JP3153487B2 - Semipermeable membrane support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semipermeable membrane support, a method for producing the same, and a semipermeable membrane having the semipermeable membrane support. More specifically, the present invention is a semi-permeable membrane support having excellent dimensional stability, surface smoothness, excellent adhesion to a membrane, high air permeability in which many fine pores are present, and a method for producing the same, And a semipermeable membrane having the above-mentioned semipermeable membrane support, and the semipermeable membrane support of the present invention and the semipermeable membrane having the same are widely used in microfiltration such as ultrafiltration and reverse osmosis. It can be used effectively for applications.

[0002]

2. Description of the Related Art Seawater desalination, wastewater treatment, food concentration,
BACKGROUND ART Semipermeable membranes are widely used in many fields, including separation of microorganisms such as bacteria, yeasts, and viruses, production of ultrapure water for medical use such as blood filtration, and semiconductor cleaning.
The semipermeable membrane is generally formed of a synthetic polymer.Since the membrane alone has poor mechanical strength, a fibrous base material such as a nonwoven fabric or a woven fabric is used as a support, and a membrane-forming solution containing the synthetic polymer thereon. Is manufactured by casting.

[0003] Among the semipermeable membranes, the semipermeable membranes used for ultra-fine filtration such as ultrafiltration and reverse osmosis are 100%.
In some cases, the support is used under a high pressure close to the atmospheric pressure. In this case, the support for reinforcing the membrane is required to have high strength that does not break even under a high pressure and dimensional stability without elongation. Conventionally, in order to cope with such a demand, a method of increasing the basis weight (basis weight) of the support is generally adopted, but there are problems such as an increase in cost and a decrease in filtration efficiency.

[0004] In order to improve the filtration speed by the semipermeable membrane, the pore size of the membrane and the support may be increased. However, the pore size and thickness of the membrane are inevitably required according to the application and use mode of the semipermeable membrane. In many cases, only the pore size of the support is variable. However, when the pore size of the support is increased, strikethrough occurs when casting a film-forming solution containing a polymer on the support, and a film is simultaneously formed on the front and back surfaces of the support in the next solidification step, There is a disadvantage that a film having a defect such as a pinhole is formed. On the other hand, when the pore size of the support is reduced, the filtration rate of the semipermeable membrane is reduced, and the adhesion between the membrane and the support is not sufficient because the membrane-forming solution does not sufficiently penetrate into the support during the production of the semipermeable membrane. Insufficient, insufficient durability against pressurization at the time of filtration and negative pressure at the time of washing, and the like, peeling of the film from the support, breakage of the film, and the like are likely to occur. Furthermore, since the semi-permeable membrane itself is generally very thin film, when the support surface is not uniform, even the non-uniformity unevenness is formed as it appeared film on the film surface, the liquid to be filtered recess thereof Concentration, the effective filtration area is reduced, and contaminants accumulate in the recesses.

[0005] Therefore, several proposals have hitherto been made for the purpose of solving the above-mentioned problems in the semipermeable membrane. For example, by winding the semipermeable membrane support using a guide roll or the like having a projection on the surface, a concave recess is formed on the film forming surface of the support or a small hole is formed through the support, There is known a semipermeable membrane support in which the adhesion between the membrane and the support is improved by the effect of anchoring the membrane component to the concave recess or through-hole (Japanese Patent Application Laid-Open No. Sho 6 (1988)).
No. 1-15705). However, in the case of this semipermeable membrane support, the adhesion strength of the membrane to the support is not so high because the effect of anchoring the membrane to the above-mentioned depressions and through holes formed in the support is not sufficient. In addition, by forming a depression in the film forming surface of the support or forming a through hole in the support, a concave portion is also formed in the film itself formed on the surface, and the concave portion of the filtered liquid as described above is formed. The effective filtration area is likely to be reduced due to concentration on the membrane, and contaminants are likely to accumulate in the concave portions of the membrane. Further, in the case where the support is provided with small through holes, there is also a problem such as generation of pinholes due to strikethrough of the film forming solution.

Further, as another conventional technique, air permeability is improved for the purpose of improving the adhesion of a film to a support, preventing the occurrence of pinholes due to strike-through of a film forming solution, and improving mechanical properties. 5~50cc / cm ² at a low density dry web layer and air permeability of-seconds 0.1 cc / cm ² · sec or more 5 cc / cm ²
A semipermeable membrane support formed of a nonwoven fabric having a two-layer structure comprising a high-density wet web layer of less than seconds has been proposed (Japanese Patent Publication No. 5-35009). However, this semipermeable membrane support has a dry web (nonwoven fabric) having a rough surface in contact with the membrane.
Therefore, it is difficult to form a smooth film surface,
A wide effective filtration area cannot be secured.

Further, for the purpose of improving mechanical strength and water permeability, a support substrate made of a polyester nonwoven fabric is subjected to corona discharge treatment, and water is sprinkled within 5 to 10 seconds to form a porous support such as polysulfone. A method has been proposed in which a support layer film is prepared by casting a body solution, and a polyamide-based thin film is formed thereon to produce a semipermeable membrane (Japanese Patent Application Laid-Open No. 8-25539). However, in the case of using this method, it is necessary to use, as a support for forming the semipermeable membrane, one subjected to a multi-stage treatment of corona discharge treatment, water spraying and formation of a porous support layer,
Therefore, the process is complicated, and the use of a porous support material such as polysulfone has the disadvantage that the raw material cost is high.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semi-permeable membrane which has excellent adhesiveness, does not cause peeling or breakage of the semi-permeable membrane from a support, and has excellent dimensional stability. Even when used for high-pressure filtration, the membrane does not peel or break, and can stably support the membrane even at high filtration speeds. It is an object of the present invention to provide a high-quality semipermeable membrane support capable of forming a film having a high quality and capable of forming a film having no pinholes without causing strikethrough of a film forming solution. It is a further object of the present invention to provide a method for producing a semipermeable membrane support having the above-described characteristics, and a semipermeable membrane having the semipermeable membrane support.

[0009]

Means for Solving the Problems The inventors of the present invention have studied to achieve the above object. As a result, a nonwoven fabric made of polyester fiber having a specific breaking length and a specific air permeability is extremely suitable as a semipermeable membrane support. That a uniform and smooth film having excellent surface smoothness and no irregularities can be formed, a film having no pinholes and no strike-through of a film forming solution can be formed, and that the film has good adhesion. Furthermore, it was found that the membrane was excellent in dimensional stability, and there was no peeling or breakage of the membrane when used for high pressure filtration or the like. Further, the present inventors have found that the semipermeable membrane support having the above-mentioned excellent properties has a birefringence (Δn) of 0.170 or more and a heat shrinkage stress at 200 ° C. of 0.10 to 0.1 μm.
It was found that the polyester fiber of 60 g / d was used as a main fiber, and a paper was made using a raw material obtained by mixing a heat-fusible binder fiber with the main fiber. Based on this, the present invention has been completed.

