WO2020032403A1

WO2020032403A1 - Conductive composite using conductive composite solution, and method for producing same

Info

Publication number: WO2020032403A1
Application number: PCT/KR2019/008533
Authority: WO
Inventors: 정운룡; 조성환; 송준혁; 공민식
Original assignee: 포항공과대학교 산학협력단
Priority date: 2018-08-10
Filing date: 2019-07-11
Publication date: 2020-02-13
Also published as: KR20200018025A

Abstract

The present invention relates to a conductive composite solution comprising: conductive nanoparticles; thermoplastic rubber; and a solvent. A conductive composite, according to the present invention, uses the conductive composite solution, according to the present invention, and thus a separate stretchable substrate does not have to be prepared, and an effect is achieved of exhibiting excellent double-sided conductivity, stretchability and adhesion, and in addition, a method for producing the conductive composite, according to the present invention, has an effect whereby the conductive composite may be produced into various forms (film or wire, etc.) through low production costs and a simple process that does not require additional processes.

Description

Conductive Composite Using Conductive Composite Solution and Manufacturing Method Thereof

The present invention relates to a conductive composite using a conductive composite solution and a method for manufacturing the same, and more particularly, by using the conductive composite solution according to the present invention, without having to prepare a stretchable substrate separately, it has a double-sided conductivity, elasticity and adhesion The present invention relates to various types of conductive composites and a method of manufacturing the same.

As the field of application of electronic devices expands, there is a growing demand for flexible electronic devices that can overcome the limitations of electronic devices existing on conventional rigid substrates. Electronic devices used in applications such as flexible displays, smart garments, dielectric elastomer actuators (DEAs), biocompatible electrodes, and in vivo electrical signal sensing require flexible and flexible forms. One of the basic and important techniques in the field of flexible and stretchable electronic devices is to form a stretchable electrode while maintaining conductivity.

Materials such as metals have excellent conductivity but are hard to utilize as they are due to their hard and stiff properties. When using materials such as carbon nanotubes or graphene alone, it is also difficult to make flexible electrodes.

As a method for making a stretchable electrode, a carbon nanotube, a transparent fluorinated polymer, an ionic liquid is prepared in paste form, a metal particle and polyacrylic acid mixture is formed in a paste form, and an inkjet method is used to make a pattern. An example of forming a metal layer on a PDMS substrate to have elasticity as much as wrinkles are spread has been reported. However, these methods have a problem such that the conductivity of the used material or the corrugated substrate is not large and the conductivity is sharply lowered or mechanically broken according to the stretching.

In addition, looking at the research trend of silver-based stretchable conductors, in the case of stretchable conductors using silver nanowires or silver nanoparticles, there is an advantage that a stretchable conductor can be made of a relatively inexpensive material, but basically a silver nano-based material In case of continued repeated test, it was very difficult to maintain the initial conductivity. In addition, most of the conductors lost their conductivity when 100% high stretching was applied, and previous studies have required complicated experiments, such as fabricating and preparing substrates and conductors separately and combining the two materials into one. There was a problem.

An object of the present invention is to solve the above problems, by using a conductive composite solution according to the present invention, without having to prepare a flexible substrate separately, the conductivity of various forms (film or wire, etc.) with double-sided conductivity, stretchable and tacky To provide a complex.

In addition, the present invention provides a method for producing a conductive composite that can be produced through a simple process that does not require low production costs and additional processes.

According to an aspect of the invention, the conductive nanoparticles; Thermoplastic rubber; And a solvent; there is provided a conductive composite solution.

The conductive nanoparticles may include one or more selected from silver (Ag), gold, aluminum, copper, platinum, palladium, tin, carbon nanotubes (CNT), and silicon.

The conductive nanoparticles may include silver (Ag).

The silver (Ag) may be in the form of any one selected from flakes, wires, spheres, and combinations thereof.

The thermoplastic rubber may include one or more selected from styrenic block copolymers, polyurethanes, and PDMS.

The styrene block copolymer is SBS (poly (styrene-butadiene-styrene)), SIS (poly (styrene-isoprene-styrene)), SEBS (poly (styrene-ethylene / butylene-styrene)), SEPS (poly (styrene) -ethylene-propylene-styrene)) and SBBS (poly (styrene-butadiene-butylene-styrene)) may include one or more selected.

The solvent is tetrahydrofuran (THF), toluene (Toluene), chloroform (Chloroform), pentane (Pentane), hexane (Hexane), heptane (Octane), methyl pentane (Methylpentane), cyclophene It may include one or more selected from among cyclopentane, cyclohexane, methylcyclohexane, benzene, benzene, ethylbenzene, and xylene.

