KR20180003006A - Non-woven Fabric Support for Ion Exchange Membrane and Method for Manufacturing The Same - Google Patents

Abstract

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

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-woven fabric support for ion exchange membranes,

More particularly, the present invention relates to a nonwoven fabric support for an ultra-thin ion exchange membrane having polyphenylene sulfide (PPS) resin as a main component and having an excellent tensile strength, and a non- And a manufacturing method thereof.

BACKGROUND ART Rechargeable batteries provide a simple and efficient method of storing electric power, so that they have been miniaturized to increase their mobility, and efforts to utilize them as an intermittent auxiliary power source or a power source for a small household appliance such as a laptop, a tablet PC, and a mobile phone have been continued.

Among them, Redox Flow Battery (RFB) is a secondary battery which can store energy by repeating charging and discharging by electrochemical reversible reaction of an electrolyte for a long time. The stack and electrolyte tanks, which depend on the capacity and output characteristics of the battery, are independent of each other, so that the battery design is free and the installation space is limited.

The redox flow cell generally consists of two separate electrolytes. One stores the electroactive material in the negative electrode reaction and the other stores the positive electrode reaction. In an actual redox flow cell, the electrolyte reaction is different between the positive electrode and the negative electrode, and there is a flow of the electrolytic solution, so a pressure difference occurs between the positive electrode and the negative electrode. In order to overcome the pressure difference at both electrodes and repeat charging and discharging, it is necessary to have an ion exchange membrane having improved physical and chemical durability. In the redox flow battery, It is the core material that accounts for 10% of the price.

As described above, in the redox flow battery, the ion exchange membrane is a key component for determining battery life and price. In order to commercialize the redox flow battery, the ion permeability of the ion exchange membrane is high and the crossover of vanadium ions Low electrical resistance, high ionic conductivity, mechanical and chemical stability, high durability and low cost.

Recently, polymer electrolyte membranes commercialized as ion exchange membranes have been used for decades and have been studied steadily. Currently, direct methanol fuel cells (DMFC) and polymer electrolyte membrane fuel (PEMFC) ion exchange membranes have been actively studied as mediators of ion transport in the cell, proton exchange membrane fuel cell, redox flow cell, and water purification.

As a substance widely used as an ion exchange membrane, there is a Nafion (TM) series of polymers containing perfluorinated sulfonic acid groups of DuPont, USA. The membrane made from this material has ionic conductivity of 0.08 S / cm at room temperature, excellent mechanical strength and chemical resistance when it has a saturated moisture content, and has stable performance as an electrolyte membrane for use in automotive fuel cells.

A similar type of a commercial membrane may be an Aciplex-S membrane of Asahi Chemicals, a Dow membrane of Dow Chemicals, a membrane of Asahi Glass, Flemion membrane from Gore & Associate, and GoreSelcet membrane from Gore & Associate. In Ballard Power System, Canada, the alpha or beta type of perfluoropolymer It is under development study.

However, the above-mentioned membranes are difficult to mass-produce due to their high price and complicated synthesis method, and also have problems such as a crossover phenomenon in an electric energy storage system such as a redox flow cell and a low ion conductivity at a high temperature or a low temperature The efficiency of the ion exchange membrane 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 a nonwoven fabric including a plurality of pores, the ion conductor can be impregnated, so that it can be used as a support for an ion exchange membrane, but the productivity is low and the mechanical strength is low.

Korean Patent Laid-Open Publication No. 10-2011-0128814 discloses a polyphenylene sulfide (PPS) resin which is excellent in heat resistance, chemical resistance, flame retardancy and insulation and can be used even in a very harsh environment, A method of manufacturing nonwoven fabric was introduced. However, since the nonwoven fabric thus produced is weak in tensile strength, has a weight per unit area of 200 g / m ² or more, has a high weight, and has a high nonwoven fabric thickness of 300 탆 or more, it can not be used as a support for ion exchange membranes.

Accordingly, the present invention is directed to a nonwoven substrate for an ion exchange membrane and a method of manufacturing the same, which can prevent problems due to limitations and disadvantages of the related art.

