JP5386901B2 - Separation membrane support, separation membrane and fluid separation element using the same - Google Patents

Description

The present invention relates to a support that supports a separation membrane such as a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, and a reverse osmosis membrane, which is composed of a long-fiber nonwoven fabric composed of composite filaments and excellent in rigidity and surface smoothness. Is. The present invention also relates to a separation membrane and a fluid separation element using the same.

  Membrane technology is often applied to water treatment in recent years. For example, microfiltration membranes or ultrafiltration membranes are used for water purification plants, reverse osmosis membranes for seawater desalination, and reverse osmosis membranes or nanofiltration membranes for semiconductor manufacturing water, boiler water, medical water, laboratory pure water, etc. In addition, a membrane separation activated sludge method using a microfiltration membrane or an ultrafiltration membrane is also applied to sewage wastewater treatment.

  These separation membranes are roughly classified into flat membranes and hollow fiber membranes according to their shapes, but flat membranes formed mainly from synthetic polymers are generally non-woven fabrics because the membrane itself having a separation function is inferior in mechanical strength. In many cases, it is used integrally with a support such as woven fabric or cloth.

  In general, a membrane having a separating function and a support are a method of casting and fixing a polymer solution that is a raw material of a membrane having a separating function on a nonwoven fabric or a woven fabric, or a semipermeable membrane such as a reverse osmosis membrane. Are integrated by, for example, a method in which a polymer solution is cast on a nonwoven fabric or a woven fabric to form a support layer, and then a semipermeable membrane is formed on the support layer. Therefore, for non-woven fabrics and woven fabrics that serve as a support, when the polymer solution is cast, it penetrates by over-penetration, the membrane material is peeled off, and the film is uneven due to fluffing of the support. There is a need for excellent film forming properties that do not cause defects such as crystallization and pinholes.

  In addition, particularly in the case of a semipermeable membrane such as a reverse osmosis membrane that is often used under high pressure, the support is required to have high mechanical strength and dimensional stability.

As such a separation membrane support and a method for producing the same, a surface layer using a thick fiber and a surface layer having a large surface roughness, and a back surface layer using a thin fiber and a small opening and a dense structure are used. Separation membrane support characterized by comprising a multilayer structure non-woven fabric based on a heavy structure (see Patent Document 1), a non-woven fabric for casting a polymer solution for forming a semipermeable membrane to form a membrane in semipermeable membrane support made from the nonwoven, low density layer of air permeability 5~50cc ^/ cm 2 ^/ sec and, 5 cc ^/ cm less than 2 / sec at air permeability 0.1 cc ^/ cm 2 / sec or more a nonwoven two-layer structure of integrating the dense layer of semipermeable, wherein the air permeability of the whole is 0.1cc ^/ cm ² /sec~4.5cc/cm 2 ^/ sec Membrane supports are known (see Patent Document 2) See). However, since these supports are made of short fibers, there is a risk that the film may become non-uniform or have defects due to fluffing, and further, there is no description about the strength of the nonwoven fabric, or there is no detailed description. There was a problem that a sufficient mechanical strength and dimensional stability could not be obtained.

Further, as such a separation membrane support and a method for producing the same, the average value of the longitudinal length (MD) and the transverse direction (CD) at 5% elongation is 4.0 km or more and the air permeability is 0. There is known a semipermeable membrane support characterized by comprising a nonwoven fabric of ^{2 to} 10.0 cc / cm ² · sec (see Patent Document 3). However, the support is a non-woven fabric produced by a papermaking method, and in order to obtain the characteristic mechanical strength, it is stretched in a hot water bath after melt spinning and subsequently subjected to tension heat treatment and / or relaxation heat treatment. As a result, the birefringence of the polyester fibers constituting the nonwoven fabric is extremely increased, and the heat shrinkage stress is set to a specific range, which increases the manufacturing cost and the machine direction (MD) and the transverse direction at 5% elongation. Since only the average value of the (CD) tear length is defined, the rigidity against the force (pressure) applied in the thickness direction of the separation membrane support cannot be stably expressed over a long period of time. Furthermore, since it consists of short fibers, there is a problem that the film may become non-uniform or have defects due to fluffing.
Japanese Patent Publication No. 4-21526 Japanese Patent Publication No. 5-35009 Japanese Patent No. 3153487

The present invention is constituted from a composite type filament consisting solely spunbonded nonwoven fabric which is excellent in rigidity and surface smoothness, microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, in supporting the separation membrane such as a reverse osmosis membrane An object of the present invention is to provide a separation membrane support having excellent membrane-forming properties and mechanical strength, and a separation membrane and a fluid separation element using the same.

  The present invention employs the following means in order to solve such problems.

(1) is composed of complex-type filaments arranged a low melting point polymer having a 10 to 140 ° C. melting point lower than the melting point of the high melting polymer around the high-melting polymer, said composite by a pair of upper and lower flat rolls Separation membrane support consisting only of a spunbonded nonwoven fabric with filaments thermocompression bonded, having a basis weight of 20 to 150 g / m ² , a packing density of 0.4 to 0.8, and an air flow rate of 0.2 to 30.0 cc / Cm ² / sec, the change in thickness at the time of high load relative to the time of low and low load is 0.00 to 0.03 mm, and the surface average roughness is 2 to 9 μm, Support.

( 2 ) The separation membrane support according to (1), wherein the thermoplastic continuous filament is made of a polyester polymer.

( 3 ) The separation membrane support according to (1) or (2) above, wherein the thermoplastic continuous filament has an average fiber diameter of 3 to 17 μm.

( 4 ) A separation membrane comprising a membrane having a separation function formed on the surface of the separation membrane support according to any one of (1) to (3 ) above.

( 5 ) A fluid separation element comprising the separation membrane according to ( 4 ) above.

According to the present invention, it is composed of a composite type filament and is composed only of a spunbond nonwoven fabric having excellent rigidity and surface smoothness, and when supporting a separation membrane such as a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, and a reverse osmosis membrane. It is possible to provide a separation membrane support having excellent film forming properties and mechanical strength, and a separation membrane and a fluid separation element using the same.

  The separation membrane support of the present invention is a separation membrane support that forms a membrane having a separation function on the surface thereof.

  It is important that the separation membrane support of the present invention is composed of a long-fiber nonwoven fabric composed of thermoplastic continuous filaments. As a result of studying the cause of non-uniformity and membrane defects at the time of casting of a polymer solution that often occurs when using a short fiber nonwoven fabric, the present inventors have found that the short fiber nonwoven fabric has a fluffing factor, It was found that this problem can be solved by using it. That is, by comprising a long-fiber non-woven fabric composed of thermoplastic continuous filaments, it is possible to suppress non-uniformity and membrane defects during casting of a polymer solution caused by fuzz, which occurs when a short-fiber non-woven fabric is used. . Furthermore, since the present invention is composed of thermoplastic continuous filaments, it has higher mechanical strength than short fiber nonwoven fabrics, especially papermaking nonwoven fabrics with short fiber lengths, and is a separation membrane support, particularly a semipermeable membrane that is subjected to high pressure during use. The durability which was excellent as a support body can be expressed.

