KR20090111493A - An electroconductive sheet with self-adhesiveness and a method for manufacturing of the same - Google Patents

Abstract

PURPOSE: An electroconductive sheet with self-adhesive force and a method for manufacturing the same are provided to exhibit high conductivity, flexibility, adhesion force, leveling properties, durability, and scratch resistance. CONSTITUTION: An electroconductive sheet(100) with self-adhesive force is produced by filling a thermally adhesive polymer rein with conductive filler(200). The thermally adhesive polymer rein is to be fused by the heat and have adhesive force. The thermally adhesive polymer rein is selected from the group consisting of polyurethane resin, polyethylene resin, poly propylene resin, polystyrene resin, polyvinyl chloride resin, chlorinated polyethylene resin, polyester resin, ethylene vinyl acetate(EVA) resin, epoxy resin, phenolic resin, and their mixture. The conductive filler is selected from the group consisting of copper, nickel, gold, silver, aluminium, carbon, silver-plated nickel, silver-plated copper, nickel-plated copper, nickel-plated graphite, and silver-plated glass.

Description

A conductive sheet having self-adhesiveness and a method of manufacturing the same {AN ELECTROCONDUCTIVE SHEET WITH SELF-ADHESIVENESS AND A METHOD FOR MANUFACTURING OF THE SAME}

The present invention relates to a conductive sheet in the form of a thin film having self adhesiveness and a method for producing the same, wherein the thermally adhesive polymer resin is filled with a conductive filler.

The present invention also provides a flexible printed circuit (substrate) and an antenna for a wireless tag using a thin film-type electromagnetic wave absorbing / shielding material including a thin film-shaped conductive sheet having self adhesiveness and a conductive sheet of a thin film having self adhesiveness. It is about.

Conventionally, in order to impart electroconductivity (conductivity), an electrically conductive sheet or film is first prepared, and then an adhesive or an adhesive is attached thereto, or a conductive adhesive or an adhesive is attached for the purpose of realizing higher electrical conductivity. However, in this case, it was not only difficult to apply to the conductive sheet having a thin film form of 50 μm or less, but also there was a troublesome process in that the release paper was removed after the adhesive or the adhesive was attached and the adhesive sheet was attached again to the bonding site. Moreover, when using a conductive adhesive or an adhesive, there existed a problem with high production cost.

In addition, it is possible to impart electrical conductivity by using a conductive adhesive or an adhesive without an electrically conductive sheet or film, but in this case, the filling rate of the conductive filler could not be increased and the required electrical conductivity could not be secured. Or there was a problem that the other side of the surface opposite the adhesive is to be treated with another substrate.

In addition, instead of the electroconductive sheet or the film may be used by adhesive or adhesive treatment on one surface of the metal thin film (metal foil), in this case, there is a disadvantage in that the flexibility and processability due to the metal thin film and the thin film is difficult to implement.

In addition, one surface of the plated conductive fabric may be used by hot melt or adhesive treatment, but in this case, the thickness is thick, and it is difficult to obtain a required smoothness, and the manufacturing process is complicated and the production cost increases. . Some products have a conductive filler filled with a hot melt to impart conductivity, but in order to impart a desired adhesive property, the filler cannot have a high filling rate, and thus, it is difficult to realize conductive performance.

In addition, there is a method of spraying a conductive solution, but since it must be sprayed directly to the required area, the material or product to be applied is limited, and if only a part of the product is to be electrically conductive, the remaining part is covered and sprayed. In addition, to obtain a product in the form of a film having a predetermined electrical conductivity required, there was a problem that only expensive conductive fillers should be used.

On the other hand, Korean Utility Model Publication No. 328855 describes a "conductive heat-adhesive film in which a plurality of conductive mesh wires woven with wires and impregnated with a conductive polymer resin are impregnated with a conductive polymer resin and formed into a sheet shape. Due to the poor post-processability, due to the thickness of the woven wire it is impossible to manufacture a thin film, due to the irregularities of the surface due to the woven fabric has a low smoothness, the adhesive strength also has a disadvantage.

Accordingly, the present inventors, after earnestly researching, filled a thermally adhesive polymer resin with a conductive filler, thereby providing a thin film having excellent properties such as self-adhesiveness, electrical conductivity, flexibility, smoothness, durability, scratch resistance, etc. without using an adhesive or an adhesive. The electroconductive sheet of the form was created.

The present invention can be produced in a thin film, can be directly attached to the application site without the use of pressure-sensitive adhesives or adhesives, conductive sheet having excellent self-adhesiveness excellent in electrical conductivity, flexibility, adhesion, smoothness, durability, scratch resistance, etc. It is an object of the present invention to provide a method for producing a conductive sheet having a self-adhesive property capable of providing a simplification and a reduction in cost and cost reduction.

