JP3128875B2 - Polyphenylene sulfide sulfone hollow fiber membrane and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous hollow fiber membrane, and more particularly to a porous hollow fiber membrane useful as an ultrafiltration membrane or a composite membrane support membrane having a pore size equivalent to that of an ultrafiltration membrane. is there.

[0002]

2. Description of the Related Art Conventionally, ultrafiltration membranes produce pure water for the electronics industry, collect electrodeposition coatings, treat sewage in thread and pulp mills, treat oily wastewater, treat building wastewater, clarify fruit juice, and sake. Production, concentration and desalination of cheese whey, production of concentrated milk, concentration of egg white, treatment of soy protein, concentration and recovery of enzymes, utilization in bioreactors, concentration and separation of biproducts, Application to various fields such as removal of fine particles, removal of fine particles in organic liquids, and water treatment of nuclear power plants has been studied and put to practical use. Further, a porous membrane having a pore size equivalent to that of an ultrafiltration membrane used for such an application is also used as a support membrane for a composite membrane in the field of a reverse osmosis composite membrane or a gas separation membrane. In such an application field, heat resistance to withstand hot water washing, steam sterilization or steam sterilization,
Characteristics such as sterilization and acidic or basic use conditions, chemical resistance to withstand organic solvents and chemicals, and stain resistance (fouling resistance) are required. However, a porous membrane that satisfies all such required characteristics has not yet been developed, and there is a strong demand for the development of a porous membrane having excellent durability, especially a porous hollow fiber membrane.

As an example of a porous film, for example, cellulose acetate is a film material having good workability and excellent performance, but is not satisfactory in heat resistance and chemical resistance.
Polyacrylonitrile, polyvinylidene fluoride, etc. are better than cellulose acetate in solvent resistance and heat resistance. Practical porous membranes have been provided, but still have satisfactory properties. It cannot be said that it is a film material. Polysulfone has excellent heat resistance and good workability, so ultrafiltration membranes including hollow fiber membranes with various fractionation characteristics have been developed and put to practical use.However, in terms of solvent resistance and fouling resistance, The problem remains. If the chemical resistance and the organic solvent resistance are excellent, the film performance can be recovered by washing, and this can be a solution in terms of durability. Polyimide membranes are extremely excellent in solvent resistance and heat resistance, and although hollow fiber membranes of practical use have been developed, they have the disadvantage of poor alkali resistance.

A polyphenylene sulfide (PPS) film has been proposed as a film excellent in heat resistance, chemical resistance and solvent resistance (Japanese Patent Application Laid-Open Nos. 58-67733 and 60-202).
No. 659), and a method for producing a hollow fiber membrane has also been studied (Japanese Patent Application Laid-Open Nos. 59-59917, 60-44404, and Kaisho).
No. 60-248202). However, there is essentially a problem in workability, and it is difficult to control the pore size of the membrane. When the stretching method is used, it becomes a microporous membrane at the level of a microfiltration membrane, and when it is dissolved in a special solvent under severe conditions and formed by a solution method, it exhibits high permeability as an ultrafiltration membrane. It is considered difficult to realize a film structure. Of course, the porous membrane for the support membrane also has problems in the pore shape and the inner and outer surface structures, and it can be said that the porous membrane is not practically usable. There has been proposed a method of further improving heat resistance and chemical resistance by converting a sulfide bond into a sulfone bond by oxidizing a PPS porous body (Japanese Patent Laid-Open No. 63-225636). Since the porous body itself is related to the method of selectively oxidizing sulfide bonds after processing by the various methods described above,
Problems remain in the control of fractionation performance and permeability.

[0005] In addition, studies have been made to form an ultrafiltration membrane from heat-resistant and chemical-resistant engineering plastics such as polyether-terketone, but no practical membrane has been developed.

[0006]

Among these polymers, polyphenylene sulfide sulfone is extremely excellent in heat resistance, chemical resistance and organic solvent resistance, and is expected to be applied to a porous hollow fiber membrane. However, it is known that it is difficult to adjust the viscosity to be high, and it is extremely difficult to spin. It is also conceivable to add polyethylene glycol or polyvinylpyrrolidone to increase the viscosity.However, such additives reduce the inherent heat resistance, chemical resistance, and organic solvent resistance of polyphenylene sulfide sulfone. Might be.

Accordingly, an object of the present invention is to solve such problems and to provide a porous hollow fiber membrane having extremely excellent heat resistance, chemical resistance and organic solvent resistance, and a method for producing the same. It is assumed that.

[0008]

Means for Solving the Problems The present invention has the following constitution to achieve the above object. (1) A polyphenylene sulfide sulfone mainly containing a repeating structural unit represented by the general formula-(Ar-S-Ar-SO ₂ ) _n- (where Ar represents a phenylene group), the inner surface of which is smooth and macrovoided Porous hollow fiber membrane without defects.

