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    • 专利摘要:
    THERMAL GREASE BASED ON HYPER-BRANCHED OLEFINIC FLUID. An effective thermal grease is prepared comprising a hyperbranched olefinic fluid and a thermally conductive filler. Property modifying additives and fillers may also be included. The hyperbranched olefinic fluid is selected to have an average of at least 1.5 methine carbon atoms per oligomer molecule and at least 40 methine carbons per thousand total carbons. Thermal grease exhibits a flash point of 180°C or greater, a pour point of 0°C or less, and a kinematic viscosity at 40°C of no more than 200 cSt (0.0002 m2/s). The composition can offer improved thermal conductivity, reduced tendency to migrate, and lower cost compared to many other thermal greases, including silicone-based thermal greases, when used in comparable applications.
    公开号:BR112017004672B1
    申请号:R112017004672-5
    申请日:2014-09-22
    公开日:2022-01-25
    发明作者:Yunfeng Yang；Hongyu Chen；Brad C. Bailey；Mohamed Esseghir；Suh Joon Han
    申请人:Dow Global Technologies Llc；
    IPC主号:
    专利说明:

    [001] The present invention relates to the field of thermal interface materials. More specifically, it relates to thermal greases that incorporate hyper-branched olefinic fluids and thermally conductive fillers.
    [002] Thermal interface materials (TIMs) play an integral role in thermal management solutions as materials that are placed between, for example, heat generating semiconductor components such as integrated circuits or transistors and heat sinks, heat spreaders and other thermal management components to improve heat transfer by filling microscopic air spaces that are present due to the components' imperfectly flat and smooth surfaces. TIMs come in many forms such as grease, gels, wafers, phase change materials and solders, and many of them are carbon (polymer) based. Thermal grease is one of the most important types, representing the largest market share of TIMs. This is because, compared to other TIMs, particularly polymer-based TIMs, thermal grease often has a higher effective thermal conductivity and a lower thermal resistance, due to the fact that it is being used in particularly narrow spaces between components, e.g. - so-called "thin joints" of less than 0.1 millimeter (mm).
    [003] Most thermal greases are viscous silicone oils or highly filled hydrocarbons. Greases with silicone oil as a matrix can exhibit many desired properties, including resistance to chemical attack and a wide operating temperature range. However, silicone oil is very expensive and tends to physically migrate from where it is applied, thus leading to contamination of nearby components. In addition, in the long term, thermal silicone grease can dry out, resulting in cracking and separation that compromises performance. To avoid such problems, non-silicone thermal greases using synthetic or natural oils, often mineral oil, have been developed. However, mineral oil has a low flash point (160°C), which limits its application in relatively high temperature devices.
    [004] Thus, researchers in the field of thermally conductive fluids have been looking for less expensive ways to transfer and/or eliminate heat. widely used in transformer applications, has been the use of dielectric fluids. Often, the identification of these fluids is related to very specific applications with important property requirements.
    [005] For example, WO2013101376A1 describes a dielectric hyperbranched fluid based on olefin oil. This dielectric fluid composition comprises a poly-α-olefin or poly(co-ethylene/α-olefin) having an average molecular weight greater than 200 and less than 10,000 Daltons. The dielectric composition has a hyper-branched structure that allows for low viscosity, high flash point, low pour point and desirable thermal oxidative stability.
    [006] EP823451A1 discloses a thermally conductive silicone composition comprising a liquid silicone and a thermally conductive filler. In this invention, the thermally conductive filler comprises an aluminum nitride powder and a zinc oxide powder.
    [007] CN1928039B discloses a conductive grease comprising an inorganic powder and an oil based on mineral oil or synthetic oil, wherein the inorganic powder is a combination of coarse and fine particles having a polyhedral shape.
    [008] EP939115A1 discloses a thermally conductive grease composition comprising: (A) 100 parts by weight of at least one base oil selected from the group consisting of liquid silicones, liquid hydrocarbons and fluorohydrocarbon oils and 500-1000 parts by weight of a thermally conductive filler consisting of (B) an inorganic filler with a Mohs hardness of at least 6 and a thermal conductivity of at least 100 W/m2K (watts per square meter per degree Kelvin) and (C) a thermally conductive filler inorganic filler with a Mohs hardness of not more than 5 and a thermal conductivity of not less than 20 W/m2K.
    [009] EP 982392B1 discloses a thermally conductive grease composition, characterized in that it comprises (A) 100 parts by weight of a base oil and (B) 500 to 1200 parts by weight of aluminum metal powder, wherein said aluminum is a 9:1 to 1:9 compound by weight of a fine metallic aluminum powder with an average particle size of 0.5 to 5 μm and a coarse metallic aluminum powder with an average particle size of 10 to 5 μm. 40 μm.
    [010] US6656389B2 discloses a thermal grease for low temperature applications comprising a thermally conductive solid filler; a dispersant; and a liquid linear alkylbenzene carrier. The linear alkylbenzene liquid carrier serves as the thermal paste (grease) matrix.
    [011] US20070031684A1 discloses a thermally conductive grease comprising 0 to about 49.5 weight percent carrier oil; 0.5 to 25 weight percent of at least one dispersant; and at least 49.5 weight percent thermally conductive particles, wherein the thermally conductive particles comprise a mixture of at least three thermally conductive particle size distributions, each of the thermally conductive particle size distributions having a mean (D50, MMD) that differs from the other distributions by at least a factor of 5.
    [012] US20080004191A1 discloses a thermally conductive grease comprising: (A) a base oil having a viscosity of 112 to 770 square millimeters (mm2) at 40°C and comprising a copolymer of an unsaturated dicarboxylic acid dibutyl ester and an α-olefin ; and (B) a thermally conductive filler filled with the base oil. A copolymer of an unsaturated dicarboxylic acid dibutyl ester and α-olefin is required.
    [013] WO2013052375A1 discloses a thermally conductive grease comprising: a carrier oil; a dispersant; and thermally conductive particles, wherein the thermally conductive particles have a D50 particle size (MMD) not greater than about 11 micrometers (μm), and wherein the thermally conductive particles in the thermally conductive fat contain less than about 3% in volume of particles having a particle size of 0.7 µm or less, based on a total volume of thermally conductive particles in the thermally conductive fat.
    [014] In one embodiment, the present invention provides a thermal grease composition comprising a mixture of (a) an olefinic fluid based on ethylene and hyperbranched propylene, with an average of at least 1.5 methine carbons per molecule of oligomer and having at least 40 methine carbons per thousand total carbons, and wherein the average number of carbons per molecule is 25 to 200; and (b) a thermally conductive filler.
    [015] In another embodiment, the present invention provides a process for preparing a thermal fat composition comprising (a) contacting ethylene and optionally propylene and further, optionally, an alpha-olefin and at least one coordination insertion catalyst , wherein the coordination insertion catalyst is a metal-ligand complex in which the metal is selected from zirconium, hafnium and titanium, and has an ethylene/octene reactivity ratio of up to 20 and a kinetic chain length of up to 20 monomer units; in a crosslinked reactor zone fed continuously under conditions such that a mixture of at least two oligomeric products is formed, the mixture including (i) a first component comprising a hyperbranched oligomer having an average of at least 1.5 methine carbons per oligomer molecule and having at least 40 methine carbons per thousand total carbons and wherein at least 40 percent of the methine carbons are derived from ethylene or, when optional propylene is included, from ethylene and propylene, and where the average number of carbons per molecule is from 25 to 200; and (ii) a second component comprising at least one volatile organic product having an average carbon number less than or equal to 14 (b) separating the volatile organic product from the hyperbranched oligomer; (c) recovering the hyperbranched oligomer; and (d) mixing hyperbranched oligomer and a thermally conductive filler to form a thermal grease composition.
    [016] Formulas I and II represent generalized metallocene catalysts useful in the invention.
    [017] Formula III represents a generalized bis-phenylphenoxy catalyst useful in the invention.
    [018] Formula IV represents a coordination insertion catalyst of formula (L)ZrMe2 wherein (L) = 2',2'''- (ethane-1,2-diylbis(oxy))bis(3-( 3,6-di-tert-butyl-9H-carbazol-9-yl)-5'-fluoro-3'-methyl-5-(2,4,4-trimethyl-pentan-2-yl)-[1, 1'-biphenyl]-2-ol).
