Curable thermally conductive composition

Abstract

A curable thermally conductive composition containing: (A) from 5% to 11% by weight of an alkenyl-functional polyorganosiloxane having a viscosity in the range of from 25 mPa * sec to 500 mPa * sec as determined by ASTM D445-21 using a glass capillary cannon-Vinck viscometer at 25 degrees Celsius, the alkenyl-functional polyorganosiloxane having a viscosity in the range of from 25 mPa * sec to 500 mPa * sec, as determined by ASTM D445-21 using a glass capillary cannon-Vinck viscometer, wherein the alkenyl-functional polyorganosiloxane has the chemical structure (I); (B) a silyl-hydride functional polysiloxane crosslinker containing at least two silyl-hydride groups per molecule, and present in a concentration that provides a molar ratio of silicon-bonded hydrogen atoms to alkenyl groups of from 0.3: 1 to 1.5: 1 of the composition; (C) 85% to 92% by weight of a thermally conductive filler containing (C1) 40% to 55% by weight of aluminum hydroxide particles having a D50 in the range of 70 [mu] m to 150 [mu] m, (C2) 15% to 30% by weight of aluminum hydroxide particles having a D50 in the range of 1 [mu] m to 30 [mu] m, and (C3) 10% to 25% by weight of aluminum oxide particles having a D50 in the range of 0.2 [mu] m to 4 [mu] m; and (D) a filler treatment agent selected from the group consisting of a trialkoxysilyl diorganopolysiloxane, an alkyltrialkoxysilane, or a mixture thereof; wherein the trialkoxysilyl diorganopolysiloxane has an average chemical structure (IV); wherein the weight percentages are relative to the weight of the curable thermally conductive composition. A method for using such a curable thermally conductive composition and an article containing such a curable thermally conductive composition are disclosed.

Description

Technical Field

[0001] The present invention relates to a curable thermally conductive composition containing a thermally conductive filler comprising a novel combination of at least three different thermally conductive particles. Background Technology

[0002] The industrial drive for smaller, more powerful electronic devices has increased the demand for thermally conductive compositions that can dissipate the heat generated in such devices. Without effective dissipation, the heat generated by the high power in smaller devices can damage them. In particular, advanced integrated circuit devices such as high-power-density inverters and lithium-ion batteries in electric vehicles generate significant amounts of heat due to accelerated operating speeds. Thermally conductive interface materials are commonly used for heat removal.

[0003] As the EV industry trends towards reducing overall vehicle weight for long-distance travel, minimizing the weight of the inverter and battery pack is crucial. Thermally conductive compositions based on silicone liquids filled with large amounts of alumina powder and zinc oxide are widely used as thermal interface (TIM) materials. However, due to the relatively high density of alumina and zinc oxide, these TIM materials are often too heavy for electric vehicle applications requiring lightweight TIM materials with a low density of less than 2.2 g / cm³. Aluminum hydroxide (ATH) has a much lower density than alumina and zinc oxide, which can contribute to weight reduction in electric vehicles. However, its lower thermal conductivity necessitates a higher filler loading to achieve a thermal conductivity of at least 2.4 W / m*Kelvin for the composition. Increasing the filler loading has limitations in improving thermal conductivity, as thermal conductivity also depends on various parameters such as the type, filler content, particle shape, and particle size of the different thermally conductive fillers incorporated. One challenge in thermally conductive interface materials is providing a combination of high thermal conductivity and excellent dispersibility (i.e., an extrusion rate of at least 240 g / min) to ensure effective distribution during manufacturing and allow for precise application of the thermally conductive material to small parts. In particular, due to the irregular shape and polar surface groups of ATH filler, it is more difficult to disperse ATH in silicone liquids compared to alumina. Therefore, simply increasing the amount of ATH filler to achieve the desired thermal conductivity often reduces the extrusion rate of the composition, which may even become a powdery paste. Thus, simultaneously satisfying all three performance parameters mentioned above is particularly challenging.

[0004] It is still necessary to identify thermally conductive compositions that can simultaneously achieve the aforementioned density, extrusion rate, and thermal conductivity properties. Summary of the Invention

[0005] This invention provides a curable thermally conductive composition (also referred to as a "curable polysiloxane composition") comprising a novel combination of at least three thermally conductive fillers comprising large aluminum hydroxide particles, small aluminum hydroxide particles, and alumina particles of a specific particle size and concentration. Surprisingly, such curable thermally conductive compositions exhibit extrusion rates ("ER") of 240 g / min or higher, as measured using the extrusion rate test defined herein, and cure to a value of less than 2.2 g / cm³ according to ASTM D792. 3 Materials with a density of at least 2.4 W / m Kelvin (W / m K) as measured using a hot plate according to ISO 22007-2. Such curable thermally conductive compositions are particularly suitable for use as thermal interface materials.

[0006] In a first aspect, the present invention is a curable thermally conductive composition comprising:

[0007] (A) 5% to 11% by weight of an alkenyl-functionalized polysiloxane having a viscosity in the range of 25 mPa·s to 500 mPa·s as determined by a glass capillary Cannon-Fenske viscometer at 25 degrees Celsius according to ASTM D445-21, wherein the alkenyl-functionalized polysiloxane has an average chemical structure (I):

[0008]

[0009] Where R a Each time it appears, it is independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, and each time it appears, it is independently an alkenyl group, with subscript a ≥ 0, subscript b > 0, subscript c being 0 or 1, subscript d being 0 or 1, (a+b) being 20 to 200, and (a+c+d) ≥ 2;

[0010] (B) A silyl-hydride functional polysiloxane crosslinking agent, wherein each molecule of the silyl-hydride functional polysiloxane crosslinking agent contains at least two silyl-hydride groups and is present at a concentration of 0.3:1 to 1.5:1 molar ratio of silicon-bonded hydrogen atoms to alkenyl groups, providing the composition.

[0011] (C) 85% to 92% by weight of thermally conductive filler, wherein the thermally conductive filler comprises:

[0012] (C1) 40% to 55% by weight of aluminum hydroxide particles with D50 in the range of 70 to 150 micrometers.

[0013] (C2) 15% to 30% by weight of aluminum hydroxide particles with D50 in the range of 1 micrometer to 30 micrometers, and

[0014] (C3) 10 wt% to 25 wt% of alumina particles with D50 in the range of 0.2 micrometers to 4 micrometers, and

[0015] (D) A filler treatment agent selected from trialkoxysilyl diorganopolysiloxanes, alkyltrialkoxysilanes, or mixtures thereof; wherein the trialkoxysilyl diorganopolysiloxane has an average chemical structure (IV):

[0016]

[0017] Where R c R d and R e Each occurrence is independently an alkyl group having 1 to 20 carbon atoms, the subscript g has a value of 20 to 130, and Y is O or [OSiR]. d 2](CH2) n The subscript n has values ​​from 3 to 20;

[0018] The weight percentages are relative to the weight of the curable thermally conductive composition.

[0019] In a second aspect, the present invention is a method for using the curable thermally conductive composition of the first aspect. The method includes: (i) providing the curable thermally conductive composition of the first aspect, (ii) applying the curable thermally conductive composition to an electronic component, and (iii) curing the curable thermally conductive composition.

[0020] In a third aspect, the present invention is an article comprising a curable thermally conductive composition of the first aspect and an electronic component having the thermally conductive composition applied thereto, wherein the curable thermally conductive composition is in a cured form. Detailed Implementation

[0021] When a test method number is not used to indicate a date, the test method refers to the most recent test method as of the priority date of this document. References to test methods include references to both the testing association and the test method number. The following test method abbreviations and identifiers apply to this document: ASTM refers to ASTM International Methods, and ISO refers to the International Organization for Standardization.

[0022] Products identified by their trade names refer to compositions available under those trade names as of the priority date of this document.

