KR101090106B1 - Electroconductive particle and?preparation method thereof - Google Patents

Abstract

The present invention relates to an electrically conductive particle and a method for producing the same, wherein the electrically conductive particle according to the present invention Conductivity stability, Excellent surface conductivity, durability and heat resistance, it can be usefully applied to the production of anisotropic conductive film used for packaging of electronic devices, and also has excellent electrical conductivity, and various display devices such as various mobile devices, liquid crystal displays, electronic paper systems, etc. It can be easily applied to the micropattern forming process essential for manufacturing.

Graphene, Electrically Conductive Particles, Covalent Bonds, Heat Resistance, Composite Particles

Description

Electrically conductive particles and manufacturing method thereof {ELECTROCONDUCTIVE PARTICLE AND 그 PREPARATION METHOD THEREOF}

The present invention provides improved long term conductivity stability with good electrical conductivity, The present invention relates to a connection electron conductive particle having a surface conductivity, durability, and heat resistance, which is easy to manufacture an anisotropic conductive film used as a connection material in the packaging of an electronic device, and a method of manufacturing the same.

In general, electronic packaging technology is a very broad and diverse system manufacturing technology that includes all manufacturing steps from semiconductor devices to the final product, and is a very important technology for determining the performance, size, price, reliability, etc. of the final electronic product. to be.

In recent years, with the fine gap of the circuit and the increase of the connection density, it is required to connect a plurality of electrodes formed at a narrow interval in semiconductor packaging or display packaging at once. Accordingly, in the packaging of liquid crystal displays (LCDs), conductive adhesives for mechanical and electrical connection between printed circuit boards and transparent electrodes are mainly used.

The conductive adhesive is used in various forms such as anisotropic conductive film (ACF) and isotropic conductive adhesive (ICA), and among these, the electrically conductive particles may be formed into a thermosetting or thermoplastic insulating resin. Anisotropic conductive films composed of a dispersed form are mainly used.

Powdered or fibrous carbonaceous materials were initially used as the electrically conductive particles serving as electrical conductors, and then solder balls such as silver (Ag) were used, followed by nickel (Ni) particles or polymers. Nickel-coated polymer balls on the particle surface have been used to date.

Nickel used in the electrically conductive particles of the anisotropic conductive film has a low price and relatively good electrical conductivity, but when exposed to high temperature and high humidity, there is a problem that corrosion or oxidation occurs on the surface. In order to solve this problem, a method of coating gold (Au) on the surface of nickel particles has been proposed, and the gold-coated electrically conductive particles are polymer fine particles including polystyrene containing a crosslinkable monomer such as divinylbenzene. ) It was developed in the form of coating nickel on the surface of the particle and coating gold on the surface again.

However, in the case of electrically conductive particles coated with a metal on the surface of the polymer fine particles, there is a problem that it is difficult to secure long-term conductive stability or mechanical properties due to low interfacial adhesion between the polymer fine particles and the metallic coating film, and also to coat the metal on the surface of the polymer fine particles. Due to the plating process, there is a problem that a large amount of environmentally harmful substances are generated with the increase of manufacturing cost. In addition, in the anisotropic conductive film prepared by dispersing the electrically conductive particles in the insulating resin, although the connection resistance, reliability, fairness, etc. are the most important characteristics, the adhesion of the polymer fine particles and the metal by adhesion to each other by heating and pressing In the process of forming the conductive portion in the indented portion, the large modulus difference between the polymer fine particle and the metal layer and the lack of affinity tend to cause the metal layer on the surface of the polymer fine particle to crack and peel off, resulting in a significant decrease in conductivity or even There was a problem of being insulated.

As a result, it has excellent long-term conduction stability, surface conductivity and durability, and excellent heat resistance without fear of conductivity deterioration due to cracking and peeling between the polymer fine particles and the metal layer, and the connection between the IC and various passive elements, the LCD substrate, There is a demand for electrically conductive particles capable of exhibiting high electrical conductivity, which can maintain an electrical circuit configuration even at an adhesive temperature of 100 ° C. or higher during an electrical connection process with a drive circuit.

