CN106810876B - Composite material with directionally arranged fillers and preparation method thereof - Google Patents

Abstract

The invention discloses a composite material with directional arrangement of fillers and a preparation method thereof, belonging to the technical field of new materials and their preparation. The method firstly mixes the lamellar filler and the organic polymer material uniformly, and then realizes the orderly and directional arrangement of the filler in the matrix by extrusion, and then prepares the composite material with the directional arrangement of the filler. The prepared composite material is composed of lamellar fillers and organic polymer material matrix. The lamellar fillers are ordered and oriented in the organic polymer material matrix, so as to give full play to the performance advantages of the fillers in a specific direction. Therefore, The composite material has excellent properties (such as thermal conductivity in a specific direction), good elasticity and flexibility, and has application potential in many fields such as thermal conductivity, electrical conductivity or electromagnetic shielding.

Description

A kind of composite material with directional arrangement of fillers and preparation method thereof

technical field

The invention relates to the technical field of new materials and their preparation, in particular to a composite material with directional arrangement of fillers and a preparation method thereof.

Background technique

With the development of science and technology, organic polymer composite materials have been widely used. Compared with traditional metal materials, organic polymer composite materials have the characteristics of light weight, flexibility, and corrosion resistance unique to the polymer matrix itself, and at the same time, it can achieve thermal conductivity and electrical conductivity by adding fillers. Traditional organic polymer composite materials are generally composite materials prepared by directly mixing filler particles in organic polymer materials such as silicone rubber. sex, etc.). However, in these composite materials, the filler particles are generally distributed in a disorderly manner in the polymer matrix and separated by the polymer matrix (Fig. 1(a)), which seriously restricts the performance of the filler. The addition of a large number of thermally conductive fillers not only increases the cost and weight, but also reduces the elasticity of the material and increases the hardness, but it is difficult to significantly improve the performance.

In some applications, only the performance of the material in a specific direction is of interest (eg thermally conductive interface materials). Therefore, in the preparation process of organic polymer composite materials, if some anisotropic fillers can be directionally distributed in the polymer matrix through certain process steps, and give full play to the performance advantages of fillers in specific directions, it may be a way to improve organic polymer composite materials. Effective means of material properties.

The miniaturization and multifunctionalization of electronic components have put forward higher requirements for the heat dissipation of the devices. The problem of heat dissipation of devices has become a technical "bottleneck" faced by the rapidly developing telecommunications industry. In order to reduce the interface thermal resistance, thermal interface materials have been developed. Filling the interface heat-conducting material between the contact surfaces can remove the air in the pores of the contact interface, form a continuous heat-conducting channel on the entire contact interface, and improve the heat dissipation efficiency of the electronic components.

Generally speaking, the thermal conductivity of lamellar fillers is anisotropic. For example, graphene, its in-plane (radial) thermal conductivity (~5000 W/mK) is very different from its vertical-plane (axial) thermal conductivity (~10 W/mK). For thermal interface materials, people mainly focus on their thermal conductivity perpendicular to the plane direction (axial). If the axial arrangement of such lamellar fillers in the matrix can be achieved through certain process steps (as shown in Figure 1(b)), the high thermal conductivity of such fillers can be brought into full play. Thereby, the purpose of reducing the amount of filler added and significantly improving the thermal conductivity of the composite material is achieved.

SUMMARY OF THE INVENTION

In order to solve the problem that the existing technology is difficult to realize the directional arrangement of the fillers in the matrix, the purpose of the present invention is to provide a composite material with directional arrangement of the fillers and a preparation method thereof, which can realize the directional arrangement of the fillers in the composite material through a simple extrusion process In the material matrix, the specific arrangement of its fillers makes it have high thermal conductivity, which is suitable for the field of heat dissipation of electronic devices.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A preparation method of a composite material with directional arrangement of fillers. The method firstly mixes lamellar fillers and organic polymer materials uniformly, and then realizes the orderly directional arrangement of fillers in a matrix by extrusion, so as to give full play to the fillers The advantage of thermal conductivity in a specific direction, and then the composite material with the filler directional arrangement is prepared; the method specifically includes the following steps:

(1) Add the lamellar filler and the curing agent into the organic polymer material, and after fully mixing, the filler is evenly dispersed in the matrix to obtain a mixed material; the specific feeding sequence is: first add the curing agent to the organic polymer material, After mixing evenly, the lamellar filler is added; in this step, one or more of the high-speed mixer, shear emulsifier, kneader or two-roll mill can be used to combine the filler, organic polymer matrix and solidification The agent is fully mixed to ensure that the filler is evenly dispersed in the matrix.

