JP2006257397A - Aromatic polyamide porous film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aromatic polyamide porous film which can be satisfactorily used as a film for the blood treatment and in which not only the adsorption of a protein is uniformly suppressed through the whole film, but also the elution of a hydrophilic polymer can be suppressed. <P>SOLUTION: This aromatic polyamide porous film comprises an aromatic polyamide polymer and one or more polymers having a hydrophilic segment, wherein the amount of the polymer having a hydrophilic segment is 2 to 50% by weight relative to the amount of the aromatic polyamide polymer and the polymer forming the porous film takes a three-dimensional network structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aromatic polyamide porous film in which protein adsorption is suppressed, and blood such as antibody, enzyme separation, concentration, blood purification membrane, plasma separation membrane, dialysis membrane, filtration membrane, filtration dialysis membrane, etc. It can be suitably used as a treatment film. Moreover, it can be suitably used as a water vapor selective permeable membrane.

  Conventionally, flat membranes and hollow fiber membranes of polysulfone-based polymers have been used for blood purification such as separation and concentration of antibodies and enzymes, hemodialysis and blood filters. In such a case, polysulfone itself is hydrophobic and has a defect that proteins such as platelets and blood cells in blood are easily adsorbed. For this reason, in order to impart blood compatibility, a polymer having a hydrophilic segment such as polyvinylpyrrolidone (hereinafter referred to as a hydrophilic polymer) is used by blending or block copolymerizing. Such examples are described in Patent Documents 1 to 4, for example.

  However, since the polysulfone polymer and the hydrophilic polymer that are hydrophobic are originally not compatible, the dispersion state of the hydrophilic polymer in the polysulfone polymer becomes non-uniform, resulting in a locally highly hydrophobic portion. May occur, and the portion may easily cause protein adsorption.

  Further, due to the poor compatibility, the hydrophilic polymer may be eluted in the filtrate when used for a long period of time or at a high temperature. In order to prevent this, Patent Documents 5 and 6 disclose a method of crosslinking a hydrophilic polymer with gamma rays. However, this method increases the number of manufacturing steps and leads to an increase in cost.

  Furthermore, when sterilization and sterilization are performed simultaneously with separation and concentration, the heat resistance of the polysulfone polymer may be insufficient.

In view of the above problems, a porous film made of an aromatic polyamide polymer having a hydrophilic amide group and having good compatibility with a hydrophilic polymer and high heat resistance is considered useful. As an example, Patent Document 7 discloses a porous film in which an aromatic polyamide and another polymer are alloyed. However, Patent Document 7 aims to provide a microporous film having a small moisture absorption coefficient, a low coefficient of humidity expansion, and excellent dimensional stability against changes in humidity. Used as alloy polymer. Therefore, like the polysulfone polymer, there is a problem that protein is likely to be adsorbed.
Japanese Patent Laid-Open No. 61-9380 Japanese Patent Laid-Open No. 61-238834 JP-A-62-201603 JP-A-2-2862 JP 2000-237557 A JP 2003-260340 A Japanese Patent No. 2956129

  The present invention is a porous film composed of an aromatic polyamide polymer and a hydrophilic polymer, which has good compatibility with a hydrophilic polymer and has high heat resistance, and is capable of separating antibodies, enzymes, etc. with suppressed protein adsorption, It is an object of the present invention to provide an aromatic polyamide porous film that can be suitably used as a blood treatment membrane such as a concentration, blood purification membrane, plasma separation membrane, dialysis membrane, filtration membrane, and filtration dialysis membrane. Another object of the present invention is to provide an aromatic polyamide porous film that can be suitably used as a water vapor selective permeable membrane because of its high hydrophilicity.

  The above object includes an aromatic polyamide polymer and a polymer having a hydrophilic segment, the content of the polymer having a hydrophilic segment is 2 to 50% by weight based on the aromatic polyamide polymer, and a three-dimensional network. This is achieved by an aromatic polyamide porous film having a structure.

