Thermally conductive compositions

Abstract

Embodiments of the present disclosure are directed towards thermally conductive compositions including a urethane / acrylic telechelic polymer, a thermally conductive filler, and an amine.

Description

THERMALLY CONDUCTIVE COMPOSITIONSField of Disclosure

[0001] Embodiments of the present disclosure are directed towards thermally conductive compositions.Background

[0002] Thermal interface materials (TIMs) such as gap fillers, adhesives, and gels can be used for thermal management in electronics and automotive applications. For example, electric vehicle (EV) batteries are cooled by mounting one or more battery modules to a cooling plate that redirects heat. TIMs can be utilized for batteries, as well as other applications. The particular combination of thermal conductivity and adhesion provided by TIMs can help batteries to disperse heat, and at the same time maintain the battery modules in place.Summary

[0003] The present disclosure provides various embodiments, including the following. In some embodiments, the present disclosure relates to a thermally conductive composition including: a urethane / acrylic telechelic polymer; a thermally conductive filler; and an amine.

[0004] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list.Detailed Description

[0005] Thermally conductive compositions are disclosed herein. Thermally conductive compositions include an A Side, which may also be referred to as a urethane / acrylic telechelic polymer composition, and a B side, which may be referred to as an amine composition.

[0006] Advantageously, the thermally conductive compositions disclosed herein have a low NCO %, e.g. less than 0.1 NCO %. Providing a low NCO % is desirable for a number of applications, and may even be a requirement in some instances, e.g., some manufacturing process. The low NCO % may be helpful in reducing health risks that may be associated with some other relatively higher NCO % materials.

[0007] Advantageously, the thermally conductive compositions disclosed herein provide a desirable thermal conductivity. For instance, embodiments provide that the thermally conductive compositions can provide a thermal conductivity greater than 0.5 Wm1K1. Such thermal conductivities are useful for a number of applications, such as battery applications, whereby the desirable thermal conductivities can help to disperse heat.

[0008] Advantageously, the thermally conductive compositions disclosed herein provide a desirable adhesion property, e.g., Pull Force as discussed further herein. Such adhesion properties are useful for a number of applications, such as battery applications, whereby the desirable adhesion properties can help to maintain placement of battery cells and / or modules. Further advantageously, the thermally conductive compositions disclosed herein can provide adhesion to both plastics and metals for a wide range of adhesion strength.

[0009] As mentioned, the thermally conductive compositions include an A Side, which may also be referred to as a urethane / acrylic telechelic polymer composition. The A Side includes a urethane / acrylic telechelic polymer.

[0010] The urethane / acrylic telechelic polymer can be made by reacting one or more polyols and one or more diisocyanates to form an NCO prepolymer and thereafter reacting with NCO prepolymer with an acrylate. The acrylate can be a hydroxyacrylate.

[0011] The polyol can have an average hydroxyl functionality from 1 .9 to 6. All individual values and subranges from 1 .9 to 6 are included; for example, the polyol can have an average hydroxyl functionality from a lower limit of 1 .9, 2.0, or 2.1 to an upper limit of 3, 4, or 6. One or more embodiments provide that the polyol has an average hydroxyl functionality of 3.0.

[0012] The polyol can have an average hydroxyl number from 20 to 150 mg KOH / g. All individual values and subranges from 20 to 150 mg KOH / g are included; for example, the polyol can have an average hydroxyl number from a lower limit of 20, 35, 45, or 50 mg KOH / g to an upper limit of 150, 85, 75, or 65. Average hydroxyl number can be determined according to ASTM D4274.

[0013] The polyol can have a number average molecular weight from 500 to 5,000 g / mol. All individual values and subranges from 500 to 5,000 g / mol are included; for example, the polyol can have a number average molecular weight from a lower limit of 500, 1000, 2,000, or 2,500 g / mol to an upper limit of 5,000, 4,500, 4,000, or 3,500 g / mol. Number average molecular weight can be determined by GPC.

[0014] The polyol can be obtained commercially. A commercial example of the polyol is VORANOL 3003 LM from The Dow Chemical Company, among other commercial polyols.

[0015] Combinations of various polyols can be utilized.

[0016] Examples of diisocyanates include m-phenylene diisocyanate, toluene-2,4- diisocyanate, toluene-2,6-diisocyanate, hexamethylene-1 ,6-diisocyanate, tetramethylene-1 ,4-diisocyanate, cyclohexane-1 ,4-diisocyanate, hexahydrotoluene diisocyanate, naphthylene-1 ,5-diisocyanate, methoxyphenyl-2,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4’-diisocyanate, hydrogenated diphenylmethane-4,4’-diisocyanate, hydrogenated diphenylmethane- 2,4’-diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl-4-4'-biphenyl diisocyanate, 3,3'-dimethyldiphenyl methane-4,4'-diisocyanate, and mixtures thereof. One or more embodiments provide that the diisocyanate is toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, or a combination thereof. Toluene-2,4-diisocyanate, toluene-2,6-diisocyanate and combinations thereof can generically be referred to as toluene diisocyanate (TDI).

[0017] The diisocyanate can be obtained commercially. A commercial example of the diisocyanate is VORANATE T-80 Type 1 TDI from The Dow Chemical Company, among other commercial diisocyanates.

