KR20100080089A - Conductive polymer composite powder and fabrication method thereof, and conductive polymer composite molded article using the same - Google Patents

Abstract

PURPOSE: A method for fabricating conductive polymer composite powder is provided to prepare conductive polymer composite powder without solvent and additive and to improve reaction efficiency. CONSTITUTION: A conductive polymer composite powder has conductive filler particles on a polymer particle surface by mechanofusion. A method for fabricating the conductive polymer composite powder comprises: a step of filling polymer particles and conductive filler particles to a dry high energy mixer; and a step of performing mechanofusion. The particle size of the polymer is 1-200 micron.

Description

Conductive polymer composite powder and manufacturing method thereof, and conductive polymer composite molded article using the same {CONDUCTIVE POLYMER COMPOSITE POWDER AND FABRICATION METHOD THEREOF, AND CONDUCTIVE POLYMER COMPOSITE MOLDED ARTICLE USING THE SAME}

The present invention relates to a conductive polymer composite powder using a mechanochemical bonding system, a method for producing the same, and a conductive polymer composite molded article having an extremely low electrical critical point.

The conductive polymer composite molded body having a conductive particle such as carbon black, carbon fiber, carbon nanotube, metal powder, etc. as a matrix and an insulator polymer as a matrix is not only excellent in formability and light weight but also inexpensive in terms of cost. Such a conductive polymer composite molded body is currently used in various fields as an antistatic material, a conductive material, a heat generating material, and a switching element, and the importance of the conductive polymer composite molded article has increased further in recent years.

In the conductive polymer composite molded body, the added conductive filler particles form a continuous conductive network in the polymer matrix to act as a path for the hopping and tunneling effect of the electrons, thereby exhibiting conductivity. will be. The minimum amount of conductive filler particles required to form this continuous conductive network is the electrical threshold. The more the content of the conductive filler particles in the conductive polymer composite molded body, the more difficult the manufacturing process due to the increase in viscosity, the lower the physical properties and the higher the cost, so considering the technical and economic aspects, the electrical critical point of the conductive filler particles It is desirable to lower as much as possible. Factors affecting the electrical critical point include the type and size of conductive filler particles, melt viscosity of the polymer, process conditions, dispersibility of the filler particles in the polymer, and interfacial energy between the polymer and the filler particles. Among the factors, research has been actively conducted to lower the electrical critical point by improving the dispersibility and interfacial adhesion of the conductive filler particles in the polymer matrix.

In general, a method of manufacturing a conductive polymer composite molded body is obtained by dispersing carbon nanotubes (CNT) in a solution in which a polymer is dissolved using a solvent, and then hot-pressing a mixed powder of a polymer and CNT obtained by evaporating the solvent into a mold. Method of manufacturing a molded article (Korean Patent Publication No. 2003-0005710), a method of manufacturing a conductive polymer composite molded article by melt-mixing a polymer and a conductive filler and molding using a hot press (Korea Patent Publication No. 2005-0051939 No.), a method of producing a mixture by mixing with the conductive filler in the monomer step of the polymer (Korean Patent Publication No. 2008-0064836) and the like.

However, in the above-described conventional manufacturing methods, a chemical surface modification or mechanical dispersion technique of the conductive filler particles is required in order to improve the dispersibility and interfacial adhesion of the conductive filler particles in the polymer matrix. In addition to the large amount of energy consumed by various post-treatment processes, there is a problem that the process time is delayed and causes environmental pollution. In addition, the electrical properties of the conductive filler particles may be impaired due to additionally required technology and / or post-treatment processes, or the electrical properties of the conductive polymer composite molded body may be degraded because the electrical network is not formed when the molded body is manufactured.

The present invention has been made to solve these conventional problems, the present invention provides a method for producing a conductive polymer composite powder without the use of solvents and additives, conductive polymer composite molded article having excellent electrical properties while significantly lowering the electrical critical point The purpose is to provide.

In addition, the present invention provides a method for producing a conductive polymer composite powder and a conductive polymer composite molded body which can improve the reaction efficiency in the process, simplify the process, and are environmentally friendly and can significantly save energy without supplying a heat source from the outside. Has its purpose.

These objects can be achieved by the following configuration of the present invention.

(1) A conductive polymer composite powder, wherein the conductive filler particles are physically bonded to each other by mechanofusion.

(2) Conductive using the conductive polymer composite powder, characterized in that a plurality of conductive polymer composite powder according to (1) is molded into a predetermined shape and the conductive filler particles are dispersed while forming a continuous conductive network in a polymer matrix Polymer composite molded body.

(3) putting polymer particles and conductive filler particles into a dry high-energy mixer, and mechanofusion to form a conductive polymer composite powder in which the conductive filler particles are physically and chemically bonded to the surface of each of the polymer particles. Method for producing a conductive polymer composite powder, characterized in that for producing.

