JPH08325890A - Fluorine-based fiber woven fabric - Google Patents

Abstract

PURPOSE: To obtain a fluorine-based fiber woven fabric, rich in proper unevenness, having moderate bending resistance and excellent heat nonshrinkability and excellent in heat and chemical resistances. CONSTITUTION: This fluorine-based fiber woven fabric is woven from at least two kinds of fluorine-based fibers having different thicknesses and has <=5% heat shrinkability thereof for both warp and weft yarns by treatment with hot air at 130 deg.C for 5min. A filtration film 4 such as a PTFE polymeric film is sandwiched between two sheets 3 and 3 of the woven fabric, adjusted, formed and processed into, e.g. a pleat shape to provide a composite 2, which is then assembled in a filter cartridge, etc., for use. Thereby, effects such as efficient function without deformation due to heat are manifested in filtration at high temperatures.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorinated fiber woven fabric which is resistant to heat shrinkage.

[0002]

2. Description of the Related Art Woven fabrics woven from fluorine fibers are
Utilizing its excellent chemical resistance, heat resistance, water repellency, etc.,
It is used for various purposes. For example, for industrial use, it may be used as a filtering material for liquids and gases, and as a supporting member (reinforcing material) for a filtering membrane made of various materials. That is, when a gas or liquid is filtered and separated under atmospheric pressure or pressure using an ultrathin filtration membrane such as a polymer membrane, the membrane itself has a high risk of damage. It is usual to use a support member that can be composited with the membrane together, and such utilization has been increasing in recent years. Furthermore, it is also used for canvas cloth of paper machines, and many other uses are expected.

[0003]

By the way, for example, the use of a fluorinated fiber woven fabric as a support member for various filtration membranes is certainly more effective than other support members, but it also has the following problems. It has become an issue that must be resolved immediately. First, the fluorinated fiber woven fabric is much less stiff and more flexible than other fiber woven fabrics, and therefore has extremely poor handleability when processed. Therefore, in order to solve this, we are trying to increase the weaving density to give rigidity. However, since the fluorocarbon resin inherently has a much larger specific gravity than other resins, increasing the woven density results in an increase in weight, and in this respect, the handling property has not necessarily been improved. Further, the large weight causes a problem that the load resistance becomes worse, for example, when the paper machine is used as a canvas cloth, which is a problem.

Further, when the fluorinated fiber woven fabric is used as a filter cloth or as a support member of a filter membrane and water or the like is filtered, it does not pass through under a higher pressure. In other words, the filtration and separation efficiency is poor. It is considered that this is due to the fact that the surface tension of the fluorinated fiber to water is extremely high (high water repellency) and the smoothness of the surface of the woven fabric.

Further, the fluorinated fiber woven fabric has a function as a support member for protecting the filter membrane from damage when used as a filter cartridge filter medium, for example. As for the constitution of the filter material, the woven fabric (supporting member) is used on both sides, and the filter membrane is sandwiched between them to be aligned, and the whole is formed into a pleated shape. It is typical that the whole is made into a cylindrical shape and housed in the cartridge. This is to make the filtration area larger, but there is a problem in that the object to be filtered may not pass through quickly because the gap disappears when the pleated space becomes small due to shrinkage or the like.

Heat is used when forming the pleat shape or fixing the pleated shape fabric to another member such as a core, but this heat may cause the support member to contract. Further, when filtering hot air or liquid, or when filtering under heating, there is a risk of shrinking due to heat and deforming the whole, which is a problem.

The present invention has been found as a result of extensive studies to solve the above-mentioned various problems. A first object of the present invention is to provide a surface having an appropriate uneven shape and to have an appropriate shape. The present invention is to provide a fluorine-based fiber woven fabric having excellent bending resistance, and a second object is to propose a fluorine-based fiber woven fabric having extremely small heat shrinkage even when used with heat.

