Hybrid elastomeric material

Abstract

The present invention proposes an elastomeric material, which is particularly suitable as a sealing raw material between the fuel cells of a fuel cell stack and the stack itself, wherein the hybrid elastomeric material comprises a hybrid elastomer having a share of a siloxane polymeric material and a share of a polyolefin elastomeric material, wherein both materials are addition-crosslinked to each other. Other aspects relate to a polyelectrolyte fuel cell comprising a sealing element made of the hybrid elastomeric material according to the invention, and the use of the hybrid elastomeric material according to the invention in a screen printing process.

Description

TECHNICAL FIELD

[0001] The present invention relates to a hybrid elastomeric material, which is used in particular as a sealing material in fuel cells, for drinking water pipelines and as a biocompatible material for medical applications, in particular for implants. BACKGROUND

[0002] The use of elastomeric sealing materials is manifold and is often exposed to conditions which require a high long-term chemical resistance in acidic, neutral or alkaline aqueous media and at the same time a mechanical compression, as well as under temperature loads of up to about 120°C.

[0003] The conditions to which the elastomeric material is exposed in fuel cells, in particular solid polymer fuel cells, first require a high resistance to extraction, in order to avoid contamination from the sealing material and not to negatively influence the function of the electrochemical processes in the fuel cell. Therefore, during the material production, in particular during the crosslinking process, the reaction by-products are to be reduced as far as possible.

[0004] Furthermore, in the elastomeric material for fuel cells, a barrier function against gas permeation is required, but this can be significantly supported by constructive measures (degree of compression, sealing profile design).

[0005] Standard liquid silicones, so-called LSR (= liquid silicone rubber), can be addition-crosslinked with the aid of transition metal complexes and have a limited chemical resistance in aqueous media in the compressed state as sealing material. However, they tend to undergo a back-reaction and a cleavage reaction (hydrolysis), including depolymerization. This is particularly true in the case of compressed sealing materials, in which tensile stress, compressive stress and shear stress also have an effect on the material.

[0006] Furthermore, the tendency of gas permeation in LSR materials is very high, i.e. the barrier function of pure LSR materials is worse than that of organic polyolefin rubbers. This should be emphasized in particular for butyl rubber, isobutylene-isoprene rubber (IIR), chlorobutyl rubber (CIIR) and brominated butyl rubber (BIIR).

[0007] The advantage of liquid silicones is the resistance to oxidation and hot air. However, these advantages are secondary for use in fuel cells of the solid polymer type (proton exchange membrane fuel cell (PEM-FC)), since the above-mentioned disadvantages in the relevant aqueous media with additives essentially determine the service life.

[0008] On the other hand, in polyolefin elastomeric materials, the long-term resistance to hot air is limited due to its unsaturation, i.e. to a maximum temperature of about 120°C.

[0009] These and other relevant aspects are discussed in detail in the scientific publication "Alken-Hydrosilylierung bei VBN-EPDM-Elastomeren" by R. Hornig, GAK Gummi Faser Kunststoffe Vol. 70, 9 / 2017, pages 584-597. SUMMARY

[0010] It is the object of the present invention to propose an elastomeric material which is particularly suitable as a sealing stock between the fuel cells of a fuel cell stack and the stack itself, which has an improved hydrolysis resistance for this purpose, and which, in addition to a low long-term compression set and a stable sealing force performance in aqueous media, has a sufficiently high breaking strength and elongation at break. Furthermore, the resistance to extraction against fuel cell-related aqueous media must be high, and there must be a sufficient barrier function against gas permeation.

[0011] According to the invention, the above object is achieved by a hybrid elastomeric material having the features of claim 1.

[0012] The hybrid elastomer of the hybrid elastomeric material according to the invention has an inorganic siloxane skeleton which has been modified by addition-crosslinking with elastomeric polyolefin units. The polyolefin units act as protective groups for the siloxane polymer material against chemical attack.

[0013] The use of the elastomeric polyolefin component provided according to the invention in the hybrid elastomer achieves a better protection of the siloxane skeleton of the siloxane polymer material against hydrolytic attack, thus reducing the cleavage reaction and the reverse reaction, thus reducing the depolymerization tendency, which is otherwise observed in un-protected siloxane polymers or pure liquid silicones (LSR) in a sealingly stressed state in contact with aqueous media, especially at temperatures of about 100°C or more, under neutral conditions but especially also under alkaline and acidic conditions.

[0014] The hybrid elastomeric material according to the invention represents an optimized material, especially in terms of hydrolysis resistance and generally chemical resistance when used as an elastomeric sealing stock at temperatures of about 90°C or more in aqueous-acidic systems and especially in a stressed state, compared to standard liquid silicones (LSR) which are addition-crosslinked.

[0015] In particular in combination, the hybrid elastomeric material according to the invention has the last-mentioned chemical resistance and the required static long-term sealing force performance in the PEM-FC customary thermal environment of about 90°C in aqueous media (up to about 120°C).

[0016] Based on their described advantageous properties, the hybrid elastomer materials according to the application are particularly suitable as sealing stock for drinking water pipelines and as biocompatible materials, in particular implants, for medical applications.

[0017] Here, the hybrid elastomers of the hybrid elastomer materials according to the application can be obtained with similar ultrafast reaction kinetics at the same processing temperatures known hitherto only from pure LSR materials.

[0018] The hybrid elastomers of the hybrid elastomer materials according to the application preferably comprise a siloxane polymeric material having one or more (poly)siloxanes having side groups and / or end groups selected from the group consisting of H, Ci-C 30 alkyl, C2-C 30 alkenyl and aryl. A first polysiloxane having terminal vinyl groups is used as base polymer, while further (poly)siloxanes are selected, if necessary, from the point of view of chain extension and crosslinking of the hybrid elastomer.

[0019] Furthermore, the hybrid elastomers used according to the application are preferably based on polyolefin elastomers having side chains and / or terminal vinyl groups.

[0020] In preferred hybrid elastomers, the siloxane polymeric material comprises one modified poly(dimethylsiloxane) or a plurality of modified poly(dimethylsiloxane)s and / or modified siloxanes. Here, the modification comprises at least vinyl and SiH groups, which can be present in the same or different (poly)dimethylsiloxanes throughout the formulation.

[0021] More preferably, the siloxane polymeric material comprises one or more siloxane polymers of the formula (I)

[0022]

[0023] where the residues R independently of one another are H, CH3, vinyl, phenyl, (CH2) x CH3and / or C3H6O(C2H4O) y (C3H5O) z R'; where

[0024] m = 1 to about 100,

[0025] n = 0 to about 1000,

[0026] x = 1 to about 30,

[0027] y = 0 to about 20,

[0028] z = 0 to about 30,

[0029] and where the sum m + n > 3 and R' is H, CH3or (CH2)x CH3.

[0030] In this case, the chain-extended dimethylsiloxane units preferably determine the arrangement or order of the reactive groups along the backbone of the siloxane polymeric material.

[0031] Further preferably, in the siloxane polymeric material according to the present application, the siloxane polymer of formula (I) is used in combination with a (poly)siloxane of formula (II):

[0032]

[0033] wherein the residues R 1 are each, independently of one another, CH3, vinyl and phenyl, and n 1 have a value in the range of 0 to about 3000, in particular of about 10 to about 1000.

[0034] Generally, in the hybrid elastomer material according to the present application, the addition-crosslinkable siloxane polymeric material and the polyolefin elastomer material are catalytically addition-crosslinkable.

[0035] Preferably, the polyolefin elastomer material and the siloxane polymeric material of the hybrid elastomer material are addition-crosslinked using a siloxane crosslinker.

[0036] The preferred siloxane crosslinker is selected from the crosslinkers of formula (III):

[0037]

[0038] wherein the residues R 2 are each, independently of one another, H and CH3, wherein m 2 has a value in the range of 1 to about 100 and n 2 has a value in the range of 0 to about 500. Preferably, n 2 has a value of 10 or more and, independently thereof, m 2 has a value of 5 or more.

[0039] It is further preferred that, in the hybrid elastomer, the siloxanes of formulae (I), (II) and (III) together have a ratio of the share of SiH groups to vinyl groups in the range of about 1 :0.5 to about 1 :4, in particular in the range of about 1 :1.5 to about 1 :2.5. This ratio has an influence on the reaction kinetics of the addition crosslinking.

[0040] Furthermore, preferred are hybrid elastomers, wherein the polyolefin elastomer material is selected from the group consisting of polybutadienes, in particular 1,2-polybutadienes, 1,4-polybutadienes, block copolymers of 1,2-butadiene and 1,4-butadiene polymers, acrylonitrile rubber, hydrogenated acrylonitrile rubber, epoxidized liquid polybutadiene, (poly)norbornenes, each having terminal or pendant vinyl groups (a-position), and styrene-butadiene rubber and mixtures of these polyolefin elastomers.

[0041] More preferred hybrid elastomers have a polyolefin elastomer fraction with functional groups as shielding groups, in particular selected from the group consisting of linear and branched C2-C8-alkyl and C2-C8-alkenyl groups.

