WO2024088062A1

WO2024088062A1 - Thermally-conductive addition type organosilicon composition for potting

Info

Publication number: WO2024088062A1
Application number: PCT/CN2023/123962
Authority: WO
Inventors: 雷丽娟; 郭鹏; 申晶
Original assignee: 江西蓝星星火有机硅有限公司
Priority date: 2022-10-27
Filing date: 2023-10-11
Publication date: 2024-05-02
Also published as: CN115612446B; CN115612446A

Abstract

The present application relates to a thermally-conductive addition type organosilicon composition for potting, a method for preparing the organosilicon composition, and a product prepared from the organosilicon composition. The organosilicon composition comprises: A) at least one polysiloxane containing, per molecule, at least two vinyl groups bonded to a silicon atom; B) at least one hydrogen-containing polysiloxane having, per molecule, at least one hydrogen atom bonded to the same or different silicon atoms, provided that the component has a total of at least two hydrogen atoms bonded to the same or different silicon atoms; C) at least one platinum group metal catalyst; and D) a thermally-conductive filler, particles of the thermally-conductive filler being treated by using a vinyltrialkoxysilane oligomer or hydrolysate and having a D50 particle size ranging from 0.5 to 50 microns.

Description

Thermally conductive addition-type silicone composition for potting

Technical Field

The present application relates to a heat-conductive addition-type silicone composition for potting, a method for preparing the silicone composition, and a product made from the silicone composition. The silicone composition of the present invention can be used in the field of new energy.

Background technique

With the rapid development of the global new energy sector, there are increasing demands for improved power and reduced size of devices such as battery power supplies or electronic devices. However, increased power and reduced size will lead to a significant increase in the amount of heat that must be dissipated. According to statistics, more than 50% of electronic failures are caused by heat dissipation problems. In order to allow different parts to work at the right temperature to ensure their functional safety and service life, heat dissipation management has become a key issue for all electronic devices, power modules, energy storage, etc. in the new energy field.

Thermally conductive addition-type silicone potting compound has been used for heat dissipation management in the new energy field. It can be deeply potted and no low molecular weight substances are produced during the curing process. The shrinkage rate is extremely low, and it can also be heated and cured quickly. Thermally conductive silicone potting compound can improve the thermal management performance of high-power equipment by quickly dissipating heat, protecting fragile components and reducing stress.

However, a common problem when using this type of silicone potting compound is that as the filling rate of the thermal conductive filler in the system increases, although the thermal conductivity will be significantly improved, the system viscosity will increase, the thixotropic index will increase, resulting in poor fluidity. At the same time, since the density of the thermal conductive filler is greater than the density of the silicone oil itself, as the filling rate of the thermal conductive filler increases, the powder is prone to sedimentation and bottom agglomeration during long-term storage, resulting in problems such as being unusable.

Therefore, there is a continuous requirement in the prior art for improving the thermal conductivity of the silicone potting compound while maintaining good fluidity and thixotropy.

Summary of the invention

Therefore, the first aspect of the present application relates to a thermally conductive addition-type silicone composition for potting, comprising:

A) at least one polysiloxane comprising at least two vinyl groups bonded to silicon atoms per molecule;

B) at least one hydrogen-containing polysiloxane having at least one hydrogen atom per molecule bonded to the same or different silicon atoms, provided that the component has a total of at least two hydrogen atoms bonded to the same or different silicon atoms;

C) a catalyst of at least one platinum group metal; and

D) A thermally conductive filler, the particles of which are treated with oligomers or hydrolysates of vinyltrialkoxysilane and have a D50 particle size in the range of 0.5-50 μm, preferably 1-40 μm, for example 5-30 μm.

The inventors of the present application have found that by specially modifying the thermally conductive filler and screening and compounding its particle size, the addition-type silicone potting composition containing the component can have improved thermal conductivity and excellent flowability. For example, the thermal conductivity of such a potting composition can reach 0.6W/m·K-2.0W/m·K, and the thixotropic index is 1.0-1.5, thus having good flowability.

Furthermore, according to a preferred embodiment of the present invention, component E) an anti-settling agent comprising white carbon treated with at least one polysiloxane and silazane compound containing at least two vinyl groups bonded to silicon atoms per molecule may be added.

It has been found that, with the addition of the anti-settling agent, the silicone composition for encapsulation prepared by the present invention can further have excellent storage stability. After long-term storage (e.g., ≥6 months), it has excellent anti-settling performance and no lumps on the bottom, thus being able to give the material excellent comprehensive properties such as electrical insulation, flame retardancy and mechanical properties after curing.

Therefore, the thermally conductive addition-type silicone composition according to the present invention is particularly suitable for thermally conductive potting of thermal management components or electronic components in new energy fields such as wind power generation motor systems, photovoltaic energy storage systems, new energy vehicle battery modules, and on-board chargers.