That is, in the present invention, the average value of the breaking length in the machine direction (MD) and the transverse direction (CD) at 5% elongation is 4.
0 km or more and the air permeability is 0.2 to 10.0 cc /
A semipermeable membrane support comprising a nonwoven fabric having a cm ² · sec.

The above-mentioned semipermeable membrane support of the present invention comprises a polyester fiber having a birefringence (Δn) of 0.170 or more and a heat shrinkage stress at 200 ° C. of 0.10 to 0.60 g / d. Non-woven fabric comprising polyester fiber as a main fiber, preferably formed of a non-woven fabric as a main fiber, and further having a property that average monofilament fineness is 1.0 to 8.0 denier together with the above-mentioned birefringence value and heat shrinkage stress value. Is more preferably formed. The preferred polyester fibers constituting the nonwoven fabric include a diol unit composed of an ethylene glycol unit and / or a 1,4-butanediol unit and a dicarboxylic acid unit composed of a terephthalic acid unit and / or a naphthalenedicarboxylic acid unit. And poly (alkylene arylate) fibers mainly composed of

The present invention provides a method for producing a semipermeable membrane support, wherein the birefringence (Δn) is 0.170 or more and the heat shrinkage stress at 200 ° C. is 0.10 to 0.60 g.
/ D is formed from a raw material containing a polyester fiber and a heat-fusible binder fiber in a weight ratio of 70:30 to 30:70 to form a single-layer papermaking web. Using a papermaking web as it is or forming a laminated web having at least a layer of the papermaking web,
Heating or pressurizing the above-mentioned papermaking web or laminated web to bond the fibers together; or heating and pressing the above single-layer papermaking web to bond the fibers together, and then bonding the single-layer papermaking web to the fibers. Alternatively, a method for producing a semipermeable membrane support, comprising laminating other fiber webs and performing heat and pressure treatment to integrate them. Further, the present invention includes a semipermeable membrane with a support having a semipermeable membrane formed on one surface of the above semipermeable membrane support.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As described above, the semipermeable membrane support of the present invention has an average value of the tear length in the machine direction (MD) and the transverse direction (CD) at 5% elongation of not less than 4.0 km and an air permeability of 0. 0.2-1
It is made of a nonwoven fabric of 0.0 cc / cm ² · second.

In developing a semipermeable membrane support, the inventors of the present invention have found that the support used for the semipermeable membrane has a stress at the time of elongation of several percent, that is, 5%, rather than the value of elongation at break. It has been found that the stress during elongation is a very important requirement for the dimensional stability of the semipermeable membrane support. In particular, the average value of the breaking length in the machine direction (MD) and the transverse direction (CD) at the time of 5% elongation of the nonwoven fabric constituting the semipermeable membrane support [hereinafter referred to as "average breaking length (at 5% elongation)" Is 4.0
It has been found that the distance of not less than km is extremely important from the viewpoint of the dimensional stability of the semipermeable membrane support. Therefore, in the semipermeable membrane support of the present invention, the average breaking length (at the time of 5% elongation)
Is required to be 4.0 km or more as described above. The average breaking length (at 5% elongation) of the semipermeable membrane support is 4.0
When the distance is less than km, the dimensional stability of the semipermeable membrane support decreases, and the support is easily stretched due to the pressure applied to the semipermeable membrane at the time of filtration or the negative pressure at the time of washing the semipermeable membrane. Of the membrane, the membrane may be damaged, the pore size of the semipermeable membrane may be enlarged or deformed, and the filtration function may be deteriorated. In the semipermeable membrane support of the present invention, the average breaking length (at 5% elongation) is 5.0.
It is preferably at least km in terms of dimensional stability, membrane supporting ability, semipermeable membrane filtration performance and the like.

Here, the breaking length as referred to in this specification is J
It refers to a value measured according to ISP 8113 (1976), and is an index indicating the tensile strength of the nonwoven fabric itself that is not affected by the basis weight, width, etc. of the nonwoven fabric sample. The "average breaking length (at 5% elongation)" of the nonwoven fabric used for the semipermeable membrane support of the present invention can be determined by the method described in detail in the following examples.

In conventional nonwoven fabrics for clothing or industrial materials mainly composed of polyester fibers, the average breaking length (at 5% elongation) measured by the method described in the present specification is usually 3.8 km or less. In view of the above, the non-woven fabric constituting the semipermeable membrane support of the present invention is greatly characterized in that it has a high average breaking length (at 5% elongation), which is not generally used conventionally. is there.

Further, the air permeability of the semipermeable membrane support of the present invention must be in the range of 0.2 to 10.0 cc / cm ² · sec as described above, 5.0cc
/ Cm ² · sec. If the air permeability of the nonwoven fabric constituting the semipermeable membrane support is less than 0.2 cc / cm ² · sec, even if the film forming solution for forming the semipermeable membrane has a low concentration and a low viscosity, Does not sufficiently penetrate into the non-woven fabric, and the membrane does not firmly adhere to the non-woven fabric. On the other hand, the air permeability of the nonwoven fabric is 1
When the concentration exceeds 0.0 cc / cm ² · second, even if the film forming solution for forming the film has a high concentration and a high viscosity, it easily oozes to the back surface of the nonwoven fabric (the breakthrough easily occurs), At this time, air existing in the voids of the nonwoven fabric is entrained, and pinholes are easily generated in the film structure. The occurrence of pinholes
This results in a decrease in separation ability and a decrease in durability in the semipermeable membrane. Here, the air permeability of the nonwoven fabric referred to in this specification is JI
It refers to a value measured in accordance with SL 1079 (1966), the details of which are as described in the following Examples.

The semipermeable membrane support of the present invention has an average breaking length (5
% Elongation) is 4.0 km or more and the air permeability is 0.2 to 1
As long as the nonwoven fabric is made of a nonwoven fabric having a flow rate of 0.0 cc / cm ² · second, the type of fibers constituting the nonwoven fabric and the method for producing the nonwoven fabric are not particularly limited. Among them, in the present invention, as the main fiber forming the basic skeleton in the nonwoven fabric for the semipermeable membrane support, the birefringence (Δn) is 0.170 or more, and the heat shrinkage stress at 200 ° C. Shrinkage stress (200 ° C.) ”is 0.10 to 0.60 g /
d (g / denier) polyester fiber is preferably used. By using such a polyester fiber, the average breaking length (at 5% elongation) is 4.0 km or more and the air permeability is 0.2 to 10%. A target nonwoven fabric having a flow rate of 0.0 cc / cm ² · second can be smoothly obtained. Here, the birefringence (Δn) referred to in the present specification means that a Belek compensator is inserted into the optical path of a polarizing microscope using a sodium light source, as described in the following Examples. And a value determined by measurement in α-bromonaphthalene.

