CN114539779A - Ultrahigh-temperature-resistant high-thermal-conductivity carbon fiber silica gel gasket and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of heat-conducting silica gel, in particular to an ultrahigh-temperature-resistant high-heat-conductivity carbon fiber silica gel gasket which comprises the following raw materials in parts by mass: 15-35 parts of organic solvent, 5-12 parts of silicon rubber, 1-5 parts of silicone oil, 1-3 parts of reinforcing agent, 0.2-0.5 part of coupling agent, 10-25 parts of carbon fiber, 40-60 parts of heat-conducting filler, 0.5-1.5 parts of cross-linking agent, 0.1-0.3 part of thixotropic agent, 0.02-0.05 part of alkynol inhibitor and 0.1-0.5 part of platinum catalyst. The invention also discloses a preparation method of the ultrahigh temperature resistant high-thermal conductivity carbon fiber silica gel gasket. The high-thermal-conductivity carbon fiber silica gel gasket provided by the invention has the advantages of high orientation rate, good mechanical property, high temperature resistance of 300 ℃, compression resilience rate of 90 percent and thermal conductivity of 50W/(m.k), and low thermal conductivity coefficient change rate and hardness change rate after aging at 300 ℃/100H, and can meet the use requirements of the technical field of wireless communication with high temperature resistance and rapid heat dissipation.

Description

Ultrahigh-temperature-resistant high-thermal-conductivity carbon fiber silica gel gasket and preparation method thereof

Technical Field

The invention relates to the technical field of heat-conducting silica gel, in particular to an ultrahigh-temperature-resistant high-heat-conductivity carbon fiber silica gel gasket and a preparation method thereof.

Background

The communication technology is one of important signs for human beings to enter an information society, and two types of communication technologies which are common in the current communication engineering are wired communication and wireless communication respectively. Compared with wireless communication, the wired communication is developed earlier, and in terms of practicability, wired technology is not affected by too many external influences, and factors interfering with the wired technology are fewer, so that information transmission and receiving safety can be effectively guaranteed.

The wireless communication technology has strong convenience, is not limited by factors such as space, time and the like, and can play a role in various fields. Especially, in recent years, 5G technology is rapidly developed, and 5G-based unmanned aerial vehicle technology and mobile phones are also rapidly developed. However, these communication devices often have internal electronic components that fail due to the weather effects of hot heat. The current 5G application equipment such as mobile phones, unmanned aerial vehicles and the like generally has the requirements on the operating environment temperature of-5-45 ℃, and the transmission equipment is greatly damaged when the temperature exceeds 50 ℃. The 5G device has obvious power consumption, and is very easy to cause thermal failure due to overhigh temperature when meeting a hot environment, so that the conventional interface heat dissipation material cannot meet the continuous and stable working condition. Therefore, in order to meet this type of heat dissipation requirement, a high thermal conductivity interface material resistant to high temperature will meet the demand explosion.

At present, the main heat conduction material is filling type heat conduction material, and the filling type heat conduction material fills high heat conduction and high insulation filler into a high polymer material matrix, so that a heat conduction network is formed inside the filling type heat conduction material, and the heat conduction performance of the composite material is improved. However, maintaining excellent thermal conductivity requires a high loading of the thermal interface material, which often results in poor mechanical properties and flame retardant properties, affecting the service life of the thermal interface material. It is therefore the current aim of research to obtain higher thermal conductivity at low loading, while other properties can be guaranteed. At present, the domestic and foreign research on the heat-conducting composite material mainly focuses on means such as surface modification of fillers, compounding and cooperation of various fillers, construction of a three-dimensional network structure, change of a processing technology and the like to improve the heat conductivity of the composite material. However, due to the high interfacial thermal resistance between the filler and the polymer matrix, these fillers either fail to meet electrical insulation requirements or require very high loadings to achieve their high thermal conductivity, increase cost and reduce mechanical properties when added to the silicone rubber matrix.

Carbon fibers have the advantages of small density, excellent mechanical properties, small thermal expansion coefficient, good heat and electricity conduction, anisotropy, high temperature resistance, fatigue resistance and the like, and are widely applied to the high-tech fields of aerospace, national defense, military industry, civil industry and the like. The carbon fiber is an anisotropic material, has ultrahigh thermal conductivity in the axial direction, can reach 600-plus 1300W/(m.K), and can remarkably improve the thermal conductivity of the silica gel under a smaller filling amount after the carbon fiber is orderly arranged in the silica gel, and simultaneously keeps good mechanical and mechanical properties of the silica gel. Carbon fiber heat-conducting silica gel gaskets with large heat conductivity coefficient are prepared by compounding carbon fiber materials and silica gel materials in the market at present, but the carbon fiber heat-conducting silica gel gaskets are complex in preparation process, poor in product stability, uninsulated, easy to cause short circuit in the application process, poor in durability at high temperature and capable of influencing the normal operation of electronic equipment.

