JP2001170172A - Dialyzer for blood processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dialyzer which is a dry type semipermeable membrane, and has high water-permeability and dialyzing performance. SOLUTION: For this dialyzer for a blood processing, a semipermeable membrane containing a hydrophobic polymer and a hydrophilic polymer as the constituent components is built in. In such a dialyzer for the blood processing, the post-drying water-permeability to the pre-drying water- permeability of the semipermeable membrane is 1/2 or higher, and also, the clearance of vitamin B12 of the dialyzer is 135 ml/min or higher by a 1.6 m2 conversion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blood treatment dialyzer with little change in water permeability before and after drying.

[0002]

2. Description of the Related Art Semi-permeable membranes for blood treatment, including artificial kidneys,
As the natural material cellulose and its derivatives, cellulose diacetate and cellulose triacetate, change with the times, synthetic polymers have appeared, and polysulfone, PM
MA, polyacrylonitrile, and the like are widely used, and in recent years, modified membranes obtained by treating cellulose with PEG or the like to improve blood compatibility have been used. In blood treatment of patients with chronic renal failure, attempts have been made to positively remove other low molecular proteins while minimizing albumin leakage. In addition to membrane improvements, hemodiafiltration (HDF) and push-and-pull methods have been developed to improve dialysis efficiency and actively remove low molecular weight proteins. At present, polysulfone having high water-permeability among membrane materials has been widely used as being compatible with such advances in dialysis techniques. Polysulfone is widely used as a heat-resistant engineering plastic in the fields of automobiles, electricity, and medical devices.However, when a dialysis membrane is made of polysulfone alone, not only cannot the pore size be controlled because of strong intermolecular cohesion. Because of its hydrophobicity, it has poor affinity for blood, and blood components such as platelets tend to adhere, causing not only residual blood, but also severe deterioration in membrane performance. Further, since the airlock phenomenon easily occurs, it cannot be used for blood treatment as it is.

Accordingly, a method of forming pores by mixing inorganic salts or the like as a pore-forming material and desorbing them, and subsequently performing a hydrophilic treatment, or mixing a hydrophilic polymer as a pore-forming agent in advance and desorbing After the formation of pores, a method has been devised in which the surface of the polymer is simultaneously hydrophilized with the remaining hydrophilic component, and this is used as a semipermeable membrane or a reverse osmosis membrane. For example, (1) a method of forming a film by adding a metal salt, (2) a method of forming a film by adding a hydrophilic polymer, and (3) a method of forming a film by adding a polyhydric alcohol have been disclosed. . However, Japanese Patent Application Laid-Open No. 61-2328
60, when a polyhydric alcohol such as polyethylene glycol is added to form a membrane as in JP-A-58-114702, and when washing is insufficient, the patient's eye during dialysis due to the elution of polyethylene glycol etc. remaining on the membrane. In some cases, abnormalities occur. In the case of metal salts, the pore size is too large and is not suitable for a dialysis membrane. In addition, Japanese Patent Publication 5-543
No. 73 describes a dialysis membrane, but does not disclose a dry-type membrane having little elution of a hydrophilic polymer and high water permeability.

[0004]

The dialysis patients have continued to grow significantly, and the number of dialysis patients in Japan has exceeded 200,000.
Various types of dialyzer are available, but they are roughly classified into a wet type using a filling liquid and a dry type not using a filling liquid. The wet type is disadvantageous in that freezing and breakage are likely to occur due to the presence of water, and transportation costs are high due to its heavy weight.

[0005] The present invention utilizes a dry type semipermeable membrane which has advantages such as lightness and non-freezing, and which has improved water permeability and dialysis performance, which has been conventionally regarded as a drawback, as well as wet. It is to provide a dialyzer.

[0006]

The present invention has the following arrangement to achieve the above object.

In a blood treatment dialyzer containing a semipermeable membrane containing a hydrophobic polymer and a hydrophilic polymer as constituents, the permeability of the semipermeable membrane after drying to the permeability before drying is 1/1/2. A dialyzer for blood treatment wherein the clearance of vitamin B12 of the dialyzer is not less than 135 ml / min in terms of 1.6 m2.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a hydrophobic polymer constituting a semipermeable membrane, most engineering plastics such as polysulfone, polyamide, polyimide, polyphenyl ether, and polyphenylene sulfide can be used. The polysulfones represented are particularly preferred. The polysulfone has the following basic skeleton, but those having a modified benzene ring portion can also be used.

