KR101065741B1 - A conductivity blowing flim and it's manufacturing method - Google Patents

Abstract

The present invention comprises a first layer formed by dispersing a carbon nanotube and a conductive metal particles having a functional group on the surface in a dispersion solvent and stirred with a polymer organic solution for a predetermined time; Concerning the conductive foam film comprising a second layer formed by mixing a solution in which carbon nanotubes having a functional group is dispersed on the upper surface of the first layer and a solution in which a blowing agent and a polyurethane are stirred and then foamed In that,
The conductive foam film may exhibit high conductivity without entanglement by using carbon nanotubes modified by introducing functional groups (carboxyl groups) through heat treatment and acid treatment on the surface of the carbon nanotubes, and additionally using conductive metal particles together. Not only is it easy to improve conductivity according to the application, but also has a lamination form consisting of a first layer having a conductive function and a second layer having a cushion function by foaming, so that it is structurally stable and variable conductivity according to the product usage It can be used for various purposes from antistatic sheet to electromagnetic shielding sheet, and especially it can be used as a product packaging material for shock absorption of electronic devices due to its high foaming property.

Description

Conductive foam film and its manufacturing method {A conductivity blowing flim and It's manufacturing method}

The present invention relates to a conductive foam film and a method for manufacturing the same, and more specifically, to cushion the cushion function through a composite with a polyurethane containing a blowing agent with excellent conductivity by containing carbon nanotubes and conductive metal particles having a functional group It has a foaming film which has, and its manufacturing method.

Recent developments in the electronics industry, precision machinery industry, etc., enrich the life, but have various disasters and obstacles, one of which is the obstacle caused by static electricity. Problems such as malfunction and breakdown of industrial electromechanical devices due to static electricity, resulting in lowering production efficiency, are causing serious problems not only in the enterprise but also in the precision machinery industry.

In this situation, as electronic devices and precision machinery industries are developing day by day, cushioning (shock protection) function is provided to protect products when packaging or laminating IT products, and the conductivity is controlled according to the amount of conductive materials incorporated. There is a need for a high performance conductive foam film product having a high antistatic property and electromagnetic shielding effect.

Recently, composite materials using carbon nanotubes as conductive materials have been applied in various fields. These carbon nanotubes were published by TEM of the multi-walled carbon nanotubes discovered in 1991 by Dr. Sumio Ijima, Japan, in the process of analyzing carbon masses formed on the cathode of graphite using the electric discharge method. It is becoming known, and its aspect ratio is thousands of times larger, which is excellent in mechanical strength, electrical conductivity, and thermal stability in the atmosphere, and many researchers continue to study in various fields.

In particular, the electrical properties of carbon nanotubes change the diameter of carbon nanotubes and the structure (chiral structure, helical structure, etc.) of carbon nanotubes, causing a change in the free electron motion method, and thus from insulators to semiconductors and conductors. It is known to have both, and accordingly, in the case of the foamed film using carbon nanotubes as a conductive material, it is possible to produce a high-performance product due to the electrical conductivity similar to copper, high thermal conductivity and high strength.

However, studies on foam films having a cushioning function using carbon nanotubes having excellent conductivity have not been carried out, which are obtained by mixing polyurethane and foaming agents in a dispersion solvent in which carbon nanotubes are dispersed and foaming them to form a film. In this case, the dispersibility is poor, and the carbon nanotubes aggregate and entangle with each other (percolation), and when the powder-type blowing agent is mixed in the dispersion solvent, swelling in the blowing agent and the blowing agent and the carbon nanotube are This is because it is not easy to manufacture a conductive foam film having excellent functions as many problems such as uneven dispersion of the polyurethane in the foam form due to uneven dispersion.