The birefringence (Δn) of the polyester fiber is 0.
Less than 170 and / or heat shrinkage stress (20
0 ° C) is less than 0.10 g / d, the average breaking length (5
% Elongation) at 4.0 km or more. Further, the heat shrinkage stress of the polyester fiber (200
℃) exceeds 0.60 g / d, the shrinkage of the web becomes large during the papermaking at the time of producing the nonwoven fabric or during the subsequent heating and pressurizing treatment, and the formation tends to deteriorate, which is severe. In some cases, cutting of the web may occur.

The polyester fiber used for clothing generally has a birefringence (Δn) of less than 0.170 and a heat shrinkage stress (200 ° C.) of less than 0.8 g / d;
Non-woven fabric made from this polyester fiber has low elastic modulus
Therefore, it is not suitable for the nonwoven fabric for a semipermeable membrane support of the present invention . Further, among polyester fibers used for industrial materials, those which require high strength, such as sewing threads, roofing materials, and ropes, are known to have a birefringence (Δn) exceeding 0.170. Its heat shrinkage stress (200
C) is less than 0.10 g / d, and the nonwoven fabric produced from such a polyester fiber also has a low elastic modulus, the average breaking length (at 5% elongation) does not exceed 4.00 km, and the It is not suitable for a nonwoven fabric for a permeable support. Also,
Polyester fibers used in special fishing nets such as sail canvas and longline have a heat shrinkage stress (200 ° C) of 0.
Some of them exceed 10 g / d, but their birefringence (Δn) is much lower than 0.170, which is also unsuitable for producing a nonwoven fabric for a semipermeable membrane support.

Therefore, the birefringence (Δn) is preferably 0.170 or more and the heat shrinkage stress (200 ° C.) is preferably 0.10 or more, which is preferably used as a main fiber in the nonwoven fabric for a semipermeable membrane support of the present invention. The polyester fiber of about 0.60 g / d is greatly different from the conventionally used polyester fiber, and this polyester fiber is subjected to spinning, drawing, and heat treatment steps as described in detail in Examples below. Can be manufactured through

In the present invention, as the main fibers in the nonwoven fabric for the semipermeable membrane support, the birefringence (Δn) is 0.170 or more, and the heat shrinkage stress (200 ° C.) is 0.10-0.
Any polyester fiber of 60 g / d is preferably used. Among them, such a polyester fiber can be obtained smoothly by using a poly (alkylene arylate) mainly composed of an aliphatic diol unit and an aromatic dicarboxylic acid unit. Therefore, in the present invention, as the main fibers constituting the nonwoven fabric for the semipermeable membrane support, the birefringence (Δn) is 0.170 or more and the heat shrinkage stress (200 ° C.) is 0.10 to 0.60 g. / D
The use of a poly (alkylene arylate) fiber as a preferred embodiment is included.

The above-mentioned poly (alkylene arylate) fibers include ethylene glycol units and / or
Alternatively, a fiber formed from a poly (alkylene arylate) mainly composed of a diol unit composed of a 1,4-butanediol unit and a dicarboxylic acid unit composed of a terephthalic acid unit and / or a naphthalenedicarboxylic acid unit is more preferably used. As a specific example, birefringence (△
n) is 0.170 or more, and heat shrinkage stress (200 ° C.)
Is 0.10 to 0.60 g / d, polyethylene terephthalate fiber, polyethylene naphthalate fiber, polybutylene terephthalate fiber and polybutylene naphthalate fiber. These poly (alkylene arylate) fibers can be used alone. Or two or more of them may be used in combination. In addition, these poly (alkylene arylate) fibers may have a structural unit derived from another copolymer component of about 20 mol% or less in some cases as long as the above-mentioned physical properties are satisfied.

Polyester fibers, which are the main fibers constituting the nonwoven fabric for the semipermeable membrane support (hereinafter sometimes referred to as “polyester main fibers”), have an average single fiber fineness of 1.
It is preferably from 0 to 8.0 denier, and from 1.0 to 8.0 denier.
More preferably, it is 4.5 denier. When the polyester fiber having the above average monofilament fineness is used, since the polyester fiber is relatively fine denier, the above-mentioned 0.1 fiber is maintained while maintaining sufficient strength in the nonwoven fabric.
A nonwoven fabric having air permeability of ^{2 to} 10.0 cc / cm ² · second and having excellent surface smoothness can be obtained smoothly. On the other hand, when the average single fiber fineness of the polyester main fiber is less than 1.0 denier, the air permeability of the nonwoven fabric having a high elastic modulus is 0.2 cc / cm ^{2 in} order to obtain a non-woven fabric having a high elastic modulus.
-When it is less than seconds, it tends to be low. On the other hand, when it exceeds 9.0 denier, the air permeability of the nonwoven fabric obtained thereby is 1
It exceeds 0 cc / cm ² · second or has a relatively large void, and in any case, it becomes difficult to form a semipermeable membrane having an excellent filtration function on the support.

The polyester-based fiber preferably has a fiber length (cut length) of 3 to 20 mm, which is suitable for the strength of the nonwoven fabric for the semipermeable membrane support, the dispersibility of the fiber in the stock solution used for papermaking, and the obtainability. This is preferred from the viewpoint of formation of the nonwoven fabric to be obtained.

The polyester-based fiber may have a circular or irregular cross-sectional shape. In the case of an irregular-shaped fiber, for example, an elliptical, triangular, quadrangular, pentagonal or higher polygon, Any cross-sectional shape such as a T-shape, a cross shape, a multi-lobe shape, a flat shape, and a dog bone shape can be adopted. Furthermore, as long as the polyester-based fiber does not impair its properties, in some cases, the core-sheath type, sea-island type,
It may be a composite fiber such as a side-by-side type.

The polyester-based fibers may include other polymers (for example, polyolefin, polycarbonate, polyamide, polyphenylene sulfide, polyetheretherketone, fluororesin, etc.), titanium oxide, etc., as long as the above-mentioned properties are not impaired. , Kaolin,
It may contain one or more additives such as silica, barium sulfate, carbon black, pigments, antioxidants, ultraviolet absorbers, and light stabilizers.

The birefringence (Δn) is 0.170 or more and the heat shrinkage stress at 200 ° C. is 0.10 to 0.10.
A polyester fiber having 0.60 g / d, particularly a polyester fiber having those properties and having an average monofilament fineness of 1.0 to 8.0 denier, especially such a fiber comprising poly (alkylene arylate) fiber. By using as a fiber to form a nonwoven fabric, the basis weight is low,
A very large number of very fine voids are uniformly dispersed throughout the nonwoven fabric, the adhesion of the semipermeable membrane is extremely good, and the surface is excellent in smoothness. The average breaking length (at 5% elongation) is 4.0 km or more. In addition, the nonwoven fabric for a semipermeable membrane support of the present invention having an air permeability of 0.2 to 10.0 cc / cm ² · sec can be obtained smoothly, and a semipermeable membrane having a large filtration area is provided on such a support. A film can be formed.