[0009]

Embedded image

As the hydrophilic polymer, for example, polyethylene glycol, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone and the like are used.
They may be used alone or as a mixture. Polyvinylpyrrolidone, which is relatively easily available industrially, is preferred. It is also preferable to use two or more hydrophilic polymers having different molecular weights. In that case, the weight average molecular weight is 5
It is preferable to use one that differs by a factor of two or more.

In the present invention, the stock solution used for forming the semipermeable membrane preferably comprises a hydrophobic polymer, a hydrophilic polymer, a solvent, and an additive. As the solvent, an amphoteric solvent that can dissolve the hydrophobic polymer, the hydrophilic polymer, and the additive well is used. Dimethylacetamide,
Examples thereof include dimethylformamide, dimethylsulfoxide, acetone, acetaldehyde, and 2-methylpyrrolidone, and dimethylacetamide is preferred from the viewpoints of danger, stability, and toxicity. The additive is a poor solvent for polysulfone and is compatible with the hydrophilic polymer, and is an alcohol, glycerin, water, an ester or the like, but water is particularly preferred from the viewpoint of process suitability.

The viscosity of the stock solution depends on the molecular weight of the hydrophilic polymer because the molecular weight of the commercially available hydrophobic polymer is low. A decrease in the viscosity of the undiluted solution causes breakage, swaying, and the like during the formation of the hollow fiber, thereby deteriorating the stability. Therefore, it is preferable to use high molecular weight PVP,
When PVP is used as a mixture, the average molecular weight is preferably increased to 200,000 or more.

Next, the polymer concentration of the stock solution will be described. From the above-mentioned point, as the polymer concentration is increased, the film-forming property is improved, but on the contrary, the porosity is reduced and the water permeability is reduced, so that an optimum range exists. In order to obtain a membrane having both high selective permeability and low albumin permeability even when the membrane is dried as in the present invention, the concentration of the hydrophobic polymer is preferably 10 to 20% by weight, more preferably 12 to 18% by weight. The concentration of the hydrophilic polymer is preferably 2 to 20% by weight, more preferably 3 to 15% by weight. Further, when two or more hydrophilic polymers having different molecular weights are used,
The mixing ratio of the polymer having a molecular weight of 100,000 or more in the stock solution is 1 to
10% by weight is preferred. If it is too high, the stock solution viscosity will increase,
Not only is it difficult to form a film, but also the water permeability and diffusion performance tend to decrease. On the other hand, if it is too low, there is a tendency that an appropriate network for permeating the medium high molecular weight uremic protein cannot be constructed.

Next, one embodiment of the film forming method will be described below. The membrane-forming stock solution having the above-described structure is simultaneously discharged simultaneously with the core liquid from a die having a double slit tube structure to form a hollow fiber membrane. Then, after a predetermined washing, drying step and crimping step, it is wound up and cut into an appropriate length,
It is inserted into a case, and its ends are sealed with a potting material to be modularized.

