KR20200036180A - Method for nano coating an inorganic filler and thermal dissipation composite material and sheet using the inorganic filler prepared therefrom - Google Patents

Abstract

The present invention relates to an inorganic filler nano-coating method, to a heat dissipation composite material using an inorganic filler produced by the method, and to a sheet thereof. The inorganic filler nano-coating method comprises the steps of: diluting silane with a solvent; adding an inorganic filler to a silane solution diluted with the solvent, and agitating the same; crushing the inorganic filler added to the silane solution; adding a curing agent or a binder after the crushing step, and agitating the same; filtering the silane-coated inorganic filler produced in the agitating step; and curing the silane-coated inorganic filler.

Description

Inorganic filler nano coating method and heat dissipation composite material and sheet using inorganic filler manufactured by this method

The present invention relates to an inorganic filler nano-coating method, and more particularly, to a nano-coating method of an inorganic filler using a silane solution and an inorganic filler produced by the method, and to a heat-resistant composite material and sheet having excellent withstand voltage.

Recently, as the industry of high power LED (light emitting diode) lighting and LED television (TV) market has expanded and the demand for high integration and high performance electronic devices has increased, many malfunctions of electronic devices due to heat generated during device operation or charging and discharging have occurred. , Due to this, the problem of shortening the life of the electronic device is frequently occurring.

In addition, there is a growing need for power consumption, and a distributed generator is attracting attention, and the power supply by the distributed generator is required to optimize a heat control design of a power conditioner.

In addition, since electric vehicles, power modules, and power electronic devices require high power, materials with excellent withstand voltage characteristics are required, and at the same time, measures to dissipate heat to control heat generated are required.

In addition, as one of the methods to reduce the volume and weight in order to increase the efficiency of power supply, in some Japanese research results, the optimization of the design of the heat dissipation system using heat dissipation sheets is in progress.

In addition, in order to apply to the heat dissipation material, it is necessary to develop a heat dissipation pad having excellent withstand voltage characteristics through high content filling technology and dispersion technology of an insulating inorganic filler. It is reported that most of the existing heat dissipation composite materials use alumina inorganic fillers, and use square alumina and spherical alumina for 2 ~ 3W class products, and use spherical alumina and nitride-based inorganic fillers for 5W class products. In addition, most of the existing heat dissipation sheet, heat dissipation double sided tape, etc. are manufactured using alumina, BN, and the like.

However, in the conventional heat dissipation composite material, heat dissipation sheet, or heat dissipation double-sided tape, if the gap between the contact interfaces of the filler is filled with air with low heat conductivity, the thermal conductivity of the composite material is reduced and the withstand voltage characteristics required by power devices are reduced. There is.

In addition, in consideration of thermal conductivity, the heat-radiating sheet is manufactured by filling the inorganic filler in the existing heat dissipation composite material by type, size, and the like. However, depending on the characteristics of the resin and the type of the inorganic filler, the amount of filling is limited, and when pores are present in the inorganic filling, a problem arises in the withstand voltage characteristics.

As described above, the existing technology makes composite materials containing inorganic fillers such as silica, alumina, and zeolite having a high thermal conductivity and an average particle size of several tens of µm. However, it is necessary to increase the filler content in order to increase the thermal conductivity properties and to increase the filling density in order to improve the withstand voltage properties, but there is a difficulty in dispersing the inorganic filler, and thus there is a problem in reproducibility of the physical properties according to the dispersion rate. As such, a method for reducing the thermal conductivity of a composite material and satisfying the withstand voltage characteristics required in a power device manufactured from such a composite material is required in manufacturing a heat dissipation composite material, a heat dissipation sheet, or a heat dissipation pad using an inorganic filler. have.

Republic of Korea Registered Patent No. 10-1782231 (2017.09.20)

The present invention was derived to solve the problems of the prior art described above, and the object of the present invention is to increase the filling content of the filler in the resin by improving the slip property of the surface of the inorganic filler by coating the inorganic filler with a nano-sized thickness. It is to provide an inorganic filler nano-coating method.

Another object of the present invention is to control the material and the thickness of the coating layer when the silane is coated with an inorganic filler to a nano-sized thickness as important variables to control the thermal conductivity and withstand voltage characteristics through path formation and porosity reduction by the network between the inorganic fillers. It is to provide an inorganic filler nano-coating method that can be improved.

