Molded part made of a flame-retardant elastomer composition for structural fire protection, and method for producing corresponding molded parts

Description

[0001] The present invention relates to molded parts for structural fire protection, which can be produced or are produced by vulcanizing a flame-retardant elastomer composition comprising an elastomer containing double bonds and a vinyl acetate-containing thermoplastic polymer, a crosslinker system comprising a sulfur- or sulfur-containing crosslinker and a peroxide crosslinker, and at least one flame retardant, wherein the sulfur- or sulfur-containing crosslinker is present in excess of the peroxide crosslinker in the crosslinker system. The present invention further relates to processes for producing corresponding molded parts and the use of the molded parts for applications with a minimum permissible service temperature of -40°C or less. State of the art

[0002] Elastic elements, such as those made of rubber or natural rubber, do not inherently exhibit flame-retardant or fire-retardant properties, as required for some applications due to standards or legal regulations. It is known that flame retardants or fire-retardant agents can be added to elastomers, such as rubber or natural rubber, to impart the desired flame-retardant properties. However, such additives generally impair the elastic properties, which often means that such an element made of rubber or natural rubber cannot, or no longer, meet the required elastic properties with regard to the desired static and dynamic properties.When used as a spring element or damping element or a similar element that is usually subject to highly dynamic loads, for example in vehicles, the required fire protection regulations cannot be satisfactorily met.

[0003] Due to this problem, it has been proposed not to manufacture the entire elastomer element with a flame retardant, but to provide such elements only with a flame-retardant coating. Such composite elements are described, for example, in DE 38 31 894 A1 and WO 2010 / 069842.

[0004] EP 2880 093 B1 describes a flame-retardant polymeric composition particularly suitable for coating workpieces, comprising: a) a vinyl acetate-containing thermoplastic polymer and) an unsaturated elastomer containing double bonds as polymeric components, wherein the polymeric components are present as a homogeneous polymer mixture, and a mixture matrix vulcanized exclusively by a sulfur or sulfur-containing crosslinking system is formed, wherein the sulfur crosslinking system extends over the entire matrix and completely penetrates it, and c) at least one flame retardant or a combination of flame retardants

[0005] A key factor in determining the properties of an elastomer is the crosslinking system, which transforms the initially flowable rubber into an elastomeric material with typical elastomeric properties. The type of crosslinking and the crosslinking density allow properties such as hardness, modulus, strength, elongation at break, tear resistance, and elasticity to be adjusted to the desired level.

[0006] Furthermore, flame-retardant-containing polymeric compositions are known from the prior art, which can be formed, for example, from mixtures of ethylene vinyl acetate and ethylene-propylene-diene monomer rubber. These mixtures are sometimes crosslinked with the aid of silanes, but mostly with peroxides or by irradiation.

[0007] Such mixtures are primarily used for sheathing cables or electrical wires. For example, EP 2 343 334 A2 describes flame-retardant compositions made of EVA, EPDM, and LLDPE that are crosslinked using a peroxide crosslinking system based on dicumyl peroxide. Peroxides are often used as crosslinking agents when rubbers that do not contain double bonds are to be crosslinked and / or when a particularly high crosslinking density and tight network structure are to be achieved, which in turn positively influences mechanical properties such as compression set, especially at elevated temperatures. On the other hand, the usually high crosslinking density and the short crosslinking bridges result in lower elongation at break compared to materials of the same hardness.If the product surfaces are no longer processed, peroxide crosslinking requires the exclusion of atmospheric oxygen during the crosslinking process. Furthermore, peroxide crosslinking systems have a detrimental effect on the elastic and dynamic properties, especially if the composition also contains large amounts of flame retardants. Finally, periodic crosslinkers also have the disadvantage of being comparatively expensive, especially compared to sulfur as a crosslinking agent.

[0008] To solve these problems, EP 2 880 093 proposes blends of elastomers containing double bonds, such as EPDM, and vinyl acetate-containing thermoplastic polymers, such as EVA, which are vulcanized exclusively with a sulfur or sulfur-containing crosslinking system. The sulfur crosslinker is intended to ensure that only the elastomer containing double bonds participates in the crosslinking process, resulting in a material with high elongation at break.