[0023] "And / or" means "and, or as an alternative." Unless otherwise specified, all ranges include the endpoints. Unless otherwise stated, all weight percentage (wt%) values ​​are relative to the weight of the composition.

[0024] "Spherical" shaped particles are defined as particles with an aspect ratio of 1.0 + / - 0.2. The aspect ratio of a particle is determined by imaging with a scanning electron microscope (SEM) and by obtaining the average ratio of the longest dimension (major axis) and the shortest dimension (minor axis) of at least ten particles.

[0025] "Spherical" refers to a shape in which the grain has small edges and the entire grain is a single grain with few crystal edges. Spherical grains have an aspect ratio other than 1.0 + / - 0.2 and can be elliptical, etc., but do not include spheres.

[0026] A "polyhedron" is a shape surrounded by multiple planes, such as a hexahedron, octahedron, and dodecahedron. Each plane does not necessarily have the same shape.

[0027] "Irregular" shaped particles refer to particles that do not have a fixed shape (such as "spherical", "quasi-circular", or "polyhedral"). Irregular particles have an aspect ratio different from 1.0 + / - 0.2 and are observed to have distinct sharp, non-uniform, and differently shaped edges when viewed through SEM imaging.

[0028] The particle size of the thermally conductive filler (which can be used interchangeably with "average particle size" and "D50") refers to the volume-weighted median of the particle diameter distribution (D50). D50 can be obtained using Mastersizer from Malvern Instruments. ™ (Malvin Instruments trademark) 2000 Laser Diffraction Particle Size Analyzer Measurement.

[0029] Unless otherwise specified, the “viscosity” of polysiloxanes is determined according to ASTM D445-21 using a glass capillary Canon-Fensk viscometer at 25 degrees Celsius (°C).

[0030] The curable thermally conductive composition of the present invention can undergo a crosslinking reaction (“curing”). In the composition of the present invention, the crosslinking reaction is a hydrosilylation reaction between an alkenyl-functionalized polysiloxane component and a silyl-hydride (SiH)-functionalized polysiloxane crosslinking agent.

[0031] The curable thermally conductive composition of the present invention comprises an alkenyl-functionalized polyorganosiloxane (component (A)) having two or more alkenyl groups per molecule. "Alkenyl" means a branched or unbranched monovalent hydrocarbon group having one or more carbon-carbon double bonds. The alkenyl group can be a terminal group, a side group, or a combination of both. A "terminal group" is located on a terminal siloxane group of the molecule. A "terminal" siloxane group is attached to only one other siloxane group. A "side group" is located on an internal siloxane group of the molecule that is attached to at least two other siloxane groups. A "siloxane group" is a group containing SiO2 bound to another Si through oxygen via SiO2. Ideally, each molecule of the alkenyl-functionalized polyorganosiloxane has an average of one or more terminal alkenyl groups. The alkenyl-functionalized polyorganosiloxane has a viscosity in the range of 25 mPa·s to 500 mPa·s. If the viscosity is too low, separation tends to occur between the polysiloxane and the filler, thereby impairing the physical properties of the composition. If the viscosity is too high, it may be difficult to incorporate thermally conductive fillers into the composition that provide sufficient high thermal conductivity and excellent dispersibility. Alkenyl-functionalized polysiloxanes can be combinations of two or more alkenyl-functionalized polysiloxanes selected from those differing in molecular weight, structure, siloxane unit, and sequence. When an alkenyl-functionalized polysiloxane is a combination of more than one alkenyl-functionalized polysiloxane, the viscosity is the combined viscosity of the alkenyl-functionalized polysiloxanes. As determined by ASTM D445-21 using a glass capillary Canon-Fensk viscometer at 25°C, the viscosity of alkenyl-functionalized polysiloxanes ranges from 25 mPa*s to 500 mPa*s, and can be 25 mPa*s or greater, 30 mPa*s or greater, 40 mPa*s or greater, 50 mPa*s or greater, 60 mPa*s or greater, 70 mPa*s or greater, 75 mPa*s or greater, 78 mPa*s or greater, even 80 mPa*s or greater, and simultaneously 500 mPa*s or less, and can be 400 mPa*s or less, 300 mPa*s or less, 200 mPa*s or less, 150 mPa*s or less, 100 mPa*s or less, 90 mPa*s or less, even 80 mPa*s or less, ideally 30 mPa*s to 100 mPa*s.

[0032] The alkenyl-functionalized polyorganosiloxane (A) that can be used in this invention may have an average chemical structure (I):

[0033]

[0034] Where R aR' is independently an alkyl group with 1 to 6 carbon atoms or an aryl group with 6 to 10 carbon atoms each time it appears, and R' is independently an alkenyl group each time it appears, with subscript a being zero or greater (≥0), subscript b being greater than 0 (>0), subscript c being 0 or 1, subscript d being 0 or 1, (a+c+d) being 2 or greater (≥2), and (a+b) being 20 to 200.

[0035] Suitable for R a The alkyl group may include, for example, methyl, ethyl, propyl (e.g., isopropyl and / or n-propyl), butyl (e.g., isobutyl, n-butyl, tert-butyl and / or sec-butyl), pentyl (e.g., isopentyl, neopentyl and / or tert-pentyl), hexyl, and branched saturated hydrocarbon groups with 6 carbon atoms. Suitable for R a Examples of aryl groups are phenyl, tolyl, xylyl, naphthyl, benzyl, and dimethylphenyl. Each R a They can be the same or different. Each R a It can be an alkyl group. Ideally, each R... a Independently methyl, ethyl, or propyl, and more ideally, each R a It is a methyl group.

[0036] The alkenyl group used for R' typically has 2 to 8 carbon atoms, 2 to 6 carbon atoms, or 2 to 4 carbon atoms. Suitable alkenyl groups may include vinyl, allyl, butenyl, and hexenyl. Particularly suitable alkenyl groups for R' are vinyl, allyl, butenyl, and hexenyl. Each R' may be the same or different. Ideally, each R' is selected from vinyl or hexenyl. More ideally, each R' is vinyl.

[0037] The subscript 'a' indicates the number of molecules per molecule (R'R) a The subscript b indicates the average number of (R) groups per molecule. a The average number of 2SiO) groups. Ideally, the amount (a+b) is 25 to 200, and can be 25 or greater, 30 or greater, 40 or greater, 50 or greater, 60 or greater, 70 or greater, 80 or greater, 90 or greater, 100 or greater, 120 or greater, 140 or greater, 160 or greater, even 180 or greater, and is usually 200 or less, and can be 180 or less, 160 or less, 140 or less, 120 or less, 100 or less, 80 or less, 60 or less, even 40 or less, ideally 25 to 60. Ideally, the amount (a+c+d) is 2 or greater, even 3 or greater, and is usually 30 or less, and can be 20 or less, 10 or less, or even 3 or less. More ideally, the subscript a is 0, the subscript c is 1, the subscript d is 1, and each R a It is a methyl group.

[0038] Examples of suitable alkenyl-functionalized polyorganosiloxanes include i) vinyl dimethylsiloxane-terminated polydimethylsiloxane, ii) dimethyl vinyl siloxane-terminated poly(dimethylsiloxane / methyl vinylsiloxane), iii) dimethyl vinyl siloxane-terminated polymethyl vinylsiloxane, iv) trimethyl siloxane-terminated poly(dimethylsiloxane / methyl vinylsiloxane), v) trimethyl siloxane-terminated polymethyl vinylsiloxane, vi) dimethyl vinyl siloxane-terminated poly(dimethylsiloxane / methyl vinylsiloxane), or mixtures thereof.

