KR101557813B1 - Heat dissipating polymer composite having an excellent thermal conductivity, preparation method thereof, and heat sink comprising the same - Google Patents

Abstract

The present invention relates to a heat dissipating polymer composite material, which is used in materials such as a heat sink plate in a lighting fixture, has excellent mechanical properties, outstanding moldability, and high heat dissipating properties, and reduces the weight of the lighting fixture, to a manufacturing method thereof, and to a heat sink plate comprising the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a heat-dissipating polymer composite material having excellent thermal conductivity, a method of manufacturing the same, and a heat sink including the heat dissipating polymer composite,

The present invention relates to a heat-dissipating polymer composite material, a method of manufacturing the same, and a heat sink made of the same. Specifically, the present invention relates to a heat-dissipating polymer composite material which satisfies excellent mechanical properties and high heat dissipation required for materials such as a heat sink of a lighting apparatus, has excellent moldability and can reduce the weight of the lighting apparatus, And a heat sink made of the same.

In general, a lighting device refers to a device that adjusts brightness, reflects or transmits light of a light source and fixes or protects the light source. Such a lighting device is classified into an indirect lighting device, a semi-direct lighting device, Direct lighting equipment and direct lighting equipment, and can be classified into incandescent lamps, fluorescent lamps, stands, floodlights, street lamps, and stage lighting depending on the purpose of use.

Among the above-mentioned lighting apparatuses, incandescent lamps and fluorescent lamps are generally used most commonly, and when incandescent lamps or fluorescent lamps emit light, the focus is blurred due to the flow of visible rays, which can rapidly lower the visual acuity of the user, And a short life span.

Therefore, in recent years, an LED lighting device realized with LED (Light Emitting Diode), which is advantageous in various aspects compared to incandescent lamps and fluorescent lamps, has been developed and sold. An LED is a light emitting diode that emits light and emits light of various colors such as red, green, blue, and yellow. Generally, a light emitting diode (LED) has a pn junction structure. When a forward current is applied to a diode, electrons in the n region of the chip are accelerated by the electric field to move to the p region, and the p region has an acceptor level ) Or recombined with the holes in the valence band state, and light having an energy corresponding to the potential difference is emitted according to the material of the chip. This phenomenon is referred to as injection type electroluminescence.

A lamp implemented as an LED requires only about 19% of power consumption compared to a conventional lamp realized with an incandescent lamp, and requires only about 50% of power consumption compared with a conventional lamp realized as a fluorescent lamp. LED lamps are not only able to minimize eye fatigue even when used for a long time, but also have a life span that is about 10 times longer than an incandescent lamp and about 8 times longer than a fluorescent lamp.

The performance of the LED lighting apparatus implemented by such an LED is excellent, but if the heat generated from the LED is not properly discharged, the LED or its driving circuit may be deteriorated and the service life may be shortened.

In order to solve this problem, it is general that the LED lighting device is designed such that a heat sink having an excellent thermal conductivity is attached to heat generated from the LED lighting device to the air.

Here, the widely used heat sink material is a metal material such as aluminum. However, since the heat sink of such a metal material has excellent heat conductivity and excellent heat dissipation property, the weight of the lighting device is increased, have.

Therefore, in order to reduce the weight of the LED lighting device and to ensure ease of handling and installation and safety, it is desirable that the material of the heat sink constituting the LED lighting device is lightweight and substantially equal to or superior in mechanical properties And a new material capable of realizing heat dissipation have been demanded.

The present invention aims to provide a heat-dissipating polymer composite material which exhibits excellent mechanical properties and heat dissipation properties required for materials such as a heat sink of a lighting apparatus and can reduce the weight of the lighting apparatus, a method of manufacturing the same, and a heat sink including the same do.

Another object of the present invention is to provide a heat-dissipating polymer composite material having excellent moldability by avoiding or minimizing degradation of moldability due to addition of an additive for realizing excellent heat radiation property, a method for producing the same, and a heat sink including the same.

In order to solve the above problems,

The heat-dissipating polymer composite material includes a thermoplastic polymer resin and at least one thermally conductive additive selected from the group consisting of carbon nanotubes (Carbon Nanotube), graphene nano-plate and expanded graphite , And a molded article formed from the composite material has an isotropic thermal conductivity (k) of 0.5 to 50 W / mK according to Equation (1) below.

