KR20130040440A - Electrically insulative and thermally conductive ceramic/polymer composit powder and method for preparatin the same - Google Patents

Abstract

PURPOSE: A manufacturing method of ceramic/polymer composite powder is provided to coat a ceramic particle on the surface of a polymer bead, and to maximize the dispersion of thermoplastic ceramic, thereby providing the ceramic/polymer composite powder with high thermal conductivity. CONSTITUTION: A manufacturing method of ceramic/polymer composite powder comprises: a step of wet-pulverizing and powderizing boron nitride, and peeling the surface thereof; a step of mixing the boron nitride and thermoplastic polymer beads in an alcohol solvent to attach the boron nitride onto the surface of the thermoplastic polymer beads; and a step of evaporating the solvent to separate the nitride/polymer composite powder in which the boron nitride is attached to the surface of the thermoplastic polymer beads.

Description

Ceramic / Polymer Composite Powder Having Electrical Insulation and Thermal Conductivity and Its Manufacturing Method {ELECTRICALLY INSULATIVE AND THERMALLY CONDUCTIVE CERAMIC / POLYMER COMPOSIT POWDER AND METHOD FOR PREPARATIN THE SAME}

The present invention relates to a ceramic / polymer composite powder and a method of manufacturing the same, and more particularly, to maximize the dispersion by producing a powder by coating the surface of the polymer bead of the micronized thermal conductive ceramic (polymer bead), heat release The present invention relates to a ceramic / polymer composite powder capable of exhibiting high thermal conductivity by using a small amount of thermally conductive filler.

Recently, for the purpose of miniaturization and high functionality of electronic devices, heat generating elements are concentrated inside the apparatus, and thus an efficient cooling method is required. Also. In an electric vehicle using a secondary battery as a power source, there is a need for a method for effectively controlling the heat generated from the secondary battery during driving.

In general, heat generated from an electronic device or a secondary battery is radiated to air, and the heat radiation is mainly performed using a radiator manufactured by a metal having excellent thermal conductivity such as aluminum or copper. However, such a heat dissipation device is not secured in insulation, and must be provided with a separate device such as a fuse, and the device is heavy due to the characteristics of the metal as a whole.

Therefore, the method of manufacturing a composite material by disperse | distributing the inorganic particle which has a high thermal conductivity to resin which consists of matrices, such as a silicone resin and an epoxy resin normally, is studied. As a thermally conductive filler to be applied in such a thermally conductive polymer composite, metal particles are effective for improving thermal conductivity but are difficult to be commonly used because they do not have electrical insulation, and are mainly materials having excellent thermal conductivity and excellent electrical insulation in metal oxides or metal nitrides. Is used. Currently, in order to obtain high thermal conductivity, a large amount of thermally conductive filler is dispersed in an epoxy or silicone resin to manufacture a composite material.

However, such a method has a disadvantage in that it is difficult to take advantage of the thermally conductive polymer material due to the high manufacturing cost, high viscosity of the material, and low mechanical properties. Accordingly, the development of the thermally conductive polymer material is currently progressing in order to obtain the optimal thermal conductivity with a minimum thermally conductive filler content in order to secure the flow capable of injection molding and an appropriate level of physical properties.

 In order to achieve optimal thermal conductivity with minimum thermally conductive filler content, a thermal pathway must be established in which the thermally conductive fillers are in direct contact within the polymer matrix to minimize phonon-scattering, more specifically. The thermally conductive ceramics should be arranged in the desired position.

However, existing thermally conductive ceramic / polymer composite material manufacturing techniques, for example, by simply mixing a thermally conductive ceramic with a liquid polymer or polymer powder, it is difficult to establish the above-mentioned thermal pathway. .

Matters related to the prior art include J Sandler, MSP Shaffer, T Prasse, W Bauhofer, Volume 40, Issue 21, October 1999, Pages 5967-5971, Yan Wang, Zixing Shi and Jie Yin, J. Mater. See Chem., 2011, 21, 11371-11377, Wenying Zhou, Shuhua Qi, Haidong Li, Shiyu Shao, Thermochimica Acta 452 (2007) 3642 and the like.

