KR20220012487A - Organic-inorganic complexed filler and heat-dissipating composition comprising the same - Google Patents

Abstract

The present invention relates to an organic-inorganic composite filler and a heat dissipation composition comprising the same. The organic-inorganic composite filler attaches a plate-shaped thermally conductive inorganic particle to a crosslinked polymer particle having specific physical properties through a coating layer to have a very low density and a very high filling rate compared to a conventional heat dissipation additive, and can further improve thermal conductivity, which has reached the limit of the same in the past.

Description

Organic-inorganic composite filler and heat dissipation composition comprising the same

The present invention relates to an organic-inorganic composite filler and a heat dissipation composition comprising the same.

Recently, heat dissipation products with excellent heat dissipation characteristics are required not only in electronic devices but also in various other fields. In addition, semiconductor devices, etc., in which high-speed integration is achieved, are gradually reduced in size, weight, and thickness, while the amount of heat generated is increasing. Therefore, higher performance heat dissipation products are required.

Currently, heat dissipation products are largely divided into electrically conductive heat dissipation products and non-conductive heat dissipation products, and metal, ceramic, heat dissipation silicon, etc. are mainly used. In the case of non-conductive heat dissipation silicone, an inorganic filler is added to the resin and used. The mainly used inorganic materials are silicon dioxide (SiO ₂ ), alumina (Al ₂ O ₃ ), non-conductive and excellent in thermal conductivity, Inorganic fillers such as boron nitride (BN) and aluminum nitride (AlN) are widely used, and are applied depending on the purpose and characteristics. However, since each inorganic filler has a large difference in thermal conductivity and a large price difference, there are various restrictions in use.

Silicon dioxide has a disadvantage in that it is inexpensive but has relatively poor thermal conductivity, and boron nitride and aluminum nitride have a disadvantage in that they are very expensive while having high thermal conductivity. Therefore, in recent years, alumina fillers having relatively higher thermal conductivity than silicon dioxide have been widely employed. However, since alumina has a high density, the mass of a product containing such a filler increases, and the hardness is high, so equipment wear inevitably occurs during the process.

Moreover, it is good to form a spherical shape in order to maximize the thermal conductivity by increasing the filling rate. Alumina and silicon dioxide can be manufactured in a spherical shape, but boron nitride or aluminum nitride is difficult to sphericalize, so the filling rate is poor. Korean Patent Laid-Open No. 10-2013-0051456 also mixed spherical alumina and hexagonal boron nitride to increase thermal conductivity.

In addition, when the filling rate is reduced in this way, the effect on thermal conductivity is lowered compared to the price, so it is difficult to obtain a large effect in thermal conductivity, and there is a problem that an additional process is impossible because the viscosity is rapidly increased. Nevertheless, in recent years, due to the diversification and miniaturization of electronic devices, the demand for small heat dissipation products having high heat dissipation characteristics is increasing.

The present invention provides an organic-inorganic composite filler.

The present invention also provides a heat dissipation composition comprising the organic-inorganic composite filler.

Hereinafter, an organic-inorganic composite filler and a heat dissipation composition including the same according to specific embodiments of the present invention will be described.

According to one embodiment of the invention, the cross-linked polymer particles having a compressive strength of 0.01 to 2.0 kgf / mm ² ; a coating layer positioned on the surface of the crosslinked polymer particle and including a polymer binder; and an organic-inorganic composite filler comprising plate-shaped thermally conductive inorganic particles attached to the crosslinked polymer particles via the coating layer.

The shape of the heat-dissipating additive added to the heat-dissipating product is advantageous to a spherical shape that can exhibit heat dissipation performance in the z-direction as well as the xy-direction rather than the plate-like shape. However, the thermal conductivity of the spherical heat-dissipating additive has already reached its limit, and it is very difficult to sphericalize the plate-shaped heat-dissipating additive.

Therefore, the inventors of the present invention, when attaching plate-shaped thermally conductive inorganic particles to crosslinked polymer particles having specific physical properties through a coating layer, by composing the core particles with crosslinked polymer particles to suppress device wear and the like, and attach thermally conductive particles without crushing Through experiments, it was confirmed through experiments that it is possible to further increase the filling rate by lowering the density of the heat-dissipating additive, and to further improve the thermal conductivity that reached the limit previously, and completed the present invention.