[Equation 1]

In the above equation (1)

k _xy is the In-Plane Thermal Conductivity of the molded product,

k _z is the through-plane thermal conductivity of the molded article.

Also, the present invention provides a heat-dissipating polymer composite material, wherein the horizontal thermal conductivity (k _xy ) is 1.5 W / m · K or more and the vertical thermal conductivity (K _z ) is 0.4 W / m · K or more.

The thermally conductive polymer composition according to any one of claims 1 to 3, further comprising 0.1 to 2 parts by weight of the carbon nanotubes, 2 to 20 parts by weight of the graphene nanoplate and 5 to 30 parts by weight of the expanded graphite, based on 100 parts by weight of the thermoplastic polymer resin. It provides composite material.

Here, the carbon nanotubes have a diameter of 5 to 15 nm, a length of 5 to 500 μm, and an apparent volume of 0.02 g / cm 3 or less. The graphene nanoplate has a thickness of 1 μm or less, Wherein the length of the expanded graphite is 3 to 50 mu m and the length of the expanded graphite is 100 mu m or less.

The thermoplastic polymer resin may be selected from the group consisting of a polycarbonate resin, a polyamide resin, an acrylonitrile-butadiene-styrene resin, a polystyrene resin, a polyethylene terephthalate resin, (1) selected from the group consisting of a polyethylene resin, a styrene acrylonitrile resin, a cellulose, a polysulfone, a styrene-butadiene-styrene resin and an acrylic resin. Wherein the heat-dissipating polymer composite material is a thermoplastic resin.

The present invention also provides a heat-dissipating polymer composite material characterized by further comprising 0.2 to 5 parts by weight of a dispersing agent based on 100 parts by weight of the thermoplastic polymer resin.

Here, the dispersing agent is a saturated, unsaturated or aromatic hydrocarbon compound having 10 or more carbon atoms, and is a liquid compound having a viscosity of 10 to 10,000 cP.

In this case, the molded article formed from the composite material has an impact strength of 3.0 kgfcm / cm 2 or more, a tensile strength of 500 kgf / cm 2 or more, and a melt index of the composite material of 0.1 g / 10 min or more A heat-dissipating polymer composite material.

On the other hand, a method for producing a heat-dissipating polymer composite material includes the steps of: preparing a mixture comprising a thermoplastic polymer resin, a dispersant, and at least one thermally conductive additive selected from the group consisting of carbon nanotubes, graphene nanoplates, , Stirring the mixture at a rotation speed of 30 to 300 rpm for 15 to 30 minutes and heating the surface of the thermoplastic polymer resin constituting the mixture so that the surface temperature is not lower than 40 DEG C to form the dispersant and the thermoconductive Heating the mixture composed of the thermoplastic polymer resin and the dispersant and the thermally conductive additive adsorbed on the thermoplastic polymer resin to produce a molten mixture, The mixture is extruded to form the composite material Wherein the heat-dissipating polymer composite material is a thermosetting resin.

Also, a heat sink made of the heat-dissipating polymer composite material is provided.

Further, the heat sink is a heat sink for LED lamp.

The heat-dissipating polymer composite material according to the present invention not only exhibits excellent heat dissipation through precise control of thermal conductivity by a specific combination of kinds and mixing ratios of thermally conductive additives, but also exhibits excellent mechanical properties such as tensile strength and impact resistance.

The heat-dissipating polymer composite according to the present invention exhibits an excellent effect of avoiding or minimizing degradation of moldability despite the addition of a thermally conductive additive for realizing heat dissipation.

The heat-dissipating polymer composite material according to the present invention has an advantageous effect of improving ease of handling and installation and stability of a lighting apparatus and the like in which the heat sink or the like is used, because weight is reduced compared to a metal material such as a heat sink.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

The heat-dissipating polymer composite material according to the present invention comprises a thermoplastic polymer resin as a base resin, one or more kinds selected from the group consisting of carbon nanotubes (carbon nanotubes), graphene nano-plates and expanded graphite Thermally conductive additives.

In general, most thermoplastic polymer resins are lighter than metals, have no rusting, have excellent mechanical properties, and are easy to process and form. Therefore, when a heat radiating plate such as a lighting device is constituted by a composite material using the thermoplastic polymer resin as a base resin, the weight of the lighting apparatus or the like can be reduced, thereby improving ease of handling and installation and stability.

