Two-component thermal conductive adhesive

Abstract

A two-component thermal conductive adhesive with a high conductive filler content.

Description

[Technical Field]

[0001] The automotive industry has seen a trend towards reducing vehicle weight over the past decade. This trend has been driven primarily by regulations aimed at reducing CO2 emissions from vehicles. In recent years, the strategy of lightweight construction has been further accelerated by the increasing number of electric vehicles. To provide longer driving ranges, batteries with higher energy density are required. All long-distance durability requires adequate thermal management. Thermal interface materials or thermally conductive adhesives are needed to thermally connect battery cells or modules to cooling units. [Background technology]

[0002] Battery cells generate heat during charging and discharging. To avoid loss of efficiency, overheating, and dangerous runaway thermal reactions, battery cells need to be maintained at an appropriate operating temperature (preferably 25-40°C). Therefore, active cooling is commonly used. An efficient active cooling method involves pumping a cooled water-glycol mixture through a channel that cools the bottom metal base plate on which the battery cells or modules are located. The battery cells or cell arrays can be directly bonded to the cooling plate with a thermally conductive adhesive. This provides good mechanical fixation and thermal connection. However, to provide sufficient conductivity, two-component thermally conductive adhesives generally must have a conductive filler content of at least 70% by weight of each component. In particular, with adhesive components containing water, achieving adequate dispersion to enable a paste-like formulation that can be mixed or cured with a second prepolymer component is often difficult or impossible. [Overview of the project] [Means for solving the problem]

[0003] An uncured two-part thermally conductive adhesive compound is disclosed, and this compound is a) i) 1% to 25% by weight of the first component, ii) A first thermally conductive filler in an amount of at least 70% by weight of the first component, iii) 0.1% to 5% by weight of the first organic functional silane, iv) A first component comprising 0% to 10% by weight of a first plasticizer, b) i) 0.01% to 5% by weight of water for the second component, ii) A second thermally conductive filler in an amount of at least 70% by weight of the second component, iii) 0.1% to 5% by weight of polyetheramine of the second component, iv) 0.1% to 5% by weight of the second organic functional silane, v) A second component comprising a second plasticizer in an amount of 1% to 20% by weight of the second component.

[0004] The uncured adhesive formulation is in the form of a kit in which the first and second components are not mixed before use. The components of the kit may be packaged together, packaged separately, or sold together or separately.

[0005] Cured adhesives are also described, which are prepared by mixing a first component and a second component of an adhesive formulation and curing the mixture, and which include the process of preparing the individual components of the adhesive and the process of curing the two components. Similarly, articles containing cured adhesives are also described. [Modes for carrying out the invention]

[0006] To achieve a thermal conductivity exceeding 1.5 W / mK, both components of a two-component adhesive typically require at least 70% by weight of thermal conductive filler. In one embodiment, each component of the adhesive independently contains 70% to 95% by weight of thermal conductive filler. In a further embodiment, each component of the adhesive independently contains 75% to 90% by weight of thermal conductive filler. In a further embodiment, each component of the adhesive independently contains 75% to 85% by weight of thermal conductive filler. In a further embodiment, each component of the adhesive independently contains 80% to 85% by weight of thermal conductive filler.

[0007] Various thermally conductive fillers can be used. Examples include aluminum hydroxide, also known as aluminum trihydrate (ATH), aluminum oxides such as spherical aluminum oxide, and any combination thereof. ATH may be a unimodal ATH powder or an ATH powder having a multimodal particle size distribution (e.g., bimodal, trimodal, etc.). When a unimodal ATH powder is used, the average particle size may be about 5 to 100 μm. When a multimodal ATH powder is used, the average particle size of the smallest particles may be less than about 10 μm, while the average particle size of the largest particles may be greater than about 50 μm. In addition, the ATH powder may be surface-treated with silanes, titanates, carboxylates, etc.

[0008] In one embodiment, a combination of ATH and aluminum oxide, such as spherical aluminum oxide, can be used as the first component, the second component, or both. When this combination is used, the ratio of ATH to aluminum oxide may vary, for example, in the range of 0.1:99.9 to 99.9:0.1. In one embodiment, the ratio of ATH to aluminum hydroxide is in the range of 80:20 to 20:80, for example, 60:40 to 40:60.

[0009] I. First adhesive component A. Silane-terminated urethane prepolymer The first component of the two-part adhesive comprises a silane-terminated urethane prepolymer. The silane-terminated urethane prepolymer is a urethane prepolymer in which some or all of the isocyanate groups are end-capped with organosilanes. The silane-terminated urethane prepolymer can be prepared by the reaction of an isocyanate-functionalized silane with a polyol, or by the reaction of an isocyanate-functionalized silane with a hydroxyl-terminated prepolymer, or by the reaction of a nucleophilic-functionalized silane (e.g., aminosilane, mercaptosilane, etc.) with an isocyanate-terminated prepolymer.

[0010] Examples of prepolymers include polyurethanes, polyureas, polyethers, polyesters, poly(meth)acrylates, polycarbonates, polystyrenes, polyamines or polyamides, polyvinyl esters, styrene / butadiene copolymers, polyolefins, polysiloxanes, and polysiloxane-urea / urethane copolymers. Silane-terminated urethane prepolymers may have a weight-average molecular weight in the range of 200-5,000, 300-3,000, or 500-2,000, as determined by gel permeation chromatography (GPC).

