AU2003203809B9 - Heat-absorbing particle - Google Patents

Description

Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Kun-Hsiang HUANG Actual Inventor/s: Kun-Hsiang HUANG Address for Service: MADDERNS, 1st Floor, 64 Hindmarsh Square, Adelaide, South Australia, Australia Invention title: HEAT-ABSORBING

PARTICLE

The following statement is a full description of this invention, including the best method of performing it known to me.

PatAU132) Heat-Absorbing Particle Background of the Invention 1. Field of the Invention The present invention relates to a heat-absorbing particle. In particular, the present invention relates to a heat-absorbing particle that can be coated on a surface of an object for heat-dissipation and/or antioxidation.

2. Description of the Related Art Computer components, electronic products, mechanical parts, etc.

generate heat during operation. It is common to mount fans, fins, heat conductive tubes, and other heat-dissipating members on these devices for expediting dissipation of the generated heat. Heat energy causes two kinds of change in a substance: one in temperature, and the other in phase, the latter being known as "latent heat." Ordinary heat-dissipating members are made of copper or aluminum that absorbs heat and thus incurs a direct increase in the temperature. These heat-dissipating members provided more or less expected heat-dissipating effect. However, due to recent improvement in the operation speed of the computers, the temperature of the heat-generating devices in the computers may rise up to 100°C or even higher. And these conventional heat-dissipating members or devices were found to be incapable of dissipating such a large amount of heat.

The surface of the heat-dissipating members is sometimes covered with a layer of paint or coating for preventing oxidation and/or providing an aesthetically pleasing appearance. However, the paint or coating adversely affects the heat-dissipating effect.

U.S. Patent No. 5,456,852 to Isiguro issued on Oct. 10, 1995 discloses a microcapsule for heat-storing material which encapsulates a compound la capable of undergoing phase transitions, the microcapsule containing a high-melting compound having a melting point 200C 110 oC higher than that of the compound capable of undergoing phase transition. However, the compound capable of undergoing phase transition has a melting point at about 1 oC 37 OC, which is incapable of effectively absorbing the heat generated by the recently developed computers.

An object of the present invention is to provide a heat-absorbing particle that can be coated on a surface of an object for heat-dissipation and/or antioxidation.

Summary of the Invention According to a first aspect of the present invention there is provided a method for manufacturing a heat-absorbing particle, including: preparing a prepolymer aqueous solution; mixing a molten heat-absorbing material, an emulsifier, a protective colloid, and water to form an emulsion; mixing the prepolymer with the emulsion to cause reaction for forming capsulated heat-absorbing material; filtering and drying the capsulated heat-absorbing material to form heatabsorbing particles.

According to a second aspect of the present invention there is provided a heatabsorbing particle having a diameter of 1-1000 m and including a shell portion (1) and a core portion the shell portion being made of a high molecular polymer selected from a group including melamine-formaldehyde, urea-formaldehyde resins, polyurethanes, and acrylics, the core portion being made of a heat-absorbing material that has a melting point at about 35oC-70 OC and that is selected from a group including straight chain alkanes, alcohols, and organic acids, a weight of the shell portion being about 1/20 1/2 of that of the core portion wherein the heatabsorbing particle is produced by a method including: preparing a prepolymer aqueous solution; mixing a molten heat-absorbing material, an emulsifier, a protective colloid, and water to form an emulsion; mixing the prepolymer with the emulsion to cause reaction for forming capsulated heat-absorbing material; filtering and drying the capsulated heat-absorbing material to form heatabsorbing particles.

Preferably, the heat-absorbing material is selected from a group including paraffin, docosane, tetracosane, tetradecanol, hexadecanol, octodecanol, dodecanic acid, tetradecanoic acid, and hexadecanoic acid.

Brief Description of the Drawings Fig. 1 is a schematic sectional view of a heat absorbing particle in accordance with the present invention.

Fig 2. is a schematic flowchart illustrating preparation of the heat-absorbing particle in accordance with the present invention and subsequent coating process.

Fig 3. is a plan view showing locations of temperature measuring points on an aluminium plate for test.

Detailed Description of the Preferred Embodiment Referring to Fig. 1, a heat-absorbing particle in accordance with the present invention is a micro-capsular particle with a diameter of 1-1000 Y m and generally includes a shell portion and a core portion The shell portion is made of a high molecular polymer selected from a group including melamine-formaldehyde, urea-formaldehyde resins, polyurethanes, and acrylics.

The core portion is made of a heat-absorbing material that has a melting point at about 35 0 C 70 0 C and that is selected from a group including straight chain alkanes, alcohols, and organic acids. Preferably, the core portion is made of a heat-absorbing material selected from a group including paraffin, docosane, tetracosane, tetradecanol, hexadecanol, octodecanol, dodecanic acid, tetradecanoic acid, and hexadecanoic acid. The weight of the shell portion is about 1/20 1/2 of that of the core portion The heat-absorbing material uses latent heat to store the heat from a heatdissipating member or heat source. When the heat-absorbing material absorbs heat, the temperature of the heat-absorbing material is not changed at first. Instead, the temperature of the heat-absorbing material lags for a period of time at the melting point (about 35 0 C 70 0 C) thereof. The heat transmitted to the heat-absorbing material is absorbed without causing a rise in the temperature of the heat-absorbing material.