Hereinafter, the organic-inorganic composite particles according to an embodiment will be described in detail.

The cross-linked polymer particles constituting the core of the organic-inorganic composite particles include a cross-linked structure and maintain excellent durability without fear of thermal decomposition or gas emission even when exposed to high temperatures for a long time to provide an organic-inorganic composite filler that continuously exhibits heat dissipation properties can do.

The crosslinked polymer particles may have a compressive strength of 0.01 to 2.0 kgf/mm ² , 0.10 to 1.95 kgf/mm ² , 0.20 to 1.90 kgf/mm ² , or 0.30 to 1.87 kgf/mm ² .

As crosslinked polymer particles, those having a compressive strength of less than 0.01 kgf/mm ² are difficult to manufacture, and non-crosslinked polymer particles having a compressive strength of less than 0.01 kgf/mm ² may be thermally decomposed or release gas at high temperatures as described above, and heat dissipation characteristics It is difficult to maintain the original sphericity during expression, so it is difficult to use it as a heat dissipation additive.

The cross-linked polymer particles do not wear the device during manufacturing of the organic-inorganic composite filler due to the low compressive strength in the above range, and may not damage heat-dissipating products such as electronic devices to which the organic-inorganic composite filler is added. In addition, due to the low compressive strength of the crosslinked polymer particles, the plate-shaped thermally conductive inorganic particles are not crushed and adhere well, so that the thermally conductive core particles are coated with the plate-shaped thermally conductive inorganic particles.

It is advantageous that the crosslinked polymer particles have a glass transition temperature of 120° C. or higher or 150° C. or higher, or have no glass transition temperature and thus have excellent thermal stability.

The moisture content of the crosslinked polymer particles may be as low as 0 to 1 wt%. If the moisture content exceeds the above range, the internal moisture of the core is released by the heat generated during the manufacturing process of the organic/inorganic composite filler that attaches the thermally conductive inorganic particles to the core or the heat generated after the organic/inorganic composite filler is applied to a heat-dissipating product. As a result, the thermally conductive inorganic particles attached to the core may be desorbed, which may cause damage, such as failing to realize desired heat dissipation performance, or deforming the shape of electronic products to which organic/inorganic composite fillers are applied. Therefore, by using the crosslinked polymer particles having a moisture content in the above range, the coating layer and the thermally conductive inorganic particles through the coating layer can be well attached to the crosslinked polymer particles, and the organic-inorganic composite filler is added. It may not damage heat dissipation products such as devices.

The crosslinked polymer particles may have a sphericity of 0.9 to 1, 0.93 to 1, or 0.94 to 1. The sphericity means that it is closer to a true sphere as it comes into contact with 1, and since the crosslinked polymer particles have the above-mentioned sphericity, even if plate-shaped thermally conductive inorganic particles are used, it is possible to provide an organic-inorganic composite filler that shows heat dissipation properties in all directions. can

The average particle size (D50) of the crosslinked crosslinked molecule particles may be 5 to 50 μm, 10 to 45 μm, or 20 to 40 μm. Within this range, the plate-shaped thermally conductive inorganic particles may be uniformly coated on the crosslinked polymer particles without agglomeration, and the filling rate of the organic-inorganic composite filler may be increased.

As the cross-linked polymer particles, as long as they satisfy the above-described characteristics, various cross-linked polymer particles known in the art to which the present invention pertains may be used.

For example, the crosslinked polymer particles may be crosslinked particles of one or more polymers selected from the group consisting of acrylic polymers, styrene polymers, and urethane polymers, or crosslinked particles of an acrylate-styrene copolymer.

A coating layer including a polymer binder is positioned on the surface of the crosslinked polymer particle. The thermally conductive inorganic particles may be attached to the surface of the crosslinked polymer particles through the coating layer.

The glass transition temperature (Tg) of the polymer binder constituting the coating layer may be 80 to 150 °C, 90 to 140 °C, or 100 to 130 °C. Within this range, when the polymer binder is coated on the cross-linked polymer particles, aggregation of the cross-linked polymer particles can be suppressed, and the polymer binder can be smoothly coated on the cross-linked polymer particles.

The polymer binder is not particularly limited as long as it is a material capable of increasing the adhesion between the crosslinked polymer particles and the thermally conductive inorganic particles, but for example, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyvinyl butyral ( PVB) and may be at least one selected from the group consisting of acrylonitrile-butadiene-styrene (ABS) resin.