[0011] Suitable silane-terminated urethane prepolymers include any of those disclosed in European Patent No. 1924621, and U.S. Patents No. 3,933,756, 5,756,751, 6,288,198, 6,545,087, 6,703,453, 6,809,170, 6,833,423, 6,844,413, 6,887,964, 6,998,459, 7,115,696, 7,465,778, 7,060,750, and 7,309,753, which are incorporated herein by reference with respect to the teachings relating to silane-terminated urethane prepolymers. Silane-terminated urethane prepolymers are also commercially available.

[0012] In one embodiment, the first component comprises 1 wt% to 25 wt% of a silane-terminated urethane prepolymer based on the weight of the first component. In a further embodiment, the first component comprises 5 wt% to 25 wt% of a silane-terminated urethane prepolymer based on the weight of the first component. In a further embodiment, the first component comprises 5 wt% to 15 wt% of a silane-terminated urethane prepolymer based on the weight of the first component. In a further embodiment, the first component comprises 8 wt% to 12 wt% of a silane-terminated urethane prepolymer based on the weight of the first component. In a further embodiment, the first component comprises 8 wt% to 10 wt% of a silane-terminated urethane prepolymer based on the weight of the first component.

[0013] B. First Organofunctional Silane The first adhesive component can include a first organofunctional silane. The first component can include 0.1 wt% to 5 wt% of an organofunctional silane based on the weight of the first component. The first organofunctional silane can be the same as or different from the second organofunctional silane. In one embodiment, both silanes are the same. The organofunctional silane can function as a surface modifier for the thermally conductive filler. For example, the organofunctional silane can partially or completely coat the surface of the conductive filler particles. The conductive filler can include surface M-OH groups (where M is a metal atom), and the organofunctional silane can include functional groups that react with the M-OH groups to form a direct or indirect bond between the surface modifier and M.

[0014] The surface of the conductive filler can be hydrophobized with the organofunctional silane. It will be appreciated that the organofunctional silane can be added to the filler before or after mixing the conductive filler with the matrix phase material. For example, before mixing the conductive filler and the matrix phase material, the conductive filler can be coated with or reacted with the organofunctional silane. As another example, the organofunctional silane can be mixed with the matrix phase material to form a premix, which can then be combined with the conductive filler. As another example, the conductive filler and the matrix phase material can be mixed, and then the organofunctional silane can be added to the mixture.

[0015] In one embodiment, the first component comprises 0.1 wt% to 5 wt% of an organofunctional silane based on the second component. In a further embodiment, the first component comprises 0.5 wt% to 3 wt% of an organofunctional silane based on the first component. In a further embodiment, the first component comprises 0.5 wt% to 1.5 wt% of an organofunctional silane based on the first component.

[0016] A variety of organofunctional silanes can be used. In one embodiment, the organofunctional silane is an alkylsilane. In a further embodiment, the organofunctional silane has the following structure:

[0017]

Chemical formula

[0018] (where n is an integer in the range of 0 to 24, and R 3 ~R 7 are independently hydrogen or optionally substituted C1-C4 alkyl). In a further embodiment, R 3 ~R 7 are independently hydrogen or unsubstituted C1-C4 alkyl. In a further embodiment, n is an integer in the range of 1 to 15, such as 2 to 14, 5 to 14, 8 to 14, or 10 to 14. Specific non-limiting examples include trimethoxy(methyl)silane, ethyltrimethoxysilane, trimethoxy(propyl)silane, butyltrimethoxysilane, trimethoxy(pentyl)silane, hexyltrimethoxysilane, heptyltrimethoxysilane, trimethoxy(octyl)silane, trimethoxy(nonyl)silane, decyltrimethoxysilane, trimethoxy(undecyl)silane, dodecyltrimethoxysilane, trimethoxy(tridecyl)silane, trimethoxy(tetradecyl)silane, trimethoxy(pentadecyl)silane, hexadecyltrimethoxysilane, or combinations thereof.

[0019] II. Second Adhesive Component In addition to the thermally conductive filler described above, the second component contains water as a curing agent. The water allows hydrolysis of the silane groups to form siloxanes in the prepolymer of the first component, which is how the two-part adhesive hardens when the two components are mixed together. In one embodiment, the second component contains 0.01% to 5% by weight of water relative to the second component. In a further embodiment, the second component contains 0.1% to 2% by weight of water relative to the second component. In a further embodiment, the second component contains 0.1% to 1% by weight of water relative to the second component. In a further embodiment, the second component contains 0.1% to 0.5% by weight of water relative to the second component.

[0020] A. Polyethylamine The inventors have surprisingly discovered that by including both polyetheramine and alkylsilane in the second adhesive component, dispersion is significantly improved, viscosity is lower, and no phase separation is observed when the portions of the second component are mixed. Typically, high conductive filler levels (e.g., above 70%) can lead to poor dispersion, making it difficult or impossible to obtain paste-like formulations, as demonstrated by the comparative examples below. The combination of polyetheramine and alkylsilane in the second component avoids these problems.

