KR102169194B1 - Core-shell filler and method for preparing core-shell filler - Google Patents

Abstract

Disclosed is a method for manufacturing a core-shell filler having a dual structure of a core made of metal and a shell made of carbon fiber by an electrospinning method including a double nozzle. The method of manufacturing the core-shell filler includes: (a) preparing a polyacrylonitrile solution for electrospinning; (b) preparing a metal solution for electrospinning; (c) introducing the polyacrylonitrile solution for electrospinning and the metal solution for electrospinning into a double nozzle of an electrospinning device; (d) spinning the polyacrylonitrile solution for electrospinning and the metal solution for electrospinning by electrospinning to prepare a core-shell structured composite fiber; And (e) crushing the core-shell structured composite fibers to prepare a core-shell filler made of metal/carbon fibers.

Description

Core-shell filler and method for preparing core-shell filler}

The present invention relates to a core-shell filler and a method for manufacturing the same, and more particularly, a dual structure of a core made of metal and a shell made of carbon fiber by an electrospinning method including a double nozzle It relates to a core-shell filler and a method of manufacturing the same.

Recently, various technologies related to a filler having a dual structure have been developed. Among them, PAN (poly acrylo nitrile)-PC (poly carbonate), PAN-PS (poly stylene), PCL (poly capro lactone)-gelatin, PVP (poly vinyl pyrrolidone)-PLA (poly lactic acid) and PEO (poly Ethylene oxide)-PEG-b-PLA (block copolymer of polyethylene glycol and polylactic acid) is developing a double-structured fiber in which a high-conductivity polymer is applied to the core, with a hollow structure (hollow structure). ) Fiber is applied to drug delivery systems, fuel cell membranes, catalysts, and sensors, but its application to fields related to electromagnetic interference (EMI) shielding is experiencing difficulties due to the resistance problem of carbon materials. When only carbon fiber is used for EMI shielding, conductivity can be improved by coating nickel (Ni), copper (Cu), silver (Ag), and carbon nanotubes (CNT) on the surface of the carbon fiber. In addition, in the case of preventing oxidation of the core-shell structure, a structure is formed on the surface of the core with a metal having a low oxidation degree as a shell or a polymer such as poly vinyl alcohol (PVA) or PVP.

A typical core-shell structure has problems in conductivity and reliability. In the case of mixing metal nanoparticles and carbon fibers (blending type), a metal with a high degree of oxidation (oxidizing property) is mixed with an antioxidant organic material such as PVP and PVA. When applied as a (shell), organic matter is easily decomposed by a high-temperature heat treatment process. Resistance increases due to oxidation when metal nanoparticles such as copper (Cu), nickel (Ni), and silver nanowire (Ag nono wire) are used, and when 20% or more of metal is coated on the oxidizing metal, Resistance increases due to increased cost and oxidation of areas that are not coated or less, and when applied as a conductive ink, it is difficult to prevent oxidation when the drying temperature is 200 ℃ or higher, and polymers at high glass transition temperatures of 300 ℃ or higher ( EP resin) It is also difficult to prevent oxidation during the extrusion process. In addition, when the metal nanoparticles and carbon fibers are mixed (blending type), conductivity and reliability are lowered due to insufficient necking between conductive metal powders (conductors), and when the amount of nanopowder added to improve necking increases, the specific surface area As it increases, cracks occur and the durability of the product decreases. In the usual pressure injection process, addition of a conductive filler and a filler (reinforcing material) for enhancing physical properties is performed. On the other hand, when a metal powder is used as a shell to secure conductivity, when an uncoated part exists due to the coating method between powders, the metal in the core part with high oxidation degree is easily oxidized, and the metal powder is In the case of thick coating, the cost increases due to the increase in the amount of metal used. ('Production and application of double structure, hollow structure and porous nanofibers by electrospinning'-Polymer Science and Technology Vol. 19 No. 1 (2008.02), colloid interface sci. (2007, 311, 417-424.), Patent disclosure 10-210-006681, patent registration 10-0830871, patent registration 10-0781586).