The second aspect of the present application relates to a product comprising a thermally conductive potting compound formed from the organic silicon composition of the present invention. The product is preferably a thermal management component or electronic component in the new energy field such as a wind power generation motor system, a photovoltaic energy storage system, a new energy vehicle battery module, and an on-board charger.

The third aspect of the present application relates to an anti-settling agent, which comprises at least one White carbon treated with polysiloxane and silazane compounds containing at least two vinyl groups bonded to silicon atoms.

The fourth aspect of the present application relates to the use of the above-mentioned thermally conductive filler and anti-settling agent in a thermally conductive silicone composition for potting, for improving the thermal conductivity, thixotropy, flowability and/or storage stability of the potting compound.

Component A) in the present application is a vinyl-containing polysiloxane, wherein the vinyl group may be located at any position on the main chain of the polysiloxane, for example, at the end or in the middle of the molecular chain or at both ends and in the middle.

Preferably, the vinyl-containing polysiloxane comprises:

(i) Siloxy unit of formula (I-1)
R ¹ _a Z _b SiO _[4-(a+b)]/2 (I-1)

in

R ¹ represents a C _2-12 , preferably a C _2-6 alkenyl group, most preferably a vinyl group or an allyl group,

Z may identically or differently represent a monovalent hydrocarbon group having 1 to 30, preferably 1 to 12, carbon atoms, preferably selected from C _1-8 alkyl groups, including alkyl groups optionally substituted by at least one halogen atom, and also preferably selected from aryl groups, especially C _6-20 aryl groups,

a is 1 or 2, b is 0, 1 or 2 and the sum of a+b is 1, 2 or 3,

and (ii) optionally other siloxy units of formula (I-2)

in

Z has the meaning as described above and c is 0, 1, 2 or 3.

In a preferred embodiment, Z may be selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, phenyl, xylyl and tolyl, etc. Preferably, at least 60 mol% (or by number) of the groups Z are methyl.

Preferred vinyl-containing polysiloxanes suitable for the present invention may have a viscosity of at least 50 mPa·s and preferably less than 1200 mPa·s, for example 100-500 mPa·s. They are also commonly referred to as vinyl silicone oils. In the present application, all viscosities are related to dynamic viscosity values and can be measured, for example, in a known manner at 25° C. using conventional equipment such as a TA rheometer.

Furthermore, it is preferred that the vinyl content of the component is 0.1-2 wt%, more preferably 0.37 wt-1.2 wt%.

The vinyl group-containing polysiloxane (a1) may be formed only of the unit of formula (I-1) or may additionally contain the unit of formula (I-2). The vinyl group-containing polysiloxane may be linear, branched or cyclic.

Examples of the siloxy unit of formula (I-1) are vinyldimethylsiloxy, vinylphenylmethylsiloxy, vinylmethylsiloxy and vinylsiloxy units.

Examples of the siloxy unit of formula (I-2) are SiO _4/2 unit, dimethylsiloxy, methylphenylsiloxy, diphenylsiloxy, methylsiloxy and phenylsiloxy.

Examples of the vinyl-containing polysiloxane include linear or cyclic compounds such as dimethyl polysiloxane (having dimethyl vinyl silyl terminal groups), (methyl vinyl) (dimethyl) polysiloxane copolymers (having trimethyl silyl terminal groups), (methyl vinyl) (dimethyl) polysiloxane copolymers (having dimethyl vinyl silyl terminal groups) and cyclic methyl vinyl polysiloxanes. For example, the vinyl polysiloxane may be vinyl-terminated polydimethylsiloxane (Vi-PDMS) or vinyl-terminated polymethylvinylsiloxane (Vi-PMVS).

In the composition of the present invention, component B) is a hydrogen-containing polysiloxane which must have at least two hydrogen atoms bonded to the same or different silicon atoms in order to undergo a crosslinking reaction with the vinyl polysiloxane of component A). Therefore, as the hydrogen-containing polysiloxane component, at least one hydrogen-containing polysiloxane having at least two hydrogen atoms bonded to the same or different silicon atoms per molecule or a mixture of at least two hydrogen-containing polysiloxanes having at least one hydrogen atom bonded to the same or different silicon atoms per molecule can be used.

In component B) or in the hydrogen-containing polysiloxane or the mixture of hydrogen-containing polysiloxanes according to the present invention, the silicon hydride groups may be located at any position on the polysiloxane main chain, for example, at the ends or in the middle of the molecular chain or at both ends and in the middle.

The hydrogen-containing polysiloxane having SiH groups can undergo a crosslinking reaction with component A), i.e., a cured product is formed by reacting the SiH groups in the component with the vinyl groups in component A). Preferably, as component B), at least one hydrogen-containing polysiloxane having two, three or more SiH groups per molecule is used.

