TW201516195A - Aluminum nitride fiber and preparation method thereof and highly thermal conductive composite material - Google Patents

Abstract

This invention provides an aluminum nitride fiber and a preparation method thereof. The preparation method comprises: preparing a spinning solution containing an aluminum nitride powder and an aluminum-containing precursor, wherein based on 100 wt% of the spinning solution, the weight percentage of the aluminum nitride powder ranges from 2 to 20 wt%, and the weight ratio of the aluminum-containing precursor to the aluminum nitride powder ranges from 25 to 55; then using solution spinning method to convert the spinning solution into aluminum nitride-containing polymeric composite fiber, which is then subjected to high temperature calcination to obtain the aluminum nitride fiber; moreover, this invention further provides a highly thermal conductive composite material containing the aluminum nitride fiber.

Description

Aluminum nitride fiber and preparation method thereof, and high thermal conductive composite material

The invention relates to a high heat dissipating fiber and a preparation method thereof, and a polymer composite material containing the high heat dissipating fiber, in particular to an aluminum nitride fiber and a preparation method thereof, and a high thermal conductive composite containing the aluminum nitride fiber material.

The high thermal conductivity polymer composite material is one of the high performance materials widely used in the thermal conduction of electronic components, and the insulating high thermal conductivity polymer composite material is usually added with an inorganic filler having high thermal conductivity in the polymer material. For example, ceramic powder, to achieve the purpose of insulation and heat dissipation. Among them, aluminum nitride is one of the main representatives of high heat dissipation ceramic powder because of its high thermal conductivity (theoretical value: 320 W/mK), good electrical insulation, low dielectric constant and dielectric loss.

Heat conduction is a way of transferring heat from a high temperature zone to a low temperature zone through direct contact between materials. The structure of the polymer generally belongs to a saturated system. There is no free electron and the molecular motion is difficult. Therefore, the heat conduction of the polymer material itself is mainly the result of lattice vibration, so the heat conduction effect is not good. Therefore, in order to obtain a polymer material having high thermal conductivity and insulation, most of them are currently highly thermally conductive. The inorganic powder is used in a polymer material, such as the aforementioned aluminum nitride powder, for the purpose of insulation and heat dissipation.

However, the addition of the aluminum nitride powder to the polymer material can increase the thermal conductivity, but the addition amount of the aluminum nitride powder is highly correlated with the heat transfer ability and the processability; the amount of addition is too small to form heat transfer. The passage leads to poor heat transfer capacity; too much addition, not only increases the cost, but also causes difficulty in processing and shaping. For example, in general, in order to obtain an insulating composite material having high heat dissipation properties, the amount of aluminum nitride powder added is not less than 50%, and even in order to obtain an insulating heat dissipating material having heat dissipation of more than 70 W/mK, the amount of aluminum nitride powder is added. It will be higher than 75%, which not only increases the cost, but also makes it difficult to process and shape.

Therefore, how to make the aluminum nitride powder form a good heat conduction path in the polymer substrate, so that the addition amount can be reduced, and the polymer composite material can have good thermal conductivity without affecting the characteristics of the original polymer material. It is an important direction for the inventors to study and develop.

Accordingly, it is an object of the present invention to provide a method of preparing an aluminum nitride fiber having high thermal conductivity.

Further, another object of the present invention is to provide an aluminum nitride fiber having high thermal conductivity.

Still another object of the present invention is to provide a highly thermally conductive composite material having aluminum nitride fibers.

Thus, the method for preparing an aluminum nitride fiber having high thermal conductivity of the present invention comprises the following three steps.

(a) preparing a spinning solution, the spinning composition comprising an aluminum nitride powder, an aluminum-containing precursor, a solvent, and a polymeric thickener, wherein the weight of the spinning solution The percentage by weight is 100% by weight, the weight percentage of the aluminum nitride powder is between 2 and 20% by weight, and the weight ratio of the aluminum-containing precursor to the aluminum nitride powder is between 25 and 55.