The thermally conductive inorganic particles may be attached to the crosslinked polymer particles via the coating layer.

The organic-inorganic composite filler may be provided in a spherical form by using plate-shaped thermally conductive inorganic particles having a low filling rate because they are difficult to be spherical as thermally conductive inorganic particles. More specifically, the organic-inorganic composite filler includes plate-shaped thermally conductive inorganic particles as it is provided in a form in which the plate-shaped thermally conductive inorganic particles are attached to the spherical crosslinked polymer particles via the coating layer, but provided in a spherical shape with a high filling rate And it can exhibit excellent thermal conductivity that exceeds the thermal conductivity of the existing spherical heat dissipation additive.

The plate-shaped thermally conductive inorganic particles may have an aspect ratio that is a value obtained by dividing an average diameter by a thickness of 3 to 1000, 4 to 500, or 5 to 250. The aspect ratio is a value obtained by dividing the average value of diameters measured in various directions of the broad surface (xy plane) of the plate-shaped thermally conductive inorganic particles by the thickness (z-axis) of the plate-shaped thermally conductive inorganic particles. Since the thermally conductive inorganic particles have an aspect ratio within the above-mentioned range, they can be prevented from being crushed when attached to the crosslinked polymer particles. The particles can be more firmly attached.

The thermally conductive inorganic particles may have a Vichers hardness of 0.01 to 1 GPa. Within this range, it can be attached to the crosslinked polymer particles without crushing.

The thermally conductive inorganic particles include boron nitride (BN), aluminum nitride (AlN), silicon carbide (SiC), magnesium oxide (MgO), zinc oxide (ZnO) and aluminum hydroxide (Al(OH) ₃ ). One or more selected types may be used. Among them, boron nitride (BN), aluminum nitride (AlN), or a mixture thereof may be used as the thermally conductive inorganic particles. For example, boron nitride may be used as the thermally conductive inorganic particles.

The organic-inorganic composite filler may be prepared by stirring the cross-linked polymer particles and a polymer binder to form a coating layer on the surface of the cross-linked polymer particles, and then adding and stirring the thermally conductive inorganic particles. Accordingly, the organic-inorganic composite filler may include a separate coating layer including thermally conductive inorganic particles on the coating layer including the polymer binder. In the present specification, a coating layer including a polymer binder may be referred to as a first coating layer, and a coating layer including thermally conductive inorganic particles may be referred to as a second coating layer.

The thickness of the first and second coating layers is adjusted to about 0.1 to 2 μm, so that the thermally conductive inorganic particles are sufficiently attached to the surface of the crosslinked polymer particles without agglomeration, thereby further improving thermal conductivity. If the thickness exceeds 2 μm, the number of non-attached thermally conductive inorganic particles increases, which may cause a problem of increasing the residue and increasing the viscosity of the heat dissipating composition including the same.

The thicknesses of the first and second coating layers are theoretical coating thicknesses, and can be obtained by forming the first and second coating layers on the crosslinked polymer particles and converting the increased volume into the added diameter from the average particle size of the crosslinked polymer particles. Specifically, the theoretical coating thickness is an increase calculated by substituting the volume V of the injected plate-shaped thermally conductive inorganic particles compared to the crosslinked polymer particles into Equation 3 derived through Equation 2, assuming that the volume of the crosslinked polymer having a radius of r is 1. thickness can be specified.

[Equation 2]

1 : (1 + V) = 3/4 * ð * r ³ : 3/4 * ð * (r + x) ³

[Equation 3]

x = r * (1 + V) ^1/3 - r

Strictly speaking, V substituted in Equation 3 should be the volume value of the plate-shaped thermally conductive inorganic particles and the polymer binder, but the volume of the polymer binder is very small compared to the thermally conductive inorganic particles, so the theoretical coating thickness difference depending on whether the volume of the polymer binder is included is very small, so the theoretical coating thickness of the present specification was defined as a value obtained by substituting the volume of the plate-shaped thermally conductive inorganic particles.

In the organic-inorganic composite filler, the crosslinked polymer particles constituting the core may have an average particle size of 1.5 times or more, 2 times or more, or 3 times or more of the average diameter of the thermally conductive inorganic particles. Within this range, it is possible to prevent the thermally conductive inorganic particles from being crushed when they are attached to the crosslinked polymer particles. can be attached. The upper limit of the above range is not particularly limited, and as a non-limiting example, the crosslinked polymer particles may have an average particle size of 10 times or less and 8 times or less of the average diameter of the thermally conductive inorganic particles.