In addition, Korean Patent Laid-Open No. 10-2012-48944 discloses a heterogeneous nanowire composed of an intermetallic compound or alloy core and a carbon nanotube shell and a method for synthesizing the same.The core focuses on functionality rather than conductivity, and the shell is made of carbon. It is characterized by using a gas, and is to manufacture a double wire by applying carbon nanotubes. In addition, Korean Patent Publication No. 10-2011-99475 discloses a method for preparing a gradient nanofiber material using a concentric multi-nozzle and a gradient nanofiber prepared by the method, and uses a polymer as a core and uses a metal oxide solution. Can be added according to. In addition, U.S. Patent Publication No. 2006-0213829 discloses the production of submicron-diameter fibers by electrospinning two fluids, and is characterized in that a core and a shell are composed of only polymers.

An object of the present invention is to provide a core-shell filler capable of increasing conductivity and preventing oxidation of a conductive metal for shielding electromagnetic waves, and a method of manufacturing the same.

Another object of the present invention is to provide a core-shell filler using an electrospinning method including a double nozzle and a manufacturing method thereof.

In order to achieve the above object, the present invention, (a) preparing a polyacrylonitrile solution for electrospinning; (b) preparing a metal solution for electrospinning; (c) introducing the polyacrylonitrile solution for electrospinning and the metal solution for electrospinning into a double nozzle of an electrospinning device; (d) spinning the polyacrylonitrile solution for electrospinning and the metal solution for electrospinning by electrospinning to prepare a core-shell structured composite fiber; And (e) crushing the core-shell structured composite fibers to produce a core-shell filler made of metal/carbon fibers.

In addition, the present invention is made of particles selected from the group consisting of metal in powder form, metal oxide, and graphene oxide, and has a cylindrical core extending in the longitudinal direction. ); And a shell made of carbon fiber and surrounding the core-shell filler.

The core-shell filler and its manufacturing method according to the present invention use carbon fibers and conductive metals to prevent oxidation and maintain conductivity of metals with high oxidation degree by applying a core-shell structure, and to improve conductivity and strength. , By preventing cracks due to an increase in filler, it can prevent the durability of the product from deteriorating (at the same content). In particular, by applying carbon fibers that have inherent conductivity and are excellent in heat, moisture resistance (0.05% or less), chemical resistance, and chemical resistance to the shell outside of the core-shell structure, a common core-shell The problem of reducing conductivity and reliability, which was a problem of the structure, has been improved, and it can be applied to a high-temperature extrusion process, and the cost can be lowered by using a carbon material. In addition, 10 to 50% of the core-shell filler may be added, and necking between powders within the shell is also excellent, so that problems that were encountered in a conventional pressure injection process can be improved. In addition, when the core-shell filler to which the flameproofing and carbonizing processes are applied using an electrospinning method is manufactured, not only the conductivity of the carbon fiber (shell) is improved, but also the conductivity of the metal (core) is reduced.

1 is a flowchart illustrating a method of manufacturing a core-shell filler according to an embodiment of the present invention.
Figure 2 is a schematic diagram of an electrospinning device for implementing a method of manufacturing a core-shell filler according to an embodiment of the present invention.
3 is a schematic diagram of a core-shell filler according to an embodiment of the present invention.
4 is a surface view (2-1 to 2-4) of an electromagnetic wave shielding sheet specimen to which a core-shell filler is applied and a surface view (2-5 and 2-6) of an electromagnetic wave shielding sheet specimen to which only carbon fiber is applied according to the present invention. ).

Hereinafter, the present invention will be described in detail.

The present invention is to manufacture a filler (filler) to be applied to the film ink, sheet, electronic products and automobile housings related to EMI shielding, and is by a method of manufacturing a highly conductive nanofiber having a core-shell structure.

The method of manufacturing a core-shell filler according to the present invention includes: (a) preparing a polyacrylonitrile solution for electrospinning, (b) preparing a metal solution for electrospinning, (c) the polyacrylonitrile for electrospinning Injecting an acrylonitrile solution and a metal solution for electrospinning into the double nozzle of an electrospinning device, (d) spinning the polyacrylonitrile solution for electrospinning and the metal solution for electrospinning by electrospinning to core-shell And (e) crushing the core-shell structured composite fibers to produce a core-shell filler made of metal/carbon fibers, and if necessary, the (d) step It may further include a step of performing a flame-resistant treatment of the composite fiber of the core-shell structure prepared in and carbonization treatment of the flame-resistant composite fiber.

