Patent Application
20150275061
The present invention relates to a heat dissipation paint composition and a heat dissipation structure. More specifically, the present invention relates to a heat dissipation paint composition capable of forming a heat dissipation layer having excellent salt water resistance, coating film strength, adherence property, scratch resistance, or the like, together with excellent heat dissipation property, in various products, and a heat dissipation structure.
Recently, as a light emitting diode (LED) head lamp is increasingly applied to an automobile, or the like, a technical effort to decrease a temperature of the lamp has been conducted. In particular, an LED device is a semiconductor device which is significantly sensitive to a temperature, and problems such as decrease in lifespan and malfunction by an increase in a temperature during operation may occur seriously. Therefore, it is significantly required to suppress the increase in a temperature of the LED head lamp, and the like, to extend the lifespan, and to suppress malfunction.
Up to now, in order to suppress the increase in the temperature of the LED head lamp, and the like, heat dissipation property is realized through a fan between the lamp and a bracket in most cases. However, in the heat dissipation structure, the fan has a shorter lifespan than that of the lamp, and noise, dust, and frequent failure occur, such that the high-priced LED head lamp needs to be frequently replaced.
Accordingly, development in technology of extending the lifespan of the lamp by appropriately radiating heat generated around the LED head lamp, and the like, to suppress the increase in the temperature without using a mechanical structure such as a fan, or the like, has been continuously demanded.
Recently, in order to obtain the above-described effect, an effort of forming a heat dissipation structure such as a heat dissipation layer, or the like, by using a heat dissipation paint composition around the LED head lamp, and the like, has been attempted. However, the heat dissipation paint composition capable of forming the heat dissipation layer having excellent salt water resistance, coating film strength, adherence property, scratch resistance, or the like, together with excellent heat dissipation property so as to preferably realize the effect, has not been achieved properly yet.
The present invention has been made in an effort to provide a heat dissipation paint composition capable of forming a heat dissipation layer having excellent salt water resistance, coating film strength, adherence property, scratch resistance, or the like, together with excellent heat dissipation property, in various products such as a light emitting diode (LED) head lamp, and the like.
The present invention has also been made in an effort to provide a heat dissipation structure such as a heat dissipation layer, or the like, having excellent salt water resistance, coating film strength, adherence property, scratch resistance, or the like, together with excellent heat dissipation property, obtained from the heat dissipation paint composition.
An exemplary embodiment of the present invention provides a heat dissipation paint composition including: an epoxy resin; a curing agent; a carbon-based filler having a functional group including at least one selected from the group consisting of an amine group, an amide group, a carboxyl group and a hydroxyl group bound thereto; and a solvent.
Another embodiment of the present invention provides a heat dissipation structure including: an epoxy resin cured material having a cross-linked structure by a ring-opened epoxy group; and a carbon-based filler having a functional group including at least one selected from the group consisting of an amine group, an amide group, a carboxyl group and a hydroxyl group bound thereto.
Hereinafter, the heat dissipation paint composition and the heat dissipation structure according to an exemplary embodiment of the present invention will be described.
According to an exemplary embodiment of the present invention, the heat dissipation paint composition including: an epoxy resin; a curing agent; a carbon-based filler having a functional group including at least one selected from the group consisting of an amine group, an amide group, a carboxyl group and a hydroxyl group bound thereto; and a solvent is provided.
The heat dissipation paint composition may include the epoxy resin having at least one epoxy group at an end thereof, or the like; the curing agent; and the carbon-based filler having a specific functional group bound onto a surface, the specific functional group being capable of forming a hydrogen bond. If the heat dissipation paint composition is applied around products requiring heat radiation, such as an LED head lamp, and the like, and then is cured, the epoxy group in the epoxy resin may be ring-opened and interact with the curing agent to thereby form a cross-linked structure of the epoxy groups as shown in Reaction Formula 1 below. Therefore, the epoxy resin cured material and the heat dissipation structure such as the heat dissipation layer including the same, may be provided.
In particular, in the epoxy resin cured material having the heat dissipation structure, the carbon-based filler having the specific functional group bound onto the surface may be uniformly dispersed, and it may be considered that a hydrogen bond may be formed between the specific functional group of the carbon-based filler and oxygen derived from the epoxy group and included in a cross-linked structure. A chemical bonding structure in which the hydrogen bonds are formed is schematically represented by Reaction Formula 2 below:
Due to the interaction between the carbon-based filler and the epoxy resin such as the formation of hydrogen bonds, in the heat dissipation structure such as the heat dissipation layer, or the like, the carbon-based filler may show more excellent compatibility with the epoxy resin and cured materials thereof, and may be more uniformly dispersed in the heat dissipation structure to provide excellent and uniform effects.
