Injectable thermal contact and fill materials and their use in

Abstract

The invention relates to an injectable thermal contacting and filling material, which consists of a component A and a component B, the component A comprises a silylated prepolymer or a mixture of silylated prepolymers, and the silylated prepolymer is based on polyurethane, polyol / diol or polyacrylate; a plasticizer which is a multifunctional carboxylic acid ester; a wetting and dispersing additive having at least one amine value of greater than 20 mg KOH / g as determined according to DIN 19645; a mixture of functionalized organosilanes; znO and another thermal conductive filler or a mixture of a plurality of thermal conductive fillers. The component B comprises a plasticizer which is a multifunctional carboxylic ester; a wetting and dispersing additive having at least one amine value of greater than 20 mg KOH / g as determined according to DIN 19645; a thermally conductive filler or a mixture of a plurality of thermally conductive fillers; water and an organometallic catalyst. The volume mixing ratio of the component A to the component B is (1: 1)-(10: 1).

Description

[0001] The operation of electronic and energy technology systems generates heat that must be dissipated quickly and efficiently from the heat-generating elements. To establish thermal contact between active components and the corresponding heat supply or heat dissipation devices, fixed mechanical connections are typically established using screws, clamps, or physical connections such as welding or brazing. While mechanical fastening offers the advantage of removable connections, heat can only be transferred through a few contact points between the active components. Because of the intervening air layer, which is a poor thermal conductor, the generated heat cannot be fully dissipated. To improve heat transfer, thermally conductive materials are added between active components—that is, at the joints between the heat-generating and heat-dissipating elements. These materials perform a dual function: they both transfer heat and connect the active components together.

[0002] Such thermally conductive materials are known in the prior art in the form of thermally conductive pastes. Thermally conductive pastes are used, on the one hand, in microelectronics for connecting very small components.

[0003] Typically, this type of thermal paste is applied to individual active components in small-area applications. By applying force to the components, they are connected to each other (press-fit).

[0004] In the electronics field, the surfaces requiring bonding are extremely small. Furthermore, high switching frequencies, high clock speeds in integrated circuits or processors, and other components, generate significant heat that must be dissipated across these small surfaces to avoid damaging the components and the entire device. Therefore, thermal conductivity is a primary consideration when selecting thermal contact and filler materials in this field, as these materials must dissipate significant amounts of heat across a very small surface area.

[0005] The use of thermally conductive pastes for connecting large-area components is described in DE 0 2018 102 989 B4. This document discloses a reactively curing thermally conductive paste based on silanized prepolymers for thermal management of modular batteries comprising a plurality of interconnected battery cells, such as in electric vehicles.

[0006] In large-area applications, such as in batteries for electric vehicles, thermal paste is applied to a carrier or base plate before installing individual batteries or prefabricated battery modules consisting of multiple battery cells. It is then pressed to a specified thickness during the installation of the individual batteries or prefabricated battery modules.

[0007] The requirements for thermal contacts and filler materials for large area applications are significantly more complex for the following reasons.

[0008] The larger the connection area, the greater the force required to join these surfaces together. Due to the inherently high viscosity of highly filled systems such as the aforementioned thermal pastes, significant forces must be applied during production to achieve the pressing of active components within acceptable cycle times. However, cycle times cannot be arbitrarily accelerated by increasing the applied force. Even individual batteries or prefabricated battery modules comprising multiple battery cells for electric vehicles can only withstand so much force before deformation, damage to the electrochemical structure, or other defects occur, which can manifest immediately or lead to a significant reduction in the service life of the battery or battery, and therefore the vehicle.

[0009] The drawbacks of the aforementioned processes, including press-fitting active components, can be avoided by using a so-called injection process. In this process, the contact and filler materials are injected rather than applied. This significantly speeds up the assembly of multiple battery cells during production, for example, while significantly reducing the risk of cell damage compared to the aforementioned conventional processes.

[0010] To enable the use of the injection process, design and process considerations require that a defined gap be filled completely and air-free by the injection of the thermal contact and filler material, thereby ensuring excellent thermal conductivity of the components to be connected. To ensure a complete and air-free filling of the gap with the thermal contact and filler material, injection is performed from one or more injection points. This ensures that all air in the gap is expelled. The injection process must be designed to avoid the formation of air bubbles during the injection process. This can be achieved through flow simulation or by appropriately designing the injection process. This can be achieved, firstly, by the type and position of the injection openings and, secondly, by targeted variation of the injection pressure at one or more injection openings. The injection process is concluded when the thermal paste flows out of the air outlet holes and no longer contains air in the gap.

[0011] However, the requirements for thermal contact and filler materials suitable for injection molding are very high. First, they must have an appropriate viscosity. If the viscosity is too high, as in the thermal pastes described in DE 0 2018 102989 B4 and other prior art materials, high backpressure will be generated during the injection process, requiring a powerful pump and injection pressure. If this is used for large-area applications, the requirements for the injection pump will be extremely high, sometimes even impossible to achieve.

[0012] Since the demand for thermally conductive contact and filling materials, especially for large-area applications, is increasing, as new battery concepts, for example in the field of electric vehicles, increasingly rely on effective thermal management, the object of the present invention is to provide a thermal contact and filling material which has the required properties for high-volume and large-scale applications in the injection process and is able to withstand high heat transfer.

