Addition curable thermally conductive organopolysiloxane adhesive composition

Abstract

A two-part addition curable thermally conductive adhesive composition comprising: A) a vinyl functional polysiloxane having at least two vinyl groups per molecule, B) at least one hydrosilylation catalyst, C) at least one condensation catalyst, D) at least one silyl hydride functional polysiloxane, E) at least one thermally conductive filler, and D) at least one silane hydride functional polysiloxane, f) at least one SiH-functional silane, and G) at least one Q-branched alkenyl polymer.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a two-part addition-curable thermally conductive organopolysiloxane adhesive composition. BACKGROUND

[0002] Electrically insulating and thermally conductive adhesives are commonly used in the electronics industry to thermally couple components to help dissipate heat. Silicone-based thermally conductive adhesives show the advantage of high elasticity and good durability compared to organic-based adhesives such as epoxy or PU. Silicone-based thermally conductive adhesives can be obtained by compounding a polysiloxane matrix with a thermally conductive but electrically insulating filler. However, establishing high adhesive strength at lower curing temperatures, such as 0.5 h at 70 °C, is one of the key challenges for addition-curable silicone systems.

[0003] Addition-curable silicone systems have vinyl-functional polysiloxanes and SiH-functional polysiloxanes and can be cured via Pt catalyst catalysis at room temperature or elevated temperatures (system D). Adhesion promoters designed for addition-curable silicone systems typically require high temperatures to establish sufficient adhesive strength. Another type of silicone is condensation-cured silicone, which is catalyzed by condensation catalysts (system F). It can be cured at room temperature, and good adhesion can be formed just by exposure to moisture.

[0004] Thermally conductive silicone materials have low surface energy and it is difficult to form strong adhesion with most substrates. For addition-curable silicone products, they typically require adhesion promoters such as epoxy or acryl-functional silanes to establish good adhesive strength at high temperatures (typically > 120 °C) during curing. To achieve good adhesive strength at low temperatures (≤ 70 °C), system D+F technology has been used.

[0005] However, the adhesive strength of thermally conductive addition-curable silicone compositions is still not good enough in some applications where PU or epoxy-based adhesives are commonly used.

[0006] In view of the above, there is still a continuing need for addition-curable thermally conductive adhesive compositions that exhibit good adhesive strength at low temperatures. SUMMARY

[0007] After continuous exploration, we surprisingly found a two-part addition-curable thermally conductive adhesive composition that exhibits good adhesive strength.

[0008] In a first aspect of the present disclosure, the present disclosure provides a two-part addition-curable thermally conductive adhesive composition comprising:

[0009] A) a vinyl-functional polysiloxane having at least two vinyl groups per molecule,

[0010] B) at least one hydrosilylation catalyst,

[0011] C) at least one condensation catalyst,

[0012] D) at least one silyl hydride functional polysiloxane,

[0013] E) at least one thermally conductive filler,

[0014] F) at least one SiH functional silane, and

[0015] G) at least one Q- branched alkenyl polymer.

[0016] In a second aspect of the disclosure, the disclosure provides an article comprising a cured product formed by curing a two-part addition-curable thermally conductive adhesive composition described herein.

[0017] In a third aspect of the disclosure, the disclosure provides use of a composition described herein in the preparation of an article.

[0018] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application as claimed. DETAILED DESCRIPTION

[0019] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Also, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference.

[0020] As disclosed herein, the term “composition,” “formulation,” or “mixture” refers to a physical blend of different components that is obtained by simply mixing the different components by physical means.

[0021] As disclosed herein, “and / or” means “and, or as an alternative.” Unless otherwise indicated, all ranges include endpoints.

[0022] “Alkyl” means an acyclic, branched or unbranched, saturated, monovalent hydrocarbon group. Examples of alkyl groups are, but are not limited to, Me, Et, Pr (e.g., iso-propyl and / or n-propyl), Bu (e.g., iso-butyl, n-butyl, t-butyl, and / or sec-butyl), pentyl (e.g., iso-pentyl, neopentyl, and / or t-pentyl), hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl, and branched saturated monovalent hydrocarbon groups of 6 to 12 carbon atoms. Alkyl groups can have 1 to 30, alternatively 1 to 24, alternatively 1 to 20, alternatively 1 to 12, alternatively 1 to 10, alternatively 1 to 8, and alternatively 1 to 6 carbon atoms.

[0023] "Alkoxy" means -O-alkyl, where alkyl is as described above.

[0024] "Alkenyl" means a noncyclic, branched or unbranched monovalent hydrocarbon group having one or more carbon-carbon double bonds. Alkenyl groups are exemplified by, but not limited to, vinyl, allyl, methallyl, propenyl, and hexenyl. Alkenyl groups can have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, alternatively 2 to 6 carbon atoms.

[0025] "Aryl" means a cyclic, fully unsaturated hydrocarbon group. Examples of aryl groups are, but are not limited to, cyclopentadienyl, phenyl, anthracenyl, and naphthyl. Monocyclic aryl groups can have 5 to 9, or 6 to 7, and or 5 to 6 carbon atoms. Polycyclic aryl groups can have 10 to 17, alternatively 10 to 14, and alternatively 12 to 14 carbon atoms.

[0026] As used with respect to another group (e.g., a hydrocarbon group), the term "substituted" means that one or more of the hydrogen atoms in the hydrocarbon group has been replaced with another substituent. Examples of such substituents include, for example, halogen atoms such as chlorine, fluorine, bromine, and iodine; halogen atom-containing groups such as chloromethyl, perfluorobutyl, trifluoroethyl, and nonafluorohexyl; oxygen atoms; oxygen atom-containing groups such as (meth)acrylic acid and carboxyl groups; nitrogen atoms; nitrogen atom-containing groups such as amines, amino functional groups, amido functional groups, and cyano functional groups; sulfur atoms; and sulfur atom-containing groups such as mercapto groups.

[0027] M, D, T, and Q units are generally represented as R u SiO (4–u) / 2 where u is 3, 2, 1, and 0 for M, D, T, and Q, respectively, and R is an independently selected hydrocarbyl group. M, D, T, Q represent one (Mono), two (Di), three (Tri), or four (Quad) oxygen atoms covalently bonded to a silicon atom, which is connected to the rest of the molecular structure.

[0028] The two-part addition-curable thermally conductive adhesive composition comprises:

[0029] A) a vinyl-functional polysiloxane having at least two vinyl groups per molecule,

[0030] B) at least one hydrosilylation catalyst,

[0031] C) at least one condensation catalyst,

[0032] D) at least one silyl hydride-functional polysiloxane,

[0033] E) at least one thermally conductive filler,

[0034] F) at least one SiH-functional silane, and

[0035] G) at least one Q-alkenyl polymer.