Accordingly, the object of the present invention is to solve the above problems, while having excellent electrical conductivity and at the same time Conductivity stability, It is to provide electrically conductive particles with improved surface conductivity, durability and heat resistance.

It is also an object of the present invention to provide a method for producing the electrically conductive particles.

It is also an object of the present invention to provide an anisotropic conductive film comprising said electrically conductive particles.

According to the above object, in the present invention, a graphene coating layer in which a polymer fine particle having a condensation-reactive functional group on its surface and a graphene having a functional group capable of covalently bonding to the condensation-reactive functional group on the surface of the polymer fine particle are covalently attached. It provides an electrically conductive particle comprising a.

In the present invention, (1) preparing a polymer fine particle modified to have a condensation functional group on the surface, (2) to the surface of the graphene, a functional group capable of covalently bonded to the condensation functional group of the surface of the polymer fine particles And (3) covalently attaching the graphene prepared in step (2) to the surface of the polymer fine particles prepared in step (1) to form a graphene coating layer. Provide a method.

The present invention also provides an anisotropic conductive film comprising the electrically conductive particles.

The electrically conductive particles according to the present invention exhibit excellent electrical conductivity by including a graphene coating layer having excellent electrical conductivity on the surface of the polymer fine particles, and thus can be easily applied to the micropattern forming process. In addition, since the graphene is covalently attached to the polymer fine particles, it is possible to prevent cracking and peeling in the conductive layer caused by the difference in properties between the polymer fine particles and the metal, and also to prevent the graphene and the polymer fine particles at a high temperature. To prevent cracking can improve durability. As a result, not only excellent electrical conductivity can be maintained for a long time, but also excellent heat resistance can maintain stable electrical conductivity even at high temperatures in the bonding process. In addition, according to the manufacturing method of the electrically conductive particles according to the present invention it is possible to produce the electrically conductive particles having the above excellent physical properties in a simple manufacturing process and low manufacturing cost.

Hereinafter, the present invention will be described in more detail.

According to the present invention, the graphene having excellent electrical conductivity is attached to the surface of the polymer fine particles through a covalent bond, thereby providing excellent electrical conductivity and at the same time. Conductivity stability, It is characterized by providing electrically conductive particles with improved surface conductivity, durability and heat resistance.

That is, according to one embodiment of the present invention, the polymer fine particles having a condensation-reactive functional group on the surface, and the graphene having a functional group capable of covalently bonded to the condensation-reactive functional group on the surface of the polymer particles are covalently attached It provides an electrically conductive particle comprising a graphene coating layer.

1 is a schematic diagram showing a cross section of the electrically conductive particles according to an embodiment of the present invention. Referring to Figure 1, the electrically conductive particles according to the present invention is a graphene having a polymer group (A) having a condensation-reactive functional group on the surface and a functional group capable of covalently bonded to the condensation-reactive functional group on the surface of the polymer particles And a graphene coating layer (C) attached by a covalent bond, wherein the polymer fine particles (A) and the graphene coating layer (C) may be covalently bonded to the condensation-reactive functional group and the condensation-reactive functional group of the polymer microparticles. Covalent bonding layer (B) is formed by covalent bonding with the functional group of graphene.

The condensation-reactive functional group and the functional group capable of covalently bonding with the condensation-reactive functional group are introduced into the surface and graphene of the polymer microparticles, respectively, during preparation of the electrically conductive particles, thereby enabling covalent bonding of the polymer microparticles and graphene. . Functional groups introduced on the surface of the polymer fine particles and graphene include a carboxyl group (-COOH), a hydroxyl group (-OH), an ester group (-COOR, wherein R is an alkyl, phenyl, or benzyl group having 1 to 10 carbon atoms. ), An amine group (-NH ₂ ), a thiol group (-SH) and the like are possible, but are not limited to the functional groups described above.

Between the condensation-reactive functional groups of the surface of the polymer fine particles and the graphene surface as above, specific examples are -COOH and -OH, -COOR and -OH, -COOH and -NH ₂ , -COOR and -NH ₂ , or -SH and -SH The reaction between them forms an ester bond (-COO-), an amide bond (-CONH-), a disulfide bond (-SS-), and the like. Since such covalent bonds are stable even at high temperatures, the electrically conductive particles according to the present invention exhibit excellent durability without the risk of cracking between the polymer fine particles and the graphene even at high temperatures, and also have excellent heat resistance, thereby maintaining stable electrical conductivity. .