[0039] Ideally, the alkenyl-functionalized polyorganosiloxane comprises, or consists of, any combination of, one or more of vinyl dimethylsiloxy-terminated polydimethylsiloxanes (A1) having an average chemical structure (II):

[0040]

[0041] Where Vi represents alkenyl, and the subscript b is the average number of ((CH3)2SiO) groups per molecule and has a value from 20 to 200, and can be 20 or greater, 25 or greater, 30 or greater, 35 or greater, 40 or greater, 45 or greater, 50 or greater, 55 or greater, or even 58 or greater, and usually has a value of 200 or less, and can be 180 or less, 160 or less, 140 or less, 120 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, or even 58 or less. For example, alkenyl-functionalized polyorganosiloxanes can be vinyl dimethylsiloxy-terminated polydimethylsiloxanes with a viscosity of 78 mPa*s and containing 1.25% by weight of vinyl groups relative to the molecular weight, such as those available from Gelest under the name SMS-V21.

[0042] Based on the weight of the curable thermally conductive composition, the concentration of component (A) alkenyl-functionalized polyorganosiloxane can be from 5.0 wt% to 11.0 wt%, and can be 5.0 wt% or greater, 5.5 wt% or greater, 6.0 wt% or greater, 6.5 wt% or greater, 7.0 wt% or greater, 7.5 wt% or greater, 8.0 wt% or greater, or even 8.5 wt% or greater, and is typically 11.0 wt% or less, and can be 10.5 wt% or less, 10.0 wt% or less, 9.5 wt% or less, 9.0 wt% or less, or even 8.8 wt% or less, ideally 8.0 wt% to 9.0 wt%.

[0043] The curable thermally conductive composition of the present invention comprises a silyl-hydride (SiH) functionalized polysiloxane crosslinker (component (B), also referred to as "SiH crosslinker"). The SiH functionalized polysiloxane crosslinker contains at least two silyl-hydride groups (i.e., at least two silicon-bonded hydrogen atoms per molecule), or even three or more silyl-hydride groups. The SiH groups can be side groups, end groups, or a combination of both. The SiH functionalized polysiloxane crosslinker may have an average chemical structure (III):

[0044]

[0045] Where R bb Each time it appears, it is independently selected from alkyl groups having 1 to 6 carbon atoms and phenyl groups; each time the subscripts h and h' are independently selected from values ​​in the range of 0 to 3, provided that the combination of e, h and h' is at least 2; the subscript e is from 0 to 30; and the subscript f is from 5 to 200.

[0046] R bb The group can have one or more carbons, two or more carbons, three or more carbons, four or more carbons, or even five or more carbons, and simultaneously six or fewer carbons, five or fewer carbons, four or fewer carbons, three or fewer carbons, or even two or fewer carbons. Ideally, R bb The group is independently selected from methyl and phenyl each time it appears. H is a hydrogen atom.

[0047] The subscripts h and h' refer to the average number of terminal hydrogen atoms at any given end, and each is independently selected from a value between 0 and 3 each time it appears, provided that the combination of e, h, and h' is at least 2. Ideally, h and h' are independently 0 or greater, 1 or greater, or even 2 or greater each time they appear, while simultaneously being 3 or less, 2 or less, or even 1 or less. More ideally, h and h' have the same value. Most ideally, both h and h' are zero. The subscript e represents the number of hydrogen atoms per molecule (HR). bb The average number of SiO groups. If both h and h' are zero, then e is in the range of 2 to 30. If neither h nor h' is zero, then the subscript e can be 0 to 30, provided that the combination of e, h, and h' is 2 or greater. Ideally, the subscript e is 1 or greater, and can be 2 or greater, and can be 3 or greater, 4 or greater, 5 or greater, 6 or greater, 7 or greater, 8 or greater, or even 9 or greater, and is usually 30 or less, and can be 25 or less, 20 or less, 15 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or even 2 or less. Ideally, e is in the range of 2 to 8. The subscript f is the number of (R) groups per molecule. bbThe average number of 2SiO groups. Generally, the subscript f is 5 or greater, 10 or greater, 14 or greater, 20 or greater, 25 or greater, 30 or greater, 40 or greater, 50 or greater, and can be 75 or greater, 100 or greater, 125 or greater, 150 or greater, 175 or greater, or even 190 or greater, and is usually 200 or less, 175 or less, 150 or less, 125 or less, 100 or less, 75 or less, 50 or less, 40 or less, 30 or less, 25 or less, 22 or less, or even 20 or less. Ideally, f is in the range of 5 to 30.

[0048] Ideally, SiH-functionalized polysiloxane crosslinking agents have structures of formula (III-a), (III-b), or combinations thereof:

[0049]

[0050] The subscript x ranges from 10 to 100, ideally from 10 to 30; the subscript y ranges from 2 to 30, ideally from 2 to 8; and the subscript z ranges from 3 to 100, ideally from 5 to 30.

[0051] Component (B) may be a combination of SiH crosslinking agents of formula (III-a) and SiH crosslinking agents of formula (III-b). Ideally, component (B) is one or more SiH crosslinking agents of formula (III-b).

[0052] SiH-functionalized polysiloxane crosslinking agents may have a silicon-bonded hydrogen atom (“SiH”) content (i.e., SiH content) of 0.01 wt% to 1.0 wt%, and may be 0.01 wt% or greater, 0.05 wt% or greater, 0.08 wt% or greater, 0.1 wt% or greater, 0.11 wt% or greater, 0.12 wt% or greater, or even 0.14 wt% or greater, and simultaneously typically 1.0 wt% or less, and may be 0.9 wt% or less, 0.8 wt% or less, 0.7 wt% or less, 0.6 wt% or less, 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, or even 0.2 wt% or less, ideally 0.08 wt% to 0.5 wt%. SiH content refers to the weight percentage of silicon-bonded hydrogen atoms relative to the molecular weight of the SiH-functionalized polysiloxane crosslinking agent, and can be determined using Fourier transform infrared (FTIR) spectroscopy.

[0053] Suitable SiH-functionalized polysiloxane crosslinking agents may include, for example, trimethylsiloxy-terminated poly(dimethylsiloxane / methylhydrosiloxane), trimethylsiloxy-terminated polymethylhydrosiloxane, hydrogen-terminated polydimethylsiloxane, hydrogen-terminated poly(dimethylsiloxane / methylhydrosiloxane), or mixtures thereof. The crosslinking agent may be a combination of two or more crosslinking agents that differ in one or more characteristics selected from molecular weight, structure, siloxane unit, and sequence, such as mixtures of trimethyl-terminated dimethyl-co-hydromethyl polysiloxane and hydride-terminated polydimethylsiloxane. Specific examples of SiH crosslinking agents include those having an average chemical structure of: Me3SiO(Me2SiO)7(MeHSiO)3SiMe3, Me3SiO(Me2SiO). 108 (MeHSiO) 10 SiMe3, Me3SiO (Me2SiO) 22 (MeHSiO)2SiMe3, Me3SiO-[MeHSiO] 3.7 [Me2SiO] 8.7 -SiMe3, HMe2SiO (Me2SiO) 25 (MeHSiO)1SiMe2H or H(Me)2SiO-[Me2SiO) 14 -SiMe2H, where Me represents methyl; or mixtures thereof. Suitable commercially available SiH crosslinking agents include those available from Gallester under the names HMS-071, HMS-501, and DMS-H11. Ideally, the SiH crosslinking agent can be a polymer or a combination of two polymers selected from the group consisting of: (Bi) trimethyl-terminated dimethyl-co-hydromethyl polysiloxane having a viscosity of 20 mPa*s to 25 mPa*s and a SiH content of 0.10% by weight; and (B-ii) trimethyl-terminated dimethyl-co-hydromethyl polysiloxane having a viscosity in the range of 7 mPa*s to 15 mPa*s and a SiH content of 0.356% by weight.

