KR101479760B1 - Multi-Nanofiber filter for excellent heat-resisting property and its manufacturing method - Google Patents

Abstract

A multi-layered nanofiber filter having increased heat resistance of the present invention is manufactured by stacking heat resistant nanofiber in multiple layers on a base material using an electrospinning method in order to resolve low thermal stability, which is a flaw of an existing nanofiber filter. The multi-layered nanofiber filter on the base material is manufactured by the steps of: stacking polyethersulfone nanofibers on a meta-aramid base material; and continuously electrospinning polyimide nanofiber on the polyethersulfone nanofiber. Therefore, the functional filter that has filter efficiency and price competitiveness and can ensure high efficiency and heat resistance is manufactured.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a multi-layer filter material having improved heat resistance,

The present invention relates to a filter material for a multilayer filter for improved heat resistance and a method for producing the same. More specifically, the present invention relates to a multilayer filter material for a filter having improved heat resistance, To a multilayer filter material having improved heat resistance usable at a high temperature such as a power plant, and a method for manufacturing the same.

Generally, a gas turbine used in a thermal power plant sucks and compresses purified air from the outside, injects compressed air into the combustor together with the fuel, mixes the mixed air and fuel, And then the high-temperature and high-pressure combustion gas is injected into the vanes of the turbine to obtain a rotational force.

Since these gas turbines are made up of very precise parts, they are subjected to periodic planned preventive maintenance and air filters are used for the pretreatment to purify the air in the compressor.

The air filter removes foreign substances such as dust and dust contained in the air when the combustion air sucked into the gas turbine is taken in the air and purifies the purified air to supply it to the gas turbine. Is weak at high temperature, and there is a problem that the foreign matter is not removed well.

In addition, most microfibers that are conventionally produced are prepared by spinning, such as melt spinning, dry spinning, wet spinning or the like, in which the polymer solution is forcedly extruded and spun through fine holes by mechanical force. However, the diameter of nanofibers produced in this manner is in the range of about 5 to 500 mu m, and it is difficult to produce nanofiber fibers of 1 mu m or less. Therefore, a filter composed of such a large-diameter fiber can filter contaminant particles having a large diameter, but it is practically impossible to filter nano-sized contaminant particles.

In order to solve the above problems, various methods for fabricating nano-sized fibers (nonwoven fabric) have been developed and used. Among them, a method for forming organic nanofibers includes forming nanostructured materials by block segments, Formation of nanofibers by polymerization using silica catalyst, nanofiber formation by carbonization process after melt spinning, and nanofiber formation by electrospinning of polymer solution or melt.

When the nanofiber filter is fabricated using the nanofibers thus produced, the nanofiber filter has a larger specific surface area than the nanofiber filter having a larger diameter, has flexibility for the surface functional group, and has a nano-sized pore size. Can be efficiently removed.

However, the implementation of the filter using the nanofibers is not easy to control the various conditions for the production because the production cost is low and the production of the filter using the nanofiber is not available at a low price. The present gas turbine, Filters used in furnaces and the like require heat resistance.

In general, a filter is a filtration device for filtering foreign matters in a fluid, and is divided into a liquid filter and an air filter. Among them, the air filter has been developed as a clean room where the biologically harmful substances such as particulate matter, germs and molds, bacteria and the like are completely removed from the air in order to prevent the deterioration of the high- Demand is gradually increasing as the usage area spreads day by day. Cleanroom applications are widely used in semiconductor manufacturing, computer equipment assembly, tape manufacturing, printing painting, hospitals, pharmaceutical manufacturing, food processing plants, agriculture, forestry and fisheries.

The air filter forms a microporous pore layer on the surface of the filter media, thereby preventing the dust from penetrating into the filter media and performing filtration. However, the large particles are formed by the filter cake on the surface of the filter material, and the fine particles pass through the primary surface layer and gradually accumulate in the filter material, thereby blocking the pores of the filter. As a result, large particles and fine particles that block the pores of the filter increase the pressure loss of the filter and deteriorate the life of the filter. In addition, conventional filter media have difficulties in filtering fine particles of nano size smaller than 1 micron there was.

On the other hand, the efficiency of the conventional air filter is measured by the principle that the static electricity is given to the fibrous aggregate constituting the filter filter material and the particles are collected by the electrostatic force. However, in recent years, EN779, the European air filter classification standard, decided to exclude the efficiency of the filter due to the electrostatic effect in 2012, so that the actual efficiency of the conventional filter was lowered by 20% or more. In Europe and the United States, the use of glass fiber is regulated for environmental stability due to the adverse effect of the glass fiber used as the material in the environment.

