WO2024239423A1 - Low-volatility, high-thermal-conductivity and single-component addition-type thermal conductive cement and preparation method therefor - Google Patents

Abstract

The present invention relates to the technical field of heat transfer, and in particular relates to a low-volatility, high-thermal-conductivity and single-component addition-type thermal conductive cement and a preparation method therefor. The thermal conductive cement is prepared from, in parts by weight, the following raw materials: 100 parts of a vinyl-terminated polydimethylsiloxane, 700-1000 parts of a thermal conductive filler, 0-5 parts of fumed silica, 1-10 parts of a hydrogen-containing silicone oil, and 0.2-2 parts of a catalyst. The main body of the thermal conductive filler is mesoporous alumina; at least part of the surface of the mesoporous alumina is loaded with nano-copper particles, and at least part of the surface of the mesoporous alumina and nano-copper particles is coated with a silicon dioxide layer; and the surface of the silicon dioxide layer is grafted with an inhibitor containing an unsaturated functional group. By means of the preparation method of the present invention, the inhibitor containing an unsaturated functional group is grafted and introduced into the thermal conductive filler, such that the catalytic activity of a platinum catalyst at normal temperature can be effectively inhibited, thereby effectively reducing the reaction activity of the thermal conductive cement, and improving the normal-temperature storage performance thereof.

Description

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive and a preparation method thereof Technical Field

The present invention relates to the field of heat transfer technology, and in particular to a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive and a preparation method thereof.

Background Art

Thermally conductive silicone materials are usually obtained by adding various thermally conductive fillers to a silicone polymer as a carrier. Commonly used thermally conductive fillers are aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon carbide, etc. Thermally conductive silicone gaskets are formed by curing, and the material has little deformation and cannot be reused. Thermal conductive silicone grease is an oil-powder mixture that will not solidify. If used for a long time at high temperature, silicone oil will precipitate, and the material will become dry and powdery and cannot be used. Thermal conductive mud has good thermal conductivity and heat transfer properties. When used, it is in the shape of plasticine, does not flow, does not volatilize, is resistant to high and low temperatures, and is easy to use. It is filled between electronic components and radiators to make them in close contact, reduce thermal resistance, quickly reduce the temperature of electronic devices, and extend the service life and reliability of electronic devices.

Patent CN106398226A discloses a thermally conductive silicone gel and a preparation method thereof, using vinyl-terminated polydimethylsiloxane or vinyl polymethylvinylsiloxane, 100 parts of base polymer; 0.1‑10 parts of cross-linking agent; 500‑1800 parts of filler; and 0.1‑15 parts of silane coupling agent. However, the use of low molecular weight vinyl-terminated polydimethylsiloxane or vinyl polymethylvinylsiloxane for a long time in a high temperature environment cannot solve the problem of low molecular weight precipitation.

Patents CN104497575A/CN111019357A both disclose a kind of organic silicone high thermal conductivity mud, whose raw materials consist of: silicone oil, thermal conductive powder filler, plasticizer, powder surface treatment agent, cross-linking agent, high temperature resistant colorant, platinum catalyst. It involves a kind of thermal conductive gel. During the production process, under the action of the catalyst, the vinyl silicone oil reacts with the cross-linking agent to cross-link and finally prepare into thermal conductive silicone mud. However, this kind of thermal conductive gel that has reacted during the production process generally has certain shortcomings of toughness, hardness, and poor extrusion, which directly affects the use of customers.

Patent CN111171571A discloses a highly elastic thermally conductive gel, which is formed by a reaction of α, ω alkoxy-terminated polydimethylsiloxane with dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane or diphenyldiethoxysilane. This patent cannot solve the problems of overall solidification and oil precipitation.

Patent CN113024164A involves a single-component high-fluidity and high-thermal-conductivity gel. This patent uses nano-gas-phase silica to adsorb platinum catalysts, and then wraps them with polymer resins to ultimately achieve long-term stability in room temperature storage. This patent simply states that a storage-stable thermally conductive gel can be prepared according to the method in the patent, but does not discuss it in detail.

