KR102498312B1 - Composition for manufacturing graphite-polymer composite and Graphite-polymer composites comprising the same - Google Patents

Abstract

A composition for preparing a graphite-polymer composite is provided. A composition for preparing a graphite-polymer composite according to an embodiment of the present invention includes a heat dissipating filler having a graphite composite including nanoparticles bonded to a graphite surface and a catecholamine layer, a matrix forming component including a thermoplastic polymer compound, and a coupling agent It is implemented by including additives that do. According to this, stability and durability can be ensured by improving interfacial adhesion and dispersibility between the polymer compound and the heat radiation filler and at the same time minimizing heat radiation performance and mechanical property degradation. In addition, it is very easy to mold when molding through injection/extrusion by being combined with a substrate, and molding into various shapes is possible. The composite material thus implemented exhibits excellent heat dissipation performance, at the same time guarantees excellent mechanical strength, is excellent in light weight, and has excellent economic feasibility, so it can be widely applied in various technical fields requiring heat dissipation.

Description

Composition for manufacturing graphite-polymer composite and graphite-polymer composites comprising the same}

The present invention relates to a composition for preparing a graphite-polymer composite, and more particularly, to a composition for preparing a graphite-polymer composite that improves interfacial adhesion and dispersibility to different materials and at the same time does not deteriorate heat dissipation performance and mechanical properties, and thereby It relates to the realized graphite-polymer composite.

Heat build-up in electronics, light fixtures, converter housings and other devices that generate unwanted heat can severely limit product life and reduce operating efficiency. Metals, which are good thermal conductors, have traditionally been used for thermal management devices such as heat sinks and heat exchangers. However, the metal part is heavy and has a high production cost.

In recent years, a heat dissipation member manufactured using injection molding or extrudable polymer resin has been proposed, and many studies have been conducted due to advantages such as light weight and low unit price due to the material characteristics of the polymer resin itself.

The heat dissipation member is provided with a heat dissipation filler in order to express a desired heat dissipation property, and the heat dissipation filler is inevitably different from a polymer resin having a low thermal conductivity in terms of material, and thus a problem arises in compatibility between the dissimilar materials. For example, ideally, uniform dispersion of the functional filler in the polymer resin may be advantageous in terms of heat dissipation performance. However, the heat dissipation performance due to the dispersibility problem that causes cutting may be significantly deteriorated.

In addition, since the heat radiating filler has a high viscosity in a molten state, it is not easy to impregnate between the polymer resins, and the interface between the heat radiating filler and the polymer resin is deteriorated due to the low surface free energy of the heat radiating filler. Separation may occur. Since this interfacial separation phenomenon can cause deterioration of the heat dissipation properties and mechanical properties of the heat dissipation member along with the above-mentioned decrease in dispersibility, many studies have been attempted to improve the interfacial adhesion between the added heat dissipation filler and the polymer resin. .

As an example of this, oxidation treatment, plasma treatment, whiskeri-zation treatment, etc. of the surface of the radiating filler have been introduced, but only the surface treatment of the radiating filler improves the interfacial adhesion characteristics between the radiating filler and the polymer resin. There is a limit to this, and there is a concern that dispersibility may be impaired through treatment with heterogeneous materials, and furthermore, chemical treatment may affect the heat radiation performance of the heat radiation filler, so it does not cause a decrease in heat radiation performance and mechanical properties, and At the same time, there is an urgent need for research to improve the interfacial adhesion and dispersibility of heat dissipating fillers and polymer resins.

Publication No. 10-2016-0031103

The present invention has been devised in view of the above points, and the present invention improves interfacial adhesion and dispersibility between the polymer resin and the heat radiation filler, and at the same time minimizes heat radiation performance and mechanical property degradation, thereby ensuring stability and durability An object of the present invention is to provide a composition for preparing a graphite-polymer composite suitable for preparing a graphite-polymer composite.

In addition, another object of the present invention is to provide a composition for preparing a graphite-polymer composite that can be molded by various molding methods such as injection/extrusion and can be easily molded into a molded body in various shapes.

In addition, the present invention provides a graphite composite that exhibits excellent heat dissipation performance through the composition for preparing a graphite-polymer composite as described above, while ensuring excellent mechanical strength, excellent light weight, excellent economic feasibility, and realized in various shapes. It has another purpose.

In order to solve the above problems, the present invention includes a heat dissipating filler having a graphite composite including nanoparticles and a catecholamine layer bonded to the surface of graphite, a matrix forming component including a thermoplastic polymer compound, and an additive including a coupling agent. A composition for preparing a graphite-polymer composite is provided.

In addition, according to an embodiment of the present invention, the coupling agent may be a silane coupling agent, maleic acid graft polypropylene (MAH-g-PP), or maleic acid graft EPDM (MAH-g-EPDM).

In addition, the maleic acid-grafted polypropylene may be included in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the thermoplastic polymer compound.

In addition, the maleic acid graft EPDM may be included in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the total thermoplastic polymer compound.

In addition, the graphite composite may further include a polymer layer coated on at least the catecholamine layer.

In addition, the graphite composite may have an average particle diameter of 50 to 600 μm.