1 is a flowchart illustrating a method of manufacturing a core-shell filler according to an embodiment of the present invention. With reference to FIG. 1, a method of manufacturing the core-shell filler will be described in detail. First, a method of preparing the electrospinning polyacrylonitrile solution prepared with acrylonitrile, acrylic comonomer, initiator, dispersion medium, and solvent will be described. Acrylonitrile and methacrylic acid purified with sodium hydroxide will be described. Mix the comonomer (S 10, for example, the comonomer, methyl acrylate, methyl methacrylate, mathacrylic acid, vinylacetate, itaconic acid, sodium methallyl sulphonate, etc.). At this time, the acrylonitrile and the acrylic comonomer are 75 to 90% by weight and 10 to 25% by weight, preferably 80 to 90% by weight and 10 to 20% by weight, more preferably 85 to 90% by weight and It is 10 to 15% by weight, for example, the acrylonitrile:acrylic comonomer may have a weight ratio of 90:10, 85:15. The mixture of acrylonitrile and acryl-based comonomer is 1 to 3 parts by weight of monomeric acrylonitrile, preferably 2 to 2.5 parts by weight of an initiator such as AIBN, and dimethylformamide (DMF) and distilled water from 1 to 1, respectively. 40% by weight and 60 to 99% by weight, preferably 1 to 20% by weight and 80 to 99% by weight, more preferably 10 to 20% by weight and 80 to 90% by weight, for example, the dimethylformamide (DMF): distilled water, after dissolving in a dispersion medium consisting of a weight ratio of 15:85, 20:80, etc. (S 12), under a nitrogen stream 50 to 80 °C, preferably 60 to 75 °C, more preferably Polyacrylonitrile (PAN) is prepared by polymerizing the mixture at 65 to 70° C. for 1 to 5 hours, preferably 2 to 4 hours, and more preferably 2.5 to 3.5 hours (S 14). The polymerization is controlled to a weight average molecular weight (Mw) of 100,000 to 500,000, preferably 110,000 to 200,000, more preferably 120,000 to 160,000 for the conditions of the electrospinning process. Next, after maintaining the temperature of a solvent such as DMF at 60 to 90° C., preferably 70 to 80° C., the prepared polyacrylonitrile (PAN) was added in portions several times, and 2 to 4 hours, Preferably, it is dissolved for 2.5 to 3.5 hours to prepare a polyacrylonitrile (PAN) solution for electrospinning (S 16). At this time, the solvent such as DMF and polyacrylonitrile (PAN) are respectively 75 to 95% by weight and 5 to 25% by weight, preferably 85 to 95% by weight and 5 to 15% by weight, more preferably 88 To 92% by weight and 8 to 12% by weight, for example, the solvent: polyacrylonitrile (PAN) may have a weight ratio such as 90:10, 85:15.

Next, a method of preparing the electrospinning metal solution prepared with a metal precursor, a stabilizer and a solvent is described, in a solvent such as diethylene glycol (DEG), which is 1 to 20 mL, preferably 5 to 15 mL, 0.01 A metal solution for electrospinning is prepared by dissolving to 0.5 mol, preferably 0.05 to 0.2 mol of a metal precursor and 0.1 to 0.5 mol, preferably 0.2 to 0.4 mol of a stabilizer (S 20 ). In addition, 0.1 to 0.5 mol, preferably 0.2 to 0.4 mol of a reducing agent may be added and dissolved in the electrospinning metal solution to prepare a metal powder (S 22).