Another object of the present invention is to increase the compatibility of the inorganic filler and the resin by forming a silane coating layer having a nano-sized thickness on the inorganic filler, thereby enabling relatively high content filling, thereby dissipating heat when used in a heat-radiating composite material and a heat-radiating sheet. It is to provide an inorganic filler nano-coating method that can simultaneously meet the overvoltage characteristics.

Another object of the present invention is to provide a heat dissipation composite material using an inorganic filler prepared by the above-described inorganic filler nano-coating method.

Another object of the present invention is to provide a heat dissipation composite material and a heat dissipation sheet or heat dissipation pad using the same, which can realize excellent thermal conductivity and excellent withstand voltage characteristics by increasing the filling density of the inorganic filler by nano-coating a silane on the surface of the inorganic filler. .

In order to solve the above technical problem, an inorganic filler nanocoating method according to an aspect of the present invention comprises: diluting a silane with a solvent; Agitating by adding an inorganic filler to the silane solution diluted with the solvent; Grinding the inorganic filler added to the silane solution; Agitating by adding a curing agent or a binder after the grinding step; Filtering the silane-coated inorganic filler produced in the stirring step; And curing the inorganic filler coated with the silane.

In one embodiment, the dilution concentration of the solvent for diluting the low molecular weight silane in the diluting step is 20 to 40%. The low molecular weight silane includes silane coupling agent octoltriethoxy-silane (OTES) based silane, and isopropanol, ethanol or an aliphatic solvent may be used as the solvent.

In one embodiment, the step of stirring by adding the inorganic filler is stirred at room temperature by adding aluminum oxide.

In one embodiment, the step of agitating by adding the curing agent or binder, dilute the concentration of the silane solution to 0.01% to 10% with the curing agent or binder, and use a mechanical mixer to stir speed 500 rpm, stirring time 20 minutes It is stirred as follows.

In one embodiment, the step of agitating by adding the curing agent or binder further comprises dispersing the inorganic filler, aluminum oxide, using ultrasonic waves.

In one embodiment, methanol is used as the curing agent in the step of stirring by adding the curing agent or binder, and the weight ratio of the methanol and the aluminum oxide is 1: 2 in the order described.

In one embodiment, the step of stirring by adding the curing agent or binder, the content and time are differently controlled according to the type of the curing agent or binder and the degree of mixing.

In one embodiment, the inorganic filler nano-coating method may further include washing the filtered inorganic filler aluminum oxide with distilled water three or more times after the filtering step.

In one embodiment, the inorganic filler nanocoating method may further include drying after the curing step. In that case, in the curing step, the washed aluminum oxide is cured under the conditions of 70 ° C to 90 ° C, 50 minutes to 70 minutes, and the drying step comprises 50 ° C to 70 ° C, 22 of the cured aluminum oxide. It is dried under the conditions of hours to 26 hours.

The heat dissipation composite material according to another aspect of the present invention for solving the above technical problem is prepared by any one of the inorganic filler nanocoating methods of the above-described embodiments, and the inorganic filler having a silane nanocoating on the surface is a predetermined liquid. It is mixed with and made into a slurry.

The heat dissipation sheet according to another aspect of the present invention for solving the above technical problem is characterized in that it is manufactured using the heat dissipation composite material of the above-described embodiment.

When using the above-described inorganic filler nano-coating method of the present invention and the heat-radiating composite material and heat-radiating sheet using the inorganic filler prepared by this method, the heat dissipation properties and the breakdown voltage characteristics are measured using an inorganic filler having a silane-based nano-coating. At the same time, it is possible to provide a heat dissipation composite material and a heat dissipation sheet.

In addition, according to the present invention, nano-coating silane on the surface of the inorganic filler to increase the filling density of the inorganic filler to produce a composite material having excellent withstand voltage characteristics, and by using this, a heat dissipation sheet having excellent thermal conductivity and withstand voltage characteristics can be produced. have.

Further, according to the present invention, it is possible to provide a heat dissipation composite material having excellent reproducibility and a method for manufacturing a heat dissipation sheet using the same.

1 is a flow chart for explaining an inorganic filler nano coating method according to an embodiment of the present invention.
FIG. 2 is an enlarged partial surface of spherical aluminum oxide according to a comparative example, silane-coated aluminum oxide prepared by the method of FIG. 1, and silane-coated aluminum oxide.
3 is a view for explaining a composite material in a slurry form according to a comparative example and this embodiment.
4 is a scanning electron microscope (SEM) photograph of a nano-coated filler and a resin interface of a heat dissipation composite material according to another embodiment of the present invention.