    [019] Formula V represents a coordination insertion catalyst of formula (L)ZrMe2 wherein (L) = 3-(3,6-di-tert-butyl-9H-carbazol-9-yl)-2'- (2-((3'-(3,6-di-tert-butyl-9H-carbazol-9-yl)-5-fluoro-2'-hydroxy-5'-(2,4,4-tri-methyl - pentan-2-yl)-[1,1'-biphenyl]-2-yl)oxy)ethoxy)-3',5'-difluoro-5-(2,4,4-trimethylpentan-2-yl)- [1,1'-bi-phenyl]-2-ol.
    [020] Formula VI represents a coordination insertion catalyst of formula (L)ZrMe2 wherein (L) = 3-(3,6-di-tert-butyl-9H-carbazol-9-yl)-2'- (2-((3'-(3,6-di-tert-butyl-9H-carbazol-9-yl)-3,5-difluoro-2'-hydroxy-5'-(2,4,4-trimethyl) - pentan-2-yl)-[1,1'-biphenyl]-2-yl)oxy)ethoxy)-5'-fluoro-3'-methyl-5-(2,4,4-trimethylpentan-2-yl) )-[1,1'-biphenyl]-2-ol.
    [021] Formula VII represents a coordination insertion catalyst of formula (L)HfMe2 wherein (L) = 2',2'''-(ethane-1,2-diylbis(oxy))bis(3-( 3,6-di-tert-butyl-9H-carbazol-9-yl)-3',5'-difluoro-5-(2,4,4-trimethylpentan-2-yl)-[1,1'-biphenyl ]-2-ol).
    [022] Formula VIII represents a coordination insertion catalyst of formula (L)ZrMe2 wherein (L) = 2',2'''-(ethane-1,2-diylbis(oxy))bis(3-( 3,6-di-tert-butyl-9H-carbazol-9-yl)-3',5'-difluoro-5-(2,4,4-trimethylpentan-2-yl)-[1,1'-biphenyl ]-2-ol).
    [023] Formula IX represents a coordination insertion catalyst of formula (L)ZrMe2 wherein (L) = 6',6'''-(ethane-1,2-diylbis(oxy))bis(3-( 3,6-di-tert-butyl-9H-carbazol-9-yl)-3'-fluoro-5-(2,4,4-trimethylpentan-2-yl)-[1,1'-biphenyl]-2 -ol).
    [024] Formula X represents a coordination insertion catalyst of formula (L)HfMe2 wherein (L) = 6',6'''-(ethane-1,2-diylbis(oxy))bis(3-( 3,6-di-tert-butyl-9H-carbazol-9-yl)-3'-fluoro-5-(2,4,4-trimethylpentan-2-yl)-[1,1'-biphenyl]-2 -ol).
    [025] The present invention offers a variety of thermal greases that are commonly based on a hyper-branched olefinic fluid. These olefinic fluids are combined with a thermally conductive filler material to form a thermal grease that offers a number of advantages over conventionally available thermal greases. It is especially desirable that the thermal grease compositions of the invention offer a lower cost and equal or better thermal conductivity and thermal resistance when compared to other thermal greases.
    [026] The first required component, called Component A, is a selected hyper-branched olefinic fluid. This fluid is desirably defined as a low molecular weight ethylene-based or ethylene-propylene-based hyperbranched olefinic fluid. In particular embodiments, this hyper-branched olefinic fluid has a flash point of at least 200°C, a pour point that is 0°C or less, and a kinematic viscosity at 40°C, measured in accordance with ASTM D455 protocol. , which allows use as a grease, i.e. desirably less than or equal to 0.0002 m2/s (200 centistokes (cSt)), more preferably less than or equal to 0.00015 m2/s (150 cSt ), but also desirable at least 0.00001 m2/s (10 cSt). In particular embodiments, it is preferred that the number average molecular weight (Mn) ranges from 350 Daltons (Da) to 2800 Da, i.e., an average of 25 to 200 carbons per molecule; more preferably from 350 Da to 2000 Da; even more preferably from 350 Da to 1000 Da; and more preferably from 350 Da to 700 Da.
    [027] In some embodiment, Component A may further comprise additional optional constituents, such as mineral oils, synthetic oils, including but not limited to silicone oils, vegetable oils, combinations thereof, and the like. Such a combination can be selected according to the desired final properties.
    [028] The second required component of the thermal greases of the invention is herein called Component B. Component B is at least one thermally conductive filler. Appropriate selections for this may include ceramic fillers such as, but not limited to, beryllium oxide, aluminum nitride, boron nitride, aluminum oxide, zinc oxide, magnesium oxide, silicon carbide, silicon nitride, silicon dioxide and zinc sulfide; solid metal particles, including but not limited to silver, copper or aluminum; carbon materials, including but not limited to diamond dust; short carbon fibers, carbon black, graphite, carbon nanotubes, graphene and graphene oxide; liquid metals such as gallium-based alloys; or combinations thereof.
    [029] Alternatively or additionally, it may be desirable in some embodiments to blend the hyper-branched olefinic fluid with, as an optional C-Component, a silicone fluid, to form an immiscible viscous grease fluid. Such a C Component, referred to herein as a "phase segregator", may be desirable where the hyperbranched olefinic fluid has a surface tension that is different from that desired. This blending can help to reduce the separation between the hyperbranched olefinic fluid from the thermally conductive additive, or other fillers, and consequent drying. This can also allow the segregation of the thermally conductive filler, often expensive, in one phase and the lower cost of other fillers in a separate phase. Since thermal conduction percolation can still be ensured in this way, the result can be higher thermal conductivity with a lower filler content and therefore a lower total cost. Examples thereof may include, but are not limited to, polydimethylsiloxane (PDMS); phenylmethylpolysiloxane; hydroxy-terminated PDMS; polydimethyl-diphenylsiloxane; polydiphenyl siloxane; and other methyl-alkoxy-polysiloxanes containing an alkyl group, such as a naphthyl group, an ethyl group, a propyl group, or an amyl group; and their combinations. This may be included in place of, or in combination with, one or more of the thermally conductive fillers.
    [030] Finally, additional additives can optionally be included in the thermal grease, as another optional C-Component, in order to ensure desirable properties. For example, a low cost (non-thermally conductive) filler such as silica may be included to ensure a desired viscosity. Flame retardants such as aluminum trihydrate, zinc borate, a flame retardant/plasticizer such as PHOSFLEXTM 71B, available from SUPRESTA U.S. LLCTM, and certain other organic flame retardants. Surfactants may be included to improve the dispersion of the thermally conductive filler, silicone fluid or other additives. Such may be selected from, for example, serial SPANTM and serial TWEENTM, available from SINOPHARM CHEMICAL REAGENTTM. Antioxidants such as IRGAFOSTM 168 or IRGANOXTM 1010, available from THE BASF CHEMICAL COMPANYTM, can be used. Coupling agents, which may be silane-based or titanate-based, can be used to treat fillers prior to incorporation into the thermal grease. Other agents, such as bleed inhibiting agents, rheology modifiers, and the like, and any combinations of the foregoing, may also be selected for use. Component ratios may vary within the art of those skilled in the art, according to the desirable properties of the final thermal grease. However, in some embodiments it may be desirable to employ a ratio of Component A (total) ranging from 10 volume percent (vol %) to 40 volume %, more preferably 20 vol %. at 30% by vol. When using both ethylene and propylene to form Component A, it is preferred that the ratio of ethylene to propylene is between 20% by mol (% by mol) and 80% by mol and more preferably between 40% by mol and 60% by mol. If another optional alpha-olefin is included, it is preferred that its ratio range from 20 mol% to 50 mol%.
    [031] Component B may preferably range from 60% by volume to 90% by volume, and more preferably between 70% by volume and 80% by volume, based on component A and component B combined. Regardless of the reason, the filler constitutes the dispersed phase, while component A constitutes the matrix, or continuous, phase.