The organic-inorganic composite filler may contain 5 to 40 parts by weight or 7 to 38 parts by weight of the polymer binder based on 100 parts by weight of the crosslinked polymer particles, and 10 to 80 parts by weight or 15 to 77 parts by weight of the thermally conductive inorganic particles. have. Within this range, the thermally conductive inorganic particles can be firmly attached to the crosslinked polymer particles, and aggregation or residues of the thermally conductive inorganic particles can be minimized.

On the other hand, according to another embodiment of the invention, there is provided a heat dissipation composition comprising the organic-inorganic composite filler.

The heat-dissipating composition may include the above-described organic-inorganic composite filler to exhibit low density, high filling rate, and high thermal conductivity.

The heat dissipation composition may include a base resin capable of serving as a base material for the organic-inorganic complex filler, or a monomer or oligomer capable of providing the same. As the base resin or a monomer or oligomer capable of providing the same, various ones known in the art to which the present invention pertains may be used.

For example, as the base resin or a monomer or oligomer capable of providing the same, a material having excellent heat dissipation properties and shock absorption properties may be used. Specific examples of such materials include thermosetting silicone rubber compounds, one-component thermosetting silicone binders, two-component thermosetting silicone binders, acrylic resins, epoxy resins, urethane resins, or mixtures thereof, or monomers or oligomers that can provide them. have. The materials exemplified above do not require a separate adhesive layer or the like for fixing during operation due to their excellent adhesive strength, thereby reducing the production cost of the final product.

The heat dissipation composition may include 50 to 1000 parts by weight, 70 to 1000 parts by weight, or 100 to 1000 parts by weight of the organic-inorganic composite filler based on 100 parts by weight of the base resin or the total weight of monomers or oligomers capable of providing the same . As the organic-inorganic composite filler is included, compatibility with the base resin or a monomer or oligomer capable of providing it can be improved, and the volume content (volume %) of the organic-inorganic composite filler for implementing the same thermal conductivity can be lowered. Therefore, it is possible to significantly increase the filling amount of the filler. On the other hand, excellent thermal conductivity is realized by controlling the content of the organic-inorganic composite filler to the above-mentioned range, and the viscosity of the heat-dissipating composition is controlled to an appropriate level to release bubbles in the heat-dissipating composition through smooth stirring, thereby exhibiting excellent thermal conductivity. have.

Meanwhile, the heat dissipating composition may further include one or more second thermally conductive inorganic particles selected from the group consisting of alumina, boron nitride, aluminum nitride, silicon carbide, magnesium oxide, zinc oxide, and aluminum hydroxide. These second thermally conductive inorganic particles are to be distinguished from thermally conductive inorganic particles included in the organic-inorganic composite filler, and may be dispersed in the base resin or a monomer or oligomer capable of providing the same, and the thermal conductivity properties of the heat dissipation material and / Alternatively, it may be added as an additional filler to improve electromagnetic wave absorption performance.

Accordingly, the heat dissipation composition may include the organic-inorganic composite filler and the second thermally conductive inorganic particles in a volume ratio of 1:0.4 to 3. If the volume ratio of the organic-inorganic composite filler and the second thermally conductive inorganic particles is less than 1:0.4, the effect of adding the filler unit may not appear, and if it exceeds 1:3, the heat dissipation additive is not uniformly blended into the composition, Increasing the viscosity of the composition may impair fairness.

The heat dissipating composition may also contain antioxidants, optical brighteners, light stabilizers, lubricants, pigments, dyes, mold release agents, crosslinking agents, friction and abrasive agents, reactive compounds, flame retardants, metal deactivators, antistatic agents, coupling agents, etc., as needed. may additionally include.

Meanwhile, the heat dissipation composition may provide a heat dissipation material according to a method known in the art to which the present invention pertains. The heat dissipation material is a substrate; and an organic-inorganic composite filler dispersed in the substrate.

The base material is formed in the form of a sheet from the base resin included in the heat dissipation composition or a monomer or oligomer capable of providing the same, and organic-inorganic composite filler particles may be dispersed and included in the base material.