[0021] In one embodiment, the second component comprises 0.1% to 5% by weight of polyetheramine. In a further embodiment, the second component comprises 0.5% to 3% by weight of polyetheramine. In a further embodiment, the second component comprises 0.5% to 1.5% by weight of polyetheramine. In a further embodiment, the second component comprises 0.5% to 1% by weight of polyetheramine, for example, about 1% by weight.

[0022] The polyetheramine can be a diamine or a triamine. The amine groups can independently be secondary or primary. Generally, the polyetheramine can have a weight average molecular weight in the range of 200 to 6,000 g / mol. In one embodiment, the polyetheramine has a weight average molecular weight in the range of 1,000 to 5,000 g / mol. In a further embodiment, the polyetheramine has a weight average molecular weight in the range of 1,500 to 4,000 g / mol. In a further embodiment, the polyetheramine has a weight average molecular weight in the range of 2,000 to 3,500 g / mol. In a further embodiment, the polyetheramine has a weight average molecular weight in the range of 2,500 to 3,500 g / mol, for example, about 3,000 g / mol.

[0023] The polyetheramine can have a backbone based on poly(alkylene oxide) diol, such as C2-C6 alkylene, C2-C4 alkylene or C3 alkylene. The backbone can be based on a polyether of propylene glycol. In one embodiment, the polyetheramine has the formula:

[0024] [Chemical formula]

[0025] (where n is an integer in the range of 1 to 5, and R 1 and R 2 are independently optionally substituted C1-C4 alkyl) and has at least one residue. In a further aspect, at least one of R 1 and R 2 is hydrogen. In a further embodiment, R 1 is hydrogen and R 2 is optionally substituted C1-C4 alkyl, for example, optionally substituted methyl, ethyl, propyl, or butyl.

[0026] In one embodiment, the polyetheramine may be a triamine having a primary amine comprising more than 90% of the amine groups and a main chain based on a polyether of propylene glycol. A non-limiting example is the structure:

[0027] [ka] This is a polyetheramine having the following characteristics (wherein x, y, and z are the sum of integers in the range of 6 to 90). Any aliphatic carbon in the above triamine structure can also be substituted with a C1-C4 alkyl group such as a methyl group. One specific example is a triamine in the above triamine structure where x, y, and z sum to approximately 50, which also has the following characteristics:

[0028] [Table 1]

[0029] B. Second organic functional silane The polyetheramine may be present in the second component together with 0.1% to 5% by weight of the second component's organic functional silane (i.e., the second organic functional silane). The second organic functional silane may be the same as or different from the first organic functional silane. In one embodiment, both silanes are the same. In one embodiment, the second component contains 0.1% to 5% by weight of the second component's organic functional silane. In a further embodiment, the second component contains 0.5% to 3% by weight of the second component's organic functional silane. In a further embodiment, the second component contains 0.5% to 1.5% by weight of the second component's organic functional silane.

[0030] Various organically functionalized silanes can be used. In one embodiment, the organically functionalized silane is an alkylsilane. In a further embodiment, the organically functionalized silane has the following structure:

[0031] [ka]

[0032] (In the formula, n is an integer in the range of 0 to 24, R 3 ~R 7 R independently comprises hydrogen, or optionally substituted C1-C4 alkyl. In further embodiments, R 3 ~R 7 n is independently hydrogen or an unsubstituted C1-C4 alkyl group. In further embodiments, n is an integer in the range of 1-15, for example, 2-14, 5-14, 8-14, or 10-14. Specific non-limiting examples include trimethoxy(methyl)silane, ethyltrimethoxysilane, trimethoxy(propyl)silane, butyltrimethoxysilane, trimethoxy(pentyl)silane, hexyltrimethoxysilane, heptyltrimethoxysilane, trimethoxy(octyl)silane, trimethoxy(nonyl)silane, decyltrimethoxysilane, trimethoxy(undecyl)silane, dodecyltrimethoxysilane, trimethoxy(tridecyl)silane, trimethoxy(tetradecyl)silane, trimethoxy(pentadecyl)silane, hexadecyltrimethoxysilane, or combinations thereof.

[0033] III. Other Additives The first component, the second component, or both may include various other additives such as plasticizers, one or more catalysts to facilitate the reaction between water and the silane-terminated urethane prepolymer, optionally a colored paste, optionally further fillers such as magnesium carbonate or calcium carbonate.

[0034] A. Plasticizer In one embodiment, the first component or the second component may each contain the first or second plasticizer. In a further embodiment, the first component does not contain a plasticizer. In a further embodiment, the first component contains 0% to 10% by weight of the first plasticizer. In a further embodiment, the first component contains 1% to 8% by weight of the first plasticizer. In a further embodiment, the first component contains 6% to 6% by weight of the first plasticizer.

[0035] In one embodiment, the second component comprises 1% to 20% by weight of a second plasticizer. The first plasticizer, when present in the first component, may be the same as or different from the second plasticizer. In one embodiment, the second component comprises 3% to 15% by weight of a second plasticizer. In a further embodiment, the second component comprises 5% to 10% by weight of a second plasticizer.