The thermoplastic polymer resin is not particularly limited and includes, for example, a polycarbonate resin, a polyamide resin, an acrylonitrile-butadiene-styrene resin, a polystyrene resin, a polyethylene terephthalate Polyethylene terephthalate resin, polyethylene resin, styrene acrylonitrile resin, cellulose, polysulfone, styrene-butadiene-styrene resin, acrylic resin, And the like.

The carbon nanotube (CNT), the graphene nanoplate (GNP), and the expanded graphite (EG), which are added as the thermally conductive additive, are uniformly dispersed in the thermoplastic polymer resin so that the optimal horizontal and vertical Thereby forming a heat transfer path, thereby realizing heat dissipation.

The molded article formed from the heat-dissipating polymer composite according to the present invention may have an isotropic thermal conductivity k of about 0.5 to 50 W / m · K, which is defined by Equation (1) below. When the isotropic thermal conductivity k is less than 0.5 W / m · K, sufficient heat dissipation can not be achieved. On the other hand, when the isotropic thermal conductivity k is more than 50 W / m · K, the thermally conductive additive must be added in an excessive amount. The moldability such as extrudability may be greatly lowered.

In the above equation (1)

k _xy is the in-plane thermal conductivity of the molded article,

k _z is the through-plane thermal conductivity of the molded article.

Specifically, the heat-dissipating polymer composite according to the present invention has a horizontal thermal conductivity (k _xy ) of about 1.5 W / m · K or more and a vertical thermal conductivity (k _z ) of about 0.4 W / m · K And thus the heat radiation function can be performed by proper harmonization of the horizontal and vertical thermal conductivity, as opposed to the normal heat radiation material depending on only the horizontal heat conductivity and performing the heat radiation function.

To this end, the thermally conductive additive constituting the heat-dissipating polymer composite material according to the present invention preferably comprises about 0.1 to about 2 parts by weight of the carbon nanotubes, about 2 to about 20 parts by weight of the graphene nanofibers based on 100 parts by weight of the thermoplastic polymer resin And about 5 to 30 parts by weight of the expanded graphite.

When the content of the carbon nanotubes, the graphene nanoplate, and the expanded graphite constituting the thermally conductive additive is less than the respective numerical values, sufficient heat dissipation can not be achieved. On the other hand, when the content of the carbon nanotubes, The moldability such as extrudability is greatly lowered, and the viscosity of the composite material is increased, so that the solvent resistance and the film adhesion are lowered, and at the same time, the stability is lowered and the physical properties may be significantly lowered.

The carbon nanotubes may be in the form of a bundle having a diameter of 5 to 15 nm, a length of 5 to 500 μm and an apparent volume of 0.02 g / cm 3 or less, The thickness may be 1 占 퐉 or less, the horizontal length may be 3 to 50 占 퐉, and the expanded graphite may preferably have a horizontal length of 100 占 퐉 or less.

The heat-dissipating polymer composite material according to the present invention may be prepared by mixing and dispersing the thermally conductive additive in the thermoplastic polymer resin, and if necessary, dispersing the thermoplastic polymer resin in a dispersant to improve the dispersibility of the thermally conductive additive to the thermoplastic polymer resin. . ≪ / RTI >

The dispersant further improves the dispersibility of the thermally conductive additive in the thermoplastic polymer resin so that it can realize excellent thermal conductivity and heat dissipation by a small amount of the thermally conductive additive and further enables the production time of the heat- Can be shortened.

The heat-dissipating polymer composite material according to the present invention may include about 0.2 to 5 parts by weight of the dispersant based on 100 parts by weight of the thermoplastic polymer resin. If the content of the dispersant is less than 0.2 parts by weight, the desired dispersibility of the thermally conductive additive can not be realized. On the other hand, if the content of the dispersant is more than 5 parts by weight,

The dispersant is not particularly limited as long as it can improve the dispersibility of the thermally conductive additive to the thermoplastic polymer resin. For example, the dispersant may be a saturated, unsaturated or aromatic hydrocarbon compound having a carbon number of 10 or more, As a liquid compound having 10 to 10,000 cP, a dispersant such as polyvinyl pyrrolidone, cetyltrimethyl ammonium bromide and the like may be used.

Further, the heat-dissipating polymer composite material according to the present invention has a sufficient melting index (MI) and is excellent in moldability such as extrudability and excellent in mechanical properties such as tensile strength and impact resistance of a molded article formed therefrom.

