WO2020107599A1 - Thermally-conductive shielding organosilicon material and preparation method therefor - Google Patents

Abstract

A thermally-conductive shielding organosilicon material and a preparation method therefor. Specifically disclosed is a thermally-conductive shielding organosilicon composite film material. The thermally-conductive shielding organosilicon composite film material comprises a thermally-conductive flexible material; the thermally-conductive flexible material comprises a graphite film core material and/or a graphene film core material; the graphite film or graphene film core material is a wave-shaped or corrugation-shaped graphite film or graphene film, and the graphite film or graphene film is parallel to the extension direction of the composite film material; preferably, the thermally-conductive flexible material is a liquid silicone rubber; more preferably, the liquid silicone rubber is prepared from poly(vinylsiloxane), a crosslinking agent, a catalyst, an inhibitor, and a surface treatment agent. In the present invention, the preparation method is simple, the materials are easy to obtain, and excellent thermally-conductive and shielding effects are obtained.

Description

Heat conductive shielding organic silicon material and preparation method thereof Technical field

The invention relates to the field of silicone materials, in particular to a thermally conductive shielding multifunctional silicone material and a preparation method thereof.

Background technique

Fifth generation mobile communication (5G) is a new generation mobile communication system facing the needs of the information society in 2020. It has the characteristics of high spectrum utilization rate, large data flow, low network energy consumption, high reliability and short delay, etc. , Unmanned driving, telemedicine, artificial intelligence and other new technology application innovation foundations. The breakthrough of 5G communication technology and the expansion of application scenarios will promote the revolutionary development of smart terminals and bring new opportunities to the development of the multifunctional polymer composite industry. With the continuous development of intelligent terminals towards ultra-high system integration, miniaturization and high density, especially after the three-dimensional integrated packaging technology has been widely recognized, high-performance thermally conductive, electrically conductive, shielding performance polymer composite materials have become more and more widely s concern. At present, the three-dimensional integrated packaging technology has made breakthrough progress in many aspects. However, there are still electrical reliability problems due to the internal complex electromagnetic environment and thermal reliability problems due to the increased power density of stacked chips. Therefore, the development of a thermally conductive and shielded multifunctional composite material for these problems has become a critical issue that needs to be solved urgently in the new generation of electronic products.

With the development of science and technology, polymer composite materials have been more and more widely used in various fields, such as thermal interface materials, conductive rubber materials and electromagnetic shielding materials. This is because polymer composites have advantages such as light weight, flexibility, compressibility, and corrosion resistance compared to metal materials. In general, polymer composite materials are prepared by adding fillers with desired properties (such as thermal conductivity, electrical conductivity, and electromagnetic shielding) to the polymer substrate. In order to obtain higher thermal and electrical conductivity, the volume fraction of fillers should be more than 60% to ensure that the fillers are in contact with each other to form a connected thermally and electrically conductive network. The addition of a large amount of thermally conductive filler 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 thermal conductivity.

Since its discovery, graphene has received a lot of attention because of its many excellent properties (such as excellent electrical conductivity, thermal conductivity, wave absorption, etc.), and its ultra-high thermal conductivity (~5000W/mK) makes graphene in thermal The management field has huge application prospects. However, the graphene raw materials that can be mass-produced on a large scale are all in a powder state. The sheet diameter of graphene is generally below 20 μm, and the sheet diameter is too small. It is difficult to achieve a large amount of addition when used alone as a thermally conductive filler. In addition, the use of graphene alone as a filler is not conducive to the construction of thermally conductive networks. Considering that the current production cost of high-quality graphene powder is still relatively high, it is not ideal to use graphene alone to prepare high-performance thermally conductive composite materials. Therefore, how to use graphene materials to construct lightweight, high thermal conductivity and conductive shielding composite materials has become an important direction for the current research and development of multifunctional polymer composite materials.

The preparation technology of the existing silicone thermal interface material is mainly by adding a relatively high density of thermally conductive inorganic powder to the silicone material, or then constructing a thermal conduction channel by close packing between the particles, which requires a large amount of powder with different particle sizes The thermal conductivity can only be achieved by the body, and there is more contact thermal resistance between the thermally conductive particles, which makes it impossible to obtain a lightweight thermal interface material with high thermal conductivity.