[0036] In one embodiment, the plasticizer may have a weight-average molecular weight of 2,000 g / mol or less, for example, 1,000 g / mol or less, 800 g / mol or less, or 600 g / mol or less. The plasticizer is generally liquid at a temperature of about 100°C. Generally, suitable plasticizers include acids such as adipic acid, azelaic acid, benzoic acid, citric acid, dimer acid, fumaric acid, isobutyric acid, isophthalic acid, lauric acid, linoleic acid, maleic acid, maleic anhydride, mericic acid, myristic acid, oleic acid, palmitic acid, phosphoric acid, phthalic acid, ricinoleic acid, sebacic acid, stearic acid, succinic acid, 1,2-benzenedicarboxylic acid, and ester derivatives of anhydrides, as well as mixtures thereof. Epoxy oils, glycerol derivatives, paraffin derivatives, sulfonic acid derivatives, and mixtures thereof are also suitable.

[0037] Specific examples of such plasticizers include diethylhexyl adipate, heptyl nonyl adipate, diisodecyl adipate, adipic acid polyester, dicaprylyl adipate, dimethyl azelate, diethylene glycol dibenzoate and dipropylene glycol dibenzoate, polyethylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate benzoate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and methyl (or ethyl or butyl) phthalyl Isopropylglycolate, triethyl citrate, dibutyl fumarate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, methyl laurate, methyl linoleate, di-n-butyl maleate, tricapryl trimellitate, heptyl nonyl trimellitate, triisodecyl trimellitate, triisononyl trimellitate, isopropyl myristate, butyloleate, methyl palmitate, tricresyl phosphate, tris(2-ethylhexyl) phosphate, dimethyl phthalate, diethyl phthalate, dibutyl Tyl phthalate, diisobutyl phthalate, di-2-ethylhexyl phthalate, octyldecyl phthalate, diisodecyl phthalate, heptyl nonyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, butyl benzyl phthalate such as n-butyl benzyl ester of o-phthalic acid, isodecyl benzyl phthalate, alkyl (C7 / C9) benzyl phthalate, dimethoxyethyl phthalate, 7-(2,6,6,8-tetramethyl-4-oxa-3-oxo-nonyl Examples include benzyl phthalate, di-2-ethylhexyl sebacate, butyl ricinoleate, dimethyl sebacate, methyl stearate, diethyl succinate, butylphenyl methyl ester of 1,2-benzenedicarboxylic acid, epoxidized linseed oil, glycerol triacetate, chloroparaffin having about 40% to about 70% Cl, o,p-toluenesulfonamide, N-ethyl p-toluenesulfonamide, N-cyclohexyl p-toluenesulfonamide, sulfonamide-formaldehyde resins, and mixtures thereof.

[0038] Other suitable plasticizers known to those skilled in the art include, alone or in mixtures with other plasticizers, castor oil, aromatic petroleum condensates, partially hydrogenated terphenyls, silicone plasticizers such as dimethicone copolyol esters, dimethiconol esters, silicone carboxylates, and garvet esters.

[0039] In one embodiment, either of the plasticizers may be a phosphate such as a trialkyl phosphate, e.g., trioctyl phosphate. In further embodiments, the first plasticizer (if present) or the second plasticizer may have the following structure:

[0040] [ka]

[0041] (In the formula, R 8 ~R 10 (These are independently and optionally substituted branched or linear C1-C24 alkyl groups). In some embodiments, R 8 ~R 10 They are the same. In further embodiments, R 8 ~R 10 At least one of them is branched. In a further embodiment, R 8 ~R 10 R is independently and optionally substituted with branched or linear C4-C18 alkyl groups, such as C6-C16 or C8-C16 alkyl groups. In certain embodiments, R 8 ~R 10 At least one (or all) of these is 3-methylheptyl, i.e., tris(2-ethylhexyl) phosphate plasticizer.

[0042] B. Adhesion promoter Some embodiments of the adhesive formulation include an adhesion promoter in the first component, the second component, or both. If both components include an adhesion promoter, the promoters may be the same or different. The adhesion promoter may be, for example, a silane, epoxysilane, aminosilane, or a combination thereof. The adhesion promoter may constitute, for example, 0.1 to 3% of the total weight of either component. In some embodiments, the adhesion promoter may be present in either component in an amount ranging from 0.1% to 1% by weight of the isocyanate component, for example, in the range of 0.2% to 0.5% by weight.

[0043] Adhesion promoters include compounds having at least one functional group that has an attractive force to the surface of the desired substrate, a cured adhesive applied to the substrate, or both. Examples of adhesion promoters include titanates, carboxylated branched or linear PEIs, and silane compounds. Non-limiting examples include silane adhesion promoters having reactive functional groups such as epoxysilanes (e.g., γ-glycidoxypropyltrimethoxysilane) or mercaptosilanes (e.g., γ-mercaptopropyltrimethoxysilane).

[0044] C. Catalyst In some embodiments, the adhesive formulation contains a catalyst in the first component, the second component, or both components at a concentration of 0.01% to 3% by weight of the component. The catalyst can facilitate the reaction between water and the silane-terminated urethane prepolymer. In further embodiments, the adhesive formulation contains a catalyst in the first component, the second component, or both components at a concentration of 0.01% to 1% by weight of the component, in which case the catalyst facilitates the reaction between water and the silane-terminated urethane prepolymer. In further embodiments, the adhesive formulation contains a catalyst in the first component, the second component, or both components at a concentration of 0.2% to 0.5% by weight of the component, in which case the catalyst facilitates the reaction between water and the silane-terminated urethane prepolymer.

