JP2017170293A - Semi-permeable membrane support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semi-permeable membrane support having a little fuzz on a face equipped with a semi-permeable membrane and few defects due to the fuzz of main body fibers.SOLUTION: A semi-permeable membrane includes main fibers made of synthetic fibers and binder fibers. The semi-permeable membrane is characterize in that the fiber orientation of a face formed with a semitransparent film of said semi-permeable membrane support is 10 to 30°, and in that the average single fiber strength of said main fibers is 5.0 cN/dtex.SELECTED DRAWING: None

Description

  The present invention relates to a semipermeable membrane support.

  Semipermeable membranes are widely used in the fields of desalination of seawater, water purifiers, food concentration, wastewater treatment, ultrapure water production for medical use and semiconductor cleaning, such as blood filtration. The semipermeable membrane is made of a synthetic resin such as a cellulose resin, a polysulfone resin, a polyacrylonitrile resin, a fluorine resin, a polyester resin, a polyamide resin, or a polyimide resin. However, since the semipermeable membrane itself is inferior in mechanical strength, it is used as a filtration membrane in which a semipermeable membrane is provided on one side of a semipermeable membrane support made of a fiber base material such as a nonwoven fabric or a woven fabric. . Hereinafter, the surface on which the semipermeable membrane of the semipermeable membrane support is provided may be referred to as “application surface”. Further, the surface opposite to the coated surface may be referred to as “non-coated surface”.

  As a method for producing a filtration membrane, there is a method in which a synthetic resin such as the polysulfone-based resin described above is dissolved in an organic solvent to prepare a semipermeable membrane liquid, and then this semipermeable membrane liquid is applied onto a semipermeable membrane support. Widely used. And in order to perform filtration efficiently, a spiral type semipermeable membrane element is formed, and a semipermeable membrane module is further assembled (for example, refer to patent documents 1).

  In order to obtain a high filtration flux and filtration performance, the semipermeable membrane surface has few irregularities, no lateral bending or wrinkling occurs when the semipermeable membrane is formed, and the semipermeable membrane is uniform on the semipermeable membrane support. It is necessary to be provided with an appropriate thickness. In order for the semipermeable membrane to be provided with a uniform thickness, excellent smoothness is required on the coated surface of the semipermeable membrane support. And in order to obtain favorable filtration performance, it is necessary to be excellent also in the adhesiveness of a semipermeable membrane and a semipermeable membrane support body. Moreover, when assembling a semipermeable membrane module, since there is a step of bonding non-coated surfaces together using an adhesive, it is also required that the non-coated surfaces have excellent adhesion. Furthermore, it is required that the semipermeable membrane liquid does not penetrate to the non-coated surface. This is because if the back-through occurs, the thickness of the semipermeable membrane becomes non-uniform and the adhesion between the non-coated surfaces decreases.

  As a semipermeable membrane support, a non-woven fabric that includes a main fiber composed of a synthetic fiber and a binder fiber, is manufactured by a wet papermaking method, and has been subjected to a hot press process has been proposed. For example, a non-woven fabric with a multilayer structure based on a double structure consisting of a surface layer with a large surface roughness (thick fiber layer) using thick fibers and a back layer (thin fiber layer) with a dense structure using thin fibers. A semipermeable membrane support has been proposed (see, for example, Patent Document 2). Specifically, a semipermeable membrane support having a thick fiber layer as an application surface and a thin fiber layer as a non-application surface, and a thin fiber layer sandwiched between thick fiber layers, and both the application surface and the non-application surface are thick fibers A semipermeable membrane support in layers is described. However, since thick fibers are used on the application surface, the adhesion between the semipermeable membrane and the semipermeable membrane support is improved, but thick and rigid fluffs increase on the application surface. There was a problem that the fuzz broke through the semipermeable membrane and the semipermeable membrane did not have a uniform thickness. In addition, when the pressure during hot pressing is increased to suppress the occurrence of fuzz, the surface density of the semipermeable membrane support increases too much, and the adhesion between the semipermeable membrane and the semipermeable membrane support decreases. There was a case. Then, during the cutting process after the semipermeable membrane support is formed or during the semipermeable membrane liquid coating process, it is generated by friction between the coating surface and the conveying roll such as an expander roll or a metal roll disposed in each process. No consideration is given to fluffing. In addition, the fluffing is called “loose fiber” in which one of the fluffy fibers is fused to the support, and “loop fiber” in which both ends of the fluffy fiber are fixed by fusion and the middle part is lifted. There are two types. The loose fiber and loop fiber are liable to cause defects when a semipermeable membrane liquid is applied, and have a problem of deteriorating membrane performance. In particular, since the both ends of the fluffed fiber were fused, the loop fiber was not easily detached from the semipermeable membrane support and was likely to be defective.