It is an object of the present invention to maximize the dispersion of thermally conductive ceramics by introducing ceramic / polymer composite powder by coating a piece of ceramic on the surface of the polymer bead, thereby minimizing thermal conductivity in the polymer matrix of the composite material. It is to provide a thermally conductive polymer composite material that can exhibit high thermal conductivity by establishing a thermal conduction path as a filler.

In order to achieve the above object, the present invention provides a method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, comprising: wet grinding a boron nitride to refine particles and peel a surface (step a); Putting the wet milled boron nitride and thermoplastic polymer beads into an alcohol solvent to mix the wet milled boron nitride to the surface of the thermoplastic polymer beads (step b); And evaporating the solvent to separate the boron nitride / polymer composite powder which is a thermoplastic polymer bead attached to the surface of boron nitride (step c).

The boron nitride before the wet grinding of step a may be prepared as a plate-shaped boron nitride having a diameter of 1 to 10 μm.

Isopropyl alcohol or an ethanol solvent can be used for the said wet grinding | pulverization.

The wet-pulverized boron nitride may have a diameter of 0.05-50 μm and a thickness of 1-50 nm.

The thermoplastic polymer is acrylonitrile butadiene styrene, polymethyl methacrylate, polyamide, polybutadiene terephthalate, polyethylene terephthalate, polycarbonate, polyethylene, polyether ketone, polypropylene, polystyrene and poly It may be any one selected from the group consisting of methyl silsesquioxane.

The thermoplastic polymer beads may be in the range of 0.1 ~ 100㎛ diameter.

In step b, the boron nitride and the thermoplastic polymer beads may be mixed in a volume ratio of 5:95 to 60:40.

The alcohol solvent may allow the wet-pulverized boron nitride and the thermoplastic polymer beads to have opposite surface charges.

The alcohol solvent may be isopropyl alcohol.

Mixing of step b may be performed by sequentially performing ultrasonic treatment and stirring.

The ultrasonic treatment may be performed for 1 minute to 50 hours.

The stirring may be performed for 10 minutes to 50 hours.

Ceramic / polymer composite powder having an electrical insulation and thermal conductivity of the present invention for achieving the above object, the polymer beads; And boron nitride attached to the surface of the polymer bead in the form of a plate, wherein the boron nitride is micronized by wet grinding and the surface is peeled off.

The polymer beads, the diameter may be in the range of 0.1 ~ 100㎛.

The boron nitride may be a plate-like piece of 0.05 ~ 50㎛ diameter, 1-50nm thickness range.

The polymer beads and wet-pulverized boron nitride may be attached to each other by electrostatic attraction due to mutual surface charge difference.

The polymer beads and the wet pulverized boron nitride may be attached to each other by van der Waals forces.

The method for producing a thermally conductive formed article of the present invention for achieving the above object is to mold using a ceramic / polymer composite powder produced by the above production method.

The molding can be performed by any one of injection molding, extrusion molding and compression molding.

The molding may be performed for 10 to 200 minutes at a pressure of 0.1 ~ 500MPa, a temperature of 50 ~ 300 ℃ using a biaxial molding machine.

The molded article produced according to the above method may further perform secondary molding by adding a thermosetting resin.

The thermosetting resin may be polydimethylsiloxane or epoxy.

Addition of the said thermosetting resin can be added in the form which mixed a thermosetting resin and a hardening | curing agent in the mass ratio of 80: 20-95: 5.

The present invention can maximize the dispersion of thermally conductive ceramics by manufacturing ceramic / polymer composite powder by coating a piece of ceramic on the surface of the polymer bead. Such thermally conductive ceramics are used as the thermally conductive filler in the polymer matrix of the composite material. By doing so, a thermally conductive polymer composite material having high thermal conductivity even with a small amount of thermally conductive filler can be manufactured.