Currently, the thermal conductive gels on the market are mainly non-reactive, which are prepared by cross-linking vinyl polysiloxane and hydrogen-containing polysiloxane under the catalysis of platinum catalyst. The biggest problem is that cross-linking has been formed during the preparation process, resulting in poor extrusion and limited use.

There are few reports on reactive thermally conductive gels on the market. They are mainly made by mixing vinyl polysiloxane, hydrogen-containing polysiloxane, thermally conductive fillers, acetylene alcohol inhibitors, and platinum catalysts. They are heated and cured into thermally conductive gels when used. Their main problem is that they have a short storage time at room temperature and must be stored for a long time in a frozen state, which makes them inconvenient to use and limits their scope of application.

Summary of the invention

Therefore, the purpose of the present invention is to provide a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive and a preparation method thereof to overcome the above problems, as the thermal conductive adhesive in the prior art is prone to volatilization and oil separation, and the reactive thermal conductive adhesive has a short storage time.

To achieve the above-mentioned invention purpose, the present invention is implemented through the following technical solutions:

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive, which is composed of the following raw materials in proportion by weight: 100 parts of vinyl-terminated polydimethylsiloxane, 700-1000 parts of thermal conductive filler, 0-5 parts of fumed silica, 1-10 parts of hydrogen-containing silicone oil, and 0.2-2 parts of a catalyst;

The main body of the thermal conductive filler is mesoporous alumina;

At least a portion of the surface of the mesoporous alumina is loaded with nano copper particles

At least a portion of the surface of the mesoporous aluminum oxide and the nano copper particles is coated with a silicon dioxide layer;

An inhibitor containing an unsaturated functional group is grafted onto the surface of the silicon dioxide layer.

Compared with the prior art, the low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive in the present invention has made certain modifications and improvements to the thermal conductive filler filled inside, thereby effectively improving the thermal conductivity of the thermal conductive filler and effectively extending the storage stability of the thermal conductive adhesive.

This application has made the following improvements to the thermal conductivity of thermally conductive fillers:

In the prior art, the thermal conductive fillers used to fill silicone potting glue to improve its thermal conductivity are mainly selected from metal oxides and metal nitrides. Aluminum oxide is the most widely used in organic potting glue because it has a higher thermal conductivity among metal oxides and is cheap and has excellent insulation properties. However, the thermal conductivity of aluminum oxide can only be maintained at about 30 W·m ^-1 ·K ^-1 , which is still relatively low compared to metal materials and carbon materials. Therefore, in order to improve the thermal conductivity of organic potting glue, the amount of aluminum oxide added can only be further increased. However, the large amount of thermal conductive material added will cause the other properties of organic potting glue (leveling and mechanical properties) to decrease to varying degrees, which seriously affects its own use.

The thermally conductive filler provided in the present application is also based on aluminum oxide material. However, a certain amount of nano-copper particles are loaded on the surface of the aluminum oxide. Therefore, compared with aluminum oxide, the thermal conductivity of metallic copper can be as high as 398 W·m ^-1 ·K ^-1 . Therefore, the addition of nano-copper particles can effectively improve the thermal conductivity of the overall thermally conductive filler to a certain extent.

However, the surface of conventional alumina fillers (such as spherical alumina) is relatively smooth, which causes the nano-copper particles to easily fall off the surface of alumina during the process of loading the nano-copper particles. Therefore, in this application, mesoporous silica is used to increase the contact area with the nano-copper particles, so that the nano-copper particles can better adhere to the surface of alumina. It was found from actual tests that the thermal conductive filler containing mesoporous alumina has significantly better thermal conductivity than the thermal conductive filler containing traditional spherical alumina.

Although the addition of nano copper particles can effectively improve the thermal conductivity of thermally conductive fillers, the applicant has found that although the content of nano copper particles is not high, it will greatly increase the conductivity of the overall potting compound, which is not conducive to its application in the electronics industry. Therefore, the present application coats at least a portion of the surface of the mesoporous alumina and nano copper particles with a layer of silicon dioxide. Compared with alumina, silicon dioxide has a lower resistivity. Therefore, after the surfaces of both are coated with silicon dioxide, the present application can shield the conductivity of the nano copper particles and prevent the nano copper particles from being oxidized by oxygen, thereby reducing their thermal conductivity.