JP 2008-238147 A Japanese Patent Publication No. 4-21526

  An object of the present invention is to provide a semipermeable membrane support having less fuzz on the surface on which the semipermeable membrane is provided, and less defects due to fluffing of main fibers when a semipermeable membrane liquid is applied.

  The above problems have been solved by the following means.

(1) In a semipermeable membrane support comprising a main fiber made of a synthetic fiber and a binder fiber, the fiber orientation degree of the surface on which the semipermeable membrane is provided is 10 to 30 °, and the average single fiber of the main fiber A semipermeable membrane support having a strength of 5.0 cN / dtex or less.

  The semipermeable membrane support of the present invention has a fiber orientation degree of 10 to 30 ° on the surface on which the semipermeable membrane is provided, and the average single fiber strength of the main fiber is 5.0 cN / dtex or less. Suppressing the occurrence of fluffing when the conveying roll in the cutting process or the semipermeable membrane liquid coating process after the formation of the permeable membrane support and the surface on which the semipermeable membrane of the semipermeable membrane support is provided contact It has become possible.

  The semipermeable membrane support of the present invention is a semipermeable membrane support comprising a main fiber composed of a synthetic fiber and a binder fiber, the fiber orientation degree of the surface on which the semipermeable membrane is provided is 10 to 30 °, and The average single fiber strength of the main fiber is 5.0 cN / dtex or less.

  In the present invention, the fiber orientation of the coated surface of the semipermeable membrane support is a longitudinal orientation. As compared with the case where the fiber orientation is a lateral orientation, the occurrence of fuzz is reduced, and coating defects derived from the fuzz can be suppressed. The reason is not clear, but when the fiber orientation of the coated surface is vertical, such as an expander roll or a metal roll, which is arranged on the coated surface and each step during the cutting process or the semipermeable membrane liquid coating process. It is presumed that the resistance between the transport roll and the semipermeable membrane support is reduced, and fuzz is suppressed. Further, it is assumed that the average single fiber strength of the main fiber is as low as 5.0 cN / dtex or less, so that the entanglement between the fibers becomes large, and fuzz is suppressed even when resistance is received from a transport roll or the like. ing.

  Next, a method for adjusting the fiber orientation degree of the fibers in the semipermeable membrane support will be described. As the semipermeable membrane support of the present invention, a nonwoven fabric such as a spunbond nonwoven fabric, a melt blown nonwoven fabric, a dry short fiber nonwoven fabric and a wet papermaking nonwoven fabric, or a composite nonwoven fabric obtained by laminating a plurality of nonwoven fabrics selected from these nonwoven fabrics can be used. In addition, the nonwoven fabric is hot-pressed with a hot roll. The degree of fiber orientation can be adjusted by controlling the manufacturing conditions of the nonwoven fabric and the processing conditions when the nonwoven fabric is hot-pressed with a hot roll. As will be described later, the semipermeable membrane support of the present invention is preferably a wet papermaking nonwoven fabric, but when the nonwoven fabric is produced by a wet papermaking method, the selection of the paper machine to be used and the adjustment of operating conditions, for example, papermaking Adjust the fiber orientation by adjusting the jet / wire ratio (raw material jet speed / paper machine wire speed) in the wet part of the machine, optimizing the dehydration process in the wire part, and adjusting the tension balance in the dryer part. can do. Moreover, as a processing condition at the time of carrying out a hot-pressure process, the fiber orientation degree can be adjusted by adjusting the kind of roll to be used, arrangement | positioning of a roll, hot roll temperature, and tension balance.

  In the present invention, the fiber orientation degree of the coated surface of the semipermeable membrane support is 10 to 30 °, more preferably 10 to 25 °, and still more preferably 10 to 20 °. When the fiber orientation degree exceeds 30 °, the resistance force between the main fiber on the coated surface and the transport roll is increased during the cutting process or the semipermeable membrane liquid coating process, and the main fibers between the binder fibers are interposed between the main fibers. Adhesion is easily cut, and as a result, fluff such as loose fiber or loop fiber is generated on the coated surface. Moreover, when the fiber orientation degree is less than 10 °, the fiber entanglement between the main fibers decreases, the adhesiveness between the fibers decreases, and fluffing occurs.

