TWI406894B - Composite material with porous powder and its manufacturing method - Google Patents

Abstract

The present invention is related to a composite material containing porous powder and its manufacturing method. The composite material comprises 20 to 80 weight percent (wt%) of the heat conductive powder and the remainder content of the plastic matrix, while above 20 wt% of the heat conductive powder are the porous granules containing a plurality of pores. Thus, the composite material containing the porous powder of the present invention not only contains an extremely high heat conductive coefficient but also has a higher toughness, thereby having a high heat conductivity and practicability, being convenient in processing, and capable of increasing the product yield.

Description

Composite material with porous powder and manufacturing method thereof

The present invention relates to a composite material and a method of manufacturing the same, and more particularly to a composite material having a porous powder and a method of manufacturing the same.

The conventional heat conductive composite material is usually a composite material prepared by mixing plastic and thermal conductive powder, but since the amount of the thermal conductive powder must be added enough, the thermal conductivity can be improved. In the prior art, the amount of the heat conductive powder generally needs to be 40 to 70 weight percent (wt%), and the addition of a large amount of the heat conductive powder may lower the toughness of the composite material.

Insufficient toughness can cause serious problems in the application of composite materials. For example, at the time of injection molding, the finished product may be broken by the impact of the thimble during ejection, or may be broken by collision or falling during transportation, or may be broken due to force during subsequent processing, or the finished product may be finished. Can not withstand impact and break when in use.

The conventional method for manufacturing the heat conductive composite material is obtained by melt-mixing the heat conductive powder and the plastic, and the plastic substrate and the heat conductive powder have a certain degree of incompatibility, so that the interface generally cannot withstand external force, under the impact of external force, The rupture is easily transmitted along the interface. Moreover, the conventional thermal conductive composite material has a high thermal conductive powder content, and the interface area between the thermal conductive powder and the plastic substrate is large, so that the impact resistance (toughness) of the conventional thermal conductive composite material is much lower than that of the ordinary plastic.

In order to improve the impact strength of the heat-conducting compound, in the prior art, fiber reinforcement is added to the heat-conductive composite material, or a short elastic body is added. However, the addition of the elastomer tends to lower the heat distortion temperature of the conventional heat conductive composite material, and the addition of the fiber increases the difficulty in forming the conventional heat conductive composite material; and when the content of the heat conductive powder is high, if it is impossible to increase The combination of heat-conducting powder and plastic substrate is limited by the added effect of adding fiber or elastomer.

The prior art documents of four conventional thermally conductive composite materials are listed below.

1. Republic of China Patent No. I285656: Thermally conductive composite material: a high aspect ratio (greater than 10:1) of thermally conductive powder with a resin blend of 25 to 60 volume percent (vol%), and a low aspect ratio of 10 to 25 vol% A thermally conductive composite material is made of a thermally conductive powder (less than 5:1).

Disadvantages: Only the thermal conductivity of the thermally conductive composite material is discussed, and the method of increasing the mechanical strength (toughness) is not disclosed.

2. Republic of China Patent Open No. 200837109: Thermally conductive resin composition and plastic products

Method: using a resin mixed with 40~70 wt% of thermal conductive powder, at least 10 wt% of the thermal conductive powder is a thermal conductive fiber with a length to height ratio of 7000 to 40,000, and another thermal conductivity of at least 10 Wt% and a length to height ratio of 10 to 1000 Powder; use a suitable proportion of fibrous heat-conductive filler to increase the bending strength of the composite.

Disadvantages: 1) Adding fibers with high aspect ratio is not only difficult to process, the fiber is easy to break during screw processing, and surface quality defects are easily formed when the finished product is shot; 2) Practically, if the thermal conductivity is to be maintained and the mechanical strength of the thermally conductive composite is increased, It is necessary to add a sufficient amount of fiber, generally carbon fiber or metal fiber, which is liable to cause poor insulation of the composite material; 3) a method for increasing the strength of the composite material to withstand external impact is not disclosed.

3. Republic of China Patent No. 238327: Filler for Thermally Conductive Plastic Materials

Method: sintering alumina of different particle size combinations to form a powdery mixture as a heat conductive filler to increase the filling amount of the heat conductive powder in the resin.

Disadvantages: It is only revealed that the filler can be increased by using the sintered filler, and it is not disclosed that the sintered powder can increase the strength of the thermally conductive composite.

4. Republic of China Patent No. 534374: Metal Polymer Hybrid Heat Sink

Practice: The plastic is mixed with a discontinuous high thermal conductivity fiber, and after injection, it is injection molded, and the surface of the formed part is coated with a metal layer having a high thermal conductivity. The metal polymer hybrid heat sink is mounted on a computer central processor to assist the central processor in dissipating heat.

Disadvantages; there is no strength requirement for the use of thermally conductive plastics in central processor cooling systems, and therefore methods for increasing the strength of thermally conductive composite materials have not been disclosed.

Therefore, it is necessary to provide an innovative and progressive composite material having a porous powder and a method of manufacturing the same to solve the above problems.