In order to extend the storage stability of thermal conductive paste by thermal conductive fillers, this application has made the following improvements:

In order to improve the stability of single-component addition-type thermal conductive paste in the prior art, a certain amount of inhibitors (such as substances containing S or P elements, unsaturated compounds, etc.) are usually added to the thermal conductive paste. These substances are usually small molecules. These small molecule inhibitors often migrate, precipitate and volatilize during storage, thereby weakening the inhibitory effect on the components in the paste, thereby significantly reducing its storage stability. In the present application, inhibitors containing unsaturated functional groups are grafted onto the surface of the silica layer covering the mesoporous alumina and the surface of the nano-copper particles, thereby effectively preventing the precipitation of these inhibitors, thereby preventing the reaction of vinyl-terminated polydimethylsiloxane with hydrogen-containing silicone oil at room temperature, and this process can be destroyed and reversed at high temperatures, so that the platinum metal catalyst can still catalyze the reaction between vinyl-terminated polydimethylsiloxane and hydrogen-containing silicone oil at high temperatures, and because the inhibitors contain unsaturated functional groups, these unsaturated functional groups can also react with hydrogen-containing silicone oil, so that the various components in the entire thermal conductive putty form a cross-linked network, further improving the mechanical properties of the putty after curing.

Therefore, in summary, the present application combines alumina, nano copper particles and silicon dioxide to obtain a thermally conductive material with higher thermal conductivity and lower electrical conductivity. This can effectively reduce the amount of thermally conductive filler used in silicone sealants and effectively improve the leveling and mechanical properties of the sealant. At the same time, this specially modified thermally conductive filler can effectively improve the room temperature storage performance of the thermally conductive glue.

Preferably, the preparation method of the thermally conductive filler is as follows:

(1) reacting alumina with an etching solution to obtain spherical mesoporous alumina;

(2) placing mesoporous alumina in a solution containing a copper precursor and a silicon dioxide precursor with silicon hydrogen and silicon alkoxy groups, and adding an acidic reducing agent after uniform dispersion, so that the copper precursor is reduced to obtain nano copper particles, and the silicon dioxide precursor is hydrolyzed to form polysiloxane, thereby coating the mesoporous alumina and the nano copper particles, and obtaining mesoporous alumina loaded with nano copper particles and polysiloxane;

(3) A mesoporous alumina loaded with nano-copper particles and polysiloxane is subjected to a condensation reaction with an alcohol inhibitor containing an unsaturated group to obtain the thermal conductive filler.

During the preparation process, the thermal conductive filler of the present invention first etches the aluminum oxide with an etching solution. The etching solution can be an acid solution or an alkaline solution, both of which have a good etching effect on aluminum oxide. Thus, it can react on the surface of the aluminum oxide, thereby obtaining a mesoporous structure on the surface.

Subsequently, the mesoporous alumina is placed in a solution containing a copper precursor and a silica precursor with silicon hydrogen and silicon alkoxy groups. After being evenly dispersed, an acidic reducing agent is added. The copper precursor is reduced under the action of the acidic reducing agent to form nano-copper particles. Part of these nano-copper particles are embedded in the pores on the surface of the mesoporous alumina, and part of them are free in the solution. Since the formed nano-copper particles can coordinate with the silica precursor with alkoxy groups, the nano-copper particles are covered. At the same time, since the silica precursor contains alkoxy groups, it will undergo a hydrolysis reaction under acidic conditions, thereby forming a cross-linked polysiloxane structure after hydrolysis, and wrapping the alumina and nano-copper particles together, so that the alumina can achieve effective loading of the nano-copper particles.

Preferably, the silicon dioxide precursor containing silicon hydrogen and silicon alkoxy groups in step (2) is any one of trimethoxysilane, methyldimethoxysilane, triethoxysilane and methyldiethoxysilane.