Disclosure of Invention

In view of this, the technical problem to be solved by the present invention is to provide an ultrahigh temperature resistant high thermal conductivity carbon fiber silicone gasket and a preparation method thereof, and the ultrahigh temperature resistant high thermal conductivity carbon fiber silicone gasket is an ultrahigh temperature resistant high thermal conductivity carbon fiber silicone gasket having high thermal conductivity, good mechanical properties and thermal stability.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides an ultrahigh-temperature-resistant high-thermal-conductivity carbon fiber silica gel gasket which comprises the following raw materials in parts by mass: 15-35 parts of organic solvent, 5-12 parts of silicone rubber, 1-5 parts of silicone oil, 1-3 parts of reinforcing agent, 0.2-0.5 part of coupling agent, 10-25 parts of carbon fiber, 40-60 parts of heat-conducting filler, 0.5-1.5 parts of cross-linking agent, 0.1-0.3 part of thixotropic agent, 0.02-0.05 part of alkynol inhibitor and 0.1-0.5 part of platinum catalyst.

Preferably, the silicone rubber is selected from heat-resistant compounded silicone rubbers.

Preferably, the reinforcing agent is selected from one or more of white carbon black, calcium carbonate or zinc oxide.

Preferably, the carbon fibers are selected from pitch-based carbon fibers.

Preferably, the carbon fiber is a 2K long fiber having a diameter of 8 to 12 μm and a thermal conductivity of 600W/(mK) or more.

Preferably, the heat-conducting filler is selected from spherical aluminum oxide or spherical aluminum nitride, and the particle size is 3-5 μm.

Preferably, the organic solvent is selected from one or more of n-heptane or xylene.

Preferably, the silicone oil is selected from vinyl silicone oils.

Preferably, the coupling agent is selected from one or more of a silane coupling agent or a titanate coupling agent.

On the other hand, the invention provides a preparation method of the ultrahigh temperature resistant high thermal conductivity carbon fiber silica gel gasket according to any one of the technical schemes, which comprises the following steps:

s1: slicing the silicon rubber, putting the sliced silicon rubber into a container, and pouring a certain amount of organic solvent to soak and soften the silicon rubber for 2 to 3 hours;

s2: after the silicon rubber is softened, transferring the silicon rubber and the organic solvent to a planetary stirrer together; adding silicone oil, a coupling agent, a cross-linking agent and a thixotropic agent, and stirring for 1-2.5 hours at the rotating speed of 20-30rpm by planetary stirring;

s3: adding a reinforcing agent, a heat-conducting filler, an alkynol inhibitor and a platinum catalyst, stirring uniformly by planetary stirring at a rotating speed of 15-30rpm for 80-130 minutes to obtain a sizing material;

s4: testing the viscosity of the rubber material, and gradually adding the organic solvent to adjust the viscosity to the specification; vacuumizing the sizing material for 5-10 minutes, and standing for more than 30 minutes;

s5: uniformly and vertically fixing the carbon fibers by using a special die, slowly injecting the sizing material, and soaking for more than 0.5 hour after injection is finished;

s6: transferring the special mold to a vacuum oven, and keeping the special mold for 1-2 hours at the temperature of 50-80 ℃ and the vacuum degree of-0.09-0.07 MPa;

s7: transferring the whole special die to a precision oven, adjusting the temperature to 100-120 ℃, baking for 1-2 hours, and curing and forming to obtain a semi-finished product;

s8: and taking the semi-finished product out of the special die, performing die cutting in a direction vertical to the carbon fiber, performing die cutting with different thicknesses according to requirements, and cutting the rim charge to the size of the finished product to obtain the finished product.

Preferably, in step S3, the specific steps include:

s301: adding the reinforcing agent, stirring uniformly by planetary stirring at the rotating speed of 25rpm for 20-30 minutes;

s302: adding half of the heat-conducting filler, and stirring for 15-20 minutes at a rotating speed of 25rpm by planetary stirring; adding the other half of the heat-conducting filler, and stirring uniformly by planetary stirring at the rotating speed of 20rpm for 15-20 minutes;

s303: adding alkynol inhibitor, stirring for 10-15 minutes at 15rpm by planetary stirring until the mixture is uniform;

s304: adding a platinum catalyst, stirring uniformly by planetary stirring at a rotating speed of 15rpm for 20-25 minutes; scraping the materials of the cylinder wall and the stirring paddle of the planetary stirrer by using a scraper, and stirring at the rotating speed of 15rpm for 20-25 minutes until the materials are uniform.

Preferably, in step S6, the specific steps include:

transferring the special mold to a vacuum oven, adjusting the temperature to 50-60 ℃ and the vacuum degree to-0.07 MPa, and keeping for 30-50 minutes; then the temperature is adjusted to 70-80 ℃ and the vacuum degree is adjusted to-0.09 MPa, and the temperature is kept for 30-50 minutes.

The high-thermal-conductivity carbon fiber silica gel gasket provided by the invention adopts a carbon fiber orientation technology, has high orientation rate and good mechanical property, can resist high temperature of 300 ℃, has a compression rebound rate of 90 percent and a thermal conductivity of 50W/(m.k), is aged at 300 ℃/100H, has low thermal conductivity coefficient change rate and low hardness change rate, and can meet the use requirements of the technical field of wireless communication with high temperature resistance and rapid heat dissipation.

