Thermally conductive composition

Abstract

Provided is a composition containing (A) an organopolysiloxane and (B) a thermal conductivity improver. The thermal conductivity improver includes: a first thermal conductivity improver having a particle size in the range of 60 to about 200 μm; a second thermal conductivity improver having a particle size in the range of 0.5 to about 30 μm; and optionally a third thermal conductivity improver having a particle size in the range of 0.01 to less than 0.5 μm.

Description

Thermally conductive composition

[0001] The present invention relates to a composition comprising an organopolysiloxane and a first thermal conductivity enhancer, a second thermal conductivity enhancer, and optionally a third thermal conductivity enhancer.

[0002] As electronic devices develop toward miniaturization and high-density integration, the heat generated by electronic devices gradually increases, and thermal failures become a major problem that impairs the performance, reliability, and lifespan of electronic devices. Therefore, efficient thermal management is crucial to solving this problem. To improve heat removal from electronic devices, thermal interface materials (TIMs) are widely used between two solid contact surfaces, i.e., a heat source and a heat sink. These materials come in various forms, such as greases, gap fillers, pre-cured gels, curable materials (one-component or two-component), phase-change materials, elastomeric pads, adhesives, thermal tapes, metal alloys, and solders. The gap between the two solid surfaces (chip and heat sink) is non-uniform or otherwise filled with air, which has low thermal conductivity. The thermal interface material fills this gap to provide a thermal conduction path. If desired, multiple thermal interface materials may be used between different solid surfaces to provide a continuous conduction path for heat removal.

[0003] The emergence of 5G communication technology in the telecommunications sector and the Internet of Things (IoT) in the consumer and industrial sectors will further increase performance demands on TIMs. 5G and IoT devices (using 5G) will operate at higher frequencies, higher device densities, higher bandwidths, lower latency, small feature sizes, and lower power, along with much higher reliability and availability requirements. These factors have made the heat removal requirements for electronic devices much more stringent, and a general trend in industry has been to move toward TIMs with higher performance, i.e., higher thermal conductivity, e.g., from low thermal conductivity of 3 to 5 W / mK to an average of 6 to 10 W / mK, and to develop even higher thermal conductivity exceeding 10 W / mK. The development of next-generation integrated circuits (ICs), three-dimensional (3D) integration, and ultra-high-speed, high-power-density communication devices is placing extremely stringent demands on thermal management.

[0004] Conventional TIMs filled with thermally conductive particles require a high volume fraction (v > 50%) of fillers such as alumina or ZnO to achieve composite thermal conductivity (TC) in the range of 1 to 5 W / mK. Many products also utilize metallic fillers such as aluminum when electrical conductivity requirements are relaxed. However, additional fillers such as BN fillers, AlN fillers, diamond fillers, SiC fillers, and combinations thereof have been disclosed in numerous patent applications to achieve high TC (> 10 W / mK). The advantage of these fillers is that they are electrically insulating and have much higher thermal conductivity (high TC fillers). In addition to thermal conductivity, TIM formulations must exhibit a variety of other important properties for use in applications. These may include low thermal resistance, low volatility, low pump-out, low bleed-out, low cracking, thermal stability, hardness, high output rate for application at a given viscosity, shear rate, pump pressure, etc. Property stability during low-high temperature cycling / impact should also be demonstrated by running tests for up to 1000 to 2000 hours. These properties are achieved by careful design of the TIM formulation, combining the appropriate polymer-resin-dispersant combination with high filler loading in the composition, as disclosed below.

[0005] Japanese Patent No. 7007161 describes a composition containing a diamond filler, in which the diamond filler has a granular shape (non-spherical, more preferably polyhedral, more preferably hexahedral, octahedral, etc., and particularly preferably hexahedral), has 10 to 18 faces, and has a sphericity of more than 0.2. The size of the diamond is 0.01 to 100 μm. The difference between the true specific gravity of the diamond and the true specific gravity of the thermal conductivity improver is 0.2 to 4 g / cm. ３The ratio of the volume average particle size of the thermal conductivity enhancer to the volume average particle size of the diamond is 0.01 to 0.5. The overall thermal conductivity shown is low, <10 W / mK. Japanese Patent No. 7084143 describes a heat dissipation composition, a heat dissipation member, and a filler aggregate for a heat dissipation member. The composition contains diamond (more than 15 volume % diamond) along with multiple fillers exhibiting a thermal conductivity greater than 10 W. It also mentions a total void volume (<3%), a contact angle (<70°) of the polymer matrix to the thermally conductive filler containing diamond particles, and a surface oxygen content (>5%) of the diamond particles. Japanese Patent No. 2938428 describes a heat-reducing grease containing diamond and liquid silicone in combination with a thermally conductive inorganic filler such as AlN, having a consistency ranging from 280 to 350 and a thermal conductivity ranging from 2.5 to 4 W / mK. Chinese Patent No. 112226199 describes an insulating composition of ultra-high thermal conductivity curable paste, which contains thermally conductive fillers such as diamond and functional fillers such as ferric oxide, and has a thermal conductivity of 11.8 W / mK and a throughput of 33 g per minute.

[0006] However, these proposed solutions do not address the need for thermally conductive compositions that have a combination of desirable attributes through the use of a combination of thermally conductive fillers.

[0007] The present invention provides a composition comprising a mixture of a polymer and a thermally conductive filler, where the loading of the thermally conductive filler in the composition provides a composition with high thermal conductivity while maintaining good dispensability and meeting all other relevant CTQs (critical to quality characteristics), such as low pump-out, low bleed-out, cracking, low hardness increase, and reliability during low-temperature-high-temperature cycling / shock (-40°C to 150°C) for up to 500 to 1000 hours. The present invention incorporates diamond as the primary filler in the thermally conductive composition. It is shown herein that diamond combined with alumina, AlN, BN, SiC, and ZnO fillers forms an ideal combination in conjunction with silicone polymers and resins to achieve thermal conductivities exceeding 12 W / mK with consistent dispensing volumes and outstanding thermal stability. All of these compositions are electrically non-conductive.

[0008] The following presents a summary of the disclosure to provide a basic understanding of some aspects of the present invention. This summary is not intended to identify key or critical elements, nor is it intended to define any limitations on the scope of the embodiments or claims. Moreover, this summary may provide a simplified overview of some aspects that may be described in more detail in other parts of the disclosure.

[0009] In one embodiment, provided is: (A) an organopolysiloxane comprising: (i) an alkenyl-functionalized diorganopolysiloxane M of formula (Ia): １ ａ M ２ ｂ D １ ｃ D ２ ｄ T １ ｅ T ２ ｆ Q ｇ (Ia) [wherein, M １ =R １ R ２ R ３ SiO １／２ M ２ =R ４ R５ R ６ SiO １／２ D １ =R ７ R ８ SiO ２／２ D ２ =R ９ R １０ SiO ２／２ T １ =R １１ SiO ３／２ T ２ =R １２ SiO ３／２ Q = SiO ４／２ where R ２ , R ３ , R ４ , R ５ , R ６ , R ８ , R ９ , R １０ , R １２ are each independently selected from monovalent aliphatic, aromatic and fluorohydrocarbon groups or alkoxy groups having from 1 to 60 carbon atoms; R １ , R ７ , R １１ are each independently selected from monovalent aliphatic, aromatic, or fluorohydrocarbon radicals having from 1 to 60 carbon atoms and containing at least one terminal olefinic bond; and the subscripts a, b, c, d, e, f, and g are 0 or positive integers, subject to the limitations that 1≦a+b+c+d+e+f+g≦6000 and a+c+e≧1; and (ii) a hydrogen-functionalized organopolysiloxane M of formula (Ib): １ ａ′ M ２ ｂ′ D １ ｃ′ D ２ ｄ′ T １ ｅ′ T ２ ｆ′ Q ｇ′ (1b) [wherein, M １ =R １３ R １４ R １５ SiO １／２ M ２=R １６ R １７ R １８ SiO １／２ D １ =R １９ R ２０ SiO ２／２ D ２ =R ２１ R ２２ SiO ２／２ T １ =R ２３ SiO ３／２ T ２ =R ２４ SiO ３／２ Q = SiO ４／２ where R １４ , R １５ , R １６ , R １７ , R １８ , R ２０ , R ２１ , R ２２ , R ２４ is a monovalent aliphatic, aromatic or fluorohydrocarbon radical having 1 to 60 carbon atoms; R １３ , R １９ , R ２３ is hydrogen; and the subscripts a', b', c', d', e', f', and g' are 0 or positive integers, subject to the limitations that 1≦a'+b'+c'+d'+e'+f'+g'≦6000 and a'+c'+e'≧1, including those in which a+c+e>1 when a'+c'+e'=1, and a'+c'+e'>1 when a+c+e=1; or an organopolysiloxane comprising the crosslinked product of (i) and (ii); and (B) a first thermal conductivity enhancer having a particle size in the range of 60 to about 200 μm, a second thermal conductivity enhancer having a particle size in the range of 0.5 to about 30 μm, and a third thermal conductivity enhancer having a particle size in the range of 0.01 to less than 0.5 μm. As used herein, "particle size" refers to the volume average particle size unless the context indicates otherwise.

