JP6767562B1 - Composite semipermeable membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation membrane having excellent oil resistance and sufficient desalting treatment performance. SOLUTION: In a composite semipermeable membrane including at least a porous layer and a separation functional layer provided on the porous layer, the porous layer is one or more selected from a fluoropolymer and an imide group-containing polymer. The compression ratio of the portion containing the polymer and the portion composed of the porous layer and the separation functional layer after pressurization at 5.5 MPa is 60% or less. [Selection diagram] Fig. 1

Description

The present invention relates to a composite semipermeable membrane.

As the composite semipermeable membrane used in the desalting treatment, a configuration including a base material, a porous layer made of an organic polymer, and a separation function layer is widely used. In particular, as a composite semipermeable membrane used in a desalting treatment by a reverse osmosis method or the like, one containing a polysulfone porous layer and a polyamide separation functional layer is well known (for example, Patent Document 1).

On the other hand, as the material of the porous layer not provided with the separation functional layer, which is not for desalting but for demineralization pretreatment such as turbidity, polysulfone, polyfluorocarbon, polyvinylidene fluoride, polyethylene, polypropylene, polyvinyl alcohol, etc. There is a disclosure about polymers such as polyacrylonitrile (for example, Patent Document 2).

Special Table 2014-523340 Japanese Unexamined Patent Publication No. 58-93734

In recent years, from the viewpoint of securing water resources, protecting the environment, etc., it has become increasingly important to desalinate and reuse water or water-based liquids. Further, the liquid to be treated containing oil may be required to be highly treated under high pressure conditions having a dimension different from that of the conventional one.

However, in the conventional configuration provided with the polysulfone porous layer as described in Patent Document 1, the treatment performance deteriorates with the passage of time, sufficient desalting treatment cannot be performed, and the polysulfone is used as the porous support layer. It was found that the separation membrane provided as is not suitable for the treatment of oil-containing liquids. When a liquid containing oil is treated using a composite semipermeable membrane having polysulfone as a porous layer, the porous layer made of polysulfone deteriorates to form a leak spot, or between the porous layer and the separation function layer. May cause delamination. Therefore, it is difficult to maintain the treatment function in the continuous use of the composite semipermeable membrane provided with the polysulfone porous layer.

Further, since the porous layer not provided with the separation functional layer as described in Patent Document 2 is usually a membrane pursuing high water permeability at a low pressure of less than 0.3 MPa, it is generally a void. Due to its high rate, it has poor pressure resistance and is not premised on use under high pressure conditions.

Therefore, in view of the above, one aspect of the present invention provides a novel composite semipermeable membrane capable of continuously desalting the liquid to be treated containing oil even under high pressure conditions. That is the issue.

The composite semipermeable membrane according to one embodiment of the present invention is a composite semipermeable membrane having at least a porous layer and a separation function layer provided on the porous layer, in which the porous layer is a fluoropolymer or an imide group. It is a composite semipermeable membrane containing the contained polymer alone and having a compression ratio of 60% or less after pressurization of 5.5 MPa in the portion composed of the porous layer and the separating functional layer.

According to one aspect of the present invention, one aspect of the present invention may cause leak spots or delamination between the porous layer and the separation functional layer even in the liquid to be treated containing oil. It is possible to provide a composite semipermeable membrane that can be continuously and stably desquamated without any need.

A schematic cross-sectional view of a composite semipermeable membrane according to an embodiment of the present invention is shown.

As shown in FIG. 1, the composite semipermeable membrane 10 according to one embodiment of the present invention includes a porous layer 2 and a separation functional layer (active layer or skin layer) 1 provided on the porous layer 2. There is. Further, as shown in FIG. 1, the composite semipermeable membrane 10 may include a base material 3 for reinforcing the porous layer 2.

In the present specification, the "semipermeable membrane" is a membrane that allows some components of the liquid to be treated to permeate and does not permeate other components. Further, "composite" in the composite semipermeable membrane means that a plurality of layers having different functions or configurations are laminated.

The separation function layer in the composite semipermeable membrane is an ultrathin layer arranged at the top. Then, the porous layer plays a role of supporting the separation functional layer. In this embodiment, the porous layer comprises an organic polymer, more specifically a polymer comprising one or more of a fluoropolymer and an imide group-containing polymer. Further, the porous layer preferably contains 1 or more of the fluoropolymer and the imide group-containing polymer in an amount of 80% by mass or more, and more preferably 90% by mass or more. Further, the porous layer is more preferably composed of one or more of a fluoropolymer and an imide group-containing polymer.