1 is a SEM image and a diameter distribution diagram of a powder before and after grinding of boron nitride powder in Example 1. FIG.
2 is a comparative graph of X-ray diffraction analysis before and after grinding of the boron nitride powder in Example 1. FIG.
3 is a SEM image of polymethylsilsesquioxane beads in Example 1 and a diameter distribution diagram of the beads.
4 is an SEM image of a ceramic / polymer composite powder prepared according to Example 1. FIG.
5 is a surface SEM image of a thermally conductive formed article prepared according to Example 2. FIG.
6 is a cross-sectional SEM image of the thermally conductive formed article prepared in Example 2. FIG.
7 is a surface SEM image of the thermally conductive formed article prepared according to Example 3. FIG.
8 is a cross-sectional SEM image of the thermally conductive formed article prepared according to Example 3. FIG.
9 is a graph comparing thermal conductivity of each sample according to Experimental Example 1. FIG.

First, a method of manufacturing the ceramic / polymer composite powder of the present invention will be described, and then a method of manufacturing a molded body using the ceramic / polymer composite powder produced thereby will be described.

The manufacturing method of the ceramic / polymer composite powder of the present invention can be divided into three steps.

First, boron nitride is prepared and wet pulverized to refine the size and peel off the surface (step a).

The micronized and exfoliated boron nitride is dispersed in a solvent in which boron nitride can be easily dispersed, and then prepared by a wet grinding process.

Specifically, a plate-like boron nitride having a diameter of 0.1 to 100 µm is prepared and dispersed in a solvent required for the wet grinding step. At this time, the dispersion solvent is an alcohol solvent such as isopropyl alcohol (isopropyl alcohol), ethanol (ethanol) can be easily dispersed.

In this way, the boron nitride dispersed in the solvent is put in a grinding vessel, and zirconia balls are added, followed by rotation to wet grinding. At this time, the rotation speed of the grinding vessel is 400 ~ 500rpm, the grinding time is preferably carried out 2 days or more. In addition, the zirconia ball is added to about 1/2 of the container, the grinding vessel is preferably made of a synthetic resin container.

Accordingly, the wet-pulverized boron nitride preferably has a diameter of 0.5 to 10 μm and a thickness of 1 to 50 nm.

Next, the micronized and exfoliated boron nitride and polymer beads are mixed (step b).

The polymer bead is a thermoplastic polymer, acrylonitrile butadiene styrene (ABS), polymethylmethacrylate (PMMA), polyamide, polybutadiene terephthalate (Polybutadieneterephtalate, PBT) Polyethylene terephtalate (PET), Polycarbonate (PC), Polyethylene (PE), Polyetheretherketone (PEEK), Polypropylene (PP), Polystyrene (Polystyrene) PS) Polymethylsilsesquioxane (PMSQ) and the like can be applied.

In addition, the size of the thermoplastic polymer is preferably used in the range of 0.1 ~ 100㎛.

The mixing is carried out by placing the micronized and exfoliated boron nitride and the polymer beads obtained in step a in an alcohol solvent, sonicating, and stirring.

In this case, the alcohol solvent may be such that the boron nitride and the thermoplastic polymer beads may have different surface charges. In addition, the sonication is performed to minimize agglomeration of the boron nitride obtained in step a, and the agitation is performed to effectively attach the boron nitride to the surface of the polymer beads.

Specifically, the micronized and exfoliated boron nitride: polymer beads = 5:95 to 60:40 using a volume ratio, the sonication is performed sufficiently for 1 minute to 50 hours, the stirring is 10 minutes to 50 hours Is preferred.

Accordingly, the micronized and exfoliated boron nitride pieces can be evenly attached to the surface of the polymer beads by electrostatic attraction due to the difference in mutual surface charges.