Drawings

FIG. 1 is a schematic view of a special mold used in the present invention;

FIG. 2 is a graph of thermal conductivity versus aging temperature for example 5 and comparative example 3 (aging time 100 h);

FIG. 3 is a graph of the rate of change of thermal conductivity versus aging temperature (aging time 100h) for example 5 and comparative example 3;

FIG. 4 is a graph of hardness versus aging temperature (aging time 100h) for example 5 and comparative example 3;

FIG. 5 is a graph of hardness change rate versus aging temperature (aging time 100h) for example 5 and comparative example 3;

reference numerals: 1-container, 2-grid, 3-carbon fiber.

Detailed Description

For further understanding of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention are within the scope of protection of the present invention without any creative work.

The embodiment provides a high thermal conductivity carbon fiber silica gel gasket of resistant ultra-high temperature, according to the part by mass, the raw materials contain: 15-35 parts of organic solvent, 5-12 parts of silicone rubber, 1-5 parts of silicone oil, 1-3 parts of reinforcing agent, 0.2-0.5 part of coupling agent, 10-25 parts of carbon fiber, 40-60 parts of heat-conducting filler, 0.5-1.5 parts of cross-linking agent, 0.1-0.3 part of thixotropic agent, 0.02-0.05 part of alkynol inhibitor and 0.1-0.5 part of platinum catalyst.

In this embodiment, the silicone rubber is selected from heat-resistant compounded silicone rubber.

In this embodiment, the reinforcing agent is selected from one or more of white carbon black, calcium carbonate, or zinc oxide.

The silicone rubber has good high and low temperature resistance, oil resistance, air permeability, biological inertia and the like, but because the silicone rubber is a linear polymer and has poor mechanical strength, under the normal condition, reinforcing materials such as white carbon black, fibers and the like need to be added into a silicone rubber curing system for doping so as to effectively improve the mechanical property of the silicone rubber, thereby preparing the silicone rubber composite material with certain mechanical strength.

In this embodiment, the carbon fibers are selected from pitch-based carbon fibers.

The carbon fiber has high strength, good heat conductivity and excellent corrosion resistance, and is used as a reinforcing material in heat conduction materials. In the research of the invention, the length of the carbon fiber can influence the heat conduction effect of the carbon fiber heat conduction silica gel gasket, the length of the carbon fiber is too short, and the good heat conduction effect cannot be achieved by mixing the carbon fiber and the silica gel, so the invention selects the long fiber.

In the present example, the carbon fiber is a 2K long fiber having a diameter of 8 to 12 μm and a thermal conductivity of 600W/(mK) or more. The bundle of carbon fiber yarns referred to by 2K is composed of 2000 individual yarns.

In this embodiment, the thermally conductive filler is selected from spherical aluminum oxide or spherical aluminum nitride. The heat-conducting filler has good filling performance, so that the particle size of the heat-conducting filler not only influences the heat conductivity of the silicon rubber in the invention. Therefore, the average particle diameter of the thermally conductive filler used in the present invention is 1 to 10 μm, and more preferably 3 to 5 μm.

In this embodiment, the organic solvent is selected from one or more of n-heptane or xylene.

In this embodiment, the silicone oil is selected from vinyl silicone oils.

The silicone oil is used for improving the filling effect of the heat-conducting filler in the silicone oil, the content is too low, the filling effect of the powder is not good, the content is too large, the filling proportion of the heat-conducting filler is reduced, the heat conductivity coefficient of the material is influenced, and the forming difficulty and the processing cost are also increased.

In this embodiment, the coupling agent is selected from one or more of a silane coupling agent or a titanate coupling agent.

The coupling agent can increase the adhesion between the silicon rubber and other solid components such as the heat-conducting filler and the like, and plays a role of a bridge.

In this example, the alkynol inhibitor is ethynylcyclohexanol.

The cross-linking agent can promote the mutual connection of the active functional groups of the silicon rubber to generate a network structure, the reaction rate is higher when the cross-linking agent is matched with a platinum catalyst, and the cross-linking reaction can be limited to a certain extent by matching with an alkynol inhibitor.

In this embodiment, the crosslinking agent is selected from any one of hydrogen-containing silicone oil, polyalkoxysilane, polyamine silane, polyamido silane, polybutanone oxime silane, polyacetoxy silane, and polyisoacryloxy silane.

In the invention, the silane coupling agent plays a role of bridging the connection among the heat-conducting filler particles, which is beneficial to forming an effective heat conduction path, thereby reducing the contact thermal resistance among the heat-conducting fillers, and the carbon fiber has very high thermal conductivity and is used for filling silicon rubber, thereby greatly improving the thermal conductivity of the silicon rubber composite material; on the other hand, the insulating silicon rubber matrix and the insulating heat-conducting filler can prevent the carbon fibers from contacting with each other and inhibit the movement of charges, so that the good mechanical property and the electric insulating property of the silicon rubber composite material are ensured.