[0013] Surprisingly, the object of the present invention is achieved by an injectable thermal contact and filling material having the features of claim 1. Preferred developments of the subject matter of the invention are the subject matter of the dependent claims. Further preferred developments of the injectable thermal contact and filling material according to the invention can be gathered from the following description and examples.

[0014] In the present invention, "prepolymer" refers to any polymer or oligomer that is pre-elongated by a specific pre-reaction and / or has new functional groups introduced by a specific pre-reaction so that a selected polymerization reaction can be carried out in a subsequent step.

[0015] For the purposes of the present invention, "silanized prepolymer" refers to an oligomer, polymer or prepolymer that has been silanized with alkoxy groups. Silane-modified prepolymers condense in the presence of water due to the detachment of the alkoxy groups, forming a reticulated polymer network. According to the above definition of prepolymer, it is unimportant whether the prepolymer backbone already consists of prepolymers (e.g., based on polyurethane prepolymers) or is a pure oligomer or polymer. Due to the specific pre-reaction of the silanization, all silane-modified polymers are also prepolymers according to the above definition.

[0016] Since there is no general consensus on the nomenclature and differentiation of the various silane-modified prepolymers, all commercially or non-commercially produced silylated polymers and prepolymers are considered to be silylated prepolymers in the sense of the present invention.

[0017] In the present invention, " plasticizer " refers to low viscosity, non-reactive additive to selected cross-linking chemical reaction, and its effect is to reduce the viscosity of liquid component.After matrix hardening, this plasticizer stays in the polymer network, reduces the mechanical property of formed polymer, makes it softer, more elastic, more flexible and / or more ductile, because the polymer network with very open network structure usually has higher fluidity owing to containing plasticizer.From chemical point of view, plasticizer is not combined with polymer matrix with covalent bond, but interacts with the polar group in polymer network through its polar group, thereby is attached between polymer chain, makes polymer chain have higher fluidity, makes whole structure more flexible. Plasticizer is low molecular weight normally, but also can use polymer plasticizer, for example plasticizer based on polypropylene glycol.Typical example of plasticizer is material based on carboxylic ester chemistry, fatty oil, soft resin and camphor.

[0018] For the purposes of this invention, "wetting and dispersing additives" refer to additives that have the property of mixing two incompatible substances. This is commonly seen in the formation of emulsions in liquid-liquid systems. However, it is also crucial in the formation of stable liquid-solid systems. Stabilization of such dispersions is achieved by compatibility of interfacial tensions and improved wetting of the solid particles with the liquid medium. These additives are designed to ensure that the liquid phase wets the solid as well as possible, ideally completely, which also facilitates the shearing required to separate agglomerates into individual particles during the manufacturing process. Furthermore, wetting and dispersing additives remain on the particle surface and stabilize the particles in the liquid phase, thereby forming a stable dispersion or at least minimizing reagglomeration of these fillers and thus preventing rapid sedimentation / precipitation. Because wetting and dispersing additives act as surfactants and some amphiphilic molecules or polymers are readily soluble in the liquid phase, particle stability also benefits from the pronounced steric effects of these chains around the particle surface. This creates repulsive forces when the particles approach each other, necessitating a certain distance between the particles to minimize mechanical interactions (e.g., particle agglomeration, frictional effects that increase viscosity, etc.). This effect can be achieved through steric repulsion, or by introducing charges through chemical functional groups (carboxylates, ammonium groups, etc.) in a similar way. These charges achieve the same effect through electrostatic repulsion between each other. The two modes of action can also be used in combination to achieve electrostatic stabilization of particles. In general, static electricity and electrostatic repulsion are very effective for relatively polar liquids, while steric repulsion is usually only used for liquids with very low polarity.

[0019] In the present invention, "organosilane" refers to a compound having a silicon group, at least one organic residue and one to three hydrolyzable substituents or hydroxyl groups. Hydrolyzable groups are, for example, alkoxy groups. They can be oligoethylene glycol chains or acetoxy functional groups. Reactive silane groups are completely or partially hydrolyzed alkoxysilane groups that subsequently form silanol groups. There are many different types of such organosilanes, which are mainly different in the structure of the organic residue and are described by their chemical structure. For example, hydroxysilanes, isocyanate silanes, aminosilanes, sulfur silanes, and vinyl silanes all have an organic chain between the silicon group and at least one other functional group. Of course, there are also organosilanes with a variety of functional groups, such as aminosilanes containing secondary and primary amino groups, or organoalkoxysilanes whose organic moieties contain at least one hydroxyl (OH), isocyanate, amino, or vinyl group.