On the other hand, the solvent for dissolving the boron nitride fragment and the polymer beads is not limited to the solvent, when using a solvent that does not form a surface charge difference, it can be attached by the van der Waals force between the two particles.

Finally, the solution from step b is evaporated to separate the solvent and the ceramic / polymer composite powder, and the powder is collected (step c).

At this time, the evaporation is preferably using a vacuum evaporation device.

The present invention provides a ceramic / polymer composite prepared according to the above production method.

In the ceramic / polymer composite, a fine plate-like boron nitride piece is uniformly attached to the surface of the polymer bead, the polymer bead has a diameter of 0.1-100 μm, and the boron nitride piece has a diameter of 0.05-50 μm, 1 It is preferable that it is a plate-shaped piece of thickness of -50 nm.

Hereinafter, a method of manufacturing the thermally conductive molded article of the present invention using the silicon / polymer composite powder prepared according to the above-described method will be described.

In the same manufacturing method as described above, a silicone / polymer composite powder may be prepared, and a molded body may be manufactured by injection molding, extrusion molding, compression molding, or the like, and may be molded using a uniaxial pressing machine. .

At this time, the molding is performed at a high pressure and for a sufficient time at the glass transition temperature or its temperature so that the contact interface between the silicon / polymer composite powder increases.

Preferably, the molding may be performed for 10 to 200 minutes at a pressure of 0.1 ~ 500MPa, a temperature of 50 ~ 300 ℃.

When the primary molded body molded according to the above method is completed, secondary molding in which a thermosetting polymer is added to the primary molded body may be further performed in order to minimize a decrease in density due to pores and a decrease in thermal diffusion rate.

The thermosetting polymer may be polydimethylsiloxane (PDMS) or epoxy resin, but is preferably applied in a fluid state, and may be added by mixing with a curing agent in a predetermined ratio.

Specifically, the solution of the thermosetting resin: curing agent = 80:20 ~ 95: 5 mixed in a mass ratio of the first molded article is added, and the pressure of 0.1 ~ 500MPa, 50 ~ 300 ℃ for 10-200 minutes Preference is given to performing secondary molding.

According to the manufacturing method, the thermal conduction path by the micronized, exfoliated boron nitride in the polymer matrix can be formed, there is an advantage that can exhibit sufficient thermal conductivity even with the addition of a small amount of boron nitride because of excellent dispersibility. .

The present invention provides a thermally conductive molded article produced according to the above production method.

Hereinafter, a preferred embodiment of the present invention will be described in detail.

Example 1 : Manufacture of Ceramic / Polymer Composite Powder

Boron nitride powder was prepared and wet pulverized for 48 hours to refine the size and peel. Thereafter, the wet milled boron nitride and polymethylsilsesquioxane (PMSQ) beads were added to isopropyl alcohol in a volume ratio of 3: 7, sonicated for 20 minutes, then stirred for 10 hours, and then dried in a vacuum dryer. Ceramic / polymer composite powders were prepared.

Here, the SEM image before and after the wet grinding of the boron nitride powder and the diameter distribution of the powder are shown in FIG. 1, and a comparative graph of X-ray diffraction analysis before and after grinding of the boron nitride powder is shown in FIG. 2. In addition, the SEM image of the polymethylsilsesquioxane beads and the diameter distribution of the beads are shown in FIG. 3.

1 and 2, the average diameter of the powder before and after the wet grinding of boron nitride was confirmed to decrease by about three times from 1.63㎛ to 0.52㎛, the average thickness was also shown to decrease. Trace amounts of boron oxide were detected in the boron nitride after wet grinding.

According to FIG. 3, it was found that the polymethylsilsesquioxane beads applied in Example 1 had an average diameter of 4.49 μm.

Meanwhile, the surface potentials of wet milled boron nitride and polymethylsilsesquioxane beads in isopropyl alcohol were analyzed using a zeta potential device.