(4) a cylindrical inner container and an armor fixed separately from the inner container spaced apart from the inner wall of the inner container and facing an inner wall of the inner container, the arm having a larger radius of curvature of the inner container Putting the polymer particles and the conductive filler particles into the inner container of a dry high energy mixer;

Rotating the inner container to collect the polymer particles and the conductive filler particles toward the inner wall of the inner container by centrifugal force, while the polymer particles and the conductive filler particles in the space between the inner wall of the inner container and the armor Conductive polymer composite powder characterized in that the physicochemical bonding by mechanofusion occurs between the polymer particles and the conductive filler particles by applying a shear force and a compressive force to the polymer particles and the conductive filler particles by passing through Method of preparation.

According to the present invention, by using the high mechanical energy of the dry high-energy mixer through the control of the material conditions and process conditions without the use of solvents and additives to induce surface changes and physical properties of the polymer particles and conductive filler particles, thereby The polymer particles and the conductive filler particles may be physically combined. Accordingly, the reaction efficiency can be improved in the process without supplying a heat source from the outside.

In addition, the process is relatively simple, environmentally friendly, and short in process time, which is economical as compared with the conventional wet method using additives or changing the surface of the conductive filler particles to lower the electrical critical point. have. That is, the molded article having the same electrical properties can be produced with a smaller amount of conductive filler particles than the conventional method.

The conductive polymer composite powder according to an aspect of the present invention is characterized in that the conductive filler particles are physicochemically bonded to the surface of the polymer particles by mechanofusion.

Here, the polymer particles are polyvinyl acetate, ethylene-vinylacetate copolymer, acrylate, acrylic-ester copolymer, styrene, styrene-acrylate copolymer, polyurethane, rubber latex, natural rubber, butyl rubber, styrene butadiene rubber And it may be made of any one material selected from the group consisting of copolymers and mixtures thereof. However, the present invention is not limited thereto. In addition, the polymer particles may be amorphous or crystalline.

In addition, the conductive filler particles may be silver, copper, gold, palladium, platinum, nickel, gold or silver coated nickel, carbon black, lead, zinc, metal alloy, carbon fiber, carbon nanotube. Graphite, aluminum, indium tin oxide, silver coated copper, silver oxide, silver coated aluminum, metal coated glass spheres, metal coated fillers, metal coated polymers, silver coated fibers, It may be made of at least one material selected from the group consisting of silver coated spheres, antimony doped tin oxide, and conductive nanospheres. However, the present invention is not limited thereto.

After the dry mixing of the polymer particles and the conductive filler particles, high mechanical energy is applied to the mixture, and the polymer particles and the conductive filler particles are subjected to a strong shear force and a compressive force, whereby between the polymer particles and the conductive filler particles By generating sufficient heat energy to cause mechanofusion, the conductive filler particles are physically bonded to the surface of the polymer particles.

In the present invention, the size of the polymer particles is 1 ~ 200 ㎛, the average diameter of the conductive filler particles (in the case of fiber or tube shape) or the size (in the case of the general shape except fiber and tube shape) is 10 nm ~ 10 μm, and the size ratio of the polymer particles to the average diameter or size of the conductive filler particles is preferably 10 or more.

Hereinafter, a method of manufacturing the conductive polymer composite powder will be described.

According to the present invention, polymer particles and conductive filler particles are put into a dry high-energy mixer, and mechanofusion is performed to form a conductive polymer composite powder in which the conductive filler particles are physicochemically bonded to the surfaces of the polymer particles. To prepare.

According to FIG. 1, the dry high energy mixer may include a rotatable inner container A, a stationary outer container B, a stationary scraper C and an armor D. Here, the inner container A is preferably cylindrical. In addition, the armor D is fixed separately from the inner container A while being spaced apart from the inner wall of the inner container A by a predetermined distance. In this case, the portion of the armor D facing the inner wall of the inner container A is preferably larger than the radius of curvature of the inner container A, as shown.

In order to manufacture the conductive polymer composite powder according to the present invention, first, the polymer particles and the conductive filler particles are placed in the inner container A of the dry high energy mixer. Then, while rotating the inner container (A) to collect the polymer particles and the conductive filler particles toward the inner wall of the inner container (A) by centrifugal force, the inner wall of the inner container (A) and the armor (D) The polymer particles and the conductive filler particles are passed through a space between the layers) to apply strong shear and compressive forces to the polymer particles and the conductive filler particles. As a result, sufficient thermal energy is generated between each of the polymer particles and the conductive filler particles so as to cause mechanofusion, and thus a strong physicochemical reaction between each of the polymer particles and the conductive filler particles. Coupling will occur. For reference, the scraper (C) is attached to the inner wall of the inner container (A) of the polymer particles and the conductive filler particles passed between the inner container (A) and the armor (D) by mechanical compression. It scrapes away the substances present and helps to participate in the mechanofusion reaction again.