Accordingly, the present invention has been made to solve the above problems, in the production of a foam film requiring conductivity and cushion (impact protection) function by applying carbon nanotubes as a conductive material and having a high conductivity while having sufficient conductivity In order to manufacture a highly functional product having absorbency, the dispersibility and the swelling of the blowing agent in the solvent, which can be caused when applying the carbon nanotubes as the conductive material of the foam film, entanglement of the carbon nanotubes in the polyurethane It is an object of the present invention to provide a foamed film and a method of manufacturing the same, which can achieve variable conductivity due to the structurally stable lamination form.

According to an aspect of the present invention,

A first layer formed by dispersing a carbon nanotube having a functional group on a surface thereof in a dispersion solvent and stirring the polymer organic solution for a predetermined time; It provides a conductive foam film consisting of a solution in which carbon nanotubes having a functional group is dispersed on the upper surface of the first layer, and a second layer formed by mixing a foaming agent and a stirred solution of polyurethane with each other and foaming them. Is achieved.

In addition, the present invention comprises the steps of removing the amorphous carbon and organic compounds in the carbon nanotubes through physical and chemical treatment to form a functional group, such as carboxyl group (-COOH) on the surface and then dispersed in a dispersion solution; Incorporating the dispersion solution in which the carbon nanotubes are dispersed into a polymer organic solution, stirring to disperse well, applying a predetermined amount to a casting paper, and drying the film to form a first layer; Dispersing the blowing agent in another dispersion solvent, and then mixing the mixture into the polymer organic solution and stirring to form a foaming solution; The foaming solution is mixed with the carbon nanotube dispersion and stirred, and then coated on the first layer and foamed in a dryer to form a second layer; provides a method for producing a conductive foam film, characterized in that it is prepared by.

As described above, the conductive foamed film of the present invention and its manufacturing method exhibit high conductivity using carbon nanotubes and conductive metal particles having a functional group (carboxyl group), and swelling of the foaming agent using a nonpolar solvent as a dispersion solvent. In addition to lowering the pressure, the antistatic sheet is structurally stable and has variable conductivity according to product use, as it has a lamination form consisting of a first layer having a conductive function and a second layer having a cushioning function by foaming. It is not only applicable to various applications from electromagnetic wave shielding sheet, but also has a high foaming property, which can be used as a product packaging material for shock absorption of electronic devices.

1 is a cross-sectional view showing a conductive foam film of the present invention
2 is a TGA graph for confirming the content of florene in carbon nanotubes according to the passion agent of the present invention.
Figure 3 is an FT-IR graph of the carbon nanotubes according to the acid treatment of the present invention
Figure 4 is a photograph for confirming the dispersion degree of the dispersion solvent to the carbon nanotubes of the present invention

Hereinafter, the conductive foam film of the present invention will be described in more detail.

According to the present invention, the foamed film is composed of two layers as shown in FIG. 1. First, a carbon nanotube having a functional group on a surface thereof is dispersed in a dispersion solvent, and then formed after stirring for a predetermined time with a polymer organic solution. Layer 10; And a second layer 20 formed by mixing a solution in which carbon nanotubes having functional groups are dispersed on a top surface of the first layer and a solution in which a blowing agent and a polyurethane are stirred, and then foaming each other.

As such, the first layer 10 focused on the conductive function and the second layer 20 focused on the cushion function are separately laminated, so that the conductivity and cushion functions are divided between layers and the mixing ratio of the components between the layers. It can be adjusted according to the needs and can be applied in various ways according to the required application.

Reference numeral 30, which is not described, refers to the casting paper 30 for applying the first layer 10, and since the conventional method is used in forming a conventional film, detailed description thereof will be omitted.

First, in order to form the first layer 10, (I) amorphous carbon and organic compounds in the carbon nanotubes are removed through physical and chemical treatment, and a functional group such as a carboxyl group (-COOH) group is formed on the surface, and then Dispersing; (II) mixing the dispersion of the carbon nanotubes into the polymer organic solution and stirring the dispersion so that the dispersion is well, and coating the casting paper 30 with a predetermined amount and drying the film to complete the first layer 10. .