Specific features and advantages of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings. In the following description, the terms or words used are based on the principle that the inventor can appropriately define the concept of terms in order to best describe his or her invention in the best way. It should be interpreted as.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, descriptions of already known functions or configurations may be omitted to clarify the gist of the present invention.

1 is a flow chart for explaining an inorganic filler nano coating method according to an embodiment of the present invention.

Inorganic filler nano-coating method according to this embodiment, the step of diluting silane with a solvent, adding an inorganic filler to the silane solution diluted with the solvent and stirring it, crushing the inorganic filler added to the silane solution, After the crushing step, a step of stirring by adding a curing agent or a binder, a step of filtering the silane-coated inorganic filler produced in the stirring step, and curing the silane-coated inorganic filler may be included.

More specifically, as shown in FIG. 1, first, silane (Silane) is diluted with methanol (S11). In the dilution process (S11), mechanical stirring may be performed. The dilution concentration of the methanol solvent for diluting the low molecular weight silane is preferably 20 to 40%. The low molecular weight silane includes silane coupling agent octoltriethoxy-silane (OTES) based silane, and isopropanol, ethanol or an aliphatic solvent may be used as the solvent.

Next, the dilution process or the stirring process following the dilution process is controlled according to the first process condition (S1) (S12). The first process condition (S1) may include stirring at a rotation speed of 500 rpm for 10 minutes. The stirred diluted solution will be referred to as a silane solution.

Next, aluminum oxide (Al2O3) is added as an inorganic filler to the silane solution (S13) and mixed at room temperature (S14).

Next, mechanical stirring is performed on the silane solution to which aluminum oxide is added (S15).

Next, the rotation speed and time are controlled and stirred according to the second process condition (S2) (S16). In the second process condition (S2), the rotation speed for stirring is 500 rpm, and the time may be 20 minutes to 40 minutes.

A curing agent or binder is added during the stirring process under the second process condition (S2). The amount of the curing agent or binder added may be selected in a range of diluting the concentration of the silane solution to 0.01% to 10%. Methanol may be used as the curing agent, and in this case, the weight ratio of methanol and aluminum oxide may be 1: 2 in the order described. The aforementioned stirring process corresponds to the surface treatment process.

In addition, in the stirring process (S16), aluminum oxide may be dispersed using ultrasonic waves to prevent agglomeration of aluminum oxide. The ultrasonic application process can be performed for 5 minutes for degassing and 20 minutes for dispersion.

In this embodiment, the content and time can be controlled differently according to the type of curing agent or binder and the degree of mixing.

Next, a filtering process for filtering aluminum oxide from the stirred solution using a mesh of a predetermined size or the like is performed (S17). During the process, silane is coated on the surface of aluminum oxide with a nano-sized thickness.

Next, the filtered aluminum oxide is washed three times or more with distilled water (S18).

Next, thermal curing is performed on the washed aluminum oxide (S19). The thermal curing process conditions (S3) may include curing process conditions and drying process conditions. Curing process conditions are controlled to cure the washed aluminum oxide at a curing temperature of 70 to 90 ° C and curing time of 50 to 70 minutes, and drying process conditions are for curing aluminum oxide at a drying temperature of 50 to 70 ° C and drying time of 22 to 26 hours. It can be controlled to dry under the condition of time (S20).

Table 1 shows the results of the component analysis spectrum of the silane-coated aluminum oxide.

Element wt% Atomic% Oxygen atom (O) 49.59 62.40 Aluminum (Al) 50.12 37.39 Silicon (Si) 0.29 0.21 total 100.00 100.00

FIG. 2 is an enlarged partial surface of spherical aluminum oxide according to a comparative example, silane-coated aluminum oxide prepared by the method of FIG. 1, and silane-coated aluminum oxide.

Referring to Comparative Examples (a) and (b) of FIG. 2, it can be seen that the surface of the spherical aluminum oxide 30 of this embodiment is smooth compared to the spherical aluminum oxide 20 of the comparative example. That is, as shown enlarged in FIG. 2 (c), the surface of the spherical aluminum oxide of the present embodiment is nano-coated with silane, thereby significantly reducing the surface curvature compared to the comparative example. That is, the surface area of the spherical aluminum oxide 30 of this embodiment is smaller than the surface area of the spherical aluminum oxide 20 of the comparative example.

The spherical aluminum oxide 30 of this embodiment is silane nanocoated and mixed with a predetermined solution to be made of a composite material in the form of a slurry.