Examples of the metal precursor, CuSO ₄ , CuCl ₂ , Cu(NO ₃ ) ₂ , CuSO ₄ , (CH ₃ COO) ₂ Cu, copper(II) acetylacetonate, copper(II) carbonate, copper(II) cyclohexane butyrate , copper(II) stearate, copper(II) perchlorate, copper(II) ethylenediamine, Cu(OH) ₂ , nickel hydroxide (Ni(OH) ₂ ), silver nitrate, silver acetate, silver perchlorate ( silver perchlorate) and silver chloride, and the like, and the stabilizer may be selected from one or more of polyvinylpyrrolidone (PVP), polyvinyl alcohol, polyacrylamide, polyacrylic acid, and copolymers thereof. Among them, the use of polyvinylpyrrolidone (PVP) is most preferred. The solvent, ethylene glycol (ethylene glycol), diethylene glycol (diethylene glycol), 1,2-propylene glycol (1,2-propylene glycol), 1,3-propylene glycol (1,3-propylene gylcol), glycerol (glycerol) and glucose, etc. can be illustrated. In addition, examples of the reducing agent include ascorbic acid, sodium phosphinate monohydrate, sodium azide, hydrazine hydrate, sodium borohydride, and lithium aluminum hydride. In addition, the metal powder includes nickel (Ni), copper (Cu) and silver (Ag), and the particle size is 30 to 1,000 nm, preferably 40 to 100 nm, more preferably 40 to 60 nm, It has the shape of a sphere, a cube, a plate, and a wire.

For reference, the order of preparation of the polyacrylonitrile (PAN) solution for electrospinning and the preparation of the metal solution for electrospinning is irrelevant even if it is reversed, and is only listed in the order of the drawings.

2 is a schematic diagram of an electrospinning device for implementing a method of manufacturing a core-shell filler according to an embodiment of the present invention. Referring to Figures 1 and 2, the following steps will be described, the prepared polyacrylonitrile (PAN) solution 10 for electrospinning and the metal solution 12 for electrospinning to the double nozzle 20 of the electrospinning device. Put it in (S30). That is, positive and negative charges are respectively immersed in the tip to which the electrospinning solution is sprayed from the double nozzle 20 and the fiber assembly portion 40 where fibers are produced and collected, and the double nozzle 20 and the tube 14 0.05 to 3 mL/min, preferably 0.1 to 0.25 mL/min, in a syringe connected to each of the solutions (the electrospinning polyacrylonitrile (PAN) solution 10 and the electrospinning metal solution 12) It is injected into the double nozzle 20 at a speed of. At the same time as the input, after supplying a voltage of 0.5 to 40 KV, preferably 1 to 36 KV to the high voltage direct current generator 30 to make a potential difference between the fiber assembly unit 40 and the double nozzle 20, electricity The electrospinning polyacrylonitrile (PAN) solution 10 and the electrospinning metal solution 12 are spun by spinning to prepare a core-shell composite fiber (S32). When explaining the inside of the double nozzle 20, the electrospinning metal solution 12 flows to the center 22 of the double nozzle 20, and the electrospinning polyacrylonitrile (PAN) solution 10 Surrounds the central portion 22 of the double nozzle 20 through which the electrospinning metal solution 12 flows and fills the peripheral portion 24. Through this method, as shown in FIG. 3, there is a core 70 such as metal or metal oxide or graphene oxide at the center, and carbon fiber is used outside. A core-shell structure in which the made shell 60 is disposed is formed. On the other hand, the rotation of the fiber assembly portion 40 (collector) in which the fibers are manufactured and collected is controlled by the rpm controller 50. Finally, the core-shell structured composite fibers are crushed by ball milling to prepare a core-shell filler made of metal/carbon fibers (S 34). The aspect ratio of the composite fiber is 10 to 400, preferably 100 to 200, and the length of the carbon fiber constituting the core-shell filler after the crushing step by ball milling is 1 to 3,000 ㎛, preferably Preferably, it is 10 to 1,000 μm, more preferably 10 to 500 μm.