As a result, the heat dissipation structure obtained from the heat dissipation paint composition according to an exemplary embodiment may exhibit more excellent effects due to the carbon-based filler which is material having thermal conductivity and heat dissipation property to provide excellent heat dissipation property, and the heat dissipation structure such as the heat dissipation layer, or the like, may show improved general physical properties such as excellent salt water resistance, coating film strength, adherence property on a substrate, scratch resistance, hardness, and the like, due to excellent compatibility, and the like, between the epoxy resin and the carbon-based filler.
Therefore, by using the heat dissipation paint composition according to an exemplary embodiment of the present invention, heat generated from the light emitting diode (LED) head lamp effectively radiates without disposing mechanical heat dissipation structures such as a fan, and the like, around the LED head lamp, such that an increase in temperature may be suppressed, and as a result, the LED head lamp may have an improved lifespan. In addition, the heat dissipation paint composition according to an exemplary embodiment of the present invention may be used to provide the heat dissipation structure such as the heat dissipation layer having excellent heat dissipation property and other general physical properties in condensers, evaporators, engines, heaters, boiler pipes, communication equipments, motors, batteries, housing materials, electrode materials, semiconductor, game machines, displays such as OLED devices, mobile phones, home appliances, automobiles, construction, medical equipments, ship, airplane, aerospace equipment, military facilities and equipments, heat exchangers, or the like.
Meanwhile, in the heat dissipation paint composition according to the exemplary embodiment of the present invention, various curing agent components which are possible to cure the epoxy resin may be used as the curing agent. For example, imidazole-based curing agent may be used.
In addition, in the heat dissipation paint composition, the carbon-based filler may be any carbon-based fillers which have been known to exhibit heat dissipation property, thermal conductivity, and the like, for example, at least one selected from the group consisting of a single wall carbon nanotube, a double wall carbon nanotube, a multi-wall carbon nanotube, graphene, graphene oxide, a graphene nano plate, graphite, carbon black, and a carbon-metal complex. Further, the functional group bound to the carbon-based filler may be any functional groups including an amine group, an amide group, a carboxyl group or a hydroxyl group in a structure, the functional group may be bound directly or via a linker such as C1 to C20 alkylene, or the like, onto the surface of the carbon-based filler.
For example, the carbon-based filler having the functional group bound thereto may have a chemical structure represented by Chemical Formula 1 below:
in Chemical Formula 1,
R1 is at least one functional group bound to the carbon-based filler, is the same as each other or different from each other, and is selected from the group consisting of —R2—NHR3, —R2—C(═O)—NHR3, —R2—C(═O)—OH, —R2—OH, and —R2—NH—C(═O)R3,
R2 is the same as each other or different from each other, and is a single bond or C1 to C20 alkylene, and
R3 is the same as each other or different from each other, and is hydrogen or C1 to C20 alkyl.
As the carbon-based filler has the above-described structure, the heat dissipation structure formed from the heat dissipation paint composition according to the exemplary embodiment of the present invention may show more excellent heat dissipation property and compatibility to significantly improve physical properties thereof.
Meanwhile, in the heat dissipation paint composition according to the exemplary embodiment of the present invention, any solvents which are possible to appropriately dissolve each component may be used as the solvent. For example, the solvent may include at least one selected from the group consisting of a water-based solvent such as water, an alcohol-based solvent, a ketone-based solvent, an amine-based solvent, an ester-based solvent, an amide-based solvent, a halogenated hydrocarbon-based solvent, an ether-based solvent, and a furan-based solvent.
In addition, the heat dissipation paint composition may include the epoxy resin in an amount of 5 to 50 wt %; the curing agent in an amount of 0.1 to 20 wt %; the carbon-based filler having a functional group including at least one selected from the group consisting of an amine group, an amide group, a carboxyl group and a hydroxyl group bound thereto in an amount of 0.05 to 5 wt %; and the solvent in a residual amount, and within the range of these amounts, a property in which the composition is applied, the compatibility between the epoxy resin and the carbon-based filler, and the heat dissipation property by the carbon-based filler may be optimized, such that the heat dissipation structure formed by the composition may have more excellent properties.
