High-temperature-resistant contact and filling material and application thereof

Abstract

The invention relates to a high-temperature-resistant contact and filling material. The high-temperature-resistant contact and filling material consists of a component A and a component B, component A comprises: a polyacrylate based silylated prepolymer or a silylated prepolymer mixture comprising at least one polyacrylate based silylated prepolymer; a plasticizer which is a multifunctional carboxylic acid ester; having at least one greater than gt as determined according to DIN 19645; a wetting and dispersing additive having an amine value of 20 mg KOH / g; 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; and an antioxidant or a mixture of a plurality of antioxidants. The volume mixing ratio of the component A to the component B is (1: 1)-(10: 1).

Description

[0001] Heat is generated during the operation of electronic and energy technology systems. This heat must be dissipated quickly and efficiently from the heat-generating units. For example, electric vehicles, due to the use of solid-state battery cells, run at very high temperatures.

[0002] Solid-state or solid-state batteries are a new development in battery technology. Unlike the lithium-ion and lithium-polymer batteries currently on the market, they use solid electrolytes instead of liquid electrolytes. The biggest advantage of this new technological development is the higher potential charge density that can be achieved with such batteries. This high charge density is partially offset by the current relatively low power density, which is due to the low charge density of typical solid electrolytes (such as glass-ceramic electrolytes). Other important technical advantages of solid-state batteries are their extremely low flammability and their greater stability at extreme external temperatures. This simplifies the complex thermal management of the batteries, especially the cooling system, by simply using switchable heating devices in combination with passive heat dissipation. Since batteries can operate at higher temperatures without short circuits, cell damage, and difficult-to-extinguish battery fires, higher temperature resistance requirements are placed on the thermal conductivity solutions used.

[0003] In this field, thermally conductive contacts and filler materials are often used to dissipate and supply heat. They transfer heat and connect active components together.

[0004] Contact and filling materials based on silanized prepolymers are known in the literature for use in thermal management (WO 2020 / 165288A1, US 2015 / 166859, DE 2018 102 989B4). However, due to the increasing operating temperatures of electric vehicles, conventional contact and filling materials based on silanized prepolymers are unsuitable for this application due to their thermal instability. They decompose over time and are therefore unable to maintain the required functionality throughout the entire service life of the electric vehicle.

[0005] Therefore, silicone-based contact and filler materials are used in applications with very high operating temperatures. Silicone-based solutions offer excellent temperature resistance, but are not universally accepted due to their negative impact on electronic circuits and connectors. Silicone-based oils are known to contain small amounts of volatile silicon compounds, which can be released into the surrounding air. These volatile silicon compounds can deposit on surfaces surrounding active components. Subsequent painting or bonding processes on these contaminated surfaces can cause the paint or bonding layer to lose adhesion. If volatile silicon compounds enter electrical contacts, they can decompose due to sparks, forming an insulating oxide layer that can impair or destroy contact functionality.

[0006] Due to the increasing demand for high-temperature-resistant contact and filling materials which do not have the above-mentioned disadvantages, the object of the present invention is to provide a high-temperature-resistant contact and filling material which has the desired properties and can be used at very high operating temperatures while being able to withstand high heat conduction and having a viscosity suitable for this application.

[0007] Surprisingly, the object of the present invention is achieved by a high-temperature-resistant 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 contact and filling material according to the invention can be gathered from the following description and the examples.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] In the present invention, " antioxidant " refers to the chemical compound that slows down or completely stops the oxidation of other substances. They are usually used as free radical scavengers to inactivate the degradation process caused by free radicals, thereby preventing the oxidative degradation of contained organic compounds. In the field of adhesives, they are added to the formula to improve the stability of cured polymers under severe conditions of use. For example, in the presence of air oxygen, high temperature can cause free radical degradation chain reaction. This type of free radical degradation chain reaction is usually interrupted or significantly slowed down by antioxidants, wherein, the antioxidant contained (such as sterically hindered phenolic group) forms a very weak stable free radical of reactivity, thereby preventing free radicals from being further transferred to other polymer groups, which are commonly referred to as primary antioxidants. Other types of antioxidants, for example, can also be reducing agents, which are oxidized earlier than the protected substance, and can also be used in combination. So-called secondary antioxidants can also be added, for example, including destroying peroxides to protect polymer chains from phosphide compounds or thioester antioxidants or amine systems that attack oxidative attacks.