Summary of the invention

In view of the technical problems in the background art, the present invention abandons the traditional method of directly mixing the thermally conductive powder and the silicone to prepare the silicone thermal interface material, and proposes to construct a corrugated graphite/graphene skeleton with high thermal conductivity, and then fill in the gap Soft silicone, this method effectively reduces and eliminates the contact thermal resistance of the heat conduction network channel between the powders, achieving high thermal conductivity in the vertical direction; at the same time, due to the compactness of the graphite/graphene film, the conductive absorption baud To obtain a silicone graphite film composite material with high thermal conductivity and shielding performance. Another object of the present invention is to provide a method for preparing a multi-functional silicone thermal interface material with high thermal conductivity shielding.

Specifically, one aspect of the present invention provides a thermally conductive and shielded silicone composite film material, which includes a thermally conductive flexible material, and the thermally conductive flexible material has a graphite film core material and/or a graphene film core material, which is characterized by graphite The core material of the film or graphene film is a wavy or corrugated graphite film or graphene film, and the extending direction of the graphite film or graphene film and the composite film material is parallel.

Further, the heat conductive flexible material is liquid silicone rubber.

Further, the liquid silicone rubber is made of polyvinyl siloxane, cross-linking agent, catalyst, inhibitor and surface treatment agent.

In the technical solution of the present invention, the thermal shielding silicone composite film material has a shielding efficiency of 10 MHz to 1 GHz higher than 30 dB, preferably higher than 50 dB, and more preferably higher than 55 dB.

In the technical solution of the present invention, the thermal conductivity shielded silicone composite film material has a thermal conductivity higher than 5W/m·K, preferably higher than 5W/m·K, preferably higher than 10W/m· K.

In the technical solution of the present invention, there is no gap between the thermally conductive flexible material and the graphite film core material and/or the graphene film core material.

In the technical solution of the present invention, the dimension of the graphene membrane core material in the extending direction is the same as the dimension of the silicone composite membrane material in the extending direction, so as to ensure better shielding effect.

In the technical solution of the present invention, the dimension of the graphite film core material and/or graphene film core material in the vertical direction is 0.20 mm to 100 mm, preferably 1 mm to 20 mm.

In the technical solution of the present invention, the thickness of the graphite film core material and/or the graphene film core material is 0.20 mm to 100 mm, preferably 5 μm to 500 μm, preferably 12 μm to 30 μm.

The invention constructs a high thermal conductivity corrugated graphite/graphene skeleton through a folding and pressing process, which not only effectively reduces and eliminates the contact thermal resistance between particles in the heat conduction network channel between powders, but also utilizes the folding of graphene to achieve The best heat conduction path in the vertical direction; at the same time, due to the compactness of the graphite/graphene film and the characteristics of conductive wave absorption, an organic silicon graphene composite material with high thermal conductivity and shielding performance is obtained.

To achieve the above objectives, the technical solutions adopted by the present invention are as follows:

Another method of the present invention provides a method for preparing a thermally conductive and shielded silicone composite film material, which includes the following steps:

(1) Graphite film or graphene film is used as raw material film to make wavy or corrugated graphite film or graphene film core material;

(2) Compress the corrugated or corrugated graphite film or graphene film core material in the mold, and inject liquid silicone rubber to press and set, to obtain a thermally shielded silicone composite material.

In the technical solution of the present invention, the graphite film or graphene film is one layer or more than one layer. It is preferably one layer, two layers, three layers, four layers, and five layers.

In the technical solution of the present invention, there is no contact point between the graphite film core material or the graphene film core material in the vertical direction.

In the technical solution of the present invention, the raw material film is a graphite film or a graphene film with high thermal conductivity, and the thickness is 5 to 500 μm.