(2) General formula-(Ar-S-Ar-SO
₂ ) In the spinning of polyphenylene sulfide sulfone mainly containing a repeating structural unit represented by _n − (where Ar represents a phenylene group), the linear velocity of the liquid to be injected discharged from the central pipe of the circular base and the liquid discharged from the circular orifice And the ratio of the linear velocity of the polyphenylene sulfide sulfone solution to the linear velocity of the solution discharged from the annular orifice is 0.85 to 2.0. A method for producing a porous hollow fiber membrane, wherein the ratio, ie, the draft ratio, is in the range of 0.7 to 1.1.

(3) General formula-(Ar-S-Ar-SO
₂ ) polyphenylene sulfide sulfone mainly containing a repeating structural unit represented by _n- (where Ar represents a phenylene group) is an n-methylpyrrolidone solution to which triethylene glycol has been added,
A method for producing a porous hollow fiber membrane according to claim 2.

[0011] The porous hollow fiber membrane of the present invention has almost no change in permeation performance and fractionation performance even after repeated steam sterilization, is resistant to many organic solvents, and is resistant to sodium hypochlorite sterilization. The characteristics do not change even if it is repeated. Further, it is useful as a porous membrane for ultrafiltration that can be used in a wide range of pH, and has excellent properties as a support membrane for a composite membrane. Further, the present invention can stably spin a hollow fiber membrane having a wide range of dimensions, and can economically provide a hollow fiber membrane having a smooth inner and outer surface, particularly an inner surface on which uneven wrinkles are easily generated. it can.

The porous hollow fiber membrane comprising polyphenylene sulfide sulfone in the present invention has the general formula-(A
r-S-Ar-SO ₂ ) _n- (where Ar represents a phenylene group) is a porous hollow fiber membrane having a smooth inner surface made of polyphenylene sulfide sulfone mainly containing a repeating structural unit represented by the following formula:

Here, the phenylene group (Ar) is usually a paraphenylene group in a preferred embodiment, but may be a metaphenylene group or an orthophenylene group, and these groups may be present together. Furthermore, this phenylene group is a hydroxyl group, a hydroxyethyl group, a hydroxymethyl group,
Although it may be substituted with a sulfonic acid group, a carboxylic acid group, or the like, an unsubstituted phenylene group is preferable in consideration of the properties of the membrane. The proportion of the polyphenylene sulfide sulfone repeating structural unit in the entire polymer composed of polyphenylene sulfide sulfone mainly containing the repeating structural unit needs to be about 70 mol% or more. When the proportion of the structure other than the repeating structural unit is more than 30%, the properties may be deteriorated in heat resistance, chemical resistance, or solvent resistance.

Although it is difficult to precisely specify the range of n indicating the degree of polymerization because many factors are involved, the approximate range is about 80 to 400, and the weight average molecular weight is 11
Polymers in the range of 600 to 93000 can be preferably used. Although the molecular weight distribution is also an important factor, the range of the polymer obtained by a usual method, that is, the value of weight average molecular weight / number average molecular weight is 1.2 to 3.5, and in terms of processability, 2.0 to 3 Polymers in the range of 0.0 are preferred. 3.
If it is 5 or more, the spinnability may lack stability. Since directly measuring the molecular weight or the degree of polymerization of a polymer is troublesome, the evaluation is usually made based on a dilute solution viscosity. When the intrinsic viscosity measured at 25 ° C. using n-methylpyrrolidone (hereinafter abbreviated as NMP) as a solvent shows a preferable range of 0.1 to 1.0 dl / g, a particularly preferable range is 0.3 to 0. 0.6 dl / g. Further, as a simpler method for evaluating the degree of polymerization, there is an evaluation based on melt viscosity.
This is represented by the number of grams of polymer discharged for 10 minutes under the following conditions using a melt flow measuring device. That is, a diameter of 0.0825 ± 0.002 inches and a length of 0.3
343 with 15 ± 0.001 inch orifice
Measure at 5 ° C. with a load of 5 kg. This value is set as the MF value. There are factors other than molecular weight in the factors that affect the melt viscosity, and it is generally difficult to specify only by the measured value of the melt viscosity, but it is empirically known that it can show an approximate suitable range. I have. Therefore, the MF value is in the range of 2 to 1500, preferably in the range of 5 to 40,
More preferably, a polymer in the range of 5 to 30 is preferred for practicing the present invention.

If the viscosity is lower than the above range, it is difficult to spin. If the viscosity is high, it is impossible or extremely difficult to obtain such a high-viscosity polyphenylene sulfide sulfone. Not.

Such a polymer can be produced according to a known method, for example, JP-A-63-270736.