Specifically, the heat-dissipating polymer composite material according to the present invention may have a melting index (MI) of 0.1 g / 10 min or more, and the molded product formed from the heat-dissipating polymer composite material has an impact strength of 3.0 kgfcm / The tensile strength may be at least 500 kgf / cm 2.

The method for producing a heat-dissipating polymer composite material according to the present invention may include a pre-treatment step and a melt dispersion step.

The preprocessing step includes the steps of: preparing a mixture of the thermoplastic polymer resin, the dispersant, and the thermally conductive additive; and stirring the mixture in a predetermined range of rotational speed, time, and temperature to form the thermoplastic polymer resin And adsorbing the dispersant and the thermally conductive additive on the surface.

The thermoplastic polymer resin may be added in powder form or added in the form of a pellet. However, the shape of the thermoplastic polymer resin is not limited to the powder or pellet shape, and any shape including the thermoplastic polymer may be used.

In addition, the heat-dissipating polymer composite material may be prepared by dispersing the thermally conductive additive in the thermoplastic polymer resin, and if necessary, the dispersing agent may be added for ease of dispersion. However, the dispersant is not essential to the heat-dissipating polymer composite material, and the addition thereof may be omitted.

In the method of manufacturing a heat-dissipating polymer composite according to the present invention, when the thermally conductive additive is added to and dispersed in the thermoplastic polymer resin, the thermally conductive additive is added to the thermoplastic polymer resin, The components such as the nanotube, the graphene nanoplate, and the expanded graphite may be collectively added, but each component may be sequentially added and dispersed sequentially.

In the pretreatment step, if the thermally conductive additive that can be composed of at least one of the thermoplastic polymer resin, the dispersant, the carbon nanotube, the graphene nanoplate, and the expanded graphite is sufficiently mixed to constitute the mixture, The mixture may be stirred for 15 to 30 minutes at a rotation speed of 30 to 300 rpm, and the surface temperature of the thermoplastic polymer resin may be heated to 40 ° C or more. Here, when the surface temperature of the thermoplastic polymer resin is 40 ° C or higher, the dispersant and the thermally conductive additive may be adsorbed on the surface of the thermoplastic additive to form a thin coating film.

Next, the pre-treatment step may be followed by the melt-dispersion step.

The melting and dispersing step may include a step of heating the mixture through the pretreatment step to produce a molten mixture and a step of extruding the molten mixture to produce the composite material.

The mixture composed of the thermoplastic polymer resin and the dispersant and the thermally conductive additive adsorbed to the thermoplastic polymer resin can be heated and melted at a predetermined range of temperatures. Here, the temperature range may be varied depending on the kind of the thermoplastic polymer resin, the type of the dispersant, and the addition ratio of the carbon nanotube, the graphene nanoplate, and the expanded graphite that can constitute the thermoplastic polymer resin have.

Next, the composite material can be manufactured by extruding the molten mixture.

In the melting and dispersing step, heating, melting and extrusion of the mixture through the pretreatment step can be performed through a twin-screw extruder. The biaxial extruder is a molding machine in which a rotary screw in a cylinder extrudes a material, melts and mixes the material, and discharges the material. The biaxial extruder may be composed of a screw combination including at least one kneading block.

The heat-dissipating polymer composite material may be used as a material of a heat sink, and the heat sink may be a heat sink for an LED lamp.

Accordingly, the heat sink formed from the heat-dissipating polymer composite material can be used for the purpose of effectively discharging heat generated from the LED lamp by being applied to the LED lamp.

[Example]

1. Manufacturing Example

A heat-dissipating polymer composite material and a test piece according to each of the examples and comparative examples constituted by the compositions shown in Table 1 below were prepared. The unit of the numerical content shown in Table 1 is parts by weight.

Carbon nanotube Graphene nanoplate Expanded graphite Comparative Example 2 Example 1 One 10 Example 2 One 20 Example 3 One 10 8

2. Property evaluation

The thermal conductivity, impact strength, tensile strength and melt index required by the ASTM standard were measured using the composite material and the test piece of each of the examples and comparative examples. The results are shown in Table 2 below.