In order to solve the above-mentioned problems, various methods of manufacturing nano-sized fibers and applying them to filters have been developed. When nanofibers are implemented in a filter, they have a large specific surface area compared to conventional filter media having a large diameter, good flexibility for surface functional groups, and nanoparticle pore size, so that harmful fine particles and gas can be efficiently removed It was.

However, since the production cost of the filter using the nanofibers is large, and it is difficult to control the various conditions for production, it is difficult to mass-produce the filter. Therefore, the filter using the nanofiber is produced at a relatively low cost I can not. Furthermore, filters used in gas turbines, blast furnaces and the like are demanding heat resistance.

The present invention is characterized in that a nozzle block having a nozzle is divided into two sections in the horizontal direction and is provided with a first supply device for supplying the polymer to each divided section and a second supply device for supplying the polymer to the electrode A method of producing a filter material for spinning a device, comprising the steps of: electrospinning a solution prepared by dissolving a heat-resistant polymeric polyethersulfone in an organic solvent in a first feeding device of the electrospinning device to electrospray on the collector to form a polyethersulfone nanofiber A solution prepared by dissolving a polyimide precursor, which is a heat resistant polymer different from the first supply device, in an organic solvent in a second supply device of the electrospinning device is spun onto the polyether sulfone nanofiber to form a polyimide precursor nanofiber And heating the laminated nanofiber layer to imidize the polyimide precursor nanofibers to form polyimide precursor nanofibers, It relates to a process for preparing a multi-layer filter media comprising the step of producing a de nanofiber and thus the polyether multi-layer filter media comprises a polysulfone / polyimide nanofibers produced by.

The present invention utilizes polyether sulfone and polyimide, which are heat-resistant polymers, and thus has excellent heat resistance. By using a continuous electrospinning method, not only the manufacturing process is efficient and cost-competitive, but also nanofibers can be used as a high efficiency filter Do.

1 is a schematic diagram of a multilayer nanofiber filter.
2 is a schematic diagram of a process for a continuous electrospinning apparatus.
3 is a schematic process diagram of a block of an electrospinning device.
4 is a schematic view of a thickness measuring apparatus.
5 is a schematic view of a nozzle block.

A method of preparing a multilayer filter material by electrospinning polyether sulfone and polyimide, which are heat-resistant polymers of the present invention, on a metha-aramid substrate will be described.

In the present invention, the base material of the filter media uses a meta-aramid base material having excellent heat resistance. The meta-aramid is bonded to the amide group at the meta-position. Its strength and elongation are similar to ordinary nylon, but it is very stable against heat. It has the advantages of being light and absorbing somewhat as compared with other heat-resistant materials. This can be suitably used as a filter substrate since the filter stability can be ensured at higher operating conditions.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be noted that like elements in the drawings denote like elements wherever possible. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

2 is a schematic diagram of the configuration of an electrospinning device according to an embodiment of the present invention.

As shown in the drawing, the schematic diagram of the continuous electrospinning device of FIG. 2 is a schematic diagram of a continuous electrospinning device shown in FIG. 2 for supplying a spinning solution main tank (not shown) filled with spinning solution therein and a polymer spinning solution filled in the spinning solution main tank (3) in which a plurality of nozzles (2) in the form of a pin are arranged and a polymer spraying liquid in the spinning liquid main tank (1) is discharged from a metering pump (not shown) A block 20 for accommodating therein a collector 4 spaced apart from the nozzle 2 in order to integrate the spinning solution and a voltage generating device 1 for generating a voltage to the collector, And a case 8 made of a negative conductor.

In the present invention, one spinning liquid main tank (not shown) is provided. However, in the case where the spinning liquid is composed of two or more spinning liquids, two or more main spinning liquid main tanks may be provided, or one spinning liquid main tanks It is also possible to divide into two or more spaces and supply two or more polymer spinning solution filled in each divided space.

Herein, in the present invention, the electrospinning device 10 uses a bottom-up electrospinning device for spraying the spinning liquid in the upward direction.

Meanwhile, in the embodiment of the present invention, a bottom-up electrospinning device for spraying the spinning solution in the upward direction with the electrospinning device is used, but a top-down electrospinning device for spraying the spinning solution in the downward direction can be used. A combined electrospinning device in which the device is used together may be used, but is not limited thereto.