The heat absorbed by the heat-absorbing particle is then dispersed to the environmental air. Thus, the heat from the heat-dissipating member or the heat source can be effectively absorbed, thereby maintaining normal operation of the device including the heat source. The core portion of the heat-absorbing material may further include a dye to provide a desired colour.

Fig. 2 is a schematic flowchart illustrating preparation of the heat-absorbing particle in accordance with the present invention and subsequent coating process. In this embodiment, the heat-absorbing material is tetradecanol, and an epoxy-polyester resin is used as a solvent. Firstly, an appropriate amount of prepolymer aqueous solution is prepared by means of mixing melamine (60 parts), formaldehyde (37%, 150 parts), and water (290 parts) together and then heating the mixture at 60 0 C for one hour (step S10). Next, preparing a mixture of molten tetradecanol and a dye at a ratio of about 1000 3 (the ratio can be optionally adjusted) until completely dissolved (step S12). The dyed tetradecanol is added into a solution of tween 80 parts) and PVP (polyvinyl pyrrolidone, 20%, 50 parts), and the solution is then stirred to form an emulsion. The emulsion is added into the prepolymer aqueous solution and then heated at 60C, and ethanoic acid is added until pH=6. The reaction is continued until a complete reaction is obtained. After the reaction is complete, the temperature is lowered to the room temperature, and ammonia water is added until pH=9. A micro-capsulation procedure is thus complete (step S14). The obtained micro-capsules are filtered and dried, and the resultant particles microcapsules) are the heat-absorbing particles in accordance with the present invention. It is noted that the heat-absorbing particles in accordance with the present invention can be produced by other suitable procedures, and the dye can be omitted.

Still referring to Fig. 2, for coating, 30 parts of micro-capsules are dissolved and dispersed with 70 parts of epoxy-polyester resin (the solvent) (the ratio between the micro-capsules and the solvent can be optionally adjusted) at high temperature.

The solution is then cooled and crushed to form a heat-absorbing coating material (step S18). The heat-absorbing coating material can be sprayed by a spray gun onto a surface of a metallic or non-metallic object (step In accordance with the present invention, a layer of heat-absorbing coating can be formed on a surface of any object. Since the layer includes a thermosetting material, certain strength and fixation are obtained. Of more importance, the heat-absorbing material of the heat-absorbing particle absorbs heat in an effective manner. The heat-absorbing coating can be coated on a large area of a casing of, a portable computer, and a conductive wire or conductive plate may be used to connect the heat-absorbing coating to the heat source, the central processing unit of the portable computer, thereby dissipating the heat generated by the central processing unit. The coating can also be coated on a casing in which the central processing unit is directly in contact with the casing no conductive wire or conductive plate is provided between the central processing unit and the casing). The heat-absorbing particle containing the dyed heat-absorbing material may be called a "heat-absorbing pigment." Of course, the heat-absorbing particle needs not to be dyed. Nevertheless, the term "heat-absorbing pigment" referred to herein means a heat-absorbing particle containing a dyed heat-absorbing material, and the term "heat-absorbing particle" includes a dyed or not dyed heat-absorbing material. The heat-absorbing material without dye can be added into a solvent containing dye. Alternatively, the heat-dissipating particles in accordance with the present invention can be added into ordinary paint for subsequent coating on a surface of an object for heat-dissipating purpose.

The heat-absorbing coating can be applied to heat-dissipating members and outer casing of computers, heat-dissipating members of machines, parts, heat-dissipating members, and outer casing of electric appliances, and parts, heat-dissipating members, outer casing of vehicles. Another advantage of 6 the heat-absorbing coating is antioxidation without adversely affecting the heat-dissipating function. In addition, the heat-absorbing coating can be coated on a surface of any integrated circuit that requires heat-dissipation and/or antioxidation.

Test In order to prove the heat-absorbing effect of the heat-absorbing particles in accordance with the present invention, the heat-absorbing particles are coated on upper and lower surfaces of an aluminum plate of mm x 10 mm ("the experimental plate"), and several points are selected on each of the upper and lower surfaces of the aluminum plate. For comparison, a comparative aluminum plate also of 10 mm x 10 mm ("the comparative plate") is provided, and corresponding points are selected on each of upper and lower surfaces of the comparative plate. As can be seen in Fig. 2, for each of the experimental plate and the comparative plate, points T1-T8 are temperature-measuring points on the upper surface of the aluminum plate.

Points B 1-B8 are temperature measuring points on the lower surface of the aluminum plate. A heater with a power of 10.8W is located on point B2 on the lower surface of the aluminum plate that is opposite to point T2 on the upper surface of the aluminum plate. The environmental temperature is 3 0C.

All of the points T1-T8 and B1-B8 are not coated with the coating. Table 1 shows the temperature detected at the points Ti-T8 and B1-B8 respectively on the comparative plate and the experimental plate. As can be clearly seen in Table 1, the detected temperatures of the points T1-T8 and B 1-B8 on the aluminum plate without coating (the comparative plate) are higher than those of the points T1-T8 and B1-B8 on the aluminum plate with coating (the experimental plate).

