JPS607856A - Anionic body fluid treating membrane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylindrical pore Ilλ suitable for separation of body fluid components by microfiltration, 'fA reduction, and in particular for separation of blood cells and cells.

In particular, it is possible to separate cancer cells in ascites, and to remove plasma 'fc' without damaging or leaking blood cell components and platelets in the blood.
The present invention relates to a vinyl alcohol-based porous membrane having a negative charge and suitable for being distributed from house to house.

As plasma separation membranes and ascites concentration membranes, conventional →z luulose acetate) [, d'' lipinyl alcohol membrane, = r; lipropylene membrane, polymethyl megcryl 1- It!

Polyethylene membranes, polysulfone membranes, etc. are well known, but
Those having ionic groups are only briefly mentioned in JP-A-56-57856. In order to efficiently separate plasma from blood, in which blood cells and platelets are suspended in a concentrated serum protein solution, it is desirable that the pore size of the membrane be as large as possible without leakage of platelets. As the pore size increases, the pressure resistance of the membrane decreases; however, the pressure resistance required for medical membranes is as low as 500 ffWH, so there is usually little problem. In addition, the decrease in mechanical strength of membranes due to larger pore diameters makes it difficult to handle the membranes when making them into modules. It can offset the shortcomings to a large extent. The biggest and essential problem with increasing the pore size is leakage of red blood cells and hemolysis. Red blood cells are disk-shaped objects with a diameter of 8 μm and a thickness of about 1.5 to 2 μm with a concave center, but when they deform and pass through the capillary blood vessels of about 0.7 to 1 μm, they stagnate. This causes leakage of blood cell components, clogging of membrane pores, and hemolysis. Therefore, the average pore diameter of currently known plasma separation membranes is currently suppressed to about 0.2 to 0.5μ, taking into account the entire pore size distribution, but even so, considerable hemolysis and blood cell and protein components still occur. clogging and a corresponding decrease in plasma separation rate over time are unavoidable. As a result of intensive research to solve these problems, the inventors of the present invention unexpectedly found that vinyl alcohol containing groups that can be ionized into anions in water within the range of 0.5 to 45 m/h We have discovered that porous membranes made of polymers have less hemolysis even with larger pore diameters than conventional plasma separation membranes, less decrease in plasma separation rate over time, and superior blood affinity, leading to the present invention. .

That is, the present invention comprises a polymer containing at least 25 moles of vinyl/L' 7 /L' cole residues and 0.5 to 45 moles of groups capable of dissociating with anions in water, and has a porosity of 40%. Above 85%, water permeability 500"/mrHq
, v? -hr JU Upper+A body fluid treatment membrane with a serum albumin rejection rate of 20% or less. The present invention will be explained in more detail below.

In the present invention, body fluids include blood, plasma, serum, lymph fluid, bone marrow fluid, ascites fluid, and fluids that have undergone some treatment, such as removing white blood cells, removing cholesterol, or cooling ( It is a general term for products that are heated (heated) to form a protein gel or that have hydroxyethyl starch added to them.

As the material for the membrane in the present invention, it is necessary to use a polymer containing at least 25 mol% of vinyl aryl residue. Such polymers include polyvinyl alcohol or vinyl alcohol copolymers, for example, at least one of olefins such as ethylene and propylene, styrene, vinyl chloride, acrylonitrile, acrylic acid and its derivatives, and #acid vinyl Examples include saponified products of copolymers with vinyl esters such as /L'. Among these polymers, ethylene vinyl (7-call copolymer) is preferred because it has excellent antithrombotic properties.

Here, the ethylene residue in the ethylene-vinylalfur copolymer is at least 10%, preferably 20% to
It is 50 mol%.

It is necessary that the vinyl alcohol residue in the polymer be at least 25 moles. When it is less than 25 mo/I/%, the affinity with blood decreases. The reason for this is not clear, but it is thought that it exerts the effect of gently adjusting the balance between hydrophilicity and hydrophobicity of the polymer, which is one of the important factors for anticoagulant properties, through water utilization of hydroxyl groups. The preferred content of vinyl alcohol residue is 50 to 95 mol%
It is.

Here, the content of vinyl alcohol/l/residue is n
It is the ratio of the number of vinyl alcohol monomers to the number of unit monomers (residues) of the polymer constituting the polymer.

The content of groups that can be ionized into anions in water (hereinafter referred to as anionic groups) in the polymer is 0.3 mo) V% ~
45) V%. The content herein refers to the ratio of anionic groups to the number of residues per unit of the polymer constituting the membrane.