[0010] In one embodiment, the composition comprises a dispersant represented by formula (II): [In the formula, R ２５is a group having an alkoxysilyl group having 1 to 4 carbon atoms, R ２６ is a linear organosiloxy group (III), [In the formula, each R ２８ are independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, L is selected from monovalent hydrocarbon groups having 1 to 6 carbon atoms and alkoxysilyl groups having 1 to 4 carbon atoms, and k is an integer from 10 to 500; each X is independently a divalent hydrocarbon group having 2 to 10 carbon atoms, each of h and i is independently 1 or a greater integer, j is 0 or a greater integer, and h + i + j is 4 or a greater integer, and each R ２７ are independently selected from hydrogen and monovalent hydrocarbon groups having 1 to 6 carbon atoms; or a group of formula (IV): [In the formula, R ２９ represents an unsubstituted or substituted alkyl group, alkenyl group, or aryl group, and each R ３０ each independently represents an unsubstituted or substituted alkyl group, alkenyl group, or aryl group; R ３１ and R ３２ each represents the same or different unsubstituted or substituted monovalent hydrocarbon group, and each R ３３ each independently represents a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, and each R ３４ each independently represents an unsubstituted or substituted alkyl group, alkoxyalkyl group, alkenyl group, or acyl group, and n represents an integer of 2 to 20.

[0011] In another embodiment, the dispersant comprises two or more hydrolyzable organopolysiloxane compounds of formula (II).

[0012] In yet another embodiment, the dispersant comprises a first hydrolyzable organopolysiloxane represented by formula (II) and having a value of k ranging from 10 to 50, and a second hydrolyzable organopolysiloxane represented by formula (II) and having a value of k ranging from 100 to 500.

[0013] In one embodiment, the organopolysiloxane has an H / Vi ratio greater than 0.4.

[0014] In yet another embodiment, the composition comprises a first thermal conductivity enhancer in an amount of about 15 wt % to about 50 wt %, based on the total weight of the composition, and the first thermal conductivity enhancer has an average particle size ranging from 60 to about 200 μm, preferably 100 to 170 μm.

[0015] In another embodiment, the first thermal conductivity enhancer is diamond.

[0016] In another embodiment, the diamond has a surface oxygen content greater than 10%.

[0017] In another embodiment, the composition comprises a second thermal conductivity enhancer in an amount of about 20 wt % to about 50 wt %, based on the total weight of the composition.

[0018] In another embodiment, the second thermal conductivity enhancer is aluminum nitride.

[0019] In another embodiment, the second thermal conductivity enhancer is present in a first average particle size ranging from 0.5 μm to less than 2 μm, a second average particle size ranging from 2 μm to less than 10 μm, and a third average particle size ranging from 10 μm to about 30 μm.

[0020] In another embodiment, the second thermal conductivity enhancer having a first average particle size is present in an amount of about 5 wt % to about 25 wt % based on the total weight of the composition, the second thermal conductivity enhancer having a second average particle size is present in an amount of about 3 wt % to about 10 wt % based on the total weight of the composition, and the second thermal conductivity filler having a third average particle size is present in an amount of about 5 wt % to about 25 wt % based on the total weight of the composition.

[0021] In yet another embodiment, the third thermal conductivity enhancer is present in an amount from about 1 wt % to about 10 wt %, based on the total weight of the composition.

[0022] In another embodiment, the third thermal conductivity enhancer is zinc oxide having a particle size ranging from 0.01 to less than 0.5 μm.

[0023] In another aspect, provided is a device comprising a first substrate, a second substrate, and a thermal interface material bridging an interfacial gap between the first and second substrates, the interface material comprising the one-component thermally conductive gel composition of any of the previous embodiments.

[0024] In another aspect, the present invention provides a thermally conductive material comprising the composition of the present invention.

[0025] In another aspect, the present invention provides a method of dissipating heat from a substrate, the method comprising contacting the substrate with a composition of the present invention.

[0026] In yet another aspect, the present invention provides a method of making a treated substrate comprising applying a composition of the present invention to a surface of a substrate.

[0027] In a further aspect, the present invention provides a device comprising a treated substrate, wherein the treated substrate comprises a composition of the present invention.

[0028] The following description and drawings disclose various exemplary embodiments. Some improvements and novel aspects may be explicitly identified, while others may be apparent from the description and drawings. Figure 1 is a photograph showing vertical stability data obtained for the composition of Example 13.

[0029] Reference will now be made to exemplary embodiments, examples of which are illustrated in the accompanying drawings. It should be understood that other embodiments may be utilized and that structural and functional changes may be made. Furthermore, features of various embodiments may be combined or substituted. Thus, the following description is presented by way of example only and is not intended to limit in any way the various alternatives and modifications that may be made to the exemplary embodiments. In this disclosure, numerous specific details are provided to provide a thorough understanding of the subject disclosure. It should be understood that aspects of the present disclosure may be implemented using other embodiments that do not necessarily include all of the aspects set forth herein.

[0030] As used herein, the words "example" and "exemplary" mean an instance or illustration. The words "example" or "exemplary" do not indicate a primary or preferred aspect or embodiment. The word "or" is intended to be inclusive rather than exclusive, unless the context suggests otherwise. As an example, the phrase "A uses B or C" includes any inclusive permutation (e.g., A uses B, A uses C, or A uses both B and C). As a separate matter, the articles "a" and "an" are generally intended to mean "one or more," unless the context suggests otherwise.

[0031] As used herein, the term "thermal conductivity enhancer" refers to a solid compound or mixture of compounds that enhances the thermal conductivity of a composition. Examples of thermal conductivity enhancers include, but are not limited to, solid inorganic compounds or mixtures thereof, such as boron nitride, aluminum nitride, aluminum oxide, zinc oxide, aluminum metal, silicon carbide, carbon-based fillers such as graphite and diamond, and metal fillers such as aluminum and silver.

[0032] As used herein, the terms "precured gel" or "crosslinked silicone gel" refer to a fluid-extended polymer system that may contain a continuous polymer phase or network, which may be chemically or physically crosslinked, for example, by ionic or covalent bonds, and an oil, such as a silicone or other oil, a plasticizer, unreacted monomer, or other fluid extender that fills the interstices of the network by swelling or otherwise. The crosslink density and extender proportion of such a network can be controlled to adjust the modulus, i.e., softness, and other properties of the gel. The term "precured gel" should also be understood to encompass materials that may be broadly classified as pseudogels or gel-like substances, which have a "loose" crosslinked network formed by relatively long crosslinked chains, but which otherwise have viscoelastic properties similar to gels, for example, by not having a fluid extender.

[0033] The term "monovalent hydrocarbon" refers to any hydrocarbon group from which one or more hydrogen atoms have been removed, and includes alkyl, alkenyl, alkynyl, cyclic alkyl, cyclic alkenyl, cyclic alkynyl, aryl, aralkyl, and allenyl, and may contain heteroatoms.

[0034] The term "alkyl" means any monovalent saturated linear, branched, or cyclic hydrocarbon group; the term "alkenyl" means any monovalent linear, branched, or cyclic hydrocarbon group containing one or more carbon-carbon double bonds, where the point of attachment of the group may be at the carbon-carbon double bond or elsewhere therein; and the term "alkynyl" means any monovalent linear, branched, or cyclic hydrocarbon group containing one or more carbon-carbon triple bonds and optionally one or more carbon-carbon double bonds, where the point of attachment of the group may be at the carbon-carbon triple bond, the carbon-carbon double bond, or elsewhere therein. Examples of alkyl include methyl, ethyl, propyl, and isobutyl. Examples of alkenyl include vinyl, propenyl, allyl, methallyl, ethylidenylnorbornane, ethylidenenorbornyl, ethylidenylnorbornene, and ethylidenenorbornenyl. Examples of alkynyl include acetylenyl, propargyl, and methylacetylenyl.