The porous hollow fiber membrane of the present invention is a porous membrane made of a hollow fiber having a smooth inner surface and a perfectly circular cross section.
Here, a hollow fiber having a smooth inner surface refers to a state in which wrinkle-like deformation or wrinkles are not recognized on the inner surface at a level observed at a magnification of 500 times with an optical microscope and a scanning electron microscope. When the inner surface is smooth, when the fluid to be treated is poured into the inside of the hollow fiber, the deposition of foreign substances and the like on the membrane surface can be suppressed, and when pressure is applied from the outside, the hollow fiber is not concentrated due to stress concentration. This is advantageous in preventing deformation or buckling.
A true circular hollow fiber is defined as a hollow fiber having a cross section perpendicular to the fiber axis of the hollow fiber, in which the degree of deformation of the outer and inner circles is regarded as elliptical, and the major axis is a _o and a _i , and the minor axis is _bo. , when a _{b i, b o} / _a o and _b i / _{a i} is 0.9 or more preferably refers to hollow fiber form which can be regarded as macroscopically circularity of 0.95 or more. When the center of the outer periphery and the center of the inner periphery of the hollow fiber are displaced from each other, the ratio WT _min / WT _max of the maximum thickness WT _max and the minimum thickness WT _min of the hollow fiber is 0.8. Above, preferably 0.9 or more hollow fiber. In such a hollow fiber membrane, deformation and buckling of the hollow fiber due to stress concentration when pressure is applied from the outside are less likely to occur.

A porous membrane has a volume porosity of 20% to 80% and an ultrafiltration rate coefficient of pure water of 1.0 to 300.
mlm ^- 2h ^{- 1} refers to a porous membrane in the range of mmHg- ¹ . The average pore size of the pores is in the range of 1 to 30 nm. When the inner and outer surfaces of such a porous membrane are observed at a magnification of 50,000 to 100,000 by a scanning electron microscope, a structure similar to an opening portion of pores of 1 nm or more can be observed. Such membranes are useful as support membranes for ultrafiltration membranes or composite membranes for reverse osmosis, composite membranes for gas separation, and other functional composite membranes, depending on the combination of the properties of water permeability and molecular weight cutoff. .

The membrane structure of the cross section perpendicular to the fiber axis of the hollow fiber is a structure having a dense layer at least on the outer surface side. A dense layer may be provided on the inner surface side. The structure of the outer surface layer is composed of a dense layer having no microvoids on the surface and a porous layer in which microvoids are arranged tangentially to the circumference supporting the layer. The microvoided porous layer has a structure further supported by the macrovoided porous layer developed tangentially to the circumference. The structure on the inner surface side may be similar to the structure on the outer surface side, but may be a structure in which a dense layer free of microvoids is supported by a porous layer of macrovoids. There may be an intermediate layer composed of microvoids without macrovoids between the inner surface layer and the outer surface layer. In that case, the microvoids in the intermediate layer have a cellular structure, and the walls between the microvoids need to be connected by pores. Such a structure is a structure in which the fractionation characteristics are determined by the dense layer and the porous layer minimizes the resistance to the permeation rate, and is also a structure that is durable against external force when the hollow fiber membrane is used.

However, a huge macro void having a void diameter reaching 80% of the thickness of the hollow fiber membrane or having an opening on the outer or inner surface of the hollow fiber membrane is a hollow fiber membrane. This is not preferable because it causes macro void defects, such as causing leaks of the fibers and deformation or buckling of the hollow fiber membrane due to stress concentration when pressure is applied from the outside.

The above general formula-(Ar-S-Ar
The preferred embodiment for producing a porous hollow fiber membrane having a smooth inner surface made of polyphenylene sulfide sulfone mainly containing a repeating structural unit represented by —SO ₂ ) _n − is a line of an injection liquid discharged from a central pipe of an annular base. The ratio between the velocity and the linear velocity of the polymer solution discharged from the annular orifice is in the range of 0.85 to 2.0, and the drawing speed of the hollow fiber in the coagulation bath and the polymer discharged from the annular orifice The ratio with the linear velocity of the solution, that is, the draft ratio is in the range of 0.7 to 1.1.