In the use of the dry high-energy mixer, the process time can be adjusted from 1 minute to several hours, thereby enabling the structure control of the conductive polymer composite powder thus prepared, and affecting the electrical critical point of the conductive filler particles. Can be.

Moreover, it is preferable that the rotation speed of the said inner container A is 500-5000 rpm. Since the strength of the mechanical force received by the conductive filler particles and the polymer particles is adjusted according to the rotation speed, morphology and structure control of the conductive polymer composite powder is possible through the control of the rotation speed. In addition, the rotational speed can affect the electrical critical point of the conductive filler particles.

In addition, the gap between the inner wall of the inner container A and the armor D is preferably 1 to 3 mm. The gap size affects the number of collisions and may affect the morphology of the conductive polymer composite powder and the electrical critical point of the conductive filler particles.

In addition, in the use of the dry high energy type mixer, the processing atmosphere can also be adjusted by air, nitrogen, argon or the like.

As such, the morphology and the structure of the conductive polymer composite powder can be controlled by controlling the material factor and the process factor when the conductive polymer composite powder is prepared, and the electric critical point of the conductive filler particles can be lowered.

Meanwhile, the conductive polymer composite molded body according to another aspect of the present invention is characterized in that a plurality of conductive polymer composite powders obtained as described above are molded into a predetermined shape and the conductive filler particles are dispersed while forming a continuous conductive network in a polymer matrix. It is done.

Referring to FIG. 2, as described above, the polymer particles and the conductive filler particles (CNT) are mechanofused to form conductive polymer composite powders in which the conductive filler particles are physicochemically bonded to the surfaces of the polymer particles. These are molded into a predetermined shape by compression molding to obtain the conductive polymer composite molded body. The conductive polymer composite molded body according to the present invention, as shown, the conductive filler particles bonded to the surface of each of the polymer particles constituting the polymer matrix are in contact with the conductive filler particles are bonded to the surface of the adjacent polymer particles Thereby forming a continuous conductive network. Therefore, according to the present invention, the electrical critical point of the conductive polymer composite molded article can be greatly lowered. That is, it is possible to produce a molded article having the same electrical properties even with a smaller amount of conductive filler particles than the conventional method. In the present invention, the content of the conductive filler particles is preferably at least 5% by weight or more indicating the electrical threshold of the conductive polymer composite molded body. Although compression molding is illustrated as a molding method in FIG. 2, the present invention is not limited thereto.

Hereinafter, the present invention will be described in detail with reference to examples, but these examples are only presented to more clearly understand the present invention, and are not intended to limit the scope of the present invention. It will be determined within the scope of the technical spirit of the claims.

Example

In order to prepare the conductive polymer composite powders, polypropylene having a size of 300 to 500 μm was used as a polymer particle, and multi-walled carbon nanotubes having a length of 10 to 50 μm and a diameter of 10 to 20 nm were used. MWNTs) were used by acid treatment. In using the dry high-energy mixer (Mechanofusion manufactured by Hosokawa Micron) of FIG. 1, the gap of the mixer (ie, the gap between the inner vessel and the armor) is fixed at 1 mm, and the process time is 5 to 30 minutes. Rotational speed of the inner container was adjusted to 500 ~ 2500 rpm to produce a conductive polymer composite powder.

The conductive polymer composite powders obtained above were compression molded at a temperature of 3 klbf at 180 ° C. using tetrahedron to prepare a conductive polymer composite molded article having a thickness of 1 mm.

As a comparative example, the conductive polymer composite powders manufactured by using the general high speed mixer were molded in the same manner as in the above-described embodiment to prepare a conductive polymer composite molded body.

Dispersion state of the conductive filler particles in the conductive polymer composite molded body was observed through a scanning electron microscope (SEM), and a four-point method (four-point method) using a current supply meter (Keithley, Model 6280) and a voltmeter (Model 2182A) was used. The electrical conductivity was measured by the probe method.

3 is an SEM image of a conductive polymer composite molded body using a general high speed mixer (a) and a dry high energy mixer (b). Unlike the conductive polymer composite molded article (a) made of a general high speed mixer in which the MWNTs are not evenly distributed, the conductive polymer composite molded article produced by the present invention was not only uniformly dispersed but also more strongly attached. Through this, it was found that the conductive polymer composite molded article manufactured with the dry high energy mixer exhibited excellent dispersibility and interfacial adhesion.