In the electrically conductive particles, if the content of the polymer fine particles is too high compared to the graphene, it is difficult to secure the electrical conductivity, and if the content of the graphene is high, the electrical conductivity may be increased, but it is difficult to secure structural stability, and furthermore, It is not easy to form. Accordingly, the weight ratio of the polymer fine particles and the graphene is preferably 20:80 to 85:15, and more preferably 50:50 to 70:30 in that it can exhibit excellent electrical conductivity and durability.

In addition, the size is almost the same as the size of the polymer fine particles because the thickness of the graphene coated on the surface of the polymer fine particles is very thin, preferably has an average particle diameter of 0.1 to 10 ㎛.

The electrically conductive particles having the structure as described above may be prepared by the manufacturing method as described below.

That is, according to another embodiment of the present invention, (1) preparing a polymer microparticles whose surface is modified with a condensation-reactive functional group, (2) covalent bond with the condensation-reactive functional group on the surface of the polymer fine particles on the surface of the graphene (3) covalently attaching the graphene prepared in step (2) to the surface of the polymer microparticles prepared in step (1) to form a graphene coating layer. It provides a method for producing electrically conductive particles.

Hereinafter, each step will be described in more detail.

Step (1)

In step (1), polymer fine particles whose surface is modified with a condensation functional group such as -COOH, -COOR, -OH, -NH ₂ , -SH, etc. are prepared.

Specifically, the polymer fine particles having a condensation-reactive functional group on the surface are prepared by dispersion polymerization, emulsion polymerization or suspension polymerization of the monomer for forming the polymer fine particles alone or together with the auxiliary monomer in the presence of a crosslinking agent, a polymerization initiator and a dispersant. can do.

At this time, it is preferable to use the monomer for forming the polymer fine particles together with the auxiliary monomer because the concentration of the condensation-reactive functional group on the surface of the polymer fine particles can be easily controlled. In addition, in the production method, it is not easy to prepare a uniform size of the polymer fine particles in the case of suspension polymerization, and in the case of emulsion polymerization can be produced a very uniform size of the polymer fine particles, but to produce a fine particle of several micrometer size This is a hassle to go through a multi-step process. Therefore, it is preferable to prepare polymer microparticles through dispersion polymerization in that uniform polymer microparticles having a size of several micrometers can be easily manufactured in a single process.

The monomer for forming the polymer microparticles can be used without particular limitation as long as it can form the polymer microparticles in the form of beads usable in the art, and preferably hydrophobic vinyl compounds such as aromatic vinyl compounds and unsaturated carboxylic acid ester compounds. Can be used. Specific examples thereof include styrene, p-hydroxystyrene, p-acetoxystyrene, p-carboxystyrene, α-methylstyrene, α-chlorostyrene, p-tert-butylstyrene, and p-methylstyrene as the aromatic vinyl compound. , p-chlorostyrene, o-chlorostyrene, 2,5-dichlorostyrene, 3,4-dichlorostyrene, dimethyl styrene, divinylbenzene and the like can be used, and methyl acrylate, methyl as the unsaturated carboxylic acid ester compound Methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate and the like can be used. These may be used alone or in combination of one or more.

The auxiliary monomer may be a single molecule or a polymer material having a different polymerization degree from about 2000 to 200,000 in number average molecular weight, and among them, one or more, preferably two or more condensation-reactive functional groups. Specific examples thereof include p-hydroxy styrene, p-acetoxy styrene, p-carboxy styrene, methacryloxyethyl trimethylammonium chloride, Polyethylene glycol methyl methacrylate, polyethylene glycol methyl ether methacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate, polypropylene glycol dimethacrylate, and the like. These may be used alone or in combination of one or more thereof. The amount used is preferably 0.1 to 20% by weight, more preferably 1 to 2% by weight based on the total weight of the monomer for forming the polymer fine particles.