A generally known method for producing a hollow fiber membrane from a polymer solution is a spinning solution obtained by dissolving a polymer in a predetermined solvent by using a spinneret provided with a center pipe at the center of an annular orifice by a wet process or a dry process. It is introduced into a coagulation bath by a method, and is subjected to coagulation, water washing, and post-treatment steps to produce a yarn. The spinning solution is discharged from an annular orifice and a predetermined amount of gas or liquid is introduced from a central pipe. In the solution spinning method, it is often difficult to inject a gas, and usually a liquid is used, and more generally, a liquid having a coagulating power is used. If the viscosity of the spinning solution is sufficiently high, a non-coagulating liquid can be used. However, when the viscosity of the spinning solution is low, as in the case of polyphenylene sulfide sulfone, a spinnable liquid is used to obtain spinnability expressed by a gel layer formed by coagulation on the inner surface of the hollow fiber. It is necessary to form a hollow fiber. In this case, a solution of the solvent used for the spinning solution is generally used as the liquid to be injected with its concentration adjusted.
Since it is advantageous in practice to use an aqueous solution for the coagulation bath, an aqueous solution is often used for the injection liquid. In order to manufacture a hollow fiber membrane suitable for various uses by adjusting the water permeability and the fractionation characteristics of the porous hollow fiber membrane widely, the polymer concentration of the spinning stock solution and the coagulation conditions are changed. Therefore, depending on the properties of the intended hollow fiber membrane, the viscosity of the spinning stock solution may be low and the spinnability may be insufficient, and furthermore, the coagulation force of the injection liquid is low and the deformation is likely to occur in the coagulation bath. It may be a condition. In addition, when a coagulable injection liquid is used, wrinkle-like irregularities are generated on the inner surface depending on the inner and outer diameters of the hollow fiber, and when the hollow fiber membrane is used, fine particles and foreign substances in the processing liquid are deposited, and the membrane module is formed. This may cause a decrease in the performance of the tool. In addition, it causes the concentration of stress of the external force applied when the membrane module is used, and causes buckling or rupture of the hollow fiber membrane. Therefore, the inner surface is required to be as smooth as possible. The outer surface tends to be relatively smooth, while the inner surface tends to wrinkle.
Further, as a general spinning technique, the thickness of the yarn is adjusted by adjusting the ratio of the drawing speed of the hollow fiber in the coagulation bath to the linear speed of the polymer solution discharged from the annular orifice, that is, the draft ratio. Do. However, when a hollow fiber membrane is formed from a low-viscosity, low-spinning spinning solution, such as polyphenylene sulfide sulfone, it is generally difficult to adjust the draft ratio.

The general formula of the present invention:-(Ar-S-Ar
-SO ₂ ) When a hollow fiber membrane is produced from a solution of polyphenylene sulfide sulfone mainly containing a repeating structural unit represented by _n- , the above-described low viscosity, low spinnability,
Smooth inner surface hollow fiber membrane having water permeability and molecular weight cutoff characteristics within the range required for ordinary ultrafiltration porous membranes due to wrinkled deformation of the inner surface and various low coagulation properties It was very difficult to make the yarn. However, when the present inventors design and manufacture an annular die for a hollow fiber having a desired dimensional characteristic so that the conditions in the above-described range are satisfied,
It has been found that a porous hollow fiber membrane having a smooth inner surface can be produced in good condition.

In the case of a spinning dope having a solution viscosity of several tens of poise or more, the difference in speed between the polymer solution discharged from the annular orifice and the injection liquid discharged from the central pipe is not much considered. However, in the case of a spinning solution having a solution viscosity of several tens of poise or less, the surface shape inside the hollow fiber is significantly impaired, and in some cases, the injection liquid is involved in the polymer solution,
The present inventors have found that macrovoids are formed in the membrane wall of the hollow fiber. This phenomenon can improve the inner surface shape to some extent by lowering the coagulability of the infusate, but it increases the inclusion of macrovoids in the membrane wall and causes leakage of the hollow fiber membrane. Become. If the coagulation property is increased, the shape of the inner surface is deteriorated, and the entrapment of macro voids cannot be completely prevented. It was extremely difficult to spin underneath.

The ratio between the linear velocity of the liquid injected from the central pipe of the annular base and the linear velocity of the polymer solution discharged from the annular orifice is in the range of 0.85 to 2.0, and The spinneret size is designed so that the ratio of the drawing speed of the hollow fiber in the coagulation bath to the linear speed of the polymer solution discharged from the annular orifice, that is, the draft ratio is in the range of 0.7 to 1.1, and the spinning is performed. It has been found that by adjusting the conditions, the hollow fiber in a good state can be produced under a wide range of spinning conditions without causing the hollow fiber inner surface to be smooth and macrovoids to be caught in the membrane wall. If the ratio of the linear velocity of the injection liquid to the linear velocity of the polymer solution discharged from the annular orifice is 0.85 or less, it becomes difficult to adjust the hollow fiber membrane to a predetermined thickness, and the inner surface has wrinkles. Top streaks or deformations are likely to occur. When it is 2.0 or more, macrovoids are easily involved, the roundness of the cross section changes, and the fluctuation of the film thickness in the fiber axis direction increases. More preferably, 0.
The spinneret dimensions should be designed so that spinning can be performed in the range of 9 to 1.5. Since the lower limit of the draft ratio is also regulated by the viscosity of the spinning stock solution, it is difficult to specify the draft ratio in a straightforward manner. The range is preferably 7 or more, more preferably 0.8 or more. The upper limit of the draft ratio is also regulated by the spinnability of the polymer solution, and since the spinnability is affected not only by the viscosity but also by the coagulation force of the injection solution and the conditions of the atmosphere in the dry section, it is difficult to specify strictly. .1
In order to spin a hollow fiber having a smooth inner surface and a defect-free hollow fiber having a roundness of 0.8 or more while maintaining a good yarn-making property, 1.0 is required.
The following conditions are more preferable.

