JP2008238147A - Semipermeable membrane support - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent semipermeable membrane support capable of generating no coating liquid strike-through and capable of obtaining a non-defect semipermeable membrane with a necessary minimum thickness when the semipermeable membrane is formed on the support which is comprised of a synthetic fiber non-woven fabric having an excellent uniformity. <P>SOLUTION: A semipermeable membrane is a non-woven fabric constituted of synthetic fibers and a mass distribution coefficient Sn expressed by a formula (A) of the non-woven fabric is less than 0.1 as under: formula (A) Sn=D/M, Sn: mass distribution coefficient [-], D: mass standard deviation per unit area [g/m<SP>2</SP>], M: mass per unit area [g/m<SP>2</SP>]. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, the non-uniformity of the mass in the XY direction of the sheet is extremely small. As a result, when the semipermeable membrane is formed on the support, there is no penetration of the coating liquid, and the minimum necessary thickness It is related with the outstanding semipermeable membrane support body which can obtain a semipermeable membrane without defect by.

  In recent years, the use of semi-permeable membranes continues to increase, such as the removal of impurities in beverages / industrial water, desalination of seawater, removal of germs in foods, wastewater treatment, and biochemistry. The research of is advancing steadily in Japan and abroad.

  As the material of the semipermeable membrane, various polymers such as regenerated cellulose, cellulose derivatives, polyvinyl alcohol, polysulfone, and polyamide are selected according to the use. However, the membrane itself is weak in strength, and by itself, ultrafiltration or Since it cannot withstand the high pressure of 1 to 10 MPa or more when used for reverse osmosis, it is necessary to form a film on a support such as a nonwoven fabric having high strength and high liquid permeability.

  In order to obtain the required liquid permeability, tensile strength, wet strength, and durability on the support, synthetic fibers such as polyester and polyolefin are formed into a sheet form by wet or dry method, and heated and pressurized. Synthetic fiber nonwoven fabrics in which fibers are melt-bonded together are generally used, but the problem here is that the non-uniformity in the XY direction of these nonwoven fabrics is not uniform in the semipermeable membrane provided thereon As a result, sufficient performance cannot be obtained, or the film thickness necessary for obtaining sufficient performance increases, resulting in a decrease in filtration efficiency. Therefore, the nonwoven fabric used for the support is required to be as uniform as possible and free from pinhole defects.

  The manufacturing method is conventionally known about the nonwoven fabric as a support body of a semipermeable membrane. For example, a method has been proposed in which polyester fibers having different thicknesses are used to create a structure having a density in the Z direction, and the semipermeable membrane coating solution is prevented from being pulled through while maintaining a low resistance to liquid passage. (Patent Document 1)

  In addition, by using polyester fiber with specific heat shrinkage stress and birefringence, the dimensional stability when tensile stress is applied is improved, the surface is smooth, there is no show-through, and the film adhesion is excellent Methods have been proposed for providing nonwoven fabrics. (Patent Document 2)

  In addition, a uniform semipermeable membrane layer is formed by controlling the orientation of the fibers, as the support is curved in the width direction during semipermeable membrane coating, causing nonuniformity of the semipermeable membrane layer. Proposals have been made. (Patent Document 3)

  In addition, in the wet papermaking method for special paper, a method for adjusting the formation using a sticky agent is conventionally known. For example, although it is not a semipermeable membrane support, glass fiber is dispersed with a betaine-type amphoteric surfactant as a dispersant when a glass fiber sheet is produced, and an anionic surfactant and a polyacrylamide-based adhesive are sequentially added. Thus, a method has been proposed in which a slurry in which glass fibers are well dispersed is obtained to obtain a sheet having good formation. (Patent Documents 4 and 5)

  However, in the method of Patent Document 1, a multi-layer structure of the support is indispensable in order to prevent the semipermeable membrane coating liquid from falling through, which complicates the process, lowers the production speed and the raw material yield, and increases the cost. Inevitable.

  According to the method of Patent Document 2, it may be effective to reduce the non-uniformity of the non-woven fabric sheet due to the partial stretch non-uniformity of the fiber due to tensile stress or heat, but the non-uniformity of the sheet Most of the nature is non-uniformity resulting from the density of the fiber distribution as the sheet is formed from the fiber and cannot be the fundamental solution to the problem.

  Further, as described in Patent Document 3, even if the curvature of the support is reduced to the utmost limit, the non-uniformity of the semipermeable membrane layer derived from the non-uniformity of the support itself is not solved.

