KR20160072754A - Heat radiating sheet using polymer nanocomposite and method for producing thereof - Google Patents

Abstract

The present invention relates to a heat dissipating sheet using a polymer nanocomposite and a producing method thereof. The heat dissipating sheet using a polymer nanocomposite can efficiently emit heat generated from inside an electronic device to the outside by showing excellent heat conductive properties. The lifespan of the electronic device can be extended and the efficiency of the electronic device can be improved. In addition, the producing method of the heat dissipating sheet using a polymer nanocomposite can provide the heat dissipating sheet having excellent heat conductive properties as a freestanding heat dissipating sheet by using graphene oxide.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a heat-dissipating sheet using a polymer nanocomposite,

A heat-dissipating sheet using a polymer nanocomposite, and a method of manufacturing the same.

BACKGROUND ART [0002] In recent years, with the development of electronic devices and the demand for complex functions, the weight, thickness, and miniaturization of printed circuit boards have been progressively increasing. In order to meet such a demand, the wiring of the printed circuit becomes more complicated, the density becomes higher, and the function becomes higher. In addition, a lightweight, thin, and flexible electronic device such as a wearable device, which is attracting much attention from many people, is required to have high integration in order to provide many functions. However, the problem of heat generation inside the electronic device due to such high integration has become a technical problem that must be solved.

In addition, as the use of incandescent lamps is totally prohibited for improving energy efficiency and reducing carbon dioxide emission, it is expected that the demand for LED light sources to replace them is expected to increase rapidly. In order to improve the economical efficiency of LED light sources, Instead of reducing the number, a high current drive is required to improve the output, and the heat dissipation problem is still a technical challenge.

Therefore, there is a need for a technique for releasing a considerable amount of heat that is inevitably generated for economical utilization of semiconductor devices and high-efficiency LEDs requiring high integration.

In addition, in order to realize light weight shortening of electronic devices, materials composing the electronic devices can be small and integrated, and at the same time, high efficiency should be exhibited. However, due to the accompanying heat, the characteristics of the material and further the characteristics of the electronic device are deteriorated. For this reason, it is necessary to develop a material for exhibiting excellent heat radiation characteristics.

For this purpose, thermally conductive polymer materials have been recognized as important materials. In particular, carbon composite materials such as polymer composite materials including ceramic or metal filler, graphite, carbon nanotube, and carbon fiber Many polymer composite materials are being developed. Of these carbon composite materials, graphene, which has received much attention recently, is a thin film structure in which carbon atoms having a thickness of about 0.35 nm are honeycomb. Many studies have been conducted due to high electrical conductivity and excellent heat conduction characteristics. In order to ensure dispersion stability in polymer complexes, they are manufactured in the form of complexes through changes in surface properties and are applied in various ways as well as thermoconductive polymer composite materials . Especially, it is known that the thermal conductivity is particularly superior to other carbon composite materials. In order to solve such a problem, recently, a heat radiation sheet using a polymer composite containing nanoparticles is increasingly applied.

There is provided a heat-radiating sheet having improved thermal conductivity using a polymer nanocomposite in which graphene nanoparticles are dispersed, and a method for manufacturing the same.

A method of manufacturing a heat-radiating sheet using a polymer nanocomposite according to an embodiment of the present invention includes:

Mixing a polymer binder and graphine oxide to form a mixture;

Ultrasonically treating the mixture;

Adding a fluorine-based additive and a defoaming agent to the mixture to prepare a coating solution;

Coating the coating liquid on a substrate to form a coating film; And

And separating the coating film from the substrate.

In the method for producing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention, the polymeric binder is selected from the group consisting of a polyurethane resin, a polyacrylic resin and a polyester resin.

In the method for manufacturing a heat radiation sheet using the polymer nanocomposite according to one aspect of the present invention, the blending ratio of the polymer binder and the graphene oxide is 2: 3 to 2: 4.

In the method for producing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention, the fluorine-based additive is added in an amount of 0.1 to 0.2 parts by weight based on 100 parts by weight of the mixture, and the defoaming agent is added in an amount of 0.5 part by weight .

In the method for producing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention, the coating film has a thickness of 25 탆 to 45 탆.