[0008]

That is, a feature of the present invention is a woven fabric woven by at least two kinds of fluorine-based fibers having different thicknesses, and 13
The heat shrinkage rate for 5 minutes at 0 ° C. (hot air) is the same, and it is 5% or less in each case. This will be described below.

As the material of the woven fabric in the present invention, at least two kinds of fluorine-based fibers having different thicknesses can be mentioned. The difference in thickness means that at least two kinds of fibers have a large diameter and a thin diameter. At this time, regarding the fibers, the monofilament and / or the multifilament itself is shown to be thick or thin as compared with the thickness of one filament. Among the multifilaments, there are twisted yarns, aligned yarns, covering yarns, and the like. Of course, all that is comprised of multiple filaments are included. The ratio of different thicknesses, that is, the ratio of thick filaments to thin filaments is generally 110 to 200%, preferably 120 to 150%, but this value is not particularly limited. This value means that if the diameter of the thin filament is 80 μm, the thick one is 88 to 160 μm, preferably 96 to 120 μm.

There are no particular restrictions on the diameters of the thick and thin two types of fibers, that is, the filaments,
Fine fibers are about 50-200 μm, preferably 80-15
0 μm, about 55 to 400 μm for thick fibers, preferably 6
For example, it can be about 0 to 300 μm. In addition, the diameter of the monofilament when the cross section is not circular is represented by the diameter of the minimum of the innumerable virtual circles drawn so as to cover all of the cross section, and the diameter of the multifilament is When the cross-sections of the individual filaments constituting the multifilament are circular, the sum of the maximum width and the maximum height, assuming that the filaments are arranged so as to contact one row in one direction, is divided by 2. Shall be represented by a value. At this time, when the individual filaments are not circular, the total width and height of the filaments are assumed to be aligned in one direction by connecting the ends of the cross sections of the filaments and forming the longest straight line. The sum of the maximum value and the maximum value is divided by 2. However, these things are not particularly limited, and when it is possible to make a judgment by visual inspection or the like, the judgment may be made by visual inspection or the like.

The fluorine-based fiber is made of a melt-spinnable fluorine-based resin, and examples of the resin include tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (hereinafter referred to as PFA) and tetrafluoroethylene / hexafluoro. Propylene copolymer, polyvinylidene fluoride (hereinafter referred to as PVDF), ethylene / tetrafluoroethylene copolymer, ethylene / chlorotrifluoroethylene copolymer, polyvinyl fluoride, polychlorotrifluoroethylene, etc. can be mentioned. . These may be blended polymers in which one kind or two or more kinds are appropriately mixed. Moreover, PFA and PVDF are mentioned as a preferable thing in the polymer illustrated above, and PFA is more preferable. The reason is that, as described above, it has excellent heat resistance and is resistant to inorganic acids and alkalis as well as organic solvents, so it can be effectively used for wider applications (for example, support members for ultrapure water filters). Is.

The above-mentioned fluororesin is melt-spun by a usual method to prepare a filament, but the method is not specified because it depends on the conditions generally used. That is, the fluororesin melt-extruded by the extruder is spun into a fibrous shape through a die and drawn while being drawn by an appropriate method. At this time, the nozzle shape of the die is not particularly specified, such as a circle, a quadrangle, and a triangle, but a circle is preferable. The reason is that, for example, when it is used as a support member for a filtration membrane, the fluid flow is smooth, and therefore foreign matter does not accumulate.

As described above, the fibers are monofilaments, multifilaments, etc., but monofilaments are preferred because of the ease of fluid flow, the ease of weaving, and the ease of processing.

Fluorine-based fibers are used in particular in the form of woven fabrics, since in other forms, such as nonwovens and knits, the object of the invention cannot be achieved effectively. The weaving means may be a weaving method such as a plain weave, a twill weave, and a double weave that are generally used, but there is no specific method.