    [032] When a surfactant is included to ensure an acceptable dispersion of fillers, it is desirable, in some embodiments, for that surfactant to be between 0.5% by weight (% by weight) and 3.0% by weight, preferably between 1.0 and 2.0% by weight, based on the total weight of fillers. Flame retardants, if included, can desirably vary from 2 to 6 times, based on the weight of Component A. In certain embodiments, typical flame retardants such as aluminum trihydrate and other inorganic compounds can also act as agents. of fillers and may have a significantly higher density than Component A. Finally, when forming an immiscible viscous fluid comprising both the hyperbranched olefinic fluid and a phase segregator, such as a silicone fluid, it is desirable that the hyperbranched olefinic fluid ranges from 20% by volume to 80% by volume and that the miscibility modifier ranges from 20% by volume to 80% by volume, both based on Component A only. Even when most of the thermal grease is composed of silicone fluid, however, this is not, as defined herein, "silicone-based", due to the very significant effect on the properties attributed to the presence of the hyperrami olefinic fluid. stayed. In order to prepare the thermal grease compositions of the invention, it is generally desirable to first dry the selected thermally conductive filler using, for example, a conventional drying oven for a suitable period of time to ensure a moisture content preferably less than 0. 5% by weight, more preferably less than 0.1% by weight, based on the weight of the thermally conductive filler. After drying, the thermally conductive filler may be surface treated using a coupling agent and/or a surfactant to improve the wettability of the thermally conductive filler by the hyperbranched olefinic fluid matrix when the two are combined. During the preparation of the thermal grease, sufficient mixing of the filler and matrix is required to ensure acceptable and homogeneous distribution and wetting of the filler in the fluid matrix. Such mixing may suitably be carried out manually, on a laboratory scale, using a spatula or similar mixing tool, but is usually done on a commercial scale by means of an impeller/kneader, a centrifugal mixer (such as a commercially available mixer at HAUSCHILDTM), or a BAKER-PERKINTM mixer.
    [033] When additional additives are selected for use, such as flame retardants, low cost (non-thermal conductive) fillers and the like, their incorporation can be carried out simultaneously with, or before or after the incorporation of the filler. thermally conductive. Suitable means and methods of incorporation will be well known to those skilled in the art and will depend on a wide variety of variables too numerous to describe in detail here. These may include the nature and physical properties of the additive(s) and preference protocols based on factors such as developmental rheology.
    [034] An ethylene-based, hyperbranched olefinic fluid that is suitable for use in the invention is described in detail in copending patent application PCT/US2014/043754, entitled “Hyperbranched Ethylene-Based Oils and Greases,” No. of attorney 73437-WO-PCT, filed June 24, 2014, claiming the benefit of Provisional Application US 61/840,622, filed June 28, 2013. Although detailed descriptions of some suitable embodiments are included therein and incorporated herein by reference in their entirety, their preparation generally includes reacting the starting monomer(s) to form a mixture of oligomers therefrom. As the term is used herein, "oligomers" are molecules, formed by consecutive addition of monomer or comonomer units, that have an average molecular size of not more than 50 units. The average size is calculated as the total number of incorporated comonomer units divided by the total number of oligomer molecules. Alternatively, another indication of molecular size is the average number of carbon atoms per molecule, which is the total carbon count divided by the total number of molecules.
    [035] The starting monomer may be ethylene alone, or ethylene and propylene, either of which may optionally further include a proportion of another alpha-olefin comonomer. If an alpha-olefin is included, it may be selected, without limitation, from linear alpha-olefins of 3 to 12 carbons, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene , 1-nonene, 1-decene, undecene, 1-dodecene and combinations thereof. Smaller linear alpha-olefins with 3 to 8 carbon atoms are preferred because they allow for a higher branch density of the oligomers in the final product. Branched alpha olefins may also be used in the process feed and may include, in non-limiting embodiments, individually branched and multiply branched alpha olefin monomers having from 5 to 16 carbons, wherein the first substituted carbon is at the "3" position. " or higher than vinyl and combinations thereof. It is generally preferred that the first substitution be at position "4" or higher.
    [036] Note that the ethylene/alpha-olefin reactivity ratio is different for any catalyst and is expected to vary with the reaction temperature. For any given catalyst, the ethylene-olefin reactivity ratio (r1) is determined by performing a low conversion co-oligomerization and by observing the oligomer composition (F) resulting from a chosen monomer composition (f). Equation 1 below is the relationship between F, f, and r1 that can be used to estimate r1 from a single oligomerization or obtain a more statistically reliable value for r1 from a series of oligomerizations:(1-F2) /F2 = r1 (1-f2)/f2(Equation 1)
    [037] FTIR or 13C NMR measurements of the oligomer (F) composition are typically used for determining the reactivity ratio, with 13C NMR being preferred. Fractions of alpha-olefin monomers (f2) ranging from 33-66% are generally used for the determination of the reactivity ratio, with a value of 50% being preferred. The preferred method for determining the ethylene-olefin reactivity ratio involves an equimolar level of olefin and ethylene dissolved in a compatible solvent, such as an alkane, such that fi = f2 = ^. After a co-oligomerization of this mixture at low conversion (<20%), the resulting oligomer compositions (F) are used in equation i to determine the reactivity ratio ri.
    [038] However, regardless of whether an alpha-olefin is used, the catalyst selected to prepare the fluid used in the formation of the thermal grease has an ethylene/octene reactivity ratio that is up to 20, preferably from 1 to 20, more preferably of ai i2, and more preferably ai of 6. Note that while ethylene/alpha-olefin reactivity ratios in general will normally vary according to processing temperature, the maximum ratios defined herein apply to any and all processing temperatures. Determination of reactivity based on the ethylene/octene reactivity ratio can be applied regardless of whether i-octene is included as an optional alpha-olefin in the compositions of the invention, but in general smaller molecules such as propylene will incorporate more readily than larger molecules, such as i-octene, and therefore the reactivity ratio of ethylene/alpha-olefin with, for example, propylene, will tend to be lower. Regardless of the comonomer(s) selected, determination of the reactivity ratio will be necessary to achieve a target oligomer composition. A simple random copolymerization model relates the molar fraction of alpha-olefin monomer (f2) to the molar fraction of alpha-olefin in the copolymer (F2), where ri is the ratio of ethylene reactivity to alpha-olefin reactivity. olefin, based on Equation 1 above, where r1 = ethylene reactivity/alpha-olefin reactivity; F2 = molar fraction of alpha-olefin in the product oligomer; and f2 = molar fraction of alpha-olefin in the monomer. Thus, for a given catalyst and with minimal experimentation, those skilled in the art will be able to easily determine the alpha-olefin monomer fraction (f2) needed to achieve the desired alpha-olefin polymer (F2) content. This desired alpha-olefin comonomer content is generally preferred from 30 mol % to 70 mol %, more preferably from 40 mol % to 60 mol %, particularly but not limited to the case of propylene, the remainder being desirable ethylene.
    [039] In preparing a suitable starting hyper-branched olefinic fluid, the selected starting monomer, or monomers, is/are contacted with a suitable coordinating insertion catalyst. As the term is used here, "coordination insertion" means that the catalysts are able to consecutively insert unsaturated monomers, with the result that the previously unsaturated carbons in the monomers and the oligomer become the backbone of a new oligomer. This catalyst can be selected, in one embodiment, from a wide variety of metal-ligand complexes. Those skilled in the art will be aware that catalyst performance varies with process temperature and may also vary with the composition of the reaction and conversion mixture. Preferred catalysts are those that exhibit an activity level of 100,000 grams of oligomer per gram of metal catalyst (g/g cat). Also preferred are catalysts capable of producing a chain termination rate that results in a product oligomer of a desired molecular weight.
    [040] Examples of suitable coordination insertion catalysts may generally include, in certain non-limiting embodiments, metal-ligand complexes including any of the metals zirconium, hafnium or titanium, and preferably zirconium or hafnium. Among these catalysts may be certain metallocene catalysts, including certain geometry restricted catalysts and bis-phenylphenoxy catalysts, provided that the selected catalyst meets the ethylene/octene reactivity ratio and kinetic chain length requirements as defined above.
    [041] The metallocene compounds useful here are cyclopentadienyl derivatives of titanium, zirconium and hafnium. These metallocenes (e.g. titanocenes, zirconocenes and hafnocenes) can be represented by one of the following formulas:
    wherein M is the metal center, and is a Group 4 metal, preferably titanium, zirconium or hafnium; T is an optional linking group which, if present, in preferred embodiments is selected from dialkylsilyl, diarylsilyl, dialkylmethyl, ethylenyl (-CH2-CH2-) or hydrocarbylethylene wherein one, two, three or four of the hydrogen atoms in ethyleneyl are replaced by hydrocarbyl, wherein the hydrocarbyl may independently be C1 to C16 alkyl or phenyl, tolyl, xylyl and the like, and when T is present, the depicted catalyst may be in a racemic or meso form; L1 and L2 are the same or different optionally substituted cyclopentadienyl, indenyl, tetrahydroindenyl or fluorenyl rings that are each linked to M, or L1 and L2 are the same or different cyclopentadienyl, indenyl, tetrahydroindenyl or fluorenyl, which rings are optionally substituted with one or more R groups, any two adjacent R groups being linked to form a substituted or unsubstituted, saturated, partially unsaturated or aromatic cyclic group or a polycyclic substituent; Z is nitrogen, oxygen or phosphorus; R' is a linear or branched cyclic group of C1 to C40 alkyl or substituted alkyl; X1 and X2 are independently hydrogen, halogen, hydride radicals, hydrocarbyl radicals, substituted hydrocarbyl radicals, halocarbyl radicals, substituted halocarbyl radicals, silylcarbyl radicals, substituted silylcarbyl, germylcarbyl radicals or substituted germylcarbyl radicals; or both X are bonded and bonded to the metal atom to form a metallacycle ring containing from about 3 to about 20 carbon atoms; or both together form an olefin, a diolefin, or an aryin ligand.