The fluoropolymer is a polymer containing fluorine. Specific examples thereof include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF), polychlorotrifluoroethylene (ethylene trifluorochloride, PCTFE), and perfluoroalkoxyalkane (four-foot). Ethylene / perfluoroalkoxyethylene copolymer (PFA), perfluoroethylene propene copolymer (ethylene tetrafluoroethylene / propylene hexafluoride copolymer, FEP), ethylene tetrafluoroethylene copolymer (ethylene tetrafluoroethylene / ethylene copolymer, FEP) ETFE), ethylene chlorotrifluoroethylene copolymer (tetrafluoroethylene / ethylene copolymer, ECTFE) and the like can be mentioned. Among the fluoropolymers, it is preferable to use polyvinylidene fluoride (PVDF), which has relatively excellent processability and can form a porous layer having excellent pressure resistance and chemical resistance.

Further, it is desirable to use an imide group-containing polymer which is an easy-to-process material because it has excellent heat resistance in addition to chemical resistance and pressure resistance. The imide group-containing polymer may be a polymer containing one or more imide bonds in the monomer unit constituting the polymer. Examples of the imide group-containing polymer include polyetherimide (PEI), polyamideimide (PAI), and polyimide (PI). Examples of the polyetherimide (PEI) include "Ultem (registered trademark) 1000" manufactured by SABIC Innovative Plastics Co., Ltd. Examples of the polyamide-imide (PAI) include "Torlon (registered trademark) AI-10" manufactured by Solvay Co., Ltd. and "Bylomax (registered trademark) HR-22BL" manufactured by Toyobo Co., Ltd. Examples of the polyimide (PI) include "KPI-MX300F" manufactured by Kawamura Sangyo Co., Ltd. and "P84 (registered trademark)" manufactured by EVONIK.

The above-mentioned polymers can be used alone or in combination of two or more. Here, the "combination" of the polymer may be a polymer blend (polymer alloy) of two or more kinds of the above-mentioned polymer, or a copolymer obtained by copolymerizing two or more kinds of monomer units forming the above-mentioned polymer. It may be a polymer blend of such a copolymer. The copolymerization may be graft copolymerization, block copolymerization or the like.

The weight average molecular weight of the polymer is preferably 100,000 or more and 1,000,000 or less, more preferably 200,000 or more and 800,000 or less, and further preferably 250,000 or more and 700,000 or less. It is more preferably 250,000 or more and 550,000 or less. When the weight average molecular weight of the polymer is 100,000 or more, appropriate processability can be obtained. Further, when the weight average molecular weight of the polymer is 1,000,000 or less, the strength of the porous layer and thus the composite semipermeable membrane can be improved.

As described above, according to this embodiment, since the polymer constituting the porous layer contains one or more of the fluoropolymer and the imide group-containing polymer, a composite semipermeable membrane having excellent oil resistance can be obtained. Therefore, even if the liquid containing oil is treated for a long period of time, the porous layer is less likely to deteriorate and delamination is less likely to occur. Therefore, good treatment can be continuously performed without deteriorating the performance of the composite semipermeable membrane due to the influence of the oil content.

Further, in the present embodiment, the compressibility of the portion composed of the porous layer and the separation function layer after pressurization of 5.5 MPa may be 0.1% or more and 60% or less, and 1.0% or more and 50% or less. It is preferable that it is 1.0% or more and 40% or less.

The compression ratio of the portion composed of the porous layer and the separation function layer is obtained by compressing the portion under a predetermined pressure for a predetermined time and subtracting the thickness after pressurization from the initial thickness (that is, the thickness reduced by the compression by pressurization). Value) is the ratio to the initial thickness.

The predetermined time can be 2 hours or more. Therefore, for example, the compressibility of the portion composed of the porous layer and the separation function layer can be the compressibility after pressurizing at 5.5 MPa for 2 hours.

As described above, the portion composed of the porous layer and the separation function layer according to the present embodiment has a compressibility in the above range and is excellent in pressure resistance. Therefore, it is possible to sufficiently cope with the operation at a high operating pressure. For example, in the composite semipermeable membrane according to this embodiment, even when an operating pressure of, for example, 1 to 12 MPa is applied by the reverse osmosis method, at least the portion composed of the porous layer and the separating functional layer has a long-term inhibition rate. Can be maintained over.

As described above, the portion composed of the porous layer and the separation function layer according to the present embodiment has a compression rate of 60% or less after pressurization of 5.5 MPa, so that the strength of the entire film is also high. Therefore, even when used at a high operating pressure for a long period of time, the structural change of the porous layer can be minimized, and the desalting prevention performance can be maintained well.