As described above, the heat dissipation material including the organic-inorganic composite filler dispersed in the substrate is filled with a low-density organic-inorganic composite filler at a high ratio, so that low density and high thermal conductivity can be realized.

The heat dissipation material may have a thickness of 0.1 to 10.0 mm. By controlling the thickness of the heat dissipation material within the above-described range, it is possible to realize light and excellent heat conduction properties.

On the other hand, the heat dissipation material may be a single-layer sheet, may be a composite sheet to which two or more of the same sheet is attached, or a sheet having different physical properties may be additionally attached to one or more surfaces of the single-layer sheet.

The organic-inorganic composite filler according to an embodiment of the present invention has a very low density and a very high filling rate compared to conventional heat dissipation additives by attaching plate-shaped thermally conductive inorganic particles to crosslinked polymer particles having specific physical properties through a coating layer. It is possible to further improve the thermal conductivity that has reached its limit.

Hereinafter, the action and effect of the invention will be described in more detail through specific examples of the invention. However, this is presented as an example of the invention and the scope of the invention is not limited in any way by this.

Preparation Example 1: Preparation of organic-inorganic composite filler

10 g of core particles (SEKISUI ARX 30) having a compressive strength of 0.50 kgf/mm ² , an average particle size of 30 μm, and a sphericity of 0.95 and polyvinylpyrrolidone (PVP, weight average molecular weight: 10,000 g/mol, Sigma -Aldrich, glass transition temperature 130 ℃) was put into a planetary mixer (planetary mixer) 3.2 g, and stirred at a speed of 1200 rpm/600 rpm (rotation/revolution) and room temperature for 5 minutes. After that, 6.4 g of hexagonal boron nitride having an average diameter of 10 μm and a thickness of 0.5 μm is added, and the presence or absence of stirring at a speed of 1200 rpm/600 rpm (rotation/revolution) and room temperature for 5 minutes A base composite filler was prepared.

Preparation Examples 2 to 4: Preparation of organic-inorganic composite filler

As shown in Tables 1 and 2 below, an organic-inorganic composite filler was prepared in the same manner as in Example 1, except that the type of core particles, the content of the polymer binder, and the content of the thermally conductive inorganic particles were changed.

Preparation Example 1 Preparation 2 Preparation 3 Preparation 4 core particle Kinds Cross-linked PA ¹⁾ Cross-linked PA ²⁾ Cross-linked PA ³⁾ alumina Compressive strength (kgf/mm ² ) ⁵⁾ 0.50 1.85 2.5 over 10 Glass transition temperature (℃) ⁶⁾ NA ⁴⁾ N.A. 130 ℃ N.A. Moisture content (wt%) ⁷⁾ 1 or less 1 or less 1 or less 1 or less Average particle size (D50, ㎛) ⁸⁾ 30 30 40 40 sphericity ⁹⁾ 0.95 0.95 0.95 0.93 content (g) 10 10 10 10 polymer binder PVP content (g) 3.2 3.2 3.2 0.65 thermally conductive weapon
particle Boron nitride content (g) 6.4 6.4 6.4 1.3 Average diameter/thickness (μm) ¹⁰⁾ 10 / 0.5 10 / 0.5 10 / 0.5 10 / 0.5 Theoretical thickness (㎛) ¹¹⁾ 1.5 1.5 2.0 1.5 Aspect Ratio ¹²⁾ 20 20 20 20 Size ratio of crosslinked polymer particles and thermally conductive inorganic particles ¹³⁾ 3 3 4 4

1) Polyacrylate crosslinked particles (average particle size (D50): 30 μm, SEKISUI ARX 30)2) Polyacrylate crosslinked particles (average particle size (D50): 30 μm, SEKISUI BMX 30)

3) Polyacrylate crosslinked particles (average particle size (D50): 40 ㎛, SEKISUI MBX 40)

4) N.A: not measurable

5) Compressive strength: This is a value measured at a speed of 1 mm/s in compression mode using a texture analyzer.

6) Glass transition temperature: The glass transition temperature of the sample was measured using DSC Q100 (TA Instrument). Before measuring the glass transition temperature, the sample was pretreated at 100° C. for 30 minutes to remove moisture.

7) Moisture content: The moisture content was calculated from the weight before and after storage at 100 °C for 4 hours.