With the above structure, the electrospinning apparatus 10 is configured such that the spinning liquid filled in the spinning liquid main tank in the block 20 continuously flows into the plurality of nozzles 2 to which a high voltage is applied through the metering pump And the spinning solution of the polymer supplied to the nozzle 2 is radiated and focused on the collector 13 having a high voltage through the nozzle 2 to form nanofibers (not shown) The fibers are laminated to produce a filter.

In the front end of the electrospinning device 10, there is provided a feed roller 11 for feeding a long sheet on which nanofibers are laminated by spraying a polymer spinning solution in each block 20, Up roller 12 for winding the sheet.

In the present invention, the filter sheet 5 is used as a long sheet and the polymer spinning solution is sprayed on the filter substrate 5 to form nanofibers .

In the embodiment of the present invention, the filter substrate 5 is used as a long sheet, but a release or nonwoven fabric may be used, but the present invention is not limited thereto.

That is, one side and the other side of the filter base 5 used as a long sheet in the present invention are wound around a feeding roller 11 provided at the front end of the electrospinning apparatus 10 and a winding roller 12 provided at the rear end .

On the other hand, the electrospinning device of each block 20 is installed in the advancing direction (a) of the radiation with respect to the collector 4. An auxiliary belt 6 is provided between each of the collectors 4 and the filter substrate 5 and is integrated with each of the collectors 4 through the auxiliary belts 6 to form nano- (5) is transported in the horizontal direction. That is, the auxiliary belt 6 rotates in synchronization with the feed speed V of the filter base material, and has the auxiliary belt roller 7 for driving the auxiliary belt 6. The auxiliary belt roller 7 is an automatic roller having at least two frictional forces. Since the auxiliary belt 6 is provided between the collector and the filter substrate 5, the filter substrate 5 is smoothly conveyed without being attracted to the collector to which the high voltage is applied.

The spinning liquid filled in the spinning liquid main tank in the block 20 of the electrospinning device 10 is sprayed onto the filter substrate 5 located on the collector 4 through the nozzle 2 And the spraying liquid sprayed on the filter substrate 5 is accumulated to form a laminate of nanofibers. The auxiliary belt 6 is driven by the rotation of the auxiliary belt rollers 7 provided on both sides of the collector 4 to transfer the filter base material 5 to the blocks 20 at the rear end of the electrospinning device 10 ) So as to repeatedly perform the above-described process.

5, the nozzle block 3 includes a plurality of nozzles 2 arranged upward from the discharge port, a tube 43 formed of a row of nozzles 2, a spinning solution storage tank 44, And a spinning liquid circulating pipe (45).

First, the spinning liquid storage tank 44 connected to the spinning liquid main tank to receive and store the spinning solution is connected to the nozzle 2 through the spinning liquid circulating pipe 45 by the metering pump (not shown) And the spinning solution is supplied to the spinning solution. Here, the tube 43 having a plurality of nozzles 2 in a row is supplied with the same spinning solution from the spinning solution storage tank 44, but a plurality of spinning solution storage tanks are provided, It is also possible to supply a spinning liquid of different kinds to each of the tubes 43 and radiate them.

When radiated from the discharge port of the plurality of nozzles 2, the overflowed solution is moved to the overflow solution storage tank 41. The overflow solution storage tank 41 is connected to a spinning solution main tank (not shown) so that the overflow solution can be reused for spinning.

The main controller 30 controls the amount of spinning solution supplied to the nozzle block 3 and controls the voltage of the voltage supply device 1 for each block 20 , And the feed rate (V) of each block can be controlled according to the thickness of the nanofiber and the filter substrate measured by the thickness measuring device (9).

The thickness measuring device 9 of the present invention is disposed opposite the filter substrate 5 located at the front end and the rear end of the block 20 and having the nanofibers stacked therebetween. The thickness measuring device 9 is connected to the main controller 30 for adjusting the radiation conditions of the electrospinning device 10 so that the thickness measuring device 9 measures the thickness of the nanofiber and the filter substrate 5 The main controller 30 controls the conveying speed V of each block 20 on the basis of one value. For example, if the deviation amount of the thickness measurement value of the discharged nanofibers for each block 20 in the electrospinning is thinly measured, the conveyance speed V of the block 20 located at the rear end is decreased, . In addition, the main controller 30 increases the discharge amount of the nozzle block 3 and adjusts the intensity of the voltage of the voltage generator 1 to increase the discharge amount of the nanofibers per unit area to uniformly control the thickness of the nanofibers It is possible.

