KR102402635B1 - Non-woven Fabric Support for Ion Exchange Membrane and Method for Manufacturing The Same - Google Patents

Abstract

Disclosed are a non-woven fabric support for an ultra-thin ion exchange membrane comprising a polyphenylene sulfide (PPS) resin as a main component and having excellent tensile strength, and a method for manufacturing the same. The nonwoven fabric support for an ultra-thin ion exchange membrane of the present invention has an average diameter of 0.1 to 7 μm and includes a plurality of fibers including polyphenylene sulfide, a thickness of 20 to 30 μm, an average pore diameter of 5 to 10 μm, 50 It has a porosity of from to 90%, an air permeability of from 20 to 50 cm ³ /cm ² /S, and a tensile strength of from 5 to 50 MPa.

Description

Non-woven Fabric Support for Ion Exchange Membrane and Method for Manufacturing The Same

The present invention relates to a nonwoven fabric support for an ion exchange membrane and a method for manufacturing the same, and more particularly, to an ultra-thin nonwoven fabric support for an ion exchange membrane comprising a polyphenylene sulfide (PPS) resin as a main component and having excellent tensile strength, and its manufacturing method It relates to a manufacturing method.

Rechargeable batteries provide a simple and efficient method of storing electricity, so efforts are being made to miniaturize them and increase their mobility to use them as an intermittent auxiliary power source or as a power source for small household appliances such as laptops, tablet PCs, and mobile phones.

Among them, a redox flow battery (RFB) is a secondary battery that can store and use energy for a long period of time by repeating charging and discharging by an electrochemical reversible reaction of an electrolyte. The stack and the electrolyte tank, which determine the capacity and output characteristics of the battery, are configured independently of each other, so the battery design is free and the installation space is small.

The redox flow battery is generally composed of two separate electrolytes. One stores the electroactive material in the negative electrode reaction and the other is used in the positive electrode reaction. In an actual redox flow battery, the electrolyte reaction is different between the positive electrode and the negative electrode, and since the electrolyte flow phenomenon exists, a pressure difference occurs between the positive electrode and the negative electrode. An ion exchange membrane with improved physical and chemical durability is required to overcome the pressure difference at both electrodes and to exhibit excellent battery performance even after repeated charging and discharging, and in the redox flow battery, the ion exchange membrane is about It is a core material that accounts for 10% of the price.

As such, in the redox flow battery, the ion exchange membrane is a key component that determines the battery life and price. For the commercialization of the redox flow battery, the selective permeability of the ion exchange membrane is high, so that the crossover of vanadium ions is It should be low, electrical resistance should be small, ionic conductivity should be high, and mechanical and chemical stability should be high durability and low price.

Polymer electrolyte membranes, which are currently commercialized as ion exchange membranes, have been used for several decades and are being continuously studied. Recently, direct methanol fuel cell (DMFC) or polymer electrolyte membrane fuel cell (PEMFC) Cell, proton exchange membrane fuel cell), a redox flow battery, a number of studies on the ion exchange membrane as a medium for transferring ions used in water purification, etc. are being actively conducted.

As a material widely used as an ion exchange membrane, there is a material of the Nafion™ series, which is a polymer containing a perfluorinated sulfonic acid group from DuPont, USA. The membrane made of this material has an ionic conductivity of 0.08 S/cm at room temperature, excellent mechanical strength and chemical resistance at a saturated moisture content, and has stable performance as an electrolyte membrane enough to be used in fuel cells for automobiles.

In addition, commercially available membranes of a similar type include Aciplex-S membranes manufactured by Asahi Chemicals, Dow membranes manufactured by Dow Chemicals, and Asahi Glass Ltd. There are Flemion membrane, Gore & Associate's GoreSelect membrane, etc., and a polymer perfluorinated in alpha or beta form by Ballard Power System of Canada. It is under development research.

However, the membranes are expensive and have difficulty in mass production due to a complicated synthesis method, crossover phenomenon in electrical energy storage systems such as redox flow batteries, and have low ionic conductivity at high or low temperatures. As an ion exchange membrane, it has a disadvantage that the efficiency is greatly reduced.