  In addition, in the cases described in Patent Documents 4 and 5, the role of a polymer thickener (also referred to as a polymer thickener) is considered to be an effect of preventing fiber re-aggregation by adhering to the surface of dispersed fibers. Therefore, the addition amount of the polymer viscosity agent is relatively small as 0.2 to 1.5% based on the glass fiber, and the formation evaluation of the obtained sheet is mainly based on the presence or absence of the binding fiber by visual observation. The uniformity of the mass distribution of the sheet is not a problem. Therefore, this technique is completely different from the semipermeable membrane support of the present invention described below.

JP 60-238103 A Japanese Patent No. 3153487 JP 2002-95937 A JP-A-5-123513 JP-A-8-209585

  As described above, synthetic fiber nonwoven fabric having excellent uniformity as a support for a semipermeable membrane and a method for producing the same are still in the process of development, and when the semipermeable membrane is formed on the support, the coating liquid is breached. In addition, it is an object of the present invention to provide an excellent semipermeable membrane support capable of obtaining a semipermeable membrane free from defects with a minimum necessary thickness.

  As a result of intensive studies, the present inventors have determined that the uniformity of the mass distribution in the X and Y directions of the synthetic fibers constituting the semipermeable membrane support is the maximum that determines the performance of the semipermeable membrane provided on the support. It is predicted that this is a factor, and the technical problem based on such prediction is solved by controlling the viscosity of the fiber dispersion slurry at the time of papermaking and the viscosity at a low fiber share by using a very high molecular weight adhesive. The present invention has been found by discovering that it is possible to achieve the expected effect.

Specifically, the semipermeable membrane support according to the present invention is a non-woven fabric composed of main fibers made of synthetic fibers and binder fibers, and has a mass distribution coefficient of 0.1 or less. By satisfying this requirement, the back-through of the coating liquid does not occur in the subsequent semipermeable membrane application step, and a thinner film than that of the conventional film can be formed uniformly, thereby improving the performance of the semipermeable membrane. The mass distribution coefficient referred to in the present invention is determined by the following formula (A):
Sn = D / M (A)
Sn: Mass distribution coefficient [-]
D: Standard deviation of mass per unit area [g / m ² ]
M: mass per unit area [g / m ² ].
D in a formula (A) is a numerical value measured using beta ray total (Beta Formation Tester BFT-1: AMBERTEC company make). Formula (A) is intended to remove the influence of basis weight from the standard deviation of mass. As the reason why the mass distribution coefficient Sn by the β-ray ground total correlates with the performance of the semipermeable membrane support, the measurement of the sheet mass distribution by the β-ray ground total is performed at 1 mmφ × any number of times. The inventor presumes that this is because the mass distribution scale substantially coincides with the scale of mass distribution that affects the penetration of the semipermeable membrane layer on the semipermeable membrane support.

  The semipermeable membrane support having the above mass distribution coefficient is a step of wet-making a fiber slurry in which the synthetic fiber is dispersed in water to form a nonwoven fabric, and the fiber content concentration of the fiber slurry at the time of papermaking is 0.01 to 0.1 mass%, the fiber slurry contains a polymer adhesive, the polymer adhesive is a water-soluble polymer having a molecular weight of 5 million or more, and the content of the polymer adhesive is set to the fiber It is obtained by making paper as 3 to 15% by mass on the basis of the mass of fiber in the slurry.

  The synthetic fiber according to the present invention comprises a polyester fiber main fiber and a binder fiber having a thickness of 0.3 to 5.0 dtex and a length of 1 to 8 mm, and the dry mass ratio thereof is the polyester main fiber: polyester binder fiber = It is desirable that it is 90: 10-50: 50.

  The semipermeable membrane support according to the present invention is a process for heating and pressurizing a nonwoven fabric web with a calendar device to melt and bond the fibers to enhance the sheet strength, as shown in FIG. It is desirable that the non-woven fabric is heated and pressed by a nip after running the web along the web.

  According to the present invention, it is possible to efficiently provide an excellent synthetic fiber nonwoven fabric as a semipermeable membrane support without achieving a high uniformity in the XY directions and without causing a factor to reduce production speed and production yield. became.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited to the following embodiments.

  The semipermeable membrane support according to the present embodiment is a nonwoven fabric made of synthetic fibers. The raw material of the synthetic fiber is not particularly limited as long as the mass distribution coefficient that is a requirement of the present invention is achieved, and various synthetic resins are used depending on the application. Examples thereof include fibers spun from a synthetic resin such as polyethylene, polypropylene, polyacrylate, polyester, polyurethane, polyvinyl chloride, polyvinylidene chloride, polyfluorinated ethylene, polyaramid, polyimide, polyacrylonitrile, and nylon. In addition, fibers made from regenerated cellulose such as rayon, cellulose derivatives such as cellulose acetate and nitrocellulose, and natural products such as polylactic acid, polybutyric acid and polysuccinic acid, which have been actively studied for biochemical applications in recent years And included in the category of synthetic fibers in the present invention. Among the above synthetic fibers, polyester fibers are preferably used because of their heat resistance, chemical resistance, low cost, abundant types of fiber diameters and properties, and the like.