    [042] Among the metallocene compounds that can be used in this invention are stereorigidic, chiral or asymmetric metallocenes, bridged or not, or so-called "geometry constrained metallocenes". See, for purposes of non-limiting example only and for further discussion and elucidation of methods for preparing catalyst, US Patent 4,892,851; US Patent 5,017,714; US Patent 5,132,281; US Patent 5,155,080; US Patent 5,296,434; US Patent 5,278,264; US Patent 5,318,935; US Patent 5,969,070; US6,376,409; US Patent 6,380,120; US Patent 6,376,412; WO-A- (PCT/US92/10066); WO 99/07788; WO-A-93/19103; WO 01/48034; EP-A2-0 577 581; EP-Al-0 578 838; WO 99/29743, and also the academic literature, for example, "The Influence of Aromatic Substituents on the Polymerization Behavior of Bridged Zirconocene Catalysts," Spaleck, W., et al., Organometallics, 1994, Vol. 13, pgs. 954-963; "ansa-Zirconocene Polymerization Catalysts with Annelated Ring Ligands—Effects on Catalytic Activity and Polymer Chain Lengths," Brintzinger, H., et al., Organometallics 1994, Vol. 13, pgs. 964-970; "Constrained Geometry Complexes—Synthesis and Applications," Braunschweig, H., et al., Coordination Chemistry Reviews, 2006, 250, 2691-2720; and documents referred to therein, all of which are incorporated herein by reference in their entirety.
    [043] In certain particular embodiments, the catalyst selected may be a compound of Formula III:
    wherein M is titanium, zirconium or hafnium, each independently being in a formal oxidation state of +2, +3 or +4; N is an integer from 0 to 3, where when n is 0, X is absent; each X independently is a monodentate ligand that is neutral, monoanionic or dianionic, or two Xs are taken together to form a bidentate ligand that is neutral, monoanionic or dianionic; X and n are selected such that the metal-ligand complex of Formula (III) is globally neutral; each Z is independently O, S, N(C1-C40)hydrocarbyl, or P(C1-C40)hydrocarbyl; L is (C1-C40)hydrocarbylene or (C1-C40)heterohydrocarbylene, wherein the (C1-C40)hydrocarbylene has a moiety comprising a linking backbone of 2 carbon atoms to 5 atoms linking the Z atoms in the Formula (III) and (C1-C40)heterohydrocarbylene has a moiety comprising a 2-atom to 5-atom linker backbone linking the Z atoms in Formula (III), wherein each atom of the 2-atom to 5-atom linker (C1-C40) heterohydrocarbylene atoms independently is a carbon atom or a heteroatom, wherein each heteroatom is independently O, S, S(O), S(O)2, Si(RC)2, Ge(RC)2 , P(RP), or N(RN), wherein independently each RC is unsubstituted (C1-C18)hydrocarbyl, or the two RCs are taken together to form a (C2-C19)alkylene, each RP is (C1-C18) unsubstituted hydrocarbyl; and each RN is unsubstituted (C1-C18)hydrocarbyl, a hydrogen atom, or absent; R1a, R2a, R1b, and R2b are independently a hydrogen, (C1-C40)hydrocarbyl, (C1-C40)heterohydrocarbyl, N(RN)2, NO2, ORC, SRC, Si(RC)3, Ge(RC )3, CN, CF3, F3CO, or halogen atom, and each of the others of R1a, R2a, R1b, and R2b is independently a hydrogen, (C1-C40)hydrocarbyl, (C1-C40)heterohydrocarbyl, N (RN)2, NO2, ORC, SRC, Si(RC)3, CN, CF3, F3CO or halogen atom; each of R3a, R4a, R3b, R4b, R6c, R7c, R8c, R6d, R7d, and R8d is independently a hydrogen atom, (C1-C40)hydrocarbyl, (C1-C40)heterohydrocarbyl, Si(RC)3, Ge(RC)3, P(RP)2, N(RN)2, ORC, SRC, NO2, CN, CF3, RCS(O)-, RCS(O)2-, (RC)2C=N-, RCC (O)O-, RCOC(O)-, RCC(O)N(R)-, (RC)2NC(O)- or halogen atom; each of R5c and R5d is independently a (C6-C40)aryl or (C1-C40)heteroaryl; and each of the above-mentioned aryl, heteroaryl, hydrocarbyl, heterohydrocarbyl, hydrocarbylene and heterohydrocarbylene groups is independently unsubstituted or substituted with 1 to 5 additional substituents RS; and each of RS is independently a halogen atom, polyfluoro substitution, perfluoro substitution, unsubstituted (C1-C18)alkyl, F3C-, FCH2O-, F2HCO-, F3CO-, R3Si-, R3Ge-, RO-, RS-, RS(O)-, RS(O)2-, R2P-, R2N-, R2C=N-, NC-, RC(O)O-, ROC(O)-, RC(O)N(R )-, or R2NC(O)-, or two of RS are taken together to form an unsubstituted (C1-C18)alkylene, where R is independently an unsubstituted (C1-C18)alkyl.
    [044] In more particular embodiments, the catalyst may be selected from compounds represented by Formulas IV to X.



    [045] The preparation of these bis-phenylphenoxy compounds can be by any means known or imagined to those skilled in the art. but generally involve means and methods such as those disclosed, for example, in PCT/US2012/0667700, filed November 28, 2012, claiming priority from Provisional Application US 61/581,418, filed December 29, 2011 (Attorney No. 71731) and US 13/105,018, filed May 11, 2011, Publication Number 20110282018, claiming priority from Provisional Application 61/487,627, filed March 25, 2011 (Attorney No. 69,428). Those skilled in the art will recognize that similar and analogous processes can be used to prepare other useful bis-phenylphenoxy compounds that fall within the given definition.
    [046] In carrying out the process to prepare the hyper-branched ethylene-based or propylene-ethylene-based olefinic oil, it is desirable that the contact between the monomer(s) and the coordination insertion catalyst occurs in a reactor zone. As the term is used herein, "backmixed reactor zone" refers to an environment in which a reaction product is mixed with unconverted reactor feeds. A continuous stirred tank reactor is preferred for this purpose, while it is noted that plug flow reactors are specifically designed to prevent backmixing. However, a closed loop reactor can achieve a variable degree of post-mixing by recycling a portion of the reactor effluent to feed a plug flow zone, with the recycling ratio moderating the degree of back-mixing. Thus, plug-flow reactors are not preferred, while a closed-loop reactor with a plug-flow zone is preferred. In the inventive process, back mixing ensures the reaction of already produced oligomers with a new raw material, for example, ethylene. It is this continuous contact that allows the oligomers to branch through repeated insertion of olefins, although, in general, the use of propylene as an alpha-olefin comonomer typically requires less backmixing to accomplish equivalent branching, because the level of branching can be controlled by the concentration of propylene in the reactor.
    [047] The conditions under which contact occurs in the continuously fed reactor zone, the backmixed reactor zone may include a desirable temperature ranging from 0°C to 250°C, more desirable from 25°C to 200°C, and more desirably from 50°C to 180°C; a desirable ethylene partial pressure ranging from 103 kilopascals, kPa (15 pounds per square inch, psi) to 3450 kPa (500 psi), more desirably from 207 kPa to 2070 kPa (30 psi to 300 psi), and most desirably from 345 kPa (50 Psi) to 1380 kPa (200 psi); and a desirable residence time ranging from 1 minute (min) to 120 min, more desirably from 5 min to 60 min, and most desirably from 10 min to 30 min. A reactor system may consist of many low residence time reaction zones or a few high residence time reaction zones. However, those skilled in the art will readily understand that changing parameters may be used for reasons of convenience, alteration of yield, avoidance of undesirable by-products or degradation, and the like.