[0054] The concentration of the SiH-functionalized polysiloxane crosslinker is sufficient to provide a molar ratio (also referred to as the "SiH / Vi ratio") of silicon-bonded hydrogen atoms from the crosslinker to alkenyl groups (ideally, vinyl groups) in a curable thermally conductive composition ranging from 0.3:1 to 1.5:1, and this molar ratio can be 0.3:1 or higher, 0.4:1 or higher, 0.45:1 or higher, 0.5:1 or higher, or even 0.8:1 or higher, and simultaneously 1.5:1 or less, and can be 1.4:1 or less, 1.3:1 or less, 1.2:1 or less, 1.1:1 or less, 1.0:1 or less, 0.9:1 or less, 0.8:1 or less, 0.7:1 or less, 0.6:1 or less, or even 0.5:1 or less. Ideally, the SiH / Vi ratio is from 0.4:1 to 1.0:1. The SiH / Vi ratio determines the degree of crosslinking that occurs when the curable thermally conductive composition cures. If the SiH / Vi ratio is too low, the composition tends not to cure sufficiently. If the SiH / Vi ratio is too high, the composition cures so much that it becomes brittle and suffers from surface cracking.

[0055] The curable thermally conductive composition of the present invention comprises a thermally conductive filler (component (C)). Component (C) comprises at least three different thermally conductive fillers, namely combinations of (C1), (C2) and (C3) described below, and may be composed of at least three different thermally conductive fillers.

[0056] The first thermally conductive filler (C1) is aluminum hydroxide particles with a D50 particle size of 70µm to 150µm, and may have a D50 of 70µm or larger, greater than 70µm, 75µm or larger, 80µm or larger, 85µm or larger, 88µm or larger, 90µm or larger, greater than 90µm, 95µm or larger, 100µm or larger, greater than 100µm, 105µm or larger, or even 110µm or larger, and simultaneously have a D50 particle size of 150µm or smaller, and may be 145µm or smaller, 140µm or smaller, 135µm or smaller, 130µm or smaller, 125µm or smaller, 120µm or smaller, 110µm or smaller, 100µm or smaller, 95µm or smaller, 90µm or smaller, or even less than 90µm. Ideally, the first thermally conductive filler (C1) has a D50 of 75µm to 150µm, more ideally 88µm to 140µm, and even more ideally greater than 100µm to 130µm or greater than 100µm to 125µm. Alternatively, the first thermally conductive filler (C1) may have a D50 in the range of 70µm to 100µm, 70µm to 90µm, or even 70µm to less than 90µm, and preferably in the range of 70µm to 88µm. The aluminum hydroxide particles used as the first thermally conductive filler (C1) may be irregularly shaped particles. The first thermally conductive filler may be a combination of two or more ATH fillers with different particle sizes, provided that each filler has a D50 within the range defined above (e.g., within 70µm to 150µm). Based on the weight of the curable thermally conductive composition, the concentration of aluminum hydroxide particles (C1) is from 40 wt% to 55 wt%, and can be 40 wt% or more, greater than 40 wt%, 40.5 wt% or more, 41 wt% or more, 41.5 wt% or more, or even 42 wt% or more, and simultaneously 55 wt% or less, or 54 wt%, 53 wt% or less, 52 wt% or less, 51 wt% or less, 50 wt% or less, or even 49.5 wt% or less; ideally, 42 wt% to 52 wt% or 45 wt% to 55 wt%. Ideally, based on the weight of the curable thermally conductive composition, the first thermally conductive filler (C1) is 45 wt% to 55 wt% of aluminum hydroxide particles with a D50 greater than 100 µm to 125 µm.

[0057] The second thermally conductive filler (C2) is aluminum hydroxide particles with a D50 particle size of 1µm to 30µm, and can have a D50 of 1µm or larger, 2µm or larger, 5µm or larger, 8µm or larger, 9µm or larger, 10µm or larger, or even 12µm or larger, while simultaneously having a D50 particle size of 30µm or smaller, and can have a D50 of 28µm or smaller, 25µm or smaller, less than 25µm, 22µm or smaller, 20µm or smaller, less than 20µm, 18µm or smaller, 15µm or smaller, or even 12µm or smaller. Ideally, the (C2) aluminum hydroxide particles have a D50 particle size of 1µm to 20µm, and more ideally 9µm to 15µm. Based on the weight of the curable thermally conductive composition, the concentration of the second thermally conductive filler (C2) is from 15 wt% to 30 wt%, and can be 15 wt% or more, 16 wt% or more, 17 wt% or more, 18 wt% or more, 19 wt% or more, 20 wt% or more, or even 21 wt% or more, and simultaneously 30 wt% or less, and can be 29.5 wt% or less, 29 wt% or less, 28.5 wt% or less, 28 wt% or less, 25 wt% or less, or even 23 wt% or less, ideally 18 wt% to 30 wt%, more ideally 20 wt% to 30 wt%, or even more ideally 20 wt% to 28 wt%. The aluminum hydroxide particles used for the second thermally conductive filler (C2) can be irregularly shaped particles. The second thermally conductive filler can be a combination of two or more ATH fillers with different particle sizes, provided that each filler has a D50 within the range described above (e.g., within 1 µm to 30 µm). The second thermally conductive filler (C2) may consist of or contain aluminum hydroxide particles, which, based on the weight of the curable thermally conductive composition, have a D50 in the range of 1µm to 20µm, preferably in the range of 9µm to 15µm, and typically at a concentration of 20% by weight or greater.

[0058] The third thermally conductive filler (C3) is alumina particles with a D50 particle size of 0.2µm to 4µm, and may have a D50 of 0.2µm or larger, 0.3µm or larger, 0.5µm or larger, 0.7µm or larger, 0.8µm or larger, or even 0.9µm or larger, while simultaneously having a D50 particle size of 4µm or smaller, and may have a D50 of 3.5µm or smaller, 3µm or smaller, 2.5µm or smaller, 2µm or smaller, 1.5µm or smaller, 1µm or smaller, less than 1µm, 0.8µm or smaller, 0.6µm or smaller, or even 0.5µm or smaller. Ideally, the third thermally conductive filler (C3) has a D50 in the range of 0.2µm to 2µm, more ideally 0.3µm to 2µm, and even more ideally 0.4µm to less than 1µm. Based on the weight of the curable thermally conductive composition, the concentration of the third thermally conductive filler (C3) is from 10% to 25% by weight, and can be 10% or more by weight, 11% or more by weight, 12% or more by weight, 14% or more by weight, 15% or more by weight, or even 16% or more by weight, while simultaneously being 25% or less by weight, and can be 24% or less by weight, 23% or less by weight, 22% or less by weight, 20% or less by weight, 18% or less by weight, 17% or less by weight, or even 15% or less by weight, ideally 10% to 20% by weight. The third thermally conductive filler (C3) may comprise spherical, near-circular, irregular, or polyhedral particles, or combinations of two or more alumina fillers of different shapes or particle sizes, provided that each filler has a D50 within the range described above (e.g., within the range of 0.2µm to 4µm). Ideally, the third thermally conductive filler (C3) is an irregular or spherical alumina particle, more preferably with a D50 of 0.4µm to less than 1µm.

[0059] The thermally conductive filler (C) may or may not contain a fourth thermally conductive filler (C4) other than (C1) to (C3) described above. The fourth thermally conductive filler (C4) may be selected from boron nitride with a (C4-i) D50 particle size in the range of 20 µm to 130 µm, alumina with a (C4-ii) D50 greater than 4 µm, or mixtures thereof. The alumina that can be used as the fourth thermally conductive filler (C4) may have a D50 of 30 µm or larger, 90 µm or larger, or even 100 µm or larger. The fourth thermally conductive filler particles may have any shape, such as spherical, irregular, near-circular, or polyhedral. Based on the weight of the curable thermally conductive composition, the concentration of (C4-i) boron nitride may range from zero wt% to 15 wt%, and may be less than 10 wt%, less than 5 wt%, less than 1 wt%, or even zero wt%. Based on the weight of the curable thermally conductive composition, the concentration of (C4-ii) alumina can range from zero wt% to less than 10 wt%, and can be less than 5 wt%, less than 1 wt%, or even zero wt%.