The present invention is melted by heat and has adhesiveness, and includes polyurethane resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, chlorinated polyethylene resin, polyester resin, polybutyral chloride resin, ethylene vinyl acetate (EVA ) Copper, nickel, gold, silver, aluminum, carbon, silver plated nickel, silver plated copper, nickel plated copper, nickel plated to a heat-adhesive polymer resin selected from the group consisting of resins, epoxy resins, phenol resins or combinations thereof Provided is a self-adhesive thin film conductive sheet, characterized in that a granular, spherical, dendritic or flake conductive filler selected from the group consisting of graphite and silver plated glass is filled.

Heat-adhesive polymer resin serves as a binder to melt by heat to have an adhesive, the material is a polyurethane resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, chlorinated polyethylene resin It is preferable that it is a polyester resin, a polybutyl butyral resin, ethylene vinyl acetate (EVA) resin, an epoxy resin, a phenol resin, or a combination thereof.

The conductive filler serves to impart electrical conductivity (conductivity) by filling in the heat-adhesive polymer resin. Copper, nickel, gold, silver, aluminum, carbon, silver plated nickel, silver plated copper, nickel plated copper, nickel plated graphite And granular, spherical, dendrite or flake conductive fillers selected from the group consisting of silver plated glass. In order to give the electrical conductivity (surface resistance) of 5x10 <^-1> Pa / sq or less in 50 micrometers or less thin films, it is more preferable that it is flake type silver plating copper.

It is preferable that the average particle diameter of an electroconductive filler is 30-50 micrometers. If the average particle diameter is less than 30㎛, it is necessary to fill more conductive fillers to obtain the same conductivity, and if the average particle diameter exceeds 50㎛ it is difficult to manufacture the conductive sheet in a thin film form.

It is preferable that the filling rate of the conductive filler is 60 to 80%, when it exceeds 80%, it is difficult to manufacture the conductive sheet in a thin film form, and when it is less than 60%, sufficient electric conductivity (conductivity) cannot be secured.

The conductive sheet in the form of a thin film having a self-adhesive property according to the present invention has a thickness of 50 μm or less, and a surface resistance of 5 × 10 ⁻¹ dl / sq or less.

In addition, the present invention is a method for producing a conductive sheet in the form of a thin film having self-adhesion, (a) polyurethane resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, chlorinated polyethylene resin, polyester resin , A thermally adhesive polymer resin selected from the group consisting of polybutyral chloride resins, ethylene vinyl acetate (EVA) resins, epoxy resins, phenol resins or combinations thereof may be selected from the group consisting of dimethylformamide (DMF), toluene and methyl ethyl ketone (MEK). Granules selected from the group consisting of copper, nickel, gold, silver, aluminum, carbon, silver plated nickel, silver plated copper, nickel plated copper, nickel plated graphite, and silver plated glass after dissolving in a mixed solvent of Homogeneously dispersing a spherical, dendritic or flake conductive filler to prepare a self-adhesive conductive liquid; (b) casting the self-adhesive conductive liquid onto a substrate; And (c) drying the cast self-adhesive conductive liquid to evaporate the solvent, thereby forming a conductive sheet in the form of a thin film having self-adhesiveness.

Step (a) is followed by dissolving a heat-adhesive polymer resin (e.g., heat-adhesive polyurethane resin) in a mixed solvent of dimethylformamide (DMF), toluene and methyl ethyl ketone (MEK), and then having an average particle diameter of 30-50 mu m. The conductive filler (preferably, flake-type silver-plated copper) is dispersed to prepare a self-adhesive conductive liquid filled with a thermally conductive polymer resin at a filling rate of 60 to 80%.

Step (b) is the step of casting the self-adhesive conductive liquid to a certain thickness on the substrate (eg PET film). Casting is preferably performed by comma coating, spin coating, gravure printing, reverse roll coating or screen printing, but is not limited to these methods.

Step (c) is to dry the cast self-adhesive conductive liquid to evaporate the solvent, thereby forming a conductive sheet in the form of a thin film having self-adhesion which is the final product.

In addition, the present invention provides a thin film type electromagnetic wave absorbing / shielding material including the above-described conductive sheet of a thin film type having self adhesiveness.

The electromagnetic wave absorbing / shielding material preferably has an electromagnetic shielding rate of at least 50 dB (99.72% shielding) in the frequency band of 10 MHz to 1 GHz.

The conductive sheet having the self-adhesiveness of the present invention does not need to use an adhesive or an adhesive and can be manufactured in a thin film, and has an advantage of excellent electrical conductivity, flexibility, adhesion, smoothness, durability, scratch resistance, and the like. Moreover, the manufacturing method of the electroconductive sheet which has the self-adhesive property of this invention can simplify a process and reduce cost.