(b) The spinning solution is formed into a polymer composite fiber containing aluminum nitride by a spinning method.

(c) The polymer composite fiber is calcined at 400 to 550 ° C in an inert atmosphere, and the organic component of the polymer composite fiber is removed in the calcination process to obtain an aluminum nitride fiber.

In addition, the present invention provides an aluminum nitride fiber having high thermal conductivity, which is obtained by the method for preparing the aluminum nitride fiber as described above, and the length/diameter ratio of the aluminum nitride fiber. More than 50.

Moreover, the present invention provides a highly thermally conductive composite material having aluminum nitride fibers, comprising a substrate and a plurality of aluminum nitride fibers dispersed on the substrate, the substrate being selected from the group consisting of polymer materials, and the aluminum nitride fibers are It is produced by the method for producing the aluminum nitride fiber as described above.

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Other features and effects of the present invention will be apparent from the following description of the drawings. FIG. 1 is a flow chart illustrating the preferred embodiment of the method for preparing aluminum nitride fibers of the present invention; Is an SEM photograph illustrating the aluminum nitride fiber produced by the preferred embodiment of the present invention; and Figure 3 is an XRD spectrum illustrating the XRD measurement results of the aluminum nitride fibers produced by the preferred embodiment of the present invention.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

The preferred embodiment of the method for producing an aluminum nitride fiber of the present invention is for producing an aluminum nitride fiber having high heat dissipation properties, and preferably, the aluminum nitride fiber has a length/diameter ratio of more than 50.

Referring to Figure 1, the preferred embodiment of the method for preparing the aluminum nitride fiber of the present invention comprises the following three steps.

In step 21, a spinning solution is prepared.

The composition of the spinning solution includes an aluminum nitride powder, an aluminum-containing precursor, a solvent, and a polymeric thickener.

The aluminum-containing precursor is selected from the group consisting of aluminum chloride, aluminum hydroxide, aluminum oxide, and a combination of the foregoing, the solvent being selected from solvents having better dispersibility and solubility for other components in the spinning solution, such as : ethanol, isopropanol, acetone, etc.; the polymeric thickener is selected from the group consisting of polyvinyl alcohol, sodium alginate, polyalkoxyethylene, polyvinyl butyral, ethyl cellulose, polyvinyl pyrrolidone, and the foregoing One of the combinations.

It should be noted that the proportional control of the components in the spinning solution is an important key factor determining the quality of the subsequently formed aluminum nitride fiber. When the content of aluminum nitride in the spinning solution is insufficient, the quality of the formed aluminum nitride fiber is Poor, it will affect the thermal conductivity, and when the aluminum nitride powder in the spinning solution is too much, the polymer When the thickener is insufficient or the viscosity is too high, there is a disadvantage that it is difficult to form or form agglomerates during the spinning stage, and there is a disadvantage that the heat dissipation is lowered; preferably, in order to allow the spinning solution to be in the subsequent spinning process The polymer composite fiber and the aluminum nitride fiber of good quality can be smoothly formed, and the viscosity of the spinning solution is controlled at 70 to 140 cps, and the weight percentage of the spinning solution is 100 wt%, and the aluminum nitride powder is The weight percentage is between 2 and 20% by weight, the weight percentage of the polymeric thickener is between 5 and 15% by weight, and the weight ratio of the aluminum-containing precursor to the aluminum nitride powder is between 25 and 55; preferably The weight percentage of the aluminum nitride powder is between 3 and 10%, the weight percentage of the polymeric thickener is between 10 and 15% by weight, and the weight ratio of the aluminum-containing precursor to the aluminum nitride powder is between 25~40.

Next, in step 22, a polymer composite fiber is obtained.

In the step 22, the spinning solution obtained by disposing the step 21 is formed by a solution spinning method, for example, a wet spinning method or a dry spinning method, to form the polymer composite fibers containing aluminum nitride particles. Since the adjustment and control of the parameters related to the solution spinning method are known in the art, no further description is provided. In the present embodiment, the step 22 is described by taking the spinning solution into a polymer composite fiber by an electrospinning method. The electrospinning process is described below.