In a preferred embodiment, the hydrogen-containing polysiloxane comprises

(i) Siloxy units of formula (I-3):
H _d R ² _e SiO _[4-(d+e)]/2 (I-3)

in

^R2 may be identical or different and represent a monovalent hydrocarbon group, which is preferably selected from _C1-8 alkyl groups, including alkyl groups optionally substituted by at least one halogen atom, and is also preferably selected from aryl groups, especially _C6-20 aryl groups,

d is 1 or 2, e is 0, 1 or 2 and the sum of d+e is 1, 2 or 3,

and optionally (ii) at least one other unit of formula (I-4)
R ³ _f SiO _(4-f)/2 (I-4)

in

R ³ has the meaning as described above and f is 0, 1, 2 or 3.

In a more preferred embodiment, R ³ can be selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, phenyl, xylyl and tolyl.

The dynamic viscosity of the component B) or the hydrogen-containing polysiloxane or the mixture thereof is at least 1 mPa·s and preferably between 3 and 1000 mPa·s, more preferably 5-100 mPa·s.

The hydrogen-containing polysiloxane may be formed only of the unit of formula (I-3) or may additionally contain the unit of formula (I-4). The hydrogen-containing polysiloxane may have a linear, branched or cyclic structure.

Examples of units of formula (I-3) are H(CH ₃ ) ₂ SiO _1/2 , HCH ₃ SiO _2/2 and H(C ₆ H ₅ )SiO _2/2 .

Examples of the unit of formula (I-4) may be the same as those given above for the unit of formula (I-2).

Examples of usable hydrogen-containing polysiloxanes include linear or cyclic compounds such as dimethylpolysiloxane (having hydrodimethylsilyl terminal groups), copolymers having (dimethyl)(hydrogenmethyl)polysiloxane units (having trimethylsilyl terminal groups), copolymers having (dimethyl)(hydrogenmethyl)polysiloxane units (having hydrodimethylsilyl terminal groups), hydromethylpolysiloxanes having trimethylsilyl terminal groups, and cyclic hydromethylpolysiloxanes.

In one embodiment, the hydrogen-containing polysiloxane may be a dimethylpolysiloxane containing a hydrogenated dimethylsilyl terminal group and an organopolysiloxane containing at least three hydrogenated silyl groups. mixture.

In a preferred embodiment, the component B) is at least one of hydrogen-terminated polydimethylmethylhydrogensiloxane H1, polydimethylmethylhydrogensiloxane H2 and hydrogenated Q resin H3. More preferably, the hydrogen content of H1 is 0.2wt-0.8wt%, the molar percentage of methylhydrogen chain segments in H2 is 3-50% and its viscosity ranges from 10-35mPa·s. Hydrogenated Q resin H3 can be commercially obtained, such as HQM-105 or HQM-107 from Gelest.

The catalyst C) of at least one platinum group metal may be composed of at least one platinum group metal or compound, and its amount should be sufficient to promote the addition reaction of the alkenyl group in component A) and the silyl hydrogen in component B) to cure. In an advantageous embodiment, the amount of the catalyst may be in the range of 0.1-1,000 ppm, preferably 1-50 ppm, based on the weight of the metal.

Catalysts of at least one platinum group metal are known in the organosilicon field and are commercially available. Platinum group metals include ruthenium, rhodium, palladium, osmium and iridium in addition to platinum. The catalyst may be composed of the following components: platinum group metals or compounds thereof or combinations thereof. Such catalysts include, but are not limited to: platinum black, chloroplatinic acid, platinum dichloride, chloroplatinic acid monohydric alcohol reactant. Preferably, a compound of platinum and rhodium is used. Platinum is generally the preferred catalyst.

A key component of the composition of the present invention is a thermally conductive filler, the particles of which are treated with oligomers or hydrolysates of vinyltrialkoxysilane and have a D50 particle size range of 0.5-50 microns, preferably 1-40 microns, such as 5-30 microns.

The inventors of the present application have found that the use of oligomers or hydrolyzates of vinyltrialkoxysilane as powder treatment agents for thermally conductive fillers is more suitable for improving the flowability of silicone compositions than other conventional treatment agents such as γ-glycidyloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane or other alkoxysilanes such as n-octyltrimethoxysilane, n-decyltrimethoxysilane and hexadecyltrimethoxysilane.

Here, the "alkoxy" in the oligomer or hydrolyzate of the vinyl trialkoxysilane can be an alkoxy group including C1-C12, such as C2-C8. Therefore, preferred oligomers or hydrolyzates of vinyl trialkoxysilane include oligomers or hydrolyzates of vinyl trimethoxysilane, vinyl triethoxysilane and vinyl tripropoxysilane.