Further, according to the present invention, it is possible to economically mass-produce the electromagnetic wave absorbing / shielding material in the form of a thin film including a conductive sheet having self-adhesiveness, as well as a pattern in manufacturing an antenna or a flexible printed circuit (substrate) of a radio tag. Can be easily formed.

Through the following examples will be described in more detail the present invention. However, the following examples are only for illustrating the present invention, and the scope of the present invention should not be construed as being limited to the following examples. Therefore, it will be understood by those skilled in the art that various modifications, modifications and applications of the following embodiments are possible within the scope of the technical idea derived from the matters described in the appended claims.

Example  One

After dissolving the heat-adhesive polyurethane resin in a mixed solvent of dimethylformamide (DMF), toluene and methyl ethyl ketone (MEK), flake silver-plated copper (silver content: 10%) having an average particle diameter of 33 μm was dispersed (A small amount of dispersant may be used for homogeneous dispersion.) A self-adhesive conductive liquid filled with a heat-adhesive polymer resin at a filling rate of 70% was prepared. Subsequently, the self-adhesive conductive liquid was cast on a substrate (eg, PET film) at a constant thickness. Casting was carried out by a comma coating method. Subsequently, the cast self-adhesive conductive liquid was dried to evaporate the solvent, thereby forming a conductive sheet in the form of a thin film having self-adhesiveness.

Properties of thermal conductivity, thickness, adhesion (adhesiveness after heat bonding to a polyimide film by applying a heat of 130 ° C.), flexibility, and the like, of a thin-film conductive sheet having final self-adhesion properties are shown in Table 1 below. .

Example  2

It is the same as Example 1 except the filling rate of the flake type silver plating copper (conductive filler) is 55%.

Example  3

It is the same as Example 1 except the filling rate of the flake type silver plating copper (conductive filler) is 85%.

Example  4

The flake type silver plated copper (conductive filler) is the same as in Example 1 except that the average particle diameter is 60 µm and the filling rate is 70%.

Example  5

Instead of flake silver plating copper, dendritic silver plating copper (silver content: 20%) was used, and the average particle diameter of the dendritic silver plating copper was 28 µm, and the filling rate of the dendritic silver plating copper was 70%. It is the same as Example 1 except for it.

Comparative example  One

After manufacturing the electromagnetic wave shielding tape treated with the conductive adhesive on a thin film aluminum foil having a thickness of 25㎛, the characteristics such as electrical conductivity, thickness, appearance, flexibility, adhesion, etc. were tested, and the results are shown in Table 1 below. Presented.

Comparative example  2

After manufacturing the electromagnetic wave shielding tape treated with the conductive adhesive on one surface of the conductive fabric having a thickness of 100㎛, the characteristics of electrical conductivity, thickness, appearance, flexibility, adhesion, etc. were tested, and the results are shown in Table 1 below. It is.

Comparative example  3

After the conductive thin film sheet was prepared by spraying with a conductive spray liquid using a flake-type silver-plated copper powder as the conductive filler, one side was subjected to the conductive adhesive treatment. The final product was subjected to electrical conductivity, thickness, appearance, flexibility, adhesion strength, and the like. The properties are shown in Table 1 below.

thickness Resistance (surface) Resistance (up and down) flexibility Adhesion Exterior Example 1 25 μm 2 × 10 ^-1 Ω / sq 5 × 10 ^-3 Ω ○ ○ ○ Example 2 25 μm 3 Ω / sq 1Ω ○ ○ ○ Example 3 60㎛ 2 × 10 ^-1 Ω / sq 1 × 10 ^-2 Ω ○ △ △ (pinhole generation) Example 4 30 μm 5 × 10 ^-1 Ω / sq 3 × 10 ^-2 Ω ○ △ △ (pinhole generation) Example 5 60㎛ 8 × 10 ^-1 Ω / sq 3 × 10 ² Ω ○ ○ △ (pinhole generation) Comparative Example 1 40 μm 5 x 10 ² Ω / sq 5 × 10 ² Ω × ○ × (scratch occurrence) Comparative Example 2 120 μm 5 × 10 ^-2 Ω / sq 5 × 10 ^-2 Ω ○ ○ X (poor smoothness) Comparative Example 3 25 μm 8 × 10 ^-1 Ω / sq 5 × 10 ^-2 Ω ○ ○ △ (pinhole generation)

○: Good △: Normal X: Poor

As can be seen from Example 1, when the flake-type silver-plated copper (conductive filler) having a silver content of 10% and an average particle diameter of about 33 μm was filled to about 70%, the thin film was able to be prepared, and excellent electrical conductivity, flexibility, Adhesion and a clean appearance could be secured.