The invention provides a composite material with porous powder, comprising 20-80 weight percent (wt%) of thermal conductive powder, and the remaining content is a plastic substrate, and 20 wt% or more of the thermal conductive powders have a plurality of Porous particles of pores.

The present invention further provides a method for producing a composite material having a porous powder, comprising the steps of: (a) providing a plurality of thermally conductive powders, wherein more than 20 wt% of the thermally conductive powders are porous having a plurality of pores (b) mixing the heat-conducting powder and a molten plastic substrate, the content of the heat-conducting powder is 20-80 wt%, and the remaining content is a plastic substrate, and the molten plastic substrate is filled in each a hole of the porous heat-conducting powder; and (c) the heat-conductive powder and the plastic substrate after solidification forming and mixing to form a composite material of porous powder.

The composite material with porous powder of the invention not only has a very high heat transfer coefficient, but also has high toughness, so it has higher thermal conductivity and practicality, is convenient for processing, and can increase the yield of the product.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing a composite material having a porous powder according to a preferred embodiment of the present invention; and Figure 2 is a cross-sectional view showing a heat conductive powder having a plurality of holes in the present invention. Referring to FIG. 1 and FIG. 2, the porous composite material 1 comprises 20 to 80 weight percent (wt%) of the thermal conductive powder 11 and the remaining content is the plastic substrate 12. 20 wt% or more of the thermally conductive powders 11 are porous particles having a plurality of holes 111. The porous powder composite material 1 of the present invention can be applied to a support member for an electronic component, a coil bobbin of a coil, or an external component of an electronic device (for example, a casing of a transformer).

The thermally conductive powder 11 may be selected from the group consisting of alumina, aluminum nitride, boron nitride, iron oxide, aluminum powder, copper powder or graphite powder. Preferably, the content of the thermally conductive powder 11 is 40 to 70 wt%, and 50 wt% or more of the thermally conductive powders 11 are porous particles, and the pore diameter of the porous thermally conductive powder 11 is 0.1 to 15 Mm. More preferably, the porous thermally conductive powder 11 has a pore size of 0.5 to 10 μm.

The plastic substrate 12 may be selected from the group consisting of polycarbonate (PC), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polysulfide (PPS) or liquid crystal polymer. (LCP). Preferably, the content of the thermally conductive powder 11 is 30 to 60 wt%, and the content of the plastic substrate 12 is 40 to 70 wt%.

Figure 3 is a flow chart showing a method of manufacturing a composite material having a porous powder according to a preferred embodiment of the present invention. Referring to FIG. 1 , FIG. 2 and FIG. 3 , first, referring to step S31 , a plurality of thermal conductive powders 11 are provided, and 20 wt% or more of the thermal conductive powders 11 are porous particles having a plurality of holes 111 (reference drawing) 2). In the method of the present invention, the holes 111 may be formed by etching the thermally conductive powder 11 with an acid, a base or a solvent in step S31, or holes may be formed by the holes formed during sintering of the powder.

Referring to step S32, the thermal conductive powder 11 and a molten plastic substrate 12 are mixed. The content of the thermal conductive powder 11 is 20-80 wt%, and the remaining content is the plastic substrate 12, and the plastic substrate 12 is melted. The hole 111 filled in each of the porous heat conductive powders 11 can be flown to increase the bonding force between the heat conductive powders 11 and the plastic substrate 12, thereby greatly improving the toughness of the composite material 1 having the porous powder. Impact strength.

Referring to step S33, the thermally conductive powder 11 and the plastic substrate 12 after solidification molding are mixed to form a composite material 1 having a porous powder. In the method of the present invention, in step S33, the composite material 1 having the porous powder can be solidified by molding, compression molding, or injection molding.

The invention is illustrated by the following examples, which are not intended to be limited to the scope of the invention.

Examples and comparison examples:

In each of the following examples and comparative examples, calcined alumina (Sumitomo product, material No. A21) was selected as the thermally conductive powder.

Preparation of porous heat conductive powder of the present invention:

The acidified washing liquid containing phosphoric acid was used to control the pickling of the vaporized aluminum at different concentrations and times to prepare porous vaporized aluminum powder having different pore diameters, and the pore size was measured by a scanning electron microscope.

Preparation of composite material with porous powder according to an example of the present invention:

PBT is selected as the plastic substrate (Changchun company product, material number PBT5600), and a certain proportion of PBT, alumina and other additives (optional addition) are mixed into a composite material at 260 ° C by a plastic spectrometer.

Sex quality measurement of composite materials:

The heat transfer coefficient of the composite was measured by a protective heat flow method (using Anter's Unitherm Model 2022 instrument in accordance with ASTM E1530), and the toughness of the composite was measured by the Izod method (ASTM D256, unnotched).

<Example 1>

Take 34 g of PBT and 66 g of porous alumina (pore size 0.5~3.5 μm) and make a composite material by a plastic spectrometer.

