CN113337253A

CN113337253A - Heat-conducting gasket and preparation method thereof

Info

Publication number: CN113337253A
Application number: CN202110659820.1A
Authority: CN
Inventors: 葛翔; 李峰; 李壮; 石燕军; 周步存
Original assignee: Changzhou Fuxi Technology Co Ltd
Current assignee: Changzhou Fuxi Technology Co Ltd
Priority date: 2021-06-11
Filing date: 2021-06-11
Publication date: 2021-09-03

Abstract

The invention provides a heat conduction gasket, which comprises a heat conduction filler and a reinforcing material, wherein the heat conduction filler is a two-dimensional heat conduction filler arranged along the thickness direction of the heat conduction gasket, the reinforcing material is a filament formed by drawing a high molecular polymer and/or a carbon filament formed by drawing the high molecular polymer and/or a carbon filament formed by heat treatment, and the high molecular filament and/or the carbon filament tightly connect the two-dimensional heat conduction filler to form a filler/high molecular and/or filler/carbon filament network structure.

Description

Heat-conducting gasket and preparation method thereof

Technical Field

The invention relates to the technical fields of heat-conducting and heat-dissipating materials, heat-conducting interface materials, heat management materials and the like, in particular to a heat-conducting gasket and a preparation method thereof.

Background

In electronic devices such as 5G base stations, notebook computers and high-power LED displays, the radiator can timely radiate heat generated by the heating element, so that the operation stability of the electronic devices is ensured. In most cases, a heat conducting gasket is required to be arranged between the heating element and the heat sink to reduce the interface thermal resistance. With the great improvement of the power of electronic devices, common heat conducting gaskets (with the heat conductivity coefficient below 10W/m/K) are far from meeting the heat dissipation requirement. Patent document JP6646836B2 discloses the use of flat graphite powder orientation to produce high thermal conductivity gaskets. However, the single graphite powder filler is difficult to fill to a high degree, and often requires the addition of ordinary thermally conductive fillers to build up an adequate thermally conductive network. The common heat-conducting filler has a limited effect of improving the heat-conducting performance, and simultaneously, the density and the hardness of the heat-conducting gasket are increased. For graphite powder, the larger the sheet diameter is, the better the heat conduction effect is. Whereas, the graphite powder used in JP6646836B2 has a flake diameter concentrated in the range of 20 to 400 μm, and if graphite powder having a larger flake diameter is used, cracking of the heat conductive sheet is caused.

Therefore, a reinforcing means can be provided which can realize a high filling amount of a single graphite powder and can also fill a graphite powder having a larger flake diameter. In this regard, patent document CN110437807A discloses a heat conductive gasket prepared by rolling only polymer fibers and sheet-like heat conductive fillers. However, the gasket prepared only by using the polymer fibers and the heat conductive filler has weak internal bonding force and high hardness, so that when two-dimensional flaky heat conductive fillers such as graphite powder, graphene and boron nitride are used, the gasket with high heat conductivity in the plane direction can be obtained, but the gasket with high heat conductivity in the thickness direction cannot be prepared.

Disclosure of Invention

The invention provides a heat conduction gasket, aiming at one or more problems in the prior art, and the heat conduction gasket comprises a heat conduction filler and a reinforcing material, wherein the heat conduction filler is a two-dimensional heat conduction filler arranged along the thickness direction, the reinforcing material is a filament formed by drawing a high molecular polymer and/or a carbon filament formed by heat treatment of the filament formed by drawing the high molecular polymer, and the two-dimensional heat conduction filler is tightly connected by the high molecular filament and/or the carbon filament to form a filler/polymer and/or filler/carbon filament network structure.

Optionally, the two-dimensional heat conductive filler accounts for 50 wt.% to 90 wt.%, preferably 60 wt.% to 80 wt.% of the heat conductive gasket, and if the two-dimensional heat conductive filler accounts for less than 50 wt.%, the heat conductive effect is poor, and if the two-dimensional heat conductive filler accounts for more than 90 wt.%, the heat conductive gasket cannot be molded due to too much two-dimensional heat conductive filler.

Alternatively, the high molecular polymer constitutes 0.3 wt.% to 5 wt.%, preferably 1 wt.% to 3 wt.%, with an amount of less than 0.3 wt.% resulting in failure to form an effective network structure and an amount of more than 5 wt.% resulting in a significant increase in the hardness of the gasket.

Optionally, the two-dimensional heat conducting filler in the heat conducting gasket comprises a two-dimensional heat conducting filler with a sheet diameter in a range of 10-1000 μm, wherein a ratio of the sheet diameter distribution between 10-100 μm and 100-1000 μm is 0.1-9.0, preferably 0.5-2.0.

Optionally, the high molecular polymer comprises at least one of PE, PP, PS, PA, PTFE, ABS, PET, PBT, PVDF, POM, polyphenylene oxide, polysulfone, and the like; the high molecular weight polymer grade is preferably a wire drawing grade.

Optionally, the composite material further comprises a binder, wherein the filler/macromolecule and/or filler/carbon filament network structure penetrates through the binder and is tightly combined with the binder.

Optionally, the proportion of binder is 5 wt.% to 49.7 wt.%, preferably 15 wt.% to 40 wt.%.