[0060] Ideally, the thermally conductive filler (C) comprises or consists of the following substances: (C1) 45% to 55% by weight of aluminum hydroxide particles with a D50 greater than 100µm to 130µm; (C2) 18% to 30% by weight of aluminum hydroxide particles with a D50 of 1µm to 20µm; and (C3) 15% to 25% by weight of alumina particles with a D50 of 0.2µm to 2µm. Alternatively, the thermally conductive filler (C) comprises or consists of the following substances: (C1) 45% to 55% by weight of aluminum hydroxide particles with a D50 of 70µm to 100µm or 70µm to 90µm; (C2) 15% to 25% by weight of aluminum hydroxide particles with a D50 of 1µm to 15µm; and (C3) 10% to 25% by weight of alumina particles with a D50 of 0.2µm to less than 1µm.

[0061] Based on the weight of the curable thermally conductive composition, the total concentration of the thermally conductive filler (C) can be from 85% to 92% by weight, and can be 85% or more, 86% or more, 87% or more, or even 87.5% or more, while simultaneously being 92% or less, and can be 90% or less, 89% or less, or even 88% or less.

[0062] The curable thermally conductive composition of the present invention comprises a filler treatment agent (component (D)). Component (D) may be selected from trialkoxysilyl diorganopolysiloxane, alkyltrialkoxysilane, or mixtures thereof. Component (D) is one filler treatment agent or a combination of more than one filler treatment agent. The filler treatment agent component (D) may comprise or consist of: one trialkoxysilyl diorganopolysiloxane (D-1) having an average chemical structure (IV) or any combination of more than one trialkoxysilyl diorganopolysiloxane (D-1) having an average chemical structure (IV):

[0063]

[0064] Where R c R d and R eEach occurrence independently represents an alkyl group having 1 to 20 carbon atoms, for example, having 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or even 8 or more carbon atoms, and typically having 20 or fewer, 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, 3 or fewer, or even 2 or fewer carbon atoms; the subscript g typically has a value from 20 to 130, and can be 20 or greater, 25 Or greater, 30 or greater, 40 or greater, 50 or greater, 60 or greater, 70 or greater, 80 or greater, 90 or greater, 100 or greater or even 110 or greater, and usually has a value of 150 or less, and can be 130 or less, 125 or less, 120 or less, 110 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 40 or less, or even 30 or less; and Y is 0 or [OSiR d 2](CH2) n The subscript n has values ​​from 3 to 20, 3 to 10, or 3 to 6; ideally, Y is [OSi(CH3)2](CH2). n Ideally, when Y is 0, the subscript g has a value in the range of 20 to 120 or 20 to 115. Alternatively, when Y is [OSiR... d 2](CH2) n At that time, the subscript g has a value in the range of 20 to 50. Each R c R d and R e They can be the same or different. R c R d and R e Examples of suitable alkyl groups are methyl, ethyl, propyl (e.g., isopropyl and / or n-propyl), butyl (e.g., isobutyl, n-butyl, tert-butyl and / or sec-butyl), pentyl (e.g., isopentyl, neopentyl and / or tert-pentyl), hexyl, and branched saturated hydrocarbon groups with 6 carbon atoms. c R d and R e Each can be independently methyl, ethyl, or propyl. Ideally, each R... c R d and R e It is methyl. Alternatively, R c Both of them, R d and R e Both are methyl groups, and one R c It is an alkyl group having 3 to 20 carbon atoms, such as octyl, where Y is [OSi(CH3)2](CH2). nThe subscript n is in the range of 3 to 20 (e.g., 3 to 6). Particularly desirable are trialkoxysilyl diorganopolysiloxanes that are monotrimethoxysiloxy and trimethylsiloxy-terminated polydimethylsiloxanes, such as those having the average chemical formula C8H. 17 [(CH3)2SiO] 26 [Si(CH3)2]C6H 12 Those of Si(OCH3)3. Suitable trialkoxysilyl diorganopolysiloxanes can be synthesized according to the teachings in US11098196B2.

[0065] Component (D) of the filler treatment agent may contain or not contain one alkyltrialkoxysilane (D-2) or a combination of more than one alkyltrialkoxysilane (D-2). Suitable alkyltrialkoxysilanes include those having the chemical formula (V):

[0066]

[0067] Where R f Each time it appears, it is independently an alkyl group having 6 to 20 carbon atoms, and may have 6 or more, 7 or more, 8 or more, 9 or more, or even 10 or more carbon atoms, and simultaneously have 20 or fewer carbon atoms, and may have 18 or fewer, 16 or fewer, 14 or fewer, 12 or fewer, or even 10 or fewer carbon atoms; and R g Each time it appears, it is independently an alkyl group having 1 to 6 carbon atoms, and may have 1 or more, 2 or more, 3 or more, 4 or more, or even 5 or more carbon atoms, and usually has 6 or fewer, 5 or fewer, 4 or fewer, 3 or fewer, or even 2 or fewer carbon atoms. Ideally, R f Each time it appears, it is independently an alkyl group having 6 to 12 carbon atoms. R g Ideally, it should be methyl to form a methoxy group attached to the silicon atom. Particularly desirable alkyltrialkoxysilanes are n-decyltrimethoxysilane, n-octyltrimethoxysilane, or mixtures thereof. Suitable alkyltrialkoxysilanes include n-decyltrimethoxysilane, which can be DOWSIL ™ Z-6210 silane is available from The Dow Chemical Company, or under the name SID2670.0 from Gallest (DOWSIL is a trademark of Dow Chemical Company).

[0068] Ideally, component (D) is a mixture of filler treatment agent (D-1) of formula (III) and filler treatment agent (D-2) of formula (V), wherein Y is [Si(CH3)2](CH2).n , where n is as defined above in equation (IV). More ideally, component (D) is selected from C9H. 19 [CH3)2SiO] 26 [Si(CH3)2]C6H 12 A mixture of Si(OCH3)3 filler treatment agent (D-1) and filler treatment agent (D-2) selected from n-decyltrimethoxysilane, n-octyltrimethoxysilane or mixtures thereof. Based on the weight of the curable thermally conductive composition, the component (D) filler treatment agent used in this invention can be present in a total concentration of 0.5 wt% to 2.5 wt%, and can be 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, 1.0 wt% or more, 1.2 wt% or more, 1.3 wt% or more, 1.4 wt% or more, 1.5 wt% or more, 1.6 wt% or more, or even 1.7 wt% or more, while typically 2.5 wt% or less, and can be 2.4 wt% or less, 2.3 wt% or less, 2.2 wt% or less, 2.1 wt% or less, 2.0 wt% or less, or even 1.9 wt% or less. Ideally, based on the weight of the curable thermally conductive composition, the trialkoxysilyl diorganopolysiloxane (D-1) is present at a concentration of 0.5 wt% to 2.5 wt%, and may be 0.5 wt% or greater, 0.6 wt% or greater, 0.7 wt% or greater, 0.8 wt% or greater, 0.9 wt% or greater, 1.0 wt% or greater, 1.1 wt% or greater, 1.2 wt% or greater, 1.5 wt% or greater, or even 1.6 wt% or greater, while typically present at a concentration of 2.5 wt% or less, and may be 2.4 wt% or less, 2.2 wt% or less, 2.0 wt% or less, 1.8 wt% or less, or even 1.7 wt% or less. Alternatively or concurrently, based on the weight of the curable thermally conductive composition, the alkyltrialkoxysilane (D-2) may be present at a concentration of 0% to 0.4% by weight, and may be greater than 0% by weight, 0.01% by weight or more, 0.05% by weight or more, 0.1% by weight or more, 0.14% by weight or more, or even 0.15% by weight or more, and is typically 0.5% by weight or less, and may be 0.4% by weight or less, 0.3% by weight or less, or even 0.2% by weight or less.