Preferably, the vinyl content of the oligomer or hydrolyzate of the vinyltrialkoxysilane is It is 8-16 wt %, and preferably has a viscosity of 2-25 mPa·s, such as 5-15 mPa·s.

The thermally conductive filler itself includes, but is not limited to: spherical alumina, quasi-spherical alumina, angular alumina, aluminum hydroxide, aluminum nitride, boron nitride, silicon carbide, magnesium oxide, zinc oxide, spherical silica, rounded crystalline silicon powder, crystalline silicon powder, etc., preferably one or more of spherical alumina, quasi-spherical alumina, spherical silica, and rounded crystalline silicon powder.

The D50 particle size of thermal conductive fillers should be in the range of 0.5-50 microns to ensure the best thixotropic index and viscosity. The D50 particle size refers to the particle size value corresponding to the cumulative distribution percentage reaching 50%. It is one of the important indicators reflecting the particle size characteristics of powders, also known as the median diameter or median particle size. The measurement equipment for D50 is a laser particle size detector.

In a more preferred embodiment, based on the total volume of the thermally conductive filler, the volume percentage of the thermally conductive filler with a D50 particle size range of 15 μm or more is 80-95%, preferably 82-92%, the volume percentage of the thermally conductive filler with a D50 particle size range of 6 μm to less than 15 μm is 5-20%, preferably 8-16%, and the volume percentage of the thermally conductive filler with a D50 particle size range of less than 6 μm is 0-2%, for example 0.5-1.6%.

The treatment of the thermally conductive filler can be achieved by fully mixing the oligomer or hydrolyzate of vinyltrialkoxysilane with the particles of the thermally conductive filler under stirring. This mixing can be performed alone or in situ, and can be performed in the presence of other components such as anti-settling agents or catalysts, thereby achieving the treatment of the thermally conductive particles. At the same time, in the case where the composition is formulated into multiple components, the treated thermally conductive particles and the anti-settling agent and/or catalyst can advantageously constitute a single component.

Preferably, the amount of the treating agent, ie, the oligomer or hydrolyzate of vinyltrialkoxysilane, is 0.15%-1.5%, preferably 0.20%-1.0%, based on the weight of the thermally conductive filler.

Preferably, the total content of the thermally conductive filler is 65-96 wt %, such as 70-90 wt %, based on the total weight of the composition.

The composition of the invention may also advantageously comprise an anti-settling agent component E) comprising white carbon treated with at least one polysiloxane and silazane compound comprising at least two vinyl groups bonded to silicon atoms per molecule.

White carbon black is a general term for powdered products of amorphous silicic acid and silicates, including precipitated silica, fumed silica and ultrafine silica gel. In the embodiment, the white carbon black is selected from fumed silica. The white carbon black may generally have, for example, a primary particle size of about 3-50 nanometers and an aggregate particle size of about 150-400 nanometers. The white carbon black suitable for the present invention (such as the preferred fumed silica) may be a single white carbon black or a mixture of a plurality of white carbon blacks having different BET specific surface areas. They preferably have, for example, a BET specific surface area of 120-300 m ² /g, preferably a BET specific surface area of 150-250 m ² /g, such as a BET specific surface area of 150, 200 or 250 m ² /g. The white carbon black suitable for the present invention may be hydrophilic or hydrophobic, preferably hydrophilic.

The vinyl-containing polysiloxane used for treating white carbon may be those of component A) as described above, and the silazane compound includes, for example, hexamethyldisilazane or hexaphenylcyclotrisilazane.

The anti-settling agent can be prepared by mixing a vinyl-containing polysiloxane such as a vinyl silicone oil having a viscosity in the range of 100-500 mPa·s and a silazane compound with white carbon under stirring conditions. The mixing process can be carried out in water and can preferably be carried out under conditions of elevated temperature and/or application of an inert gas such as nitrogen.

Preferably, the content of the anti-settling agent may be in the range of 0.2-1.0%, preferably 0.3-0.8%, based on the total weight of the composition.

In addition to the above components, the potting silicone composition may further contain a polymerization inhibitor.

Commonly used inhibitors for addition-type polysiloxane systems are acetylenic alcohol inhibitors or vinyl inhibitors, or a mixture of these two inhibitors in a specific ratio.

Examples of the vinyl type inhibitor may be: tetramethyldivinylsilane, polyvinyl silicone oil, tetramethyltetravinylcyclotetrasiloxane.