Optionally, the adhesive comprises one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin and organic silica gel; silicone rubber is preferable from the viewpoints of compressibility, compression resilience, hardness, caulking effect, and the like; the organic silica gel is preferably liquid organic silica gel; the liquid silicone gum may include one or more of polydimethylsiloxane, alpha, omega-dihydroxypolydimethylsiloxane, polydiphenylsiloxane, alpha, omega-dihydroxypolymethyl (3,3, 3-trifluoropropyl) siloxane, cyanosiloxysilane, and alpha, omega-diethylpolydimethylsiloxane.

According to another aspect of the present invention, there is provided a method for manufacturing a thermal pad, including:

(a) fully mixing the heat-conducting filler and the high molecular polymer;

(b) the high-speed shearing is carried out to convert the high-molecular polymer into filaments, the filaments connect the two-dimensional heat-conducting fillers to form a filler/high-molecular network structure, the filler/high-molecular network structure can be further subjected to heat treatment to convert the high-molecular filaments into carbon filaments, and the carbon filaments still tightly connect the two-dimensional heat-conducting fillers to form a filler/carbon filament network structure;

(c) preparing a filler/macromolecule and/or filler/carbon filament network structure into a sheet, wherein two-dimensional heat-conducting fillers in the sheet are arranged along the transverse direction;

(d) laminating the sheets, pressing the laminated sheets into a block, and curing and forming;

(e) and cutting the solidified and molded block into a plurality of thin slices along the direction of the stacking height to obtain the heat-conducting gasket with the two-dimensional heat-conducting filler arranged longitudinally.

Optionally, the method further comprises the step (c) of adding an adhesive, and fully and uniformly mixing to enable the filler/polymer and/or filler/carbon filament network structure to penetrate through the adhesive and be tightly combined with the adhesive.

Alternatively, the shearing in step (b) may be carried out using a high speed shearing machine or a jet mill; preferably, the high-speed shearing machine adopts a blade type shearing device rotating at a high speed, the rotating speed is 1000-50000r/min, preferably 15000-30000r/min, and the shearing time is 0.5-6min, preferably 1-3 min; preferably, when a jet mill is used, the milling pressure is 3 to 10kg · f/cm²Preferably 5 to 8 kg. f/cm²(ii) a Further preferably, the vibration frequency of the feeder is 15-50Hz, preferably 20-40 Hz; and/or the feeding pressure is 3-8 kg.f/cm²Preferably 4 to 6 kg. f/cm²。

Optionally, the thickness of the sheet in the step (d) is 0.2-3.0mm, preferably 0.5-2.0mm, and is less than 0.2mm, so that the sheet is not easy to take out and perform subsequent operations; above 3.0mm, the orientation of the two-dimensional heat conductive filler is poor.

Optionally, the curing in step (e) is performed by heating or normal temperature curing; when the curing is carried out by heating, the temperature is 150 ℃ or lower, preferably 120 ℃ or lower, and when the temperature is higher than 150 ℃, the curing reaction is too severe due to the excessively high temperature, and the product is liable to crack.

Optionally, the cutting manner in step (f) is not particularly limited, and may be linear cutting, laser cutting, ultrasonic cutting, blade cutting, freezing cutting, vibration cutting, ultrasonic-freezing cutting, etc.; the thickness of the slice has no special requirement, and the slice is cut according to the specific requirement, and is generally the conventional thickness, such as 0.25-5 mm; it can also be cut into thinner sheets, such as 0.05-0.25 mm.

According to a third aspect of the present invention, there is provided an electronic device comprising a heat source, a heat dissipating member, and a heat conductive pad sandwiched between the heat source and the heat dissipating member, wherein the heat conductive pad is the heat conductive pad or is manufactured by the above manufacturing method.

The invention only adopts the two-dimensional heat-conducting filler as the heat-conducting filler to prepare the heat-conducting gasket, and filler matching with low heat-conducting coefficient is not needed; the high molecular filament and/or the carbon filament obtained by high molecular polymer wire drawing and/or further heat treatment tightly connect the two-dimensional heat-conducting filler to form a filler/high molecular and/or filler/carbon filament network structure with excellent mechanical property, the effect is obviously superior to the effect of directly adding high molecular fiber, and the ultrahigh filler content of the two-dimensional heat-conducting filler is ensured; the two-dimensional heat-conducting filler is highly oriented (e.g., Z-direction in fig. 3) along the thickness direction (e.g., Y-direction in fig. 3); the method for realizing the orientation of the two-dimensional heat-conducting filler is simple and easy to implement; the heat conductivity coefficient is high, and the application thermal resistance is low; has good compression resilience. The preparation method of the heat-conducting gasket directly realizes the high orientation of the two-dimensional heat-conducting filler in a mode of pressing the heat-conducting gasket into a sheet; an ultrathin longitudinal high-thermal-conductivity gasket can be prepared, such as 0.05 mm.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a photograph of a block according to the present invention;

FIG. 2 is a macro-topography of the thermal pad of the present invention;

FIG. 3 is a schematic view of the heat conductive pad of the present invention in the X-Y-Z direction;

FIG. 4 is an SEM image of the X-direction of the thermal pad of the present invention;

FIG. 5 is a Y-direction SEM image of a thermal pad of the present invention;

FIG. 6 is a Z-direction SEM image of a thermal pad of the present invention;

fig. 7 is a picture of embodiment 1 of the heat conductive gasket of the present invention;

FIG. 8 is a photograph of comparative example 1 of the heat conductive gasket of the present invention;

fig. 9 is a photograph of comparative example 2 of the thermal conductive gasket of the present invention.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

