JP4784522B2 - Polyvinylidene fluoride based porous separation membrane - Google Patents

Description

  The present invention relates to a separation membrane particularly suitable for purifying sewage (living wastewater generated from cooking, washing, bathing, toilets, and other living environments) and wastewater generated from production factories, restaurants, fishery processing factories, food processing plants, and the like.

  In recent years, separation membranes in the form of flat membranes or hollow fiber membranes have been used for purification of sewage and wastewater.

  There are various types and forms of such separation membranes, but a polyvinylidene fluoride resin solution containing a surfactant can be applied to the surface of a porous substrate such as a woven fabric or a non-woven fabric. A flat membrane called a so-called microfiltration membrane is known, in which a polyvinylidene fluoride resin is solidified by impregnating the substrate and a porous polyvinylidene fluoride resin layer is formed on the surface of the porous substrate. (See Patent Document 1).

In this separation membrane, the porous polyvinylidene fluoride resin layer acts as a separation functional layer, but in such a flat membrane, the effective membrane area per unit volume compared to other forms of separation membrane, for example, hollow fiber membranes Therefore, it is required to increase the water permeation amount while maintaining the pore diameter corresponding to the filtration target. However, if you try to increase the amount of water permeation, or too large pore size, the blocking rate or cracked on the surface decreases. On the other hand, if the pore diameter is reduced in order to increase the blocking rate, the water permeability will be lowered. In other words, the improvement in the rejection rate and the improvement in water permeability are in a contradictory relationship, and it is difficult to make a good balance between the two.

  Furthermore, since polyvinylidene fluoride resin is generally a resin that is extremely difficult to adhere, hot melt adhesives are generally used when manufacturing the separation membrane element by bonding the end of the separation membrane to the support base frame. Although it is used, the adhesive strength is still not sufficient, and further enhancement is required. In particular, in the membrane manufacturing process of forming a porous layer on a substrate, when the density of the porous substrate is low and the viscosity of the film-forming stock solution is low, the film-forming stock solution reaches the back of the substrate, In the case of a separation membrane in which the porous substrate of the adhesive surface is covered with a polyvinylidene fluoride resin, or the porous substrate is immersed in a polyvinylidene fluoride resin film forming stock solution, or coated on both sides. In the case of a separation membrane in which the surface of the separation membrane is covered with a polyvinylidene fluoride resin layer by forming a porous layer, the hot melt adhesive is sufficiently entangled with the polyvinylidene fluoride resin on the surface of the separation membrane There is a problem that it is difficult to obtain desired adhesive strength. Even if it can be bonded, the porous layer is significantly lower in strength than the supporting substrate, so that during the membrane filtration operation, inorganic substances such as sand, sludge, and other solids in the treated water collide violently. Or the supply of oxygen to the activated sludge and the aeration operation performed to prevent clogging causes the air bubbles to collide violently, causing the adhesion between the support substrate and the separation membrane to be peeled off, resulting in leakage from the joint. There is.

  Patent Document 2 discloses that a polysulfone is blended with a resin composition obtained by blending a small amount of polyvinylidene fluoride with polysulfone in order to provide a porous membrane having a film-forming property similar to that of polysulfone and a hydrophobic property similar to that of polyvinylidene fluoride. A method for producing a porous porous membrane has been proposed. However, this porous membrane has a problem that it is inferior in chemical resistance compared to polyvinylidene fluoride because the main component of the resin constituting the membrane is polysulfone, and it is difficult to use it practically for a long time. There is.

Further, Patent Document 3, as a physical method of joining the separation membrane and the supporting substrate frame performs irradiation of local heating or an ultrasonic or high frequency of light to the junction of each resin material superimposed A method of melting and welding the interfaces of the resin members has been proposed. The local heating and ultrasonic or high-frequency irradiation employed in this physical bonding method has the disadvantage that damage to the membrane sheet and filter is likely to be expanded by the heat and vibration generated by the heating and irradiation. Further, since spots due to welding occur, there is also a problem that there is a high possibility of leakage from the joint.

JP 2003-135939 A JP-A-7-118438 Japanese Patent Laid-Open No. 7-24271

  The present invention solves the above-mentioned problems of the prior art, has a separation membrane function and durability at the same level as a separation membrane made of a polyvinylidene fluoride resin, and can improve adhesiveness. The object is to provide a system separation membrane.

In order to achieve the above object, the present invention comprises the configurations described in the following (1) to (7) .
(1) In a separation membrane composed of a base material layer and a porous separation functional layer, the porous separation functional layer comprises 51% by weight to 95% by weight of polyvinylidene fluoride resin and 5% by weight to 49% by weight of polysulfone resin. A polyvinylidene fluoride-based porous separation membrane characterized by comprising a blend resin.
(2) The separation membrane is a flat membrane in which a part of the resin constituting the porous separation functional layer enters the base material layer and a layer in which the porous separation functional layer and the base material layer are combined exists. The polyvinylidene fluoride porous separation membrane according to (1) .

(3) The polyvinylidene fluoride porous separation membrane according to the above (1) or (2), wherein the exclusion rate of fine particles having an average particle size of 0.9 μm is at least 90%.
(4) The polyvinylidene fluoride-based porous separation membrane according to any one of (1) to (3), wherein the density of the porous substrate is 0.7 g / cm ³ or less.
(5) The polyvinylidene fluoride porous separation membrane according to any one of (1) to (4), wherein the porous substrate is a nonwoven fabric or a woven or knitted fabric.
(6) A membrane separation element comprising the flat membrane-like separation membrane according to any one of (1) to (5), a flow path material, and a permeate collecting member.
(7) A membrane separation module in which a plurality of the membrane separation elements according to (6) are accommodated in a housing.

  The polyvinylidene fluoride-based porous separation membrane of the present invention is a flat membrane in which a resin constituting the porous separation functional layer enters a part and all of the porous separation membrane to form a composite layer with the substrate. Even when the porous separation membrane is bonded to the support plate of the element with a hot melt adhesive, the adhesive strength can be sufficiently increased, for example, 5 N / 25 mm or more and 150 N / 25 mm or less. It can be adhesive strength. In addition, inorganic substances such as sand, sludge, and other solids in the water to be treated collide violently with the membrane surface, and bubbles are generated by aeration operations to prevent oxygen from being supplied to the activated sludge and clogging. Even if it collides violently, since the adhesive strength which can fully endure is obtained, peeling in an adhesion part can be suppressed significantly. Therefore, the durability of the separation membrane is improved, and it is easy to achieve long-term operation.