[0009] In structural fire protection, the primary goal is to prevent the passage of smoke and heat from one room to the next, or from different building areas to adjacent areas, due to a fire. Obviously, the sealing of wall or ceiling openings between adjacent rooms or building areas is important for fire protection. Of particular importance here are openings for electrical cables and pipes, or ventilation flaps.

[0010] Conventional elastomer materials that can be used for sealing purposes often use sulfur crosslinkers, which are said to enable advantageous dynamic properties and good fillability with flame retardants. As an example, reference can be made to the aforementioned EP 2 880 093 B1. However, these materials do not exhibit optimal properties with regard to their glass transition temperature. This temperature affects the potential service temperature of the material, which becomes inflexible below the glass transition temperature and can no longer provide the desired elastomeric properties. Against this background, a material for the production of molded articles for structural fire protection that has the lowest possible glass transition temperature in the vulcanized state would be desirable in order to broaden the temperature range that can be covered by such a component.In other areas of application, the material should offer properties as equivalent as possible to conventional materials based on elastomers containing double bonds and vinyl acetate-containing thermoplastic polymers. A low glass transition temperature would be particularly advantageous in applications in areas and regions of the world where ambient temperatures can drop to -40°C or below, such as pipeline systems in Siberia or the Arctic.

[0011] Against this background, there was a need for elastomer mixtures for the production of molded articles for structural fire protection and corresponding molded articles that exhibit mechanical properties as similar as possible to those of commercially available products, but which have lower glass transition temperatures compared to these, thus covering a broader service temperature range. The present invention addresses this need. Detailed description

[0012] In the investigations underlying the present application, it was surprisingly found that improved properties with respect to the glass transition temperature and advantageous elastic and mechanical properties can be obtained when moldings are produced from a composition comprising an elastomer containing double bonds and a vinyl acetate-containing thermoplastic polymer, and this composition is crosslinked with a mixture of a peroxidic and a sulfur- or sulfur-containing crosslinker. A small amount of peroxidic crosslinker is sufficient to achieve a noticeably reduced glass transition temperature, so that the peroxidic crosslinker can be used in a substoichiometric amount compared to the sulfur- or sulfur-containing crosslinker.Due to the reduced glass transition temperature of the crosslinked molded body, a broadening of the temperature window in which the molded body with elastomeric properties can be used can be achieved.

[0013] According to a first aspect, the present invention accordingly relates to a molded part for structural fire protection, which can be produced or is produced by vulcanizing a flame-retardant elastomer composition, wherein the elastomer composition contains i) an elastomer containing double bonds, and ii) a vinyl acetate-containing thermoplastic polymer as polymeric components, wherein the polymeric components are present as a homogeneous polymer mixture, a crosslinker system comprising a sulfur- or sulfur-containing crosslinker and a peroxidic crosslinker, wherein the proportion of the peroxidic crosslinker is lower than that of the sulfur- or sulfur-containing crosslinker, and a flame retardant or a combination of flame retardants.

[0014] The term "molded part for structural fire protection" refers to molded parts used in applications where the spread of a fire or gases, such as combustion gases, from one room to an adjacent room or from different building areas to adjoining areas is to be prevented or at least slowed. Such molded parts are usually designed so that they can be inserted into wall openings between rooms or building areas with a form-fitting fit, whereby the openings can have a round, rectangular, or square cross-section. In contrast, cable insulation, for example, which is primarily intended to prevent the insulation itself from burning, is not considered molded parts for structural fire protection within the meaning of the invention described here.Moulded parts for structural fire protection generally have dimensions that are based on the dimensions of the opening in which they are used, i.e. they have a length that is equal to or greater than the thickness of the wall, but not significantly greater (for example, not more than five times and preferably not more than twice the wall thickness).

[0015] In the context described here, the term "building areas" covers areas of stationary, immovable structures ("buildings"), including technical and industrial installations in the onshore and offshore sectors, wind turbines and solar power plants, and also movable structures, such as ships in particular, which have areas or units that must be separated from one another for the purpose of fire protection in order to prevent gas exchange.