The crosslinking agent is lipophilic, such as styrene, acrylic, or methacryl, which is the same as the monomer used in the production of the polymer fine particles, and is a multifunctional having two or more vinyl groups as a crosslinking functional group in the unit. It is preferable to use a substance, and it is preferable that the usage-amount is 0.1-20 weight% with respect to the total weight of the said monomer, More preferably, it is 0.5-2 weight%.

Examples of the polymerization initiator include persulfate-based initiators such as calcium persulfate, ammonium persulfate and sodium persulfate; Peroxide initiators such as hydrogen peroxide, benzoyl peroxide and lauryl peroxide; And azo initiators such as azobisisobutyronitril (AIBN) and azobisporamide, and the amount of the azobis isobutyronitril may be used in the total weight of the monomer, auxiliary monomer, crosslinking agent, polymerization initiator and dispersant for forming the polymer fine particles. It is preferable that it is 0.01 to 10 weight% with respect to.

As the dispersant, polyvinylpyrrolidone, polyvinylacetate, hydroxypropyl-cellulose butyl acrylate, and the like may be used. The amount of the dispersant may be used in the total weight of the monomer for forming the polymer fine particles, the auxiliary monomer, the crosslinking agent, the polymerization initiator, and the dispersant. 1 to 2% by weight is preferred.

remind As a solvent, monomers for forming polymer fine particles and auxiliary monomers And if it can dissolve the initiator can be used without particular limitation, specific examples thereof include water, dimethylsulfoxide (DMSO), tetrahydrofuran (THF), dimethylformamide (DMF) or alcohol And polar solvents such as benzene, xylene, toluene or cyclohexane. Moreover, as said alcohol, C1-C10 Straight or branched alcohols may be used, preferably ethanol, methanol, isopropanol, propanol, butanol, pentanol, hexanol, heptanol, cyclohexanol Etc. can be used.

It is preferable that the reaction temperature at the time of monomer polymerization is 50-70 degreeC, and reaction time is 12-24 hours, but it is not limited to this.

Preferably, polystyrene-based, polymethacrylate-based, or polyacrylate-based polymer fine particles having a condensation-reactive functional group formed on the surface by polymerization by the above method can be used.

In addition, the polymer fine particles can be modified to any size that can be used commonly, and preferably has an average particle diameter of 0.1 to 10 ㎛.

Step 2

In step (2), a functional group capable of covalently bonding to the condensation functional group on the surface of the polymer fine particles is introduced to the surface of the graphene.

Specifically, functional groups such as -COOH, -COOR, -OH, -NH ₂ and -SH which can form covalent bonds with the condensation-reactive functional groups on the surface of the polymer fine particles on both the surface or the terminal, both the surface and the terminal of the graphene. Introduce.

Graphene usable in the present invention is not particularly limited to low crystallinity, high crystallinity, and the like, and may be purchased from a commercially available product, or may be prepared from graphite and used in a conventional manner.

Conventional methods for preparing graphene from graphite are largely divided into two methods, mechanical peeling and physicochemical peeling. The mechanical peeling method is to obtain graphene by using adhesive tapes commonly used for commonly used graphite, and to break the laminated structure of the graphite constituting the graphite by repeatedly attaching and peeling the adhesive tape on the graphite mass. to be. The physicochemical exfoliation method causes oxidation reaction between the surface of the graphite and the interlayer structure in the state of dispersing the graphite layer having the laminated structure in an appropriate solvent, thereby increasing the space between the layers and the hydroxyl group, Some of the polar functional groups such as carboxyl groups remain, or at the same time, the ionic functional groups are placed on the graphene surface to prevent the original laminated structure from being restored to the original laminated structure. The former method is simple but the yield is low in commercial evaluation, it is preferable in the present invention to use a graphene prepared using the latter method that can obtain a relatively large amount of graphene.