In the method of manufacturing a heat-radiating sheet using a polymer nanocomposite according to one aspect of the present invention, the substrate is made of a material selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate , Polycarbonate) and a polyimide substrate.

In the method of manufacturing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention, the method may further include the step of separating the coating film from the substrate and then applying heat to the coating film.

In the method for producing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention, the step of applying heat to the coating film uses two rolls.

In the method for producing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention, the step of applying heat to the coating film is performed at a temperature of 80 ° C to 120 ° C.

In another embodiment of the present invention, there is provided a freestanding heat-radiating sheet produced by the above manufacturing method.

The heat-radiating sheet using the polymer nanocomposite fabricated according to one aspect of the present invention exhibits excellent heat conduction characteristics and can efficiently emit heat generated inside the electronic device to the outside. As a result, the lifetime of the electronic device can be extended and the efficiency of the electronic device can be improved.

In addition, in the method of manufacturing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention, a heat-radiating sheet having excellent heat conduction characteristics can be provided as a free-standing heat-radiating sheet by using graphen oxide.

In addition, the method of manufacturing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention can further improve the orientation characteristics of graphene oxide particles by performing a dry lamination process.

1 is a flowchart illustrating a method of manufacturing a heat-radiating sheet using a polymer nanocomposite according to an embodiment of the present invention.
2 is a flowchart showing a method of manufacturing a heat-radiating sheet using a polymer nanocomposite according to another embodiment of the present invention.
3 is a view showing the orientation of graphene oxide in the heat radiation sheet before and after the dry lamination process in the method of manufacturing the heat radiation sheet using the polymer nanocomposite according to the embodiment of the present invention.
4 is a SEM (scanning electron microscope) photograph showing the surface of the heat radiation sheet before and after the dry lamination process.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may unnecessarily obscure the subject matter of the present invention. In addition, the terms described below are established in consideration of the functions of the present invention, and these may vary depending on the intention of the manufacturer or custom in the industry, and the definition should be based on the contents throughout the specification.

Hereinafter, a method of manufacturing a heat-radiating sheet using a polymer nanocomposite according to one aspect of the present invention will be described in detail with reference to FIG.

The method for producing a heat-radiating sheet using the polymer nanocomposite according to the present invention comprises the steps of: i) mixing a polymer binder and graphine oxide to form a mixture (S100); ii) sonicating the mixture (S200); iii) preparing a coating solution by adding a fluorinated additive and a defoaming agent to the mixture (S300); iv) forming a coating layer by coating the coating solution on the substrate (S400); And v) separating the coating film from the substrate (S500).

First, in step S100 in which a polymer binder and graphene oxide are mixed to form a mixture, the polymer binder may be a polyurethane resin or a polyacrylic resin. The polymeric binder may be any one selected from water-soluble binders such as polyester resins.

The polymeric binder according to the present invention has excellent merits such as ease of processing and variety of forms, but it is disadvantageous in that the thermal energy transferred through the inside is dispersed due to the characteristics of the polymer, and the thermal conductivity is low. Therefore, when a composite material is appropriately mixed with a material having excellent heat conduction characteristics such as graphene oxide, it can be used without limitation in various fields in various fields requiring heat radiation characteristics.

The graphene oxide acts as an inorganic filler to lower the coefficient of thermal expansion of the polymeric binder and to enhance the heat dissipation properties of the coating film formed of the coating solution.

The blending ratio of the polymer binder and the graphene oxide may vary depending on the required properties in consideration of the use of the coating solution to be prepared and the like. In one aspect of the present invention, the blending ratio of the polymer binder and the graphene oxide is 2: 3 to 2: 4 < / RTI > That is, when the blending ratio of the polymer binder and the graphene oxide is less than 2: 3, the thermal conductivity of the composite material due to the graphene oxide blending is lowered. If the mixing ratio of the polymer binder and the graphene oxide is greater than 2: 4 The content of the solid content is increased and the dispersibility may be deteriorated, resulting in a decrease in the uniformity of the coating. Therefore, preferably, the mixing ratio of the polymer binder and the graphene oxide may be 2: 3 to 2: 4.