Carbon nanotubes used in the present invention can be used not only multi-walled carbon nanotubes, but also single-walled carbon nanotubes or double-walled carbon nanotubes, and the method of generating them may be arc discharge, CVD, plasma CVD, or pyrolysis. Law and so on.

However, conventional carbon nanotubes contain carbon organic materials, such as fullerene and amorphous carbon, produced by synthesizing with transition metals used for growth in the production process, and thus contained in carbon nanotubes as in step (I). In order to remove the carbon organic matter and transition metals and to form functional groups on the surface, a physical treatment, a passion agent method and a chemical treatment, an acid treatment method are required.

The enthusiasm method can be used all of the conventional methods currently known, but preferably, carbon nanotubes are put in a furnace at 200 ° C. and heated at 5 ° C. per minute to flow atmospheric gas into the furnace at 450 ° C. After heat treatment to decompose amorphous carbon or fullerene for 80 minutes, and finish by lowering the temperature by 5 ℃ per minute to remove carbon organic matter.The gas introduced into the furnace affects the heat treatment of carbon nanotubes with air, argon, nitrogen, etc. Preference is given to using gases which are not supplied.

FIG. 2 is a TGA graph for confirming the content of florene in carbon nanotubes according to the passion agent of the present invention. As shown in FIG. 2, the content of florene in the carbon nanotubes after the passion agent is greater than that before the passion agent. It can be seen that the decrease.

As described above, the carbon nanotubes having the physical treatment are subjected to acid treatment, which is a chemical treatment method, to remove transition metals present in the carbon-determined carbon nanotubes and form functional groups on the surface thereof. As a method for forming a carboxyl group (COOH-), 1 to 2 parts by weight of carbon nanotubes with enthusiasm are added to 100 parts by weight of an acid solution mixed with nitric acid and sulfuric acid at a 3: 1 ratio by weight, and then subjected to normal temperature (about 28 ° C.). Ultrasonic dispersion for 1 hour at, and then washed with distilled water at least 5 times to adjust the acid treated carbon nanotubes to pH 6.5-7 and dried in a vacuum dryer at 80 ℃ for 24 hours to remove amorphous carbon organic materials and transition metals And carbon nanotubes having a carboxyl group (-COOH) as a functional group.

3 is an FT-IR graph of the carbon nanotubes according to the acid treatment of the present invention. As can be seen from FIG. 3, it can be understood that a carboxyl group is formed as a functional group in the carbon nanotubes through the above-described acid treatment.

In addition, a process of grafting conductive metal particles (CNT-graft-metal nanoparticles) through a ball milling method for the purpose of further increasing the conductivity in the carbon nanotubes in which the functional groups are generated as described above is dispersed in a dispersion solvent. It can be added, which can optionally be used when the present invention has high conductivity required according to the application of the foam film. In this case, the amount of the conductive metal particles is not particularly limited in order to achieve the required conductivity. However, when the amount of the conductive metal particles is large, the amount of the conductive metal particles may cause a change in physical properties. It is preferred to be added.

The conductive metal particles used in this way are nanoparticles of metals such as gold, silver, copper, platinum, and palladium, and the carbon nanoparticles are attached to the carbon surface having functional groups through ball milling, or the hollow carbon nanotubes in the form of tubes. As part of the inside of the tube is filled, the conductivity that cannot be satisfied by carbon nanotubes alone is further improved.

As such, the carbon nanotubes having functional groups are added in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of the dispersion solvent and dispersed well so as not to aggregate. The dispersion solvent is a representative nonpolar solvent, DMF (dimethylformamide), MEK (Mathylethylketon), IPA (isopropyl alcohol) or toluene (Toluene) and the like can be used, in addition to any solvent that can disperse carbon nanotubes can be used. In addition to the purpose of dispersing the carbon nanotubes, the use of such an organic dispersion solvent has the advantage of lowering the viscosity of the polymer organic solution to evenly disperse the carbon nanotubes in the polymer organic solution.