[0018] Combinations of various diisocyanates can be utilized.

[0019] The polyol and the diisocyanate can be reacted in the presence of a catalyst and an acidifying agent. The catalyst can promote a urethane (polyolisocyanate) reaction. Catalysts that can promote the urethane reaction, which may be referred to urethane promotion catalysts, are known. An example of a catalysts that can promote the urethane reaction is dibutyltin dilaurate. Acidifying agents are known. An example of an acidifying agent is benzoyl chloride. The reaction process may utilize known equipment and known reaction conditions.

[0020] When reacting the polyol and the diisocyanate, the polyol can be from 10 to 90 weight percent (wt%) based on a total weight of a combination of the polyol, the diisocyanate, the catalyst, and the acidifying agent. All individual values and subranges from 10 to 90 wt% are included; for example, the polyol can be from a lower limit of 10, 15, or 20 wt% to an upper limit of 90, 80, 75, 70, or 65 wt% based on the total weight of the combination of the polyol, the diisocyanate, the catalyst, and the acidifying agent.

[0021] When reacting the polyol and the diisocyanate, the diisocyanate can be from 10 to 90 wt% based on a total weight of a combination of the polyol, thediisocyanate, the catalyst, and the acidifying agent. All individual values and subranges from 10 to 90 wt% are included; for example, the diisocyanate can be from a lower limit of 10, 25, 30, or 35 wt% to an upper limit of 49, 47, or 45, 90 wt% based on the total weight of the combination of the polyol, the diisocyanate, the catalyst, and the acidifying agent.

[0022] When reacting the polyol and the diisocyanate in the presence of the catalyst and the acidifying agent, the catalyst can be from 0.001 to 0.100 wt% based on a total weight of a combination of the polyol, the diisocyanate, the catalyst, and the acidifying agent. All individual values and subranges from 0.001 to 0.100 wt% are included; for example, the catalyst can be from a lower limit of 0.001 , 0.005, or 0.010 wt% to an upper limit of 0.100, 0.050, or 0.030 wt% based on the total weight of the combination of the polyol, the diisocyanate, the catalyst, and the acidifying agent.

[0023] When reacting the polyol and the diisocyanate in the presence of the catalyst and the acidifying agent, the acidifying agent can be from 0.0001 to 0.1 wt% based on a total weight of a combination of the polyol, the diisocyanate, the catalyst, and the acidifying agent. All individual values and subranges from 0.0001 to 0.0100 wt% are included; for example, the acidifying agent can be from a lower limit of 0.0001 , 0.0005, or 0.0010 wt% to an upper limit of 0.0100, 0.0500, or 0.0100 wt% based on the total weight of the combination of the polyol, the diisocyanate, the catalyst, and the acidifying agent.

[0024] The NCO prepolymer can have an NCO % from 1 to 25%. All individual values and subranges from 1 to 25% are included; for example, the NCO prepolymer can have an NCO % from a lower limit of 1 , 2, or 6% to an upper limit of 25, 20, or 14%. NCO% can be determined by ASTM D5155.

[0025] As mentioned, the NCO prepolymer can be reacted with an acrylate to make the urethane / acrylic telechelic polymer. Examples of the acrylate include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and combinations thereof. One or more embodiments provide that that acrylate is hydroxyethyl acrylate.

[0026] The NCO prepolymer and the acrylate can be reacted in the presence of a catalyst and a stabilizer. An example of a commercially available catalyst is DABCO 33 LV from Evonik. Several catalysts such as amines and organometallic compounds can be used a catalyst for reacting the NCO prepolymer with the acrylate. An example of a stabilizer is methyhydroxyquinone. The reaction process may utilize known equipment and known reaction conditions.

[0027] When reacting the NCO prepolymer and the acrylate, the NCO prepolymer can be from 50 to 95 wt% based on a total weight of a combination of the NCO prepolymer, the acrylate, the catalyst, and the stabilizer. All individual values and subranges from 50 to 95 wt% are included; for example, the NCO prepolymer can be from a lower limit of 50, 60, or 70 wt% to an upper limit of 95, 85, or 80 wt% based on the total weight of the combination of the NCO prepolymer, the acrylate, the catalyst, and the stabilizer.

[0028] When reacting the NCO prepolymer and the acrylate, the acrylate can be from 5 to 50 wt% based on a total weight of a combination of the NCO prepolymer, the acrylate, the catalyst, and the stabilizer. All individual values and subranges from 5 to 50 wt% are included; for example, the acrylate can be from a lower limit of 5, 10, 15, or 20 wt% to an upper limit of 50, 40, or 30 wt% based on the total weight of the combination of the NCO prepolymer, the acrylate, the catalyst, and the stabilizer.

[0029] When reacting the NCO prepolymer and the acrylate, the catalyst can be from 0.05 to 2 wt% based on a total weight of a combination of the NCO prepolymer, the acrylate, the catalyst, and the stabilizer. All individual values and subranges from 0.05 to 2 wt% are included; for example, the catalyst can be from a lower limit of 0.05, 0.01 , or 0.2 wt% to an upper limit of 2, 1 .5, or 1 wt% based on the total weight of the combination of the NCO prepolymer, the acrylate, the catalyst, and the stabilizer.