First, the step 21 is prepared, the spinning solution with a viscosity control of 70-140 cps is injected into a needle tube having a stainless steel needle, and a receiving device remote from the needle and grounded is disposed, and then 9 to 18 kV is applied to the needle ( High-voltage static electricity of kV), and a strong electric field is generated between the needle and the receiving device, so that the spinning solution that is sprayed from the needle to the receiving device is accelerated and A plurality of non-woven polymer composite fibers are formed on the receiving device by unfolding into a finer submicron liquid column and simultaneously volatilizing the solvent.

Finally, in step 23, the polymer composite fibers are calcined to obtain aluminum nitride fibers.

In the step 23, the polymer composite fibers containing the aluminum nitride powder and the aluminum-containing precursor prepared in the step 22 are placed in a high temperature furnace under an inert atmosphere and at a temperature of 400 to 500 ° C. The polymer composite fibers are calcined to remove organic components in the polymer composite fiber, and the aluminum nitride powder and the aluminum-containing precursor in the polymer composite fibers generate oxides during the calcination process. The oxide encapsulates the aluminum nitride powder to form a long chain shape, so that continuous aluminum nitride fiber can be obtained after calcination. In the present embodiment, the high molecular composite fibers are calcined at 400 to 500 ° C under nitrogen for 0.5 to 2 hours to obtain the aluminum nitride fibers.

Referring to Figures 2 and 3, Figure 2 shows a scanning electron microscope (SEM) photograph of the obtained aluminum nitride fiber; and Figure 3 shows the results of XRD detection of the aluminum nitride fibers. The XRD results were confirmed to be aluminum nitride structures after being compared with the ICDD database.

When the aluminum nitride fiber obtained by the invention is doped into a polymer substrate, a highly thermally conductive composite material having high thermal conductivity can be obtained, and then the high thermal conductive composite material is processed through a general polymer processing method. If extruded or extruded, it can be made into a heat dissipating component suitable for various purposes.

The polymer substrate of the foregoing high thermal conductive composite material may be selected from General thermoplastic or thermosetting plastics, such as: polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, thermosetting resin: such as phenolic resin, epoxy resin Polyimide, polyester, or ABS resin, etc., the aluminum nitride fiber may be added or subtracted according to the heat conduction requirement of the high thermal conductive composite material; preferably, the polymer substrate itself is not affected Under the premise of physical properties and high thermal conductivity, the aluminum nitride fiber is added in an amount of 10 to 50% based on 100% by weight of the high thermal conductive composite.

Next, the preparation method of the aluminum nitride fiber of the present invention will be described in the following specific examples and one comparative example, which can be more clearly understood.

Specific example 1

A spinning solution comprising 0.15 g of aluminum nitride powder, 5.5 g of an aluminum chloride solution, 2 g of a solvent, and 0.6 g of polyvinyl alcohol was prepared.

The spinning solution was poured into a needle, and the spinning solution was formed into a plurality of polymer composite fibers by electrospinning under conditions of 9 kV.

Then, the polymer composite fibers were placed in a high-temperature furnace and calcined at 450 ° C for 0.5 hour to obtain an aluminum nitride fiber A-1.

Comparative example 1

The production method of Comparative Example 1 was substantially the same as that of the specific example 1, except that in the spinning solution of Comparative Example 1, the aluminum nitride powder was 0.7 g, and the aluminum chloride solution was 5.5 g, and aluminum nitride was obtained. Fiber B-1.

Then, the aluminum nitride fiber prepared in the specific example 1 and the comparative example 1 and the conventionally used aluminum nitride powder are respectively doped into the epoxy resin high score. Different test pieces were made in the sub-material, and thermal conductivity measurement was performed using a heat conduction analyzer, and the measured results were summarized in Table 1 below.