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

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

Other features and advantages of the invention will be set forth in the description which follows, or may be learned by those skilled in the art from the description.

In accordance with one aspect of the present invention as described above, it comprises a plurality of fibers having an average diameter of 0.1 to 7 占 퐉 and comprising polyphenylene sulfide and having a thickness of 20 to 30 占 퐉, an average pore size of 5 to 10 占 퐉, A non-woven support for ion exchange membranes is provided which has 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.

It is preferred that the average diameter of the fibers is 0.5 to 5 탆, more preferably 1 to 3 탆.

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

It is preferable that the nonwoven fabric support for ion exchange membrane has a thickness of 22 to 28 탆.

According to another aspect of the present invention, there is provided a method for producing a polyphenylene sulfide resin, comprising: melting a polyphenylene sulfide resin; Extruding the molten polyphenylene sulfide resin; Discharging the polyphenylresulfide resin through a through hole at a single injection amount of 0.08 to 0.2 g / min / hole by spraying air to the extruded polyphenylene sulfide resin at a pressure of 0.5 to 1.5 kgf / cm ² ; Collecting fibers formed by discharging the polyphenylene sulfide resin to form a web; And thermo-compressing the web at a pressure of 10 to 50 kgf / cm ² using a roll heated to 40 to 150 ° C.

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 캜 according to ASTM D1238 may be 100 to 2000 g / 10 min.

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

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

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

The foregoing general description of the present invention is intended to be illustrative of or explaining the present invention, but does not limit the scope of the present invention.

The ion-exchange membrane nonwoven substrate of the present invention is characterized by having PPS as a main component having excellent chemical resistance and having excellent productivity and mechanical strength as compared with the electrospinning method by the melt spinning method. There is an advantage that a nonwoven fabric having a thinner thickness can be easily manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
FIG. 1 schematically shows an apparatus for manufacturing a nonwoven fabric support for an ion exchange membrane according to an embodiment of the present invention,
FIGS. 2A and 2B are SEM photographs showing a plan view and a cross-sectional view, respectively, of a nonwoven fabric support for an ion exchange membrane manufactured according to Example 1 of the present invention.

Hereinafter, a method for 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 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 injected into an extruder 110 through a charging section 111 and then melted therein. The molten PPS resin is extruded toward the detoning unit 120 side by the screw 112 in the extruder 100.

PPS contained as a main component in the PPS resin includes p-phenylene sulfide and m-phenylene sulfide as repeating units, and may contain 95 mol% or more of the p-phenylene sulfide. When the amount of the m-phenylene sulfide is large, the melting temperature of the PPS resin is lowered, which is advantageous in that the economical efficiency and workability are facilitated. However, it is preferable that the p-phenylene sulfide unit is contained in an amount of 95 mol% Do.

The PPS resin may have a melting point of 280 to 290 DEG C and the melt index (MI) of the PPS resin measured at 300 DEG C according to ASTM D1238 is 100 to 2000 g / 10 min, more preferably 600 to 1400 g / Lt; / RTI >

If the melt index (MI) of the PPS resin is more than 2,000 g / 10 min, the flowability of the molten PPS resin is improved to facilitate spinning, but the excessively stretched fibers may be cut off and fly phenomenon may occur, There is a great risk of causing side effects that produce dust.

On the other hand, if the melt index (MI) of the PPS resin is less than 100 g / 10 min and the internal pressure of the spinning apparatus including the extruder 110 and the spinneret 120 is excessively increased, Ultimately, microfiber fabrication may be difficult.

Then, the air supplied from the air manifold 130 is injected into the PPS resin to be extruded, thereby discharging the PPS resin through the detaching hole 121.

According to the present invention, in order to produce an ultra-thin nonwoven fabric made of staple fibers having a small average diameter of 0.1 to 7 탆, air is sprayed to the PPS resin at a pressure of 0.5 to 1.5 kgf / cm ² , To 0.2 g / min / hole, and more preferably 0.1 to 0.15 g / min / hole. In particular, when the single-ended discharge amount exceeds 0.2 g / min / hole, the average diameter of the fibers constituting the nonwoven fabric exceeds 7 탆, making it difficult to manufacture the ultra-thin nonwoven fabric having a thickness of 30 탆 or less.