The method for producing the porous layer in this embodiment is not particularly limited, and a non-solvent-induced phase separation method (NIPS), a heat-induced solvent phase separation (TIPS), or the like can be used, but a uniform and wide porous layer can be produced. It is preferable to use the non-solvent-induced phase separation method (NIPS) because it can be used. More specifically, after the above-mentioned polymer is dissolved in a solvent to obtain a film-forming solution, the film-forming solution is applied to a substrate such as a non-woven fabric with a knife coater or the like. Then, after microphase separation is caused by placing it under high humidity, the polymer in the applied solution is coagulated and the residual solution is removed.

In the production of the porous layer by the above-mentioned non-solvent-induced phase separation method, the polymer is dissolved in a solvent, but a uniform film-forming solution can be prepared and good microphase separation can be obtained. Is preferably water-soluble and has a high boiling point. For example, the solvent used is preferably a water-soluble solvent having a boiling point of 130 ° C. or higher and 250 ° C. or lower. Specific examples of the solvent include dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAC), 1,3-dimethyl-2-imidazolidinone (DMI), N-methylpyrrolidone (NMP), and γ-. Butyrolactone (GBL) and the like can be mentioned. In other words, it is preferable that the polymer used in this embodiment is soluble in the above solvent and dissolved in the above solvent at a temperature of about room temperature to about 80 ° C. to obtain a uniform film-forming solution. ..

In the production of the film-forming solution, in addition to the above solvent, polyoxyalkylene such as polyethylene glycol and polybutylene glycol, water-soluble polymer such as polyvinyl alcohol and polyvinyl butyral, glycerin, diethylene glycol, water, acetone, 1,3 -Dioxolane and the like can be added as a pore-forming agent. By adding a predetermined amount of the pore-forming agent, the porosity, pore diameter, etc. of the porous layer can be adjusted.

The porosity (porosity) of the porous layer before pressurization in the present embodiment is preferably 35% or more and 70% or less, and more preferably 40% or more and 50% or less. When the porosity of the porous layer is 35% or more, the water permeability and desalting performance of the composite semipermeable membrane can be ensured. Further, when the porosity of the porous layer is 70% or less, the pressure resistance and strength of the porous layer and the composite semipermeable membrane can be improved, and the permeation performance of the permeation flux and the like can be improved. Further, even if the porous layer is compressed by applying pressure for a long time or high pressure, high permeation performance can be maintained. The porosity of the porous layer can be measured based on the weight of the pores of the porous layer filled with pure water.

Further, the porosity of the porous layer after pressurization, for example, the porosity of the porous layer after pressurization at a pressure of 5.5 MPa over 2 hours is preferably 30% or more and 60% or less.

The crystallinity of the polymer used in this embodiment is preferably 10% or more and 80% or less, more preferably 20% or more and 70 or less, further preferably 25% or more and 60% or less, and 30% or more 55. % Or less is more preferable, and 30% or more and 50% or less is further preferable. When the crystallinity of the polymer is 10% or more, the pressure resistance of the porous layer and thus the composite semipermeable membrane can be improved. Further, when the crystallinity of the polymer is 80% or less, it is possible to impart appropriate flexibility to the porous layer, and it is possible to obtain a composite semipermeable membrane that is not easily damaged even when pressure is applied. The crystallinity of the polymer can be calculated by measuring the heat of fusion by the differential scanning calorimetry (DSC method).

In particular, when the polymer contains polyvinylidene fluoride, the crystallinity of the polymer is preferably 30% or more and 50% or less, and more preferably 35% or more and 45% or less. When the crystallinity is 30% or more, the pressure resistance of the porous layer and thus the composite semipermeable membrane can be improved. Further, when the crystallinity is 50% or less, it is possible to impart appropriate flexibility to the porous layer, and it is possible to obtain a composite semipermeable membrane that is not easily damaged even when pressure is applied.

The average pore size on the surface of the porous layer is preferably 5 nm or more and 50 nm or less, and more preferably 15 nm or more and 25 nm or less.

The porous layer may contain a polymer other than the fluoropolymer and the imide group-containing polymer as long as it does not interfere with the action / effect of this embodiment. Further, components other than the polymer, additives and the like may be contained. Examples of components other than the polymer include functional particles such as colloidal silica and zeolite.

The separation functional layer may be a layer containing a crosslinked polyamide. The crosslinked polyamide separation functional layer is obtained by interfacial polymerization of a polyfunctional amine and an acid halide compound.