The method for producing the polyester-based fiber used for the nonwoven fabric for the semipermeable membrane support is not limited at all, and the birefringence (△
n) was produced by any method capable of producing a polyester fiber having the above-mentioned physical properties of 0.170 or more and a heat shrinkage stress (200 ° C.) of 0.10 to 0.60 g / d. It may be something. Although not limited in any way, polyester fibers having the above-mentioned properties can be melted using, for example, a polyester having an intrinsic viscosity of 0.5 to 0.8 dl / g [preferably the above-mentioned poly (alkylene allylate)]. After spinning, it can be produced by drawing in a warm water bath, followed by a tension heat treatment and / or a relaxation heat treatment, and then cutting to a predetermined length. The melt spinning conditions, stretching conditions (drawing ratio, stretching temperature, etc.), heat treatment conditions (heat treatment temperature, heat treatment time, tension during heat treatment, etc.) and winding conditions at that time depend on the type and intrinsic viscosity of the polyester used. What is necessary is just to select an appropriate thing according to it.

Although there is no particular limitation, for example, in the case of polyethylene terephthalate fiber, the spinning temperature is 275 to 300 ° C., and the take-up speed is 600 to 1000 m.
Per minute, and the resulting fiber is subjected to a drawing treatment at a temperature of 70 to 85 ° C and a draw ratio of 4.8 to 5.5. .9
Tensile heat treatment under conditions of about 9 to 1.01 times,
Birefringence (△) by relaxation heat treatment at 0 to 140 ° C. (for example, by placing a tow vertically on a free wire mesh belt and slowly moving it through a hot air dryer).
n) is 0.170 or more and the heat shrinkage stress (200 ° C.)
0.10 to 0.60 g / d of polyethylene terephthalate fiber can be obtained. For example, in the case of polybutylene naphthalate fiber, the spinning temperature is 270 to 295.
At a temperature of 70 to 85 ° C and a draw ratio of 4.8 to 5.5, and then polyethylene terephthalate. By performing the tension heat treatment and the relaxation heat treatment under the same conditions as in the case of the fiber, the birefringence (Δn) is 0.170 or more and the heat shrinkage stress (200 ° C.) is 0.10 to 0.60 g / d. Polybutile
A terephthalate fiber can be obtained.

In the above case, the stretching treatment may be carried out in one step or in two steps, and in the case of carrying out in two steps, the stretching temperature of the first step is 75 to 80 ° C. and the stretching ratio is 4.6. and <br/> a degree, 80-85 ° C. the stretching temperature of the second stage, the draw ratio 1.
It is preferred to be about 10 to 1.15. 2 stretching process
It is preferable to carry out in a step because the process is stable. When the above-described series of steps is adopted, by adjusting the conditions in the heat treatment step (tensile heat treatment and / or relaxation heat treatment) that is the final step, the birefringence (Δn) is 0.170 or more and the heat refraction is 0.170 or more. Shrinkage stress (200 ° C) is 0.1
A target polyester fiber having a weight of 0 to 0.60 g / d can be obtained smoothly.

In producing a nonwoven fabric for a semipermeable membrane support using the polyester-based fibers described above, in order to obtain a nonwoven fabric having excellent mechanical properties by making the bonding between the fibers in the nonwoven fabric strong and good. In addition, in order to obtain a nonwoven fabric having excellent surface smoothness and further facilitate the production of the nonwoven fabric, it is preferable to use a heat-fusible binder fiber together with a polyester-based fiber to produce the nonwoven fabric. In this case, the binder fiber melts at a lower temperature than the polyester-based fiber, has an average breaking length (at 5% elongation) of 4.0 km or more, and has an air permeability of 0.2 to 10.
Any thermoplastic fiber capable of forming a nonwoven fabric of 0 cc / cm ² · second can be used, and is not particularly limited. Examples thereof include polyester-based heat-fusible fibers, polyamide-based heat-fusible fibers, and polyolefin-based heat-fusible fibers. A fusible fiber or the like can be used. Among them, polyester-based heat-fusible fibers are preferably used as binder fibers from the viewpoint of affinity with polyester-based fibers and performance of the obtained nonwoven fabric as a semipermeable membrane support.

Examples of the polyester-based heat-fusible binder fibers include undrawn polyester fibers, low-melting polyester fibers, and low-melting polyesters and ordinary polyesters so that the low-melting polyester is present on at least a part of the fiber surface. Core-sheath type, side-by-side type, sea-island type, and other composite fibers. One type of polyester-based heat-fusible binder fiber may be used alone, or two or more types may be used in combination. In this case, as the low-melting polyester fiber or low-melting polyester, for example, a fiber having a low melting point obtained by copolymerization or melt mixing can be used. Further, as the polyester-based heat-fusible binder fiber, birefringence (△
n) is 0.05 or less and specific gravity is 1.335 to 1.360.
Those having the above range are preferably used since they have excellent adhesiveness between fibers. Further, the melting point of the heat-fusible binder fibers including the polyester-based heat-fusible binder fibers is preferably in the range of 120 to 210 ° C. from the viewpoint of heat-fusibility.

The ratio of polyester-based fibers to heat-fusible binder fibers when forming a nonwoven fabric is 70:30 to
The weight ratio is preferably 30:70, and 65:35.
More preferably, the weight ratio is up to 45:55. 30% by weight of polyester-based fiber based on the total weight of polyester-based fiber and heat-fusible binder fiber
If it is less than 4.0, the average breaking length (at 5% elongation) is 4.0 km.
It is difficult to obtain a non-woven fabric having the above-mentioned air permeability of 0.2 to 10.0 cc / cm ² · sec . On the other hand, if it exceeds 70% by weight, poor adhesion occurs between the fibers constituting the non-woven fabric. In addition, fluff and dimensional stability are likely to be reduced.

In the production of a nonwoven fabric for a semipermeable membrane support, the polyester-based fibers and the heat-fusible binder fibers described above are preferably used in the range of 70:30 to 3 as described above.
A nonwoven fabric can be produced by a dry method or a wet method using a weight ratio of 0:70, but a wet papermaking method is preferably used. In the case of the wet papermaking method, a method in which an aqueous slurry in which the polyester main fiber and the heat-fusible binder fiber are uniformly mixed and dispersed is prepared, and then the wet papermaking is performed according to an ordinary method is preferably used. The solid content concentration in the aqueous slurry is not particularly limited, and may be set to the same solid content concentration as in the case of ordinary wet papermaking.
An aqueous slurry having a final solid concentration of about 0.01 to 0.5% by weight is preferably used.

In preparing the aqueous slurry,
To increase the dispersibility of polyester-based fibers and heat-fusible binder fibers, etc., and to improve the performance of the obtained nonwoven fabric, hydrophilic agents, dispersing aids, defoamers, antistatic agents,
One or two of a release agent, a water repellent, an antibacterial and a bactericide may be added to the stock. Further, if necessary, a small amount of other components other than the above-mentioned components, for example, other polymer fibers or polymer binders may be used in combination within a range not to hinder the object of the present invention.

