KR101274975B1 - Thermally conductive materials based on thermally conductive hollow particles and fabrication method thereof - Google Patents

Abstract

The present invention relates to a thermally conductive composite material comprising a thermally conductive hollow particle, comprising a thermally conductive hollow particle and a polymer resin, wherein the thermally conductive hollow particle is dispersed in the polymer resin while maintaining a hollow form. It is characterized in that, the thermally conductive composite material of the present invention is a material having a significantly increased thermal conductivity by forming a heat transfer path therein even under a much lower thermal conductor content, material for electronic packaging by such excellent thermal conductivity Very useful as In addition, since the thermally conductive composite material of the present invention has a relatively small content of filler particles for achieving a desired thermal conductivity, it is possible to manufacture a low-density component material having excellent fluidity, toughness, workability, and productivity.

Description

Thermally conductive composites including thermally conductive hollow particles and a method for manufacturing the same

The present invention relates to a thermally conductive composite including a thermally conductive hollow particle, more specifically, to prepare a thermal conductor having excellent thermal conductivity in the form of hollow fine particles and to disperse it in a polymer resin, even in a low thermal conductor content conditions By forming a heat transfer path, the present invention relates to a thermally conductive composite having excellent thermal conductivity and a method of manufacturing the same.

IC packages such as CPUs, which are electronic components mounted on printed wiring boards, may degrade or be damaged due to temperature rise due to heat generation during operation. A heat conductive sheet or a heat dissipating grease having good thermal conductivity is essentially used.

Recently, the amount of heat generated during the operation of electronic devices has also increased greatly due to the large increase in the amount of power consumed due to the rapid reduction of the weight of electronic devices, high integration, and high performance. The need for more effective thermal management materials is emerging from the fact that more than 80% of the malfunctions of electronic devices are caused by heat. In addition, in the flip chip technology, there is an increasing demand for interfacial materials that effectively transfer heat emitted from high-performance devices to a heat sink or heat spreader.

Accordingly, the characteristics required for electronic packaging materials require much higher thermal conductivity than conventional thermally conductive materials in order to smoothly dissipate heat. In addition, as a connection material connecting the electronic device and the circuit, it is a cause of breakdown of the electronic device adhesive layer. In addition to the properties for minimizing the occurrence of thermal stress due to shrinkage-expansion, high strength and toughness, low density, low cost, near-net shape manufacturing process is required.

Currently, as a thermal conductive material in the field of most microelectronic packaging, ceramic materials having excellent thermal conductivity, for example, aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), boron nitride (BN), carbon black (CB), carbon nanotubes (CNT), silicon carbide (SiC) and the like are partially used or researched and developed in a form filled with a high content in a polymer resin or a silicone resin such as epoxy.

In order to produce high thermal conductivity in a composite composed of such a conventional inorganic thermal conductor dispersed in a polymer-based or silicone-based resin as a filler, the presence or absence of a heat transfer path by the inorganic thermal conductor is important. High content of is required. However, in this case, due to the high viscosity and low fluidity of the polymer composite caused by the high content of the thermally conductive inorganic component and the aggregation of the inorganic particles caused by the weak compatibility between the inorganic thermally conductive filler and the organic polymer matrix component. Due to the extremely poor processability and the weakness of the thermal conductivity, which are caused by the big problems, the thermal management material in the electronic package field that can cope with the miniaturization, high density, and high speed of the current electronic devices should be further complemented. Situation.

Japanese Patent Application Laid-Open Nos. 61 (1986) -157569 and 63 (1988) -251466 include spherical alumina powders having an average particle size of 10 to 50 in resins of organic polysiloxanes and organic hydrogen polysiloxanes, spherical or ratios of less than 10 The thermal conductive silicone rubber composition which consists of spherical alumina powder and a platinum or a platinum compound is described.

Japanese Patent Application Laid-Open No. 02 (1991) -041362 discloses an organic polysiloxane containing an alkenyl group, an amorphous alumina powder having an average particle size of 0.1 to 5, a spherical alumina powder having an average particle size of 5 to 50, and a resin of an organic hydrogen polysiloxane. A thermally conductive silicone rubber composition comprising a platinum catalyst is described.

Japanese Patent Application Laid-Open No. 02-041362 discloses organic polysiloxanes containing two or more silicon-bonded alkenyl groups per molecule, organic hydrogen polysiloxanes containing three or more silicon-bonded hydrogen atoms per molecule, and an average particle size of 5 Reference is made to thermally conductive silicone rubber compositions consisting of thermally conductive fillers, adhesion promoters, and platinum or platinum compounds of from 20 to 20.