On the other hand, the embodiment provides a preparation method of the ultrahigh temperature resistant high thermal conductivity carbon fiber silica gel gasket according to any one of the above technical solutions, including the following steps:

s1: slicing the silicon rubber, putting the sliced silicon rubber into a container, and pouring a certain amount of organic solvent to soak and soften the silicon rubber for 2 to 3 hours;

s2: after the silicon rubber is softened, transferring the silicon rubber and the organic solvent to a planetary stirrer together; adding silicone oil, a coupling agent, a cross-linking agent and a thixotropic agent, and stirring for 1-2.5 hours at the rotating speed of 20-30rpm by planetary stirring;

s3: adding a reinforcing agent, a heat-conducting filler, an alkynol inhibitor and a platinum catalyst, stirring uniformly by planetary stirring at a rotating speed of 15-30rpm for 80-130 minutes to obtain a sizing material;

s4: testing the viscosity of the rubber material, and gradually adding the organic solvent to adjust the viscosity to the specification; vacuumizing the sizing material for 5-10 minutes, and standing for more than 30 minutes;

s5: uniformly and vertically fixing the carbon fibers by using a special die, slowly injecting the sizing material, and soaking for more than 0.5 hour after injection is finished;

s6: transferring the special mold to a vacuum oven, and keeping the special mold for 1-2 hours at the temperature of 50-80 ℃ and the vacuum degree of-0.09-0.07 MPa;

s7: transferring the whole special die to a precision oven, adjusting the temperature to 100-120 ℃, baking for 1-2 hours, and curing and forming to obtain a semi-finished product;

s8: and taking the semi-finished product out of the special die, performing die cutting in a direction vertical to the carbon fiber, performing die cutting with different thicknesses according to requirements, and cutting the rim charge to the size of the finished product to obtain the finished product.

The planetary stirrer has a unique and novel stirring form, two or 3 multi-layer blade stirrers and 1-2 automatic scrapers are arranged in the kettle, the stirrers revolve around the axis of the kettle body, and simultaneously rotate around the axis of the stirrer at high speed at different rotating speeds, so that materials do complex motion in the kettle body, and the efficiency of the planetary stirrer subjected to strong shearing and twisting is usually multiple times that of a common stirrer. The main machine adopts the design of a planetary gear speed reducer, has low noise and high mechanical efficiency, can save power and reduce the occupied space of equipment.

Referring to fig. 1, the special mold used in the present invention is a square container 1, the upper end is open, the lower end is closed, the upper end and the lower end are provided with the same mesh grid 2, the two ends of the carbon fiber 3 are simultaneously fixed at the corner of the mesh grid 2, the carbon fiber 3 is kept parallel to the side wall plane of the square container and perpendicular to the mesh grid plane, and by adopting the above technical scheme, a plurality of carbon fibers 3 are mutually parallel and directionally arranged.

In steps S6-S7, the vacuum process is mainly performed to remove air in the product, improve the heat conduction of the product, and reduce the fraction defective due to the presence of air holes; and the degree of vacuum in the process of vacuumizing and the time of vacuumizing can influence the compactness of the carbon fiber silica gel gasket, thereby influencing the heat-conducting property of the carbon fiber silica gel gasket. The temperature of the curing program is set to be 50-120 ℃, because when the temperature of the curing temperature is lower than 50 ℃, the vulcanization time of the carbon fiber silica gel gasket is prolonged, the production efficiency is influenced, when the temperature of the curing temperature is higher than 120 ℃, the solvent is volatilized too fast, holes are easy to generate in the middle of the heat-conducting carbon fiber silica gel gasket, and the rejection rate is increased.

In this embodiment, in the step S3, the specific steps include:

s301: adding the reinforcing agent, stirring uniformly by planetary stirring at the rotating speed of 25rpm for 20-30 minutes;

s302: adding half of the heat-conducting filler, and stirring for 15-20 minutes at a rotating speed of 25rpm by planetary stirring; adding the other half of the heat-conducting filler, and stirring uniformly by planetary stirring at the rotating speed of 20rpm for 15-20 minutes;

s303: adding alkynol inhibitor, stirring for 10-15 minutes at 15rpm by planetary stirring until the mixture is uniform;

s304: adding a platinum catalyst, stirring uniformly by planetary stirring at a rotating speed of 15rpm for 20-25 minutes; scraping the materials of the cylinder wall and the stirring paddle of the planetary stirrer by using a scraper, and stirring at the rotating speed of 15rpm for 20-25 minutes until the materials are uniform.

In this embodiment, in the step S6, the specific steps include:

transferring the special mold to a vacuum oven, adjusting the temperature to 50-60 ℃ and the vacuum degree to-0.07 MPa, and keeping for 30-50 minutes; then the temperature is adjusted to 70-80 ℃ and the vacuum degree is adjusted to-0.09 MPa, and the temperature is kept for 30-50 minutes.

The ultrahigh temperature resistant high-thermal conductivity carbon fiber silica gel gasket can be applied to heat dissipation gaskets of electronic components.

