JPS6256765B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing a flat membrane type permeable membrane. More specifically, the present invention relates to a method for manufacturing a flat membrane type permeable membrane suitable for filtering body fluids such as blood, ascites, and pleural fluid. (Prior Art) Artificial kidney devices, plasma separation devices, etc. that utilize osmosis, ultrafiltration, etc. have recently made remarkable progress and are widely used in the medical world. Among such devices, a flat membrane-like permeable membrane is the most important component in certain types of devices. Typical examples of these flat membrane-like permeable membranes include acrylonitrile-sodium methacrylsulfonate copolymer membranes, polyether-carbonate membranes, cellulose acetate membranes, ethylene-vinyl acetate copolymer membranes, and copper ammonia membranes. There are regenerated cellulose membranes, etc. (Problems to be Solved by the Invention) However, all such permeable membranes mainly allow the permeation of substances with small molecular weights such as urea and vitamin _B12 , and have very little permeation of substances with medium molecular weights. When used in an artificial kidney device, the drawback was that melanin pigment gradually accumulates as dialysis is repeated. Therefore, an object of the present invention is to provide a novel method for manufacturing a flat membrane type permeable membrane. Another object of the present invention is to provide a method for producing a flat membrane-type permeable membrane that is capable of permeating substances with medium molecular weight or higher. (Means for Solving the Problems) These objects are produced by the reaction between ammonium or alkali metal salt of a polymer having a number average molecular weight of 500 to 200,000 and containing 10 to 70 equivalent % of carboxyl groups and cuprammonium cellulose. A stock solution composition containing a substance is discharged in the form of a flat film from a slit-like extrusion hole, and the stock solution composition discharged in the form of a flat film is further passed between at least two rollers to regulate the thickness. It is immersed in dilute sulfuric acid to solidify and regenerate.
This is achieved by a method for producing a flat membrane type permeable membrane, which further comprises immersing the polymer in a strong alkaline aqueous solution to remove ammonium or alkali metal salts of the polymer. (Function) In the present invention, the polymer to be reacted with cuprammonium cellulose contains in its constituent monomer units
number average molecular weight 500 to 200000, containing 10 to 70 equivalent %, preferably 15 to 50 equivalent % of carboxyl groups,
Preferably, it is a polymer or copolymer having a molecular weight of 1,000 to 100,000. This polymer is used as an ammonium salt or an alkali metal salt such as lithium, sodium, potassium, etc., preferably as an ammonium salt. The reason why the polymer is used as the above-mentioned salt is to dissolve it well in the copper ammonia cellulose stock solution and facilitate the reaction. The reason why the polymer needs to contain 10 to 70 equivalents of carboxyl groups is to form a coordination bond with the copper of cuprammonium cellulose in the stock solution. That is, the carboxyl group content is 10
If the content is less than equivalent %, the amount of coordination with the copper will be insufficient, while if the carboxyl group content exceeds 70 equivalent %, the amount of coordination with the copper will be too large, causing gelation. The reason why the number average molecular weight of the polymer having a carboxyl group is within the above range is that, as will be described later, after regenerating and coagulating the formed membrane, by further removing the polymer, the permeable membrane has the molecular weight within the above range. This is because a large number of micropores with a size corresponding to the chemical structure are formed.
This is because by using a polymer having a molecular weight within this range, a permeable membrane capable of dialyzing a substance having a predetermined molecular weight can be obtained. There are various polymers containing carboxyl groups, but one example is a copolymer of a carboxyl group-containing unsaturated monomer such as acrylic acid or methacrylic acid and another copolymerizable monomer. . Therefore, as copolymerizable monomers, alkyl acrylates such as methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, lauryl acrylate, alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, acrylamide, methacrylate, etc. Examples include amide, acrylonitrile, methacrylonitrile, hydroxyalkyl acrylate (or methacrylate), dialkylaminoacrylate (or methacrylate), vinyl acetate, styrene, vinyl chloride, ethylene, etc., with alkyl acrylate and alkyl methacrylate being particularly preferred. Therefore, the most preferred copolymers are acrylic acid-alkyl acrylate (or methacrylate) copolymers, methacrylic acid-alkyl acrylate (or methacrylate) copolymers, and partial hydrolysis products of alkyl acrylates (or methacrylates). . Salts of these carboxyl group-containing copolymers are
Usually 1 to 40 parts by weight, preferably 2 to 30 parts by weight, most preferably 3 parts by weight, per 100 parts by weight of cellulose.
~15 parts by weight are used. The reason why the amount of the salt used is within this range is that the amount of the salt used determines the amount of micropores to be formed, as will be described later.