    [048] The result of the process is the production of at least two products, a product called hyper-branched and a volatile organic product. The term "hyper-branched oligomer" refers to the desired or target "hyper-branched" fluid, regardless of their order of production or relative proportion. Such materials are collectively referred to herein as "utility fluids." By "hyperbranched" is meant that the oligomer molecules comprise a random distribution of straight chain segments joined through methine carbons and having an average of at least 1.5 methine carbons per molecule. Hyperbranching is present when the methine carbons are located randomly in the molecule and are not isolated in the backbone of the main polymer, as with a standard ethylene-olefin copolymer. The 13C NMR measurement of methine carbons can be used to determine the level of total branching. Note that, due to the nature of the coordination insert, continued contact of the raw material and mixed product with the catalyst is expected to result in either true complete polymerization or an excessive level of branching, thereby forming a material that may contain a predominant amount of a hyper-branched product. Thus, the reaction conditions, namely time, temperature and pressure, are desirably controlled so as to produce the desired hyperbranched oligomer. The final hyperbranched oligomer can be further characterized by the fact that at least 40 percent of the methine carbons are ethylene derivatives; and the average number of carbons per molecule is from 25 to 200, i.e. the molecular weight is the desired oligomer fraction is preferably from 350 to 2800. In particular embodiments, the "hyperbranched" product has at least 55 methine carbons. per thousand total carbons, and in more preferred embodiments, has at least 70 methine carbons per thousand total carbons. This level of branching is affected by both the incorporation of added alpha-olefins and the incorporation of in situ generated olefins. This fraction may conveniently be termed the "heavy" product.
    [049] Additional desired characteristics of the hyper-branched fluid produced include embodiments where it is an oligomeric grease having a pour point below 0°C, and embodiments where the oligomer grease has a pour point below -20°C, or less than -25oC, or less than -35oC, or less than -40oC.
    [050] The volatile organic product comprises one or more "light" oligomers, i.e. oligomers that are C14 and lower, which are removable by devolatilization so that not more than 10% by weight, preferably not more than 5% by weight. weight, remain with the hyper-branched product.
    [051] Since the thermal grease of the invention utilizes the hyper-branched fluid per se, it is desirable to devolatilize the product mixture to separate the hyper-branched and volatile organic product from one another, and thus recover the hyper-branched fluid. This devolatilization may be carried out using any conventional devolatilization means and methods, including, in non-limiting embodiments, use of extrusion reactors and/or kneading reactors, and methods including, for example, direct separation, bulk evaporation, and main evaporation. and/or direct devolatilization. In general, more severe devolatilization conditions will remove a greater proportion of the volatile organic product, which in general will tend to increase the flash point and reduce the pour point of the hyperbranched olefinic fluid. For purposes of the invention, the hyperbranched fluid is, in preferred embodiments, further hydrogenated in order to increase the oxidative stability of the product and lower the pour point.
    [052] It is important to note that the mechanism that occurs in the preparation of the hyperbranched fluids useful in the present invention is coordination insertion, in which monomers are added to a growth molecule through an organometallic center, such that a Molecular backbone is formed from carbons originating from unsaturated carbons in the monomer units. Thus, a coordination insertion oligomerization with ethylene alone will produce branches with almost exclusively equal numbers of carbons, and a coordination insertion co-oligomerization involving ethylene and an olefin with an odd number of carbons (N) will result in branches with an odd number of carbons (N) odd number of carbon atoms (N-2). This is different from "short-chain" which produces branches with a random distribution of even, odd numbers of carbons. In this way, those skilled in the art will understand without further directions how to distinguish these by 13C NMR.
    [053] It is further suggested here that the relatively high weight percentage of product that has methine branching carbons resulting from the coordination-insertion mechanism serves to ensure that most molecules are morphologically smaller and still have the same molecular weight, which results in reduced viscosity. As is well known to those skilled in the art, 13C NMR spectra can be analyzed to determine the following amounts: • Number of methine carbons per thousand total carbons • Number of methyl carbons per thousand total carbons • Number of vinyl groups per thousand total carbons• Number of vinylidene groups per thousand total carbons• Number of vinylene groups per thousand total carbons
    [054] Based on the results obtained from analyzing the 13C NMR spectra, the average number of carbons per molecule (Cn) can be determined using the following equation, which is based on the observation that each additional methine carbon, vinylidene group and vinylene results in an additional methyl carbon chain terminus:1000/Cn= methyl carbons - methine carbons - vinylidene groups - vinylene groups (Equation 2)
    [055] Alternatively, the average number of carbons per molecule (Cn) can be determined for cases where each oligomer molecule has a single unsaturation that occurs after chain termination. Exclusive terminal unsaturation is common when oligomerizations and polymerizations occur without the presence of added chain transfer agents, such as hydrogen or metal alkyls.1000/Cn= vinyl group + vinylidene group + vinylene group (Equation 3)
    [056] An alternative determination of the average number of carbons per molecule (Cn) can be achieved simply by averaging the two previous methods. The advantage of this method is that it no longer uses vinylidene and vinylene group levels and provides the correct Cn even when vinyls are not present. 1000/Cn= (methyl carbons-methine carbons + vinyl group)/2 (Equation 4)
    [057] Determining the average branching level, in terms of the number of branches per thousand (1,000) carbon atoms (Bc), is equal to the methine carbon count per thousand total carbons. Bc= methine carbons (Equation 5)
    [058] The average degree of branching, in terms of number of branches per oligomer molecule (Bn), can be determined by multiplying Bc and Cn and solving the thousand-carbon base.Bn= Bc * Cn/1000 (Equation 6 )
    [059] The determination of the molar fraction of oligomers with a vinyl group (Fv) is done as follows: Fv= (vinyl group) * Cn/1000 (Equation 7)
    [060] For the case where each molecule has a single unsaturation, Fv becomes: Fv= (vinyl group)/(vinyl group + vinylidene group + vinylene group) (Equation 8)
    [061] To determine the molar fraction of methine carbons that are derived from the ethylene feed rather than derived from the added alpha-olefin monomer, mass balance calculations can be performed. Those skilled in the art will be able to easily do this in the appropriate context with the process variables taken into account. However, for some cases of added alpha-olefin monomer, it is alternatively possible to measure or estimate this amount conservatively. (For higher proportions of propylene, it may be more convenient to employ equation 4 above). For example: (a) Added propylene monomer will result in methyl branches when incorporated into the oligomeric backbone. One skilled in the art can use 13C NMR spectral data to calculate the level of methyl branching per thousand carbons. Each methyl branch is expected to be accompanied by a methine carbon which is not derived from ethylene and/or propylene. Therefore, the calculation of the fraction of methine carbons derived from ethylene and/or propylene is given below: (b) Fraction of methines derived from ethylene=(methine carbons - methyl branches)/(methine carbons) (Equation 9)( c) The added hexene monomer will result in n-butyl branches when incorporated into the oligomeric backbone. One skilled in the art can use 13C NMR spectral data to calculate the level of n-butyl branching per thousand carbons. However, some n-butyl branching is expected to occur in the absence of added hexene as both chain ends and ethylene-derived branches. However, the assignment of all n-butyl branches to the added hexene incorporation results is a conservative estimate of ethylene-derived methine carbons as follows: Fraction of ethylene-derived methines=(methine carbons - n-butit branches )/(methine carbons) (Equation 10)
    [062] The most definitive determination of the methane fraction derived from ethylene is made using mass balance data around the oligomerization process. The mass balance data will indicate the net molar consumption of added monomer which can be a cumulative value for a semi-batch process or a rate value for a fully continuous process. The mass balance will also indicate the total moles of carbons as oligomers, which can be a cumulative value for a semi-batch process or a rate value for a fully continuous process: Net added monomer per thousand carbons=1000* (monomer added moles liquids)/(total moles of carbons as oligomers)(Equation 11)The fraction of ethylene-derived methines is then calculated in the same manner as methods using only 13C NMR data:Fraction of ethylene-derived methines= (methine carbons - net added monomer per thousand carbons)/(methine carbons)(Equation 12).
    [063] The number average molecular weight (Mn) of the hyperbranched oligomer produced by the inventive process desirably ranges from 350 Da to 2800 Da, more desirably from 350 Da to 1000 Da, and most desirably from 350 Da to 700 Da. This can be determined using conventional methods known to those skilled in the art, including gel permeation chromatography and gas chromatography. Furthermore, the determination of Mn from oligomers using 13C NMR techniques is possible, taking into account the fact that Mn is about 14 times the average number of carbons per molecule (Cn). The exact method used to relate 13C NMR data to Mn is affected by the choice of monomers, such as feeding branched and/or multi-unsaturated monomers. However, those skilled in the art will readily understand how recipe changes may require altering this 13C NMR method for measuring Mn.