Further, the vertical dimension of the graphite membrane core material or the graphene membrane core material is the same as the vertical length of the heat-shielding silicone composite membrane material, or 10%-100% of the vertical length of the silicone composite membrane material For example, it can be 99%, 98%, 97%, 96%, 95%, 90%, 80%, 70%, 60%, 50%, usually 0.20mm-100mm.

Further, the liquid silicone rubber is composed of polyvinyl siloxane, cross-linking agent, catalyst, inhibitor and surface treatment agent, according to the weight of 100:1-25:0.01-2.5:0.2-3.0:0.5-8.0 Served together.

Further, the polyvinyl siloxane is linear, branched, dendritic or micro-crosslinked polysiloxane, and any one molecular structure contains at least two or more aliphatic Saturated double bond, viscosity range from 300 to 500,000 mPa·s, its chain end or side chain contains at least two vinyl groups.

Further, the cross-linking agent is a linear hydrogen-containing silicone oil, a ring-shaped or branched cross-linked hydrogen-containing silicone resin, and its molecular structure contains at least two or more silicon-hydrogen bonds; the viscosity range is 10 to 10000mPa·s, the hydrogen content is 0.02～1.52%, of which 100～3000mPa·S is the best, and one or more curing agents can be mixed among them.

Further, the catalyst is selected from metal compounds or complexes of groups VIII and VII and some rare earth metal compounds, mainly including platinum series catalysts (Speier catalysts, Karstedt catalysts), rhodium catalysts (Wilkinson catalysts), and palladium catalysts Etc., in which the chloroplatinic acid complex catalyst is the best, and the Pt content is between 100 and 5000 ppm.

Further, the inhibitor is one of acetylene alcohol compounds and polyvinyl silicone oil.

Further, the surface treatment agent is selected from vinyl silane coupling agent, epoxy coupling agent, acryloxy silane coupling agent, phthalate coupling agent, zirconate coupling agent, aluminum Acid ester coupling agent and its hydrolysate, such as: γ-methacryloxypropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-(2,3 ring Oxypropyloxy)propylmethyl diethoxysilane, 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, isopropyl titanate tristearate, n-butyl titanate , Bis (acetylacetonyl) ethoxy isopropoxy titanate, bis (triethanolamine) diisopropyl titanate, tetra-n-propyl zirconate, etc., of which 3-glycidyl ether oxypropyl Trimethoxysilane is preferred, especially with its mixed hydrolysate. It can be a mixture of one or more of them and their hydrolysates.

Another aspect of the present invention provides the use of thermally conductive and shielded silicone composite film materials in the field of consumer electronics.

In the present invention, "corrugated" and "wavy" all mean that the graphite film or graphite film has ups and downs in the upper and lower plane directions of the composite film material.

Because the graphite/graphene film is dense and continuous, it has a good plane shielding effect, and its wave folding makes the graphite/graphene film form an ordered arrangement in the vertical direction, which can give the composite material a higher thermal conductivity and maintain a certain degree. The compressibility of the heat conduction shield realizes multiple effects of heat conduction shielding, which can effectively solve the heat dissipation and shielding problems of electronic industrial products, simplify the assembly structure and volume of electronic components, and further reduce production costs.

Beneficial effect

Compared with the prior art, the present invention uses a graphite/graphene with a corrugated structure as a skeleton to realize the integration and verticalization of the heat conduction path, significantly reduce the contact thermal resistance between particles in the traditional technology, and realize the heat conduction path. The shortest, greatly reducing the amount of thermally conductive materials, so as to obtain a lightweight and high thermal conductivity shielding multifunctional silicone graphite composite material.

The method of the invention not only overcomes the problems of low thermal conductivity and poor shielding of the existing organosilicon graphite composite materials, but also maintains the high flexibility and tight fit of the organosilicon, and is especially suitable for heat conduction of new energy vehicles, 5G communication equipment, etc. Multifunctional application requirements for conductive shielding.

The invention provides a novel structured organosilicon thermal conductive shielding material and a preparation method thereof. The preparation method is simple and the preparation materials are easy to obtain, which provides stable and reliable operation of power devices on terminal devices such as the Internet of Things, new energy vehicles, smart phones, etc. Ideas.