Nonwoven fabric made of composite filaments constituting the separation membrane support of the present invention is a spunbonded nonwoven fabric prepared by spunbonding. Its film-forming property upon forming the separation membrane on it as possible out to obtain a separation membrane having excellent and durability good. Further, since it is possible to obtain more uniformity excellent separation membrane support, Ru also preferable der laminate comprising a plurality of spunbond nonwoven layer. The laminate 2 laminates spunbond nonwoven layers such as, a shall such substantially only spunbonded nonwoven fabric.

  It is important that the long fiber nonwoven fabric constituting the separation membrane support of the present invention has a packing density of 0.4 to 0.8, preferably 0.5 to 0.8, and 0.6 to 0.8. More preferably, it is 0.8. When the packing density is 0.4 or more, there are few voids inside the nonwoven fabric, and when used as a separation membrane support, deformation and damage are less likely to occur due to external pressure. On the other hand, if the packing density is 0.8 or less, the water permeability and air permeability of the nonwoven fabric can be secured, and the pressure loss as the separation membrane support does not become too high.

As a method for obtaining a long-fiber nonwoven fabric having a packing density of 0.4 to 0.8, as a thermoplastic continuous filament constituting the long-fiber nonwoven fabric, the high-melting polymer is around 10 to 140 around the melting point of the high-melting polymer. It is important to use a composite filament provided with a low melting point polymer having a low melting point. In addition, the average fiber diameter of the thermoplastic continuous filament constituting the long-fiber nonwoven fabric is 3 to 17 μm, and the spunbond nonwoven fabric obtained by the spunbond method can be integrated into a sheet by thermocompression bonding. This is a preferred method for obtaining a non-woven fabric having a density of 0.4 to 0.8.

It is important that the long-fiber nonwoven fabric constituting the separation membrane support of the present invention has an air permeability of 0.2 to 30.0 cc / cm ² / sec, and 0.3 to 20.0 cc / cm ² / sec. It is preferable that it is 0.4-10.0 cc / cm < ² > / sec. When the air flow rate is 0.2 cc / cm ² / sec or more, the pressure loss as the separation membrane support does not become too high. On the other hand, if the air flow rate is 30.0 cc / cm ² / sec or less, the denseness of the nonwoven fabric can be maintained and a separation membrane can be easily formed.

As a method for obtaining a long fiber nonwoven fabric having an air permeability of 0.2 to 30.0 cc / cm ² / sec, it is preferable that the average fiber diameter of the thermoplastic continuous filament constituting the long fiber nonwoven fabric is 3 to 17 μm. In addition, it is possible to adjust the basis weight of the long-fiber nonwoven fabric to 20 to 150 g / m ² , or to integrate the long-fiber nonwoven fabric obtained by the spunbond method or the like into a sheet shape by thermocompression bonding. This is a preferable method for obtaining a non-woven fabric of 0.0 cc / cm ² / sec.

  It is important that the long-fiber nonwoven fabric constituting the separation membrane support of the present invention has a thickness change amount of 0.00 to 0.03 mm at a high load with respect to a low load, and 0.00 to 0.02 mm. It is preferable that it is 0.00-0.01 mm. Here, the amount of change in thickness at high load relative to low load is the thickness when a low load (load 2 kPa) is applied with a pressurizer having a diameter of 16 mm, and a high load (load 200 kPa) is applied with the same pressurizer. The difference from the thickness when In particular, a support for a separation membrane such as a reverse osmosis membrane is required to have a high rigidity capable of withstanding a high pressure because a high reverse osmosis pressure is applied. Here, the required rigidity is the rigidity to withstand the force applied perpendicularly to the separation membrane surface and not to be deformed, and it can be said to be the desired rigidity if the change in thickness between low load and high load is small. The present inventors have found that it is suitable as a separation membrane support. If the amount of change in thickness at high load relative to low load is 0.03 mm or less, there will be little deformation due to pressure applied when used as a separation membrane support, particularly partial pressure, and membrane performance and processing capacity will be reduced. Can be maintained.

  As a method of obtaining a long fiber nonwoven fabric having a thickness change amount of 0.00 to 0.03 mm at a high load with respect to a low load, as a thermoplastic continuous filament constituting the long fiber nonwoven fabric, around a high melting point polymer It is preferable to use a composite filament in which a low melting point polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high melting point polymer. In addition, the average fiber diameter of the thermoplastic continuous filament constituting the long-fiber nonwoven fabric is set to 3 to 17 μm, and the long-fiber nonwoven fabric obtained by the spunbond method or the like is integrated into a sheet shape by thermocompression bonding. This is a preferable method for obtaining a long-fiber nonwoven fabric having a thickness change amount of 0.00 to 0.03 mm at the time of high load relative to the load.

Long-fiber nonwoven fabric composing the support for a separation membrane present invention, average surface roughness Ri 2~9μm der, it is good Mashiku is 2 to 8 m, and more preferably 2-7 [mu] m. When the surface average roughness is 2 μm or more, the surface of the nonwoven fabric is extremely densified, and when used as a separation membrane support, there is little increase in pressure loss or separation membrane peeling on the support. When the average roughness is 9 μm or less, formation of a separation membrane on the support is rarely difficult when used as a separation membrane support.

As a method for obtaining a long fiber nonwoven fabric having an average surface roughness of 2 to 9 μm, it is important to integrate the long fiber nonwoven fabric by thermocompression bonding with a pair of upper and lower flat rolls. Moreover, as the thermoplastic continuous filament constituting the long-fiber nonwoven fabric, a composite filament in which a low-melting polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high-melting polymer is disposed around the high-melting polymer. In addition, setting the average fiber diameter of the thermoplastic continuous filament constituting the long-fiber nonwoven fabric to 3 to 17 μm is also a preferable method for obtaining a long-fiber nonwoven fabric having a surface average roughness of 2 to 9 μm.

  In the present invention, the raw material of the thermoplastic continuous filament constituting the long fiber nonwoven fabric is not particularly limited as long as a long fiber nonwoven fabric suitable for the separation membrane support can be obtained. For example, a polyester polymer, a polyamide polymer, a polyolefin polymer, or a mixture or copolymer thereof is not limited at all, but more mechanical strength, heat resistance, water resistance, chemical resistance, etc. From the viewpoint of obtaining a separation membrane support having excellent durability such as the above, a polyester polymer is preferable. The polyester polymer used in the present invention is a polyester composed of an acid component and an alcohol component, and the acidic component includes aromatic carboxylic acids such as terephthalic acid, isophthalic acid and phthalic acid, adipic acid, sebacic acid and the like. Aliphatic dicarboxylic acids such as aliphatic dicarboxylic acid and cyclohexanecarboxylic acid can be used, and ethylene glycol, diethylene glycol, polyethylene glycol and the like can be used as the alcohol component. Examples of the polyester polymer include polyethylene terephthalate resin, polybutylene terephthalate resin, polytrimethylene terephthalate resin, polyethylene naphthalate resin, polylactic acid resin, polybutylene succinate resin, and the like. Examples include coalescence.

  In addition, when the separation membrane support is discarded after use, the biodegradable resin is also preferably used as a raw material for the thermoplastic continuous filament constituting the long fiber nonwoven fabric because it is easy to discard and has a low environmental impact. Examples of the biodegradable resin used in the present invention include polylactic acid resin, polybutylene succinate resin, polycaprolactone resin, polyethylene succinate resin, polyglycolic acid resin, polyhydroxybutyrate resin, etc. However, it is a plant-derived resin that does not deplete petroleum resources, has relatively high mechanical properties and heat resistance, and has recently been highlighted as a biodegradable resin with low production costs. The polylactic acid resin used is preferably used as a raw material for fibers constituting the nonwoven fabric. The polylactic acid resin used in the present invention is preferably poly (D-lactic acid), poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, or a blend thereof.