[0014] In the present invention, "organosilane" refers to a chemical compound having a silicon group, at least one organic residue and one to three hydrolysable substituents or hydroxyl groups. The hydrolysable groups are for example alkoxy groups. They can be oligoethylene glycol chains or acetoxy functional groups. The reactive silane group is an alkoxysilane group which is fully or partially hydrolysed, which subsequently forms a silanol group. There are many different types of such organosilanes, which mainly differ in the structure of the organic residue and are described by their chemical structure. For example, hydroxylsilanes, isocyanate silanes, aminosilanes, thiosilanes, vinylsilanes all have an organic chain between the silicon group and at least one other functional group. Of course, there are also organosilanes with multiple functionalities, for example aminosilanes containing secondary and primary amino groups, or organoalkoxysilanes with at least one hydroxyl (OH), isocyanate, amino or vinyl group in the organic part.

[0015] Depending on the contained functional groups, organosilanes can be classified into the following groups:

[0016] - without further functional groups (organic chain), for example octyltrimethoxysilane, OCTMO;

[0017] - primary amine functionality, for example 3-aminopropyltrimethoxysilane, AMMO;

[0018] - secondary amine functionality, for example N-(n-butyl)-3-aminopropyltrimethoxysilane;

[0019] - diamino functionality, for example N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, DAMO;

[0020] - epoxy functionality, for example 3-glycidoxypropyltrimethoxysilane, GLYMO;

[0021] - thio functionality, for example 3-mercaptopropyltrimethoxysilane, MTMO;

[0022] - methacrylic functionality, for example 3-methacryloyloxypropyltrimethoxysilane, MEMO;

[0023] - vinyl functionality, for example vinyltrimethoxysilane, VTMO.

[0024] The chemically and commercially available compounds mentioned in each of the above groups are only used as examples, the groups are not limited to these compounds.

[0025] In the present invention, "thermally conductive filler" refers to a chemical compound which is added to a formulation to ensure filling and at the same time has thermal conductivity. Typical thermally conductive fillers are:

[0026] - metals, but due to their electrical conductivity, they are not suitable for many applications;

[0027] - aluminium oxide / aluminium hydroxide; and

[0028] -magnesium oxide / magnesium hydroxide; and

[0029] Diamond, carbon nanotubes, aluminum nitride (AlN), boron nitride (BN), graphite.

[0030] 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.

[0031] The high temperature resistant contact and filling material of the present invention comprises component A and component B, wherein:

[0032] Component A includes:

[0033] 1.A) a silylated prepolymer based on polyacrylate or a silylated prepolymer mixture comprising at least one silylated prepolymer based on polyacrylate;

[0034] 2. A) a plasticizer which is a polyfunctional carboxylic acid ester;

[0035] 3.A) Wetting and dispersing additives having at least one amine value of >20 mg KOH / g, determined according to DIN 19645;

[0036] 4.A) a mixture of functionalized organosilanes;

[0037] 5. A) a mixture of ZnO and another thermally conductive filler or multiple thermally conductive fillers; and

[0038] Component B includes:

[0039] 1.B) a plasticizer which is a polyfunctional carboxylic acid ester;

[0040] 2.B) wetting and dispersing additives having at least one amine value of >20 mg KOH / g, determined according to DIN 19645;

[0041] 3.B) a thermally conductive filler or a mixture of multiple thermally conductive fillers;

[0042] 4.B) Water;

[0043] 5.B) Organometallic catalysts;

[0044] 6.B) an antioxidant or a mixture of antioxidants; and wherein

[0045] The volume mixing ratio of component A to component B is 1:1 to 10:1.

[0046] Surprisingly, the contact and filling material according to the application exhibits a very high heat resistance. Surprisingly, it was found that using a combination of a selected silane-modified prepolymer and an antioxidant, the temperature resistance of the technology can be significantly improved, making it suitable for high-temperature applications and worth recommending. Also surprisingly, the contact and filling material according to the application also achieves a suitable viscosity. The polyacrylate-based silanized prepolymer of component A has a very high viscosity on its own, so it was feared that the desired viscosity could not be achieved. Surprisingly, the contact and filling material according to the application exhibits the desired properties, namely very good temperature resistance (usable at very high working temperatures), very good thermal conductivity and a viscosity suitable for the application.