In addition, the thermoplastic polymer compound is polyamide, polyester, polyketone, liquid crystal polymer, polyolefin, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyphenylene oxide (PPO), polyether sulfone (PES) ), one compound selected from the group consisting of polyetherimide (PEI) and polyimide, or a mixture or copolymer of two or more.

In addition, one or more additives selected from the group consisting of a flame retardant, a strength improver, a dispersant, an antioxidant, a work improver, a coupling agent, a light stabilizer, a heat stabilizer, and a UV absorber may be further included.

In addition, the present invention provides a master batch for preparing a graphite-polymer composite material in which the above-described composition for preparing a graphite-polymer composite material is molded.

In addition, the present invention is molded with a heat dissipating filler having a graphite composite including nanoparticles and a catecholamine layer bonded to the surface of graphite, an additive including a coupling agent, and a thermoplastic polymer compound, and the heat dissipating filler and the additive are dispersed therein. Provided is a graphite-polymer composite including a polymer matrix.

In addition, the heat radiation filler may be included in 10 to 90% by weight of the total weight of the graphite-polymer composite.

In addition, a protective coating layer may be further provided on the outer surface of the polymer matrix.

According to the present invention, stability and durability can be ensured by improving interfacial adhesion and dispersibility between the polymer compound and the heat radiation filler and at the same time minimizing heat radiation performance and mechanical property degradation. In addition, it is very easy to mold when molding through injection/extrusion by being combined with a substrate, and molding into various shapes is possible. The composite material implemented according to this can be widely applied to various technical fields requiring heat dissipation as it exhibits excellent heat dissipation performance, guarantees excellent mechanical strength, is excellent in light weight, and has excellent economic feasibility.

1 is a diagram of a graphite composite according to an embodiment of the present invention, wherein FIG. 1A is a perspective view of the graphite composite, FIG. 1B is a cross-sectional view along the XX′ boundary of FIG. 1A, and
2 is a cross-sectional view of a graphite-polymer composite according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. This invention may be embodied in many different forms and is not limited to the embodiments set forth herein. In order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are added to the same or similar components throughout the specification.

A composition for preparing a graphite-polymer composite according to an embodiment of the present invention includes a heat-dissipating filler having a graphite composite including nanoparticles bonded to the surface of graphite and a catecholamine layer, a matrix forming component including a thermoplastic polymer compound, and a coupling agent It is implemented by including additives that do.

First, a heat dissipation filler including a graphite composite will be described.

As shown in FIGS. 1A and 1B, the heat dissipating filler 101 having the graphite composite includes nanoparticles 20 and a catecholamine layer 30 bonded to the surface of the graphite 10, and the polymer layer 40 ) may be further included.

The graphite 10 is a mineral in which planar macromolecules, in which 6-membered rings of carbon atoms are infinitely connected in a plane, are layered and superimposed, and may be of a type known in the art, specifically, impression graphite, high crystalline graphite, and earthy graphite It may be either natural graphite or artificial graphite. When the graphite 10 is natural graphite, for example, it may be expanded graphite obtained by expanding impression graphite. The artificial graphite may be prepared through a known method. For example, a thermosetting resin such as polyimide is prepared in the form of a film of 25 μm or less and then graphitized at a high temperature of 2500 ° C. or higher to produce graphite in a single crystal state, or a hydrocarbon such as methane is thermally decomposed at a high temperature to obtain chemical vapor deposition (CVD) ), it is also possible to manufacture highly oriented graphite.

In addition, the shape of the graphite 10 may be a known shape such as a spherical shape, a plate shape, or a needle shape, or an atypical shape, and may be a plate shape as an example. In addition, the average particle diameter of the graphite 10 may be 50 to 600 μm, for example, 300 μm, and the graphite 10 may be high-purity graphite having a purity of 99% or more, through which more improved physical properties It may be advantageous to express.

Next, the nanoparticles 20 bonded to the surface of the above-described graphite 10 function as a medium capable of providing the graphite 10 with a catecholamine layer 30 to be described later. Specifically, since the surface of the above-described graphite 10 is rarely provided with functional groups capable of mediating chemical reactions, a catecholamine layer capable of improving the dispersibility of the graphite 10 in heterogeneous materials ( 30) on the surface of the graphite 10, there is a problem in that the amount of catecholamine actually remaining in the graphite is very small even if the graphite is treated with catecholamine. In addition, in order to solve this problem, even if the surface of graphite is modified to have functional groups, there is a limit to increasing the amount of catecholamine provided on the surface of the modified graphite. However, in the case of graphite having nanoparticles on the surface, since catecholamines are easily bonded to the surface of the nanoparticles, a desired amount of catecholamines can be introduced into the graphite.

The nanoparticle 20 may be a metal or non-metal material that exists as a solid at room temperature, and as non-limiting examples thereof, alkali metals, alkaline earth metals, lanthanum groups, actinium groups, transition metals, post-transition metals, It may be selected from metalloids and the like. For example, the nanoparticles may be Ni, Si, Ti, Cr, Mn, Fe, Co, Cu, Sn, In, Pt, Au, Mg, or a combination thereof, and may be Cu, Ni, or Si.