The polyfunctional amine may be an aromatic polyfunctional amine, an aliphatic polyfunctional amine, or a combination thereof. Aromatic polyfunctional amines include m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene and the like, or N-alkylated products thereof such as N, N-dimethyl m-phenylenediamine, N, N. It may be -diethylm-phenylenediamine, N, N-dimethylp-phenylenediamine, N, N-diethylp-phenylenediamine. Further, the aliphatic polyfunctional amine may be piperazine or a derivative thereof. Specific examples of the aliphatic polyfunctional amines include piperazine, 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,3,5-trimethylpiperazine, 2,5-diethylpiperazine, 2, Examples thereof include 3,5-triethylpiperazine, 2-n-propylpiperazine, 2,5-di-n-butylpiperazine and ethylenediamine. These polyfunctional amines can be used alone or in combination of two or more.

The acid halide compound is not particularly limited as long as it gives a polyamide by the reaction with the polyfunctional amine, but an acid halide having two or more carbonyl halide groups in one molecule is preferable.

Specific examples of the acid halide compound include oxalic acid, malonic acid, maleic acid, fumaric acid, glutaric acid, 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and the like. Fragrances such as halide compounds of fatty acids, phthalic acid, isophthalic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, etc. An acid halide compound of a group acid can be used. These acid halide compounds can be used alone or in combination of two or more.

When the separation functional layer is formed, the porous layer is formed on the base material, and then the surface of the porous layer is immersed in a solution of the polyfunctional amine compound. Then, the crosslinked polyamide layer is formed by contacting with a solvent solution of the acid halide compound and advancing the interfacial polymerization.

As the base material in the composite semipermeable membrane, a fiber planar structure, specifically, a woven fabric, a knitted fabric, a non-woven fabric, or the like can be used. Of these, non-woven fabric is preferable. Nonwoven fabrics are manufactured by spunbond method, spunlace method, melt blow method, carding method, air array method, wet method, chemical bonding method, thermal bond method, needle punch method, water jet method, stitch bond method, electrospinning method, etc. It may be the one that has been done. The type of fibers constituting the non-woven fabric is not limited, but synthetic fibers are preferable. Specific examples of the fibers include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polypropylene (PP), polyethylene (PE), and polyphenylene sulfide (PPS). , Polyfluoride vinylidene (PVDF), polyglycolic acid (PGA), polylactic acid (PLA), nylon 6, polycaprolactone (PCL), polyethylene adipate (PEA), polyhydroxyalkanoate (PHA), or copolymers thereof. You can. Of these, it is preferable to use polyester such as polyethylene terephthalate because it is inexpensive, has high dimensional stability and moldability, and has high oil resistance.

The thickness of the composite semipermeable membrane according to this embodiment may be 100 μm or more and 250 μm or less. The thickness of the porous layer can be 10 μm or more and 100 μm or less. The thickness of the separation function layer can be 0.01 μm or more and 1 μm or less. The thickness of the base material can be 50 μm or more and 200 μm or less.

The composite semipermeable membrane according to this embodiment may be a reverse osmosis membrane. By using the composite semipermeable membrane according to this embodiment, for example, the NaCl inhibition rate after desalting a 32000 mg / L NaCl aqueous solution at an operating pressure of 5.5 MPa for 2 hours at room temperature (25 ° C.) is 99% or more. Can be.

As described above, the composite semipermeable membrane according to this embodiment is suitably used for desalting treatment of an aqueous liquid containing oil. Here, when oil is contained, is the oil dissolved in water or an aqueous liquid? , Or that it is mixed or emulsified with a surfactant or the like. Further, this oil component may be mineral oil, animal or vegetable oil, higher fatty acid derived from animal or vegetable oil, or the like. The mineral oil may be, for example, gasoline, heavy oil, or the like, and may contain hydrocarbon oils such as paraffin-based, olefin-based, or aromatic-based oils. In particular, according to this embodiment, desalination treatment of the system to be treated containing aromatic hydrocarbon oils such as benzene, toluene, ethylbenzene and xylene can be satisfactorily performed. Examples of the animal and vegetable oils include fish oil, whale oil, lard, linseed oil, sesame oil, palm oil and the like.

Further, by using the composite semipermeable membrane according to this embodiment, a water or water-based liquid containing 0.02 ppm or more of oil can be treated, and a water or water-based liquid containing 0.1 ppm or more of oil, 1 ppm or more of oil, or 10 ppm or more of oil can be treated. Can be processed continuously.

The composite semipermeable membrane according to this embodiment is preferably formed in a flat membrane shape. Further, the flat membrane-like composite semipermeable membrane according to the present embodiment can be suitably used in a spiral-type membrane module configured by spirally winding the composite semipermeable membrane around the outside of the water collecting pipe.