Particularly, in the case of the present invention, in the process up to the modularization, a stock solution is designed in consideration of film shrinkage without using a method of holding the membrane with a humectant and not including a drying step at all. By performing an operation of drying without using a membrane, it is possible to obtain a membrane having a water permeability after drying of 1/2 or more of the water permeability before drying of the present invention. Furthermore, especially when used for an artificial kidney, since the hydrophilic polymer is often eluted from the semipermeable membrane as it is, γ is used to reduce the eluted material.
Crosslinking is preferably performed by a beam, an electron beam, heat, or chemical.
Irradiation of γ-rays in the presence of air (in the presence of oxygen) breaks the main chain of the polymer due to excited oxygen radicals and causes decomposition.
Less than 100% to 600% of water is preferably immersed in water, and the air is replaced with an inert gas, and then γ-ray irradiation is performed, whereby the elution of the hydrophilic polymer is suitably suppressed. As the inert gas, nitrogen, argon, helium, carbon dioxide, or the like is preferably used, and particularly, inexpensive nitrogen is preferable. The amount of γ-ray irradiation is preferably 10 to 50 Kgy, more preferably 10 to 50 Kgy.
30 KGy. By the cross-linking treatment, the elution of the hydrophilic polymer is reduced due to the binding of the hydrophobic polymer and the hydrophilic polymer, and no peak is observed in the elution of the hydrophilic polymer in the forced elution test described later, and the semipermeable liquid is not observed. A film having an elution amount of 10 ppm or less from the film can be obtained. The elution amount here is a good solvent of a hydrophobic polymer and a hydrophilic polymer, the solubility is 0.5 g / 1 ml or more, and a certain amount of hollow fiber is dispersed and dissolved in a solvent that is not mixed with water, Next, a certain amount of aqueous phase (0.1 N-ammonium chloride solution (pH 9.
5)) Extracting the hydrophilic polymer, and means the concentration of the hydrophilic polymer in the extract. As the good solvent, for example, in the case of polysulfone and polyvinylpyrrolidone, methylene chloride is suitably used.

The semipermeable membranes produced by these methods exhibit the properties of a blood treatment membrane, such as the diffusion of uremic substances and the inhibition of albumin, a useful protein, due to the network of hydrophobic and hydrophilic polymers. However, it is characterized in that the elution of the hydrophilic polymer is small. Albumin transmittance 3%
If the ratio exceeds the above, there is a tendency to affect hypoalbuminemia or the nutritional status of the elderly, and the albumin transmittance is preferably 3% or less. Examples of the uremic substance include vitamin B12, urea, creatinine, and uric acid, and in the present invention, the clearance of vitamin B12 can be 135 ml / min or more in terms of 1.6 m2. It is practically preferable that urea, creatinine, and uric acid each have a clearance of 188, 175, and 165 ml / min or more.

In order to obtain the above characteristics,
It is preferable that the content of the hydrophilic polymer in the film after crosslinking is 2 to 6% by weight. If it is extremely low, the water wettability is reduced and causes coagulation upon contact with blood. The crosslinked film preferably contains 5 to 15% by weight of an insolubilized substance.

As described above, the semipermeable membrane for blood treatment obtained according to the present invention employs a manufacturing step of drying without a moisturizing agent attached, and a manufacturing step of cross-linking after membrane formation. Thereby, a structure in which the water permeability after drying with respect to the water permeability before drying of the semipermeable membrane is １ ／ or more can be formed. As a result, even when used in a dry state, it is possible to obtain a dialyzer having an excellent effect that a decrease in water permeability is small and a leakage of an elute is small. Because it can be used in a dry state, it is possible to provide a high-performance semipermeable membrane that is light, free from worry of freezing, easy to handle, and can contribute to reduction in dialysis cost. In addition, since dialysis performance is not significantly reduced by drying, high dialysis performance is realized even under various temperature and sterilization conditions. At the same time, the elution of the hydrophilic polymer, which is a foreign substance when viewed from the human body, can be suppressed,
The safety of the medical device can be improved. The dialyzer of the present invention is also applicable to blood treatment applications such as artificial kidneys, plasma separation membranes, and carriers for extracorporeal circulation adsorption.

[0019]

Next, the present invention will be described based on examples.

The measuring method used is as follows. (1) Measurement of Water Permeability The water pressure is 100 m inside the hollow fiber of a glass tube mini module (36 tubes: effective length 10 cm) in which both ends of the hollow fiber are sealed.
mHg was applied, and the amount of filtration per unit time flowing out was measured.

The water permeability was calculated by the following equation.