In addition, the nanoparticles 20 may have an average particle diameter of 10 to 500 nm, preferably 10 to 100 nm.

In addition, the nanoparticles 20 are preferably in a crystallized particle state, and may be provided to occupy 10 to 70% of the total surface area of each graphite 10, more preferably 30 to 70% of the area. there is. In addition, the nanoparticles 20 may be provided in an amount of 5 to 70% by weight, preferably 20 to 50% by weight, based on the total weight of the heat dissipating filler 101 including the graphite composite. At this time, the nanoparticles 20 can express a stronger bonding force by forming a chemical bond with the graphite 10.

Next, the catecholamine layer 30 may be provided on at least the surface of the above-described nanoparticles 20, and through this, excellent fluidity and dispersibility of graphite in a polymer compound of a heterogeneous material described later, and between the graphite composite and the polymer compound Interfacial bonding properties can be improved. In addition, the catecholamine layer 30 itself has reducing power and at the same time forms a covalent bond between the catechol functional group on the surface of the layer and the amine functional group by Michael addition reaction, so that the catecholamine layer is used as an adhesive material for secondary surface modification. This is possible, and for example, it can act as a bonding material capable of introducing the polymer layer 40 into graphite in order to express more improved dispersibility in the polymer compound.

The catecholamine forming the catecholamine layer 30 has a hydroxyl group (-OH) as the ortho-group of the benzene ring and a para-group having various alkylamines. A term meaning a single molecule As non-limiting examples of various derivatives of these structures, dopamine, dopamine-quinone, epinephrine, alpha-methyldopamine, norepinephrine, alpha-methyl It may be alphamethyldopa, droxidopa, indolamine, serotonin, or 5-hydroxydopamine, and the like. As an example, the catecholamine layer 30 is dopamine dopamine) layer. The dopamine is a monomolecular substance having a catechol and an amine functional group and having a molecular weight of 153 (Da). As an example, a substance to be surface modified in an aqueous solution under basic pH conditions (about pH 8.5) containing dopamine represented by Formula 1 below If it is put in and taken out after a certain period of time, a polydopamine (pDA) coating layer may be formed on the surface of the material by oxidation of catechol.

[Formula 1]

In Formula 1, at least one of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ is each selected from a thiol, a primary amine, a secondary amine, a nitrile, and an aldehyde. ), imidazole, azide, halide, polyhexamethylene dithiocarbonate, hydroxyl, carboxylic acid, carboxylic ester) or one selected from the group consisting of carboxamide, and the rest may be hydrogen.

In addition, the thickness of the catecholamine layer 30 may be 5 ~ 100 ㎚, but is not limited thereto.

On the other hand, the polymer layer 40 may be further coated on the catecholamine layer 30, and as compatibility with the polymer compound forming the composite material increases due to the polymer layer 40, further improved fluidity, dispersibility and interface binding properties can be implemented. The polymer layer 40 may be implemented with a thermosetting polymer compound or a thermoplastic polymer compound, and specific types of the thermosetting polymer compound and the thermoplastic polymer compound may be known. As a non-limiting example of this, the thermosetting polymer compound may be one compound selected from the group consisting of epoxy-based, urethane-based, ester-based, and polyimide-based resins, or a mixture or copolymer of two or more. The thermoplastic polymer compound is polyamide, polyester, polyketone, liquid crystal polymer, polyolefin, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyphenylene oxide (PPO), polyether sulfone (PES), It may be one type of compound selected from the group consisting of polyetherimide (PEI) and polyimide, or a mixture or copolymer of two or more types. Alternatively, the polymer layer may be a rubber elastic body including natural rubber and/or synthetic rubber, or similar materials thereof.

The heat dissipating filler 101 having the above-described graphite composite can be prepared by preparing a graphite-nanoparticle assembly in which nanoparticles are formed on the graphite surface and forming a catecholamine layer on the graphite-nanoparticle assembly. And, it can be prepared by further performing the step of further forming a polymer layer after forming the catecholamine layer.

The step of preparing a graphite-nanoparticle conjugate in which nanoparticles are formed on the surface of graphite according to an embodiment of the present invention can be employed without limitation if it is a known method for forming nanoparticles on the surface of graphite, and is not limited thereto. As an example, existing gas-phase synthesis technologies for producing metal-based nanopowder include inert gas condensation (IGC), chemical vapor condensation (CVC), metal salt spray-drying, etc. method can be employed. However, among them, the inert gas condensation (IGC) process is capable of producing high-purity ultra-fine nanometal powder, but requires a lot of energy and has a very low production rate, which limits industrial applications. Chemical vapor condensation (CVC) The process is slightly improved in terms of energy or production rate compared to the inert gas condensation (IGC) process, but may be uneconomical because the price of precursors, which are raw materials, is very high. In addition, the metal salt spray drying process is economical because it uses cheap salt as a raw material, but it is disadvantageous in terms of environment because contamination and powder aggregation cannot be avoided in the drying step and toxic by-products are generated.