In weaving, thick fibers and thin fibers are appropriately used for warp and weft. Which of the two, the weaving number to be used, is to be increased or decreased, and the weaving density and the like are to be determined. It is not specified because it is appropriately determined depending on the purpose of use and the use as a woven fabric. For example, when it is used as a support member for a filtration membrane by forming it into a pleat shape, it is desirable that the fabric has suitable rigidity so as to improve the handling property and the shape retention property.
Bending is increased by using a large number of thick fibers or increasing the weaving density. However, if the weaving density is too high, the fluidity of the fluid will be impaired, so care must be taken.

The above-mentioned handleability means the handleability and processability of the woven fabric. If such handling is poor, it cannot be smoothly processed into a special shape such as a pleat shape, and it is difficult to obtain a desired shape accurately, and as a result, the final target product can be quickly and highly produced. The yield cannot be obtained. Therefore, in particular, when the obtained woven fabric is used after being further processed into a certain shape, it is desirable to check the flexibility of the woven fabric and select and use the woven fabric in a preferable range. To numerically express this stiffness, the B method (slide method) of the stiffness measurement method according to JIS-L1096-1990 is used.
It is indicated by the bending resistance (N · cm). Since the bending resistance may differ in the machine direction and the transverse direction of the woven fabric, its average value is generally 0.0013 to 0.02 N · cm. Preferably 0.0
An example is 02 to 0.01 N · cm. N means Newton.

The fluorinated fiber woven fabric thus woven is
In many cases, it cannot be used immediately as it is. The reason is that the heat shrinkage of the woven fabric under specific conditions should not exceed 5%, especially when used for industrial applications,
Since it is sometimes used under heating, heat shrinkage is not preferable. Specifically, for example, when used as a functional member, a slight heat shrinkage may not be allowed. Further, when forming into a predetermined pleat or the like, heat setting is performed, but the heat at that time should not shrink more than a predetermined value. Further, when it is attached to a certain device (for example, a filter cartridge), it may be performed under heating, but in such a case, it should not shrink more than a predetermined value during the attachment. Therefore, it is ideal that the shrinkage due to heat is 0%.
% Or less, preferably up to 3% is acceptable. This is because the woven fabric of the present invention is composed of at least two types of fibers having different thicknesses and is made of fluorine-based fibers. Here, the thermal shrinkage (%) refers to the degree of shrinkage when heated with hot air at 130 ° C. for at least 5 minutes from the working temperature or processing temperature of the fluororesin. At this time, the heat shrinkage may vary depending on the material of the fluorine-based fiber,
For example, in the case of PFA, it is desirable to stay within 5% at 150 ° C for 60 minutes, and in the case of PVDF, it is 1
It suffices that the temperature falls within 5% at 30 ° C. × 5 minutes. From this also, the above value of 130 ° C. × 5 minutes is based on PVDF for the time being.

The heat shrinkage rate of a woven fabric is determined by factors such as characteristics of the fiber itself, weaving width, weaving tension, dimensions at the time of tentering, overfeed, and set (heat treatment) temperature, which are complicatedly entangled. Therefore, such factors are examined, and the heat shrinkage rate is 130 ° C (hot air) x 5 minutes, and if necessary 150 ° C (hot air) x 60 minutes, and 5 times each.
You must select the condition that is within%. The above-mentioned set is usually performed as a tenter and steam, hot plate, dry heat, etc. are used, but generally the set temperature is 150
It is performed in the range of up to 210 ° C. As a tentative guideline, a temperature higher by about 40 ° C. than the temperature at which the woven fabric is used can be mentioned. This value can be said when setting the fiber itself, and the operating temperature is considered to be up to 150 ° C. However, this value is not specified, and the set temperature is preferably as high as possible. If the woven fabric is simply washed with cold water without applying such a set, the heat shrinkage of the fiber itself may be the same as that of the woven fabric. To do. Therefore, the thermal contraction rate of the fiber itself used is 1
Setting the temperature to 30% (hot air) × 5 minutes within 5% is also a method for obtaining the woven fabric of the present invention, and thus the woven fabric of the present invention may not need to be set.