  The separation membrane according to the present invention is a polyvinylidene fluoride porous membrane comprising a base material layer and a porous separation functional layer. Here, the base material layer and the porous separation functional layer are a part of the porous separation membrane, and a part of the resin constituting the porous separation functional layer enters the base material layer, so that the porous separation membrane A functional layer and a base material layer are formed into a composite layer, and the adhesive strength when the porous film is bonded to the element support plate with a hot melt adhesive is at least 5 N / 25 mm to 150 N / 25 mm Preferably there is. With such an adhesive strength, peeling of the separation membrane can be sufficiently suppressed.

  The porous separation functional layer is a layer that bears the separation function in the separation membrane, and is composed of a blend resin of 51% to 95% by weight of polyvinylidene fluoride resin and 5% to 49% by weight of other organic resin. The As described above, since the polyvinylidene fluoride blend resin is a main component, membrane formation with a solution is easy, and a separation membrane excellent in physical durability and chemical resistance can be obtained.

  Here, the polyvinylidene fluoride resin is a vinylidene fluoride homopolymer or a vinylidene fluoride copolymer. A plurality of types of vinylidene fluoride copolymers may be contained. Examples of the vinylidene fluoride copolymer include a copolymer obtained by copolymerizing vinylidene fluoride with at least one selected from the group consisting of ethylene tetrafluoride, hexafluoropropylene, and ethylene trifluoride chloride. .

  Further, the weight average molecular weight of the polyvinylidene fluoride resin is preferably in the range of 50,000 to 1,000,000, more preferably 100,000 to 750,000 in consideration of the processability to the separation membrane. When the weight average molecular weight is larger than this range, the viscosity of the polyvinylidene fluoride resin composition solution becomes too high. When the weight average molecular weight is smaller than this range, the viscosity of the polyvinylidene fluoride resin composition becomes too low. It becomes difficult to form. If the amount of the polyvinylidene fluoride resin in the polyvinylidene fluoride blend resin constituting the separation functional layer is too small, there is a drawback that the chemical resistance is lowered, and the polyvinylidene fluoride resin is close to 100% by weight. It is difficult to increase the adhesive strength. Therefore, the ratio of the polyvinylidene fluoride resin as the main component is 51% to 95% by weight of the blend resin.

  Further, in the blend resin constituting the separation functional layer, if the amount of the secondary component organic resin is too large, durability may be lowered. Therefore, the amount of the secondary component organic resin is 5 wt% to 49 wt% of the blend resin. % Is necessary.

  Such an accessory organic resin is an organic resin other than the polyvinylidene fluoride-based resin. For example, a polyacrylonitrile-based resin (for example, an acrylonitrile-butadiene-styrene copolymer (ABS resin), an acrylonitrile-styrene copolymer ( Examples thereof include copolymers of polyacrylonitrile such as AS resin) and other resins, polysulfone resins, polyethersulfone resins, polyolefin resins, and the like. Among them, because it is familiar with the solvent and is advantageous for the effect of improving durability and adhesion by blending, at least selected from polysulfone resin, polyacrylonitrile resin, polyether sulfone resin One type of resin is preferred. Among these, a polysulfone resin is particularly preferable from the viewpoint of film forming property due to the viscosity of the stock solution.

  In the separation membrane in which the porous separation functional layer is formed on the base material layer, the base material layer has a function of supporting the porous separation functional layer and giving strength to the separation membrane. The material constituting the base material layer is not particularly limited, such as an organic base material and an inorganic base material, but an organic base material is preferable from the viewpoint of easy weight reduction. Examples of the organic substrate include woven and knitted fabrics and nonwoven fabrics made of organic fibers such as cellulose fibers, cellulose triacetate fibers, polyester fibers, polypropylene fibers, and polyethylene fibers. Among these, a nonwoven fabric whose density is relatively easy to control is particularly preferable.

  If the thickness of the base material layer is too thin, it will be difficult to maintain the strength as a separation membrane, and if it is extremely thick, the water permeability will be reduced, so a range of 0.01 mm to 1 mm is preferable. Most preferably, the range is 0.05 mm to 0.5 mm.

The density of the substrate is 0.7 g / cm ³ or less, preferably 0.6 g / cm ³ or less. This density range is suitable for accepting a film-forming stock solution and forming a composite layer of a substrate and a porous layer in the production process described later. However, when the density is extremely low, the strength as a separation membrane is lowered, and thus it is preferably 0.3 g / cm ³ or more. The density here is an apparent density, which can be obtained from the area, thickness and weight of the substrate by the following formula.

  On the other hand, if the thickness of the porous separation functional layer is too thin, defects such as cracks may occur, and the filtration performance may deteriorate. If the thickness is too thick, the water permeability may decrease, so it is usually 0.001 to 0.5 mm. The thickness is preferably selected in the range of 0.05 to 0.2 mm.

  Furthermore, in the separation membrane in which the porous separation functional layer is formed on the base material layer, a part of the polyvinylidene fluoride resin composition constituting the porous separation functional layer enters the base material layer to form a composite layer. It is preferable that By inserting the polyvinylidene fluoride blend resin into the base material layer, the porous separation functional layer is firmly fixed to the base material layer by a so-called anchor effect, and the porous separation functional layer can be prevented from peeling off from the base material layer. become. The porous separation functional layer may be present on one side with respect to the base material layer, or may be present on both sides. The porous separation functional layer may have a symmetric structure or an asymmetric structure with respect to the base material layer. Further, when the porous separation functional layer is present on both sides with respect to the base material layer, the porous separation functional layers on both sides may be continuous through the base material layer, or discontinuous It does not matter.

  Next, the manufacturing method of the separation membrane of this invention is demonstrated. The separation membrane of the present invention is produced, for example, by forming a porous separation functional layer by coagulating a membrane-forming stock solution containing a polyvinylidene fluoride-based blend resin and a pore-opening agent in a coagulating solution containing a non-solvent. Can do.

  At this time, the membrane separation solution may be applied to the surface of the substrate to form a porous separation functional layer, or the substrate may be immersed in the membrane formation solution to form a porous separation functional layer. When applying the film-forming stock solution to the substrate, it may be applied on one side of the substrate or on both sides. Only the porous separation functional layer may be formed separately from the substrate.