When the content of anionic groups is less than a3 mo/l/poly, there is no effect of keeping the plasma filtration rate stable over time when the pore size becomes larger than 0.05 μ. On the other hand, the upper limit is 45 moles, but if it exceeds this, the membrane will swell to a large extent and its pressure resistance will drop significantly, making it necessary to carry out a large amount of crosslinking, which will reduce the filtration rate.

Protein permeability also decreases, which is not preferable.

For the crosslinking reaction, known general methods can be used. Examples include crosslinking reactions caused by radiation and light such as rays and electron beams. A crosslinked structure can be introduced by copolymerization with a polymer having a crosslinked structure in advance. Further, a crosslinking reaction can also be carried out during polymerization and film formation. In particular, a step in which only a crosslinking reaction is performed may be performed. If necessary, a crosslinking reaction can be carried out after film formation. Also acecoolization and esterification.

Various reactions including etherification can also be carried out at any time. Although these are not crosslinks, they are meaningful in adjusting the hydrophilicity and hydrophobicity of the membrane.

Examples of ionic groups include carboxyl groups, sulfonic acid groups, sulfinic acid groups, phosphonic acid groups, phosphonic acid groups, and salts thereof, phenolic hydroxyl groups and salts thereof, esters such as sulfates, phosphates, and Examples include salt. Two or more types of these groups may be present in the same residue, or two or more types of these groups may be present in the polymer forming the membrane. The ionic group can be introduced into the membrane-forming polymer by copolymerizing a vinyl monomer, polymer, or multicomponent copolymer containing the ionic group with the polymer. Alternatively, it can also be introduced by a chemical reaction after polymerization. An ionic group may be introduced by light, radiation, or the like.

Further, if necessary, it may be introduced after film formation or after molding into a module.

Introduction of anionic groups includes acetalization, esterification, etherification, sulfonation, oxidation, 'I1 element, addition,
Known reactions such as substitution, exchange, and graffiti can be used. The solvent 2 reactants, catalysts, etc. used must be thoroughly removed before treatment of body fluids.

The membrane used in the present invention has a porosity of 40% to 85%, a water permeability of 500"/vrmHg, i, hr or more, preferably 2000 ytl/MMg, 7?/mmr or more, and serum albumin ( Molecular weight 67, ooo) has a rejection rate of 2
It is 0% or less, preferably 10% or less. If the porosity is smaller than this, or if the water permeability is smaller than this, the r-pass rate of body fluid, which is a concentrated protein solution, will be small, and the p-pass rate will decrease greatly over time due to clogging. On the other hand, the porosity is 8
If it exceeds 5%, hemolysis is likely to occur, and the strength of the membrane is extremely insufficient, making it difficult to assemble it into a module. Furthermore, if the inhibition rate of serum albumin, which is the main protein component in body fluids, exceeds 20%, the plasma p overrate will be too small. It is more preferable that the cholesterol inhibition rate is 25% or less.

When the membrane of the present invention is used for plasma separation and ascites concentration, the effect of the water washing invention, which has many pores with a pore diameter of 0.05 μ or more, preferably 0.2 μ or more, is remarkable, and the membrane of the present invention has a remarkable effect on blood cells, platelets, and cells. Leakage is prevented, the amount of solution is small, the flow rate of plasma and ascites is high, and it is stable over time. However, these effects become unclear when the pore size exceeds 5μ gold. The reason for this is not clear, but because the surfaces of blood cells, platelets, and cells are slightly negatively charged, electrical repulsion acts on the membrane, causing these formed components to clog the membrane pores. It is presumed that this is because it suppresses adhesion.

Next, the method for forming the body fluid treatment membrane of the present invention will be described in more detail. The average molecular weight of the polymer that forms the membrane is approximately 3
More than 10,000. Usually about 65,000 to 200,000 is used. The higher the average molecular weight, the better the mechanical properties of the membrane. The solvent for the polymer is water or an organic solvent,
Select a material that can completely dissolve the raw material polymer and can be quickly dissolved in the coagulation bath. For example, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, tetofhydrofufurn, pyrrolidone, N-methylpyrrolidone,
and monohydric alcohols such as methanol, ethanol, and isoflobanol, polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin, puenol, metacresol, formic acid, and mixtures thereof.