  The long fiber nonwoven fabric constituting the separation membrane support of the present invention has a crystal nucleating agent, a matting agent, a lubricant, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, as long as the effects of the present invention are not impaired. A hydrophilic agent or the like may be added. In particular, when thermocompression molding of long fiber nonwoven fabrics, metal oxides such as titanium oxide, which have the effect of improving the adhesion of long fiber nonwoven fabrics by increasing the thermal conductivity, and releasability between thermocompression rolls and webs. It is preferable to add an aliphatic bisamide such as ethylenebisstearic acid amide and / or an alkyl-substituted aliphatic monoamide, which has an effect of improving the adhesion stability by increasing the number. These various additives may be present in the thermoplastic continuous filament or may be present on the surface thereof.

In the present invention, a composite type filament composing the long-fiber nonwoven fabric is a composite thermoplastic continuous filaments made of several components, in the separation membrane support of the present invention, around the high-melting polymer, the refractory A spunbonded nonwoven fabric composed of composite thermoplastic continuous filaments in which a low melting point polymer having a melting point lower by 10 to 140 ° C. than the melting point of the polymer is used . A low-melting polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high-melting polymer is disposed around the high-melting polymer to form a long fiber nonwoven fabric by thermocompression bonding and used as a separation membrane support. In this case, since the filaments constituting the nonwoven fabric are firmly bonded to each other, nonuniformity at the time of casting the polymer solution due to fluffing and film defects can be suppressed. Further, by using such a composite thermoplastic continuous filament, the filaments constituting the nonwoven fabric are firmly bonded to each other, and the number of bonding points is increased as compared to the mixed fiber type. The amount of change in thickness at high loads can be controlled to 0.03 mm or less, and the dimensional stability and durability when used as a separation membrane support, particularly a semipermeable membrane support that is subjected to high pressure during use. Connected. If the melting point difference between the high melting point polymer and the low melting point polymer is 10 ° C. or higher, the desired thermal adhesiveness can be obtained, and if it is 140 ° C. or lower, the low melting point polymer component is applied to the thermocompression bonding roll during thermocompression bonding. Can be prevented from being fused and the productivity is lowered. Good preferable range of the melting point difference between the high-melting polymer and low-melting polymer is 20 to 120 ° C., still more preferably in the range of, Ru 30 to 100 ° C. der. For combinations of high melting and low-melting polymer in the case of this (high melting point polymer / low melting point polymer), but not where to obtain a long-fiber nonwoven fabric suitable for the separation membrane support be limited if possible And combinations of polyethylene terephthalate resin / polybutylene terephthalate resin, polyethylene terephthalate resin / polytrimethylene terephthalate resin, polyethylene terephthalate resin / polylactic acid resin, polyethylene terephthalate resin / copolymerized polyethylene terephthalate resin, and the like. As the copolymer component, isophthalic acid or the like is preferably used.

  Further, in the separation membrane support of the present invention, a composite thermoplastic continuous filament in which a low melting point polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high melting point polymer is disposed around the high melting point polymer. When the separation membrane is formed on the separation membrane support of the present invention, the melting point of the high-melting polymer in the case of the long-fiber nonwoven fabric composed of the separation membrane is excellent in film forming properties and excellent in durability. Although it will not be limited if it can be obtained, it is preferable that it is the range of 160-320 degreeC. When the melting point of the high-melting polymer is 160 ° C. or higher, when a long-fiber nonwoven fabric is formed and used as a separation membrane support, even if it passes through a process of applying heat during the production of the separation membrane or fluid separation element, the shape stability is improved. If it is excellent and it is 320 degrees C or less, it can suppress that the heat energy for melting at the time of long-fiber nonwoven fabric manufacture is consumed greatly, and productivity falls. A more preferable range of the melting point of the high melting point polymer is 170 to 300 ° C, and a more preferable range is 180 to 280 ° C.

The proportion of the low melting point polymer in the composite thermoplastic continuous filament is not limited as long as a long-fiber nonwoven fabric suitable for the separation membrane support can be obtained, but it is preferably 10 to 70 wt%. More preferably, it is 15-60 wt%, and it is further more preferable that it is 20-50 wt%. If the proportion of the low melting point polymer is 10 wt% or more, the desired thermal adhesiveness can be obtained, and if it is 70 wt% or less, the low melting point polymer component is fused to the thermocompression-bonding roll at the time of thermocompression bonding. It can suppress that property falls.
The composite form of the composite thermoplastic continuous filament is not limited as long as a long fiber nonwoven fabric suitable for the separation membrane support can be obtained. For example, a concentric core-sheath type, an eccentric core-sheath type, a sea-island type, etc. In addition, examples of the cross-sectional shape of the filament include a circular cross-section, a flat cross-section, a polygonal cross-section, a multi-leaf cross-section, and a hollow cross-section. Above all, filaments can be firmly bonded to each other by thermocompression bonding. Furthermore, the thickness of the resulting separation membrane support can be reduced, and the separation membrane area per unit when used as a fluid separation element can be increased. Therefore, it is preferable to use a concentric core-sheath type for the composite form and a circular cross section or a flat cross section as the filament shape.

In the long-fiber nonwoven fabric composing the support for a separation membrane present invention, the average and the average fiber diameter of thermoplastic continuous filaments are converted at a density 1.38 g / cm ³ of 3～17Myuemu (polyethylene terephthalate fiber fineness of 0.1 to 3. 0 dtex), preferably 5 to 15 μm (0.3 to 2.5 dtex), and more preferably 7 to 14 μm (0.5 to 2.0 dtex). If the average fiber diameter of the thermoplastic continuous filament constituting the long-fiber nonwoven fabric is 3 μm or more (fineness is 0.1 dtex or more), the spinnability is less likely to deteriorate during the production of the long-fiber nonwoven fabric, and the ventilation of the separation membrane support Therefore, good film-forming property can be obtained with little film peeling at the time of casting the polymer solution. On the other hand, if the average fiber diameter of the thermoplastic continuous filament constituting the long fiber nonwoven fabric is 17 μm or less (fineness is 3.0 dtex or less), a long fiber nonwoven fabric and a separation membrane support excellent in uniformity can be obtained. In addition, since the separation membrane support can be densified, it is possible to obtain a good membrane forming property with less permeation and the like during casting of the polymer solution.

Long-fiber nonwoven fabric composing the support for a separation membrane present invention preferably has a basis weight is 20 to 150 g / ^{m 2,} more preferably from 30 to 120 g / ^{m 2,} is 40~90g / ^{m 2} More preferably. If the basis weight of the long-fiber nonwoven fabric constituting the separation membrane support is 20 g / m ² or more, it is easy to obtain good film-forming properties with little over-permeation at the time of casting a polymer solution, mechanical strength, durability It becomes easy to obtain a separation membrane having excellent properties. On the other hand, when the basis weight of the separation membrane support is 150 g / m ² or less, the thickness of the separation membrane is reduced, and the separation membrane area per fluid separation element unit is easily increased.