However, in order to form highly thermally conductive silicone rubber from such thermally conductive silicone rubber compositions, it is necessary to pay attention to the amount of thermally conductive fillers in the thermally conductive silicone rubber composition, which increases their handling characteristics and formability as the filler content increases. A problem arises. In addition, it is difficult to provide a sufficient heat conduction network only with the particles close to the existing spherical form, the content of the filler particles is excessive, there is a problem that the flowability and moldability is reduced while the content of the resin is reduced.

Accordingly, the first problem to be solved by the present invention is to provide a thermally conductive composite of a novel structure that can reduce the content of the thermal conductor to improve the fluidity, toughness, processability, etc. of the polymer composite and at the same time can express excellent thermal conductivity.

The second problem to be solved by the present invention is to provide a method for producing the thermally conductive composite.

The present invention to achieve the first object,

Thermally conductive hollow particle bodies; And a thermally conductive composite comprising a polymer resin;

The thermally conductive hollow particle body is made of any one selected from carbon nanotubes, graphene, graphite nanosheets, aluminum nitride, boron nitride and aluminum oxide,

The carbon nanotubes, graphene and graphite nanosheets are each independently introduced with functional groups of a carboxyl group and a hydroxyl group, and the aluminum nitride, boron nitride and aluminum oxide are each independently treated with a titanate binder. It is,

The polymer resin is any one selected from silicone resin, epoxy resin, phenol resin and polyethylene resin,

The thermally conductive hollow particles are dispersed in the polymer resin while maintaining a hollow shape to provide a thermally conductive composite.

According to one embodiment of the invention, the thermally conductive hollow particles may be dispersed in the polymer resin in 1-20% by weight relative to the total weight of the thermally conductive composite.

According to another embodiment of the present invention, the polymer resin may be a bisphenol-based epoxy resin or a high density polyethylene resin.

According to another aspect of the present invention,

(a) pretreating the thermally conductive particles to produce thermally conductive particles with modified surfaces;

(b) preparing a polymer-thermally conductive composite particle coated with the thermally conductive particles on a surface of a polymer microparticle;

(c) heat-treating the polymer-thermally conductive composite particles to remove the polymer to prepare a thermally conductive hollow particle body; And

(d) dispersing the thermally conductive hollow particles in a polymer resin;

The thermally conductive particles are any one selected from carbon nanotubes, graphene and graphite nanosheets; Or any one selected from aluminum nitride, boron nitride and aluminum oxide;

The polymer fine particles are any one selected from polystyrene, polymethacrylate and polyacrylate,

The polymer resin provides a method for producing a thermally conductive composite, characterized in that any one selected from silicone resin, epoxy resin, phenol resin and polyethylene resin.

According to one embodiment of the present invention, the polymer fine particles are prepared by dispersion polymerization of an aromatic vinyl compound or an unsaturated carboxylic acid ester compound as a monomer, and the aromatic vinyl compound is styrene, α-methylstyrene, α-chlorostyrene, p-tert-butylstyrene, p-methylstyrene, p-chlorostyrene, o-chlorostyrene, 2,5-dichlorostyrene, 3,4-dichlorostyrene, dimethylstyrene and divinylbenzene The unsaturated carboxylic ester compound may be any one selected from methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate and butyl methacrylate. .

According to another embodiment of the present invention, the diameter of the polymer microparticles may be 0.1-10 ㎛.

According to an embodiment of the present invention, the modified thermally conductive particles of step (a) are treated with hydrazine and ammonia to introduce carbon nanotubes, graphene or graphite nanosheets into which functional groups of carboxyl and hydroxyl groups are introduced. Can be.

According to another embodiment of the present invention, by controlling the mass ratio of the hydrazine and ammonia to control the ion concentration on the surface of the carbon nanotube, graphene or graphite nanosheet, the mass ratio of hydrazine and ammonia can be 1: 1-20 have.

According to another embodiment of the present invention, the modified thermally conductive particles of step (a) may be aluminum nitride, boron nitride or aluminum oxide surface treated with a titanate binder.

According to another embodiment of the present invention, in the step (b), the surface-modified thermally conductive particles and the polymer fine particles are dispersed in a mixed solvent of isopropyl alcohol and deionized water, followed by stirring to coat the thermally conductive particles. Polymer-thermally conductive composite particles can be prepared.

According to another embodiment of the present invention, the step (c) may remove the polymer by heat-treating the polymer-thermal conductive composite particles in a nitrogen atmosphere of 250-400 ℃.

According to another embodiment of the present invention, in the step (d), the thermally conductive hollow particles may be dispersed in the polymer resin at 1-20% by weight based on the total weight of the thermally conductive composite.

