KR20210064459A - Manufacturing method of thermally conductive masterbatch based on thermoplastic resin and heat sink composite using the same - Google Patents

Abstract

The present invention relates to a manufacturing method of a thermally conductive masterbatch based on a thermoplastic resin and a heat dissipation composite material using the same. The present invention can provide the pellet-shaped heat dissipation composite material made of an extrudate melt-extruded by mixing with a polymer resin without a separate grinding process as the dispersibility of the thermal conductivity filler in the thermoplastic resin is excellent, and a granular particle size that can be injected during a polymerization process is secured by providing the thermally conductive masterbatch based on the thermoplastic resin polymerized in situ by mixing a thermally conductive filler in a monomer polymerization process of the thermoplastic resin.

Description

Manufacturing method of a thermoplastic resin-based thermally conductive masterbatch and heat dissipation composite material using the same {MANUFACTURING METHOD OF THERMALLY CONDUCTIVE MASTERBATCH BASED ON THERMOPLASTIC RESIN AND HEAT SINK COMPOSITE USING THE SAME}

The present invention relates to a method for producing a thermoplastic resin-based thermally conductive masterbatch and a heat dissipation composite material using the same, and more particularly, by mixing a thermally conductive filler in a monomer polymerization process of a thermoplastic resin and polymerizing in situ, A thermoplastic resin-based thermally conductive masterbatch is prepared in which the thermally conductive filler is uniformly dispersed and can be secured in a granular particle size that can be injected during the polymerization process, and melt-extruded by mixing the thermoplastic resin-based thermally conductive masterbatch with a polymer resin It relates to a pellet-shaped heat dissipation composite material made of an extrudate.

In general, a heat dissipating material such as a heat sink is used in electronic products and automobile parts to dissipate heat generated during use.

Heat dissipation materials with heat dissipation characteristics are widely used in electric and electronic parts such as LED lighting fixtures, industrial inverters, electric vehicles, robot devices, and photovoltaic power generation. In particular, with the recent development of electronic product technology, as the amount of heat generated by the electronic product itself increases due to high directivity, high density, and high performance of electronic products, a material with high thermal conductivity is required to effectively discharge the increased amount of heat. have.

In addition, the space for dissipating heat becomes smaller by the pursuit of miniaturization, weight reduction, minimum space, and portability of electronic products, so that the performance of the heat dissipation material may be significantly reduced or malfunction due to the heat generated during use of the electronic product. In this regard, the importance of heat-dissipating materials is increasing.

As a method for imparting thermal conductivity to thermoplastic resins, since thermoplastic resins generally have low thermal conductivity, fillers such as carbon materials, metal powders, and ceramic powders with high thermal conductivity are added or compounded to realize thermal conductivity. At this time, a filler with high thermal conductivity must be added in a high content, and the completed thermoplastic resin composite material must create a heat transfer path so that heat can move from one side to the other.

Therefore, there is a close relationship between the content of the thermally conductive filler and the thermal conductivity of the thermoplastic resin composite material.

However, the thermoplastic resin has a high viscosity even at a temperature above the melting point and has a viscosity of tens to several million, so there is a problem in that it is difficult to add or complex a high content of thermally conductive filler.

In addition, when a resin highly filled with plate-shaped particles is produced in the form of a plate by injection molding to manufacture a polymer-based heat-dissipating composite material, the heat-dissipating plate-shaped particles are uniaxially oriented in the injection direction by shear force in the injection direction. Heat conduction is good in the arrangement direction (heat dissipation is good), but heat conduction is not well done in the other direction, resulting in a problem of thermal conductivity anisotropy (thermal conductivity is different depending on the direction) and heat dissipation performance is deteriorated.

In addition, in the case of a high-filling heat-dissipating composite material manufactured by conventional injection molding, workability is reduced due to the high flowability of the resin, and the filled plate-shaped particles are expensive and have a heavy weight.