  ADVANTAGE OF THE INVENTION According to this invention, the aromatic polyamide porous film which can be used suitably as a film | membrane for blood processing which can suppress protein adsorption | suction uniformly to the whole film and can also suppress the elution of a hydrophilic polymer is obtained. Furthermore, since it has high heat resistance, sterilization and the like can be performed at the same time.

Here, as an aromatic polyamide, what has a repeating unit represented, for example by following formula (2) and / or Formula (3) is preferable.
Formula (2):

Formula (3):

Here, as the group of Ar ₁ , Ar ₂ , Ar ₃ , for example,

Etc. can be mentioned, X, group Y _{is, -O -, - CH 2 -} , - CO -, - CO 2 -, - S -, - SO 2 -, - C (CH 3) 2 - selected from such However, it is not limited to these.

  Furthermore, some of the hydrogen atoms on these aromatic rings are halogen groups such as fluorine, bromine and chlorine (especially chlorine), nitro groups, alkyl groups such as methyl, ethyl and propyl (especially methyl groups), methoxy and ethoxy, Those substituted with a substituent such as an alkoxy group such as propoxy are preferred because they lower the moisture absorption rate and reduce the dimensional change due to changes in humidity. In addition, hydrogen in the amide bond constituting the polymer may be substituted with another substituent.

In the aromatic polyamide used in the present invention, the above aromatic ring having para-orientation preferably accounts for 80 mol% or more, more preferably 90 mol% or more of the total aromatic ring. Para-orientation here means a state in which the divalent bonds constituting the main chain on the aromatic ring are coaxial or parallel to each other. When this para orientation is less than 80 mol%, the rigidity and heat resistance of the film may be insufficient. Further, when the aromatic polyamide contains 60 mol% or more of the repeating unit represented by the formula (3), it is preferable because the stretchability and the film physical properties are particularly excellent.
Formula (4):

  The aromatic polyamide porous film of the present invention includes an aromatic polyamide polymer and a polymer having a hydrophilic segment (hereinafter referred to as a hydrophilic polymer), and the content of the hydrophilic polymer is relative to the aromatic polyamide polymer. 2 to 50% by weight. If the content of the hydrophilic polymer is less than 2% by weight, protein adsorption to the film surface may not be suppressed. If the content exceeds 50% by weight, the rigidity (Young's modulus) of the film decreases and self-supporting May be insufficient, or heat resistance may be reduced. Since the suppression of protein adsorption and the rigidity and heat resistance of the film can be achieved in a balanced manner, the content of the hydrophilic polymer is more preferably 5 to 40% by weight, and further preferably 10 to 30% by weight. The hydrophilic polymer may be dispersed throughout the film or may be present only on the surface of the film. The presence of the hydrophilic polymer only on the surface is preferable because the content of the aromatic polyamide in the film can be increased while maintaining the effect of suppressing protein adsorption, and the physical properties such as heat resistance are further improved.

  When the hydrophilic polymer is dispersed throughout the film, the hydrophilic polymer content is determined by dissolving only the hydrophilic polymer using methylene chloride, then evaporating the solvent and weighing the hydrophilic polymer. Can be sought. Further, when the hydrophilic polymer is present only on the surface, the content of the hydrophilic polymer can be determined from the weight change before and after the graft reaction described later.

  Moreover, when the aromatic polyamide porous film of the present invention has a three-dimensional network structure, the porosity can be increased while maintaining the rigidity and heat resistance of the film, and a space for capturing unnecessary components can be widened. Since it can be taken, it is preferable. The three-dimensional network structure referred to in the present invention refers to a structure in which a network structure in which fibers made of a polymer constituting a porous film are joined together with an intersection that branches into three or more branches in three dimensions (see FIG. 1). On the other hand, a structure having a straight hole (see FIG. 2) as a hole structure not belonging to the three-dimensional network structure (see FIG. 2), a structure having a through hole in which the straight hole is curved or branched (see FIG. 3), and a spherical or discoidal hole A structure connected by a narrow path (see FIG. 4) can be mentioned, but these are not preferable because the space for capturing unnecessary components is narrow and the fractionation ability is lowered.