On the other hand, the electrospinning method used in the manufacture of the core-shell filler of the present invention enables the production of carbon fibers having various lengths, and the carbon fibers are used as a filler having excellent conductivity, for example, a conductive filler for ESD ink or EMI shielding. When applied to a conductive filler for ink, the length is 1 to 3,000 µm, preferably 1 to 1,000 µm, more preferably 1 to 500 µm, and the carbon fiber is used for ESD and EMI shielding pressure injection product conductive filler and strength When applied to a reinforcing filler (commercialization of 5 to 7 µm-sized carbon fibers for extrusion products), the length is 1 to 3,000 nm, preferably 100 to 3,000 nm, more preferably 500 to 3,000 nm. Therefore, with the two functions of conductivity and strength, it is possible to suppress the occurrence of cracks in the injection product due to the addition of the filler. The electro spinning method enables a simple process, easy fiber diameter control (40 nm or less), and various types of nanofibers such as hollow structure, core-shell, and porosity.

The step of treating the flame-resistant composite fiber of the core-shell structure prepared in step (S 32), which may be further included as necessary, and the step of carbonizing the flame-resistant composite fiber, will be described, alumina tube type Using an atmosphere controlled heat treatment furnace, while supplying air in an amount of 90 to 110 mL/min, preferably 95 to 105 mL/min, to the prepared core-shell structured composite fiber, 1 to 10 °C/min at room temperature , Preferably heated to a temperature of 150 to 250 °C, preferably 150 to 200 °C at a temperature rising rate of 3 to 7 °C/min, and maintained for 0.5 to 2 hours, preferably 0.5 to 1 hour to prevent flame resistance Do it. Then, argon (Ar) gas, which is an inert gas, is supplied to the chlorinated composite fiber in an amount of 90 to 110 mL/min, preferably 95 to 105 mL/min, using the heat treatment furnace, at room temperature. Heating to a temperature of 500 to 1,500° C., preferably 600 to 1,000° C. at a rate of 1 to 10° C./min, preferably 3 to 7° C./min, and 0.5 to 2 hours, preferably 0.5 to 1 hour It undergoes a carbonization treatment process that is maintained during. The flameproofing treatment is for improving the uniformity, structural properties, and mechanical properties (Young's modulus, Tensile Strength) of a shell made of carbon fiber, and the carbonization treatment is a shell made of carbon fiber. It is to improve the structural and electrical properties of In this way, the composite fiber that has undergone the flame-resistant treatment and carbonization treatment is crushed and then passed to a step (S34) in which a core-shell filler made of metal/carbon fibers is manufactured.

Meanwhile, a filler applicable to various fields may be manufactured by the method of manufacturing a core-shell filler according to the present invention. For example, in addition to the above-described conductive filler for ESD ink, conductive filler for EMI shielding ink, product conductive filler for ESD and EMI shielding pressure injection, filler for strength reinforcement, a filler for heat dissipation ink and a multifunctional filler.

Next, referring to FIG. 3, a core-shell filler according to the present invention will be described.

3 is a schematic diagram of a core-shell filler according to an embodiment of the present invention. As shown in FIG. 3, the core-shell filler according to the present invention includes powder-type copper (Cu) and nickel (Ni). , Metal oxide such as cobalt (Co), silver (Ag) or copper oxide (CuO), nickel oxide (NiO), cobalt oxide (CoO), or graphene oxide Consisting of particles such as, etc., a cylindrical core 70 (core) extending in the longitudinal direction (the extension direction of the core-shell filler shown in FIG. 3), and made of carbon fiber, and surrounding the core 70 It includes a shell (60, shell). The diameter of the shell 60 is 0.2 to 2 µm, preferably 0.4 to 1 µm, more preferably 0.4 to 0.8 µm, and the diameter of the particles constituting the core 70, for example, the metal ( metal) the diameter of the particles is 10 to 500 nm, preferably 10 to 100 nm, more preferably 10 to 60 nm, and the diameter of the core 70 is 20 to 95% of the diameter of the shell 60, preferably Preferably, it consists of a structure occupying 30 to 95%, more preferably 40 to 90%.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are intended to illustrate the present invention, and the present invention is not limited by the following examples.

