A single-component thermally conductive gel and a preparation method thereof

Abstract

The present invention relates to a single-component thermally conductive gel and a preparation method thereof, comprising the following raw materials by weight, which are cross-linked by mixing: 50-100 parts of vinyl silicone oil, 5-10 parts of catalyst, 5-10 parts of cross-linking agent, 5-10 parts of chain extender, 1-5 parts of ethynyl cyclohexanol, 1-5 parts of graphene oxide, and 0-200 parts of thermally conductive filler; firstly, graphene oxide is mixed with ethynyl cyclohexanol and stripped at the same time to obtain a single-layer graphene oxide dispersion, and then mixed evenly with the remaining materials, and then the thermally conductive filler is added, and the single-layer graphene oxide is reduced to a single-layer graphene while mixing and cross-linking under mixing, vacuuming and heating conditions to generate addition reaction, and the single-layer graphene oxide is reduced to a single-layer graphene, that is, the single-component thermally conductive gel is obtained. The thermal conductivity of the single-component thermally conductive gel of the present invention is greater than 5W / m·K, and has good flow processing performance.

Description

Technical Field

[0001] The invention relates to the technical field of thermal conductive materials, and in particular to a single-component thermal conductive gel and a preparation method thereof. Background Art

[0002] With the development of science and technology, electronic components, electrical power circuit modules, large-scale integrated circuits and other fields have further achieved high performance, high reliability and miniaturization, and the working efficiency has been continuously improved. Therefore, the heat generated by each component during operation has also increased sharply. However, as the working temperature of electronic components increases, the speed at which their working life decreases will also increase. Therefore, quickly dissipating heat has become one of the key factors for the safe and stable operation of equipment.

[0003] Graphene is a new material with carbon atoms connected by sp2 hybridization tightly stacked into a single-layer two-dimensional honeycomb lattice structure. The thermal conductivity of graphene is as high as 5300W / m·K, which is higher than that of carbon nanotubes and diamonds. Its electron mobility exceeds 15000cm at room temperature. 2 / Vs. Since the surface of single-layer graphene is inert and the specific surface area is 500g / m 2 The above, and the oil absorption value is very high, its direct addition in the polymer system will cause the viscosity of the mixed system to rise quickly, making processing difficult and unable to achieve the effect of uniform mixing, and if the amount of thermal conductive filler added is too small, the purpose of high thermal conductivity cannot be achieved.

[0004] Therefore, how to better add high thermal conductivity single-layer graphene to the polymer system and efficiently construct a thermal conduction channel is an important research direction.

[0005] Prior art CN 112375392 A discloses a method for preparing a graphene thermally conductive interface material, which first prepares graphene oxide composite hollow glass microspheres / polymer hollow microspheres, then adds them to fibers, etc., and performs reduction treatment on them to obtain reduced graphene oxide composite thermally conductive fillers. The process is complicated and requires an additional step of reducing graphene oxide. In addition, the amount of composite thermally conductive fillers added is relatively large. The thermal conductivity of the thermally conductive material finally obtained is about 3-4 W / m·K, and its thermal conductivity effect is still poor. Summary of the invention

[0006] In order to solve the technical problem of uniform dispersion of single-layer graphene in a polymer system and the technical problem of poor thermal conductivity of the material, a single-component thermal conductive gel and a preparation method thereof are provided. The present invention can evenly disperse graphene in silica gel, and the material system is easy to process; in addition, through the synergistic effect of graphene and other dimensional thermal conductive materials, a thermal conductive channel can be efficiently constructed, so that heat can be released quickly.

[0007] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A single-component thermally conductive gel, comprising the following raw materials in parts by weight, mixed and cross-linked:

[0009]

[0010] Before mixing and cross-linking, the graphene oxide is firstly subjected to exfoliation treatment to obtain a single-layer graphene oxide. During the mixing and cross-linking process, an addition reaction occurs and the single-layer graphene oxide is reduced to a single-layer graphene.

[0011] Furthermore, the vinyl silicone oil is monovinyl silicone oil and / or polyvinyl silicone oil, wherein the vinyl content is 0.5-5wt% and the viscosity is 100-1000mPa·s; the particle size of the graphene oxide is 0.1-20μm, and the total content of carbon and oxygen elements is ≥99wt%.