In the following examples and comparative examples, liquid silica gel was used as a binder to prepare a thermal conductive pad, and in order to show a comparative effect, the thickness (in the Y direction in fig. 3) of the slice of the following examples was measured as four thicknesses of 0.1mm, 0.5mm, 1mm, and 2mm, and the application thermal resistance and compression resilience thereof were measured;

the preparation process of the heat-conducting gasket with the two-dimensional heat-conducting fillers arranged longitudinally comprises the following steps:

fully mixing the heat-conducting filler and the high molecular polymer;

converting a high-molecular polymer into high-molecular filaments by high-speed shearing, wherein the high-molecular filaments mutually connect two-dimensional heat-conducting fillers to form a filler/high-molecular network structure; the filler/polymer network structure can be further subjected to heat treatment to change the polymer filaments into carbon filaments, and the carbon filaments are tightly connected with the two-dimensional heat-conducting filler to form the filler/carbon filament network structure; the filler/macromolecule andor filler/carbon wire network structure not only plays a role in mechanical reinforcement, but also can obviously improve the filling amount of the two-dimensional heat-conducting filler, and can still maintain higher mechanical property under the condition of ultrahigh filling amount;

adding adhesive, mixing to make filler/macromolecule andor filler/carbon fiber network structure penetrate through the adhesive and combine with it tightly;

pressing into a sheet material, and arranging the two-dimensional filler along the transverse direction of the sheet material;

laminating the sheets, pressing into a block (shown in figure 1), and curing and forming;

the heat conductive gasket (as shown in fig. 2) with two-dimensional heat conductive filler longitudinally arranged is obtained by cutting into a plurality of thin sheets along the direction of the stacking height (as shown in the direction Z in fig. 3), fig. 4 is an SEM image of the heat conductive gasket in the direction X of the invention, fig. 5 is an SEM image of the heat conductive gasket in the direction Y of the invention, fig. 6 is an SEM image of the heat conductive gasket in the direction Z of the invention, which is observed from different directions, and from fig. 4 to 6, it can be seen that the micro-sheets of the heat conductive gasket in the direction X are all flat, and Y, Z are both vertical, which indicates that the micro-sheets are highly oriented in the heat conductive gasket.

Example 1

As shown in fig. 7, 95 wt.% graphite sheet and 5 wt.% reinforcing material, wherein the reinforcing material is polymer filament, without binder, can still be directly pressed into shape, and has better formability.

Comparative example 1

As shown in fig. 8, 60 wt.% of graphene and 40 wt.% of binder are used, and the heat conducting gasket is prepared without reinforcing materials, and is poorly formed after pressing, so that the heat conducting gasket cannot be stacked.

Comparative example 2

As shown in fig. 9, the heat conductive gasket was prepared using 80 wt.% graphite sheet +20 wt.% binder without reinforcement and could not be press-molded.

The remarkable and indispensable role of the reinforcing material according to the invention for shaping is evident from figures 7-9.

The following examples, thermal conductivity, applied thermal resistance of thermal gaskets at 20psi were tested by ASTM D5470; the thermal gasket was tested for compression resilience under 30% strain by ASTM D575.

Example 2:

in this embodiment, the graphene accounts for 50 wt.%, the polymer filaments accounts for 0.3 wt.%, and the liquid silica gel accounts for 49.7 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 0.1;

the high molecular polymer used for wire drawing is PE;

the liquid silica gel is polydimethylsiloxane;

the high-speed shearing and wire drawing speed is 50000 r/min; shearing time is 0.5 min;

adding liquid silica gel, and mixing to obtain sheet with thickness of 0.2 mm;

the curing temperature is 150 ℃;

the test shows that the thermal conductivity of the sample is 15.4W/(m K), and the results of the application thermal resistance and the compression resilience of the samples with different thicknesses are shown in the following table 1:

TABLE 1

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.033	/
0.50	0.075	73
			1.00	0.126	66
2.00	0.230	61

Example 3:

in this embodiment, the graphene accounts for 90 wt.%, the polymer filament accounts for 2 wt.%, and the liquid silica gel accounts for 8 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 9.0;

the high molecular polymer used for wire drawing is PP;

the liquid silica gel is polydimethylsiloxane;

the shearing and wire drawing speed of the high-speed shearing machine is 1000 r/min; shearing time is 6 min;

adding liquid silica gel, and fully mixing to obtain a sheet with the thickness of 3 mm;

the curing temperature is 120 ℃;

the test shows that the thermal conductivity of the sample is 47.3W/(m K), and the results of the application thermal resistance and the compression resilience of the samples with different thicknesses are shown in the following table 2:

TABLE 2

Example 4:

in this embodiment, the graphene accounts for 60 wt.%, the polymer filaments accounts for 1 wt.%, and the liquid silica gel accounts for 39 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 0.5;

the high molecular polymer used for wire drawing is PS;

the liquid silica gel is alpha, omega-dihydroxy polydimethylsiloxane;

the shearing and wire drawing speed of the high-speed shearing machine is 30000 r/min; shearing time is 1 min;

adding liquid silica gel, and mixing to obtain sheet with thickness of 0.5 mm;

the curing temperature is 80 ℃;

the thermal conductivity of the sample was 20.9W/(m K), and the results of the applied thermal resistance and compression resilience of the samples with different thicknesses are shown in Table 3 below:

TABLE 3

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.030	/
0.50	0.060	68
			1.00	0.097	59
2.00	0.171	54