That is, if it is less than 1 part by weight, it is too small and the ability to permeate a substance with a predetermined molecular weight is low, while if it exceeds 40 parts by weight, the strength of the resulting permeable membrane will be reduced. The cellulose preferably has an average degree of polymerization of 500 to 2,500, and most preferably has an average degree of polymerization of 1000±100. The cuprammonium cellulose solution is prepared by a conventional method. For example, first, aqueous ammonia, a basic aqueous copper sulfate solution, and water are mixed to prepare an aqueous cupric ammonia solution, an antioxidant (e.g., sodium sulfite) is added thereto, and then raw material cellulose is added and dissolved with stirring.
Further, an aqueous sodium hydroxide solution is added to completely dissolve undissolved cellulose. A predetermined amount of the salt of the polymer as a permeability control agent is mixed and dissolved in the cuprammonium cellulose solution obtained in this manner, and the mixture is heated at a temperature of 8 to 30°C, preferably 14 to 25°C.
The solution is stirred for 20 to 120 minutes, preferably 60 to 100 minutes to coordinate the copper ammonia cellulose, and further aged to obtain an inhibitor stock solution. Therefore, a typical composition of the stock solution is as follows (parts by weight). Cellulose 100 Carboxyl group-containing polymer salt 3-15 Basic copper sulfate 50-200 Sodium sulfite 25-50 Sodium hydroxide 10-50 Ammonia 100-300 Water 1000-2000 Next, a method for manufacturing the permeable membrane will be described. That is, a copper ammonia cellulose stock solution to which a predetermined amount of a carboxyl group-containing polymer salt has been coordinately bonded is discharged from a slit-shaped extrusion hole, and the stock solution composition discharged in the form of a flat film is passed between at least two rollers. This is then immersed in dilute sulfuric acid to regenerate solidification. There are various methods for forming the stock solution into a flat film shape, but one example is as shown in FIG.
The stock solution 3 discharged in the form of a flat film is transferred to rollers 4,
The coagulating liquid 6 in the coagulating tank 5 has its thickness regulated by 4.
The material is immersed in water, passes through the deflection rod 7, solidifies during that time, and is pulled up by rollers 8. As another method, as shown in FIG.
3 is adhered to the surface of the rotating drum 26a, and the thickness is regulated by pressing with the roller 24, and then the drum 26b rotates in contact with the rotating drum 26a,
Further, it is solidified while being transferred to the rotating drums 26c and 26d, and then pulled up via rollers 28a and 28b. The concentration of the dilute sulfuric acid solution used is 5-50%,
It is preferably 15 to 30%. Then, the attached sulfuric acid is removed by washing with water. Next, the film-like material formed by such solidification and regeneration is subjected to decopper treatment to remove copper remaining in the film-like material, if necessary, and then washed with water. Copper removal treatment is usually carried out by immersion in a dilute sulfuric acid solution or nitric acid solution with a concentration of 3 to 30%. Next, this film-like material is immersed in a strong alkaline aqueous solution to remove the carboxyl group-containing polymer, thereby forming micropores in the membrane wall of the film-like material corresponding to the molecular weight of the polymer used. Copper still remaining after treatment with hot water at 5 to 100 °C, preferably from 50 to 80 °C, or plasticized with an aqueous glycerin solution with a concentration of 1 to 10% by weight, preferably 2 to 5% by weight,
Cupric sulfate, copper hydrogen sulfate, medium-low molecular weight cellulose, etc. are removed, then dried and wound up to obtain the desired permeable membrane. The thickness of the permeable membrane thus formed is 5 to 30 microns, preferably 8 to 20 microns. Examples of strong alkalis include sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, etc., with a concentration of 0.1 to 20%, preferably 1 to 15%.
% aqueous solution. According to the present invention, the effect of adding the permeability control agent (pore size control agent) is to form in the permeable membrane pores (voids) with a pore diameter corresponding to the molecular weight of the permeability control agent, so the permeation membrane has many pores. If this happens, the apparent density of the film will become smaller. For example, when a permeable membrane is obtained by adding the permeation performance controlling agent (ammonium salt of acrylic acid-methyl methacrylate copolymer with a number average molecular weight of about 50,000) according to the present invention to cuprammonium cellulose having a density of 1.50, the apparent density is , as shown in the following table. Addition amount (parts by weight/100 parts by weight) Apparent density 0 1.50 2 1.47 10 1.35 15 1.28 20 1.20 25 1.13 30 1.05 35 0.98 40 0.90 (Example) Next, examples will be given and permeation using the stock solution according to the present invention will be explained. The case of manufacturing a membrane will be explained in detail. In addition, in the following examples, all percentages are by weight unless otherwise specified. Example 1 A copper ammonia aqueous solution was prepared by mixing 4132 g of a 28% ammonia aqueous solution and 1870 g of a 44% basic copper sulfate suspension aqueous solution, and 2730 g of a 10% sodium sulfite aqueous solution was added thereto. This solution has a degree of polymerization of approximately 1000.