In order to solve the above problems, Patent Document 1 is a polymer-based heat dissipation composite material that can improve heat dissipation performance, as a main component of a polymer-based continuous phase resin, chemically bonding with the continuous phase resin, and on the continuous phase resin. Mixed and dispersed heat dissipation filler; and dispersed phase particles that are incompatible with the heat dissipation filler and cause phase separation from the heat dissipation filler when mixed with the continuous resin and the heat dissipation filler, and make the arrangement direction of the heat dissipation filler irregular during injection; and random orientation of the heat dissipation filler It is described that the problem of anisotropy of thermal conductivity is solved through the

Patent Document 2 discloses a heat sink of a thermally conductive plastic material for a battery or electronic device, comprising expanded graphite in an amount of at least 20% by weight based on the total weight of the thermally conductive plastic material. However, in Patent Document 2, the graphite is not properly dispersed in the polymer, and it contains a relatively small amount of expanded graphite, so it is somewhat difficult to obtain a desired thermal conductivity.

In addition, in order to secure sufficient thermal conductivity, other thermally conductive fillers and thermally conductive components such as thermally conductive fibers are included in addition to graphite. In order to increase thermal conductivity, the more the filler is filled, the more the viscosity rises due to poor flowability, There are problems in that it is difficult to produce a product due to a decrease in processability, and the appearance and physical properties of the final product are deteriorated.

As a heat dissipation material currently in use, aluminum die-casting material is representative, and its demand is dependent on foreign imports.

Aluminum die-casting heat dissipation material has excellent thermal conductivity, but it is heavy, difficult to form, and has processing conditions that are harmful to the environment, such as insulation coating.

In order to compensate for the above disadvantages, recently, by manufacturing a heat dissipating material using a thermally conductive composite plastic, a heat dissipating material that is free to implement various shapes and is lightweight compared to the case of using a metal has been manufactured. Such a conventional thermally conductive composite plastic is made by using a filler excellent in thermal conductivity, and aluminum nitride, boron nitride, silicon nitride, etc. are used as fillers for high thermal conductivity [Patent Document 3].

However, since these materials are not only expensive, but most of them depend on imports, there is another problem in that the manufacturing cost increases when using them to produce heat dissipation materials. Therefore, carbon-based fillers are currently manufactured using various polymer resins as a base. Heat dissipation material in the form of a master batch (intermediate material) is being developed by dispersing it, but due to reasons such as heat dissipation, insulation and price competitiveness, it cannot completely replace the aluminum die-casting heat dissipation material.

Therefore, as a result of the present inventors' efforts to solve the conventional problems, by mixing the thermal conductivity filler in the monomer polymerization process of the thermoplastic resin and polymerizing it in situ, the dispersibility of the thermal conductivity filler in the resin is excellent and the particle size that can be injected during the polymerization process is reduced. The present invention was completed by manufacturing a thermoplastic resin-based thermally conductive masterbatch, and confirming the physical properties of a heat dissipating composite material made of an extrudate melt-extruded by mixing the thermoplastic resin-based thermally conductive masterbatch and a polymer resin without a separate grinding process did.

Republic of Korea Patent Publication No. 2013-0038775 (published on April 18, 2013) Republic of Korea Patent Publication No. 2010-0126415 (published on Dec. 1, 2010) Republic of Korea Patent Publication No. 2019-0120421 (published on October 23, 2019)

It is an object of the present invention to provide a method for preparing a thermoplastic resin-based thermally conductive masterbatch, in which a thermally conductive filler is mixed and polymerized in situ in a monomer polymerization process of a thermoplastic resin.

Another object of the present invention is to provide a heat dissipation composite material using the thermoplastic resin-based thermally conductive masterbatch.

In order to achieve the above object, the present invention provides a method for preparing a thermoplastic resin-based thermally conductive masterbatch, in which a thermally conductive filler is mixed with a thermoplastic resin monomer-containing solution and polymerized in situ.

At this time, with respect to 100 parts by weight of the thermoplastic resin monomer, 300 to 800 parts by weight of the thermal conductivity filler is contained.