[0042] These polyolefin elastomer materials preferably have a monomer content with shielding groups, which is preferably in the range of 15 mol% to about 92 mol%. Examples thereof are 1,2-polybutadiene with a monomer content of shielding groups of 15 mol% available as Nisso B-3008 and 1,2-polybutadiene with a monomer content of shielding groups of 92 mol% available as Nisso B-3000, both from Nippon Soda Co., Ltd., Japan. Corresponding hydrogenated polybutadienes are also suitable polyolefin elastomer materials, which are for example available from Nippon Soda Co., Ltd., Japan under the product names Nisso BI-3000 and Nisso BI-3015.

[0043] Alternatively, polybutadienes with hydroxyl end groups are also available as polyolefin elastomer materials, for example provided by Total Petrochemicals & Refining USA, Inc. under the brand CRAY VALLEY under the product names Poly bd R-20LM (molecular weight about 1200 g / mol) and Poly bd R-45HTLO (molecular weight about 2800 g / mol).

[0044] Furthermore, polybutadienes, in which the 1,4-polybutadiene fraction is dominant, in particular in liquid form, and block copolymers based on 1,2-polybutadiene and 1,4-polybutadiene are preferred polyolefin elastomers. 1,4-polybutadienes of this type are for example available from Kuraray Co., Ltd., Japan under the product names LBR-302, LBR-307 and LBR-305. Block copolymers based on 1,2-polybutadiene and 1,4-polybutadiene are available from Kuraray Co., Ltd., Japan under the product names LBR-352 and LBR-361.

[0045] The silicone polymer material preferably has a total mass fraction of about 70 to about 99 wt.-% in the polymer fraction of the hybrid elastomer material according to the application. The corresponding fraction of the polyolefin elastomer material, in particular of the 1,2-polybutadiene, in the polymer fraction of the hybrid elastomer material according to the application is preferably about 28 to about 1 wt.-%, more preferably about 10 to about 1 wt.-%.

[0046] The hybrid elastomer material according to the application also preferably comprises additives, in particular hydrophobic and / or hydrophilic fillers, selected from the group consisting of silicic acid, silicone and titanate. These fillers act as acid scavengers and serve to increase the mechanical strength values. The fraction of the additives in the total mass of the hybrid elastomer material according to the application is preferably about 5 to about 50 wt.-%, more preferably about 15 to about 30 wt.-%. The fillers for foaming are preferably used in a fraction of about 0.5 to about 4 wt.-% of the total formulation, more preferably in a fraction of about 0.2 to about 2 wt.-%.

[0047] A particularly preferred additive is hydrophobic and / or hydrophilic silicic acid, which constitutes a reinforcing filler due to its high specific surface area. In this sense, the silicic acids listed in Table 1A below are particularly suitable as fillers. The BET values given in Table 1A represent the specific surface area, the carbon content is an indicator of the degree of hydrophobization of the otherwise hydrophilic silicic acid particles. The AEROSIL products are available from Evonik Industries AG.

[0048] Table 1A

[0049]

[0050]

[0051] In general, solid particles are suitable as additives for improving the gas permeation resistance of the hybrid elastomer material according to the application used as a sealant.

[0052] In particular applications, in particular in the case of coatings having a pore structure or foam structure (as explained in more detail below), fillers made of expandable or expanded glass or ceramic material are also used as additives. Furthermore, also suitable as fillers are polymeric particles based on polyurethane, polyethylene, polypropylene, polyacrylate and polycarbonate. The pore size in these fillers can be, for example, about 1 to about 200 pm, in particular about 1 to about 50 pm. The pore structure / foam structure of the coating can also be produced from polymeric particles which are expandable during the crosslinking of the polymer of the coating.

[0053] Silanol trimethylsilyl-modified silicone resins (SiVance MQOH-7 MQ silanol resin by Milliken Chemical) can be used as silicone resin additives, which preferably have a polymer viscosity of about 6000 mPas and a concentration of, for example, about 20 wt.%. Special resins modified with vinyl and / or SiH groups can also be chemically bonded to the hybrid elastomers used according to the application via crosslinking reactions, which further improve their chemical resistance in aqueous media.

[0054] In addition to silicone resins, so-called silicone polymer plasticizers, such as polydimethylsiloxanes (PDMS) and high-molecular-weight hydroxy-functional polysiloxanes, can also be used to improve protection against chemical attack (cleavage reactions) in aqueous media.

[0055] The proportion of siloxanes of the formulae (I) and (II) in the total mass of the hybrid elastomers used according to the application preferably amounts to about 50 to about 90 wt.%, more preferably about 60 to about 70 wt.%.

[0056] Further preferably, the siloxane polymers of the formula (I) are used in the form of a mixture of two siloxane polymers having different dynamic viscosities, for example about 10,000 mPas (n ~ 850) and 1,000 mPas (n ~ 350), wherein the weight ratio of these polymers is preferably about 1 :2.

[0057] Furthermore, in the preferred siloxane polymer material, siloxane polymers of the formula (I) having terminal SiH groups and thus fulfilling the function of chain extenders are used. The proportion of this siloxane polymer in the siloxane polymer material is preferably about 1 to about 3 wt.%.

[0058] The average molecular weight of the siloxane polymers according to the formulae (I) and (II) is preferably in the range from about 30,000 to about 300,000 g / mol, particularly preferably in the range from about 60,000 to about 120,000 g / mol. The vinyl content can generally be about 0.02 to about 2.0 mmol / g of polymer, preferably about 0.03 to about 0.06 mmol / g of polymer.

[0059] Preferred chemical crosslinkers and chain extenders according to the application are siloxanes and / or polysiloxanes having reactive SiH units along the main chain and / or at the terminus.

[0060] A wide range of preferred crosslinkers or chain extenders have the schematic molecular structure corresponding to the formulae (II) and (III).

[0061] For the crosslinker, a SiH group content of about 0.5 to about 10 mmol / g is preferred, for the chain extender a SiH group content of about 0.5 to about 3 mmol / g is preferred.

[0062] Exemplary crosslinkers of formula (III) are listed in Table 1 B below.

[0063] Table 1 B

[0064]

[0065] For the production of the hybrid elastomer used according to the application, the use of platinum-based silicophilic catalyst complexes is preferred, for example catalyst systems according to Ossko, Osborn-Fisher, Ashby, Markó, but particularly preferred is the Karstedt catalyst.

[0066] Other transition metal complexes can also be based on other central atoms of the platinum group, namely Rh, Ru, Ir, Os, Pd. Listed here are the ruthenium complexes according to patent EP 2 004 663 B1 (Wacker AG) and the ruthenium-sulfoxide complexes according to patent EP 2 285 814 B1 (Wacker AG). The ligands should have silicophilic properties. In addition, mention is made of lanthanide transition metal complexes, which do not follow the Chalk-Harrod mechanism. The concentration of the catalyst can be in a broad range of about 5 to about 1000 ppm, preferably about 40 to about 80 ppm.

[0067] As already mentioned, the addition of organic protective groups serves to optimize the chemical resistance of the hybrid elastomer to cleavage reactions and back reactions in aqueous media. The organic protective groups or shielding groups are chemically bonded to the polysiloxane skeleton by means of a hydrosilylation reaction, i.e. an addition crosslinking. This grafting of, for example, 1,2-polybutadiene takes place by means of the reaction of the side chains and / or terminal vinyl groups of the polyolefin elastomer with the SiH groups on the polysiloxane skeleton.

[0068] This process consumes SiH groups that are no longer available for the actual chemical crosslinking process when the hybrid elastomer material is crosslinked. The grafting reaction also takes place in parallel with the actual crosslinking process.

[0069] The hybrid elastomer used according to the application thus reduces the reactivity with increasing degree of grafting, for example with 1,2-polybutadiene. In comparison with standard LSR types, significantly higher concentrations of crosslinker and platinum catalyst are recommended here. A platinum catalyst fraction corresponding to a platinum content of about 40 to about 100 ppm should be preferred.

[0070] In standard LSRs, 1-ethynyl-1-cyclohexanol (ECH) is used, for example, in a proportion based on the total mass in the range from 0 to about 600 ppm. In the case of the hybrid elastomers used according to the application, an ECH content of 0 ppm is generally preferred, since the reaction kinetics has already been reduced by the grafting reaction. Whether a reaction inhibitor such as ECH is required, however, also depends on the processing technology, for example the design of the flow channel, the latency in the case of elastomer injection molding by means of cold channel technology, etc. If necessary, the reaction kinetics and the technical properties of the hybrid elastomer can be influenced significantly by varying the concentration of the reaction inhibitor.

[0071] In addition to acetylenic alcohols (ECH, 3-methyl-1-octyn-3-ol (TMDO), etc.), maleic acid alkyl esters (dimethyl maleate (DMM), dibutyl maleate (DBM), etc.), silyl acetylenic alcohols, low-molecular-weight silicone oils (divinyltetramethyldisiloxane (DVDS), 1,3,5,7-tetra-vinyltetramethyltetrasiloxane (ViD4), etc.), and fumaric acid alkyl esters (diallyl fumarate (DAF), dimethyl fumarate (DMF), etc.) and organic hydroperoxides can also be used as reaction inhibitors. Furthermore, organic sulfoxides, amines, diamines, amides (for example 5,5-dimethylhydantoin (DMH)), phosphines, phosphites, nitriles, triazoles, oximes, diaziridines, trialkyl cyanurate and trimethylolpropane trimethacrylate (TMPTMA) are suitable for this purpose.