  And in coagulating the membrane forming undiluted solution, only the porous separation functional layer formed on the substrate may be brought into contact with the coagulating solution, or the porous separation functional layer may be immersed in the coagulating solution together with the substrate. In order to bring only the porous separation functional layer into contact with the coagulation liquid, for example, a method in which the porous separation functional layer formed on the base material is brought into contact with the coagulation bath surface, glass plate, metal A method in which a base material is brought into contact with a flat plate such as a plate and attached so that the coagulation bath does not enter the base material side, and the base material having a porous separation functional layer is immersed in the coagulation bath together with the plate. is there. In the latter method, the base material may be attached to the plate and then the film of the film-forming stock solution may be formed, or the stock solution film may be formed on the base material and then attached to the plate.

  In addition to the above-described polyvinylidene fluoride-based blend resin, a pore-opening agent, a solvent for dissolving them, or the like may be added to the film-forming stock solution as necessary.

In the case of adding a pore-opening agent having an action of promoting porous formation to the film-forming stock solution, the pore-opening agent may be any one that can be extracted by the coagulation liquid, and preferably has high solubility in the coagulation liquid. For example, polyethylene glycol, or polyoxyalkylenes, such as polypropylene glycol, polyvinyl alcohol, polyvinyl butyral, also possible to use water-soluble high molecules and glycerol such as Pol acrylic acid.

  In the present invention, as the pore opening agent, a surfactant containing a polyoxyalkylene structure, a fatty acid ester structure or a hydroxyl group can be used. Use of a surfactant makes it easy to obtain the target pore structure.

As polyoxyalkylene structure,
In particular, from the viewpoint of hydrophilicity, polyoxyethylene represented by the following formula is preferable.

  Examples of the fatty acid ester structure include fatty acids having a long-chain aliphatic group. The long-chain aliphatic group may be linear or branched, and examples of the fatty acid include stearic acid, oleic acid, lauric acid, and palmitic acid. Moreover, fatty acid ester derived from fats and oils, such as beef tallow, palm oil, coconut oil, etc. are also mentioned.

  Examples of the surfactant having a hydroxyl group include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, glycerin, sorbitol, glucose, and sucrose.

  The surfactant used as the pore-opening agent in the present invention preferably contains two or more of a polyoxyalkylene structure, a fatty acid ester structure and a hydroxyl group.

Of these, surfactants containing all of the polyoxyalkylene structure, fatty acid ester structure and hydroxyl group are particularly preferably used. For example, polyoxyethylene sorbitan fatty acid ester includes polyoxyethylene sorbitan monostearate, polyoxyethylene palm Oil fatty acid sorbitan, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene fatty acid ester, polyethylene glycol monostearate, polyethylene glycol monooleate, polyethylene glycol monolaurate Can be mentioned. These surfactants, water permeability also be remaining in the porous layer dried, blocking resistance is preferred because both the feature that does not decrease.

  When a solvent for dissolving a polyvinylidene fluoride resin, other organic resin, a pore-opening agent, or the like is used in the film forming stock solution, N-methylpyrrolidone (NMP), N, N- Dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone, methyl ethyl ketone and the like can be used. Of these, NMP, DMAc, DMF, and DMSO, which are highly soluble in polyvinylidene fluoride resins, can be preferably used.

  In addition, a non-solvent can also be added to the film-forming stock solution. The non-solvent does not dissolve the polyvinylidene fluoride resin or other organic resins, and acts to control the size of the pores by controlling the solidification rate of the polyvinylidene fluoride resin and other organic resins. To do. As the non-solvent, water and alcohols such as methanol and ethanol can be used. Of these, water and methanol are preferred from the viewpoint of ease of wastewater treatment and price. These may be mixed.

In the composition of the film forming stock solution, the blended resin composed of polyvinylidene fluoride and other organic resins is 5 to 30% by weight, the pore-opening agent is 0.1 to 15% by weight, and the solvent is 45 to 94% by weight. It is preferable that the non-solvent is in the range of 0.1% by weight to 10% by weight. Among these, the polyvinylidene fluoride-based blend resin has a lower porous layer strength when it is extremely small, and the water permeability may be lowered when it is too large, so the range of 8% by weight to 20% by weight is more preferable. If the amount of the pore-opening agent is too small, the water permeability may decrease, and if the amount is too large, the strength of the porous layer may decrease. On the other hand, if the amount is extremely large, it may remain excessively in the polyvinylidene fluoride-based blend resin and elute during use, and the quality of the permeated water may deteriorate or the water permeability may fluctuate . Therefore, a more preferable range is 0.5 wt% to 10 wt%. Furthermore, if the amount of the solvent is too small, the stock solution is likely to be gelled, and if the amount is too large, the strength of the porous layer is lowered. If the amount of non-solvent is too large, gelation of the stock solution tends to occur, and if it is extremely small, control of the size of pores and macrovoids becomes difficult. Therefore, it is more preferably 0.5 wt% to 5 wt%.

  On the other hand, as the coagulation bath, a non-solvent or a mixed solution containing a non-solvent and a solvent can be used. When a non-solvent is used for the film-forming stock solution, the non-solvent in the coagulation bath is preferably at least 80% by weight of the coagulation bath. If the amount is too small, the coagulation rate of the polyvinylidene fluoride-based blend resin becomes slow and the pore diameter becomes large. More preferably, it is in the range of 85% by weight to 100% by weight. On the other hand, when a non-solvent is not used for the film-forming stock solution, it is preferable to reduce the content of the non-solvent in the coagulation bath, compared to the case where a non-solvent is also used for the film-forming stock solution. preferable. When the amount of non-solvent is large, the solidification rate of the polyvinylidene fluoride-based blend resin is increased, and the surface of the porous layer becomes dense and water permeability may be lowered. More preferably, the range is from 60% to 99% by weight. By adjusting the content of the non-solvent in the coagulation bath, the pore size on the surface of the porous layer and the size of the macrovoids can be controlled. If the temperature of the coagulation bath is too high, the coagulation rate will be too fast. Conversely, if the temperature is too low, the coagulation rate will be too slow, so it is usually selected in the range of 15 ° C to 80 ° C. preferable. More preferably, it is the range of 20 to 60 degreeC.

Moreover, the separation membrane of the present invention, nanofiltration membrane, ultrafiltration membrane, may be any of the microfiltration membrane, select the appropriate one or more film according to the size of the separation subject substance, a combination However, an ultrafiltration membrane and a microfiltration membrane are particularly preferable for treating sewage wastewater. Further, it is more preferable that the rejection of fine particles having an average particle size of 0.088 μm is 90% or more. If not satisfied this rejection, when wastewater treatment, is or occurred clogging due bacteria and sludge or the like bacteria or sludge leaks, or occurred sudden upward rise of the filtration differential pressure, the life is extremely It becomes shorter.

