KR101848241B1 - Method for manufacturing epoxy composites comprising boron nitride - Google Patents

Abstract

One embodiment of the present invention provides a method for manufacturing an epoxy composite, which comprises the following steps: (a) pre-treating boron nitride particles with a metal salt and an acid; (b) surface-treating the pretreated boron nitride particles with a silane-based compound; and (c) mixing the surface-treated boron nitride particles and the epoxy resin. It is an object of the present invention to provide the method for manufacturing the epoxy composite having high compatibility between boron nitride and an epoxy resin, thermal conductivity and mechanical properties.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for producing an epoxy composite material containing boron nitride,

The present invention relates to a method for producing an epoxy composite material excellent in compatibility with epoxy resin and thermal conductivity using boron nitride particles pretreated with a metal salt and an acid.

Microelectronic devices continue to require high-density, high-frequency, and high-speed performance improvements. Small size and performance improvements are likely to result in higher amounts of heat generation within narrow devices. Small differences in operating temperature can result in more than twice the device lifetime, which is a direct problem with the reliability of electronic devices. The packaging material of the article needs to have a high thermal conductivity, since unnecessary heat must be removed quickly to ensure proper device operation.

Epoxy resins are polymeric materials that are widely used in the electrical and electronic industries because of their excellent properties such as corrosion resistance, adhesive strength, and electrical insulation. However, the relatively low thermal conductivity of 0.17 W / m · k can not be used alone as an electronic packaging material capable of releasing heat generated in power density devices. In addition, when the degree of curing is high, there is a tendency that the material tends to break easily, which is a disadvantage that it still has to be solved as a microelectronic device packaging material due to thermal stability and the like. Therefore, studies have been made to produce polymer composite materials having excellent thermal conductivity and high mechanical properties by mixing inorganic particles and additives with epoxy resin.

Among the fillers, boron nitride is considered as an attractive candidate for low toxicity, good chemical stability, electrical insulation and relatively low cost, along with high thermal conductivity of 300 W / m · k. In order to form a high thermal conductivity and a smooth heat conduction network, a boron nitride input amount of 60 wt% or more was used. However, high boron nitride loading causes phase separation due to low compatibility of epoxy resin and boron nitride. As a result, thermal conductivity can not be formed due to failure to form a network for thermal conduction, and the phase coagulated boron nitride acts as a crack in the epoxy resin to generate stress concentration, thereby reducing mechanical properties.

It is an object of the present invention to provide a method for producing an epoxy composite having high compatibility between boron nitride and epoxy resin, thermal conductivity and mechanical properties.

One aspect of the present invention relates to a method for preparing boron nitride, comprising: (a) pre-treating boron nitride particles with a metal salt and an acid; (b) surface-treating the pretreated boron nitride particles with a silane-based compound; And (c) mixing the surface-treated boron nitride particles and the epoxy resin; Wherein the epoxy composite material is an epoxy composite material.

In one embodiment, the boron nitride may be a hexagonal boron nitride particle in the form of a plate.

In one embodiment, the average grain size of the boron nitride particles may be less than or equal to 1 占 퐉.

In one embodiment, the metal salt may be selected from the group consisting of sodium nitrate, lithium hypochlorite, lithium perchlorate, lithium manganese oxide, lithium nitrate, cesium nitrate, potassium chlorate, potassium permanganate and mixtures of two or more thereof .

In one embodiment, the acid may be selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and mixtures of two or more thereof.

In one embodiment, the pretreatment of step (a) may be performed at 160 to 250 ° C.

In one embodiment, the pretreatment of step (a) may be performed for 4 to 10 hours.

In one embodiment, the silane-based compound may be 3-aminopropyltriethoxysilane.

In one embodiment, the surface treatment of step (b) may be performed at 90 to 150 < 0 > C.

In one embodiment, the surface treatment of step (b) may be performed for 4 to 10 hours.

In one embodiment, the epoxy resin may be one selected from the group consisting of bisphenol A type.