The technical solution of the present invention is further described with reference to the specific embodiments.

Example 1

The utility model provides an ultra-high temperature resistant high thermal conductivity carbon fiber silica gel gasket, the raw materials contains: 2.5kg of n-heptane, 0.9kg of silicon rubber, 0.3kg of vinyl silicone oil, 0.2kg of white carbon black, 0.03kg of silane coupling agent, 1.7kg of carbon fiber, 5.5kg of spherical alumina, 0.01kg of cross-linking agent, 0.02kg of thixotropic agent, 0.003kg of alkynol inhibitor and 0.04kg of platinum catalyst.

The preparation method comprises the following specific steps:

(1) slicing the silicon rubber, putting the sliced silicon rubber into a container, pouring 2kg of n-heptane into the container, soaking and softening the silicon rubber for 2.5 hours;

(2) after the silicon rubber is softened, transferring the silicon rubber and n-heptane to a planetary stirrer together; adding vinyl silicone oil, a silane coupling agent, a cross-linking agent and a thixotropic agent, and stirring for 1 hour at the rotating speed of 25rpm by planetary stirring;

(3) adding white carbon black, spherical alumina, alkynol inhibitor and platinum catalyst, stirring uniformly by planetary stirring at a rotating speed of 20rpm for 80-130 minutes to obtain a sizing material;

(4) testing the viscosity of the rubber material, and gradually adding n-heptane to adjust the viscosity to the specification viscosity if the viscosity is greater than the specification viscosity; vacuumizing the sizing material for 5 minutes, and standing for more than 30 minutes;

(5) uniformly and vertically fixing the carbon fibers by using a special die, slowly injecting a sizing material, and soaking for more than 0.5 hour after injection is finished;

(6) transferring the special mold to a vacuum oven, adjusting the temperature to 50 ℃ and the vacuum degree to-0.07 MPa, and keeping for 30 minutes; then the temperature is adjusted to 70 ℃ and the vacuum degree is adjusted to-0.09 MPa, and the mixture is kept for 30 minutes;

(7) transferring the whole special die to a precision oven, adjusting the temperature to 100 ℃, baking for 1 hour, and curing and forming to obtain a semi-finished product;

(8) and taking the semi-finished product out of the special die, performing die cutting in the direction vertical to the carbon fiber, performing die cutting to different thicknesses according to requirements, and cutting the rim charge to the size of the finished product to obtain the finished product.

Example 2

The utility model provides an ultra-high temperature resistant high thermal conductivity carbon fiber silica gel gasket, the raw materials contains: 1.5kg of dimethylbenzene, 0.5kg of silicon rubber, 0.1kg of vinyl silicone oil, 0.1kg of calcium carbonate, 0.02kg of titanate coupling agent, 1kg of carbon fiber, 4kg of spherical aluminum nitride, 0.07kg of cross-linking agent, 0.01kg of thixotropic agent, 0.002kg of alkynol inhibitor and 0.02kg of platinum catalyst.

The preparation method comprises the following specific steps:

(1) slicing silicon rubber, putting the sliced silicon rubber into a container, and pouring 1kg of dimethylbenzene to soak and soften the silicon rubber for 2 hours;

(2) after the silicon rubber is softened, transferring the silicon rubber and xylene to a planetary stirrer together; adding vinyl silicone oil, titanate coupling agent, cross-linking agent and thixotropic agent, and stirring for 1 hour at the rotating speed of 20rpm by planetary stirring;

(3) adding calcium carbonate, spherical aluminum nitride, alkynol inhibitor and platinum catalyst, stirring uniformly by planetary stirring at a rotating speed of 15rpm for 80-130 minutes to obtain a sizing material;

(4) testing the viscosity of the rubber material, and gradually adding dimethylbenzene to adjust the viscosity to the specification viscosity if the viscosity is larger than the specification viscosity; vacuumizing the sizing material for 5 minutes, and standing for more than 30 minutes;

(5) uniformly and vertically fixing the carbon fibers by using a special die, slowly injecting a sizing material, and soaking for more than 0.5 hour after injection is finished;

(6) transferring the special mold to a vacuum oven, adjusting the temperature to 50 ℃ and the vacuum degree to-0.07 MPa, and keeping for 30 minutes; then adjusting the temperature to 70 ℃ and the vacuum degree to-0.09 MPa, and keeping for 30 minutes;

(7) transferring the whole special die to a precise oven, adjusting the temperature to 100 ℃, baking for 2 hours, and curing and forming to obtain a semi-finished product;

(8) and taking the semi-finished product out of the special die, performing die cutting in the direction vertical to the carbon fiber, performing die cutting to different thicknesses according to requirements, and cutting the rim charge to the size of the finished product to obtain the finished product.

Example 3

The utility model provides an ultra-high temperature resistant high thermal conductivity carbon fiber silica gel gasket, the raw materials contains: 1.5kg of n-heptane, 2kg of xylene, 1.2kg of silicone rubber, 0.5kg of vinyl silicone oil, 0.3kg of zinc oxide, 0.05kg of silane coupling agent, 2.5kg of carbon fiber, 3kg of spherical alumina, 3kg of spherical aluminum nitride, 0.15kg of cross-linking agent, 0.03kg of thixotropic agent, 0.005kg of alkynol inhibitor and 0.05kg of platinum catalyst.