[0069] The curable thermally conductive compositions of the present invention may contain or not contain one or more platinum (Pt)-based hydrosilylation catalysts (component (E)). Such hydrosilylation catalysts may include compounds and complexes such as platinum (O)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane (Karstedt's catalyst), H₂PtCl₆, di- .-Carbonyl di-. - Cyclopentadienyl nickel, platinum-carbonyl complexes, platinum-divinyltetramethyldisiloxane complexes, platinum cyclovinylmethylsiloxane complexes, platinum acetylacetonate (acac), platinum black, platinum compounds (such as chloroplatinic acid, chloroplatinic acid hexahydrate, the reaction product of chloroplatinic acid with a monohydric alcohol, bis(ethyl acetoacetate)platinum, bis(acetylacetonate)platinum, platinum dichloride), and platinum compounds in complexes with olefins or low molecular weight organopolysiloxanes, or platinum compounds microencapsulated in a matrix or core-shell structure. The hydrosilylation catalyst may be part of a solution comprising complexes of platinum with low molecular weight organopolysiloxanes, including complexes of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum. These complexes may be microencapsulated or deencapsulated in a resin matrix (typically, in phenyl resins). The resin matrix used for microencapsulating the complexes may be a phenyl resin, an acrylate polymer, polycarbonate, or other resin matrices with a melting point below 150°C to release Pt during thermosetting. Exemplary hydrosilylation catalysts are described in U.S. Patents 3,159,601 and 3,220,972, and encapsulated platinum catalysts are described in WO2014017671A1. These catalysts may be complexes of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum. Platinum-based hydrosilylation catalysts are commercially available, for example, SYL-OFF. ™ The 4000 catalyst, SYL-OFF 4500 catalyst, and SYL-OFF 2700 catalyst are available from Dow Chemical Company (SYL-OFF is a trademark of Dow Chemical Company). Two different catalysts (e.g., E1 and E2) activated at different temperatures can be added. The two different catalysts can be (E1) a complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum, and (E2) an encapsulated platinum catalyst, such as a complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum, encapsulated in a dimethylsiloxane containing phenylsilsesquioxane.

[0070] Based on the weight of the curable thermally conductive composition, the amount of component (E) platinum-based hydrosilylation catalyst is sufficient to provide 0.5 ppm to 300 ppm of platinum, and may be 0.5 ppm or more, 5 ppm or more, 10 ppm or more, 20 ppm or more, or even 30 ppm or more, while typically 300 ppm or less, and may be 200 ppm or less, 130 ppm or less, 100 ppm or less, or even 50 ppm or less. Alternatively, based on the weight of the curable thermally conductive composition, the amount of platinum-based hydrosilylation catalyst may be from 0.01 wt% to 0.6 wt%, and may be 0.01 wt% or greater, 0.03 wt% or greater, 0.04 wt% or greater, 0.05 wt% or greater, 0.06 wt% or greater, or even 0.07 wt% or greater, while typically being 0.6 wt% or less, and may be 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, 0.2 wt% or less, 0.1 wt% or less, 0.09 wt% or less, 0.08 wt% or less, or even 0.075 wt% or less.

[0071] The curable thermally conductive compositions of the present invention may contain or exclude one or more of a combination of hydrosilylation inhibitors (component (F), also referred to as "inhibitors"). Inhibitors can be used to stabilize the curable thermally conductive compositions to prevent premature curing and to provide storage stability to the compositions. Examples of suitable inhibitors include any combination of one or more of the following: acetylene compounds, such as 2-methyl-3-butyn-2-ol; 3-methyl-1-butyn-3-ol; 3,5-dimethyl-1-hexyn-3-ol; 2-phenyl-3-butyn-2-ol; 3-phenyl-1-butyn-3-ol; 1-ethynyl-1-cyclohexanol; 1,1-dimethyl-2-propynyl)oxy)trimethylsilane; and methyl(tri(1,1-dimethyl-2-propynyl))trimethylsilane. oxysilanes; enylene-yne ​​compounds, such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; triazoles, such as benzotriazoles; hydrazine-based compounds; phosphine-based compounds; thiol-based compounds; cycloalkenylsiloxanes, including methylvinylcyclosiloxanes, such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane.

[0072] Based on the weight of the curable thermally conductive composition, the concentration of component (F) inhibitor can be from zero wt% to 0.5 wt%, and can be 0.001 wt% or greater, 0.002 wt% or greater, 0.003 wt% or greater, 0.01 wt% or greater, 0.05 wt% or greater, or even 0.1 wt% or greater, while typically being 0.5 wt% or less, and can be 0.3 wt% or less, 0.2 wt% or less, 0.15 wt% or less, 0.01 wt% or less, 0.005 wt% or less, 0.004 wt% or less, or even 0.003 wt% or less.

[0073] The curable thermally conductive composition of the present invention may contain or exclude other optional components, which include any combination of one or more of the following components: heat stabilizers and / or pigments (such as copper phthalocyanine powder), thixotropic agents, fumed silica (ideally, surface-treated), and isolating additives (such as glass beads). Based on the weight of the curable thermally conductive composition, the total concentration of these additional components may range from 0.6% by weight, and may be greater than 0.05% by weight, 0.1% by weight or greater, 0.2% by weight or greater, 0.3% by weight or greater, 0.4% by weight or greater, or even 0.5% by weight or greater, while typically being 0.6% by weight or less, and may be 0.5% by weight or less, 0.4% by weight or less, 0.3% by weight or less, 0.2% by weight or less, 0.1% by weight or less, or even 0.05% by weight or less.

[0074] The curable thermally conductive composition of the present invention may contain or not contain (G) a combination of one or more solvents. Based on the weight of the curable thermally conductive composition, the solvent concentration may be less than 0.01% by weight, less than 0.005% by weight, or even 0%. Ideally, the curable thermally conductive composition is substantially solvent-free, i.e., solvent-free or may contain trace amounts of residual solvent delivered from the starting material in the composition. The solvent concentration can be measured by gas chromatography (GC). If the amount of solvent is too high, voids tend to form during the curing of the curable thermally conductive composition, resulting in a poor surface appearance or even reduced thermal conductivity. The solvent can be an organic solvent, such as saturated or unsaturated aliphatic or aromatic hydrocarbons, such as benzene, toluene, xylene, hexane, heptane, octane, isoalkanes, hydrocarbon compounds having 8 to 18 carbon atoms per molecule and at least one aliphatic unsaturated group, such as tetradecene; ketones, such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; acetates, such as ethyl acetate or isobutyl acetate; ethers, such as glycol ethers, such as propylene glycol methyl ether, dipropylene glycol methyl ether and propylene glycol n-butyl ether, diisopropyl ether, or 1,4-dioxane; cyclic or linear siloxanes having an average degree of polymerization of 3 to 10, such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and / or decamethylcyclopentasiloxane; or mixtures thereof. The curable thermally conductive composition does not require the use of any solvents (such as those described above) while still achieving desirable ER (i.e., good processability) and TC properties, as described below.