  Among the synthetic fibers according to the present embodiment, a synthetic fiber having a normal melting point that is not intended for fusion bonding at a low temperature is referred to as a main fiber. The shape of the main fiber is not limited as long as the mass distribution coefficient, which is a requirement of the present invention, is obtained, but if a fiber with a small fiber diameter is used, the hole diameter of the completed sheet becomes smaller and a fiber with a larger fiber diameter is used. This increases the strength of the sheet. If short fibers are used, dispersibility in water is improved, and if long fibers are used, the strength of the sheet is increased. Accordingly, it is necessary to select an appropriate shape in consideration of the strength required for the support, the hole diameter, the sheet uniformity, etc. In this embodiment, the thickness is 0.3 to 5.0 dtex and the length is 1 to 8 mm. Those in the range are preferably used. Moreover, the shape of the cross section of the fiber can be appropriately selected as necessary, and is not limited in the present embodiment.

  In the synthetic fiber according to the present embodiment, it is desirable that a binder fiber is mixed in order to obtain sufficient sheet strength during the sheet forming process and the winding process. Binder fiber generally refers to synthetic fiber having a melting point lower than that of the main fiber (about 80 to 160 ° C), and the surface is melt-bonded by heating in the drying process after papermaking, and tension that enables operation Has the effect of imparting strength to the sheet. However, since the tensile strength of the fiber itself is inferior to that of the main fiber, it is necessary to set the blending ratio so that the ease of operation and the strength of the finished product can be balanced. In this embodiment, the main fiber: binder fiber = 90: 10. A range of ˜50: 50 is preferred. The binder fiber has a low melting point of all the constituent resins, a double structure inside and outside, a so-called core-sheath structure, and a type in which only the surface is fused. It can be used. The thickness, length, cross-sectional shape, and the like can be selected according to the purpose as in the case of the main fiber.

Although the density of the nonwoven fabric which concerns on this embodiment is not specifically limited, The range of 0.6-1.0 g / cm < ³ > is preferable in consideration of the liquid permeability fixed to a support body. If it is 1.0 g / cm ³ or more, the pore diameter of the support becomes too small to obtain sufficient water permeability. If it is less than 0.6 g / cm ³ , the pore diameter becomes conversely too large and the coating liquid tends to break through. Further, the basis weight of the support is preferably 20 g / m ² or more, and if it is less than 20 g / m ² , the thickness tends to be too thin to easily cause through-through.

  In this embodiment, as long as the mass distribution coefficient which is a requirement of the present invention can be obtained, the fiber may be formed into a sheet by any method, but after dispersing the fiber in water, the fiber is laminated on the papermaking wire, A so-called wet papermaking method in which a sheet is formed by dehydration from below the wire is preferably used. The type of paper machine used at this time is not limited as long as the mass distribution coefficient which is a requirement of the present invention can be obtained. For example, a long net type paper machine, a round net type paper machine, an inclined wire type paper machine or the like can be used. A multi-layer paper machine combining one or more of them may be used. It is the uniformity of fiber dispersion in water that has a great influence on the mass distribution coefficient of the finished nonwoven fabric, and more specifically, the uniformity of the fiber at the moment of dewatering on the papermaking wire. For this reason, it is desirable to adjust the fiber concentration of the fiber slurry during papermaking to a range of 0.01 to 0.1% by mass. When the concentration of the fiber slurry is lower than 0.01%, the paper making speed is significantly reduced. When the concentration of the fiber slurry is higher than 0.1%, it is difficult to obtain a desired mass distribution uniformity. The fiber concentration is particularly preferably 0.01 to 0.08%, in particular 0.01 to 0.05%.

  In addition, for nonwoven fabrics that require a high degree of uniformity such as a semipermeable membrane support, it is difficult to obtain sufficient uniformity only by reducing the papermaking concentration. In the present invention, this is made possible by using a polymer viscosity agent having a molecular weight of 5 million or more.

  In general, fibers dispersed in a slurry are uniformly dispersed when dispersed at a relatively high speed by a disperser. However, in a low-speed flow state during papermaking, the fibers aggregate together and the resulting sheet is not. It becomes uniform. Therefore, by adding a certain type of polymer viscosity agent that shows high viscosity at low shear fiber concentration and controlling the viscosity at low flow rate, it prevents the fibers from moving in the coagulation direction and forms a uniform sheet. can do. According to the study of the present inventor, the dispersibility of fibers at a low shear fiber concentration can be improved by using a water-soluble polymer having a molecular weight of 5 million or more. In this case, it should be noted that the polymer viscous agent may be structurally broken by a device that applies a high share to a fluid such as a disperser or a pump, and the viscosity may be lowered.