The preparation method comprises the following specific steps:

(1) slicing silicon rubber, putting into a container, pouring 0.5kg of n-heptane and 2kg of xylene, soaking and softening for 3 hours;

(2) after the silicon rubber is softened, transferring the silicon rubber and n-heptane to a planetary stirrer together; adding vinyl silicone oil, a silane coupling agent, a cross-linking agent and a thixotropic agent, and stirring for 2.5 hours at the rotating speed of 30rpm by planetary stirring;

(3) adding zinc oxide, spherical alumina, spherical aluminum nitride, alkynol inhibitor and platinum catalyst, stirring uniformly by planetary stirring at the rotating speed of 30rpm for 80-130 minutes to obtain a sizing material;

(4) testing the viscosity of the sizing material, and gradually adding n-heptane to adjust the viscosity to the specification viscosity if the viscosity is greater than the specification viscosity; vacuumizing the sizing material for 10 minutes, and standing for more than 30 minutes;

(5) uniformly and vertically fixing the carbon fibers by using a special die, slowly injecting a sizing material, and soaking for more than 0.5 hour after injection is finished;

(6) transferring the special mold to a vacuum oven, adjusting the temperature to 60 ℃ and the vacuum degree to-0.07 MPa, and keeping for 50 minutes; then the temperature is adjusted to 80 ℃ and the vacuum degree is adjusted to-0.09 MPa, and the mixture is kept for 50 minutes;

(7) transferring the whole special die to a precision oven, adjusting the temperature to 120 ℃, baking for 1 hour, and curing and forming to obtain a semi-finished product;

(8) and taking the semi-finished product out of the special die, performing die cutting in the direction vertical to the carbon fiber, performing die cutting to different thicknesses according to requirements, and cutting the rim charge to the size of the finished product to obtain the finished product.

Example 4

The utility model provides a high thermal conductivity carbon fiber silica gel gasket of resistant ultra-temperature, the raw materials contains: 1.5kg of n-heptane, 2kg of xylene, 1.2kg of silicone rubber, 0.5kg of vinyl silicone oil, 0.3kg of zinc oxide, 0.05kg of silane coupling agent, 2.5kg of carbon fiber, 3kg of spherical alumina, 3kg of spherical aluminum nitride, 0.15kg of cross-linking agent, 0.03kg of thixotropic agent, 0.005kg of alkynol inhibitor and 0.05kg of platinum catalyst.

The preparation method comprises the following specific steps:

(1) slicing silicon rubber, putting into a container, pouring 0.5kg of n-heptane and 2kg of xylene, soaking and softening for 3 hours;

(2) after the silicon rubber is softened, transferring the silicon rubber and n-heptane to a planetary stirrer together; adding vinyl silicone oil, a silane coupling agent, a cross-linking agent and a thixotropic agent, and stirring for 2.5 hours at the rotating speed of 30rpm by planetary stirring;

(3) adding zinc oxide, stirring for 30 minutes at 25rpm by planetary stirring until the mixture is uniform;

(4) adding spherical alumina, and stirring for 20 minutes at the rotating speed of 25rpm by planetary stirring; spherical aluminum nitride was added and stirred at 20rpm for 20 minutes with planetary stirring until homogeneous.

(5) The alkynol inhibitor was added and stirred with planetary stirring at 15rpm for 15 minutes to homogeneity.

(6) Adding a platinum catalyst, stirring uniformly by a planetary stirrer at a rotating speed of 15rpm for 25 minutes; the material from the wall of the planetary mixer and the stirring paddle was scraped off using a scraper and stirred at 15rpm for 25 minutes until uniform.

(7) Testing the viscosity of the rubber material, and gradually adding n-heptane to adjust the viscosity to the specification viscosity if the viscosity is greater than the specification viscosity; vacuumizing the sizing material for 10 minutes, and standing for more than 30 minutes;

(8) uniformly and vertically fixing the carbon fibers by using a special die, slowly injecting a sizing material, and soaking for more than 0.5 hour after injection is finished;

(9) transferring the special mold to a vacuum oven, adjusting the temperature to 50 ℃ and the vacuum degree to-0.07 MPa, and keeping for 30 minutes; then the temperature is adjusted to 70 ℃ and the vacuum degree is adjusted to-0.09 MPa, and the mixture is kept for 30 minutes;

(10) transferring the whole special die to a precision oven, adjusting the temperature to 100 ℃, baking for 1 hour, and curing and forming to obtain a semi-finished product;

(11) and taking the semi-finished product out of the special die, performing die cutting in the direction vertical to the carbon fiber, performing die cutting to different thicknesses according to requirements, and cutting the rim charge to the size of the finished product to obtain the finished product.