A preferred embodiment of the thermoplastic resin monomer-containing solution is (A) an anionic caprolactam and (B) a reaction tank containing an initiator containing sodium caprolactamate, and (A) anionic caprolactam and (C) hexamethylene dicarbamoyl A reactor containing an activator including dicaprolactam is mixed and polymerized.

At this time, in order to successfully complete the polymerization reaction, 3 to 5 parts by weight of (B) the initiator and 2 to 3 parts by weight of the (C) activator are mixed and polymerized with respect to the weight part of the anion caprolactam.

The thermal conductivity filler used in the present invention is any one carbon material selected from the group consisting of graphite, expanded graphite, carbon nanotubes (CNT), graphene and carbon nanofibers (CNF); Alternatively, any one inorganic material selected from the group consisting of boron nitride (BN), alumina (Al ₂ O ₃ ), aluminum nitride (AlN), ceramic material, copper and aluminum may be used, and in the embodiment of the present invention, graphite is used However, it will not be limited thereto.

The thermoplastic resin-based thermally conductive masterbatch of the present invention is a granular type with a particle size of 500 to 6mm.

The present invention is a pellet-shaped heat dissipation composite material composed of an extrudate in which 30 to 60 wt% of a thermoplastic resin-based granular-type thermally conductive masterbatch and 40 to 70 wt% of a polymer resin obtained from the above manufacturing method are mixed and melt-extruded through an extruder. provides

According to the present invention, it is possible to provide a thermoplastic resin-based thermally conductive masterbatch that is polymerized in situ by mixing a thermal conductivity filler in the monomer polymerization process of a thermoplastic resin having a low viscosity and high flowability compared to a thermoplastic resin.

In the thermoplastic resin-based thermally conductive masterbatch of the present invention, a high content of thermally conductive filler is uniformly dispersed, and can be obtained in a granular particle size that can be injected during the polymerization process.

Therefore, when applied to the powder mixing process, the extruded product mixed with the polymer resin is palletized and injected without a separate grinding process, thereby securing easy moldability, increasing productivity, excellent price competitiveness, and thermal conductivity. It is possible to provide a heat dissipation composite material with excellent heat dissipation characteristics.

1 is a schematic diagram of a reactor for producing a thermoplastic resin-based thermally conductive masterbatch of the present invention;
2 is a photograph of a thermoplastic resin-based thermally conductive masterbatch of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention provides a method for preparing a thermoplastic resin-based thermally conductive masterbatch, in which a thermally conductive filler is mixed with a thermoplastic resin monomer-containing solution and polymerized in situ.

Specifically, a preferred embodiment of the thermoplastic resin monomer-containing solution is (A) an anionic caprolactam and (B) a reactor containing an initiator containing sodium caprolactamate, and (A) anionic caprolactam and (C) hexamethylenedica. A reactor containing an activator including bamoyldicaprolactam is mixed and polymerized.

Accordingly, FIG. 1 is a schematic diagram of a reactor for manufacturing the thermoplastic resin-based thermally conductive masterbatch of the present invention, and a reaction tank 10 in which an initiator containing (A) anionic caprolactam and (B) sodium caprolactamate is mixed (A) anionic caprolactam and (C) hexamethylene dicarbamoyl dicaprolactam are mixed at the same time so that the reaction tank 11 is mixed in the polymerization tank 30 heated to 150-160 ° C. React with stirring to complete the nylon polymerization reaction. At this time, the reactors 10 and 11 are prepared by heating at a temperature of 90° C. for smooth mixing between the components.

A thermal conductivity filler 40 is included in the polymerization tank 30 .

The thermal conductivity filler is a carbon material; Alternatively, an inorganic material of a metal or non-metal type may be used. As a specific example, the carbon material is any one selected from the group consisting of graphite, expanded graphite, CNT, graphene and CNF carbon fiber, and the metal or non-metal-based inorganic material is BN (boron nitride), Al ₂ O ₃ ( alumina), AlN (aluminum nitride), a ceramic material, copper and aluminum, any one selected from the group consisting of is used.