[0047] A preferred improvement of the high-temperature-resistant contact and filling material is that the mixture of silanized prepolymers also includes at least one polyurethane- and / or polyol / diol-based silanized prepolymer.

[0048] The general name of the silanized prepolymers referred to in the present application includes compounds of the following formula:

[0049]

[0050] In the above formula, A denotes the backbone (main chain) of the polymer or prepolymer, which as a basis can be

[0051] - polyol / diol (e.g. polyether polyol / diol, polypropylene glycol)

[0052] - having a trans-polyacrylate or

[0053] - can even be a prepolymer based on a different technology, e.g. a polyurethane-modified prepolymer, which is modified with an alkoxyl-protected silane group in a subsequent reaction step.

[0054] According to the application, the substituents R 1 , R 2 and R 3 may be chemical groups, wherein at least R 1 and R 2 are alkoxy groups and R 3 is an alkoxy group or an alkyl group.

[0055] According to the application, an alkyl group means a C1-C 10 alkyl group. According to the application, C1-C 10 alkyl means a straight-chain or branched saturated hydrocarbon group containing 1 to 10 carbon atoms. This includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2,2-dimethylpropyl, n-hexyl, isohexyl, 2-ethylhexyl, n-heptyl, isohexyl, n-octyl, isooctyl, n-nonyl, n-decyl, etc.

[0056] According to the present application, the alkoxy group means O-C1-C 10 alkyl group. The C1-C 10 The alkyl group is as described above.

[0057] Another preferred modification of the high temperature resistant contact and filling material is that the alkoxy group is selected from the group consisting of OCH3 and OCH2CH3, and the alkyl group is CH3.

[0058] Another particularly preferred modification of the high temperature resistant contact and filling material is that the alkoxy group is OCH3 and the alkyl group is CH3.

[0059] Another preferred modification of the high temperature resistant is that the silanized prepolymer or mixture of silanized prepolymers is selected from the group consisting of:

[0060] - Group A

[0061] This group includes prepolymers based on polyol / glycol backbone, the chemical name of which is as follows: silane-modified polymer (SMP), modified silane polymer, MS polymer, silane-terminated polymer.

[0062] Commercially available prepolymers belonging to this group are, for example:

[0063] Dimethoxysilane MS polymer S (e.g. S303H) and high-strength dimethoxysilane MS polymer SAX (e.g. SAX350).

[0064] The prepolymers most suitable for use in the high temperature resistant contact and filling material are prepolymers of formula A-1 :

[0065]

[0066] - Group B

[0067] This group includes silanized prepolymers with oligomeric polyacrylate backbone.

[0068] Commercially available prepolymers belonging to this group are, for example: Kaneka XMAP SA (e.g. Kaneka XMAP SA100).

[0069] The prepolymers most suitable for use in the high temperature resistant contact and filling material are prepolymers of formula B-1 :

[0070]

[0071] R is H, C1-C6-alkyl; 1 is H, C1-C6-alkyl;

[0072] R is H, C1-C6-alkyl 2 is H, C1-C6-alkyl

[0073] -Group C

[0074] 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.

[0075] The chemical names of these prepolymers are as follows: silane-terminated polyurethane (SPU or STPU), silane-terminated polyurethane, silane-modified polyurethane.

[0076] 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)

[0077] Another preferred improvement of the high temperature resistant contact and filling material is that one or more silanized prepolymers are selected from the following group:

[0078] SAX350, SAX015 (Group A)

[0079] XMAP SA120S (Group B)

[0080] Another preferred improvement of the high-temperature resistant contact and filling materials is that the plasticizer is a multifunctional carboxylic acid ester.

[0081] Another preferred improvement of the high-temperature resistant contact and filling material is that the plasticizer of component A is a trifunctional carboxylic acid ester.

[0082] Another preferred improvement of the high-temperature-resistant contact and filling material is that the plasticizer of component A is a triester of trimethylolpropionic acid.

[0083] Another preferred improvement of the high-temperature-resistant contact and filling material is that the plasticizer of component B includes a trifunctional carboxylic acid ester.

[0084] 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.