[0045] Examples of such catalysts include tertiary amine catalysts, organometallic catalysts, such as bismuth catalysts, alkyltin carboxylates, oxides, and tin mercaptiides. Specific examples of tertiary amine catalysts include N-methylmorpholine, N-methylimidazole, triethylenediamine, bis-(2-dimethylaminoethyl) ether, 1,4-diazabicyclo[2.2.2]octane (DABCO), dimethylcyclohexylamine, dimethylethanolamine, 2,2-dimorpholinyl diethyl ether (DMDEE), N,N,N-dimethylaminopropylhexahydrotriazine, dimethyltetrahydropyrimidine, tetramethylethylenediamine, dimethylcyclohexylamine, 2,2-N,N-benzyldimethylamine, dimethylethanolamine, and dimethylamino Examples include propylamine, pentadimethyldiethylenetriamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N',N'-trimethylaminoethylpiperazine, 1,1'-[[3-(dimethylamino)propyl]imino]bispropan-2-ol, 1,3,5-tris[3-(dimethylamino)propyl]hexahydro-1,3,5-triazine, NN-dimethyldipropylenetriamine, N,N,N'-trimethylaminoethylethanolamine, tris-2,4,6-dimethylaminomethylphenol, and 1,8-diazabicyclo[5.4.0]undeca-7-ene.

[0046] When an organometallic catalyst is used, it is any organometallic catalyst capable of catalyzing the reaction between an isocyanate and a functional group having at least one reactive hydrogen. Examples include bismuth catalysts, metal carboxylates such as tin carboxylates and zinc carboxylates. Examples of metal alkanoates include stannous octanoate, bismuth octanoate, or bismuth neodecanoate. The organometallic catalyst may be a bismuth catalyst or an organotin catalyst. Examples include dibutyltin dilaurate, dimethyltin dineodecanoate, dimethyltin mercaptide, dimethyltin carboxylate, dimethyltin dioleate, dimethyltin dithioglycolate, dibutyltin mercaptide, dibutyltin bis(2-ethylhexylthioglycolate), dibutyltin sulfide, dioctyltin dithioglycolate, dioctyltin mercaptide, dioctyltin dioctoate, dioctyltin dineodecanoate, and dioctyltin dilaurate.

[0047] D. Anti-settling and rheological additives Precipitated calcium carbonate can be added to either or both components of the formulation in amounts of up to approximately 10% by weight of the components, or approximately 1–10% by weight, or approximately 2–7% by weight, or approximately 2–5% by weight. Although not bound by any particular theory, the optional addition of precipitated calcium carbonate is thought to improve the prevention of sedimentation of conductive fillers. Furthermore, rheological additives such as waxy polyester polyols or urea-based rheological additives can be included in either or both components. These additives can be present in amounts of up to 10% by weight of the components, for example, 0.1%–8% by weight, 0.5%–6% by weight, or 1%–4% by weight.

[0048] IV. Methods and Uses In one embodiment, the process for preparing an adhesive formulation includes providing first and second components. When provided as a kit, each adhesive component may be packaged together or separately. Once the adhesive is ready to bond substrates together, the components may be mixed, blended, or combined to produce a reaction product when the combination of components cures. If necessary, one or more additional components may be added to the formulation. For example, at least one catalyst or at least one filler may be added to the adhesive formulation in either component before or after mixing the components together.

[0049] The amounts of components useful for producing the reaction products that make up the adhesive formulation may vary, but once the first and second components have been formulated (separately and individually) and are ready to be combined to form the reaction product adhesive, the first and second components can be mixed in a ratio ranging from 2:1 to 1:2, for example, 1:1.

[0050] When the components are prepared separately and individually, the contents can be mixed together at the desired concentration considered above, for example, at a temperature of 5°C to 80°C, for example, 15°C to 50°C, or for example, room temperature. In one embodiment, the contents can be mixed under vacuum. The mixing order is not important, and the remaining contents can be added after two or more compounds have been mixed together. The adhesive formulation contents constituting the components can be mixed together by any known mixing process and apparatus.

[0051] In another embodiment, the process for joining two substrates may include the steps of forming an adhesive layer between the two substrates and curing the layer to form a cured adhesive bonded to each substrate. For example, this process may include the steps of combining a first component and a second component, forming an assembly by forming an adhesive layer between the two substrates, partially curing the adhesive layer at room temperature or by applying heat to a part of the assembly or irradiating it with infrared light, and completing the curing of the adhesive layer in a subsequent curing step.

[0052] The application of the adhesive to the substrates to be bonded together can be carried out by any known device, such as a measuring / mixing / dispensing device, which can combine predetermined amounts of a first and second component (as an adhesive) and apply it to selected portions of the substrate. For example, in an automotive manufacturing process, the two components can be supplied in two separate containers. The first component can be drawn from one tank and the second component from another tank at the same time, and both flows can be combined using a known static or dynamic mixer when applying the combined adhesive components to the substrate. A partial curing step can be performed by curing only one or more predetermined local portions of the adhesive layer by applying heat to only one or more predetermined local portions of the assembly, thereby producing an adhesive layer having at least partially cured and uncured portions, which can then be cured in a subsequent curing step.