[0020] According to the functional groups contained, organosilanes can be divided into the following categories:

[0021] - No other functional groups (organic chains), such as octyltrimethoxysilane, OCTMO;

[0022] - primary amine functional groups, such as 3-aminopropyltrimethoxysilane, AMMO;

[0023] - secondary amine functional groups, such as N-(n-butyl)-3-aminopropyltrimethoxysilane;

[0024] - diamino functions, for example N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, DAMO;

[0025] - epoxy functions, such as 3-glyceryloxypropyltrimethoxysilane, GLYMO;

[0026] - sulfur functions, such as 3-mercaptopropyltrimethoxysilane, MTMO;

[0027] - methacrylic acid functional, such as 3-methacryloxypropyltrimethoxysilane, MEMO;

[0028] - Vinyl functional, such as vinyltrimethoxysilane, VTMO.

[0029] The chemically and commercially available compounds mentioned in the above groups are only examples and the groups are not limited to these compounds.

[0030] In the present invention, "thermally conductive fillers" refer to chemical compounds added to the formulation to ensure filling and thermal conductivity at the same time. Typical thermally conductive fillers are:

[0031] -Metals, however, are not suitable for many applications due to their electrical conductivity;

[0032] -aluminium oxide / aluminium hydroxide; and

[0033] -magnesium oxide / magnesium hydroxide; and

[0034] Diamond, carbon nanotubes, aluminum nitride (AlN), boron nitride (BN), graphite.

[0035] In the present invention, "catalyst" refers to a chemical compound that increases the reaction rate or reduces the activation energy of the reaction by forming an intermediate between the catalyst and the reactants without being consumed in the reaction itself.

[0036] The injectable thermal contact and filling material of the present invention comprises component A and component B, wherein:

[0037] Component A includes:

[0038] 1.A) Silylated prepolymers or mixtures of silylated prepolymers, wherein the silylated prepolymers are based on polyurethanes, polyols / diols or polyacrylates;

[0039] 2. A) a plasticizer which is a polyfunctional carboxylic acid ester;

[0040] 3.A) Wetting and dispersing additives having at least one amine value of >20 mg KOH / g, determined according to DIN 19645;

[0041] 4.A) a mixture of functionalized organosilanes;

[0042] 5. A) a mixture of ZnO and another thermally conductive filler or multiple thermally conductive fillers; and

[0043] Component B includes:

[0044] 1.B) a plasticizer which is a polyfunctional carboxylic acid ester;

[0045] 2.B) wetting and dispersing additives having at least one amine value of >20 mg KOH / g, determined according to DIN 19645;

[0046] 3.B) a thermally conductive filler or a mixture of multiple thermally conductive fillers;

[0047] 4.B) Water; and

[0048] 5.B) an organometallic catalyst; and

[0049] The volume mixing ratio of component A to component B is 1:1 to 10:1.

[0050] Surprisingly, the injectable thermal contact and filling material of the present invention exhibits processing properties essential in injection processes. Surprisingly, it was found that adding zinc oxide to the mixture produces surprising changes in processing properties essential in injection applications.

[0051] Developers in this field are well aware that to liquefy thermally conductive compositions, on the one hand, a formulation with larger particles should be selected, as larger particles have a smaller surface-to-volume ratio. On the other hand, formulations with particles that are close to round should be chosen. This helps reduce viscosity, as particles in highly filled systems act more like ball bearings, sliding against each other without getting stuck. However, such compositions often suffer from significant drawbacks in terms of application and injection. A significant drawback is that such compositions have a high tendency to settle, which significantly impacts storage stability. During storage and transport, the filler settles and separates, forming a dense layer that cannot be fully reassembled into the suspension even under strong shear. Furthermore, during injection, such compositions have the potential for separation of the solid and liquid components due to the high pump pressures required, making continuous and reproducible injection impossible.

[0052] To avoid these drawbacks, thixotropic agents are often added to the composition, which thicken the liquid phase through particle interactions or, for example, gelation. However, the addition of thixotropic agents does not make the formulation free-flowing and as fluid and injectable as possible. Instead, they form a high-viscosity paste that, while preventing sedimentation, is also unsuitable for injection.

[0053] Surprisingly, partial replacement of the thermally conductive filler with zinc oxide significantly improves the filler's settling behavior and injectability, with minimal effect on viscosity. Since zinc oxide itself has high thermal conductivity, its replacement does not reduce thermal conductivity. This provides an injectable thermal contact and filling material that does not exhibit the aforementioned drawbacks and is suitable for large-area applications.

[0054] A preferred development of the injectable thermal contact and filling material is the use of silylated prepolymers or mixtures of silylated prepolymers, wherein the silylated prepolymers are based on polyurethanes, polyols / diols or polyacrylates.

[0055] A preferred development of the injectable thermal contact and filling material provides that component A comprises exclusively silylated prepolymers based on polyurethane.

[0056] The common names of the silylated prepolymers referred to in the present invention include compounds represented by the following formula:

[0057]

[0058] In the above formula, A represents the backbone (main chain) of the polymer or prepolymer, which can be

[0059] - Polyols / diols (e.g. polyether polyols / diols, polypropylene glycol)

[0060] - having trans polyacrylate or

[0061] It can even be a prepolymer based on a different technology, for example a polyurethane-modified prepolymer, which is modified with alkoxy-protected silane groups in a subsequent reaction step.

[0062] According to the present invention, the substituent R 1 、R 2 and R 3 can be a chemical group, wherein at least R 1 and R 2 is an alkoxy group, R 3 is an alkoxy group or an alkyl group.