[0072] In the hybrid elastomers used according to the application, 1,2-polybutadienes are preferably used as polyolefin protecting groups, in particular of the Nd-BR, Co-BR, Ni-BR, Ti-BR (BR = butadiene rubber) type. Furthermore, it is preferable to use syndiotactic 1,2-polybutadienes, since these have better low-temperature flexibility than the isotactic or atactic isomer forms.

[0073] Particularly preferred are polybutadienes of the formula (IV)

[0074]

[0075] where, depending on the polymer variant, the parameters x, y and z can each independently of one another have a value in the range from 0 to about 200, and where the sum x+y+z is in the range from about 10 to about 500, preferably from about 10 to about 60. Polybutadienes of this type, in which the 1,2-polybutadiene component predominates (hereinafter also referred to simply as 1,2-polybutadiene) and the sum x+y+z is about 60, are available, for example, under the trade names Nisso B-3000 and Nisso B-3008 from Nippon Soda Co., Ltd., Japan. For hydrogenated polybutadienes (for example the Nisso BI-3000 and Nisso BI-3015 products), the value of the parameter x is essentially zero. The radicals R1and R2represent, for example, the radicals H or OH.

[0076] Furthermore, as already mentioned, polybutadienes, in particular in liquid form, are also preferred polyolefin elastomers, wherein the 1,4-polybutadiene fraction predominates, and also block copolymers based on 1,2-polybutadiene and 1,4-polybutadiene.

[0077] Another variant of the preferred polyolefin elastomers has a structure according to formula (IVa):

[0078]

[0079] wherein the parameters u, w, x, y and z here each independently of one another have values in the range from 0 to about 200, and the sum of these values u + w + x + y + z is preferably from about 30 to about 1000.

[0080] The styrene-butadiene copolymers of formula (IVa) are obtainable, for example, under the trade name L-SBR-820 and L-SBR-841 from the Japanese company Kuraray Co. Ltd.

[0081] Furthermore, alkyl-modified polysiloxanes are used to provide olefinic protecting groups, as shown in formula (V).

[0082]

[0083] wherein the parameter x here has a value in the range from 0 to about 500, the parameters y and z each independently of one another have values in the range from 1 to about 100, and wherein the sum x + y + z has a value from 2 to about 700.

[0084] The 1,2-polybutadienes of formula (IV) and the polysiloxanes of formula (V) can also be used in the form of mixtures, wherein the parts by weight of polysiloxane of formula (V) can be up to 100 times the parts by weight of 1,2-polybutadiene. The preferred mixing ratio of the parts by weight of 1,2-polybutadiene of formula (IV) and the parts by weight of polysiloxane of formula (V) is in the range from 1 : 1 to 1 : 5.

[0085] Furthermore, as polyolefin protecting groups - also in combination with one another - liquid acrylonitrile-butadiene rubbers (liquid NBR) with a high proportion of 1,2-vinyl butadiene isomers, epoxidized liquid polybutadienes with a 1,2-vinyl butadiene fraction of more than 70% by weight (Nippon Soda Co. Ltd.), (poly)norbornenes with terminal vinyl groups, such as 5-vinylidene-2-norbornene (VNB), 5-methyl-5-vinylidene-2-norbornene (MeVNB), 5-isopyrrolidine-2-norbornene (IPNB), 5-methylallyl-2-norbornene (MANB), 5-methylene-2-norbornene (MNB) and norbornadiene (NBD) can be used.

[0086] Furthermore, low molecular weight butadiene-styrene rubber (SBR) having a share of 1,2-vinyl butadiene isomers and partially saturated or unsaturated HNBR (hydrogenated NBR) having the remaining share of 1,2-vinyl butadiene is suitable for providing the shielding groups.

[0087] Preferred 1,2-polybutadienes (e.g. NISSO B-3000 and NISSO B-3008 from Nippon Soda Co. Ltd.) have an average molar weight of about 1000 to about 5000 g / mol. Particularly preferred is a 1,2-polybutadiene having a molar weight of about 3000 g / mol. The vinyl content (monomer share) of the preferred 1,2-polybutadienes is in the range of about 15 to about 92 mol%.

[0088] Corresponding hydrogenated polybutadienes are also suitable polyolefinic elastomer materials which are available, for example, under the product names Nisso BI-3000 and Nisso BI-3015 from Nippon Soda Co. Ltd., Japan.

[0089] Alternatively, polybutadienes having hydroxyl end groups are also available as polyolefinic elastomer materials, as already described in detail above.

[0090] The share of the 1,2-polybutadiene, in particular having a molar mass of about 3000 g / mol, for providing the shielding groups can be in the range of about 1 wt.-% to about 60 wt.-%, in particular up to about 40 wt.-%, more preferably up to about 30 wt.-%, and also preferably in the range of about 2 to about 10 wt.-%, each based on the total polymer content of the hybrid elastomer material.

[0091] A too low or too high concentration of shielding groups in the hybrid elastomer used according to the present application can be disadvantageous in terms of quality. As already mentioned before, the grafted shielding groups should mainly serve to prevent cleavage reactions and back reactions in aqueous media.

[0092] A too high grafting degree of the 1,2-polybutadiene units can lead to a decrease in the tensile strength of the hybrid elastomer used according to the present application, for example, compared to a pure addition-crosslinked standard LSR material (corresponding to the backbone of the hybrid elastomer according to the present application). Furthermore, the long-term seal force performance can deteriorate after aerobic and anaerobic hot air aging.

[0093] The present application also relates to a process for producing a hybrid elastomer material according to the present application comprising the following steps:

[0094] - providing a reaction mixture comprising a share of a siloxane polymer material and a share of a polyolefinic elastomer material;

[0095] - and an addition-crosslinking of both materials.

[0096] If the hybrid elastomer material according to the application is produced in an injection molding process, the reaction mixture used here is generally produced from two mixture components, which are also referred to as components A and B in the following. Both components A and B are combined together immediately prior to injection molding, for example mixed with one another in a static mixer of the injection molding machine. The viscosities of components A and B are preferably matched to one another in order to achieve as homogeneous, finely dispersed a distribution as possible on mixing. This can be seen from the following formulation examples.

[0097] In the process according to the application, the reaction mixture is preferably prepared from a component A and a component B, wherein component A comprises a first polysiloxane material fraction, a polyolefin material fraction and a catalyst for addition crosslinking, and wherein component B comprises a first polysiloxane material fraction and a second (poly)siloxane material fraction which is different from the first polysiloxane material, wherein the first polysiloxane material comprises a vinyl polysiloxane having terminal vinyl groups and the second (poly)siloxane material comprises a (poly)siloxane having side chains and / or terminal SiH groups.

[0098] Only component A comprises the catalyst and optionally the inhibitor, while only the crosslinker is added to component B, which can additionally comprise an inhibitor fraction if necessary. The inhibitor is used in the range from 0 to about 600 ppm, based on the sum of the fractions of components A and B, based on the total weight of the reaction mixture.

[0099] According to a further aspect of the process according to the application, the reaction mixture comprises a filler, in particular in the form of a hydrophobic and / or hydrophilic mineral filler.

[0100] Furthermore, in the process according to the application, the filler can be provided in a masterbatch and the masterbatch is added to the reaction mixture, preferably as an ingredient of component A and / or component B.

[0101] The application also relates to a polymer electrolyte fuel cell stack having a plurality of fuel cells, wherein the cell stack comprises a sealing element produced using the hybrid elastomer material according to the application.

[0102] The application also relates to the use of the hybrid elastomer material according to the application in a screen printing process. Coatings produced using the screen printing process can also form sealing elements of fuel cells in particular. In particular, coatings having a layer thickness in the range from about 10 μm to about 500 μm, preferably from about 10 μm to about 150 μm, more preferably from about 60 μm to about 120 μm, can also be applied to substrates by the screen printing process. In the case of static loading, a layer thickness of about 100 μm is suitable, a layer thickness of from about 80 μm to about 100 μm being particularly suitable for elastic applications. Such coatings can optionally be formed with a closed-cell porous structure, which can be produced in different ways, as will be explained in more detail below.

[0103] In such applications, according to a first variant, use is made of hybrid elastomers according to the application, the filler fraction of which is at most about 30% by weight, in particular also at most about 20% by weight and also at most about 10% by weight. Generally, the filler fraction is at least about 5% by weight. The filler is also optionally chosen from expandable / expanded glass materials or ceramic materials. As already mentioned, polymeric particles based on polyurethane, polyethylene, polypropylene, polyacrylate and polycarbonate are also suitable. The pore diameter in these fillers can be, for example, from about 1 μm to about 200 μm. The pore structure / foam structure of the coating can also be produced from polymeric particles which are expandable during the crosslinking of the polymer of the coating.

[0104] Fine-particle powders in the form of porous glass particles having a particle size of from about 10 μm to about 200 μm are particularly suitable as fillers for hybrid elastomers having a pore structure.

[0105] The density of the porous hybrid elastomer material of from about 0.7 g / cm3 3 to about 1.1 g / cm3 3 is preferably achieved by the addition of a predetermined amount of such fillers, where in this case the mechanical properties of the hybrid elastomer material, in particular the tensile strength and the elongation at break, are substantially preserved.

[0106] Suitable porous glass particles are available under the trade names 11W34G (average particle size of from about 30 to about 40 μm) or 34P30 (average particle size of about 30 μm) from Potters Industries, Inc. Poraver® porous glass particles having an average particle size of from about 40 to about 200 μm of the type Poraver® 40, Poraver® 60, Poraver® 80, Poraver® 100, Poraver® 120, Poraver® 140, Poraver® 160 and Poraver® 200 from Dennert Poraver GmbH are also suitable.