It is preferable that the hydrophilic polymer of the present invention has a repeating unit represented by the formula (5) (representing a hydrophilic segment as referred to in the present invention) since the protein adsorption suppressing effect is high.
Formula (5):

  In particular, at least one hydrophilic polymer selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol, polyethyleneimine, polyacrylamide, polyvinyl alcohol, polyallylamine, polyacrylic acid and polyvinyl sulfate is preferable.

  In addition, the aromatic polyamide porous film of the present invention is preferably a flat film. Since the hollow fiber membrane is bulky, the device tends to be large. In particular, when membranes having different pore diameters are stacked and filtered in multiple stages, a flat membrane is preferable because it becomes bulky.

  The aromatic polyamide porous film of the present invention preferably has an average pore diameter of 1 to 500 nm. The average pore diameter is appropriately adjusted depending on the substance to be separated, but if it is less than 1 nm, it is necessary to apply a high pressure to pass the filtrate, and the film may be broken. If it exceeds 500 nm, the strength of the film may be significantly reduced. Since the permeability of the filtrate and the strength of the film can be balanced, the average pore diameter is more preferably 3 to 300 nm, and further preferably 5 to 100 nm.

  The aromatic polyamide porous film of the present invention preferably has an amount of thermal deformation at 150 ° C. in at least one direction of 2% or less. If it exceeds 2%, the pore size may change due to shrinkage or expansion of the film when used at high temperatures, and the filtration accuracy may not be accurate. The lower limit is 0%. Since heat resistance becomes higher, the thermal shrinkage at 150 ° C. is more preferably 1.5% or less, and further preferably 1.0% or less.

  The aromatic polyamide porous film of the present invention preferably has a moisture absorption rate of 5 to 15%. If the moisture absorption rate is less than 5%, the protein adsorption may be insufficiently suppressed or the filtrate may be difficult to pass. If the moisture absorption rate exceeds 15%, it swells, the pore size changes, and the filtration accuracy is accurate. It may disappear.

  The aromatic polyamide porous film of the present invention preferably has a Young's modulus in at least one direction of 3 GPa or more and an elongation of 5% or more. Since the Young's modulus and elongation are high, it is possible to resist high tension and tension fluctuation during processing, and the productivity is improved. In order to satisfy these characteristics, as described above, the aromatic polyamide used in the present invention has a para-orientation, preferably 80 mol% or more of the total aromatic ring, more preferably It is effective to occupy 90 mol% or more (productivity is improved). More preferably, the Young's modulus in at least one direction is 4.5 GPa or more and the elongation is 10% or more. From the general characteristics of aromatic polyamides, the upper limit of Young's modulus is 15 GPa, and the upper limit of elongation is about 60%.

  The aromatic polyamide porous film of the present invention preferably has a thickness of 2 to 100 μm. When the thickness exceeds 100 μm, it takes time for filtration and loss may increase, and when the thickness is less than 2 μm, the strength of the film may decrease.

  Next, although the manufacturing method of the aromatic polyamide porous film of this invention is demonstrated below, it is not limited to this.

  First, an aromatic polyamide, for example, when it is obtained from acid chloride and diamine, a method of synthesis by solution polymerization in an aprotic organic polar solvent such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide, or an aqueous medium is used. A method of synthesis by interfacial polymerization or the like to be used can be employed. When acid chloride and diamine are used as monomers, hydrogen chloride is by-produced in the polymer solution. To neutralize this, inorganic neutralizers such as calcium hydroxide, calcium carbonate, lithium carbonate, and ethylene An organic neutralizing agent such as oxide, propylene oxide, ammonia, triethylamine, triethanolamine, diethanolamine may be used. Moreover, when obtaining aromatic polyamide from reaction of isocyanate and carboxylic acid, it can synthesize | combine in presence of a catalyst in an aprotic organic polar solvent.

In order to obtain the porous film of the present invention, the intrinsic viscosity η _{inh of the} polymer (value measured at 30 ° C. as a solution of 0.5 g of polymer in 98 wt% sulfuric acid in 100 ml) is 0.5 (dl / g) The above is preferable because the elongation becomes high when the porous film is formed and the handling property is improved.