Further, the composition according to an exemplary embodiment of the present invention may further include: general additives, for example, at least one additive selected from the group consisting of a dispersant, a leveling agent, a dispersion stabilizer, a pH adjusting agent, an anti-precipitation agent, a surfactant, a wetting agent, and a thickener, in addition to each above-described component.
As the dispersant among the additives, all of any dispersants which have been known to be usable to paint compositions or resin compositions including the carbon-based filler, and the like, may be used without specific limitation. Representative examples of the dispersant may include: a modified acrylate-based dispersant; a modified polyurethane acrylic copolymer dispersant; a polyacetal-based dispersant; an acrylic dispersant such as an acrylic add, methyl methacrylate, alkyl(C1 to C10)acrylate, vinyl acrylate or 2-ethylhexyl acrylate; a polycarbonate-based dispersant; a styrene-based dispersant such as styrene or alpha methyl styrene; a polyester-based dispersant; a polyphenylene ether-based dispersant; a polyolefin-based dispersant; an acrylonitrile-butadiene-styrene copolymer dispersant; a polyarylate-based dispersant; a polyamide-based dispersant; a polyamide imide-based dispersant; a polyaryl sulfone-based dispersant; a polyether imide-based dispersant; a polyether sulfone-based dispersant; a polyphenylene sulfide-based dispersant; a polyimide-based dispersant; a polyether ketone-based dispersant; a poly benzoxazol-based dispersant; a poly oxadiazole-based dispersant; a poly benzothiazole-based dispersant; a poly benzimidazole-based dispersant; a polypyridine-based dispersant; a polytriazole-based dispersant; a polypyrrolidine-based dispersant; a poly dibenzofuran-based dispersant; a polysulfone-based dispersant; a polyurea-based dispersant; a polyurethane-based dispersant; a polyphosphazene-based dispersant; and the like, and a mixture containing two or more selected therefrom or a copolymer thereof may also be used.
In addition, as the leveling agent, known additives such as BYK series may be typically used, and various other leveling agents may be used. Further, as the dispersion stabilizer, an anionic surfactant, a cationic surfactant, a non-ionic surfactant, a wetting agent, a wetting-improving agent, or the like, may be used, and any known additives which are possible to stabilize dispersibility of the carbon-based filler, and the like, of other resin compositions or paint compositions may be used. All additives which are known in the art or which are commercially available may be used as each additive.
The above-described heat dissipation paint composition according to the exemplary embodiment of the present invention may be applied to any substrates such as a metal substrate such as an aluminum (Al) heat sink, a plastic substrate, a fiber substrate, or the like, with high adherence property, and may be applied to provide the heat dissipation structure such as the heat dissipation layer having excellent heat dissipation property and other general physical properties in condensers, evaporators, engines, heaters, boiler pipes, communication equipments, motors, batteries, housing materials, electrode materials, semiconductor, game machines, displays such as OLED devices, mobile phones, home appliances, automobiles, construction, medical equipments, ship, airplane, aerospace equipment, military facilities and equipments, heat exchangers, or the like, as well as the device such as LED head lamp, or the like as described above.
Meanwhile, according to another exemplary embodiment of the present invention, there is provided the heat dissipation structure formed from the above-described heat dissipation paint composition. The heat dissipation structure may include: an epoxy resin cured material having a cross-linked structure by a ring-opened epoxy group; and a carbon-based filler having a functional group including at least one selected from the group consisting of an amine group, an amide group, a carboxyl group and a hydroxyl group bound thereto. In the heat dissipation structure, the carbon-based filler may be more uniformly dispersed in the epoxy resin cured material, and in particular, due to excellent compatibility with the epoxy resin cured material, the carbon-based filler may be more uniformly dispersed to provide excellent properties. Therefore, the heat dissipation structure may have not only excellent heat dissipation property, but also improved general physical properties such as excellent salt water resistance, coating film strength, adherence property on a substrate, scratch resistance, hardness, and the like, due to excellent compatibility, and the like. It may be considered that these excellent properties are obtained due to the interaction between the functional groups bound to the carbon-based filler and oxygen derived from the epoxy group in the epoxy resin cured material through the hydrogen bonds, or the like.
The heat dissipation structure may be applied to various products such as condensers, evaporators, engines, heaters, boiler pipes, communication equipments, motors, batteries, housing materials, electrode materials, semiconductor, game machines, displays such as OLED devices, mobile phones, home appliances, automobiles, construction, medical equipment, ship, airplane, aerospace equipment, military facilities and equipment, heat exchangers, or the like, as well as the device such as LED head lamp, or the like as described above, and may show excellent heat dissipation property and other general physical properties, and may be the heat dissipation layer, and the like, formed from the above-described heat dissipation paint composition according to the exemplary embodiment of the present invention.