[0063] According to the present invention, an alkyl group is a C1-C 10 According to the present invention, C1-C 10Alkyl refers to a straight-chain or branched saturated hydrocarbon group containing 1 to 10 carbon atoms. It includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl, isohexyl, 2-ethylhexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, n-decyl, etc.

[0064] According to the present invention, the alkoxy group refers to O-C1-C 10 Alkyl group. C1-C 10 The alkyl group is as described above.

[0065] Another preferred improvement of the injectable thermal contact and filler material is that the alkoxy group is selected from the group consisting of: OCH3 and OCH2CH3, and the alkyl group is CH3.

[0066] Another particularly preferred development of the injectable thermal contact and filling material is that the alkoxy groups are OCH3 and the alkyl groups are CH3.

[0067] Another preferred improvement of the injectable thermal contact and filling material is that the silylated prepolymer or the mixture of silylated prepolymers is selected from the following group:

[0068] -Group A

[0069] This group includes prepolymers based on a polyol / diol backbone with the following chemical names: Silane-modified polymers (SMP), modified silane polymers, MS polymers, silane-terminated polymers.

[0070] Commercially available prepolymers belonging to this group are, for example:

[0071] Dimethoxysilane MS polymer S (such as S303H) and high-strength dimethoxysilane MS polymer SAX (such as SAX350).

[0072] The most suitable prepolymer for use in injectable thermal contact and filler materials is the prepolymer of formula A-1:

[0073]

[0074] -Group B

[0075] This group includes silylated prepolymers with an oligomeric polyacrylate backbone.

[0076] Commercially available prepolymers belonging to this group are, for example: Kaneka XMAP SA (eg Kaneka XMAP SA100).

[0077] The most suitable prepolymer for use in injectable thermal contact and filler materials is the prepolymer of formula B-1:

[0078]

[0079] R 1 is H, C1-C6-alkyl;

[0080] R 2 H, C1-C6-alkyl

[0081] -Group C

[0082] Group C includes prepolymers whose polymer backbone itself consists of a polyurethane prepolymer and therefore contains polyurethane groups. The polyol used in the backbone may consist of a polyether polyol as shown herein, but other "polyols" may also be used.

[0083] The chemical names of these prepolymers are as follows: silane-terminated polyurethane (SPU or STPU), silane-terminated polyurethane, silane-modified polyurethane.

[0084] Commercially available prepolymers belonging to this group are, for example: Polymer ST (for example Polymer ST44) and Geniosil STP-E (for example Geniosil STP-E30)

[0085] The most suitable prepolymer for use in injectable thermal contact and filler materials is the prepolymer of formula C-1:

[0086]

[0087] Another preferred improvement of the injectable thermal contact and filling material is that one or more silylated prepolymers are selected from the group consisting of:

[0088] SAX350 (Group A)

[0089] XMAP SA120S (Group B)

[0090] Polymer ST-61LV (Group C).

[0091] Another particularly preferred development of the injectable thermal contact and filling material is that component A comprises only one silylated prepolymer, which is a silylated prepolymer from group C, preferably ST-61LV.

[0092] Another preferred improvement of the injectable thermal contact and filling material is that the plasticizer is a multifunctional carboxylic acid ester.

[0093] According to the present invention, phthalates, such as diethylhexyl phthalate or dioctyl phthalate, can be used as plasticizers. However, due to their potential harmful effects on humans, phthalates are currently included in the ECHA Candidate List of Substances of Very Important Concern (SVHC List). As alternatives to phthalates, alkyl sulfonates and citric acid-based plasticizers (such as triethyl citrate) or adipic acid-based plasticizers (such as diethylhexyl adipate or diethyloxyhexyl adipate) can be used.

[0094] Plasticizers should be selected based on their function in the injectable thermal contact and filling materials of the present invention, but it should be noted that these plasticizers are not completely identical to the plasticizers in other formulations. In the injectable thermal contact and filling materials of the present invention, the plasticizers have the following functions:

[0095] - Reduce the viscosity of liquid components

[0096] Silicone-functionalized prepolymers are typically high-viscosity raw materials, even though low-viscosity systems are typically chosen for formulation. Nevertheless, the achievable filling level of thermally conductive fillers is directly related to the mixed viscosity of the liquid component. For this reason alone, low-viscosity additives are required to minimize the mixed viscosity of the liquid component, thereby achieving the desired filling level without making the finished formulation too high in viscosity to affect the application.

[0097] - Improve the flexibility of cured materials

[0098] At very high filler contents, the polymer network loses its degrees of freedom, and a matrix that is very flexible and has a high elongation at break when unfilled becomes increasingly less flexible, with the elongation at break often falling to very low values. The internal wettability of the filler is improved by the use of plasticizers, as the plasticizer molecules not only adhere to the polymer chains as defined above, but ideally also form a compatibility layer between the filler particles and the polymer chains, thereby significantly increasing the degrees of freedom of the polymer chains that were previously severely restricted by the filler particles.