    [064] Viscosity measurements can be performed, for example, on a BROOKFIELDTM CAP 2000+ viscometer with a 01 spindle. Approximately 70 microliters (μL) of the sample is added through a micropipette to the center of the plate which is held at 25° Ç. The spindle is placed on the sample and centrifuged at 1000 revolutions per minute (rpm) for 40 seconds until the viscosity measurement stabilizes. The instrument is calibrated to a Cannon Instruments viscosity standard of 203 centipoise (cP, 0.203 pascal * second, Pa * s) at 25°C. For high viscosity samples, the spin rate is reduced to 300 rpm or until the torque percentage drops between 50% and 75%.
    [065] Flash point measurements can be performed, for example, with an ERAFLASHTM instrument from ERA ANALYTICSTM with a high temperature accessory. An amount, 2 mL, of sample is added to the stainless steel sample cup via a micropipette and a stir bar is added. The sample cup and holder are placed in the sample chamber and the door is closed. Runtime parameters for ERAFLASHTM include: stirring rate = 100 revolutions per minute (rpm), heart rate = 10°C/min, with ignition every 2°C, temperature variation = 70°C, ignition time = 2 milliseconds , air volume = 10 mL between 150°C and 300°C. After each sample the chamber is cleaned and the electrodes are cleaned with a wire brush typically supplied by the manufacturer.
    [066] The process described for preparing the hyperbranched olefinic fluid results in particularly desirable rheological properties, including unexpectedly low viscosity for a given molecular weight, e.g. in some embodiments below 60 centipoise (cP, 0.06 pascal second, Pa*s) at room temperature. As noted, the hyper-branched product can also exhibit low pour point, in some embodiments below 25°C, and high flash point, in some embodiments above 200°C. In particular, the process can be relatively inexpensive to carry out, because it can use readily available, inexpensive starting materials, and can be carried out as a continuous or semi-batch process employing a conventional retromixed reactor. In particular, it employs one or more of the identified coordination insertion catalysts, selected from a group of catalyst families, and the catalyst can function efficiently and over a wide range of thermal operation, in some non-limiting embodiments withstanding temperatures. that exceed 200°C.
    [067] More details regarding such hyper-branched oils and greases can be found in the previously referenced copending patent application, PCT/US2014/043754, entitled "Ethylene-Based Oils and Greases", Attorney No. 73437-WO -PCT, filed on June 24, 2014, claiming the benefit of Provisional Application 61/840,622, filed on June 28, 2013.
    [068] In summary, the thermal grease compositions of the invention, comprising one or more of the hyperbranched olefinic fluids as defined, exhibit desirable properties including viscosity and dispensing properties. As defined herein, dispensing is a subjective judgment of the workability exhibited by thermal grease when bonded using a spreading tool. Grease is judged here based on the feel of the spread resistance and by looking at the degree of homogeneity of its spread coating appearance. As illustrated in the Examples section below, in many cases the thermal conductivity of the thermal grease compositions of the invention can be superior to that of thermal greases that are otherwise comparable but which contain only a silicone oil matrix. Furthermore, the thermal grease compositions of the invention may exhibit superior thermal resistance when compared to such purely silicone oil matrix greases. As described above, such grease compositions can desirably exhibit high flash points and desirably low pour points, thus allowing their use in applications that require a relatively wide operating temperature. They may have a reduced tendency, compared to silicon oil-based greases, to migrate and therefore contaminate their environments, thus making them more desirable for electronic applications in particular. Furthermore, the thermal grease compositions of the invention are, in many embodiments, less expensive to produce and, therefore, likely to be priced lower on the market.
    [069] The following examples and comparative examples serve to illustrate certain embodiments of the invention and are therefore not intended to limit its scope in any way.Example 1 and Comparative Example 1
    [070] Thermal grease samples are prepared, with a first series serving as inventive samples (Example 1a-1f), based on a hyper-branched olefinic fluid and the second serving as comparative samples (Comparative Example 1a'-1f') based on a silicone oil.Preparation of an ethylene-based hyperbranched olefinic fluid
    [071] In order to prepare a suitable hyper-branched ethylene-based olefinic fluid, feeds comprising ethylene, ISOPAR-E™ as a solvent and toluene (as a solvent to dissolve the catalyst) are passed through columns of activated alumina and Q-5 to first remove water and oxygen from them. These feeds are then introduced into an adiabatic continuous stirred tank reactor (CSTR), with typical CSTR back mixing, with the solvent (toluene), catalyst (Formula V) and activator (ISOPAR-ETM) being introduced into the reactor through lines of stainless steel syringe pumps located in a glove-insulated box containing a nitrogen atmosphere. Ethylene and catalyst solution are introduced through separate dip tubes and measured with the aid of mass flow controllers. The reaction is allowed to proceed at a temperature of 60°C, with a residence time of 10 minutes, a C2 feed rate of 1.00 g/min, and a C2 monomer feed mass fraction of 0. 14 (C2 feed rate/total feed rate).
    [072] The container is heated by circulating hot silicone oil through the outer shell and cooled when necessary through an internal cooling coil with water. Reactor pressure is controlled with a GO REGULATORTM BP-60 back pressure regulator. The system runs hydraulically filled with no headspace and without a devolatilization unit. Polymer solutions are removed from the vessel for periodic sampling from an outlet at the top of the reactor equipped with an electrically heated stainless steel line. The olefin concentrations of the reactor effluent solution are then measured using a Fourier Transform Near Infrared (FT-NIR) spectrometer to determine the concentration in the ethylene reactor. Further product analyzes are performed by 13C NMR as described below.
    [073] Once the desired reaction endpoint is reached, the hyper-branched olefinic fluid is treated, prior to collection, with a catalyst deactivator comprising 2-propanol with water and a stabilizing pack containing IRGANOX™ 1010, tetrakis pentaerythritol (3 ,5-di-tert-butyl-4-hydroxyhydrocinnamate), and IRGAFOS™ 168, tris(2,4-di-tert-butylphenyl) phosphite from CIBA GEIGY CORPORATION™. Multiple runs are performed on the CSTR and the oligomeric fractions are all combined. The oligomers are first rotary evaporated at 80°C/10 Torr to remove solvent, then passed through a cleaning film evaporator (WFE) set at 155°C/100 mTorr. WFE products are collected and tested for viscosity. Among the products, those designated as "light" are generally residual solvent molecules and light product that tend to degrade the flash points and fire points of the material, while "heavy" are all other products that comprise the olefinic fluid. hyper-branched to be used in the manufacture of a thermal grease. The kinematic viscosity, (at 40°C/100°C, according to ASTM D445) is 0.0003494/0.0000660 m2/s (34.94/6.60 (cSt)). The samples are not hydrogenated, as may be desirable on a commercial scale for product stability, and an olefinic unit remains for each oligomeric chain.
    [074] The test is performed to determine the flash point and pour point of the base, or matrix, hyper-branched olefinic fluid and also a selected silicone-based matrix, as described below. In general, physical properties such as the flash point and pour point of the final thermal grease tend to be reasonably correlated with the same properties of the matrix fluid, so their determination can be performed on the fluid in the absence of fillers. for convenience. It is also noted, however, that while the fire point is always higher than the flash point, it is not always predictable how much higher it will be. However, since flash point determination generally requires a smaller sample, it is often used instead of flash point determination for experimental purposes.
    [075] Flash point: Measurements are made on an ERAFLASHTM instrument from ERA ANALYTICSTM with a high temperature accessory. This method follows ASTM D93 for a closed cup flash point measurement. In this protocol, 2 mL of sample is added to the stainless steel sample cup via a micropipette and a stir bar is added. The sample cup and holder are placed in the sample chamber and the door is closed. Runtime parameters for ERAFLASHTM include: stirring rate = 100 rpm, heating rate = 10 oC/min, Step = 2 oC temperature variation = 70 oC, ignition = 2 milliseconds (ms), air volume = 10 mL /min between 150 °C and 300 °C. After each sample, the chamber is cleaned and the electrodes are cleaned with a wire brush supplied by the manufacturer.
    [076] Pour point: In a 48-well plate with vials, 1 mL of sample is added to each vial, followed by a copper BB. This method follows ASTM D455. Measurements are performed in triplicate and measurement is based on two agreements. A rubber mat is placed on top of the samples and the 48-well plate is placed in a temperature-programmed freezer. After a minimum of 4 h, samples are removed and turned into a scanner. Samples are allowed to stand for 1 min and then scanned, with the image being used to determine whether copper BB is apparent in the scanned image. This serves as a pass/fail test. The freezer temperature is then changed and the procedure repeated until the desired level of pour point resolution is reached.