The method for modifying graphene to have a condensation-reactive functional group can be carried out by a conventional surface modification method using a raw material capable of providing a condensation-reactive functional group. The raw material may be used without particular limitation as long as it is a material capable of providing a condensation-reactive functional group. Specific examples thereof include hydrazine and ammonia in the case of the carboxyl group and the hydroxyl group, and methanol, It can be produced by further reacting an aliphatic alcohol such as n-hexanol or an aromatic alcohol such as benzyl alcohol or phenyl alcohol, and in the case of an amine group, a bifunctional amine compound such as hexamethylenediamine in the carboxyl group obtained above It can be produced by the reaction, in the case of a thiol group can be produced using H ₂ S and the like.

As a specific example of the graphene reforming method, when the graphene is modified to have a carboxyl group and a hydroxyl group, graphite is pulverized and oxidized to prepare graphite oxide, which is dispersed by sonication to obtain graphene oxide, and the graphene oxide As a raw material capable of providing a carboxyl group and a hydroxyl group on the surface, graphene having a carboxyl group and a hydroxyl group introduced on the surface can be prepared by treating hydrazine and ammonia.

At this time, the degree of progress of the reduction reaction on the surface of the graphene can be controlled by the mass ratio of hydrazine and ammonia used, thereby adjusting the concentration of the surface functional group of the graphene. If the reduction reaction proceeds a lot on the surface of the graphene, the surface functional group concentration decreases, thereby reducing the covalent bond with the polymer microparticles, thereby weakening the binding force, but reducing the defects on the surface of the graphene, thereby increasing the electrical conductivity. On the contrary, if the reduction reaction proceeds less, the concentration of the surface functional group is increased to increase the covalent bond with the polymer microparticles, thereby increasing the bonding strength, but the electrical conductivity cannot be obtained due to the increase of the graphene surface defects. Therefore, it is preferable that the weight ratio of hydrazine and ammonia is 1: 1 to 1:20, and the graphene having a covalently bonded functional group is optimized for cohesion and electrical conductivity through covalent condensation with functional groups on the surface of the polymer particles. It is more preferable that the weight ratio of hydrazine and ammonia is 1: 5-1: 8 in that it may have a point.

Step 3

Step (3) is a step of covalently attaching the graphene prepared in step (2) to the surface of the polymer particles prepared in step (1) to form a graphene coating layer.

More specifically, a dispersion in which polymer fine particles whose surface is modified to have a condensation-reactive functional group obtained in step (1) are dispersed, The graphene is coated on the surface of the polymer fine particles by covalently bonding the polymer fine particles and graphene by mixing a dispersion of graphene having a functional group capable of forming a covalent bond with the condensation-reactive functional group on the surface of the polymer fine particles. Produces conductive particles.

The dispersing medium which can be used to disperse the polymer fine particles and graphene is distilled water, isopropanol, ethanol, methanol, butanol, chloroform, diethyl ether, hexane, cyclohexane, propylene glycol monomethyl ether acetate, cyclotetrahydrofuran and methyl ethyl ketone Those selected from the group consisting of can be used alone or in combination.

In addition, the mixing ratio of the dispersion of the polymer fine particles and the graphene dispersion is preferably mixed in an amount such that the weight ratio of the polymer fine particles and the graphene is 20:80 to 85:15 in the final electrically conductive particles.

By the above manufacturing method, it is possible to produce electrically conductive particles of various sizes and shapes having excellent electrical conductivity with a simple manufacturing process and low manufacturing cost.

In addition, the electrically conductive particles produced by the manufacturing method as described above exhibits excellent electrical conductivity by including a graphene coating layer having excellent electrical conductivity on the surface of the polymer fine particles, and as a result, various mobile electronics such as mobile phones, liquid crystals It is advantageous for the application to the micropattern process which is essential for manufacturing high-end electronic devices such as a liquid crystal display (LCD) and various display devices such as an e-paper system. In addition, since the graphene is covalently attached to the polymer fine particles, it is possible to prevent cracking and peeling in the conductive layer caused by the difference in properties between the polymer fine particles and the metal, and also to prevent the Prevents cracks and improves durability. As a result, not only excellent electrical conductivity can be maintained for a long time, but also excellent heat resistance can maintain stable electrical conductivity even during the bonding process performed at a high temperature during semiconductor mounting or electronic circuit mounting process.

Due to the excellent physical properties as described above, the electrically conductive particles according to the present invention can be applied to the production of an anisotropic conductive film used as a packaging process connection material for electronic devices.