Further, the composite translucent film according to this embodiment is particularly used for desalination of a liquid to be treated containing oil, for example, a petroleum refining plant, a petrochemical plant, a thermal power plant, an automobile manufacturing factory, an oil and fat manufacturing factory, a food manufacturing factory, etc. It can be suitably used for desalting treatment of the effluent generated in the above, the effluent containing oil generated at home, the seawater containing oil, or the liquid obtained by pretreating these.

Hereinafter, embodiments of the present invention will be described based on examples, but the present invention is not limited to these examples.

In the examples, a composite semipermeable membrane was prepared or prepared and evaluated by the method shown below.
[Evaluation method]
<Inhibition rate of composite semipermeable membrane>
To evaluate the desalination inhibition rate of the composite semipermeable membrane, the composite semipermeable membrane is installed in a membrane evaluation device (flow type flat membrane test cell manufactured by Nitto Denko Co., Ltd., Membrane Master C70-F) and cross-flow method is used. It was done by driving. The effective transmission area was 32.5 cm ² . The supply flow rate was 5 L / min. The evaluation was performed by the following method.

Using a 32000 mg / L NaCl aqueous solution, a pressure of 5.5 MPa was applied and the mixture was operated for 2 hours. After 2 hours, the water permeation amount and the NaCl content after permeation were measured. Then, the inhibition rate (%) was calculated based on the NaCl content before and after permeation.

<Compression rate of the portion composed of the porous layer and the separation function layer>
A plurality of φ75 mm samples were cut out from the composite semipermeable membrane, and the average value of 5 points of thickness of one sample was defined as (A). Further, the base material was peeled off from the composite semipermeable membrane, and the average value of 5 points of the thickness of the taken out base material was taken as (B). Then, the value obtained by removing (B) from (A) was defined as the thickness (C) of the portion composed of the porous layer before pressurization and the separation function layer.

Using another sample having a diameter of 75 mm, the average value of 5 points of thickness of the composite semipermeable membrane was taken as (A') after operation under the measurement conditions of <blocking rate of composite semipermeable membrane>. Further, the base material was peeled off from the composite semipermeable membrane, and the average value of the thickness of the taken out base material at 5 points was taken as (B'). Then, the value obtained by removing (B') from (A') was defined as the thickness (C') of the portion composed of the porous layer after pressurization and the separation function layer. Then, the compression ratio (k) was obtained based on the following formula.
Compressibility (k)% = 100- (C') / (C) x 100

<Porosity of porous layer>
At the stage of forming the porous layer on the base material, that is, before forming the crosslinked polyamide layer (separation functional layer), a sample of φ75 mm was cut out from the porous layer sheet on which the porous layer was formed on the base material, and 100 It was dried at ° C for 1 hour. Then, the thickness (T) and the weight (W) of the porous layer sheet were measured.

Further, the porous layer was peeled off from the porous layer sheet, and the thickness (T1) and weight (W1) of the base material were measured. The film thickness was measured at 5 points with the digital indicator "ID-C112X" manufactured by Mitutoyo Co., Ltd., and the weight was measured three times with the balance "AUW220D" manufactured by Shimadzu Corporation.

The porosity (φ) was calculated based on the following formula.
Porosity φ (%) = (1- (W-W1) / (A × (T-T1) × ρ)) × 100
A = 3.75 cm x 3.75 cm x 3.14 (area of sample of φ75 mm)
ρ (PVDF) = 1.78 g / cm ³
ρ (PEI) = 1.27 g / cm ³
ρ (PAI) = 1.42 g / cm ³

<Crystallinity of porous layer>
At the stage of forming the porous layer on the base material, that is, before forming the crosslinked polyamide layer (separation functional layer), the base material is removed from the dry porous layer sheet provided with the porous layer on the base material. Then, about 5 mg of the porous layer was sealed in a DSC measurement pan. The measurement was carried out using a differential scanning calorimeter (DSC-6200) manufactured by Seiko Electronics Co., Ltd. in a nitrogen gas atmosphere, and the temperature was raised from 50 ° C. to 210 ° C. at a heating rate of 10 ° C./min. A DSC curve was obtained. The baseline for calculating the heat absorption was drawn from 120 ° C. to the melting end temperature (about 170 to 190 ° C.), and the crystallinity was calculated with the heat of melting the perfect crystal of PVDF as 104.7 (J / g).

<Evaluation of oil resistance of composite semipermeable membrane>
The oil resistance of the composite semipermeable membrane was evaluated for Example 2 and Comparative Example 3 as typical examples. It was immersed in a solution of 85% xylene and 15% ethylbenzene as a hydrocarbon-based oil at room temperature for 40 minutes. Then, the inhibition rate of the composite semipermeable membrane was evaluated by the above-mentioned inhibition rate evaluation method. The immersion conditions were the contact conditions when the liquid to be treated containing 12.7 ppm of xylene and 2.3 ppm of ethylbenzene was desalted for 5 consecutive years.