Table 1 comparative plate experimental plate B2 (heater) 70.10C 43.45°C Tl 60.0°C 40.8C T2 64.8°C 43.0°C T3 56.7°C 39.60C T4 53.8°C 38.10C 52.6°C 36.9 C T6 51.6°C 36.4C T7 51.4°C 36.4C T8 51.6°C 36.5oC Bl 61.2°C 42.10 B3 57.4°C 40.10C B4 54.6°C 38.6C B5 52.5°C 36.8C B6 50.5°C 36.3oC B7 51.8°C 36.4°C B8 51.5°C 36.20C According to the above description, it is appreciated that the heat-absorbing particle in accordance with the present invention provides an excellent heat-absorbing effect. The heat-absorbing coating in accordance with the present invention can be coated on any surface of an object for heat-dissipation and/or antioxidation. Further, when the heat-absorbing coating layer has a color the heat-absorbing material is dyed), an aesthetically pleasing effect may be provided without adversely affecting the heat-absorbing effect.

Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention as hereinafter claimed.

Claims (19)

1. A method for manufacturing a heat-absorbing particle, including: preparing a prepolymer aqueous solution; mixing a molten heat-absorbing material, an emulsifier, a protective colloid, and water to form an emulsion; mixing the prepolymer with the emulsion to cause reaction for forming capsulated heat-absorbing material; filtering and drying the capsulated heat-absorbing material to form heat-absorbing particles.

2. The method as claimed in claim 1, wherein the emulsifier is one of tween tween 40, tween 60, tween 80, and tween

3. The method as claimed in claim 2, wherein the emulsifier is tween

4. The method as claimed in claim 1, further including dissolving the heat- absorbing particles with solvent and coating onto a surface of an object. The method as claimed in claim 4, wherein the emulsifier is tween

6. The method as claimed in any one of claims 1 or 4, wherein the heat-absorbing material is selected from a group including paraffin, docosane, tetracosane, tetradecanol, hexadecanol, octodecanol, dodecanic acid, tetradecanoic acid, and hexadecanoic acid.

7. The method as claimed in claim 6, wherein the emulsifier is tween

8. The method as claimed in claim 1, further including adding a dye in the step of mixing molten heat-absorbing material, emulsifier, protective colloid, and water to form an emulsion.

9. The method as claimed in claim 8, wherein the emulsifier is tween The method as claimed in claim 8, further including dissolving the heat- absorbing particles with solvent and coating onto a surface of an object.

11. The method as claimed in claim 10, wherein the emulsifier is tween

12. The method as claimed in claim 8, wherein the heat-absorbing material is selected from a group including paraffin, docosane, tetracosane, tetradecanol, hexadecanol, octodecanol, dodecanic acid, tetradecanoic acid, and hexadecanoic acid.

13. The method as claimed in claim 12, wherein the emulsifier is tween

14. The method as claimed in any one of claims 1 to 13, wherein the protective colloid is polyvinyl pyrrolidone. A heat-absorbing particle having a diameter of 1-1000 y m and including a shell portion and a core portion the shell portion being made of a high molecular polymer selected from a group including melamine- formaldehyde, urea-formaldehyde resins, polyurethanes, and acrylics, the core portion being made of a heat-absorbing material that has a melting point at about 35oC-70 oC and that is selected from a group including straight chain alkanes, alcohols, and organic acids, a weight of the shell portion being about 1/20 1/2 of that of the core portion wherein the heat-absorbing particle is produced by a method including: preparing a prepolymer aqueous solution; mixing a molten heat-absorbing material, an emulsifier, a protective colloid, and water to form an emulsion; mixing the prepolymer with the emulsion to cause reaction for forming capsulated heat-absorbing material; filtering and drying the capsulated heat-absorbing material to form heat-absorbing particles.

16. The heat-absorbing particle as claimed in claim 15, wherein the heat-absorbing material is selected from a group including paraffin, docosane, tetracosane, tetradecanol, hexadecanol, octodecanol, dodecanic acid, tetradecanoic acid, and hexadecanoic acid.

17. The heat-absorbing particle as claimed in claim 15, wherein the heat-absorbing material further includes a dye.

18. The heat-absorbing material as claimed in claim 15, wherein the emulsifier is one of tween 20, tween 40, tween 60, tween 80, and tween

19. The heat-absorbing material as claimed in claim 16, wherein the heat- absorbing material further includes a dye. The heat-absorbing material as claimed in any one of claims 16 or 17, wherein the emulsifier is tween

21. The heat-absorbing material as claimed in any one of claims 15 to 20, wherein the protective colloid is polyvinyl pyrrolidone.

22. A heat-absorbing particle as hereinbefore described with reference to and as shown in the accompanying drawings.

23. A method as hereinbefore described with reference to and as shown in the accompanying drawings. Dated this 16 t day of July, 2004. Kun-Hsiang Huang By his Patent Attorneys MADDERNS