4 to 6 show electrical conductivity measurement results of a general high speed mixer and a conductive polymer composite molded body produced by the present invention. When the conductive polymer composite molded body was manufactured with a general high speed mixer, the electrical critical point appeared at 7 wt%. However, when manufactured with a dry high energy type mixer, the electrical critical point did not change significantly depending on the process time. The electrical threshold changed with speed. It was found that the electrical threshold was significantly reduced to 5 wt% at 500 rpm and 2 wt% at 2500 rpm. Therefore, when the conductive polymer composite molded body is manufactured according to the present invention, it can be seen that the electrical critical point can be lowered.

In the above, the present invention has been described with reference to the illustrated examples, which are merely examples, and the present invention may be embodied in various modifications and other embodiments that are obvious to those skilled in the art. Understand that you can.

1 is a cross-sectional view showing a schematic structure of a dry high energy mixer used in the present invention.

Figure 2 is a schematic diagram showing the manufacturing process of the conductive polymer composite molded article according to the present invention.

FIG. 3 is a scanning electron microscope (SEM) image (a) of a conductive polymer composite molded body using conductive polymer composite powders prepared with a general high speed mixer as a comparative example, and a conductive high energy mixer manufactured as a dry high energy mixer as an embodiment of the present invention. A scanning electron microscope (SEM) image (b) of a conductive polymer composite molded body using polymer composite powders.

4 to 6 show electrical conductivity measurement results of a general high speed mixer and a conductive polymer composite molded body produced by the present invention.

Claims (12)

A conductive polymer composite powder, characterized in that the conductive filler particles are physically bonded to the surface of the polymer particles by mechanofusion. The method of claim 1, wherein the polymer particles are polyvinylacetate, ethylene-vinylacetate copolymer, acrylate, acrylic-ester copolymer, styrene, styrene-acrylate copolymer, polyurethane, rubber latex, natural rubber, butyl rubber Conductive polymer composite powder, characterized in that made of any one material selected from the group consisting of styrene butadiene rubber and copolymers and mixtures thereof. The method of claim 1, wherein the conductive filler particles are silver, copper, gold, palladium, platinum, nickel, gold or silver coated nickel, carbon black, lead, zinc, metal alloys, carbon fiber , Carbon nanotubes, graphite, aluminum, indium tin oxide, silver coated copper, silver oxide, silver coated aluminum, metal coated glass spheres, metal coated fillers, metal coated polymers, silver coated A conductive polymer composite powder comprising at least one material selected from the group consisting of coated fibers, silver coated spheres, antimony-doped tin oxide and conductive nanospheres. The method of claim 1, wherein the size of the polymer particles is 1 ~ 200 ㎛, the average diameter or size of the conductive filler particles is 10 nm ~ 10 ㎛, the diameter of the polymer particles relative to the average diameter or size of the conductive filler particles Conductive polymer composite powder, characterized in that the size ratio is 10 or more. The conductive polymer composite according to any one of claims 1 to 4, wherein the plurality of conductive polymer composite powders are formed into a predetermined shape and the conductive filler particles are dispersed in a polymer matrix while forming a continuous conductive network. Conductive polymer composite molded body using powder. The method of claim 5, wherein the conductive filler particles bonded to the surface of each of the polymer particles constituting the polymer matrix are in contact with the conductive filler particles bonded to the surface of the adjacent polymer particles to form a continuous conductive network Conductive polymer composite molded body using a conductive polymer composite powder, characterized in that. The conductive polymer composite molded body of claim 5, wherein a content of the conductive filler particles is 5 wt% or less, the minimum content representing an electrical critical point of the conductive polymer composite molded body. Putting polymer particles and conductive filler particles into a dry high-energy mixer, and mechanofusion to prepare a conductive polymer composite powder in which the conductive filler particles are physically and chemically bonded to the surfaces of the polymer particles. Method for producing a conductive polymer composite powder. A dry solid having a cylindrical inner container and an armor which is fixed apart from the inner container at a distance from the inner wall of the inner container and whose portion facing the inner wall of the inner container is larger than the radius of curvature of the inner container. Putting the polymer particles and the conductive filler particles into the inner container of an energy mixer; Rotating the inner container to collect the polymer particles and the conductive filler particles toward the inner wall of the inner container by centrifugal force, while the polymer particles and the conductive filler particles in the space between the inner wall of the inner container and the armor Conductive polymer composite powder characterized in that the physicochemical bonding by mechanofusion occurs between the polymer particles and the conductive filler particles by applying a shear force and a compressive force to the polymer particles and the conductive filler particles by passing through Method of preparation. The method of claim 9, wherein the rotation speed of the inner container is 500 ~ 5000 rpm. 10. The method of claim 9, wherein the gap between the inner wall of the inner container and the armor is 1 to 3 mm. 10. The method of claim 9, wherein the physicochemical bonding by the mechanofusion is performed under air, nitrogen, or argon atmosphere.

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