The thermoplastic rubber may be 5 to 100 parts by weight based on 100 parts by weight of the conductive nanoparticles.

According to another aspect of the present invention, there is provided a conductive composite prepared by drying a solvent in a conductive composite solution containing conductive nanoparticles, a thermoplastic rubber and a solvent.

The conductive composite may be any one selected from fiber, wire, and film.

Modulus of the conductive composite may be 0.3 to 1.5 Gpa.

Peel strength of the conductive composite may be 10 to 2500 N / m.

The conductive composite may be used as any one selected from an adhesive tape, an electrode, an interconnection circuit, and a shielding film.

According to another aspect of the invention, (a) mixing the conductive nanoparticles, thermoplastic rubber and a solvent to prepare a conductive composite solution; And (b) molding the conductive composite solution into a film, wire, or flake form; And (c) drying the solvent in the molded conductive composite solution to prepare a conductive composite.

The thermoplastic rubber may be 5 to 100 parts by weight based on 100 parts by weight of the conductive nanoparticles in step (a).

In step (a), the thermoplastic rubber may be 10 to 30 parts by weight based on 100 parts by weight of the conductive nanoparticles.

In step (b) the molding can be any one selected from casting, spin coating, dip coating, screen printing, nozzle printing, spinning and spraying.

The shape and thickness of the conductive composite may be controlled according to one or more selected from the type of the solvent and the concentration of the conductive composite solution.

By using the conductive composite solution according to the present invention, the conductive composite of the present invention does not need to separately prepare a stretchable substrate, and has excellent effects on both sides of conductivity, stretchability and adhesion.

The conductive composite of the present invention can be produced in various forms (film or wire, etc.) by using the conductive composite solution according to the present invention.

In addition, the manufacturing method of the conductive composite of the present invention has the effect that can be produced through a simple process that does not require a low production cost and additional processes.

1 is a schematic view showing the configuration of a conductive composite solution of the present invention.

2 is an image showing a patterned conductive composite prepared according to Example 3. FIG.

3 is an SEM image of a conductive composite prepared according to Example 1. FIG.

4 is a roughness measurement result of the conductive composite prepared according to Example 1.

5 is a result of comparing the resistance (conductivity) according to the stretchability of the conductive composite prepared according to Example 1.

6 is a strain-stress curve of a conductive composite prepared according to Example 1. FIG.

7 is an optical microscope (OM) image of the conductive composite prepared according to Example 2. FIG.

8A and 8B are SEM images of the conductive composite prepared according to Example 2. FIG.

9 is a current-voltage curve of a conductive composite prepared according to Example 2. FIG.

10 is a photograph showing a process of attaching two films by applying a heat source to the conductive composite prepared according to Example 1.

11 is a photograph showing a process of attaching two films using body temperature and pressure to the conductive composite prepared according to Example 4.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

However, the following descriptions are not intended to limit the present invention to specific embodiments, and detailed descriptions of well-known techniques related to the present invention will be omitted when it is determined that the present invention may obscure the gist of the present invention. .

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, or combination thereof described in the specification, and one or more other features or It should be understood that the present invention does not exclude the possibility of adding or presenting numbers, steps, operations, components, or a combination thereof.

1 is a schematic view showing the configuration of a conductive composite solution of the present invention. Hereinafter, the conductive composite solution and the conductive composite of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

The present invention is a conductive nanoparticle; Thermoplastic rubber; It provides a conductive complex solution comprising a; and a solvent.

The conductive nanoparticles may include at least one selected from silver (Ag), gold, aluminum, copper, platinum, palladium, tin, carbon nanotubes (CNT), and silicon, and preferably include silver (Ag). can do.

The silver (Ag) may be in the form of any one selected from flakes, wires, spheres, and combinations thereof, and preferably silver flakes having a flake structure.

In general, silver is cheaper than other precious metals and is manufactured in various forms (nanowires and nanoparticles) and is applied to various industrial fields. Silver is an easy-to-purchase material that can be used immediately without additional processing.

The thermoplastic rubber may include at least one selected from a styrenic block copolymer, polyurethane, and PDMS.

The styrenic block copolymer is a block copolymer of styrene and diene, and two separate phases exist. Each phase consists of repeating parts of the same molecule. The simplest arrangement is an A-B-A or triblock structure, where A represents a hard copolymer block and B represents a soft block. Therefore, the hard block acts as a skeleton, the soft block is a polymer that can be stretched to increase the stretchability. The most commonly used dienes are butadiene (S-B-S), isoprene (S-I-S) and ethylene (S-EB-S).