[0012] Furthermore, the catalyst is a platinum catalyst, which contains 0.1-5wt% platinum; the cross-linking agent is a side hydrogen-containing silicone oil with a hydrogen content of 0.05-5wt% and a viscosity of 30-300mPa·s; the chain extender is a single-end hydrogen-containing silicone oil and / or a double-end hydrogen-containing silicone oil, wherein the hydrogen content is 0.05-5wt% and the viscosity is 30-300mPa·s.

[0013] Furthermore, the thermal conductive filler includes one or more of spherical aluminum oxide, zinc oxide nanorods, silicon carbide whiskers, hexagonal aluminum nitride, and flaky boron nitride; wherein the zinc oxide nanorods have a length of 1-10 μm and a diameter of ≤100 nm; and the silicon carbide whiskers have a diameter of 0.1-1 μm and a length of 10-50 μm.

[0014] Preferably, the single-component thermally conductive gel comprises the following raw materials in parts by weight, which are mixed and cross-linked:

[0015]

[0016] The method for preparing the above-mentioned single-component thermally conductive gel comprises the following steps:

[0017] (1) mixing graphene oxide and ethynyl cyclohexanol and performing an exfoliation treatment, wherein the graphene oxide is exfoliated during the mixing process to obtain a single-layer graphene oxide dispersion;

[0018] (2) uniformly mixing a portion of the vinyl silicone oil with the catalyst to obtain a first material;

[0019] The remaining vinyl silicone oil is mixed evenly with the cross-linking agent, the chain extender, and the monolayer graphene oxide dispersion to obtain a second material;

[0020] Mixing the first material and the second material to obtain a base material;

[0021] (3) Adding a thermally conductive filler into the base material, kneading and cross-linking under mixing, vacuuming and heating conditions to generate an addition reaction, while the single-layer graphene oxide is reduced to a single-layer graphene, to obtain a single-component thermally conductive gel.

[0022] Furthermore, the mixing speed in steps (1)-(3) is 10-50 rpm and the mixing time is 30-100 min. It can be conventional mechanical stirring mixing or mixing in an open mill or internal mixer without heating, the purpose of which is to achieve uniform mixing. The stripping treatment in step (1) includes one or more combinations of ultrasonic treatment, grinding and dispersion treatment, and high-pressure homogenization treatment.

[0023] Furthermore, the heating temperature during the mixing and cross-linking is 160-220° C. and the reaction time is 0.5-3 h.

[0024] Beneficial technical effects:

[0025] Although single-layer graphene has high thermal conductivity, it is extremely difficult to add it to a silicone oil system. The present invention directly disperses graphene oxide powder in a reagent (ethynyl cyclohexanol) in the system, without the need to add additional solvents or reagents to increase the post-processing process, and first opens the graphene oxide sheet by homogenization, ultrasound, grinding and other methods to prepare a single-layer graphene oxide dispersion, which is easy to add to the silicone oil system for material mixing;

[0026] In the present invention, there is no need to perform a separate reduction process on the added graphene oxide, and no additional process is required. The catalytic addition reaction of the vinyl silicone oil occurs in the subsequent mixing and cross-linking stage, and the monolayer graphene oxide is reduced to a monolayer graphene in this process, thereby avoiding the processing difficulties and uneven dispersion problems caused by directly adding graphene. By using the method of the present invention to add graphene in situ, a thermally conductive gel that is evenly dispersed and easy to process can be obtained, and with the aid of a thermally conductive filler, costs are saved and it is suitable for industrial production.

[0027] In addition, the present invention compounds high thermal conductive fillers of different dimensions (zero-dimensional spherical aluminum oxide, one-dimensional zinc oxide nanorods, and two-dimensional graphene). Since the single-layer graphene oxide has been evenly dispersed in the matrix in the early stage, thermal conductive fillers of different dimensions are subsequently added to the matrix, and rod-shaped and spherical thermal conductive fillers can be filled between a small amount of flaky graphene oxide, thereby quickly forming a thermal conductive path to achieve the purpose of high thermal conductivity. Although the added amount of aluminum oxide and zinc oxide is larger than that of graphene, the thermal conductive gel maintains good extrusion performance while having excellent thermal conductivity. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Unless otherwise specifically stated, the numerical value set forth in these embodiments does not limit the scope of the present invention. The technology and method known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology and method should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values.

[0030] In addition, it should be noted that the use of terms such as "first" and "second" to limit materials is only to facilitate the distinction between the substances obtained in each step. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0031] The experimental methods in the following examples without specifying specific conditions are usually measured according to national standards; if there is no corresponding national standard, it is carried out according to the general international standards or the standard requirements proposed by relevant enterprises. Unless otherwise specified, all parts are by weight and all percentages are by weight.