8) Average particle size (D50): The particle size distribution based on the volume of the sample is obtained using the laser diffraction method using the Marvern Mastersizer 3000 The diameter (D50) was obtained.

9) Sphericity: Sphericity is the average value of circularity measured using Marvern's sphericity analysis equipment (FPIA-3000). Specifically, the circularity is a value obtained by measuring a projected area (A) and a peripheral length (P) of a sample from a scanning electron microscope photograph, and substituting them into Equation 1 below. The sphericity and circularity are expressed as values from 0 to 1, and the closer to 1, the closer to a true sphere.

[Equation 1]

Circularity = 4πA/P ²

10) Average diameter and thickness: The average diameter is the average value of the diameters measured in various directions of the broad side (xy plane) of the plate-shaped thermally conductive inorganic particles, and the thickness is the thickness (z-axis) of the plate-shaped thermally conductive inorganic particles 10 It is the average value of repeated measurements of multiple sites more than once. The diameter and thickness were measured through SEM.

11) Theoretical coating thickness: The thickness of the first and second coating layers formed on the crosslinked polymer particles. The theoretical coating thickness is the increased thickness calculated by substituting the volume V of the plate-shaped thermally conductive inorganic particles injected compared to the crosslinked polymer particles into Equation 3 derived from Equation 2, assuming that the volume of the crosslinked polymer with radius r is 1.

[Equation 2]

1 : (1 + V) = 3/4 * ð * r ³ : 3/4 * ð * (r + x) ³

[Equation 3]

x = r * (1 + V) ^1/3 - r

12) Aspect Ratio: It is a value obtained by dividing the average diameter (㎛) of the thermally conductive inorganic particles by the thickness (㎛).

13) Size ratio of crosslinked polymer particles to thermally conductive inorganic particles: This is the value obtained by dividing the average particle size (D50, μm) of the crosslinked polymer particles by the average diameter (μm) of the thermally conductive inorganic particles.

Test Example 1: Evaluation of manufacturing problems and physical properties of organic-inorganic composite fillers

The organic-inorganic composite filler was prepared by manufacturing the organic-inorganic composite filler according to Preparation Examples 1 to 4, and the content of the residue including the polymer binder and thermally conductive inorganic particles was checked, and the organic-inorganic composite filler was observed by observing whether the thermally conductive inorganic particles were well attached to the core particles. To evaluate the problems during the manufacture, and measure the density of the organic-inorganic composite filler.

i) content of residue

After the organic-inorganic composite filler is prepared, the content of the polymer binder and thermally conductive inorganic particles remaining uncoated is measured, and if less than 5% by weight remains with respect to the total weight added, it is written as 'minor amount', and the remaining amount is 5% by weight or more. In this case, 'a lot' was entered.

ii) Adhesion evaluation

In order to evaluate whether the thermally conductive inorganic particles were well attached to the crosslinked polymer particles, the appearance of the prepared organic-inorganic composite filler was observed with a scanning electron microscope. As a result of observation, if the thermally conductive inorganic particles were evenly attached without agglomerated parts, it was indicated by 'O', and if the thermally conductive inorganic particles were not attached, it was indicated by 'X'.

iii) Density of organic-inorganic composite filler

The density (g/cm ² ) of the organic-inorganic composite filler was measured using a hydrometer (GeoPyc 1360, Micromeritics).

residue Attach Density (g/cm ³ ) Preparation Example 1 a very small amount O 1.55 Preparation 2 a very small amount O 1.55 Preparation 3 a very small amount O 1.59 Preparation 4 much O 3.23

Referring to Table 2, in the case of Preparation Examples 1 to 3, it was confirmed that the thermally conductive inorganic particles were well attached to the core particles without a residue.

However, in the case of Preparation Example 4, although a very small amount of thermally conductive inorganic particles were attached to the core particles compared to Preparation Examples 1 to 3, a large amount of residue was generated, and the density was high, so when such an organic-inorganic composite filler was used, heat dissipation material It is expected that it may be difficult to use according to the trend of lightening electronic products by increasing the weight of the product.

Examples 1 to 4 and Comparative Examples 1 to 4: Preparation of a heat-dissipating composition

A heat dissipation composition was prepared by adding the organic-inorganic composite filler prepared above to the two-component urethane-based adhesive composition.