Next, wet papermaking is performed using the aqueous slurry prepared above, but the papermaking method and papermaking apparatus are not particularly limited, and any of the methods and apparatuses conventionally used in wet papermaking can be used. , for example, Fourdrinier, Extract by short wire cloth paper machine, can be carried out using one or two or more of such cylinder paper machine, two or more paper machines
When the joining is performed, a finished web (papermaking web) with further reduced papermaking unevenness is obtained.

The papermaking web obtained as described above is subjected to heat and pressure treatment in a single layer state, or a plurality of the papermaking webs are laminated, or the papermaking web and another fiber web are laminated to form a laminated web. In this state, a heat-pressing treatment is performed to melt the heat-fusible binder fibers and bond and integrate the fibers to produce a desired nonwoven fabric for a semipermeable membrane support. Alternatively, as another method, the single-layer papermaking web obtained as described above is heated and pressurized to melt the heat-fusible binder fibers and bond the fibers together, and then the same heating and heating is performed as described above. Laminating a single layer of papermaking web or other fiber web before applying pressure treatment,
If necessary, a method of producing a nonwoven fabric for a semipermeable membrane support by performing a heating and pressurizing treatment may be employed.

When a plurality of papermaking webs are stacked and heated and pressed, the uniformity of the integrated nonwoven fabric is increased by using the same kind of web, and the thickness direction is increased by using different kinds of webs. A nonwoven fabric having a difference in density and other physical properties can be obtained, and an appropriate one of them may be selected according to the use and type of the semipermeable membrane. In the case of a nonwoven fabric formed by laminating a plurality of papermaking webs and heating and pressurizing, in some cases, birefringence (Δn)
It is also possible to use a part of a web formed by using a fiber having a ratio of less than 0.170 and / or a heat shrinkage stress (200 ° C.) out of the range of 0.10 to 0.60 g / d.

The temperature and pressure during the heating and pressurizing treatment in the production of the nonwoven fabric depend on the type of the papermaking web, the method of superposition,
Although it can be adjusted according to the performance required for the semipermeable membrane support made of a nonwoven fabric, it is generally preferably 150 to
260 ° C, more preferably at a temperature of 200 to 240 ° C, preferably 50 to 150 kg / cm, more preferably 80 to
A linear pressure of 120 kg / cm is employed.

The type of the heat press device used for the heating and pressurizing treatment is not particularly limited, and a commonly used device can be used. For example, a calender device including a pair of heated metal rolls can be used. For example, a calender made of a combination of a heated metal roll and an elastic roll can be used. Further, a preheating device and / or a cooling device may be arranged before and after the heating press device. For example, when using a calendering device composed of a combination of a heating roll and an elastic roll, it is preferable to perform the heating and pressurizing treatment by passing through the front and back twice to prevent fuzzing on both sides of the nonwoven fabric and equalize the surface smoothness. Is preferred. In that case, the temperature and pressure conditions of the second heat treatment may be the same as or different from those of the first heat treatment.

From the above, the average breaking length (at 5% elongation)
Is 4.0 km or more and air permeability is 0.2 to 10.0 cc
The semipermeable membrane support of the present invention comprising a nonwoven fabric having a thickness of / cm ² · sec . Such a semipermeable membrane support has a higher elastic modulus and better dimensional stability than a conventional semipermeable membrane support. In addition, when the air permeability is the same, it has many pores and is excellent in surface smoothness as compared with a conventional semipermeable membrane support. Therefore, the semipermeable membrane support has excellent adhesion to the semipermeable membrane formed on the support, does not cause peeling or breakage of the semipermeable membrane, and is used even when used for high-pressure filtration. No dimensional change occurs, and no peeling or breakage of the film occurs.
Even if the filtration rate is high, the membrane can be stably supported, and a uniform and smooth membrane without irregularities can be formed.
It has various excellent properties that a film without pinholes can be formed without strikethrough of a film forming solution.

The semipermeable membrane support of the present invention having the above-mentioned excellent properties includes, for example, a filter for producing ultrapure water, a seawater desalination filter, an industrial or domestic wastewater purification filter, a blood purification filter, It can be used very effectively as a support in various semipermeable membrane devices such as a filter for liquid treatment such as a filter for concentrating food, a gas filter in an oxygen concentrator and the like. In some cases, it is possible to use a support having no semi-permeable membrane alone, as a preliminary filter, disposed in front of the semi-permeable membrane device.

In forming a semipermeable membrane on the semipermeable membrane support of the present invention to form a semipermeable membrane with a support, a semipermeable membrane is formed on a porous support such as a nonwoven fabric. Any of the conventionally known methods can be adopted and is not limited in any way. Also, the type of polymer for film formation used to form the semipermeable membrane, the type and content of the film forming solution, how to apply the film forming solution on the support,
The method for forming a film from the film-forming solution applied on the support is not limited at all. Although not limited in any way, for example, after casting or other method is applied to a film forming solution in which a polymer is dissolved or dispersed on the semipermeable membrane support of the present invention, solidification or drying is performed. By forming a semipermeable polymer membrane, the semipermeable membrane of the present invention comprising a support made of the above-described nonwoven fabric and a semipermeable membrane can be obtained.

[0045]

EXAMPLES The present invention will be specifically described below with reference to examples and the like, but the present invention is not limited thereto. In the following examples, the intrinsic viscosity of polyester, the birefringence (Δn) of polyester fiber and the heat shrinkage stress (20)
0 ° C.) and the average breaking length (at 5% elongation), air permeability, surface smoothness, and pore size of the nonwoven fabric (semi-permeable membrane support) were determined as follows. In the following example,
Unless otherwise indicated, means weight%.

<< Intrinsic Viscosity of Polyester [η] >> A solution obtained by dissolving a polyester chip in o-chlorophenol to a concentration of 0.5% was placed in a thermostat at 30 ° C., and an Ubbelohde viscometer was used. Was used to determine the relative viscosity (concentration: 0.5%) and the specific viscosity, and then the intrinsic viscosity was extrapolated and calculated from a previously prepared specific viscosity-concentration relationship graph (unit: dl / g).

<< Birefringence of Polyester Fiber (Δn) >> A Belek compensator was inserted into the optical path of a polarizing microscope using a sodium light source, and a temperature of 20 ° C.
It was measured and measured in α-bromonaphthalene under the conditions of ° C. and 65% relative humidity (unitless).

<< Heat shrinkage stress of polyester fiber (200
° C) >> Single fibers are sampled from the polyester tow before cutting so that the denier becomes 125 denier. This 125
After the denier fiber bundle is hooked on the upper and lower hooks (at an interval of about 5 cm) of a heat shrinkage stress measuring device (“KE-II type” manufactured by Kanebo Engineering Co., Ltd.), the fiber bundle is tied into a 250 denier fiber bundle. Next, an initial load of 15 g was applied to the 250-denier fiber bundle, and the temperature was increased at a heating rate of 300 ° C./120 seconds until the fiber was melted, and the heat shrinkage stress of the fiber at 200 ° C. was determined (unit: g). /Denier).