(2) Using a twin-roll mill to extrude the mixture obtained in step (1) into a flake sample with a thickness of less than 0.5 mm, the lamellar filler in the obtained flake sample is located along the location of the flake sample. The plane is arranged in a directional arrangement;

(3) Laminate a plurality of sheet-like samples obtained in step (2), and then further press them into block samples, and then slice the blocks along the required specific orientation to obtain layered materials; when slicing the blocks, The slicing direction can be perpendicular to the flaky sample, but it is not limited to the vertical direction, and can be cut along different angles and directions according to needs, so as to realize the arrangement of fillers along the required directions and angles;

(4) The layered material obtained in step (3) is heated and pressurized to solidify and form, that is, a composite material in which the fillers are oriented in a directional arrangement is obtained.

The lamellar filler is one or more of flake graphite, graphene, flake boron nitride, flake silicon carbide, flake aluminum powder and flake silver powder. The sheet diameter of the lamellar filler is in the range of 0.1-500 μm, and the thickness is in the range of 0.1-100 μm.

The organic macromolecular material is one or more organic macromolecular elastic materials with good elasticity and flexibility among methyl vinyl silicone rubber, vinyl silicone oil, polyurethane and polydimethylsiloxane. The curing agent is 2,4-dichlorobenzoyl peroxide, hydrogen-containing silicone oil or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and the like.

In the above step (1), the weight ratio of the lamellar filler to the organic polymer material is (0.25-9): 1, and the weight ratio of the curing agent to the organic polymer material is (0.5-2): 100 .

The composite material obtained through the above process of the present invention is composed of lamellar fillers and an organic polymer material matrix, wherein: the lamellar fillers are arranged in an orderly and directional arrangement in the organic polymer material matrix, and the fillers are in the composite material. The weight percentage of 20-90%.

The thermally conductive interface material is a sheet-like material, and the orientational arrangement direction of the sheet-like fillers is perpendicular to the plane where the thermally conductive interface material is located or at other angles. The thermal conductivity of the thermally conductive interface material along the directional arrangement direction of the lamellar fillers can reach 60 W/mK, and has good elasticity and compressibility.

The present invention has the following advantages:

1. The present invention utilizes the in-plane high thermal conductivity characteristics of lamellar materials such as graphene to prepare a thermally conductive interface material with excellent thermal conductivity, the preparation process is simple, the required raw materials are cheap and easy to obtain, and it is easy to realize industrialized mass production through process amplification, The cost has significant advantages over traditional products in related application fields.

2. In the composite material prepared by the process of the present invention, lamellar thermal conductive fillers such as graphene are uniformly dispersed in the organic polymer material matrix, and it can be found by observing the microscopic morphology of its cross-section through scanning electron microscope (SEM) etc. The packing orientation arrangement characteristics. The thermal conductivity of the composite material with the directional arrangement of the filler prepared by the invention is significantly improved compared with that without the directional arrangement treatment. The thermal conductivity of the composite material can reach 60W/mK (in the direction of the directional arrangement of the filler), and it has good elasticity and compressibility.

3. The composite thermal interface material prepared by the present invention has the characteristics of light weight, elasticity, flexibility and high thermal conductivity, which can well fill the gaps in the thermal interface, reduce the thermal resistance of the interface, and improve the heat dissipation efficiency of electronic components. Its cooling effect is obvious, which exceeds the level of current commercial thermal interface materials. It can be widely used in high-power LED street lamps, computers, smart phones, network switches and other electronic products. the heat dissipation performance of the product.