[0053] In one embodiment, a process for bonding at least a first substrate to at least a second substrate may include (1) bringing the first component and the second component into contact and mixing them at a temperature of, for example, 10-40°C or 20-30°C to form a uniform adhesive mixture; (2) applying the adhesive mixture to at least a portion of the first substrate; (3) bringing the second substrate into contact with the first substrate so that the mixture is positioned between the first and second substrates; and (4) exposing at least a portion of the mixture to heat under conditions such that the mixture is partially and sufficiently cured and the first and second substrates are sufficiently, i.e., sufficiently strong, bonded together. The process may further include (5) heating the two partially cured substrates at a certain temperature for a certain time so that the two substrates are completely bonded together as a single unit to completely cure the mixture. Heat may be applied in step (4) by any known heating means, such as infrared heating. The time between steps (4) and (5) may be about 1 hour or more in one embodiment, about 24 hours or more in another embodiment, or any time between the two above.

[0054] By curing the adhesive composition, a structure is formed comprising two or more substrates joined together with a cured adhesive based on the curable adhesive formulation, in which case the cured adhesive is positioned between portions of each substrate. In one embodiment, the substrates may include dissimilar substrates, i.e., substrates of different materials such as metal, glass, plastic, thermosetting resin, fiber-reinforced plastic, or mixtures thereof.

[0055] Adhesive formulations can be used in a variety of applications. Various articles containing cured adhesives are conceivable. In one embodiment, the article includes a battery module formed from at least one battery cell and a cooling unit, the battery module being connected to the cooling unit via a cured adhesive. In a further embodiment, the battery module is part of an electric vehicle. [Examples]

[0056] The following embodiments further illustrate the present disclosure. The scope of the present disclosure and claims is not limited by the scope of the following embodiments.

[0057] I. Material The aluminum hydroxide used was bimodal aluminum trihydrate (ATH). Its properties are as follows:

[0058] [Table 2]

[0059] The spherical monoelastic aluminum oxide used had particle sizes of 5 μm and 70 μm, respectively. The spherical aluminum oxide was purchased from Sibelco.

[0060] Surface-modified pulverized aluminum oxide was purchased from Sibelco and had the following properties:

[0061] [Table 3]

[0062] [Table 4]

[0063] I purchased hexadecyltrimethoxysilane from Evonik.

[0064] The epoxysilane was purchased from Momentive. It is an epoxide-functionalized silane. Its chemical structure is γ-glycidoxypropyltrimethoxysilane.

[0065] Polyetheramine was a triamine with a molecular weight of approximately 3000. It is a clear, nearly colorless liquid product with moderate viscosity and a very low vapor pressure.

[0066] [Table 5]

[0067] [Table 6]

[0068] To improve the settling prevention properties, precipitated calcium carbonate was used.

[0069] The catalysts used included dioctyl tin dineodecanoate supplied by Momentive, 33% 1,4-diazabicyclo[2.2.2]octane in dipropylene glycol purchased from Evonik, and a solution of 1,4-diazabicyclo[2.2.2]octane in propylene glycol, in which case the diazabicyclooctane is the active compound.

[0070] I purchased aminosilane from Evonik.

[0071] Rheological additives: CAPA 2201, a polyester polyol; RHEBYK-100 or RHEOBYK-7502, modified urea waxes.

[0072] DBU:1,8-Diazabicyclo(5.4.0)undeca-7-ene.

[0073] DESMOSEAL 2749: Silane-terminated polyurethane prepolymer of Evonik.

[0074] [Table 7]

[0075] II. Method A. Sample preparation In Comparative Examples CE1 to CE3 and Examples IE1 and IE2 of the present invention, all components listed in Table 1 or Table 2 (liquid components first, then solid components) were added to a planetary mixer or a double asymmetric centrifuge, mixed under vacuum for approximately 30 minutes, and then transferred to a cartridge, bucket, or drum for storage.

[0076] B. Exam Compression force: Compression force is measured using a tension meter (Zwick). The gap filler material is placed on a metal surface. A 40 mm diameter aluminum piston is placed on top of it, and the material is compressed to 5 mm (initial position). Then, the material is compressed at a speed of 1 mm / sec to 0.3 mm, and the force-displacement curve is recorded. The force (N) at a thickness of 0.5 mm is then recorded in the data table and considered as the compression force.

[0077] Thermal conductivity: Thermal conductivity is measured according to ASTM 5470-12 using a ZFW Stuttgart TIM tester. Measurements were performed in Spaltplus mode with a thickness of 1.8–1.2 mm. The described thermal interface is considered to be type I (viscous liquid) as described in ASTM 5470-12. The upper contact area is heated to approximately 40°C and the lower contact area to approximately 10°C, resulting in a sample temperature of approximately 25°C. Components A and B are mixed in a static mixer if applied from a manual cartridge system.

[0078] Gel Permeation Chromatography (GPC): Molecular weight data for polyurethane prepolymers were measured by gel permeation chromatography (GPC) using a Malvern Viscothek GPC max instrument. Emsure-THF (ACS, Reag. Ph EUR, for analysis) was used as the eluent, PLgel MIXED-D (Agilent, 300 × 7.5 mm, 5 μm) was used as the column, and MALVERN Viscotek TDA was used as the detector.