In addition, the dispersion process by using a high speed stirrer to disperse the dispersion solution containing carbon nanotubes in the polymer organic solution little by little, or by placing a ball (iron ball, zircon ball) in the stirring vessel or by installing a rod The solution and the carbon nanotube dispersion solution are allowed to stir evenly in the vertical and horizontal directions.

Figure 4 is a photograph for confirming the dispersion degree of the dispersion solvent in which the carbon nanotubes of the present invention is injected, first the general carbon nanotubes without functional groups as shown in Figure 4 (a) was added to the dispersion solvent (DMF) and dispersed As a result of checking after 1 hour, the carbon nanotubes could not be dispersed and deposited and phase separation occurred. On the other hand, as shown in FIG. Was measured in the same manner as in (a) with respect to the carbon nanotubes formed on the surface of the functional group was confirmed to be uniformly dispersed in the dispersion solvent without phase separation phenomenon.

Next, the carbon nanotube-containing dispersion liquid was stirred with a polyurethane solution as in step (II), and then applied to a casting paper, then applied to the casting paper 30, and then applied in an appropriate amount. Drying for 2 minutes to produce a first layer 10 having a conductive function, the thickness of the first layer 10 is preferably to be 100 ~ 200㎛.

As the organic polymer solution used in this way, polyurethane, which is a non-conductive polymer material, is most commonly used. In addition, polyester, polyamide, polyvinyl alcohol, polycarbonate, urea resin, acrylic rubber, epoxy resin, phenol resin, melamine One or a mixture of two or more of the resins may be used. At this time, the molecular weight and use viscosity of the polymer are not particularly limited, but the molecular weight is preferably 200,000 or less and the viscosity is between 6,500 ~ 7,500cps.

On the other hand, when the organic solution is composed only of the non-conductive polymer, the overall conductivity of the first layer 10 may be reduced, so that the conductive polymer may be mixed within the range of not impairing the physical properties of the first layer 10. In general, it may be used by mixing 10 to 200 parts by weight based on 100 parts by weight of the nonconductive polymer. In addition, for the purpose of the aesthetics and functionality of the film, dyes, functional particles and the like can be further added at this step.

The conductive polymer may be polyacetylene (PA), polypyrrole polythiophene (PT), poly 3-alkyl thiophene (poly (3-allkyl) thiophene: P3AT).

When the formation of the first layer 10 is completed as described above, the second layer 20 is formed on the upper surface thereof. In order to form the second layer 20, (I) physically and chemically treating the carbon nano Removing amorphous carbon and organic compounds in the tube, creating functional groups such as carboxyl groups (-COOH) on the surface, and then dispersing them in a dispersion solvent; (II ') dispersing the blowing agent in another dispersion solvent, incorporating into the polymer organic solution and stirring to form a foaming solution; (III) mixing and stirring the foamed solution with the carbon nanotube dispersion and then applying it on the first layer 10 and foaming in a dryer to form a second layer 20.

First, the step (I) for forming the second layer 20 proceeds in the same manner as the step (I) for forming the first layer 10, whereby a carbon nanotube dispersion having a functional group is prepared. Will be omitted.

Apart from the prepared carbon nanotube dispersion, 30 to 50 parts by weight of the blowing agent is added to 100 parts by weight of another dispersion solvent as in step (II ′), dispersed, mixed with a high molecular weight organic solution, and rapidly stirred to expand the foaming solution. In order to prevent the swelling phenomenon of the blowing agent is carried out in a separate dispersion solvent, the content of the blowing agent is preferably added to 1 to 10 parts by weight based on 100 parts by weight of the polymer organic solution.

The polymer organic solution used in the second layer 20 may also be applied in the same manner as used in the first layer 10. However, in order to maximize foaming properties, the solid polyurethane (urethane resin content of 95% or more) ) May be most preferably used.