(Example 1)
Polyvinylidene fluoride copolymer having a weight average molecular weight of 470,000 (Arkema, Kynar Flex® LBG) 19 parts by weight, polyvinylidene fluoride copolymer having a weight average molecular weight of 680,000 (Arkema, Kynar (registered trademark)) ) 761A) 1 part by weight, 79.48 parts by weight of dimethylacetamide, 0.02 part by weight of polyethylene glycol (polyethylene glycol 35000 manufactured by Merck) having a weight average molecular weight of 35,000, and 0.5 part by weight of glycerin are heated at 70 ° C. , A uniform film-forming solution was obtained. The film-forming solution was cooled to 40 ° C., and then impregnated and applied to a polyester non-woven fabric having a thickness of 0.1 mm and a density of 0.7 g / cm ³ using a film-forming device equipped with a knife coater. The coater gap of the knife coater was adjusted to 130 μm. Then, microphase separation was caused in an atmosphere having a relative humidity of 95% and a temperature of 30 ° C., and then the mixture was immersed in a coagulation water tank at 40 ° C. to solidify. Further, the polyvinylidene fluoride porous layer was formed on the non-woven fabric by washing and removing the residual solvent in a washing tank at 70 ° C.

Next, the porous layer formed on the non-woven fabric was immersed in a 1.5% by mass aqueous solution of m-phenylenediamine (aromatic polyfunctional amine compound) for 1 minute so as to be in contact with the porous layer side. Then, the excess m-phenylenediamine aqueous solution was removed. Then, the porous layer was immersed in a naphthenic solution containing 0.1% by mass of trimesic acid trichloride (aromatic acid halide compound) and 0.13% by mass of isophthalic acid chloride for 30 seconds. As a result, a crosslinked polyamide layer (separation function layer) was formed on the porous layer. This was dried in a dryer at 140 ° C. to obtain a composite semipermeable membrane in which the non-woven fabric, the porous layer, and the crosslinked polyamide separation functional layer were arranged in this order. Then, by the above-mentioned evaluation method, the crystallinity of the porous layer, the porosity of the porous layer before pressurization, the blocking rate, and the compressibility (k) of the portion composed of the porous layer and the separation functional layer are determined. I asked. The results are shown in Table 1.

(Example 2)
Polyvinylidene fluoride copolymer having a weight average molecular weight of 470,000 (Arkema, Kynar Flex (registered trademark) LBG) 20 parts by weight, dimethylacetamide 79.48 parts by weight, polyethylene glycol having a weight average molecular weight of 20000 (Merck, polyethylene) A polyvinylidene fluoride porous layer was obtained in the same manner as in Example 1 except that a film-forming solution was obtained using 0.02 parts by weight of glycol 20000) and 0.5 parts by weight of glycerin.

Then, a composite semipermeable membrane was obtained by forming a crosslinked polyamide layer in the same manner as in Example 1. Also in Example 2, according to the above-mentioned evaluation method, the crystallinity of the porous layer, the porosity of the porous layer before pressurization, the blocking rate, and the compressibility of the portion composed of the porous layer and the separating functional layer ( k) was sought. The results are shown in Table 1. In addition, the oil resistance of Example 2 was also evaluated. The results are shown in Table 2.

(Example 3)
20 parts by weight of polyvinylidene fluoride copolymer (manufactured by Archema, Kynar Flex 2850) having a weight average molecular weight of 470,000, 79.48 parts by weight of dimethylacetamide, polyethylene glycol having a weight average molecular weight of 20 (registered trademark) 000 (manufactured by Merck Co., Ltd., A polyvinylidene fluoride porous layer was obtained on the non-woven fabric in the same manner as in Example 1 except that a film-forming solution was obtained using 0.02 parts by weight of polyethylene glycol 20000) and 0.5 parts by weight of glycerin.

Next, a composite semipermeable membrane was obtained by forming a crosslinked polyamide layer in the same manner as in Example 1. Also in Example 3, according to the above-mentioned evaluation method, the crystallinity of the porous layer, the porosity of the porous layer before pressurization, the blocking rate, and the compressibility of the portion composed of the porous layer and the separation functional layer. (K) was calculated. The results are shown in Table 1.