 3 is a view for explaining a comparative example and a composite material in the form of a slurry in this example.

The comparative example shown in (a) of Figure 3 is to prepare a composite material 22 in the form of a slurry using a conventional aluminum oxide. This embodiment shown in Figure 3 (b) is to produce a composite material 32 in the form of a slurry of the same material and composition using the aluminum oxide produced by the method of Figure 1, Comparative Example (a) It can be seen that the viscosity is greatly improved compared to the composite material.

In actual use, it is also possible to mix the general composite material of the comparative example and the composite material of the present embodiment in an appropriate ratio and use them in the production of sheets, pads, and the like.

4 is a scanning electron microscope (SEM) photograph of a nano-coated filler and a resin interface of a heat dissipation composite material according to another embodiment of the present invention. 4 (b) is a partially enlarged view of the heat dissipation composite material 32 of (a).

4 (a) and (b), it is possible to clearly distinguish the interface between the nano-coated filler 30 and the resin 31 of this embodiment. That is, it can be seen that the nano-coated filler 30 of this embodiment has a relatively small effect on the surface of the resin 31 in comparison with the existing technology. This improves the dispersion of the filler 30, has a good effect on the thermal conductivity and withstand voltage characteristics, and thereby functions to provide a composite material having excellent reproducibility.

According to the above-described embodiments, in order to increase heat dissipation properties, fillers having a high thermal conductivity are used, and also under conditions of increasing the content, when a ceramic filler having a high content is used to increase the thermal conductivity, the air gap between the filler and the filler This can solve the problem of the prior art, which may cause the cause of the withstand voltage drop due to the air gap.

That is, in this embodiment, by coating the nano-sized silane on the surface of the inorganic filler, the content of the filler can be increased by improving the slip property, and multiple fillers can be introduced, thereby improving thermal conductivity and withstand voltage characteristics. In addition, in the influence of the filler and the resin due to the surface coating, the surface effect of the inorganic filler on the resin may be minimized by the nano-sized surface coating.

The above-described present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and other equivalent embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention should be defined by the technical spirit of the appended claims.

Claims (11)

Diluting the silane with a solvent;
Agitating by adding an inorganic filler to the silane solution diluted with the solvent;
Grinding the inorganic filler added to the silane solution;
Agitating by adding a curing agent or a binder after the grinding step;
Filtering the silane-coated inorganic filler produced in the stirring step;
Curing the silane-coated inorganic filler;
Inorganic filler nano coating method comprising a. The method according to claim 1,
The diluent concentration of the solvent for diluting the low molecular weight silane in the diluting step is 20 to 40%, inorganic filler nano coating method. The method according to claim 1,
In the step of adding the inorganic filler and stirring, the aluminum filler is stirred at room temperature by adding aluminum oxide. The method according to claim 1,
The step of agitating by adding the curing agent or binder is to dilute the concentration of the silane solution to 0.01% to 10% with the curing agent or binder and stir at a stirring speed of 500 rpm or stirring time of 20 minutes or less using a mechanical mixer. Inorganic filler nano coating method. The method according to claim 4,
The step of adding and curing the curing agent or binder further comprises dispersing the inorganic filler aluminum oxide by using ultrasonic waves, the inorganic filler nano-coating method. The method according to claim 5,
In the step of adding and stirring the curing agent or binder, methanol is used as the curing agent, and the ratio of the methanol to the aluminum oxide is 1: 2 in the order described, inorganic filler nano coating method. The method according to claim 1,
The step of adding and curing the curing agent or binder controls the content and time differently according to the type of the curing agent or the binder and the degree of mixing, the inorganic filler nano coating method. The method according to claim 1,
After the filtration step further comprising the step of washing the filtered inorganic filler aluminum oxide with distilled water three or more times, inorganic filler nano coating method. The method according to claim 8,
Further comprising a step of drying after the curing step,
In the curing step, the washed aluminum oxide is cured under conditions of 70 ° C to 90 ° C, 50 minutes to 70 minutes,
In the drying step, the cured aluminum oxide is dried under conditions of 50 ° C to 70 ° C, 22 hours to 26 hours, and an inorganic filler nanocoating method. A heat dissipation composite material characterized by being made in the form of a slurry by mixing an inorganic filler prepared by any one of claims 1 to 9 with an inorganic filler having a silane nanocoating on its surface in a predetermined liquid. A heat radiation sheet, characterized in that it is manufactured using the heat radiation composite material of claim 10.

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