That is, according to another embodiment of the present invention can provide an anisotropic conductive film comprising the electrically conductive particles.

The anisotropic conductive film includes an electrically conductive particle and a thermosetting or thermoplastic insulating resin, and as the thermosetting or thermoplastic insulating resin, any of those commonly used may be used without particular limitation.

Hereinafter, the present invention will be described in more detail with reference to Examples, which are only intended to assist in understanding the configuration and operation of the present invention, and the scope of the present invention is not limited to these Examples.

Example  One

Step 1: Preparation of Polymer Fine Particles Having Condensation-Reactive Functional Groups

Polymeric microparticles having a hydroxyl group (-OH) as a condensation-reactive functional group on the surface were prepared in the following manner.

A mixed solvent of 200 mL of isopropanol and 10 mL of deionized water was added to a three-necked round bottom flask, and the temperature of the reactor was fixed at 70 ° C., followed by stirring at a speed of 400 rpm for 30 minutes under a nitrogen atmosphere. Herein, 5 mol of polyvinylpyrrolidone as a dispersant, 1 mol of styrene as a hydrophobic vinyl monomer, 0.5 mol of p-acetoxystyrene as an auxiliary monomer, and divinylbenzene as a crosslinking agent are 3 mol% based on the total weight of the monomer and the auxiliary monomer. After stirring for about 10 minutes, 1 g of azobisisobutyronitrile as a polymerization initiator was added to the reactor and polymerized for about 8 hours.

After the completion of the reaction, the mixture was quenched, and the obtained polymer fine particles were washed several times in the order of ethanol, methanol, and distilled water, and then stirred at room temperature for one day in a 10 mol% aqueous solution of NaOH to saponify the acetoxy group with a hydroxyl group. Then, the saponified particles were washed several times in the order of ethanol, methanol, and distilled water, and the solvent and particles were separated after washing the particles again using a centrifuge. The separated particles were freeze-dried to obtain polymer fine particles having a diameter of about 300 nm in powder form.

The polymer particles prepared in step 1 may be subjected to a subsequent process in a state in which the polymer particles are directly dispersed in a solvent without drying, but in the present embodiment, the precise particle size and shape of the polymer prepared are confirmed, and the mixing ratio with graphene For the calculation, the solvent was removed, dried, and obtained as powder particles, and then dispersed in DMF 200 mL at room temperature and used in the following procedure.

Step 2: modification and dispersion process of graphene

The graphite was pulverized for 10 minutes and then mixed with sulfuric acid (H ₂ SO ₄ ) and deionized water at a ratio of 1:50 and mixed for 2 hours, followed by oxidation with potassium permanganate (KMnO ₄ ). Distilled water was added at 70 degreeC, and it was made to react for 10 hours. Thereafter, an aqueous solution of hydrogen peroxide (H ₂ O ₂ ) was added thereto to obtain graphite oxide. The mixture was centrifuged, washed with hydrochloric acid (HCl) and distilled water, and dispersed by sonication for 2 hours to obtain graphene oxide. The reaction was terminated by adding hydrazine (N ₂ H ₂ ) and ammonia (NH ₃ ) to a solution mixed at a weight ratio of 1: 7 in an 80 ° C. reactor to graphene. In this case, the functional groups introduced into the graphene are a carboxyl group and a hydroxyl group, The presence of functional groups was confirmed by infrared spectroscopy, and the content of carboxyl and hydroxyl group functional groups on the surface was 0.02 mmol and 0.05 mmol, respectively, per mg of graphene.

Step 3: Graphene Coating Step

Polystyrene fine particles (0.9 g) of a hydroxy functional group, dispersed in 200 mL of DMF prepared in Step 1, 0.1 g of the surface-modified graphene prepared in step 2 was added to 200 mL of the dispersed DMF solution, followed by stirring at 100 ° C. for 24 hours at a speed of 100 rpm to coat the graphene on the polystyrene fine particles.

Confirmation of shape and covalent bonding of electrically conductive particles

The morphologies of the polystyrene fine particles prepared in Step 1 of Example 1 and the electrically conductive particles prepared in Step 3 were each observed with a field emission scanning electron microscope (SEM, JEOL. JSM 890). The results are shown in FIGS. 2 and 3, respectively.