The analysis results are shown in Table 1 below.

matter Zeta Potential (mV) Thermally conductive filler
Boron nitride before grinding -49.57 Boron nitride after grinding -57.45 Polymer matrix Polymethylsilsesquioxane 101.7

According to Table 1, the boron nitride before and after the wet grinding process has a value of (-) while polymethylsilsesquioxane was found to have a value of (+). In other words, it can be seen that boron nitride and polymethylsilsesquioxane have opposite surface charges in isopropyl alcohol, and the two materials are different due to the different surface charges of boron nitride and polymethylsilsesquioxane in the solution. It can be expected that this can be effectively attached.

The SEM image of the finally prepared ceramic / polymer composite powder is shown in FIG. 4.

According to Figure 4, the ceramic / polymer composite powder prepared according to Example 1 was confirmed that the wet-pulverized plate-like boron nitride particles are evenly attached to the surface of the polymethylsilsesquioxane.

Example  2: using ceramic / polymer composite powder Thermal conductivity Of the shaped body  Manufacturing method

The ceramic / polymer composite powder prepared according to Example 1 was compression molded at 150 ° C. and 400 MPa for 30 minutes to prepare a thermally conductive molded body.

SEM images of the surface and the cross section of the thermally conductive formed article prepared according to Example 2 are shown in FIGS. 5 and 6, respectively.

5 and 6, the boron nitride particles were uniformly distributed in the polymethylsilsesquioxane matrix after compression molding. However, many pores in the molded body were observed.

Example  3: using ceramic / polymer composite powder impregnated with epoxy resin Thermal conductivity  Manufacturing method of the molded article

Second compression molding was performed for 30 minutes at 150 ° C. and 50 MPa by adding 5 ml of a liquid mixed with an epoxy resin and a curing agent in a mass ratio of 9: 1 to the thermally conductive molded article prepared according to Example 2.

Surface and cross-sectional SEM images of the thermally conductive formed article prepared according to Example 3 are shown in FIGS. 7 and 8, respectively.

According to FIG. 7 and FIG. 8, the pores were markedly reduced as compared with Example 2, and accordingly, it can be expected that the thermal diffusivity and thermal conductivity of the thermally conductive formed body will be increased.

Comparative example  One: Polymethylsilsesquioxane  Used Thermal conductivity Of the shaped body  Manufacturing method

Compression molding was carried out under the same conditions as in Example 2, except that polymethylsilsesquioxane was used as the material.

Comparative example  2: Polymethylsilsesquioxane  And epoxy resin Thermal conductivity Of the shaped body  Manufacturing method

Primary and secondary compression molding were performed under the same conditions as in Example 3, except that only polymethylsilsesquioxane was used as the material for the primary compression molding.

Thermal conductivity Of the shaped body  Comparison of thermal conductivity

The thermal conductivity of the thermally conductive molding agents prepared according to Example 2, Example 3, Comparative Example 1 and Comparative Example 2 was compared.

The results are shown in Table 2 and FIG. 9.

Thermal conductive molded article manufacturing method Thermal Conductivity (W / mK) Comparative Example 1 0.11 Comparative Example 2 0.2 Example 2 0.36 Example 3 0.96

According to Table 2 and Figure 9, it can be confirmed that the molded article prepared according to Example 2 is about three times higher than the molded article prepared according to Comparative Example 1, the molded article prepared according to Example 3 is about 9 times higher thermal conductivity. have.

As mentioned above, although the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the above embodiment, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. It is possible.