[0036] Components of the composition

[0037] A) a vinyl-functional polysiloxane having at least two vinyl groups per molecule

[0038] The vinyl-functional polysiloxane A) having at least two vinyl groups per molecule can be a linear polysiloxane having the following molecular structure (I):

[0039] R x Vi (3-x) SiO-(R2SiO) d -SiR y Vi (3-y) (I)

[0040] wherein R is independently at each occurrence selected from the group consisting of alkyl groups having 1 to 8 carbon atoms (preferably alkyl groups having 1 to 6 carbon atoms, more preferably alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or t-butyl) and aryl groups having 6 to 14 carbon atoms (preferably phenyl or naphthyl); Vi is a vinyl group (-CH=CH2); x and y indicate the average number of terminal R groups on each end of the linear polysiloxane, and each of x and y is independently selected from a number in the range of 0 to 2, preferably 1 to 2, and ideally x=y; (3-x) and (3-y) indicate the average number of terminal Vi groups on each end of the linear polysiloxane; and d is the average number of (R2SiO) groups in the linear polysiloxane, and is typically 10 or more, preferably 50 or more, and at the same time 1000 or less, preferably 500 or less. Ideally, R is methyl at each occurrence; at the same time, it is generally desired that x and y are each 2.

[0041] Generally, the content of A) the vinyl-functional polysiloxane having two vinyl groups per molecule used herein is 3% by weight or more, preferably 4% by weight or more, more preferably 5% by weight or more, most preferably 6% by weight or more, and at the same time 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less, most preferably 15% by weight or less, based on the total weight of the adhesive composition.

[0042] B) a hydrosilylation catalyst

[0043] The hydrosilylation catalyst B) can include any substance capable of promoting a hydrosilylation reaction. Suitable hydrosilylation catalysts are known in the art and are commercially available. Component B) can comprise a platinum group metal selected from platinum, rhodium, ruthenium, palladium, osmium or iridium metals, or an organometallic compound thereof, or a combination thereof. Preferred are platinum compounds such as chloroplatinic acid, reaction products of chloroplatinic acid with alcohols, platinum-olefin complexes, platinum-vinylsiloxane complexes, platinum-ketone complexes and platinum-phosphine complexes; rhodium compounds such as rhodium-phosphine complexes and rhodium-sulfide complexes; and palladium compounds such as palladium-phosphine complexes, more preferred are platinum compounds, and particularly preferred are platinum-vinylsiloxane complexes.

[0044] Examples of hydrosilylation catalysts B) are platinum metal fine powder, platinum black, platinum dichloride, platinum tetrachloride; chloroplatinic acid, alcohol-modified chloroplatinic acid, chloroplatinic acid hexahydrate; and complexes of said compounds such as platinum complexes of olefins, platinum complexes of carbonyls, platinum complexes of alkenylsiloxanes (e.g. 1,3-divinyltetramethyldisiloxane), platinum complexes of low molecular weight organopolysiloxanes (e.g. 1,3-divinyl-1,1,3,3-tetramethyldisiloxane), complexes of chloroplatinic acid with beta-diketones, complexes of chloroplatinic acid with olefins and complexes of chloroplatinic acid with 1,3-divinyltetramethyldisiloxane.

[0045] The hydrosilylation catalyst B) can also be a rhodium compound such as those represented by the following formulae: RhX3[(R 4 )2S]3; (R 5 3P)2Rh(CO)X, (R 5 3P)2Rh(CO)H, Rh2X2Y4, H f Rh g (En) h Cl i or Rh[O(CO)R] 3-j (OH) j (wherein X represents a hydrogen atom, a chlorine atom, a bromine atom or an iodine atom; Y represents a methyl group, an ethyl group or a similar alkyl group, CO, C8H 14 or 0.5 C8H 12 ; R 4 represents a methyl group, an ethyl group, a propyl group or a similar alkyl group; a cycloheptyl group, a cyclohexyl group or a similar cycloalkyl group; or a phenyl group, a xylyl group or a similar aryl group; R 5The symbols represent methyl, ethyl, or similar alkyl groups; phenyl, tolyl, xylyl, or similar aryl groups; methoxy, ethoxy, or similar alkoxy groups; "En" represents ethylene, propylene, butene, hexene, or similar olefins; "f" is 0 or 1; "g" is 1 or 2; "h" is an integer from 1 to 4; "i" is 2, 3, or 4; and "j" is 0 or 1. More specifically, rhodium compounds are RhCl(Ph3P)3, RhCl3[S(C4H9)2]3, [Rh(O2CCH3)2]2, Rh(OCCH3)3, Rh2(C8H 15 O2)4, Rh(C5H7O2)3, Rh(C5H7O2)(CO)2 and Rh(CO)[Ph3P](C5H7O2).

[0046] The hydrosilylation catalyst B) can also be an iridium group catalyst represented by the following formula: Ir(OOCCH3)3, Ir(C5H7O2)3, [Ir(Z)(En)2]2, or [Ir(Z)(Dien)]2 (where “Z” represents a chlorine atom, bromine atom, iodine atom, or a methoxy group, ethoxy group, or similar alkoxy group; “En” represents ethylene, propylene, butene, hexene, or similar olefins; and “Dien” refers to cyclooctadiene tetra(triphenyl)). Component (F) can also be a mixture of palladium, palladium black, and triphenylphosphine.

[0047] The hydrosilylation catalyst B) can be a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex.

[0048] The amount used is the amount of catalyst, which can be appropriately selected according to the required curing conditions. Generally speaking, based on the total weight of the adhesive composition, the content of the catalyst used herein is greater than or equal to 0.01% by weight and at most 1.0% by weight, preferably at most 0.5% by weight, and more preferably at most 0.25% by weight.