[0035] The terms "cyclic alkyl," "cyclic alkenyl," and "cyclic alkynyl" include bicyclic, tricyclic, and higher polycyclic structures, as well as those cyclic structures which are further substituted with alkyl, alkenyl, and / or alkynyl groups. Representative examples include norbornyl, norbornenyl, ethylnorbornyl, ethylnorbornenyl, cyclohexyl, ethylcyclohexyl, ethylcyclohexenyl, cyclohexylcyclohexyl, and cyclododecatrienyl.

[0036] The term "aryl" means any monovalent aromatic hydrocarbon group; the term "aralkyl" means any alkyl group (as defined herein) in which one or more hydrogen atoms are replaced by an equal number of identical and / or different aryl (as defined herein) groups; and the term "allenyl" means any aryl group (as defined herein) in which one or more hydrogen atoms are replaced by an equal number of identical and / or different alkyl groups (as defined herein). Examples of aryl include phenyl and naphthalenyl. Examples of aralkyl include benzyl and phenethyl. Examples of allenyl include tolyl and xylyl.

[0037] The present disclosure provides one-component grease compositions, reworkable pre-cured thermally conductive gel compositions, and two-component post-cured compositions, each consisting of a crosslinked silicone gel, an alkenyl-functionalized diorganopolysiloxane fluid, a hydrogen-functionalized organopolysiloxane, an alkoxy-functionalized surface wetting agent (dispersant) or a hydrolyzable organopolysiloxane, a thermally conductive filler, additives, and pigments. Ultra-high thermal conductivity was achieved by using dispersants and organo-functionalized silicone fluids in conjunction with diamond and other thermally conductive fillers. Although these thermally conductive compositions consisted of diamond and hard fillers such as AlN fillers, they demonstrated very stable long-term discharge rates and outstanding thermal stability at very high temperatures (150°C) for over 1,000 hours, based on optimization of not only the filler and filler ratio, but also the compositional optimization of the organo-functionalized silicone fluid and dispersant.

[0038] The one-component pre-cured thermally conductive gel composition achieved a discharge rate of more than 14 g per minute and a thermal conductivity of more than 14 W / mK, and the hardness (Shore E) was within 10 at 150°C even after aging for 1000 hours, demonstrating stable dischargeability.

[0039] The two-component, post-cured (addition curable) thermally conductive composition achieved thermal conductivities of over 17 W / mK with output rates of over 14 g / min, exhibited less hardness increase at temperatures as high as 150°C, and showed stable output rates after aging.

[0040] The one-component grease composition also comprises additives. The additives used in this disclosure may be selected from one or a combination of two or more of the following: pigments, lubricants, viscosity modifiers, heat stabilizers, light stabilizers, antioxidants, flame retardants, inhibitors, adhesion promoters.

[0041] Thermal conductivities of over 12 W / mK have been achieved with one-component grease compositions, along with output rates of over 19 g / min.

[0042] Filler combinations are optimized to arrive at the best possible combination that provides a high TC and highly ejectable composition. Therefore, while any two, three, or more fillers can be combined to obtain a composition, it should be noted that such an approach is rarely successful and results in powdery or low TC compositions. Only after experimental design and optimization can an optimal filler combination be obtained that improves filler packing, thus providing high thermal conductivity while maintaining paste-like rheology, viscosity, and flow properties. Filler combinations can be described as consisting of three or more fillers—(C-I) being the smallest fillers with a D50 of 0.01 to less than 0.5 μm, which may consist of alumina, ZnO, SiC, diamond, BN, and / or aluminum nitride fillers, or combinations thereof—which, despite their large surface area, improve the overall TC by providing multiple filler-polymer-dispersant contacts, along with filler-filler and filler-substrate contacts. They can also provide the desired lubrication and thixotropy effects for the composition. The next filler (C-II) is an intermediate size filler of 0.5 to 30 μm, which provides improved contact and gap filling between larger fillers. These fillers consist of alumina, diamond, BN, or aluminum nitride powder, or combinations thereof. The third filler (C-III) is the largest filler type (>60 to 200 μm), which provides the largest crystalline domain size and provides a high thermal conductivity path, i.e., improved thermal conductivity. The largest fillers utilize materials with inherently high TC, such as BN, cubic BN, SiC, diamond, and AlN, which improve the overall conductivity of the composition. Careful experimental studies have revealed excellent thermal conductivity (>12 W / mK), throughput (>12 g / min), electrical insulation (volume resistivity >1×10 １０In order to achieve a thermally conductive composition that is flexible and moldable, has a low-cost and easily manufacturable resistance (Ω-cm), specific fillers and combinations of fillers are demonstrated herein for use as thermally conductive fillers, and the present invention has been completed.

[0043] Herein, optimization of the organofunctionalized silicone fluids (organosilicone hydrides, vinylorganosilicones, pre-cured silicone gels) along with filler optimization (single crystal diamond in combination with other fillers) and dispersants were performed to achieve ultra-high thermal conductivity combined with good and consistent discharge and good thermal stability.

[0044] The present disclosure may specify many different ranges for one or more components in the composition, and it will be understood that the numerical values ​​in each range can be combined to form new unspecified ranges.

[0045] In one embodiment, the present invention provides an organopolysiloxane comprising: (A) an organopolysiloxane comprising: (i) an alkenyl-functionalized diorganopolysiloxane M of formula (Ia): １ ａ M ２ ｂ D １ ｃ D ２ ｄ T １ ｅ T ２ ｆ Q ｇ (Ia) [wherein, M １ =R １ R ２ R ３ SiO １／２ M ２ =R ４ R ５ R ６ SiO １／２ D １ =R ７ R ８ SiO ２／２ D ２ =R ９ R １０ SiO ２／２ T １ =R １１ SiO３／２ T ２ =R １２ SiO ３／２ Q = SiO ４／２ where R ２ , R ３ , R ４ , R ５ , R ６ , R ８ , R ９ , R １０ , R １２ are each independently selected from monovalent aliphatic, aromatic and fluorohydrocarbon groups or alkoxy groups having from 1 to 60 carbon atoms; R １ , R ７ , R １１ are each independently selected from monovalent aliphatic, aromatic, or fluorohydrocarbon radicals having from 1 to 60 carbon atoms and containing at least one terminal olefinic bond; and the subscripts a, b, c, d, e, f, and g are 0 or positive integers, subject to the limitations that 1≦a+b+c+d+e+f+g≦6000 and a+c+e≧1; and (ii) a hydrogen-functionalized organopolysiloxane M of formula (Ib): １ ａ′ M ２ ｂ′ D １ ｃ′ D ２ ｄ′ T １ ｅ′ T ２ ｆ′ Q ｇ′ (1b) [wherein, M １ =R １３ R １４ R １５ SiO １／２ M ２ =R １６ R １７ R １８ SiO １／２ D １ =R １９ R ２０ SiO ２／２ D ２ =R ２１ R ２２ SiO ２／２ T １ =R ２３ SiO３／２ T ２ =R ２４ SiO ３／２ Q = SiO ４／２ where R １４ , R １５ , R １６ , R １７ , R １８ , R ２０ , R ２１ , R ２２ , R ２４ is a monovalent aliphatic, aromatic or fluorohydrocarbon radical having 1 to 60 carbon atoms; R １３ , R １９ , R ２３is hydrogen; and the subscripts a', b', c', d', e', f', and g' are 0 or positive integers, subject to the limitations that 1≦a'+b'+c'+d'+e'+f'+g'≦6000 and a'+c'+e'≧1, including those in which a+c+e>1 when a'+c'+e'=1, and a'+c'+e'>1 when a+c+e=1; or an organopolysiloxane comprising the crosslinked product of (i) and (ii); and (B) a first thermal conductivity enhancer having a particle size in the range of 60 to about 200 μm, a second thermal conductivity enhancer having a particle size in the range of 0.5 to about 30 μm, and a third thermal conductivity enhancer having a particle size in the range of 0.01 to less than about 0.5 μm. Component (i) is an organopolysiloxane represented by formula (Ia) and contains at least two alkenyl groups bonded to silicon atoms per molecule. The viscosity of component (i) at 25°C may range from 0.01 to 10 Pa·s, preferably from 0.06 to 1 Pa·s. A viscosity of less than 0.01 Pa·s at 25°C results in poor storage stability of the composition, while a viscosity of more than 10 Pa·s results in insufficient flowability. The viscosities described above and elsewhere in this application are measured using a Brookfield rotational viscometer. Such organopolysiloxanes are not particularly limited as long as they satisfy the above-mentioned viscosity and alkenyl group content requirements, and known organopolysiloxanes can be used. The molecular structure of the organopolysiloxane may be, for example, linear, branched, partially branched, or dendrimeric. The molecular structure is preferably linear or partially branched. Component (i) may be a single polymer having this structure, a copolymer having this structure, or a mixture of two or more organopolysiloxanes having different viscosities. Component (i) may also be used in combination with a monoalkenyl-terminated organopolysiloxane having one silicon-bonded alkenyl group per molecule. The viscosity of this organopolysiloxane at 25°C may be in the range of 0.001 to 1 Pa·s, preferably 0.006 to 0.1 Pa·s.By using this polyorganosiloxane in combination with component (i), i.e., an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule, improved fluidity is achieved, and the cured product is more likely to achieve the low hardness required for a thermal interface material. Component (ii) is an organohydrogenpolysiloxane represented by formula (1b) and has hydrogen atoms directly bonded to silicon atoms. That is, it is an organohydrogenpolysiloxane having at least two hydrogen atoms (hydrosilyl groups) directly bonded to silicon atoms per molecule, and acts as a crosslinker for component (i). The hydrosilyl groups in component (ii) and the alkenyl groups in component (i) are added via a hydrosilylation reaction promoted by a platinum group metal curing catalyst, as described below, to form a three-dimensional network structure with a crosslinked structure. If the number of hydrosilyl groups in component (ii) is less than two, curing is not achieved. The amount of component (ii) added is an amount such that the number of hydrosilyl groups in component (ii) is 0.1 to 5.0 moles per mole of alkenyl groups in component (i), i.e., an amount such that the number of moles of hydrogen atoms directly bonded to silicon atoms is 0.1 to 5.0 times the number of moles of alkenyl groups in component (i), preferably 0.2 to 2.0 moles, and more preferably 0.3 to 1.0 moles. If the amount of hydrosilyl groups in component (ii) is less than 0.1 mole per mole of alkenyl groups in component (i), curing may not be achieved, or the strength of the cured product may be insufficient to handle as a molded product. On the other hand, if the amount exceeds 5.0 moles, the cured product loses flexibility and becomes brittle.