[0032] Example 1

[0033] A single-component thermally conductive gel, comprising the following raw materials in parts by weight:

[0034] 50 parts of vinyl silicone oil, 5 parts of catalyst, 5 parts of cross-linking agent, 5 parts of chain extender, 1 part of ethynyl cyclohexanol, 2 parts of graphene oxide powder, and 80 parts of thermal conductive filler;

[0035] The vinyl silicone oil is a monovinyl silicone oil with a vinyl content of 0.5wt% and a viscosity of 100mPa·s; the catalyst is a platinum catalyst with a platinum content of 0.1wt%; the cross-linking agent is a side hydrogen-containing silicone oil with a hydrogen content of 0.05wt% and a viscosity of 30mPa·s; the chain extender is a single-end hydrogen-containing silicone oil with a hydrogen content of 0.05wt% and a viscosity of 30mPa·s; the thermal conductive filler is 40 parts of spherical alumina and 40 parts of zinc oxide nanorods (the length of the zinc oxide nanorods is 1-10μm and the diameter is ≤100nm).

[0036] The method for preparing the above-mentioned single-component thermally conductive gel comprises the following steps:

[0037] (1) After weighing in proportion, graphene oxide and ethynyl cyclohexanol are mixed, and during the mixing process, the graphene oxide is exfoliated by ultrasound to obtain a single-layer graphene oxide dispersion;

[0038] (2) uniformly mixing a portion of the vinyl silicone oil with the catalyst to obtain a first material;

[0039] The remaining vinyl silicone oil is mixed evenly with the cross-linking agent, the chain extender, and the monolayer graphene oxide dispersion to obtain a second material;

[0040] Mixing the first material and the second material to obtain a base material;

[0041] (3) Adding a thermally conductive filler to the base material, placing the base material in a double planetary mixer, stirring at a speed of 10 rpm for half an hour, and then evacuating the mixture. The mixture is heated to 200° C. for mixing and cross-linking reaction for 2 hours. During the addition reaction, the single-layer graphene oxide is reduced to a single-layer graphene, thereby obtaining a single-component thermally conductive gel.

[0042] Example 2

[0043] A single-component thermally conductive gel, comprising the following raw materials in parts by weight:

[0044] 100 parts of vinyl silicone oil, 10 parts of catalyst, 10 parts of cross-linking agent, 10 parts of chain extender, 5 parts of ethynyl cyclohexanol, 4 parts of graphene oxide powder, and 200 parts of thermal conductive filler;

[0045] The vinyl silicone oil is a polyvinyl silicone oil with a vinyl content of 5wt% and a viscosity of 1000mPa·s; the catalyst is a platinum catalyst with a platinum content of 5wt%; the cross-linking agent is a side hydrogen-containing silicone oil with a hydrogen content of 5wt% and a viscosity of 300mPa·s; the chain extender is a single-end hydrogen-containing silicone oil with a hydrogen content of 5wt% and a viscosity of 300mPa·s; the thermal conductive filler is 80 parts of spherical alumina and 120 parts of zinc oxide nanorods (the length of the zinc oxide nanorods is 1-10μm and the diameter is ≤100nm).

[0046] The method for preparing the above-mentioned single-component thermally conductive gel comprises the following steps:

[0047] (1) After weighing in proportion, graphene oxide and ethynyl cyclohexanol are mixed, and the mixing process is grinded and dispersed by a nano sand mill, so that the graphene oxide is peeled off into a single layer of graphene oxide, and a single layer of graphene oxide dispersion is obtained;

[0048] (2) uniformly mixing a portion of the vinyl silicone oil with the catalyst to obtain a first material;

[0049] The remaining vinyl silicone oil is mixed evenly with the cross-linking agent, the chain extender, and the monolayer graphene oxide dispersion to obtain a second material;

[0050] Mixing the first material and the second material to obtain a base material;

[0051] (3) Adding a thermally conductive filler to the base material, placing the base material in a double planetary mixer, stirring at a speed of 50 rpm for 100 min, and then evacuating the mixture, heating the mixture to 200° C. for 2 hours to carry out a mixing and cross-linking reaction. While the addition reaction occurs, the single-layer graphene oxide is reduced to a single-layer graphene, thereby obtaining a single-component thermally conductive gel.