  The hydrophilic polymer is added to the film-forming stock solution when the hydrophilic polymer is dispersed in the film and added to the neutralized aromatic polyamide polymer solution in the form of pellets or dissolved in a solvent. Further, after the aromatic polyamide polymer is isolated, it may be dissolved in an aprotic organic polar solvent together with the aromatic polyamide polymer.

  The polymer concentration in the film-forming stock solution is preferably about 2 to 30% by weight. From the viewpoint of efficiently obtaining a thin and stable porous film, the content is more preferably 8 to 25% by weight, and further preferably 12 to 20% by weight.

  The film-forming stock solution prepared as described above is formed into a porous film by a so-called solution film-forming method. The solution casting methods include dry and wet methods, wet methods, and deposition methods, and any method can be used to form a film, but since the porous film has a uniform internal structure, the precipitation method is preferred. More preferred.

When producing a porous film by the precipitation method, the solution is cast on a support such as a glass plate, film, drum, endless belt, etc., and then cooled, or water is absorbed. By taking the above, the solubility of the polymer is lowered and precipitated. At this time, a cooling method is more preferable because the deposition rate can be easily controlled.
In the cooling method, the support and the ambient temperature are set to -30 to 0 ° C. When the temperature is lower than −30 ° C., precipitation may occur abruptly, and pores may not be formed. When the temperature exceeds 0 ° C., the polymer solubility may not be sufficiently lowered and precipitation may not occur. The difference between the support temperature and the ambient temperature is preferably 15 ° C. or less because the difference in physical properties between the front and back of the membrane is reduced.

  The cooling time is preferably 1 to 20 minutes. If it is less than 1 minute, the formation of pores is not sufficient, and the ion permeability may be deteriorated. If it exceeds 20 minutes, the pores become too large, and the film becomes brittle and cannot be practically used.

  In addition, as a method of absorbing water, any method of adhering mist-like water, a method of introducing into water, or a method of introducing into humidified air may be used, but the water absorption rate and amount are finely controlled. Since it is possible, the method of introducing into humidity-conditioned air is preferably used. When the polymer solution having a film shape is introduced into the conditioned air, the polymer is preferably precipitated in the air conditioned at 50 to 100% relative humidity. The temperature at this time is preferably 0 to 80 ° C.

  The humidity conditioning time is preferably 1 to 20 minutes. If it is less than 1 minute, the formation of pores is not sufficient, and the ion permeability may be deteriorated. If it exceeds 20 minutes, the pores become too large, and the film becomes brittle and cannot be practically used.

  The solution that has finished polymer precipitation is then introduced into a wet bath and desolventization is performed. At this time, it may be peeled off from the support and introduced into the wet bath, or may be peeled off after being introduced into the wet bath together with the support. The bath composition is not particularly limited as long as the solubility in the aromatic polyamide is low, but it is preferable to use water or a mixed system of an organic solvent / water from the viewpoint of economy and ease of handling. Further, the wet bath may contain an inorganic salt.

  The porous film that has been desolvated is subjected to heat treatment. The temperature at this time is preferably higher because the dimensional stability at high temperature is improved, but it is necessary that the temperature be lower than the thermal decomposition temperature of the hydrophilic polymer used, and is 200 to 350 ° C. It is preferable. At this time, stretching may be performed. The draw ratio is preferably 1.0 to 4.0 in terms of surface magnification because the Young's modulus and elongation are within the scope of the present invention, and the elongation is further improved. More preferably, it is 1.0 to 1.1 times so that it does not shrink.

  When the hydrophilic polymer is present only on the film surface, the hydrophilic polymer is grafted onto the film surface by the following method after film formation.

  First, the graft reaction is performed by irradiating a film such as γ rays or electron beams after the film is immersed in or brought into contact with a hydrophilic polymer solution. The absorbed dose is preferably 5 to 100 kGy. If it is less than 5 kGy, the generation of radicals is insufficient and the graft reaction may not proceed, and if it exceeds 100 kGy, the decomposition of the hydrophilic polymer may proceed.