[Example 1] Preparation of polyacrylonitrile ( PAN ) solution for electrospinning

After purifying acrylonitrile (Junsei chemical, Japan) and methacrylic acid (Junsei chemical, Japan) with sodium hydroxide (Samchun chemical, Korea), 90% by weight of the acrylonitrile and 10% by weight of the above Methacrylic acid was mixed and dissolved in a dispersion medium consisting of 20% by weight of dimethylformamide (DMF) and 80% by weight of distilled water with an initiator AIBN (2.5% by weight of acrylonitrile, Sigma-Aldrich, USA). Then, polymerization was performed at 70° C. for 3 hours under a nitrogen stream to prepare polyacrylonitrile (PAN) having an average molecular weight of 150,000 (GPC analysis). Then, after maintaining the temperature of a 90% by weight DMF (Samchun Chemical, Korea) solution in a 5-necked circular flask at 80 °C, 10% by weight of the prepared polyacrylonitrile (PAN) was added to the DMF solution. After dividing into ash and dissolving for 3 hours, a polyacrylonitrile (PAN) solution was prepared.

[Example 1-1a] Preparation of copper solution for electrospinning

At room temperature, 0.1 mol of CuSO ₄ (Sigma-Aldrich, USA) as a metal precursor, 0.3 mol of PVP10 (weight average molecular weight (Mw) = 10,000, Sigma-Aldrich, USA) as a stabilizer, and diethylene glycol (DEG, a solvent) Samchun Chemical Co., Korea) After dissolving in 13 mL, 0.25 mol of ascorbic acid (Fluka Co., Japan) as a reducing agent was dissolved in the DEG solution in which CuSO ₄ and PVP10 were dissolved to prepare a copper solution.

[Example 1-1b] Preparation of silver solution for electrospinning

At room temperature, metal precursor AgNO ₃ 0.1 mol, stabilizer PVP10 (weight average molecular weight (Mw) = 10,000, Sigma-Aldrich, USA) 0.4 mol, reducing agent hydrazine (Samchun chemical, Korea) 0.01 mol, solvent diethylene After dissolving in glycol (DEG, Samchun Chemical, Korea), 300 ml of the DEG solution in which AgNO _3, PVP10 and hydrazine were dissolved and 500 ml of diethylene glycol (DEG) were stirred to prepare a silver solution.

[Example 1-2a] Preparation of a filler having a core-shell structure made of copper/ carbon fibers by electrospinning

The positive and negative charges are immersed in the tip and the forming rod of the double nozzle, respectively, and the solution in a 20 mL syringe connected by the double nozzle and the tube (the polyacrylonitrile for electrospinning prepared in Examples 1 and 1-1a above) (PAN) solution and copper solution for electrospinning) are sprayed at a rate within 0.3 mL/min, and a high-voltage direct current generator is supplied with a voltage of 1 to 36 KV to produce a core-shell structured composite fiber by electrospinning. I did. The prepared fiber was heated to 150° C. at a rate of 5° C./min at room temperature while supplying air in an amount of 100 mL/min using an alumina tube-type atmosphere controlled heat treatment furnace, and then maintained for 1 hour to be flame resistant. Was done. Next, while supplying 99.99% argon (Ar) gas in an amount of 100 mL/min to the fiber that has undergone the chlorination-resistant process using the heat treatment furnace, heating it to 800 °C at a rate of 5 °C/min at room temperature. After going through a carbonization process maintaining 1 hour, a core-shell filler made of copper/carbon fibers was prepared by crushing with a composite fiber aspect ratio of about 100 using ball milling. .

[Example 1-2b] Silver by electrospinning / Manufacture of core-shell filler made of carbon fiber

A core-shell filler made of silver/carbon fibers was prepared in the same manner as in Example 1-2a, except that a silver solution for electrospinning was used instead of the copper solution for electrospinning.

In Table 1 below, when the filler was manufactured (Examples 1-2a and 1-2b), the change in the diameter of the filler according to the change in the applied voltage was measured.

Applied voltage (KV) Radiation temperature (℃) Average diameter of filler (nm) 8 23±2 430 12 23±2 560 15 23±2 620 18 23±2 770 20 23±2 980

As shown in Table 1, it is shown that the core-shell filler made of copper/carbon fiber and the core-shell filler made of silver/carbon fiber can be manufactured in dimensions of nanometers to micrometers.