[0030] When reacting the NCO prepolymer and the acrylate, the stabilizer can be from 0.001 to 1 wt% based on a total weight of a combination of the NCO prepolymer, the acrylate, the catalyst, and the stabilizer. All individual values and subranges from 0.001 to 1 wt% are included; for example, the stabilizer can be from a lower limit of 0.001 , 0.005, or 0.010 wt% to an upper limit of 1 , 0.5, or 0.1 wt% based on the total weight of the combination of the NCO prepolymer, the acrylate, the catalyst, and the stabilizer.

[0031] As mentioned, the A Side includes the urethane / acrylic telechelic polymer. The urethane / acrylic telechelic polymer can be from 0.01 to 50 wt% of the A Side based on a total weight of a combination of A Side components. All individual values and subranges from 0.01 to 50 wt% are included; for example, the urethane / acrylic telechelic polymer can be from a lower limit of 0.01 , 0.05, or 0.09 wt% to an upper limit of 50, 40, or 20 wt% of the A Side based on the total weight of the combination of A Side components.

[0032] The A Side includes one or more thermally conductive fillers, e.g., an A Side thermally conductive filler. Fillers disclosed herein may have a thermalconductivity of at least 1 W / m-K, at least 5 W / m-K, or at least 20 W / m-K, and may have a thermal conductivity of less than 1000 W / m-K, or less than 100 W / m-K. Fillers disclosed herein may be low density and low hardness to reduce overall weight of the composition and reduce weight in automotive, EV, and reduce abrasiveness of the composition. Different thermally conductive fillers may be utilized for different applications. The thermally conductive filler can be an inorganic thermally conductive filler. The thermally conductive filler can be aluminum hydroxide, aluminum oxide, aluminum nitride, boron nitride, or combinations thereof. One or more embodiments provide that the thermally conductive filler is aluminum trihydroxide, aluminum trihydrate, or ATH.

[0033] The thermally conductive filler can be from 50 to 95 wt% of the A Side based on a total weight of a combination of A Side components. All individual values and subranges from 50 to 95 wt% are included; for example, the thermally conductive filler can be from a lower limit of 50, 75, or 80 wt% to an upper limit of 95, 93, or 90 wt% of the A Side based on the total weight of the combination of A Side components.

[0034] As used herein, the term “average particle size” refers to the median particle size, e.g., diameter, of a distribution of particles as determined for example, by a Multisizer 3 Coulter Counter (Beckman Coulter, Inc., Fullerton, CA) according to the procedure recommended by the manufacturer. The average particle size may be estimated based on measuring the surface area according to 8-11 ASTM D4315 or by using sieves of various mesh sizes and calculating the average from the cumulative weight of each size fractions. The median particle size, D5Q is defined as the size wherein 50 volume % of the distribution is smaller than the stated value, Dgg is defined as the size wherein 90 volume % of the distribution is smaller than the stated value. D-|o is defined as the size wherein 10 volume % of the distribution is smaller than the stated value. Particle size distribution can be determined by known methods in the art such as ASTM B822-10 or ASTM B822-20 or ISO 13320 using appropriate suspending medium or in dry state.

[0035] The average D5Q particle size for the thermally conductive fillers discussed herein may be in the range of from 0.05 pm to 500 pm, from 0.1 pm to 300 pm, from 0.5 pm to 100 pm, or from 0.5 pm to 50 pm. The average Dgg particle size for the thermally conductive fillers discussed herein may be in the range of from 0.05 pm to 500 pm, 1 pm to 300 pm, 5 pm to 200 pm, or 10 pm to 150 pm. The average D-| Qparticle size for the thermally conductive fillers discussed herein may be in the range of from 0.05 pm to 30 pm, 0.08 pm to 10 pm, 0.1 pm to 10 pm.

[0036] The A Side can include a plasticizer, e.g., an A Side plasticizer. Examples of plasticizers include butylcarbitol adipate, hexadecyltrimetoxysilane, diisononyl phthalate (DINP), dioctyl adipate, isodecyl succinate, diethylene glycol dibenzoate, pentaerythritol ester, butyl oleate, methyl acetyl ricinoleate, tricresyl phosphate, trioctyl phosphate, propylene glycol adipate polyester, butylene glycol adipate polyester, and combinations thereof. One or more embodiments provide that the A Side includes butylcarbitol adipate, hexadecyltrimetoxysilane, or a combination thereof. Suitable plasticizers include bis(2-(2-butoxyethoxy)ethyl) adipate, bis- dipropylene glycol n-butyl ether adipate, bis-diethylene glycol n-butyl ether malonate, bis-diethylene glycol n-butyl ether glutarate, bis-dipropylene glycol methyl ether maleate, tetraetyleneglycol di-2-ethylhexanoate, and the like.

[0037] The plasticizer can be from 2 to 20 wt% of the A Side based on a total weight of a combination of A Side components. All individual values and subranges from 2 to 20 wt% are included; for example, the plasticizer can be from a lower limit of 2, 3, or 5 wt% to an upper limit of 20, 15, or 10 wt% of the A Side based on the total weight of the combination of A Side components.