[0099] Silylated prepolymers typically have a high molecular weight, primarily due to their long (pre)polymer backbone. This backbone separates the crosslinks, creating a dense, flexible network suitable for applications such as flexible adhesives and / or sealants. As mentioned in the first point, the viscosity of these silylated prepolymers is crucial for the application, so only low-viscosity types are fully suitable. However, since a high molecular weight backbone also increases the viscosity of the prepolymer, low molecular weight silylated prepolymers are generally more suitable. Of course, these prepolymers also have a higher crosslink density, resulting in higher mechanical properties and lower flexibility, a phenomenon further exacerbated by the effects of high filling levels mentioned above. Attempts to compensate for this phenomenon have been made by using plasticizers, exploiting the "plasticizer effect" between the cured prepolymer and the filler particles (see the second point), while minimizing the volume fraction of the prepolymer used. This, of course, can result in an incompletely formed polymer network, as not all polymer chains are fully crosslinked. This results in a polymer network with larger meshes, which at least partially offsets the disadvantages of the low molecular weight silylated prepolymer used, making the network more flexible, with lower modulus and lower mechanical properties, similar to the effects that can be achieved using long-chain silylated prepolymers.

[0100] Based on the above description, the following plasticizers have proven to be particularly suitable for use in the injectable thermal contact and filling materials of the present invention:

[0101] Oxsoft 3G8:CAS 94-28-0

[0102] -Triethylene glycol di(2-ethylhexanoate)

[0103] -2,2'-Ethylene glycol diethyl di(2-ethylhexanoate)

[0104] Cereplas L810TM:CAS 90218-76-1

[0105] -1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters

[0106] Oxsoft TOTM LE:CAS 3319-31-1

[0107] -Tris(2-ethylhexyl)benzene-1,2,4-tricarboxylate

[0108] -Trioctyl trihydroxycarboxylate.

[0109] Most preferred are di-, tri- or polyfunctional carboxylates.Another particularly preferred modification of the injectable heat contact and filler material is the use of Oxsoft 3G8 as a plasticizer.

[0110] Another preferred development of the injectable thermal contact and filling material is that the wetting and dispersing additive has at least functionalized amine groups, which may optionally contain acidic groups, for example phosphorus groups or carboxylate groups.

[0111] Particularly preferred are: Dispbyk2157 or Byk W969.

[0112] Disperbyk 2157 and Byk W 969 have in common that they contain amine groups, which are defined at least by the amine value for wetting and dispersing additives according to DIN 16945. Optionally, they may also contain other functional groups, such as phosphorus or carboxylate groups, which can also be surface-active. Optionally, the wetting and dispersing additives may also have an acid number determined according to DIN EN ISO 2114.

[0113] Wetting and dispersing additives having an amine number of at least 20 mg KOH / g and optionally an acid number are considered to be of particular importance.

[0114] Another preferred development of the injectable thermal contact and filling material is that component A comprises a mixture of functionalized organosilanes.

[0115] Both monofunctional and polyfunctional organosilanes are within the scope of the present invention. Polyfunctional organosilanes exist in the form of oligomeric or precondensed silanes. Due to their high functional group density, they react faster in the oligomeric form and can more effectively increase the local crosslink density of the cured polymer or improve the adhesion of the adhesive to the surface.

[0116] First, all of the aforementioned organosilanes function as crosslinkers. They are incorporated into the network of the silylated prepolymer, thereby increasing the crosslink density of the prepolymer. The functional groups they contain are crucial for their functionality within the formulation.

[0117] Another preferred improvement of the injectable thermal contact and filling material is to use the following organosilane:

[0118] In the formulation, the following organosilanes (including their mode of function) are relevant:

[0119] a) Amino-functional organosilanes

[0120] They generally accelerate silane condensation reactions and, in addition to their general properties, can be used as co-catalysts. They also have a similar effect as epoxy-functional organosilanes, improving adhesion to various substrates.

[0121] Another particularly preferred development of the injectable thermal contact and filling material is the use of:

[0122] -AMMO or

[0123] - Amine-containing oligomeric pre-shrinked silanes (such as SIVO).

[0124] b) Vinyl-functional organosilanes

[0125] Their primary drying effect is that fillers and plasticizers used during production have a certain residual moisture or water content. Although this amount is very low, it can negatively impact the storage stability of silylated prepolymers due to undesirable silane polycondensation over time, leading to a significant increase in viscosity and, consequently, reduced application performance. For drying purposes, vinyl-functional organosilanes are added to the formulation, thereby drying the filler and other formulation components in situ. The small amount of unreacted vinyl-functional organosilanes remaining in the formulation allows the formulation to have viable storage stability without the need for specialized equipment (e.g., production and storage of the components under inert gas, pre-drying of the filler in a special dryer).

[0126] Another particularly preferred development of the injectable thermal contact and filling material is the use of VTMO.

[0127] c) Epoxy-functional organosilanes

[0128] In addition to the general properties described above, epoxy silanes possess other interesting properties that lead to their inclusion in formulations. First, epoxy and amine-functional organosilanes can react with each other (beyond silane condensation), forming crosslinks. Furthermore, epoxy silanes are known for their adhesion-improving properties on a wide range of surface chemistries, from polymers to metals, contributing to a balanced product performance.