The thermally conductive composite material of the present invention prepares the hollow microparticles with a thermal conductor having excellent thermal conductivity, and disperses it in the polymer resin, so that the heat transfer path is internally maintained even in a condition where the thermal conductor content is much lower than in the case where the thermal conductor is simply dispersed in the polymer resin. The thermally conductive composite material according to the present invention is very useful as an electronic packaging material because of its excellent thermal conductivity. In addition, since the thermally conductive composite material of the present invention has a relatively small content of filler particles for achieving a desired thermal conductivity, it is possible to manufacture a low-density component material having excellent fluidity, toughness, workability, and productivity.

1 is a conceptual diagram showing a network configuration of a thermally conductive hollow particle-based thermally conductive composite according to the present invention.
2a to 2c are electron micrographs of the aluminum nitride-based hollow particle body prepared according to an embodiment of the present invention,
Figure 2a is a scanning electron micrograph of the polymer particles, Figure 2b is a scanning electron micrograph of the polymer particles coated with aluminum nitride particles, Figure 2c is an aluminum nitrate after the polymer component is removed from the aluminum nitride-polymer composite particles It is a transmission electron microscope photograph of the ride hollow particle body.
3A to 3C are electron micrographs of graphite nanosheets-based hollow particle bodies prepared according to an embodiment of the present invention.
Figure 3a is a scanning electron micrograph of the polymer particles, Figure 3b is a scanning electron micrograph of the polymer particles coated with graphite nanosheets on the surface, Figure 3c is a scanning electron micrograph of the graphite nanosheets hollow particle body.

Hereinafter, the present invention will be described in more detail.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermally conductive composite for electronic packaging having high thermal conductivity and excellent processability. In particular, a thermal conductor having excellent thermal conductivity is prepared in the form of hollow fine particles and dispersed in a polymer resin, whereby the thermal conductor is simply dispersed in the polymer resin. Compared to the case, by forming a heat transfer path even at a much lower thermal conductor content condition, the low thermal conductivity and poor processability of the composite of the conventional thermal conductor filler-polymer resin composition are overcome.

The present invention is a thermally conductive composite comprising a thermally conductive hollow particles and a polymer resin, wherein the thermally conductive hollow particles are carbon nanotubes, graphene, graphite nanosheets, aluminum nitride, boron nitride and aluminum oxide The carbon nanotube, graphene and graphite nanosheets are each independently selected from a functional group of a carboxyl group and a hydroxyl group, and the aluminum nitride, boron nitride and aluminum oxide are each independently selected. Surface-treated with a titanate binder, wherein the polymer resin is any one selected from silicone resins, epoxy resins, phenol resins, and polyethylene resins, and the thermally conductive hollow particles maintain the hollow shape in the polymer resin. To be distributed It shall be.

The thermally conductive hollow particles dispersed in the polymer resin can realize a very good thermal conductivity even when the content of the structure is small, and further increases the thermal conductivity as the content is increased, but the processability, toughness, In consideration of fluidity and productivity, it is preferable to disperse the polymer resin in a content of 20% by weight or less.

In addition, the present invention provides a method for producing the thermally conductive composite, the production method according to the present invention comprises the steps of (a) preparing the thermally conductive particles, the surface of which is modified by pre-treating the thermally conductive particles; (b) preparing a polymer-thermally conductive composite particle coated with the thermally conductive particles on a surface of a polymer microparticle; (c) heat-treating the polymer-thermally conductive composite particles to remove the polymer to prepare a thermally conductive hollow particle body; And (d) dispersing the thermally conductive hollow particle body in a polymer resin, wherein the thermally conductive particles are any one selected from carbon nanotubes, graphene, and graphite nanosheets; Or any one selected from aluminum nitride, boron nitride, and aluminum oxide; and the polymer microparticles are any one selected from polystyrene, polymethacrylate, and polyacrylate, and the polymer resin is silicone resin, epoxy resin, or phenol. It is characterized in that it is any one selected from resin and polyethylene resin.

The thermally conductive particles whose surface has been modified are nanocarbon materials such as CNT, graphene, graphite nanosheets, or titanate-based CNTs, graphene, graphite nanosheets having polar functional groups such as -COOH, -OH and ionic functional groups introduced to the surface through a redox reaction. It is characterized in that the ceramic material, such as aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), boron nitride (BN) is a surface treatment using a binder.

In particular, the graphite nanosheets are treated with hydrazine and ammonia to pretreat the graphite nanosheets to introduce carboxyl and hydroxyl groups to the surface.

At this time, the degree of progress of the reduction reaction on the graphite nanosheet surface can be controlled by the mass ratio of hydrazine and ammonia used, whereby the concentration of the graphite nanosheet surface ions is controlled. At this time, the weight ratio of hydrazine and ammonia is preferably 1: 1 to 1:20 to surface treatment.