[Experimental Example 1a] Preparation of a conductive ink to which a core-shell filler made of copper/ carbon fibers manufactured by electrospinning was applied

The core-shell filler consisting of about 400 nm-sized copper/carbon fibers prepared in Example 1-2a 70 wt%, propylene glycol monomethyl ether acetate (PGMEA) 21 wt%, polyester resin 8 wt%, polyacrylate dispersant 1 After adding wt% and mixing for about 30 minutes, the paste is prepared by dispersing with a 3 roll mill. The prepared paste was applied to a polyimide film to a thickness of about 10 μm using an automatic coating machine, and then put in a hot air oven and dried for 30 minutes at each temperature, and the sheet resistance of the film was measured using a 4 point probe.

[Experimental Example 1b] Preparation of conductive ink to which a core-shell filler made of silver/ carbon fibers manufactured by electrospinning was applied

The experiment was performed in the same manner as in Experimental Example 1a, except that the core-shell filler made of silver/carbon fiber was applied instead of the core-shell filler made of copper/carbon fiber.

Table 2 below shows the results of measuring the sheet resistance of the film in Experimental Examples 1a and 1b, respectively.

Drying temperature
(℃) Film sheet resistance (Ω/sq, copper/carbon fiber filler) Film sheet resistance (Ω/sq, silver/carbon fiber filler) 100 8.1 X 10 5.1 X 10 ^-1 150 1.4 X 10 8.4 X 10 ^-2 200 9 X 10 ^-1 7 X 10 ^-2 250 5.7 X 10 ^-1 6.7 X 10 ^-2

As shown in Table 2, it can be seen that there is no increase in resistance due to the effect of preventing oxidation when heat treatment is performed up to 100 to 250°C by applying the filler for EMI shielding.

[Experimental Examples 2-1 to 2-6] Preparation of an electromagnetic wave shielding sheet to which a core-shell filler made of copper/ carbon fibers manufactured by electrospinning is applied

As shown in Table 3 below, a core-shell filler consisting of an ABS resin (acrylonitrile-butadiene-styrene resin) and copper/carbon fibers having an average diameter of about 1 micrometer (㎛) prepared in Example 1-2a After premixing at a weight ratio of 85: 15 to 60: 40, it was administered to a twin-screw extruder maintaining the temperature of the barrel at 250 to 270 °C, and the screw rotation speed was melted, kneaded and cooled at 200 rpm. After passing through, a master batch was prepared through pelletizing. In addition, the dried master batch was administered to a hopper of an injection machine and maintained at a cylinder temperature of 230 to 255 °C and a nozzle temperature of 240 °C, and the mold with an injection pressure of 940 kgf/cm ² and a back pressure of 20 kgf/cm ² Injected into, an electromagnetic wave shield having a size of 80 mm x 15 mm x 3 mm (length x width x thickness) was prepared to measure the surface resistance, and the results are shown in Table 3 below. In addition, by applying 15 to 20% by weight of carbon fiber (Toho Tenax, Japan) having an average diameter of about 7 micrometers (㎛) and an aspect ratio of about 100, a specimen of the same size was prepared through the same process. , The surface resistance was measured, and it is shown together in Table 3 below.

Content of ABS resin (% by weight) Filler (filler) Content of filler (filler) (% by weight) Surface resistance
(Ω/sq) Shielding sheet thickness (mm) Experimental Example 2-1 85 Core-shell copper/carbon composite fiber 15 50 3 Experimental Example 2-2 80 Core-shell copper/carbon composite fiber 20 34 3 Experimental Example 2-3 70 Core-shell copper/carbon composite fiber 30 5.3 3 Experimental Example 2-4 60 Core-shell copper/carbon composite fiber 40 3.6 3 Experimental Example 2-5 85 Carbon fiber 15 250 3 Experimental Example 2-6 80 Carbon fiber 20 100 3

As shown in Table 3, in the case of the electromagnetic wave shielding sheet impregnated with the core-shell filler made of copper/carbon fiber prepared in Example 1-2a, compared to the same content of the sheet prepared by adding only the existing carbon fiber It has a surface resistance value of 20 to 35%. 4 is a surface view (2-1 to 2-4) of an electromagnetic wave shielding sheet specimen to which a core-shell filler is applied and a surface view (2-5 and 2-6) of an electromagnetic wave shielding sheet specimen to which only carbon fiber is applied according to the present invention. ), as shown in Table 3 above It can be seen that as the filler content increases, the surface resistance value decreases and the color of the specimen becomes darker as shown in FIG. 4. Accordingly, it is shown that a product having excellent conductivity and electromagnetic wave shielding performance can be manufactured by using the core-shell filler made of metal/carbon fiber of the present invention.