Example 5:

in this embodiment, the graphene accounts for 80 wt.%, the carbonaceous filament accounts for 3 wt.%, and the liquid silica gel accounts for 17 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 2.0;

the high molecular polymer used for wire drawing is PA;

the liquid silica gel is poly diphenyl siloxane;

the shearing and drawing speed of the high-speed shearing machine is 15000 r/min; shearing time is 3 min;

the temperature for converting the high molecular filament into the carbon filament is 600 ℃;

adding liquid silica gel, and fully mixing to obtain a sheet with the thickness of 2 mm;

the curing temperature is 85 ℃;

the test shows that the thermal conductivity of the sample is 36.3W/(m K), and the results of the application thermal resistance and the compression resilience of the samples with different thicknesses are shown in the following table 4:

TABLE 4

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.027	/
0.50	0.045	60
			1.00	0.066	52
2.00	0.109	48

Example 6:

in this embodiment, the graphene accounts for 70 wt.%, the carbon filament accounts for 5 wt.%, and the liquid silica gel accounts for 25 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 1.0;

the high molecular polymer used for wire drawing is PTFE;

the liquid silica gel is alpha, omega-dihydroxy polymethyl (3,3, 3-trifluoropropyl) siloxane;

the shearing and wire drawing speed of the high-speed shearing machine is 20000 r/min; shearing time is 2 min;

the temperature for converting the high molecular filament into the carbon filament is 3200 ℃;

adding liquid silica gel, and fully mixing to obtain a sheet with the thickness of 1 mm;

the curing temperature is 90 ℃;

the thermal conductivity of the sample was found to be 26.7W/(m K), and the results of the applied thermal resistance and compression resilience of the samples of different thicknesses are shown in Table 5 below:

TABLE 5

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.028	/
0.50	0.051	63
			1.00	0.079	58
2.00	0.137	51

Example 7:

in this embodiment, the graphene accounts for 55 wt.%, the polymeric filaments accounts for 0.9 wt.%, and the liquid silicone gel accounts for 44.1 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 1.5;

the high molecular polymer used for wire drawing is ABS;

the liquid silica gel is cyano-siloxysilane;

the jet mill has a pulverizing pressure of 3kgf/cm²(ii) a The vibration frequency is 15Hz or/and the feeding pressure is 3kgf/cm²；

Adding liquid silica gel, and mixing to obtain sheet with thickness of 2.5 mm;

the curing temperature is 90 ℃;

the thermal conductivity of the sample was 16.6W/(m K), and the results of the applied thermal resistance and compression resilience of the samples with different thicknesses are shown in table 6 below:

TABLE 6

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.032	/
0.50	0.070	70
			1.00	0.119	64
2.00	0.216	59

Example 8:

in this example, graphite flakes accounted for 65 wt.%, carbon filaments accounted for 3.5 wt.%, liquid silica gel accounted for 31.5 wt.%;

the ratio of the graphite flake diameter distribution between 10-100 μm and 100-1000 μm is 0.4;

the high molecular polymer used for wire drawing is PET;

the liquid silica gel is alpha, omega-diethyl polydimethylsiloxane;

the jet mill has a pulverizing pressure of 10kgf/cm²(ii) a The vibration frequency is 50Hz or/and the feeding pressure is 8kgf/cm²；

The temperature of the high molecular filament to be converted into the carbon filament is 2800 ℃;

adding liquid silica gel, and mixing to obtain sheet with thickness of 1.5 mm;

the curing temperature is 100 ℃;

the test shows that the thermal conductivity of the sample is 23.3W/(m K), and the results of the application thermal resistance and the compression resilience of the samples with different thicknesses are shown in the following table 7:

TABLE 7

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.031	/
0.50	0.058	60
			1.00	0.091	53
2.00	0.159	48

Example 9:

in this example, the graphene/graphite flake ratio is 70 wt.%, the polymeric filament ratio is 1 wt.%, and the liquid silica gel ratio is 29 wt.%;

the mass ratio of the graphene to the graphite flake is 1: 1;

the ratio of the graphene/graphite sheet diameter distribution between 10-100 μm and 100-1000 μm is 6.0;

the high molecular polymer used for wire drawing is PBT;

the liquid silica gel is polydimethylsiloxane-polydimethylsiloxane;

the jet mill has a pulverizing pressure of 5kgf/cm²(ii) a The vibration frequency is 20Hz or/and the feeding pressure is 4kgf/cm²；

Adding liquid silica gel, and mixing to obtain sheet with thickness of 0.5 mm;

the curing temperature is 50 ℃;

the thermal conductivity of the sample was found to be 26.4W/(m K), and the results of the applied thermal resistance and compression resilience of the samples of different thicknesses are shown in Table 8 below:

TABLE 8

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.030	/
0.50	0.053	62
			1.00	0.083	56
2.00	0.141	49

Example 10:

in this example, graphite flakes account for 75 wt.%, carbon filaments account for 4.5 wt.%, liquid silica gel accounts for 20.5 wt.%;

the ratio of the graphite flake diameter distribution between 10-100 μm and 100-1000 μm is 8.0;

the high molecular polymer used for wire drawing is PVDF;

the liquid silica gel is polydimethylsiloxane-polydimethylsiloxane;

the crushing pressure of the jet mill is 8kgf/cm²(ii) a The vibration frequency is 40Hz or/and the feeding pressure is 6kgf/cm²；

The temperature of the high molecular filament to the carbon filament is 2000 DEG C

Adding liquid silica gel, and mixing to obtain sheet with thickness of 1.5 mm;

curing at normal temperature;

the test results show that the thermal conductivity of the sample is 31.0W/(m K), and the results of the application thermal resistance and the compression resilience of the samples with different thicknesses are shown in the following table 9:

TABLE 9

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.029	/
0.50	0.049	58
			1.00	0.074	53
2.00	0.124	45

Example 11:

in this embodiment, the graphene accounts for 65 wt.%, the carbonaceous filament accounts for 4 wt.%, and the liquid silica gel accounts for 31 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 4.0;

the high molecular polymer used for wire drawing is POM-polyphenyl ether-polysulfone;

the liquid silica gel is polydimethylsiloxane-alpha, omega-dihydroxy polydimethylsiloxane;

the crushing pressure of the jet mill is 6kgf/cm²(ii) a The vibration frequency is 30Hz or/and the feeding pressure is 5kgf/cm²；

The temperature for transforming the high molecular filament into the carbon filament is 1000 DEG C

Adding liquid silica gel, and mixing to obtain sheet with thickness of 1.5 mm;

curing at normal temperature;

the thermal conductivity of the sample was 21.1W/(m K), and the results of the applied thermal resistance and compression resilience of the samples with different thicknesses are shown in table 10 below:

watch 10

Thickness (mm)	Using thermal resistance (K in)²/W)	Compression Resilience (%)
			0.10	0.032	/
0.50	0.061	64
			1.00	0.098	55
2.00	0.172	51

Comparative example 3:

in this embodiment, the graphene accounts for 40 wt.%, the carbonaceous filament accounts for 5 wt.%, and the liquid silica gel accounts for 55 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 3.0;

the high molecular polymer used for wire drawing is PVDF;

the liquid silica gel is polydimethylsiloxane;

the shearing and wire drawing speed of the high-speed shearing machine is 10000 r/min; shearing time is 0.5 min;

the temperature for transforming the high molecular filament into the carbon filament is 1500 DEG C

the curing temperature is 100 ℃;

the thermal conductivity of the sample was found to be 8.2W/(m K), and the results of the applied thermal resistance and compression resilience of the samples of different thicknesses are shown in Table 11 below:

TABLE 11

In the comparative example, the filling amount of the graphene is too small, the content of the liquid silica gel is too high, and the prepared heat conducting gasket is low in heat conductivity coefficient and high in heat resistance.

Comparative example 4:

in this embodiment, the graphene accounts for 95 wt.%, the polymer filament accounts for 0.5 wt.%, and the liquid silica gel accounts for 4.5 wt.%;

the high molecular polymer used for wire drawing is ABS;

the liquid silica gel is polydimethylsiloxane;

adding liquid silica gel, and mixing to obtain sheet with thickness of 1.5 mm;

the curing temperature is 120 ℃;

since the content of graphene used in the comparative example was too high and the content of liquid silica gel was too small, the obtained sample cracked and could not be molded.

Comparative example 5:

in this embodiment, the graphene accounts for 70 wt.%, the polymer filament accounts for 0.1 wt.%, and the liquid silica gel accounts for 29.9 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 7.0;

the high molecular polymer used for wire drawing is ABS;

the liquid silica gel is polydimethylsiloxane;

adding liquid silica gel, and mixing to obtain sheet with thickness of 1.5 mm;

the curing temperature is 120 ℃;

since the content of the high molecular polymer used in this comparative example was too small, a sufficient network structure could not be formed, and a good connection effect could not be formed between the graphenes, the obtained sample could not be molded.

Comparative example 6:

in this example, the graphite flakes account for 50 wt.%, the polymeric filaments account for 10 wt.%, and the liquid silicone gel accounts for 40 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 5.0;

the high molecular polymer used for wire drawing is ABS;

the liquid silica gel is polydimethylsiloxane;

the shearing rate of the high-speed shearing machine is 20000 r/min; shearing time is 2 min;

adding liquid silica gel, and mixing to obtain sheet with thickness of 1.5 mm;

the curing temperature is 120 ℃;

the thermal conductivity of the sample was 15.8W/(m K), and the results of the applied thermal resistance and compression resilience of the samples with different thicknesses are shown in table 12 below:

TABLE 12

Thickness (mm)	Using thermal resistance (K in)²/W)
		0.10	0.310
0.50	0.348
		1.00	0.397
2.00	0.494

Because the proportion of the high molecular polymer used in the comparative example is too high, the hardness of the obtained sample is higher, and the application thermal resistance is higher.

Comparative example 7:

in this embodiment, the graphene accounts for 50 wt.%, the carbon filament accounts for 3 wt.%, and the liquid silica gel accounts for 47 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 15.0;

the high molecular polymer used for wire drawing is PVDF;

the liquid silica gel is polydimethylsiloxane;

the shearing rate of the high-speed shearing machine is 10000 r/min; shearing time is 1 min;

the temperature for converting the high molecular filament into the carbon filament is 2500 DEG C

the curing temperature is 100 ℃;

the thermal conductivity of the sample was found to be 8.6W/(m K), and the results of the applied thermal resistance and compression resilience of the samples of different thicknesses are shown in Table 13 below:

watch 13

Thickness (mm)	Using thermal resistance (K in)²/W)
		0.10	0.058
0.50	0.130
		1.00	0.220
2.00	0.401

Due to the fact that the proportion of 10-100 mu m of graphene in the distribution of the sheet diameter is too large, the obtained heat conduction gasket is small in heat conduction coefficient and large in application heat resistance.