Thereafter, a coating layer is formed on the surface of the polymer fine particles to have a thickness of several tens to several hundred nanometers to obtain a polymer-thermal conductor composite particle.

The graphene or graphite nanosheets usable in the present invention are not particularly limited in low crystallinity, high crystallinity, and the like, and can be prepared from graphite by conventional mechanical peeling and physicochemical peeling. AlN, BN, and the like were purchased from commercially available products.

There are two common methods of obtaining graphite nanosheets from graphite, which are mechanical peeling and physicochemical peeling. The mechanical peeling method is a method of stacking graphite particles by repeatedly attaching and removing a conventional adhesive tape onto a graphite mass. The physicochemical exfoliation method is to break the structure and oxidative reaction between the surface of the graphite and the interlayer structure in the state of dispersing the graphite layer having the laminated structure in a suitable solvent to expand the space between the layers and the other materials Surface adsorption and eventually a process of completely peeling it off.

In the present invention, the graphite nanosheets were obtained in the following examples using the latter method, but the scope of the present invention is not limited thereto.

Physical properties of the thermal conductor and the polymer resin used in the present invention are as shown in the following [Table 1].

matter Density (g / cm 3) Thermal conductivity (W / mK) Suzy
Epoxy resin 1.2 0.33 HDPE 0.945 0.25 Thermal conductor

AlN 3.26 200 graphene 1.5-1.7 2000-3000 BN 2.27 30-80

The polymer fine particles in the form of beads usable in the present invention may include all polymers usable in the art, and the size thereof may also be modified to any size generally available. However, in order to form stable thermally conductive hollow particles and to realize improved physical properties, polystyrene-based, polymethylmethacrylate-based, and polyacrylate-based polymers are preferable, and from 0.1 μm to a single process obtained through dispersion polymerization from monomers 10 μm in size It is preferable that it is a polymer microparticle.

Examples of the monomer used for producing the polymer fine particles include hydrophobic vinyl compounds such as aromatic vinyl compounds and unsaturated carboxylic acid ester compounds.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, α-chlorostyrene, p-tert-butylstyrene, p-methylstyrene, p-chlorostyrene, o-chlorostyrene, 2,5-dichlorostyrene, 3,4-dichloro Styrene, dimethyl styrene, divinylbenzene, and the like. In addition, examples of the unsaturated carboxylic acid ester compound include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate and butyl methacrylate.

In order to selectively remove only the polymer component from the polymer-thermal conductor composite particle, the polymer particles are selectively removed by a pyrolysis method to obtain hollow hollow particles having a hollow form only of the heat conductor filler component. The hollow particle body may be prepared by heat treatment at a temperature condition of 250 ° C. to 400 ° C. for 1 to 5 hours.

In the following examples, a tubular furnace in a nitrogen atmosphere was used to easily remove a small amount of polymer and to facilitate analysis, but other methods such as pyrolysis or removal of solvent-based polymer in a box-type furnace may be used. have.

2 and 3 are electron micrographs of hollow particles prepared based on AlN and graphite nanosheets, respectively, as thermal conductor components, and it can be confirmed that the removal of the polymer component by heat treatment is effectively terminated.

In order to disperse the hollow particles in the polymer resin, after dispersing and mixing the hollow particles and the polymer resin in toluene as a solvent, an ultrasonic bath is used, and a vacuum oven is used to remove the dispersion solvent. In the following examples, an ultrasonic bath that is easy to disperse a small amount of content for characterization is used, but other mechanical methods such as mechanical stirring, paste mixer, and ball milling may be used.

As the polymer resin, a liquid resin such as a silicone resin, a resin in a paste state such as an epoxy resin or a phenol resin, and a solid thermoplastic resin capable of extrusion and injection such as high density polyethylene (HDPE) can be used. At this time, the total content of the thermally conductive hollow particles is preferably 20% by weight or less based on the total volume of the thermally conductive material from the viewpoint of ensuring processability.

Compared with the case where the same weight ratio of the thermal conductors is added, when the hollow particles are added, the thermal conductivity can be increased by 100% or more. (The following [Table 2] and [Table 3]) In the case of dispersing the filler having a significantly higher thermal conductivity than the polymer matrix in the composite, in the case where the thermally conductive filler is simply mixed with the matrix component, the absence of the heat transfer path due to the severe coagulation of the thermally conductive filler and the interface between the heat carrier and the polymer resin Due to the phonon scattering effect, the thermal conductivity change according to the thermally conductive filler content is minute, and when a certain level is reached, no further thermal conductivity increases. Even if graphite nanosheets or aluminum nitrate are present in the composite at a high content above the percolation concentration, it can be seen that there is no significant change in thermal conductivity when they are simply dispersed.