Examples of acetylenic alcohol inhibitors include: 3-butyn-2-ol, 1-pentyn-3-ol, 1-hexyn-3-ol, 1-heptyn-3-ol, 5-methyl-1-hexyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynyl-1-cyclopentanol, 1-ethynyl-1-cyclohexanol, 1-ethynyl-1-cycloheptanol, 3-ethyl-1-hexyn-3-ol, 3-ethyl-1-heptyn-3-ol, 3-isobutyl-5-methyl-1-hexyn-3-ol, 3,4-dimethyl-1-hexyn-3-ol. 4-Trimethyl-1-pentyn-3-ol, 3-ethyl-5-methyl-1-heptyn-3-ol, 4-ethyl-1-octyn-3-ol, 3,7,11-trimethyl-1-dodecyne-3-ol, 1-ethynyl-1-cyclooctanol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3-methyl-1-hexyn-3-ol, 3-methyl-1-heptyn-3-ol, 3-methyl-1-octyn-3-ol, 3-methyl-1-nonyl-3-ol, 3-methyl -1-decyn-3-ol, 3-methyl-1-dodecyn-3-ol, 3-ethyl-1-pentyn-3-ol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol or 2-phenyl-3-butyn-2-ol.

The amount of components A) and B) is determined according to the molar ratio of silyl hydride groups to vinyl groups. In an advantageous embodiment, components A) and B) are used in such amounts in the organosilicon composition that the molar ratio of silyl hydride groups to vinyl groups is in the range of 0.5-5, preferably 0.8-4 and for example 1-3.

In addition, the composition of the present invention may also include other additives, including but not limited to: any one or more of color paste, leveling agent, mildewproof agent, chain extender, wetting agent, etc. The preferred chain extender may be, for example, hydrogen-terminated polydimethylsiloxane, whose hydrogen content is 0.08wt-0.2wt% and viscosity is 8-50mPa·s. The wetting agent includes but is not limited to at least one of alkoxy-terminated polydimethylsiloxane, polyether-modified silicone oil, dimethyl silicone oil, and hydroxyl-terminated silicone oil.

According to actual use requirements, the silicone composition for injection of the present invention can be formulated into multiple parts, preferably two parts.

In the case of a two-part formulation, the thermally conductive silicone composition consists of a first part and a second part, wherein the first part includes a vinyl-containing polysiloxane and the second part includes a hydrogen-containing polysiloxane. The thermally conductive filler and anti-settling agent can be distributed in the first or second part or both. In addition, other additives can also be formulated into the first or second part according to properties and needs.

In an advantageous embodiment, the first part (by weight) may include 65-96 parts of thermal conductive filler, 0.15-3.0 parts of wetting agent, 0.2-0.8 parts of anti-settling agent, 3-30 parts of vinyl-containing polysiloxane, 0.005-0.01 parts of catalyst and 0.2-0.8 parts of other auxiliary agents; the second component (by weight) may include 65-96 parts of thermal conductive filler, 0.2-0.8 parts of anti-settling agent, 2-20 parts of vinyl-containing polysiloxane, 0.5-2 parts of hydrogen-containing polysiloxane, 2-15 parts of chain extender, 0.01-0.1 parts of inhibitor and 0.2-0.8 parts of other auxiliary agents, etc. The two parts may be mixed in equal weight ratios.

The composition according to the invention can be obtained by mixing the components by mixing and stirring techniques known in the art, using heating and cooling operations as required and applying a vacuum during mixing.

The present invention will be further described below through examples.

Example

The present application is further described below in conjunction with the examples. However, the present application is not limited to the following examples. In addition, the percentage data and proportion ratios in the present application specification are all measured by weight unless otherwise clearly stated.

Ingredients

Preparation of Anti-settling Agent AS

Fill a 20L vertical kneader with nitrogen to ensure that the system is air-free. Add 30 parts by mass of terminal vinyl silicone oil (230mPa·s) and 2.5 parts by mass of deionized water. After stirring at low speed at room temperature for 5 minutes, add 10 parts by mass of hexamethyldisilazane, stir at room temperature for another 5 minutes, and add 40 parts by mass of hydrophilic fumed silica and 3.5 parts by mass of deionized water in batches. Slowly increase the temperature to control the product temperature ≤90°C. When the material temperature reaches 85°C, reflux for 1h, and then control the temperature at 150°C for heat treatment for 2h. Introduce a vacuum to 70mbar in the system, control the temperature at 150°C, and de-gas for 2h. Then cut off the vacuum valve, fill with nitrogen to de-vacuate to atmospheric pressure, and add 13.5 parts by mass of 0.5 parts by mass of vinyl-terminated silicone oil (230 mPa·s) and 0.5 parts by mass of hydroxyl-terminated silicone oil (40 mPa·s) were mixed evenly and then cooled to room temperature to obtain an anti-settling agent AS for use.