[0022]

(Equation 1)

Here, QW: filtration amount (ml) T: outflow time (hr) P: pressure (mmHg) A: membrane area (m ² ) (in terms of hollow fiber inner surface area) (2) Confirmation of performance change by drying If the humectant is not attached, it may be dried as it is under the following conditions, but if it is attached, 10 g of the hollow fiber is immersed in 150 ml of pure water and left for 24 hours to remove the humectant. . After repeating this operation twice, the bundle is dried at 100 ° C. for 24 hours in the state of a yarn bundle, and the water permeability before and after the drying is measured. (3) Measurement of solute clearance Measured based on dialyzer performance evaluation standards published by the Japanese Society for Artificial Organs, September 1982. The measurement method is 2
Although there are some types, this experiment was based on TMP of 0 mmHg.
Of the solutes, especially VB12, which is decomposed by light, it is desirable to measure it on the day of measurement after sampling. The clearance was calculated using the following equation.
For those having different membrane areas, the overall mass transfer coefficient can be calculated from the clearance and the area can be converted therefrom. clearance

[0024]

(Equation 2)

Here, CBi: concentration at the module inlet side,
CBo: Module outlet concentration QB: Module supply liquid volume (ml / min) (4) Measurement of albumin transmittance Hematocrit 30% kept in a blood tank at a temperature of 37 ° C.
Bovine blood (heparin-treated blood) having a total protein amount of 6.5 g / dl was used to pump the inside of the hollow fiber at a rate of 200 ml / min using a pump. At that time, the pressure at the module outlet side was adjusted so that the filtration amount was 20 ml / min per 1 m2 of the module area (that is, 32 ml / min at 1.6 m2), and the filtrate and the outlet blood were returned to the blood tank. One hour after the start of the reflux, blood and filtrate at the inlet and outlet of the hollow fiber were sampled, and the blood was separated into serum by centrifugation, and then BCG (Bromcresol, trade name: A / GB-Test Wako (Wako Pure Chemical)) Green) method kit, and albumin transmittance (%) was calculated from the concentration. In calculating the concentration of the filtrate, the albumin calibration curve was prepared by appropriately diluting the serum albumin included in the kit in order to obtain a calibration curve at a low concentration in order to obtain good sensitivity.

[0026]

(Equation 3)

Here, CF: in the filtrate, CBi: the module inlet, and CBi: the albumin concentration at the module outlet. (5) Measurement of the concentration of the hydrophilic polymer polyvinylpyrrolidone transferred to the aqueous layer in the forced elution test The liquid side was washed with 1 liter of pure water, and 1 g of the hollow fiber taken out of the module was dissolved in 10 ml of methylene chloride (charged amount: 10 wt / vol%), and extracted with 10 ml of a 0.1N ammonium chloride solution (pH 9.5). The obtained methylene chloride-water solution was separated as it was by an ultracentrifuge (20,000 rpm × 15 min), and the aqueous layer was filtered with a filter having a pore diameter of 0.5 μm to obtain a sample liquid.

This solution was heated at a temperature of 23 ° C. to Tosoh TSK-g.
el-GMPWXL The number of theoretical plates connected in series (8
Using a column of 900 stages x 2), 0.1N as mobile phase
-Ammonium chloride solution (pH 9.5), flow rate 1.0
The analysis was performed at a ml / min and a sample injection amount of 0.2 ml. Calibration of molecular weight was performed using 9 kinds of monodispersed polyethylene glycol as a reference substance, a calibration curve of peak area of standard PVP-concentration curve was prepared, and the concentration of PVP transferred to the aqueous layer (5 ml) was determined from the peak area of PVP of the sample. Was. P
For the sample in which VP was detected, the recovery rate (amount transferred to the aqueous phase) was obtained from the sample, and the elution amount per hollow fiber was calculated from the PVP concentration in the aqueous phase based on the recovery rate. (6) Measurement of content of polyvinylpyrrolidone by elemental analysis method The sample after γ-ray irradiation was dried at room temperature with a vacuum pump,
10 mg thereof was analyzed with a CHN coder, and the content of polyvinylpyrrolidone was calculated from the nitrogen content. (7) Measurement of insoluble matter amount 10 g of the hollow fiber membrane after γ-ray irradiation was taken and dissolved in 100 ml of dimethylformamide. 1500r with centrifuge
The insolubles are separated at pm 10 minutes and the supernatant is discarded. This operation is repeated three times, and further washed with 100 ml of pure water.
Similarly, the centrifugation operation was repeated three times, and the remaining solid matter was evaporated to dryness, and finally dried by a vacuum pump. The content of insolubles was determined from the weight. Example 1 Polysulfone (Amoco Udel-P3500) 4
Part, (Amoco Udel-P1700) 12 parts, polyvinylpyrrolidone (International Special Products Company; hereinafter abbreviated as ISP) 4 parts K30, polyvinylpyrrolidone (ISP K90) 2 parts 77 parts dimethylacetamide, and 1 part water It was dissolved and used as a film forming stock solution.