[0052] Example 3

[0053] A single-component thermally conductive gel, comprising the following raw materials in parts by weight:

[0054] 100 parts of vinyl silicone oil, 8 parts of catalyst, 8 parts of cross-linking agent, 8 parts of chain extender, 8 parts of ethynyl cyclohexanol, 5 parts of graphene oxide powder, and 150 parts of thermal conductive filler;

[0055] The vinyl silicone oil is a polyvinyl silicone oil with a vinyl content of 2wt% and a viscosity of 500mPa·s; the catalyst is a platinum catalyst with a platinum content of 2wt%; the cross-linking agent is a side hydrogen-containing silicone oil with a hydrogen content of 2wt% and a viscosity of 150mPa·s; the chain extender is a single-end hydrogen-containing silicone oil with a hydrogen content of 2wt% and a viscosity of 150mPa·s; the thermal conductive filler is 50 parts of spherical alumina and 100 parts of zinc oxide nanorods (the length of the zinc oxide nanorods is 1-10μm and the diameter is ≤100nm).

[0056] The method for preparing the above-mentioned single-component thermally conductive gel comprises the following steps:

[0057] (1) After weighing in proportion, graphene oxide and ethynyl cyclohexanol are mixed, and a homogenizer is used for high-pressure homogenization during the mixing process, so that the graphene oxide is peeled off into a single layer of graphene oxide, and a single layer of graphene oxide dispersion is obtained;

[0058] (2) uniformly mixing a portion of the vinyl silicone oil with the catalyst to obtain a first material;

[0059] The remaining vinyl silicone oil is mixed evenly with the cross-linking agent, the chain extender, and the monolayer graphene oxide dispersion to obtain a second material;

[0060] Mixing the first material and the second material to obtain a base material;

[0061] (3) Adding a thermally conductive filler to the base material, placing the base material in a double planetary mixer, stirring at a speed of 30 rpm for 1 hour, and then evacuating the mixture. The mixture is heated to 200° C. for 2 hours to perform a mixing and cross-linking reaction. During the addition reaction, the single-layer graphene oxide is reduced to a single-layer graphene, thereby obtaining a single-component thermally conductive gel.

[0062] Example 4

[0063] The composition and preparation method of the single-component thermally conductive gel of this embodiment are the same as those of Embodiment 1, except that no thermally conductive filler is added.

[0064] Comparative Example 1

[0065] The composition and preparation method of the single-component thermally conductive gel of this embodiment are the same as those of Example 1, except that graphene oxide and thermally conductive filler, as well as the subsequent step (1) are not added. This comparative example is a blank comparison.

[0066] Comparative Example 2

[0067] The composition and preparation method of the single-component thermally conductive gel of this embodiment are the same as those of Example 1, except that graphene oxide and the subsequent step (1) are not added. In this comparative example, there is only thermally conductive filler.

[0068] Comparative Example 3

[0069] The composition and preparation method of the single-component thermally conductive gel of this embodiment are the same as those of Embodiment 1, except that the thermally conductive filler is entirely aluminum oxide.

[0070] Comparative Example 4

[0071] The composition and preparation method of the single-component thermally conductive gel of this embodiment are the same as those of Embodiment 1, except that the thermally conductive filler is all zinc oxide.

[0072] Comparative Example 5

[0073] The composition and preparation method of the single-component thermal conductive gel of this embodiment are the same as those of embodiment 1, except that graphene oxide and the subsequent step (1) are not added, but the single-layer graphene is directly mixed and cross-linked with other raw materials. This comparative example is a direct mixing method.

[0074] Comparative Example 6

[0075] The thermally conductive gel was prepared using the formula of Example 2 in CN 112375392 A.

[0076] The formulations of the above examples are shown in Table 1 below.

[0077] Table 1 Examples and Comparative Examples

[0078]

[0079] (Note: In the table, the thermal conductive fillers in Examples 1-3 and Comparative Example 2 are spherical aluminum oxide and zinc oxide nanorods, the thermal conductive fillers in Comparative Example 3 are all spherical aluminum oxide, and the thermal conductive fillers in Comparative Example 4 are all zinc oxide nanorods)

[0080] The thermal conductivity and gel extrusion rate of the above examples were tested, and the results are shown in Table 2. The thermal conductivity test method was tested using the DRL-III thermal conductivity tester of Xiangtan Xiangyi Instrument. The extrusion rate test conditions were 30cc tube, 90psi, 0.130 model needle (inner diameter 2.42mm), and the mass of thermally conductive gel extruded in 1 minute.