In order to obtain a porous membrane as used in the present invention, a thin liquid solution containing only a polymer and a solvent may be used, but additives are usually added to the solution for forming pores in order to form pores. Examples of additives include inorganic acids and inorganic salts such as boric acid, mirabilite, and calcium carbonate, organic acids and their salts, alkalis, polyethylene glycol, polypropylene glycol, nonsolvents such as acetone, hexane, and benzene, colloidal silica, Dispersoids such as finely divided silica can be used. The amount of these substances added should be 10% or more based on the ratio of rice to polymer6.
00% or less, preferably 50% or more and 200% or less. If it is less than this, it is difficult to obtain a membrane with a serum albumin rejection rate of 20% or less, and if it is more than this, the porosity is too large and the mechanical strength is insufficient.

The concentration of the polymer in the membrane forming stock solution is in the range of 5 to 50% by weight, preferably 10 to 35% by weight. At lower concentrations, the viscosity is too low, and at higher concentrations, the viscosity is too high, making it difficult to stably obtain a uniform film.

The temperature of the film forming stock solution is 0°C to 120°C, preferably 5°C.
~95°C is good. At temperatures lower than this, the viscosity is too low, making it difficult to manufacture, and at temperatures higher than this, there is a risk that the polymer may decompose or change in quality.

The film-forming stock solution obtained in this way is formed into a film by various known wet coagulation methods or wet-dry coagulation methods.

To name a few examples, there is a method of extruding the membrane forming stock solution through a die with elongated null holes and assimilation by contacting or immersing it in a coagulation bath, forming a flat film, and forming a membrane using a die with annular holes. Examples include a method of extruding a stock solution to form a tubular or hollow fiber membrane. Alternatively, the film may be formed by casting the film-forming stock solution into a desired shape, or by contacting it in a coagulation bath while casting, or by immersing it in a coagulation bath.

As the coagulation bath, one is used that has high compatibility with the solvent of the membrane-forming stock solution and has substantially no compatibility with the components forming the membrane. Generally water and methanol.

Monohydric alcohols such as ethanol, polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin, acetone, or mixtures thereof are used.

In order to adjust the coagulation rate or to control gelation or phase separation, miscible organic solvents, inorganic salts such as mirabilite and calcium chloride, acids, alkalis, etc. may be added to the coagulation bath.

In special cases, only one side of the film is in contact with the coagulation bath, and the other side is exposed to a gas such as air, nitrogen, or benzene,
The process is carried out in contact with a liquid that is immiscible with both the solvent of the film-forming stock solution and the coagulation bath, such as toluene, hexane, and mercury.

In some cases, as in JP-A-55-148209, the material is passed through a gas phase immediately before contacting the coagulation bath.

The temperature of the coagulation bath is an important factor in obtaining a membrane with performance suitable for body fluid treatment, and is generally in the range of -10°C to 50'Q, with the preferred 1fC being in the range of 10 to 41'C. At lower temperatures, solidification is slow and the pore size becomes too small. At higher temperatures, the solidification rate is too fast, resulting in excessive porosity and spots.

After leaving the coagulation bath, the membrane is further stretched as necessary.

Heat treatment and cleaning can be performed.

However, the membrane according to the invention can be used as a wet or dry membrane. Drying methods include direct drying with a button such as air flow, heat rays, electromagnetic waves, etc., as well as methods such as replacing the water contained in the membrane with an organic solvent that is miscible with water and does not dissolve the polymer (e.g. acetone, methanol, tetofhydrofuran, etc.). Then, the organic solvent is removed by reduced pressure, heating, etc., or glycerin or ethylene glycol during or after film formation.

A method of treating with an aliphatic polyhydric alcohol such as polyethylene glycol and subsequent drying, or a method of freezing a water-containing film with liquid nitrogen or carbon dioxide gas and freeze-drying it, etc. can be used.

When modularizing the membrane of the present invention, the best shape is a hollow fiber type, but it is also possible to use other known shapes such as a flat membrane type, keel type, coil type, spiffle type, or tubular type. I can do it! When used in the form of a hollow fiber membrane for Samurai, the inner diameter is 40 to 6000μ, preferably 80 to 800μ.
μ and film thickness are preferably in the range of 200 μm or less.

When performing plasma separation using the membrane of the present invention, it is extremely effective to use a system such as an IV tube. That is, it is a device that completely separates plasma using an anionic porous membrane and processes the obtained plasma using another module, which includes a blood inflow circuit equipped with pump M+i and an anionic membrane connected to the blood inflow circuit. A porous membrane module (first membrane 7JL-), a blood outflow circuit connected to it, and a plasma processing module /L/(second module / a plasma processing module connected to the plasma introduction circuit, a circuit connected to the plasma processing module for deriving the processed plasma, and a filtration pressure (TMP) of the first membrane module.
) to prevent substantial depressurization.Using a system similar to a pressure regulator equipped with at least a pump M, it is possible to remove unnecessary components in plasma at the same time as plasma separation, making it extremely effective. It is. Examples of such systems are shown in FIGS. 1 to 3. P in the figure is a pressure gauge.