  In the present invention, the average single fiber strength of the main fibers contained in the semipermeable membrane support is 5.0 cN / dtex or less, preferably 4.7 cN / dtex or less, more preferably 4.5 cN / dtex or less. is there. When the average single fiber strength exceeds 5.0 cN / dtex, the fiber has high rigidity, so that the main fiber on the coated surface received resistance from the transport roll during the cutting process or the semipermeable membrane liquid coating process. At this time, the adhesion between the fibers is easily cut, and as a result, the generation of fluff such as loose fibers and loop fibers is caused. The lower limit value of the average single fiber strength is preferably 4.2 cN / dtex.

  In the present invention, the main fiber and the binder fiber are made of synthetic fibers. The main fiber is a fiber that forms the skeleton of the semipermeable membrane support, and the main fiber is difficult to soften or melt even at a temperature at which the binder fiber is softened or melted. Is a fiber that is not damaged. Examples of the main fiber include polyolefin-based, polyamide-based, polyacrylic-based, vinylon-based, vinylidene-based, polyvinyl chloride-based, polyester-based, benzoate-based, polyclar-based, and phenol-based fibers. High polyester fibers are more preferably used.

  In the semipermeable membrane supporting material of the present invention, it is preferable to contain two or more kinds of fibers having different fiber diameters as main fibers. The fiber network formed by intertwining two or more main fibers having different fiber diameters causes complex and fine irregularities on the coated surface, so that the adhesion between the semipermeable membrane and the semipermeable membrane support can be improved. it can. Further, the smoothness of the coated surface can be improved by this fiber network, and a uniform semipermeable membrane can be obtained. When the main fiber contains one kind of fiber having a fiber diameter and the binder fiber contains two or more kinds of fibers having different fiber diameters, the binder fiber is softened or melted by a drying process or a hot pressing process. The smoothness of the semipermeable membrane support may become too high, and may not contribute to the fiber network for improving the adhesion between the semipermeable membrane and the semipermeable membrane support.

  The average fiber diameter of the main fibers is preferably 7.0 to 20.0 μm, and more preferably 8.0 to 16.0 μm. Moreover, when the fiber diameter of at least 1 type of main fiber is 13.0 micrometers or less, the smoothness of an application surface can be improved more and it becomes easy to obtain the semipermeable membrane with the uniform film thickness. When the average fiber diameter of the main fibers is less than 7.0 μm, the peel strength between the coated surface and the semipermeable membrane may decrease, or the adhesion between the non-coated surfaces may deteriorate. When the average fiber diameter of the main fibers exceeds 20.0 μm, the smoothness of the surface of the semipermeable membrane support is lost, and it becomes difficult to obtain a semipermeable membrane with a uniform thickness, as well as Frazier (FG) air permeability. Becomes too high, and there is a case where the back-through occurs when the semipermeable membrane liquid is applied.

  In the present invention, the average fiber diameter of the main fiber is obtained by the following formula. N is a positive integer.

Average fiber diameter = (fiber diameter of main fiber 1 (μm) × mass% of main fiber 1 + fiber diameter of main fiber 2 (μm) × mass% of main fiber 2 + fiber diameter of main fiber 3 (μm) × main body Mass% of fiber 3 +... + Fiber diameter of main fiber N (μm) × mass% of main fiber N) / (% by mass of main fiber 1 +% by mass of main fiber 2 +% by mass of main fiber 3+ ... + mass% of the main fiber N)

  The single fiber strength is a value measured according to the tensile strength of JIS L1015.

  In the present invention, the average single fiber strength of the main fiber is obtained by the following formula. N is a positive integer.