Accordingly, preferably, nanoparticles may be formed on the graphite through atmospheric pressure high-frequency thermal plasma. Specifically, through the steps of mixing graphite and nanoparticle-forming powder, injecting gas into the prepared mixture, vaporizing the nanoparticle-forming material through a high-frequency thermal plasma, and crystallizing the vaporized nanoparticle-forming material on the graphite surface. can be performed

Next, a gas can be injected into the mixed mixture. At this time, the injected gas can be classified into sheath gas, central gas, carrier gas, etc. according to its function, and these gases include inert gases such as argon, hydrogen, nitrogen or A mixture of these gases may be used, and argon gas may be preferably used. The sheath gas is injected to prevent vaporized nanoparticles from adhering to the inner surface of the wall and to protect the wall from ultra-high-temperature plasma, and 30 to 80 lpm (liters per minute) of argon gas may be used. In addition, the central gas is a gas injected to generate a high-temperature thermal plasma, and 30 to 70 lpm argon gas may be used. In addition, the carrier gas serves to supply the mixture into the plasma reactor, and 5 to 15 lpm of argon gas may be used.

Next, the nanoparticle-forming material may be vaporized through a high-frequency thermal plasma. The thermal plasma is an ionized gas composed of electrons, ions, atoms, and molecules generated from a plasma torch using a DC arc or high-frequency inductively coupled discharge, and is a high-speed jet with ultra-high temperature and high activity ranging from thousands to tens of thousands of K. . Accordingly, in order to smoothly generate high-temperature plasma, power of 10 to 70 kW is supplied to the power supply of the plasma device, an arc is formed by electric energy, and about 10,000 kW by argon gas used as a thermal plasma generating gas A super-high temperature plasma of K is generated. As described above, the ultra-high temperature thermal plasma generated by using argon gas as a generating gas while maintaining power of 10 to 70 kW has an effect of being generated at a higher temperature than thermal plasma generated by a heat treatment method or a combustion method. At this time, in the present invention, a known high-frequency thermal plasma (RF) method may be appropriately modified and used, and an existing thermal plasma treatment device may be used.

Next, a step of crystallizing the vaporized nanoparticle-forming material on the graphite surface may be performed. A quenching gas may be used to crystallize the vaporized nanoparticle-forming material on the graphite surface. At this time, crystallization may be performed while inhibiting the growth of nanoparticles by condensing or rapidly cooling with the quenching gas.

Forming a catecholamine layer on the graphite-nanoparticle conjugate prepared by the above method may be performed, and specifically, dipping the graphite-nanoparticle conjugate in a weakly basic dopamine aqueous solution; and forming a polydopamine layer on the surface of the graphite-nanoparticle conjugate.

First, the method for preparing the weakly basic dopamine aqueous solution is not particularly limited, but a tris buffer solution (10 mM, tris buffer solution) of pH 8 to 14, more preferably pH 8.5 basic Tris buffer solution, which is the same basic condition as the underwater environment. It may be prepared by dissolving dopamine in a buffer solution, and at this time, the dopamine concentration of the weakly basic dopamine aqueous solution may be 0.1 to 5 mg/ml, preferably 2 mg/ml.

After dipping the graphite-nanoparticle conjugate in the prepared weakly basic dopamine aqueous solution, dopamine spontaneously polymerizes under basic and oxidative conditions to form a catecholamine layer, which is a polydopamine layer, on the graphite-nanoparticle conjugate. At this time, an oxidizing agent may be further provided to form a polydopamine layer, and oxygen gas in the air may be used as an oxidizing agent without an oxidizing agent, and the present invention is not particularly limited thereto.

At this time, the dipping time determines the thickness of the polydopamine layer. In the case of using a dopamine aqueous solution having a pH of 8 to 14 and a dopamine concentration of 0.1 to 5 mg/ml, in order to form a catecholamine layer with a thickness of 5 to 100 nm, it is preferably about Dipping for 0.5 to 24 hours is preferred. Pure plate-like graphite hardly forms a dopamine coating layer on the graphite surface through this method, but a catecholamine layer may be formed on the nanoparticles due to the nanoparticles. On the other hand, dipping is exemplified as the above-described method for forming the polymer layer, but is not limited thereto, and blade coating, flow coating, casting, printing method, transfer method, brushing, or spraying A polymer layer may be further formed through a known method such as spraying.

On the other hand, in order to further provide a polymer layer to the graphite composite having a catecholamine layer, the graphite composite having a polymer layer may be prepared by mechanically mixing the graphite composite with a solution in which a desired polymer compound is dissolved or a molten liquid.

Next, the matrix forming component including the thermoplastic polymer compound may include a known thermoplastic polymer compound, and may be a material forming a body of a graphite-polymer composite to be described later. The thermoplastic polymer compound is preferably polyamide, polyester, polyketone, liquid crystal polymer, polyolefin, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyphenylene oxide (PPO), polyether sulfone ( PES), polyetherimide (PEI), and a compound selected from the group consisting of polyimide, or a mixture or copolymer of two or more kinds. The polyamide may be a known polyamide-based compound such as nylon 6, nylon 66, nylon 11, nylon 610, nylon 12, nylon 46, nylon 9T (PA-9T), keyana, and aramid.

For example, the polyester may be a known polyester compound such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), or polycarbonate.

As another example, the polyolefin may be a known polyolefin-based compound such as polyethylene, polypropylene, polystyrene, polyisobutylene, or ethylene vinyl alcohol.