[0049] C) a condensation catalyst

[0050] A condensation catalyst is a component that imparts primary curability to the composition according to the invention within a temperature range of 70°C or lower, suitably 60°C or lower, and more suitably room temperature (25°C) to 50°C or lower by promoting the condensation reaction of the composition according to the invention. Examples of such condensation catalysts include: organotin compounds, such as dibutyltin dilaurate, dibutyltin diacetate, octentin, dibutyltin dioctanoate, tin laurate, dimethyltin dineodecanate, and stannous octoate; organotitanium compounds, such as tetra(isopropoxy)titanium, tetra(n-butoxy)titanium, tetra(tert-butoxy)titanium, di(isopropoxy)bis(ethyl acetoacetate)titanium (also known as diisopropoxy di(ethoxyacetoacetyl)titanate), di(isopropoxy) bis(methyl acetoacetate)titanium, bis(isopropoxy)bis(acetylacetonate)titanium, tetrabutyl titanate, tetrapropyl titanate and dibutoxybis(ethyl acetoacetate); acidic compounds such as hydrochloric acid, sulfuric acid and dodecylbenzenesulfonic acid; basic compounds such as ammonia and sodium hydroxide; and amine compounds such as 1,8-diazabicyclo[5.4.0]undecene (DBU) and 1,4-diazabicyclo[2.2.2]octane (DABCO), etc.

[0051] The amount used is the amount of catalyst, which can be appropriately selected according to the required curing conditions. Generally speaking, based on the total weight of the adhesive composition, the content of the catalyst used herein is greater than or equal to 0.01% by weight and at most 1.0% by weight, preferably at most 0.5% by weight, and more preferably at most 0.25% by weight.

[0052] D) a silyl hydride functional polysiloxane

[0053] Silyl-hydride-functionalized polysiloxanes have an average of at least two silyl-hydride groups per molecule. For the avoidance of ambiguity, the silyl-hydride groups are SiH groups. Silyl-hydride-functionalized polysiloxanes are sometimes referred to as crosslinking agents in compositions. Ideally, D) silyl-hydride-functionalized polysiloxanes are linear polysiloxanes having the following general molecular structure:

[0054] R' 3-h H h SiO-(HRSiO) a -(R2SiO) b -SiH h’ R' 3-h’ (II)

[0055] R and R' are each independently selected, in each occurrence, from alkyl groups having 1 to 8 carbon atoms (preferably alkyl groups having 1 to 6 carbon atoms, more preferably alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, or tert-butyl), alkoxy groups having 1 to 8 carbon atoms (preferably alkoxy groups having 1 to 6 carbon atoms, more preferably alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, or tert-butoxy), and... The aryl group (preferably phenyl or naphthyl) has 6 to 14 carbon atoms; H is hydrogen; subscripts h and h' refer to the average number of terminal hydrogens at the corresponding ends of the molecule, and their value is 0, 1, 2 or 3 (preferably 0, 1 or 2, more preferably 0 or 1, most preferably 1); subscript a is the average number of (HRSiO) groups per molecule; subscript b is the average number of (R2SiO) groups per molecule, subscripts a and b are 0 to 1000, provided that subscripts a and b are not simultaneously 0, and the sum of a, h and h' is at least 1, preferably at least 2. Preferably, the silyl hydride functionalized polysiloxane is a trimethylsiloxy-terminated methylhydrosiloxane-dimethylsiloxane copolymer, or a hydride-terminated polydimethylsiloxane.

[0056] Generally speaking, based on the total weight of the adhesive composition, the content of the silylhydride functional polysiloxane used herein is 0.05% by weight or more, preferably 0.10% by weight or more, more preferably 0.15% by weight or more, most preferably 0.20% by weight or more, and simultaneously 10% by weight or less, preferably 5% by weight or less, more preferably 2% by weight or less, and most preferably 0.6% by weight or less.

[0057] E) a thermally conductive filler

[0058] Examples of thermally conductive fillers include, but are not limited to, Al2O3, AlN, BN, SiC, and ZnO, as well as other fillers such as TiO2, SiO2, Fe2O3, Fe3O4, finely ground quartz powder, chalk, talc, diatomaceous earth, zeolite, conductive fillers, Ag, carbon black, graphite, metal oxides, functional nanoparticles, hollow beads, etc. These fillers can be endowed with hydrophobicity by treatment with organosilanes and / or organosiloxanes, with stearic acid, or with other reagents.

[0059] There are no particular restrictions on the shape of the thermally conductive filler particles; however, round or spherical particles can prevent the viscosity from increasing to undesirable levels when there is a high filler content in the composition. The average particle size of the thermally conductive filler will depend on various factors, including the type of thermally conductive filler selected by component E) and the exact amount added to the curable composition, as well as the thickness of the adhesive layer of the device in which the cured product of the composition will be used. In certain specific examples, the thermally conductive filler may have an average particle size in the range of 0.1 micrometers to 80 micrometers, alternatively 0.1 micrometers to 50 micrometers, and alternatively 0.1 micrometers to 10 micrometers.

[0060] Alternatively, the thermally conductive filler is independently one or more particles selected from the group consisting of: aluminum, copper, silver, carbon nanotubes, carbon fibers, graphene, graphite, silicon nitride, aluminum nitride, diamond, silicon carbide, silicon dioxide, alumina, aluminum trihydrate, zinc oxide, beryllium oxide, and magnesium oxide. Preferably, the thermally conductive filler is one or more particles selected from the group consisting of silicon dioxide, alumina, aluminum trihydrate, and zinc oxide. More preferably, the thermally conductive filler is a combination of particles of silicon dioxide, alumina, and zinc oxide, or a combination of particles of silicon dioxide and aluminum trihydrate. More preferably, the thermally conductive filler is a combination of spherical Al2O3 with a particle size of 20 μm to 60 μm, irregular Al2O3 with a particle size of 1 μm to 10 μm, and ZnO and SiO2 with a particle size of 0.05 μm to 0.20 μm; or the thermally conductive filler is a combination of aluminum trihydrate with a particle size of 15 μm to 35 μm, aluminum trihydrate and SiO2 with a particle size of 0.5 μm to 2 μm.

[0061] The amount used can be appropriately selected according to the required application. Generally speaking, based on the total weight of the adhesive composition, the content of the thermally conductive filler used herein is 60% by weight or more, 65% by weight or more, 70% by weight or more, and simultaneously 95% by weight or less, preferably 90% by weight or less, more preferably 88% by weight or less.

[0062] F) a SiH functional silane

[0063] SiH functional silanes are also referred to in this disclosure as adhesion promoter AP components.

[0064] F) SiH-functionalized silanes have the following structures:

[0065] HR 1 R 2 Si [OSiR 3 R 4 ] n -X-Si(OR 5 )3(II)

[0066] Where n is an integer between 1 and 10, preferably between 1 and 8, more preferably between 1 and 6, even more preferably between 1 and 4, and most preferably between 1 and 2; X is a linking group selected from the group consisting of C2-C6 alkylene (more preferably C2-C4 alkylene) and O; R 1 Each of R5 is independently a C1-C6 alkyl group, preferably a C1-C4 alkyl group, more preferably a methyl or ethyl group.