When fibers of different types of fluororesins are used, it is preferable to set them at the fiber stage.
Of course, it is desirable to set it even after weaving. Further, since the set has an effect of further improving the toughness in addition to the heat shrinkability, it is more desirable to set even if the heat shrinkage rate before setting is 5% or less.

The fluorinated fiber woven fabric according to the present invention is used in various applications making full use of its characteristics, and one effective example of use is the above-mentioned support member for a filtration membrane. The reason is as follows.

Generally, a filtration membrane is often used in a microfiltration method or an ultrafiltration method, which is made of a high molecular substance such as polytetrafluoroethylene (PTFE), PVDF, and ultra-high-molecular-weight polyethylene. It has a transparent hole and is generally very thin and soft with a thickness of about 0.5 mm or less. Therefore, since it is weak in strength and easily damaged, it is rarely used alone, and it is protected and reinforced by some means. One of the means is to use the support member together.

Nylon cloth, polypropylene cloth, polyester cloth and the like have been generally used as the support member. Although these cloths are used with their respective characteristics, they are not particularly satisfactory in heat resistance and chemical resistance, and depending on the usage of the filtration membrane, the filtration and separation efficiencies cannot be further improved. It can be said that the use of the woven fabric according to the present invention as a support member can solve the above-mentioned problems at once in response to the conventional drawbacks.

Since the woven fabric of the present invention is often used by adhering to a filtration membrane, that is, it is used in a composite form, its usage form is often determined by that of the filtration membrane. The form of use of the filtration membrane is flat, helical, or cylindrical. At this time, in most cases, the shape itself is devised so that the filtration area is as large as possible in order to maximize filtration and separation.

The filter membrane is pleated (accordion type) among the usage forms of the filtration membrane and is used as a cartridge. The filtration membrane can be installed in a narrow space with the maximum filtration area. Can be stored. Therefore, the filtration area can be further increased by making the whole into a cylindrical shape with the pleats spaced as closely as possible and in close contact with each other. This is particularly preferable when the present invention uses a woven fabric made of fluorine-based fibers having different thicknesses, for example, the thicknesses differing by about 110 to 200%. If this is used in the same way with the above-mentioned conventional polypropylene cloth, filtration and separability will be extremely lowered, so it is the current situation that pleats should be wide enough to have a gap, which is sufficient filtration. Since the area cannot be obtained, as a result, the filtration and separability are reduced.

The method for forming the pleat shape is not particularly limited. For example, first, a filter membrane of a predetermined size is placed at the center, and the two fluororesin fabrics are sandwiched between the two to firmly align them. Then, the whole is bent into an accordion shape so as to have a predetermined size, and compressed from both sides and heated.
The heating is preferably performed at a temperature lower than the heat resistant temperature of the filtration membrane and at least lower than the melting point of the woven fabric. In this way, it is heated up to the time of heat setting, taken out after cooling. If the whole is to be formed into a cylindrical shape, both ends may be bonded by an adhesive, fused, or sandwiched by a jig.

[0026]

In the present invention, by using at least two kinds of fluorine-based fibers having different thicknesses, it is possible to form suitable, for example, fine irregularities on the woven surface, and to obtain appropriate strength, bending resistance, heat resistance and chemical resistance. The present invention provides a woven fabric having a heat shrinkage rate of 5% or less at 130 ° C. (hot air) for 5 minutes.

Since such a suitable uneven surface creates a partial space, the object to be filtered passes through these voids even if it is a pleat-shaped support member for the filtration membrane and has a short width. And flows smoothly, so there is no accumulation of dust,
It is efficiently filtered and separated.