On the other hand, in the case of dispersing the hollow particles according to the present invention, a large increase in thermal conductivity was found under the same volume content conditions.If the heat carrier filler component was dispersed in the form of hollow particles, the content of the heat carrier component was low. The heat transfer path can be configured to solve the problem of poor moldability and fluidity due to the decrease of the polymer resin content due to the excessive content of the heat conductor filler, and the weak workability, and to maintain the processability of the conventional polymer resin. It is also shown that it is very effective in raising the thermal conductivity.

Thus, according to the present invention, it is possible to obtain an electronic packaging material having a high thermal conductivity and excellent processability, the content of the filler particles for achieving the desired thermal conductivity is relatively reduced, the flowability, toughness and workability, the electron having excellent productivity Packaging part materials can be manufactured.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be clear to those who have knowledge.

<Examples>

Examples 1-4. Preparation of Thermally Conductive Composites Comprising Graphite Nanosheet-Based Thermally Conductive Hollow Particles

(1) step 1: pretreatment step of thermal conductor particles

The graphite was pulverized and oxidized to form graphite oxide, and then dispersed by ultrasonic treatment to obtain an oxidized graphite nanosheet, which was treated with hydrazine and ammonia to obtain a graphite nanosheet having a carboxyl group and a hydroxyl group introduced thereon. When the mass ratio of hydrazine and ammonia was 1: 1-20, a graphite nanosheet having a carboxyl group and a hydroxyl group introduced thereon was obtained.

(2) step 2: preparing polymer-thermal conductor composite particles

The thermally conductive hollow particle body was prepared using the graphite nanosheets prepared in step 1 as a thermal conductor component. Cationic polystyrene fine particles (1.0 g) dispersed in 200 mL of isopropyl alcohol (IPA) and 10 mL of deionized water were mixed. 0.1 g of the graphite nanosheets prepared in step 1 was added to 200 mL of the dispersed graphite nanosheet solution, and then stirred at a speed of 100 rpm for 24 hours to coat the graphite nanosheets with polystyrene fine particles, thereby obtaining the graphite nanosheet-polymer composite particles. Was prepared.

(3) step 3: heat conductive hollow particle sieve manufacturing step

The graphite nanosheet-polymer composite particles were prepared by using a tubular furnace at 500 ° C. and a nitrogen atmosphere to remove polymer components in the composite particles, thereby preparing hollow nanoparticles based on graphite nanosheets.

3 is an electron micrograph of the prepared graphite nanosheet-based hollow particle body.

(4) Step 4: Mixing Hollow Particle and Thermosetting Polymer Matrix

In the mixing method, the hollow nanoparticles based on the graphite nanosheets and the polymer matrix are prepared by dispersing each of the hollow nanoparticles and the polymer resin in toluene as a solvent, followed by mixing and using an ultrasonic bath to improve dispersion. A vacuum oven was used to remove the solvent used in the dispersion. As the polymer matrix, bisphenol A resin, which is generally used as an epoxy resin having excellent properties for bonding organic and inorganic materials, is used as a thermosetting resin, and as a curing agent, an anhydride-based curing agent and an imidazole-based curing agent for promoting curing Accelerators were used.

Examples 1 to 4 vary the content of the thermally conductive hollow particles based on the graphite nanosheets, which is 0 wt% in Example 1, 1 wt% in Example 2, 5 wt% in Example 3, and Example 4 Is 10 wt%.

(5) Step 5: thin film manufacturing and curing step

end. In order to prepare a 40 탆 thick film (for electrical conductivity measurement) using a doctor blade method and to remove internal pores and residual solvents that may occur during thin film manufacturing, the thermally conductive hollow particle composite mixed with the epoxy resin is prepared using a doctor blade method. 0.1 MPa at 25 ° C. vacuum oven for 40-60 minutes.

I. In addition, in order to measure the coefficient of thermal expansion, a film having a thickness of 1 mm was prepared. The prepared film was prepared by curing at 130 ° C. for 1 hour and then post-curing at 160 ° C. for 2 hours.

Examples 5 to 6. Preparation of Thermally Conductive Composites Comprising Aluminum-Nitelite-Based Thermally Conductive Hollow Particles

(1) step 1: pretreatment step of thermal conductor particles

The thermal conductor particles of the aluminum nitride (AlN) component were pretreated using a titanate binder (KR-138S). The titanate binder in an amount of 0.5 wt% of the thermal conductor particles was dissolved in isopropyl alcohol (IPA), and then the thermal conductor was added to the solution, and kneaded at 70 ° C. for 2 hours using a mechanical stirrer. . The amount of IPA used at this time was about three times the volume of the thermal conductor to be used. The treated heat conductor was vacuum dried at 100 ° C. for 24 hours to completely remove IPA, and then stored at 100 ° C. to prevent contact with moisture.

