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Patent Application Titled "Heat-Conducting and Heat-Dissipating Nano-Materials, Preparing Method Thereof and Heat-Dissipating System" Published Online

June 26, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors Juy, King Sun (Kowloon, HK); Hui, Man Wah (Kowloon, HK), filed on June 10, 2011, was made available online on June 12, 2014.

The assignee for this patent application is Green Formula Limited.

Reporters obtained the following quote from the background information supplied by the inventors: "Light emitting diode (LED) has a great potential of development among solid light sources, and receives increasing attention from people by virtue of its advantages of long lifespan, firm structure, low energy consumption and flexible appearance and size. In recent years, LED lighting devices are becoming inexpensive and thus gradually replace traditional lights used in various occasions of illumination. However, heat energy emitted from the LED is quite high during use. If such high heat energy could not be dissipated sufficiently, the working efficiency and the lifespan of various components inside the LED lighting device would be reduced, or some of the components may even fail to work normally or even melt. Therefore, effective dissipation of heat energy generated by LED light source is one of the most important factors to be considered when a LED light device is designed or implemented.

"It is generally known that there are three ways of heat transfer: convection, conduction and radiation. Presently, the heat-dissipating system used in LED lighting devices is designed to include:

"Presently, some LED lighting devices have a heat dissipating silica gel applied between the heat conduction panel and the heat sink. As the silica gel are prone to getting dry to turn into grains, the contact surface between the heat conduction panel and the heat sink are not in close contact each other, which would increase a heat resistance on the contact surface. Accordingly, the heat conduction performance of interface between the light source and the heat sink is greatly reduced. Therefore, it is impossible to acquire good heat dissipation effect.

"In order to enhance the heat dissipation capacity of the LED lighting devices, the heat sink may be subject to surface treatment, including but not limited to anodic oxidation treatment and black coating treatment. However, these two methods only bring limited improvement on the heat dissipation capacity of the heat sink in the LED lighting device, particularly in the LED lighting device with high power.

"Nanotechnology has found a wide range of applications as a new technology in recent years. The nano-materials are well known for their surface effect, volume effect and quantum size effect, and exhibit many outstanding physical and chemical properties, for example in aspects of melting point, electrical conductivity, thermal conductivity etc. There have been a large number of teachings on the use of nano-materials as heat-conducting and heat-dissipating materials. However, the problem of even dispersion of nano-particles, especially nano-particles with particle size less than 1 nm, in a solvent remains.

"In general, the prior art LED lighting devices are very bulky and require labor-intensive manufacturing procedures because their heat dissipation structures are quite bulky and complicated. Therefore, there is a need for improvement on the heat-dissipating system of the LED lighting devices. The present invention introduces a novel heat-dissipating system taking advantage of nano-materials, which not only improves the heat dissipation efficiency but also allows the lighting devices to work in a stable condition while implementing a compact and light structure at a low cost."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "It is the inventors' finding that simultaneous use of tert-butyl acetate (CAS#540885) and 4-Chlorobenzotrifluoride (CAS#98566) as dispersants enables even dispersion of nano-particles with particle size less than 1 inn in the water-soluble solvent such as water so as to afford an emulsion which has particularly excellent performance in heat conduction and heat dissipation.

"Based on the above finding, the present invention proposes a new process for preparation of a heat-conducting and heat-dissipating nano-material. The resultant heat-conducting and heat-dissipating nano-material has the ability of effectively and quickly dissipating the heat generated inside the LED lighting device. Due to its excellent heat dissipation effect, the size of heat dissipation structure can be very small, the heat dissipation fins commonly used in the art can even be removed. As a result, the whole lighting device becomes smaller and lighter.

"In order to achieve the above objects, the present invention provides a method for preparation of a heat-conducting and heat-dissipating nano-material, characterized by comprising the following steps:

"i) mixing a complex formed by a high molecular material and a substance having heat conduction and heat dissipation properties with tert-butyl acetate and 4-Chlorobenzotrifluoride, wherein the complex is of nanoscale in particle size; and

"ii) placing the mixture obtained from step i) into water and stirring the mixture in water for a period of time to afford the heat-conducting and heat-dissipating material.

"According to the present invention, the substance having heat conduction and dissipation properties may be inorganic or organic, and may be selected from the group consisting of ceramic, carbon, paraffin, silica and polymethylsilazane.

"Preferably, the complex, the tert-butyl acetate and the 4-Chlorobenzotrifluoride are mixed in a ratio by weight of the complex 20-40%: the tert-butyl acetate 35-45%: the 4-Chlorobenzotrifluoride 25-35%. Based on a total weight of water, the complex, the tert-butyl acetate and the 4-Chlorobenzotrifluoride, the water is used in an amount of about 25-75% weight of the total weight.

"The particle size of the complex used in the invention is less than 1 nm.

"In step ii), the stirring is performed at an atmospheric pressure and at room temperature for 10-20 minutes. The heat conducting and heat dissipating material is then formed as an emulsion.