  As the polymer viscous agent in the present embodiment, known synthetic or natural hydrophilic polymers can be used, but as a precaution when using the polymer adhesive agent, if these polymers are added excessively, As the wet paper web moisture increases, or due to the viscosity of the polymer itself, the releasability of the papermaking wire and the nonwoven web deteriorates, causing paper breakage and a significant reduction in papermaking efficiency. Moreover, the air permeability (liquid permeability) required as a semipermeable membrane support is impaired by the adhesive filling the voids of the nonwoven fabric. Therefore, it is desirable to obtain desired fiber dispersibility and mass distribution uniformity with a small addition amount. As a result of the study by the present inventors, it is desirable to contain a water-soluble polymer viscosity agent having a molecular weight of 5 million or more in a range of 3 to 15% by mass based on the mass of the fiber in the fiber slurry. When the molecular weight is 5 million or less, a desired mass distribution coefficient cannot be obtained. The molecular weight of the polymer viscosity agent is preferably 6 million or more, particularly preferably 7 million or more. Further, when the content is 3% by mass or less, it is difficult to obtain a desired mass distribution coefficient, and when the content is 15% by mass or more, papermaking properties such as wire peelability and air permeability are deteriorated.

  As the kind of the polymer viscous agent, it is possible to use it regardless of whether it is synthetic or natural. Examples of natural polymers include cellulose polymers such as methyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose; protein polymers such as casein, gelatin, and glue; natural polysaccharides such as pectin; starch, trooaoi, and the like. Examples thereof include polyvinyl alcohol (PVA), polyacrylamide polymer (PAM), polyethylene oxide polymer (PEO), and polyacrylic polymer (PAA). Among these, PAM, PEO, and PAA are preferably used because they can easily handle high molecular weight ones. In the present invention, these polymers may be a simple substance, a copolymer or a mixture, or two or more kinds may be used in combination. Moreover, as long as the performance of a polymer viscous agent is not impaired, those addition positions in a process are not ask | required. In addition, other additives such as pH adjusters, chelating agents, dispersants, antifoaming agents, water repellents, wetting agents, preservatives, electrification are necessary as necessary from the synthetic fiber dispersion process to the papermaking process. An inhibitor or the like may be added.

  The synthetic fiber sheet containing the binder fiber after passing through the sheet forming step and the drying step can be said to be a non-woven fabric in that state as well, but generally the strength as a semipermeable membrane support is insufficient as it is. Therefore, in order to obtain sufficient strength as a semipermeable membrane support, heat treatment is performed at a temperature near the melting point of the main fiber to melt and bond the main fiber to increase the strength. In this treatment, a general method is to pass a metal roll nip calender that can be treated at a temperature of 200 ° C. or higher, but a resin roll having high heat resistance can also be used. The temperature condition, pressure condition, and sheet tension at this time affect the performance of the completed support, but any condition can be adopted as long as the mass distribution uniformity, which is a requirement of the present invention, is not impaired. Generally, a range of 160 ° C. to 240 ° C. is preferable, but a lower temperature or a higher temperature may be desirable depending on the type of synthetic fiber used. The linear pressure is preferably in the range of 50 to 200 kg / cm, but is not limited thereto. Further, in order to achieve uniform performance throughout the web, it is desirable to process with a temperature profile and linear pressure profile that are as uniform as possible. In addition, it is possible to perform the heat and pressure treatment in multiple stages, and the conditions and apparatuses in each stage may be different.

  Moreover, according to examination of this inventor, the mass distribution uniformity of a support body changes with the extent of the shrinkage | contraction in the XY direction in a heating-pressing process. As shown in FIG. 1, after the nonwoven fabric web is run along the roll 2 (heated roll) from the roll 1 of the calender device, the heat and pressure treatment is performed in the nip formed by the roll 2 and the roll 3, thereby reducing the mass. Distribution uniformity is improved. Here, the roll 1 is a roll that is not heated, and the roll 3 may not be heated or may be heated similarly to the roll 2. The roll 2 (heating roll) is preferably a metal roll, and the other unheated rolls can be made of metal, but a resin roll, a cotton roll, or an aramid roll is more preferable. The reason for the improvement in uniformity is that the present inventor can suppress uneven shrinkage due to rapid temperature rise in the nip by bringing the web temperature into contact with a heating roll for a certain period of time before being pressed. is doing. At this time, the nip formed by the roll 1 and the roll 2 may or may not be pressurized. Further, the number of rolls and the number of nips passing therethrough are not limited as long as the web is run along the heating roll and then pressed.