Average single fiber strength = (single fiber strength of main fiber 1 (cN / dtex) × mass% of main fiber 1 + single fiber strength of main fiber 2 (cN / dtex) × mass% of main fiber 2 + main fiber 3 Single fiber strength (cN / dtex) × mass% of main fiber 3 +... + Single fiber strength of main fiber N (cN / dtex) × mass% of main fiber N) / (mass% of main fiber 1 + main body) (Mass% of fiber 2 + mass% of main fiber 3 + ... + mass% of main fiber N)

  Although the fiber length of a main fiber is not specifically limited, Preferably it is 1-12 mm, More preferably, it is 3-10 mm, More preferably, it is 4-6 mm. When the fiber length is less than 1 mm, it is difficult to form a three-dimensional network of fibers in the paper making process, and the peelability from the paper making wire may be deteriorated. On the other hand, when the fiber length exceeds 12 mm, entanglement or twisting of the fibers may adversely affect the uniformity of the semipermeable membrane support and the smoothness of the semipermeable membrane. The cross-sectional shape of the main fiber is preferably circular, but fibers having an irregular cross-section such as T-type, Y-type, and triangle can also be contained within a range that does not hinder other characteristics in order to prevent back-through and smooth the coated surface. .

  Although the semipermeable membrane support of the present invention contains binder fibers, the process of raising the temperature to near the temperature at which the binder fibers are softened or melted is incorporated into the production process of the semipermeable membrane support, thereby producing the binder fibers. Improves the mechanical strength of the semipermeable membrane support. For example, a semipermeable membrane support can be produced by a wet papermaking method, and the binder fiber can be softened or melted in a subsequent drying step.

  Examples of the binder fiber include core-sheath fibers (core-shell type), parallel fibers (side-by-side type), composite fibers such as radially divided fibers, unstretched fibers, and the like. Since the composite fiber hardly forms a film, the mechanical strength can be improved while maintaining the space of the semipermeable membrane support. More specifically, a combination of polypropylene (core) and polyethylene (sheath), a combination of polypropylene (core) and ethylene vinyl alcohol (sheath), a combination of high melting point polyester (core) and low melting point polyester (sheath), polyester, etc. Of undrawn fiber. In addition, a single fiber (fully fused type) composed only of a low melting point resin such as polyethylene or polypropylene, or a hot water-soluble binder such as polyvinyl alcohol easily forms a film in the drying process of the semipermeable membrane support. However, it can be used as long as the properties are not impaired. In the present invention, a combination of a high-melting point polyester (core) and a low-melting point polyester (sheath) and unstretched polyester fibers can be preferably used.

  The fiber diameter of the binder fiber is preferably different from that of the main fiber, but is not particularly limited. Because the fiber diameter is different from the main fiber, the binder fiber plays a role of forming a uniform three-dimensional network together with the main fiber and the thin fiber, in addition to the role of improving the mechanical strength of the semipermeable membrane support, In the Yankee dryer and hot air drying, the smoothness of the coated surface can be improved in the step of raising the temperature to near the temperature at which the binder fiber is softened or melted.

  The fiber length of the binder fiber is not particularly limited, but when the fiber length exceeds 20 mm, the formation tends to deteriorate. The cross-sectional shape of the binder fiber can also include a fiber having a circular shape and a modified cross-section such as a T shape, a Y shape, or a triangle.

  The content ratio of the main fiber and the binder fiber is preferably 60:40 to 80:20, more preferably 60:40 to 75:25, and 65:35 to 75:25 on a mass basis. Is more preferable, and 65:35 to 70:30 is particularly preferable. When the content ratio of the main fiber is less than 60% by mass with respect to the total amount of the main synthetic fiber and the binder synthetic fiber, the permeation flux may decrease. If the content ratio of the main fibers exceeds 80% by mass, the mechanical strength of the semipermeable membrane supporting member may be reduced and may be easily broken.

  The semipermeable membrane support of the present invention can contain semi-synthetic fiber acetate, triacetate, promix, regenerated fiber rayon, cupra, lyocell fiber and the like as long as the performance is not impaired.

  The semipermeable membrane support of the present invention is preferably a semipermeable membrane support produced by subjecting a nonwoven fabric produced by a wet papermaking method (wet papermaking nonwoven fabric) to hot pressing with a hot roll.

  In the wet papermaking method, first, the main fibers and binder fibers are uniformly dispersed in water, and then passed through processes such as screen (removal of foreign matters, lumps, etc.), and the final fiber concentration is 0.01 to 0.50 mass%. The slurry prepared in (1) is made up with a paper machine to obtain a wet paper. In the process, chemicals such as a dispersant, an antifoaming agent, a hydrophilic agent, an antistatic agent, a polymer viscosity agent, a release agent, an antibacterial agent, and a bactericide may be added.