<< Average breaking length of nonwoven fabric (semipermeable membrane support) (at 5% elongation) >>
A test piece having a width of 15 mm × 200 mm is sampled, and the tensile strength in the longitudinal direction and the transverse direction is measured using the test piece in accordance with JIS P 8113 (1976), and corresponds to 5% elongation. The breaking length was determined from the applied tensile strength. Then, the average value of the longitudinal and transverse breaking lengths ｛(5 in the longitudinal direction)
% Breaking length + 5% breaking length in the transverse direction) / 2｝ was determined and defined as an average breaking length (at 5% elongation) of the nonwoven fabric (unit: km).
The average breaking length (at 5% elongation) is an index of the dimensional stability of the nonwoven fabric, and the larger the value, the higher the dimensional stability.

<< Permeability of Nonwoven Fabric (Semipermeable Membrane Support) >> From the nonwoven fabric obtained in each of the following examples, length × width = 200 mm ×
A test piece of 300 mm was sampled, and the
According to IS L 1079 (1966), the air permeability was measured using a Frazier type tester (unit: cc / c).
m ² · sec).

<< Surface Smoothness of Nonwoven Fabric (Semipermeable Membrane Support) >>
Using the nonwoven fabric obtained in each of the following examples, the surface smoothness was measured using a Beck tester in accordance with JIS P8119 (1976) (unit: seconds).

<< Pore Size in Nonwoven Fabric (Semipermeable Membrane Support) >> The nonwoven fabric obtained in each of the following examples was used in accordance with JIS.
The pore size (maximum pore diameter) of the nonwoven fabric was measured (unit: μm) according to “Explanation” (pages 7 to 10) attached to K 3832 (1990) “Method for testing bubble point of microfiltration membrane element and module”. The size of the pore size (maximum pore diameter) in the nonwoven fabric is an index of whether or not the number of fine pores is large when the air permeability is at the same level.

Examples 1 to 5 and Comparative Example 13 (1) A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 dl / g was melted at 300 ° C.
Through a spinneret having 00 pieces of round holes discharge at 285 ° C.
And taken up at a speed of 565 m / min.
One denier undrawn yarn was produced. (2) The undrawn yarn obtained in the above (1) is aligned and 6
50,000 denier tow, hot tub (75-85 temperature)
C), the film was stretched in two steps at a draw ratio shown in Table 1 below, and then subjected to a tension heat treatment and a relaxation heat treatment under the conditions shown in Table 1 below to obtain a birefringence (Δn) shown in Table 1 below. And a stretched polyester fiber having a heat shrinkage stress (200 ° C.) and an average monofilament fineness of 1.8 to 2.1, respectively, and cutting it into a length of 10 mm to obtain a crimp-free stretched PET short Fiber was obtained. The relaxation heat treatment was carried out by subjecting the material to a tension heat treatment (heat roller method) at a predetermined temperature, followed by drying with hot air in a free state for about 30 minutes.

(3) The stretched PET obtained in the above (2)
60 parts by weight of short fibers and PET undrawn short fibers [birefringence (△
n) 0.012, single fiber fineness 1.1 denier, fiber length 5
mm, specific gravity 1.340, circular cross section, no crimp] of 40 parts by weight into a pulper, and thoroughly mixed and dispersed in water to prepare an aqueous slurry having a fiber concentration of 0.05%. After the paper was sent to a round paper machine, it was dried by a Yankee dryer (120 ° C.) after the papermaking and wound up to produce a papermaking web (basis weight: 72 g / m ² ). (4) The paper web obtained in the above (3) was put on a heat calendering machine with a metal roll / cotton roll combination at a metal roll set temperature of 230 ° C. and a linear pressure of 80 kg / c.
m, at a processing speed of 10 m / min, first pass the back side (the non-contact surface of the Yankee dryer during papermaking) in contact with the metal roll, and then, under the same processing conditions, make the front side contact the metal roll. And then calendered on both sides to produce a PET non-woven fabric. The basis weight of the nonwoven fabric thus obtained was 72 to 74 g / m ² . (5) The average breaking length (5) of the nonwoven fabric obtained in (4) above
% Elongation) and the air permeability were determined by the methods described above, and were as shown in Table 1 below.

[0055]

[Table 1]

From the results shown in Table 1 above, unlike non-woven paper made of natural wood pulp, the performance of the non-woven fabric made of synthetic fiber varies greatly depending on the heat treatment conditions during fiber production, and the specific birefringence ( Δn) and a polyester fiber having a heat shrinkage stress (200 ° C.), in particular, a birefringence (Δn) of 0.170 or more and a heat shrinkage stress (20
(0 ° C.) is in the range of 0.10 to 0.60 g / d, so that the intended average breaking length (at 5% elongation) is 4.0 km or more and the air permeability is 0.
It can be seen that a nonwoven fabric of 2 to 10.0 cc / cm for a semipermeable membrane support can be obtained smoothly.

Examples 6 to 10 (1) A PET chip having an intrinsic viscosity of 0.64 dl / g was melted at 300 ° C., and the same operation as in (1) of Example 1 was performed to obtain a single fiber fineness. Produced an undrawn yarn of 17.8 denier. (2) The undrawn yarn obtained in the above (1) is aligned and 6
A 50,000 denier tow was drawn in a hot water bath (at a temperature of 75 to 85 ° C.) in the same manner as in (2) of Example 1 and stretched in two stages at a draw ratio shown in Table 2 below. Under the conditions shown in Table 2, a tensile heat treatment and a relaxation heat treatment were carried out to obtain a birefringence (Δn) and a heat shrinkage stress (200 μm) shown in Table 2 below.
C), and each of the drawn polyester fibers having an average single fiber fineness of 3.8 to 4.2 is produced, and the length is 1
It was cut to 0 mm to obtain a crimp-free drawn PET short fiber. (3) 55 parts by weight of the drawn PET short fiber obtained in (2) and 45 parts by weight of the same PET undrawn short fiber used in (3) of Example 1 were charged into a pulper. The same operation as in (3) of 1 was performed to produce a paper web (hereinafter referred to as “paper web A”) (basis weight 51 g /
m ² ).

(4) Apart from the above (1), the above (1)
An unstretched polyester yarn having an average monofilament fineness of 6.2 denier was produced by the same operation as described above, and the unstretched yarn was aligned to a tow of 650,000 denier to obtain a hot water bath (temperature of 75%).
８５85 ° C.), stretched in two steps at a stretching ratio shown in Table 2 below, and then subjected to a tension heat treatment and a relaxation heat treatment under the conditions shown in Table 2 below to obtain a birefringence (△) shown in Table 2 below. n) and a stretched polyester fiber having a heat shrinkage stress (200 ° C.) and an average monofilament fineness of 1.2 to 1.4, respectively, are cut to a length of 5 mm, and are drawn without crimping. PET short fibers were obtained. (5) 55 parts by weight of the drawn PET short fiber obtained in the above (4) and 45 parts by weight of the same PET undrawn short fiber used in (3) of Example 1 were charged into a pulper. The same operation as in (3) of 1 was performed to produce a paper web (hereinafter referred to as “paper web B”) (basis weight 51 g /
m ² ).