In the embodiment of the present invention, it is preferably described using graphite, but it will not be limited thereto.

In addition, in order to complete the smooth nylon polymerization reaction in FIG. 1, (B) 3 to 5 parts by weight of the initiator and 2 to 3 parts by weight of the (C) activator are mixed and polymerized with respect to the parts by weight of the anion caprolactam [ Table] 1 ].

From the above, in the present invention, the thermal conductivity filler is polymerized in situ in a solution containing a thermoplastic resin monomer having a low viscosity and thus a high flowability compared to the thermoplastic resin, so that the thermal interface contact between the compositions is smooth and the dispersibility problem is solved at the same time. It may be contained in a high content. Accordingly, with respect to 100 parts by weight of the thermoplastic resin monomer, the thermal conductivity filler may provide a high content masterbatch containing 300 to 800 parts by weight.

2 is a photograph of a thermoplastic resin-based thermally conductive masterbatch prepared by the manufacturing method of the present invention, and is obtained in a granular-type particle size that can be injected during the polymerization process.

Specifically, by providing a granular type thermoplastic resin-based thermally conductive masterbatch having a particle size of 500㎛ to 6mm, when applied to the powder mixing process, it can be performed without a separate grinding process, thereby increasing price competitiveness due to the omission of the process It can also fundamentally solve problems such as worker's health and facilities when working with powder.

Furthermore, the present invention is a pellet-shaped heat dissipation made of an extrudate in which 30 to 60% by weight of a thermally conductive masterbatch of the thermoplastic resin-based granular type obtained from the above manufacturing method and 40 to 70% by weight of a polymer resin are mixed and then melt-extruded through an extruder. Composite materials are provided.

The polymer resin used in the above includes PP (polypropylene), PA6 (Polyamide6), PET (Polyethylene terephthalate), PBT (poly-butylene-terephthalate), PA66 (Polyamide66), etc., ABS (acrylonitrile butadiene styrene copolymer), PC (polycarbonate) and PA (polyamide) can also be applied. That is, in the present invention, a thermoplastic resin-based thermally conductive masterbatch obtained in granular particle size that can be injected during the polymerization process is mixed with a polymer resin without a separate grinding process. By palletizing an extruded product to enable injection, it provides a heat dissipation composite material with excellent heat dissipation properties by securing easy moldability, increasing productivity, excellent price competitiveness, and improved thermal conductivity. After the extrusion As the heat cools, the polymer resin absorbs moisture, so if the moisture increases, the injection molding properties may deteriorate.

Therefore, since the moisture content is increased by absorbing moisture immediately after extrusion molding, the step of dehumidifying and drying the extrusion-molded pellets may be further performed.

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

These examples are for explaining the present invention in more detail, and the scope of the present invention is not limited to these examples.

<Production Example 1>

A mixture of 100 g of anion caprolactam and 6 g of sodium caprolactamate as an initiator was mixed in reactor A at 90° C., 100 g of anion caprolactam and 4 g of activator hexamethylene dicarbamoyldicaprolactam were mixed in reactor B. After that, the initiator and activator mixtures in reactors A and B were simultaneously injected into reactor C heated to 160° C., and then reacted for 20 minutes with slow stirring. After cooling the reactor, it was taken out and the degree of polymerization of the reactant was measured.

<Preparation Example 2>

A mixture of 100 g of anion caprolactam and 8 g of sodium caprolactamate as an initiator was mixed in reactor A at 90° C., 100 g of anion caprolactam and 5 g of activator hexamethylene dicarbamoyldicaprolactam were mixed in reactor B. Thereafter, the initiator and activator mixtures in reactors A and B were simultaneously injected into reactor C heated to 160° C., and then reacted for 20 minutes with slow stirring. After the reactor was cooled, it was taken out and the degree of polymerization of the reactant was measured.