[0107] According to a second variant, polymeric porous particles can be used as fillers, which generally have an average pore diameter in the range from about 1 μm to about 200 μm, preferably from about 1 μm to about 10 μm. Specific examples in this regard are the products of the type DE(T), WE and FG from Akzo Nobel Pulp and Performance Chemicals AB, which have an average particle size of from about 5 μm to about 100 μm. The amount of polymeric porous particles used in the hybrid elastomers according to the application can be at most 4% by weight, preferably at most about 2% by weight, without impairing the siloxane crosslinking.

[0108] ​​According to a third variant, a closed-cell porous structure is produced in situ or beforehand in the hybrid elastomeric material according to the application. To produce such pores or pore structures, particles based on polyurethane, polyethylene, polypropylene, polyacrylate and polycarbonate can be used, which swell by absorbing solvent in a suitable solvent, preferably selected from pure hydrocarbons, and then expand endothermically to form a pore structure. The addition of such fillers to the hybrid elastomer according to the application is preferably limited to about 2 wt.% or less, wherein the density of the hybrid elastomeric material can also reach a range of about 0.7 g / cm 3 up to about 1.1 g / cm 3 without strongly impairing the mechanical properties, in particular the tensile strength and elongation at break.

[0109] Examples of particles that can swell in the above sense and are commercially available are the DU, WU, MB and SL types, or also the INC, NC and NCS types from the company Tramaco GmbH.

[0110] These and other aspects of the hybrid elastomeric material according to the application and the hybrid elastomers used therein are explained in more detail with reference to the following examples and figures. Examples

[0111] The hybrid elastomeric material according to the application is produced using a silicone polymeric material and a polyolefin elastomeric material.

[0112] To provide the silicone polymeric material, a so-called liquid silicone based on a two-component (2K) additive system from the group of organic silicone elastomers (also known as LSR or liquid silicone rubber) is preferably used.

[0113] One-component (1 K) mixtures can also be produced on a laboratory scale, but their storage time is limited, so that for industrial applications a 2K additive system is preferred.

[0114] To provide the two-component additive system, two ready-to-use pre-mixes, hereinafter referred to as component A and component B, are produced, which are usually mixed with each other in a 1 : 1 share. The two components A and B each contain a so-called masterbatch share, which will be described in more detail below, which preferably provides hydrophobic and / or hydrophilic fillers and is composed simply as follows:

[0115] Component A

[0116] - masterbatch

[0117] - vinylsiloxane polymer with terminal arrangement of vinyl groups (formula (II))

[0118] - platinum catalyst

[0119] - optional retarder for adapting the reaction kinetics

[0120] - optional further functional additives or fillers

[0121] Component B

[0122] - masterbatch

[0123] - vinyl siloxane polymer with terminal arrangement of vinyl groups (formula (II))

[0124] - crosslinker in the form of a siloxane with H-modified side chains (formula (I))

[0125] - chain extender in the form of a siloxane with H-modified end groups (formula (I))

[0126] - crosslinker of formula (III) (crosslinker)

[0127] - optional retarder for adapting the reaction kinetics

[0128] - optional further functional additives or fillers

[0129] Functional additives are optionally used to optimize the properties of the hybrid elastomer material according to the application for specific applications, in particular also its chemical resistance.

[0130] The masterbatch used in each case in components A and B comprises a vinyl siloxane polymer with terminal vinyl groups (formula (II)) as reaction medium, to which an in situ prepared hydrophobized silicic acid is added according to the following examples.

[0131] The hydrophobized silicic acid can be prepared, for example, by mixing the hydrophilic fumed silicic acid substantially homogeneously with the vinyl siloxane polymer of formula (II) used as reaction medium at this stage in a double-Z discharge kneader. Here, the hydrophilic OH groups of the silicic acid are replaced by trimethylsilyl groups of the added hydrophobizing agent. The production of such a product is generally known and is described, for example, in Examples 5 and 7 of patent EP 0 378 785 A1.

[0132] Specific examples of compositions which can be used to provide the masterbatch of hydrophobized fumed silicic acid are listed in Table 2 below as Masterbatch 1. In most of the examples below, this composition is used as masterbatch at the same time.

[0133] Table 2 (Masterbatch 1 ; MBA 37130)

[0134]

[0135]

[0136] In addition to masterbatch 1 in table 2, masterbatch 2 according to table 3 can also be used, which differs from masterbatch 1 in that the filler used, i.e. a mixture of two different silicic acids is contained for hydrophobization and further filler reinforcement, i.e. in addition to Aerosil 300V also Aerosil 814 (Evonik Industries) (see example 3, BF146). The concentration of masterbatch 2 in components A and B of the formulation of example 3 (BF146) deviates from the concentration of the formulation of example 2 (BF131).

[0137] Table 3 (masterbatch 2)

[0138]

[0139] In addition, masterbatch 3 according to table 3A, also referred to as MBA 37121 below, can be used.

[0140] Table 3A (masterbatch 3; MBA 37121)

[0141]

[0142]

[0143] For the preparation of components A and B of the following examples, respectively, a planetary dissolver was used which meets the following requirements:

[0144] The capacity of the stirring vessel was about 1 liter and was equipped with a double jacket with a cooling water connection. It was necessary to degas the mixture using a vacuum pump. The planetary dissolver was filled under pressure with the aid of a pressure machine.

[0145] Components A and B each contained a share of a vinyl polysiloxane with terminal vinyl groups (65,000 mPas) (base polymer), which was available from Momentive Performance Materials GmbH as Silopren U65 or from CHT Germany GmbH as ALPA-VINYL-POLYMER 65, the share for the purpose of homogenizing the viscosity of the respective component being varied.

[0146] As described above, the following parameters preferably apply to the composition of the total mass of the hybrid elastomer material according to the application:

[0147] The share of the siloxane polymers of the formula (I) and optionally (II) in the total mass of the polymer fraction of the hybrid elastomer material according to the application is preferably from about 50 to about 90 wt.-%, more preferably from about 60 to about 70 wt.-%.

[0148] More preferably, the siloxane polymer of formula (I) is in the form of a mixture of polymers having a dynamic viscosity of about 10,000 mPas (n = 850) and 1,000 mPas (n = 350), wherein the weight ratio of these units is preferably about 1 :2. The total share of these siloxane polymers in the composition of the hybrid elastomer used according to the application is preferably about 62 to about 67% by weight.

[0149] Furthermore, in the preferred siloxane polymer material, a siloxane polymer of formula (I) is used, which has terminal SiH groups and thus can assume the function of a chain extender. The share of this siloxane polymer in the siloxane polymer material is preferably about 1 to about 10% by weight, more preferably about 1 to about 3% by weight.

[0150] Within these preferred specifications, the individual ingredients of the formulation can vary greatly, as summarized in Tables 4A and 4B below for components A and B:

[0151] Table 4A (Component A)

[0152]

[0153] Table 4B (Component B)

[0154]

[0155] In addition to the masterbatch, for example the masterbatch (ALPA MBA 37130) of Table 2, component A also comprises a platinum catalyst and a base polymer (for example the liquid silicone Silopren U65, viscosity: 65,000 mPas, manufacturer: Momentive Performance Materials GmbH), the share of which is used to assimilate the viscosity to the viscosity of component B can vary.

[0156] Component A preferably comprises a platinum-based, silicophilic catalyst complex, for example according to the catalyst systems of Ossko, Osborn-Fisher, Ashby, Markó, but preferably the Karstedt catalyst.

[0157] Other transition metal complexes can also be based on other central atoms of the platinum group, namely Rh, Ru, Ir, Os, Pd. A ruthenium complex according to patent EP 2 004 663 B1 (Wacker AG) and a ruthenium-sulfoxide complex according to patent EP 2 285 814 B1 (Wacker AG) are listed here. The ligands should have siliconophilic properties. In addition, lanthanide transition metal complexes should be mentioned, which do not follow the Chalk-Harrod mechanism. The concentration of the catalyst in component A can vary in a broad range from about 5 to about 1000 ppm, preferably the concentration is in the range from about 30 to about 80 ppm. Throughout the formulation, the catalyst is present in half the concentration, since component A is mixed with component B, which does not contain the catalyst, in a 1 : 1 ratio.

[0158] In addition to the masterbatch, for example the masterbatch of table 2 (ALPA MPA 37130), component B also comprises a combination of different crosslinking agents, for example a so-called standard crosslinking agent (Hansa SFA 11230) or a soft crosslinking agent (Hansa SFA 11340), as well as a chain extender (HANSA SFA 12010). In addition, component B comprises a vinyl polysiloxane with terminal vinyl groups (Silopren U65), the proportion of which can also be varied in order to adapt the viscosity to the viscosity of component A, and optionally also a retarder, for example 1-ethynyl-1-cyclohexanol (ECH).

[0159] The concentration and chemical structure of the so-called standard crosslinking agents and soft crosslinking agents (crosslinking agents) contained in component B influence the conversion and kinetics of the chemical crosslinking reaction.