(Example 4)
Film formation using 18 parts by weight of polyvinylidene fluoride copolymer (manufactured by Archema, Kynar Flex (registered trademark) LBG), 15 parts by weight of polyvinylpyrrolidone, 66 parts by weight of dimethylacetamide, and 1 part by weight of glycerin having a weight average molecular weight of 470,000. The film-forming solution was impregnated and applied to the polyester non-woven fabric in the same manner as in Example 1 except that the solution was obtained and the coater gap of the knife coater was set to 160 μm. Then, microphase separation was caused in an atmosphere having a relative humidity of 90% and a temperature of 40 ° C., and then the mixture was immersed in a coagulation water tank at 40 ° C. to solidify. Further, the residual solvent was washed and removed in a washing tank at 70 ° C. to obtain a polyvinylidene fluoride porous layer on the non-woven fabric.

Then, in the same manner as in Example 1, a crosslinked polyamide layer was formed by the method according to the above-mentioned Separation Function Layer Formation Example 1 to obtain a composite semipermeable membrane. Also in Example 4, according to the above-mentioned evaluation method, the crystallinity of the porous layer, the porosity of the porous layer before pressurization, the blocking rate, and the compressibility of the portion composed of the porous layer and the separation functional layer. (K) was calculated. The results are shown in Table 1.

(Example 5)
A film-forming solution was obtained by heating and dissolving at 80 ° C. using 22 parts by weight of a polyvinylidene fluoride copolymer (manufactured by Arkema, Kynar (registered trademark) HSV900) having a weight average molecular weight of 1 million and 78 parts by weight of N-methylpyrrolidone. The polyvinylidene fluoride porous layer was the same as in Example 1 except that it was allowed to run idle in an atmosphere having a relative humidity of 15% and a temperature of 40 ° C. and then immersed in a coagulation water tank at 25 ° C. to solidify it. Got

Next, a composite semipermeable membrane was obtained by forming a crosslinked polyamide layer in the same manner as in Example 1. Also in Example 5, according to the above-mentioned evaluation method, the crystallinity of the porous layer, the porosity of the porous layer before pressurization, the permeation flux and the blocking rate, and the portion composed of the porous layer and the separation functional layer. The compression ratio (k) of was obtained. The results are shown in Table 1.

(Example 6)
Heat-dissolved at 85 ° C. using 24 parts by weight of polyvinylidene fluoride copolymer (manufactured by Arkema, Kynar® HSV900) having a weight average molecular weight of 1 million, 63 parts by weight of N-methylpyrrolidone, and 13 parts by weight of dientylene glycol. Obtained a film-forming solution, allowed it to run idle in an atmosphere with a relative humidity of 15% and a temperature of 42 ° C, and then immerse it in a coagulation water tank at 20 ° C to coagulate it, and set the coater gap of the knife coater to 120 μm. A polyvinylidene fluoride porous layer was obtained on the non-woven fabric in the same manner as in Example 1.

Next, a composite semipermeable membrane was obtained by forming a crosslinked polyamide layer in the same manner as in Example 1. Also in Example 6, according to the above-mentioned evaluation method, the crystallinity of the porous layer, the porosity of the porous layer before pressurization, the blocking rate, and the compressibility of the portion composed of the porous layer and the separation functional layer. (K) was calculated. The results are shown in Table 1.

(Example 7)
18 parts by weight of polyetherimide (SABIC Innovative Plastics (registered trademark), Ultram1000) having an average molecular weight of 32000, 49.2 parts by weight of N-methylpyrrolidone, and 32.8 parts by weight of 1,3-dioxolane are heated at 65 ° C. It was dissolved to obtain a uniform film-forming solution, and the coater gap of the knife coater was adjusted to 120 μm. A polyetherimide porous layer was obtained on the non-woven fabric by immersing and coagulating in a coagulating water tank at 40 ° C. through a free running distance of 300 mm and washing and removing the residual solvent in a water washing tank at 45 ° C.

Next, a composite semipermeable membrane was obtained by forming a crosslinked polyamide layer in the same manner as in Example 1. Also in Example 7, the porosity, permeation flux and blocking rate of the porous layer, and the compressibility (k) of the portion composed of the porous layer and the separation functional layer were determined by the above-mentioned evaluation method. The results are shown in Table 1.

(Comparative Example 1)
A membrane provided with a polyvinylidene fluoride porous layer used for RS50 (manufactured by Nitto Denko KK), which is a spiral type UF membrane element, was prepared. A crosslinked polyamide layer was formed on the membrane in the same manner as in Example 1 to obtain a composite semipermeable membrane. In Comparative Example 1, according to the above-mentioned evaluation method, the crystallinity of the porous layer, the porosity of the porous layer before pressurization, the blocking rate, and the compressibility of the portion composed of the porous layer and the separating functional layer ( k) was sought. The results are shown in Table 1.