According to one aspect of the present invention, boron nitride particles pretreated with a metal salt and an acid are surface-treated with a silane compound and then mixed with an epoxy resin to have high compatibility between boron nitride and an epoxy resin to form pores in the epoxy resin An epoxy composite excellent in thermal conductivity and mechanical properties can be produced.

It should be understood that the effects of the present invention are not limited to the effects described above, but include all effects that can be deduced from the description of the invention or the composition of the invention set forth in the claims.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic diagram of a pretreatment process and a surface treatment reaction mechanism of boron nitride particles. FIG.
FIG. 2 shows FT-IR analysis results of an epoxy composite material prepared according to an embodiment of the present invention.
FIG. 3 shows an XRD structure analysis result of an epoxy composite material produced according to an embodiment of the present invention.
4 is a TEM photograph of an epoxy composite prepared according to an embodiment of the present invention.
5 is a SEM photograph of an epoxy composite prepared according to an embodiment of the present invention.
FIG. 6 is a thermogravimetric analysis (TGA) result of an epoxy composite prepared according to an embodiment of the present invention.
FIG. 7 shows the thermal expansion analysis results of an epoxy composite material manufactured according to an embodiment of the present invention.
FIG. 8 shows the results of analysis of the storage elastic modulus and the loss elastic modulus of an epoxy composite material prepared according to an embodiment of the present invention.
9 is a graph showing the tan δ diagram of an epoxy composite produced according to an embodiment of the present invention.
FIG. 10 shows the thermal conductivity measurement results of an epoxy composite material manufactured according to an embodiment of the present invention.
11 shows the tensile strength test results of an epoxy composite material produced according to an embodiment of the present invention.
12 shows the results of the bending strength test of an epoxy composite material produced according to an embodiment of the present invention.
13 is a graph showing changes in fracture toughness of an epoxy composite material produced according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

One aspect of the present invention relates to a method for preparing boron nitride, comprising: (a) pre-treating boron nitride particles with a metal salt and an acid; (b) surface-treating the pretreated boron nitride particles with a silane-based compound; And (c) mixing the surface-treated boron nitride particles and the epoxy resin; Wherein the epoxy composite material is an epoxy composite material.

The boron nitride may be a hexagonal boron nitride particle having a plate-like shape. The hexagonal boron nitride particles have a strong covalent bond with boron and nitrogen bonded at a ratio of about 1: 1 and have a flat planar structure at the atomic level. It is preferable in the epoxy composite material because it has transparency, flexibility, excellent mechanical properties, thermal conductivity, and insulation properties at the time of exfoliation.

The average particle size of the boron nitride particles may be 1 占 퐉 or less, preferably 0.1 to 1 占 퐉, but is not limited thereto. When the boron nitride particles are larger than 1 mu m, the surface area becomes smaller and the compatibility with the epoxy resin becomes lower, thereby decreasing the thermal conductivity of the epoxy composite.

A schematic diagram of the pretreatment process of the boron nitride particles and the surface treatment reaction mechanism using the silane compound is shown in FIG. A swelling phenomenon occurs in the hexagonal boron nitride grains of the laminated structure by using an acid and a metal salt to increase the distance between the layer of the boron nitride grains and the layer during the pretreatment. Thereafter, when the surface treatment is performed using the silane-based compound, the layer and the layer of the boron nitride gradually become more distant from each other, causing chemical exfoliation, and the surface of each boron nitride layer becomes silane functionalized.

Wherein the metal salt is one selected from the group consisting of sodium nitrate, lithium hypochlorite, lithium perchlorate, lithium manganese oxide, lithium nitrate, cesium nitrate, potassium chlorate, potassium permanganate and mixtures of two or more thereof, preferably sodium nitrate However, the present invention is not limited thereto. The degree of swelling of the boron nitride particles is low when only the acid is used for the pretreatment of the boron nitride particles. For effective swelling, metal salts are introduced in the present invention. When the metal salt is dissolved in the acid, it acts as a strong oxidizing agent to promote the introduction of oxygen functional groups in the acid.