  At this time, if the temperature of the solution is high, spots depending on the location are likely to occur in the graft reaction, so that the temperature is preferably 0 to 18 ° C, more preferably 4 to 10 ° C.

  The solvent used is a solvent that dissolves the hydrophilic polymer and does not dissolve the aromatic polyamide polymer, and water, methanol, ethanol, acetone, etc. are used, but water is particularly preferable from the viewpoint of cost and safety. Used.

  After the graft reaction, the solvent is dried at a temperature of 100 to 200 ° C. to obtain a porous film.

  Since the aromatic polyamide porous film of the present invention can suppress the adsorption of proteins, separation and concentration of antibodies and enzymes, blood purification membranes, plasma separation membranes, plasma separation membranes, dialysis membranes, filtration membranes, filtration dialysis membranes, and other blood treatment membranes Can be suitably used. Moreover, since it has high hydrophilicity, it can be suitably used as a water vapor selective permeable membrane.

[Methods for measuring physical properties and methods for evaluating effects]
The physical property measurement method and the effect evaluation method in the examples were performed according to the following methods.

(1) Average pore diameter (nm)
In accordance with ASTM F316-86, the average pore size was measured at 23 ° C. and 65% relative humidity using Perm-Porometer (manufactured by PMI) by the bubble point method.

(2) Three-dimensional network structure Using a super high resolution field emission scanning electron microscope (SEM) S-900H manufactured by Hitachi, Ltd., the center part of the porous film surface is 5 cm away from the center part in the vertical and horizontal directions under the following conditions. Observed and confirmed 5 points in the area.

Acceleration voltage: 5 kV
Observation magnification: 30,000 times (3) Thermal deformation (%)
The porous film was cut to a width of 1 cm and a length of 22 cm, and a 1 cm portion was marked from both ends in the length direction. Heat treatment was performed in a hot air oven at 200 ° C. for 30 minutes with substantially no tension applied, and the following formula was used for calculation. Measurement was performed 5 times, and an average value was obtained.

Thermal deformation (%) = (| Test length before heat treatment−Test length after heat treatment and cooling | / Test length before heat treatment) × 100
(4) Moisture absorption rate (%)
The porous film was cut into 100 mm × 100 mm, heated and dehumidified in an oven at 150 ° C. for 1 hour, then cooled in a dry nitrogen atmosphere, and weight when completely dehumidified: W. Was measured. The film was allowed to stand for 48 hours in 75% RH, and was taken out. The weight after moisture absorption: W was measured and calculated according to the following formula.

Moisture absorption rate = ((W−W.) / W.) × 100
(5) Thickness Using an electronic micrometer (detector model number: K107C, stylus radius 1.5 mm, stylus load 1.5 g) manufactured by Kansai Anritsu Electronics Co., Ltd. Measurements were taken at various locations to determine the average value.

(6) Content of hydrophilic polymer When the hydrophilic polymer was dispersed throughout the film, the film was cut, added to 2% by weight in methylene chloride, and stirred at 60 ° C for 2 hours. After filtering the solution, the solvent of the filtrate was evaporated and the weight of the remaining hydrophilic polymer was measured.

  When the hydrophilic polymer was present only on the surface, the content of the hydrophilic polymer was determined from the change in weight before and after the graft reaction.

(7) Outflow amount of hydrophilic polymer 10 g of the porous film was immersed in 1 L of hot water at 60 ° C. and heated for 24 hours. The porous film taken out from the hot water is dried in an oven at 150 ° C., and the weight loss is measured. The reduction amount with respect to the hydrophilic polymer in the porous film before the hydrothermal treatment was obtained as a percentage, and evaluation was performed according to the following criteria. Δ and ○ are practical ranges.