<Comparative Preparation Example 1>

100 g of anion carprolactam and 4 g of sodium caprolactamate as an initiator were mixed in reactor A at 90°C, 100 g of anion caprolactam and 3 g of activator hexamethylene dicarbamoyl dicaprolactam were mixed in reactor B mixed. Thereafter, the initiator and activator mixtures in reactors A and B were simultaneously injected into reactor C heated to 160° C., and then reacted for 20 minutes with slow stirring. After cooling the reactor, it was taken out and the degree of polymerization of the reactant was measured.

The reaction-completed specimen was cut to a predetermined size, and then the weight was measured. When the specimen is immersed in distilled water for 24 hours, unpolymerized caprolactam is dissolved. After sufficiently impregnated in distilled water, it is dried for one day (24 hours), and after drying, the weight of the specimen is measured, and the polymerization conversion rate can be calculated by substituting it for the polymerization conversion rate of Equation 1 below.

Equation 1

Polymerization conversion (%) = (1-(M _mon /M _tot ))×100

In the above, M _mon is the weight of unreacted caprolactam, and M _tot is the total weight after completion of the reaction.

<Example 1>

A mixture of 50 g anion caprolactam and 3 g sodium caprolactamate as an initiator was mixed in reactor A at 90° C., 50 g anion caprolactam and 2 g activator hexamethylene dicarbamoyldicaprolactam were mixed in reactor B. After that, the initiator and activator mixtures in reactors A and B were heated to 160° C. and simultaneously injected into reactor C containing 800 g of graphite powder, and then reacted for 20 minutes with slow stirring to form a granular graphite masterbatch. prepared. After cooling the reactor, it was taken out and the degree of polymerization of the reactant was measured.

<Example 2>

220 g of the granular graphite masterbatch prepared in Example 1 and 430 g of polyamide were put into a 10L plastic barrel, shaken and mixed, and melt-extruded using a twin-screw extruder heated to 200 to 260 ° C. A pellet-shaped heat dissipation composite material containing graphite was prepared.

<Example 3>

290 g of the granular graphite masterbatch prepared in Example 1 and 360 g of polyamide were put in a 10L plastic barrel and mixed by shaking, and then melt-mixed using a twin screw extruder heated to 200 to 260 ° C. A pellet-shaped heat dissipation composite material containing graphite was prepared.

<Example 4>

In Example 1, 365 g of granular graphite masterbatch and 285 g of polyamide were put in a 10L plastic barrel and mixed by shaking, and then melt-mixed using a twin-screw extruder heated to 200 to 260° C. to obtain about 50% of graphite. A heat dissipation composite material in the form of pellets was prepared.

<Example 5>

In the same manner as in Example 1, a mixture of 50 g of anion caprolactam and 3 g of sodium caprolactamate as an initiator was mixed in reactor A at 90° C., 50 g of anion caprolactam and 2 g of hexamethylene dicarbamoyl dicaprolactam as an activator were mixed. Mix in reactor B. After that, the initiator and activator mixtures in reactors A and B were heated to 160° C. and simultaneously injected into reactor C containing 800 g of graphite, followed by reaction for 20 minutes with slow stirring to prepare a graphite masterbatch. The graphite was immersed in a nylon-based sizing agent of 3% by weight before being put into the reactor C, and then dried at 130° C. and then used. After cooling the reactor, it was taken out and the degree of polymerization of the reactant was measured.

<Example 6>

365 g of the graphite masterbatch prepared by the method of Example 5 and 285 g of polyamide were put in a 10L plastic barrel and mixed by shaking, and then melt-mixed using a twin screw extruder heated to 200 to 260 ° C. A pellet-shaped heat dissipation composite material containing graphite was prepared.

<Comparative Example 1>

195 g (30 wt %) of graphite powder and 455 g (70 wt %) of freeze-pulverized polyamide are put in a 10L plastic barrel, shaken and mixed, and then melt-mixed using a twin screw extruder heated to 200 to 260 ° C to obtain graphite. The contained polymer composite pellets were prepared.

<Comparative Example 2>

260 g (40 wt %) of graphite powder and 390 g (60 wt %) of freeze-pulverized polyamide are put in a 10L plastic barrel, shaken and mixed, and then melted and mixed using a twin-screw extruder heated to 200 to 260 ° C to obtain graphite. The contained polymer composite pellets were prepared.