Embodiment 1:

643 parts by mass of rounded crystalline silicon powder (D50 = 20 microns, density 2.64 g/cm ³ ), 80 parts by mass of crystalline silicon powder (D50 = 8 microns, density 2.64 g/cm ³ ), 268 parts by mass of terminal vinyl silicone oil (100 mPa·s), 1.8 parts by mass of vinyl trimethoxysilane oligomer (6 mPa·s), 1.8 parts by mass of ethoxy polydimethylsiloxane (60 mPa·s) and 4.5 parts by mass of the above-prepared anti-settling agent AS were treated in situ at 80°C for 1 hour by a high-speed stirring device. Subsequently, the temperature was lowered to below 50°C by vacuum stirring, and an appropriate amount of di(1,3-divinyl-1,1,3,3-tetramethyldisiloxane) platinum catalyst (platinum metal content 8 ppm) was added and mixed in vacuum for 30 minutes, and component A-1 was obtained after vacuum removal.

652 parts by mass of rounded crystalline silica powder (D50=20 microns, density 2.64 g/cm ³ ), 82 parts by mass of crystalline silica powder (D50=8 microns, density 2.64 g/cm ³ ), 181 parts by mass of vinyl-terminated silicone oil (100 mPa·s), 1.8 parts by mass of vinyltrimethoxysilane oligomer (6 mPa·s), 1.8 parts by mass of ethoxypolydimethylsiloxane (60 mPa·s) and 4.5 parts by mass of the anti-settling agent AS prepared as above were treated in situ at 80° C. for 1 hour by a high-speed stirring device. Subsequently, the mixture was cooled to below 50°C under vacuum stirring, and 0.2 parts by mass of tetramethyltetravinylcyclotetrasiloxane, 68 parts by mass of hydrogen-terminated polydimethylsiloxane (hydrogen content of 0.2wt%, viscosity of 20mPa·s) and 9 parts by mass of hydrogen-terminated polydimethylmethylhydrogensiloxane (hydrogen content of 0.5wt%, viscosity of 10mPa·s) were added to the mixture. The mixture was mixed under vacuum for 30 minutes, and component B-1 was obtained after removing the vacuum.

Then, components A-1 and B-1 were mixed evenly in a mass ratio of 1:1, degassed and poured into a mold, and cured at room temperature for 20 hours or heated at 80°C for 30 minutes, and then the product performance was tested. The results are shown in Table 1.

Embodiment 2:

643 parts by mass of spherical alumina (D50 = 20 microns, density 3.5 g/cm ³ ), 80 parts by mass of aluminum hydroxide (D50 = 8 microns, density 2.4 g/cm ³ ), 268 parts by mass of vinyl-terminated silicone oil (100 mPa·s), 1.8 parts by mass of vinyltrimethoxysilane oligomer (6 mPa·s), and 1.5 parts by mass of ethoxylated silane were added. 1.8 parts by mass of polydimethylsiloxane (60 mPa·s) and 4.5 parts by mass of the anti-settling agent AS prepared as above were added, and the powder was treated in situ at 80°C for 1 hour by a high-speed stirring device. Then, the temperature was lowered to below 50°C by vacuum stirring, and an appropriate amount of di(1,3-divinyl-1,1,3,3-tetramethyldisiloxane) platinum catalyst (platinum metal content 8 ppm) was added and mixed in vacuum for 30 minutes. After removing the vacuum, component A-2 was obtained.

652 parts by mass of spherical alumina (D50=20 microns, density 3.5 g/cm ³ ), 82 parts by mass of aluminum hydroxide (D50=8 microns, density 2.4 g/cm ³ ), 181 parts by mass of vinyl-terminated silicone oil (100 mPa·s), 1.8 parts by mass of vinyltrimethoxysilane oligomer (6 mPa·s), 1.8 parts by mass of ethoxypolydimethylsiloxane (60 mPa·s) and 4.5 parts by mass of the anti-settling agent AS prepared as above were treated in situ at 80° C. for 1 hour by a high-speed stirring device. Then, the mixture was stirred under vacuum and cooled to below 50° C., 0.2 parts by weight of tetramethyltetravinylcyclotetrasiloxane, 68 parts by weight of hydrogen-terminated polydimethylsiloxane (hydrogen content of 0.2wt%, viscosity of 20mPa·s) and 9 parts by weight of hydrogen-terminated polydimethylmethylhydrogensiloxane (hydrogen content of 0.5wt%, viscosity of 10mPa·s) were added to the mixture, and the mixture was mixed under vacuum for 30 minutes. After the vacuum was released, component B-2 was obtained.

Then, A-2 and B-2 were mixed evenly in a mass ratio of 1:1, degassed and poured into a mold, and cured at room temperature for 20 hours or heated at 80°C for 30 minutes, and then the product performance was tested. The results are shown in Table 1.