[0067] Generally speaking, based on the total weight of the adhesive composition, the content of SiH functional silane used herein is 0.05% by weight or more, preferably 0.08% by weight or more, more preferably 0.1% by weight or more, most preferably 0.12% by weight or more, and simultaneously 3% by weight or less, preferably 2% by weight or less, more preferably 1% by weight or less, and most preferably 0.4% by weight or less.

[0068] G) a Q- branched alkenyl polymer

[0069] G) Q-branched alkenyl polymers have the following structure:

[0070] (III)

[0071] in:

[0072] R is independently selected each time it appears from substituted or unsubstituted alkyl groups having 1 to 8 carbon atoms (preferably alkyl groups having 1 to 6 carbon atoms, more preferably alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl), or substituted or unsubstituted aryl groups having 6 to 14 carbon atoms (preferably phenyl or naphthyl).

[0073] R' is independently selected from R and a terminal unsaturated alkenyl group (preferably a terminal unsaturated vinyl group) having 2 to 6 carbon atoms each time it appears; and

[0074] The average values ​​of subscripts n1 to n4 are each greater than zero and are independently selected from the range of 10 to 200, preferably 20 to 180, more preferably 50 to 170, even more preferably 100 to 160, and most preferably 120 to 155.

[0075] The condition is that at least one R' is a terminal unsaturated alkenyl group (preferably a terminal unsaturated vinyl group) having 2 to 6 carbon atoms.

[0076] Generally speaking, based on the total weight of the adhesive composition, the content of the Q-branched alkenyl polymer used herein is 0.5% by weight or more, preferably 0.8% by weight or more, more preferably 1.0% by weight or more, most preferably 1.2% by weight or more, and simultaneously 10% by weight or less, preferably 8% by weight or less, more preferably 6% by weight or less, and most preferably 4% by weight or less.

[0077] I) other adjuvants

[0078] The compositions of the present invention may optionally include I) other additives. A single compound (I) or a mixture of two or more may be used. These additives (I) are, for example, inhibitors, stabilizers, silanes other than (F), adhesion promoters, fungicides, fragrances, rheology modifiers, moisture scavengers, corrosion inhibitors, filler treatment agents, antioxidants, light stabilizers, flame retardants, reagents affecting electrical properties, dispersants, solvents, adhesion promoters, pigments, dyes, plasticizers, organic polymers, heat stabilizers, etc. They include additives such as metal carbonates, metal sulfates, metal salts of carboxylic acids, fibers such as glass fibers, plastic fibers, plastic powders, dyes, pigments, etc.

[0079] Examples of suitable inhibitors are 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-dodecyn-3-ol, methyl vinylcyclosiloxanes, polymethyl vinylcyclosiloxanes such as 1,3,5,7-tetravinyltetramethyltetracyclosiloxane, divinyltetramethyldisiloxane, tetravinyldimethyldisiloxane, trialkyl cyanurate, alkyl maleate, organic sulfoxides, organic amines, diamines, phosphine and phosphites, nitriles, diaziridine, and oximes, acetylene compounds, phosphites, maleates, amines or alcohols, by which the processing life, onset temperature and crosslinking rate of the compositions of the present invention can be targeted.

[0080] Based on the total weight of the adhesive composition, the content of the inhibitor (e.g., methyl vinyl cyclosiloxane) is from 0% to 1.5% by weight, 0.01% to 1.0% by weight, or 0.02% to 0.5% by weight.

[0081] Based on the total weight of the adhesive composition, the content of the adhesion promoter, excluding F)SiH functional silane, is 0% to 5% by weight.

[0082] The pigment (e.g., iron oxide (Fe2O3)) content is from 0% to 10% by weight, based on the total weight of the binder composition.

[0083] Based on the total weight of the adhesive composition, the filler treatment agent (e.g., n-decyltrimethoxysilane; monodimethylvinylsiloxy-terminated and monotrimethoxysiloxy-terminated dimethylsiloxane) is present in an amount of 0% to 1% by weight. Based on the total weight of the adhesive composition, the moisture scavenger (e.g., trimethoxymethylsilane) is present in an amount of 0% to 1% by weight.

[0084] Composition

[0085] This composition is a two-part addition-curable thermally conductive adhesive composition.

[0086] Preferably, A) a vinyl-functionalized polysiloxane having at least two vinyl groups per molecule, B) at least one hydrogenation silylation catalyst, C) at least one condensation catalyst, E) at least one thermally conductive filler, G) at least one Q-branched alkenyl polymer and optionally I) other additives (such as filler treatment agents) are present in portion A of the two-part addition-curable thermally conductive adhesive composition; A) a vinyl-functionalized polysiloxane having at least two vinyl groups per molecule, D) at least one silyl hydride-functionalized polysiloxane, E) at least one thermally conductive filler, F) at least one SiH-functionalized silane, G) at least one Q-branched alkenyl polymer and optionally I) other additives (such as filler treatment agents, pigments, curing inhibitors, etc.) are present in portion B of the two-part addition-curable thermally conductive adhesive composition.

[0087] Preferably, the SiH / alkenyl (including vinyl and other alkenyl groups) ratio in the composition is greater than 0.7, and more preferably greater than 1.0. For example, the SiH / alkenyl ratio in the composition may be from 1.01 to 1.50, or from 1.02 to 1.40.

[0088] Preferably, the composition further comprises one or more of the following components: inhibitors, other adhesion promoters, pigments, filler treatment agents, moisture scavengers, and antioxidants.

[0089] Preferably, A) the amount of vinyl-functionalized polysiloxane having two vinyl groups per molecule is 5% to 30% by weight based on the total weight of the composition, B) the amount of at least one hydrogenation silylation catalyst is 0.01% to 0.5% by weight based on the total weight of the composition, C) the amount of at least one condensation catalyst is 0.01% to 0.5% by weight based on the total weight of the composition, and D) the amount of at least one silyl hydride-functionalized polysiloxane is 0.05% to 10% by weight based on the total weight of the composition.

[0090] The composition does not contain epoxy-containing coupling agents, such as (γ)-glycidylpropylmethyldimethoxysilane, which are used as adhesion promoters.

[0091] Manufacturing technique

[0092] Part A of a two-part addition-curable thermally conductive adhesive composition is formed by mixing A) a vinyl-functionalized polysiloxane having at least two vinyl groups per molecule, B) at least one hydrogenation silanization catalyst, C) at least one condensation catalyst, E) at least one thermally conductive filler, G) at least one Q-branched alkenyl polymer and optional I) other auxiliaries (such as filler treatment agents, moisture scavengers, etc.).