[0038] The A Side can include an epoxy resin. The epoxy resin can be an aliphatic or an aromatic epoxy resin. Epoxy equivalent weight (EEW) of the epoxy resin can be in the range of 100-1000. Suitable epoxy resins include aromatic epoxy resin such as bisphenol A diglycidyl ether or aliphatic epoxy resins such as trimethylol ethane triglycidyl ether. Different amounts of epoxy resins can be utilized for various applications. Epoxy resin can be present from 0.01 to 10 wt% of the A Side composition.

[0039] The A Side can include an epoxy silane, such as glycidoxypropyltrimethoxysilane. Different amounts of epoxy silane can be utilized for various applications. Epoxy silane can be present in 0.01 to 4 wt% of the A Side composition. Other known epoxysilanes can also be utilized characterized by a molecule containing silane groups and epoxy groups.

[0040] The A Side can include a colorant. Different colorants can be utilized for various applications. When utilized, the colorant can be from 0.001 to 0.500 wt% of the A Side based on a total weight of a combination of A Side components. All individual values and subranges from 0.001 to 0.500 wt% are included; for example, the colorant can be from a lower limit of 0.001 , 0.005, or 0.010 wt% to an upper limitof 0.500, 0.100, or 0.090 wt% of the A Side based on the total weight of the combination of A Side components.

[0041] Embodiments provide that the A Side can include an additive, e.g., an A Side additive. Examples of additives include moisture scavengers, adhesion promoters, thixotropic agents, antioxidants, wetting agents, surface treatment additives, and combinations thereof, among other additives. Different additives can be utilized for various applications. Different amounts of additives can be utilized for various applications.

[0042] As mentioned, the thermally conductive compositions disclosed herein include a B side, which may be referred to as an amine composition. The B side includes an amine, i.e. a primary and / or secondary amine. Examples of amines include triethylentetramine, JEFFAMINE polyether amines, isophorone diamine and combinations thereof. The B can include one or more secondary amines, such as triethylenetetramine. Various combinations of primary and secondary amines can be utilized.

[0043] Embodiments provide that the B side can include a primary amine.Examples of primary amines include polyoxypropylenetriamine, isophorone diamine, and combinations thereof. One or more embodiments provide that the primary amine has two or more primary amine moieties. One or more embodiments provide that the primary amine has three primary amine moieties. One or more embodiments provide that the primary amine comprises polyoxypropylenetriamine.

[0044] The amine, i.e. the primary and / or secondary amine, can be from 0.01 to 50 wt% of the B Side based on a total weight of a combination of B Side components.All individual values and subranges from 0.01 to 50 wt% are included; for example, the amine can be from a lower limit of 0.01 , 0.05, or 0.10 wt% to an upper limit of 50, 30 20, 10, or 2 wt% of the B Side based on the total weight of the combination of B Side components.

[0045] The B Side includes a plasticizer, e.g., a B Side plasticizer. Plasticizers are discussed herein. Examples of plasticizers include butylcarbitol adipate, hexadecyltrimetoxysilane, diisononyl phthalate (DINP), dioctyl adipate, isodecyl succinate, diethylene glycol dibenzoate, pentaerythritol ester, butyl oleate, methyl acetyl ricinoleate, tricresyl phosphate, trioctyl phosphate, propylene glycol adipate polyester, butylene glycol adipate polyester, and combinations thereof. One or more embodiments provide that the B Side includes butylcarbitol adipate, hexadecyltrimetoxysilane, or a combination thereof. One or more embodiments provide that the B Side plasticizer is the same as the A Side plasticizer. One or moreembodiments provide that the B Side plasticizer is different than the A Side plasticizer. Suitable plasticizers include bis(2-(2-butoxyethoxy)ethyl) adipate, bis- dipropylene glycol n-butyl ether adipate, bis-diethylene glycol n-butyl ether malonate, bis-diethylene glycol n-butyl ether glutarate, bis-dipropylene glycol methyl ether maleate, tetraetyleneglycol di-2-ethylhexanoate, and the like.

[0046] The plasticizer can be from 2 to 20 wt% of the B Side based on a total weight of a combination of B Side components. All individual values and subranges from 2 to 20 wt% are included; for example, the plasticizer can be from a lower limit of 2, 3, or 5 wt% to an upper limit of 20, 15, or 10 wt% of the B Side based on the total weight of the combination of B Side components.

[0047] The B Side includes a thermally conductive filler, e.g., a B Side thermally conductive filler. Fillers disclosed herein may have a thermal conductivity of at least 1 W / m«K, at least 5 W / n K, or at least 20 W / m«K, and may have a thermal conductivity of less than 1000 W / m«K, or less than 100 W / m«K. Fillers disclosed herein may be low density and low hardness to reduce overall weight of the composition and reduce weight in automotive, EV, and reduce abrasiveness of the composition. One or more embodiments provides that the thermally conductive filler is aluminum trihydroxide, aluminumtrihydrate, or ATH. One or more embodiments provide that the B Side thermally conductive filler is the same as the A Side thermally conductive filler. One or more embodiments provide that the B Side thermally conductive filler is different than the A Side thermally conductive filler.