Embodiment 3:

756 parts by mass of spherical alumina (D50 = 20 microns, density 3.5 g/cm ³ ), 95 parts by mass of spherical alumina (D50 = 8 microns, density 2.4 g/cm ³ ), 11 parts by mass of aluminum hydroxide (D50 = 1.5 microns, density 2.4 g/cm ³ ), 126 parts by mass of vinyl-terminated silicone oil (100 mPa·s), 4 parts by mass of vinyl trimethoxysilane oligomer (6 mPa·s), 4 parts by mass of ethoxy polydimethylsiloxane (60 mPa·s) and 5 parts by mass of the above-prepared anti-settling agent AS were treated in situ at 80° C. for 1 hour by a high-speed stirring device. Then, the mixture was stirred in vacuum and cooled to below 50° C., and an appropriate amount of di(1,3-divinyl-1,1,3,3-tetramethyldisiloxane) platinum catalyst was added and mixed in vacuum for 30 minutes. After the vacuum was released, component A-3 was obtained;

760 parts by mass of spherical alumina (D50 = 20 microns, density 3.5 g/cm ³ ), 95 parts by mass of spherical alumina (D50 = 8 microns, density 3.5 g/cm ³ ), 11 parts by mass of aluminum hydroxide (D50 = 1.5 microns, density 2.4 g/cm ³ ), and 68 parts by mass of vinyl-terminated silicone oil (100 mPa·s) were mixed. 4 parts by mass of vinyl trimethoxysilane oligomer (6mPa·s), 4 parts by mass of ethoxy polydimethylsiloxane (60mPa·s) and 5 parts by mass of the anti-settling agent AS prepared as above, the powder is treated in situ at 80°C for 1 hour by a high-speed stirring device. Then, the mixture is stirred in vacuum and cooled to below 50°C, 0.1 parts by mass of tetramethyl tetravinyl cyclotetrasiloxane, 53 parts by mass of hydrogen-terminated polydimethylsiloxane (hydrogen content of 0.2wt%, viscosity of 20mPa·s) and 8 parts by mass of hydrogen-terminated polydimethylmethylhydrogensiloxane (hydrogen content of 0.5wt%, viscosity of 10mPa·s) are added to the mixture, and the mixture is mixed in vacuum for 30 minutes, and the component B-3 is obtained after the vacuum is released;

Then, A-3 and B-3 were mixed evenly in a mass ratio of 1:1, degassed and poured into a mold, and cured at room temperature for 20 hours or heated at 80°C for 30 minutes, and then the product performance was tested. The results are shown in Table 1.

Comparative Example 1

Example 2 was repeated, except that an equal mass portion of γ-glycidyloxypropyltrimethoxysilane was used instead of vinyltrimethoxysilane oligomer (6 mPa·s), and other components and proportions remained unchanged. The product performance test results are shown in Table 1.

Comparative Example 2

Example 2 was repeated, except that an equal mass portion of γ-methacryloxypropyltrimethoxysilane was used instead of vinyltrimethoxysilane oligomer (6 mPa·s), and other components and proportions remained unchanged. The product performance test results are shown in Table 1.

Comparative Example 3

Example 2 was repeated, except that n-decyltrimethoxysilane was used in place of vinyltrimethoxysilane oligomer (6 mPa·s) in equal parts by mass, and other components and proportions remained unchanged. The product performance test results are shown in Table 1.

Comparative Example 4

Example 2 was repeated, except that the spherical alumina with D50=100 μm was used in equal parts to replace the spherical alumina with D50=20 μm, and the aluminum hydroxide with D50=1.5 μm was used in equal parts to replace the aluminum hydroxide with D50=8 μm. The other components and proportions remained unchanged. The product performance test results are shown in Table 1.

Comparative Example 5

Example 3 was repeated without adding the anti-settling agent AS. The product performance test results are shown in Table 1.

Comparative Example 6

Example 3 was repeated, but 1.2 parts of anti-settling agent AS was added. The product performance test results are shown in Table 1.

Comparative Example 7

Repeat Example 3, using untreated hydrophilic fumed silica The anti-settling agent AS was replaced in equal parts by mass. The product performance test results are shown in Table 1.

Performance Testing

Thixotropic index: Using a Haake rheometer C20/2° rotor product, the ratio of the viscosity at a shear rate of 10.0 s ^-1 to the viscosity at a shear rate of 1.0 s ^-1 is taken as the thixotropic index, using the ASTM D1824 standard.

Mixed viscosity: After the prepared A component and B component are uniformly mixed in a mass ratio of 1:1 and degassed, the viscosity value is recorded using a Haake rheometer C20/2° rotor at a shear rate of 10.0 s ^-1 , using the ASTM D1824 standard.