  As the papermaking method, for example, a long net, a circular net, an inclined wire type, or the like can be used. You may use the paper machine which has one kind of paper making system chosen from these paper making methods, and may use the combination paper machine in which two or more kinds of same or different kinds of paper making methods are installed online. . In addition, when the semipermeable membrane support has a multilayer structure of two or more layers, it is possible to laminate a wet paper made by each paper making method, and after forming one layer, It can be produced by a casting method in which a slurry in which fibers are dispersed is cast. In the casting method, the previously formed layer may be in a wet paper state or in a dry state. Further, two or more dry layers can be thermally fused to form a multilayer structure.

  A wet nonwoven fabric is obtained by drying wet paper produced by a paper machine with a Yankee dryer, air dryer, cylinder dryer, suction drum dryer, infrared dryer, or the like. When the wet paper is dried, it is brought into close contact with a hot roll such as a Yankee dryer and dried by heat and pressure to improve the smoothness of the contacted surface. Hot-pressure drying means that the wet paper is pressed against the heat roll with a touch roll or the like and dried. The surface temperature of the hot roll is preferably 100 to 180 ° C, more preferably 100 to 160 ° C, and still more preferably 110 to 160 ° C. When the surface temperature of the hot roll is less than 100 ° C., the water content of the wet paper produced by the paper machine does not sufficiently evaporate, and the thickness uniformity of the semipermeable membrane support may be deteriorated. When the temperature exceeds 180 ° C., the wet paper produced by the paper machine may stick to the heat roll and the formation of the semipermeable membrane support may deteriorate. The pressure is preferably 5 to 100 kN / m, more preferably 10 to 80 kN / m. When the pressure is less than 5 kN / m, the moisture of the wet paper manufactured by the paper machine may not be sufficiently removed, and the thickness uniformity of the semipermeable membrane support may be deteriorated. When the pressure exceeds 100 kN / m, the paper machine The wet paper manufactured in (1) may stick to the heat roll, and the formation of the semipermeable membrane support may deteriorate.

  In the hot press processing, the wet nonwoven fabric is passed between the hot rolls while niping the hot rolls of the hot press processing apparatus. Examples of the combination of the heat rolls include two metal rolls, a metal roll and a resin roll, a metal roll and a cotton roll, and one or both of the heat rolls are heated. Furthermore, if necessary, the front and back of the nonwoven fabric may be reversed so that the number of passes through the nip is two or more.

  The surface temperature of the heat roll used for the hot pressing process is lower than the melting point of the main fiber measured by differential thermal analysis, and is preferably −70 to −20 ° C. with respect to the melting point of the binder fiber, and −60 to −30. More preferably, it is ° C. If the surface temperature of the hot roll temperature is lower than the melting point of the binder fiber by more than 70 ° C., fuzzing may occur easily, and it becomes difficult to obtain a semipermeable membrane having a uniform thickness. On the other hand, if the surface temperature of the hot roll is increased beyond a temperature 20 ° C. lower than the melting point, the melt of the fibers may adhere to the hot roll, and the semipermeable membrane support may become non-uniform, and the uniform thickness It becomes difficult to obtain a semipermeable membrane. The melting point of the fiber was determined by measuring with a DSC (Differential Scanning Calorimeter) under conditions of a temperature range of 25 to 300 ° C. and a heating rate of 10 ° C./min.

  The nip pressure of the hot roll used for the hot pressing process is preferably 50 to 250 kN / m, more preferably 70 to 180 kN / m. The processing speed is preferably 5 to 100 m / min, and more preferably 10 to 50 m / min.

  The semipermeable membrane support of the present invention may have a multilayer structure in which the fiber blends of the respective layers are the same, or may have a multilayer structure in which layers having different fiber blends are laminated. In this case, since the fiber concentration of the slurry can be lowered by reducing the basis weight of each layer, the formation of the semipermeable membrane support is improved, and as a result, the smoothness and uniformity of the coated surface are improved. Moreover, even when the formation of each layer is non-uniform | heterogenous, it can compensate by laminating | stacking. Further, the paper making speed can be increased, and the operability is improved.