In a further preferred embodiment for producing a defect-free hollow fiber membrane from the polyphenylene sulfide sulfone polymer of the present invention, triethylene glycol (hereinafter abbreviated as TEG) is added in preparing a spinning dope. Spinning from the NMP solution obtained by a dry-wet method. When producing a hollow fiber membrane by a solution spinning method, an additive has often been conventionally recommended. Additives are used as pore-opening agents or for the purpose of improving spinnability. However, in the case of low-molecular-weight organic compounds, it is necessary to add more than 10% or more in order to utilize the phase separation function. is there. In the case of a high molecular compound, it is washed out in the process after coagulation and uses the remaining pores, and is added to the spinning solution at a rate of more than 10% as in the case of the low molecular organic compound. There is a need. In many cases, it may also have the function of phase separation.
A polymer compound is also added for the purpose of improving spinnability while keeping the size and structure of the die as conventional. In this case, the effect of increasing the viscosity of the spinning solution is aimed at, and the effect can be expected even with a relatively small amount. However, the additive must have a high molecular weight. The purpose of the addition of TEG of the present invention is not any of these, and it aims at a rectifying effect of improving the flow state of the polymer solution near the mouthpiece. Therefore, the effect of increasing the viscosity with a low molecular weight and a small amount of addition is intended. Even under unexpected conditions, it is effective for smoothing the inner surface, preventing macro voids, and improving spinnability. It is not clear why such an effect appears, but TEG is added to the spinning dope in a range of 2.5% by weight to 10% by weight, more preferably 3.5% by weight to 7.5% by weight. When added in the following range, the spinning effect is further improved even in the range of the optimum conditions of the linear velocity ratio and the draft ratio of the spinning solution. When the content is less than 2.5% by weight, the effect is small, and when the content is more than 10% by weight, the stability of the NMP solution of the polyphenylene sulfide sulfone polymer of the present invention is lost, so that the polymer is easily gelled or solidified and spinning becomes difficult. . As substances other than TEG, ethylene glycol, glycerin, diethylene glycol, tetraethylene glycol, and monoesters or diesters thereof have the same effect as TEG, and low molecular weight polyvalent alcohols and Mono- or diesters. Each of them has a different gelation or solidification range, especially an upper limit, and TEG is easy to spin.

The undiluted spinning solution is prepared by taking a predetermined amount of the dried polymer in a dissolving tank equipped with a stirrer, adding measured NMP, heating to 150 ° C. while stirring and dissolving, and dissolving at 150 ° C. for 1 hour or more. Further, the temperature is raised to 180 ° C. or more, and dissolved for 1 hour or more. After dissolution, defoaming is performed to prepare a spinning dope. Next, the solution is transferred to a stock solution tank of a generally known hollow fiber spinning device, and is subjected to spinning. When an additive such as TEG is added, the mixture is melted at 180 ° C., and after the temperature reaches 150 ° C. or lower and 120 ° C. or higher, a predetermined amount of the additive is added and further stirred to mix uniformly.

Even if the viscosity of the spinning dope thus prepared is not more than ten and several poise at 50 ° C., if the conditions of the spinneret and the spinning draft are selected within the above-mentioned suitable ranges, the known spinning solution and spinning conditions are usually used. Thus, a hollow fiber membrane in a good state can be spun. That is, the temperature around the spinneret during spinning is 20 to
The temperature is adjusted at 100 ° C, more preferably within the range of 30 to 60 ° C. When the spinning temperature is high, the viscosity decreases and spinning becomes difficult. If the spinning temperature is too low, the stock solution tends to solidify, making continuous spinning difficult.

The fluid to be injected into the hollow portion of the hollow fiber membrane is preferably a solidifying liquid in the case of the polyphenylene sulfide sulfone of the present invention. This is because the viscosity of the solution of the polymer is very low and the spinning property is inferior, and it is necessary to promote a certain amount of thread formation in the dry portion before being introduced into the coagulation bath. The injection liquid is preferably an aqueous solution of a solvent used for the spinning dope, preferably 30 to 90% by weight, particularly preferably 50 to 90% by weight.
A 70% strength by weight solution is preferred. If the concentration is high, the coagulation property is low, the filament formation is delayed, the spinning property becomes insufficient, the filament is easily cut directly under the die, and in a severe state, it becomes a droplet and cannot be spun. If the concentration is too low, the coagulability is too strong, and wrinkles or streaks are formed on the inner surface, and it is difficult to spin a hollow fiber membrane having a perfect circular shape because of the smooth inner surface.

The concentration of the coagulation bath is preferably an aqueous solution of the solvent used for the spinning dope having a concentration in the range of 0 to 40% by weight. From the viewpoint of recovering the solvent, a high concentration is economically excellent. However, in the case of the polyphenylene sulfide sulfone of the present invention, since the solidification is relatively slow, a low concentration is preferred. The temperature is from 0 to 70 ° C, and a more preferable range is 2 ° C.
0-60 ° C. The coagulation conditions are selected in consideration of the coagulation properties and the performance characteristics of the hollow fiber membrane.