About the manufacturing method of the separation membrane support of the present invention, it is a long-fiber nonwoven fabric composed of thermoplastic continuous filaments, with a packing density of 0.4 to 0.8 and an air flow rate of 0.2 to 30.0 cc / It is cm ² / sec, and the amount of change in thickness at the time of high load with respect to low load is 0.00 to 0.03 mm. However, a spunbond method, a melt blow method, and a method of laminating these long fiber nonwoven fabrics are preferably used.

  In the case of the spunbond method, a molten thermoplastic polymer is extruded from a nozzle, drawn and drawn by a high-speed suction gas, and then spun. Then, the fibers are collected on a moving conveyor to form a web, and further heated continuously. Although it can be integrated and manufactured by performing crimping, entanglement, etc., the spinning speed is preferably 2000 m / min or more, and more preferably 3000 m / min or more in order to highly orientate and crystallize the constituent fibers. More preferably, it is more preferably 4000 m / min or more. When the thermoplastic continuous filament is formed into a composite form such as a core-sheath type, a normal composite method can be employed.

  In the case of the melt-blowing method, the thermoplastic polymer can be stretched by drawing a heated high-speed gas fluid onto the molten thermoplastic polymer to form ultrafine fibers, which can be collected.

  Further, in order to obtain a separation membrane having good film forming properties and excellent mechanical strength and durability when the separation membrane is formed, it is preferably a long length obtained by a spunbond method or the like in terms of suppressing fuzz. It is preferable to integrate the fiber nonwoven fabric into a sheet by thermocompression bonding, and the amount of change in thickness at high load relative to low load can be easily controlled to 0.03 mm or less. It is more preferable to press and integrate. The flat roll is a roll having no irregularities on the surface of the roll, and a metal roll or an elastic roll can be adopted.

  An elastic roll is a roll which consists of a material which has elasticity compared with metal rolls. Examples of the material of the elastic roll include so-called paper rolls such as paper, cotton, and aramid paper, and resin rolls such as urethane resin, epoxy resin, silicon resin, and hard rubber.

  As a combination of a pair of flat rolls, a metal roll and a metal roll can be paired, or a metal roll and an elastic roll can be paired. Moreover, since the anchoring effect which suppresses peeling of a separation membrane when using as a separation membrane support can be obtained by suppressing the fusion of fibers on the surface of the non-woven fabric and maintaining the form, a pair of flat rolls It is also a preferable method to make a temperature difference between the rolls. In particular, a method of thermocompression bonding with a heated metal roll and a non-heated elastic roll can be preferably employed from the viewpoint of the anchoring effect.

  As temperature of the flat roll to heat, it is preferable that it is 80-20 degreeC lower than melting | fusing point of the polymer which comprises at least the surface of the thermoplastic filament which comprises a long-fiber nonwoven fabric, and it is more preferable that it is 60-30 degreeC lower.

  Further, the temperature of the other flat roll (on the low temperature side) of the pair of flat rolls is preferably 40 to 120 ° C. lower than the temperature of the flat roll on the high temperature side. By setting the temperature difference between the flat roll on the low temperature side and the flat roll on the high temperature side to 40 ° C. or more, more preferably 60 ° C. or more, it is possible to suppress the occurrence of extremely high density portions on the surface of the long fiber nonwoven fabric. There is little film peeling due to insufficient permeation during casting of the molecular polymer solution, and good film forming properties can be obtained. On the other hand, when the temperature difference between the low-temperature side flat roll and the high-temperature side flat roll is 120 ° C. or less, more preferably 100 ° C. or less, delamination of the laminated long-fiber nonwoven fabric can be suppressed. Good film-forming properties can be obtained with little over-permeation at the time of casting of the solution.

  Further, the temperature during processing of the upper and lower rolls is preferably in the range of ± 15 ° C. or less, more preferably in the range of ± 10 ° C. or less, centering on the temperature at the start of processing, and ± 5 ° C. or less. More preferably, it is the range. Although it is generally difficult to strictly control the temperature of the non-heated elastic roll, preliminary operation is performed in a state where it is in contact with a heated metal roll before processing, or the temperature of the elastic roll during processing. If it becomes too high, contact with air blow, shower ring, cooling roll, etc. If it becomes too low, heat with an infrared heater, heat medium circulation inside the roll, contact with heating roll, etc. Can be controlled.

  The linear pressure of the flat roll is preferably 20 to 500 kg / cm because the amount of change in thickness at high load relative to low load can be easily controlled to 0.03 mm or less. By setting the linear pressure of the flat roll to 20 kg / cm or more, more preferably 50 kg / cm or more, and even more preferably 100 kg / cm or more, delamination of the long fiber nonwoven fabric can be suppressed, and the flow of the polymer solution can be reduced. Good film-forming property can be obtained with little excessive permeation at the time of stretching. On the other hand, by setting the linear pressure of the flat roll to 500 kg / cm or less, it is possible to suppress the generation of extremely high density portions on the surface of the long-fiber nonwoven fabric, and film peeling due to insufficient penetration during casting of the polymer solution. Therefore, good film forming property can be obtained.

  In addition, thermocompression bonding with a pair of flat rolls is performed continuously after a pair of flat rolls or a collection nonwoven fabric in a temporarily bonded state is obtained by a collecting conveyor used for collecting one flat roll and a web. Alternatively, it is preferable to adopt a two-stage pressure bonding method in which after winding once, the film is further heat-bonded with a flat roll once again. By doing so, the characteristic of a long-fiber nonwoven fabric can be controlled more precisely. Also in the case of laminated long-fiber nonwoven fabric, a high-density surface layer is formed on the surface of each layer by thermocompression in the first stage, and a laminate is formed by thermocompression in the second stage, so that a high-density layer is formed at the lamination interface. Can be obtained, and there is little over-permeation at the time of casting of the polymer solution and good film-forming properties can be obtained.

  In the first-stage thermocompression bonding in the two-stage crimping method, since the nonwoven fabric can be densified at the time of the second-stage thermocompression bonding, the filling density of the temporarily bonded nonwoven fabric is 0.1 to 0.3. Preferably, the temperature of the heat roll at that time is 140 to 20 ° C. lower than the melting point of the fiber (or the low melting point portion) constituting the long fiber nonwoven fabric, and the linear pressure is preferably 5 to 80 kg / cm. .

  By setting the difference in melting point between the temperature of the flat roll and the thermoplastic continuous filament (or its low melting point portion) in the first stage of thermocompression bonding to 140 ° C. or less, more preferably 120 ° C. or less, and even more preferably 100 ° C. or less. A high-density layer can be formed on the front side and / or the back side of the long fiber nonwoven fabric. On the other hand, by setting the temperature to 20 ° C. or higher, more preferably 40 ° C. or higher, it is possible to prevent the fusion on the front side and / or the back side of the long-fiber nonwoven fabric from proceeding excessively and making integration difficult.

  Moreover, a high-density layer can be formed on the front side and / or the back side of the long-fiber nonwoven fabric by setting the linear pressure in the first-stage thermocompression bonding to 5 kg / cm or more, more preferably 10 kg / cm or more. . On the other hand, 80 kg / cm or less, more preferably 70 kg / cm or less, and even more preferably 60 kg / cm or less, the fusion on the front side and / or the back side of the long-fiber nonwoven fabric proceeds excessively, making integration difficult. Can be prevented.