The acid is selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid and a mixture of two or more thereof, preferably sulfuric acid, but is not limited thereto. The chemical exfoliation of the boron nitride particles can be achieved by introducing a silane-based compound after swelling of the particles due to insertion of the boron nitride inter-layer oxygen functional group. The acid can introduce an oxygen functional group onto the surface of the boron nitride grains.

As used herein, the term " oxygen functional group " may include aliphatic alcohols, ketones, aldehydes, carboxylic acids, ethers, esters, hydrogen peroxides, and the like that contain functional groups containing oxygen as C-O bonds.

The pretreatment of step (a) may be performed at 160 to 250 ° C, preferably at 190 to 210 ° C, but is not limited thereto. When the pretreatment is carried out at a temperature lower than 160 ° C., the acid hardly swells the boron nitride particles. When the pretreatment is carried out at a temperature higher than 250 ° C., the metal salt or the acid used for the pretreatment may be decomposed, .

The pretreatment of step (a) may be carried out for 4 to 10 hours, preferably 6 to 8 hours, but is not limited thereto. When the pretreatment is performed for less than 4 hours, the boron nitride particles are not sufficiently swollen. When the pretreatment is performed for more than 10 hours, the degree of swelling of the boron nitride particles is uniform, resulting in lower energy efficiency.

The silane compound may be 3-aminopropyl triethoxysilane (3-APTS), but is not limited thereto. The silane-based compound is introduced into the surface and between the surfaces of the pretreated boron nitride particles to induce the chemical exfoliation of the boron nitride particles. Further, the boron nitride particles are functionalized with silane to increase compatibility with the epoxy resin.

The surface treatment in step (b) may be performed at 90 to 150 ° C, preferably 110 to 140 ° C, but is not limited thereto. When the surface treatment is performed at a temperature of less than 90 ° C, the reaction is difficult to proceed because the temperature is low. When the surface treatment is performed at a temperature higher than 150 ° C, a side reaction may occur due to a high temperature.

The surface treatment of step (b) may be performed for 4 to 10 hours, preferably 6 to 9 hours, but is not limited thereto. If the surface treatment is performed for less than 4 hours, sufficient time is not provided for the surface treatment, chemical peeling does not progress sufficiently, and when the treatment is performed for more than 10 hours, the chemical peeling of the boron nitride particles sufficiently progresses, .

The epoxy resin may be one selected from the group consisting of a bisphenol A type and preferably a diglycidyl ether of bisphenol A (DGBA), but is not limited thereto.

Hereinafter, embodiments of the present invention will be described in detail.

Example 1

(1) Pre-treatment of hexagonal boron nitride particles (Pretreated hBN)

5 g of hexagonal boron nitride (hBN) particles (98%, 1 탆 size) are added to a beaker together with a solution of 4.2 g of sodium nitrate and 200 ml of sulfuric acid and stirred at 200 캜 for 5 hours. The mixture is then filtered and washed with deionized water until the pH is neutral. The obtained particles were dried in an oven at 80 ° C for 12 hours to prepare pretreated boron nitride (Pretreated hBN).

(2) Surface treatment of pretreated hexagonal boron nitride particles (Si-hBN)

5 g of the particles obtained in the above step (1) are mixed with 5 ml of 3-APTS (3-aminopropyltriethoxysilane, ≥98%), 375 ml of ethanol and 122.5 ml of distilled water, and the mixture is stirred at 130 ° C for 8 hours. The resulting mixture was washed with distilled water and filtered, and the obtained particles were dried in an oven at 80 ° C for 12 hours to prepare surface-treated boron nitride (Si-hBN).