The liquid crystal polymer may be used without limitation in the case of a polymer exhibiting liquid crystallinity in a solution or dissolved state, and may be a known type, so the present invention is not particularly limited thereto.

Next, additives containing the coupling agent will be described.

The coupling agent serves to improve interfacial adhesion between the graphite composite and the polymer compound.

On the other hand, since the above-described graphite composite is produced by firing at a high temperature, it is resistant to heat and has excellent elasticity compared to general carbon. In particular, the thermal conductivity (500 W / mL) of the graphite composite is superior to that of conventional silver (400 W / mL), copper (390 W / mL), and aluminum (230 W / mL), and in the longitudinal direction perpendicular to the conventional heat dissipation member In the heat transfer form, heat transfer in the transverse direction is possible according to the structural characteristics of graphite, so there is an advantage of very excellent heat dissipation characteristics. In addition, graphite is advantageous in lightweight screens due to its unique light weight and can respond to the recent trend of thinning, ultra-small and lightweight electronic products, so attempts to use it as a heat dissipation filler are continuing.

At this time, the graphite composite is mixed with a polymer compound that can be made into a molding to be implemented as a heat dissipating filler, and the carbon material such as the graphite composite is an organic / inorganic matrix Since agglomeration may occur, a study on dispersibility is needed.

In particular, the problem of interfacial adhesion between the graphite composite and the polymer compound directly affects physical properties such as the above-mentioned dispersibility, fluidity of the heat radiating filler in the polymer compound and bonding characteristics with the polymer compound, and thus, Since it can directly or indirectly affect heat dissipation performance and mechanical properties, improvement of interfacial adhesion between graphite composites and polymer compounds is a technical task that must be preceded in heat dissipation members implemented including graphite composites and polymer compounds. .

Accordingly, in order to improve interfacial adhesion, a method of modifying the surface of a graphite composite or a polymer matrix formed of a polymer compound has been introduced, but chemical/physical treatment called surface modification can affect the physical properties of the graphite composite as a heat dissipation filler, and further However, this may have an effect on the heat dissipation performance and mechanical properties of the realized heat dissipation member. In other words, while imparting excellent interfacial adhesion to the surface of the graphite composite or polymer matrix, it is uniformly dispersed in the polymer compound, so there is no degradation in heat dissipation performance and mechanical properties, and research on additives that can ensure chemical stability and durability is urgently needed. am.

Therefore, the composition for preparing a graphite-polymer composite according to the present invention includes a heat dissipating filler having the above-described graphite composite and a coupling agent as an additive, wherein the coupling agent is a silane coupling agent, maleic acid grafted polypropylene (MAH-g-PP ), maleic acid graft EPDM (MAH-g-EPDM), preferably maleic acid graft polypropylene (MAH-g-PP), maleic acid graft EPDM (MAH-g-EPDM). there is.

The maleic acid-grafted polypropylene (MAH-g-PP) may be represented by Formula 1 below.

[Formula 1]

The maleic acid-grafted polypropylene (MAH-g-PP) represented by Chemical Formula 1 can increase compatibility by forming a crosslinking point with the surface of the graphite composite by the polar group provided in maleic anhydride, thereby increasing the bonding force with the graphite composite and It serves to increase dispersibility. In addition, since the maleic acid-grafted polypropylene (MAH-g-PP) has a relatively low degree of unsaturation, it has excellent chemical resistance that is not denatured by oxidation or ozone, and has stable insulating properties even at high temperatures.

In addition, due to the hydrophobic nature of the polymerized propylene part, it has high compatibility with polymer resins, and has excellent insolubility and chemical resistance that do not react with other functional additives. Furthermore, there is an advantage in that injection moldability and reproducibility of the graphite-polymer composite material implemented with the polymer compound and the graphite composite can be ensured due to excellent injection properties.

In this case, the maleic acid-grafted polypropylene (MAH-g-PP) may have a predetermined weight average molecular weight. If the weight average molecular weight of the maleic acid-grafted polypropylene (MAH-g-PP) is excessively low, the content of the maleic acid-grafted polypropylene (MAH-g-PP) in the composition for preparing the graphite composite is insignificant, resulting in an interface Adhesive properties may not be expressed as desired.

In addition, maleic acid-grafted polypropylene (MAH-g-PP) may be included in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the thermoplastic polymer compound. If the maleic acid-grafted polypropylene (MAH-g-PP) is included in an amount of less than 0.1 parts by weight, the improvement in interfacial adhesion properties to be achieved through the maleic acid-grafted polypropylene (MAH-g-PP) may be insignificant, If the maleic acid-grafted polypropylene (MAH-g-PP) is implemented in excess of 30 parts by weight, the uniform dispersibility in the polymer compound may be lowered, thereby improving the heat dissipation performance and mechanical properties of the prepared graphite-polymer composite. It may cause deterioration of physical properties.

A coupling agent according to another embodiment of the present invention may be implemented as maleic acid graft EPDM (MAH-g-EPDM).