[0075] The curable thermally conductive composition of the present invention achieves an extrusion rate (ER) of 240 g / min or greater. The ER can be determined using a standard 30 cm³ EFD syringe packaged at a pressure of 0.62 MPa and 25°C (further details are provided below under the extrusion rate test). Ideally, the thermally conductive composition can have an ER of 250 g / min or greater, more ideally 300 g / min or greater. ER is a useful characteristic as a measure of extrudability, viscosity, and dispensability, which, for example, allows the curable thermally conductive composition to be easily dispensed for application to another material (such as electronic components or heat sinks). Meanwhile, the curable thermally conductive composition of the present invention achieves a curing rate of less than 2.2 g / cm³ as measured according to ASTM D792 upon curing. 3 The density is such that the cured sample provides a thermal conductivity (TC) of at least 2.4 W / m*K, ideally 2.5 W / m*K or greater, and more ideally 2.6 W / m*K or greater, as measured using a hot plate according to ISO 22007-2 (further details are provided in the thermal conductivity test section below). Such a high TC (providing effective heat dissipation) and ease of dispensing make the curable thermally conductive composition particularly suitable as a thermally conductive interface material for effectively transferring heat between two components. Thermally conductive interface materials are commonly used for thermally coupling heat-generating and heat-dissipating components, especially in electronic devices.

[0076] The present invention also relates to a method for preparing a curable thermally conductive composition. The method comprises mixing an alkenyl-functionalized polyorganosiloxane, a SiH crosslinking agent, a thermally conductive filler, a filler treatment agent, and optionally a hydroxylation reaction catalyst and inhibitor, as well as other optional components described above.

[0077] The present invention also relates to a method for using the curable thermally conductive composition described above. The method includes: step (i) providing the curable thermally conductive composition; step (ii) applying the curable thermally conductive composition to an electronic component; and step (iii) curing the curable composition; thereby forming a thermally conductive silicone material (i.e., a cured material). Ideally, the application of the curable thermally conductive composition involves dispensing or extruding the curable thermally conductive composition. Due to the aforementioned properties of the curable thermally conductive composition, such as excellent dispensability and conformability indicated by the aforementioned low ER, this method allows for automated dispensing and assembly (i.e., increased productivity) with minimal stress applied to fill complex geometries and varying gaps, thereby avoiding potential damage to the electronic component. In step (iii) of the method, the thermally conductive composition can be cured at room temperature or by heat, for example at temperatures above 25°C, and possibly above 40°C or above 80°C. The curing duration can vary depending on the temperature, typically from 0.5 hours to 24 hours. The curable thermally conductive composition can be cured by heat generated by the electronic component. Examples of electronic components that generate heat during the operation of electronic devices that include such components include central processing units (CPUs), graphics processing units (GPUs), memory chips, batteries, driver chips, and optical modules. Ideally, when the electronic device is in operation, the heat generated by the electronic components typically solidifies the curable thermally conductive composition within a few hours, thus forming a cured material.

[0078] Because the concentration of solvent in the curable thermally conductive composition is low or absent, this method does not include (i.e., does not contain) additional procedures for removing the solvent, such as stripping or evaporating the solvent. While still imparting the desired properties to the resulting composition as described above, the curable thermally conductive composition allows the method to use the composition without the aid of a solvent, and also makes it suitable for dispensing the composition (e.g., by extrusion) directly onto parts of an article without the need to add a solvent to the composition prior to use.

[0079] The present invention further relates to an article of manufacture. The article of manufacture may be formed by the methods described above, or may comprise a curable thermally conductive composition and an electronic component on which the thermally conductive composition is applied. The thermally conductive composition may be applied to one or two heat-generating electronic components. The article of manufacture may also include another component, such as another electronic component that is the same as or different from the electronic component or heat dissipation component on which the thermally conductive composition is applied, such that the thermally conductive composition is between and in contact with one electronic component and a heat dissipation component, or between and in contact with two electronic components of an electronic device, wherein at least one electronic component generates heat when the electronic device is in operation. Examples of suitable heat dissipation components include radiators, cooling plates / pads, cooling pipes, and metal shields. Ideally, the article of manufacture of the present invention is an electronic device. Examples of suitable electronic devices may include optical modules, smartphones, digital cameras, computers, tablet devices, servers and base stations for communication, power inverters, DC-DC converters, advanced driver assistance systems (ADAS), and battery packs (e.g., lithium-ion batteries) in electric vehicles (EVs). In particular, curable thermally conductive compositions are suitable as heat dissipation materials (which can be used as interstitial fillers) for automotive electronic components that require lightweight, excellent dispersibility and high-temperature durability.

[0080] Example

[0081] Some embodiments of the invention will now be described in the following examples, wherein all weight percentages (wt%) are relative to the weight of the composition unless otherwise specified, and all particle sizes of the filler are D50 particle sizes. Table 1 lists the materials of the thermally conductive compositions used in the samples described below. Note: “Vi” represents vinyl, “Me” represents methyl, and “TC filler” is a guide thermal filler. SYL-OFF is a trademark of The Dow Chemical Company.

[0082] Table 1

[0083]

[0084]

[0085] *The viscosity of the polysiloxane was measured at 25°C according to ASTM D445-21.

[0086] D50 was measured using a Mastersizer 2000 from Malvern Instruments (with Hydro 2000 SM dispersion unit).

[0087] Samples of Examples (IE) 1 to 6 and Comparative Examples (CE) 1 to 8 of the present invention

[0088] The formulations of the samples are shown in Tables 2 and 3, where the amount of each component is reported in grams (g). The formulations were prepared using SpeedMixer from FlackTek Inc. (South Carolina, USA). ™ The DAC 400 FVZ mixer was used to combine these components to prepare the sample. Vi polymer (A-1), SiH crosslinking agents (B-1) and (B-2), treatment agents (D-1) and (D-2), and TC filler C3 were added to the cup of the SpeedMixer. The mixture was mixed at 1000 rpm for 20 seconds, then at 1500 rpm for 20 seconds. TC filler C2 was added and mixed at 1000 rpm for 20 seconds, then at 1500 rpm for 20 seconds. TC filler C1 or TC filler [C1+C2], and TC fillers C4 and C5 (if used), were added and mixed in the same manner. The resulting composition in the cup was scraped to ensure homogeneous mixing, and then Pt catalyst E-1, inhibitor F-1, and pigment G-1 were added and mixed in a similar manner to obtain a curable thermally conductive composition sample.

[0089] The extrusion rate, thermal conductivity, and density of the obtained thermally conductive composition samples were evaluated using the following test methods:

[0090] Extrusion rate test

[0091] The extrusion rate (“ER”) of the sample was determined using a Nordson EFD dispensing apparatus. The sample material was loaded into a 30 cubic centimeter syringe (an EFD syringe from Nordson Company) with a 2.54 mm opening. The sample was dispensed through the opening at 25°C by applying a pressure of 0.62 MPa to the syringe. The mass of sample extruded in grams (g) after one minute corresponds to the extrusion rate in g / min. The objective of this invention is to achieve an extrusion rate of at least 240 g / min. It is worth noting that some samples were non-extrudable powdery pastes, and therefore they were reported with an ER of 0 (and thermal conductivity and density were not measured, therefore reported as “NA”).

[0092] Thermal conductivity test

[0093] Thermal conductivity (“TC”) was determined using a hot plate according to ISO 22007-2. The thermal conductivity of the cured sample was measured using a Hot Disk TPS 2500 S instrument with a 3.189 mm Kapton sensor (model 5465). The cured sample, measuring 25 mm × 25 mm × 8 mm, was prepared by curing the above-prepared curable thermally conductive composition sample at 100 °C for 60 minutes. The objective of this invention is to achieve a thermal conductivity of at least 2.4 W / m × K.

[0094] Density test

[0095] The density of the cured sample was measured according to ASTM D792. An acceptable density is less than 2.2 g / cm³. 3 Prepare a cured sample according to the same method described in the above thermal conductivity test.