According to an embodiment of the present invention, the molten PPS resin may be maintained at 290 to 320 캜 (i.e., a spinning temperature of 290 to 320 캜) until it is discharged through the detaching hole 121.

If the spinning temperature is less than 290 ° C, the molten PPS resin does not smoothly pass through the spinneret and the inner pressure of the spinning apparatus including the extruder 110 and the spinneret 120 is excessively increased, Causing damage. Further, since sufficient stretching can not be ensured, fibers having an average diameter of 7 mu m or less can not be obtained, and the bonding strength between the short fibers stacked on the collector 140 is weakened, and the mechanical strength is lowered. Nonwoven fabric having low mechanical strength can not be used as a support for an ion exchange membrane. In particular, the thermocompression process of the present invention can not be performed on a web composed of short fibers that are not sufficiently bonded.

On the other hand, when the spinning temperature is higher than 320 ° C, excessively stretched fibers may be cut due to excessive temperature, causing a fly phenomenon, which can produce a side effect of mass production of fine dust. Further, since the PPS fibers subjected to excessive heat energy are not sufficiently formed in the course of drawing by air, the degree of crystallization is lowered, and heat shrinkage and wrinkles are generated in the subsequent thermal compression process of the present invention, It can not be used as a support for a substrate. In addition, the bonding force between the laminated short fibers on the collector 140 becomes too strong, which makes it impossible to secure an appropriate average pore size (for example, 5 to 10 mu m), and the porosity is drastically reduced. Excessively low porosity (e.g., porosity of less than 50%) of the nonwoven fabric can make it difficult for a sufficient amount of ionic conductor to be impregnated into the nonwoven fabric in the preparation of the 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 탆, the PPS resin is discharged through the detaching hole 121 at a spinning speed of 4,000 to 21,000 m / min do. The spinning speed (m / min) can be calculated by the following equation (1).

* Equation 1: Radial speed = 9,000 占 Single discharge (g / min / hole) / Average fineness (De)

When the spinning speed is less than 4,000 m / min, the PPS fibers can not be stretched sufficiently and thus have a small average diameter of 7 탆 or less, which makes it difficult to produce an ultra-thin support having a thickness of 30 탆 or less. The heat shrinkage and wrinkling are caused in the subsequent thermocompression bonding process and can not be used as a support for an ion exchange membrane in the future.

On the other hand, when the spinning speed is more than 21,000 m / min, excessively stretched fibers are cut off, causing a fly phenomenon, which may cause side effects of mass production of fine dust.

The polyphenylene sulfide resin is discharged from the piercing hole 121, and the fibers formed and collected on the collector 140 form a web.

According to the present invention, in order to increase the mechanical strength of the nonwoven fabric formed of PPS microfine fibers and to manufacture a supporter for an ultra-thin ion exchange membrane having a thickness of 30 μm or less, the web is thermally pressed.

According to the present invention, the web is hot-pressed 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 pressing process is performed by a roll heated to less than 40 캜, there is a problem that heat shrinkage of the nonwoven fabric substrate is largely generated when the ion conductor impregnation process and the drying process are performed for the preparation of 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 is excessively heat-shrunk and a large amount of wrinkles are generated due to the meltblown method, The nonwoven fabric can not be used as a support for an ion exchange membrane.

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

On the other hand, when the web is squeezed with a roll pressure exceeding 50 kgf / cm ² (or a Nip pressure exceeding 145 kgf / cm), macropores are generated. In the process of impregnating the thus- The macropores act as defects.

The nonwoven substrate for an ion exchange membrane of the present invention prepared by the above-described method comprises a plurality of PPS fibers having an average diameter of 0.1 to 7 mu m, preferably 0.5 to 5 mu m, more preferably 1 to 3 mu m.