○: Less than 0.01% Δ: 0.01% or more and less than 0.02% X: 0.02% or more (8) Platelet adhesion number A porous film is placed on the bottom of a 18 mmφ polystyrene cylindrical tube, Fill with saline. 3. Platelet rich plasma (PRP) prepared by adjusting blood mixed with 2% trisodium citrate dihydrate aqueous solution and fresh rabbit blood at 1: 9 (volume ratio) to a platelet count of 20 × 10 ⁻⁶ / ml After discarding the prepared physiological saline in the cylindrical tube, 1.0 ml of PRP is added and shaken at 37 ° C. for 1 hour. Then, it was washed with physiological saline three times, blood components were fixed with 3% glutaraldehyde aqueous solution, washed with distilled water and dried. The inner surface of this porous film was observed with a scanning electron microscope, and the number of adhering platelets in an area of 1.12 × 10 ³ μm ² was counted. Based on the number of adhering platelets, the following criteria were used for evaluation. Δ and ○ are practical ranges.

○: Less than 10 Δ: 10 or more and less than 20 X: 20 or more (9) Fractionation ability A dextran aqueous solution having a molecular weight distribution of 1,000 to 1,000,000 is passed through a porous film and filtered. The permeate was collected. The dextran concentration before and after permeation was measured, and the transmittance was calculated from the following equation.

Transmittance (%) = (permeate concentration / non-treatment solution concentration) × 100
Concentration measurement was performed using GPC under the following conditions, and was determined from the area detected by a refractometer.

GPC: GMPWXL2 connection manufactured by Tosoh Corporation Flow rate: 0.5 ml / min
Solvent: methanol: water = 1: 1 (volume ratio)
Column temperature: 40 ° C
Detector: Refractometer Next, after the porous film was heat-treated at 150 ° C. for 10 minutes under no tension, the transmittance was measured in the same manner, and the evaluation was performed according to the following criteria from the difference in transmittance before and after the heat treatment. . Δ and ○ are practical ranges.

○: Difference is less than 5% Δ: Difference is 5% or more and less than 10% X: Difference is 10% or more (Example 1)
2-chloroparaphenylenediamine corresponding to 80 mol% and 4,4′-diaminodiphenyl ether corresponding to 20 mol% are dissolved in dehydrated N-methyl-2-pyrrolidone, which corresponds to 98.5 mol%. 2-chloro terephthalic acid chloride was added, polymerized by stirring for 2 hours, and then neutralized with lithium carbonate to obtain an aromatic polyamide solution having a polymer concentration of 11% by weight. This solution was poured into a mixer together with water, and the polymer was precipitated while stirring.

  This aromatic polyamide polymer was weighed to 10 wt%, N-methyl-2-pyrrolidone 88.8 wt%, and polyvinylpyrrolidone (average molecular weight 2,000) 1.2 wt%, and dissolved at 60 ° C. To obtain a homogeneous and completely compatible polymer solution.

  This polymer solution was supplied to a die and cast into a film of about 150 μm on a stainless steel belt. The base and the pipe to the base were set to 5 ° C, and the ambient temperature around the belt and the belt was set to -5 ° C. It was cooled on the belt for 5 minutes to obtain a self-retaining gel film. The gel film was peeled from the belt, and the solvent and impurities were extracted in a 0 ° C. water bath for 2 minutes and then in a 50 ° C. water bath for 1 minute. Thereafter, heat treatment was performed at 200 ° C. for 2 minutes while stretching in the tenter 1.1 times in the width direction.

  The main production conditions and evaluation results are shown in Table 1. All evaluations were beyond the practical range.

(Example 2)
A porous film was obtained in the same manner as in Example 1 except that the amount of N-methyl-2-pyrrolidone added was 85.2% by weight and the amount of polyvinylpyrrolidone added was 4.8% by weight. All evaluations were beyond the practical range.

(Example 3)
A porous film was obtained in the same manner as in Example 1 except that the addition amount of N-methyl-2-pyrrolidone was 89.7% by weight and the addition amount of polyvinylpyrrolidone was 0.3% by weight. All evaluations were beyond the practical range.

Example 4
The same method as in Example 1 except that the addition amount of N-methyl-2-pyrrolidone is 87.5 wt% and polyvinyl alcohol (average molecular weight 4,500) is added 2.5 wt% instead of polyvinyl pyrrolidone. A porous film was obtained. All evaluations were beyond the practical range.

(Example 5)
The same method as in Example 1 except that the addition amount of N-methyl-2-pyrrolidone is 88.8% by weight, and 1.2% by weight of polyethylene glycol (average molecular weight 1,500) is added instead of polyvinylpyrrolidone. A porous film was obtained. All evaluations were beyond the practical range.