On the other hand, in order to increase the mechanical strength and dimensional stability of the ion exchange membrane, it has been proposed to use a porous support by electrospinning polyimide. However, since the polyimide porous support prepared by electrospinning is in the form of a nonwoven fabric including a large number of pores, it can be impregnated with an ion conductor, so it can be used as a support for an ion exchange membrane, but there are problems in that productivity is low and mechanical strength is weak.

Korean Patent Laid-Open Publication No. 10-2011-0128814 discloses a long fiber by spunbond method using polyphenylene sulfide (PPS) resin as a raw material that has excellent heat resistance, chemical resistance, flame retardancy and insulation, and can be used in very harsh environments. A method for manufacturing a nonwoven fabric was introduced. However, the nonwoven fabric prepared in this way has weak tensile strength, has a high weight of 200 g/m ² or more in weight per unit area, and has a high thickness of 300 μm or more, so it cannot be applied as a support for an ion exchange membrane.

Accordingly, the present invention relates to a nonwoven fabric support for an ion exchange membrane that can prevent problems due to the limitations and disadvantages of the related art, and a method for manufacturing the same.

One aspect of the present invention is to provide a non-woven fabric support for an ultra-thin ion exchange membrane comprising a PPS resin as a main component and having excellent tensile strength.

Another aspect of the present invention is to provide a method for manufacturing a non-woven fabric support for an ultra-thin ion exchange membrane comprising a PPS resin as a main component and having excellent tensile strength.

In addition to the above-mentioned aspects of the present invention, other features and advantages of the present invention will be described below or will be clearly understood by those of ordinary skill in the art from such description.

According to one aspect of the present invention as described above, it has an average diameter of 0.1 to 7 μm and includes a plurality of fibers including polyphenylene sulfide, a thickness of 20 to 30 μm, an average pore diameter of 5 to 10 μm, 50 to A porosity of 90%, an air permeability of 20 to 50 cm ³ /cm ² /S, and a tensile strength of 5 to 50 MPa, the nonwoven support for an ion exchange membrane is provided.

The average diameter of the fibers may be preferably 0.5 to 5 μm, more preferably 1 to 3 μm.

The polyphenylene sulfide may include p-phenylene sulfide and m-phenylene sulfide as repeating units, and may include 95 mol% or more of the p-phenylene sulfide.

The nonwoven support for the ion exchange membrane may preferably have a thickness of 22 to 28 μm.

According to another aspect of the present invention, the method comprising: melting a polyphenylene sulfide resin; extruding the molten polyphenylene sulfide resin; discharging the polyphenylene sulfide resin at a single hole discharge rate of 0.08 to 0.2 g/min/hole through the nozzle hole by spraying air to the extruded polyphenylene sulfide resin at a pressure of 0.5 to 1.5 kgf/cm ² ; forming a web by collecting fibers formed while the polyphenylene sulfide resin is discharged; and thermocompression bonding the web at a pressure of 10 to 50 kgf/cm ² using a roll heated to 40 to 150° C. A method for producing a nonwoven support for an ion exchange membrane is provided.

The polyphenylene sulfide resin may have a melting point of 280 to 290 °C.

The melt index (MI) of the polyphenylene sulfide resin measured at 300° C. according to ASTM D1238 may be 100 to 2000 g/10 min.

The molten polyphenylene sulfide resin may be maintained at 290 to 320° C. until it is discharged through the nozzle hole.

The polyphenylene sulfide resin may be discharged through the nozzle hole at a spinning speed of 4,000 to 21,000 m/min.

Nip pressure applied to the web in the thermocompression bonding step may be 22 to 145 kgf / cm.

The above general description of the present invention is only for illustrating or explaining the present invention, and does not limit the scope of the present invention.

The ion exchange membrane nonwoven support of the present invention has PPS as a main component, which has excellent chemical resistance, and is manufactured according to the melt spinning method, thereby having superior productivity and mechanical strength compared to the electrospinning method, and has excellent uniformity and porosity compared to the spunbonding method. There is an advantage in that a nonwoven fabric having a thinner thickness can be easily manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are intended to aid the understanding of the present invention and constitute a part of this specification, illustrate embodiments of the invention, and together with the description, explain the principles of the invention.
1 schematically shows an apparatus for manufacturing a nonwoven fabric support for an ion exchange membrane according to an embodiment of the present invention,
2a and 2b are SEM photographs each showing the plane and cross-section of the nonwoven fabric support for an ion exchange membrane prepared according to Example 1 of the present invention.