[0129] Another particularly preferred development of the injectable thermal contact and filling material provides that the mixture of functionalized organosilanes comprises at least one amino-functional, vinyl-functional, or epoxy-functional organosilane.

[0130] Another particularly preferred improvement of the injectable thermal contact and filler material is that the mixture of functionalized organosilanes comprises at least two organosilanes selected from the group consisting of amino-functionalized organosilanes, vinyl-functionalized organosilanes, and epoxy-functionalized organosilanes.

[0131] Another particularly preferred development of the injectable thermal contact and filling material is that the mixture of functionalized organosilanes comprises at least an amino-functional organosilane and a vinyl-functional organosilane.

[0132] Another particularly preferred improvement of the injectable thermal contact and filler material is one in which the mixture of functionalized organosilanes includes an amino-functionalized organosilane, a vinyl-functionalized organosilane, and an epoxy-functionalized organosilane.

[0133] Another particularly preferred development of the injectable thermal contact and filling material provides that the at least one functionalized organosilane is an oligomeric silane.

[0134] Another particularly preferred development of the injectable thermal contact and filling material is the use of GLYMO.

[0135] Another particularly preferred development of the injectable thermal contact and filling material is the use of zinc oxide as a filler.

[0136] Another preferred development of the injectable thermal contact and filling material is to use, in addition to ZnO, a thermally conductive filler selected from the group consisting of Al(OH) 3 , Al 2 O 3 .

[0137] Another preferred improvement of the injectable thermal contact and filling material is that the total filler content in components A and B is 80 to 95% by weight, preferably 88 to 93% by weight, more preferably 88 to 90% by weight, wherein the ZnO content in the filler mixture is correspondingly 10 to 30% by weight, preferably 15 to 25% by weight, more preferably 15 to 20% by weight.

[0138] Another preferred development of the injectable thermal contact and filling material provides that at least one thermally conductive filler has a surface coating and / or surface functionalization, which preferably has hydrophobic properties.

[0139] It is well known that silylated prepolymers react in the presence of water during the condensation reaction. The water required for this reaction is typically introduced primarily via fillers. As mentioned above, the filler surface is at least partially covered with water due to atmospheric humidity. Furthermore, filler particles store water in their pores and cracks through porosity and capillary action.

[0140] The filler can be dried by adding a vinyl-functional organosilane, as shown in one embodiment of the present invention. However, in this case, the amount of vinyl-functional organosilane required must be adjusted based on the moisture content of the filler. If the filler is not fully dried, the storage stability of the finished component will be affected, as the viscosity of the liquid component will slowly increase, primarily due to the slow onset of polycondensation of the polymer.

[0141] This can be avoided by using partially hydrophobized fillers in the formulation. Hydrophobization of fillers is a process used on a large scale in industry, whereby fillers are coated with surface-active molecules or polymers as much as possible. Depending on the filler, this is achieved by using, for example, fatty acids, organosilanes, organotitanates, functionalized or non-functionalized polymers, which allow these coating additives to be chemically or physically adsorbed onto the surface, thereby achieving surface functionalization.

[0142] This very thin coating makes the filler surface more hydrophobic, so that less water from the air humidity adheres to the filler, which reduces the residual moisture content of the filler. Therefore, by optimizing the choice of these coating agents, it is possible to achieve similar effects to the wetting and dispersing additives mentioned above, without having to use these additives in this case.

[0143] Another preferred development of the injectable thermal contact and filler material is that component B comprises a catalyst.

[0144] Another particularly preferred improvement to the injectable heat contact and filler material is one in which the catalyst is an organometallic complex. All commonly available organometallic catalysts can be used. Tin complexes are used as an example here, but the present invention is not limited thereto. Suitable catalysts include preferably dibutyltin dilaurate (DBTL), dioctyltin dilaurate, their oxides (such as dibutyltin oxide and dioctyltin oxide), or other tin complexes to which exchange ligands are added (such as dioctyltin diacetylacetonate or dioctyltin / dibutyltin silane complexes).

[0145] Another particularly preferred development of injectable thermal contact and filler materials is that the catalyst can be a co-catalyst base, such as an amine, which acts as a proton acceptor. These are typically used in the formulation in the form of amino-functionalized organosilanes and are summarized in the description of organosilanes.

[0146] Another particularly preferred improvement of the injectable thermal contact and filler material is that the catalyst is an acid catalytic system.

[0147] Another particularly preferred development of the injectable thermal contact and filling material is that it contains no silicone.

[0148] The advantage of this measure is that it ensures that no volatile silicon compounds are deposited on the surface surrounding the active ingredient in the system. This prevents the adhesion of the coating or adhesive layer on the contaminated surface from being affected and also protects the electrical contacts.

[0149] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0150] Example 1 - Preparation of Component A and Component B

[0151] The raw materials listed in Table 1 were weighed into a high-speed blender and premixed at 2000 rpm for 30 seconds to form a uniform composition. The composition was then degassed in a vacuum high-speed blender at 900 rpm for 3 minutes. All of the above compositions were prepared as described above.