The viscosity of the stock solution was 13.4 Pa · s at 50 ° C. This undiluted solution is sent to a spinneret at a temperature of 50 ° C., and a solution consisting of 65 parts of dimethylacetamide and 35 parts of water is discharged as a core solution from a double slit tube having an outer diameter of 0.35 mm and an inner diameter of 0.25 mm, thereby forming a hollow fiber membrane. After the formation of
0 ° C., humidity controlled at a dew point of 28 ° C., passed through a 250 mm dry zone atmosphere to which a dry mist of 10 μm or less was added, passed through a coagulation bath at a temperature of 40 ° C. composed of 20% by weight of dimethylacetamide and 80% by weight of water, After passing through a water washing step at 80 ° C. for 60 seconds and a drying step at 135 ° C. for 2 minutes,
The hollow fiber membrane obtained through the crimping step at a temperature of ° C was wound into a bundle. This hollow fiber membrane is filled in a case so as to be 1.6 m ² , potted, and both ends are opened on both sides.
A dialysis module was used. After modularization, the blood side was degassed with warm water (37 ° C) and the blood side was 200 ml / m / min.
After filling for 1 minute in, the blood side was stopped, and the filling water was extruded at an inert gas (nitrogen) pressure of 0.1 MPa for 15 seconds. At this time, the hydration rate of the hollow fiber membrane was 320%.

After replacing the dialysate side with an inert gas, γ-ray irradiation (25 K
Gy). When the water permeability, clearance in each solute, and albumin permeability were measured, the clearances of urea, creatinine, uric acid, phosphoric acid, and VB12 were 195 ml / min, 185 ml / min, and 180, respectively.
ml / min, 186 ml / min, 145 ml / mi
n, water permeability 756 ml / hr / m ² / mmHg, and albumin transmittance 1.5%.

The water permeability of the dried hollow fiber is 772.
ml / hr / m ² / mmHg, and no performance decrease was observed. Furthermore, when the amount of polyvinylpyrrolidone in the hollow fiber membrane was measured by elemental analysis, it was 3.5%. In addition, the amount of insoluble matter in the hollow fiber after gamma ray irradiation was 7.2%. As a result of examining the concentration of PVP transferred from the hollow fiber membrane to the aqueous layer in the forced elution test, no peak appeared and was not detected. Example 2 Polysulfone (Amoco Udel-P3500) 4
Parts, 12 parts of (Amoco Udel-P1700), 3 parts of polyvinylpyrrolidone (ISP K30), 3 parts of polyvinylpyrrolidone (ISP K90) 77 parts of dimethylacetamide, and 1 part of water dissolved by heating to obtain a stock solution. .
The stock solution viscosity was 18 Pa · s at 50 ° C. A module was created through the same steps as in Example 1.

The water retention rate of the hollow fiber membrane after water extrusion was 330.
%Met. After γ-ray irradiation (25 KGy), the water permeability, the clearance in each solute, and the albumin transmittance were measured, and urea, creatinine, uric acid, phosphoric acid, VB1
The clearances of 2 were 193 ml / min and 18 respectively.
2ml / min, 178ml / min, 184ml / m
in, 142ml / min, water permeability 720ml / h
r / m ² / mmHg, and albumin transmittance was 1.8%. The water permeability of the hollow fiber after drying is 734 ml / hr /
m2 / mmHg, and no performance deterioration was observed.