  The long-fiber non-woven fabric constituting the separation membrane support of the present invention may be a single-layer long-fiber non-woven fabric as described above, but a separation membrane support with better uniformity can be obtained. Therefore, a laminate composed of a plurality of long fiber nonwoven fabric layers is also a preferred form. Regarding the method for producing a laminate, for example, as a method for producing a laminate composed of two layers of spunbond nonwoven fabric, two temporarily bonded spunbond nonwoven fabrics obtained by a pair of flat rolls by the above-described two-stage adhesion method are used. The method of carrying out thermocompression bonding with a flat roll again after layering can be preferably used. In addition, as a method for producing a laminate having a three-layer structure in which a meltblown nonwoven fabric is disposed between two layers of a spunbond nonwoven fabric, the spunbond nonwoven fabric in a temporarily bonded state obtained by a pair of flat rolls by the above-described two-stage adhesion method The two layers are stacked so that the melt blown nonwoven fabric produced on a separate line is sandwiched between them, and then heat-pressed again with a flat roll, or a spunbond nozzle and melt blown arranged on top of a series of collection conveyors. A method of collecting, laminating, and thermocompression-bonding webs that are extruded from the nozzle for splicing and the nozzle for spunbonding, respectively, in order, can be preferably used. Further, the spunbond nozzle, melt blow nozzle, and spunbond nozzle arranged on the upper part of the collection conveyor are respectively collected and laminated in order, and the laminated web is collected. A method of thermocompression bonding between a heat roll installed on a collecting conveyor and the conveyor to produce a temporarily bonded sheet, and a method of thermocompression bonding with a pair of flat rolls in a continuous process or once wound up is also preferably used. be able to.

  The separation membrane of the present invention is a separation membrane formed by forming a membrane having a separation function on the above-mentioned separation membrane support, and examples include a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, A semipermeable membrane such as a reverse osmosis membrane can be mentioned. The production method is preferably a method of forming a separation membrane by casting a polymer solution on at least one surface of the separation membrane support to form a membrane having a separation function. In the case where the separation membrane is a semipermeable membrane, it is also a preferred form that the membrane having a separation function is a composite membrane including a support layer and a semipermeable membrane layer (in this case, the support layer has a separation function). You don't have to.)

  The polymer solution cast on the separation membrane support is not limited as long as it has a separation function when it becomes a membrane, but polyarylethersulfone such as polysulfone and polyethersulfone, polyimide A solution of polyvinylidene fluoride, cellulose acetate or the like is preferably used, and in particular, a solution of polysulfone or polyarylethersulfone is more preferably used from the viewpoint of chemical, mechanical and thermal stability. The solvent can be appropriately selected according to the film-forming substance. Further, as a semipermeable membrane in the case where the separation membrane is a composite membrane including a support layer and a semipermeable membrane layer, a crosslinked polyamide membrane obtained by polycondensation of a polyfunctional acid halide and a polyfunctional amine is preferably used. it can.

  The fluid separation element of the present invention is a fluid separation element in which the above-described separation membrane is housed in a housing for easy handling, and the form thereof is not limited at all, but a flat membrane plate frame type In particular, a pleat type, a spiral type, and the like are preferable. In particular, a spiral type in which a separation membrane is spirally wound around a water collecting pipe together with a permeate flow path material and a supply liquid flow path material is preferably used. A plurality of fluid separation elements can be connected in series or in parallel to form a separation membrane unit.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited by these Examples. The characteristic values of the separation membrane support, the long-fiber nonwoven fabric constituting the separation membrane support, and the thermoplastic continuous filament constituting the long-fiber nonwoven fabric, and the characteristic values in the following examples are as follows: It is measured by the method.

(1) Melting point (° C)
Using a differential scanning calorimeter DSC-2 manufactured by Perkin Elma Co., Ltd., measurement was performed under the condition of a temperature rising rate of 20 ° C./min. Further, for a resin whose melting endotherm curve does not show an extreme value in a differential scanning calorimeter, the resin was heated on a hot plate, and the temperature at which the resin was completely melted by microscopic observation was taken as the melting point.

(2) Intrinsic viscosity IV
The intrinsic viscosity IV of the polyethylene terephthalate resin was measured by the following method.
8 g of a sample was dissolved in 100 ml of orthochlorophenol, and a relative viscosity η _r was determined by the following formula using an Ostwald viscometer at a temperature of 25 ° C.
η _r = η / η ₀ = (t × d) / (t ₀ × d ₀ )
Where η: viscosity of the polymer solution
η ₀ : viscosity of orthochlorophenol
t: Dropping time of solution (second)
d: density of the solution (g / cm ³ )
t ₀ : Fall time of orthochlorophenol (seconds)
d ₀ : Orthochlorophenol density (g / cm ³ )
Then, from the relative viscosity η _r , the following formula:
IV = 0.0242η _r +0.2634
Was used to calculate the intrinsic viscosity IV.

(3) Average fiber diameter (μm)
Ten small sample samples are taken at random from the nonwoven fabric, photographed with a scanning electron microscope at a magnification of 500 to 3000 times, 10 from each sample, the diameter of a total of 100 fibers is measured, and the average value is calculated. Calculated by rounding off the first decimal place.

(4) Average fineness (dtex)
The average fineness was calculated from the average fiber diameter obtained above by the following formula.
Average fineness (dtex) = (d × D ² × π / 4) × 10 ⁻⁸
Where d: density (g / cm ³ )
D: Single fiber diameter by number average (nm)
The fiber density in this example is 1.38 g / cm ³ for polyethylene terephthalate resin and copolymerized polyester resin, 1.32 g / cm ³ for polybutylene terephthalate resin, and 1.27 g / cm for polylactic acid resin. Each m ³ was used.

(5) Weight per unit area (g / m ² )
Three non-woven fabrics of 30 cm × 50 cm were collected, the weight of each sample was measured, the average value of the obtained values was converted per unit area, and the first decimal place was rounded off.

(6) Thickness (mm)
A. Based on JIS L 1906: 2000 5.1 under normal load, using a pressurizer with a diameter of 10 mm, measure 10 points at regular intervals per 1 m in the width direction of the nonwoven fabric with a load of 10 kPa, Rounded to the second decimal place.

B. At the time of low load A pressurizer having a diameter of 16 mm was used, a load of 2 kPa, a 30 cm × 50 cm non-woven fabric was measured for any 15 points in 0.01 mm units, and the third decimal place of the average value was rounded off.

C. At the time of high load Using a pressurizer with a diameter of 16 mm, a load of 200 kPa, a 3030 cm × 50 cm non-woven fabric was measured for any 15 points in units of 0.01 mm, and the average value was rounded to the third decimal place.

(7) Packing density (5), (6) A. above. Was calculated from the basis weight (g / m ² ), thickness under normal load (mm), and polymer density using the following formula and rounded off to the second decimal place.
Packing density = basis weight (g / m ² ) ÷ thickness (mm) ÷ 10 ³ ÷ polymer density (g / cm ³ ).

(8) Aeration rate (cc / cm ² / sec)
Based on the JIS L 1906: 2000 4.8 (1) Frazier method, measurement was performed on any 45 points in a 30 cm × 50 cm non-woven fabric with a pressure gauge of 125 Pa. However, the average value was rounded off to the second decimal place.