Although the basic weight of a semipermeable membrane support body is not specifically limited, 20-150 g / m < ² > is preferable, More preferably, it is 50-100 g / m < ² >. If it is less than 20 g / m ² , sufficient tensile strength may not be obtained. Moreover, when it exceeds 150 g / m < ² >, a liquid flow resistance may become high, thickness may increase, and a predetermined amount of semipermeable membrane may not be accommodated in a unit or a module.

The density of the semi-permeable membrane support is preferably 0.5 to 1.2 g / cm ^3, more preferably 0.6~1.0g / cm ^3. When the density of the semipermeable membrane support is less than 0.5 g / cm ³ , the thickness increases, and the area of the semipermeable membrane that can be incorporated into the unit is reduced. As a result, the life of the semipermeable membrane is shortened. May end up. On the other hand, when it exceeds 1.2 g / cm ³ , the liquid permeability may be lowered, and the life of the semipermeable membrane may be shortened.

  The thickness of the semipermeable membrane support is preferably 60 to 150 μm, more preferably 70 to 130 μm, and still more preferably 80 to 120 μm. When the thickness of the semipermeable membrane support exceeds 150 μm, the area of the semipermeable membrane that can be incorporated into the unit is reduced, and as a result, the life of the semipermeable membrane may be shortened. On the other hand, if the thickness is less than 60 μm, sufficient tensile strength may not be obtained or the liquid permeability may be reduced, and the life of the semipermeable membrane may be shortened.

Air permeability of the semipermeable membrane support is preferably from 0.5~5.0cm ³ / ^cm 2 · ^sec, more preferably from ^{1.0~4.5cm 3 / cm 2 · sec,} 1. More preferably, it is 5 to 4.0 cm ³ / cm ² · sec. If it is smaller than 0.5 cm ³ / cm ² · sec, the adhesion between the semipermeable membrane and the semipermeable membrane support may be inferior. If it is greater than 5.0 cm ³ / cm ² · sec, there may be a case where strikethrough is likely to occur when a semipermeable membrane solution is applied. In addition, the smoothness of the coated surface may be reduced.

  The invention is explained in more detail by means of examples. Hereinafter, unless otherwise specified, the parts and ratios described in the examples are based on mass.

Example 1
The main fiber is 60% by mass of a stretched polyester fiber (main fiber A) having a fiber diameter of 7.9 μm, a single fiber strength of 4.6 cN / dtex, and a fiber length of 5 mm, and the binder fiber has a fiber diameter of 10.5 μm and a fiber length of 5 mm. The unstretched polyester binder fiber having a melting point of 260 ° C. was 40% by mass. These fibers were mixed and dispersed in water and stored separately in two stock tanks having a stirring device. Using a combination machine of inclined wire paper machine and circular net paper machine, forming wet paper with 40g / m ² each layer with inclined wire paper machine on the coated surface side and circular paper machine on the non-coated surface side Then, it was hot-pressure dried with a Yankee dryer having a surface temperature of 130 ° C. so that the coated surface side was in contact with the Yankee dryer, and a wet nonwoven fabric having a basis weight of 80 g / m ² was obtained. At this time, the ratio of the jetting speed of the raw material and the wire speed of the paper machine (jet / wire ratio) was adjusted to adjust the fiber orientation degree of the coated surface.

  The obtained wet nonwoven fabric was subjected to the metal at the first roll nip using a hot press processing device in which the first and second roll nips composed of a metal roll (heating) and a resin roll (non-heating) were continuously installed. The surface temperature of the roll was 220 ° C., the surface temperature of the metal roll at the time of the second roll nip was 225 ° C., and processing was performed under the conditions of a nip pressure of 100 kN / m and a processing speed of 20 m / min to obtain a semipermeable membrane support. In addition, the surface which touches a metal roll in the 1st roll nip was made into the application surface.

(Examples 2 to 4)
A semipermeable membrane support was obtained in the same manner as in Example 1 except that the jet / wire ratio was adjusted and the fiber orientation degree of the coated surface was changed.