(3) Production of epoxy composites using surface treated boron nitride particles

10 wt% of the particles obtained in the above step (2) was introduced into a diglycidyl ether of bisphenol A (DGBA), stirred for 30 minutes through a mechanical stirrer, and a low viscosity polyamidoamine ) Was added at a ratio of 3: 2 with epoxy and stirred for 15 minutes. Thereafter, degassing was carried out in a vacuum oven for 30 minutes and then poured into a mold and molded at 80 ° C for 2 hours to prepare an epoxy composite material.

Example 2

An epoxy composite material was prepared in the same manner as in Example 1, except that the boron nitride particles were surface-treated in the step (3) of Example 1 at 1 wt%.

Example 3

An epoxy composite material was prepared in the same manner as in Example 1, except that the surface-treated boron nitride particles were added in an amount of 5 wt% in the step (3) of Example 1 above.

Comparative Example 1

10 wt% of hexagonal boron nitride (hBN) particles were added to a diglycidyl ether of bisphenol A (DGBA), stirred for 30 minutes through a mechanical stirrer, and a low viscosity polyamidoamine ) Was added at a ratio of 3: 2 with epoxy and stirred for 15 minutes. Thereafter, degassing was carried out in a vacuum oven for 30 minutes and then poured into a mold and molded at 80 ° C for 2 hours to prepare an epoxy composite material.

Comparative Example 2

An epoxy composite material was prepared in the same manner as in Comparative Example 1, except that the hexagonal boron nitride particles were added in an amount of 1 wt%.

Comparative Example 3

An epoxy composite material was prepared in the same manner as in Comparative Example 1, except that the hexagonal boron nitride particles were added in an amount of 5 wt%.

Comparative Example 4

(1) Surface treatment of hexagonal boron nitride particles

5 g of hexagonal boron nitride (hBN) particles are mixed with 5 ml of 3-APTS (3-aminopropyltriethoxysilane, ≥98%), 375 ml of ethanol and 122.5 ml of distilled water, and the mixture is stirred at 130 ° C for 8 hours. The resulting mixture was washed with distilled water and filtered, and the obtained particles were dried in an oven at 80 캜 for 12 hours to prepare surface-treated boron nitride.

(2) Production of epoxy composites using surface treated boron nitride particles

10 wt% of the particles obtained in the above step (1) was added to a diglycidyl ether of bisphenol A (DGBA), stirred for 30 minutes through a mechanical stirrer, and a low viscosity polyamidoamine ) Was added at a ratio of 3: 2 with epoxy and stirred for 15 minutes. Thereafter, degassing was carried out in a vacuum oven for 30 minutes and then poured into a mold and molded at 80 ° C for 2 hours to prepare an epoxy composite material.

Comparative Example 5

(1) Pretreatment of hexagonal boron nitride particles

5 g of hexagonal boron nitride (hBN) particles (98%, 1 탆 size) are added to a beaker together with a solution of 4.2 g of sodium nitrate and 200 ml of sulfuric acid and stirred at 200 캜 for 5 hours. The mixture is then filtered and washed with deionized water until the pH is neutral. The obtained particles were dried in an oven at 80 ° C for 12 hours to prepare pretreated boron nitride.

(2) Preparation of epoxy composites using pretreated boron nitride particles

10 wt% of the particles obtained in the above step (1) was added to a diglycidyl ether of bisphenol A (DGBA), stirred for 30 minutes through a mechanical stirrer, and a low viscosity polyamidoamine ) Was added at a ratio of 3: 2 with epoxy and stirred for 15 minutes. Thereafter, degassing was carried out in a vacuum oven for 30 minutes and then poured into a mold and molded at 80 ° C for 2 hours to prepare an epoxy composite material.

Comparative Example 6

An epoxy composite material was prepared in the same manner as in Example 1, except that acetic acid was used in place of sulfuric acid in the step (1) of Example 1.

The structure and characteristics of the epoxy composites prepared in the above Examples and Comparative Examples will be described with reference to the drawings.