It can be seen from the results shown in Table 1 that by adding the aluminum nitride fiber of the present invention to the polymer substrate, since the aluminum nitride fibers can establish a good heat transfer path inside the polymer substrate, The amount of addition (40 wt%) can be equivalent to the thermal conductivity of a conventionally added 50 wt% aluminum nitride powder, and when the amount of the aluminum nitride fiber of the present invention is increased to 50 wt%, the thermal conductivity is comparable. The same amount of aluminum nitride powder was increased by 1.5 times. From the results of the test piece 2 of Table 1, it is found that when the aluminum nitride fiber B-1 is added to the polymer substrate, the heat dissipation property is not good, and it is presumed that the process of preparing the aluminum nitride fiber B-1 should be performed. Because the ratio of the aluminum chloride solution to the aluminum nitride powder is too small, the oxide generated during the calcination process is insufficient to coat the aluminum nitride powder, so that not only the aluminum nitride fiber can be effectively formed, but also the formation The agglomerate cannot effectively dissipate heat, and greatly reduces the heat dissipation effect of the composite.

In summary, the present invention uses the electrospinning method to prepare a polymer composite fiber, and then removes the polymer material by calcination to obtain an aluminum nitride fiber, and the aluminum nitride fiber is added to the polymer substrate. Because these aluminum nitride fibers can establish good heat transfer inside the polymer substrate The transfer path has a relatively high thermal conductivity when added in a small amount, and the addition of a large amount of aluminum nitride powder filler generally on the polymer substrate can be improved, thereby not only reducing the cost but also avoiding the addition. Excessive additives affect the basic physical properties of the polymer substrate, so the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the patent application scope and patent specification content of the present invention, All remain within the scope of the invention patent.

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Claims (10)

A method for preparing an aluminum nitride fiber, comprising: (a) preparing a spinning solution, the composition of the spinning solution comprising an aluminum nitride powder, an aluminum-containing precursor, a solvent, and a polymer thickening The weight percentage of the aluminum nitride powder is between 2 and 20% by weight, and the weight ratio of the aluminum-containing precursor to the aluminum nitride powder is between 25 and 50% by weight of the spinning solution. ~55; (b) the spinning solution is formed into a polymer composite fiber containing aluminum nitride by a solution spinning method; and (c) the polymer composite fiber is calcined at 400 to 550 ° C under an inert atmosphere. The organic component of the polymer composite fiber is removed during the calcination process to obtain an aluminum nitride fiber. The method for producing an aluminum nitride fiber according to claim 1, wherein the step (b) is to prepare the aluminum nitride-containing polymer composite fiber by an electrospinning method. The method for producing an aluminum nitride fiber according to claim 1, wherein the weight ratio of the aluminum-containing precursor to the aluminum nitride powder is 25 to 40. The method for producing an aluminum nitride fiber according to claim 1, wherein the polymer thickener has a weight percentage of 5 to 15% by weight based on 100% by weight of the spinning solution. The method for preparing an aluminum nitride fiber according to claim 1, wherein the viscosity of the spinning solution in the step (a) is controlled at 70 to 140 cps. The method for producing an aluminum nitride fiber according to claim 1, wherein the aluminum-containing precursor is selected from the group consisting of aluminum chloride, aluminum hydroxide, aluminum oxide, and the foregoing One combination. An aluminum nitride fiber which is an aluminum nitride fiber obtained as in the first aspect of the patent application, and has a length/diameter ratio of more than 50. A highly thermally conductive composite material comprising a substrate and a plurality of aluminum nitride fibers dispersed on the substrate, the substrate being selected from the group consisting of polymer materials, the aluminum nitride fibers being produced by the method of claim 1 Got it. The highly thermally conductive composite material of claim 8, wherein the aluminum nitride fiber has a length to diameter ratio greater than 50. The high thermal conductive composite material according to claim 8, wherein the aluminum nitride fiber is added in an amount of 10 to 50% by weight based on 100% by weight of the high thermal conductive composite material.