The water washing step can be carried out in the same manner as in a usual spinning method of a dry-wet system. As a post-treatment after washing with water, it is preferable to perform a heat treatment. Usually, hot water at 50 to 95 ° C., preferably 70 to 95 ° C., is used for 1 hour following the washing step.
By performing the treatment continuously for 0 to 60 seconds, the performance and dimensions of the hollow fiber membrane can be stabilized. Of course, there is no particular problem even if the batch processing is performed for 1 minute or more. The hollow fiber membrane after the heat treatment may be processed into a membrane module, and then may be dried by adhering and impregnating a suitable amount of a surfactant so that it is easily replaced with water at the time of use.

Hereinafter, the present invention will be described in detail with reference to Examples, but it goes without saying that the present invention is not limited to the following Examples.

The method for evaluating and measuring the characteristic values of the present invention is as follows.

(1) The viscosity of the spinning stock solution was measured by measuring the viscosity at 50 ° C. and 70 ° C. using a B-type viscometer manufactured by Tokyo Keiki.
o. The measurement was performed at 30 rpm or 60 rpm using the rotor of No. 2.

(2) Form and size of hollow fiber (inner diameter (I
D), measurement of outer diameter (OD), roundness, smoothness of inner surface)
The measurement was performed by observation and measurement using a Nikon VMS type metal microscope manufactured by Nippon Kogaku.

The roundness was calculated by the following equation.

Roundness = minor axis of outer diameter (a _o ) / major axis of outer diameter (b _o ) × 100 The smoothness of the inner surface is determined by the aforementioned optical microscope or scanning electron microscope with a magnification of about 500 times. And evaluated in the following manner.

Good inner surface smoothness ○ Less wrinkles, less streaks △ More wrinkles, more streaks × (3) The volume porosity of the hollow fiber is calculated from the dimensions of the hollow fiber, and is calculated based on the absolute dry weight of the polymer and the volume of the hollow fiber. Calculated from

(4) With respect to the pressure resistance of the hollow fiber, a leak was observed after preparing a glass mini-module having a length of about 25 cm. The number of hollow fibers was about 10 to 20, and the hollow fibers were inserted into glass so that the effective length was 20 cm, and both ends were sealed with an adhesive. One end of the hollow fiber sealed with an adhesive is closed, a rubber tube is connected to the other end, and nitrogen gas is used.
A pressure of about 100 mmHg was applied from the inside of the hollow fiber. The module was filled with water, and air bubbles from the hollow fiber were observed and evaluated in the following manner.

No bubbles are generated. ○ 0 to 1 bubble / m is a place where bubbles are generated. 1 or more / m is a place where bubbles are generated. (5) The water permeability of the hollow fiber is glass having a length of about 25 cm. Was prepared and the ultrafiltration rate was measured using purified water. The number of hollow fibers is about 10 to 20
The hollow fiber was inserted into glass so that the effective length of the hollow fiber was 20 cm, and both ends were sealed with an adhesive. The filtered water was collected from a nozzle of a branch pipe attached to a glass tube, and the weight of the water filtered over a certain period of time was measured. Purified water was supplied while being filtered through a hollow fiber type ultrafiltration membrane, and measured at 25 ° C. The water permeability UFRS was calculated by the following equation.

UFRS = Wd ⁻¹ A ⁻¹ t ⁻¹ P ⁻¹ (mlm ⁻² h ⁻¹ mmHg ⁻¹ ) where W: weight of filtered water d: density of water at 25 ° C. (g / ml) A: Effective membrane area of the hollow fiber membrane (m ² ) t: Time for collecting filtered water (h) P: Applied pressure (mmHg) (6) Linear velocity of injected liquid discharged from the central pipe of the annular base The ratio of the linear velocity of the polymer solution discharged from the annular orifice to the linear velocity of the polymer solution is about 1.15 and the specific gravity of the injection liquid is about 1.00, and the discharge weight per unit time (g / min) And the discharge area of the orifice.

[0042]

EXAMPLES The present invention will be described with reference to Examples.

Examples 1 to 7, Comparative Examples 1 to 15 Polyparaphenylene sulfide sulfone (PPS) obtained from Toray Philippe Spectro-Liam Co., Ltd.
Using (S), a spinning test of the hollow fiber membrane was performed. 320 parts by weight of PPSS polymer having an MF value of 28, 80 parts by weight of TEG, and 1200 parts by weight of n-methylpyrrolidone (NMP) are weighed into a separable flask having a volume of 2 l, and the temperature is raised from room temperature to 130 ° C. for 1 hour. Subsequently, the mixture was dissolved by stirring at 180 ° C. for 6 hours. The viscosity was 2.98 poise at 50 ° C and 1.60 poise at 70 ° C. This polymer solution was filtered through a 400 mesh stainless steel mesh and subjected to a spinning test. The test was performed by changing the die size and the polymer discharge amount. The results are shown in Table 1. The temperature of the spinneret portion at the time of spinning was 55 ° C., a 60% NMP aqueous solution was used for the injection solution, and 40 ° C. water was used for the coagulation bath. Wash 30
C. in a tray-type water washing bath.