[0160] The siloxane crosslinking agents and chain extenders in component B, for example Hansa SFA 11340, Hansa SFA 11230 and Hansa SFA 12010, have reactive SiH units along the main chain and / or at the end. The various Hansa SFA products provided by CHT Germany GmbH correspond to formulae (II) and (III). They can be contained in component B in a total of about 1 to about 30% by weight, preferably about 12 to about 20% by weight.

[0161] The ALPA and HANSA ingredients of components A and B of the following examples are available from CHT Germany GmbH.

[0162] Example 1, according to the application (BF 109)

[0163] Component A

[0164]

[0165]

[0166] Weigh 630 g of masterbatch 1 from table 2, 249.9 g of a vinyl polysiloxane with terminal vinyl groups (65,000 mPas) of the formula (II) and 40 g of 1,2-polybutadiene into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1,000 rpm. Thereafter, 60 g of Ti02pigment IRIOTEC 8850 and 20 g of Ti02pigment KRONOS 2300 are added at the same rotational speed. Once the mass is homogeneous (after about 60 minutes), 0.1 g of Pt(0) Karstedt catalyst is added and the entire mass is homogenized in the dissolver for 2 hours under a vacuum of 100 mbar. The temperature must be kept below 30°C.

[0167] Component B

[0168]

[0169] Weigh 696.5 g of masterbatch 1 from table 2 and 101.2 g of a vinyl polysiloxane with terminal vinyl groups of the formula (II) (65,000 mPas) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1,000 rpm. Thereafter, 126 g of a polysiloxane of the type HANSA SFA 11230 as crosslinker, 23.6 g of a polysiloxane of the type HANSA SFA 12010 as chain extender and 52.7 g of a polysiloxane of the type HANSA SFA 11340 as passivator are added at the same rotational speed. Once the mass is homogeneous (after about 30 minutes), homogenize for a further 2 hours under a vacuum of 100 mbar. The temperature must be kept below 30°C.

[0170] Components A and B are mixed with one another in a weight ratio of 1 :1 and the polymer components are subjected to addition crosslinking as described below.

[0171] Examples 1A, 1 B, 1 C and 1 D (according to the application)

[0172] In examples 1A, 1 B and 1 C, 2% by weight of filler are mixed into each of the two components A and B of example 1 when the masterbatch is mixed with the vinyl polysiloxane component, based on the respective formulation, to form a closed-cell cellular structure; in example 1 D, 5% by weight of filler are mixed in, based on the total weight of the formulation.

[0173]

[0174] The UNICELL filler is available from Tramaco GmbH

[0175] Expancel fillers are available from Akzo Nobel Pulp and Performance Chemicals AB

[0176] Q-Cel fillers are available from Potters Industries LLC (Cary Company)

[0177] Example 1 E according to the application (BF 109 B)

[0178] The formulation corresponds in general to Example 1, except that 4.0 wt.-% of hydrogenated polybutadiene BI-3015 instead of 1,2-polybutadiene B-3000 is contained in component A. The hybrid elastomer is prepared as in Example 1 (BF 109).

[0179] Example 2 according to the application (BF 131 )

[0180] Component A

[0181]

[0182]

[0183] The amounts of 628.8 g of masterbatch 1 of Table 2, 190 g of vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) and 26 g of 1,2-polybutadiene were weighed into the stirring vessel of a planetary dissolver and homogenized for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Then 134.3 g of silicone resin as hydrophobizing and mechanical reinforcing component were added at the same rotational speeds. Then 20 g of Ti02pigment were added at the same rotational speeds. Once the mass was homogeneous (about 60 minutes), 0.9 g of Pt(0) Karstedt catalyst were added and the entire mass was homogenized for 2 hours under vacuum at 100 mbar. The temperature had to be kept below 30°C.

[0184] Component B

[0185]

[0186] Weigh 615.7 g of masterbatch 1 of table 2 and 112.5 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1,000 rpm. Thereafter, 162 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 21.5 g of a polysiloxane of type HANSA SFA 12010 as chain extender and 47.9 g of a polysiloxane of type HANSA SFA 11340 as passivator are added at the same speed. Once the mass is homogenized (after about 60 minutes), 7.4 g of 1,2-polybutadiene and 33 g of silicone resin are added and the entire mass is homogenized for 2 hours under vacuum of 100 mbar. The temperature must be kept below 30°C.

[0187] Components A and B are mixed with each other in a weight ratio of 1 :1 and the polymer components are subjected to addition crosslinking as described below.

[0188] Example 3, according to the application (BF146)

[0189] Component A

[0190]

[0191] Weigh 615.7 g of masterbatch 1 of table 2 and 112.5 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1,000 rpm. Thereafter, 162 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 21.5 g of a polysiloxane of type HANSA SFA 12010 as chain extender and 47.9 g of a polysiloxane of type HANSA SFA 11340 as passivator are added at the same speed. Once the mass is homogenized (after about 60 minutes), 7.4 g of 1,2-polybutadiene and 33 g of silicone resin are added and the entire mass is homogenized for 2 hours under vacuum of 100 mbar. The temperature must be kept below 30°C.

[0192] Component B

[0193]

[0194]

[0195] Weighing 657.7 g of masterbatch 2 of table 3 and 101.2 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) of table 3 into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, 168 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 22.5 g of a polysiloxane of type HANSA SFA 12010 as chain extender and 50.0 g of a polysiloxane of type HANSA SFA 11340 as passivator are added at the same speed. Once the mass is homogenized (after about 60 minutes), 0.6 g of 1-ethynyl-1-cyclohexanol (ECH) as inhibitor is added and the whole mass is homogenized for 2 hours under vacuum of 100 mbar. The temperature must be kept below 30°C.

[0196] Components A and B are mixed with each other in a weight ratio of 1 : 1 and the polymer components are subjected to addition crosslinking, as described below.

[0197] Example 4 (reference: standard LSR material ALPA 130201)

[0198] Component A

[0199]

[0200] Weighing 657.7 g of masterbatch 2 of table 3 and 101.2 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) of table 3 into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, 168 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 22.5 g of a polysiloxane of type HANSA SFA 12010 as chain extender and 50.0 g of a polysiloxane of type HANSA SFA 11340 as passivator are added at the same speed. Once the mass is homogenized (after about 60 minutes), 0.6 g of 1-ethynyl-1-cyclohexanol (ECH) as inhibitor is added and the whole mass is homogenized for 2 hours under vacuum of 100 mbar. The temperature must be kept below 30°C.

[0201] Component B

[0202]

[0203] Weigh out 696.5 g of masterbatch 1 of table 2 and 101.2 g of a vinyl polysiloxane with terminal vinyl groups (65,000 mPas) of formula (II) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, add 126 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 23.6 g of a polysiloxane of type HANSA SFA 12010 as chain extender and 52.7 g of a polysiloxane of type HANSA SFA 11340 as passivator as crosslinker at the same speed. Once the mass is homogeneous (after about 30 minutes), homogenize for a further two hours under a vacuum of 100 mbar. The temperature must be kept below 30°C.

[0204] Components A and B are mixed with each other in a weight ratio of 1 : 1 and the polymer components are addition-crosslinked, as described in the following sections.

[0205] Example 5, according to the application (1 wt% polybutadiene fraction)

[0206] Component A

[0207]

[0208] Weigh out 696.5 g of masterbatch 1 of table 2 and 101.2 g of a vinyl polysiloxane with terminal vinyl groups (65,000 mPas) of formula (II) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, add 126 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 23.6 g of a polysiloxane of type HANSA SFA 12010 as chain extender and 52.7 g of a polysiloxane of type HANSA SFA 11340 as passivator as crosslinker at the same speed. Once the mass is homogeneous (after about 30 minutes), homogenize for a further two hours under a vacuum of 100 mbar. The temperature must be kept below 30°C.

[0209] Component B

[0210]

[0211] Weigh out 514.4 g of masterbatch 1 from Table 2, 273.1 g of a vinyl polysiloxane with terminal vinyl groups of the formula (II) (65,000 mPas) and 10 g of 1,2-polybutadiene into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, 119 g of a polysiloxane of the type HANSA SFA 11230 as crosslinker, 19.5 g of a polysiloxane of the type HANSA SFA 12010 as chain extender and 64 g of a polysiloxane of the type HANSA SFA 11340 as passivator are added at the same rotational speeds. Once the material is homogeneous (after about 30 minutes), homogenize for a further 2 hours under a vacuum of 100 mbar. The temperature must be kept below 30°C.

[0212] Components A and B are mixed with one another in a weight ratio of 1 :1 and the polymer components are subjected to addition crosslinking as described below.

[0213] Example 6, according to the application (5% by weight share of polybutadiene)

[0214] Component A

[0215]

[0216] Weigh out 514.4 g of masterbatch 1 from Table 2, 273.1 g of a vinyl polysiloxane with terminal vinyl groups of the formula (II) (65,000 mPas) and 10 g of 1,2-polybutadiene into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, 119 g of a polysiloxane of the type HANSA SFA 11230 as crosslinker, 19.5 g of a polysiloxane of the type HANSA SFA 12010 as chain extender and 64 g of a polysiloxane of the type HANSA SFA 11340 as passivator are added at the same rotational speeds. Once the material is homogeneous (after about 30 minutes), homogenize for a further 2 hours under a vacuum of 100 mbar. The temperature must be kept below 30°C.