Preferably, the alcohol inhibitor containing an unsaturated group in step (3) is any one of acetylene cyclohexanol, acetylene alcohol, propynol, butynol, methyl butynol, tert-butyl cyclohexanol, phenyl butynol, 3,5-dimethyl-1-hexyne-3-ol, 3,6-dimethyl-1-heptyne-3-3,7,11-trimethyldodecyne-3-ol.

Preferably, the viscosity of the vinyl-terminated polydimethylsiloxane is between 100 and 10,000 mPa.s.

Preferably, the fumed silica is fumed silica treated with hexamethyldisilazane, and has a specific surface area of 100 to 600 m ² /g.

Preferably, the hydrogen-containing silicone oil is a mixture of one or more hydrogen-containing silicone oils having a hydrogen content between 0.1 and 0.75%.

Preferably, the catalyst is a Castel catalyst, with an effective platinum content of 3000~8000ppm.

In a second aspect, the present invention also provides a method for preparing the low-stress, low-volatile, high-thermal-conductivity single-component addition-type thermal conductive adhesive as described above, comprising the following steps:

(S.1) Mix and stir vinyl-terminated polydimethylsiloxane, thermal conductive filler and fumed silica to obtain a base material;

(S.2) Add hydrogen-containing silicone oil and catalyst into a mixer containing the above base material, stir evenly, and obtain a low-stress, high-thermal-conductivity, heat-curable thermally conductive gel.

Preferably, in the step (S.1), the mixing and stirring temperature is 120-170°C, the vacuum degree is <-0.095MPa, and the mixture is dehydrated for 120-240min and then cooled to room temperature;

In the step (S.2), the vacuum degree is <-0.095MPa, and the stirring is performed at a rotation speed of 10-20 Hz for 60-180 min.

Therefore, the present invention has the following beneficial effects:

(1) The present invention can effectively inhibit the catalytic activity of the platinum catalyst at room temperature by grafting an inhibitor containing an unsaturated functional group into the thermal conductive filler, thereby effectively reducing the reaction activity of the thermal conductive mortar and improving its storage performance at room temperature;

(2) The present application effectively improves the thermal conductivity of the thermally conductive filler without affecting the electrical conductivity by introducing nano copper particles and silica coatings into the thermally conductive filler;

(3) This application can significantly reduce the viscosity of the system, slow down the oil-powder separation, and improve the anti-settling effect of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an electron microscope photograph of the thermal conductive filler A1 of the present invention.

Implementation

The present invention is further described below in conjunction with the drawings and specific embodiments of the specification. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only part of the embodiments of the present invention, rather than all of the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making any creative work should fall within the scope of protection of the present invention.

【Preparation of thermal conductive filler】

Thermal conductive filler A1: Its preparation method is as follows:

(1) At room temperature, immersing the spherical alumina in a 0.005 mol/L sodium hydroxide solution for 15 min, allowing the spherical alumina to react with the sodium hydroxide for 30 min, and then filtering and washing to obtain spherical mesoporous alumina;

(2) 500 g of mesoporous alumina was placed in a solution containing 2 L of 30 g of copper sulfate pentahydrate and 24.5 g (0.2 mol) of trimethoxysilane, and dispersed evenly to form a suspension. Then, 40 g of citric acid was added and continued to be stirred and dispersed. The mixture was then heated to 75° C. and stirred for 2 h to reduce the copper sulfate to obtain nano-copper particles and hydrolyze the trimethoxysilane to form polysiloxane to coat the mesoporous alumina and the nano-copper particles. The mixture was filtered and dried at 80° C. for 5 h to obtain mesoporous alumina loaded with nano-copper particles and polysiloxane.

(3) The obtained mesoporous alumina loaded with nano-copper particles and polysiloxane was placed in 1L of toluene solution, and then 0.01g of tri(pentafluorophenyl)borane was added thereto. After mixing evenly, 6.2g (0.05mol) of acetylene cyclohexanol was added dropwise thereto. The mixture was stirred for reaction at room temperature for 2h, and then filtered and dried to obtain the thermal conductive filler A1, an electron microscope photograph of which is shown in FIG1 .