Hereinafter, a method of manufacturing a nonwoven fabric support for an ion exchange membrane according to an embodiment of the present invention will be described in detail with reference to FIG. 1 .

1 illustrates an apparatus 100 for manufacturing a nonwoven fabric support for an ion exchange membrane according to an embodiment of the present invention.

First, a polypropylene sulfide (PPS) resin is introduced into the extruder 110 through the input unit 111 and then melted therein. The molten PPS resin is extruded toward the nozzle 120 by the screw 112 in the extruder 100 .

The PPS included as a main component in the PPS resin may include p-phenylene sulfide and m-phenylene sulfide as repeating units, and may contain 95 mol% or more of the p-phenylene sulfide. When there is a lot of m-phenylene sulfide, the melting temperature of the PPS resin is lowered, which makes economical efficiency and workability easier. do.

The PPS resin may have a melting point of 280 to 290 °C, and the melt index (MI) of the PPS resin measured at 300 °C according to ASTM D1238 is 100 to 2000 g/10min, more preferably 600 to 1400 g/ It can be 10min.

When the melt index (MI) of the PPS resin exceeds 2,000 g/10min, the flowability of the molten PPS resin is improved, making it easy to spin, but excessively stretched fibers may be cut and a fly phenomenon may occur. There is a high risk of causing the side effect of producing dust.

On the other hand, the melt index (MI) of the PPS resin is less than 100 g/10min, and the internal pressure of the spinning facility including the extruder 110 and the nozzle 120 increases excessively, thereby causing damage to the detention hole 121 and ultimately, it may be difficult to manufacture microfibers.

Then, the PPS resin is discharged through the nozzle hole 121 by spraying the air provided from the air manifold 130 to the extruded PPS resin.

According to the present invention, in order to produce an ultra-thin nonwoven fabric made of short fibers having a small average diameter of 0.1 to 7 μm, the PPS resin is 0.08 by spraying air to the PPS resin at a pressure of 0.5 to 1.5 kgf/cm ² . to 0.2 g/min/hole, more preferably 0.1 to 0.15 g/min/hole, so that it is discharged through the nozzle hole 121. In particular, when the single hole discharge amount exceeds 0.2 g/min/hole, the average diameter of fibers constituting the nonwoven fabric exceeds 7 μm, so it may be difficult to manufacture an ultra-thin nonwoven fabric having a thickness of 30 μm or less.

According to an embodiment of the present invention, the molten PPS resin may be maintained at 290 to 320 °C until discharged through the nozzle hole 121 (that is, a radiation temperature of 290 to 320 °C).

When the spinning temperature is less than 290 ° C, the molten PPS resin does not smoothly pass through the spinneret, and the internal pressure of the spinning facility including the extruder 110 and the spinneret 120 rises excessively. will cause damage. In addition, since sufficient elongation is not ensured, fibers having an average diameter of 7 μm or less cannot be obtained, and the bonding force between the short fibers stacked on the collector 140 is weakened, thereby reducing mechanical strength. A nonwoven fabric having a low mechanical strength cannot be used as a support for an ion exchange membrane. In particular, the thermocompression bonding process of the present invention cannot be performed on a web composed of short fibers that are not sufficiently bonded.

On the other hand, when the spinning temperature exceeds 320° C., excessively stretched fibers may be cut due to the excessive temperature and a fly phenomenon may occur, which may create a side effect of mass-producing fine dust. In addition, since the PPS fibers that have received excessive thermal energy do not form sufficient crystals during the stretching process with air, the crystallinity is lowered, and heat shrinkage and wrinkles are caused during the thermocompression bonding process of the present invention that is subsequently performed, so that the ion exchange membrane It cannot be used as a support for the In addition, the bonding force between the short fibers stacked on the collector 140 becomes too strong, and accordingly, an appropriate average pore diameter (eg, 5 to 10 μm) cannot be secured, so that the porosity is rapidly reduced. An excessively low porosity of the nonwoven fabric (eg, less than 50% porosity) may make it difficult to impregnate the nonwoven fabric with a sufficient amount of an ion conductor when manufacturing an ion exchange membrane.