[0085] The choice of the respective plasticizer will be made according to its function in the high temperature resistant contact and filling material according to the present invention, but it has to be noted that these plasticizers are not identical to the plasticizers used in other formulations. In the high temperature resistant contact and filling material according to the present invention the plasticizer has the following functions:

[0086] - reduction of the viscosity of the liquid component

[0087] Generally, silicon based functionalized prepolymers are high viscosity raw materials, even if usually low viscosity systems are chosen to formulate the formulation. Nevertheless, the degree of fillability of the thermally conductive filler is directly related to the mixed viscosity of the liquid component. For this reason alone, the use of low viscosity additives is required to reduce the mixed viscosity of the liquid component as low as possible to achieve the required degree of fillability without over increasing the viscosity of the finished formulation to the point that the application is affected.

[0088] - increase of the flexibility of the cured material

[0089] Due to the very high filler content, the polymer network loses its degrees of freedom and the matrix, which is very flexible and has a high elongation at break when not filled, becomes more and more inflexible and the elongation at break usually decreases to very low values. By using a plasticizer, the internal wetting of the filler is improved, because the plasticizer molecules not only attach between the polymer chains as defined above, but ideally also form a layer of compatibility between the filler particles and the polymer chains, thus greatly increasing the degrees of freedom of the polymer chains, which are severely limited by the filler particles.

[0090] Generally, silane based prepolymers have a high molecular weight, mainly due to their long (pre)polymer backbone. This backbone separates the crosslinking sites from each other, thus forming a network with a large mesh and high flexibility, for example suitable for flexible adhesives and / or sealants. As mentioned in the first point, the viscosity of these silane based prepolymers is of great importance for the application, so only low viscosity types can fully meet the application requirements. However, due to the high molecular weight backbone, the viscosity of the prepolymers is also increased, so generally low molecular weight silane based prepolymers are more suitable for the application. Of course, these prepolymers also have a higher crosslinking density, so they have higher mechanical properties and are less flexible, and the effect of the above-mentioned high degree of filling further exacerbates this phenomenon. One tries to compensate for this phenomenon by using a plasticizer, by exploiting the "plasticizer effect" between the cured prepolymer and the filler particles (see second point), while at the same time reducing the volume fraction of the prepolymers used to a minimum. Of course, this can lead to the formation of an incompletely formed polymer network, because not all polymer chains are fully crosslinked. This results in a larger mesh of the polymer network, at least partially offsetting the disadvantages of the low molecular weight silane based prepolymers used, making the network more flexible, with lower modulus and lower mechanical properties, which is the same effect as can be achieved with long chain silane based prepolymers.

[0091] Based on the above description, the following plasticizers have been found to be particularly suitable for use in the high-temperature-resistant contact and filling materials of the present invention:

[0092] Oxsoft 3G8:CAS 94-28-0

[0093] -Triethylene glycol di(2-ethylhexanoate)

[0094] -2,2'-Ethylene glycol diethyl di(2-ethylhexanoate)

[0095] Cereplas L810TM:CAS 90218-76-1

[0096] -1,2,4-Benzenetricarboxylic acid, mixed decyl and octyl triesters

[0097] Oxsoft TOTM LE:CAS 3319-31-1

[0098] -Tris(2-ethylhexyl)benzene-1,2,4-tricarboxylate

[0099] -Trioctyl trihydroxycarboxylate.

[0100] Another preferred improvement of the high temperature resistant contact and filling material is that component A includes an antioxidant or a mixture of multiple antioxidants. Examples of this can be found in the product portfolios of typical antioxidant manufacturers, such as ADK or Adeka Polymer Additives.

[0101] Another preferred development of the high-temperature-resistant contact and filling material is that the wetting and dispersing additive has at least functionalized amine groups, which can optionally contain acidic groups, such as carboxylic esters or phosphorus groups.

[0102] Particularly preferred are: Dispbyk2157 or Byk W969.

[0103] 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.

[0104] 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.

[0105] Another preferred development of the high-temperature-resistant contact and filling material is that component A comprises a mixture of functionalized organosilanes.

[0106] 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.

[0107] 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.

[0108] Another preferred improvement of high temperature resistant contact and filling materials is to use the following organosilane:

[0109] In the formulation, the following organosilanes (including their mode of function) are relevant:

[0110] a) Amino-functional organosilanes

[0111] 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.