Then, in step (III), the dispersion of the carbon nanotubes of step (I) is added little by little to the foaming solution containing the blowing agent and polymer organic solution of step (II ′), and the stirring speed is carbon. Work is started at low speed so that the nanotube dispersion solution is evenly mixed with the foamed urethane stirring solution, and gradually the stirring speed is increased to be sufficiently mixed. Preferably, the stirring solution is performed in a stirrer at 250 to 500 / min for 30 minutes.

The stirring solution in which the carbon nanotube dispersion and the foaming solution are evenly mixed is applied to the upper surface of the first layer 10 and foamed at a foamable temperature (130 ° C. to 195 ° C.), followed by drying in a dryer, to form the second layer 20. By forming the conductive film of the present invention is completed. At this time, the thickness of the second layer 20 is preferably 200 to 1000㎛.

The polymer organic solution used in the second layer 20 may also be used in the same manner as used in the first layer 10. In addition to the high solid polyurethane (urethane resin content of 95% or more), which is a typical non-conductive polymer, , Polyamide, polyvinyl alcohol, polycarbonate, urea resin, acrylic rubber, epoxy resin, phenol resin, melamine resin can be used, or a mixture of two or more selected from the non-conductive polymer mixed with a conductive polymer It is possible.

The conductive foam film of the present invention as described above is a problem of dispersion caused when the carbon nanotubes are applied as a conductive material, swelling of the foaming agent, agglomeration problem in the polymer material of the blowing agent and carbon nanotubes (aggregation) As a result of research to solve, it is possible to show high conductivity without entanglement by using carbon nanotube modified by introducing functional group (carboxyl group) through heat treatment and acid treatment on the surface of carbon nanotube, and additionally conductive metal particles It is not only easy to improve the conductivity according to the application use, but also has a lamination form consisting of a first layer having a conductive function and a second layer having a cushion function by foaming. It has variable conductivity according to various purposes from antistatic sheet to electromagnetic shielding sheet This can facilitate, in particular, also used as a high conductivity and excellent foam properties as a shock absorbing product for packaging the electronic apparatus is possible.

Hereinafter, the foamed film according to the present invention will be described in more detail through the following examples, but the scope of the present invention is not limited by the following examples.

<Manufacture example 1>

Carbon nanotubes having a carboxyl group (-COOH) group on the surface were added and dispersed through a passion agent and an acid treatment. Then, 40 g of the dispersion solution had a molecular weight of 200,000 or less and a viscosity of 6,500-7,500 cps. After mixing and stirring in a predetermined amount to the casting paper 30 and dried to form a film to complete the first layer.

7 g of an organic foaming agent is added to 100 g of a dispersion solvent IPA and dispersed therein, and then mixed with 50 gdp of solid polyurethane (95% or more of urethane resin) and stirred to form a foaming solution, and then a carbon nanotube dispersion having a functional group used in the first layer. After mixing and stirring with the upper surface of the first layer was applied and foamed in a dryer to form a second layer to prepare a foam film.

&Lt; Example 1 >

To prepare a foam film as in Preparation Example 1, as shown in Figure 5 attached to measure the conductivity according to the content of the carbon nanotube having a carboxyl group functional group for IPA, MEK, Toiuene as a dispersion solution. The conductivity is measured using a conductivity meter (KEITHLEY 8009, USA) and an electrometer (KEITHLEY 6517B, USA), measurement time (Measure Time, sec.) 15, offset voltage (V) 0, alternating voltage (Alternating Voltage, V) The surface resistivity was measured under the conditions of 50 and 20 (Current Range, mA).

As shown in FIG. 5, when the carbon nanotube having the carboxyl functional group of the present invention is used as the conductive material, the conductivity may be improved according to its content, and the content of the carbon nanotube through the conductivity measurement value. It can be seen that it is possible to manufacture a high quality foam film according to the intended use by adjusting the.