M represents a pump, ■ represents a valve, and F represents a flow meter.

In order to prevent the filtration pressure in the first anionic porous membrane module from becoming equal to the pressure relief, pressure gauge P2 and pump Δ12 are used in Figure 1, flow meter F1 and pump 8 [in Figure 2], but valves are used in Figure 6. V1 and pump M2 are controlled in conjunction.

The second module for plasma processing may be a membrane for fractionating plasma components or an adsorbent.

In this application, water permeability, porosity, and rejection were measured as follows.

(1) The water removal rate was measured at 37°C and 5 to 50 degrees IIq, and the water removal performance was evaluated.

K'-■/A-t・ΔP (Ginketsu hr, Tomo H,)■: Permeated water amount (fu/), A: Membrane area (m')t: Permeation time (h
r), ΔP: Measured pressure (mallg) (2) The porosity was calculated from the following formula.

PD (4---) weight after removing moisture) (6) For the inhibition rate, fresh blood with a hemadcrit of 65% is used.
57°C, TMP5~50g, QB = 10
0 yxl/plot.

The measurement was performed under the condition that the membrane area was 0.5 WI.

The present invention will be further explained below with reference to Examples.

Example 1 Saponification & s + a, s mol, polyvinyl alcohol with a degree of polymerization of 2400, vs. polyvinyl alcohol
-Polyethylene glycol 1000 with a polyurethane ratio of 91.5
(!:, Polyvinyl alcohol/I/concentration 17% solution was obtained by heating and dissolving 4th boric acid and 0.4% acetic acid.

This film-forming stock solution is discharged from an annular nozzle, and while dilute alkali is injected from the inner core of the annular ring, 15% of mirabilite and 8% of caustic soda are added.
The fibers were solidified into hollow fibers in a pseudo-solid bath containing 50% of the solidified material, and then placed in an acidic bath and crosslinked with boric acid. Further, crosslinking with glutaraldehyde was carried out by immersing it in solution 18 at 60° C. containing 3% glutaraldehyde, 5% sulfuric acid, and 12% Glauber's salt for 15 minutes.

The obtained inner diameter was 350μ, film thickness was 100μ, porosity was 52%,
90% rejection of 0.2μ latex particles at 0.1% concentration
Hollow fibers with a vinyl alcohol/l/residue content of 73% were used as a total control, which was further treated with 2% Na orthovaldehyde sulfonate, 10% sulfuric acid, 10% Glauber's salt and 70'C. The mixture was treated in a sulfonation bath for 4 hours. The sulfonated hollow fiber has an inner diameter of 440μ and a membrane thickness of 150μ.
, porosity 63%, sulfone ([5,2 mol %
, vinyl alcohol residue content 67.8
% porous hollow fiber, water permeability is 2900 fl/l
mHg-2&hr serum albumin inhibition rate was 0%. This sulfonated polyvinyl alcohol porous membrane and the control membrane were measured using a conventional method to determine the inner diameter of II! 4 area 0.577
/ was molded into a cylindrical module, and a live blood plasma separation test was conducted using these two types of modules. The results are shown in Table 1. Compared to the control membrane, the polyvinyl alcohol porous membrane with usulfone groups had a larger plasma p transit rate and was stable over time, had a higher serum protein permeability, and had less hemolysis.
There is no platelet leakage, and water permeability recovers well after blood return.

Table 1 Example 2 Ethylene content 65%), saponification R99,13
Saponified copolymer of ethylene-vinyl acetate (mo/l/%) and polyethylene glycol 6oo' (dissolved in I-dimethyl sulfoxide to a concentration of 20% by weight of ethylene vinyl l/l/%), polyethylene glycol b o o
) A membrane forming stock solution of 19 degrees and 26% was obtained. The nozzle hole diameter is 650 μm, and the outer diameter is 250 μm.

The needle is discharged from an annular nozzle with an inner diameter of 90 μm, and 0.0 μm is discharged from the needle. , 42 Me/, , was coagulated in a 20% aqueous solution of dimethyl sulfoxide at 20° C. while nitrogen gas of 42 Me/. After sufficiently removing polyethylene glycol 600 by washing with hot water, replacement with acetone was performed, and then drying was performed in an air stream at 25°C.