[0046] In one embodiment, the composition further comprises a dispersant represented by formula (II): [In the formula, R ２５ is a group having an alkoxysilyl group having 1 to 4 carbon atoms, R ２６ is a linear organosiloxy group (III), [In the formula, each R ２８are independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, L is selected from monovalent hydrocarbon groups having 1 to 6 carbon atoms and alkoxysilyl groups having 1 to 4 carbon atoms, and k is an integer from 10 to 500; each X is independently a divalent hydrocarbon group having 2 to 10 carbon atoms, each of h and i is independently 1 or a greater integer, j is 0 or a greater integer, and h + i + j is 4 or a greater integer, and each R ２７ are independently selected from hydrogen and monovalent hydrocarbon groups having 1 to 6 carbon atoms; or a group of formula (IV): [In the formula, R ２９ represents an unsubstituted or substituted alkyl group, alkenyl group, or aryl group, and each R ３０ each independently represents an unsubstituted or substituted alkyl group, alkenyl group, or aryl group; R ３１ and R ３２ each represents the same or different unsubstituted or substituted monovalent hydrocarbon group, and each R ３３ each independently represents a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, and each R ３４ each independently represents an unsubstituted or substituted alkyl group, alkoxyalkyl group, alkenyl group, or acyl group, and n represents an integer of 2 to 20.

[0047] In another embodiment, the dispersant comprises two or more hydrolyzable organopolysiloxane compounds of formula (II).

[0048] In yet another embodiment, the dispersant comprises a first hydrolyzable organopolysiloxane represented by formula (III) and having a value of k ranging from 10 to 50, and a second hydrolyzable organopolysiloxane represented by formula (III) and having a value of k ranging from 100 to 500.

[0049] In one embodiment, the organopolysiloxane has an H / Vi ratio greater than 0.4.

[0050] In yet another embodiment, the composition comprises the first thermal conductivity enhancer in an amount from about 15 wt % to about 50 wt %, based on the total weight of the composition.

[0051] In another embodiment, the first thermal conductivity enhancer is diamond.

[0052] In another embodiment, the diamond has a surface oxygen content greater than 10%.

[0053] In another embodiment, the composition comprises a second thermal conductivity enhancer in an amount of about 20 wt % to about 50 wt %, based on the total weight of the composition.

[0054] In another embodiment, the second thermal conductivity enhancer is aluminum nitride.

[0055] In another embodiment, the second thermal conductivity enhancer is present in a first average particle size ranging from 0.5 μm to less than 2 μm, a second average particle size ranging from 2 μm to less than 10 μm, and a third average particle size ranging from 10 μm to about 30 μm.

[0056] In another embodiment, the second thermal conductivity enhancer having a first average particle size is present in an amount of about 5 wt % to about 25 wt % based on the total weight of the composition, the second thermal conductivity enhancer having a second average particle size is present in an amount of about 3 wt % to about 10 wt % based on the total weight of the composition, and the second thermal conductivity enhancer having a third average particle size is present in an amount of about 5 wt % to about 25 wt % based on the total weight of the composition.

[0057] In yet another embodiment, the third thermal conductivity enhancer is present in an amount from about 1 wt % to about 10 wt %, based on the total weight of the composition.

[0058] In another embodiment, the third thermal conductivity enhancer is zinc oxide having a particle size in the range of 0.01 to 0.5 μm.

[0059] In another aspect, there is provided a device comprising a first substrate, a second substrate, and a thermal interface material bridging an interfacial gap between the first and second substrates, wherein the interface material comprises the one-component thermally conductive gel composition of any of the previous embodiments.

[0060] In another aspect, the present invention provides a thermally conductive material comprising the composition of the present invention.

[0061] In another aspect, the present invention provides a method of dissipating heat from a substrate, the method comprising contacting the substrate with a composition of the present invention.

[0062] In yet another aspect, the present invention provides a method of making a treated substrate comprising applying a composition of the present invention to a surface of a substrate.

[0063] In a further aspect, the present invention provides a device comprising a treated substrate, wherein the treated substrate comprises a composition of the present invention.

[0064] It will be understood that the thermal conductivity enhancer may include a mixture of compounds of a single type, and that the mixture may include compounds of different average particle sizes. In one embodiment, the thermal conductivity enhancer includes aluminum nitride, boron nitride, SiC, and aluminum oxide.

[0065] The particle size of the thermal conductivity enhancer can be selected as desired for a particular purpose or intended use. It will be understood that a composition can include a combination of thermal conductivity enhancers with different average particle sizes. Such a combination can be selected as desired for a particular purpose or intended use. In one embodiment, the composition includes a first thermal conductivity enhancer having an average particle size of about 60 μm to about 200 μm, a second thermal conductivity enhancer having an average particle size of about 0.5 μm to about 30 μm, and optionally a third thermal conductivity enhancer having an average particle size of about 0.01 μm to less than about 0.5 μm. The first, second, and third thermal conductivity enhancers may have the same or different filler chemical makeup. The particle size can be determined by any suitable method. Average particle size is often provided or reported by the material supplier. Average particle size can be determined by measuring particle size distribution using a laser diffraction / scattering method in accordance with JIS R1629. In this study, the volume-based median diameter (D50) obtained by measurement was used as the average particle size.

[0066] The filler(s) may be present in an amount of about 80% to about 99%, about 82% to about 96%, or about 85% to about 95% by weight, based on the total weight of the composition.