(2) step 2: preparing polymer-thermal conductor composite particles

An aluminum nitride prepared in Step 1 was used as a heat conductor component to prepare a heat conductive hollow particle body. 1.0 g of cationic polystyrene fine particles were added to 200 mL of IPA in which 0.1 g of AlN 0.1 g pretreated in step 1 was dispersed, followed by stirring in the same manner as in Examples 1 to 4- (2). Phosphorus AlN-polymer composite particles were prepared.

(3) step 3: heat conductive hollow particle sieve manufacturing step

For the AlN-polymer composite particles prepared above, AlN-based hollow particle bodies were prepared by removing polymer components in the composite particles using a tubular furnace at 500 ° C. and a nitrogen atmosphere.

2 is an electron micrograph of the prepared AlN-based hollow particle body.

(4) Step 4: Mixing Hollow Particle and Thermosetting Polymer Matrix

The mixing method was a step of mixing the prepared AlN-based hollow particle body and the polymer matrix was dispersed after each of the hollow particle body and the polymer resin in a solvent toluene was mixed and used to ultrasonic dispersion to improve the dispersion degree, A vacuum oven was used to remove the solvent utilized in the dispersion. As the polymer matrix, bisphenol A resin, which is generally used as an epoxy resin having excellent properties for bonding organic and inorganic materials, is used as a thermosetting resin. An anhydride-based curing agent and an imidazole-based curing agent for promoting curing are used as a curing agent. Accelerators were used.

Examples 5 to 6 vary the content of aluminum nitride based thermally conductive hollow particle bodies, with Example 5 being 0 wt% and Example 6 being 5 wt%.

(5) Step 5: The thin film manufacturing and curing step was prepared in the same manner as the steps of Examples 1 to 4.

Examples 7 to 8. Preparation of Thermally Conductive Composites Comprising Boron Nitride-based Thermally Conductive Hollow Particles

(1) step 1: pretreatment step of thermal conductor particles

The thermal conductor particles of the boron nitride (BN) component were pretreated using a titanate binder (KR-138S). The titanate binder in an amount of 0.5 wt% of the thermal conductor particles was dissolved in isopropyl alcohol (IPA), and then the thermal conductor was added to the solution, and kneaded at 70 ° C. for 2 hours using a mechanical stirrer. . The amount of IPA used at this time was about three times the volume of the thermal conductor to be used. The treated heat conductor was vacuum dried at 100 ° C. for 24 hours to completely remove IPA, and then stored at 100 ° C. to prevent contact with moisture.

(2) step 2: preparing polymer-thermal conductor composite particles

Using the boron nitride prepared in step 1 as a thermal conductor component to prepare a thermally conductive hollow particle body. 1.0 g of cationic polystyrene fine particles were added to 200 mL of IPA in which 0.1 g of BN 0.1 g pretreated in step 1 was dispersed, followed by stirring in the same manner as in Examples 1 to 4- (2). Phosphorus BN-polymer composite particles were prepared.

(3) step 3: heat conductive hollow particle sieve manufacturing step

For the BN-polymer composite particles prepared above, BN-based hollow particle bodies were prepared by removing polymer components in the composite particles using a tubular furnace at 500 ° C. and a nitrogen atmosphere.

(4) Step 4: Mixing Hollow Particle and Thermosetting Polymer Matrix

The mixing method was a step of mixing the prepared BN-based hollow particle body and the polymer matrix was dispersed after each of the hollow particle body and the polymer resin in toluene as a solvent, and mixed with each other, using an ultrasonic bath to improve the degree of dispersion, A vacuum oven was used to remove the solvent utilized in the dispersion. As the polymer matrix, bisphenol A resin, which is generally used as an epoxy resin having excellent properties for bonding organic and inorganic materials, is used as a thermosetting resin, and as a curing agent, an anhydride-based curing agent and an imidazole-based curing agent for promoting curing Accelerators were used.

Examples 5 to 6 vary the content of the boron nitride-based thermally conductive hollow particulate body, and Example 5 is 0 wt% and Example 6 is 5 wt%, respectively.

(5) Step 5: The thin film manufacturing and curing step was prepared in the same manner as the steps of Examples 1 to 4.