(Example 6)
Using the precipitated polymer obtained in the same manner as in Example 1, 10% by weight of the aromatic polyamide polymer and 90% by weight of N-methyl-2-pyrrolidone were weighed and dissolved at 60 ° C. A completely compatible polymer solution was obtained.

  This polymer solution was supplied to a die and cast into a film of about 150 μm on a stainless steel belt. The base and the pipe to the base were set to 5 ° C, and the ambient temperature around the belt and the belt was set to -5 ° C. It was cooled on the belt for 5 minutes to obtain a self-retaining gel film. The gel film was peeled from the belt, and the solvent and impurities were extracted in a 0 ° C. water bath for 2 minutes and then in a 50 ° C. water bath for 1 minute. Thereafter, heat treatment was performed at 200 ° C. for 2 minutes while stretching in the tenter 1.1 times in the width direction.

  Next, the film was introduced into a 5 ° C. aqueous solution containing 0.2% by weight of polyvinyl pyrrolidone (average molecular weight 2,000), and irradiated with γ rays. The γ-ray irradiation dose was 25 kGy. Thereafter, it was washed with water in a water bath and dried at 120 ° C. for 3 minutes.

  All evaluations were beyond the practical range.

(Example 7)
A porous film was obtained in the same manner as in Example 1 except that the temperature of the aqueous solution of polyvinylpyrrolidone was 20 ° C. All evaluations were beyond the practical range.

(Comparative Example 1)
A porous film was obtained in the same manner as in Example 1 except that the amount of N-methyl-2-pyrrolidone added was 90% by weight and the amount of hydrophilic polymer added was 0% by weight. Platelet adhesion number deteriorated. Moreover, since the dextran aqueous solution did not permeate, the fractionation ability could not be measured.

(Comparative Example 2)
1. 10% by weight of polysulfone is added in place of the aromatic polyamide polymer, the amount of N-methyl-2-pyrrolidone added is 87.5% by weight, and polyvinyl alcohol (average molecular weight 4,500) is used in place of polyvinylpyrrolidone. A porous film was obtained in the same manner as in Example 1 except that 5% by weight was added. The outflow amount and fractionation ability of the hydrophilic polymer deteriorated.

(Comparative Example 3)
A porous film was obtained in the same manner as in Example 1 except that the addition amount of N-methyl-2-pyrrolidone was 89.2% by weight and the addition amount of polyvinylpyrrolidone was 0.8% by weight. Platelet adhesion number deteriorated.

(Comparative Example 4)
A porous film was obtained in the same manner as in Example 1 except that the amount of N-methyl-2-pyrrolidone added was 84.8% by weight and the amount of polyvinylpyrrolidone added was 5.2% by weight. The fractionation ability deteriorated.

(Comparative Example 5)
Using the precipitated polymer obtained in the same manner as in Example 1, a film-forming solution was prepared with 10% by weight of aromatic polyamide polymer and 90% by weight of N-methyl-2-pyrrolidone. This solution was cast on an endless belt so as to have a thickness of about 100 μm, heated for 2 minutes with hot air at 180 ° C. to evaporate the solvent, and the film having self-holding property was continuously peeled from the belt. Next, the film was introduced into a 50 ° C. water tank, and the residual solvent and the inorganic salt produced by neutralization were extracted with water. Then, after preliminary drying at 80 ° C. for 30 seconds with a tenter, the film was stretched 1.1 times in the transverse direction while being heat-treated at 280 ° C. for 1.5 minutes to obtain an aromatic polyamide film having a thickness of 9 μm. It was.

  This film is passed under pressure between an iron roll and a silicone rubber roll, on which a large number of synthetic diamond particles having a particle size of 50 to 60 μm and sharp corners are electrodeposited, and an aromatic polyamide porous film is obtained. Obtained.

  Thereafter, polyvinyl pyrrolidone was grafted on the film surface in the same manner as in Example 6.

  From the SEM observation, it was found that straight holes were formed. The fractionation ability was bad.