Further, it is advantageous to give such a woven fabric an appropriate degree of bending resistance because it is easy to handle and various kinds of processing can be carried out accurately and quickly. Further, the above-mentioned heat shrinkage of 5% or less and high heat resistance means that there is little thermal change when processed under heating or when used under heating. Therefore, it is easy to deal with various uses.

[0029]

EXAMPLES The present invention will be further described below by way of examples, but it goes without saying that the present invention is not restricted by these examples.

[0030]

Example 1 A monofilament was obtained by the following method using PFA (Teflon 44OHP manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) as the fluorine-based resin. That is, in order to spin fine fibers, a die with a nozzle diameter of 3 mmφ × 4 holes was attached to an extruder, and the barrel temperature was adjusted to 280 to 380 ° C. to perform melt spinning using the PFA described above, followed by cooling. The filament was drawn to obtain a filament. The draw ratio at this time was 2.3 times, and the diameter of the obtained monofilament was 110 μm. On the other hand, in order to spin a fiber having a large diameter, a die having a nozzle diameter of 3 mmφ × 4 holes was prepared, melt-spun and cold-drawn in the same manner as above to obtain a monofilament. The draw ratio at this time was 1.5 times, and the diameter of the obtained filament was 170 μm.

The heat shrinkage of each filament thus obtained (200 ° C. × 5 minutes, left in a hot air drier) was measured separately.
8.0%, 170 μm diameter monofilament is 17.
5%, with hot air at 130 ° C for 5 minutes, the former is 10%,
The latter is 9%, and the former is 14 at 150 ° C x 60 minutes.
%, And the latter was 13%.

Next, the above monofilaments having a diameter of 110 μm and 170 μm were driven at a rate of 3: 1 at a rate of 36 filaments / inch, and the monofilament having a diameter of 110 μm was hammered at 46 filaments / inch, and the weaving was performed. Width 45
cm plain weave fabric was woven.

Next, since the weave width of the plain weave fabric thus obtained is set by shrinking it by 17%, the finished width is 37.4.
cm through a tenter machine,
It was set by passing it through a heating furnace adjusted to ° C at a speed such that it was heated for 1 minute per 1 m. At this time, the overfeed in the warp direction was also set to be contracted by 17%.

A part of the obtained PFA fiber woven fabric was sampled and heated with hot air at 150 ° C. for 1 hour to check the heat shrinkage. Both the warp and the weft were 0.5% and no wrinkles were observed on the surface. Was not done. Also, on the surface, fine irregularities based on a monofilament with a diameter of 170 μm are uniformly formed,
The bending resistance was 0.0027 N · cm, and the handling was good. The heat shrinkage at 130 ° C. for 5 minutes was 0.3% for both warp and weft.

[0035]

[Embodiment 2] In this embodiment, weaving was performed by changing the number of driving in the embodiment 1 as follows, and fabrics having different bending resistances were produced. Therefore, the procedure was exactly the same as in Example 1 except for the number of implants. That is, the number of implants is 110 μm in diameter.
And 170 filaments of monofilament having a diameter of 170 μm were woven at a ratio of 3: 1 to 44 filaments / inch, and wefts were woven at 56 filaments / inch having a filament diameter of 110 μm. The bending resistance of the obtained woven fabric was 0.0053 N · cm, which was stiffer than that of Example 1 and was more excellent in handleability. The heat shrinkage ratio was the same as in Example 1.

[0036]

Example 3 PVDF (Hailer 460, manufactured by Ausimont Co.) was used as the fluorine-based resin, and a monofilament was obtained by the following method. That is, for fiber spinning of both small diameter and large diameter, a die with a nozzle diameter of 4 mmφ × 4 holes was attached to the tip of the extruder, the barrel temperature was set to 180 to 230 ° C., melt spinning was performed using the PVDF, and subsequently, Cold drawing was performed to obtain each monofilament. At this time, the draw ratio was 4.0 times for the former and 1.8 times for the latter, and the diameter of the obtained monofilament was 110 μm for the former and 150 μm for the latter.