(Comparative Example 2)
18 parts by weight of polyvinylidene fluoride (Solvay, Solef (registered trademark) 6012) having a weight average molecular weight of 380,000, 15 parts by weight of polyvinylpyrrolidone, 66.5 parts by weight of dimethylacetamide, and 0.5 parts by weight of glycerin at 70 ° C. It was melted by heating to obtain a uniform film-forming solution. After cooling to 40 ° C., a polyester non-woven fabric having a thickness of 0.1 mm and a density of 0.7 g / cm ³ was impregnated and coated using a film-forming device equipped with a knife coater. The coater gap of the knife coater was adjusted to 180 μm. Then, after microphase separation occurs in an atmosphere having a relative humidity of 95% and a temperature of 30 ° C., the residue is coagulated by immersing it in a coagulation water tank at 45 ° C., and the residual solvent is washed and removed in a water washing tank at 50 ° C. A polyvinylidene fluoride porous layer was obtained on the non-woven fabric.

Next, a crosslinked polyamide layer was formed in the same manner as in Example 1 to obtain a composite semipermeable membrane. In Comparative Example 2, according to the above-mentioned evaluation method, the crystallinity of the porous layer, the porosity of the porous layer before pressurization, the blocking rate, and the compressibility of the portion composed of the porous layer and the separating functional layer ( k) was sought. The results are shown in Table 1.

(Comparative Example 3)
A reverse osmosis membrane of a spiral type RO membrane element (LG SW 400 R manufactured by LG Chemical Corporation) was prepared. The reverse osmosis membrane is a composite semipermeable membrane having a porous layer as a polysulfone membrane. For Comparative Example 3, oil resistance was evaluated. The results are shown in Table 2.

From Table 1, Examples 1 to 7 in which the compressibility k of the portion composed of the porous layer and the separating functional layer was 60% or less showed a high NaCl inhibition rate of 99% or more. Further, from Table 1, it can be seen that the NaCl inhibition rates in Comparative Examples 1 and 2 in which the compressibility k of the portion composed of the porous layer and the separation functional layer exceeds 60% are inferior to those in Examples 1 to 7. Do you get it.

Further, from Table 2, it was found that the NaCl inhibition rate of Example 2 showed a high value even after immersion in the xylene-containing liquid. On the other hand, in Comparative Example 3, as a result of immersing in the xylene solution at room temperature for 40 minutes, the porous layer was dissolved and delamination occurred, so that the inhibition rate could not be evaluated.

1 Separation function layer 2 Porous support layer 3 Base material 10 Composite semipermeable membrane

Claims (11)

In a composite semipermeable membrane provided with at least a porous layer and a separation function layer provided on the porous layer.
The porous layer contains a fluoropolymer or an imide group-containing polymer alone ,
A composite semipermeable membrane in which the compressibility of the portion composed of the porous layer and the separation functional layer after pressurization at 5.5 MPa is 60% or less. The composite semipermeable membrane according to claim 1, wherein the separation functional layer is a polyamide-based separation functional layer. The composite semipermeable membrane according to claim 1 or 2, wherein the polymer is soluble in a water-soluble solvent having a boiling point of 130 ° C. or higher and 250 ° C. or lower. The water-soluble solvent is dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAC), 1,3-dimethyl-2-imidazolidinone (DMI), N-methylpyrrolidone (NMP), γ-butyrolactone. The composite translucent film according to claim 3, which comprises one or more selected from (GBL). The polymer according to any one of claims 1 to 4, wherein the polymer is one or more selected from polyvinylidene fluoride (PVDF), polyetherimide (PEI), polyamideimide (PAI), and polyimide (PI). Composite semipermeable membrane. The composite semipermeable membrane according to any one of claims 1 to 5, wherein the porosity of the porous layer before pressurization is 35% or more and 70% or less. The composite semipermeable membrane according to any one of claims 1 to 6, wherein the porosity of the porous layer after pressurization is 30% or more and 60% or less. The composite semipermeable membrane according to any one of claims 1 to 7, wherein the polymer has a crystallinity of 10% or more and 80% or less. The composite semipermeable membrane according to any one of claims 1 to 8, wherein the polymer has a weight average molecular weight of 100,000 or more and 1,000,000 or less. Claims 1 to 9 wherein the polymer contains vinylidene fluoride, the weight average molecular weight of the polymer is 100,000 or more and 1,000,000 or less, and the crystallinity of the polymer is 30% or more and 50% or less. The composite semipermeable membrane according to any one of the above. The composite semipermeable membrane according to any one of claims 1 to 10, which is a flat membrane.

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