[0067] Crosslinked silicone gels may also be referred to herein as precured gels or polymer gels. Crosslinked silicone gels are made by reacting an alkenyl-functionalized diorganopolysiloxane with a hydrogen-functionalized organopolysiloxane. This reaction can be carried out under hydrosilylation reaction conditions using an appropriate catalyst. Common hydrosilylation catalysts are platinum-based catalysts (e.g., but not limited to, Karstedt's catalyst). In one embodiment, precured gels can be made by reacting a linear vinyl-end-capped polysiloxane with a pendant poly(hydrosiloxane) or poly(methylhydrosiloxane) copolymer (crosslinker) or a crosslinked MT or MQ resin containing Si—H reactive groups via a Pt-catalyzed hydrosilylation reaction. Similar gel networks can also be achieved by reacting pendant vinyl silicone polymers with end-capped hydrosiloxyl-group-containing poly(hydrosiloxane) or poly(methylhydrosiloxane) copolymers or crosslinked MT or MQ resins containing Si—H reactive groups via a Pt-catalyzed hydrosilylation route. The effective Si—H / Si-alkenyl molar ratio [r] reacted to form Si—C bonds must satisfy r≦0.3. The final "gel rheology" must satisfy the following conditions: a) 0.2≦G′≦1000 (Pa) b) 0.1≦G″ / G′≦10 Here, the term G′ represents the “storage shear modulus” of the final pre-cured gel composition used in the thermal interface material composition, measured at T=25°C under an oscillation frequency of 1 Hz or 6.28 rad / s using a stress or strain controlled rheometer, and the term G″ represents the “loss shear modulus” of the final pre-cured gel composition used in the thermal interface material composition, measured at T=25°C under an oscillation frequency of 1 Hz or 6.28 rad / s using a stress or strain controlled rheometer. G″ and G′ are measured together in their respective viscoelastic regions.

[0068] The following examples are intended to illustrate aspects and embodiments of the present technology. All parts and percentages are by weight and all temperatures are in degrees Celsius unless expressly stated otherwise. All patents, other publications and U.S. patent applications referenced in this application are hereby incorporated by reference in their entirety.

[0069] Example

[0070] Steady shear viscosity and thixotropy were determined using a TA Instruments rheometer (DHR-3) using parallel plate geometry (measurement geometry gap 300 μm).

[0071] Hardness Test: The hardness of the gel was measured using an ASTM D2240 type durometer (Shore E) and a penetrometer ASTM D-217 (penetration range: 0 to 400 Pen to 40 mm; penetration time: 5 seconds).

[0072] The pre-cured (one-part) and post-cured (two-part) compositions were hardness tested using an ASTM D2240 type durometer (Shore E).

[0073] The bulk thermal conductivity of the thermally conductive compositions was measured at 22°C using a hot disk apparatus, and the thermal resistance and thermal conductivity were measured using ASTM D5470.

[0074] The sample was filled into a 30 cc syringe with a 2 mm opening, called EFD Optimum, and dispensed at 90 psi using a Nordson EFD automatic dispenser, and the dispensed volume per minute was measured to determine the dispensed amount.

[0075] The composition was sandwiched between two Si chips of 10 x 10 x 0.5 mm, and a pressure of 1 MPa was applied for 30 seconds, and the bond line thickness (BLT) was determined.

[0076] The volume resistivity was measured by a test method conforming to ASTM D257, and the dielectric strength was measured by a test method conforming to ASTM D149.

[0077] Vertical sliding tests (vertical stability performance) were performed by placing 2 grams of the composition in a circle between an aluminum / alumina Q panel and a glass plate measuring 5 cm x 5 cm, using spacers of 0.5 mm, 1 mm, and 2 mm. The plates were clamped together with paper clips, placed in a vertical position, and subjected to temperature cycling or shock (-40 to 150°C).

[0078] The crystallite size was measured by XRD using an X-ray diffractometer with a copper target (Kα radiation) of 1.54 Å wavelength, an acceleration voltage of 40 kV, a tube current of 30 mA, a scan rate of 4° per minute, and a step width of 0.02°.

[0079] The surface oxygen content was measured using an Al Kα radiation source at a vacuum level of 2×10 －９ Torr, hemispherical analyzer, dwell time 0.7 seconds, energy step 1 eV and HR scan 0.1 eV were measured by XPS using an X-ray photoelectron spectrometer.

[0080] Precured gel compositions were prepared using a Thinky mixer. First, specific amounts of dispersant, vinyl PDMS fluid, and gel were weighed into a plastic container and mixed at 2000 rpm for 30 seconds. Fillers of various particle sizes were added to this mixture in stages, and all materials were mixed using the Thinky mixer at 2000 rpm for 30 seconds each time. After each 30-second mixing, the composition was hand-mixed for 2 minutes using a broad-blade spatula. Finally, one or two 30-second mixes were performed at 2000 rpm to obtain a uniform paste.

[0081] The two-component curable composition was prepared in the same manner as the pre-cured gel composition. Equal amounts of component A and component B were prepared separately, mixed, and cured at 70° C. for 1 hour.

[0082] Thermally conductive grease-type compositions were prepared according to Examples 1 to 12 using irregular polycrystalline diamond, single crystal diamond fillers and other thermally conductive fillers.

[0083] Two-part addition-curable compositions were prepared according to Examples 13-17.

[0084] Thermally conductive pre-cured gel compositions were prepared according to Examples 18 to 22.

[0085] Tables 1 and 2 show the properties of the thermally conductive grease compositions.

[0086] Table 3 shows the properties of the two-part addition-curable compositions.

[0087] Table 4 shows the properties of the thermally conductive pre-cured gel compositions.

[0088] The divinyl-terminated organopolysiloxane (A-1a) has a viscosity of 0.1 Pa·s and is represented by the following formula: wherein each X is vinyl and n is 42. The divinyl-terminated organopolysiloxane (A-1b) has a viscosity of 0.03 Pa·s and is represented by the following formula: wherein each X is vinyl and n is 20.

[0089] The monovinyl-terminated organopolysiloxane (A-2a) has a viscosity of 0.02 Pa·s and is represented by the following formula: In the formula, X is vinyl and m is 30. The monovinyl-terminated organopolysiloxane (A-2b) has a viscosity of 0.01 Pa·s and is represented by the following formula: wherein X is vinyl and m is 20.

[0090] The crosslinker organohydrogenpolysiloxane (B-1) has a viscosity range of 0.01 to 0.1 Pa·s with an Si—H content of 0.05 to 0.5 wt %, and a compound of the following formula having a viscosity of 0.02 Pa·s was used in the examples:

[0091] Irregular polycrystalline diamond was purchased from either HongXiang or Hexanovation.

[0092] Aluminum nitride was purchased from Toyo Aluminum Co., Ltd.

[0093] Nano zinc oxide was obtained from Zochem.

[0094] Irregular polycrystalline diamond (C-1) with a volume average particle size of 0.57 μm, a crystallite size of 306 Å, and a surface oxygen content of 10.9%

[0095] Irregular polycrystalline diamond (C-2) with a volume average particle size of 5.2 μm, a crystallite size of 428 Å, and a surface oxygen content of 8.1%

[0096] Irregular polycrystalline diamond (C-3) with a volume average particle size of 83.5 μm and a surface oxygen content of 8.6%

[0097] Irregular polycrystalline diamond (C-4) with a volume average particle size of 89 μm, a crystallite size of 1070 Å, and a surface oxygen content of 6.9%.

[0098] Irregular polycrystalline diamond (C-5) with a volume average particle size of 115 μm, a crystallite size of 1097 Å, and a surface oxygen content of 10.1%.

[0099] Single crystal diamond (C-6) with a volume average particle size of 165 μm, a crystallite size of 1206 Å, and a surface oxygen content of 13.5%

[0100] Single crystal diamond (C-7) with a volume average particle size of 125 μm

[0101] Single crystal diamond (C-7a) with a volume average particle size of 107 μm, a crystallite size of 905 Å, and a surface oxygen content of 16.7%

[0102] Alumina nitride having a volume average particle size of 1.2, 5, 20, and 70 μm (C-8a, C-8b, C-8c, and C-8d, respectively)

[0103] Nano zinc oxide (C-9) with a volume average particle size of 0.16 μm

[0104] (D-1) is a hydrolyzable organopolysiloxane (II-i) represented by the compound of the following formula:

[0105] (D-2) is a hydrolyzable polyorganosiloxane represented by the compound of formula (II-ii).

[0106] E-1 is an additive in the composition.