When the heat shrinkage ratio (150 ° C. × 5 minutes, hot air dryer) of each of the obtained monofilaments was checked, the thin ones had a diameter of 20% and the large diameters had a percentage of 21%. The former is 15% and the latter is 16 in 5 minutes.
%Met.

Next, a monofilament having a diameter of 150 μm was used for the warp, and a monofilament having a diameter of 100 μm was used for the weft. The warp was driven at 36 yarns / inch and the weft was 46 yarns / inch to obtain a plain weave fabric having a weaving width of 45 cm.

This plain weave fabric has a finished width of 36.5 cm
To reduce the weaving width by 19%, and set it by passing it through a tenter machine through a heating furnace adjusted to 150 ° C at a speed such that it is heated for 1 m / min. I went. At this time, the overfeed in the warp direction was set to shrink by 20%.

A part of the obtained PVDF fiber woven fabric was sampled and heated at 150 ° C. for 1 hour, and the shrinkage rate was checked. Both the warp and the weft were constant at 0.5%, and there were no wrinkles on the surface. Not observed. In addition, the surface has moderate fine irregularities, and the bending resistance is 0.008 N · cm,
It was slightly stiffer than the PFA fiber woven fabric and was easy to handle. However, since the heat resistance is inferior to PFA, it is necessary to lower the operating temperature. At this time, 1
Heat shrinkage by hot air at 30 ° C for 5 minutes is 0% for both warp and weft
Met.

[0041]

Example 4 Using the PFA fiber woven fabric obtained in Example 2, a PTFE polymer filtration membrane was sandwiched between both sides,
After they were firmly aligned, they were folded so that the pleat width (the size of the crest and the crest on the opposite side) was 8 mm and the number of crests was 11. Then, a force of 5 kgf was applied to both sides to make it in a compressed state, heated at 150 ° C. for 30 minutes, cooled and released, and then taken out. As a result, a PTFE polymer filtration membrane was sandwiched between PFA fiber woven fabrics, and a pleated shape was obtained. A complex of

The obtained pleated composite was sandwiched from both sides so as to be compressed by glass plates, and the composite was housed in a container opened vertically. At the time of storage, the composite is stored so that a force of 5 kgf is applied from both sides, and the pleat surface contacting the inner wall of the container is filled with a sealing material to completely seal it and prevent water from leaking. I was not allowed to. The composite body thus compressed with a force of 5 Kgf is in a close contact state (only a part of the upper part has a gap, and the other parts are completely in close contact). The above is shown in FIGS. 1 and 2.

FIG. 1 is a side view of a heat-set pleated composite body 2 sandwiched by glass plates 1 from both sides. The composite 2 has a structure in which two PTFE polymer filtration membranes 4 are sandwiched between two PFA fiber woven fabrics 3 to form a composite. Figure 2 shows the container 5 opened up and down
FIG. 2 is a perspective view having a partial cross section showing a state in which the composite body 2 sandwiched between the glass plates of FIG. 1 is compressed and stored with a force of 5 Kgf therein. The following apparatus was used by using the apparatus shown in FIG. 1 and FIG.

First, the entire apparatus was immersed in an isopropyl alcohol solution for 1 minute, and the isopropyl alcohol on the surface was wiped off. Then, 1.0 cc of water was dropped on the upper surface of the composite body 2 placed at once, and the time until 1 cc of the water disappeared was measured (the time from the fall to the extinction arrow). The result was 10 seconds. The immersion in isopropyl alcohol is for lowering the surface tension of the PTFE film because water is repelled even if water is dropped onto the hydrophobic PTFE film as it is and it is difficult for water to pass therethrough.

[0045]

Comparative Example 1 Of the PFA monofilaments used in Example 2, only those having a diameter of 110 μm were used.
A plain weave was conducted in the same manner as in Example 2 with the same number of shots (65 / inch), and a heat treatment was carried out in the same manner as in Example 2 to obtain a woven fabric having the same heat shrinkage rate as in Example 2.