Example 5

The procedure was analogous to example 4, except that: (2) the method comprises the following steps: after the silicon rubber is softened, transferring the silicon rubber and n-heptane to a planetary stirrer together; adding vinyl silicone oil, a silane coupling agent, a crosslinking agent and a thixotropic agent, stirring for 30 minutes at the rotating speed of 25rpm by planetary stirring, scraping off the material cylinder wall of the planetary stirrer and the silicone rubber of the stirring paddle by using a scraper, and stirring for 30 minutes at the rotating speed of 25rpm until the materials are uniform.

Comparative example 1

The procedure was analogous to example 4, except that: (8) the method comprises the following steps: no carbon fibers were placed.

Comparative example 2

The preparation procedure was similar to example 4, except that: (8) the method comprises the following steps: slowly injecting a sizing material by using a special mould, uniformly spraying 30-100um short carbon fibers on the surface of the sizing material every time 1cm thick sizing material is injected, finally slowly injecting the sizing material to cover the short carbon fibers, and soaking for more than 0.5 hour after the injection is finished.

Comparative example 3

A commercially available heat-conducting carbon fiber silica gel gasket of a certain company.

In the present invention, the source of the material used is not particularly limited except for the above-mentioned specific description, and may be a material generally commercially available.

The hardness, thermal conductivity, thermal resistance, volume resistivity, tensile strength, elongation at break and compression rebound rate of the heat-conducting carbon fiber silica gel gaskets of examples 1-5 and comparative examples 1-3 were respectively tested, and the hardness, thermal conductivity, hardness change rate and thermal conductivity change rate of the heat-conducting carbon fiber silica gel gaskets under the high-temperature aging condition of 300 ℃/100H were tested under the same test conditions, and the same thickness of each sample was maintained. Hardness properties were measured according to the test method of ASTM D2240, thermal conductivity properties according to ASTM D5470, thermal resistance properties according to ASTM D5470, volume resistivity according to the test method of ASTM D257, tensile strength and elongation at break according to the test method of ASTM D412. The compression rebound rate test method comprises the following steps: the sample is compressed to 50% of the thickness at room temperature, the pressure is removed after 24 hours, and the sample is stood for 2 hours to test the rebound rate. The test results for the specific examples and comparative examples are given in table 1 below:

TABLE 1 test results of examples and comparative examples

The data in table 1 confirm that the tensile strength, the elongation at break and the compression rebound rate of the heat-conducting carbon fiber silica gel gasket used in examples 1 to 5 are significantly improved, and particularly the compression rebound rate can reach nearly 90% compared with the commercially available heat-conducting carbon fiber silica gel gasket of proportion 3.

The thermal conductivity, tensile strength, elongation at break, and compression rebound rate of the heat conductive carbon fiber silica gel gasket using examples 1 to 5 were all significantly improved as compared with comparative example 1 in which the carbon fiber was removed. Compared with comparative example 2 filled with short carbon fibers, the heat conductivity, tensile strength and elongation at break of the heat-conducting carbon fiber silica gel gasket of examples 1-5 are all improved, and the compression rebound rate is obviously improved.

The heat-conducting carbon fiber silica gel gaskets of example 5 and comparative example 3 were placed in a precision oven and baked at high temperature for an aging test with an aging time of 100 hours and comparative data of characteristic changes, see fig. 2-5.

FIG. 2 is a graph of thermal conductivity versus aging temperature for example 5 and comparative example 3 (aging time 100 h); FIG. 3 is a graph of the rate of change of thermal conductivity versus aging temperature for example 5 and comparative example 3 (aging time 100 h); as can be confirmed from fig. 2-3, compared with the commercially available heat-conductive carbon fiber silicone gasket of comparative example 3, the heat-conductive carbon fiber silicone gasket of example 5 has a heat conductivity change rate of only about 10% after 300 ℃/100H, whereas the heat conductivity change rate of the commercially available heat-conductive carbon fiber silicone gasket has reached about 70%, which has completely lost the advantage of high heat conductivity of the heat-conductive carbon fiber silicone gasket.

FIG. 4 is a graph of hardness versus aging temperature for example 5 and comparative example 3 (aging time 100 h); FIG. 5 is a graph of hardness change rate versus aging temperature (aging time 100h) for example 5 and comparative example 3; as can be seen from fig. 4 to 5, compared with the commercially available heat conductive carbon fiber silica gel gasket of comparative example 3, the hardness of the heat conductive carbon fiber silica gel gasket using example 5 after 300 ℃/100H is only increased by about 17%, whereas the hardness of the commercially available heat conductive carbon fiber silica gel gasket has been increased by about 60%, and the hardness thereof has reached Shore oo 90 or more, which has completely lost the compressive property required for the heat conductive gasket.