(Example 5)
As main fibers, 50% by mass of drawn polyester fiber (main fiber B) having a fiber diameter of 9.4 μm, a single fiber strength of 5.1 cN / dtex, and a fiber length of 6 mm, 10% by mass of main fiber A, and fibers as binder fibers The unstretched polyester binder fiber having a diameter of 10.5 μm, a fiber length of 5 mm, and a melting point of 260 ° C. was 40% by mass. These fibers were mixed and dispersed in water and stored separately in two stock tanks having a stirring device. Using a combination machine of inclined wire paper machine and circular net paper machine, forming wet paper with 40g / m ² each layer with inclined wire paper machine on the coated surface side and circular paper machine on the non-coated surface side Then, it was hot-pressure dried with a Yankee dryer having a surface temperature of 130 ° C. so that the coated surface side was in contact with the Yankee dryer, and a wet nonwoven fabric having a basis weight of 80 g / m ² was obtained. At this time, the jet / wire ratio was adjusted to adjust the degree of fiber orientation on the coated surface.

  The obtained wet nonwoven fabric was subjected to the metal at the first roll nip using a hot press processing device in which the first and second roll nips composed of a metal roll (heating) and a resin roll (non-heating) were continuously installed. The surface temperature of the roll was 220 ° C., the surface temperature of the metal roll at the time of the second roll nip was 225 ° C., and processing was performed under the conditions of a nip pressure of 100 kN / m and a processing speed of 20 m / min to obtain a semipermeable membrane support. In addition, the surface which touches a metal roll in the 1st roll nip was made into the application surface.

(Example 6)
As the main fiber, the main fiber A is 30% by mass, the fiber diameter is 12.5 μm, the single fiber strength is 4.4 cN / dtex, the stretched polyester fiber (main fiber C) having a fiber length of 5 mm is 20% by mass, and the fiber diameter is 17.5 μm. Unstretched polyester fiber having a fiber diameter of 10.5 μm, a fiber length of 5 mm, and a melting point of 260 ° C. as a binder fiber, 10% by mass of a stretched polyester fiber (main fiber E) having a single fiber strength of 4.1 cN / dtex and a fiber length of 5 mm The binder fiber was 40% by mass. After forming a single-layer wet paper using an inclined wire paper machine, it is hot-pressure dried with a Yankee dryer with a surface temperature of 130 ° C. so that the coated surface is in contact with the Yankee dryer, and a wet nonwoven fabric with a basis weight of 80 g / m ² is obtained. Obtained. At this time, the jet / wire ratio was adjusted to adjust the degree of fiber orientation on the coated surface.

  The obtained wet nonwoven fabric was subjected to the metal at the first roll nip using a hot press processing device in which the first and second roll nips composed of a metal roll (heating) and a resin roll (non-heating) were continuously installed. The surface temperature of the roll was set to 220 ° C., the surface temperature of the metal roll at the time of the second roll nip was set to 225 ° C., and processed under the conditions of a nip pressure of 100 kN / m and a processing speed of 20 m / min. Obtained. In addition, the surface which touches a metal roll in the 1st roll nip was made into the application surface.

(Comparative Example 1)
As the main fiber, the main fiber B is 25% by mass, the fiber diameter is 13.0 μm, the single fiber strength is 5.9 cN / dtex, the stretched polyester fiber (main fiber D) having a fiber length of 6 mm is 45% by mass, and the binder fiber is a fiber. The unstretched polyester binder fiber having a diameter of 10.5 μm, a fiber length of 5 mm, and a melting point of 260 ° C. was 30% by mass. These fibers were mixed and dispersed in water and stored separately in two stock tanks having a stirring device. Using a combination machine of inclined wire paper machine and circular net paper machine, forming wet paper with 40g / m ² each layer with inclined wire paper machine on the coated surface side and circular paper machine on the non-coated surface side Then, it was hot-pressure dried with a Yankee dryer having a surface temperature of 130 ° C. so that the coated surface side was in contact with the Yankee dryer, and a wet nonwoven fabric having a basis weight of 80 g / m ² was obtained. At this time, the jet / wire ratio was adjusted to adjust the degree of fiber orientation on the coated surface.

  The obtained wet nonwoven fabric was subjected to the metal at the first roll nip using a hot press processing device in which the first and second roll nips composed of a metal roll (heating) and a resin roll (non-heating) were continuously installed. The surface temperature of the roll was 220 ° C., the surface temperature of the metal roll at the time of the second roll nip was 225 ° C., and processing was performed under the conditions of a nip pressure of 100 kN / m and a processing speed of 20 m / min to obtain a semipermeable membrane support. In addition, the surface which touches a metal roll in the 1st roll nip was made into the application surface.