As shown in Figure 2, it was confirmed that the polystyrene microparticles prepared in step 1 of Example 1 has a size of about 1 to 10 ㎛.

In addition, as shown in FIG. 3, it can be seen that the graphene is successfully coated on the surface of the polymer particles from the presence of a very dense curved surface of the surface of the electrically conductive particles.

In addition, the covalent bond ester bond (-COO-) obtained by the reaction between the -COOH functional group on the graphene surface and the -OH functional group on the polymer particle surface was confirmed through infrared spectroscopy, from which the polystyrene fine particles were It was confirmed that the graphene coating film was successfully formed on the surface through covalent bonding. At this time, the size of the graphene-coated electrically conductive particles was observed to be almost the same without being particularly distinguished from the size of the polystyrene fine particles because the thickness of the graphene coating layer was very thin.

Evaluation of Electrical Conductivity of Electrically Conductive Particles

The conductive polymer particles prepared in Example 1 were placed between two flat copper electrodes, and the electrical conductivity was measured by a four-probe method to determine the resistance value.

As a result of the experiment, the average value obtained by repeating the measurement 10 times was 600 mΩ / square. In the case of micropearl AU (Micropearl ^® AU, Sekisui Chemical Co., Ltd.), which is a gold-plated polymer fine particle, as a representative example of electrically conductive particles plated with metal based on a conventional polymer, the present invention considers that the average resistance value is 700 mΩ / □. It was confirmed that the electrically conductive particles prepared by have superior electrical conductivity equivalent to or higher than those of the metal-plated electrically conductive particles based on the conventional polymer.

1 is a schematic diagram showing a cross section of the electrically conductive particles formed according to the present invention.

2 is a scanning electron micrograph of the polymer fine particles prepared in Step 1 of Example 1.

3 is a scanning electron micrograph of the electrically conductive particles prepared according to Example 1.

<Description of the symbols for the main parts of the drawings>

A: polymer fine particles

B: covalent bond layer

C: graphene coating layer

Claims (22)