[0048] The thermally conductive filler can be from 50 to 95 wt% of the B Side based on a total weight of a combination of B Side components. All individual values and subranges from 50 to 95 wt% are included; for example, the thermally conductive filler can be from a lower limit of 50, 75, or 80 wt% to an upper limit of 95, 93, or 90 wt% of the B Side based on the total weight of the combination of B Side components.

[0049] Embodiments provide that the B side can include a catalyst. Examples of the catalyst include amidines. One or more embodiments provide that the catalyst comprises an amidine. An example of an amindine is diazabicycloundecene. One or more embodiments provide that catalyst is diazabicycloundecene. The catalyst may be any one or any combination of more than one selected from carboxylate salts, tertiary amines, amidines, guanidines, and diazabicyclo compounds. In some embodiments the carboxylate salt is a metal carboxylate; in a further embodiment the carboxylate salt is a metal alkanoate; in a further embodiment the carboxylate salt is an alkali metal carboxylate; and in a further embodiment the carboxylate salt is analkali metal alkanoate. Examples of suitable metal alkanoates include bismuth octoate, bismuth neodecanoate, potassium acetate, potassium 2-ethylhexanoate, or mixtures thereof. In some embodiments, the tertiary amine is sterically hindered tertiary amine; in a further embodiment, the tertiary amine is a long chain tertiary amine (i.e. amine substituents of at least 6 hydrocarbons); in a further embodiment the tertiary amine is a cyclic tertiary amine. Examples of suitable tertiary amines include dimorpholinodialkyl ether, a di((dialkylmorpholino)alkyl)ether such as (di-(2- (3,5-dimethyl-morpholino)ethyl)ether), triethylene diamine, N,N- dimethylcyclohexylamine, N,N-dimethyl piperazine, 4-methoxyethyl morpholine, N- methylmorpholine, N-ethyl morpholine, or mixtures thereof. In some embodiments, the amidine or guanidine are N-hydrocarbyl substituted amidines or guanidines; in a further embodiment the amidine or guanidine are cyclic amidines or cyclic guanidines. Examples of suitable amidines or guanidines include 1 ,8- diazabicyclo[5.4.0]undec-7-ene (DBU), 1 ,5,7-triazabicyclo[4.4.0]dec-5-ene, diazabicyclo[5.4.0]undec-7-ene, and N-methyl-1 ,5,7-triazabicyclododecene.

[0050] When utilized, the catalyst, e.g. B side catalyst, can be from 0.001 to 3 wt% of the B Side based on a total weight of a combination of B Side components. All individual values and subranges from 0.001 to 3 wt% are included; for example, the catalyst can be from a lower limit of 0.001 , 0.005, or 0.10 wt% to an upper limit of 3, 2, 1 , or 0.5 wt% of the B Side based on the total weight of the combination of B Side components.

[0051] One or more embodiments provide that the A side can include a catalyst, as discussed herein. When utilized, the catalyst, e.g. A side catalyst, can be from 0.001 to 3 wt% of the A Side based on a total weight of a combination of A Side components. All individual values and subranges from 0.001 to 3 wt% are included; for example, the catalyst can be from a lower limit of 0.001 , 0.005, or 0.10 wt% to an upper limit of 3, 2, 1 , or 0.5 wt% of the A Side based on the total weight of the combination of A Side components.

[0052] Embodiments provide that the B Side can include an additive, e.g., an B Side additive. Examples of additives include moisture scavengers, adhesion promoters, thixotropic agents, antioxidants, wetting agents, surface treatment additives, and combinations thereof, among other additives. Different additives can be utilized for various applications. Different amounts of additives can be utilized for various applications.

[0053] The A Side and the B Side can be combined, e.g., mixed to make the thermally conductive compositions disclosed herein. The A Side and the B Side canbe combined, using known components, methods, and conditions, which may vary for different applications.

[0054] As mentioned, advantageously the thermally conductive compositions disclosed herein have low a NCO %, e.g. less than 0.1 NCO %, e.g., based upon a combination of the urethane / acrylic telechelic polymer, a first portion of the thermally conductive filler, and a first portion of plasticizer, and the colorant. Providing a low NCO % is desirable for a number of applications, and may even be a requirement in some instances, e.g., some manufacturing process. The low NCO % may be helpful in reducing health risks that may be associated with some other relatively higher NCO % materials.

[0055] The thermally conductive compositions disclosed herein can be cured to make a cured product, e.g. a thermally conductive product. The thermally conductive compositions can be cured, using known components, methods, and conditions, which may vary for different applications. Advantageously, the thermally conductive compositions disclosed herein can be cured at ambient temperatures, in contrast to some other thermally conductive compositions. For example, the thermally conductive compositions disclosed herein can be cured at a temperature from 15 to 25 °C, 15 to 35 °C, 18 to 35 °C, or from 18 to 23 °C.

[0056] The thermally conductive products disclosed herein desirably provide a thermal conductivity greater than 0.5 Wm1K1. For example, the thermally conductive products can provide a thermal conductivity from 0.5 to 10.0 Wm1K1. All individual values and subranges from 0.5 to 10.0 Wm1K1are included; for example, the thermally conductive products can provide a thermal conductivity from a lower limit of 0.5, 1 .0, 1 .5 or 2.0 to an upper limit of 10, 9, 8, or 6 Wm1K1. One or more embodiments provide that the thermally conductive products can provide a thermal conductivity equal to or greater than 2.0 Wm1K1. Thermal conductivity can be determined in accordance with ISO 22007-2 or ASTM D-5470.