[0217] Component B

[0218]

[0219] Weigh out 521.9 g of masterbatch 1 of table 2 and 243.1 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, add 121 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 21 g of a polysiloxane of type HANSA SFA 12010 as chain extender and 43 g of HANSA SFA 11340 as mechanical reinforcing component at the same speed. Once the mass is homogeneous (after about 60 minutes), homogenize 50 g of 1,2-polybutadiene and the entire mass under vacuum at 100 mbar for 2 hours. The temperature must be kept below 30°C.

[0220] Components A and B are mixed with one another in a weight ratio of 1 :1 and the polymer components are subjected to addition crosslinking as described below.

[0221] Example 7, according to the application (10 wt% share of polybutadiene) (CL253)

[0222] Component A

[0223]

[0224] Weigh out 521.9 g of masterbatch 1 of table 2 and 243.1 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, add 121 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 21 g of a polysiloxane of type HANSA SFA 12010 as chain extender and 43 g of HANSA SFA 11340 as mechanical reinforcing component at the same speed. Once the mass is homogeneous (after about 60 minutes), homogenize 50 g of 1,2-polybutadiene and the entire mass under vacuum at 100 mbar for 2 hours. The temperature must be kept below 30°C.

[0225] Component B

[0226]

[0227] Weigh 558.9 g of masterbatch 1 of table 2 and 86 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, 122.8 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 131.9 g of a polysiloxane of type H-Si 150 / 2 as chain extender of this type are added at the same speed. Once the mass is homogenized (after about 60 minutes), 100 g of 1,2-polybutadiene and 0.40 g of the retarder ALPA Retard A are added and the entire mass is homogenized for 2 hours under a vacuum of 100 mbar. The temperature must be kept below 30°C.

[0228] Components A and B are mixed with each other in a weight ratio of 1 :1 and the polymer components are subjected to addition crosslinking as described below.

[0229] Example 7A, according to the application

[0230] The formulation corresponds in general to example 7, except that 10.0 wt.-% of hydrogenated polybutadiene BI-3015 instead of 1,2-polybutadiene B-3000 are contained in components A and B, respectively. The hybrid elastomer is prepared as in example 7.

[0231] Example 8, according to the application (20 wt.-% share of polybutadiene) (BF 290)

[0232] Component A

[0233]

[0234] Weigh 545.1 g of masterbatch 1 of table 2, 201.4 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) and 200 g of 1,2-polybutadiene into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, 37.9 g of the modified Ti02pigment Iriotec 8850 and 12.6 g of the Ti02pigment KRONOS 2300 as mechanical reinforcing component are added at the same speed. Once the mass is homogenized (after about 60 minutes), 3.0 g of the Pt(0) Karstedt catalyst are added and the entire mass is homogenized for 2 hours under a vacuum of 100 mbar. The temperature must be kept below 30°C.

[0235] Component B

[0236]

[0237] Weigh out 496.8 g of masterbatch 1 of table 2 and 76.5 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, add 109.2 g of a polysiloxane of type HANSA SFA 11230 as crosslinker, 117.2 g of a polysiloxane of type H-Si 150 / 2 as chain extender at the same speed. Once the mass is homogeneous (after about 60 minutes), add 200 g of 1,2-polybutadiene and 0.3 g of the inhibitor ALPA Retard A and homogenize the entire mass under vacuum at 100 mbar for 2 hours. The temperature must be kept below 30°C.

[0238] Components A and B are mixed with one another in a weight ratio of 1 :1 and the polymer components are subjected to addition crosslinking as described below.

[0239] Example 8A, according to the application (BF 290Y)

[0240] The formulation corresponds overall to example 8, except that 20.0 wt.-% of hydrogenated polybutadiene BI-3015 is contained in components A and B instead of 1,2-polybutadiene B-3000. The hybrid elastomer is prepared as in example 8 (BF 290).

[0241] Example 9, according to the application (40 wt.-% share of polybutadiene) (BF 307)

[0242] Component A

[0243]

[0244] Weigh out 403.5 g of masterbatch 3 of table 3A, 149.2 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) and 400 g of 1,2-polybutadiene into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, add 33.2 g of the modified Ti02pigment Iriotec 8850 and 11.1 g of the Ti02pigment KRONOS 2300 as mechanical reinforcing components at the same speed. Once the mass is homogeneous (after about 60 minutes), add 3.0 g of the Pt(0) Karstedt catalyst and homogenize the entire mass under vacuum at 100 mbar for 2 hours. The temperature must be kept below 30°C.

[0245] Component B

[0246]

[0247]

[0248] Weigh 657.7 g of masterbatch 1 of table 2 and 101.1 g of a vinyl polysiloxane with terminal vinyl groups of formula (II) (65,000 mPas) into the stirring vessel of a planetary dissolver and homogenize for 10 minutes at a planetary drive speed of 10 rpm and a dissolver speed of 1000 rpm. Thereafter, 168.7 g of a polysiloxane of type HANSA SFA 11230 as crosslinker I, 50.0 g of a polysiloxane of type HANSA SFA 11340 of formula (III) (4000 mPas) as crosslinker II, 22.3 g of a polysiloxane of type HANSA SFA 11340 as chain extender of type HANSA SFA 12010 are added at the same speed. Once the mass is homogenous (after about 60 minutes), 0.2 g of the retarder ALPA Retard A is added and the entire mass is homogenized for 2 hours under vacuum of 100 mbar. The temperature must be kept below 30°C.

[0249] First, components A and B are mixed with each other in a weight ratio of 1 : 1, then another portion of BI-3015 type 1,2-polybutadiene is added so that the content of 1,2-polybutadiene in the mixture reaches a value of 40.0 wt.%. The polymer ingredients are then subjected to the addition crosslinking described later.

[0250] Despite the high share of 1,2-polybutadiene, an optimized fast reaction kinetics is observed. BRIEF DESCRIPTION OF DRAWINGS

[0251] Properties of the hybrid elastomer material according to the application compared to conventional LSR elastomers and EPDM elastomers

[0252] In the following, various properties of the hybrid elastomer material according to the application are investigated and compared to corresponding properties of conventional LSR elastomers and EPDM elastomers. The results are described in detail below and partly shown in the figures. In the figures, the following is shown in detail:

[0253] Figure 1 A curve showing the change in static long-term sealing force after oxidative hot-air aging of conventional elastomer materials and hybrid elastomer materials according to the application under the influence of the share of polyolefin protecting groups;

[0254] Figures 2A to 2C A depolymerization effect of conventional elastomer materials and hybrid elastomer materials according to the application after storage in sulfonic acid based on electron micrographs;

[0255] Figures 3A to 3C A depolymerization effect of conventional elastomer materials and hybrid elastomer materials according to the application after storage in FKM ionomer dispersions based on electron micrographs;

[0256] Figure 4 The influence of the 1,2-polybutadiene content of the polymer material on the hydrogen permeation coefficient P is shown schematically; and

[0257] Figures 5A to 5D The electron micrographs after storage in FKM ionomer dispersions of conventional elastomer materials and various hybrid elastomer materials according to the application are shown.

[0258] General test procedures for determining the properties of conventional elastomers and hybrid elastomer materials according to the application

[0259] For testing the application properties of the elastomers obtained from Examples 1 to 9, crosslinked sheets were prepared from the respective components A and B as test specimens, as described below.

[0260] To this end, the two components A and B were each combined in a 1 :1 share in a vacuum high-speed mixer (U. Hauschild) under vacuum (about 100 mbar) at room temperature for a mixing time of about 2 minutes, then poured into a mold to produce a sheet (thickness 2 mm) and vulcanized (1 h / 150°C).

[0261] The chemical crosslinking reaction in the production of the hybrid elastomer materials according to the application starts immediately after the components A and B are mixed together and under the action of temperature (20°C to 200°C). Both components A and B are each adjusted to a similar viscosity level to improve miscibility.

[0262] From these sheets, test specimens conforming to the respective standards were produced to determine:

[0263] DIN 53505 - Shore A hardness

[0264] DIN 53504 S2 - Tensile test - tensile strength and elongation at break

[0265] DIN ISO 34-1, method B, test (a) + (b) tear resistance

[0266] ISO 188, DIN ISO 1817 chemical resistance

[0267] Rheological properties (curemeter test), 150°C to 180°C, 3 minutes.

[0268] ISO 815 - Compression set test (DVR)

[0269] The results are summarized in Tables 5 to 12 below, parts of which are shown in Figure 1 to 5.

[0270] Influence of the polyolefin fraction on the crosslinking reaction kinetics and mechanical properties of hybrid elastomer materials according to the present invention

[0271] Based on example 1 (BF109), the influence of different concentrations of 1,2-polybutadiene in the overall formulation on the chemical crosslinking reaction kinetics and the resulting mechanical starting values was investigated. In addition, the viscoelastic behavior of the obtained samples was described in the compression set (CVR) test. The material of sample 4 corresponds to example 1 (BF109). The materials of samples 1 and 2 correspond to examples 8 and 7. The materials of samples 3 and 5 correspond to examples 6 and 5.

[0272] The t10 values given in table 5 correspond to the time at which 10% of the relative crosslinking conversion has taken place at 180°C, the t90 value indicates the time to achieve 90% of the relative crosslinking conversion. This applies to the t50 and t80 values. These values are determined by means of so-called crosslinking isotherms. These are measured on a vulcameter, in which the torque over the measurement time indicates the increase in the internal crosslinking density in the elastomer material. The lower heated half of the cavity oscillates around a deflection angle, wherein the upper heated rigid half of the cavity detects the torque required for this. The device manufacturer: Zwick® / Roell®Material Testing Machine GmbH, MonTech Material Testing Machine GmbH.