10: first floor
20: the second layer
30: casting paper

Claims (23)

(I) physical and chemical treatment to remove the carbon organic matter and transition metal in the carbon nanotubes to form a functional group such as carboxyl group (-COOH) on the surface and to disperse in a dispersion solvent; (II) a first layer 10 formed by incorporating the carbon nanotube dispersion into a polymer organic solution, stirring the dispersion so that the dispersion is well, and coating the casting paper 30 with a predetermined amount and drying the film;
(I) removing amorphous carbon organics and transition metals in the carbon nanotubes through physical and chemical treatments, creating functional groups such as carboxyl groups (-COOH) on the surface, and dispersing them in a dispersion solvent; (II ') dispersing the blowing agent in another dispersion solvent, incorporating into the polymer organic solution and stirring to form a foaming solution; (III) a second layer 20 formed by mixing and stirring a dispersion solution containing carbon nanotubes and a dispersion solution containing a foaming agent and a polymer organic solution, and then coating the first layer 10 and foaming in a dryer; Conductive foam film, characterized in that consisting of. delete delete The method of claim 1, wherein the physical treatment is to put carbon nanotubes in a furnace of 200 ℃ and the temperature is increased by 5 ℃ per minute to flow an atmospheric gas such as air, argon, nitrogen into the furnace at 450 ℃ in 80 minutes A conductive foam film, characterized in that the enthusiastic method to finish by lowering the temperature by 5 ℃ per minute after the heat treatment to decompose the fullerene. The method according to claim 1, wherein the chemical treatment is 1 to 2 parts by weight of the carbon nanotubes enthusiastic to 100 parts by weight of the acid solution mixed with nitric acid and sulfuric acid in a 3: 1 ratio by weight ratio, and then ultrasonically dispersed for 1 hour at room temperature Next, the acid-treated carbon nanotubes were washed with distilled water five times or more so as to have a pH of 6.5 to 7, and then dried in a vacuum dryer at 80 ° C. for 24 hours to form a carboxyl group on the surface of the carbon nanotubes as a functional group. Foam film. The method according to claim 4 or 5, before dispersing the carbon nanotubes in which the functional group is produced in a dispersion solvent by adding 5 to 100 parts by weight based on 100 parts by weight of carbon nanotubes graft (through ball milling) CNT-graft-Metalic nano particles) conductive foam film characterized in that. The conductive foam film of claim 6, wherein the conductive metal particles are nanoparticles of a metal such as gold, silver, copper, platinum, and palladium. The conductive foam film of claim 6, wherein the dispersion solvent is selected from DMF (dimethylformamide), MEK (Mathylethylketon), IPA (isopropyl alcohol) or toluene. The method according to claim 7, wherein the polymer organic solution is one or two or more of a non-conductive polymer material polyurethane, polyester, polyamide, polyvinyl alcohol, polycarbonate, urea resin, acrylic rubber, epoxy resin, phenol resin, melamine resin A conductive foam film, characterized in that the mixture is used. The conductive foam film of claim 9, wherein the polymer organic solution is polyurethane having a molecular weight of 200,000 or less and a viscosity of 6,500 to 7,500 cps. The conductive foam film of claim 9, wherein the polymer organic solution is a mixture of 10 to 200 parts by weight of the conductive polymer with respect to 100 parts by weight of the nonconductive polymer. The method of claim 11, wherein the conductive polymer is one of polyacetylene (PA), polypyrrole polythiophene (PT), and poly 3-alkyl thiophene (poly (3-allkyl) thiophene: P3AT). Or a mixture of two or more conductive foam films. The method of claim 11, wherein the blowing agent for forming the second layer (20) is a conductive foam film, characterized in that added to 1 to 10 parts by weight based on 100 parts by weight of the polymer organic solution. The conductive foam film according to claim 13, wherein the first layer (10) has a thickness of 100 to 200 µm and the thickness of the second layer (20) is 200 to 1000 µm. delete delete delete delete delete delete delete delete delete

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