Comparative example 8:

in this embodiment, the graphene accounts for 80 wt.%, the polymer filament accounts for 3 wt.%, and the liquid silica gel accounts for 17 wt.%;

the ratio of the graphene sheet diameter distribution between 10-100 μm and 100-1000 μm is 0.05;

the high molecular polymer used for wire drawing is PVDF;

the liquid silica gel is polydimethylsiloxane;

the curing temperature is 100 ℃;

the graphene sheets with the sheet diameter distribution of 100-1000 mu m account for too large, so that the prepared heat-conducting gasket is not easy to form.

Comparative example 9:

in this embodiment, the graphene accounts for 60 wt.%, the polymeric filament accounts for 1 wt.%, and the liquid silica gel accounts for 39 wt.%;

the high molecular polymer used for wire drawing is PVDF;

the liquid silica gel is polydimethylsiloxane;

adding liquid silica gel, mixing, and directly making into heat-conducting gasket with thickness of 0.1mm, 0.5mm, 1mm, 2 mm;

the curing temperature is 100 ℃;

the thermal conductivity of the samples was found to be 4.3W/(m K), and the results of the applied thermal resistance and compression resilience of the samples of different thicknesses are shown in Table 14 below:

TABLE 14

Thickness (mm)	Using thermal resistance (K in)²/W)
		0.10	0.536
0.50	0.680
		1.00	0.861
2.00	1.221

In the comparative example, the sheets are not stacked layer by layer, the graphene is mainly arranged along the transverse direction, and the prepared heat conducting gasket is low in heat conductivity coefficient and high in application heat resistance.

Comparative example 10:

in this embodiment, the graphene accounts for 70 wt.%, the polymer filament accounts for 2 wt.%, and the liquid silica gel accounts for 28 wt.%;

the high molecular polymer used for wire drawing is PVA;

the shearing rate of the high-speed shearing machine is 500 r/min; shearing time is 6 min;

the curing temperature is 100 ℃;

due to the fact that the adopted shearing rate is too low, the high molecular polymer cannot be drawn to form an effective network structure, and the prepared heat conducting gasket cannot be formed.

Comparative example 11:

the high molecular polymer used for wire drawing is PTFE;

the shearing rate of the high-speed shearing machine is 60000 r/min; shearing time is 1 min;

the curing temperature is 100 ℃;

due to the fact that the adopted shearing rate is too large, the graphene sheet can be smashed into extremely small fragments, the specific surface area can be remarkably increased, the oil absorption value can be remarkably improved, the mechanical property of a sample obtained under the existing binder proportion is poor, and the sample can be formed only by adding a large amount of binders.

Comparative example 12:

in this example, graphite flakes account for 60 wt.%, carbon filaments account for 2 wt.%, liquid silica gel accounts for 38 wt.%;

the ratio of the graphite flake diameter distribution between 10-100 μm and 100-1000 μm is 1.0;

the high molecular polymer used for wire drawing is POM;

the liquid silica gel is polydimethylsiloxane;

the crushing pressure of the jet mill is 1kgf/cm²(ii) a The vibration frequency is 30Hz or/and the feeding pressure is 5kgf/cm²；

The temperature for transforming the high molecular filament into the carbon filament is 1800 DEG C

the curing temperature is 100 ℃;

because the adopted jet milling pressure is too small, the high molecular polymer can not be effectively drawn into a good filamentous network, and after heat treatment, the filler/carbon filaments can not form a good network structure, so that the prepared heat-conducting gasket has poor mechanical property and can not be formed.

Comparative example 13:

in this example, graphite flakes account for 80 wt.%, carbon filaments account for 2 wt.%, liquid silica gel accounts for 18 wt.%;

the ratio of the graphite flake diameter distribution between 10-100 μm and 100-1000 μm is 2.0;

the high molecular polymer used for wire drawing is PET;

the liquid silica gel is polydimethylsiloxane;

the crushing pressure of the jet mill is 15kgf/cm²(ii) a The vibration frequency is 30Hz or/and the feeding pressure is 5kgf/cm²(ii) a The high molecular polymer used for wire drawing is 1600 DEG C

the curing temperature is 100 ℃;

because the crushing pressure is too large, the graphite sheet can be crushed into extremely small fragments, the specific surface area can be obviously increased, the oil absorption value can be obviously improved, the mechanical property of the obtained sample is poor under the existing binder proportion, and the sample can be formed only by adding a large amount of binders.

Comparative example 14:

in this example, graphite flakes account for 60 wt.%, polymeric filaments account for 2 wt.%, liquid silicone gel accounts for 38 wt.%;

the high molecular polymer used for wire drawing is PET;

the liquid silica gel is polydimethylsiloxane;

the crushing pressure of the jet mill is 6kgf/cm²(ii) a The vibration frequency is 10Hz or/and the feeding pressure is 2kgf/cm²；

the curing temperature is 100 ℃;

because vibration frequency or/and feeding pressure undersize, the graphite flake dwell time overlength in fluid energy mill leads to a large amount of graphite flakes to be smashed into minimum size, and specific surface area can show the increase, and the oil absorption value can show and promote, and the sample mechanical properties that obtains are relatively poor under the current binder proportion, need add a large amount of binders just can the shaping.

Comparative example 15:

the high molecular polymer used for wire drawing is PET;

the liquid silica gel is polydimethylsiloxane;

the crushing pressure of the jet mill is 6kgf/cm²(ii) a The vibration frequency is 60Hz or/and the feeding pressure is 10kgf/cm²；

the curing temperature is 100 ℃;

due to the fact that the vibration frequency or/and the feeding pressure are/is too large, the residence time of the graphite flakes and the high molecular polymer in the jet mill is too short, the high molecular polymer cannot be effectively drawn, a three-dimensional network structure which is well combined with the graphene flakes cannot be formed, and the prepared sample cannot be formed.