[0273] The minimum value describes the uncrosslinked state, while the maximum value corresponds to the fully crosslinked state. The difference between the minimum and maximum values represents the relative crosslinking density.

[0274] Unlike pure LSR materials, a reaction retarder is not necessary in the hybrid raw material system according to the present invention and is therefore usually 0 ppm, so that the reaction kinetics can be increased.

[0275] The stress modulus obtained from the tensile test according to DIN 53504 S2 describes the static stiffness of the crosslinked hybrid elastomer material according to the present invention and corresponds to the elastic modulus.

[0276] The properties of the various samples and the data obtained in the tests are summarized in table 5.

[0277] Table 5

[0278]

[0279] With increasing grafting degree (for example with 1,2-polybutadiene), the hybrid elastomer becomes increasingly less reactive, as can be seen from the comparison of the crosslinking properties of the various samples in table 5.

[0280] A higher catalyst concentration and crosslinker concentration can compensate for this kinetic loss that occurs with increasing grafting degree of 1,2-polybutadiene to a certain extent.

[0281] Technical properties of the hybrid elastomer material according to the invention

[0282] It has been shown that too low or too high concentrations of shielding groups in the hybrid elastomer according to the invention are not beneficial in terms of quality. Grafted shielding groups hinder the cleavage reaction and the back reaction in aqueous media.

[0283] However, an increase in the grafting degree of the 1,2-polybutadiene units, i.e. more than about 2 wt.-% at a molecular weight of 3000 g / mol, leads to an increasingly significant decrease in the tensile strength compared to pure, addition-crosslinkable standard LSR materials (backbone), as can be seen from Table 7 at the same crosslinking chemical concentration.

[0284] In addition, with increasing 1,2-polybutadiene fraction, the static long-term seal force performance deteriorates significantly, especially after aerobic and anaerobic hot air aging. This effect limits the use of the hybrid elastomer according to the invention to temperatures below 120 °C.

[0285] Figure 1 The long-term seal force performance after oxidative hot air aging at 120 °C of various conventional elastomer materials and the hybrid elastomer material according to the invention is shown, in which the decrease in static seal force in % is plotted against the storage time in hours. As a comparison to the hybrid elastomer materials according to the invention based on the formulations of Example 1 (BF109) (2 wt.-% 1,2-PB B-3000), Example 7 (10 wt.-% 1,2-PB B-3000) and Example 8 (20 wt.-% 1,2-PB B-3000), on the one hand an LSR standard material without organic protecting groups of Example 4 (ALPA 130201; ) is used, on the other hand the Keltan 2650 polyolefin material (ARLANXEO Netherlands BV) as ENB-EPDM. The seal force test is carried out according to the DIN EN ISO 1183-1 procedure A.

[0286] Figure 1 The influence of an increasing fraction of polyolefin groups in the hybrid elastomer material according to the invention on the static seal force development in the long-term test after oxidative hot air aging at 120 °C is shown, using the samples of Examples 1, 7 and 8 according to the invention and the conventional LSR material and EPDM material (Example 4) (LSR standard ALPA 130201) or Keltan 2650 (ARLANXEO Netherlands BV).

[0287] The residual fraction of still present, not consumed reactive SiH groups or vinyl groups in the addition crosslinking has a negative influence on the chemical aging behavior and the long-term chemical resistance. This has the effect of increasing the cleavage reaction or the back reaction on the siloxane network.

[0288] It is of utmost importance that the modified hybrid elastomers are chemically resistant to so-called pitting, which refers to the resistance to ageing of the polymer degradation and cleavage reactions caused by corrosive acids and increasing acid concentrations.

[0289] One important example is sulfonic acid, which can form on the membrane in PEM-FC fuel cells by cleavage reactions of sulfonic groups and then exist in the form of water-diluted. Due to its special properties, sulfonic acid is used as a balancing catalyst in the synthesis of LSR polymers and causes ring-opening reactions there.

[0290] Alkylbenzenesulfonic acid is a suitable test medium with which the damage pattern of polymer pitting or so-called siliconization on standard LSR materials can be well simulated, even though these structures do not usually occur in fuel cells.

[0291] Significant polymer degradation after the shortest contact times of 72 hours and 144 hours with very low concentrations of water-diluted alkylbenzenesulfonic acid leads to significant polymer degradation in standard LSR materials, as can be seen from the storage temperature of 75°C in Table 5.

[0292] In addition to the test results summarized in Table 6, Figures 2A to 2C The electron micrographs in accordance with the damage pattern illustrate the difference in chemical resistance between standard LSR materials and the hybrid elastomer materials according to the application of Examples 1 and 2 (BF109 and BF131) according to the application.

[0293] Table 6: Storage in alkylbenzenesulfonic acid (acid group concentration 0.091 mol / l) at 75°C

[0294]

[0295]

[0296] The base values given in the table correspond to the values measured on samples that have not yet been stored.

[0297] Table 7: Storage in water-diluted FKM ionomer dispersion 3M980EW (acid group concentration: 0.091 mol / l)

[0298]

[0299] The base values given in the table correspond to the values measured on samples that have not yet been stored.

[0300] Further tests on the FKM ionomer dispersions representing the starting products for coating the fuel cell membranes were carried out on the samples of Examples 1 and 2 and again with the LSR reference material. The results are summarized in Table 7 and visualized in the electron micrographs in accordance with the damage pattern in Figures 3A to 3C The electron micrographs in accordance with the damage pattern illustrate the difference in chemical resistance between standard LSR materials and the hybrid elastomer materials according to the application of Examples 1 and 2 (BF109 and BF131) according to the application.

[0301] The coating resulting from the dispersion is necessary for the proton transport in the electrochemical process of a fuel cell. FKM ionomer dispersions consist of polytetrafluoroethylene and perfluorosulfonyl vinyl ether, wherein the latter forms a PFSA (perfluorosulfonic acid) structure in aqueous media. They are available from several manufacturers including 3M, Dow Chemical, DuPont and Solvay.

[0302] The samples were likewise stored at 75°C for 72 hours and 336 hours in the product 3M 980EW (manufacturer 3M) with an acid group concentration of 0.091 mol / l. The advantage of the hybrid elastomers according to the application in terms of chemical resistance in this actual test medium is particularly evident compared to standard LSR materials, since the high concentration of PFSA thereof creates the most adverse, i.e. chemically aggressive, conditions. Pure LSR (reference ALPA 130201, Example 4) ages extremely under these conditions (see Table 6) whereas the hybrid elastomer materials according to the application, in particular the hybrid elastomer material according to Example 1 (BF109) show excellent medium resistance (Table 7 and Figure 3A ) and Figure 2A and 2B ).

[0303] The hybrid elastomer materials according to the application according to Example 1 (BF109) and subsequent Example 2 (BF131 ) show significantly better chemical resistance in the test media (Table 6 and Table 7) than conventional LSR materials. This is a major advantage of the hybrid elastomers according to the application.

[0304] Finally, the influence of the grafting degree of the organic shielding groups on the gas permeation resistance P is schematically shown in Figure 4 .

[0305] For standard LSR, the so-called hydrogen permeation P value is usually obtained in the dimension [cm 3 (NTP) mm / (m 2 h bar] at 20°C and 0% relative humidity, whereas EPDM materials (ethylene-propylene-diene rubber; here equivalent to 100 wt% of 1,2-polybutadiene) usually exhibit a P value of 56 P. The hybrid elastomers according to the application have a significantly reduced P value compared to standard LSR as shown in Figure 4 in terms of the content of 1,2-polybutadiene.

[0306] The test results after 1000 hours of storage at 75°C of the hybrid elastomer material obtained in Example 9 in a FKM ionomer aqueous dispersion with an acid group fraction of c = 0.091 mol / l (pH = 1.5 to 2; available as 3M 980EW from 3M) are summarized in Table 8 in comparison with other corresponding test values of the materials of Examples 1 and 8 and of a material from the prior art (Shin Etsu X34-4269). The electron micrographs of these materials after storage are shown in Figures 5A to 5D

[0307] Table 8

[0308]

[0309]

[0310] The compression set determined for the material of Example 9 (BF307) after hot air aging (24h / 150°C / cold debound) was 23.5%. The compression degree was 25%.

[0311] In comparison with the conventional Shin Etsu X34-4269 material (available from SHIN-ETSU SILICONES EUROPE B.V.) and also in comparison with the hybrid elastomer BF 109 according to the application obtained in Example 1, the chemical resistance of the hybrid elastomer material according to Example 9 of the application to aqueous diluted FKM ionomer dispersions is significantly improved.

[0312] Furthermore, in the case of the hybrid elastomer material obtained in Example 9, also a significantly improved resistance to extraction was observed (see Table 12 below).

[0313] Further test results of the hybrid elastomer materials according to the application of Examples 1, 1A, 1 B, 1 C and 1 D are summarized in Table 9 below.

[0314] Table 9

[0315]

[0316] *) The values for compression set in Table 9 were measured on samples after cold debound, which had been previously exposed to hot air at 150°C for 24 hours at a compression degree of 25%.