Thermal conductivity: After mixing the prepared A components and B components in a mass ratio of 1:1, degas and pour into the corresponding mold, and cure at room temperature for 20 hours or heat and cure at 80°C for 30 minutes to obtain a block with a length*width*height of 80mm*80mm*6mm. Use Hotdisk to test the thermal conductivity obtained, using ISO22007-2 standard;

Anti-sedimentation: Pour the prepared A component and B component into two 1L volumes Place the mixture in a round plastic can at room temperature (25°C) for 6 months. Test 3 samples in parallel for each group of samples to observe the oil phase precipitation. Use a tongue depressor to stir the components and observe whether there is powder compaction at the bottom. If it can be easily stirred and the oil phase precipitation is not obvious, the anti-sedimentation performance is OK; if the bottom is compacted and cannot be stirred or is difficult to stir, the anti-sedimentation performance is NG.

Claims

A thermally conductive addition-type silicone composition for potting, comprising:

A) at least one polysiloxane comprising at least two vinyl groups bonded to silicon atoms per molecule;

B) at least one hydrogen-containing polysiloxane having at least one hydrogen atom per molecule bonded to the same or different silicon atoms, provided that the component has a total of at least two hydrogen atoms bonded to the same or different silicon atoms;

C) a catalyst of at least one platinum group metal; and

D) A thermally conductive filler, the particles of which are treated with oligomers or hydrolysates of vinyltrialkoxysilane and have a D50 particle size in the range of 0.5-50 μm, preferably 1-40 μm, for example 5-30 μm.
The organosilicon composition according to claim 1, characterized in that the oligomer or hydrolyzate of vinyltrialkoxysilane has a vinyl content of 8-16 wt% and a viscosity of 5-25 mPa·s.
The organosilicon composition according to claim 1 or 2 is characterized in that the thermally conductive filler itself includes but is not limited to: spherical alumina, quasi-spherical alumina, angular alumina, aluminum hydroxide, aluminum nitride, boron nitride, silicon carbide, magnesium oxide, zinc oxide, spherical silica, rounded crystalline silicon powder, crystalline silicon powder, etc., preferably one or more of spherical alumina, quasi-spherical alumina, spherical silica, and rounded crystalline silicon powder.
The organosilicon composition according to any one of claims 1 to 3, characterized in that the total content of the thermally conductive filler is in the range of 65-96 wt%, preferably 70-90 wt%, based on the total weight of the composition.
The organic silicon composition according to any one of claims 1 to 4, characterized in that, based on the total volume of the thermally conductive filler, the thermally conductive filler with a particle size range of D50 and above 15 μm accounts for a volume The volume percentage is 80-95%, the volume percentage of thermal conductive fillers with a D50 particle size range of 6 microns to less than 15 microns is 5-20%, and the volume percentage of thermal conductive fillers with a D50 particle size range of less than 6 microns is 0-2%.
The organosilicon composition according to any one of claims 1 to 5, characterized in that the amount of the oligomer or hydrolyzate of vinyltrialkoxysilane is 0.15%-1.5%, preferably 0.20%-1.0%, based on the weight of the thermally conductive filler.
The silicone composition according to any one of claims 1 to 6, characterized in that the silicone composition further comprises an anti-settling agent component E), which comprises white carbon treated with at least one polysiloxane and silazane compound containing at least two vinyl groups bonded to silicon atoms per molecule.
The organosilicon composition according to claim 7, characterized in that the silazane compound is hexamethyldisilazane or hexaphenylcyclotrisilazane, and/or the polysiloxane is a vinyl silicone oil with a viscosity in the range of 100-500 mPa·s.
The organosilicon composition according to claim 7, characterized in that the content of the anti-settling agent is in the range of 0.2-1.0%, preferably 0.3-0.8%, based on the total weight of the composition.
An anti-settling agent comprises white carbon treated with at least one polysiloxane and silazane compound containing at least two vinyl groups bonded to silicon atoms per molecule.
Use of a thermally conductive filler and an anti-settling agent in a thermally conductive silicone composition for potting, for improving the thermal conductivity, thixotropy, flowability and/or storage stability of the potting compound, wherein the particles of the thermally conductive filler are treated with an oligomer or hydrolyzate of vinyltrialkoxysilane and have a D50 particle size range of 0.5-50 microns, preferably 1-40 microns, for example 5-30 microns; and the anti-settling agent comprises white carbon black treated with at least one polysiloxane and silazane compound containing at least two vinyl groups bonded to silicon atoms per molecule.
A method for preparing the silicone composition according to any one of claims 1 to 9, comprising the step of intimately mixing components A) to D) and optionally component E).
A product comprising a potting compound obtained from the organosilicon composition according to any one of claims 1 to 9, wherein the product is a thermal management component or electronic component in the field of wind power generation motor system, photovoltaic energy storage system, new energy vehicle battery module, and on-board charger, or a part thereof.