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

The nonwoven substrate of the present invention has a thickness of 20 to 30 mu m, more preferably 22 to 28 mu m. If the thickness of the nonwoven fabric support is less than 20 占 퐉, the tensile strength in the range described below can not be ensured. On the other hand, if the thickness of the nonwoven fabric support exceeds 30 탆, it is unsuitable as a support for an ion exchange membrane.

The nonwoven substrate of the present invention has an average pore size 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 占 퐉, the ion conductor is hardly impregnated with the nonwoven fabric support during the production of the ion exchange membrane. On the other hand, when the average pore size exceeds 10 탆, the ion conductor can not effectively block pores and acts as a defect.

The porosity less than 50% or if the air permeability is less than ^{20 cm 3 / cm 2 / S} , the amount of impregnation of the ionic conductor can not write down so do the ion exchange membrane serves as effectively. On the other hand, if the porosity exceeds 90%, or air permeability is more than ^{50 cm 3 / cm 2 / S} , the support is a nonwoven fabric decreases the mechanical properties to deteriorate the ease of handling.

Hereinafter, the present invention will be described in detail with reference to specific examples. It should be noted, however, that the following examples are intended to assist the understanding of the present invention and should not limit the scope of the present invention thereby.

Example  One

A PPS web was prepared using the apparatus illustrated in FIG. Specifically, a PPS resin (SK Chemical Co.) having a melting point of 283.7 DEG C and a melt index of 900 g / 10 min, which contains 95 mol% or more of p-phenylene sulfide repeating units, is melted at 300 DEG C to prepare a dope, The dope was discharged from the spinneret hole (diameter: 0.25 mm) at a single-ended discharge rate of 0.1 g / min / hole and a spinning speed of 12,663 m / min by spraying air at a pressure of 0.8 kgf / cm ² . The short fibers formed by discharging the dope were collected and laminated on a collector to form a web having an average thickness of 80 mu m. The distance from the cage hole to the collector was fixed at 70 mm.

Subsequently, the web was thermocompression bonded at a roll pressure of 50 kgf / cm ² (Nip pressure: 145 kgf / cm) using an upper and a lower calender roll heated to 70 캜 to obtain a weight per unit area of 20 g / Thereby completing the nonwoven fabric support having a thickness of 5 mm. Figures 2a and 2b are SEM images of the plan and cross-section of the nonwoven substrate, respectively.

Example  2

A nonwoven substrate having a weight per unit area of 20 g / m 2 and a thickness of 25 탆 was prepared in the same manner as in Example 1, except that the air pressure was 0.8 kgf / cm ² and the spinning rate was 17,450 m / min.

Example  3

A weight per unit area of 20 g / m < 2 > was measured using the same method as in Example 1, except that the air pressure was 1.3 kgf / cm ² , the single throughput was 0.125 g / min / hole and the spinning rate was 20,033 m / And a non-woven support having a thickness of 26 mu m were completed.

Comparative Example  One

A single roll of 20 kgf / cm ² using an upper and a lower calender roll heated to 25 ° C, and a pressure of 1.2 kgf / cm ² , a single throughput of 0.125 g / min / hole and a radial velocity of 18,462 m / Nonwoven substrate having a weight per unit area of 20 g / m < 2 > and a thickness of 43 mu m was completed by the same method as in Example 1, except that the thermocompression bonding was carried out under pressure (Nip pressure: 20 kgf / cm).

Comparative Example  2

A weight per unit area of 20 g / m < 2 > was obtained using the same method as in Example 1, except that the air pressure was 0.4 kgf / cm ² , the single throughput was 0.25 g / min / hole, and the spinning rate was 3,995 m / And a non-woven support having a thickness of 23 mu m were completed.

The strengths of the nonwoven substrates prepared according to the examples and comparative examples, respectively, were measured by the following methods, and the results are shown in Table 1 below.

Average fiber diameter  (탆)

Twenty or more measurement samples were collected and fiber diameters were measured using a scanning electron microscope (SEM) and an image analyzer (using JVC Digital Camera KY-F70B in Image-Pro Plus software) and the average of the measured diameters Respectively.