Further, the amount of polyvinylpyrrolidone in the hollow fiber membrane was measured by elemental analysis and found to be 4.0%. The amount of insoluble matter in the hollow fiber after γ-ray irradiation was 7.8%. As a result of examining the concentration of PVP transferred from the hollow fiber membrane to the aqueous layer in the forced elution test, no PVP was detected as in Example 1. Example 3 Polysulfone (Amoco Udel-P3500) 4
Parts, (Amoco Udel-P1700) 12 parts, polyvinylpyrrolidone (ISP K30) 2 parts, polyvinylpyrrolidone (ISP K90) 4 parts 77 parts dimethylacetamide and water 1 part heated and dissolved to obtain a film forming stock solution. .
The stock solution viscosity was 23 Pa · s at 50 ° C. The module was formed through the same steps as in Example 1.

The water retention rate of the hollow fiber membrane after water extrusion is 400
%Met. After γ-ray irradiation (25 KGy), the water permeability, the clearance in each solute, and the albumin transmittance were measured. The water permeability was 702 ml / hr / m ² / mmH.
g, urea, creatinine, uric acid, phosphoric acid, clearance of VB12 are 191 ml / min and 180 ml, respectively.
/ Min, 175 ml / min, 181 ml / min,
140 ml / min, and albumin transmittance was 1.0%. The water permeability of the dried hollow fiber is 727 ml / hr /
m2 / mmHg, and no performance deterioration was observed.

Further, the amount of polyvinylpyrrolidone in the hollow fiber membrane was measured by elemental analysis and found to be 4.7%. The amount of insoluble matter in the hollow fiber after γ-ray irradiation was measured to be 8.3%. As a result of examining the concentration of PVP transferred from the hollow fiber membrane to the aqueous layer in the forced elution test, no PVP was detected as in Example 1. Example 4 Polysulfone (Amoco Udel-P3500) 4
Parts, (Amoco Udel-P1700) 12 parts, polyvinylpyrrolidone (ISP K30) 1 part, polyvinylpyrrolidone (ISP K90) 5 parts 77 parts dimethylacetamide and water 1 part heated and dissolved to obtain a film forming stock solution. .
The stock solution viscosity was 29 Pa · s at 50 ° C. The module was formed through the same steps as in Example 1.

The water retention rate of the hollow fiber membrane after water extrusion was 380.
%Met. After γ-ray irradiation (25 KGy), the water permeability, the clearance in each solute, and the albumin transmittance were measured. The water permeability was 675 ml / hr / m ² / mmH.
g, urea, creatinine, uric acid, phosphoric acid, clearance of VB12 are 190 ml / min and 179 ml, respectively.
/ Min, 173 ml / min, 179 ml / min,
138 ml / min and albumin transmittance was 0.9%. The water permeability of the dried hollow fiber was 668 ml / hr /
m2 / mmHg, and no performance deterioration was observed.

Further, the content of polyvinylpyrrolidone in the hollow fiber membrane was measured by elemental analysis and found to be 5.1%. In addition, the amount of insoluble matter in the hollow fiber after γ-ray irradiation was measured to be 8.9%. As a result of examining the concentration of PVP transferred from the hollow fiber membrane to the aqueous layer in the forced elution test, no PVP was detected as in Example 1. Example 5 Polysulfone (Amoco Udel-P3500) 4
Parts, 12 parts of (Amoco Udel-P1700), 6 parts of polyvinylpyrrolidone (K90 of ISP), 77 parts of dimethylacetamide, and 1 part of water were heated and dissolved to prepare a film forming stock solution. The stock solution viscosity was 38 Pa · s at 50 ° C. The module was formed through the same steps as in Example 1.

The water retention rate of the hollow fiber membrane after water extrusion is 350
%Met. After γ-ray irradiation (25 KGy), the water permeability, the clearance in each solute, and the albumin transmittance were measured. The water permeability was 620 ml / hr / m ² / mmHg,
The clearances of urea, creatinine, uric acid, phosphoric acid and VB12 are 189 ml / min and 177 ml / m, respectively.
in, 169 ml / min, 178 ml / min, 13
7 ml / min and albumin transmittance was 0.8%.
The water permeability of the dried hollow fiber is 656 ml / hr / m2.
/ MmHg, and no performance degradation was observed.