Claims (12)

(a) preparing a polyacrylonitrile solution for electrospinning;
(b) metal precursors; A stabilizer selected from the group consisting of polyvinylpyrrolidone (PVP), polyvinyl alcohol, polyacrylamide, polyacrylic acid, and copolymers thereof; And preparing a metal solution for electrospinning consisting of a solvent.
(c) introducing the polyacrylonitrile solution for electrospinning and the metal solution for electrospinning into a double nozzle of an electrospinning device;
(d) spinning the polyacrylonitrile solution for electrospinning and the metal solution for electrospinning by electrospinning to prepare a core-shell structured composite fiber; And
(e) manufacturing a core-shell filler made of metal/carbon fibers by crushing the core-shell structured composite fibers. The core-shell filler according to claim 1, further comprising the step of treating the composite fiber of the core-shell structure prepared in step (d) with a flame resistance and carbonizing the composite fiber having the flame-resistant treatment. Method of manufacturing. The method according to claim 1, wherein the step (c), the electrospinning metal solution flows to the center of the double nozzle, the electrospinning polyacrylonitrile solution is the center of the double nozzle through which the electrospinning metal solution flows The method of manufacturing a core-shell filler that wraps around and fills the periphery. The method of claim 1, wherein the polyacrylonitrile solution for electrospinning is prepared with acrylonitrile, an acrylic comonomer, an initiator, a dispersion medium, and a solvent. delete The method of claim 1, wherein a metal powder is prepared by adding a reducing agent to the metal solution for electrospinning. The method according to claim 2, wherein the salt-resistant treatment is heated to a temperature of 150 to 250 °C at a temperature rising rate of 1 to 10 °C/min at room temperature while supplying air and maintained for 0.5 to 2 hours, and the carbonization treatment is inert. A method for producing a core-shell filler that is heated to a temperature of 500 to 1,500° C. at a rate of 1 to 10° C./min while supplying gas and maintained for 0.5 to 2 hours. The method according to claim 1, wherein when the carbon fiber is applied to a conductive filler for ESD ink or a conductive filler for EMI shielding ink, a length of 1 to 3,000 µm is applied, and the carbon fiber is used as a product conductive filler and strength for ESD and EMI shielding extrusion. The length when applied to the reinforcing filler is 1 to 3,000 nm, and the diameter of the metal particles constituting the core-shell filler is 10 to 500 nm. A core in the form of a cylinder, which is made of particles selected from the group consisting of powder-type metal, metal oxide, and graphene oxide, and extends in the longitudinal direction; And
A core-shell filler for ESD ink or EMI shielding ink made of carbon fiber and comprising a shell surrounding the core. The method according to claim 9, wherein the diameter of the shell (shell) is 0.2 to 2 ㎛, the diameter of the particles constituting the core is 10 to 500 nm, the diameter of the core occupies 20 to 95% of the diameter of the shell Core-shell filler for phosphorus ESD inks or EMI shielding inks. The method according to claim 9, wherein the metal is selected from the group consisting of copper (Cu), nickel (Ni), cobalt (Co), and silver (Ag), and the metal oxide is copper oxide (CuO ), nickel oxide (NiO) and cobalt oxide (CoO) that is selected from the group consisting of ESD ink or EMI shielding ink for core-shell filler. The method according to claim 9, wherein the metal powder has a shape selected from the group consisting of a sphere (spherical), a cube (cube), a plate (plate) and a wire (wire) for ESD ink or EMI shielding ink core- Shell filler.

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