[0044]

[Table 1]

As can be clearly seen from Table 1, the ratio of the linear velocity of the injection liquid discharged from the central pipe of the annular orifice to the linear velocity of the spinning dope discharged from the annular orifice is 0.85 to 2.0. In the case where the spinning draft ratio is in the range of 0.7 to 1.1, the hollow fiber has a smooth inner surface, and the hollow fiber has a good hollow state without leakage due to macro voids in the membrane wall. The yarn membrane can be spun.

Table 2 shows the evaluation results of the circularity, water permeability, volume porosity, and puncture pressure of the cross section of the hollow fiber membrane in a good state.

[0047]

[Table 2]

Examples 8 to 12 A spinning stock solution was prepared in the same manner as in Example 1 by using PPSS having an MF value of 40 obtained from Toray Philippe Spectro-Liam Co., Ltd. However, the amount of TEG added was two types, 2.5 and 5.0% by weight. TEG0
% Of the stock solution was 2.0 poise at 50 ° C. and 1.2 poise at 70 ° C. The stock solution with 2.5% TEG was slightly higher than the case with 0% TEG, and the stock solution with 5.0% TEG had a viscosity of 2.2 poise at 50 ° C and 1.3 poise at 70 ° C, respectively. However, it is judged that the viscosity does not increase as much as expected to improve spinnability. The dimensions of the spinneret used were a slit outer diameter of 1.4, a slit inner diameter of 1.1, an injection pipe inner diameter of 0.7 (mm), a spinning draft of 0.83, a discharge linear velocity ratio of 1.36, and a spinning temperature of 30.
~ 50 ° C, dry length 10 ~ 50mm, injection solution concentration 60
%, Infusion liquid temperature 25 ° C, coagulation bath concentration 10%, coagulation bath temperature 20 ° C, washing bath temperature 30 ° C, heat treatment bath 95 ° C,
The spinning was performed while changing the spinning temperature and the range of the dry length. The spinning conditions and results examined are shown in Table 3.

[0049]

[Table 3]

It has been shown that the addition of TEG allows stable spinning from a low-viscosity spinning dope.

Examples 13 to 16 Using a PPSS having an MF value of 33 obtained from Toray Philippe Spectro-Liam Co., Ltd., 5% TEG was added in the same manner as in Example 1 to prepare a spinning dope. The intrinsic viscosity number of the polymer measured at 30 ° C. using NMP as a solvent was about 0.35 dl / g, and the weight average molecular weight was about 30,000. The viscosity of the spinning dope was 2.1 poise at 50 ° C and 1.4 poise at 70 ° C. The dimensions of the cap used were: slit outer diameter 1.4, slit inner diameter 1.1, injection pipe inner diameter
0.7 (mm), spinning draft 0.79, discharge linear velocity ratio 0.88, spinning temperature 50 ° C, dry length 30 mm, injection liquid concentration 40-80%, injection liquid temperature 50 ° C, coagulation bath concentration 0
%, Coagulation bath temperature 30 ° C, washing bath temperature 30 ° C, heat treatment bath 9
Under the condition of 0 ° C., spinning was performed while changing the range of the concentration of the injection solution.
The results are shown in Table 4.

[0052]

[Table 4]

In a spinneret with dimensional accuracy that can be usually manufactured,
The concentration of the injection solution is preferably in the range of 40 to 65%, and it was determined that spinning was possible up to about 80% by selecting the size of the die.

Examples 17 to 27 Using a PPSS having an MF value of 8 obtained from Toray Philippe Spectro-Liam Co., Ltd., 5% TEG was added in the same manner as in Example 1 to prepare a spinning stock solution. The viscosity of the spinning dope was 4.1 poise at 50 ° C. and 2.7 poise at 70 ° C. The dimensions of the base used were the slit outer diameter.
4, slit inner diameter 1.1, injection pipe inner diameter 0.7 (mm)
With a spinning draft of 0.83, a discharge linear velocity ratio of 1.36, a spinning temperature of 60 ° C., a dry length of 50 mm, and an injection liquid concentration of 60%,
Spinning by changing the range of the coagulation bath concentration and coagulation bath temperature under the conditions of an infusate temperature of 55 ° C, a coagulation bath concentration of 0 to 40%, a coagulation bath temperature of 10 to 50 ° C, a washing bath temperature of 30 ° C, and a heat treatment bath of 95 ° C. did. Table 5 shows the results.

[0055]

[Table 5]

When the concentration of the coagulation bath was increased, the water permeation rate tended to decrease. When the concentration was 60% or less, particularly preferable inner surface smoothness was obtained.

When the coagulation bath temperature was high, the water permeation rate tended to increase. When the temperature was 50 ° C. or less, particularly preferable characteristics without leakage were obtained.