    [077] Table 1 shows the experimental conditions that are used in the synthesis of the hyper-branched, ethylene-based olefinic fluid for Example 1, for each of the runs. In this case, the catalyst corresponds to Formula V. Table 1. Typical experimental conditions for hyperbranched ethylene-based fluid synthesis
    *μmol/min =micromols per minute
    [078] For confirmations of 13C NMR, samples are dissolved in 10 millimeters (mm) NMR tubes in d-chloroform with 0.02 M chromium(III) acetyl acetonate (Cr(AcAc)3, C15H21CrO6, tris( 2-4-pentanedione)-chromium(III)) is added. Typical concentration is 0.50 g/2.4 ml. The tubes are then heated in a heating block set at 50°C. The sample tubes are repeatedly vortexed and heated to obtain a smooth, flowing fluid. For samples with visible wax present, d2-tetrachloroethane is used as a solvent instead of d-chloroform and the sample preparation temperature is 90°C. 13C NMR spectra are taken on a 400 megahertz (MHz) BRUKERTM AVANCETM spectrometer equipped with a 10 mm cryoprobe. The following acquisition parameters are used: 5 second relaxation delay, 13.1 microsecond 90 degree pulse, 256 scans. The spectra are centered at 80 ppm, with a spectral width of 250 ppm. All measurements are performed without sample wiring at 50oC (for chloroform solutions) or 90oC (for tetrachloroethane solutions). 13 C NMR spectra are referenced at 77.3 ppm for chloroform or 74.5 ppm for tetrachloroethane. The results of the analysis of the 13C NMR spectra are provided in Table 2. Table 2. Analysis of the 13C NMR results of the hyperbranched olefinic fluid
    Mn is the number average molecular weight
    [079] Table 3 shows a comparison of the flash point and pour point of the ethylene-based hyperbranched olefinic fluid of Example 1 and, as Comparative Example 1, a selected silicone-based fluid. Table 3. Comparison flash point and pour point of hyper-branched olefinic fluid and silicone-based fluid
    * A 50/50 volume % mixture of Dow Corning 510TM fluid (phenylmethyl polysiloxane) with a viscosity of 0.0001 m2/s (100 cSt) and the same fluid having a viscosity of 0.00005 m2/s (50 cSt).B. Preparation of thermal greases
    [080] The matrix hyper-branched olefinic fluid or selected silicone oil is first weighed into a ceramic cylinder cup. The surfactant, SPANTM 85, used only with hyper-branched fluid to overcome polarity problems that tend to reduce the homogeneity of the grease, is weighed and added to the matrix and the mixture is stirred with a metal spatula until the surfactant is completely mixed into the matrix. . The thermally conductive fillers are weighed and pre-mixed by dramatic manual agitation. The fillers are then added to the ceramic cylinder cup and dispersed into the matrix mixture by sufficient agitation and kneading with a metal spatula until the matrix visually appears to have completely wetted the surface of the filler and the composite appears as a mixture. even and smooth. Agitation is carried out at approximately 100 revolutions per minute (rpm) for three times, each time for at least 10 minutes to ensure good visual homogeneity. The resulting thermal greases are transferred inside and stored in stoppered glass bottles. The greases prepared have the constituents indicated in Table 4. Table 4. Constituents of thermal grease compositions for Examples 1a-1f and Comparative Examples 1a'-1f'Component Specifications Supplier
    * These are matrix materials. Only one is used for any given formulation.* *Dow Corning's 510TM fluid is polyphenylmethyldimethylsiloxane, which is a clear, heat-stable silicone fluid.* **SPANTM 85 is a surfactant (sorbitan trioleate) that is used only with the formulation olefinic fluid based hyper-branched thermal grease.* *** WLS, AX3-75, AX35-125, AX10-32, Nano-ZnO and ASFT-20 are trade names of listed suppliers.D50 = MMD, mass of mean diameter, mean particle diameter by mass; D100 = maximum particle diameter, in mass.
    [081] After the formation of greases after incorporation of all the constituents shown in Table 5, the test is done to determine the thermal conductivity (TC), the shear viscosity and the thermal resistance. Testing is also done on a commercially available thermal grease called Z9TM, available from DEEPCOOLTM. The methodology of this test is described as follows.
    [082] Thermal conductivity (TC): The thermal conductivity (W/mK) of thermal grease samples is measured with a HOT DISKTM instrument (TPS 2500S, transient plane source), available from HOT DISK ABTM, Sweden, according to ISO 220072:2008 standard. For these grease samples, measurement is done with a HOT DISKTM sensor (3.2 mm, mm, radius) in a liquid cell. The experimental parameters used to collect the data are: Temperature 24 oC, Power 0.2 watt (W), and Time 2 s.
    [083] Frequency scan test for viscosity: Shear viscosity is measured at 25°C on 25 mm parallel steel plates of an AR2000EXTM tension-controlled rheometer, available from TA INSTRUMENTSTM. The shear rate is adjusted from 0.1/s to 5/s and the test duration is 10 min. The value in 1.1/s is recorded and used for comparison. The test is performed according to the modified ASTM D4440-08 protocol.
    [084] Thermal Resistance: Thermal grease samples are evaluated for thermal resistance by LW-9389TM Appliances, available from LONG WIN SCIENCE AND TECHNOLOGY CORPORATIONTM, in compliance with ASTM D5470-06 standard. Test conditions include: Constant Tavg (average temperature of the hot and cold interface between the sample and the thermosensor) 60 oC, Contact pressure 137.90, 275.80, 551.58 kPa (20, 40, 80 psi), Array Area 6.4516 cm2, Test Duration - 30 min.
    [085] Table 5 presents formulations and test results.
    [086] Examples 1a to 1f and comparative examples 1a' to 1f' shown in Table 5 illustrate differences in performance of thermal greases based on hyper-branched ethylene based fluids compared to those based on a mixture at 50°C. /50% by volume of phenylmethylpolysiloxane fluids with two different viscosities. The phenylmethylpolysiloxane mixture is selected to obtain a material with a viscosity comparable to that of the base hyperbranched olefinic fluid. SPANTM 85 surfactant is used for Examples 1a to 1f only and is intended to compensate for the higher polarity of the hyperbranched material to ensure comparable dispersion of the thermally conductive filler. Table 5. The formulations and performance results of Examples la-lf and Comparative Examples la'-lf'.
    —indicates that data was not obtainedN/A indicates that grease could not be formed
    [087] As can be seen, Example 1a of the invention has a higher thermal conductivity than Comparative Example 1a. In Inventive Example 1b and Comparative Example 1b', the AlN loading is increased to 71.3% by volume, which leads to different performance results. Example 1b of the Invention is described as a "good" thermal grease, having relatively low viscosity and higher thermal conductivity, whereas Comparative Example 1b' cannot form a grease due to its much higher viscosity. This is characterized by the fact that the sample cannot be glued. This is because while the hyper-branched olefinic fluid and phenylmethyl-polysiloxane base matrices have nearly the same viscosity, the hyper-branched olefinic fluid system can accommodate more load to achieve higher thermal conductivity.
    [088] It is also noteworthy that the matrices of Example 1c and Comparative Example 1c' of the invention have similar appearance and viscosity adaptation for Al2O3 spherical system (35 μm:3 μm = 7:3) at a load level of 75% by volume. However, the thermal conductivity of Inventive Example 1c is slightly higher than that of Comparative Example 1c'.
    [089] In order to simulate applications with thin gaps, i.e. small bond line thickness (BLT), examples 1d to 1f of the invention and comparative examples 1d'to 1f' use smaller cut point size (i.e. D100). The primary thermally conductive filler for each is spherical Al2O3 (D50=10 μm, D100=32 μm). A submicron filler (ZnO and spherical Al2O3) is also used in combination. As in Examples 1a to 1b and Comparative Examples 1a' to 1b' of the invention, it is observed that the hyperbranched olefinic fluid matrix can incorporate more filler than the phenylmethyl-polysiloxane matrix, resulting in higher conductivity. thermal grease for hyper-branched olefinic fluid based thermal grease. It is also noted that both Inventive Example 1d and Comparative Example 1d' exhibit good gluing and adhesion properties, which would be useful in practical application.