Air permeability ( cm ³ / cm ² / S)

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

Porosity ( % )

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

Average pore size (탆)

The average pore size of the nonwoven substrate was measured using a Capillary Flow Porometer (Model: CFP-1100-AEL, manufacturer: PMI). The measurement standard was measured for each 10 pieces in accordance with ASTM F 316-03. A circular specimen having a diameter of 1 inch was prepared by cutting the nonwoven filter, and then the pores of the nonwoven support were sufficiently wetted using a Galwick solution having a surface tension of 15.9 dyne / cm.

The tensile strength ( MPa )

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

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 radiation
Condition Single 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 Radial speed (m / min) 12,663 17,450 20,033 18,462 3,995 Thermocompression Temperature (℃) 70 70 70 25 70 Pressure (kgf / cm ² ) 50 50 50 20 50 Nonwoven substrate Weight per unit area
(g / m ² ) 20 20 20 20 20 Thickness (㎛) 23 25 26 43 23 Average fiber diameter
(탆) 2.7 2.3 2.4 2.5 7.6 Air permeability (cm3 / cm2 / S) 27 to 40 28 ~ 41 26-37 70 to 90 65 ~ 83 Porosity (%) 58 63 54 58 46 Average pore size (탆) 8.3 9.8 8.5 14.5 12.5 Tensile Strength (MPa) 21 17 15 5 18

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

Claims (10)

A plurality of fibers having an average diameter of from 0.1 to 7 占 퐉 and comprising polyphenylene sulfide,
Characterized by having a thickness of 20 to 30 탆, an average pore size of 5 to 10 탆, 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 ,
Nonwoven fabric support for ion exchange membrane. The method according to claim 1,
Characterized in that the average diameter of the fibers is 0.5 to 5 [mu] m.
Nonwoven fabric support for ion exchange membrane. The method according to claim 1,
Characterized in that the average diameter of the fibers is between 1 and 3 mu m.
Nonwoven fabric support for ion exchange membrane. The method according to claim 1,
Wherein the polyphenylene sulfide includes p-phenylene sulfide and m-phenylene sulfide as repeating units, and the polyphenylene sulfide includes 95 mol% or more of the p-phenylene sulfide.
Nonwoven fabric support for ion exchange membrane. The method according to claim 1,
Characterized in that the nonwoven fabric support for ion exchange membrane has a thickness of 22 to 28 [mu] m.
Nonwoven fabric support for ion exchange membrane. Melting the polyphenylene sulfide resin;
Extruding the molten polyphenylene sulfide resin;
Discharging the polyphenylresulfide resin through a through hole at a single injection amount of 0.08 to 0.2 g / min / hole by spraying air to the extruded polyphenylene sulfide resin at a pressure of 0.5 to 1.5 kgf / cm ² ;
Collecting fibers formed by discharging the polyphenylene sulfide resin to form a web; And
Compressing the web at a pressure of 10 to 50 kgf / cm < ² > using a roll heated to 40 to 150 DEG C,
A method for manufacturing a nonwoven fabric support for an ion exchange membrane. The method according to claim 6,
The polyphenylene sulfide resin has a melting point of 280 to 290 DEG C,
Wherein the polyphenylene sulfide resin has a melt index (MI) of 100 to 2000 g / 10 min measured at 300 캜 according to ASTM D1238.
A method for manufacturing a nonwoven fabric support for an ion exchange membrane. The method according to claim 6,
Characterized in that the molten polyphenylene sulfide resin is maintained at 290 to 320 DEG C until it is discharged through the above-
A method for manufacturing a nonwoven fabric support for an ion exchange membrane. The method according to claim 6,
Wherein the polyphenylene sulfide resin is discharged at a spinning speed of 4,000 to 21,000 m / min through the spinneret hole.
A method for manufacturing a nonwoven fabric support for an ion exchange membrane. The method according to claim 6,
Wherein the Nip pressure applied to the web in the thermocompression step is 22 to 145 kgf / cm.
A method for manufacturing a nonwoven fabric support for an ion exchange membrane.

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