Thermal conductive filler A2: Its preparation method is as follows:

(1) At room temperature, immersing the spherical alumina in a 0.005 mol/L sodium hydroxide solution for 15 min, allowing the spherical alumina to react with the sodium hydroxide for 30 min, and then filtering and washing to obtain spherical mesoporous alumina;

(2) 500 g of mesoporous alumina was placed in a solution containing 2 L of 35 g of copper chloride and 24.5 g (0.2 mol) of trimethoxysilane, and dispersed evenly to form a suspension. Then, 30 g of ascorbic acid was added and continued to be stirred and dispersed. The mixture was then heated to 60° C. and stirred for 4 h to reduce the copper chloride to obtain nano-copper particles and hydrolyze the trimethoxysilane to form polysiloxane to coat the mesoporous alumina and the nano-copper particles. The mixture was filtered and dried at 85° C. for 5 h to obtain mesoporous alumina loaded with nano-copper particles and polysiloxane.

(3) The obtained mesoporous alumina loaded with nano-copper particles and polysiloxane was placed in 1L of toluene solution, and then 0.01g of tri(pentafluorophenyl)borane was added thereto. After mixing evenly, 4.2g (0.05mol) of methylbutynol was added dropwise thereto. The mixture was stirred at room temperature for 2h and then filtered and dried to obtain the thermal conductive filler A2.

Thermal conductive filler A3: Its preparation method is as follows:

(1) At room temperature, immersing the spherical alumina in a 0.005 mol/L sodium hydroxide solution for 15 min, allowing the spherical alumina to react with the sodium hydroxide for 30 min, and then filtering and washing to obtain spherical mesoporous alumina;

(2) 500 g of mesoporous alumina was placed in a solution containing 2 L of 24.5 g (0.2 mol) of trimethoxysilane and dispersed evenly to form a suspension. Then, 30 g of ascorbic acid was added and the mixture was stirred and dispersed. The mixture was then heated to 60 ° C and stirred for 4 h to allow the trimethoxysilane to hydrolyze to form polysiloxane, thereby coating the mesoporous alumina. The mixture was filtered and dried at 85 ° C for 5 h to obtain mesoporous alumina coated with polysiloxane.

(3) The obtained mesoporous alumina coated with polysiloxane was placed in 1L of toluene solution, and then 0.01g of tri(pentafluorophenyl)borane was added thereto. After mixing evenly, 4.2g (0.05mol) of methylbutynol was added dropwise thereto. The mixture was stirred for reaction at room temperature for 2h, and then filtered and dried to obtain the thermal conductive filler A3.

Example 1

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of thermal conductive filler A1 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at a temperature of 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 2

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 700 parts of thermal conductive filler A1 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 3

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 1000 parts of thermal conductive filler A1 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at a temperature of 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 4

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, thermal conductive filler A2 900 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at a temperature of 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 5

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, and 900 parts of thermal conductive filler A1 with a D50 of 20 um were added into a mixer, and the mixture was dehydrated, blended and kneaded for 180 minutes at a temperature of 150°C and a vacuum degree of -0.095 MPa, and then cooled to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 6

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of thermal conductive filler A1 with a D50 of 20 um, and 2 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at a temperature of 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

At room temperature, 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% were added into a power vacuum planetary mixer filled with the above base material, and stirred for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 7

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of thermal conductive filler A1 with a D50 of 20 um, and 5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at a temperature of 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 8

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of thermal conductive filler A1 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at 170°C and a vacuum degree of -0.095 MPa for 240 minutes, and cool to obtain a base rubber;

Add 1 part of dimethylmethylhydrogensiloxane with a hydrogen content of 0.75% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 10hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 9

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, 100 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of thermal conductive filler A1 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane are added into a mixer, dehydrated and blended for 120 minutes at a temperature of 120°C and a vacuum degree of -0.095 MPa, and cooled to obtain a base rubber;

Add 10 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.1% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 2 parts of 3000PPM Custer platinum catalyst at room temperature and add into a power vacuum planetary mixer filled with the above base materials. Set the vacuum degree to -0.095Mpa and the rotation speed to 20hz. Stir for 180min to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Example 10

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 100 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 900 parts of thermal conductive filler A1 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 20 Hz to obtain a thermal conductive gel intermediate.