860 g of cotton linter pulp was added to stir the solution, and then 1600 g of a 10% aqueous sodium hydroxide solution was added to prepare an aqueous cuprammonium cellulose solution. To this aqueous solution, 160 g of an ammonium salt of an acrylic acid-methyl methacrylate copolymer having a number average molecular weight of about 50,000 and containing 18.0 equivalent % of carboxyl groups was added, and the mixture was cooled to about 25°C.
The mixture was reacted with stirring for 60 minutes at a temperature of 100 mL, and further aged to obtain a stock solution. As shown in FIG.
1 and discharged from the slit-shaped extrusion hole 22 at a nitrogen pressure of 3.5±0.5 Kg/cm ² . The width of the extrusion hole is 100
mm, the length was 50 mm, and the discharge rate of the stock solution was 6.45 ml/min. The discharged film-like material is deposited on the surface of the rotating drum 26a, and while the thickness is controlled by pressing with the roller 24, it is sequentially transferred onto the surfaces of the drums 26b, 26c, and 26d, which rotate while in contact with each other, while being transferred to the coagulation tank. It was coagulated with a 20% dilute aqueous sulfuric acid solution in a bath temperature of 20° C. in the drum 25, and then peeled off from the rotating drum 26d and pulled up through rollers 28a and 28b. The speed at this time was 50 m/min. Next, it was introduced into a bathtub with a bath temperature of 20°C, and washed with water at a bath length of about 4 m, and the film-like material thus formed was run in a copper removal bath filled with a 5% sulfuric acid aqueous solution at a bath length of 12 m. Thereafter, the copolymer salt was removed by washing with water and running in an alkaline bath filled with 5.5% sodium hydroxide at a bath length of 8 m, followed by washing with water and winding. The processing speed at this time is 8
m/min. The permeable membrane wound up in a skein is placed in a tank, and hot water is poured into it, heated to 70°C, stirred for 1 hour under 45mmHg, and then drained. This operation was repeated three times to remove low molecular weight compounds in the membrane. The membrane treated with hot water in this way was heated to 120℃±10℃.
A tunnel type drying oven (3.45 m long) maintained at
It was run at a running speed of 4.8 m/min and dried to obtain a flat membrane type permeable membrane with an average thickness of 1.5 microns. Using the permeable membrane thus obtained (membrane area 1.0 m ² ), an indicator substance with a known molecular weight [urea (BUN): molecular weight 60, phosphate ion: molecular weight 95,
Creatinine: molecular weight 113, vitamin B ₁₂ : molecular weight
1355 and inulin (molecular weight 5200), the graph shown in Figure 3 (curve A) was obtained. The dialysate at this time was tap water, and its flow rate (Q _D ) was 500ml/
It's a minute. The flow rate (Q _B ) of the blood substitute containing indicator substances such as inulin, vitamin B ₁₂ , creatinine, urea, and PO ₄ ^-- is 200 ml/min. The respective dialysis capacities are shown in the graph (curve A) in FIG.
UFR was 10.6 ml/mmHg·hr. Comparative Example 1 A flat membrane type permeable membrane was obtained in the same manner as in Example 1 except that the ammonium salt of the acrylic acid-methyl methacrylate copolymer was not used. When the thus obtained permeable membrane was subjected to the same dialysance test as in Example 1, the graph shown in FIG. 3 (curve B) was obtained. In addition, the UFR at this time is 3.9ml/mmHg・
It was hot at hr. Example 2 Flat membrane type permeable membranes were produced in the same manner as in Example 1 except that the amount of copolymer salt added to 100 parts by weight of cellulose was varied as shown in Table 1. For this permeable membrane, data obtained using indicator substances with known molecular weights (vitamin B ₁₂ : molecular weight 1255, inulin: molecular weight 5200, cytochrome C: molecular weight 13400, bovine serum albumin: molecular weight 68000) was plotted on normal probability paper. The molecular weight showing the inhibition rate of 50% was determined, and the calculation was made from this value using the following formula.
However, in the formula, ^- d is the average molecular diameter (average pore diameter), and MW is the number average molecular weight. ^- d=1.32 (MW) The test results are as shown in Table 1.