The thickness measuring device 9 is provided with a thickness measuring part consisting of a pair of ultrasonic longitudinal waves and a transverse wave measuring method for measuring the distance from the nanofiber on which the nanofibers are laminated to the filter base 5 by an ultrasonic measuring method , And the thickness of the nanofiber and the filter substrate 5 is calculated on the basis of the distance measured by the pair of ultrasonic measuring devices, as shown in FIG. More specifically, the ultrasonic longitudinal wave and the transverse wave are projected to the filter substrate 5 on which the nanofibers are laminated, and the time during which each ultrasonic signal of the longitudinal wave and the transverse wave reciprocates on the filter base 5, From the predetermined arithmetic expression using the propagation time of the measured longitudinal waves and transverse waves and the temperature constants of longitudinal and transverse wave propagation speeds and propagation speeds at the reference temperature of the filter substrate 5 on which the nanofibers are stacked, It is a thickness measuring device that calculates the thickness of a dead body.

The electrospinning device 10 used in the present invention is configured such that when the thickness deviation P of the nanofiber is less than a predetermined value, the feed velocity V is not changed from the initial value, , It is possible to control the feed speed V to be changed from the initial value, so that it becomes possible to simplify the control of the feed speed V by the feed speed V control device. In addition to the control of the conveying speed V, the discharge amount and the voltage intensity of the nozzle block 3 can be adjusted. When the thickness deviation P is less than the predetermined value, the discharge amount of the nozzle block 3 and the intensity of the voltage It is possible to control the amount of discharge and the intensity of the voltage of the nozzle block 3 to be changed from the initial value when the deviation amount P is equal to or larger than the predetermined value without changing the initial value, It becomes possible to simplify control of the discharge amount and the intensity of the voltage.

The block 20 of the electrospinning device 10 is divided into a front end block 20a located at the front end portion and a rear end block 20b located at the rear end portion according to the radiation position. In the embodiment of the present invention, the number of blocks is limited to two, but it is also possible to have two or more blocks.

In the present invention, the same polymeric spinning solution is radiated in each of the blocks 20a and 20b, but it is also possible to spin different kinds of polymer spinning solutions for each block, and two or more different It is also possible that the polymer spinning solution is radiated. When at least two different kinds of spinning solutions are supplied and radiated for each block 20, it is possible that the polymer nanofibers of different kinds are successively laminated.

In addition, it is also possible to manufacture hybrid nanofibers by constituting two or more polymer types of the spinning solution to be used.

It is also possible to continuously laminate nanofibers having different fiber thicknesses by varying the intensity of the voltage applied to each block 20. In a block 20, the number of nozzles 2 located in the nozzle block 3 It is also possible to form a hybrid nanofiber in which two or more polymers are electrospun and laminated.

On the other hand, a laminating device 19 is provided at the rear end of the electrospinning device 10 of the present invention. The production of the nanofibers is finished through the heating device 19 in which the nanofibers are deposited, and the heating temperature may be set differently according to the type of the meta-aramid base or the nanofiber. Is heated at 150 to 350 DEG C for imidization. Thus, the laminating device 19 applies heat and pressure, and the filter base material on which the nanofibers are laminated, that is, the nanofiber filter is wound on the winding roller 12 to form a nanofiber filter.

The heat-resistant polymer resin is composed of a polymer having a melting point of 180 ° C or more so that the nanofibers do not collapse due to melting even when the temperature is continuously increased. For example, the heat-resistant polymer resin constituting the heat-resistant polymer microfine fiber layer may be selected from the group consisting of polyamide, polyimide, polyamideimide, poly (meta-phenylene isophthalamide), polysulfone, polyetherketone, polyetherimide, , Aromatic polyesters such as polytrimethylene terephthalate and polyethylene naphthalate, and polyphosphates such as polytetrafluoroethylene, polydiphenoxaphospazene, and polybis [2- (2-methoxyethoxy) phosphazene] Such as polyurethane copolymers including polyglycerol, polyglycerol, polyglycerol, polyglycerol, polyglycerol, polyglycerol, polyetherketone, polyglycerol, polyglycerol, polyglycerol, polyglycerol and polyetherurethane; cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate and the like. A resin with no melting point refers to a resin that burns without experiencing a melting process even when the temperature rises above 180 ° C. The heat-resistant polymer resin used in the present invention is preferably soluble in an organic solvent for ultra-fine fiberization such as electrospinning.