As can be seen from Examples 2 and 3, when the filling rate of the conductive filler is 55%, the electrical conductivity (conductivity) was lowered, and when 85%, the thickness was thick and pinholes were generated, resulting in poor appearance characteristics. .

As can be seen from Examples 4 and 5, when flake-type silver plated copper having an average particle diameter of 60 µm is used as the conductive filler, adhesion and appearance characteristics are deteriorated, and when dendritic type silver-plated copper is used as the conductive filler. The thickness became thick and the external appearance property fell.

As can be seen from Comparative Example 1, when the aluminum foil is used, the electrical conductivity is excellent, but the flexibility and appearance characteristics are lowered, especially the occurrence of scratches.

As can be seen from Comparative Example 2, in the case where the conductive adhesive treated one surface of the conductive fabric could not be manufactured as a thin film, the woven shape was exposed on the surface, resulting in poor surface smoothness.

As can be seen from Comparative Example 3, in the case of using the spray solution, it was possible to manufacture a thin film and had excellent electrical conductivity, but there was a disadvantage in that pinholes were generated.

1 illustrates the structure of a conductive sheet in the form of a thin film having self-adhesiveness according to the present invention.

2 is a process chart for producing a conductive sheet of a thin film form having a self-adhesive of the present invention.

3 is a graph showing electromagnetic shielding efficiency of a conductive sheet having a self-adhesive thin film form according to a preferred embodiment of the present invention.

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

10: conductive sheet in the form of a thin film having self adhesiveness

100: heat adhesive polymer resin

200: conductive filler

Claims (12)

Melted by heat and has adhesiveness; polyurethane resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, chlorinated polyethylene resin, polyester resin, polybutyral chloride resin, ethylene vinyl acetate (EVA) resin, Copper, nickel, gold, silver, aluminum, carbon, silver plated nickel, silver plated copper, nickel plated copper, nickel plated graphite, and the like in a heat-adhesive polymer resin selected from the group consisting of epoxy resins, phenol resins, or combinations thereof. A conductive sheet having a self-adhesive thin film, characterized in that a granular, spherical, dendrite or flake conductive filler selected from the group consisting of silver plated glass is filled. The method of claim 1, The average particle diameter of the said conductive filler is 30-50 micrometers, The electroconductive sheet of the thin film form which has self-adhesion property. The method of claim 1, The conductive filler is a flake (silver) plated copper, characterized in that the self-adhesive thin sheet conductive sheet. The method of claim 1, The conductive sheet in the form of a thin film having self adhesiveness, characterized in that the filling rate of the conductive filler is 60 to 80%. The method of claim 1, The conductive sheet has a thickness of 50 μm or less and a surface resistance of 5 × 10 ⁻¹ μs / sq or less, wherein the conductive sheet in the form of a thin film having self adhesiveness. As a manufacturing method of the conductive sheet of the thin film form which has self adhesiveness, (a) polyurethane resins, polyethylene resins, polypropylene resins, polystyrene resins, polyvinyl chloride resins, chlorinated polyethylene resins, polyester resins, polybutyral chloride resins, ethylene vinyl acetate (EVA) resins, epoxy resins, phenol resins or After dissolving the heat-adhesive polymer resin selected from the group consisting of these in a mixed solvent of dimethylformamide (DMF), toluene and methyl ethyl ketone (MEK), copper, nickel, gold, silver, aluminum, carbon, The self-adhesive conductive liquid is uniformly dispersed by granular, spherical, dendritic or flake conductive fillers selected from the group consisting of silver plated nickel, silver plated copper, nickel plated copper, nickel plated graphite, and silver plated glass. Manufacturing; (b) casting the self-adhesive conductive liquid onto a substrate; And (c) drying the cast self-adhesive conductive liquid to evaporate the solvent, thereby forming a conductive sheet in the form of a thin film having self-adhesiveness. The method of claim 6, The conductive filler has an average particle diameter of 30 to 50 µm and a filling rate of 60 to 80%. The method of claim 7, wherein The conductive filler is flake type silver plated copper. The method of claim 6, The casting is performed by comma coating, spin coating, gravure printing, reverse roll coating or screen printing. The electromagnetic wave absorbing / shielding material in the form of a thin film comprising a conductive sheet in the form of a thin film having the self-adhesiveness according to any one of claims 1 to 5. The method of claim 10, The electromagnetic wave absorbing / shielding material is a thin film type electromagnetic wave absorbing / shielding material, characterized in that the electromagnetic shielding rate in the frequency band of 10MHz ~ 1GHz average 50dB (99.72% shielding) or more. An antenna and a radio recognition tag for a radio identification tag using a conductive sheet in the form of a thin film having the self-adhesion of any one of claims 1 to 5.

Images