According to the present invention, in order to produce an ultra-thin nonwoven fabric made of short fibers having a small average diameter of 0.1 to 7 μm, the PPS resin is discharged through the detention hole 121 at a spinning speed of 4,000 to 21,000 m/min. do. The spinning speed (m/min) can be calculated by Equation 1 below.

* Equation 1: Spinning speed = 9,000 × single hole discharge (g/min/hole)/average fineness (De)

When the spinning speed is less than 4,000 m/min, the PPS fiber cannot be sufficiently drawn, so it cannot have a small average diameter of 7 μm or less, so it may be difficult to manufacture an ultra-thin support having a thickness of 30 μm or less, and the crystallinity is excessively low, heat shrinkage and wrinkles are caused in the subsequent thermocompression bonding process, so that it cannot be used as a support for an ion exchange membrane in the future.

On the other hand, when the spinning speed exceeds 21,000 m/min, excessively stretched fibers are cut to cause a fly phenomenon, which may cause a side effect of mass-producing fine dust.

The fibers formed while the polyphenylene sulfide resin is discharged from the nozzle hole 121 are collected and laminated on the collector 140 to form a web.

According to the present invention, in order to increase the mechanical strength of the nonwoven fabric formed of the PPS microfibers and to prepare a support for an ultra-thin ion exchange membrane having a thickness of 30 μm or less, the web is thermocompression bonded.

According to the present invention, the web is thermocompression-bonded at a pressure of 10 to 50 kgf/cm ² by a roll heated to 40 to 150 °C. At this time, the Nip pressure applied to the web may be 22 to 145 kgf / cm.

When the compression process is performed by a roll heated to less than 40° C., there is a problem in that heat shrinkage of the non-woven fabric support is greatly generated when the ion conductor impregnation process and the drying process are performed for manufacturing the ion exchange membrane.

On the other hand, when the pressing process is performed by a roll heated to a temperature exceeding 150° C., the web having a relatively low crystallinity by being manufactured in a melt-blown method is excessively heat-shrinked and a large amount of wrinkles are generated. Nonwoven fabrics cannot be used as supports for ion exchange membranes.

On the other hand, when the web is compressed with a roll pressure of less than 10 kgf/cm ² (or a nip pressure of less than 22 kgf/cm), it may be difficult to manufacture an ultra-thin nonwoven support having a thickness of 30 μm or less.

On the other hand, when the web is compressed with a roll pressure exceeding 50 kgf/cm ² (or a Nip pressure exceeding 145 kgf/cm), macropores are generated. Even after passing through, the large pores act as a defect.

The nonwoven fabric support for an ion exchange membrane of the present invention prepared through the method described above includes a plurality of PPS fibers having an average diameter of 0.1 to 7 μm, preferably 0.5 to 5 μm, and more preferably 1 to 3 μm.

As described above, the PPS includes p-phenylene sulfide and m-phenylene sulfide as repeating units, and may include 95 mol% or more of p-phenylene sulfide.

The nonwoven support of the present invention has a thickness of 20 to 30 μm, more preferably 22 to 28 μm. If the thickness of the nonwoven support is less than 20 μm, the tensile strength in the range to be described later cannot be secured. On the other hand, if the thickness of the nonwoven support exceeds 30 μm, it is not suitable as a support for an ion exchange membrane.

The nonwoven support of the present invention has an average pore diameter of 5 to 10 μm, a porosity of 50 to 90%, an air permeability of 20 to 50 cm ³ /cm ² /S, and a tensile strength of 5 to 50 MPa.

If the average pore diameter is less than 5㎛, it is difficult to impregnate the ion conductor into the nonwoven fabric support during the manufacture of the ion exchange membrane. On the other hand, when the average pore diameter exceeds 10 μm, the ion conductor cannot effectively block the pores, which acts as a defect.

If the porosity is less than 50% or the air permeability is less than 20 cm ³ /cm ² /S, the amount of impregnation of the ion conductor is decreased, and thus the role of the ion exchange membrane cannot be effectively performed. On the other hand, when the porosity exceeds 90% or the air permeability exceeds 50 cm ³ /cm ² /S, the mechanical properties of the nonwoven support are reduced, and thus ease of handling is deteriorated.