(9) Thickness change at high load relative to low load (mm)
(6) B. above. From the thickness (mm) at the time of low load obtained in step (5) above. The value obtained by subtracting the thickness (mm) at the time of the high load obtained in step 1 was defined as the amount of change in thickness at the time of high load with respect to the time of low load.

(10) Surface average roughness (μm)
Ra (arithmetic mean roughness) was determined based on the definition described in JIS B 0601: 1994 3.1. The measurement was performed using a surf coder SE-40C manufactured by Kosaka Laboratories Co., Ltd. under the conditions of a cutoff value of 2.5 mm, an evaluation length of 12.5 mm, and a feed rate of 0.5 mm / s. When the nonwoven fabric length direction is set as the evaluation length direction (vertical) and when the nonwoven fabric width direction is set as the evaluation length direction (horizontal), 10 points are measured for each of the front and back surfaces, and the average value is measured. The surface average roughness (μm) was obtained by rounding off to the nearest significant figure.

(10) Membrane cast liquid penetration-through property A 15% by weight dimethylformamide solution of polysulfone ("Udel" (registered trademark) -P3500, manufactured by Solvay Advanced Polymers) on each separation membrane support fixed on a glass plate ( Casting liquid) is cast at room temperature (20 ° C) with a thickness of 50μm, immediately immersed in pure water at room temperature (20 ° C) and left for 5 minutes to produce a polysulfone separation membrane for seawater desalination did.
Next, the reverse surface of the produced reverse osmosis membrane was visually observed, and the penetration property of the cast liquid was evaluated in the following five stages.
5 points: There is no see-through of cast liquid.
4 points: There is almost no see-through of the casting liquid (area ratio of the back-through part is less than 5%).
3 points: See-through of cast liquid is observed (area ratio of back-through part is 5 to 50%).
2 points: Cast-through of the cast liquid is observed in most (area ratio of back-through part 51 to 80%).
1 point: The cast liquid can be seen through almost the entire surface.

(11) Separation amount of separation membrane (μm)
Supply liquid channel material made of mesh fabric, seawater desalination reverse osmosis membrane, pressure-resistant sheet, and permeate channel material (groove width 200 μm, groove depth 150 μm, groove density 40 / 2.54 cm, thickness A spiral type fluid separation element (element) having an effective membrane area of 40 m ² was produced using a polyester single tricot having a thickness of 200 μm.
Next, the manufactured fluid separation element was subjected to a durability test under conditions of a reverse osmosis pressure of 7 MPa, a seawater salt concentration of 3 wt%, and an operating temperature of 40 ° C., and the fluid separation element was disassembled after 1000 hours of operation. Then, the amount of the separation membrane dropped into the permeate channel material was measured. The amount of sagging is measured by taking 500-3000 times photographs with a scanning electron microscope (unit: μm) for any three cross sections of the separation membrane in one fluid separation element. Calculated by rounding to the first place. The direction in which the separation membrane support and the permeate flow channel material overlap is the width direction of the nonwoven fabric when the length direction of the nonwoven fabric of the separation membrane support (nonwoven fabric direction length) is perpendicular to the groove direction of the permeate flow channel material. The test was carried out for each of the cases where the width of the nonwoven fabric was orthogonal.

Example 1
Intrinsic viscosity IV0.65 dried to a moisture content of 50 ppm or less, melting point 260 ° C., polyethylene terephthalate resin containing 0.3 wt% titanium oxide, intrinsic viscosity IV0.66 dried to a moisture content of 50 ppm or less, isophthalic acid copolymerization rate A copolymer polyester resin having a melting point of 11 mol% and a melting point of 230 ° C. and containing 0.2 wt% of titanium oxide is melted at 295 ° C. and 280 ° C., respectively, and a polyethylene terephthalate resin is used as the core component and the copolymer polyester resin is used as the sheath component. After spinning from the pores at a base temperature of 300 ° C. and a weight ratio of core: sheath = 80: 20, spinning with an ejector at a spinning speed of 4300 m / min to form a concentric core-sheath filament (circular cross section), moving net conveyor It was collected as a fiber web on top. The collected fiber web is thermocompression bonded with a pair of upper and lower steel flat rolls at a flat roll surface temperature of 190 ° C. and a linear pressure of 60 kg / cm. The average fiber diameter of the constituent filaments is 11 μm (single fiber fineness: 1.3 dtex), basis weight A spunbonded nonwoven fabric having a thickness of 80 g / m ² and a thickness of 0.11 mm was produced to obtain a separation membrane support. The obtained separation membrane support had a packing density of 0.5, an air flow rate of 2.0 cc / cm ² / sec, a thickness change amount at a high load relative to a low load of 0.01 mm, and a surface average roughness of 4 μm. Met.

(Example 2)
Intrinsic viscosity IV0.65 dried to a moisture content of 50 ppm or less, melting point 260 ° C., polyethylene terephthalate resin containing 0.3 wt% titanium oxide, intrinsic viscosity IV0.66 dried to a moisture content of 50 ppm or less, isophthalic acid copolymerization rate A copolymer polyester resin having a melting point of 11 mol% and a melting point of 230 ° C. and containing 0.2 wt% of titanium oxide is melted at 295 ° C. and 280 ° C., respectively, and a polyethylene terephthalate resin is used as the core component and the copolymer polyester resin is used as the sheath component. After spinning from the pores at a base temperature of 300 ° C. and a weight ratio of core: sheath = 80: 20, spinning with an ejector at a spinning speed of 4500 m / min to form a concentric core-sheath filament (circular cross section), moving net conveyor It was collected as a fiber web on top. The collected fiber web was heat-set with a pair of upper and lower steel flat rolls at a temperature of 140 ° C. and a linear pressure of 50 kg / cm, the average fiber diameter of the constituent filaments was 10 μm (single fiber fineness 1.2 dtex), and the basis weight was 70 g / m. ^2. A spunbond nonwoven fabric having a thickness of 0.25 mm was produced. The obtained spunbonded nonwoven fabric was used with a pair of steel rolls each having a flat surface, the upper roll was heated to 170 ° C., and the lower roll was heated to 70 ° C., respectively, and the linear pressure was 170 kg / cm, Adhesion processing was performed at a processing speed of 10 m / min to produce a spunbond nonwoven fabric to obtain a separation membrane support. The obtained separation membrane support had a packing density of 0.6, an air flow rate of 1.2 cc / cm ² / sec, a thickness change amount of 0.01 mm at a high load relative to a low load, and a surface average roughness of 5 μm. Met.