(Comparative Example 6)
Using the precipitated polymer obtained in the same manner as in Example 1, a film-forming solution was prepared with 10% by weight of aromatic polyamide polymer and 90% by weight of N-methyl-2-pyrrolidone. In this solution, a surfactant (“Homogenol” L-18 manufactured by Kao) and zinc oxide fine particles having an average particle diameter of 1 μm (manufactured by High-Purity Chemical Co., Ltd., specific gravity 5.47) are respectively 2% by weight and 80% by weight with respect to the polymer. The mixture was uniformly dispersed and mixed while heating to 60 ° C. under a nitrogen stream. This solution was cast on an endless belt so as to have a thickness of about 100 μm, heated with hot air at 180 ° C. for 2 minutes to evaporate the solvent, and the self-holding film was continuously peeled from the belt. Next, the film was introduced into a 50 ° C. water tank, and the residual solvent and the inorganic salt produced by neutralization were extracted with water. Then, after preliminary drying at 80 ° C. for 30 seconds with a tenter, the film was stretched 1.1 times in the transverse direction while being heat-treated at 280 ° C. for 1.5 minutes to obtain an aromatic polyamide film having a thickness of 16 μm. It was.

  This film was immersed in a 5% nitric acid aqueous solution for 30 minutes to dissolve and remove the zinc oxide fine particles dispersed in the white film. And after washing | cleaning in a 40 degreeC water tank, the drying process was performed at 100 degreeC for 1 minute, and the aromatic polyamide porous film was obtained.

  Thereafter, polyvinyl pyrrolidone was grafted on the film surface in the same manner as in Example 6.

  From observation by SEM, it was found that a hole structure as shown in FIG. 4 was formed. The fractionation ability was bad.

  The present invention relates to an aromatic polyamide porous film in which protein adsorption is suppressed, and blood such as antibody, enzyme separation, concentration, blood purification membrane, plasma separation membrane, dialysis membrane, filtration membrane, filtration dialysis membrane, etc. It can be suitably used as a treatment film. Moreover, since it has high hydrophilicity, it can be suitably used as a water vapor selective permeable membrane.

It is the schematic which shows the three-dimensional network structure of the aromatic polyamide porous film which concerns on one embodiment of this invention. It is the schematic which shows the structure different from a three-dimensional network structure. It is the schematic which shows the structure different from a three-dimensional network structure. It is the schematic which shows the structure different from a three-dimensional network structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid content consisting of aromatic polyamide polymer 2 Void 3 Solid content consisting of aromatic polyamide polymer 4 Void 5 Solid content consisting of aromatic polyamide polymer 6 Void 7 Solid content consisting of aromatic polyamide polymer 8 Void

Claims (9)

It contains an aromatic polyamide polymer and a polymer having a hydrophilic segment, the content of the polymer having a hydrophilic segment is 2 to 50% by weight based on the aromatic polyamide polymer, and has a three-dimensional network structure Aromatic polyamide porous film. The aromatic polyamide porous film according to claim 1, wherein the polymer having a hydrophilic segment has a repeating unit represented by the formula (1).
Formula (1):

The polymer having a hydrophilic segment is at least one polymer selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol, polyethyleneimine, polyacrylamide, polyvinyl alcohol, polyallylamine, polyacrylic acid, and polyvinyl sulfate. 2. The aromatic polyamide porous film according to 2. The aromatic polyamide porous film according to any one of claims 1 to 3, wherein the average pore diameter is 1 to 500 nm. The aromatic polyamide porous film according to any one of claims 1 to 4, wherein an amount of thermal deformation at 150 ° C in at least one direction is 2% or less. The aromatic polyamide porous film according to any one of claims 1 to 5, which has a moisture absorption rate of 5 to 15%. The aromatic polyamide porous film according to any one of claims 1 to 6, which has a thickness of 2 to 100 µm. The aromatic polyamide porous film according to any one of claims 1 to 7, which is used as a blood treatment membrane. The aromatic polyamide porous film according to any one of claims 1 to 7, which is used as a water vapor selective permeable membrane.

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