FIG. 2 is a graph showing the relationship between the boron nitride particles (Raw BN) of Example 1, the pretreated boron nitride particles (Pretreated BN) prepared through the step (1), and the surface treated boron nitride particles + Silane treated BN). The results of the FT-IR spectroscopy are shown in Fig. The surface-treated boron nitride particles prepared in the step (2) of Example 1 clearly showed the absorption peak of the silane group (Si-O bond) at a wavenumber of 1101 cm ^-1 , Able to know.

FIG. 3 is a graph showing the relationship between the boron nitride particles (Raw BN) of Example 1, the pretreated boron nitride particles (Pretreated BN) prepared through the step (1), and the surface treated boron nitride particles + Silane treated BN) was investigated by XRD (X-ray diffraction) analysis. As a result, all three particles can find peaks at 2θ = 26 ° (002), 41 ° (100) and 55 ° (004). In the case of the pretreated boron nitride particles prepared in the step (1) of Example 1, there was almost no change at the peak of 55 ° (004), but the peaks of 26 ° (002) and 41 ° 100) is decreased. Especially at the 26 ° (002) peak. (002) and 41 (100) peaks of the surface treated boron nitride particles (Pretreated + Silane treated BN) prepared in the step (2) of Example 1 were higher than the boron nitride particles A higher peak can be seen.

FIG. 4 is a graph showing the results of the preparation of boron nitride particles (Raw BN), (b) pretreated boron nitride particles (Pretreated BN) prepared in (1) (Transmission Electron Microscope) images of surface treated boron nitride particles (Pretreated + Silane treated BN). As a result of analysis (a), boron nitride layers were stacked on each other. In the case of (b), the inter-layer distance due to the preprocessing is increased compared with the case of (a). (c), it can be confirmed that the interlayer overlapping frequency and chemical exfoliation of the boron nitride particles were induced by increasing the interlayer spacing due to the introduction of the silane compound.

5 is an SEM (Scanning Electron Microscope) image of (a) Comparative Example 1, (b) Comparative Example 5, and (c) In the case of Comparative Example 1, it was confirmed that the phase separation was induced due to the low compatibility between the boron nitride particles and the epoxy resin, so that the boron nitride particles were aggregated. In Comparative Example 5, the dispersion was better than Comparative Example 1, but the bonding force between the boron nitride particles and the epoxy resin was poor, so that a large amount of fine pores were generated as compared with Comparative Example 1. In the case of Example 1 as compared with Comparative Example 1, the compatibility with the epoxy resin was improved and uniform mixing was performed, and cohesion of the boron nitride particles or pores in the epoxy resin was hardly observed.

6 is a thermogravimetric analysis result of the epoxy composite prepared in Comparative Example 1, Comparative Example 5 and Example 1. FIG. When heated to 800 ° C, the epoxy composite prepared in Example 1 was about 3.57% more weight than the epoxy composite prepared in Comparative Example 1 and about 2.71% in weight than the epoxy composite prepared in Comparative Example 5 . This indicates that the surface treatment of the boron nitride particles through the silane compound improves the thermal performance of the epoxy composite.

The thermal expansion, viscoelasticity and thermal conductivity measurement, tensile strength, bending strength and fracture test were performed to confirm the activity of the epoxy composite obtained in the above Examples and Comparative Examples.

FIG. 7 shows the thermal expansion coefficients of the epoxy composites prepared in Comparative Example 1, Comparative Example 5, and Example 1 to evaluate the thermal stability. FIG. 7 (a) is a graph showing the thermal strain rate of the epoxy composite material. As the temperature increases, all the three epoxy composites increase. The epoxy composites prepared in Comparative Example 5, Comparative Example 1, and Example 1 exhibited high strain rates in that order.