[0057] The thermally conductive products can provide a Pull Force (PET Plates) greater than 0.15 MPa. For example, the thermally conductive products can provide a Pull Force (PET Plates) from 0.15 to 10 MPa. All individual values and subranges from 0.15 to 10 MPa are included; for example, the thermally conductive cured products can provide a Pull Force (PET Plates) from a lower limit of 0.15, 0.25, or 0.30 MPa to an upper limit of 10, 5, 3, or 2 MPa. Pull Force (PET Plates) can be determined as discussed herein. A Pull Force (PET Plates) greater than 0.15 MPa indicates that the thermally conductive product is adhesive to plastic. Adhesion to plastic is desirable for a number of applications.

[0058] The thermally conductive cured products can provide a Pull Force (Aluminum Plates) greater than 0.15 MPa. For example, the thermally conductive products can provide a Pull Force (Aluminum Plates) from 0.15 to 10 MPa. All individual values and subranges from 0.15 to 10 MPa are included; for example, the thermally conductive products can provide a Pull Force (Aluminum Plates) from a lower limit of 0.15, 1 .0, or 2.0 MPa to an upper limit of 10, 8 or 6 MPa. Pull Force (Aluminum Plates) can be determined as discussed herein. A Pull Force (Aluminum Plates) greater than 0.15 MPa indicates that the thermally conductive cured product is adhesive to metal. Adhesion to metal is desirable for a number of applications.

[0059] The thermally conductive products can provide a Squeeze Force less than 200 N before curing. For example, the thermally conductive product can provide a Squeeze Force from 20 to 200 N. All individual values and subranges from 20 to 200 N are included; for example, the thermally conductive products can provide a Squeeze Force from a lower limit of 20, 30, or 40 N to an upper limit of 200, 150, 120, or 95 N. Squeeze Force can be determined as discussed herein. A Squeeze Force less than 120 N can indicate good workability and is desirable for a number of applications.

[0060] The thermally conductive products can provide an Aged Squeeze Force less than 200 N indicating shelf stability of the product. For example, the thermally conductive product can provide an Aged Squeeze Force from 35 to 200 N. All individual values and subranges from 35 to 200 N are included; for example, the thermally conductive products can provide an Aged Squeeze Force from a lower limit of 35, 50, 60, or 80 N to an upper limit of 200 N. Aged Squeeze Force can be determined as discussed herein. Aged Squeeze Force less than 200 N can indicate good shelf life and good workability and is desirable for a number of applications.

[0061] Preparation of the thermally conductive compositions of the present disclosure may be achieved by mixing the respective components of the A Side composition and the B Side composition. Suitable mixing techniques include the use of a Ross PD Mixer (Charles Ross), Myers mixer, FlackTek Speedmixer, or other mixers known in the art that distribute the different components. The respective components and compositions can generally be added in any sequence, various combinations, and have various times of additions. Any of the above-mentioned optional additives may also be added during the mixing to form the thermally conductive composition, or prior to the mixing, e.g., added to the A Side and / or B Side compositions. One or more of the components of the composition may be premixed.

[0062] The present disclosure also provides a process for preparing a thermally conductive composition, including mixing the A Side with the B Side, and optional components described above. The A Side and the B side composition can be combined such that a molar ratio of acrylic groups to amine reactive groups is in the range of 0.90:1.1 to 1 .1 :0.9, such as 0.90:1 .1 , 0.95:1 .05, 0.97:1 .03, or 1 :1 . At the same time, a volume ratio of the A side to the B side in the thermally conductive composition may be within the range 0.90:1 .1 , from 0.95:1 .05, from 0.97:1 .03, or at the ratio of 1 :1 .

[0063] The A Side composition and the B Side composition are reactive with one another and when contacted or mixed upon application, can undergo a curing reaction wherein the reaction product is a cured thermally conductive product that can provide a thermally conductive interface between two surfaces. The mixture of A Side and B Side may be cured at a temperature from 0 °C to 60 °C, 10 °C to 50 °C, 15 °C to 45 °C, or 18 °C to 35 °C. Curing may be indicated by an increase in the viscosity after mixing the A Side and B Side, with the eventual formation of a cured thermally conductive product with a measurable pull force. Thermally conductive compositions disclosed herein may cure in less than 14 days, less than 10 days, or less than 7 days, and generally on a time scale greater than 30 minutes.

[0064] In some embodiments, cured thermally conductive products may have a density of 1 g / cm3to 4 g / cm3, 1 .5 g / cm3to 3.5 g / cm3, or 1 .8 g / cm3to 3.1 g / cm3. Additionally, the viscosity of A-side and B-side allows for easy processing of the material.

[0065] Thermally conductive compositions disclosed herein may be useful as a gap filler or an adhesive for energy storage devices and in electronic vehicle battery thermal management. In some cases, the compositions can be applied between a heat sink such as a cooling plate and heat source such as a battery module to provide a thermally conductive interface.