Further, the amount of polyvinylpyrrolidone in the hollow fiber membrane was measured by elemental analysis and found to be 5.5%. In addition, the amount of insoluble matter in the hollow fiber after γ-ray irradiation was measured to be 9.2%. As a result of examining the concentration of PVP transferred from the hollow fiber membrane to the aqueous layer in the forced elution test, no PVP was detected as in Example 1. Comparative Example 1 Polysulfone (Amoco Udel-P3500) 18
Parts, polyvinylpyrrolidone (BASF K90) 3 parts,
6 parts of polyvinylpyrrolidone (BASF K30) were heated and dissolved in 72 parts of dimethylacetamide and 1 part of water to prepare a film forming stock solution. The stock solution viscosity was 70 Pa · s at 30 ° C.
This stock solution was sent to a spinneret at a temperature of 50 ° C.
A solution composed of 65 parts of dimethylacetamide and 35 parts of water was discharged as a core liquid from a double slit tube having a diameter of 5 mm and an inner diameter of 0.25 mm to form a hollow fiber membrane.
After passing through a dry zone atmosphere having a dew point of 28 ° C. and a humidity control of 250 mm, a coagulation bath containing dimethylacetamide (20% by weight) and water (80% by weight) at a temperature of 40 ° C. is passed. The obtained hollow fiber membrane was used as a wound bundle. After the glycerin was drained, the case was filled, potted, and the ends were opened on both sides to produce a module. After glycerin was washed out and filled with water, 25 kGy of γ-ray irradiation was performed. When the water permeability, clearance in each solute, and albumin permeability of this module were measured, the clearances of urea, creatinine, uric acid, phosphoric acid, and VB12 were 194, respectively.
ml / min, 185 ml / min, 176 ml / mi
n, 183 ml / min, 135 ml / min, water permeability 716 ml / hr / m ² / mmHg, and albumin transmittance 0.7%.

The amount of polyvinylpyrrolidone in the hollow fiber membrane was measured by elemental analysis and found to be 4.5%. Further, the insoluble matter content of the hollow fiber was measured, and it was 8.0%. As a result of examining the concentration of PVP transferred from the hollow fiber membrane to the aqueous layer in the forced elution test, no PVP was detected as in Example 1. Next, the filling liquid of the module was drained, and the hollow fiber membrane was dried with a dryer as it was, and the water permeability, the clearance in each solute, and the albumin transmittance were measured, and urea, creatinine, uric acid, phosphoric acid, and VB12 were removed. Clearance is 186ml / min and 177ml respectively
/ Min, 169 ml / min, 176 ml / min,
119 ml / min, water permeability 10 ml / hr / m ²
/ MmHg and albumin transmittance of 0.1%, a significant decrease in performance was observed. Even when the hollow fiber before drying was taken out of the module and dried by the method described above, a decrease in water permeability was also confirmed.

[0041]

According to the present invention, a dialyzer for blood treatment incorporating a semi-permeable membrane of a dry type having advantages such as lightness and non-freezing and having excellent water permeability and dialysis performance. Can be provided.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C077 AA05 BB01 KK12 KK21 LL01 LL05 LL11 PP15 PP18 4D006 GA13 HA02 JA02C JA13A JA70A JB05 MA01 MB02 MB20 MC40 MC62 MC85 MC86 MC89 NA10 NA63 NA64 NA75 PB09 PB52 PC41 PC47

Claims (4)

[Claims] 1. A blood treatment dialyzer having a built-in semipermeable membrane containing a hydrophobic polymer and a hydrophilic polymer as a constituent component, wherein the semipermeable membrane has a water permeability after drying as compared to a water permeability before drying. A blood treatment dialyzer wherein the clearance of vitamin B12 of the dialyzer is at least 135 ml / min in terms of 1.6 m ² . 2. The blood treatment dialyzer according to claim 1, wherein the hydrophobic polymer is a polysulfone resin and the hydrophilic polymer is polyvinylpyrrolidone. 3. The blood treatment dialyzer according to claim 2, wherein the content of polyvinylpyrrolidone is 1 to 10% by weight based on the polysulfone resin. 4. The blood processing dialyzer according to claim 1, wherein the albumin transmittance is 3% or less.