Using the obtained woven fabric, a pleated composite was formed in exactly the same manner as in Example 4, sandwiched between glass plates, stored in a container 5 in a state of being compressed by a force of 5 kgf, and passed through a container. As a water test device, a water flow test was conducted in the same manner as in the above example. As a result, the time until disappearance was 15 seconds.

As described above, in Comparative Example 1, water was passed for 5 seconds (50%) longer than in Example 4, which is a difference in effect depending on the presence or absence of fine unevenness. It demonstrates how the present invention is a good fabric.

[0048]

Comparative Example 2 Using the plain weave fabric obtained in Example 1, the tenter was set so that it could freely shrink by 10.5%, the overfeed was set to shrink by 10.5%, and the temperature was adjusted to 200 ° C. It was set by passing it through the heating furnace at a heating speed of 1 minute / 1 m.

A part of the PFA woven fabric obtained by the heat treatment was sampled and heated at 150 ° C. for 1 hour to check the heat shrinkage ratio. The warp and weft were 6.5%, and 130 ° C. for 5 minutes. Both the warp and the weft were 6%, and small wrinkles were scattered on the surface. This means that wrinkles are generated when the heat shrinkage ratio exceeds 5%. Therefore, if the woven fabric is used as a support member for a filtration membrane, it cannot be practically used for filtration and separation, especially at high temperatures. Become.

[0050]

INDUSTRIAL APPLICABILITY According to the present invention, since suitable unevenness is formed on the woven surface, when it is used as a supporting member of a filtration membrane, for example, it is possible to filter an object to be filtered very efficiently with a maximum filtration area. The effect that it can be separated is exhibited.
Furthermore, since the woven fabric of the present invention has an appropriate bending resistance, it is easy to handle, and the molding process suitable for the purpose can be accurately and quickly performed, and also has excellent heat resistance, and the heat shrinkability is also measured by the present invention. Since it is 5% or less in the method, it has an effect that it can be used under heating and can be molded and processed under heating, so that it can be easily applied to various applications. In addition, it has excellent chemical resistance not only to organic solvents but also to inorganic acids and alkalis, so when used as a support member for filtration membranes, for example, it efficiently filters many types of substances to be filtered. It can be separated, and future applications are highly expected.

The application of the present invention is effectively used as a support member for a filtration membrane as described above, but the present invention is not limited to this, and is expected to be utilized by taking advantage of the above-mentioned characteristics in a canvas cloth of a paper machine. It can be used in various other fields.

[Brief description of drawings]

FIG. 1 is a side view showing a process of forming the woven fabric of the present invention into a pleated composite.

FIG. 2 is a perspective view showing a state in which a pleat-shaped composite body sandwiched between glass plates is housed in an upper and lower open container.

[Explanation of symbols]

 1. Glass plate 2. Pleated laminate 3. Support member 4. PTFE polymer membrane 5. Container (open above and below)

Claims (5)

[Claims] 1. A woven fabric woven from at least two kinds of fluorine-based fibers having different thicknesses, and 1 of the woven fabrics
A fluorinated fiber woven fabric having a heat shrinkage ratio of 5 minutes at 30 ° C. (hot air) for 5 minutes or less. 2. The fluorinated fiber woven fabric according to claim 1, wherein at least two types of fluorinated fibers having different thicknesses in the range of 110 to 200% are used. 3. The fluorinated fiber woven fabric according to claim 1, wherein the woven fabric has a heat shrinkage ratio of 60% at 150 ° C. (hot air) for 60 minutes and is 5% or less for each weft. 4. The fluorinated fiber woven fabric according to claim 1, wherein the fluorinated fiber comprises a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer. 5. The fluorinated fiber woven fabric according to claim 1, which is used as a support member for a filtration membrane.