The EPDM (Ethylene-propylene-diene rubber) can be implemented by copolymerizing ethylene, propylene and diene, and the EPDM according to an embodiment of the present invention is an unsaturated carboxylic acid or its derivative (ester, acid anhydride, salt, acid halide, amide, imide, etc.) or other functional groups. In addition to maleic anhydride, the unsaturated carboxylic acid or its derivative includes acrylic acid, methacrylic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, norbornene dicarboxylic acid, ) Glycidyl acrylate, maleic acid ester, etc. can be used, and structures such as ester salts and metal salts thereof can also be borrowed. However, it is preferable to use acrylic acid, methacrylic acid and maleic anhydride as the unsaturated carboxylic acid or its derivative, and it is most preferable to use maleic anhydride.

At this time, the modification of EPDM through an unsaturated carboxylic acid or a derivative thereof can be performed by heating and mixing in the presence of a graft polymerization initiator, and the diene in EPDM used as a raw material is 5-ethylidene-2-norbornene, Dicyclopentadiene, 1,4-hexadiene and the like can be used.

Similar to the above-mentioned maleic acid-grafted polypropylene (MAH-g-PP), the maleic anhydride-grafted EPDM can increase compatibility by forming a cross-linking point with the surface of the graphite composite by the polar group provided in maleic anhydride. It serves to increase the bonding strength and dispersibility with the graphite composite. In addition, it has excellent chemical resistance, insulation properties, injection moldability and reproducibility similar to the above-mentioned maleic acid grafted polypropylene (MAH-g-PP).

In this case, the maleic anhydride-grafted EPDM may be included in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the thermoplastic polymer compound. If the maleic anhydride-grafted EPDM is included in less than 0.1 part by weight based on 100 parts by weight of the thermoplastic polymer compound, the desired interfacial adhesion and dispersibility may not be improved, and if the maleic anhydride-grafted EPDM When EPDM is included in an amount of more than 30 parts by weight based on 100 parts by weight of the thermoplastic polymer compound, uniform dispersibility in the polymer compound may be deteriorated, which causes the heat dissipation performance and mechanical properties of the prepared graphite-polymer composite to deteriorate This can be.

In addition, the maleic anhydride-grafted EPDM has a copolymerization weight ratio of ethylene, propylene, and diene, while maintaining the above-described impact resistance of the maleic anhydride-grafted EPDM, and graphite-manufactured through a composition for preparing a graphite-polymer composite containing the same. It is not particularly limited in that it may be appropriately selected to the extent that the mechanical properties and heat dissipation performance of the polymer composite are not deteriorated.

In addition, the composition for preparing a graphite-polymer composite according to an embodiment of the present invention includes, as an additive, an impact improver, a flame retardant, a strength improver, an antioxidant, a heat stabilizer, a light stabilizer, a plasticizer, an antistatic agent, a work improver, a UV absorber, and a dispersant. It may be implemented by further including one or more additives selected from the group consisting of.

The impact modifier can be used without limitation in the case of a known component capable of improving impact resistance by expressing flexibility and stress relaxation of a composite material between graphite and a polymer compound, for example, thermoplastic polyurethane (TPU), thermoplastic polyolefin (TPO), maleic acid grafted EPDM, core/shell structured elastic particles, and rubber-based resin may be provided as an impact modifier. The thermoplastic polyolefin is a group of materials similar to rubber, and is a linear polyolefin block copolymer having a polyolefin block and a rubbery block such as polypropylene or polyethylene, or a blend of polypropylene with an ethylene-based elastomer, ethylene-propylene-diene monomer (EPDM) And, since known thermoplastic polyolefins can be used, the description of specific types thereof is omitted in the present invention. In addition, since known thermoplastic polyurethanes can also be used, descriptions of specific types are omitted. In addition, for the core/shell structured elastic particle, for example, an allyl-based resin may be used for the core, and the shell portion is a polymer having a functional group capable of reacting to increase compatibility and bonding force with a thermoplastic polymer compound. It may be resin.

Such flame retardants include, for example, halogenated flame retardants, like tretabromo bisphenol A oligomers such as BC58 and BC52, brominated polystyrene or poly(dibromo-styrene), brominated epoxies, decabromo Modiphenylene oxide, pentabromobenzyl acrylate monomer, pentabromobenzyl acrylate polymer, ethylene-bis(tetrabromophthalimide, bis(pentabromobenzyl)ethane, Mg(OH) ₂ and Al(OH) Metal hydroxides such as ₃ , melamine cyanurate, phosphor-based FR systems such as red phosphorus, melamine polyphosphates, phosphate esters, metal phosphinates, ammonium polyphosphates, expandable graphite, sodium or potassium perfluorobutane sulfate, sodium or potassium perfluorooctane sulfate, sodium or potassium diphenylsulfonesulfonate and sodium- or potassium-2,4,6,-trichlorobenzoate and N-(p-tolylsulfonate The flame retardant includes, but is not limited to, phonyl)-p-toluenesulfimide potassium salt, N-(N'-benzylaminocarbonyl) sulfanylimide potassium salt, or mixtures thereof. It may be included in an amount of 0.1 to 30 parts by weight based on parts by weight.