[0093] Part B of the two-part addition-curable thermally conductive adhesive composition is formed by mixing A) a vinyl-functionalized polysiloxane having at least two vinyl groups per molecule, D) at least one silyl hydride-functionalized polysiloxane, E) at least one thermally conductive filler, F) at least one SiH-functionalized silane, and G) at least one Q-branched alkenyl polymer, and optionally I) other additives (such as filler treatment agents, pigments, curing inhibitors, etc.).

[0094] This application also provides an article comprising a cured product formed by curing the two-part addition-curable thermally conductive adhesive composition disclosed herein. Preferably, the article is an electronic component or electronic device.

[0095] This application also relates to the use of the compositions of this disclosure in the preparation of articles. Preferably, the article is an electronic component or electronic device.

[0096] Examples

[0097] Some embodiments of the invention will now be described in the following examples, wherein all parts and percentages are by weight unless otherwise stated.

[0098] Table 1 below lists information about the raw materials used in the examples:

[0099] Table 1. Raw materials

[0100] Composition and experimental procedure for CE 1-11 samples and IE 1-6

[0101] Table 1-a. Composition of CE 1-6 samples

[0102] Table 1-b. Composition of CE 7-11 samples

[0103] Table 1-c. Composition of IE 1-6 samples

[0104] Preparation of CE 1-11 and IE 1-6 using a 4L kneader mixer .

[0105] Part A composition

[0106] The VP and QP polymer components, along with the TA filler treatment agent, were placed into a 10-liter Turello mixer container and mixed for 5 minutes at 20 rpm under a nitrogen flow of 0.4 m³ / h. The thermally conductive filler component was added, and stirring continued for 15 minutes. The mixture was then heated to 120°C under vacuum (approximately 0.1 MPa) for one hour. After cooling to 22°C, the MS, Pt 1 catalyst, and Ti catalyst components were added, and the mixture was mixed for 15 minutes at 750 RPM under nitrogen purging.

[0107] Part B composition

[0108] The VP and QP polymer components, red pigment, and TA component were placed in a 10-liter Turello mixer container and mixed at 20 RPM for 5 minutes under a nitrogen flow of 0.4 m³ / h. The thermally conductive filler component was added and mixing continued for 15 minutes. The mixture was heated to 120°C under vacuum (approximately 0.1 MPa) for one hour. After cooling to 22°C, the curing inhibitor, crosslinking agent XL component, and adhesion promoter AP component were added, and the mixture was mixed at 750 RPM for 15 minutes under nitrogen purging.

[0109] Table 2. Results of tested properties for CE and IE samples

[0110] Adhesion can be a physical or chemical bond between two materials. A substrate with reactive groups suitable for bonding (such as hydroxyl (OH) or carbonyl (C=O) groups on glass, plastics, and aluminum) will enhance this chemical attraction through van der Waals forces or weak hydrogen attraction. Al is known to have a surface energy of approximately 45 dynes / cm², representing the thermodynamic effect of how a liquid will "penetrate" the surface. However, silicone has a low surface energy, and a mismatch exists between the Al substrate and the silicone matrix. To improve adhesion, adhesion promoters can be applied to the surface of the substrate.

[0111] Several adhesion promoters exist that can minimize mismatch and improve adhesion strength to the substrate. Silane adhesion promoters that do not inhibit Pt catalysts can be used to increase adhesion. Silanes are known to functionalize the interface between the polymer matrix and the substrate to act as adhesion promoters and are widely used to improve adhesion to metal or glass substrates. Migration is an important consideration when selecting silanes. Therefore, if a silane has good mobility, can easily migrate to the interface, and simultaneously has strong interactions with both the silicone composite and the substrate, it should be an ideal candidate for adhesion promoter in this self-adhesive formulation. However, most adhesion promoters require high temperatures to establish good adhesion strength.

[0112] Therefore, several functionalized silanes were added to the thermally conductive potting compound formulation, and the improvement in lap shear strength was evaluated by testing. First, all lap shear test samples for CE and IE were cured at 70°C for 30 minutes, and then left at room temperature for 7 days. The lap shear strength was then collected, as shown in Table 2.

[0113] It was observed that adding functionalized silane adhesion promoters CE1 to CE3 did not significantly improve the adhesion strength when curing at a lower temperature of 70°C. When adding a condensation catalyst (CE4), functionalized silanes with epoxy groups showed a slight improvement. In the presence of a Ti catalyst, the adhesion strength increased to over 1 MPa when using Gemini trioxane-functionalized silanes (i.e., bis(trimethoxysilyl)hexane). When using SiH-functionalized silanes as adhesion promoters, the adhesion strength reached approximately 2 MPa in the presence of a Ti catalyst. CE7-CE9 showed that the combination of SiH and bis(trimethoxysilyl)hexane in the presence of a Ti catalyst exhibited good adhesion strength, and the adhesion strength increased as the SiH / Vi ratio increased from approximately 0.85 to approximately 1.35. Further increasing the SiH / Vi ratio to approximately 2.0 did not result in a further significant improvement in adhesion strength, as shown in CE10. In CE11, it was demonstrated that the use of SiH-functionalized silanes and Ti catalysts, as well as different filler systems, remained effective in improving adhesion. In CE11, pure ATH filler was used to provide a binder with a low density of 2 W / mK. However, even with the simultaneous use of a hydrosilylation catalyst and a condensation catalyst, none of the CE samples could provide a strong bond strength >2.5 MPa.

[0114] In the IE sample, a Q-branched alkenyl polymer is added to the system. The Q-branched alkenyl polymer has one siloxane branching point (“Q” siloxane unit) and four polysiloxane chains with alkenyl groups (preferably vinyl groups). When portions A and B are mixed in the presence of Pt and Ti catalysts, one, two, three, or even all of the alkenyl groups (preferably vinyl groups) on the four polysiloxane chains can react in situ with SiH functional silanes. The in-situ formation of 1-4 trioxane functional groups on the Q siloxane unit allows for stronger interactions with the Al substrate, thereby improving the adhesive strength of the composite material.

[0115] Sample IE1, containing a SiH-functionalized silane adhesive promoter and a Q-branched alkenyl polymer, exhibited good adhesive strength >2.5 MPa, meeting the requirements. Samples IE2-3 contained SiH and Gemini trioxane-functionalized silane adhesive promoters with varying loadings of Q-branched alkenyl polymers. Samples IE4-5, with the same loading of Q-branched alkenyl polymers, used low-density filler ATH and exhibited different SiH / VI ratios. The low-density type sample IE4-5 showed good adhesive strength >3.3 MPa, a significant improvement compared to sample CE11.