  It is a requirement of the present invention that the completed semipermeable membrane support has a mass distribution coefficient of 0.1 or less. By satisfying this requirement, defects due to back-through of the coating liquid and deterioration of operability do not occur in the subsequent semipermeable membrane application step, and a thinner film than the conventional one can be uniformly formed. Improved performance. The mass distribution coefficient is preferably 0.080 or less, particularly preferably 0.069 or less.

  The method for applying the semipermeable membrane coating solution to the semipermeable membrane support according to this embodiment is not particularly limited. As an example, a semipermeable membrane coating solution supplied from a slit is applied in layers on a support web that runs along a backing roll. At this time, if the mass distribution of the semipermeable membrane support is not uniform, the coating liquid may pass from the thin part of the support to the back side, resulting in a defect in the semipermeable membrane and possibly causing a backing roll stain. In some cases, an excessive film thickness is required to obtain a uniform semipermeable membrane layer.

  Next, the support web holding the semipermeable membrane layer is introduced into the layer filled with the coagulating liquid and solidified. For example, in the case of producing a polysulfone semipermeable membrane, a DMF (dimethylformamide) solution of polysulfone resin is used as a coating solution, and water is used as a coagulation solution. The semipermeable membrane thus obtained can be used as it is as an ultrafiltration membrane, but when used as a reverse osmosis membrane, a layer called an active layer is further provided on the surface thereof. This active layer can be obtained, for example, by forming cellulose acetate, aromatic polyamide, crosslinked polyamic acid, polyurea or the like as an ultrathin film on the supporting semipermeable membrane by interfacial polymerization.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to these Examples. In the examples, “%” represents “dry mass%” unless otherwise specified, and “part” represents “dry mass part”.

Example 1
<Preparation of fiber raw material slurry>
24 kg of commercially available polyester-based fiber (trade name: EP133, manufactured by Kuraray Co., Ltd.) with a thickness of 1.45 dtex and a cut length of 5 mm, and a commercially available polyester binder fiber (product with a thickness of 2.2 dtex and a cut length of 5 mm) (Name: EP201, manufactured by Kuraray Co., Ltd.) 6 kg was introduced into 2970 kg of water and dispersed for 5 minutes with a cowless mixer to obtain a fiber raw material slurry 1 having a fiber concentration of 1%.
<Preparation of polymer viscous agent 1>
To 200 kg of water, 90 g of polyethylene oxide / polyacrylamide (partially hydrolyzed) copolymerization type polymer thickener (trade name: Pamol P-130, manufactured by Meisei Chemical Industry Co., Ltd.) having a molecular weight of 8 million is charged and propeller mixer is used for 2 hours. By stirring, the polymer viscous agent 1 having a concentration of 0.045% was obtained.
<Preparation of fiber slurry>
After adding the polymer viscous agent 1 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-1a having a fiber concentration of 0.03%. .
<Production of sheet>
After the fiber slurry 1-1a is put into a head box of a short net type paper machine and the fiber slurry 1-1a is made, it is dried with a cylinder dryer having a surface temperature of 120 ° C. until the sheet moisture becomes 3% or less, and wound on a roll. The support base paper 1-1a was obtained.
<Heat and pressure treatment>
The support base paper 1-1a was subjected to a cotton roll (non-heated; roll 1) -metal roll (heated; heated in the paper run shown in FIG. 1 under conditions of a surface temperature of 170 ° C., a linear pressure of 100 kg / cm, and a speed of 5 m / min. Roll 2) -metal roll (heating; roll 3) was heated and pressurized in a nip calender to obtain a semipermeable membrane support 1-1a having a basis weight of 75 g / m ² and a thickness of 100 μm.

(Example 2)
<Preparation of fiber slurry>
After adding the polymer adhesive 1 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole was diluted with water to obtain a fiber slurry 1-1b having a fiber concentration of 0.01%. .
<Production of sheet>
The fiber slurry 1-1b was paper-made according to Example 1 to obtain a support base paper 1-1b.
<Heat and pressure treatment>
The support base paper 1-1b was subjected to a heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-1b.

(Example 3)
<Preparation of fiber slurry>
After adding the polymer viscous agent 1 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-1c having a fiber concentration of 0.1%. .
<Production of sheet>
The fiber slurry 1-1c was made according to Example 1 to obtain a support base paper 1-1c.
<Heat and pressure treatment>
The support base paper 1-1c was heat-pressed according to Example 1 to obtain a semipermeable membrane support 1-1c.