[Table] Table 2 shows the average pore diameters obtained by plotting the results in Table 1 on normal probability paper with respect to the amount of control agent added. Table 2 Addition amount (parts by weight/100 parts by weight) Average pore diameter (Å) 0 19.2 15 20.0 30 20.4 Furthermore, the results of the dialysance test conducted in the same manner as in Example 1 are as shown in Table 3. Ta.

[Table] Example 3 Acrylic acid with a number average molecular weight of 10,000 having 15 equivalent % of carboxyl groups in the method of Example 1.
Ammonium salt of ethyl acrylate copolymer
A flat membrane type permeable membrane was obtained in the same manner as in Example 1 except that 155 g was used. When this permeable membrane was subjected to the same dialysance test as in Example 1, the permeability shown in Table 4 was obtained. Example 4 In the method of Example 1, instead of hot water treatment, 5
A flat membrane type permeable membrane was obtained in the same manner as in Example 1, except that the solution was treated with a % glycerin aqueous solution at a liquid temperature of 30° C. for 60 minutes. Example 1 about this permeable membrane
When we conducted a dialysance test similar to
The permeability shown in Table 4 was obtained. Comparative Example 2 In the method of Comparative Example 1, instead of hot water treatment,
A flat membrane type permeable membrane was obtained in the same manner as in Example 1, except that the solution was treated with a % glycerin aqueous solution at a liquid temperature of 30° C. for 60 minutes. Example 1 about this permeable membrane
When we conducted a dialysance test similar to
The permeability shown in Table 4 was obtained.

[Table] (Effects of the Invention) As described above, the method for producing a permeable membrane according to the present invention is based on an ammonium or alkali metal salt of a polymer having a number average molecular weight of 500 to 200,000 and containing 10 to 70 equivalent % of carboxyl groups. A phantom composition containing a reaction product of copper ammonia cellulose and cuprammonium cellulose is discharged in the form of a flat film from a slit-like extrusion hole, and the stock solution composition discharged in the form of a flat film is further passed between at least two rollers. This is done by immersing the polymer in dilute sulfuric acid to control the thickness, then immersing it in dilute sulfuric acid to solidify and regenerate it, and then immersing it in a strong alkaline aqueous solution to remove ammonium or alkali metal salts from the polymer. The diameter of the pores formed and the permeation ability can be controlled arbitrarily by selecting the molecular weight of the polymer salt used as a polymer salt and changing the amount used, thereby obtaining a flat membrane type permeable membrane that can selectively permeate substances with a desired molecular weight. be able to. Also,
Since the thickness is regulated by passing between at least two rollers, a flat membrane type permeable membrane of any thickness can be obtained, and this allows the permeation performance, water permeability, mechanical strength, etc. Can be assigned arbitrarily.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing each example of the film forming process of the present invention, and FIG. 3 is a graph showing the results of a dialysance test of a permeable membrane manufactured according to the present invention. 1, 11, 21...extrusion device, 2, 12, 22...
Slit-shaped extrusion hole, 3, 13, 23...membrane-like material,
5, 15, 25... coagulation tank, 6, 16, 26... coagulation liquid.

Claims (1)

[Claims] 1. A stock solution composition containing a reaction product of ammonium or alkali metal salt of a polymer having a number average molecular weight of 500 to 200,000 and containing 10 to 70 equivalent % of carboxyl groups and cuprammonium cellulose. is discharged in the form of a flat film from a slit-shaped extrusion hole, and the stock solution composition discharged in the form of a flat film is further passed between at least two rollers to regulate the thickness, and then immersed in dilute sulfuric acid for solidification and regeneration. A method for producing a flat membrane type permeable membrane, which comprises further immersing the polymer in a strong alkaline aqueous solution to remove ammonium or alkali metal salts from the polymer. 2. The method according to claim 1, wherein the polymer salt is used in an amount of 1 to 40 parts by weight based on 100 parts by weight of cellulose. 3. The method according to claim 1 or 2, wherein the reaction between the polymer salt and cuprammonium cellulose is carried out at a temperature of 8 to 30°C. 4. The method according to claim 1, wherein the number average molecular weight of the polymer is 1,000 to 100,000. 5. The method according to any one of claims 1 to 4, wherein the average degree of polymerization of cellulose is 500 to 2,500. 6. The carboxyl group-containing polymer is at least one selected from the group consisting of acrylic acid-alkyl acrylate (or methacrylate), methacrylic acid-alkyl acrylate (or methacrylate), and a partial hydrolysis product of polyalkyl acrylate (or methacrylate). Claims 1 to 5 which are copolymers of species
The method described in any one of the paragraphs.