The solvent is tetrahydrofuran (THF), toluene (Toluene), chloroform (Chloroform), pentane (Pentane), hexane (Hexane), heptane (Octane), methyl pentane (Methylpentane), cyclophene It may include one or more selected from among cyclopentane, cyclohexane, methylcyclohexane, benzene, benzene, ethylbenzene, and xylene, but the solvent may include Any solvent capable of dissolving the styrenic block copolymer can be used, and the scope of the present invention is not limited thereto.

The conductive composite solution of the present invention can be manufactured in a desired form (film or wire or other form) using the conductive composite solution without separately preparing a conductor and a flexible substrate. The solvent to be used is not fixed, so that any solvent capable of dissolving the polymer can be used in a variety of applications, and the concentration of the conductive complex solution is also irrelevant.

The present invention provides a conductive composite prepared by drying a solvent in a conductive composite solution containing conductive nanoparticles, a thermoplastic rubber and a solvent.

The conductive composite may be any one selected from fiber, wire, and film.

Modulus of the conductive composite may be 0.3 to 1.5 GPa, preferably 0.7 to 1.4 GPa, more preferably 1 to 1.3 GPa.

Peel strength of the conductive composite may be 10 to 2500 N / m, preferably 20 to 2300 N / m, more preferably 40 to 2100 N / m.

Since the conductive composite is viscoelastic, including a thermoplastic rubber (styrene-based block copolymer), heat can be applied to the polymer chain in the conductive composite. Therefore, according to the substrate to be attached through this can be utilized as an adhesive tape having a degree of adhesiveness that can be completely attached from the post-it level of 3M company. For example, when the conductive composite is attached through a simple heat treatment, the adhesive may be attached at a strength similar to that of a tape, and chemically through the O ₂ plasma process may be more strongly attached than a simple heat treatment.

When the conductive composite is manufactured in the form of a film, the roughness is low, and it can be utilized as a very flat stretchable electrode.

The conductive composite may be utilized as a self-healing conductive material recoverable to a heat source such as an iron or a dryer.

In addition, the conventional conductor proceeds with a process of raising a conductive layer on a stretchable substrate. However, this method has only one side in terms of the entire substrate, and thus has only one conductivity. The surface roughness caused by the conductor on the surface increases sharply. Will follow. However, in the case of the present invention, since the conductive composite itself made of the conductive composite solution exhibits conductivity, it has conductivity while maintaining the properties of the styrene-based block copolymer. Therefore, it has the advantage of having conductivity on both sides, so it can be actively used in the field requiring interconnection on the z-axis.

Hereinafter, a method of manufacturing the conductive composite of the present invention will be described in detail.

First, a conductive composite solution is prepared by mixing conductive nanoparticles, a thermoplastic rubber, and a solvent (step a).

In step (a), the thermoplastic rubber may be 5 to 100 parts by weight, and preferably 10 to 30 parts by weight based on 100 parts by weight of the conductive nanoparticles.

The conductive composite solution makes a solution based on the ratio of the thermoplastic rubber and the conductive nanoparticles. Since the weight ratio of the thermoplastic rubber and the conductive nanoparticles is 1: 3, the conductivity of the conductive composite solution is shown, and the concentration of the solution can be adjusted to suit the desired process.

Next, the conductive composite solution film, wire , flake Mold into shape (step b).

In step (b) the molding can be any one selected from casting, coating, printing, spinning and spraying.

The coating may include one or more selected from spin coating, slot coating, dip coating, bar coating, roll coating, gravure coating, microgravure coating, wire coating and spray coating.

The printing may include at least one selected from inkjet printing, nozzle printing, screen printing, flexo printing, and offset printing.

The spinning may comprise one or more selected from melt spinning, dry spinning, wet spinning and electrospinning.

Finally, Molded Solvent in the conductive composite solution Drying Prepare the conductive composite (step c).

EXAMPLE

Hereinafter, a preferred embodiment of the present invention will be described. However, this is for illustrative purposes and the scope of the present invention is not limited thereto.

Example 1: conductive composite in film form

10 wt% of polystyrene-butadiene-styrene (SBS, (poly (styrene-butadiene-styrene)), 9003-55-8, sigma aldrich) was dissolved in chloroform, and SBS: Silver flake , 7440-22-4, sigma aldrich) weight ratio of 1: 5 was prepared to prepare a conductive composite solution, by the spin coating method to prepare a conductive composite in the form of a film having a thickness of 20um level.

Example 2: fiber-like conductive composite

After dissolving 10 wt% of polystyrene-butadiene-styrene (SBS) in tetrahydrofuran (THF), THF: conductive material was added so that the weight ratio of silver flakes was 1: 5. The composite solution was prepared, and a conductive composite in the form of fiber was prepared by the method of electrospinning.