  Here, the blocking rate is the temperature of 25 ° C. of raw water in which polystyrene latex fine particles (nominal particle size 0.088 μm, standard deviation 0.0062 μm) manufactured by Ceradyne are dispersed in reverse osmosis membrane permeated water to a concentration of 10 ppm. From the absorbance of ultraviolet light having a wavelength of 202 nm obtained by allowing the separation membrane to permeate under a pressure of 10 kPa and obtaining the raw water and the permeated water, respectively, the following equation is used.

The adhesive method of definitive to the present invention, the element support plate of the separation membrane and the ABS resin by using a hot-melt adhesive, be a method of bonding the flat membrane which is characterized in that an adhesive by hot press method The anchor effect that can be exhibited by the hot-melt adhesive is maximized, and the adhesive penetrates deep into the separation membrane and is fixed on the support substrate of the separation membrane.

  The porous separation functional layer may be present on one side with respect to the base material layer, or may be present on both sides. The porous separation functional layer may have a symmetric structure or an asymmetric structure with respect to the base material layer. Further, when the porous separation functional layer is present on both sides with respect to the base material layer, the porous separation functional layers on both sides may be continuous through the base material layer, or discontinuous It does not matter.

In the present invention, when the separation membrane and the ABS resin element support plate are bonded, an ABS resin element support plate is placed on a weighing pan of an electronic balance (TANITA Corporation / TLC-500). It is preferable to place a hot melt adhesive thereon, place a separation membrane thereon, apply heat at 165 [deg.] C. with a hot press, iron, or the like from above the separation membrane, and press and adhere for 20 seconds at a pressure of 0.13 MPa. Here, the shape of hot-melt adhesive may be a good pellet shape in GATT shape when using a hot melt adhesive gun, even when not using the hot melt adhesive gun is a may be in sheet form or fill beam shape, Good.

  Note that if the amount of hot melt adhesive is small, the adhesive cannot be uniformly adhered and leaks, so that the adhesive adheres in a linear form with a width of 10 mm and a thickness of 0.15 mm on the adhesive surface between the separation membrane and the element support plate. It is preferable to do.

  As such a hot melt adhesive, polyacrylic ester resin, polyimide resin, polyurethane resin, polyolefin resin, polyester resin and the like are preferable. Among these, an ABS resin that is generally used as a constituent material of the element support plate and a polyester resin that is familiar to the polyester fiber that is generally used as the base material layer of the separation membrane are particularly preferable.

Then, the adhesive strength between the separation membrane and the element support plate is measured using “Tensilon” ( TENSILON (registered trademark) / UTM-4L TOYO MEASURING INSTRUMENTS CO., LTD) according to JIS K6854 180 degree peel test. A separation membrane sample having a width 25mm was laminated separation membrane with a hot-melt adhesive element support plate, to measure the peel strength at a rate of pulling speed 200 mm / min.

  When the separation membrane of the present invention is used for membrane filtration, when the separation membrane is flat, it has a separation membrane (or a separation membrane and a flow path material) and a permeate collecting member. It is preferable to form an element or a module in which a plurality of elements are housed in a housing. In the case where the separation membrane is in the form of a hollow fiber, the plurality of hollow fiber membranes are aligned in one direction and accommodated in a housing having a stock solution inlet and a permeate outlet, and at least one end thereof is an end surface. The module is preferably fixed to the case so as to be in an open state. The element or module is preferably used for the treatment of sewage wastewater as a liquid processing apparatus by providing a means for supplying the stock solution to the separation membrane and a liquid collecting means for collecting the permeated liquid that has passed through the separation membrane. it can.

  Although the form of an element is not specifically limited, An example of the form of the element which can be used suitably for a wastewater treatment use is demonstrated using FIG.

  The element shown in FIGS. 1 and 2 includes a flow path material 2 and a flat membrane-like separation membrane 3 arranged in this order on both sides of a rigid support plate 1. Since it is difficult to increase the membrane area of the element of this form, the separation membranes 3 are arranged on both surfaces of the support plate 1 in order to increase the water permeability. The support plate 1 has convex portions 4 and concave portions 5 on both sides. The separation membrane 3 filters impurities in the liquid. The flow path member 2 is for efficiently flowing the permeated water filtered by the separation membrane 3 to the support plate 1. The permeated water that has flowed to the support plate 1 is taken out through the recesses of the support plate 1.

The support plate 1 is not particularly limited as long as it has a structure having a plurality of projections and depressions on both surfaces of the plate-like body. The recesses are preferably provided so as to form a plurality of grooves arranged in parallel at regular intervals so as to flow evenly relative to the surface. At this time, the width of each recess 5 is within a range of 1 to 20 mm, and further 1.5 to 5 in order to prevent the passage material 2 and the separation membrane 3 from falling down under severe aeration conditions while keeping the permeated water amount high. It is preferable to be within a range of 5 mm. The depth of the recess 5 is preferably selected within a range of about 1 to 10 mm in order to secure the permeate flow path while suppressing the thickness as the element. Furthermore, the porosity of the support plate due to the recesses is in the range of 15 to 85% in order to sufficiently secure the permeate flow path and suppress the flow resistance when the permeate flows, while maintaining the strength of the support plate. Is preferred. This indicates the volume percentage of voids formed by the recesses when the support plate straight rectangular parallelepiped of 100%, can be efficiently intake flow resistance increases permeate the porosity is below 15% However, if it exceeds 85%, the strength of the support plate is significantly reduced.

  The material of the support plate 1 is preferably a material having a rigidity with a tensile strength of about 15 MPa or more in accordance with ASTM test method D638. Metals such as stainless steel, acrylonitrile-butadiene-styrene copolymer (ABS resin), resins such as polyethylene, polypropylene and vinyl chloride, composite materials such as fiber reinforced resin (FRP), and other materials are preferably used. it can.

Moreover, in the element of this invention, it is also preferable to install the frame 6 in the peripheral part of the support plate 1 as shown in FIG. In this case, the separation membrane 3 may be fitted between the support plate 1 and the frame body 6 or may be adhered to the outer surface of the frame body 6. Here, "adhesion" refers to the fixed child being in contact, be bonded with such separately resin, also by welding the separation membrane itself, further adhered in other various ways Also good. Costs can be reduced by fitting the frame body 6 manufactured by injection molding, extrusion molding, or the like into the periphery of the support plate 1 manufactured by an inexpensive manufacturing method such as resin extrusion molding. In order to make it easy to fit the support plate 1, the frame body 6 is preferably formed so that the cross-section is a U-shape.