[0066] Manual or semiautomatic dispensing tools can be used to apply the composition directly to the target surface to minimize waste. In an embodiment, a thermally conductive composition may be prepared by combining the A Side and B Side and applying to a heat sink using an automated mix-meter-dispense system, followed by installation of a battery cell, module or pack, or other heat source.

[0067] The thermally conductive cured products are advantageously used for a number of applications, such as automotive applications, among others.EXAMPLES

[0068] In the Examples, various terms and designations for materials are used including, for instance, the following:

[0069] Polyol (VORANOL 3003 LM, average hydroxyl functionality of 3.0, average hydroxyl number 56 mg KOH / g, number average molecular weight 2978 g / mol, obtained from The Dow Chemical Company);

[0070] Diisocyanate (Toluene diisocyanate, VORANATE T-80 Type 1 TDI, obtained from The Dow Chemical Company);

[0071] Catalyst 1 (dibutyltin dilaurate, DABCO T-12, obtained from Evonik);

[0072] Acidifying agent (benzoyl chloride);

[0073] Acrylate (hydroxyethyl acrylate, obtained from The Dow Chemical Company);

[0074] Catalyst 2 (amine catalyst, DABCO 33 LV);

[0075] Stabilizer (methylhydroquinone);

[0076] Secondary amine (triethylentetramine);

[0077] Primary amine 1 (polyoxypropylenetriamine, with a molecular weight of 400);

[0078] Primary amine 2 (polyoxypropylenetriamine with a molecular weight of 5000);

[0079] Primary amine 3 (isophoronediamine);

[0080] Plasticizer 1 (butylcarbitol adipate);

[0081] Plasticizer 2 (hexadecyltrimetoxysilane);

[0082] Thermally conductive filler (aluminum trihydroxide, hydrophobically surface modified aluminum trihydrate (ATH) with a D-| Q of 0.5 microns, D5Q of 8 microns, and Dgp of 80 microns.);

[0083] Epoxy (Trimethylol ethane triglycidyl ether);

[0084] Epoxy silane (3-glycidyloxypropyltrimethoxysilane);

[0085] Catalyst 3 (1 ,8-Diazabicyclo(5.4.0)undec-7-ene);

[0086] Colorant (Blue).

[0087] An NCO prepolymer was made as follows. Polyol (59.53 wt%), diisocyanate (40.45 wt%), Catalyst 1 (0.015 wt%), and Acidifying agent (0.005 wt%) were added to a container. The contents of the container were maintained at approximately 70 °C and were stirred for 4 hours to provide the NCO prepolymer. The NCO prepolymer had a NCO% of 12%.

[0088] A urethane / acrylic telechelic polymer was made as follows. Acrylate (27.59 wt%), Catalyst 2 (0.3 wt%), and Stabilizer (0.02 wt%) were added to the container having the NCO prepolymer (72.09 wt%). The contents of the containerwere maintained at approximately 50 °C and were stirred for 6 hours to provide the urethane / acrylic telechelic polymer.

[0089] Example 1 , a thermally conductive composition, was made as follows. A side components were added to a container and mixed at 2350 rpm for approximately 90 seconds using a high speed mixer; B side components were added to a container and mixed at 2350 rpm for approximately 90 seconds using a high speed mixer. A side component and B side component amounts are shown in Table 1 . Then, the A side component (10 grams) and the B side component (10 grams) were added to container and mixed at 2350 rpm for approximately 90 seconds using a high speed mixer to make Example 1 .

[0090] Examples 2-3 and Comparative Examples A-B were made as Example 1 , with any changes shown in Table 1 .Table 1

[0091] The data of Table 1 show that each of Examples 1-2 have a total NCO% that is less than 0.1%. A total NCO% that is less than 0.1% is advantageous for a number of applications.

[0092] Squeeze force for individual part A and B was measured per the method described below.

[0093] For the measurement of aged squeeze force, Part A and B samples were individually kept in glass vial and aged for a week at 60 °C. Aged squeeze force was measured after cooling the samples to room temperature.

[0094] The data of Table 1 show that the products made with Examples 1 -2 each provided a Squeeze Force less than 120 N, in contrast to products made with Comparative Examples A-B, which each provided a Squeeze Force greater than 120 N. A Squeeze Force less than 120 N is advantageous and desirable for a number of applications.

[0095] The data of Table 1 show that the products made with Examples 1 -2 each provided an Aged Squeeze Force less than 200 N, in contrast to products madewith Comparative Examples A-B, which each provided an Aged Squeeze Force greater than 1000 N. An Aged Squeeze Force less than 200 N is advantageous and desirable for a number of applications.

[0096] For the measurement of pull force, part A and par B were mixed in 1 :1 weight ratio. Portions of Examples 1-3 were placed between respective aluminum plates and respective PET plates, where the volumes between the plates were 2.5 cm x 2.5 cm x 0.1 cm. After being placed between the plates, the plates were kept together with metallic clips and the portions of Examples 1-3 were cured at approximately 20 °C for 24 hours to form cured products. A number of properties were determined for the cured products, the results are shown in Table 2.Table 2

[0097] For the measurement of thermal conductivity, Part A and Part B were combined in 1 :1 weight ratio and measurements were conducted on the paste. The data of Table 2 show that the products made with Examples 1 -3 each provided a Thermal Conductivity greater than or equal to 0.5 Wm1K1.