(Example 3)
Intrinsic viscosity IV0.65 dried to a moisture content of 50 ppm or less, melting point 260 ° C., polyethylene terephthalate resin containing 0.3 wt% titanium oxide, intrinsic viscosity IV0.66 dried to a moisture content of 50 ppm or less, isophthalic acid copolymerization rate A copolymer polyester resin having a melting point of 11 mol% and a melting point of 230 ° C. and containing 0.2 wt% of titanium oxide is melted at 295 ° C. and 280 ° C., respectively, and a polyethylene terephthalate resin is used as the core component and the copolymer polyester resin is used as the sheath component. After spinning from the pores at a base temperature of 300 ° C. and a weight ratio of core: sheath = 80: 20, spinning with an ejector at a spinning speed of 4500 m / min to form a concentric core-sheath filament (circular cross section), moving net conveyor It was collected as a fiber web on top. The collected fiber web was heat-set with a pair of upper and lower flat rolls at a temperature of 140 ° C. and a linear pressure of 50 kg / cm, the average fiber diameter of the constituent filaments was 10 μm (single fiber fineness 1.2 dtex), the basis weight was 35 g / m ² , A spunbond nonwoven fabric having a thickness of 0.15 mm was produced. Two sheets of the obtained spunbonded nonwoven fabric are superposed, a pair of flat rolls, a steel roll on the upper side and a urethane resin roll on the lower side, are used, and only the upper steel roll is heated to 170 ° C. When the roll was stabilized at a surface temperature of 100 ° C., adhesion processing was performed at a linear pressure of 170 kg / cm and a processing speed of 20 m / min to produce a laminated spunbonded nonwoven fabric to obtain a separation membrane support. The obtained separation membrane support had a packing density of 0.5, an air flow rate of 2.2 cc / cm ² / sec, a thickness change amount at a high load relative to a low load of 0.01 mm, and a surface average roughness of 4 μm. Met.

Example 4
Polyethylene terephthalate resin having an intrinsic viscosity of 0.45, dried at a moisture content of 50 ppm or less, a melting point of 260 ° C. and containing 0.3 wt% titanium oxide, and 10 mol% of isophthalic acid as a copolymer component dried to a moisture content of 50 ppm or less Then, a polybutylene terephthalate resin having a melting point of 211 ° C. is melted at 295 ° C. and 260 ° C., respectively, and the polyethylene terephthalate resin is used as a core component, and the copolymerized polybutylene terephthalate resin is used as a sheath component. After spinning from the pores at a weight ratio of 80:20, spinning was performed by an ejector at a spinning speed of 4500 m / min to form a concentric core-sheath filament (circular cross section) and collected as a fiber web on a moving net conveyor . The collected fiber web was heat-set with a pair of upper and lower flat rolls at a flat roll surface temperature of 130 ° C. and a linear pressure of 50 kg / cm, the average filament diameter of the constituent filaments was 12 μm (single fiber fineness 1.5 dtex), and the basis weight was 30 g / A spunbonded nonwoven fabric of m ² and a thickness of 0.13 mm was produced. Two sheets of the obtained spunbonded nonwoven fabric are superposed, using a pair of flat rolls with a steel roll on the upper side and a urethane resin roll on the lower side, and only the upper steel roll is heated to a temperature of 160 ° C. When the roll was stabilized at a surface temperature of 90 ° C., adhesion processing was performed at a linear pressure of 180 kg / cm and a processing speed of 25 m / min to produce a laminated spunbonded nonwoven fabric to obtain a separation membrane support. The obtained separation membrane support has a packing density of 0.4, an air flow rate of 4.0 cc / cm ² / sec, a thickness change amount at a high load relative to a low load of 0.01 mm, and a surface average roughness of 5 μm. Met.

( Reference Example 1 )
A poly (L-lactic acid) resin having a weight average molecular weight of 150,000, a Q value (Mw / Mn) of 1.51 and a melting point of 168 ° C. dried at a moisture content of 50 ppm or less is melted at 230 ° C. After spinning from the pores at 235 ° C., the ejector was spun at a spinning speed of 4300 m / min to form a concentric core-sheath filament (circular cross section), which was collected as a fiber web on a moving net conveyor. The collected fiber web is thermocompression bonded with a pair of upper and lower steel flat rolls at a temperature of 150 ° C. and a linear pressure of 60 kg / cm, the average fiber diameter of the constituent filaments is 11 μm (single fiber fineness 1.1 dtex), and the basis weight is 60 g / m. ^2. A spunbond nonwoven fabric having a thickness of 0.09 mm was produced to obtain a separation membrane support. The obtained separation membrane support had a packing density of 0.5, an air flow rate of ^2.5 cc / cm ² / sec, a thickness change amount at a high load relative to a low load of 0.01 mm, and a surface average roughness of 4 μm. Met.

(Example 5 )
Intrinsic viscosity IV0.65 dried to a moisture content of 50 ppm or less, melting point 260 ° C., polyethylene terephthalate resin containing 0.3 wt% titanium oxide, intrinsic viscosity IV0.66 dried to a moisture content of 50 ppm or less, isophthalic acid copolymerization rate A copolymer polyester resin having a melting point of 11 mol% and a melting point of 230 ° C. and containing 0.2 wt% of titanium oxide is melted at 295 ° C. and 280 ° C., respectively, and a polyethylene terephthalate resin is used as the core component and the copolymer polyester resin is used as the sheath component. After spinning from the pores at a base temperature of 300 ° C. and a weight ratio of core: sheath = 70: 30, spinning with an ejector at a spinning speed of 4000 m / min to form a concentric core-sheath filament (circular cross section), moving net conveyor It was collected as a fiber web on top. The collected fiber web was heat-set with a pair of upper and lower steel flat rolls at a temperature of 140 ° C. and a linear pressure of 50 kg / cm, the average fiber diameter of the constituent filaments was 16 μm (single fiber fineness 2.8 dtex), and the basis weight was 100 g / m. ^2. A spunbonded nonwoven fabric having a thickness of 0.38 mm was produced. The obtained spunbonded nonwoven fabric was used with a pair of steel rolls each having a flat surface, the upper roll was heated to 170 ° C., and the lower roll was heated to 70 ° C., respectively, and the linear pressure was 170 kg / cm, Adhesion processing was performed at a processing speed of 10 m / min to produce a spunbond nonwoven fabric to obtain a separation membrane support. The obtained separation membrane support had a packing density of 0.4, an air flow rate of 11.0 cc / cm ² / sec, a thickness change amount at a high load with respect to a low load was 0.02 mm, and a surface average roughness was 7 μm. Met.

The properties of the obtained nonwoven fabric are as shown in Tables 1 and 2, but the separation membrane supports of Examples 1 to 5 all have a cast liquid penetration property of 4 or more during film formation, There were no peeling, non-uniform film formation, pinhole defects, etc., and the film forming property was good. The separation membrane supports of Examples 1 to 5 all have a packing density of 0.4 to 0.8, an air flow rate of 0.2 to 30.0 cc / cm ² / sec, and a high load relative to a low load. The amount of change in the thickness was 0.00 to 0.03 mm, and the mechanical strength was excellent. In each case, the amount of the separation membrane dropped was 50 μm or less, and the durability was excellent.