BRIEF DESCRIPTION

FIG. 1 is a schematic diagram of a side view of a silicone heat conductive shielding material. Among them, 1 is silicone rubber, and 2 is wavy or corrugated graphite film or graphene film.

detailed description

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below through examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the invention.

Example 1

Preparation method of corrugated organic silicon graphene composite material (corrugated paper core thickness 10mm):

(1) Using 25μm graphene film as the raw material paper, a wave-shaped foldable and retractable core material is made by a wave folding device;

(2) Compress the wave-shaped folded core material in the mold and press it into shape, and then inject liquid silicone rubber, evacuate the bubble, and cure at 150 ℃ for 30 minutes to obtain a thermally conductive silicone composite material. The composition and weight ratio of the liquid silicone rubber are as follows: 1000 parts by weight of 1000 mPa·s vinyl-terminated polysiloxane, 5.5 parts by weight of methyl hydrogen-containing polysiloxane crosslinking agent, 0.3 parts by weight of platinum catalyst, 0.2 By weight parts of butynol inhibitor and 1.5 parts by weight of KH-560 surface treatment agent are mixed to form liquid silica gel. The thermal conductivity of the tile-shaped organosilicon graphene composite material prepared by this method is 17.95W/m·K, and the shielding efficiency of 10MHz～1GHz is 62dB.

Example 2

Preparation method of corrugated organic silicon graphite composite material (corrugated paper core thickness 5mm):

(1) Using 25μm graphite film as the raw material paper, a wave-shaped foldable and retractable core material is made by a wave folding device;

(2) Compress the wave-shaped folded core material in the mold and press it into shape, and then inject liquid silicone rubber, evacuate the bubble, and cure at 150 ℃ for 30 minutes to obtain a thermally conductive silicone composite material. The composition and weight ratio of liquid silicone rubber are as follows: 5000 mPa·s vinyl-terminated polysiloxane 100 parts by weight, 2.5 parts by weight of methyl hydrogen-containing polysiloxane crosslinking agent, 0.2 parts by weight of platinum catalyst, 0.1 By weight parts of butynol inhibitor and 3.0 parts by weight of KH-560 surface treatment agent are mixed to form liquid silica gel. The thermal conductivity of the rib-like organosilicon graphite composite thermal material prepared by this method is 13.32W/m·K, and the shielding efficiency of 10MHz～1GHz is 60dB.

Example 3

Preparation method of corrugated organic silicon graphite/graphene composite material (corrugated paper core thickness 2mm):

(1) A 17μm graphene film is used as the raw paper, and a wave-shaped foldable and retractable core material is made by a wave folding device;

(2) Compress the wave-shaped folded core material in a mold, press and shape, then pour liquid silicone rubber, evacuate the bubble, and cure at 150 ℃ for 30 minutes to obtain a thermally conductive silicone composite material. The composition of liquid silicone rubber and the proportion by weight are as follows: 100 parts by weight of 3000 mPa·s vinyl terminated polysiloxane, 3.5 parts by weight of methyl hydrogen-containing polysiloxane crosslinking agent, 0.5 parts by weight of platinum catalyst, 0.1 By weight parts of butynol inhibitor and 2.0 parts by weight of KH-560 surface treatment agent are mixed to form liquid silica gel. The thermal conductivity of the rib-like organosilicon graphite composite thermal material prepared by this method is 10.41W/m·K, and the shielding efficiency of 10MHz～1GHz is 56dB.