[0096] The extrusion rate of each sample was characterized using the extrusion rate test described above, the thermal conductivity of each sample was characterized using the thermal conductivity test described above, and the density of each sample was characterized using the density test described above. Table 2 includes the characterization results for samples IE1 to IE6. As shown in Table 2, samples IE1 to IE6, each containing a specific amount of at least three different TC fillers, all showed a density of less than 2.2 g / cm³. 3 The low density of the filler material achieves both an ER of at least 240 g / min (or even 300 g / min or higher) and a TC of at least 2.4 W / m*K (or even 2.5 W / m*K or higher). This TC filler comprises ATH filler with (C1) D50 ranging from 70 µm to 150 µm, ATH filler with (C2) D50 ranging from 1 µm to 30 µm, and Al2O3 filler with (C3) D50 ranging from 0.1 µm to 4 µm. Specifically, IE 1, IE 4, and IE 5 samples each exhibit even higher ERs (e.g., greater than 300 g / min).

[0097] Table 2

[0098]

[0099] Note: In Tables 2 and 3 below:

[0100] "Fill weight %" refers to the weight of the total thermally conductive filler relative to the total weight of all components in the sample.

[0101] The "SiH / Vi ratio" refers to the molar ratio of SiH functional groups to vinyl functional groups from the crosslinking agent.

[0102] Evaluate “ER”, “TC” and “density” according to the test methods described above.

[0103] Table 3 contains the characterization results for samples CE 1 to CE 8. Each of the samples CE 1 to CE 8 does not contain one or more of the claimed TC fillers (C1), (C2) and (C3) (e.g., differs from the IE sample in terms of filler type and / or particle size) and / or fails to meet at least one of the above-mentioned TC, density and ER requirements beyond the claimed concentration.

[0104] CE 1 samples without Al2O3 fillers having a D50 in the range of 0.1µm to 4µm and CE 3 samples containing the claimed TC fillers (C1), (C2) and (C3) but at concentrations outside the claimed concentration range both produced ERs well below 240 g / min.

[0105] CE 2 samples containing Al2O3 packing material with D50 in the range of 0.1µm to 4µm but only containing ATH packing material with different D50 and / or concentrations outside the claimed protection range of TC packing material (C1) and (C2) do not meet both ER and TC requirements.

[0106] CE 5 samples containing only smaller ATH and Al2O3 fillers but lacking ATH fillers with a D50 of 70µm to 150µm failed to meet TC and density requirements. CE 6 samples using only ATH fillers with D50s ranging from 1µm to 30µm produced an ER of less than 240 g / min.

[0107] Samples using TC packing packages with a different packing type and / or concentration than the claimed TC packing combination fail to meet one or more of the above three requirements. For example, CE 4 samples provide greater than 2.2 g / cm³. 3 The density, and the CE 7 and CE 8 samples provided ER well below 240 g / min.

[0108] Table 3

[0109]

Claims

1. A curable thermally conductive composition, said curable thermally conductive composition comprising: (A) 5% to 11% by weight of an alkenyl-functionalized polysiloxane, said alkenyl-functionalized polysiloxane having a viscosity in the range of 25 mPa·s to 500 mPa·s as determined by a glass capillary Canon-Fensk viscometer at 25 degrees Celsius using ASTM D445-21, wherein said alkenyl-functionalized polysiloxane has an average chemical structure (I): Where R a Each time it appears, it is independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, and each time it appears, it is independently an alkenyl group, with subscript a ≥ 0, subscript b > 0, subscript c being 0 or 1, subscript d being 0 or 1, (a+b) being 20 to 200, and (a+c+d) ≥ 2; (B) A silyl-hydride functional polysiloxane crosslinker, wherein each molecule of the silyl-hydride functional polysiloxane crosslinker contains at least two silyl-hydride groups and is present at a concentration that provides a molar ratio of silicon-bonded hydrogen atoms to alkenyl groups of 0.3:1 to 1.5:1 for the composition; (C) 85% to 92% by weight of thermally conductive filler, wherein the thermally conductive filler comprises: (C1) 40% to 55% by weight of aluminum hydroxide particles with D50 in the range of 70 to 150 micrometers. (C2) 15% to 30% by weight of aluminum hydroxide particles with D50 in the range of 1 micrometer to 30 micrometers, and (C3) 10 wt% to 25 wt% of alumina particles with D50 in the range of 0.2 micrometers to 4 micrometers, and (D) A filler treatment agent selected from trialkoxysilyl diorganopolysiloxanes, alkyltrialkoxysilanes, or mixtures thereof; wherein the trialkoxysilyl diorganopolysiloxane has an average chemical structure (IV): Where R c R d and R e Each occurrence is independently an alkyl group having 1 to 20 carbon atoms, the subscript g has a value of 20 to 130, and Y is O or [OSiR]. d 2](CH2) n The subscript n has values ​​from 3 to 20; The weight percentages are relative to the weight of the curable thermally conductive composition.

2. The curable thermally conductive composition according to claim 1, wherein the curable thermally conductive composition further comprises (E) a platinum-based hydrosilylation catalyst, wherein the amount of the platinum-based hydrosilylation catalyst is sufficient to provide 0.5 ppm to 300 ppm of platinum based on the weight of the curable thermally conductive composition.

3. The curable thermally conductive composition according to claim 1 or 2, wherein the curable thermally conductive composition further comprises (F) a hydrosilylation inhibitor, wherein the concentration of the hydrosilylation inhibitor is from 0.001% by weight to 0.5% by weight based on the weight of the curable thermally conductive composition.

4. The curable thermally conductive composition according to claim 1 or 2, wherein the alkenyl-functionalized polyorganosiloxane comprises a vinyl dimethylsiloxy-terminated polydimethylpolysiloxane having an average chemical structure (II): Where Vi represents vinyl and the subscript b has a value from 20 to 200.

5. The curable thermally conductive composition according to claim 1 or 2, wherein, based on the weight of the curable thermally conductive composition, the filler treatment agent comprises 0.5% to 2.5% by weight of the trialkoxysilyl diorganopolysiloxane having the average chemical structure (IV), wherein R c Both of them and R d and R e Both are methyl groups, one R c It is an alkyl group having 3 to 20 carbon atoms, and Y is [OSi(CH3)2](CH2). n The subscript n is in the range of 3 to 6.

6. The curable thermally conductive composition according to claim 1 or 2, wherein, based on the weight of the curable thermally conductive composition, the thermally conductive filler (C) comprises: (C1) 45% to 55% by weight of D50 are aluminum hydroxide particles larger than 100 to 130 micrometers. (C2) 18% to 30% by weight of D50 aluminum hydroxide particles ranging from 1 to 20 micrometers, and (C3) 15% to 25% by weight of D50 is alumina particles of 0.2 to 2 micrometers.

7. The curable thermally conductive composition according to claim 1 or 2, wherein, based on the weight of the curable thermally conductive composition, the thermally conductive filler (C) comprises: (C1) 45% to 55% by weight of D50 are aluminum hydroxide particles of 70 to 100 micrometers. (C2) 15% to 25% by weight of D50 aluminum hydroxide particles ranging from 1 to 15 micrometers, and (C3) 10% to 25% by weight of D50 is alumina particles ranging from 0.2 micrometers to less than 1 micrometer.

8. The curable thermally conductive composition according to claim 1 or 2, wherein, based on the weight of the curable thermally conductive composition, the thermally conductive filler (C) comprises less than 10% by weight of alumina particles with a D50 greater than 4 micrometers.

9. A method for using a curable thermally conductive composition according to any one of claims 1 to 8, the method comprising: (i) Providing the curable thermally conductive composition. (ii) Applying the curable thermally conductive composition to the electronic component, and (iii) Curing the curable thermally conductive composition.

10. An article comprising a curable thermally conductive composition according to any one of claims 1 to 8 and an electronic component having the curable thermally conductive composition applied thereon, wherein the curable thermally conductive composition is in a cured form.

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