"A second aspect of the invention relates to a heat-conducting and heat-dissipating nano-material prepared by a method of the invention.

"A third aspect of the invention provides a heat dissipating system for a lighting device, comprising a heat conduction panel connected with a light source in a thermally conductive manner, and a heat sink heat sink connected with the heat conduction panel for heat conduction, the heat-conducting and heat-dissipating nano-material of the invention is applied onto a surface of the heat conduction panel in contact with the heat sink, and/or onto an external surface of the heat sink.

"In one preferred embodiment of the invention, the heat-conducting and heat-dissipating nano-material applied onto the surface of the heat conduction panel in contact with the heat sink is 0.3-2 mil in thickness, and the heat-conducting and heat-dissipating nano-material applied onto the external surface of the heat sink is 0.3-2 mil in thickness.

"In order to ensure that the surfaces are sufficiently clean for the application of the heat-conducting and heat-dissipating material for enhanced attachment and prolonged lifespan of the material, the heat conduction panel and the heat sink are pre-treated by sand blast before the application of the material.

"In one embodiment of the invention, the light source is one or more LEDs.

"In another embodiment of the invention, the heat sink is free of heat-dissipating fins or provided with a small number of fins. The heat conduction panel and the heat sink are made from metal.

"Depending on which type of substance having properties of heat conduction and heat dissipation is used, the heat-conducting and heat-dissipating nano-material of the invention varies in its heat conduction performance and heat dissipation performance. For example, the heat-conducting and heat-dissipating material made from the complex formed by high molecular material and ceramic would have better heat conductivity, which is more suitable to be coated between the heat conduction panel and the heat sink to transfer the heat generated by the LED light source to the heat sink by heat conduction and also by heat radiation as a supplementary means. The heat-conducting and heat-dissipating material made from the complex formed by high molecular material and silica would have better performance in heat dissipation, which is more suitable to be coated on the external surface of the heat sink so as to transfer the heat to the ambient by the way of radiation.

"The heat-conducting and heat-dissipating nano-material of the present invention is viscous, and can be naturally cured within half an hour. This allows the material to adhere the heat conduction panel and heat sink together.

"The heat-conducting and heat-dissipating material of the present invention is of nano-particles, particularly nano-particles with sizes less than 1 nm, they can be easily and evenly dispersed in the water-soluble solvent in the presence of both tert-butyl acetate and 4-Chlorobenzotrifluoride used as the dispersing agents to give a homogenous emulsion. The present invention has not only solved the problems of even dispersion of the nano-particles in the solvent, but also acquired the emulsion with excellent performance in heat conduction and heat dissipation. It is found that coating of this emulsion between the heat conduction panel and the heat sink as well as on the external surface of the heat sink can transfer quickly the heat generated by the LED light source to the surface of the heat sink through heat conduction or heat convection, and the heat is then dissipated from the heat sink to the ambient by heat radiation, thereby conferring the active heat dissipation ability on the heat sink. Since the nano-material of the present invention has greatly increased the heat dissipation efficiency of the LED light, in some cases the fins may be removed from the heat sink. Such a heat sink thus has simple structure with light weight and small size, and the cost on raw materials can be reduced significantly.

"As stated above, depending on which type of substance having properties of heat conduction and heat dissipation is used, the heat-conducting and heat-dissipating nano-material of the invention varies in its heat conduction performance and heat dissipation performance. The material selected for the coating between the heat conduction panel and the heat sink preferably has better heat conductivity and therefore the heat-conducting and heat-dissipating material made from the complex formed by high molecular material and ceramic may be used. The material selected for the coating on the surface of the heat sink preferably has better performance in heat dissipation, and therefore the heat-conducting and heat-dissipating material made from the complexes formed by high molecular material and silica may be used.

"The following paragraphs will further illustrate and explain the conceptions, structures and technical effects of the present invention with reference to the drawings, so as to allow for a better understanding of the objects, features and effects of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

"The further objects, features, characteristics and effects of the invention will be illustrated in more details by way of examples with reference to the accompany drawings, wherein:

"FIG. 1 is a schematic view of a heat sink adopted by an existing LED lighting device;

"FIG. 2 is a schematic view of a heat-dissipating system of a LED lighting device according to an embodiment of the present invention;

"FIG. 3 is a schematic view of a heat sink according to an embodiment of the present invention."

For more information, see this patent application: Juy, King Sun; Hui, Man Wah. Heat-Conducting and Heat-Dissipating Nano-Materials, Preparing Method Thereof and Heat-Dissipating System. Filed June 10, 2011 and posted June 12, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5305&p=107&f=G&l=50&d=PG01&S1=20140605.PD.&OS=PD/20140605&RS=PD/20140605

Keywords for this news article include: Chemicals, Chemistry, Silica Gel, Green Formula Limited.

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Source: Politics & Government Week


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