The strength improving agent may be used without limitation in the case of a known component capable of improving the strength of a composite material between graphite and a polymer compound, and as non-limiting examples thereof, carbon fiber, glass fiber, glass beads, zirconium oxide, wool With stonyte, gibbsite, boehmite, magnesium aluminate, dolomite, calcium carbonate, magnesium carbonate, mica, talc, silicon carbide, kaolin, calcium sulfate, barium sulfate, silicon dioxide, ammonium hydroxide, magnesium hydroxide and aluminum hydroxide One or more components selected from the group consisting of may be included as a strength improver. The strength improving agent may be included in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the graphite composition, but is not limited thereto. For example, when glass fibers are used as the strength improver, the glass fibers may have a diameter of 2 to 8 mm.

The antioxidant is provided to prevent breaking of the main chain of the thermoplastic polymer compound due to shear during extrusion and injection, and to prevent thermal discoloration. As the antioxidant, known antioxidants may be used without limitation, and as non-limiting examples thereof, tris (nonyl phenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, bis (2 organophosphites such as ,4-di-t-butylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite or the like; alkylated monophenols or polyphenols; alkylated reaction products of polyphenols with dienes, such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane, or the like; butylated reaction products of para-cresol or dicyclopentadiene; alkylated hydroquinones; hydroxylated thiodiphenyl ether; alkylidene-bisphenol; benzyl compounds; esters of monohydric or polyhydric alcohols with beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid; esters of monohydric or polyhydric alcohols with beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid; Distearylthiopropionate, dilaurylthiopropionate, ditridecylthiopropionate, octadecyl-3-(3,5-di-tert-butyl-l-4-hydroxyphenyl)propionate , esters of thioalkyl or thioaryl compounds such as pentaerythrityl-tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or the like; amides of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid or the like, or mixtures thereof. The antioxidant may be provided in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the thermoplastic polymer compound.

In addition, the heat stabilizer may be used without limitation in the case of known heat stabilizers, but as non-limiting examples thereof, triphenyl phosphite, tris-(2,6-dimethylphenyl) phosphite, tris-(mixed mono- organic phosphites such as tris-(mixed mono-and di-nonylphenyl)phosphate or the like; phosphonates such as dimethylbenzene phosphonate or the like, phosphates such as trimethyl phosphate, or the like, or mixtures thereof. The heat stabilizer may be included in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the thermoplastic polymer compound.

In addition, the light stabilizer may be used without limitation in the case of known light stabilizers, but as non-limiting examples thereof, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5 benzotriazoles such as -tert-octylphenyl)-benzotriazole and 2-hydroxy-4-n-octoxy benzophenone or the like or mixtures thereof. Light stabilizers can generally be included at 0.1 to 1.0 parts by weight based on 100 parts by weight of the total composition excluding any fillers.

In addition, the plasticizer may be used without limitation in the case of known plasticizers, but as non-limiting examples thereof, dioctyl-4,5-epoxy-hexahydrophthalate, tris-(octoxycarbonylethyl) isocyanurate, phthalic acid esters such as tristearin, epoxidized soybean oil or the like, or mixtures thereof. The plasticizer may be included in an amount of 0.5 to 3.0 parts by weight based on 100 parts by weight of the thermoplastic polymer compound.

In addition, as the antistatic agent, known antistatic agents may be used without limitation, and as non-limiting examples thereof, glycerol monostearate, sodium stearyl sulfonate, sodium dodecylbenzenesulfonate, polyether block amides, or mixtures thereof, including, for example, BASF under the tradename Irgastat; Arkema under the trade name PEBAX; and from Sanyo Chemical industries under the trade name Pelestat. The antistatic agent may be included in an amount of 0.1 to 1.0 parts by weight based on 100 parts by weight of the thermoplastic polymer compound.

In addition, the work improver may use a known work improver without limitation, and as non-limiting examples thereof, metal stearate, stearyl stearate, pentaerythritol tetrastearate, beeswax, montan wax (montan wax), paraffin wax, polyethylene wax or the like or mixtures thereof. The work improver may be included in an amount of 0.1 to 1.0 parts by weight based on 100 parts by weight of the thermoplastic polymer compound.

In addition, as the UV absorber, known UV absorbers may be used without limitation, and non-limiting examples thereof include hydroxybenzophenone; hydroxybenzotriazole; hydroxybenzotriazine; cyanoacrylate; oxanilides; benzoxazinones; 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3,-tetramethylbutyl)-phenol; 2-hydroxy-4-n-octyloxybenzophenone; 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phenol; 2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one); 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-biphenylacryloyl)oxy] methyl]propane; 2,2'-(1,4-phenylene) bis(4H-3,1-benzoxazin-4-one); 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy] methyl]propane; nano-sized inorganic materials such as titanium oxide, cerium oxide and zinc oxide having a particle size of less than 100 nm; or the like, or mixtures thereof. The UV absorber may be included in an amount of 0.01 to 3.0 parts by weight based on 100 parts by weight of the thermoplastic polymer compound.

In addition, known dispersants and coupling agents may be used without limitation as the dispersing agent and coupling agent, and maleic acid-grafted polypropylene, silane-based coupling agents, and the like may be used for heat resistance as non-limiting examples of the coupling agent.