[0112] Another particularly preferred development of the high-temperature-resistant contact and filling material is the use of:

[0113] -AMMO or

[0114] - Amine-containing oligomeric pre-shrinked silanes (such as SIVO).

[0115] b) Vinyl-functional organosilanes

[0116] 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).

[0117] Another particularly preferred development of the high-temperature-resistant contact and filling material is the use of VTMO.

[0118] c) Epoxy-functional organosilanes

[0119] 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.

[0120] Another particularly preferred development of the high-temperature-resistant contact and filling material is that the mixture of functionalized organosilanes comprises at least amino-functional, vinyl-functional, or epoxy-functional organosilanes.

[0121] Another particularly preferred improvement of the high-temperature-resistant contact and filling 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.

[0122] Another particularly preferred development of the high-temperature-resistant contact and filling material is that the mixture of functionalized organosilanes comprises at least an amino-functionalized organosilane and a vinyl-functionalized organosilane.

[0123] Another particularly preferred improvement of the high-temperature resistant contact and filling material is that the mixture of functionalized organosilanes includes amino-functionalized organosilanes, vinyl-functionalized organosilanes, and epoxy-functionalized organosilanes.

[0124] Another particularly preferred development of the high-temperature-resistant contact and filling material provides that the at least one functionalized organosilane is an oligomeric silane.

[0125] Another particularly preferred development of the high-temperature-resistant contact and filling material is the use of GLYMO.

[0126] Another particularly preferred development of the high-temperature-resistant contact and filling material consists in using zinc oxide as filler.

[0127] Another preferred development of the high-temperature-resistant contact and filling material is to use, in addition to ZnO, a heat-conducting filler selected from the group consisting of Al(OH) 3 , Al 2 O 3 .

[0128] Another preferred improvement of the high-temperature-resistant contact and filling material is that the total filler content in components A and B is 80 to 95 weight %, preferably 88 to 93 weight %, more preferably 88 to 90 weight %, wherein the ZnO content in the filler mixture is correspondingly 10 to 30 weight %, preferably 15 to 25 weight %, more preferably 15 to 20 weight %.

[0129] Another preferred development of the high-temperature-resistant contact and filling material is that at least one heat-conducting filler has a surface coating and / or surface functionalization, which preferably has hydrophobic properties.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] Another preferred development of the high-temperature-resistant contact and filling material is that component B comprises a catalyst.

[0135] Another particularly preferred improvement to the high-temperature-resistant contact and filler materials 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).

[0136] Another particularly preferred development of the high-temperature-resistant 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 usually used in the formulation in the form of amino-functionalized organosilanes and are summarized in the description of organosilanes.

[0137] Another particularly preferred improvement of the high-temperature resistant contact and filling materials is that the catalyst is an acid catalytic system.

[0138] Another particularly preferred development of the high-temperature-resistant contact and filling material is that it is free of silicon.

[0139] 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.

[0140] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0141] Example 1 - Preparation of Component A and Component B

[0142] 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.

[0143] As shown in Table 1, formulations F1 to F4 each lack one component compared to reference formulation F. Only one polymer (XMAP or SMP) was used in formulations F1 and F2. ZnO was missing from formulation F3, and an antioxidant was missing from formulation F4.

[0144] Table 1 - Component A

[0145]

[0146] 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.

[0147] Table 2 - Component B

[0148]

[0149] 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:

[0150] On the one hand, it allows moisture to enter component A evenly, allowing it to cure uniformly. Without component B, component A would cure from the outside inward after coming into contact with the outside air. Because the diffusion paths within the module are very long in typical large-area coating applications, and the contact area of ​​component A with the surrounding air is very small, some components can remain uncured for a long time between the heat-resistant contact and filler materials of the large-area coating.

[0151] -On the other hand, the addition of catalysts can accelerate the polycondensation reaction of silane functional groups.

[0152] Experiment 1 - Studying Temperature Stability by TGA Measurement

[0153] A small amount of material cured at room temperature for 7 days was heated in a crucible at a heating rate of 10 K / min, and the mass loss of the sample at different temperatures was measured.

[0154] The respective mass losses were measured at 280°C, 340°C and 370°C.