Comparative example 16:

in this example, graphite flakes account for 60 wt.%, the filamentous network accounts for 2 wt.%, and liquid silica gel accounts for 38 wt.%;

the high molecular polymer used for wire drawing is PET;

the liquid silica gel is polydimethylsiloxane;

Adding liquid silica gel, and mixing to obtain sheet with thickness of 0.1 mm;

due to the thin thickness of the prepared sheet, the stacking of the sheet is not easy to realize.

Comparative example 17:

in this example, the graphite flakes account for 50 wt.%, the polymeric filaments account for 2 wt.%, and the liquid silicone gel accounts for 48 wt.%;

the ratio of the graphite flake diameter distribution between 10-100 μm and 100-1000 μm is 4.0;

the high molecular polymer used for wire drawing is PET;

the liquid silica gel is polydimethylsiloxane;

Adding liquid silica gel, and fully mixing to obtain a sheet with the thickness of 5 mm;

the curing temperature is 100 ℃;

the thermal conductivity of the sample was found to be 5.2W/(m K), and the applied thermal resistance results for samples of different thicknesses are shown in Table 15 below:

watch 15

Thickness (mm)	Using thermal resistance (K in)²/W)
		0.10	0.460
0.50	0.579
		1.00	0.728
2.00	1.026

Because the prepared sheet is thick, the good orientation of the graphite flake can not be realized, and the prepared heat conduction gasket has low heat conductivity coefficient and high heat resistance.

Comparative example 18

In this embodiment, the graphene accounts for 65 wt.%, the polymer filament accounts for 2 wt.%, and the liquid silica gel accounts for 33 wt.%;

the graphene sheet diameter is distributed in the range of 1-10 μm;

jet millingThe pressure of the mechanical grinding is 6kgf/cm²(ii) a The vibration frequency is 30Hz or/and the feeding pressure is 5kgf/cm²；

Adding liquid silica gel, and mixing to obtain sheet with thickness of 1.5 mm;

curing at 100 ℃;

due to the fact that the adopted graphene is too small in sheet diameter, the specific surface area can be remarkably increased, the oil absorption value can be remarkably improved, the mechanical property of a sample obtained under the existing binder proportion is poor, and the sample can be formed only by adding a large amount of binders.

Comparative example 19

In this embodiment, the graphene accounts for 65 wt.%, the carbonaceous filament accounts for 2 wt.%, and the liquid silica gel accounts for 33 wt.%;

the graphene has the sheet diameter distribution of 1000-2000 mu m;

the high molecular polymer used for wire drawing is 1200 ℃;

Adding liquid silica gel, and mixing to obtain sheet with thickness of 1.5 mm;

curing at 100 ℃;

as the adopted graphene sheet has overlarge diameter and is difficult to fill in the adhesive, the obtained sample has poor mechanical property and is easy to crack.

In the embodiment of the invention, the adopted liquid silica gel is taken as a representative of the adhesive, and other types of adhesives are also applicable.

According to the heat conduction gasket, the two-dimensional heat conduction filler in the heat conduction gasket is highly oriented along the thickness direction. The two-dimensional heat conduction graphene sheet or graphite sheet is preferably selected as the heat conduction filler, the liquid binder is used as the binder, and the high-molecular filament and/or the carbon filament are/is used as the reinforcing material, so that the heat conduction gasket with high heat conduction performance in the thickness direction is prepared. The invention can adopt millimeter-scale two-dimensional heat-conducting filler, the wire-drawing high-molecular polymer forms a wire-like network structure and is tightly combined with the two-dimensional heat-conducting filler to form a filler/high-molecular network structure through the high-strength shearing action, the filler/carbon wire network structure can be obtained through further heat treatment, the two-dimensional filler is tightly connected, the internal binding force is fully improved, and the content of the two-dimensional heat-conducting filler reaches the ultrahigh content of 90 wt.%. In the orientation of the two-dimensional heat-conducting filler, the preparation method of the heat-conducting gasket firstly realizes the highly directional arrangement of the two-dimensional heat-conducting filler in the plane direction in a mode of pressing a sheet; then, the sheets are stacked layer by layer, pressed into a block and cured to be molded, and the internal network structure and the binder interact with each other, so that the binding force in the block can be obviously improved; and finally, cutting the block body into a plurality of pieces along the height direction of the block body to obtain the heat-conducting gasket, wherein the two-dimensional heat-conducting filler in the gasket is highly oriented along the thickness direction and has higher heat-conducting performance and good compression resilience in the direction.

As described above, according to the embodiments of the present invention, various changes and modifications can be made by those skilled in the art without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims

1. The heat conduction gasket is characterized by comprising heat conduction fillers and a reinforcing material, wherein the heat conduction fillers are two-dimensional heat conduction fillers arranged along the thickness direction of the heat conduction gasket, the reinforcing material is filaments formed by drawing high-molecular polymers and/or carbon filaments formed by drawing the high-molecular polymers after heat treatment, and the two-dimensional heat conduction fillers are tightly connected by the high-molecular filaments and/or the carbon filaments to form a filler/high-molecular and/or filler/carbon filament network structure.

2. The gasket of claim 1, further comprising a binder, wherein the filler/polymer and/or filler/carbon filament network structure penetrates through the binder and is tightly bonded to the binder, preferably, the binder comprises one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin and organic silica gel, further preferably, the binder is liquid organic silica gel; preferably, the proportion of binder is 5 wt.% to 49.7 wt.%, further preferably, the proportion of binder is 15 wt.% to 39 wt.%.