[0116] CE1: A 2.0 W / mK addition-curable thermally conductive adhesive with an epoxy-functionalized silane adhesive accelerator. Al₂O₃ and ZnO are used as thermally conductive fillers with different particle sizes. The filler loading is 86.3 wt% (TC approximately 2.09 W / mK, and density approximately 2.78 g / cm³). 3 The SiH / Vi ratio is approximately 1.00. 0.4% by weight of a high-temperature adhesion promoter (epoxy-functionalized silane) is present in part B. However, the lap shear strength to the Al substrate upon low-temperature curing is less than 0.1 MPa, indicating almost no adhesive strength.

[0117] Conclusion Adhesion accelerators with epoxy functional groups do not provide the required adhesion at low-temperature curing.

[0118] CE2: A 2.0 W / mK addition-curable thermally conductive adhesive with a bis(trimethoxysilyl)hexane adhesion promoter. Al₂O₃ and ZnO are used as thermally conductive fillers with different particle sizes. The filler loading is 86.3 wt% (TC approximately 2.13 W / mK, and density approximately 2.80 g / cm³). 3 The SiH / Vi ratio is approximately 1.00. 0.4 wt% bis(trimethoxysilyl)hexane is present in portion B. The lap shear strength to the Al substrate upon curing at low temperature is approximately 0.15 MPa, indicating weak adhesion.

[0119] ConclusionAdhesion promoters containing bis(trimethoxysilyl)hexane can provide weak adhesion to Al substrates when cured at low temperatures.

[0120] CE3: A 2.0 W / mK addition-curable thermally conductive adhesive with SiH-functionalized silane adhesive accelerator. Al₂O₃ and ZnO are used as thermally conductive fillers with different particle sizes. The filler loading is 86.3 wt% (TC approximately 2.10 W / mK, and density approximately 2.79 g / cm³). 3 The SiH / Vi ratio is approximately 1.01. 0.4% by weight of a SiH-functionalized silane adhesion promoter is present in portion B. The lap shear strength on the Al substrate is low upon curing at low temperatures, only about 0.25 MPa.

[0121] Conclusion Adhesion promoters with SiH functional silanes do not provide the required adhesion at low-temperature curing.

[0122] CE4: A 2.0 W / mK addition-curable thermally conductive binder with epoxy-functionalized silane and Ti catalyst. Al₂O₃ and ZnO are used as thermally conductive fillers with different particle sizes. The filler loading is 86.3 wt% (TC approximately 2.09 W / mK, and density approximately 2.78 g / cm³). 3 The SiH / Vi ratio is approximately 1.01. 0.4 wt% epoxy-functionalized silane adhesive accelerator is present in fraction B, and 0.18 wt% Ti is present in fraction A. The lap shear strength to the Al substrate remains low upon low-temperature curing, at only approximately 0.15 MPa.

[0123] Conclusion Adhesion promoters with epoxy functional groups, when used with Ti catalysts, cannot provide the required adhesion at low-temperature curing.

[0124] CE5: A 2.0 W / mK addition-curable thermally conductive adhesive with bis(trimethoxysilyl)hexane binder accelerator and Ti catalyst. Al₂O₃ and ZnO are used as thermally conductive fillers with different particle sizes. The filler loading is 86.3 wt% (TC approximately 2.07 W / mK, and density approximately 2.78 g / cm³). 3 The SiH / Vi ratio is approximately 1.01. 0.4 wt% bis(trimethoxysilyl)hexane adhesion promoter is present in fraction B, and 0.18 wt% Ti is present in fraction A. The lap shear strength to the Al substrate increases to 1.12 MPa upon curing at low temperature.

[0125] Conclusion Adhesion promoters with Gemini trioxane functional groups, when used with condensation catalysts, can improve adhesion at low temperatures, but still do not meet the requirements.

[0126] CE6: A 2.0 W / mK thermally conductive binder with SiH-functionalized silane binder promoter and Ti catalyst. Al₂O₃ and ZnO are used as thermally conductive fillers with different particle sizes. The filler loading is 86.3 wt% (TC approximately 2.11 W / mK, and density approximately 2.79 g / cm³). 3 The SiH / Vi ratio was approximately 1.02. 0.4 wt% SiH-functionalized silane adhesion promoter was present in fraction B, and 0.18 wt% Ti was present in fraction A. The lap shear strength of the Al substrate was significantly improved upon curing at low temperatures, reaching approximately 1.63 MPa.

[0127] Conclusion Adhesion promoters with SiH functional groups, when used in conjunction with condensation catalysts, can significantly improve adhesion, but slight modifications are still needed to meet the adhesion requirements at low temperatures.

[0128] CE7: ​​A 2.0 W / mK thermally conductive binder containing 0.25 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane binder accelerator in part B, and 0.18 wt% Ti in part A. The filler group remains a combination of Al2O3 and ZnO, with a total filler loading of 86.3 wt% (where TC is approximately 2.02 W / mK and density is approximately 2.77 g / cm³). 3 The SiH / Vi ratio is approximately 0.85. When using a combination of adhesion promoters, good lap shear strength of approximately 0.97 MPa is observed at lower temperatures.

[0129] Conclusion Adhesion promoters with a combination of SiH and Gemini silica functional groups, when used with condensation catalysts, can significantly improve adhesion, but further improvements are still needed to meet the adhesion requirements at low temperatures.

[0130] CE8: A 2.0 W / mK thermally conductive binder containing 0.25 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane binder accelerator in part B, and 0.18 wt% Ti in part A. The filler group remains a combination of Al2O3 and ZnO, with a total filler loading of 86.3 wt% (where TC is approximately 2.11 W / mK and density is approximately 2.79 g / cm³). 3 The SiH / Vi ratio is approximately 1.04. When using a combination of adhesion promoters, the lap shear strength at lower temperatures is increased to approximately 1.75 MPa.

[0131] ConclusionAdhesion promoters with a combination of SiH and Gemini silica functional groups, when used in conjunction with condensation catalysts, can significantly improve adhesion. Compared to CE7, adhesive strength increases with increasing SiH / Vi ratio. However, it still cannot meet the adhesion requirements under low-temperature curing conditions.

[0132] CE9: A 2.0 W / mK thermally conductive binder containing 0.25 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane binder accelerator in part B, and 0.18 wt% Ti in part A. The filler group remains a combination of Al2O3 and ZnO, with a total filler loading of 86.3 wt% (where TC is approximately 2.15 W / mK and density is approximately 2.79 g / cm³). 3 The SiH / Vi ratio is approximately 1.35. When using a combination of adhesion promoters, the lap shear strength at lower temperatures is increased to approximately 1.94 MPa.

