = 8 mmol of diaminobenzoic acid (DABA) was placed together with p-chlorophenol in a separable flask equipped with a stirrer and a gas inlet tube, and the temperature was raised from room temperature to 180°C in about 1 hour while flowing the gas. 18
Polymerization was carried out at 0°C for a predetermined time. The results are shown in Table 1. p-
Chlorphenol has a polymer concentration of 10.12,15
, 17.20%. Also BP
As a method of adjusting the molecular weight of DA, a slightly smaller amount of O was added than that of the aromatic diamine.

Table 1 Examples 1 to 2 and Comparative Examples 1 to 3 Using the dope solution prepared in each reference example, aromatic polyimide hollow fibers were spun using the hollow fiber spinning apparatus shown in Figure 1. .

First, each dope solution 16 was supplied to the rad l to a hollow fiber spinning nozzle having a tube-in-orifice type nozzle as shown in FIG. The hollow fiber nozzle of the nozzle head 1 has an inner diameter of 6 m at the center of the bottom surface of the head 1.
, m, and a tube 3 coaxial with the orifice 2 and having an outer diameter of 1.0 ma and an inner diameter of 0.5 ms protrudes. The dope solution was heated so that the discharge temperature when discharging it from the in-or was as shown in Table 2. Gaseous nitrogen is supplied from the inside of the hollow fiber nozzle 3 to the first coagulation tank 6.
It is immersed in the coagulation liquid (deep liquid; 14 m) 17 in the coagulation tank, is then coagulated, passes through the guide roll 5 and the guide roll 7 in the first coagulation tank 6, and then passes through a pair of coagulation liquids in the second coagulation tank 11. Raw coagulation liquid 1
8 for secondary coagulation, and then passed through a third coagulation bath and wound up in a wet state. The obtained wet yarn was wound into a skein, dipped in ethanol and then in n-hexane to replace the solvent, dried and heat treated to obtain a hollow fiber. This bundle of hollow fibers is fixed to a glass tube with epoxy resin to create a gas separation module.
The gas permeation rate of each sample at room temperature was measured. Spinning conditions, hydrogen gas permeation rate, hydrogen, -carbon oxide content

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a hollow fiber spinning apparatus for carrying out the method of the present invention. FIG. 2 is a partial sectional view showing an example of a hollow fiber nozzle, and FIG. 3 is a plan view of a discharge portion of the hollow fiber nozzle. ; Nozzle head for hollow fiber spinning, 2; Orifice, 3;
Cheap, 4; Hollow filament, 5. 'i'. C11. ．． - elementary gas supply conduit, 16; dope liquid, 17; first coagulation liquid,
18; second coagulation liquid; 19; storage liquid; 20; core gas.

Claims (1)

[Scope of Claims] A repeating unit substantially represented by the general formula. It is characterized by being extruded through a slurry and coagulated in a coagulation bath made of a polar solvent. Hydrogen-carbon dioxide