(Comparative Examples 2-3)
A semipermeable membrane support was obtained in the same manner as in Example 1 except that the jet / wire ratio was adjusted and the fiber orientation degree of the coated surface was changed.

(Comparative Example 4)
A semipermeable membrane support was obtained in the same manner as in Comparative Example 1 except that the jet / wire ratio was adjusted and the fiber orientation of the coated surface was changed.

(Comparative Example 5)
A semipermeable membrane support was obtained in the same manner as in Example 6 except that the jet / wire ratio was adjusted and the fiber orientation degree of the coated surface was changed.

  The obtained wet nonwoven fabric is a metal roll at the time of the first roll nip using a hot press processing apparatus in which first and second roll nips comprising a metal roll (heating) and a resin roll (non-heating) are continuously installed. Was processed at a nip pressure of 100 kN / m and a processing speed of 20 m / min, and a semipermeable membrane support of Comparative Example 5 was obtained. It was. In addition, the surface which touches a 1st metal roll was made into the application surface.

Measurement 1 (Fiber orientation)
Ten small sample samples were randomly collected from the semipermeable membrane supports obtained in Examples and Comparative Examples, photographed 100 to 1000 times with a scanning electron microscope, and 10 samples from each sample totaled 100. For the fibers, measure the angle when the longitudinal direction (longitudinal direction) of the semipermeable membrane support is 0 °, and the width direction (lateral direction) of the nonwoven fabric is 90 °, and calculate the average value thereof, The degree of fiber orientation was determined by rounding off the first decimal place.

Measurement 2 (basis weight)
The basis weight was measured according to JIS P8124.

Measurement 3 (thickness)
The thickness was measured according to JIS P8118.

Measurement 4 (Air permeability)
The air permeability was measured according to JIS L1096.

Evaluation (fuzz evaluation)
From the semipermeable membrane support obtained in Examples and Comparative Examples, a sample having a width direction of 40 mm × longitudinal direction of 60 mm was taken and attached to the center of a support paper having a width of 100 mm × longitudinal direction of 700 mm, and one end of the support paper was attached The sample affixed to the mirror finished φ140 mm metal roll is brought into contact with the roll, the other end is fixed so that the support paper does not sag, and the metal roll is rotated at 65 mm / sec for 1 minute. Thereafter, the sample is removed, the surface is observed at 40 to 100 times with a stereomicroscope, and the number of loose fibers and loop fibers is counted. The measurement is performed at n = 4, and the average value is shown. Evaluation was made according to the following degree.

The number of “○” loose fibers and loop fibers is less than 5. There is no problem in practical use.
“△” The number of loose fibers and loop fibers is 5 or more and less than 10. Practically usable level.
The number of “x” loose fibers and loop fibers is 10 or more. Practical, unusable level.

  In the semi-permeable membrane supports of Examples 1 to 6, the fiber orientation degree of the coated surface is 10 to 30 °, and the average single fiber strength of the main fibers is 5.0 cN / dtex or less. Thus, it has become possible to provide a semipermeable membrane support having less fuzz on the surface of the coated surface.

  The semipermeable membrane support of Comparative Example 1 had a fiber orientation degree of 10 to 30 °, but the average single fiber strength exceeded 5.0 cN / dtex, so that fuzzing was practically impossible. The semipermeable membrane supports of Comparative Examples 2 to 3 have an average single fiber strength of 5.0 cN / dtex or less, but the degree of fiber orientation is out of the range of 10 to 30 °, and fuzzing is practically impossible. It was. The semipermeable membrane support of Comparative Example 4 had a fiber orientation degree exceeding 30 ° and an average single fiber strength exceeding 5.0 cN / dtex. The semipermeable membrane support of Comparative Example 5 had an average single fiber strength of 5.0 cN / dtex or less, but the fiber orientation was less than 10 °, so that the fluff was practically impossible.

  The semipermeable membrane support of the present invention can be used in fields such as seawater desalination, water purifiers, food concentration, wastewater treatment, medical filtration typified by blood filtration, and ultrapure water production for semiconductor cleaning. it can.

Claims (1)

  A semipermeable membrane support comprising a main fiber composed of a synthetic fiber and a binder fiber, the fiber orientation degree of the surface of the semipermeable membrane support on which the semipermeable membrane is provided is 10 to 30 °, and the main fiber A semipermeable membrane supporting material having an average single fiber strength of 5.0 cN / dtex or less.