Hereinafter, the present invention will be described in detail through specific examples. However, the following examples are only for helping the understanding of the present invention, and the scope of the present invention should not be limited thereto.

Example One

A PPS web was prepared using the apparatus illustrated in FIG. 1 . Specifically, a dope is prepared by melting a PPS resin (SK Chemical) having a p-phenylene sulfide repeating unit of 95 mol% or more, a melting point of 283.7° C. and a melt index of 900 g/10 min at 300° C., and extrusion By spraying air at a pressure of 0.8 kgf/cm ² to the dope, the dope was discharged from the detention hole (diameter: 0.25 mm) at a single hole discharge rate of 0.1 g/min/hole and a spinning speed of 12,663 m/min. The short fibers formed while the dope was discharged were collected and stacked on a collector to form a web having an average thickness of 80 μm. The distance from the nozzle hole to the collector was fixed at 70 mm.

Then, the web was thermocompressed with a roll pressure of 50 kgf/cm ² (Nip pressure: 145 kgf/cm) using upper and lower calender rolls heated to 70° C., and the weight per unit area of 20 g/m 2 and 23 μm A nonwoven support having a thickness was completed. 2A and 2B are SEM photographs of a plane and a cross-section of the nonwoven support, respectively.

Example 2

Using the same method as in Example 1, except that the air pressure was 0.8 kgf/cm ² and the spinning speed was 17,450 m/min, a nonwoven support having a weight per unit area of 20 g/m 2 and a thickness of 25 μm was completed.

Example 3

Weight per unit area of 20 g/m 2 using the same method as in Example 1 except that the air pressure was 1.3 kgf/cm ² , the single hole discharge rate was 0.125 g/min/hole, and the spinning speed was 20,033 m/min and a nonwoven support having a thickness of 26 μm was completed.

comparative example One

The air pressure was 1.2 kgf/cm ² , the single hole discharge rate was 0.125 g/min/hole, the spinning speed was 18,462 m/min, and a roll of 20 kgf/cm ² using the upper and lower calender rolls heated to 25° C. A nonwoven support having a weight per unit area of 20 g/m 2 and a thickness of 43 μm was completed in the same manner as in Example 1, except that pressure (Nip pressure: 20 kgf/cm) was used for thermocompression bonding.

comparative example 2

Weight per unit area of 20 g/m 2 using the same method as in Example 1 except that the air pressure was 0.4 kgf/cm ² , the single hole discharge rate was 0.25 g/min/hole, and the spinning speed was 3,995 m/min and a nonwoven support having a thickness of 23 μm was completed.

The strength of each of the nonwoven supports prepared by Examples and Comparative Examples was measured by the following method, and the results are shown in Table 1 below.

average fiber diameter (μm)

After collecting more than 20 measurement samples, the fiber diameter was measured using a scanning electron microscope (SEM) and an image analyzer (using JVC Digital Camera KY-F70B for Image-Pro Plus software), and the average of the measured diameters was measured. was calculated.

air permeability ( cm ³ / cm ² /S)

Air permeability was evaluated using Textest Instruments (Model: FX-3300) according to the Frazier Machine Method (ASTM D 737 or KS K 0570). Air permeability is the amount of air passing vertically per unit area under a certain area and under a certain pressure for the test piece to be evaluated. A method of measuring the amount of air passing through a certain area (cm ² ) per unit time (sec) (cm ³ ) This was applied.

porosity ( % )

The porosity of the nonwoven support was measured using a Mercury porosimeter (model Autopore IV, Micromeritics Instrument Corp. USA). At this time, the mercury (Hg) penetration method, which is one of the most common methods for measuring the pore size distribution of a porous sample, was applied.

Average pore diameter (㎛)

The average pore diameter of the nonwoven support was measured using a capillary flow porometer (Model: CFP-1100-AEL, manufacturer: PMI). According to ASTM F 316-03, the measurement standard was measured by 10 each. After cutting the nonwoven filter to prepare a circular specimen with a diameter of 1 inch, a Galwick solution with a surface tension of 15.9 dyne/cm was used to sufficiently wet the pores of the nonwoven support for measurement.