Example 3: Patterned Conductive composite

After dissolving 10 wt% of polystyrene-butadiene-styrene (SBS) in chloroform, SBS: conductive composite solution was added so that the weight ratio of silver flakes was 1: 5. And a conductive composite patterned by screen printing on a substrate using a pattern mask. Figure 2 is a photograph showing the appearance of the patterned conductive composite prepared according to Example 3.

Example 4: conductive composite in film form

Chloroform in polystyrene-butadiene-styrene (SBS, polystyrene-butadiene-styrene) and polystyrene-isoprene-styrene (SIS), 25038-32-8, Sigma Aldrich) was dissolved 10wt% to a ratio of 1: 4, and then (SBS + SIS): silver flake (Silver flake) was added so that the weight ratio of 1: 5 to prepare a conductive composite solution, by spin coating method 20um A conductive composite in the form of a film with a level thickness was prepared.

[Test Example]

Test Example 1: of a conductive composite made of a film SEM image

Referring to FIG. 3, it was found that silver flakes (conductive materials) were uniformly distributed in the styrene block copolymer (extensible body) to form a conductive network.

Test Example 2: of the conductive composite made of film Roughness (Roughness) measurement

Referring to FIG. 4, when the conductive composite solution itself is made of a film (thin film) (Example 1), roughness is 10 nm or less, which is very low compared to other electrodes.

Therefore, it is very soft when touched by hand and has a great advantage to use as an electrode material. Considering the roughness of electrodes that have been studied in the past, it is generally possible to use it as an extremely flat stretchable electrode, considering that the roughness is generally about 30-50 nm.

Test Example 3: Electrical Characterization of Conductive Composites Made of Film

Figure 5 is a graph measuring the resistance change according to the stretchability of the conductive composite prepared according to Example 1.

Referring to FIG. 5, the change in resistance in stretching within about 50% maintains a very low resistance from 4 ohms to 10 ohms, and does not show a big difference from the initial state.

Thus, when the conductive composite is prepared using the conductive composite solution of the present invention, it was found that the conductivity is maintained without losing the conductivity.

Test Example 4: Mechanical Characterization of Conductive Composites Made of Film

6 is a strain-stress curve of a conductive composite prepared according to Example 1. FIG. A film of 1 × 3 cm ² area was used.

In addition, the tensile stress and strain at break (%) of the conductive composite prepared according to Example 1 in the form of a film was measured by drawing a stress-strain curve and analyzing the same while pulling at a constant rate of 100 μ / s. The average value of the remaining measured values except the highest value and the lowest value by measuring 10 times is shown in Table 1 below.

	모듈러스 (GPa)Modulus (GPa)	파단신도(strain at break, %)Elongation at break (%)
실시예 1Example 1	1.21.2	2500 %2500%

Referring to FIG. 6, the conductive composite (film) prepared according to Example 1 was maintained unbroken even at about 500% or more of stretching, and maintained at about 50% of stretching based on such mechanical properties. Could.

In addition, referring to Table 1, it was found that the modulus and elongation at break of the conductive composite prepared according to Example 1 were not easily broken even when the film was pulled.

Therefore, it is determined that the conductive composite prepared according to Example 1 may be used as an extensible electrode.

Test Example 5: of the conductive composite made of fiber SEM And OM image

7 is an optical microscope (OM) image of the conductive composite prepared according to Example 2, Figures 8a and 8b are SEM images of the conductive composite prepared according to Example 2.

7, 8a and 8b, it was possible to make a fiber from the thickness of 5um to 100um level, it can be seen that also in the form of a porous film using this.

Test Example 6: Electrical Characterization of Conductive Composites Made of Fiber

Referring to FIG. 9, it can be seen that the current increases constantly as the voltage increases, which causes the electrode to have ohmic behavior.

Test Example 7: adhesive analysis

FIG. 10 is a photograph showing a process of attaching two films by applying a heat source to the conductive composite prepared according to Example 1, and FIG. 11 shows two films using body temperature and pressure on the conductive composite prepared according to Example 4. This is a picture showing the attaching process.

10 and 11, the conductive composite in the form of a film prepared according to Example 1 was cut and overlapped with '+', and the overlapping portions were contacted with a heat source, and the overlapping portions were sufficiently adhered. Therefore, it was found that the conductive composite according to the present invention can be adhered to a desired shape by using a heat source (ex: iron) that can be easily used in real life (FIG. 10). In addition, by varying the composition of the polymer used, both ends of the conductive composite in the form of a film prepared according to Example 4 were overlapped in a ring shape, and after pressing with a finger, it was confirmed that the overlapped portions were sufficiently adhered to the stretch. Therefore, the conductive composite according to the present invention could simply adhere to the desired shape using the body temperature and pressure (Fig. 11).