According to the present invention, it is possible to provide the heat dissipation paint composition capable of providing a heat dissipation structure having improved general physical properties such as excellent salt water resistance, coating film strength, adherence property on a substrate, scratch resistance, hardness, and the like, together with excellent heat dissipation property.
Therefore, by using the heat dissipation paint composition, heat generated from the light emitting diode (LED) head lamp effectively radiates without disposing mechanical heat dissipation structures such as a fan, and the like, around the LED head lamp, such that an increase in temperature may be suppressed, and therefore, the LED head lamp may have an improved lifespan.
In addition, the heat dissipation paint composition according to the present invention may be used to provide the heat dissipation structure such as a heat dissipation layer having excellent heat dissipation property and other general physical properties in condensers, evaporators, engines, heaters, boiler pipes, communication equipments, motors, batteries, housing materials, electrode materials, semiconductor, game machines, displays such as OLED devices, mobile phones, home appliances, automobiles, construction, medical equipments, ship, airplane, aerospace equipment, military facilities and equipments, heat exchangers, or the like.
Hereinafter, preferably exemplary embodiments are described in order to help the understanding of the present invention. These embodiments are provided by way of example only, and the scope of the present invention is not limited thereto.
A CNT solution was prepared by mixing 10 g of multi-wall carbon nanotube (CNT) with 990 g of distilled water. Before the CNT solution was injected into a pre-heater at a flow rate of 30 g/min, oxygen in a gas phase which was compressed to 245 atm to 252 atm was mixed with the CNT solution at a flow rate of 0.8 g/min to obtain a mixed solution, and then the mixed solution was injected into a pre-heater which was pre-heated to 200 to 260° C.
The pre-heated mixed solution was injected into a reactor for surface treatment at a temperature of 350° C. under subcritical condition at 230 atm to 250 atm to be surface treated. Ammonia water was high-pressure injected at a flow rate of 0.20 g/min under a pressure of 230 to 250 atm and at a temperature of 300 to 350° C. at a point of 4/5 from an entrance of the reactor for surface treatment during the surface-treatment reaction. The surface-treated product was primarily cooled to 200° C. again, and cooled to about 25° C. again to obtain 9.8 g of a continuously surface-treated product.
A CNT dispersion solution was prepared by mixing and dispersing 30 g of the functionalized CNT which was prepared by the same method as Preparation Example 1 above, 90 g of a modified polyacrylate-based dispersant with 880 g of a mixed solution of methyl ethyl ketone (MEK) and 1-propanol.
46 g of an epoxy resin (Kukdo Chemical Co., Ltd., YD 128), 0.2 g of a leveling agent, 11.6 g of MEK, and 14.6 g of 1-propanol were mixed with each other for 10 mins to obtain a mixed solution. 23 g of the CNT dispersion solution of Preparation Example 2 was mixed with the mixed solution, followed by blending. Then, 4.6 g of 2-ethyl-4-methylimidazole was mixed with the mixed solution, followed by blending for 10 mins again, to thereby prepare a heat dissipation paint composition. Final compositions of the prepared heat dissipation paint composition were shown in Table 1 below.
The heat dissipation paint composition of Preparation Example 3 was used as a composition of Example 1, and the composition was coated on a non-surface treated aluminum specimen having a size of width*length*thickness of 70*70*1 so as to have a thickness of 10 μm. A curing process was performed in an oven at 130° C. for 30 mins.
In addition, the aluminum specimen coated with the CNT heat dissipation paint composition was mounted on equipments for measuring a heat dissipation effect. The equipments were schematically shown in
A dispersion solution of Example 2 was prepared by the same method as Preparation Example 2 above, except for adding 90 g of a modified polyurethane-based dispersant instead of the modified polyacrylate-based dispersant as a dispersion aid, and a heat dissipation paint composition of Example 2 was prepared by the same method as Preparation Example 3.
The heat dissipation effect of the heat dissipation paint composition of Example 2 was evaluated by observing change in temperatures in the heat dissipation paint composition of Example 2 by the same method as Example 1.
The heat dissipation effect was evaluated by measuring change in temperatures by the same method as Example 1, except for using a non-coated (bare) aluminum specimen.