[0107] Example 1: Polysiloxanes A-1a (0.06 g) and A-2a (0.9 g) and hydrolyzable polysiloxane D-1 (0.61 g) were weighed into a plastic container and mixed for 30 seconds at 2000 rpm using a Thinky mixer. To this mixture, thermally conductive fillers C-4 (16 g), C-8a (8 g), and C-8c (8 g) were added stepwise, with each step requiring 30 seconds at 2000 rpm to mix all ingredients. After each 30-second mixing period, the composition was hand-mixed for 2 minutes using a broad-blade spatula. The mixture was further mixed for an additional 30 seconds at 2000 rpm using the Thinky mixer. After mixing, the composition was degassed at room temperature to remove any trapped air. The total weight of the composition was 33.6 g.

[0108] Example 2 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.08 g), hydrolyzable polysiloxane D-1 (2.08 g), thermally conductive fillers C-4 (15.6 g), C-8a (13.78 g), and C-8c (11 g). The total weight of the composition was 42.54 g.

[0109] Example 3 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.08 g), hydrolyzable polysiloxane D-1 (1.77 g), thermally conductive fillers C-4 (14.76 g), C-8a (9.85 g), and C-8c (15.7 g). The total weight of the composition was 42.16 g.

[0110] Example 4 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.05 g), A-2a (1.13 g), and hydrolyzable polysiloxane D-1 (0.75 g) with thermally conductive fillers C-1 (3.68 g), C-2 (2.45 g), C-8a (7.46 g), and C-8d (18.05 g). The total weight of the composition was 33.56 g.

[0111] Example 5 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.06 g), A-2a (0.78 g), and hydrolyzable polysiloxane D-1 (0.43 g) with thermally conductive fillers C-2 (3.8 g), C-8a (10.5 g), and C-8d (21.07 g), and additive KBM3103 (decyltrimethoxysilane) E-1 (0.77 g). The total weight of the composition was 37.41 g.

[0112] Example 6 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.08 g), A-2a (0.94 g), and hydrolyzable polysiloxane D-1 (0.63 g) with thermally conductive fillers C-5 (16 g), C-8a (8.0 g), and C-8c (8.0 g). The total weight of the composition was 33.68 g.

[0113] Example 7 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.06 g), A-2a (0.92 g), and hydrolyzable polysiloxane D-1 (0.62 g) with thermally conductive fillers C-6 (16 g), C-8a (8.0 g), and C-8c (8.0 g). The total weight of the composition was 33.72 g.

[0114] Example 8 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.66 g), A-2a (0.60 g), and hydrolyzable polysiloxane D-1 (0.51 g) with thermally conductive fillers C-3 (22.5 g), C-8a (7.51 g), C-8b (5.0 g), C-8c (10.38 g), and C-9 (2.89 g). The total weight of the composition was 50.04 g.

[0115] Example 9 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.06 g), A-2a (0.99 g), and hydrolyzable polysiloxane D-1 (0.61 g) with thermally conductive fillers C-6 (18.02 g), C-8a (7.5 g), C-8b (3.32 g), C-8c (6.33 g), and C-9 (1.51 g), and additive KBM3103 (decyltrimethoxysilane) E-1 (0.13 g). The total weight of the composition was 38.46 g.

[0116] Example 10 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.15 g), A-2a (2.7 g), and hydrolyzable polysiloxane D-1 (1.8 g) with thermally conductive fillers C-4 (47.7 g), C-8a (23.8 g), and C-8c (23.8 g). The total weight of the composition was 100 g.

[0117] Example 11 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (0.15 g), A-2a (2.7 g), and hydrolyzable polysiloxane D-1 (1.8 g) with thermally conductive fillers C-6 (47.7 g), C-8a (23.8 g), and C-8c (23.8 g). The total weight of the composition was 100 g.

[0118] Example 12 was prepared in the same manner as in Example 1 by mixing polysiloxane A-1a (1.6 g), A-2a (1.8 g), and hydrolyzable polysiloxane D-1 (1.2 g) with thermally conductive fillers C-2 (3.0 g), C-6 (47.7 g), C-8a (17.9 g), C-8c (20.9 g), and C-9 (6.0 g). The total weight of the composition was 100 g.

[0119] Example 13

[0120] Component A: Polysiloxanes A-1a (1.00 g) and A-2a (1.21 g), hydrolyzable polysiloxane D-1 (1.0 g), and platinum catalyst G-1 (0.286 g of an 18 wt% solution of a platinum dimer complex containing 2 wt% platinum in a monovinyl-terminated organopolysiloxane (viscosity 0.02 Pa s)) were weighed into a plastic container and mixed for 30 seconds at 2000 rpm using a Thinky mixer. To this mixture, thermally conductive fillers C-6 (45.0 g), C-8a (15.0 g), C-8b (10.0 g), C-8c (20.75 g), and C-9 (5.75 g) were added stepwise, and all materials were mixed using the Thinky mixer at 2000 rpm for 30 seconds in each step. After each 30-second mixing period, the composition was hand-mixed for 2 minutes using a broad-blade spatula. The composition was further mixed in a Thinky mixer at 2000 rpm for 30 seconds. After mixing, the composition was degassed at room temperature to remove any trapped air. The total weight of the composition was 100 g.

[0121] Component B: Polysiloxanes A-1a (1.00 g) and A-2a (1.18 g), hydrolyzable polysiloxane D-1 (1.0 g), crosslinker B-1 (hydrogen-functionalized organopolysiloxane) (0.12 g), and reaction inhibitor F-1, a 1.5 wt % solution (0.2 g) of bis-{(1,1-dimethyl-2-propynyl)oxy}dimethyl-silane in crosslinker organohydrogenpolysiloxane (viscosity 0.02 Pa s), were weighed into a plastic container and mixed for 30 seconds at 2000 rpm using a Thinky mixer. To this mixture, thermally conductive fillers C-6 (45.0 g), C-8a (15.0 g), C-8b (10.0 g), C-8c (20.75 g), and C-9 (5.75 g) were added stepwise, and all materials were mixed in a Thinky mixer for 30 seconds at 2000 rpm after each step. After each 30-second mixing, the composition was mixed by hand for 2 minutes using a broad-blade spatula. The mixture was further mixed for 30 seconds at 2000 rpm in the Thinky mixer. After mixing, the composition was degassed at room temperature to remove any trapped air. The total weight of the composition was 100 g.

[0122] Example 14 was prepared similarly to Example 13 as follows.

[0123] Component A: Polysiloxanes A-1a (1.30 g) and A-2a (1.87 g), hydrolyzable polysiloxane D-1 (1.0 g), and Pt catalyst G-1 (0.285 g of an 18 wt % solution of a platinum dimer complex containing 2 wt % platinum in a monovinyl-terminated organopolysiloxane (viscosity 0.02 Pa s)) were mixed with thermally conductive fillers C-6 (48.5 g), C-8a (15.0 g), C-8b (5.0 g), C-8c (21.03 g), and C-9 (6.0 g). The total weight of the composition was 100 g.

[0124] Component B: Polysiloxanes A-1a (1.30 g) and A-2a (1.75 g), hydrolyzable polysiloxane D-1 (1.0 g), crosslinker B-1 (hydrogen-functionalized organopolysiloxane) (0.13 g), and reaction inhibitor F-1: a 1.5 wt % solution (0.283 g) of bis-{(1,1-dimethyl-2-propynyl)oxy}dimethyl-silane in organohydrogenpolysiloxane crosslinker (viscosity 0.02 Pa s) were mixed with thermally conductive fillers C-6 (48.5 g), C-8a (15.0 g), C-8b (5.0 g), C-8c (21.03 g), and C-9 (6.0 g). The total weight of the composition was 100 g.

[0125] Example 15 was prepared similarly to Example 13 as follows.

[0126] Component A: Polysiloxanes A-1b (0.98 g) and A-2b (0.32 g), hydrolyzable polysiloxane D-2 (0.37 g), and Pt catalyst G-1 (18 wt % solution of platinum dimer complex containing 2 wt % platinum in monovinyl-terminated organopolysiloxane (viscosity 0.01 Pa s)) (0.18 g) were mixed with thermally conductive fillers C-7 (24.09 g), C-8a (9.36 g), C-8b (4.16 g), and C-8c (8.55 g). The total weight of the composition was 48.03 g.