Then, in order to improve the dispersibility of the graphene oxide particles, ultrasonic treatment may be performed for 15 minutes using a bath type ultrasonic apparatus (S200). After ultrasonication, the mixture is mixed for about 10 minutes using a magnetic stirrer.

Then, a fluorine-based additive and a defoaming agent are added to the mixture of the high molecular weight binder and the graphene oxide to prepare a coating solution (S300). The fluorine-based additive is a non-ionic fluorosurfactant. The defoamer is an organic modified polysiloxane emulsion, a dimethyl polysiloxane, a polyether siloxane copolymer emulsion, a polyether siloxane copolymer and an organic polymer. Polymers, polymers of hydrophobic silica and organic polymers.

The fluorine-based additive is added in an amount of 0.1 to 0.2 part by weight based on 100 parts by weight of the mixture, and the defoaming agent may be added in an amount of 0.5 part by weight based on 100 parts by weight of the mixture. The fluorine-based additives and antifoaming agents are used to improve the surface tension reduction and leveling of the solution in subsequent coating processes in the course of preparing the composite material solution. When the mixing ratio of the fluorine-based additive and the defoaming agent is less than the above ratio, it is difficult to achieve the object of the present invention such that the coating is not easy. If the mixing ratio is larger than the mixing ratio, the compatibility of the coating solution is deteriorated, There is a possibility of deteriorating the characteristics of the back coating film itself.

Add a fluorine-based additive and defoamer and mix for about 10 minutes using a magnetic stirrer. Thereafter, in order to remove bubbles and the like which may be present in the coating liquid, stabilization can be performed in a vacuum chamber for about 24 hours.

Thereafter, the coating solution is coated on the substrate to form a coating film (S400). The coating solution is uniformly applied on the substrate to a thickness of about 25 μm to 45 μm using an applicator, dried at room temperature for about 5 minutes, and then cured in a convection oven for about 12 hours.

The coating film may have a thickness of 25 [mu] m to 45 [mu] m. That is, since the shape of electronic apparatuses and the like pursues the tendency of light and thin chips, the thickness of the heat radiation sheet to be applied should be as thin as possible and exhibit excellent heat radiation characteristics. That is, when the thickness of the heat-radiating sheet is too small, it may be difficult to handle the coating film. As a result of the experiment of the present invention, the heat radiation effect is excellent when the thickness of the coating film is 25 μm to 45 μm.

The substrate may be a PET (polyethylene terephthalate) film, a polyethylene naphthalate (PEN), a polyethersulfon (PES), a polycarbonate (PC), a polycarbonate or a polyimide substrate. Then, the substrate or the PET film was peeled off (S500) to measure the heat conduction characteristics. In addition, the content of graphene oxide contained in the coating film was measured by thermogravimetric analysis (TGA). The measurement results are shown in the following examples.

In the method of manufacturing a heat dissipation sheet using the polymer nanocomposite according to one aspect of the present invention, the method may further include a step S600 of separating the coating film from the substrate and applying heat to the coating film as shown in FIG.

The step of applying heat to the coating film may be performed by using two rolls, that is, a dry lamination process is performed under a constant temperature and pressure condition using two rolls in the separated coating film.

As a result, as shown in FIG. 3, the arrangement state of the graphene oxide particles contained in the separated coating film can be improved (after heat is applied) to the orientation property along the in-plane direction of the polymer film at the plate structure . Therefore, the isotropic orientation of graphene oxide can further improve the thermal conductivity characteristics of the heat-radiating sheet produced according to the present invention. That is, the reason why the thermal conductivity of the heat-radiating sheet is low is that the thermal energy is dispersed during thermal conduction due to the complex chain structure of the polymer contained therein. However, in the heat- radiating sheet containing graphene oxide according to the present invention, It can be seen that the thermal conductivity characteristics are greatly improved by improving the orientation of the graphene oxide particles by applying the process.

In addition, in the present invention, heat can be uniformly applied to the entire coating layer by using two rolls to apply heat to the separated coating film, so that a heat-radiating sheet of uniform quality can be manufactured in an actual mass production process. Further, it is possible to make the heat radiation sheet larger in size by adjusting the gap using the two rolls.