Description of drawings

Figure 1 is a schematic diagram of thermal conductivity of lamellar fillers; wherein: (a) the fillers are randomly arranged; (b) the lamellar fillers are oriented and arranged in the axial direction in the matrix.

FIG. 2 is a schematic diagram of the preparation process of the thermally conductive interface material with directional arrangement of fillers according to the present invention.

3 is an optical photograph of the graphene composite thermal interface material of the present invention.

Fig. 4 is the scanning electron microscope photograph of the graphene composite thermal interface material of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

The present invention prepares a composite material formed by directional arrangement of fillers in an organic polymer material matrix. The preparation process is shown in FIG. 2 , which can be obtained through the simple process shown in the figure.

The thermal conductivity of the material is the main index to measure the thermal conductivity of the material, so the present invention measures the thermal conductivity of the prepared thermal interface material. The instrument used for the test is the TIM Tester 1400 material thermal resistance and thermal conductivity tester of ANALYSIS TECH Company of the United States (this instrument is currently widely used in domestic electronic product manufacturers and scientific research units), and the test implements the ASTMD 5470 standard. At the same time, this test method can directly detect the thermal resistance value of the tested sample, which is especially suitable for measuring the thermal conductivity of thermal interface materials.

Example 1:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 30 g of graphene powder was added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. Slice the block in the vertical direction; heat and pressurize the cut sheet to solidify and form, and then a graphene-silica composite thermal conductive material in which the graphene is arranged in an axial orientation (that is, perpendicular to the plane of the sheet) can be obtained.

The macroscopic morphology of the graphene composite thermal interface material prepared in this example is shown in the optical photo in Figure 3. The material has good flexibility and elasticity, can fully fill the thermal interface gap, and significantly improve the heat dissipation effect of electronic devices.

The microscopic morphology of the graphene composite thermal interface material prepared in this example is shown in the scanning electron microscope photo in FIG. 4 . As can be seen from the photos, the graphene is uniformly distributed in the silicone rubber matrix. The graphene micro-sheets are tightly connected, showing a relatively obvious feature of being arranged along the axial direction (that is, the direction perpendicular to the plane of the sheet-like composite material).

Using the apparatus and method described in the description, the thermal conductivity of the composite material in the direction perpendicular to its plane was measured to be 6.7W/mK. Since the morphology and testing method of the samples in other embodiments are similar to those of this example, they will not be repeated hereafter.

Example 2:

First, 100 g of vinyl silicone oil and 1 g of curing agent (hydrogen-containing silicone oil) were mixed in a kneader, and then 30 g of graphene powder was added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instruments and methods described in the description, the thermal conductivity of the material was measured to be 6.3W/mK.

Example 3:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 200 g of flake boron nitride powder was added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instrument and method described in the description, the thermal conductivity of the material was measured to be 4.8W/mK.

Example 4:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 20 g of graphene powder and 400 g of flaky silicon carbide powder were added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instrument and method described in the description, the thermal conductivity of the material was measured to be 7.5W/mK.

Example 5:

First mix 100g methyl vinyl silicone rubber and 1g curing agent (2,4-dichlorobenzoyl peroxide) in a kneader, then add 20g graphene powder and 200g flake boron nitride powder and mix for 2h . The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instrument and method described in the description, the thermal conductivity of the material was measured to be 12.1 W/mK.

Example 6:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 20 g of graphene powder and 300 g of flake aluminum powder were added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instrument and method described in the description, the thermal conductivity of the material was measured to be 13.5W/mK.

Example 7:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 20 g of graphene powder and 100 g of flake graphite powder were added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instrument and method described in the description, the thermal conductivity of the material was measured to be 15.2W/mK.

Example 8:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 15 g of graphene powder and 150 g of flake graphite powder were added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instruments and methods described in the description, the thermal conductivity of the material was measured to be 25.0 W/mK.

Example 9:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 20 g of graphene powder and 150 g of flake graphite powder were added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instrument and method described in the description, the thermal conductivity of the material was measured to be 40.0 W/mK.