Meanwhile, according to an embodiment of the present invention, the above-described composition for preparing a graphite-polymer composite material is implemented as a masterbatch for preparing a graphite composite material together with a thermoplastic polymer compound.

Next, a graphite-polymer composite according to an embodiment of the present invention will be described.

As shown in FIG. 2, the graphite-polymer composite 1000 is implemented with a polymer matrix 200 and a heat radiation filler 101 and a coupling agent 102 according to the present invention dispersed inside the polymer matrix 200 And, a protective coating layer 300 may be further provided on the outer surface of the polymer matrix 200. Although the coupling agent 102 is shown in an elliptical shape, it may vary depending on the weight average molecular weight or polymer type of the coupling agent 102 used, and is schematically shown due to the difficulty of accurately measuring it with a measuring device, so its shape is It is not limited.

The heat dissipating filler 101 and the coupling agent 102 are shown as being dispersed only inside the polymer matrix 200 in FIG. 2 , but may be disposed to be exposed to the outer surface differently from FIG. 2 .

The heat dissipating filler 101 may be provided in an amount of 10 to 90% by weight based on the total weight of the graphite-polymer composite 1000. If the amount of the heat dissipating filler 101 is less than 10% by weight, the desired heat dissipation and shielding performance may not be exhibited. In addition, if it is provided in excess of 80% by weight, the mechanical strength of the composite material is significantly lowered, moldability such as injection is lowered, and it may be difficult to implement it into a complex shape.

The polymer matrix 200 is formed of the above-described thermoplastic polymer compound, and detailed descriptions are the same as those described above and will be omitted.

A protective coating layer 300 may be further provided on the outer surface of the polymer matrix 200 . The protective coating layer 300 prevents the escape of the heat dissipating filler 101 located on the surface of the polymer matrix, prevents scratches due to physical stimuli applied to the surface, and provides an insulating function depending on the material to insulate and dissipate heat At the same time, it can be used for applications such as electronic devices that are required.

The protective coating layer 300 may be implemented with a known thermosetting polymer compound or thermoplastic polymer compound. The thermosetting polymer compound may be one compound selected from the group consisting of epoxy-based, urethane-based, ester-based, and polyimide-based resins, or a mixture or copolymer of two or more kinds. In addition, the thermoplastic polymer compound is polyamide, polyester, polyketone, liquid crystal polymer, polyolefin, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyphenylene oxide (PPO), polyether sulfone (PES) ), one compound selected from the group consisting of polyetherimide (PEI) and polyimide, or a mixture or copolymer of two or more, but is not limited thereto.

The protective coating layer 300 may have a thickness of 0.1 to 1000 μm, but is not limited thereto, and may be implemented by changing according to the purpose.

On the other hand, the protective coating layer 300 may prevent the radiation of the conducted heat into the air. Accordingly, in order to exhibit improved heat dissipation, in particular heat radiation into the outside air, the protective coating layer 300 may be a heat dissipating coating layer further provided with a heat dissipating filler. The heat radiating filler may be used without limitation in the case of a known heat radiating filler. If insulation is required at the same time, at least one insulating heat radiating filler selected from the group consisting of aluminum oxide, boron nitride, talc, magnesium oxide, silicon carbide, etc. It is desirable to provide

Since the type, particle size, content, etc. of the heat dissipating filler provided in the protective coating layer 400 may be designed differently according to the purpose, the present invention is not particularly limited thereto.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention may add elements within the scope of the same spirit. However, other embodiments can be easily proposed by means of changes, deletions, additions, etc., but these will also fall within the scope of the present invention.

101: heat radiation filler having a graphite composite
102: coupling agent
200: polymer matrix 300: protective coating layer

Claims (13)

A heat dissipating filler comprising nanoparticles having an average particle diameter of 50 to 600 μm bonded to a surface of graphite, a catecholamine layer provided on at least the surface of the nanoparticles, and a graphite composite including a polymer layer coated on the catecholamine layer;
A matrix forming component containing a thermoplastic polymer compound; and
An additive containing a maleic acid-grafted polypropylene (MAH-g-PP) and a maleic acid-grafted EPDM (MAH-g-EPDM) coupling agent contained in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the thermoplastic polymer compound; A master batch for preparing a graphite-polymer composite comprising a molded composition for preparing a graphite-polymer composite. delete delete delete delete delete Nanoparticles having an average particle diameter of 50 to 600 μm bonded to the surface of graphite, a catecholamine layer provided on at least the surface of the nanoparticles, and a graphite composite including a polymer layer coated on the catecholamine layer Heat dissipation filler having; An additive containing a maleic acid-grafted polypropylene (MAH-g-PP) and a maleic acid-grafted EPDM (MAH-g-EPDM) coupling agent contained in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the thermoplastic polymer compound; and
a polymer matrix formed of a thermoplastic polymer compound and having the heat dissipating filler and additives dispersed therein; A graphite-polymer composite comprising a. According to claim 7,
The heat-dissipating filler is a graphite-polymer composite containing 10 to 90% by weight of the total weight of the graphite-polymer composite. According to claim 7,
A graphite-polymer composite wherein a protective coating layer is further provided on the outer surface of the polymer matrix. delete delete delete delete

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