[0155] Table 3

[0156]

[0157] As shown in Table 3, Formulation R outperforms Formulations F2 and F4. However, Formulation F1 has better thermal properties than the reference formulation, so it is preferred due to its thermal properties. However, due to the very high viscosity of XMAP, this formulation is no longer suitable for practical applications because the viscosity of the formulated components is too high and there is no comparable low-viscosity prepolymer available on the market.

[0158] Formulation F3 also slightly outperformed the reference formulation at temperatures of 280°C and 370°C. However, due to poor application and settling properties, this formulation was also not suitable. As mentioned above, zinc oxide has no significant effect on temperature stability, but has a significant impact on application and settling properties.

[0159] In summary, the reference formulation R performed the best on average and is therefore suitable for the application.

[0160] Experiment 2 - Study of Mechanical Properties

[0161] In another experiment, the mechanical properties of the aforementioned formulation were investigated after curing for 7 days at room temperature and aging for several days at 150°C. Tensile strength test pieces were produced, cured, and measured according to DIN EN ISO 527, with the corresponding tensile strength and elongation at break recorded.

[0162] The measurements after room temperature curing were then compared with those after aging at 150 °C for 7 days, and the relative mechanical properties were calculated with respect to the initial values.

[0163] Table 4

[0164]

[0165] Formulation F1 exhibited the best heat aging properties and had the best tensile strength and elongation at break after heat aging. However, as mentioned above, this formulation could not be used in the field due to its high viscosity.

[0166] Formulation F2 performed well in terms of viscosity, but exhibited severe embrittlement and decomposition during temperature aging, making it unsuitable for this application.

[0167] Aging of Formulation F3 shows that the use of antioxidants is essential. Without antioxidants, severe embrittlement and a decrease in elongation at break occur, which is also very important for the application.

[0168] In agreement with the TGA test results, the use of zinc oxide has no effect on the aging behavior, but in order to improve the formulation application and sedimentation properties of the marketed product, zinc oxide must be added.

Claims

1. A high temperature resistant contact and filling material, consisting of component A and component B, wherein: Component A includes: 1.A) a silylated prepolymer based on polyacrylate or a silylated prepolymer mixture comprising at least one silylated prepolymer based on polyacrylate; 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 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; 5.B) Organometallic catalysts; 6.B) an antioxidant or a mixture of antioxidants; and wherein The volume mixing ratio of component A to component B is 1:1 to 10:

1.

2. The high temperature resistant contact and filling material according to claim 1, characterized in that The mixture of silylated prepolymers also includes at least one silylated prepolymer based on polyurethane and / or polyol / diol.

3. The high temperature resistant contact and filling material according to claim 1 or 2, characterized in that: The plasticizer of component A is a trifunctional carboxylic acid ester.

4. The high-temperature resistant contact and filling material according to any one of claims 1 to 3, characterized in that Component A includes an antioxidant or a mixture of antioxidants.

5. The high-temperature resistant 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 high-temperature-resistant 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 high-temperature resistant 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 high-temperature-resistant 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 high-temperature-resistant contact and filling material according to any one of claims 1 to 10, characterized in that The total filler content in component A and component B is 80 to 95% by weight, wherein the ZnO content in the filler mixture is 10 to 30% by weight.

12. The high-temperature-resistant contact and filling material according to any one of claims 1 to 11, characterized in that The total filler content in component A and component B is 80 to 93% by weight, wherein the ZnO content in the filler mixture is 15 to 25% by weight.

13. The high-temperature-resistant contact and filling material according to any one of claims 1 to 12, characterized in that It includes: 3 to 10% by weight of a silylated prepolymer mixture, wherein the silylated prepolymer is based on polyacrylate and the content does not exceed 50% by weight, 0.5 to 5% by weight of an antioxidant, 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 78 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 10-30 wt. %.

14. The high-temperature-resistant contact and filling material according to any one of claims 1 to 13, characterized in that It includes: 5 to 9% by weight of a silylated prepolymer mixture, wherein the silylated prepolymer is based on polyacrylate and the content does not exceed 50% by weight, 0.5 to 1.5% by weight of an antioxidant, 3 to 5% 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 80 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 high-temperature-resistant 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 high-temperature-resistant contact and filling material according to claim 1 in electronic components subject to high thermal stress.

17. Use of the high-temperature-resistant contact and filling material according to any one of claims 1 to 15 in a battery system having a complex battery structure.

Images