  In the element configured as described above, the permeated water filtered by the separation membrane 3 flows to the flow path member 2 and the concave portion 5 of the support plate 1 and finally from the permeated water outlet 7 to the outside of the element. And discharged.

  Then, the module which accommodated the said element in multiple sheets housing, and its usage method are demonstrated based on FIGS. FIG. 3 shows a separation membrane module 10 in which a plurality of elements 9 are housed in a housing so that a space is formed between the membrane surfaces of the separation membrane 3 in parallel with each other. The separation membrane module 10 is used so as to be immersed in water to be treated such as organic waste water stored in the water tank 11 to be treated. Inside the separation membrane module 10 are provided a plurality of elements 9 loaded in the vertical direction, and an air diffuser 12 for supplying the gas from the blower 13 to the membrane surface of the separation membrane below it, and the separation membrane A pump 14 for sucking permeate is provided downstream of the module 10.

In the sewage wastewater treatment apparatus configured as described above, water to be treated such as wastewater passes through the separation membrane 3 by the suction force of the pump 14. At this time, sludge that is part of water to be treated, the suspended solids such as inorganic particles are filtered. Then, the permeated water that has passed through the separation membrane 3 passes through the water collecting section 8 formed in the frame body 6 from the concave portion 5 of the support plate 1 through the permeated water flow path formed by the flow path material 2 and permeated. The water is taken out from the water tank 11 through the water outlet 7. On the other hand, the air diffuser 12 generates bubbles in parallel with the filtration, and the upward flow parallel to the membrane surface of the element 9 generated by the air lift action of the bubbles separates the filtrate deposited on the membrane surface.

  Of course, the liquid to be treated is not limited to sewage wastewater, but can be used in the water treatment field for water purification, clean water treatment, wastewater treatment, industrial water production, river water, lake water, groundwater, seawater, etc. Sewage, waste water, etc. can be treated water.

The water permeability and blocking rate of the separation membranes in the examples and comparative examples were measured as follows.
To measure the water permeability of the separation membrane, cut the separation membrane into a circle with a diameter of 50 mm, set it in a cylindrical filter holder, and pre-permeate the reverse osmosis membrane permeate at 25 ° C. for 5 minutes at a head height of 1 m. Then, the permeated water was sampled for 5 minutes after permeation.

  For the rejection, a calibration curve of the concentration was obtained using latex particles (polystyrene latex fine particles manufactured by Ceradyne, nominal particle size 0.088 μm, standard deviation 0.0062 μm). That is, a separation membrane (diameter: 43 mm) is set in a holder for measuring a fine particle rejection rate (UHP-43K, manufactured by Advantech Toyo Co., Ltd.), raw water prepared to a latex particle concentration of about 10 ppm is added, and a nitrogen pressure with an evaluation pressure of 10 kPa is added. Then, 25 cc of permeated water was collected while stirring the raw water, and 25 cc of permeated water was collected, and the latex particle concentration of the raw water and the permeated water was measured with an ultraviolet ray having a wavelength of 202 nm using a spectrophotometer (manufactured by Hitachi, U-3200). The blocking rate was determined from the concentration ratio by the following formula.

  Adhesion between the separation membrane and the element support plate made of ABS resin is done by placing the element support plate on an electronic balance (TLC-500, manufactured by Tanita Co., Ltd.), and hot melt with a width of 10 mm, length of 50 mm, and thickness of 150 μm. Place a film of adhesive, place a separation membrane on it, and apply a 0.13 MPa load over 20 seconds with an iron heated to 165 ° C. from above the separation membrane. After adhesion, the membrane sample has a width of 25 mm. The film sample for adhesive strength measurement was produced by cutting.

Further, the adhesion test of the separation membrane "Tensilon" (TENSILON (TM) / UTM-4L TOYO MEASURING INSTRUMENTS CO., LTD) by using, in accordance with JIS K6854 180 degree peel test, tensile speed 200 mm / min, A separation test was performed under the condition that the sample width of the separation membrane was 25 mm, and the adhesive strength was obtained.

<Example 1>
Polyvinylidene fluoride (PVDF / manufactured by Kureha Chemical Industry Co., Ltd., KF # 850) resin as a main component resin in a polyvinylidene fluoride-based blend resin, and polysulfone (PS / manufactured by Teijin Amoco Engineering Plastics Co., Ltd., P-3500) as an auxiliary component resin Using polyoxyethylene sorbitan monostearate as a pore-opening agent, N, N-dimethylformamide (DMF) as a solvent, and H ₂ O as a non-solvent, respectively, and stirring them sufficiently at a temperature of 95 ° C. A film-forming stock solution having a composition was obtained.

Polyvinylidene fluoride (PVDF): 15.3% by weight
Polysulfone (PS): 1.7% by weight
Polyoxyethylene sorbitan monostearate: 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after the film-forming stock solution is cooled to 30 ° C., it is applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and after application, immediately immersed in pure water at 20 ° C. for 5 minutes. It was immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide as a solvent and polyoxyethylene sorbitan monostearate as a pore opening agent to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle size of 0.088 μm was measured for the separation membrane, it was a high value of 99.1%. Moreover, the water permeability was 40.2 × 10 ⁻⁹ m ³ / m ² · s · Pa.
When a peel test of adhesive strength was performed by attaching the separation membrane and an ABS resin element support plate with a hot melt adhesive, a desired level of 90.8 N / 25 mm was satisfied. Incidentally, showing the results in Table 1.

  Furthermore, as shown in FIG. 4, the surface of the separation membrane formed with the blend resin (the surface of the porous separation functional layer) has the same level as that of the unblended polyvinylidene fluoride resin, even by observation with a scanning electron microscope. A surface structure was observed. In addition, as shown in FIG. 16, the back surface structure (the state in which the stock solution was removed) was also observed by a scanning electron microscope, with the polyvinylidene fluoride resin covering the base material layer.