[0317] ​The mechanical parameters obtainable according to the application of the hybrid elastomer material according to the application are compared in Table 10 below with the values of a conventional LSR material, which is obtainable from SHIN-ETSU SILICONES EUROPE B.V. under the trade name ShinEtsu X34-4269. The difference is significant, in particular in terms of chemical resistance, compared to an aqueous FKM ionomer dispersion with an acid group content of c = 0.091 mol / l (here: 3M 725EW). Thus, the storage time of the reference material is shortened from 1000 hours to 336 hours.

[0318] Table 10

[0319]

[0320] The test results of the hybrid elastomer materials according to the application of Examples 1 (BF 109), 8 (BF 290) and 9 (BF 307) are summarized in Table 11 below.

[0321] Table 11

[0322]

[0323] *) The compression set values in Table 11 were measured on samples after cold removal, which had previously been exposed to hot air at 150°C for 24 hours at a compression of 25%.

[0324] Furthermore, the higher the polybutadiene content, in particular when the polybutadiene content is 30 to 40% by weight of the total formulation, the better the gas permeation resistance is observed.

[0325] Another important property of the elastomer seal stock, in particular of the hybrid elastomer according to the application, is their resistance to extraction, which overcomes the so-called pitting or so-called siliconization. The weight loss of the seal stock is usually associated with the flushing away of particles that can block or incorporate into the proton exchange membrane, which plays an electrochemical role in the fuel cell. This leads to irreversible power loss in the fuel cell.

[0326] The resistance to extraction can be easily detected by means of the weight loss after storage in the above FKM ionomer dispersions. The weight loss at different storage times for the five different hybrid elastomers according to the present application is summarized in Table 12 below. The weight loss expressed in weight-% was determined after re-drying the previously stored samples for 25 hours at 80°C. For comparison, samples of two conventional materials are included in the table, namely LSR ShinEtsu X34-4269 (available from SHIN ETSU SILICONES EUROPE B.V.) and the addition-crosslinkable liquid fluorosilicone DOW Silastic FL30-9201 (available from Dow Chemicals).

[0327] Table 12

[0328]

[0329] From the data in Table 12 it can be seen that the resistance to extraction improves with increasing polybutadiene fraction and tends to zero at a hydrogenated polybutadiene fraction of 30 wt.%. In contrast, the extraction values for the two conventional samples are much higher.

[0330] The extraction values given in Table 12 can also be applied to the resistance to pure water and aqueous coolant resistance.

Claims

1. A hybrid elastomeric material, wherein, The hybrid elastomer material comprises a hybrid elastomer having a share of siloxane polymer material and a share of polyolefin elastomer material, wherein the siloxane polymer material comprises siloxanes of formula (I) wherein the residues R are independently from each other H, CH3, vinyl, phenyl, (CH2) x CH3and / or C3H6O(C2H4O) y (C3H5O) z R'; wherein m = 1 to 100, n = 0 to 1000, x = 1 to 30, y = 0 to 20, z = 0 to 30, and wherein the sum m+n is > 3 and R' is H, CH3or (CH2) x CH3; and comprises siloxanes of formula (II) wherein the residue R 1 each independently is CH3, vinyl, and phenyl, and n 1 has a value in the range of 0 to 3000, wherein the polyolefin elastomer material is selected from 1,2-polybutadiene, wherein the sum of the shares of siloxanes of formula (I) and formula (II) relative to the total mass of the hybrid elastomer material is 50 to 90 wt.-%, wherein both materials are crosslinked to each other by an addition reaction.

2. The hybrid elastomeric material of claim 1, wherein, The siloxane polymer material has one or more pendant and / or terminal groups selected from H, C1-C 30 alkyl, C2-C 30 alkenyl, and aryl groups.

3. The hybrid elastomeric material of claim 2, wherein, The siloxane polymer material comprises one or more modified dimethylsiloxanes, wherein methyl groups are partially substituted by hydrogen to form SiH groups and vinyl groups.

4. The hybrid elastomer material of any one of claims 1 to 3, wherein, The hybrid elastomer material is crosslinked by an addition reaction using a siloxane crosslinker.

5. The hybrid elastomeric material of claim 4, wherein, The siloxane crosslinker is selected from crosslinkers of formula (III) wherein the residue R 2 independently of one another represent H and CH3, and wherein m 2 has a value in the range from 1 to 100 and n 2 has a value in the range from 0 to 500.

6. The hybrid elastomeric material of claim 5, wherein, There are three or more SiH groups per siloxane molecule.

7. The hybrid elastomeric material of claim 3, wherein, The ratio of the share of SiH groups to the share of vinyl groups in the siloxane polymer of formula (I) and in the siloxanes of formula (II) and (III) taken as a whole is in the range of 1 :0.5 to 1 :4.

5.

8. The hybrid elastomeric material of claim 7, wherein, The ratio of the share of SiH groups to the share of vinyl groups in the siloxane polymer of formula (I) and in the siloxanes of formula (II) and (III) taken as a whole is in the range of 1 :1.5 to 1 :2.

5.

9. The hybrid elastomer material of claim 1, wherein, The polyolefin elastomer material has functional groups selected from linear and branched C2-C8 alkyl groups and C2-C8 alkenyl groups as shielding groups.

10. The hybrid elastomeric material of claim 9, wherein, The polyolefin elastomer material has a share of shielding groups in the range of 40 to 92 wt.-%.

11. The hybrid elastomeric material of claim 10, wherein, The shielding groups are selected from vinyl groups, alkyl groups, 2,3-butene and mixtures thereof.

12. The hybrid elastomer material of claim 1, wherein, The share of siloxanes relative to the polymer share of the hybrid elastomer material is in the range of 70 to 99 wt.-%.

13. The hybrid elastomeric material of claim 12, wherein, The sum of the shares of the siloxane polymer of formula (I) and the siloxanes of formula (II) is in the range of 60 to 70 wt.-%.

14. The hybrid elastomer material of claim 1, wherein, The share of the polyolefin elastomer material relative to the polymer share of the hybrid elastomer material is in the range of 1 to 50 wt.-%.

15. The hybrid elastomeric material of claim 14, wherein, The share of the polyolefin elastomer material relative to the polymer share of the hybrid elastomer material is in the range of 1 to 30 wt.-%.

16. The hybrid elastomer material of claim 1, wherein, The hybrid elastomer material comprises one or more fillers, wherein the share of the fillers relative to the hybrid elastomer material is in the range of 5 to 50 wt.-%.

17. The hybrid elastomer material of claim 16, wherein, The hybrid elastomer material comprises one or more fillers, wherein the share of the fillers relative to the hybrid elastomer material is in the range of 15 to 30 wt.-%.

18. The hybrid elastomer of claim 16 or 17, wherein, The one or more fillers are selected from silicic acid based, silicone resin based and titanate based fillers.

19. The hybrid elastomer material of claim 1, wherein, The siloxane polymer material and the polyolefin elastomer material which are crosslinkable by an addition reaction are catalytically crosslinked by an addition reaction.

20. A process for manufacturing a hybrid elastomer material according to any one of claims 1 to 19, the process comprising the steps of - providing a reaction mixture comprising a share of siloxane polymer material and a share of polyolefin elastomer material; and - crosslinking both materials by an addition reaction. - providing a reaction mixture comprising a share of siloxane polymer material and a share of polyolefin elastomer material; and - crosslinking both materials by an addition reaction.

21. The method of claim 20, wherein, The reaction mixture is made from a component A and a component B, wherein the component A comprises a first polysiloxane material fraction, a polyolefin elastomer material fraction and a catalyst for addition crosslinking, and wherein component B comprises a first polysiloxane material fraction and a second siloxane material fraction different from the first polysiloxane material, wherein the first polysiloxane material comprises a vinyl polysiloxane with terminal vinyl groups and the second siloxane material comprises a siloxane with side chain and / or terminal SiH groups.

22. The method of claim 20 or 21, wherein, The reaction mixture comprises a filler.

23. The method of claim 22, wherein, The reaction mixture comprises a filler in the form of a hydrophobic and / or hydrophilic mineral filler.

24. The method of claim 22, wherein, The filler is provided in the form of a masterbatch and the masterbatch is added to the reaction mixture.

25. The method of claim 24, wherein, The filler is provided in the form of a masterbatch as an ingredient of component A and / or component B.

26. The method of claim 21, wherein, Component B comprises a fraction of a retarder.

27. A polymer electrolyte fuel cell stack having a plurality of fuel cells, wherein, The battery stack comprises a sealing element produced using the hybrid elastomer material according to any one of claims 1 to 19.

28. Use of the hybrid elastomer material according to any one of claims 1 to 19 in a screen printing process.

29. The use of claim 28, wherein, The hybrid elastomer material is applied to a substrate as a sealing compound in a screen printing process.

30. Use according to claim 28 or 29, wherein, The hybrid elastomer material is applied to the substrate in a layer thickness of 10 pm to 500 pm.

31. The use of claim 30, wherein, The hybrid elastomer material is applied to the substrate in a layer thickness of 10 pm to 100 pm.

32. The use of claim 28 or 29, wherein, The hybrid elastomer material comprises a filler forming a closed cell pore structure.

33. The use of claim 32, wherein, The hybrid elastomer material comprises a filler forming a closed cell pore structure in a content of 0.5 wt.-% to 4 wt.-%, based on the total weight of the hybrid elastomer material.

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