Example 4
<Preparation of fiber slurry>
After adding the polymer viscous agent 1 to the fiber raw material slurry 1 so as to be 15% to the fiber, the whole was diluted with water to obtain a fiber slurry 1-1d having a fiber concentration of 0.03%. .
<Production of sheet>
The fiber slurry 1-1d was made according to Example 1 to obtain a support base paper 1-1d.
<Heat and pressure treatment>
The support base paper 1-1d was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-1d.

(Example 5)
<Preparation of polymer viscous agent 2>
Into 200 kg of water, 90 g of polyacrylamide (partially hydrolyzed) polymer thickener (trade name: Pamall, manufactured by Meisei Chemical Co., Ltd.) with a molecular weight of 10 million was added and stirred for 2 hours with a propeller mixer to a concentration of 0.045% The high molecular viscosity agent 2 was obtained.
<Preparation of fiber slurry>
After adding the polymer viscous agent 2 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole was diluted with water to obtain a fiber slurry 1-2a having a fiber concentration of 0.03%. .
<Production of sheet>
After the fiber slurry 1-2a is put into the head box of a short net type paper machine and the fiber slurry 1-1a is made, it is dried with a cylinder dryer having a surface temperature of 120 ° C. until the sheet moisture becomes 3% or less and wound on a roll. The support base paper 1-2a was obtained.
<Heat and pressure treatment>
The support base paper 1-2a was heat-pressed with a metal nip calender in the paper run shown in FIG. 1 under the conditions of a surface temperature of 170 ° C., a linear pressure of 100 kg / cm, and a speed of 5 m / min. A semipermeable membrane support 1-2a with m ² and a thickness of 100 μm was obtained.

(Example 6)
<Preparation of fiber slurry>
After adding the polymer viscous agent 2 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-2b having a fiber concentration of 0.01%. .
<Production of sheet>
The fiber slurry 1-2b was made according to Example 1 to obtain a support base paper 1-2b.
<Heat and pressure treatment>
The support base paper 1-2b was heated and pressurized according to Example 1 to obtain a semipermeable membrane support 1-2b.

(Example 7)
<Preparation of fiber slurry>
After adding the polymer viscous agent 2 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole is diluted with water to obtain a fiber slurry 1-2c having a fiber concentration of 0.1% by mass. It was.
<Production of sheet>
The fiber slurry 1-2c was made according to Example 1 to obtain a support base paper 1-2c.
<Heat and pressure treatment>
The support base paper 1-2c was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-2c.

(Example 8)
<Preparation of fiber slurry>
After adding the polymer viscous agent 2 to the fiber raw material slurry 1 so as to be 15% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-2d having a fiber concentration of 0.03%. .
<Production of sheet>
The fiber slurry 1-2d was made according to Example 1 to obtain a support base paper 1-2d.
<Heat and pressure treatment>
The support base paper 1-2d was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-2d.

Example 9
<Preparation of fiber raw material slurry>
24 kg of commercially available polyester-based fiber (trade name: EP043, manufactured by Kuraray Co., Ltd.) with a thickness of 0.44 dtex and a cut length of 5 mm, and a commercially available polyester binder fiber (product with a thickness of 2.2 dtex and a cut length of 5 mm) (Name: EP201, manufactured by Kuraray Co., Ltd.) 6 kg was introduced into 2970 kg of water and dispersed for 5 minutes with a cowless mixer to obtain a fiber raw material slurry 2 having a fiber concentration of 1%.
<Preparation of fiber slurry>
After adding the polymer viscous agent 1 to the fiber raw material slurry 2 so as to be 4% to the fiber, the whole was diluted with water to obtain a fiber slurry 2-1a having a fiber concentration of 0.03%. .
<Production of sheet>
The fiber slurry 2-1a was paper-made according to Example 1 to obtain a support base paper 2-1a.
<Heat and pressure treatment>
The support base paper 2-1a was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 2-1a.

(Example 10)
<Preparation of fiber raw material slurry>
24 kg of commercially available polyester fiber (product name: EP303, manufactured by Kuraray Co., Ltd.) with a thickness of 3.3 dtex and a cut length of 5 mm, and a commercially available polyester binder fiber (product with a thickness of 2.2 dtex and a cut length of 5 mm) (Name: EP201, manufactured by Kuraray Co., Ltd.) 6 kg was introduced into 2970 kg of water and dispersed for 5 minutes with a cowless mixer to obtain a fiber raw material slurry 3 having a fiber concentration of 1%.
<Preparation of fiber slurry>
After adding the polymer viscous agent 1 to the fiber raw material slurry 3 so as to be 4% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 3-1a having a fiber concentration of 0.03%. .
<Production of sheet>
The fiber slurry 3-1a was made according to Example 1 to obtain a support base paper 3-1a.
<Heat and pressure treatment>
The support base paper 3-1a was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 3-1a.