Comparative Examples 1 to 8. Preparation of Composites with Simple Dispersion of Thermal Conductor Fillers

The graphite nanosheets prepared in each step 1 of Examples 1 to 8 (Comparative Examples 1 to 4), aluminum nitride, and boron nitride were used as thermal conductors. Toluene was used as a solvent for the dispersion of the filler, and the filler was dispersed for 1 hour using ultrasonic waves in the solvent. The bisphenol A-based epoxy resin was mixed with the toluene solution, an ultrasonic bath was used to improve dispersion, and a vacuum oven was used to remove the solvent used for dispersion. As a hardening | curing agent, the anhydride type hardening | curing agent and the imidazole type hardening accelerator for accelerating hardening were utilized.

Comparative Examples 1 to 4 are each 0, 1, 5, 10 wt% of the graphite nanosheets, Comparative Examples 5 to 6 are each 0, 5 wt% of the aluminum nitride, In Comparative Examples 7 to 8, the content of boron nitride was 0 and 5 wt%, respectively.

Comparative Examples 9 to 11 Preparation of Thermally Conductive Composites Prepared by Different Polymer Matrix Resins

Instead of the epoxy resin used in the preparation of Examples 1 to 4, a high-density polyethylene (HDPE), which is easy to mold the test piece through injection molding, was used as the thermoplastic polymer matrix. The hollow particle body of the graphite nanosheets component of the above example was used after drying at 100 ° C. for at least 6 hours, and HDPE was used after drying at 60 ° C. The hollow particulates and HDPE were dry mixed at about 4,000 rpm for 15 minutes in a Henschel mixer (PR Tech. Korea), and the content of the hollow particulates was 5 wt% (Example 10) and 10 wt% ( Example 11), the composite material was prepared in a rod shape of 65 mm long, 15 mm wide and 3 mm thick at 250 ℃ using an injection molding machine (Babyplast, USA).

In Comparative Examples 9 to 11, the polymer matrix is made of high density polyethylene (HDPE), and the graphite nanosheet-based thermally conductive hollow particles are different. The comparative examples 9 are 0 wt%, the comparative examples 10 are 5 wt%, Comparative Example 11 is 10 wt%.

Experimental example. Thermal Conductivity Measurements for Examples 1-11 and Comparative Examples 1-8

Thermal conductivity was measured using a TC probe ™ (Perkin-Elmer, USA). As the duration time of each sample, the deviation time obtained by the blotter method was applied.

Specimen measurement and calibration were performed at 30 ° C, and the effusivity of the polymer matrix applied during the calibration was measured using a TC probe. In order to minimize the thermal contact resistance between the probe and the specimen, thermal grease (YG-6111, Toshiba, Japan) was applied to the specimen and measured with a weight of about 700 g.

Table 2 shows the thermal conductivity of the case where the epoxy resin according to Examples 1 to 8 were mixed in the form of hollow particles.

division Hollow Heat Conductor
particle Content of thermal conductor
(wt%) Thermal conductivity
(W / mK) Example 1 Graphite
Nano sheet 0 0.33 Example 2 One 0.74 Example 3 5 1.55 Example 4 10 2.26 Example 5 aluminum
Nitride 0 0.33 Example 6 5 1.01 Example 7 Boron
Nitride 0 0.33 Example 8 5 1.15

In Table 3 below, the thermal conductivity of the epoxy resin according to Comparative Examples 1 to 8 was simply mixed with the heat conductor filler.

division Thermal conductor particles Content of thermal conductor
(wt%) Thermal conductivity
(W / mK) Comparative Example 1 Graphite
Nano sheet 0 0.33 Comparative Example 2 One 0.33 Comparative Example 3 5 0.49 Comparative Example 4 10 0.79 Comparative Example 5 aluminum
Nitride 0 0.33 Comparative Example 6 5 0.38 Comparative Example 7 Boron
Nikride 0 0.33 Comparative Example 8 5 0.40

As shown in [Table 2], when the hollow particle body was prepared with graphite nanosheets and mixed in the epoxy resin, the thermal conductivity increased as the hollow particle body filling ratio increased. However, as shown in [Table 3], when the graphite nanosheets were simply mixed, the increase in the thermal conductivity was very small. This tendency was similarly expressed when the type of the thermal conductor was changed to AlN and BN. It can be seen that changing the dispersion of the filler is very significant for improving the thermal conductivity.

In Table 4 below, changes in thermal conductivity when the graphite nanosheets hollow particles are mixed according to the polymer matrix resin are shown.

division Hollow Heat Conductor
particle Polymer Matrix Content of thermal conductor
(wt%) Thermal conductivity
(W / mK) Example 1 Graphite
Nano sheet Epoxy
Suzy 0 0.33 Example 2 One 0.74 Example 3 5 1.55 Example 4 10 2.26 Comparative Example 9 High density
Polyethylene 0 0.25 Comparative Example 10 5 1.31 Comparative Example 11 10 1.98

As shown in Table 4, the results for specimens in which the polymer matrix resin is a liquid epoxy and a solid HDPE, respectively, show that the thermal conductivity is affected by the initial state of the matrix resin. This can be seen that the dispersion of the hollow particle body may vary depending on the viscosity when mixed with the polymer resin, because it affects the formation of a heat transfer path that can conduct heat, which affects the thermal conductivity. However, even when the solid polymer resin is applied, the heat transfer filler exhibits significantly higher thermal conductivity than the case where the heat transfer filler is simply dispersed in the polymer matrix. It can be seen that the effective early construction of the heat transfer path can be realized by controlling the high heat conductivity at low heat carrier content conditions.