[0133] Conclusion Adhesion promoters with a combination of SiH and Gemini trioxane functional groups, when used with condensation catalysts, can significantly improve adhesion. Adhesion strength is higher than CE8, and the SiH / Vi ratio is slightly higher than 1.0. However, it still cannot meet the adhesion requirements under low-temperature curing conditions.

[0134] CE10: A 2.0 W / mK thermally conductive binder containing 0.25 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane binder accelerator in part B, and 0.18 wt% Ti in part A. The filler group remains a combination of Al2O3 and ZnO, with a total filler loading of 86.3 wt% (where TC is approximately 2.17 W / mK and density is approximately 2.80 g / cm³). 3 The SiH / Vi ratio is approximately 2.04. At a higher SiH / Vi ratio, the lap shear strength at a lower temperature is approximately 1.67 MPa.

[0135] Conclusion Adhesion promoters with a combination of SiH and Gemini silica functional groups, when used in conjunction with condensation catalysts, can significantly improve adhesion. However, compared to CE 9, further increasing the SiH / Vi ratio did not significantly improve adhesive strength and still failed to meet the adhesion requirements under low-temperature curing.

[0136] CE11: A low-density thermally conductive adhesive with a density of 2.0 W / mK, comprising 0.25 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane adhesive accelerator in part B, and 0.18 wt% Ti in part A. The filler group consists of pure ATH of varying sizes, with a total filler loading of 84.13 wt% (where TC is approximately 2.03 W / mK and density is approximately 1.93 g / cm³). 3 The SiH / Vi ratio is approximately 1.03. The lap shear strength at lower temperatures is approximately 1.81 MPa.

[0137] Conclusion Adhesion promoters with a combination of SiH and Gemini trioxane functional groups, when used with condensation catalysts, can also exhibit good adhesive strength at low temperatures when using different filler systems. In pure ATH filler systems, the D+F technique can provide an adhesive strength of approximately 2 MPa, but improvements are still needed to meet the adhesive requirements under low-temperature curing.

[0138] IE1: A 2.0 W / mK thermally conductive adhesive containing 0.4 wt% SiH-functionalized silane adhesive accelerator in fraction B and 0.18 wt% Ti in fraction A. Q-branched alkenyl polymers are loaded at 1.5 wt% in both fractions A and B. The filler group is a combination of Al₂O₃ and ZnO, with a total filler loading of 86.3 wt% (where TC is approximately 2.10 W / mK and density is approximately 2.79 g / cm³). 3 The SiH / Vi ratio is approximately 1.05. The lap shear strength at lower temperatures is increased to approximately 2.54 MPa through the combination of SiH-functionalized silanes and Q-branched alkenyl polymers.

[0139] Conclusion In the presence of a Ti catalyst, by using an adhesion promoter consisting of a combination of SiH-functionalized silanes and Q-branched alkenyl polymers, the adhesive strength is improved (>2.5 MPa) compared to CE 6. It can meet the adhesion requirements under low-temperature curing conditions.

[0140] IE2: A 2.0 W / mK thermally conductive binder containing 0.4 wt% SiH functional accelerator in fraction B and 0.18 wt% Ti in fraction A. Q-branched alkenyl polymers are loaded at 3.5 wt% in both fractions A and B. The filler group is a combination of Al2O3 and ZnO, with a total filler loading of 86.3 wt% (where TC is approximately 2.11 W / mK and density is approximately 2.79 g / cm³). 3The SiH / Vi ratio was approximately 1.39. With increasing Q-branched alkenyl polymer loading and SiH / Vi ratio, the lap shear strength at lower temperatures increased to approximately 2.79 MPa.

[0141] Conclusion In the presence of a Ti catalyst, the adhesive strength is improved by increasing the loading of the Q-branched alkenyl polymer and the SiH / Vi ratio. It can meet the adhesion requirements under low-temperature curing conditions.

[0142] IE3: A 2.0 W / mK thermally conductive binder containing 0.25 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane adhesive accelerator in part B, and 0.18 wt% Ti in part A. Q-branched alkenyl polymers are loaded at 3.5 wt% in part A and 1.0 wt% in part B. The filler group is a combination of Al₂O₃ and ZnO, with a total filler loading of 86.3 wt% (where TC is approximately 2.09 W / mK and density is approximately 2.79 g / cm³). 3 The SiH / Vi ratio was approximately 1.37. With increasing Q-branched alkenyl polymer loading and SiH / Vi ratio, the lap shear strength at lower temperatures increased to approximately 2.65 MPa.

[0143] Conclusion Compared to IE2, the Q-branched alkenyl polymer decreased from 3.5 wt% to 1.0 wt% in the B fraction, and the adhesive strength decreased from 2.79 MPa to 2.65 MPa. It can still meet the adhesion requirements under low-temperature curing conditions.

[0144] IE4: A low-density thermally conductive adhesive with a density of 2.0 W / mK, comprising 0.25 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane adhesive accelerator in fraction B, and 0.18 wt% Ti in fraction A. Q-branched alkenyl polymers are loaded at 1.5 wt% in both fractions A and B. The filler group consists of pure ATH of varying sizes, with a total filler loading of 84.13 wt% (where TC is approximately 2.01 W / mK and density is approximately 1.95 g / cm³). 3 The SiH / Vi ratio is approximately 1.03. The lap shear strength increases to 2.75 MPa at lower temperatures.

[0145] Conclusion In the presence of a Ti catalyst, the adhesive strength is improved compared to CE 11 by using an adhesive promoter consisting of a combination of SiH-functionalized silanes and Q-branched alkenyl polymers. It can meet the adhesive requirements under low-temperature curing conditions.

[0146] IE5: A low-density thermally conductive adhesive with a density of 2.0 W / mK, comprising 0.25 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane adhesive accelerator in part B, and 0.18 wt% Ti in part A. Q-branched alkenyl polymers are loaded at 3.5 wt% in part A and 2.5 wt% in part B. The filler group consists of pure ATH of varying sizes, with a total filler loading of 84.13 wt% (where TC is approximately 2.05 W / mK and density is approximately 1.95 g / cm³). 3 The SiH / Vi ratio is approximately 1.02. The lap shear strength increases to 2.86 MPa at lower temperatures.