Specifically, the organic-inorganic composite filler prepared in Preparation Examples 1 to 4 was dispersed in 50 g of caprolactone-based polyol and 50 g of polyisocyanate (HDI, Hexamethylene diisocyanate) having the structure shown in Chemical Formula 1 below as described in Table 3 below for heat dissipation. A composition was prepared.

[Formula 1]

The polyol represented by Formula 1 includes polyols in which n is 2 to 3 and m is 1 to 3 in Formula 1 above.

Types of organic-inorganic composite fillers Organic-inorganic composite filler input amount
(Weight, unit: phr ^* ) Organic-inorganic composite filler input amount
(volume, unit: vol%) Example 1 Preparation Example 1 100 40 Example 2 Preparation 2 100 40 Comparative Example 1 Preparation 3 100 40 Comparative Example 2 Preparation 4 100 25 Example 3 Preparation Example 1 250 63 Example 4 Preparation 2 250 63 Comparative Example 3 Preparation 3 250 63 Comparative Example 4 Preparation 4 500 63

* phr: an abbreviation of parts per hundred resin, meaning parts by weight based on 100 parts by weight of the polymer.

As shown in Table 3, in Examples 1 and 2, Comparative Examples 1 and 2, each 100 g of the organic/inorganic composite filler prepared in Preparation Examples 1 to 4 was added to prepare a heat dissipation composition, and Examples 3 and 4 , In Comparative Examples 3 and 4, the organic-inorganic composite filler prepared in Preparation Examples 1 to 4 was added up to the maximum volume (63 vol%) to be added, respectively, to prepare a heat-dissipating composition.

Test Example 2: Evaluation of the physical properties of the heat dissipation composition

The physical properties of the heat-dissipating compositions prepared according to Examples and Comparative Examples were evaluated, and the results are shown in Table 4.

i) Density of heat dissipation material

The density of the resin layer formed from the heat-dissipating composition was measured using a hydrometer (GeoPyc 1360, Micromeritics).

ii) thermal conductivity

The thermal conductivity of the heat dissipating composition was measured according to ASTM D 5470 standard. After placing a resin layer formed using a heat-dissipating composition between two copper bars according to the standard of ASTM D 5470, one of the two copper bars is in contact with a heater, and the other is a cooler. After contact with the , the heater was maintained at a constant temperature, and the capacity of the cooler was adjusted to create a thermal equilibrium state (a state showing a temperature change of about 0.1 ° C. or less in 5 minutes). The temperature of each copper rod was measured in a thermal equilibrium state, and thermal conductivity (K, unit: W/mK) was evaluated according to Equation 2 below. When evaluating the thermal conductivity, the pressure applied to the resin layer was adjusted to be about 11 kg/25 cm ² , and when the thickness of the resin layer was changed during the measurement process, the thermal conductivity was calculated based on the final thickness.

[Equation 4]

K = (Q X dx)/(A X dT)

In Equation 4, K is the thermal conductivity (W / mK), Q is the heat moved per unit time (unit: W), dx is the thickness of the resin layer (unit: m), A is the cross-sectional area of the resin layer (unit: m) : m ² ), and dT is the temperature difference (unit: K) of the copper rod.

iii) durability test

After measuring the thermal conductivity, the resin layer is stored at 100° C. for 100 hours, and then the thermal conductivity is measured again in the above-mentioned manner. If the change is within 10%, it is described as ‘maintained’, and if it exceeds 10%, it is described as ‘reduced’. did

Density of heat dissipation material (g/cm ³ ) Thermal Conductivity (W/mK) durability test Example 1 1.29 0.82 maintain Example 2 1.29 0.76 maintain Comparative Example 1 1.29 0.66 maintain Comparative Example 2 1.64 0.74 maintain Example 3 1.41 3.02 maintain Example 4 1.41 2.82 maintain Comparative Example 3 1.39 2.43 maintain Comparative Example 4 2.61 2.46 maintain

According to an embodiment of the present invention, when a crosslinked polymer particle having a specific compressive strength is used as the core particle, even when a force is applied to attach the thermally conductive inorganic particle to the core particle, a large amount of plate-shaped thermally conductive inorganic material is generated by the restoring force of the core particle. The particles were able to adhere well to the core particles without being damaged.

On the other hand, core particles such as alumina have high compressive strength, so when a force is applied to attach the thermally conductive inorganic particles, the plate-shaped thermally conductive inorganic particles are easily broken. It was confirmed through the experiment that the manufacturing yield of the organic-inorganic composite filler was very low.