<Comparative Example 3>

325 g (50 wt %) of graphite powder and 325 g (50 wt %) of freeze-pulverized polyamide are put in a 10L plastic barrel, shaken and mixed, and then melted and mixed using a twin-screw extruder heated to 200 to 260 ° C to obtain graphite. The contained polymer composite pellets were prepared.

<Experimental Example 1> Physical property evaluation

prepared in Examples 1 to 4 above. Polymer composite pellets containing graphite are injection molded into heat conduction and tensile test pieces using an injection molding machine.

The results for the thermal conductivity, electrical conductivity and tensile strength of the injection-molded test piece are shown in Table 2 below.

As can be seen in Table 2, the heat dissipation composite materials prepared in Examples 2 to 4 showed physical properties equal to or greater than that of the materials of Comparative Examples 1 to 3 applied in powder form, in thermal conductivity, electrical conductivity, and tensile strength.

This physical property result is due to the use of the granular graphite masterbatch of Example 1, and since graphite powder is impregnated and polymerized in the monomer polymerization process of a thermoplastic resin having a low viscosity and high flowability compared to a thermoplastic resin, the dispersibility problem has been solved. back up

From the results of Examples 5 and 6, when a nylon sizing agent was added to the graphite masterbatch manufacturing step and polymerized, the improvement of the interface between the graphite (filler) and the polyamide (matrix) ultimately improved the physical properties of the thermally conductive composite material The results were confirmed.

In addition, when the heat dissipation composite material is manufactured, the use of a granular type graphite masterbatch, not a powder form, is used, and thus the handleability is excellent. In particular, the granular type graphite masterbatch of the present invention is used in the polymerization process without a separate grinding process. It has excellent workability because it can be secured with a particle size that can be injected.

In the above, the present invention has been described in detail only with respect to the described embodiments, but it is apparent to those skilled in the art that various changes and modifications are possible within the scope of the technical spirit of the present invention, and it is natural that such variations and modifications belong to the appended claims.

10, 11: Reactor
20: gas inlet 21: vacuum outlet
30: polymerization tank 40: thermal conductivity filler

Claims (6)

In-situ polymerization is performed by mixing a thermal conductivity filler with a solution containing a thermoplastic resin monomer.
With respect to 100 parts by weight of the thermoplastic resin monomer, the thermal conductivity filler contains 300 to 800 parts by weight, a method for producing a thermoplastic resin-based thermally conductive masterbatch. The method according to claim 1, wherein the thermoplastic resin monomer-containing solution is
(A) a reactor containing an initiator comprising anionic caprolactam and (B) sodium caprolactamate; and
(A) Anionic caprolactam and (C) a method for producing a thermoplastic resin-based thermally conductive masterbatch, characterized in that the reaction tank containing an activator containing hexamethylene dicarbamoyl dicaprolactam is mixed polymerization. [Claim 3] The preparation of a thermoplastic resin-based thermally conductive masterbatch according to claim 2, wherein 3 to 5 parts by weight of (B) the initiator and 2 to 3 parts by weight of the (C) activator are polymerized based on parts by weight of the anion caprolactam. Way. According to claim 1, wherein the thermally conductive filler is any one carbon material selected from the group consisting of graphite, expanded graphite, carbon nanotubes, graphene, and carbon nanofibers; Or boron nitride, alumina, aluminum nitride, ceramic material, any one inorganic material selected from the group consisting of copper, aluminum and iron; Method for producing a thermoplastic resin-based thermally conductive masterbatch, characterized in that. The method of claim 1, wherein the thermoplastic resin-based thermally conductive masterbatch is a granular type having a particle size of 500㎛ to 6mm. Claims 1 to 5, wherein 30 to 60% by weight of the thermoplastic resin-based thermally conductive masterbatch and 40 to 70% by weight of the polymer resin prepared from any one of claims 1 to 5 are mixed and then melt-extruded through an extruder. Heat dissipation composite material.

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