In the graph of FIG. 7 (a), a singular point is found in the diagram due to the glass transition temperature at about 60 ° C, which is due to the method of the instrument being measured. The equipment used for the measurement is carried out in such a manner that the stress is generated by increasing the temperature while blocking the epoxy composite in both directions. Therefore, it can be seen that the increase in strain at the glass transition temperature shrinks. It appears that the strain is significantly reduced in the epoxy composite of Comparative Example 1 in which the double boron nitride particles are added. This is presumably due to the fact that the pores generated by the boron nitride particles agglomerated in the epoxy resin were very poor in dispersibility and could not transfer the thermal stress applied to the epoxy resin due to the thermal expansion.

On the other hand, the epoxy composite prepared in Example 1 shows a slope of the rising curve at a glass transition temperature, but the decrease of the slope is relatively small. It is considered that the pores generated due to thermal expansion are relatively small and uniformly distributed due to excellent compatibility with epoxy resin, and the thermal stress is well dispersed and transmitted.

7 (b) is a technical alpha line obtained by differentiating the thermal strain curve with the unit temperature by the thermal expansion coefficient. It can be seen that the coefficient of thermal expansion continues to increase with increasing temperature, then increases again after decreasing at the glass transition temperature. The epoxy composite prepared in Example 1 exhibited an average thermal reduction of about 4% compared to the other two epoxy composites because the bonding strength between the boron nitride particles and the epoxy resin due to the surface treatment using the silane compound And it resists thermal expansion inside. This suggests that the use of thermally conductive adhesives for packaging materials for electronic devices may reduce the peeling phenomena due to repeated thermal expansion and shrinkage, thereby increasing the service life.

FIG. 8 is a graph showing the results of measuring the storage elastic modulus and the loss elastic modulus in response to stress and strain due to the elastic modulus of the epoxy composite prepared in Comparative Example 1, Comparative Example 5, and Example 1. FIG.

8 (a) is a graph showing the storage elastic modulus, which corresponds to the reaction of the sample generated with the periodic stress and the reversible elasticity of the sample. It can be seen that the epoxy composite prepared through Example 1 has the highest storage elastic modulus at 2.86 GPa at room temperature. This is because the mutual bonding force is increased due to excellent compatibility between the boron nitride particles and the epoxy resin.

FIG. 8 (b) is a graph showing the loss elastic modulus, which corresponds to the mechanical energy which is phase-shifted up to 90.degree. C. and is converted into heat and irreversibly lost. The epoxy composite prepared in Example 1 had the highest loss modulus of 146 MPa.

9 is a graph showing a tan? Diagram obtained by dividing the loss elastic modulus of the epoxy composite material prepared in Comparative Example 1, Comparative Example 5 and Example 1 by the storage modulus. The peak point in this graph is the glass transition temperature. Peaks were observed at about 56 ° C, 60 ° C and 64 ° C in the order of the epoxy composites prepared in Comparative Example 1, Comparative Example 5 and Example 1, which showed not only compatibility in the epoxy resin of the boron nitride particles, It is believed that the bonding strength between the particles and the epoxy resin is increased, which further resists the micro-Brownian motion due to thermal energy. In the polymer, the shape of the chain changes constantly as a result of the bond rotation of the bond, in addition to the translation and rotation of the molecule as a whole at a temperature or in a molten state above the glass temperature, and is severely curved.

10 shows the results of thermal conductivity measurements of the epoxy composites prepared in Examples 1 to 3, Comparative Examples 1 to 3, Comparative Examples 4 and 6. When the content of boron nitride particles was 0%, that is, 0.17 W / mK for pure epoxy resin, the thermal conductivity was the lowest, 0.225 W / mK for epoxy composite prepared in Example 2, 3, the thermal conductivity increased as the content of boron nitride grains injected into the epoxy resin increased, which was 0.266 W / m · K for the epoxy composite prepared through Example 1 and 0.35 W / m · K for the epoxy composite prepared through Example 1 Able to know.

It can be seen that the thermal conductivity of the epoxy composites prepared in Comparative Examples 1 to 3 is increased as the content of boron nitride grains injected into the epoxy resin is increased similarly to Examples 1 to 3. However, it can be confirmed that the thermal conductivity is lower than that of the epoxy composite prepared in Examples 1 to 3. This is due to the excellent compatibility between the boron nitride particles and the epoxy resin due to the effect of the pretreatment using the metal salt and the acid and the surface treatment using the silane compound, .