Polyethersulfone (PES) is an amber, transparent, amorphous resin.

That is, since the polyether sulfone (PES) is amorphous, there is little deterioration of physical properties due to temperature rise, and the temperature dependence of the flexural modulus is very small, so that it hardly changes at 100 to 200 ° C. The load-strain temperature is 200 to 220 占 폚, and the glass transition temperature is 225 占 폚. In addition, the creep resistance up to 180 占 폚 is the most excellent among the thermoplastic resins, and has the characteristic of being resistant to hot water and steam at 150 to 160 占 폚. Therefore, polyether sulfone is used for optical disks, magnetic disks, electric and electronic fields, hydrothermal fields, automobile fields, heat-resistant paints and the like due to the above characteristics.

Polyethersulfone has properties of improving heat resistance and thermal dimensional stability, and is not difficult to dissolve in a solvent. The molecular weight of the polyethersulfone is in the range of 8,000 to 200,000 in viscosity average molecular weight. If the viscosity average molecular weight is less than 8,000, the molded article is extremely undesirable even for a resin composition article. On the other hand, if it exceeds 200,000, the melt fluidity is deteriorated and it becomes difficult to form a good molded article. A preferred viscosity is 400 to 1,200 cps. Examples of the solvent include dichloromethane, chloroform, tetrahydrofuran, methanol, ethanol, butanol, toluene, xylene, acetone, ethyl acetate, dimethylformamide, N-methyl-2-pyrrolidinone, dimethylacetamide But are not limited to these.

The polyimide is prepared by preparing a spinning solution in which a polyimide precursor is dissolved in a mixed solvent of THF / DMAc (THF / DMAc), electrospinning the precursor, and then imidizing the precursor .

In the present invention, poly (amic acid) (PAA) is synthesized and dissolved in a mixed solvent of tetrahydrofuran (THF) and dimethylacetamide (DMAc) (THF / DMAc) , Polyimide nanofibers using electrospinning, and polyimide (PI) nanofibers through imidization can be prepared.

The polyimide is prepared by a two-step reaction.

In the first step, polyamic acid is prepared by adding dianhydride to a reaction solution in which diamine is dissolved. In order to increase the degree of polymerization, the reaction temperature, the water content of the solvent, And purity control. As the solvent used in this step, organic polar solvents such as dimethylacetamide (DMAc), dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) are mainly used. Examples of the anhydride include pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic anhydride (4,4'-oxydiphthalic anhydride) anhydride, ODPA, biphenyltetracarboxylic dianhydride (BPDA), and bis (3,4'-dicarboxyphenyl) dimethylsilane dianhydride (SIDA) May be used. Examples of the diamine include 4,4'-oxydianiline (ODA), p-penylene diamine (p-PDA) and ortho- penylenediamine, o-PDA) may be used.

Reaction 1. Preparation of polyamic acid

The second step is the dehydration and ring-closing reaction step of producing polyimide from polyamic acid as the following four methods.

In the re-impregnation method, a polyamic acid solution is added to an excessive amount of a poor solvent to obtain a solid polyamic acid. As the re-precipitation solvent, water is mainly used, but toluene or ether is used as a co-solvent.

The chemical imidization method is a method of chemically imidizing the reaction using a dehydration catalyst such as acetic anhydride / pyridine, and is useful in the production of a polyimide film.

The thermal imidation method is a method in which the polyamic acid solution is heated to 150 to 200 ° C to thermally imidize the resin. In the simplest process or crystallization degree, the amine exchange reaction occurs when the amine type solvent is used, have.

In the isocyanate method, a diisocyanate is used instead of a diamine as a monomer, and when the monomer mixture is heated to a temperature of 120 ° C or higher, a polyimide is produced while CO 2 gas is generated.

Reaction formula 2. Preparation of polyimide

Hereinafter, a method for producing filter media using polyether sulfone and polyimide as the heat-resistant polymer resin will be described in detail.

First, polyethersulfone is dissolved in an organic solvent to prepare a first spinning solution. The first spinning liquid is supplied to the spinning liquid main tank of the electrospinning device 10 and is supplied to the spinning liquid main tank. The first spinning liquid is supplied to a plurality of nozzle blocks 3 In a constant amount in the nozzle 2 of the nozzle.