Claims (24)

Wet grinding the boron nitride to refine the particles and to peel off the surface (step a);
Putting the wet milled boron nitride and thermoplastic polymer beads into an alcohol solvent to mix the wet milled boron nitride to the surface of the thermoplastic polymer beads (step b); And
Separating the boron nitride / polymer composite powder which is a thermoplastic polymer bead attached to the surface of the boron nitride by evaporating the solvent (step c); a method of manufacturing a ceramic / polymer composite powder having electrical insulation and thermal conductivity .
The method according to claim 1,
Boron nitride before the wet grinding of step a,
A method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized by preparing a plate-like boron nitride having a diameter of 0.1 to 100 µm.
The method according to claim 1,
The wet grinding,
A method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized by using isopropyl alcohol or an ethanol solvent.
The method according to claim 1,
The wet milled boron nitride,
It is characterized by having a diameter of 0.05 ~ 50㎛, 1 ~ 50nm thickness A method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity.
The method according to claim 1,
The thermoplastic polymer,
Acrylonitrile butadiene styrene, polymethyl methacrylate, polyamide, polybutadiene terephthalate, polyethylene terephthalate, polycarbonate, polyethylene, polyether ketone, polypropylene, polystyrene and polymethylsilsesquioxane Method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized in that any one selected from the group consisting of.
The method according to claim 1,
The thermoplastic polymer beads,
A method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, wherein the diameter is in the range of 0.1 to 100 μm.
The method according to claim 1,
Step b,
A method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, wherein boron nitride and thermoplastic polymer beads are mixed at a volume ratio of 5:95 to 60:40.
The method according to claim 1,
The alcohol solvent,
A method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, wherein the wet ground boron nitride and the thermoplastic polymer beads have opposite surface charges.
The method according to claim 1,
The alcohol solvent,
A method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized in that it is isopropyl alcohol.
The method according to claim 1,
Mixing of the step b,
A method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized by performing sonication followed by stirring.
The method of claim 10,
The ultrasonic treatment,
Method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized in that performed for 1 minute to 50 hours.
The method of claim 10,
The stirring is
Method for producing a ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized in that performed for 10 minutes to 50 hours.
Polymeric beads; And
Boron nitride is attached to the surface of the polymer bead in the form of a plate-like piece, the boron nitride is ceramic / polymer composite having electrical insulation and thermal conductivity, characterized in that the particles are micronized by the wet grinding and the surface is peeled off powder.
The method according to claim 13,
The polymer beads,
Ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized in that the diameter ranges from 0.1 to 100 μm.
The method according to claim 13,
The boron nitride,
Ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized in that it is a plate-like piece having a diameter of 0.05 to 50 µm and a thickness of 1 to 50 nm.
The method according to claim 13,
The polymer beads and wet milled boron nitride,
Ceramic / polymer composite powder having electrical insulation and thermal conductivity, characterized in that they are attached to each other by electrostatic attraction due to mutual surface charge difference.
The method according to claim 13,
The polymer beads and wet milled boron nitride,
Ceramic / polymer composite powder with electrical insulation and thermal conductivity, characterized by mutual adhesion by van der Waals forces.
A method for producing a thermally conductive formed article characterized by molding using a ceramic / polymer composite powder produced by the method of claim 1.
19. The method of claim 18,
The molding,
A method for producing a thermally conductive molded article characterized in that any one of injection molding, extrusion molding and compression molding.
The method of claim 19,
The molding,
Method for producing a thermally conductive molded article characterized in that it is carried out for 10 to 200 minutes at a pressure of 0.1 ~ 500MPa, a temperature of 50 ~ 300 ℃ using a biaxial molding machine.
19. The method of claim 18,
The molded article produced according to the above method,
A method for producing a thermally conductive formed article characterized by further performing secondary molding by adding a thermosetting resin.
23. The method of claim 21,
In the thermosetting resin,
A method for producing a thermally conductive formed article, which is polydimethylsiloxane or epoxy.
23. The method of claim 21,
The addition of the thermosetting resin,
A thermosetting resin and a hardening | curing agent are added in the form which mixed in the mass ratio of 80: 20-95: 5, The manufacturing method of the heat conductive molded object characterized by the above-mentioned.
23. The method of claim 21,
The secondary molding,
Method of producing a thermally conductive molded body, characterized in that carried out for 10 to 200 minutes at a pressure of 0.1 ~ 500MPa, a temperature of 50 ~ 300 ℃.

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