<Example 2>
Polyvinylidene fluoride (PVDF) resin as a main component resin in a polyvinylidene fluoride-based blend resin, polysulfone (PS) as a secondary component resin, polyoxyethylene sorbitan monostearate as a pore-opening agent, N, N-dimethylformamide (DMF as a solvent) ), H ₂ O was used as a non-solvent, and these were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 11.9% by weight
Polysulfone (PS): 5.1% by weight
Polyoxyethylene sorbitan monostearate: 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after cooling the film-forming stock solution to 30 ° C., it was applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and after application, immediately immersed in pure water at 20 ° C. for 5 minutes, Further, it was immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide and polyoxyethylene sorbitan monostearate to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle size of 0.088 μm was measured for the separation membrane, it was a high value of 98.8%. Moreover, the water permeability was 40.9 × 10 ⁻⁹ m ³ / m ² · s · Pa.
Next, when the separation membrane and the ABS plate as the element support plate were pasted with a hot melt adhesive and a peel test for the adhesive strength was performed, the desired level of 71.2 N / 25 mm was satisfied. The results are shown in Table 1.

  Furthermore, as shown in FIG. 5, the surface structure of the same level as that of the unblended polyvinylidene fluoride resin was observed on the surface of the separation membrane formed by the blend resin as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

<Example 3>
Polyvinylidene fluoride (PVDF) resin as a main component resin in a polyvinylidene fluoride-based blend resin, polysulfone (PS) as a secondary component resin, polyoxyethylene sorbitan monostearate as a pore-opening agent, N, N-dimethylformamide (DMF as a solvent) ), H ₂ O was used as a non-solvent, and these were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 8.67% by weight
Polysulfone (PS): 8.33 wt%
Polyoxyethylene sorbitan monostearate: 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after cooling the film-forming stock solution to 30 ° C., it was applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and after application, immediately immersed in pure water at 20 ° C. for 5 minutes, Further, it was immersed in hot water at 90 ° C. for 2 minutes to wash away N, N-dimethylformamide and polyoxyethylene sorbitan monostearate to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle size of 0.088 μm was measured for the separation membrane, it was a high value of 99.0%. Moreover, the water permeability was 43.1 × 10 ⁻⁹ m ³ / m ² · s · Pa.
Next, when the separation membrane and the ABS plate as the element support plate were pasted with a hot melt adhesive and a peel test for the adhesive strength was performed, the desired level of 34.7 N / 25 mm was satisfied. The results are shown in Table 1.

  Furthermore, as shown in FIG. 6, the surface structure of the same level as that of the unblended polyvinylidene fluoride resin was observed on the surface of the separation membrane formed with the blend resin as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

<Example 4>
Polyvinylidene fluoride (PVDF) resin as the main component resin in the polyvinylidene fluoride blend resin, polysulfone (PS) as the secondary component resin, polyethylene glycol (PEG 20,000) as the pore-opening agent, N, N-dimethylformamide (DMF as the solvent) ), H ₂ O was used as a non-solvent, and these were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 15.3% by weight
Polysulfone (PS): 1.7% by weight
Polyethylene glycol (PEG 20,000): 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after the film-forming stock solution is cooled to 30 ° C., it is applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm. washed out N, N- dimethylformamide and polyethylene glycol was further immersed for 2 minutes in 90 ° C. hot water, to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle size of 0.088 μm was measured for the above separation membrane, it was a high value of 97.1%. Moreover, the water permeability was 34.3 × 10 ⁻⁹ m ³ / m ² · s · Pa.
Next, when the separation membrane and the ABS plate as the element support plate were pasted with a hot melt adhesive and subjected to a peel test of the adhesive strength, the desired level of 85.1 N / 25 mm was satisfied. The results are shown in Table 1.

  Furthermore, on the surface of the separation membrane formed with the blend resin, a surface structure of the same level as that of the unblended polyvinylidene fluoride resin was observed by scanning electron microscope observation as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

<Example 5>
Polyvinylidene fluoride (PVDF) resin as the main component resin in the polyvinylidene fluoride blend resin, polysulfone (PS) as the secondary component resin, polyethylene glycol (PEG 20,000) as the pore-opening agent, N, N-dimethylformamide (DMF as the solvent) ), H ₂ O was used as a non-solvent, and these were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 11.9% by weight
Polysulfone (PS): 5.1% by weight
Polyethylene glycol (PEG 20,000): 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after cooling the film-forming stock solution to 30 ° C., it was applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and after application, immediately immersed in pure water at 20 ° C. for 5 minutes, washed out N, N- dimethylformamide and polyethylene glycol was further immersed for 2 minutes in 90 ° C. hot water, to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle diameter of 0.088 μm was measured for the separation membrane, it was a high value of 98.2%. Moreover, the water permeability was 36.2 × 10 ⁻⁹ m ³ / m ² · s · Pa.
Next, when the separation membrane and the ABS plate as the element support plate were pasted with a hot melt adhesive and subjected to a peel test for adhesive strength, the desired level of 60.8 N / 25 mm was satisfied. The results are shown in Table 1.

  Further, as shown in FIG. 8, the surface structure of the same level as that of the unblended polyvinylidene fluoride resin was not observed on the surface of the separation membrane formed with the blend resin as shown in FIG.

<Example 6>
Polyvinylidene fluoride (PVDF) resin as the main component resin in the polyvinylidene fluoride blend resin, polysulfone (PS) as the secondary component resin, polyethylene glycol (PEG 20,000) as the pore-opening agent, N, N-dimethylformamide (DMF as the solvent) ), H ₂ O was used as a non-solvent, and these were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 8.67% by weight
Polysulfone (PS): 8.33 wt%
Polyethylene glycol (PEG 20,000): 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after cooling the film-forming stock solution to 30 ° C., it was applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm, and after application, immediately immersed in pure water at 20 ° C. for 5 minutes, washed out N, N- dimethylformamide and polyethylene glycol was further immersed for 2 minutes in 90 ° C. hot water, to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle size of 0.088 μm was measured for the separation membrane, it was a high value of 98.0%. Moreover, the water permeability was 38.0 × 10 ⁻⁹ m ³ / m ² · s · Pa.
Next, when the separation membrane and the ABS plate as the element support plate were pasted with a hot melt adhesive and subjected to a peel test for adhesive strength, the desired level of 35.1 N / 25 mm was satisfied. The results are shown in Table 1.