[0152] As shown in Table 1, the compositions F1 to F4 differ only in the type of filler used. Compositions F1 and F2 contain the same filler at the same content, but V2 also includes fumed silica, a synthetic colloidal material with defined properties and particle size, as a filler. It consists entirely of amorphous silica particles (SiO2) aggregated into larger units. Compositions F3 and F4, on the other hand, contain different contents of the same filler.

[0153] Table 1 - Component A

[0154]

[0155] Table 2 - Component B

[0156] The raw materials listed in Table 2 were weighed into a high-speed blender and premixed at 2000 rpm for 30 seconds to form a uniform composition. The composition was then degassed in a vacuum high-speed blender at 900 rpm for 3 minutes. All of the above compositions were prepared as described above.

[0157]

[0158] The mixing ratio of components A and B is 10:1 (by volume). Component B is the so-called booster component, which has two functions:

[0159] On the one hand, it ensures uniform moisture incorporation into component A, allowing it to cure evenly. Without component B, component A would cure from the outside inwards upon contact with the outside air. Since the diffusion paths within the module are very long in typical large-area coating applications, and component A has very little contact with the surrounding air, parts of the component can remain uncured for a long time between the injectable heat contact material and the filler material applied over the large area.

[0160] -On the other hand, the addition of catalysts can accelerate the polycondensation reaction of silane functional groups.

[0161] Experiment 1 - Investigation of Sedimentation Behavior, Viscosity and Extrudability

[0162] The settling behavior is determined solely based on the formulation of Part A, since settling problems are more severe in Part A, which is the reactive component. Therefore, Part B is not shown here. It is non-reactive and contains the water and catalyst required to accelerate the curing of the contact and filling materials of the present invention.

[0163] The viscosities of compositions F1 to F4 were measured immediately after preparation of component A (100 g or 500 g batches). The results are summarized in column 1 of Table 2:

[0164] Table 2:

[0165]

[0166] As shown, compositions F1 and F3 differ in the use of ZnO (see Table 1), but have almost identical viscosities measured immediately after preparation.

[0167] Compositions F1 to F4 were then transferred to cartridges and stored upright at 60°C for one week. This process simulated aging and sedimentation processes during storage and transportation. After one week at 60°C, the sedimentation behavior of compositions F1 to F4 was determined by measuring the viscosity and density of each composition in the cartridge. To this end, the cartridge was divided into five volume sections, and the corresponding samples were extracted. It is important to note that "Sample 1" was sampled directly from the top of the cartridge, "Sample 3" was sampled from the middle volume section, and "Sample 5" was sampled from the bottom of the cartridge. Samples 2 and 4 represent intermediate measurements within the volume range above and below the center of the respective cartridges.

[0168] The viscosity of the extracted samples was measured on a plate-plate rheometer at a shear rate of 10 s⁻¹. Due to the very high viscosity of the composition, the density was measured in a small plastic cup of approximately 2 ml. Before measuring the density, the cup volume was determined by completely filling it with water and reweighing it. After the cup was allowed to dry, it was filled with the corresponding component without bubbles, and the excess material was removed flush with the cup rim. The filled cup was reweighed, and the density was calculated based on the mass of the component and the exact volume of the cup. The performance of the extrusion cartridge was also evaluated by squeezing the cartridge, and the impression was recorded.

[0169] As shown in Table 2, the viscosity evolution of composition V1 is comparable to that of reference formulations F2 through F4. All formulations exhibited sedimentation, with the viscosity of the lower volume increasing by 20-30% compared to the upper volume. This corresponds to a more subtle increase in density in the lower portion of the cartridge. In formulation F4, the more severe sedimentation made accurate measurement impossible in the lower region, as it was impossible to transfer the sample to the measuring cup without air bubbles.

[0170] However, a significant difference in extrusion properties was observed between composition V1 and compositions V3 and V4 (the latter two without ZnO addition). This clearly shows that the injection properties of composition V1 are significantly improved, which is attributed to the addition of ZnO.

[0171] In direct comparison, compositions V3 and V4 were too viscous to be transported. Even in composition V2 (composition 1 with 1.5% fumed silica added to increase viscosity), extrusion performance was significantly improved over the comparative compositions V3 and V4.

[0172] Experiment 2 - Study of injection performance

[0173] In this experiment, composition V1, which has the best extrusion properties, was compared with composition F3, which does not contain ZnO.

[0174] A plexiglass cover was installed on the metal model for injection testing. The movement of the injection front was recorded by video and the injection time was determined. The gap width was 1 mm, the injection volume was approximately 85 ml, and the injection cavity dimensions were 450 mm x 195 mm x 1 mm.

[0175] The plexiglass cover is sealed at the edges with a sealing strip. The plexiglass plate has a hole for injection and a groove for a sealing rubber to evacuate air and excess injection material from the opposite side of the injection volume after the test. The plexiglass plate is divided into uniform injection areas of 1 / 3, 2 / 3 and the entire injection length with two pieces of tape to enable repeated recording of intermediate injection times.

[0176] First, compositions V1 and V3 containing only component A were prepared as shown in Table 1. These were then injected into cartridges with component B at a ratio of 10:1 without air bubbles and fitted with a static mixer (10-24T-MFHX). Compositions V1 + component B and V3 were injected into a plexiglass plate with component B through a hole using a pneumatic cartridge gun. The pneumatic pressure was set to a maximum of 6 bar. Ambient and material temperatures were laboratory temperature (approximately 23°C).