In the method for producing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention, the step of applying heat to the coating film is performed at a temperature of 80 ° C to 120 ° C. In the step of applying heat to the coating film, if the process temperature is lower than 80 ° C, the molecular state of the polymer is not flexible and it is difficult to change the arrangement state of the graphene oxide particles even when the lamination process is performed. When the process temperature is higher than 120 ° C Since the self-properties of the polymer film may vary, the process is performed in the temperature range, preferably at 100 ° C.

The present invention provides a freestanding heat-radiating sheet manufactured by the above-described manufacturing method, and can be applied to itself as a freestanding heat-radiating sheet and can be attached to other substrates or the like to improve the heat conduction characteristics of the substrate, It can be used as a purpose.

The heat-radiating sheet using the polymer nanocomposite fabricated according to one aspect of the present invention exhibits excellent heat conduction characteristics and can efficiently emit heat generated inside the electronic device to the outside. Accordingly, the lifetime of the electronic device can be extended, the efficiency of the electronic device can be improved, and a free standing heat-radiating sheet can be provided, which can be used in various ways such as by being attached to another substrate.

Hereinafter, a method of manufacturing a heat-radiating sheet using the polymer nanocomposite according to one aspect of the present invention will be described.

Example 1

Manufacture of free standing heat-radiating sheet

8 g of polyurethane resin and 12 g of graphene oxide are mixed. Thereafter, ultrasonic treatment is performed for 15 minutes using a bath sonicator for 15 minutes, and the resultant is mixed with a bar magnet for 10 minutes. Then, 0.04 g of a fluorine-based additive and 0.1 g of a defoaming agent were added, and the mixture was stirred for 10 minutes using a bar magnet to prepare a coating solution. Stabilization is carried out in a vacuum chamber for about 24 hours in order to remove bubbles which may be present in the prepared coating solution.

Thereafter, the prepared coating solution is applied on a PET film with a thickness of 33 μm by using an applicator, dried at about 25 ° C. for 5 minutes, and then cured in a convection oven for 12 hours to produce a coating film. Then, the coating film was peeled off from the PET film to measure the heat conduction characteristics.

Example 2

Manufacture of free standing heat-radiating sheet

8 g of polyurethane resin and 13 g of graphene oxide are mixed. Thereafter, ultrasonic treatment is performed for 15 minutes using a bath sonicator for 15 minutes, and the resultant is mixed with a bar magnet for 10 minutes. Then, 0.04 g of a fluorine-based additive and 0.1 g of a defoaming agent were added, and the mixture was stirred for 10 minutes using a bar magnet to prepare a coating solution. Stabilization is carried out in a vacuum chamber for about 24 hours in order to remove bubbles which may be present in the prepared coating solution.

Thereafter, the prepared coating solution is applied on a PET film with a thickness of 33 μm by using an applicator, dried at about 25 ° C. for 5 minutes, and then cured in a convection oven for 12 hours to produce a coating film. Then, the coating film was peeled off from the PET film to measure the heat conduction characteristics.

Example 3

Manufacture of free standing heat-radiating sheet

8 g of polyurethane resin and 14 g of graphene oxide are mixed. Thereafter, ultrasonic treatment is performed for 15 minutes using a bath sonicator for 15 minutes, and the resultant is mixed with a bar magnet for 10 minutes. Then, 0.04 g of a fluorine-based additive and 0.1 g of a defoaming agent were added, and the mixture was stirred for 10 minutes using a bar magnet to prepare a coating solution. Stabilization is carried out in a vacuum chamber for about 24 hours in order to remove bubbles which may be present in the prepared coating solution.

Then, the prepared coating solution is applied on a PET film with a thickness of 31 탆 by using an applicator, dried at about 25 캜 for 5 minutes, and then cured in a convection oven for 12 hours to prepare a coating film. Then, the coating film was peeled off from the PET film to measure the heat conduction characteristics.

Example 4

Manufacture of free standing heat-radiating sheet

8 g of polyurethane resin and 15 g of graphene oxide are mixed. Thereafter, ultrasonic treatment is performed for 15 minutes using a bath sonicator for 15 minutes, and the resultant is mixed with a bar magnet for 10 minutes. Then, 0.04 g of a fluorine-based additive and 0.1 g of a defoaming agent were added, and the mixture was stirred for 10 minutes using a bar magnet to prepare a coating solution. Stabilization is carried out in a vacuum chamber for about 24 hours in order to remove bubbles which may be present in the prepared coating solution.