  Furthermore, as shown in FIG. 9, the surface structure of the same level as that of the unblended polyvinylidene fluoride resin was observed on the surface of the separation membrane formed by the blend resin as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

< Reference Example 1 >
Polyvinylidene fluoride (PVDF) resin as a main component resin in a polyvinylidene fluoride-based blend resin, polyacrylonitrile (PAN) as an auxiliary component resin, polyethylene glycol (PEG 20,000) as a pore opening agent, N, N-dimethylformamide (as a solvent) DMF) and H ₂ O as non-solvents were used respectively, and these were sufficiently stirred at a temperature of 95 ° C. to obtain a film forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 15.3% by weight
Polyacrylonitrile (PAN): 1.7% by weight
Polyethylene glycol (PEG 20,000): 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after the film-forming stock solution is cooled to 30 ° C., it is applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm. washed out N, N- dimethylformamide and polyethylene glycol was further immersed for 2 minutes in 90 ° C. hot water, to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle diameter of 0.088 μm was measured for the separation membrane, it was a high value of 98.6%. Moreover, the water permeability was 34.4 × 10 ⁻⁹ m ³ / m ² · s · Pa.
Next, when the separation membrane and the ABS plate as the element support plate were pasted with a hot melt adhesive and subjected to a peel test for adhesive strength, the desired level of 33.6 N / 25 mm was satisfied. The results are shown in Table 1.

< Reference Example 2 >
Polyvinylidene fluoride (PVDF) resin as a main component resin in a polyvinylidene fluoride-based blend resin, acrylonitrile-butadiene-styrene copolymer (ABS resin) as an auxiliary component resin, polyethylene glycol (PEG 20,000) as a pore-opening agent, and as a solvent Using N, N-dimethylformamide (DMF) and H ₂ O as a non-solvent, these were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 15.3% by weight
Acrylonitrile-butadiene-styrene copolymer (ABS resin): 1.7% by weight
Polyethylene glycol (PEG 20,000): 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after the film-forming stock solution is cooled to 30 ° C., it is applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm. washed out N, N- dimethylformamide and polyethylene glycol was further immersed for 2 minutes in 90 ° C. hot water, to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle size of 0.088 μm was measured for the separation membrane, it was a high value of 98.7%. The water permeability was 40.1 × 10 ⁻⁹ m ³ / m ² · s · Pa.
Next, when the separation membrane and the ABS plate as the element support plate were attached with a hot melt adhesive and subjected to a peel test of the adhesive strength, the desired level of 42.1 N / 25 mm was satisfied. The results are shown in Table 1.

< Reference Example 3 >
Polyvinylidene fluoride (PVDF) resin as a main component resin in a polyvinylidene fluoride-based blend resin, acrylonitrile-styrene copolymer (AS resin) as an auxiliary component resin, polyethylene glycol (PEG 20,000) as a pore-opening agent, N, N-dimethylformamide (DMF) and H ₂ O as a non-solvent were used, respectively, and these were sufficiently stirred at a temperature of 95 ° C. to obtain a film-forming stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 15.3% by weight
Acrylonitrile-styrene copolymer (AS resin): 1.7% by weight
Polyethylene glycol (PEG 20,000): 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

Next, after the film-forming stock solution is cooled to 30 ° C., it is applied to a non-woven fabric made of polyester fiber having a density of 0.48 g / cm ³ and a thickness of 220 μm. washed out N, N- dimethylformamide and polyethylene glycol was further immersed for 2 minutes in 90 ° C. hot water, to obtain a separation membrane.

Next, when the blocking rate of latex fine particles having an average particle diameter of 0.088 μm was measured for the separation membrane, it was a high value of 98.2%. Moreover, the water permeation amount was 40.6 × 10 ⁻⁹ m ³ / m ² · s · Pa.
Next, when the separation membrane and the ABS plate as the element support plate were attached with a hot melt adhesive and subjected to a peel test of the adhesive strength, the desired level of 40.3 N / 25 mm was satisfied. The results are shown in Table 1.

<Comparative Example 1>
A separation membrane obtained in the same manner as in Example 1 was evaluated except that the polysulfone resin, which is an auxiliary component resin, was not used, and only a polyvinylidene fluoride resin was used to form a membrane with a stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 17.0% by weight
Polyoxyethylene sorbitan monostearate: 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

With respect to the obtained separation membrane, the rejection rate of latex fine particles having an average particle diameter of 0.088 μm was measured and found to be 99.2%. Moreover, the water permeability was 42.3 × 10 ⁻⁹ m ³ / m ² · s · Pa.
When the separation membrane and the ABS plate as the element support plate were attached with a hot melt adhesive and subjected to a peel test of the adhesive strength, the adhesive strength was as low as 3.8 N / 25 mm. The results are shown in Table 1.

  Furthermore, the surface structure of the separation membrane was observed by scanning electron microscope observation as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

<Comparative example 2>
It was obtained in the same manner as in Example 1 except that the polyvinylidene fluoride resin as the main component resin in Example 1 was not used, and only the polysulfone resin as the subcomponent resin was used to form a film with a stock solution having the following composition. The separation membrane was evaluated.

Polysulfone (PS): 17.0% by weight
Polyoxyethylene sorbitan monostearate: 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

With respect to the obtained separation membrane, the blocking rate of latex fine particles having an average particle size of 0.088 μm was measured and found to be a low value of 83.1%. Further, the water permeability was 8.1 × 10 ⁻⁹ m ³ / m ² · s · Pa, and the water permeability was low.
Furthermore, it was 97.4 N / 25mm when it stuck on the separation membrane and the ABS board which is an element support board with the hot-melt-adhesive, and the adhesive strength peeling test was done. The results are shown in Table 1.

  Furthermore, the surface structure of the separation membrane was observed by scanning electron microscope, and a non-uniform film surface structure with a small number of pores was observed as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

<Comparative Example 3>
Polyvinylidene fluoride (PVDF) resin as a main component resin in a polyvinylidene fluoride-based blend resin, polysulfone (PS) as a secondary component resin, polyoxyethylene sorbitan monostearate as a pore-opening agent, N, N-dimethylformamide (DMF as a solvent) ), A separation membrane obtained in the same manner as in Example 1 was evaluated except that H ₂ O was used as a non-solvent and a membrane was prepared with a stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 1.7 by weight%
Polysulfone (PS): 15.3% by weight
Polyoxyethylene sorbitan monostearate: 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

The obtained separation membrane was measured for a blocking rate of latex fine particles having an average particle size of 0.088 μm, and it was a low value of 74.2%. Further, the water permeability was 12.6 × 10 ⁻⁹ m ³ / m ² · s · Pa, and the water permeability was low.
It was 88.7 N / 25mm when it stuck on the separation membrane and the ABS plate which is an element support plate with the hot melt adhesive, and the peel test of the adhesive strength was performed. The results are shown in Table 1.