The tensile strength ( MPa )

The tensile strength moves so that the upper clamp can be stretched at a constant speed by the constant rate of extension (CRE, KS K 0521 or ASTM D 5035) method, and the equipment used at this time is a universal testing machine (universal testing) machine, Model: UTM-3365) was used to measure the tensile strength of the nonwoven support.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 radiation
Condition single hole discharge
(g/min/hole) 0.10 0.10 0.125 0.125 0.25 air pressure
(kgf/cm ² ) 0.8 1.21 1.3 1.20 0.4 Radiation speed (m/min) 12,663 17,450 20,033 18,462 3,995 thermocompression bonding Temperature (℃) 70 70 70 25 70 Pressure (kgf/cm ² ) 50 50 50 20 50 nonwoven support Weight per unit area
(g/m ² ) 20 20 20 20 20 Thickness (㎛) 23 25 26 43 23 average fiber diameter
(μm) 2.7 2.3 2.4 2.5 7.6 Air permeability (㎤/㎠/S) 27-40 28-41 26-37 70-90 65-83 Porosity (%) 58 63 54 58 46 Average pore diameter (㎛) 8.3 9.8 8.5 14.5 12.5 Tensile strength (MPa) 21 17 15 5 18

110: extruder 111: input unit
120: detention 121: detention hall
130: air manifold 140: collector

Claims (10)

and a plurality of fibers having an average diameter of 0.1 to 7 μm and comprising polyphenylene sulfide,
A thickness of 20 to 30 μm, an average pore diameter of 5 to 10 μm, a porosity of 50 to 90%, an air permeability of 20 to 50 cm ³ /cm ² /S, and a tensile strength of 5 to 50 MPa. ,
Non-woven fabric support for ion exchange membrane. The method of claim 1,
Characterized in that the average diameter of the fibers is 0.5 to 5 ㎛,
Non-woven fabric support for ion exchange membrane. The method of claim 1,
Characterized in that the average diameter of the fibers is 1 to 3 μm,
Non-woven fabric support for ion exchange membrane. The method of claim 1,
The polyphenylene sulfide comprises p-phenylene sulfide and m-phenylene sulfide as repeating units, characterized in that it contains 95 mol% or more of the p-phenylene sulfide,
Non-woven fabric support for ion exchange membrane. The method of claim 1,
The non-woven fabric support for the ion exchange membrane is characterized in that it has a thickness of 22 to 28 ㎛,
Non-woven fabric support for ion exchange membrane. melting the polyphenylene sulfide resin;
extruding the molten polyphenylene sulfide resin;
Discharging the polyphenylene sulfide resin at a single hole discharge rate of 0.08 to 0.2 g/min/hole through the nozzle hole by spraying air to the extruded polyphenylene sulfide resin at a pressure of 0.5 to 1.5 kgf/cm ² ;
forming a web by collecting fibers formed while the polyphenylene sulfide resin is discharged; and
It characterized in that it comprises the step of thermocompression bonding the web at a pressure of 10 to 50 kgf / cm ² using a roll heated to 40 to 150 ℃,
A method of manufacturing a non-woven fabric support for an ion exchange membrane. 7. The method of claim 6,
The polyphenylene sulfide resin has a melting point of 280 to 290 ℃,
characterized in that the melt index (MI) of the polyphenylene sulfide resin measured at 300° C. according to ASTM D1238 is 100 to 2000 g/10min,
A method of manufacturing a non-woven fabric support for an ion exchange membrane. 7. The method of claim 6,
Characterized in that the molten polyphenylene sulfide resin is maintained at 290 to 320 °C until discharged through the nozzle hole,
A method of manufacturing a non-woven fabric support for an ion exchange membrane. 7. The method of claim 6,
The polyphenylene sulfide resin is characterized in that it is discharged through the nozzle hole at a spinning speed of 4,000 to 21,000 m/min,
A method of manufacturing a non-woven fabric support for an ion exchange membrane. 7. The method of claim 6,
Nip pressure applied to the web in the thermocompression bonding step is characterized in that 22 to 145 kgf / cm,
A method of manufacturing a non-woven fabric support for an ion exchange membrane.

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