[0127] Component B: Polysiloxane A-1b (0.98 g) and A-2b (0.1 g), hydrolyzable polysiloxane D-2 (0.37 g), crosslinker B-1 (hydrogen-functionalized organopolysiloxane) (0.22 g), reaction inhibitor F-1: a 1.5 wt% solution (0.21 g) of bis-{(1,1-dimethyl-2-propynyl)oxy}dimethyl-silane in organohydrogenpolysiloxane crosslinker (viscosity 0.02 Pa s), thermally conductive filler C-7 (24.09 g), C-8a (9.36 g), C-8b (4.16 g), and C-8c (8.55 g) were mixed. The total weight of the composition was 48.06 g.

[0128] Example 16 was prepared similarly to Example 13 as follows.

[0129] Component A solution: Polysiloxanes A-1b (0.98 g) and A-2b (0.32 g), hydrolyzable polysiloxane D-2 (0.37 g), and Pt catalyst G-1 (18 wt% solution of platinum dimer complex containing 2 wt% platinum in monovinyl-terminated organopolysiloxane (viscosity 0.01 Pa s)) (0.18 g) were mixed with thermally conductive fillers C-7 (24.09 g), C-8a (9.36 g), C-8b (4.16 g), C-8c (8.55 g), and C-9 (1.94 g). The total weight of the composition was 50 g.

[0130] Component B: Polysiloxane A-1b (0.98 g) and A-2b (0.1 g), hydrolyzable polysiloxane D-2 (0.37 g), crosslinker B-1 (hydrogen-functionalized organopolysiloxane) (0.22 g), reaction inhibitor F-1: a 1.5 wt% solution (0.21 g) of bis-{(1,1-dimethyl-2-propynyl)oxy}dimethyl-silane in crosslinker organohydrogenpolysiloxane (viscosity 0.02 Pa s), thermally conductive filler C-7 (24.09 g), C-8a (9.36 g), C-8b (4.16 g), C-8c (8.55 g), and C-9 (1.94 g) were mixed. The total weight of the composition was 50 g.

[0131] Example 17 was prepared similarly to Example 13 as follows.

[0132] Component A solution: Polysiloxanes A-1b (0.98 g) and A-2b (0.32 g), hydrolyzable polysiloxane D-2 (0.37 g), Pt catalyst G-1 (18 wt% solution of platinum dimer complex with 2 wt% platinum in monovinyl-terminated organopolysiloxane (viscosity 0.01 Pa s)) (0.18 g) were mixed with thermally conductive fillers C-7 (24.09 g), C-8a (9.36 g), C-8b (4.16 g), C-8c (8.55 g), and C-9 (2.91 g). The total weight of the composition was 50.97 g.

[0133] Component B: Polysiloxane A-1b (0.98 g) and A-2b (0.1 g), hydrolyzable polysiloxane D-2 (0.37 g), crosslinker B-1 (hydrogen-functionalized organopolysiloxane) (0.22 g), reaction inhibitor F-1: a 1.5 wt% solution (0.21 g) of bis-{(1,1-dimethyl-2-propynyl)oxy}dimethyl-silane in organohydrogenpolysiloxane crosslinker (viscosity 0.02 Pa s), thermally conductive filler C-7 (24.09 g), C-8a (9.36 g), C-8b (4.16 g), C-8c (8.55 g), and C-9 (2.91 g) were mixed. The total weight of the composition was 50.97 g.

[0134] Synthesis of crosslinked polysiloxane: Vinyl-terminated PDMS (500 g, MW ∼17280 g / mol, vinyl milliequivalent ∼0.115) along with Pt catalyst (2 wt% Karstedt's catalyst, 10 ppm Pt) and inhibitor (Surfynol® 61, 200 ppm) was added to a double planetary mixer at room temperature and mixed at 20 rpm for 30 minutes at room temperature. Silicone hydride (55.4 g, MW ∼40802, hydride milliequivalent ∼0.1586) was added to the reaction mixture at 50 °C, and mixing continued at 20 rpm for an additional hour. While continuing mixing at the same speed at 50 °C, a vacuum was applied for 60 minutes to remove the inhibitor and form a gel network. The reaction temperature was then increased to 90 °C and continued until all the hydride was consumed and a gel was formed.

[0135] Example 18: Polysiloxane A-1a (1.5 g), crosslinked polysiloxane (1.0 g), and hydrolyzable polysiloxane D-1 (1.0 g) were weighed into a plastic container and mixed for 30 seconds using a Thinky mixer at 2000 rpm. To this mixture, thermally conductive fillers C-6 (45.0 g), C-8a (15.0 g), C-8b (10.0 g), C-8c (20.75 g), and C-9 (5.75 g) were added stepwise, and all materials were mixed for 30 seconds at 2000 rpm using the Thinky mixer. After each 30-second mixing period, the composition was mixed by hand for 2 minutes using a broad-blade spatula. The mixture was further mixed for 30 seconds at 2000 rpm using the Thinky mixer. After mixing, the composition was degassed at room temperature to remove any trapped air. The total weight of the composition was 100 g.

[0136] Example 19 was prepared in the same manner as in Example 18 by mixing polysiloxane A-1a (1.75 g), crosslinked polysiloxane (1.0 g), and hydrolyzable polysiloxane D-1 (1.5 g) with thermally conductive fillers C-6 (48.5 g), C-8a (15.0 g), C-8b (5.0 g), C-8c (20.95 g), and C-9 (6.0 g). The total weight of the composition was 100 g.

[0137] Example 20 was prepared in the same manner as in Example 18 by mixing polysiloxane A-1a (1.65 g), crosslinked polysiloxane (1.1 g), and hydrolyzable polysiloxane D-1 (1.1 g) with thermally conductive fillers C-6 (45.0 g), C-8a (15.0 g), C-8b (10.0 g), C-8c (20.75 g), and C-9 (5.75 g). The total weight of the composition was 100 g.

[0138] Example 21 was prepared in the same manner as in Example 18 by mixing polysiloxane A-1a (1.75 g), crosslinked polysiloxane (1.0 g), and hydrolyzable polysiloxane D-1 (1.5 g) with thermally conductive fillers C-6 (48.5 g), C-8a (15.0 g), C-8b (5.0 g), C-8c (20.95 g), and C-9 (6.0 g). The total weight of the composition was 100 g.

[0139] Example 22 was prepared in the same manner as in Example 18 by mixing polysiloxane A-1a (1.75 g), crosslinked polysiloxane (1.0 g), and hydrolyzable polysiloxane D-1 (1.5 g) with thermally conductive fillers C-6 (48.5 g), C-8a (15.0 g), C-8b (5.0 g), C-8c (20.95 g), and C-9 (6.0 g), and antioxidants (2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene and didodecyl 3,3'-thiodipropionate) (0.3 g). The total weight of the composition was 100 g.

[0140] Thermally conductive grease-type compositions using irregular polycrystalline diamond fillers and other thermally conductive fillers

[0141] As can be seen from Table 1, compositions with different loadings of filler, dispersant, and polymer resin were optimized by using fillers of different particle sizes. In some cases, the compositions were dry and not jettable. When irregular polycrystalline diamond was used in the compositions, low jetting rates, low thermal conductivity, and the compositions were not stable.

[0142] Single crystal diamond was used in conjunction with other thermally conductive fillers to improve the thermal conductivity, delivery rate and stability of the thermally conductive composition (Table 2).

[0143] As shown in Table 2, the composition containing the mixture of thermal conductivity enhancer and single crystal diamond exhibited better thermal conductivity and jettability.

[0144] Ultra-high thermal conductivity two-component addition-curing thermally conductive composition

[0145] TIA2101GF is a commercially available two-part silicone composition manufactured by Momentive Performance Materials.

[0146] Two-component, addition-cure thermally conductive compositions with different filler loadings were prepared, achieving very good and stable discharge rates (>20 g / min) and excellent thermal stability, along with ultra-high thermal conductivity (>20 W / mK) (Table 3). Components A and B were mixed in a 1:1 ratio and cured at 70°C for 1 hour. The H / Vi ratios of the cured samples ranged from 0.4 to 0.9.

[0147] As can be seen from Table 3, Examples 13, 14, 16 and 17 exhibited a thermal conductivity of more than 12 W / mK with a dispensing rate of more than 13 g per minute, and also exhibited a smaller increase in hardness at a high temperature of 150°C, and showed a stable discharge rate after aging.