46 g of an epoxy resin, 0.2 g of a leveling agent, 12.6 g of MEK, and 15.9 g of 1-propanol were mixed with each other, and mixed for 10 mins. 23 g of a non-functionalized CNT dispersion solution was mixed with the mixed solution, followed by blending, and 2.3 g of 2-ethyl-4-methylimidazole was added thereto and mixed again for 10 mins. Then, a heat dissipation paint composition of Comparative Example 2 was prepared by the same method as Preparation Example 3.
The heat dissipation effect of the prepared heat dissipation paint composition of Comparative Example 2 was evaluated by observing change in temperatures in the heat dissipation paint composition of Comparative Example 2 by the same method as Example 1.
A dispersion solution was prepared by adding 90 g of a modified polyacrylate-based dispersant and 4 g of 2,5,8,11-tetramethyl-6-dodecyn-5,8-diol ethoxylate which was a non-ionic fluorinated additive as a dispersion stabilizer to 30 g of the functionalized CNT which was prepared by the same method as Preparation Example 1, followed by mixing with 876 g of distilled water.
A heat dissipation paint composition of Comparative Example 3 was prepared by mixing 50.0 g of the CNT dispersion solution, 2.0 g of a 3-aminopropyltriethoxysilane-based binder, 13.3 g of a silane-based leveling agent, and 34.7 g of distilled water.
The heat dissipation effect of the heat dissipation paint composition of Comparative Example 3 was evaluated by observing change in temperatures in the heat dissipation paint composition of Comparative Example 3 by the same method as Example 1.
A CNT dispersion solution of Comparative Example 4 was prepared by the same method as Comparative Example 3, and a heat dissipation paint composition of Comparative Example 4 was prepared by mixing 66 g of the CNT dispersion solution with 24 g of a mixed solution of a water-based modified acrylic urethane-based binder and a copolymerized urethane binder, 8 g of a silicon-based binder, 0.1 g of a silane-based leveling agent, and 1.9 g of isopropyl alcohol.
The heat dissipation effect of the heat dissipation paint composition of Comparative Example 4 was evaluated by observing change in temperatures in the heat dissipation paint composition of Comparative Example 4 by the same method as Example 1.
Graphs regarding the heat dissipation properties measured in Examples 1 and 2 and Comparative Example 1 were shown in
Meanwhile, paint stability and surface properties of the coating films, adherence property (JIS D0202; <M2.5), salt water resistance (240 hr, about 30° C., 5% salt water concentration; ASTM B117), pencil hardness, and scratch resistance (ASTM D 3363-92a) of the heat dissipation layer were evaluated in specimens obtained from Examples 1 and 2, and Comparative Examples 1 and 2, respectively. The evaluation results on surface properties of the coating films and the salt water resistance of Examples 1 and 2, and Comparative Example 2 were compared with each other and shown in
Surface properties, adherence property, and salt water resistance were evaluated by the following evaluation standards, and the results were shown in Tables 2 and 3 below.
* Evaluation Standard
Surface Properties: Evaluation with unaided eye (determined by visual inspection using images such as
Adherence property: Adherent properties were classified into six stages from 5B indicating excellent adherence property to 0B indicating poor adherence property, according to ASTM D 3359, and determined on the basis of quantitative inspection, and the results were shown in Table 2, and the like.
Salt water resistance: A degree in which a coated surface was salified at a specific time was evaluated with unaided eye and determined according to ASTM standard (determined by visual inspection using images such as
Referring to Tables 2 and 3, and
Meanwhile, the comparison results in view of the heat dissipation property measured in Example 2 and Comparative Examples 3 and 4 were shown in Table 4 below. In addition, the comparison results in view of the paint stability and the surface properties, and the adherence property (JIS D0202; <M2.5), salt water resistance (240 hr, about 30° C., 5% salt water concentration; ASTM B117), pencil hardness, and scratch resistance (ASTM D 3363-92a) of the heat dissipation layer were shown in Table 4 below, and the evaluation results on the coating film surface properties and salt water resistance of Example 2, and Comparative Examples 3 and 4 were compared with each other and the comparison results were shown in
It was confirmed that the Example 2, and Comparative Examples 3 and 4 had similar heat dissipation effect to each other; however, the salt water resistance was obtained in Example 2 only.
Lastly, heat dissipation performance was confirmed by applying the heat dissipation paint composition of Example 2 to various heat sink structures. More specifically, in the heat sink structure shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2012-0109475 | Sep 2012 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2013/008491 | 9/23/2013 | WO | 00 |