Mix 1.5 parts of 5000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain the finished thermal conductive gel.

Example 11

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, 100 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of thermal conductive filler A1 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane are added into a mixer, and the mixture is dehydrated, blended and kneaded for 180 minutes at a temperature of 150°C and a vacuum degree of -0.095 MPa, and cooled to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 20 Hz to obtain a thermal conductive gel intermediate.

Mix 1.5 parts of 5000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain the finished thermal conductive gel.

Comparative Example 1

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of thermal conductive filler A3 with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

At room temperature, 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% were added into a power vacuum planetary mixer filled with the above base material, and stirred for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15hz to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive intermediate.

Mix 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add it into a power vacuum planetary mixer filled with the above base material. Mix at a vacuum degree of -0.095Mpa and a rotation speed of 15hz for 60 minutes to obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive product.

Comparative Example 2

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 200 mPa.s, 50 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of alumina powder with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 m ² /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a thermal conductive gel intermediate.

Mix 1 part of acetylene cyclohexanol and 1.5 parts of 3000PPM Custer platinum catalyst at room temperature and add into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain the finished thermal conductive gel.

Comparative Example 3

A low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive is prepared according to the following steps:

At 25°C, add 100 parts of vinyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa.s, 900 parts of alumina powder with a D50 of 20 um, and 0.5 parts of fumed silica with a specific surface area of 200 ^m2 /g treated with hexamethyldisilazane into a mixer, dehydrate and blend at 150°C and a vacuum degree of -0.095 MPa for 180 minutes, and cool to obtain a base rubber;

Add 5 parts of dimethylmethylhydrogensiloxane with a hydrogen content of 0.18% into a power vacuum planetary mixer filled with the above base material at room temperature. Stir for 120 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain a thermal conductive gel intermediate.

Mix 2 parts of hydroxybutadiene, 1 part of dodecyne-3-ol and 1.5 parts of 5000PPM Custer platinum catalyst at room temperature and add into a power vacuum planetary mixer filled with the above base materials. Stir for 60 minutes at a vacuum degree of -0.095Mpa and a rotation speed of 15Hz to obtain the finished thermal conductive gel.

Table 1: Component ratio of silicone potting glue in Examples 1 to 5 and Comparative Example 1

Note: The unit of each component in the above table is "part".

Performance testing: The following performance tests were carried out on the thermal conductive glues prepared in Examples 1 to 10 and Comparative Examples 1 to 3 and the cured colloids. The specific test data are shown in Table 2.

Extrusion performance: Extrusion performance is tested in accordance with GB/T 14683-2017.

Storage time: Store the thermal conductive adhesive at room temperature for 91 days and observe the change in its viscosity.

Curing time: Place the thermal conductive adhesive in a 100°C environment and measure its curing time.

Thermal conductivity: Thermal conductivity is tested in accordance with GB/T10297-2015.

Toughness/hardness: Solidify the thermal conductive glue to obtain a colloid, cut the colloid into thin slices 2~3 mm thick, fold it in half, observe whether it can be broken and test its Shore hardness at the same time.

Table 2

 From the data in Table 2 above, it can be seen that the preparation method of the present invention can effectively inhibit the catalytic activity of the platinum catalyst at room temperature by grafting an inhibitor containing an unsaturated functional group into the thermal conductive filler, thereby effectively reducing the reaction activity of the thermal conductive mortar and improving its room temperature storage performance. It can still remain normal after 90 days of storage. At the same time, the introduction of nano copper particles and a silicon dioxide layer into the thermal conductive filler can effectively improve its thermal conductivity without affecting the electrical conductivity, and can greatly reduce the viscosity of the system, slow down the separation of oil and powder, and improve the anti-settling effect of the system.