The polyethersulfone solution supplied to each of the nozzles 2 is injected onto the meta-aramid substrate 5 while being radiated and focused on the collector 4 with a high voltage applied thereto through the nozzle 2, . The substrate on which the polyether sulfone nanofibers are laminated in the front end block 20a of the electrospinning device 10 is composed of a feed roller 11 operated by driving of a motor (not shown) Is transferred from the front end block 20a into the rear end block 20b by the rotation of the auxiliary belt 6 driven by the rotation of the auxiliary belt 6. [

The second spinning solution supplied to the main tank in which the polyimide precursor solution is injected in the rear end block 20b is continuously quantified in the plurality of nozzles 2 of the nozzle block 3 to which a high voltage is applied through the metering pump .

At this time, the front end block 20a is referred to as a first feeding device and the rear end block 20b is referred to as a second feeding device.

More specifically, the polyethersulfone spinning solution is stored in the first main tank for storing the spinning solution for electrospinning of the present invention, and the spinning solution of the polyimide precursor resin is stored in the second main tank. The supply device is designed to have a closed cylindrical shape as a whole, and serves to supply the spinning solution continuously injected from the spinning liquid tank for each section. The nozzle block is divided into two sections, and the first and second supply devices are provided in the respective sections, and the spinning liquids each contain a polyether sulfone solution in the first supply device and a solution of the polyimide precursor resin in the second supply device use.

The filter formed by stacking the polyether sulfone nanofibers and the polyimide nanofibers on the produced meta-aramid base material is an air filter of a gas turbine into which air having a high temperature flows in the air inlet direction. The life span can be prolonged.

The length of the section defined by the nozzle block can be adjusted according to the thickness of each layer constituting the filter media.

The mechanical properties such as the thickness of the polymer membrane, the diameter of the fiber, and the shape of the fiber can be arbitrarily controlled by controlling the electrospinning process conditions such as the intensity of the applied voltage, the kind of the polymer solution, the viscosity of the polymer solution, have.

The preferred electrospinning process conditions are such that when the spinning solution transferred to the spinning liquid supply tube is discharged to the collector through the multi tubular nozzle to form the fibers, the nanofibers electrospun from the multi-tubular nozzles are ejected from the air- When it spreads widely and is collected on the collector, the collecting area becomes wider and the density of the collecting becomes uniform. The excess flushing liquid which is not fibrous in the tubular nozzle is collected in the overflow removing nozzle and then moved to the flushing liquid supply plate through the temporary storage plate of the overflow liquid.

When manufacturing nanofibers, it is preferable that the speed of air in the air supply nozzle is 0.05 m to 50 m / sec, more preferably 1 to 30 m / sec. If the velocity of the air is less than 0.05 m / sec, the collecting area of the nanofibers is low and the collecting area is not greatly improved. If the velocity of the air exceeds 50 m / sec, the velocity of the air is too fast, And more seriously, it is attached to the collector in the form of a thick thread rather than a nanofiber, thereby causing a problem that the forming ability of the nanofiber is remarkably lowered.

In addition, the spinning solution which is excessively supplied to the top of the nozzle block is forcibly transferred to the spinning liquid main tank by the spinning solution discharging device.

At this time, in order to promote the formation of the fiber by the electric force, a voltage of 1 kV or more, more preferably 20 kV or more, generated by the voltage generator is applied to the conductive plate and collector provided at the lower end of the nozzle block. It is more advantageous in terms of productivity to use an endless belt as the collector. The collector preferably reciprocates a predetermined distance in the left and right directions to uniform the density of the nanofibers.

When the nanofibers formed on the collector are wound on the winding roller through the web supporting roller, the manufacturing process of the nanofibers is completed.

The manufacturing apparatus can increase the collecting area to uniform the density of the nanofibers and effectively prevent the droplet phenomenon, thereby improving the quality of the nanofibers and enhancing the fiber-forming effect by the electric force, Can be mass produced. In addition, the width and thickness of the nanofibers and filaments can be freely changed and adjusted by arranging the nozzles composed of a plurality of pins in block form.

In addition, when the heat-resistant polymer is spun as described above, it is most preferable to spin the polymer under environmental conditions of a temperature range of 30 to 40 DEG C and a humidity of 40 to 70% depending on the polymer material.

In the present invention, the diameter of the nanofiber forming the multi-layer filter media is preferably from 30 to 1,000 nm, more preferably from 50 to 500 nm.