Then, the prepared coating solution is applied on a PET film with a thickness of 41 탆 by using an applicator, dried at about 25 캜 for 5 minutes, and then cured in a convection oven for 12 hours to prepare a coating film. Then, the coating film was peeled off from the PET film to measure the heat conduction characteristics.

Comparative Example

Manufacture of free standing heat-radiating sheet

8 g of the polyurethane resin is applied on the PET film to a thickness of 40 탆 using an applicator, dried at about 25 캜 for 5 minutes, and then cured in a convection oven for 12 hours to prepare a coating film. Then, the coating film was peeled off from the PET film to measure the heat conduction characteristics.

Experimental results and discussion

Table 1 shows the results of the free standing heat-radiating sheet manufactured in the above Examples and Comparative Examples.

Sheet thickness (mm) Thermal conductivity (W / (m · K)) Weight reduction (% @ 900 ℃) Comparative Example 0.040 - 99.89 Example 1 0.037 8.62 94.26 Example 2 0.033 12.22 91.58 Example 3 0.031 14.41 91.08 Example 4 0.041 19.24 85.91

The thickness of the sheet means the thickness of the freestanding coating film prepared in the comparative example and the examples. In recent years, the thickness of the sheet has been set to 25 탆 to 45 탆 for heat dissipation performance in consideration of the thinning tendency of electronic equipment.

The thermal conductivity was measured using Thermal Diffusivity Measurements (NETZSCH, LFA 447 Nanoflach, Germany). In Example 4, the thermal conductivity was 19.24, indicating excellent thermal conductivity. In addition, the weight reduction means that the content of the polymeric binder in the heat-radiating sheet is decreased, and conversely, the content of graphene oxide is increased. When the weight reduction degree in Example 4 is maintained, the thermal conductivity property is maintained at 19.24, and when the weight is reduced, the content of graphene oxide is further increased to further decrease the coating property itself .

As a result, the heat-radiating sheet using the polymer nanocomposite fabricated according to one aspect of the present invention is manufactured using graphene oxide, thereby exhibiting excellent heat conduction characteristics and efficiently discharging heat generated in the electronic device to the outside. In addition, the present invention provides a free-standing heat-radiating sheet, which can be applied to itself as a free-standing heat-radiating sheet, and can be used for various purposes such as being able to improve the heat conduction characteristics of the substrate by attaching it to another substrate .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (10)

Mixing a polymer binder and graphine oxide to form a mixture;
Ultrasonically treating the mixture;
Adding a fluorine-based additive and a defoaming agent to the mixture to prepare a coating solution;
Coating the coating liquid on a substrate to form a coating film; And
And separating the coating film from the substrate.
The method according to claim 1,
Wherein the polymeric binder is selected from the group consisting of a polyurethane resin, a polyacrylic resin, and a polyester resin.
The method according to claim 1,
Wherein the mixing ratio of the polymer binder to the graphene oxide is 2: 3 to 2: 4.
The method according to claim 1,
The fluorine-based additive is added in an amount of 0.1 to 0.2 parts by weight based on 100 parts by weight of the mixture,
Wherein the defoaming agent is added in an amount of 0.5 part by weight based on 100 parts by weight of the mixture.
The method according to claim 1,
Wherein the coating film has a thickness of 25 [mu] m to 45 [mu] m.
The method according to claim 1,
The substrate is selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), and polyimide Wherein the polymer nanocomposite is formed of a thermosetting resin.
The method according to claim 1,
And separating the coating film from the substrate, and then applying heat to the coating film. The method of manufacturing a heat-radiating sheet using the polymer nanocomposite according to claim 1,
8. The method of claim 7,
The method according to claim 1,
Wherein the step of applying heat to the coating layer comprises using two rolls.
8. The method of claim 7,
Wherein the step of applying heat to the coating layer is performed at a temperature of 80 to 120 ° C.
A free-standing heat-radiating sheet produced by any one of claims 1 to 9.

Images