Examples 28 to 36 In the same manner as in Example 1, a stock spinning solution was prepared using PPSS having an MF value of 7 obtained from Toray Philippe Spectro-Liam Co., Ltd. without adding TEG. The weight average molecular weight of the polymer was about 30,000. The viscosity of the spinning dope was 80 poise at 50 ° C. and 49 poise at 70 ° C. The dimensions of the die used were a slit outer diameter of 1.5, a slit inner diameter of 1.1, an injection pipe inner diameter of 0.7 (mm), a spinning draft of 1.04, a discharge linear velocity ratio of 1.82, and a spinning temperature of 70.
~ 100 ° C, dry length 50 ~ 450mm, injection solution concentration 6
Under the conditions of 0%, infusion liquid temperature of 65 to 85 ° C, coagulation bath concentration of 0%, coagulation bath temperature of 30 ° C, washing bath temperature of 30 ° C, and heat treatment bath of 95 ° C, the range of coagulation bath concentration and coagulation bath temperature was changed. Spun. The results are shown in Table 6.

[0059]

[Table 6]

In the case of a spinning dope having a high molecular weight and a high viscosity, it can be seen that spinning can be performed at a relatively high temperature and a dry length can be increased.

Example 37 Using PPSS having an MF value of 31 obtained from Toray Philippe Spectro-Liam Co., Ltd., 5% of TEG was added in the same manner as in Example 1, and the polymer concentration of the spinning solution was 22%.
Was prepared. The viscosity of the spinning solution is 7.degree.
It was 3.7 poise at 8 poise and 70 ° C. The dimensions of the base used are: slit outer diameter 1.4, slit inner diameter
1.1, inner diameter of injection pipe 0.7 (mm), spinning draft 0.75, discharge linear velocity ratio 1.20, spinning temperature 80 ° C, dry length 50 mm, injection liquid concentration 60%, injection liquid temperature 65.
° C, coagulation bath concentration 0%, coagulation bath temperature 30 ° C, washing bath temperature 3
Spinning was performed at 0 ° C. and a heat treatment bath of 95 ° C. When the ratio between the spinning draft and the discharge linear velocity was set in a suitable range, a hollow fiber membrane having no leak and having a smooth inner surface and UFRS = 55 could be spun.

Example 38 Using PPSS having an MF value of 31 obtained from Toray Philippe Spectro-Liam Co., Ltd., 5% of TEG was added in the same manner as in Example 1 and the polymer concentration of the spinning solution was 18%.
Was prepared. The viscosity of the spinning dope is 2.degree.
It was 1.2 poise at 1 poise and 70 ° C. The dimensions of the base used are: slit outer diameter 1.4, slit inner diameter
1.1, injection tube inner diameter 0.7 (mm), spinning draft 0.79, discharge linear velocity ratio 0.88, spinning temperature 30 ° C, dry length 10 mm, injection liquid concentration 60%, injection liquid temperature 20
° C, coagulation bath concentration 0%, coagulation bath temperature 30 ° C, washing bath temperature 3
Spinning was performed at 0 ° C. and a heat treatment bath of 95 ° C. When the spinning draft and the discharge linear velocity ratio were set in a suitable range, a hollow fiber membrane having no leak and a smooth inner surface and UFRS = 156 could be spun despite being a low viscosity stock solution.

[0063]

According to the present invention, a hollow fiber membrane having excellent heat resistance and solvent resistance and having a smooth inner surface and free from defects such as macrovoids can be produced economically based on a stable technology. It can be provided in an advantageous manner. Application of such a hollow fiber membrane having excellent heat resistance and solvent resistance to various separation / purification processes contributes to saving of resources and energy, and economically produces high quality products to provide to society. Contribute to things.

Claims (3)

(57) [Claims] 1. A general formula - (Ar-S-Ar- SO 2) n
-A porous hollow fiber membrane made of polyphenylene sulfide sulfone mainly containing a repeating structural unit represented by (where Ar represents a phenylene group), having a smooth inner surface and free from defects due to macrovoids. 2. A compound of the general formula-(Ar-S-Ar-SO ₂ )
_In the spinning of polyphenylene sulfide sulfone mainly containing a repeating structural unit represented by _n − (where Ar represents a phenylene group), the linear velocity of the liquid injected from the central pipe of the annular die and the liquid discharged from the annular orifice The ratio of the linear velocity of the polyphenylene sulfide sulfone solution to the linear velocity of the solution is 0.85 to 2.0, and the ratio of the drawing velocity of the hollow fiber in the coagulation bath to the linear velocity of the solution discharged from the annular orifice, that is, A method for producing a porous hollow fiber membrane, wherein the draft ratio is in the range of 0.7 to 1.1. 3. A compound of the general formula-(Ar-S-Ar-S
O ₂₎ n _- (where Ar is polyphenylene sulfide sulfone triethylene glycol to the repeating structural unit comprising mainly represented by a phenylene group) - characterized in that it is a n- methylpyrrolidone solution added Le, billing Item 3. The method for producing a porous hollow fiber membrane according to Item 2.