Claims (10)

A low volatility, high thermal conductivity, single-component addition-type thermal conductive adhesive, characterized in that: It is composed of the following raw materials in proportion by weight: 100 parts of vinyl-terminated polydimethylsiloxane, 700-1000 parts of thermal conductive filler, 0-5 parts of fumed silica, 1-10 parts of hydrogen-containing silicone oil, and 0.2-2 parts of catalyst; The main body of the thermal conductive filler is mesoporous alumina; At least a portion of the surface of the mesoporous alumina is loaded with nano copper particles At least a portion of the surface of the mesoporous aluminum oxide and the nano copper particles is coated with a silicon dioxide layer; An inhibitor containing an unsaturated functional group is grafted onto the surface of the silicon dioxide layer. The low volatility, high thermal conductivity, single-component addition-type thermal conductive adhesive according to claim 1 is characterized in that: The preparation method of the thermal conductive filler is as follows: (1) reacting alumina with an etching solution to obtain spherical mesoporous alumina; (2) placing mesoporous alumina in a solution containing a copper precursor and a silicon dioxide precursor with silicon hydrogen and silicon alkoxy groups, and adding an acidic reducing agent after uniform dispersion, so that the copper precursor is reduced to obtain nano copper particles, and the silicon dioxide precursor is hydrolyzed to form polysiloxane, thereby coating the mesoporous alumina and the nano copper particles, and obtaining mesoporous alumina loaded with nano copper particles and polysiloxane; (3) A mesoporous alumina loaded with nano-copper particles and polysiloxane is subjected to a condensation reaction with an alcohol inhibitor containing an unsaturated group to obtain the thermal conductive filler. The low volatility, high thermal conductivity, single-component addition-type thermal conductive adhesive according to claim 2 is characterized in that: The silicon dioxide precursor containing silicon hydrogen and silicon alkoxy in step (2) is any one of trimethoxysilane, methyldimethoxysilane, triethoxysilane and methyldiethoxysilane. The low volatility, high thermal conductivity, single-component addition-type thermal conductive adhesive according to claim 2 or 3 is characterized in that: The alcohol inhibitor containing an unsaturated group in step (3) is any one of acetylene cyclohexanol, acetylene alcohol, propynol, butynol, methyl butynol, phenyl butynol, 3,5-dimethyl-1-hexyne-3-ol, 3,6-dimethyl-1-heptyne-3-3,7,11-trimethyldodecyne-3-ol. The low volatility, high thermal conductivity, single-component addition-type thermal conductive adhesive according to any one of claims 1 to 3 is characterized in that: The viscosity of the vinyl-terminated polydimethylsiloxane is 100-10000 mPa.s. The low volatility, high thermal conductivity, single-component addition-type thermal conductive adhesive according to any one of claims 1 to 3 is characterized in that: The fumed silica is fumed silica treated with hexamethyldisilazane, and has a specific surface area of 100 to 600 m ² /g. The low volatility, high thermal conductivity, single-component addition-type thermal conductive adhesive according to any one of claims 1 to 3 is characterized in that: The hydrogen-containing silicone oil is a mixture of one or more hydrogen-containing silicone oils with a hydrogen content between 0.1 and 0.75%. The low-volatility, high-thermal-conductivity, single-component addition-type thermal conductive adhesive according to any one of claims 1 to 3 is characterized in that the catalyst is a Castel catalyst with an effective platinum content of 3000 to 8000 ppm. The method for preparing the low-volatile, high-thermal-conductivity, single-component addition-type thermal conductive adhesive as described in claims 1 to 8 is characterized in that: The following steps are involved: (S.1) Mix and stir vinyl-terminated polydimethylsiloxane, thermal conductive filler and fumed silica to obtain a base material; (S.2) Add hydrogen-containing silicone oil and catalyst into a mixer containing the above base material respectively, stir evenly, and obtain a low-volatile and high-thermal-conductivity single-component addition-type thermal conductive adhesive. The method according to claim 9 is characterized in that In the step (S.1), the mixing and stirring temperature is 120-170°C, the vacuum degree is ≤-0.095MPa, and the mixture is dehydrated for 120-240min and then cooled to room temperature; In the step (S.2), the vacuum degree is ≤-0.095MPa, and the stirring is performed at a rotation speed of 10-20 Hz for 60-180 min.