(6) The paper web A obtained in the above (3) and the paper web B obtained in the above (5) are layered one by one, and in the same manner as in (4) of Example 1, Both sides of the front and back are subjected to heat processing by a heat calendering machine of a metal roll / cotton roll combination, and the basis weight is 102 to 104 g.
/ M ² was produced. (7) The average breaking length (at 5% elongation) and the air permeability of the nonwoven fabric obtained in the above (6) were determined by the above-mentioned methods, and were as shown in Table 2 below.

[0060]

[Table 2]

From the results shown in Table 2 above, when laminating a plurality of webs and heating and pressing to produce a nonwoven fabric,
The birefringence (Δn) is 0.170 or more and the heat shrinkage stress (2
(00 ° C.) is in the range of 0.10 to 0.60 g / d, and when a nonwoven fabric is manufactured by heating and pressurizing using at least one layer of a finished web formed using polyester fibers. n) is not less than 0.170 and the heat shrinkage stress (200 ° C.) is in the range of 0.10 to 0.60 g / d. Even if (Example 1
0), only a web made of polyester fiber having a birefringence (Δn) of 0.170 or more and a heat shrinkage stress (200 ° C.) of 0.10 to 0.60 g / d. As in the case where a plurality of layers are laminated and heated and pressed to produce a nonwoven fabric (Examples 6 to 9), the desired average breaking length (5
% Elongation) is 4.0 km or more and the air permeability is 0.2 to 1
It can be seen that a nonwoven fabric for a semipermeable membrane support having a flow rate of 0.0 cc / cm · sec can be smoothly obtained.

Example 11 (1) An undrawn yarn was produced by changing the discharge amount of the molten polymer in the spinning step and performing the same operation as in (1) of Example 1 to produce an undrawn yarn. The tow was drawn up to 650,000 denier and stretched in two steps at a draw ratio shown in Table 3 below in a hot water bath (temperature of 75 to 85 ° C.) in the same manner as in (2) of Example 1. Tensile heat treatment and relaxation heat treatment are performed under the conditions shown in Table 3 below to produce drawn polyester fibers having birefringence (Δn), heat shrinkage stress (200 ° C.) and single fiber fineness shown in Table 3 below. Then, it was cut into a length of 10 mm to obtain a drawn PET short fiber without crimp. (2) 60 parts by weight of the drawn PET short fiber obtained in the above (1) and 40 parts by weight of the same PET undrawn short fiber used in (3) of Example 1 were charged into a pulper. One
After performing the same operation as in (3) to produce a paper web, in the same manner as in (4) of Example 1, heat processing is performed on both front and back surfaces with a heat calendering machine combining metal rolls / cotton rolls. A nonwoven fabric having a basis weight of 82 to 83 g / m ² was produced. (3) The average breaking length of the nonwoven fabric obtained in (2) (5)
% Elongation) and the air permeability were determined by the methods described above, and were as shown in Table 3 below.

[0063]

[Table 3]

From the results in Table 3 above, the average breaking length (5
% Elongation) is 4.0 km or more and the air permeability is 0.2 to 1
To obtain a nonwoven fabric of 0.0 cc / cm ² · sec, the birefringence (Δn) is 0.170 or more and the heat shrinkage stress (200
C) is in the range of 0.10 to 0.60 g / d , and it is preferable to use polyester fibers having a single fiber fineness of 1.0 to 8.0 denier, and the single fiber fineness of the polyester fiber is 1.0 denier. If less than the air permeability of the nonwoven fabric is 0.2c
c / cm ² · sec, and when it exceeds 8.0 denier, the air permeability of the nonwoven fabric is 10.0 cc / cm ² · ^second.
It can be seen that it easily exceeds seconds.

<< Examples 12 to 14 and Comparative Examples 4 to 5 >> (1) A polyethylene naphthalate (PEN) chip having an intrinsic viscosity of 0.62 dl / g was melted at 305 ° C.
It is discharged at 288 ° C. through a spinneret having 0 round holes, and is taken out at a speed of 565 m / min.
A 2 denier undrawn yarn was produced. (2) The undrawn yarn obtained in the above (1) is aligned and 6
50,000 denier tow, hot tub (75-85 temperature)
C)), the film was stretched in two steps at a stretching ratio shown in Table 4 below, and then subjected to a tension heat treatment and a relaxation heat treatment under the conditions shown in Table 4 below to obtain a birefringence (Δn) shown in Table 1 below. And a stretched polyester fiber having a heat shrinkage stress (200 ° C.) and an average monofilament fineness of 1.9 to 2.2, respectively, is cut to a length of 5 mm, and a stretched PEN short without crimping is produced. Fiber was obtained.

(3) The stretched PEN obtained in the above (2)
50 parts by weight of short fibers and PET undrawn short fibers [birefringence (△
n) 0.016, single fiber fineness 1.0 denier, fiber length 5
mm, specific gravity 1.342, circular section, no crimp] of 50 parts by weight into a pulper, and thoroughly mixed and dispersed in water to prepare an aqueous slurry having a fiber concentration of 0.05%. The paper was sent to a round paper machine, dried after drying by a Yankee dryer (120 ° C.), and rolled to produce a finished web (basis weight: 88 g / m ² ). (4) The paper web obtained in the above (3) is processed on both front and back sides with a hot calendering machine in the same manner as in (4) of Example 1, and the basis weight is 90 to 91 g / m ² . A non-woven fabric containing PEN fibers as main fibers was obtained. (5) The average breaking length (5) of the nonwoven fabric obtained in (4) above
% Elongation) and the air permeability were determined by the methods described above, and were as shown in Table 4 below.

[0067]

[Table 4]

From the results in Table 4 above, it can be seen that the same results as in the case of PET fibers are obtained when the main fibers constituting the nonwoven fabric are PEN fibers.