    [090] Thermal resistance results show that Example 1d of the invention has a relatively low thermal resistance of 0.028 degrees Celsius square inches per watt (oC-in2/W) at a relatively low contact pressure load of 137.9 kilopascals, approximately kPa (20 pounds per square inch (psi), ). Thus, low mounting pressure is permissible for the use of such a grease. For comparison, the product data sheet for Z9TM, available from DEEPCOOLTM, states that the commercial silicone oil-based product has a thermal resistance of less than or equal to 0.058 oC-in2/W, which would be defined as a result of inferior performance. EXAMPLE 2 and COMPARATIVE EXAMPLE 2
    [091] Two sets of thermal greases are prepared, the first including a hyper-branched olefinic fluid, based on ethylene and propylene as Component A of matrix, and the second including only a silicone fluid, phenylmethylpolysiloxane, as component A of matrix.A. The preparation of the ethylene and propylene-based hyper-branched olefinic fluid is conducted in a 2 L Parr™ batch reactor on a semi-batch basis. The reactor is heated by an electrical heating mantle and cooled by an internal cooling coil containing cooling water. Both the reactor and the heating/cooling system are controlled and monitored by a processing computer. CAMILETM TG. The bottom of the reactor is equipped with a dump valve, which empties the contents of the reactor into a stainless steel (SS) dump vessel, which is pre-filled with a catalyst quench solution (typically 5 mL of an IRGAFOXTM/ IRGANOXTM toluene mixture). The flush pot is vented to a 30 liter flush tank, both the pot and the tank purged with N2. All chemicals used for polymerization or catalyst composition are passed through purification columns to remove any impurities that could affect polymerization. The propylene is passed through 2 columns, the first containing alumina A1204, the second containing reagent Q5 to remove oxygen. Ethylene is also passed through 2 columns, the first containing A1204 alumina and 4 Angstrom (Â) pore size molecular sieves, containing the second reagent Q5. The N2, used for transfers, is passed through a single column of A1204 alumina, 4 µ pore size molecular sieves and reagent Q5.
    [092] The reactor is loaded first with toluene and then with propylene to the desired reactor load. The reactor is charged first with toluene and then with propylene to the desired reactor charge. When ethylene is used, it is added to the reactor when at reaction temperature to maintain the reaction pressure set point. The amounts of ethylene addition are monitored by a micromotion flow meter.
    [093] The catalyst and activators are mixed with the appropriate amount of purified toluene to obtain a solution of desired molarity. Catalyst and activators are handled in an insulated box with inert gloves, introduced into a syringe and transferred by pressure to the catalyst injection tank. This is followed by 3 toluene washes, 5 mL each.
    [094] Immediately after adding catalyst the run timer starts. When using ethylene, it is then added by CAMILETM to maintain the reaction pressure setpoint in the reactor. These polymerizations are carried out for the desired amount of time, then the stirrer is stopped and the bottom discharge valve opened to discharge the contents of the reactor into the discharge vessel. The contents of the dump container are poured into trays placed in a laboratory compartment where the solvent is evaporated overnight. The trays containing the remaining polymer are then transferred to a vacuum oven, where they are heated to 140°C under vacuum to remove any remaining solvent. After the trays have cooled to room temperature, the oligomers are weighed for yield/efficiencies and tested.Table 6. Reactor parameters
    * RIBS-2 co-catalyst: (CAS); Amines, bis(hydrogenated tallow alkyl) methyl, tetrakis(pentafluorophenyl)borate(1-)** The co-catalyst of MMA0-3A is a modified methyl aluminoxaneTable 7. Characterization of hyperbranched olefinic fluid data

    [095] This is performed as in Example 1, with the parameters shown in Table 6, with the exception that the propylene comonomer is included as a feed, with a C3 feed rate of 1.00 g/min, and a fraction of C3 monomer feed mass of 0.14 (C3 feed rate/total feed rate). The resulting hyperbranched olefinic fluid exhibits the characteristics shown in Table 7. The catalyst corresponds to Formula X.
    [096] After the preparation of the ethylene and propylene-based hyperbranched olefinic fluid and selection of the silicone-based matrix for the Comparative Example 2 grease, the matrix fluids are tested to determine flash points and pour points, using the procedures described in Example 1 and Comparative Example 1. The results of this test are shown in Table 8. Table 8. Flash point and pour point of thermal greases
    *A 50/50% by volume mixture of Dow Corning 510TM fluid (phenylmethyl polysiloxane) with a kinematic viscosity of 0.0001 m2/s (100 cSt) and the same fluid having a kinematic viscosity of 0.00005 m2/s ( 50 cSt). B. Examples 2a to 2c and Comparative Example 2a' to 2c' are prepared having the constituents provided in Table 4 and using the methodology described in Example 1 and Comparative Example 1. Table 9 presents formulations and test results. Table 9. The formulations and performance results of Examples 2a-2c and Comparative Examples 2a'-2c'.
    *Watt/meter*Kelvin
    [097] It will be seen from Table 9 that Example 2a of the invention exhibits higher thermal conductivity than Comparative Example 2a' when using AlN as the thermally conductive filler. Based on other filler packages, higher thermal conductivity is also achieved using hyper-branched ethylene-propylene fluid as the matrix than is using phenylmethylpolysiloxane as the matrix. This in Example 2b and 2c, which are compared with Comparative 2b' and 2c'.
    权利要求:
    Claims (7)
    [0001]
    1. Thermal grease composition, characterized in that it comprises a mixture of: (a) an ethylene-based or ethylene-propylene-based hyperbranched olefinic fluid having an average of at least 1.5 methine carbons per oligomer molecule , and having at least 40 methine carbon atoms per thousand total carbons, the average number of carbon atoms per molecule being from 25 to 200; and (b) a thermally conductive filler.
    [0002]
    2. Thermal grease composition, according to claim 1, characterized in that the ethylene-based or ethylene-propylene-based hyperbranched olefinic fluid has at least one of: (a) a flash point of 180 oC or greater, as measured in accordance with ASTM D-93; (b) a pour point of zero oC or less, as measured in accordance with ASTM D-97; (c) a kinematic viscosity at 40 oC, such as as measured in accordance with ASTM D-445, not more than 0.0002 square meters per second; and (d) a combination thereof.
    [0003]
    3. Thermal grease composition, according to claim 1, characterized in that the ethylene-based or ethylene-propylene-based fluid further comprises an alpha-olefin comonomer other than propylene.
    [0004]
    4. Thermal grease composition, according to claim 1, characterized in that the thermally conductive filler is selected from beryllium oxide, aluminum nitride, boron nitride, aluminum oxide, zinc oxide, magnesium oxide , silicon carbide, silicon nitride, silicon dioxide and zinc sulfide; solid metal particles selected from silver, copper or aluminum; carbon materials selected from diamond powder; carbon fibers, carbon black, graphite, carbon nanotubes, graphene and graphene oxide; liquid metals, selected from gallium-based alloys; and combinations thereof.
    [0005]
    5. Thermal grease composition, according to claim 1, characterized in that it further comprises a phase segregator, a surfactant, a flame retardant, an antioxidant, a coupling agent, a bleeding inhibiting agent, a rheology, a filler or a combination thereof.
    [0006]
    6. Thermal grease composition, according to claim 5, characterized in that the phase segregator is a compound selected from polydimethylsiloxane; vinyl methyl polysiloxane; hydroxyl terminated polydimethylsiloxane; polydimethyldiphenylsiloxane; polydiphenylsiloxane; methyl-alkyl-polysiloxanes containing an alkyl group selected from a naphthyl group, an ethyl group, a propyl group or an amyl group; and their combinations.
    [0007]
    7. Process for preparing a thermal grease composition, as defined in claim 1, characterized in that it comprises: (a) contacting ethylene and optionally propylene and, further, optionally, an alpha-olefin, and at least one catalyst insertion coordination, the insertion coordination catalyst being a metal-ligand complex, the metal being selected from zirconium, hafnium and titanium, and having an ethylene/octene reactivity ratio of up to 20, and a length chain kinetics of up to 20 monomer units; in a continuously fed backmixed reactor zone under conditions such that a mixture of at least two products is formed, the mixture including: (i) a hyperbranched oligomer having an average of at least 1.5 methine carbons per oligomer molecule, and having at least 40 methine carbon atoms per thousand total carbons, with at least 40 percent of the methine carbons being derived from ethylene, or, where propyl optional is included, from ethylene and propylene, the average number of carbon atoms per molecule being from 25 to 200; and (ii) at least one volatile organic product having an average number of carbons per molecule that is less than or equal to 14; (b) separating the hyper-branched oligomer from the volatile organic product; (c) recovering the hyper-branched oligomer; and (d) mixing the hyperbranched oligomer and a thermally conductive filler to form a thermal grease composition.
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    法律状态:
    2019-08-13| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-08-03| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|
    2021-11-23| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2022-01-25| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 22/09/2014, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    PCT/CN2014/087083|WO2016044975A1|2014-09-22|2014-09-22|Thermal grease based on hyperbranched olefinic fluid|
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