[0098] The data of Table 2 show that the cured products made with Example 1 and Example 3 each provided a Pull Force (PET Plates) greater than 0.15 MPa. A Pull Force (PET Plates) greater than 0.15 MPa is advantageous and desirable for a number of applications.

[0099] The data of Table 2 show that the cured products made with Examples 1-2 each provided a Pull Force (Aluminum Plates) greater than 0.15 MPa.A Pull Force (Aluminum Plates) greater than 0.15 MPa is advantageous and desirable for a number of applications.

[0100] Pull Force (PET Plates) and Pull Force (Aluminum Plates) was determined as follows. Respective samples were tested with an INSTRON Model 5500 S device. For testing, plates were pulled with a 5 mm / min rate. Respective Pull Force values were calculated as the force utilized to detach the plates.

[0101] Squeeze force was determined using a texture analyzer equipped with a 100 kg load cell. After dispensing the thermally conductive compositions onto respective flat heavy-duty aluminum substrates, an acrylic probe with a diameter of 40 mm was lowered to sandwich the test material against the flat substrate to achieve a standard 5.0 mm gap thickness. Any excess overflow material was trimmed away with a flat-edge spatula. After trimming, the test started and the probe moved to a final thickness of 0.3 mm, at a rate of 1 .0 mm / sec while the force was recorded. The specific force value recorded at the gap of 0.5 mm was reported as the Squeeze Force.

[0102] Aged Squeeze Force was determined as Squeeze Force, with the change that the A side components and the B side components were individually maintained at 60 °C for approximately 168 prior to testing.

[0103] Thermal conductivity was determined with a Hot Disk Thermal Constants Analyzer (TPS 2500S, Thermtest Instruments) in accordance with ISO 22007-2. All measurements were performed with a thermal probe using a doublesided measurement with two-6 mm cups, at 150 mW heating power and 5 s measurement time.

Claims

ClaimsWhat is claimed is:1 . A thermally conductive composition comprising: a urethane / acrylic telechelic polymer; a thermally conductive filler; and an amine.

2. The thermally conductive composition of claim 1 , wherein the urethane / acrylic telechelic polymer is a reaction product of a NCO prepolymer with a hydroxyacrylate.

3. The thermally conductive composition of claim 2, wherein the amine is triethylene tetramine, isophorone diamine, a polyetheramine or a combination thereof4. The thermally conductive composition of claim 3, further comprising: a plasticizer; and a colorant; wherein: the urethane / acrylic telechelic polymer is from 0.01 to 50 wt% based on a total weight of a combination of the urethane / acrylic telechelic polymer, a first portion of the thermally conductive filler, and a first portion of plasticizer, and the colorant; the first portion of the thermally conductive filler is from 50 to 95 wt% based on the total weight of the combination of the urethane / acrylic telechelic polymer, the first portion of the thermally conductive filler, and the first portion of plasticizer, and the colorant; the first portion of plasticizer is from 2 to 20 wt% based on the total weight of the combination of the urethane / acrylic telechelic polymer, the first portion of the thermally conductive filler, and the first portion of plasticizer, and the colorant; and the colorant is from 0.001 to 0.500 wt% based on the total weight of the combination of the urethane / acrylic telechelic polymer, the first portion of the thermally conductive filler, and the first portion of plasticizer, and the colorant.

5. The thermally conductive composition of claim 4, further comprising: a catalyst, wherein:the amine is from 0.01 to 50 wt% based on a total weight of a combination of the amine, a second portion of the thermally conductive filler, a second portion of the plasticizer, and the catalyst; the second portion of the thermally conductive filler is from 50 to 95 wt% based on the total weight of the combination of the amine, a second portion of the thermally conductive filler, a second portion of the plasticizer, and the catalyst; the second portion of the plasticizer if from 2 to 20 wt% based on the total weight of the combination of the amine, a second portion of the thermally conductive filler, a second portion of the plasticizer, and the catalyst; and the catalyst is from 0.001 to 3 wt% based on the total weight of the combination of the secondary amine, a second portion of the thermally conductive filler, a second portion of the plasticizer, and the catalyst.

6. The thermally conductive composition of claim 5, wherein the thermally conductive composition has less than 0.1 NCO % based upon the combination of the urethane / acrylic telechelic polymer, the first portion of the thermally conductive filler, the first portion of plasticizer, and the colorant.

7. The thermally conductive composition of any one of claims 1 -6, wherein the thermally conductive filler is aluminum trihydrate.

8. The thermally conductive composition of any one of claims 4-7, wherein the plasticizer is butylcarbitol adipate, hexadecyltrimetoxysilane, or a combination thereof.

9. The thermally conductive composition of any one of claims 5-8, wherein the catalyst is an amidine, a tertiary amine, an organometallic compound, or a combination thereof.

10. The thermally conductive composition of any one of claims 1 -9 further comprising an epoxy, an epoxy silane, or a combination thereof.

11. A thermally conductive product formed by curing the thermally conductive composition of any one of claims 1 -10.

12. The thermally conductive product of claim 11 , wherein the thermally conductive product provides a thermal conductivity greater than 0.5 Wm 'K1as determined in accordance with ISO 22007-2.

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