Comparative Example 1

Take 50 parts by weight of 1000 mPa·s vinyl-terminated polysiloxane into the reactor, and then sequentially add 1.2 parts by weight of methyl hydrogen-containing polysiloxane, 3 parts by weight of vinyl trimethoxysilane, 550 parts by weight Parts of alumina with a particle size of 10 microns, 200 parts by weight of alumina with a particle size of 2.0 microns, 5.0 parts by weight of graphene, 0.3 parts by weight of platinum catalyst, and 0.005 parts by weight of butynol inhibitor. The high-speed power mixer is vacuum-stirred for 30 minutes to obtain a homogeneously mixed mixture. The mixture material after stirring and mixing is filled into a frame-shaped mold with a thickness of 2 mm. The frame-shaped mold is an open-top mold to facilitate the solidification and molding of the upper surface of the material. After the material loaded into the frame mold is leveled, the excess material is scraped out with a scraper. Put the mold containing the mixture into the oven and cure at 150°C for 15 minutes. After curing and molding, a sheet with a thickness of 2 mm is obtained. Thermal conductivity 4.10W/m·K, shielding effectiveness 26dB from 10MHz to 1GHz.

The above is an inspiration based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the contents of the description, and the technical scope must be determined according to the scope of the claims.

Claims (10)

1. A thermally conductive and shielded silicone composite film material, which contains a thermally conductive flexible material, which has a graphite film core material and/or graphene film core material in the thermally conductive flexible material, characterized in that the graphite film or graphene film core material is Wavy or corrugated graphite film or graphene film, and the extension direction of the graphite film or graphene film and the composite film material is parallel;

   Preferably, the thermally conductive flexible material is liquid silicone rubber;

   More preferably, the liquid silicone rubber is made of polyvinyl siloxane, cross-linking agent, catalyst, inhibitor and surface treatment agent.
2. According to the heat-shielding silicone composite film material according to claim 1, the dimension of the graphite film core material and/or the graphene film core material in the vertical direction is 0.20 mm to 100 mm, preferably 1 mm to 20 mm.
3. The thermally conductive silicone composite film material according to claim 1 or 2, wherein the thickness of the graphite film core material and/or the graphene film core material is the same as the vertical length of the thermally conductive shielding silicone composite film material, or is a silicone 10%-100% of the vertical length of the composite membrane material.
4. The method for preparing a thermally conductive shielding silicone composite film material according to any one of claims 1 to 3, characterized in that it includes the following steps:

   1) Graphite or graphene film is used as raw material film to make wavy or corrugated graphite film or graphene film core material;

   2) Compress the corrugated or corrugated graphite film or graphene film core material into the mold, and inject liquid silicone rubber to press and set, to obtain a thermally conductive and shielded silicone composite material.
5. The preparation method according to claim 4, characterized in that the liquid silicone rubber is composed of polyvinyl siloxane, cross-linking agent, catalyst, inhibitor, surface treatment agent, according to 100: 1 ~ 25: 0.01 ~ 2.5: 0.2 to 3.0: 0.5 to 8.0 parts by weight are mixed.
6. The preparation method according to any one of claims 4-5, wherein the polyvinyl siloxane is selected from one of linear, branched, dendritic or micro-crosslinked polysiloxanes Mixture of one or more species, preferably, the molecular structure of polyvinyl siloxane contains at least two or more aliphatic unsaturated double bonds, the viscosity range is 300 to 500,000 mPa·s, and its chain ends or side chains Contains at least two vinyl groups.
7. A method for preparing a ribbed structure organosilicon graphite/graphene composite material according to any one of claims 4-6, wherein the cross-linking agent is selected from linear hydrogen-containing silicone oil, ring-shaped or One or more mixtures of branched and cross-linked hydrogen-containing silicone resins. Preferably, the molecular structure of the cross-linking agent contains at least two or more silicon-hydrogen bonds; the viscosity ranges from 10 to 10000 mPa· s, hydrogen content is 0.02 ~ 1.52%.
8. The preparation method according to any one of claims 4-7, wherein the catalyst is selected from a mixture of one or more of metal compounds or complexes of Groups VIII and VII and rare earth metal compounds.
9. The preparation method according to any one of claims 4-8, wherein the inhibitor is a mixture of one or more of acetylene alcohol compounds and polyvinyl silicone oil.
10. The preparation method according to any one of claims 4-9, wherein the surface treatment agent is selected from a vinyl silane coupling agent, an epoxy coupling agent, an acryloyloxy silane coupling agent, Mixtures of one or more of ester coupling agents, zirconate coupling agents, aluminate coupling agents and their hydrolysates.

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