[0079] Lapped shear test: An aluminum substrate (from Novelis, AA6061 T6 1.92mm MF noPT nolub) (140×25mm, 1.9mm thickness) was used. The substrate was cleaned with isopropanol before use. After applying the thermal interface material to one substrate, the second substrate was joined within 5 minutes. The thickness was adjusted to 1.0mm, and the overlap area was 25mm×25mm. The material was cured and left to stand for 7 days at 23°C and 50% relative humidity before performing the lapped shear test. The lapped shear specimen was then mounted on a tensile strength meter, and the lapped shear test was performed using a tensile speed of 10mm / min as known to those skilled in the art. The force-displacement curve was monitored, and the strength at fracture was reported as the lapped shear strength.

[0080] Viscosity: Rheological measurements were performed using an Anton Paar MC302 rheometer with a parallel plate geometry and a diameter of 25 mm, with a fixed gap of 0.5 mm. The thermal interface material was placed between the two plates, and then shear rate tests were performed from 0.001 to 20 1 / s, with the viscosity at 10 1 / s reported.

[0081] Examples are reported below as comparative "CE" and the present invention "IE".

[0082] [Table 8]

[0083] [Table 9]

[0084] C. Results The results of the comparative example and the examples of the present invention are shown in Table 3 below. Component A in both the comparative example and the examples of the present invention is based on a silane-terminated polyurethane prepolymer (8% and 10%, respectively) combined with 84-85% filler (aluminum oxide or a mixture of aluminum oxide and aluminum hydroxide).

[0085] Comparative Example 1 does not contain polyetheramine but contains 0.3% hexadecyltrimethoxysilane and 82.5% filler (20% ATH, 62.5% Alox). The liquid components were mixed, then the filler was added, and the mixture was mixed under vacuum for 30 minutes. Very poor dispersion was observed, resulting in a granular powder product that could not be applied as an adhesive, and therefore a paste-like material could not be obtained. Comparative Example 3 does not contain polyetheramine but contains 1% hexadecyltrimethoxysilane and 84.9% filler (47% ATH, 37.9% Alox). Comparative Example 3 could not be mixed into a paste-like product because the dispersion was too poor. Comparative Example 2 contains 1% polyetheramine but no hexadecyltrimethoxysilane. In Comparative Example 2, the dispersion was insufficient, and a paste-like product could not be obtained.

[0086] When component B contains polyetheramine and hexadecyltrimethoxysilane, a good paste-like product with low viscosity and high thermal conductivity was obtained. To obtain a high thermal conductivity exceeding 1.8 W / mK, high filler levels are required in both components A and B. When polyetheramine and alkylsilane are mixed in component B, the formulation is miscible and results in low viscosity.

[0087] [Table 10]

[0088] The features and advantages of this disclosure are evident from the detailed specification, and the claims encompass all such features and advantages. Many variations will be conceivable to those skilled in the art, and any variations equivalent to those described herein are included within the scope of this disclosure. Those skilled in the art will understand that the underlying concepts of this disclosure can be used as a basis for designing other compositions and methods to accomplish some of the objectives of this disclosure. Consequently, the claims should not be considered limited by this specification or the examples.

Claims

1. An uncured two-part thermal conductive adhesive compound, a) The first component, i) 1% to 25% by weight of the first component, ii) At least 70% by weight of the first component, a first thermally conductive filler, iii) 0.1% to 5% by weight of the first component, iv) A first plasticizer in an amount of 0% to 10% by weight of the first component, The first component includes, b) A second component, i) 0.01% to 5% by weight of water of the second component, ii) At least 70% by weight of the second component, a second thermally conductive filler, iii) 0.1% to 5% by weight of the second component, iv) 0.1% to 5% by weight of the second component, v) A second plasticizer in an amount of 1% to 20% by weight of the second component, It has a second component which includes The uncured adhesive compound is an uncured two-part thermally conductive adhesive compound in the form of a kit in which the first component and the second component are not mixed.

2. The adhesive compound according to claim 1, wherein the first component comprises 5% to 25% by weight of the silane-terminated urethane prepolymer.

3. The adhesive compound according to claim 1, wherein the first component comprises 5% to 15% by weight of the silane-terminated urethane prepolymer.

4. The adhesive compound according to claim 1, wherein the first component comprises 8% to 12% by weight of the silane-terminated urethane prepolymer.

5. The adhesive compound according to claim 1, wherein the first and second components independently comprise 70% to 95% of each of the first and second thermally conductive fillers.

6. The adhesive compound according to claim 1, wherein the first and second components independently comprise 75% to 85% of each of the first and second thermally conductive fillers.

7. The adhesive compound according to claim 1, wherein the first and second components independently comprise 80% to 85% of each of the first and second thermally conductive fillers.

8. The adhesive compound according to claim 1, wherein the first or second thermally conductive filler comprises aluminum trihydrate, aluminum oxide, or a combination thereof.

9. The adhesive formulation according to claim 1, wherein the second component comprises 0.1% to 2% by weight of water relative to the second component.

10. The adhesive formulation according to claim 1, wherein the second component comprises 0.1% to 1% by weight of water relative to the second component.