Item
unit standard Comparative Example
Example One 2 3 Horizontal thermal conductivity W / m · K ASTM D5470 ¹⁾ 0.4 1.62 2.17 3.37 Vertical thermal conductivity W / m · K ASTM D5470 ¹⁾ 0.2 0.44 1.0 1.36 Isotropic thermal conductivity W / m · K ASTM D5470 ¹⁾ 0.32 1.05 1.68 2.49 Impact strength kgfcm / ㎠ ASTM D256 2.8 4.9 3.4 3.6 The tensile strength kgf / cm2 ASTM D638 704 730 653 508 Melt Index g / 10 min ASTM D256 ²⁾ 2.5 3.8 One 0.4

¹⁾ : Measured using Laser Flash Method.

²⁾ : Measured at a temperature of 300 ° C for 10 minutes under a load of 2.16 kg.

As shown in Table 2, it was confirmed that the polymer composite material according to the comparative example failed to realize sufficient horizontal and vertical thermal conductivity of the thermally conductive additive.

On the other hand, the polymer composite materials of Examples 1 to 3 according to the present invention were found to have improved heat dissipation properties by realizing optimum horizontal and vertical thermal conductivity by a specific combination of the types of thermoconducting additives and blending ratio. Nevertheless, Mechanical properties such as impact strength and moldability.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. . It is therefore to be understood that the modified embodiments are included in the technical scope of the present invention if they basically include elements of the claims of the present invention.

Claims (11)

As a heat-dissipating polymer composite material,
A carbon nanotube having a diameter of 5 to 15 nm, a length of 5 to 500 占 퐉, and an apparent volume of 0.02 g / cm3 or less based on 100 parts by weight of the thermoplastic polymer resin; 0.1 to 2 parts by weight, 2 to 20 parts by weight of a graphene nano-plate having a thickness of 1 μm or less and a horizontal length of 3 to 50 μm and expanded graphite 5 having a horizontal length of 100 μm or less To 30 parts by weight of a thermally conductive additive,
The molded article formed from the composite material has an isotropic thermal conductivity (k) of 0.5 to 50 W / mK according to Equation (1) below.
[Equation 1]

In the above equation (1)
k _xy is the In-Plane Thermal Conductivity of the molded product,
k _z is the through-plane thermal conductivity of the molded article. The method according to claim 1,
Wherein the horizontal thermal conductivity (k _xy ) is 1.5 W / m · K or more, and the vertical thermal conductivity (K _z ) is 0.4 W / m · K or more. delete delete 3. The method according to claim 1 or 2,
The thermoplastic polymer resin may be at least one selected from the group consisting of a polycarbonate resin, a polyamide resin, an acrylonitrile-butadiene-styrene resin, a polystyrene resin, a polyethylene terephthalate resin, At least one member selected from the group consisting of a polyethylene resin, a styrene acrylonitrile resin, a cellulose, a polysulfone, a styrene-butadiene-styrene resin and an acrylic resin And a heat dissipating polymer composite material. 3. The method according to claim 1 or 2,
Further comprising 0.2 to 5 parts by weight of a dispersing agent based on 100 parts by weight of the thermoplastic polymer resin. The method according to claim 6,
Wherein the dispersing agent is a liquid hydrocarbon compound having a carbon number of 10 or more and a saturated, unsaturated or aromatic form and having a viscosity of 10 to 10,000 cP. 3. The method according to claim 1 or 2,
Wherein the molded article formed from the composite material has an impact strength of 3.0 kgfcm / cm 2 or more, a tensile strength of 500 kgf / cm 2 or more, and a melt index of the composite material of 0.1 g / 10 min or more. Polymer composite material. A method for producing a heat-dissipating polymer composite material,
Preparing a mixture comprising a thermoplastic polymer resin, a dispersant, and at least one thermally conductive additive selected from the group consisting of carbon nanotubes, graphene nanoplates, and expanded graphite;
The mixture is stirred for 15 to 30 minutes at a rotation speed of 30 to 300 rpm and heated so that the surface temperature of the thermoplastic polymer resin constituting the mixture is 40 DEG C or higher to form the dispersant and the thermoconductive additive To the surface of the thermoplastic polymer resin,
Heating the mixture comprising the thermoplastic polymer resin, the dispersant adsorbed on the thermoplastic polymer resin and the thermally conductive additive to produce a molten mixture, and
3. The method of manufacturing a heat dissipating polymer composite material according to claim 1 or 2, comprising the step of extruding the molten mixture to produce the composite material. A heat sink comprising the heat-dissipating polymer composite material according to claim 1 or 2. 11. The method of claim 10,
Wherein the heat sink is a heat sink for an LED lamp.