[0147] Conclusion In the presence of a Ti catalyst, the adhesive strength is improved compared to CE 11 by using an adhesive promoter consisting of a combination of SiH-functionalized silanes and Q-branched alkenyl polymers. It can meet the adhesive requirements under low-temperature curing conditions.

[0148] IE6: A low-density thermally conductive adhesive with a density of 2.0 W / mK, containing 0.5 wt% SiH-functionalized silane and 0.15 wt% bis(trimethoxysilyl)hexane adhesive accelerator in part B, and 0.18 wt% Ti in part A. Q-branched alkenyl polymers are loaded at 3.5 wt% in part A and 2.5 wt% in part B. The filler group consists of pure ATH of varying sizes, with a total filler loading of 84.13 wt% (where TC is approximately 2.02 W / mK and density is approximately 1.95 g / cm³). 3 The SiH / Vi ratio is approximately 1.36. The lap shear strength increases to 3.01 MPa at lower temperatures.

[0149] Conclusion In the presence of a Ti catalyst, the adhesive strength is improved compared to CE 11 by using an adhesive promoter consisting of a combination of SiH-functionalized silanes and Q-branched alkenyl polymers. It can meet the adhesive requirements under low-temperature curing conditions.

[0150] Conclusion

[0151] Thermal conductivity was tested using a Hot Disk thermal constant analyzer (Hot Disk TPS 2500S).

[0152] Determination of thermal conductivity

[0153] Density was tested according to ASTM D792 method.

[0154] Determination of density Determination of lap shear strength

[0155] Then, lap shear strength tests were performed according to ASTM D1002 to verify the improvement in adhesion caused by the addition of different adhesion promoters. Al Q-plates were used as the substrate. Two Al plates were firmly bonded together using different samples with dimensions of 25mm x 10mm x 1mm. After the silicone composite was fully cured at 70°C for 0.5 hours, it was left at room temperature for 1 week, fitted with fixtures, and strained at the joint using a pull-out test apparatus (Instron, ID3366Q3995, maximum power: 300VA) at a constant rate of 5mm / min until the plug of the composite detached from the substrate surface. For each test, five replicate samples were used, and the average value is given. For each embodiment, at least five samples were prepared and tested.

Claims

1. A two-part additively curable thermally conductive adhesive composition comprising: A) a vinyl-functional polysiloxane having at least two vinyl groups per molecule, B) at least one hydrosilylation catalyst, C) at least one condensation catalyst, D) at least one silyl hydride functional polysiloxane, E) at least one thermally conductive filler, F) at least one SiH functional silane, and G) at least one Q- branched alkenyl polymer.

2. The composition of claim 1, wherein the F) SiH functional silane has the following structure: H R 1 R 2 Si [OSiR 3 R 4 ] n -X-Si(OR 5 )3(II) wherein n is an integer between 1 and 10; X is a linking group selected from the group consisting of C2-C6 alkylene and O; R 1 each of R1to R5is independently C1-C6 alkyl.

3. The composition of claim 1, wherein the G) Q- branched alkenyl polymer has the following structure: (III) wherein: R is independently at each occurrence selected from a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms; R’ is independently at each occurrence selected from R and a terminally unsaturated alkenyl having 2 to 6 carbon atoms; and the average values of subscripts n1 to n4 are each greater than zero and independently selected from the range of 10 to 200; with the proviso that at least one R’ is a terminally unsaturated alkenyl having 2 to 6 carbon atoms.

4. The composition of claim 1, wherein the A) vinyl-functional polysiloxane is a linear polysiloxane having the following molecular structure (I): R x Vi (3-x) SiO-(R2SiO) d -SiR y Vi (3-y) (I) wherein R is independently at each occurrence selected from an alkyl group having 1 to 8 carbon atoms and an aryl group having 6 to 14 carbon atoms; Vi is a vinyl group (-CH=CH2); x and y indicate the average number of terminal R groups on each end of the linear polysiloxane, and each of x and y is independently selected from a number ranging from 0 to 2; (3-x) and (3-y) indicate the average number of terminal Vi groups on each end of the linear polysiloxane; and d is the average number of (R2SiO) groups in the linear polysiloxane, and is typically 10 or greater, and simultaneously 1000 or less.

5. The composition of claim 1, wherein the E) thermally conductive filler is independently a particle of a material selected from the group consisting of aluminum, copper, silver, carbon nanotubes, carbon fibers, graphene, graphite, silicon nitride, aluminum nitride, diamond, silicon carbide, silicon dioxide, aluminum oxide, aluminum trihydrate, zinc oxide, beryllium oxide, and magnesium oxide.

6. The composition of claim 1, wherein D) the silyl hydride functional polysiloxane is a linear polysiloxane having the following general molecular structure: R' 3-h H h SiO-(HRSiO) a -(R2SiO) b -SiH h’ R' 3-h’ (II) wherein R and R’ are independently at each occurrence selected from an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, and an aryl group having 6 to 14 carbon atoms; H is hydrogen, subscripts h and h’ refer to the average number of terminal hydrogens on the respective ends of the molecule, and have a value of 0, 1, 2, or 3; subscript a is the average number of (HRSiO) groups per molecule; subscript b is the average number of (R2SiO) groups per molecule, subscripts a and b are 0 to 1000, with the proviso that the subscripts a and b are not both 0, and the sum of a, h, and h’ is at least 1.

7. The composition according to claim 1, wherein the amount of the thermally conductive filler is 60% by weight or more and at the same time 95% by weight or less, based on the total weight of the composition.

8. The composition according to claim 1, wherein the ratio of SiH / alkenyl is greater than 0.

7.

9. The composition according to claim 1, wherein the composition further comprises one or more or all of the following components: an inhibitor, other adhesion promoter, pigment, filler treatment agent, moisture scavenger, and antioxidant.

10. The composition according to claim 1, wherein the amount of A) a vinyl functional polysiloxane having two vinyl groups per molecule is 5 to 30% by weight, based on the total weight of the composition, the amount of B) at least one hydrosilylation catalyst is 0.01 to 0.5% by weight, based on the total weight of the composition, the amount of C) at least one condensation catalyst is 0.01 to 0.5% by weight, based on the total weight of the composition, and the amount of D) at least one silyl hydride functional polysiloxane is 0.05 to 10% by weight, based on the total weight of the composition.

11. An article comprising a cured product formed by curing the two-part addition-curable thermally conductive adhesive composition according to any one of claims 1 to 10.

12. The article according to claim 11, wherein the article is an electronic component or electronic device.

13. Use of the composition according to any one of claims 1 to 10 in the preparation of an article.

14. The use according to claim 13, wherein the article is an electronic component or electronic device.

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