11. The adhesive formulation according to claim 1, wherein the second component comprises 0.5% to 3% by weight of polyetheramine.

12. The adhesive formulation according to claim 1, wherein the second component comprises 0.5% to 1.5% by weight of polyetheramine.

13. The adhesive formulation according to claim 1, wherein the polyetheramine has a molecular weight in the range of 200 to 6,000 g / mol.

14. The adhesive formulation according to claim 1, wherein the polyetheramine has a molecular weight in the range of 1,500 to 4,000 g / mol.

15. The adhesive formulation according to claim 1, wherein the polyetheramine has a molecular weight in the range of 2,000 to 3,500 g / mol.

16. The adhesive formulation according to claim 1, wherein the polyetheramine has a molecular weight in the range of 2,500 to 3,500 g / mol.

17. The aforementioned polyetheramine is given by formula: 【Chemistry 1】 (In the formula, n is an integer in the range of 1 to 5, R 1 and R 2 The adhesive formulation according to claim 1, wherein each residue has at least one residue that is independently hydrogen or optionally substituted with a C1-C4 alkyl group.

18. The aforementioned polyetheramine has the following structure: 【Chemistry 2】 The adhesive compound according to claim 1, having (wherein x, y, and z are the sum of integers in the range of 6 to 90).

19. The adhesive compound according to claim 1, wherein the first and second components independently comprise 0.5% to 3% by weight of each of the first and second organically functionalized silanes.

20. The adhesive compound according to claim 1, wherein the first and second components independently comprise 0.5% to 1.5% by weight of each of the first and second organically functionalized silanes.

21. The adhesive formulation according to claim 1, wherein the first or second organically functionalized silane is an alkylsilane.

22. The first or second organically functionalized silane has the following structure: 【Transformation 3】 (In the formula, n is an integer in the range of 0 to 24, R 3 ~R 7 The adhesive compound according to claim 1, wherein ( is independently hydrogen, or optionally substituted C1-C4 alkyl).

23. The adhesive compound according to claim 1, wherein the first component comprises 1% to 8% by weight of the first plasticizer.

24. The adhesive compound according to claim 1, wherein the first component comprises 3% to 6% by weight of the first plasticizer.

25. The adhesive compound according to claim 1, wherein the second component comprises 3% to 15% by weight of the second plasticizer.

26. The adhesive compound according to claim 1, wherein the second component comprises 5% to 10% by weight of the second plasticizer.

27. The first plasticizer (if present) or the second plasticizer has the following structure: 【Chemistry 4】 (In the formula, R 8 ~R 10 The adhesive compound according to claim 1, wherein ( is independently and optionally substituted branched or linear C1-C24 alkyl groups).

28. The adhesive compound according to claim 1, further comprising 0.1% to 3% by weight of an adhesion promoter in the first component, the second component, or both components.

29. The adhesive compound according to claim 1, further comprising 0.1% to 1% by weight of an adhesion promoter in the first component, the second component, or both components.

30. The adhesive compound according to claim 1, further comprising 0.2% to 0.5% by weight of an adhesion promoter in the first component, the second component, or both components.

31. The adhesive compound according to claim 1, wherein the adhesion promoter comprises aminosilane, epoxysilane, or a combination thereof.

32. The adhesive compound according to claim 1, further comprising in the first component, the second component, or both components, a catalyst in an amount of 0.01% to 3% by weight of the component, wherein the catalyst promotes the reaction between water and the silane-terminated urethane prepolymer.

33. The adhesive compound according to claim 1, further comprising in the first component, the second component, or both components, 0.01% to 1% by weight of a catalyst, wherein the catalyst promotes the reaction between water and the silane-terminated urethane prepolymer.

34. The adhesive compound according to claim 1, further comprising in the first component, the second component, or both components a catalyst in an amount of 0.2% to 0.5% by weight of the component, wherein the catalyst promotes the reaction between water and the silane-terminated urethane prepolymer.

35. A cured adhesive prepared by mixing the first component and the second component of the adhesive compound described in claim 1, and curing the mixture.

36. An article comprising the cured adhesive described in claim 35.

37. The article according to claim 36, comprising a battery module formed of at least one battery cell and a cooling unit, wherein the battery module is connected to the cooling unit via the cured adhesive.

38. A process for curing an adhesive compound according to claim 1, comprising mixing the first component and the second component of the adhesive compound and curing the mixture.

39. The process according to claim 38, wherein the first and second components of the adhesive compound are mixed in a ratio in the range of 2:1 to 1:

2.

40. The process according to claim 39, wherein the first and second components of the adhesive compound are mixed in a 1:1 ratio.

41. The process according to claim 38, wherein the first and second components of the adhesive compound are mixed at a temperature in the range of 10°C to 40°C.

42. The process according to claim 41, wherein the first and second components of the adhesive compound are mixed at a temperature in the range of 20°C to 30°C.

43. A cured adhesive prepared by the process described in claim 38.

44. The process according to claim 38, further comprising applying the mixture to an inorganic substrate before the mixture is completely cured.

45. The process according to claim 44, further comprising bonding the inorganic substrate on which the mixture is coated to a second non-inorganic substrate to a bonded assembly before the mixture is completely cured.

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