Comparative Examples 6 to 7 (1) PET fiber having a birefringence (Δn) of 0.166 and a heat shrinkage stress (200 ° C.) of 0.06 g / d (single fiber fineness: 6.0 denier, fiber length: 10 mm) ) 25 parts by weight, birefringence (Δn) 0.162 and birefringence (Δn) 0.05 g /
d PET fiber (single fiber fineness 1.5 denier, fiber length 5
mm) 30 parts by weight and 45 parts by weight of the same undrawn polyester short fiber as used in (3) of Example 1 are charged into a pulper, and thoroughly mixed and dispersed in water to form an aqueous slurry .
A rally is prepared , sent to a round paper machine, dried by a Yankee dryer (120 ° C.) after papermaking, and wound up.
A paper web was produced (basis weight 49 g / m ² ). (2) The paper web obtained in the above (1) was superimposed on two layers , and a metal roll / cotton roll combination type heat calendering machine was used. The metal roll temperature was 230 ° C and the linear pressure was 80 kg /. cm, at a processing speed of 10 m / min., one side is thermocompression-bonded, then the laminate is turned over and the other side is thermocompression-bonded under the same conditions (Comparative Example 6), or a metal roll temperature of 240 ° C., wire Pressure 150kg / cm, processing speed 10m
Thermocompression bonding under the conditions of 1 / min (Comparative Example 7),
g / m ² (Comparative Example 6) and a nonwoven fabric having a basis weight of 104 g / m ² (Comparative Example 7) were obtained.

(3) The average breaking length (at 5% elongation), the air permeability, the smoothness of the front and back surfaces, and the pore size of the nonwoven fabric obtained in the above (2) were determined by the above-mentioned methods. Was as shown in FIG. (4) For comparison, the average breaking length (at 5% elongation), the air permeability, the smoothness of the front and back surfaces, and the pore size of the nonwoven fabrics obtained in Examples 6 and 8 were also measured. It was as shown in the following Table 5 as determined by the above method. In Table 5 below, the surface subjected to the first heat calendering (the surface in contact with the metal roll for the first time) is a table, and the surface subjected to the second heat calendering (the second time) The surface smoothness was measured with the surface in contact with the back) as the back side.

[0071]

[Table 5]

Conventionally, there is an inverse correlation between the air permeability of the nonwoven fabric and the surface smoothness. When the density of the nonwoven fabric is reduced to increase the air permeability, the surface smoothness is reduced. Although it was a common practice to reduce the air permeability when the processing conditions at the time of calendering were strict or fine denier fibers were used, from the results in Table 5 above, according to the present invention, the air permeability was high and the surface was smooth. It is understood that a high-quality nonwoven fabric can be provided. Moreover, from the results in Table 5 above, it can be seen that in the nonwoven fabric of the present invention, the pore size (maximum pore diameter) is small, and the improvement of the air permeability is achieved by having many fine pores in the nonwoven fabric.

[0073]

The semipermeable membrane support of the present invention has dimensional stability,
It has excellent surface smoothness and adhesiveness to the membrane, and has high air permeability, and has excellent adhesiveness to the semipermeable membrane formed on the support, and does not cause peeling or breakage of the semipermeable membrane. Even when used for high-pressure filtration, dimensional change of the support does not occur and peeling or breakage of the membrane can be prevented, and the membrane can be stably supported even at a high filtration speed, and is uniform without irregularities Thus, a smooth film can be formed, and a film having no pinholes can be formed without a strikethrough of the film forming solution. The semipermeable membrane support of the present invention has excellent mechanical properties and excellent durability, so that the basis weight can be reduced and the life is long.

The semipermeable membrane support of the present invention having such excellent characteristics preferably has a birefringence (Δn) of 0.170 or more and a heat shrinkage stress at 200 ° C. of 0.10 to 0.10. A polyester fiber of 0.60 g / d,
More preferably, the birefringence (Δn) is 0.170 or more and 20
By using a polyester fiber having a heat shrinkage stress at 0 ° C. of 0.10 to 0.60 g / d and an average single fiber fineness of 1.0 to 8.0 denier as a main fiber,
It can be manufactured very smoothly. In addition, by using the heat-fusible binder fiber together with the polyester-based fiber at that time, the nonwoven fabric for the semipermeable membrane support can be manufactured with extremely simple operation by heat and pressure treatment with good productivity and economical efficiency. can do.

Therefore, the semipermeable membrane support of the present invention can be used, for example, by utilizing the above-mentioned characteristics, for example, a filter for producing ultrapure water, a desalination filter, an industrial or domestic wastewater purification filter, a blood purification filter, It can be used very effectively as a support in various semipermeable membrane devices such as a filter for liquid treatment such as a filter for concentrating food, a gas filter in an oxygen concentrator and the like.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akio Miyagi 121, Kawanoe-cho, Kawanoe-shi, Ehime Prefecture Miki Tokusou Special Paper Co., Ltd. (56) References JP-A-64-38226 (JP, A) JP-A 8- 10538 (JP, A) JP-A-4-78428 (JP, A) JP-A-61-15705 (JP, A) JP-A-61-71802 (JP, A) JP-A-58-79506 (JP, A) JP-A-60-75311 (JP, A) JP-A-62-1412 (JP, A) JP-A-8-25539 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 67/00-71/82 510 C02F 1/44 B01D 39/00-39/20

Claims (7)

(57) [Claims] 1. An average value of the breaking length in the machine direction (MD) and transverse direction (CD) at 5% elongation is 4.0 km or more and the air permeability is 0.2 to 10.0 cc / cm ² ··· A semi-permeable membrane support comprising a non-woven fabric for seconds. 2. The composition has a birefringence (Δn) of 0.170 or more and a heat shrinkage stress at 200 ° C. of 0.10 to 0.60.
2. The semipermeable membrane support according to claim 1, comprising a nonwoven fabric mainly composed of g / d polyester fibers. 3. Birefringence (Δn) of 0.170 or more and 20
A polyester fiber having a heat shrink stress at 0 ° C. of 0.10 to 0.60 g / d and an average single fiber fineness of 1.0 to 8.0 denier is a main fiber, and the content of the polyester fiber is 30 to 70% by weight. %. 3. The semipermeable membrane support according to claim 1, wherein the support is made of a nonwoven fabric. 4. The poly (alkylene) wherein the polyester fiber is mainly composed of a diol unit composed of ethylene glycol units and / or 1,4-butanediol units and a dicarboxylic acid unit composed of terephthalic acid units and / or naphthalenedicarboxylic acid units. The semipermeable membrane support according to any one of claims 1 to 3, which is an arylate) fiber. 5. A method for producing a semipermeable membrane support, wherein the polyester has a birefringence (Δn) of 0.170 or more and a heat shrinkage stress at 200 ° C. of 0.10 to 0.60 g / d. 70: 30-3 of fiber and heat-fusible binder fiber
After forming a single-layer papermaking web by performing papermaking using the raw materials contained in a weight ratio of 0:70, the single-layer papermaking web may be used as it is or a laminated web having at least the above-mentioned papermaking web layer. Forming the above-mentioned papermaking web or laminated web by heating and pressing to bond the fibers; or, after heating and pressing the single-layer papermaking web to bond the fibers to each other, A method for producing a semipermeable membrane support, comprising laminating a single-layer papermaking web or another fiber web, and performing heat and pressure treatment to integrate them. 6. The method according to claim 5, wherein the heat-fusible binder fibers are polyester fibers. 7. A semipermeable membrane with a support, wherein a semipermeable membrane is formed on one surface of the semipermeable membrane support according to claim 1.