The obtained hollow fiber has an inner diameter of 220 μm and an outer diameter of 38 μm in the dry state.
It was a porous film with a thickness of 0μ and a film thickness of 8oμ. This hollow fiber 56
80 pieces were bundled and both ends thereof were fixed to a cylindrical housing with polyurethane resin to produce a module /I/ (effective membrane surface @ 0.8 y#). A 15% polyethylene glyco~lv (molecular it 400) maleate solution of maleic anhydride was introduced inside the hollow fibers of this module, and esterification was performed at 70'C for 4 hours to bond carboxyl groups, followed by hot water treatment. Washed for 2 hours.

The vinyl alcohol residue content of the maleated ethylene vinyl/l/m hollow fiber is 64.5 mol%, the maleic acid group content is 25 mol/l/m, and its inner diameter is 2
80μ, outer diameter 460)i, porosity 58.

Water permeability was 947 M'/xmHg, vl-hr.

-7V, (Table 2 shows the results of a plasma separation test using bovine blood using the module before conversion and the module after maleation. Porous membrane with anionic groups The effect is clear.

Table 2 Example 5 Contains ethylene! 32 mol%, saponified ff9s+, a mol%
Chips of the saponified ethylene-vinyl acetate copolymer were dispersed in a mixed aqueous solution of 10 parts of sulfuric acid, 10% of Glauber's salt, and 5% of sodium benzaldehyde sulfonate, and an acecooling reaction was performed at 70°C for 5.5 hours. A polymer having an average molecular weight of 42,000 and containing 5.4 mo/I/% of sulfonated vinyl alcohol residues was obtained. After thorough washing and drying, the polymer was treated with dimethyl sulfoxide K 80.
'C and further polyethylene glycol/v6aa
was added to obtain a membrane forming stock solution with a polymer concentration of 20 and a polyethylene glycol concentration of 26%. Nozzle hole diameter is 650
μm, = -F'/L/outer diameter is 25Q/Zln,
This original i
J was discharged and coagulated in water at 23°C while nitrogen gas of 0.42"/xi* was discharged from the needle. Hereinafter, in the same manner as in Example 2, 5000 porous hollow fibers were prepared. Soju/I/ with 0 and 7 doors was produced.The inner diameter of this hollow fiber was 294 μ, the outer diameter was 470 μ, the porosity was 73, and the water permeability was 3500 M</luHg-ytl-
It was hr.

Also, the plasma separation test results using this module were good as shown in Table 6.

Table 3 Example 4 The 0.5yd module prepared in Example 1 was set in the apparatus shown in Figure 1, and double filtration plasmapheresis of bovine blood was carried out. Human blood to the anionic plasma separation membrane has a hematocrit of 35% and a total protein of 6.7'/lt.
t, in7 rubumin 4'/die total colesf 0-
The flow rate is 100N.4. It is. The obtained plasma was filtered through a plasma processing membrane while controlling the plasma molecule iBIJTMP at 10 HzH4.
The 0-fold concentrated plasma was discarded 7, and the same amount of new plasma was added in its place, mixed with the blood concentrated by the plasma separation membrane together with the added fluid, and circulated. The average plasma separation rate of the anionic plasma separation membrane during the 4-hour test was 211%+, which was high and stable, with little hemolysis, and the plasma processing membrane was effective in removing about 50% of cholesterol-V. Admitted. In addition, the pressure controllability and operability of the device were both good.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 5 are process diagrams showing an example of plasma separation carried out using the anionic body fluid treatment membrane of the present invention. In the figure, P+, P'1. P2. P5...Pressure gauge M1. M2, Ms...Pump F
1 ......Flowmeter V1. V2......Indicates a valve. Patent Applicant RiRa Shi Co., Ltd. Agent Patent Attorney Ken Honda Figure 1 Figure 2

Claims (1)

[Scope of Claims] (1) Contains at least 25 moles of vinyl alcohol/V residue, and contains 0.3 to 0.3 to
Made of a polymer containing 45 m/I/%, a porosity of 40% to 85%, and a water permeability of 500πI7/2. Ga, h
1. A body fluid treatment membrane with a serum albumin inhibition rate of 20% or less. (2) The body fluid treatment membrane according to claim 1, which has a rejection rate of 5μ particles of 90% or more. (6) The body fluid treatment membrane according to claim 1 and claim 2, which contains at least 10 mol% of ethylene residue. (4) The body fluid treatment membrane according to claim 1, 2, or 6, wherein the group capable of dissociating into an anion in water is a sulfuric acid ester, a sulfonic acid, or a salt thereof. (5) The body fluid treatment membrane according to claim 1, 2, or 6, wherein the group capable of dissociating into anions in water is a carboxyl group or a salt thereof.