(Comparative Example 1)
Intrinsic viscosity IV0.65 dried to a moisture content of 50 ppm or less, melting point 260 ° C., polyethylene terephthalate resin containing 0.3 wt% titanium oxide, intrinsic viscosity IV0.66 dried to a moisture content of 50 ppm or less, isophthalic acid copolymerization rate A copolymer polyester resin having a melting point of 11 mol% and a melting point of 230 ° C. and containing 0.2 wt% of titanium oxide is melted at 295 ° C. and 280 ° C., respectively, and a polyethylene terephthalate resin is used as the core component and the copolymer polyester resin is used as the sheath component. After spinning from the pores at a base temperature of 300 ° C. and a weight ratio of core: sheath = 80: 20, spinning with an ejector at a spinning speed of 4300 m / min to form a concentric core-sheath filament (circular cross section), moving net conveyor It was collected as a fiber web on top. The collected fiber web is thermocompression bonded at a temperature of 170 ° C. and a linear pressure of 50 kg / cm with a steel thread pattern embossing roll and a steel flat roll with a crimping area ratio of 25%, engraving depth of 0.3 mm, and engraving pitch of 2.0 mm. Then, a spunbonded nonwoven fabric having an average fiber diameter of the constituent filaments of 13 μm (single fiber fineness of 1.8 dtex), a basis weight of 100 g / m ² , and a thickness of 0.27 mm was manufactured to obtain a separation membrane support. The obtained separation membrane support has a packing density of 0.3, an air flow rate of 20.8 cc / cm ² / sec, a thickness change amount at a high load relative to a low load of 0.05 mm, and a surface average roughness of 13 μm. Met.

(Comparative Example 2)
Polyethylene terephthalate resin having an intrinsic viscosity of 0.60 and a melting point of 260 ° C. dried to a moisture content of 50 ppm or less is melted at 295 ° C., spun from the pores at a die temperature of 300 ° C., and then undrawn yarn at a speed of 1600 m / min. Rolled up. Subsequently, the obtained undrawn yarn was drawn at a draw ratio of 3.0 times using a hot roll-hot roll type drawing machine, cut by imparting crimp, and having a fineness of 2.8 dtex and a fiber length of 6 mm. A terephthalate fiber was obtained. The obtained fiber was dispersed in a water tank, and then the fiber and water mixed solution was separated using a mesh drum while the drum was rotated to separate the fiber and water, and the wet nonwoven fabric was rolled up. This is squeezed using two rolls, then dried on the surface of a drum dryer having a surface temperature of 150 ° C., and further at a temperature of 180 ° C. and a linear pressure of 100 kg / cm with a pair of upper and lower steel flat rolls. Thermocompression bonding was carried out to produce a wet short fiber nonwoven fabric having an average fiber diameter of 16 μm (single fiber fineness of 2.8 dtex), a basis weight of 95 g / m ² , and a thickness of 0.18 mm to obtain a separation membrane support. The obtained separation membrane support had a packing density of 0.4, an air flow rate of 7.9 cc / cm ² / sec, a thickness change amount at a high load with respect to a low load was 0.04 mm, and a surface average roughness was 6 μm. Met.

(Comparative Example 3)
Intrinsic viscosity IV0.65 dried to a moisture content of 50 ppm or less, melting point 260 ° C., polyethylene terephthalate resin containing 0.3 wt% titanium oxide, intrinsic viscosity IV0.66 dried to a moisture content of 50 ppm or less, isophthalic acid copolymerization rate A copolymer polyester resin having a melting point of 11 mol% and a melting point of 230 ° C. and containing 0.2 wt% of titanium oxide is melted at 295 ° C. and 280 ° C., respectively, and a polyethylene terephthalate resin is used as the core component and the copolymer polyester resin is used as the sheath component. After spinning from the pores at a base temperature of 300 ° C. and a weight ratio of core: sheath = 60: 40, spinning with an ejector at a spinning speed of 3500 m / min to form a concentric core-sheath filament (circular cross section), moving net conveyor It was collected as a fiber web on top. The collected fiber web is thermocompression-bonded with a pair of upper and lower steel flat rolls at a flat roll surface temperature of 210 ° C. and a linear pressure of 70 kg / cm, and the average fiber diameter of the constituent filaments is 10 μm (single fiber fineness 1.1 dtex). A spunbond nonwoven fabric having a thickness of 110 g / m ² and a thickness of 0.09 mm was produced to obtain a separation membrane support. The obtained separation membrane support had a packing density of 0.9, an air flow rate of 0.0 cc / cm ² / sec, a thickness change amount at a high load relative to a low load of 0.00 mm, and a surface average roughness of 3 μm. Met.

(Comparative Example 4)
Intrinsic viscosity IV0.65 dried to a moisture content of 50 ppm or less, melting point 260 ° C., polyethylene terephthalate resin containing 0.3 wt% titanium oxide, intrinsic viscosity IV0.66 dried to a moisture content of 50 ppm or less, isophthalic acid copolymerization rate A copolymer polyester resin having a melting point of 11 mol% and a melting point of 230 ° C. and containing 0.2 wt% of titanium oxide is melted at 295 ° C. and 280 ° C., respectively, and a polyethylene terephthalate resin is used as the core component and the copolymer polyester resin is used as the sheath component. After spinning from the pores at a base temperature of 300 ° C. and a weight ratio of core: sheath = 80: 20, spinning with an ejector at a spinning speed of 4300 m / min to form a concentric core-sheath filament (circular cross section), moving net conveyor It was collected as a fiber web on top. The collected fiber web is thermocompression bonded with a pair of upper and lower steel flat rolls at a flat roll surface temperature of 190 ° C. and a linear pressure of 60 kg / cm, and the average fiber diameter of the constituent filaments is 13 μm (single fiber fineness 1.8 dtex). A spunbonded nonwoven fabric having a thickness of 40 g / m ² and a thickness of 0.05 mm was produced to obtain a separation membrane support. The obtained separation membrane support had a packing density of 0.6, an air flow rate of 32.8 cc / cm ² / sec, a thickness change amount at a high load relative to a low load of 0.01 mm, and a surface average roughness of 5 μm. Met.

  The characteristics of the obtained separation membrane support are as shown in Table 1, but the separation membrane supports of Comparative Examples 1, 2, and 4 show that the cast liquid that reaches the back side plane of the separation membrane support does not show through. As can be seen, the cast liquid penetration through the film was less than 4 points. On the other hand, in the separation membrane support of Comparative Example 3, when a polysulfone separation membrane was formed, membrane separation on the surface of the support was observed, and the film-forming property was inferior. In addition, the separation membrane support of Comparative Example 2 also had a membrane defect that caused the separation membrane support fibers to protrude from the separation membrane surface. Furthermore, the separation membrane supports of Comparative Examples 1 and 2 have large thickness changes of 0.05 and 0.04 mm at high loads relative to low loads, respectively, and are inferior in mechanical strength. The amount exceeded 50 μm, and the durability was inferior.

Claims (5)

It is composed of a composite filament in which a low melting polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high melting polymer is arranged around the high melting polymer, and the composite filament is heated by a pair of upper and lower flat rolls. It is a separation membrane support made only of a spunbond nonwoven fabric that is pressure-bonded, and has a packing density of 0.4 to 0.8, an air flow rate of 0.2 to 30.0 cc / cm ² / sec, and a low load ( The thickness change amount at high load (pressurizer diameter 16 mm, load 200 kPa) with respect to the pressurizer diameter 16 mm and load 2 kPa is 0.00 to 0.03 mm, and the surface average roughness is 2 to 9 μm. A separation membrane support. The separation membrane support according to claim 1, wherein the composite filament is made of a polyester polymer. The separation membrane support according to claim 1 or 2, wherein the composite filament has an average fiber diameter of 3 to 17 µm.   A separation membrane comprising a membrane having a separation function formed on the surface of the separation membrane support according to any one of claims 1 to 3.   A fluid separation element comprising the separation membrane according to claim 4.