(Example 11)
<Heat and pressure treatment>
The surface temperature of the support base paper 1-1a is 170 ° C. and linear pressure in a paper run (metal roll (heating; roll 2) −metal roll (heating; roll 3)) that passes directly through the nip without being along the heating roll. Heating and pressing were performed under the conditions of 100 kg / cm and a speed of 5 m / min to obtain a semipermeable membrane support 1-1ax.

(Comparative Example 1)
<Preparation of fiber slurry>
After adding the polymer viscous agent 1 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-1e having a fiber concentration of 0.20%. .
<Production of sheet>
The fiber slurry 1-1e was made according to Example 1 to obtain a support base paper 1-1e.
<Heat and pressure treatment>
The support base paper 1-1e was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-1e.

(Comparative Example 2)
<Preparation of fiber slurry>
After adding the polymer viscous agent 1 to the fiber raw material slurry 1 so as to be 20% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-1f having a fiber concentration of 0.03%. .
<Production of sheet>
The fiber slurry 1-1f was made according to Example 1 to obtain a support base paper 1-1f.
<Heat and pressure treatment>
The support base paper 1-1f was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-1f.

(Comparative Example 3)
<Preparation of fiber slurry>
After adding the polymer viscous agent 1 to the fiber raw material slurry 1 so as to be 2% to the fiber, the whole was diluted by adding water to obtain 1-1 g of a fiber slurry having a fiber concentration of 0.03%. .
<Production of sheet>
The fiber slurry 1-1g was paper-made according to Example 1 to obtain a support base paper 1-1g.
<Heat and pressure treatment>
The support base paper 1-1g was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-1g.

(Comparative Example 4)
<Preparation of polymer viscosity agent 3>
Into 200 kg of water, 90 g of polyethylene oxide polymer viscous agent (trade name: Alcox SP, manufactured by Meisei Chemical Industry Co., Ltd.) with a molecular weight of 4 million is added and stirred with a propeller mixer for 2 hours. Molecular sticking agent 3 was obtained.
<Preparation of fiber slurry>
After adding the polymer viscous agent 3 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-3a having a fiber concentration of 0.03%. .
<Production of sheet>
The fiber slurry 1-3a was made according to Example 1 to obtain a support base paper 1-3a.
<Heat and pressure treatment>
The support base paper 1-3a was heat-pressed according to Example 1 to obtain a semipermeable membrane support 1-3a.

(Comparative Example 5)
<Preparation of fiber slurry>
After adding the polymer viscous agent 3 to the fiber raw material slurry 1 so as to be 4% to the fiber, water was added to dilute the whole to obtain a fiber slurry 1-3b having a fiber concentration of 0.01%. .
<Production of sheet>
The fiber slurry 1-3b was made according to Example 1 to obtain a support base paper 1-3b.
<Heat and pressure treatment>
The support base paper 1-3b was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-3b.

(Comparative Example 6)
<Preparation of fiber slurry>
After adding the polymer viscous agent 3 to the fiber raw material slurry 1 so as to be 4% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-3c having a fiber concentration of 0.10%. .
<Production of sheet>
The fiber slurry 1-3c was made according to Example 1 to obtain a support base paper 1-3c.
<Heat and pressure treatment>
The support base paper 1-3c was heat-pressed according to Example 1 to obtain a semipermeable membrane support 1-3c.

(Comparative Example 7)
<Preparation of fiber slurry>
After adding the polymer viscous agent 3 to the fiber raw material slurry 1 so as to be 15% to the fiber, the whole was diluted by adding water to obtain a fiber slurry 1-3d having a fiber concentration of 0.03%. .
<Production of sheet>
The fiber slurry 1-3d was made according to Example 1 to obtain a support base paper 1-3d.
<Heat and pressure treatment>
The support base paper 1-3d was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1-3d.

(Comparative Example 8)
<Preparation of fiber slurry>
The fiber raw material slurry 1 was diluted with water to obtain a fiber slurry 1x having a fiber concentration of 0.03%. No polymer viscosity was added.
<Production of sheet>
The fiber slurry 1x was made according to Example 1 to obtain a support base paper 1x.
<Heat and pressure treatment>
The support base paper 1x was subjected to heat and pressure treatment according to Example 1 to obtain a semipermeable membrane support 1x.

The following table shows data obtained by measuring the viscosity of the polymer adhesives 1 to 3 used in the examples. It measured at 60 rpm and 20 degreeC using B type viscometer (made by Toki Sangyo Co., Ltd.) and BL adapter (same).

Table 2 shows a list of configurations of the semipermeable membrane supports of Examples and Comparative Examples.