[0148] As shown in FIG. 1, the vertical stability performance under thermal shock (from bottom to top, gaps of 0.5 mm, 1 mm, and 2 mm) of Example 13 after 500 hours under thermal shock (from −40° C. to 150° C.) showed very good vertical stability.

[0149] Ultra-high thermal conductivity pre-cured gel composition

[0150]

[0151] Pre-cured thermally conductive gel compositions based on the combination of single crystal diamond and other fillers were designed and showed very high thermal conductivities ranging from 14 to 21 W / mK (Table 4). These thermally conductive gel compositions not only contained hard fillers such as AlN and diamond fillers, but also showed very good thermal stability over ultra-high temperatures despite being highly filled thermally conductive compositions. These thermally conductive gel compositions showed very little hardness increase at 150°C. For example, Example 19 showed very little hardness increase (Shore E) at 150°C even up to 1000 hours and showed stable discharge.

[0152] The foregoing description includes examples herein. While it is, of course, not possible for purposes of describing this specification to describe every conceivable combination of elements or methodologies, one skilled in the art will recognize that many further combinations and permutations of the present specification are possible. Accordingly, this specification is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent the term "comprising" is used in either the detailed description or the claims, such term is intended to be inclusive in the same manner as "comprising," as the term "comprises" is interpreted when used as a transitional phrase in the claims.

[0153] The above description identifies various non-limiting embodiments of the thermally conductive gel composition. Modifications will occur to those skilled in the art and those able to make and use the invention. The disclosed embodiments are merely exemplary and are not intended to limit the scope of the invention or the subject matter defined in the claims.

Claims

1. (A) an organopolysiloxane comprising: (i) an alkenyl-functionalized diorganopolysiloxane of formula (Ia) M １ ａ M ２ ｂ D １ ｃ D ２ ｄ T １ ｅ T ２ ｆ Q ｇ (Ia) [wherein, M １ = R １ R ２ R ３ SiO １／２ M ２ = R ４ R ５ R ６ SiO １／２ D １ = R ７ R ８ SiO ２／２ D ２ = R ９ R １０ SiO ２／２ T １ = R １１ SiO ３／２ T ２ = R １２ SiO ３／２ Q = SiO ４／２ where R ２ , R ３ , R ４ , R ５ , R ６ , R ８ , R ９ , R １０ , R １２ are each independently selected from monovalent aliphatic, aromatic and fluorohydrocarbon groups or alkoxy groups having 1 to 60 carbon atoms; R １ , R ７ , R １１ are each independently selected from monovalent aliphatic, aromatic or fluorohydrocarbon radicals having from 1 to 60 carbon atoms and containing at least one terminal olefinic bond, and the subscripts a, b, c, d, e, f and g are 0 or positive integers, subject to the limitations that 1≦a+b+c+d+e+f+g≦6000 and a+c+e≧1; and (ii) a hydrogen-functionalized organopolysiloxane M of formula (Ib): １ ａ′ M ２ ｂ′ D １ ｃ′ D ２ ｄ′ T １ ｅ′ T ２ ｆ′ Q ｇ′ (1b) [wherein, M １ = R １３ R １４ R １５ SiO １／２ M ２ = R １６ R １７ R １８ SiO １／２ D １ = R １９ R ２０ SiO ２／２ D ２ = R ２１ R ２２ SiO ２／２ T １ = R ２３ SiO ３／２ T ２ = R ２４ SiO ３／２ Q = SiO ４／２ where R １４ , R １５ , R １６ , R １７ , R １８ , R ２０ , R ２１ , R ２２ , R ２４ is a monovalent aliphatic, aromatic or fluorohydrocarbon radical having 1 to 60 carbon atoms; R １３ , R １９ , R ２３ is hydrogen; and the subscripts a', b', c', d', e', f' and g' are 0 or positive integers, subject to the limitations that 1≦a'+b'+c'+d'+e'+f'+g'≦6000 and a'+c'+e'≧1, including those in which a+c+e>1 when a'+c'+e'=1, and a'+c'+e'>1 when a+c+e=1; or an organopolysiloxane comprising the crosslinked product of (i) and (ii); and (B) a first thermal conductivity enhancer having a particle size in the range of 60 to about 200 μm, a second thermal conductivity enhancer having a particle size in the range of 0.5 to about 30 μm, and optionally a third thermal conductivity enhancer having a particle size in the range of 0.01 to less than about 0.5 μm.

2. The composition of claim 1, further comprising a dispersant represented by formula (II). [In the formula, R ２５ is a group having an alkoxysilyl group having 1 to 4 carbon atoms; R ２６ is a linear organosiloxy group (III), [In the formula, each R ２８ are independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, L is selected from a monovalent hydrocarbon radical having 1 to 6 carbon atoms and an alkoxysilyl radical having 1 to 4 carbon atoms, and k is an integer from 10 to 500; each X is independently a divalent hydrocarbon radical having 2 to 10 carbon atoms, each of h and i is independently 1 or a greater integer, j is 0 or a greater integer, h+i+j is 4 or a greater integer, and each R ２７ are independently selected from hydrogen and monovalent hydrocarbon radicals having 1 to 6 carbon atoms, or are represented by formula (IV): [In the formula, R ２９ represents an unsubstituted or substituted alkyl group, alkenyl group, or aryl group, and each R ３０ each independently represents an unsubstituted or substituted alkyl group, alkenyl group, or aryl group; R ３１ and R ３２ each represents the same or different unsubstituted or substituted monovalent hydrocarbon group, and each R ３３ each independently represents a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group; ３４ each independently represents an unsubstituted or substituted alkyl group, alkoxyalkyl group, alkenyl group, or acyl group, and n represents an integer of 2 to 20.

3. The composition of claim 1, wherein said organopolysiloxane has an H / Vi ratio greater than 0.

4.

4. The dispersant is represented by formula (II) The composition according to claim 2, wherein the compound is represented by the formula:

5. The composition of claim 4, wherein the dispersant comprises two or more hydrolyzable organopolysiloxane compounds of formula (II).

6. The composition of claim 4, wherein the dispersant comprises a first hydrolyzable organopolysiloxane represented by formula (II) and having a value of k in the range of 10 to 50, and a second hydrolyzable organopolysiloxane represented by formula (II) and having a value of k in the range of 100 to 500.

7. The composition of any one of claims 1 to 6, wherein the composition comprises the first thermal conductivity enhancer in an amount of 15% to 50% by weight based on the total weight of the composition.

8. The composition of claim 7, wherein said first thermal conductivity enhancer is diamond.

9. The composition of claim 8, wherein the diamond has a surface oxygen content of greater than 10%.

10. The composition of claim 7 or 8, wherein the composition comprises the second thermal conductivity enhancer in an amount of 20% to 50% by weight based on the total weight of the composition.

11. The composition of claim 10, wherein said second thermal conductivity enhancer is aluminum nitride.

12. The composition of claim 10 or 11, wherein the second thermal conductivity enhancer is present in a first average particle size in the range of 0.5 μm to less than 2 μm, a second average particle size in the range of 2 μm to less than 10 μm, and a third average particle size in the range of 10 μm to 30 μm.

13. The composition of claim 12, wherein the second thermal conductivity enhancer having the first average particle size is present in an amount of 5 wt. % to 25 wt. % based on the total weight of the composition, the second thermal conductivity enhancer having the second average particle size is present in an amount of 3 wt. % to 10 wt. % based on the total weight of the composition, and the second thermal conductivity enhancer having the third average particle size is present in an amount of 5 wt. % to 25 wt. % based on the total weight of the composition.

14. The composition of any one of claims 1 to 13, comprising the third thermal conductivity enhancer in an amount of 1 wt. % to 10 wt. %, based on the total weight of the composition.

15. The composition of claim 14, wherein the third thermal conductivity enhancer is zinc oxide having a particle size ranging from 0.01 to less than 0.5 μm.

16. A device comprising a first substrate, a second substrate, and a thermal interface material filling an interfacial gap between the first substrate and the second substrate, the interface material comprising the composition of any one of claims 1 to 15.

17. A heat dissipating material comprising the composition according to any one of claims 1 to 15.

18. A method for dissipating heat from a substrate, comprising contacting the substrate with a composition according to any one of claims 1 to 15.

19. A method of making a treated substrate comprising applying a composition according to any one of claims 1 to 15 to a surface of a substrate.

20. A device comprising a treated substrate, the treated substrate comprising a composition according to any one of claims 1 to 15.

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