Claims (12)

Thermally conductive hollow particle bodies; And a thermally conductive composite comprising a polymer resin,
The thermally conductive hollow particle body is made of any one selected from carbon nanotubes, graphene, graphite nanosheets, aluminum nitride, boron nitride and aluminum oxide,
The carbon nanotubes, graphene and graphite nanosheets are each independently introduced with functional groups of a carboxyl group and a hydroxyl group, and the aluminum nitride, boron nitride and aluminum oxide are each independently treated with a titanate binder. It is,
The polymer resin is any one selected from silicone resin, epoxy resin, phenol resin and polyethylene resin,
The thermally conductive composite material is characterized in that the thermally conductive hollow particles are dispersed in the polymer resin while maintaining the hollow form. The method of claim 1,
The thermally conductive hollow particles are dispersed in the polymer resin in 1-20% by weight based on the total weight of the thermally conductive composite material. The method of claim 1,
The polymer resin is a thermally conductive composite, characterized in that the bisphenol-based epoxy resin or high density polyethylene resin. (a) pretreating the thermally conductive particles to produce thermally conductive particles with modified surfaces;
(b) preparing a polymer-thermally conductive composite particle coated with the thermally conductive particles on a surface of a polymer microparticle;
(c) heat-treating the polymer-thermally conductive composite particles to remove the polymer to prepare a thermally conductive hollow particle body; And
(d) dispersing the thermally conductive hollow particles in a polymer resin;
The thermally conductive particles are any one selected from carbon nanotubes, graphene and graphite nanosheets; Or any one selected from aluminum nitride, boron nitride and aluminum oxide;
The polymer fine particles are any one selected from polystyrene, polymethacrylate and polyacrylate,
The polymer resin is a method of producing a thermally conductive composite, characterized in that any one selected from silicone resin, epoxy resin, phenol resin and polyethylene resin. The method of claim 4, wherein
The polymer microparticles are prepared by dispersion polymerization using an aromatic vinyl compound or an unsaturated carboxylic ester compound as a monomer,
The aromatic vinyl compound is styrene, α-methylstyrene, α-chlorostyrene, p-tert-butylstyrene, p-methylstyrene, p-chlorostyrene, o-chlorostyrene, 2,5-dichlorostyrene, 3,4- Any one selected from dichlorostyrene, dimethyl styrene and divinylbenzene,
The unsaturated carboxylic ester compound may be any one selected from methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate and butyl methacrylate. Method for producing a thermally conductive composite characterized in. The method of claim 5, wherein
The diameter of the polymer fine particles is a method of producing a thermally conductive composite, characterized in that 0.1-10 ㎛. The method of claim 4, wherein
The modified thermally conductive particles of step (a) is a carbon nanotube, graphene or graphite nanosheets in which functional groups of a carboxyl group and a hydroxyl group are introduced to the surface by treating hydrazine and ammonia to produce a thermally conductive composite. Way. The method of claim 7, wherein
And controlling the ionic concentration on the surface of the carbon nanotube, graphene or graphite nanosheet by adjusting the mass ratio of hydrazine and ammonia, and the mass ratio of hydrazine and ammonia is 1: 1-20. The method of claim 4, wherein
Wherein the modified thermally conductive particles of step (a) are aluminum nitride, boron nitride or aluminum oxide surface treated with a titanate binder. The method of claim 4, wherein
In the step (b), the surface-modified thermally conductive particles and the polymer microparticles are dispersed in a mixed solvent of isopropyl alcohol and deionized water, followed by stirring to prepare the polymer-thermally conductive composite particles coated with the thermally conductive particles. Method for producing a thermally conductive composite characterized in. The method of claim 4, wherein
Step (c) is a method of producing a thermally conductive composite, characterized in that to remove the polymer by heat-treating the polymer-thermal conductive composite particles in a nitrogen atmosphere of 250-400 ℃. The method of claim 4, wherein
The step (d) is a method for producing a thermally conductive composite, characterized in that the thermally conductive hollow particles are dispersed in the polymer resin in 1-20% by weight based on the total weight of the thermally conductive composite.

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