Therefore, it can be seen that the conductive composite including the conductive composite solution according to the present invention can be attached to a desired place using adhesiveness, and self repair or extension or shape molding can be performed.

Test Example 8: Peel strength and mechanical properties

Peel strength of the conductive composite prepared according to Example 1 was measured and shown in Table 1 below.

At this time, the peel strength was measured by the method of 90 ° peeling test the two films attached to before and after heat treatment and before and after O ₂ plamsa.

	박리강도 (N/m)Peel Strength (N / m)
	열처리 전Before heat treatment	열처리 후After heat treatment
O₂ plasma 전O ₂ plasma before	50 N/m50 N / m	150 N/m150 N / m
O₂ plasma 후After O ₂ plasma	2000 N/m2000 N / m	2000 N/m2000 N / m

Referring to Table 2, it can be seen that the adhesive strength increases when the two films prepared according to Example 1 are attached after heat treatment or O ₂ plasma treatment.

The scope of the present invention is indicated by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Claims

Conductive nanoparticles;

Thermoplastic rubber; And

Solvent;

Conductive composite solution containing.
The method of claim 1,

The conductive nanoparticles include at least one selected from silver (Ag), gold, aluminum, copper, platinum, palladium, tin, carbon nanotubes (CNT) and silicon.
The method of claim 1,

The conductive nanoparticles are conductive composite solution, characterized in that containing silver (Ag).
The method of claim 3,

The silver (Ag) is a conductive composite solution, characterized in that any one selected from flakes, wires, spheres and combinations thereof.
The method of claim 1,

A conductive composite solution, characterized in that the thermoplastic rubber comprises one or more selected from styrenic block copolymer, polyurethane and PDMS.
The method of claim 1,

The styrene block copolymer is SBS (poly (styrene-butadiene-styrene)), SIS (poly (styrene-isoprene-styrene)), SEBS (poly (styrene-ethylene / butylene-styrene)), SEPS (poly (styrene) -ethylene-propylene-styrene)) and SBBS (poly (styrene-butadiene-butylene-styrene)) conductive composite solution comprising at least one selected from.
The method of claim 1,

The solvent is tetrahydrofuran (THF), toluene (Toluene), chloroform (Chloroform), pentane (Pentane), hexane (Hexane), heptane (Octane), methylpentane (Methylpentane), cyclophene Conductive complex solution comprising at least one selected from among cyclopentane, cyclohexane, methylcyclohexane, benzene, benzene, ethylbenzene and xylene .
The method of claim 1,

The conductive composite solution, characterized in that the thermoplastic rubber is 5 to 100 parts by weight based on 100 parts by weight of the conductive nanoparticles.
A conductive composite prepared by drying a solvent in a conductive composite solution containing conductive nanoparticles, a thermoplastic rubber, and a solvent.
The method of claim 9,

Form of the conductive composite is a conductive composite, characterized in that any one selected from fiber (wire), wire and film.
The method of claim 9,

The conductive composite, characterized in that the modulus of the conductive composite is 0.3 to 1.5 Gpa.
The method of claim 9,

A conductive composite, characterized in that the peel strength of the conductive composite is 10 to 2500 N / m.
The method of claim 9,

The conductive composite is a conductive composite, characterized in that for use in any one selected from the adhesive tape, the electrode, the interconnection circuit and the shielding film.
(a) mixing a conductive nanoparticle, a thermoplastic rubber, and a solvent to prepare a conductive composite solution;

(b) forming the conductive composite solution into a film, wire, or flake form; and

(c) drying the solvent in the formed conductive composite solution to prepare a conductive composite;

Method for producing a conductive composite comprising.
The method of claim 14,

The method for producing a conductive composite, characterized in that 5 to 100 parts by weight of the thermoplastic rubber relative to 100 parts by weight of the conductive nanoparticles in step (a).
The method of claim 15,

The method for producing a conductive composite, characterized in that the thermoplastic rubber is 10 to 30 parts by weight based on 100 parts by weight of the conductive nanoparticles in step (a).
The method of claim 14,

The method of manufacturing a conductive composite, characterized in that the molding in step (b) is any one selected from casting, spin coating, dip coating, screen printing, nozzle printing, spinning and spraying.
The method of claim 14,

Form and thickness of the conductive composite is controlled according to at least one selected from the type of the solvent and the concentration of the conductive composite solution.