  Furthermore, the surface structure of the above-mentioned separation membrane was observed by scanning electron microscope, and an uneven membrane surface structure with a small number of pores was observed as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

<Comparative example 4>
Polyvinylidene fluoride (PVDF) resin as a main component resin in a polyvinylidene fluoride-based blend resin, polysulfone (PS) as a secondary component resin, polyoxyethylene sorbitan monostearate as a pore-opening agent, N, N-dimethylformamide (DMF as a solvent) ), A separation membrane obtained in the same manner as in Example 1 was evaluated except that H ₂ O was used as a non-solvent and a membrane was prepared with a stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 5.1% by weight
Polysulfone (PS): 11.9% by weight
Polyoxyethylene sorbitan monostearate: 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

With respect to the obtained separation membrane, when the blocking rate of latex fine particles having an average particle size of 0.088 μm was measured, it was a low value of 72.1%. Further, the water permeability was as low as 17.3 × 10 ⁻⁹ m ³ / m ² · s · Pa.
It was 73.9N / 25mm when it stuck on the separation membrane and the ABS plate which is an element support plate with a hot melt adhesive, and the peel test of the adhesive strength was performed. The results are shown in Table 1.

  Furthermore, the surface structure of the above-mentioned separation membrane was observed by scanning electron microscope, and an uneven membrane surface structure with a small number of pores was observed as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

<Comparative Example 5>
In Example 4, only the polyvinylidene fluoride resin, which is the main component resin, without using the polysulfone resin, which is a subcomponent resin, polyethylene glycol (PEG 20,000) as the pore-opening agent, and N, N-dimethylformamide (DMF) as the solvent ), A separation membrane obtained in the same manner as in Example 4 was evaluated except that H ₂ O was used as a non-solvent and a membrane was prepared with a stock solution having the following composition.

Polyvinylidene fluoride (PVDF): 17.0% by weight
Polyethylene glycol (PEG 20,000): 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

With respect to the obtained separation membrane, the rejection rate of latex fine particles having an average particle diameter of 0.088 μm was measured and found to be 99.2%. Moreover, the water permeability was as low as 22.3 × 10 ⁻⁹ m ³ / m ² · s · Pa.
It was 4.6 N / 25 mm when it was pasted with a hot melt adhesive on the separation membrane and an ABS plate as an element support plate, and a peel test of the adhesive strength was performed. The results are shown in Table 1.

  Further, the surface structure of the separation membrane was observed by a scanning electron microscope, as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

<Comparative Example 6>
Without using the polyvinylidene fluoride resin is a main component resin of Oite in Example 4, only a polysulfone resin is a subcomponent resin, except that a film was formed by a stock solution having the following composition in the same manner as in Example 4 to give The obtained separation membrane was evaluated.

Polysulfone (PS): 17.0% by weight
Polyethylene glycol (PEG 20,000): 8.0% by weight
N, N-dimethylformamide (DMF): 72.0% by weight
H ₂ O: 3.0% by weight

With respect to the obtained separation membrane, the blocking rate of latex fine particles having an average particle diameter of 0.088 μm was measured and found to be a low value of 72.3%. Further, the water permeability was 20.2 × 10 ⁻⁹ m ³ / m ² · s · Pa. That is, the water permeability decreased.
Furthermore, it was 98.0N / 25mm when it stuck on the separation membrane and the ABS board which is an element support board with the hot-melt-adhesive, and the adhesive strength peeling test was done. The results are shown in Table 1.

  Further, the surface structure of the separation membrane was observed by scanning electron microscope observation as shown in FIG. Moreover, the back surface structure was the state which covered the base material layer with the polyvinylidene fluoride resin similarly to the case of Example 1 (FIG. 16).

It is a general | schematic expanded perspective view of the element using the separation membrane which concerns on this invention. It is a general | schematic cross-sectional view in the AA cross section of the element (element of FIG. 1) using the separation membrane which concerns on this invention. It is a schematic flowchart of the liquid processing method using the separation membrane module which concerns on this invention. 2 is a scanning electron micrograph of the surface structure of a separation membrane according to Example 1. FIG. 4 is a scanning electron micrograph of the surface structure of a separation membrane according to Example 2. 4 is a scanning electron micrograph of the surface structure of a separation membrane according to Example 3. 4 is a scanning electron micrograph of the surface structure of a separation membrane according to Example 4. 6 is a scanning electron micrograph of the surface structure of a separation membrane according to Example 5. 6 is a scanning electron micrograph of the surface structure of a separation membrane according to Example 6. FIG. 4 is a scanning electron micrograph of the surface structure of a separation membrane according to Comparative Example 1. 4 is a scanning electron micrograph of the surface structure of a separation membrane according to Comparative Example 2. 6 is a scanning electron micrograph of the surface structure of a separation membrane according to Comparative Example 3. 6 is a scanning electron micrograph of the surface structure of a separation membrane according to Comparative Example 4. 6 is a scanning electron micrograph of the surface structure of a separation membrane according to Comparative Example 5. 6 is a scanning electron micrograph of the surface structure of a separation membrane according to Comparative Example 6. 2 is a scanning electron micrograph of the back side structure of a separation membrane according to Example 1. FIG.

Explanation of symbols

1: support plate 2: flow path material 3: separation membrane 4: convex part 5: concave part (groove)
6: Frame 7: Filtrate outlet 8: Liquid collector 9: Element 10: Separation membrane module 11: Waste treatment water tank 12: Air diffuser 13: Blower 14: Pump

Claims (7)

In the separation membrane composed of the base material layer and the porous separation functional layer, the porous separation functional layer is a blend of 51% by weight to 95% by weight of the polyvinylidene fluoride resin and 5% by weight to 49% by weight of the polysulfone resin. A polyvinylidene fluoride porous separation membrane comprising a resin.   The separation membrane is a flat membrane in which a part of the resin constituting the porous separation functional layer enters the base material layer and a layer in which the porous separation functional layer and the base material layer are combined exists. The polyvinylidene fluoride-based porous separation membrane described. The polyvinylidene fluoride-based porous separation membrane according to claim 1 or 2, wherein the rejection rate of fine particles having an average particle size of 0.9 µm is at least 90%. The polyvinylidene fluoride porous separation membrane according to any one of claims 1 to 3, wherein the density of the porous substrate is 0.7 g / cm ³ or less.   The polyvinylidene fluoride porous separation membrane according to any one of claims 1 to 4, wherein the porous substrate is a nonwoven fabric or a woven or knitted fabric.   A membrane separation element comprising the flat membrane-like separation membrane according to any one of claims 1 to 5, a flow path material, and a permeate collecting member.   A membrane separation module in which a plurality of membrane separation elements according to claim 6 are accommodated in a housing.