In addition, referring to Table 4, when crosslinked polymer particles having a specific compressive strength are used as in Examples 1 to 4, even when a crosslinked polymer having no thermal conductivity is used, compared to the case of using alumina core particles having thermal conductivity. It is confirmed that it exhibits high thermal conductivity. In addition, when cross-linked polymer particles having a specific compressive strength are employed as core particles according to an embodiment of the present invention, it is expected that the density of the organic/inorganic composite filler will be lowered to provide excellent heat dissipation performance while providing lightweight electronic products.

Finally, comparing Examples 1 to 4 with Comparative Examples 1 and 3, even if the core particles are cross-linked polymer particles, cross-linked polymer particles that do not satisfy the specific compressive strength according to an embodiment of the invention are employed. It is confirmed that it does not exhibit low density and high thermal conductivity.

Accordingly, the organic-inorganic composite filler according to an embodiment of the present invention employs cross-linked polymer particles that do not exhibit thermal conductivity to achieve a low density while exhibiting higher thermal conductivity than thermally conductive alumina core particles, thereby overcoming the existing heat dissipation performance limitations and It is expected to be able to provide lighter electronic products.

Claims (16)

Crosslinked polymer particles having a compressive strength of 0.01 to 2.0 kgf/mm ² ; a coating layer positioned on the surface of the crosslinked polymer particle and including a polymer binder; and plate-shaped thermally conductive inorganic particles attached to the crosslinked polymer particles via the coating layer.
The organic-inorganic composite filler according to claim 1, wherein the crosslinked polymer particles have a glass transition temperature of 120° C. or higher or no glass transition temperature.
The organic-inorganic composite filler according to claim 1, wherein the crosslinked polymer particles have a moisture content of 0 to 1 wt%.
The organic-inorganic composite filler according to claim 1, wherein the crosslinked polymer particles have a sphericity of 0.9 to 1.
The organic-inorganic composite filler according to claim 1, wherein the crosslinked polymer particles have an average particle size of 5 to 50 µm.
The organic-inorganic composite filler according to claim 1, wherein the crosslinked polymer particles are crosslinked particles of one or more polymers selected from the group consisting of acrylic polymers, styrene polymers, and urethane polymers, or crosslinked particles of an acrylate-styrene copolymer.
According to claim 1, wherein the polymer binder has a glass transition temperature of 80 to 150 ℃, organic-inorganic composite filler.
According to claim 1, wherein the polymer binder comprises at least one selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl butyral and acrylonitrile-butadiene-styrene resin, organic-inorganic composite filler.
The organic-inorganic composite filler according to claim 1, wherein the thermally conductive inorganic particles have an aspect ratio that is a value obtained by dividing an average diameter by a thickness of 3 to 1000.
According to claim 1, wherein the organic-inorganic composite filler is cross-linked polymer particles; a first coating layer positioned on the surface of the crosslinked polymer particle and including a polymer binder; and a second coating layer comprising plate-shaped thermally conductive inorganic particles attached to the crosslinked polymer particles via the coating layer, wherein the thickness of the first and second coating layers is 0.1 to 2 μm.
According to claim 1, wherein the thermally conductive inorganic particles are boron nitride (BN), aluminum nitride (AlN), silicon carbide (SiC), magnesium oxide (MgO), zinc oxide (ZnO) and aluminum hydroxide (Al(OH) ₃ ), including at least one selected from the group consisting of, organic-inorganic composite filler.
The organic-inorganic composite filler according to claim 1, wherein the crosslinked polymer particles have an average particle size that is two or more times larger than an average diameter of the thermally conductive inorganic particles.
The organic-inorganic composite filler according to claim 1, comprising 5 to 40 parts by weight of the polymer binder and 10 to 80 parts by weight of the thermally conductive inorganic particles based on 100 parts by weight of the crosslinked polymer particles.
A heat dissipation composition comprising the organic-inorganic composite filler of claim 1.
The heat dissipating composition according to claim 14, wherein the heat dissipating composition further comprises a base resin or a monomer or oligomer capable of providing the same.
The heat dissipating composition according to claim 15, comprising 50 to 1000 parts by weight of the organic-inorganic composite filler based on 100 parts by weight of the total weight of the base resin or a monomer or oligomer capable of providing the same.