Through the above embodiments, it can be confirmed that, compared with commercially available heat-conducting carbon fiber silica gel gaskets of the same specification, the heat-conducting carbon fiber silica gel gasket using the technical scheme has significantly lower heat conductivity change rate and hardness change rate under the high-temperature aging condition of 300 ℃/100H, thoroughly meets the use requirements in the technical field of wireless communication with high temperature resistance and fast heat dissipation, such as 5G communication, and provides an effective solution for various types of outdoor electronic facilities.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (9)

1. The utility model provides an ultra-high temperature resistant high thermal conductivity carbon fiber silica gel gasket which characterized in that, according to the part by mass, the raw materials contains: 15-35 parts of organic solvent, 5-12 parts of silicon rubber, 1-5 parts of silicone oil, 1-3 parts of reinforcing agent, 0.2-0.5 part of coupling agent, 10-25 parts of carbon fiber, 40-60 parts of heat-conducting filler, 0.5-1.5 parts of cross-linking agent, 0.1-0.3 part of thixotropic agent, 0.02-0.05 part of alkynol inhibitor and 0.1-0.5 part of platinum catalyst.

2. The ultra-high temperature resistant high thermal conductivity carbon fiber silicone gasket as claimed in claim 1, wherein said silicone rubber is selected from heat resistant compounded silicone rubber.

3. The ultrahigh-temperature-resistant high-thermal-conductivity carbon fiber silica gel gasket according to claim 1, wherein the reinforcing agent is selected from one or more of white carbon black, calcium carbonate or zinc oxide.

4. The ultra-high temperature resistant high thermal conductivity carbon fiber silicone gasket of claim 1, wherein said carbon fibers are selected from pitch-based carbon fibers.

5. The ultrahigh-temperature-resistant high-thermal-conductivity carbon fiber silicone gasket according to claim 4, wherein the carbon fibers are 2K long fibers with a linear diameter of 8-12 μm and a thermal conductivity of 600W/(m-K) or more.

6. The ultrahigh temperature-resistant high thermal conductivity carbon fiber silica gel gasket according to claim 1, wherein the thermal conductive filler is selected from spherical alumina or spherical aluminum nitride, and the particle size is 3-5 μm.

7. The preparation method of the ultrahigh temperature resistant high thermal conductivity carbon fiber silica gel gasket according to any one of claims 1 to 6, characterized by comprising the following steps:

s1: slicing the silicon rubber, putting the sliced silicon rubber into a container, and pouring a certain amount of organic solvent to soak and soften the silicon rubber for 2 to 3 hours;

s2: after the silicon rubber is softened, transferring the silicon rubber and the organic solvent to a planetary stirrer together; adding silicone oil, a coupling agent, a cross-linking agent and a thixotropic agent, and stirring for 1-2.5 hours at the rotating speed of 20-30rpm by planetary stirring;

s3: adding a reinforcing agent, a heat-conducting filler, an alkynol inhibitor and a platinum catalyst, stirring uniformly by planetary stirring at a rotating speed of 15-30rpm for 80-130 minutes to obtain a sizing material;

s4: testing the viscosity of the rubber material, and gradually adding the organic solvent to adjust the viscosity to the specification; vacuumizing the sizing material for 5-10 minutes, and standing for more than 30 minutes;

s5: uniformly and vertically fixing the carbon fibers by using a special die, slowly injecting the sizing material, and soaking for more than 0.5 hour after injection is finished;

s6: transferring the special mold to a vacuum oven, and keeping the special mold for 1-2 hours at the temperature of 50-80 ℃ and the vacuum degree of-0.09-0.07 MPa;

s7: transferring the whole special die to a precision oven, adjusting the temperature to 100-120 ℃, baking for 1-2 hours, and curing and forming to obtain a semi-finished product;

s8: and taking the semi-finished product out of the special die, performing die cutting in a direction vertical to the carbon fiber, performing die cutting with different thicknesses according to requirements, and cutting the rim charge to the size of the finished product to obtain the finished product.

8. The method for preparing the ultrahigh-temperature-resistant high-thermal-conductivity carbon fiber silicone gasket according to claim 7, wherein in the step S3, the specific steps are as follows:

s301: adding the reinforcing agent, stirring uniformly by planetary stirring at the rotating speed of 25rpm for 20-30 minutes;

s302: adding half of the heat-conducting filler, and stirring for 15-20 minutes at a rotating speed of 25rpm by planetary stirring; adding the other half of the heat-conducting filler, and stirring uniformly by planetary stirring at the rotating speed of 20rpm for 15-20 minutes;

s303: adding alkynol inhibitor, stirring for 10-15 minutes at 15rpm by planetary stirring until the mixture is uniform;

s304: adding a platinum catalyst, stirring uniformly by planetary stirring at a rotating speed of 15rpm for 20-25 minutes; scraping off the material of the material cylinder wall and the stirring paddle of the planetary stirrer by using a scraping knife, and stirring at the rotating speed of 15rpm for 20-25 minutes until the material is uniform.

9. The method for preparing the ultrahigh-temperature-resistant high-thermal-conductivity carbon fiber silicone gasket according to claim 7, wherein in the step S6, the specific steps are as follows:

transferring the special mold to a vacuum oven, adjusting the temperature to 50-60 ℃ and the vacuum degree to-0.07 MPa, and keeping for 30-50 minutes; then the temperature is adjusted to 70-80 ℃ and the vacuum degree is adjusted to-0.09 MPa, and the temperature is kept for 30-50 minutes.

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