Example 10:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 20 g of graphene powder and 600 g of flake silver powder were added and mixed for 2 hours. The mixture was taken out, and the mixture was repeatedly extruded 10 times using a double-roll mill with a gap of 0.5 mm; the mixture was extruded into a sheet with a thickness of less than 0.5 mm. The extruded sheet-like mixture is laminated and further compacted into a block. The block is sliced along the vertical direction; the cut sheet is heated and pressed to solidify and form, and the composite thermally conductive material in which the fillers are oriented along the axial direction can be obtained.

The macroscopic morphology and microscopic morphology of the thermally conductive interface material prepared in this example are the same as in Example 1, that is, the filler is uniformly distributed in the polymer material matrix. The layers of the filler are closely connected, showing a relatively obvious feature of being oriented along the axial direction (ie, the direction perpendicular to the plane where the thermally conductive interface material is located).

Using the instrument and method described in the description, the thermal conductivity of the material was measured to be 60.0 W/mK.

Comparative Example 1:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 30 g of graphene powder was added and mixed for 2 hours. The mixture was taken out, heated and pressurized to solidify and form, to obtain a comparative sample with the same filler ratio as in Example 1.

Using the instruments and methods described in the description, the thermal conductivity of the material was measured to be 2.0 W/mK.

Comparative Example 2:

First, 100 g of methyl vinyl silicone rubber and 1 g of curing agent (2,4-dichlorobenzoyl peroxide) were mixed in a kneader, and then 20 g of graphene powder and 400 g of flaky silicon carbide powder were added and mixed for 2 hours. The mixture was taken out, heated and pressurized to solidify and form, to obtain a comparative sample with the same filler ratio as in Example 4.

Using the instrument and method described in the description, the thermal conductivity of the material was measured to be 3.9W/mK. The embodiments provided above are only for explanation and should not be considered as limiting the scope of the present invention. Any method that is equivalently replaced or changed according to the technical solution of the present invention and its inventive concept should be included in the protection scope of the present invention. within.

Claims (3)

1. a preparation method of the composite material of the directional arrangement of fillers, is characterized in that: the method first uniformly mixes lamellar fillers with organic macromolecular materials, and then realizes the orderly directional arrangement of fillers in the matrix by extrusion cloth, and then prepare the composite material with the directional arrangement of the filler; the method specifically includes the following steps: (1) Add the lamellar filler and the curing agent into the organic polymer material, and after fully mixing, the filler is uniformly dispersed in the matrix to obtain a mixed material; the weight ratio of the lamellar filler to the organic polymer material is (0.25) -9): 1, the weight ratio of the curing agent to the organic polymer material is (0.5-2): 100; (2) The mixed material obtained in step (1) is extruded with a double-roll mill, and extruded into a flake sample with a thickness of less than 0.5 mm, and the lamellar filler in the obtained flake sample is along the location of the flake sample The plane is arranged in a directional arrangement; (3) laminating the plurality of sheet-like samples obtained in step (2), and then further pressing them into block samples, and then slicing the blocks along a desired specific orientation to obtain a layered material; (4) heating and pressurizing the layered material obtained in step (3) to solidify and form, that is, to obtain a composite material in which the fillers are directionally arranged; The lamellar filler is one or more of flake graphite, graphene, flake boron nitride, flake silicon carbide, flake aluminum powder and flake silver powder; The sheet diameter of the lamellar filler is in the range of 0.1-500 μm, and the thickness is in the range of 0.1-100 μm; The organic polymer material is methyl vinyl silicone rubber. 2 . The method for preparing a composite material with directional arrangement of fillers according to claim 1 , wherein: in step (1), the curing agent is 2,4-dichlorobenzoyl peroxide or 2,5 - Dimethyl-2,5-di(tert-butylperoxy)hexane. 3 . The method for preparing a composite material with directional arrangement of fillers according to claim 1 , wherein the order of adding materials in step (1) is as follows: first add the curing agent to the organic polymer material, and then add the curing agent after mixing evenly. 4 . lamellar filler; in step (1), use one or more of a high-speed mixer, a shear emulsifier, a kneader or a two-roll mill to fully mix the filler, the organic polymer matrix and the curing agent, Ensure that the filler is evenly dispersed in the matrix.

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