In the case of the epoxy composite prepared in Comparative Example 4, there is no significant difference in thermal conductivity from the epoxy composite prepared in Comparative Example 1. As a result, it can be seen that when the silane-based compound alone is introduced into the boron nitride particles not subjected to the pretreatment, the effect is not excellent in compatibility between the boron nitride particles and the epoxy resin.

The epoxy composite prepared in Comparative Example 6 has a lower thermal conductivity than the epoxy composite prepared in Example 1 and the thermal conductivity is lower than that of the epoxy composite prepared in Comparative Example 3 . This shows that the pretreatment of the boron nitride particles is superior to the acetic acid in the ability to swell the sulfuric acid.

11 is a graph of stress strain of epoxy composites prepared by Examples 1 to 3 and Comparative Examples 1 to 3. It can be seen that the tensile strength of the epoxy composite prepared through Examples 1 to 3 increases as the content of the boron nitride particles is increased. However, in the case of the epoxy composite prepared through Comparative Examples 1 to 3, the tensile strength was decreased when the content of the charged boron nitride particles was increased. This is because when the boron nitride particles are added to the epoxy resin without the pretreatment and the surface treatment using the silane compound, the compatibility is poor and induces phase separation, because the phase-separated and aggregated boron nitride particles induce stress concentration in the epoxy composite.

12 is a graph showing the bending coefficients of the epoxy composites prepared in Examples 1 to 3 and Comparative Examples 1 to 3. The epoxy composites prepared in Comparative Examples 1 to 3 showed no difference in the flexural modulus. However, in the case of the epoxy composite (pretereated + silane treated BN) prepared in Examples 1 to 3, as the content of boron nitride particles increased The flexural modulus increased.

13 is a graph showing changes in fracture toughness of epoxy composites prepared in Examples 1 to 3 and Comparative Examples 1 to 3. It can be seen that as the content of boron nitride particles increases regardless of the examples and comparative examples, the fracture toughness decreases gradually because the epoxy composite becomes brittle. Here, brittleness is a property that a material is destroyed without permanent deformation by an external force, or only a part is permanently deformed and destroyed. The epoxy prepared in Examples 1 to 3 had an average increase in fracture toughness slightly in comparison with the epoxy composite prepared in Comparative Examples 1 to 3.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (11)

(a) pre-treating boron nitride particles with a metal salt and an acid;
(b) surface-treating the pretreated boron nitride particles with a silane-based compound; And
(c) mixing the surface-treated boron nitride particles and the epoxy resin;
≪ / RTI > The method according to claim 1,
Wherein the boron nitride is a hexagonal boron nitride particle having a plate-like shape. The method according to claim 1,
Wherein the average particle size of the boron nitride particles is 1 占 퐉 or less. The method according to claim 1,
Wherein the metal salt is one selected from the group consisting of sodium nitrate, lithium hypochlorite, lithium perchlorate, lithium manganese oxide, lithium nitrate, cesium nitrate, potassium chlorate, potassium permanganate, and mixtures of two or more thereof. The method according to claim 1,
Wherein the acid is one selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and a mixture of two or more thereof. The method according to claim 1,
Wherein the pretreatment in step (a) is performed at 160 to 250 占 폚. The method according to claim 1,
Wherein the pretreatment of step (a) is performed for 4 to 10 hours. The method according to claim 1,
Wherein the silane compound is 3-aminopropyltriethoxysilane. The method according to claim 1,
Wherein the surface treatment of step (b) is carried out at 90 to 150 占 폚. The method according to claim 1,
Wherein the surface treatment of step (b) is performed for 4 to 10 hours. The method according to claim 1,
Wherein the epoxy resin is one selected from the group consisting of bisphenol A type epoxy resins.

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