The porosity of the multi-layer filter media is preferably from 40 to 80%, and as the fiber diameter is smaller, the pore size becomes smaller and the pore size distribution becomes smaller. Further, as the diameter of the fibers is smaller, the specific surface area of the fibers is increased, so that the efficiency of filtering small particulates becomes larger.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

[Example 1]

In the first section, a polyether sulfone electrospun solution (Dope) was prepared by dissolving a polyether sulfone having a viscosity of 1,200 cps and a solid content of 20% by weight in dimethylacetamide (DMAc) Polyamic acid dope is prepared by dissolving 100,000 polyamic acid (PAA) in a mixed solvent of tetrahydrofuran (THF) and dimethylacetamide (DMAc) (THF / DMAc) . A polyether sulfone nanofiber having a thickness of 3 m was formed on a meta-aramid substrate having a basis weight of 30 gsm under the conditions of a distance between the electrode and the collector of 40 cm, an applied voltage of 15 kV, a spinning liquid flow rate of 0.1 mL / h, a temperature of 22 캜 and a humidity of 20% And the collector was moved at a constant speed to form a nanofiber layer by spinning the polyamic acid nanofibers so that the thickness was 3 μm on the upper layer of the polyether sulfone nanofibers in the two sections and then heated at 200 ° C. to form the polyamic acid nanofiber, Imidized with nanofibers to form a multi-layer filter media.

[Example 2]

In the first section, a polyethersulfone electrospun solution (Dope) was prepared by dissolving a polyether sulfone having a viscosity of 1,200 cps and a solid content of 10% by weight in dimethylacetamide (DMAc), and in the second section, a weight average molecular weight Polyamic acid dope is prepared by dissolving 100,000 polyamic acid (PAA) in a mixed solvent of tetrahydrofuran (THF) and dimethylacetamide (DMAc) (THF / DMAc) . A polyether sulfone nanofiber having a thickness of 1 m was formed on a meta-aramid substrate having a basis weight of 30 gsm under the conditions of a distance of 40 cm between the electrode and the collector, an applied voltage of 15 kV, a spinning liquid flow rate of 0.1 mL / h, a temperature of 22 캜 and a humidity of 20% The collector was moved at a constant speed to spin the polyamic acid nanofibers to a thickness of 5 μm on the upper layer of the polyether sulfone nanofibers to form a nanofiber layer. The polyamic acid nanofibers were then heated at 200 ° C. to form polyimide nanofibers Imidized with nanofibers to form a multi-layer filter media.

[Example 3]

In the first section, a polyether sulfone electrospun solution (Dope) was prepared by dissolving a polyether sulfone having a viscosity of 1,200 cps and a solid content of 20% by weight in dimethylacetamide (DMAc) Polyamic acid dope is prepared by dissolving 100,000 polyamic acid (PAA) in a mixed solvent of tetrahydrofuran (THF) and dimethylacetamide (DMAc) (THF / DMAc) . Under the electrospinning conditions of a distance of 40 cm between the electrode and the collector, an applied voltage of 15 kV, a flushing liquid flow rate of 0.1 mL / h, a temperature of 22 캜 and a humidity of 20%, a polyethersulfone nanofiber having a thickness of 5 탆 was placed on a meta-aramid base And the collector was moved at a constant speed to form a nanofiber layer by spinning the polyamic acid nanofiber on the upper layer of the polyethersulfone nanofibers in a thickness of 1 μm, followed by heating at 200 ° C. to form the polyamic acid nanofiber, Imidized with nanofibers to form a multi-layer filter media.

[Example 4]

In the first section, a polyether sulfone electrospun solution (Dope) was prepared by dissolving a polyether sulfone having a viscosity of 1,200 cps and a solid content of 20% by weight in dimethylacetamide (DMAc) Polyamic acid dope is prepared by dissolving 100,000 polyamic acid (PAA) in a mixed solvent of tetrahydrofuran (THF) and dimethylacetamide (DMAc) (THF / DMAc) . A polyether sulfone nanofiber having a thickness of 3 μm was applied to a meta-aramid base having a basis weight of 30 gs at an applied voltage of 12 kV under a condition of a distance between the electrode and the collector of 40 cm, a spinning solution flow rate of 0.1 mL / h, a temperature of 22 ° C. and a humidity of 20% A nanofiber having a fiber diameter of 400 nm was formed and the collector was moved at a constant speed to spin the polyamic acid nanofiber at an applied voltage of 20 kV so as to have a thickness of 3 탆 on the upper layer of the polyether sulfone nanofiber, And then heated at 200 ° C to imidize the polyamic acid nanofibers with polyimide nanofibers to form a multi-layer filter material.