Polymer fine particles having a condensation-reactive functional group on the surface, and Graphene coating layer to which the graphene having a functional group capable of covalently bonding with the condensation-reactive functional group is attached to the surface of the polymer fine particles by covalent bonding Electrically conductive particles comprising a. The method of claim 1, The condensation-reactive functional group is a carboxyl group (-COOH), a hydroxyl group (-OH), an ester group (-COOR, wherein R is an alkyl, phenyl, or benzyl group having 1 to 10 carbon atoms), an amine group (-NH ₂ ) And thiol group (-SH) is electrically conductive particles, characterized in that at least one selected from the group consisting of. The method of claim 1, The functional group capable of covalently bonding to the condensation-reactive functional group is a carboxyl group (-COOH), a hydroxyl group (-OH), an ester group (-COOR, wherein R is an alkyl, phenyl or benzyl group having 1 to 10 carbon atoms) , An amine group (-NH ₂ ) and a thiol group (-SH) electrically conductive particles, characterized in that at least one selected from the group consisting of. The method of claim 1, Electrically conductive particles, characterized in that the covalent bond comprises an ester bond (-COO-), amide bond (-CONH-) or disulfide bond (-S-S-). The method of claim 1, Electrically conductive particles, characterized in that the polymer fine particles and graphene are included in a weight ratio of 20:80 to 85:15. The method of claim 1, Electrically conductive particles, characterized in that the polymer fine particles are polystyrene-based, polymethacrylate-based or polyacrylate-based polymer fine particles. The method of claim 1, Electrically conductive particles, characterized in that the electrically conductive particles have an average particle diameter of 0.1 to 10 ㎛. (1) preparing a polymer fine particle modified to have a condensation functional group on the surface, (2) introducing a functional group capable of covalently bonding to a condensation-reactive functional group on the surface of the polymer fine particles on the surface of graphene, and (3) covalently attaching the graphene prepared in step (2) to the surface of the polymer fine particles prepared in step (1) to form a graphene coating layer. The method of claim 8, The condensation-reactive functional group is a carboxyl group (-COOH), a hydroxyl group (-OH), an ester group (-COOR, wherein R is an alkyl, phenyl, or benzyl group having 1 to 10 carbon atoms), an amine group (-NH ₂ ) And thiol group (-SH) is a method for producing electrically conductive particles, characterized in that at least one selected from the group consisting of. The method of claim 8, The functional group capable of covalently bonding to the condensation-reactive functional group is a carboxyl group (-COOH), a hydroxyl group (-OH), an ester group (-COOR, wherein R is an alkyl, phenyl or benzyl group having 1 to 10 carbon atoms) , Amine group (-NH ₂ ) and thiol group (-SH) at least one member selected from the group consisting of the production method of the electrically conductive particles. The method of claim 8, The step of preparing the polymer microparticles modified to have a condensation functional group on the surface, dispersing and polymerizing the monomer for forming the polymer microparticles and optionally, an auxiliary monomer having one or more condensation functional groups in a solvent in the presence of a crosslinking agent, a polymerization initiator and a dispersant, A method for producing electrically conductive particles, which is carried out by emulsion polymerization or suspension polymerization. The method of claim 11, The monomer for forming the polymer fine particles is selected from the group consisting of aromatic vinyl compounds, unsaturated carboxylic acid ester compounds, and mixtures thereof. The method of claim 11, The auxiliary monomer having one or more condensation-reactive functional groups may be selected from p-hydroxystyrene, p-acetoxystyrene, p-carboxystyrene, methacryloxyethyl trimethylammonium chloride, In the group consisting of polyethylene glycol methyl methacrylate, polyethylene glycol methyl ether methacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate and polypropylene glycol dimethacrylate A method for producing electrically conductive particles, characterized in that at least one species is selected. The method of claim 11, The auxiliary monomer having at least one condensation-reactive functional group is used in the production of electrically conductive particles, characterized in that used in 0.1 to 20% by weight based on the total weight of the monomer for forming polymer fine particles. The method of claim 8, The step of introducing a functional group capable of covalently bonded to a condensation-reactive functional group on the surface of the graphene, characterized in that to obtain a graphene introduced carboxyl group and hydroxyl group by reducing the graphene oxide in a mixed solution of hydrazine and ammonia Method for producing electrically conductive particles. The method of claim 15, The mixing ratio of the hydrazine and ammonia is 1: 1 to 1:20 manufacturing method of the electrically conductive particles, characterized in that the weight ratio. The method of claim 15, The step of introducing a functional group capable of covalently bonding to the condensation-reactive functional group on the surface of the graphene, the introduction of a carboxyl group and a hydroxyl group on the surface of the graphene, and reacted with an aliphatic alcohol or an aromatic alcohol to introduce the graphene Method for producing the electrically conductive particles, characterized in that it further comprises the step of obtaining. The method of claim 15, The step of introducing a functional group capable of covalently bonding to the condensation-reactive functional group on the surface of the graphene, after the introduction of the carboxyl group and hydroxyl group on the surface of the graphene, reacted with the bifunctional amine compound graphene introduced amine group Method for producing the electrically conductive particles, characterized in that it further comprises the step of obtaining. The method of claim 8, The step of introducing a functional group capable of covalently bonded to a condensation-reactive functional group on the surface of the graphene, the method for producing electrically conductive particles, characterized in that the graphene oxide is introduced with H ₂ S to obtain a thiol group introduced graphene . The method of claim 8, The forming of the graphene coating layer may include: a dispersion in which polymer fine particles having a surface modified to have a condensation-reactive functional group are dispersed; And a covalent bond between the polymer fine particles and graphene by mixing a dispersion of graphene having a functional group capable of forming a covalent bond with a condensation-reactive functional group on the surface of the polymer fine particles. 21. The method of claim 20, The polymer fine particle dispersion and the dispersion of the graphene is a method for producing electrically conductive particles, characterized in that the weight ratio of the polymer fine particles and the graphene in the final conductive conductive particles are mixed in an amount of 20:80 to 85:15. . Anisotropic conductive film comprising the electrically conductive particles according to claim 1.

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