3. A heat conducting gasket according to claim 1, wherein said two-dimensional heat conducting filler comprises graphene, graphite flakes, boron nitride, aluminum nitride, silicon carbide, preferably graphene, graphite flakes, and wherein said two-dimensional heat conducting filler comprises from 50 wt.% to 90 wt.%, preferably wherein said two-dimensional heat conducting filler comprises from 60 wt.% to 80 wt.%.

4. A heat conducting pad according to claim 1, wherein said high molecular polymer accounts for 0.3-5 wt.%, preferably said high molecular polymer accounts for 1-3 wt.%.

5. The heat conducting gasket according to claim 1, wherein the two-dimensional heat conducting filler comprises a two-dimensional heat conducting filler with a sheet diameter in the range of 10-1000 μm, preferably the ratio of the sheet diameter distribution of the two-dimensional heat conducting filler between 10-100 μm and 100-1000 μm is 0.1-9.0, and further preferably the ratio of the sheet diameter distribution of the two-dimensional heat conducting filler between 10-100 μm and 100-1000 μm is 0.5-2.0.

6. The heat conducting gasket of claim 1, wherein the high molecular polymer is preferably a wiredrawing high molecular polymer, preferably the high molecular polymer comprises one or more of PE, PP, PS, PA, PTFE, ABS, PET, PBT, PVDF, POM, polyphenylene oxide and polysulfone.

7. The thermal pad of claim 2, wherein the liquid silicone gum comprises one or more of polydimethylsiloxane, α, ω -dihydroxypolydimethylsiloxane, polydiphenylsiloxane, α, ω -dihydroxypolymethyl (3,3, 3-trifluoropropyl) siloxane, cyanosiloxysilane, and α, ω -diethylpolydimethylsiloxane.

8. A method for preparing a heat-conducting gasket is characterized by comprising the following steps:

fully mixing the heat-conducting filler and the high molecular polymer;

converting a high molecular polymer into filaments by high-speed shearing, wherein the filaments connect two-dimensional heat-conducting fillers to form a filler/high molecular network structure; the filler/polymer network structure can be further subjected to heat treatment to change polymer filaments into carbon filaments, and the carbon filaments are tightly connected with the two-dimensional heat-conducting filler to form the filler/carbon filament network structure;

preparing a filler/macromolecule and/or filler/carbon filament network structure into a sheet, wherein two-dimensional heat-conducting fillers in the sheet are arranged along the transverse direction;

laminating the sheets, pressing the laminated sheets into a block, and curing and forming;

and cutting the solidified and molded block into a plurality of thin slices along the direction of the stacking height to obtain the heat-conducting gasket with the two-dimensional heat-conducting filler arranged longitudinally.

9. The method according to claim 8, wherein the step of forming the filler/polymer and/or filler/carbon filament network structure into a sheet further comprises: and fully mixing the filler/polymer and/or filler/carbon filament network structure with the binder, so that the filler/polymer and/or filler/carbon filament network structure penetrates through the binder and is tightly combined with the binder.

10. The method for preparing the heat conducting gasket according to claim 8, wherein the step of converting the high molecular polymer into filaments by shearing and connecting the two-dimensional heat conducting filler comprises converting the high molecular polymer into filaments by using a high speed shearing machine or an air flow pulverizer, preferably, the high speed shearing machine uses a blade type shearing device rotating at a high speed, the rotating speed is 1000-50000r/min, the shearing time is 0.5-6min, and furtherOne step preferably, the rotating speed of the high-speed shearing machine is 15000-30000r/min, and the shearing time is 1-3 min; preferably, the crushing pressure of the jet mill is 3-10 kg-f/cm²Further preferably, the pulverization pressure of the jet mill is 5 to 8kg · f/cm²(ii) a Preferably, the vibration frequency of the feeder of the jet mill is 15-50 Hz; and/or the feeding pressure is 3-8 kg.f/cm²Further preferably, the vibration frequency of the feeder of the jet mill is 20-40 Hz; and/or the feed pressure is 4-6 kg.f/cm²。

11. The method for preparing a heat conductive pad according to claim 8, wherein the temperature for transforming the filler/polymer network structure into the filler/carbon fiber network structure is 600-3200 ℃, preferably 1000-2800 ℃.

12. The method for preparing a thermal pad according to claim 8, wherein the thickness of the sheet is 0.2-3.0mm, preferably 0.5-2.0 mm.

13. The method for manufacturing a thermal pad according to claim 8, wherein the step of curing and molding includes: the heat curing or the normal temperature curing is carried out, preferably, the temperature of the heat curing is below 150 ℃, and further preferably, the temperature of the heat curing is below 120 ℃.

14. The method for manufacturing a thermal gasket according to claim 8, wherein the step of cutting the thermal gasket into the plurality of thin pieces in the direction of the stack height comprises:

the solidified and shaped block is cut into a plurality of thin sheets along the direction of the stacking height by wire cutting, laser cutting, ultrasonic cutting, blade cutting, freeze cutting, vibration cutting, or ultrasonic-freeze cutting.

15. An electronic device comprising a heat source, a heat dissipating member, and a heat conductive pad sandwiched between the heat source and the heat dissipating member, wherein the heat conductive pad is the heat conductive pad according to any one of claims 1 to 7 or produced by the method according to any one of claims 8 to 14.