[Example 5]

In the first section, a polyether sulfone electrospun solution (Dope) was prepared by dissolving a polyether sulfone having a viscosity of 1,200 cps and a solid content of 20% by weight in dimethylacetamide (DMAc) Polyamic acid dope is prepared by dissolving 100,000 polyamic acid (PAA) in a mixed solvent of tetrahydrofuran (THF) and dimethylacetamide (DMAc) (THF / DMAc) . A polyether sulfone nanofiber having a thickness of 3 μm was applied to a meta-aramid base having a basis weight of 30 gs at an applied voltage of 20 kV under a condition of a distance between the electrode and the collector of 40 cm, a spinning solution flow rate of 0.1 mL / h, a temperature of 22 ° C. and a humidity of 20% The nanofibers having a fiber diameter of 100 nm were formed and the collector was moved at a constant speed to spin the polyamic acid nanofibers at an applied voltage of 12 kV so as to have a thickness of 3 탆 on the upper layer of the polyether sulfone nanofibers. And then heated at 200 ° C to imidize the polyamic acid nanofibers with polyimide nanofibers to form a multi-layer filter material.

[Comparative Example 1]

Polyethersulfone having a viscosity of 1,200 cps and a solid content of 20% by weight is dissolved in dimethylacetamide (DMAc) to prepare a polyether sulfone dopant. Under the condition of the distance between the electrode and the collector being 40 cm, the applying voltage of 15 kV, the spinning liquid flow rate of 0.1 mL / h, the temperature of 22 캜 and the humidity of 20%, 6 탆 thick polyethersulfone nanofibers were placed on a meta-aramid substrate having a basis weight of 30 gsm To form a filter media.

- Heat resistance evaluation -

Examples 1 to 5 and Comparative Example 1 were heat-pressed at a temperature of 200 DEG C and a linear pressure of 50 kg / cm to confirm the heat resistance.

- Filtration efficiency measurement -

The DOP test method was used to measure the efficiency of the fabricated nanofiber filter. The DOP test method measures the dioctyl phthalate (DOP) efficiency with an automated filter analyzer (AFT) of TSI 3160 from TSI Incorporated and measures the permeability, filter efficiency and differential pressure of the filter media material .

The automation analyzer is a device that measures DOP on a filter sheet by making particles of a desired size and is a very important device for a high efficiency filter.

The DOP filtration efficiency (%) is defined as:

DOP transmittance (%) = 1 - 100 (DOP concentration downstream / DOP concentration upstream)

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Fiber shrinkage
(%) 3.0 2.6 3.5 3.0 3.0 5.0

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 0.35um
DOP% 95 95 95 99 99 85

As described above, the multi-layered nanofiber filter manufactured by the embodiment of the present invention has higher heat shrinkage and filtration efficiency than the comparative example.

1, 1a, 1b: voltage generating device 2: nozzle
3: Nozzle block 4: Collector
5: substrate 6: auxiliary belt
7: Auxiliary belt roller 8: Case
9: thickness measuring device 10: electrospinning device
11: feed roller 12: take-up roller
19: laminating apparatus 20, 20a, 20b: block
30: main control device 41: overflow solution storage tank
43: tubular body 44: spinning liquid storage tank
45: Fluid distribution pipe
200: polyimide nanofiber
300: polyethersulfone nanofiber

Claims (5)

A nozzle block provided with a nozzle is divided into two sections toward the horizontal direction and is provided with a first supply device for supplying the polymer to each divided section and an electrospinning device for radiating the polymer on the collector, In the filter material manufacturing method of the present invention,
Forming a polyethersulfone nanofiber layer by electrospinning a spinning solution prepared by dissolving polyether sulfone having excellent heat resistance in an organic solvent in a first feeding device of the electrospinning device;
Depositing a polyimide precursor nanofiber on the polyether sulfone nanofiber by spinning a spinning solution prepared by dissolving a polyimide precursor, which is a heat resistant polymer, in an organic solvent, into a second supply device of the electrospinning device;
Heating the laminated nanofibers to imidize the polyimide precursor nanofibers to the polyimide nanofibers;
Wherein the electrospinning is a bottom-up electrospinning method.
The method according to claim 1,
Wherein the polyimide precursor is poly (amic acid) (PAA) as the polyimide precursor.
The method according to claim 1,
Wherein the substrate is made of meta-aramid.
delete A multi-layer filter material made of a polyethersulfone / polyimide nanofiber and having improved heat resistance, produced by the manufacturing method according to any one of claims 1 to 3.

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