[0177] The results are summarized in Table 3:

[0178] Table 3:

[0179]

[0180] After an injection time of 3:00, the injection of composition V3 + component B was stopped. Due to its extremely high viscosity and poor fluidity, complete injection was not possible using a cartridge gun, as the maximum air pressure required for injection was insufficient and there was a risk of cracking the plexiglass sheet due to pressure buildup. In contrast, the injectable thermal contact and filler material of the present invention (V1 + component B) could be injected very quickly and easily.

Claims

1. An injectable thermal contact and filling material, consisting of component A and component B, wherein: Component A includes: 1.A) Silylated prepolymers or mixtures of silylated prepolymers, wherein the silylated prepolymers are based on polyurethanes, polyols / diols or polyacrylates; 2. A) a plasticizer which is a polyfunctional carboxylic acid ester; 3.A) Wetting and dispersing additives having at least one amine value of >20 mg KOH / g, determined according to DIN 19645; 4.A) a mixture of functionalized organosilanes; 5. A) a mixture of ZnO and another thermally conductive filler or multiple thermally conductive fillers; and wherein Component B includes: 1.B) a plasticizer which is a polyfunctional carboxylic acid ester; 2.B) wetting and dispersing additives having at least one amine value of >20 mg KOH / g, determined according to DIN 19645; 3.B) a thermally conductive filler or a mixture of multiple thermally conductive fillers; 4.B) Water; and 5.B) an organometallic catalyst; and wherein The volume mixing ratio of component A to component B is 1:1 to 10:

1.

2. The injectable thermal contact and filling material according to claim 1, wherein Component A comprises exclusively silylated prepolymers based on polyurethane.

3. The injectable thermal contact and filling material according to claim 1 or 2, characterized in that The plasticizer is a difunctional carboxylic acid ester.

4. The injectable thermal contact and filler material according to claim 3, wherein The plasticizer is a difunctional carboxylic acid ester based on polyether alcohol.

5. The injectable thermal contact and filling material according to any one of claims 1 to 4, characterized in that The mixture of functionalized organosilanes comprises at least an amino-functional, vinyl-functional, or epoxy-functional organosilane.

6. The injectable thermal contact and filling material according to any one of claims 1 to 4, characterized in that The mixture of functionalized organosilanes includes at least two organosilanes selected from the group consisting of amino-functionalized organosilanes, vinyl-functionalized organosilanes, and epoxy-functionalized organosilanes.

7. The injectable contact and filling material according to any one of claims 1 to 6, characterized in that At least one functional organosilane is an oligomeric silane.

8. The injectable contact and filling material according to any one of claims 1 to 7, characterized in that The thermally conductive filler is selected from the group consisting of Al(OH)3 and Al2O3.

9. The injectable thermal contact and filling material according to any one of claims 1 to 8, characterized in that The mixture of thermally conductive fillers includes Al(OH)3 and Al2O3.

10. The injectable thermal contact and filling material according to any one of claims 1 to 9, characterized in that At least one thermally conductive filler has a surface coating and / or surface functionalization.

11. The injectable thermal contact and filling material according to any one of claims 1 to 10, characterized in that The total filler content of components A and B is 80 to 95% by weight, wherein the ZnO content of the filler mixture is 10 to 30% by weight.

12. The injectable thermal contact and filling material according to any one of claims 1 to 11, characterized in that The total filler content of components A and B is 88 to 93% by weight, wherein the ZnO content of the filler mixture is 15 to 25% by weight.

13. The injectable thermal contact and filling material according to any one of claims 1 to 12, characterized in that It includes: 1 to 10% by weight of a silylated prepolymer mixture, wherein the silylated prepolymer is based on polyurethane and the content does not exceed 50% by weight, 3 to 15% by weight of plasticizer, 0.2 to 2% by weight of wetting and dispersing additives, 0.5 to 5 wt% of an organosilane, and A mixture of 80 to 95 wt. % ZnO and another thermally conductive filler or a plurality of thermally conductive fillers, wherein the content of ZnO in the filler mixture is 10-30 wt. %.

14. The injectable thermal contact and filling material according to any one of claims 1 to 13, characterized in that It includes: 1 to 7% by weight of a silylated prepolymer mixture, wherein the silylated prepolymer is based on polyurethane and the content does not exceed 50% by weight, 3 to 8% by weight of plasticizer, 0.5 to 1.5% by weight of wetting and dispersing additives, 0.5 to 1.5 wt% of an organosilane, and A mixture of 83 to 93 wt. % ZnO and another thermally conductive filler or a plurality of thermally conductive fillers, wherein the content of ZnO in the filler mixture is 15-25 wt. %.

15. The injectable thermal contact and filling material according to any one of claims 1 to 14, characterized in that It does not contain silicone.

16. Use of the injectable thermal contact and filling material according to any one of claims 1 to 15 in large area electronic components.

17. Use of the injectable thermal contact and filling material according to any one of claims 1 to 15 in a battery system having a complex battery structure.

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