[0081] Table 2 Examples and Comparative Examples Data

[0082]

[0083] As shown in Table 2, Comparative Example 1 is a blank comparison. Example 4 of the present invention can achieve a thermal conductivity of 1.6 W / m·K by adding only 2 parts by weight to Comparative Example 1, which has good thermal conductivity, but the extrusion rate is relatively large. Comparative Example 2 only adds 80 parts by weight of spherical and rod-shaped thermal conductive fillers to Comparative Example 1, which can achieve a thermal conductivity of 3.0 W / m·K; and the thermal conductive gel formed in situ with a single layer of graphene by the method of the present invention can achieve a thermal conductivity of 5.4 W / m·K, which has the effect of 1+1>2. The improvement of the graphene addition method has a significant effect on improving the thermal conductivity of the material.

[0084] Comparative Example 5 is a direct blending method of graphene. Since adding graphene directly to silicone oil causes processing difficulties, graphene and thermally conductive fillers are unevenly dispersed, which greatly affects the thermal conductivity. Comparative Example 6 is a thermally conductive material prepared using the formula of Example 2 in CN112375392 A, which additionally adds a process for reducing graphene oxide. The process is complicated, and the amount of composite thermally conductive filler added (the weight ratio of composite thermally conductive filler to vinyl silicone oil is 2: 1) is more than that of Example 1 of the present invention (the weight ratio of the total amount of thermally conductive filler to vinyl silicone oil is 1.6: 1). Under the premise, its thermal conductivity is worse than that of Example 1 of the present invention. The method of in-situ generation of graphene in the present invention can facilitate the processing of graphene and silicone oil system, and can make graphene evenly dispersed, and the thermal conductivity is better. The present invention does not need to add an additional step of separate reduction, and reduces graphene oxide while cross-linking vinyl silicone oil, saving process and cost.

[0085] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a single-component thermally conductive gel, characterized in that: The single-component thermal conductive gel is made by mixing and cross-linking the following raw materials in parts by weight: The zinc oxide nanorods have a length of 1-10 μm and a diameter of ≤100 nm; Before mixing and cross-linking, the graphene oxide is firstly subjected to exfoliation treatment to obtain a single-layer graphene oxide. During the mixing and cross-linking process, an addition reaction occurs and the single-layer graphene oxide is reduced to a single-layer graphene. The steps include: (1) mixing graphene oxide and ethynyl cyclohexanol and performing an exfoliation treatment to obtain a single-layer graphene oxide dispersion; (2) uniformly mixing a portion of the vinyl silicone oil with the catalyst to obtain a first material; The remaining vinyl silicone oil is mixed evenly with the cross-linking agent, the chain extender, and the monolayer graphene oxide dispersion to obtain a second material; Mixing the first material and the second material to obtain a base material; (3) adding spherical aluminum oxide and zinc oxide nanorods to the base material, mixing, vacuumizing and heating to perform cross-linking and addition reaction, while the single-layer graphene oxide is reduced to a single-layer graphene, to obtain a single-component thermally conductive gel; The heating temperature during the mixing and cross-linking is 200-220° C. and the reaction time is 0.5-3 h.

2. The method for preparing a single-component thermally conductive gel according to claim 1, characterized in that: The vinyl silicone oil is monovinyl silicone oil and / or polyvinyl silicone oil, wherein the vinyl content is 0.5-5wt% and the viscosity is 100-1000mPa·s; the particle size of the graphene oxide is 0.1-20μm, and the total content of carbon and oxygen elements is ≥99wt%.

3. The method for preparing a single-component thermally conductive gel according to claim 1, characterized in that: The catalyst is a platinum catalyst, which contains 0.1-5wt% of platinum; the cross-linking agent is a side hydrogen-containing silicone oil with a hydrogen content of 0.05-5wt% and a viscosity of 30-300mPa·s; the chain extender is a single-end hydrogen-containing silicone oil and / or a double-end hydrogen-containing silicone oil, which has a hydrogen content of 0.05-5wt% and a viscosity of 30-300mPa·s.

4. The method for preparing a single-component thermally conductive gel according to claim 1, characterized in that: The mixing speed in steps (1)-(3) is 10-50 rpm and the mixing time is 30-100 min; the stripping treatment in step (1) is selected from one or more combinations of ultrasonic treatment, grinding and dispersion treatment, and high-pressure homogenization treatment.

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