<Example 2>

Take 34 g of PBT and 66 g of porous alumina (pore size 1.0~5.5 μm) and make a composite material by a plastic spectrometer.

<Example 3>

Take 34 g of PBT and 66 g of porous alumina (pore size 2.0~6.0 μm) and make a composite material by a plastic spectrometer.

<Example 4>

Take 30 g of PBT, 66 g of porous alumina (pore size 1.0 to 3.0 μm) and 3.4 g of MBS elastomer (with butadiene-based elastomer), and make a composite material by a spectrometer.

<Comparative Example 1>

Take 34 g of PBT and 66 g of alumina (without holes) and make a composite material with a spectrometer.

<Comparative Example 2>

30.6 g PBT, 66 g alumina (without holes) and 3.4 g MBS elastomer were used to make a composite material by a spectrometer.

<Comparative Example 3>

Take 29 g of PBT, 59 g of alumina (without holes) and 12 g of 3 mm of glass fiber, and make a composite material by a spectrometer.

The experimental results of Examples 1-4 and Comparative Examples are summarized in Table 1.

It can be seen from the experimental results of Comparative Examples 1-3 that when the addition amount of alumina (thermally conductive powder) is as high as 59 to 66 wt%, the addition of MBS elastomer and glass fiber not only causes a significant decrease in the heat transfer coefficient of the composite material, but also the toughness cannot be obtained. Improved; shows that when the composite is filled with a large amount of thermally conductive powder, the toughness is considerably more difficult.

The composite compositions of Example 3 and Comparative Example 1 were the same, but Example 3 used porous aluminum carbide. As a result, the composite material of Example 3 showed not only an increase in heat transfer coefficient compared with Comparative Example 1, but also a toughness increase of 1.8 times. From the experimental results of Examples 1-3, it was found that the porous alumina was also used and the addition amount was fixed at 66 wt%, and when the maximum pore diameter was increased from 3.5 μm of Example 1 to 6.0 μm of Example 3, the toughness of the composite was increased from 1.5 to 2.0 ft-lbf/in.

The composite compositions of Comparative Example 4 and Comparative Example 2 were the same, but Example 4 used porous alumina, and the results showed that the composite material toughness of Example 4 was increased to 2.0 times that of Comparative Example 2.

The composite material with porous powder of the invention not only has a very high heat transfer coefficient, but also has high toughness, so it has higher thermal conductivity and practicality, is convenient for processing, and can increase the yield of the product.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the scope of the present invention. The scope of the invention should be as set forth in the appended claims.

1. . . Composite material with porous powder of preferred embodiment

11. . . Thermal powder

12. . . Plastic substrate

111. . . Hole

1 is a schematic view showing a composite material having a porous powder according to an embodiment of the present invention;

2 is a cross-sectional view showing a thermally conductive powder having a plurality of holes in the present invention; and

Fig. 3 is a flow chart showing a method of manufacturing a composite material having a porous powder according to an embodiment of the present invention.

11. . . Thermal powder

111. . . Hole

Claims (12)

The composite material with porous powder comprises 20-80 weight percent (wt%) of thermal conductive powder, and the remaining content is a plastic substrate, and more than 20 wt% of the thermal conductive powder is porous with a plurality of holes Shaped particles. The composite material of claim 1, wherein the thermally conductive powder is contained in an amount of 40 to 70 wt%. The composite material of claim 1, wherein the thermally conductive powder system is alumina, aluminum nitride, boron nitride, iron oxide, aluminum powder, copper powder or graphite powder. The composite material of claim 1, wherein 50% by weight or more of the thermally conductive powders are porous particles. The composite material of claim 1, wherein the porous thermally conductive powder has a pore size of 0.1 to 15 μm. The composite material of claim 5, wherein the porous thermally conductive powder has a pore size of 0.5 to 10 μm. The composite material of claim 1, wherein the content of the heat conductive powder is 30 to 60 wt%, and the content of the plastic substrate is 40 to 70 wt%. The composite material of claim 1, wherein the plastic substrate is polycarbonate (PC), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polysulfurized benzene. (PPS) or liquid crystal polymer (LCP). The composite material of claim 1, which is applied to a support member of an electronic component, a coil bobbin of a coil, or an external component of an electronic device. A method for manufacturing a composite material having a porous powder, comprising the steps of: (a) providing a plurality of thermally conductive powders, wherein more than 20 wt% of the thermally conductive powders are porous particles having a plurality of pores; Mixing the heat-conducting powder and a molten plastic substrate, the content of the heat-conducting powder is 20-80 wt%, and the remaining content is a plastic substrate, and the molten plastic substrate is filled with each porous heat conduction a hole of the powder; and (c) the thermally conductive powder and the plastic substrate after solidification forming to form a composite material of porous powder. The method of claim 10, wherein in the step (a), the holes are formed by etching with an acid, a base or a solvent, or holes are formed when the powder is sintered to form the holes. The method of claim 10, wherein in step (c), the composite material having the porous powder is solidified by molding, compression molding, or injection molding.