The evaluation results are shown in Table 3 for the semipermeable membrane supports obtained in the above Examples and Comparative Examples.

(Evaluation methods)
<Wire peelability>
The fiber slurry before paper making is collected to a fiber content of 4.4 g, introduced into a 25 cm × 25 cm square hand-making machine, made with 100 mesh plastic wire, and suction dehydrated. It was peeled off further and the wet paper was peeled off from the wire (peeling resistance, fibers were removed from the wire) and visually evaluated. Evaluation was performed as follows.
A: Peels almost without resistance, and fibers are not removed.
○: There is light resistance but fiber is not removed. (Practical level)
Δ: The resistance is large, and there is a slight fiber residue in the outline. (Practical lower limit level),
X: The resistance is large and hardly peeled off, and partially remains on the wire. (Not suitable for practical use.)

<Mass distribution uniformity Sn>
The obtained semipermeable membrane support was conditioned for 24 hours in an environment of 23 ° C. and 50% RH, and then the mass distribution standard deviation was measured using β-line total (Beta Formation Tester BFT-1: manufactured by AMBERTEC). And mass distribution uniformity Sn was calculated | required based on Formula (A).

<Fragile air permeability>
The Frazier air permeability was measured by a Swiss Textest Corporation air permeability tester FX3300 based on the air permeability test method A (Fragile method) described in JIS L1096.

<Back-through>
The obtained semipermeable membrane support was cut to 20 cm × 30 cm, and a 20% solution of polysulfone resin in DMF (dimethylformamide) was applied onto the semipermeable membrane support using a Mayer bar # 12. The degree of penetration of the coating liquid was visually evaluated from the back side. Evaluation was performed as follows.
◎ ... There is no strikethrough. (Practical level)
○: There is no show-through, but penetration of the coating solution is observed in the thin part of the formation. (Practical level)
Δ: If a number of coatings are applied, there may be a case where the film breaks through. (Practical lower limit level)
×… There is a strikethrough. (Not suitable for practical use)

  Each of the semipermeable membrane supports of Examples 1 to 10 had a mass distribution coefficient Sn of 0.1 or less, and was satisfactory without see-through of the resin coating solution. Moreover, the wire peelability and fragile air permeability satisfied the practical level or the practical lower limit level. In Example 11, although the paper was made in the same manner as in Example 1, the mass distribution coefficient deteriorated due to the difference in the conditions of the heat and pressure treatment.

  On the other hand, Comparative Examples 1 and 3 to 9 had a mass distribution coefficient exceeding 0.1, and show-through occurred. In Comparative Example 2, the polymer adhesive was increased to 20% for the fiber, so the wire peelability did not reach a practical level. In Comparative Example 7, the addition amount of the polymer viscosity agent having a low molecular weight was increased, but the improvement effect of the mass distribution coefficient was low, and the back-through occurred, and the peelability deteriorated at the same time, and it was possible to balance the two. There wasn't. In Comparative Example 8, the peelability was the best because no polymer adhesive was used, but the show-through was bad.

These show the schematic of the calendar apparatus used at the heating-pressing process of the semipermeable membrane support body of this invention.

Explanation of symbols

1 ... Roll 1 (non-heated)
2 ... Roll 2 (heating)
3 ... Roll 3 (heated or non-heated)

Claims (4)

A semipermeable membrane support, which is a nonwoven fabric composed of synthetic fibers, and has a mass distribution coefficient Sn represented by the following formula (A) of the nonwoven fabric of 0.1 or less:
Sn = D / M (A)
Sn: Mass distribution coefficient [-]
D: Standard deviation of mass per unit area [g / m ² ]
M: mass per unit area [g / m ² ].   In the step of wet-paper-making a fiber slurry in which the synthetic fiber is dispersed in water to form a nonwoven fabric, the nonwoven fabric has a fiber content concentration of 0.01 to 0.1% by mass and a molecular weight of 5 million during papermaking. 2. The semipermeable membrane supporting material according to claim 1, wherein the above water-soluble polymer adhesive is made into a paper by containing 3 to 15% by mass based on the mass of the fiber in the fiber slurry. .   The synthetic fiber comprises a polyester fiber main fiber and a binder fiber having a thickness of 0.3 to 5.0 dtex and a length of 1 to 8 mm, and the dry mass ratio is the polyester main fiber: polyester binder fiber = 90: 10. The semipermeable membrane support according to claim 1 or 2, wherein the ratio is -50: 50.   The non-woven fabric is heated by a pressure nip after running the web along a heating roll of the calendar device in a process of increasing the sheet strength by heat-pressing the non-woven web with a calendar device to melt and bond the fibers. The semipermeable membrane support according to any one of claims 1 to 3, which is a pressed nonwoven fabric.

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