[0016] The specification "for structural fire protection" does not preclude the molded part from fulfilling additional functions, such as sealing against the penetration of gases, water, sound (to improve acoustics), or pathogens such as aerosols containing bacteria, mold, or their spores. The assumption of such functions is expressly desired and preferred for the molded parts according to the invention.

[0017] The use of peroxide crosslinker in only a small proportion has the advantage that the costs of the crosslinker system can be minimized.

[0018] The double-bond-containing elastomer is preferably a homopolymer, copolymer, or terpolymer made of or containing diene monomer units. A terpolymer consisting of ethylene, propylene, and a diene-containing termonomer is particularly suitable, preferably with a termonomer content of at least 2% to 12% by weight, based on the terpolymer.

[0019] It is particularly advantageous if the elastomer containing double bonds is a rubber with an unsaturated side group, especially an ethylene-propylene-diene rubber (EPDM). Ethylene-propylene-diene monomer rubbers (EPDM) offer significant advantages in the event of a fire due to their low smoke density and toxicity, but are not themselves fire-resistant. On the other hand, EPDM rubbers can be highly filled with fillers and plasticizers and can thus absorb a high proportion of flame retardants in solid and liquid form. The hardness and mechanical properties of EPDM rubbers can thus be adjusted over a wide range, and the rubbers offer advantages in terms of weather, UV, ozone, and heat resistance.

[0020] EPDM rubbers which are particularly suitable for use in the flame-retardant elastomer composition from which the shaped body according to the invention is formed contain non-conjugated diene monomer units selected from the group comprising 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-cyclopentadiene, dicyclopentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,4-hexadiene, 1,4-cyclohexadiene, tetrahydroindene, methyltetrahydroindene, ethylidenenorbornene or 5-ethylidene-2-norbornene (ENB), 5-methylene-2-norbornene (MNB), 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, 5-isopropylidene-2-norbornene, and 5-vinylnorbornene. It is particularly advantageous if the ethylene-propylene-diene monomer rubber (EPDM) is a terpolymer of ethylene, propylene, and 5-ethylidene-2-norbornene (ENB) or dicyclopentadiene (DCPD), preferably with a termonomer content of at least 2 to 12 wt.% and in particular 4 to 12 wt.%.-% based on the terpolymer (according to ASTM D 6047). The most preferred diene component of EPDM rubber is 5-ethylidene-2-norbornene (ENB).

[0021] In the investigations underlying the present invention, it was also found that particularly favorable properties can be achieved if the EPDM is formed from a mixture of two EPDM types, one of which has a diene content in the range of 8 to 12 wt.% and the other a diene content in the range of 4 to 7 wt.%. In this case, further EPDM types can also be included, but these are then preferably contained in an amount of no more than 5 wt.% and in particular no more than 2 wt.% based on the total amount of EPDM with high and low diene content in the mixture. In a mixture, the EPDM with a diene content in the range of 8 to 12 wt.% preferably makes up the predominant proportion of the EPDM (i.e. 50 to 95 wt.% and preferably 60 to 80 wt.% of the total EPDM in the mixture).

[0022] The thermoplastic vinyl acetate-containing polymer to be included in the elastomer composition from which the molded article according to the invention is formed is preferably a homopolymer, copolymer, or terpolymer of vinyl acetate, and particularly preferably polyvinyl acetate (PVAc) or ethylene-vinyl acetate (EVA). For an ethylene-vinyl acetate copolymer, it is preferred if it has a vinyl acetate content in the range of 40 to 75 wt.% and in particular in the range of 50 to 65 wt.%.

[0023] Alternatively or additionally, it is preferred if the vinyl acetate-containing polymer has a melting temperature or a start of the melting range of less than 150 °C, preferably less than 100 °C.

[0024] The ratio of the polymeric components i) and ii) in the elastomer composition according to the invention is preferably in the range from 5:1 to 20:1 and in particular 6:1 to 12:1, ie the elastomer containing double bonds is present in excess compared to the vinyl acetate-containing thermoplastic polymer.

[0025] All peroxidic crosslinkers known to the person skilled in the art are suitable as peroxidic crosslinkers in the crosslinking system of the present invention. Dialkyl peroxides and ketal peroxides are particularly suitable for use. Suitable dialkyl peroxides include, for example, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-(3), alpha,alpha'-bis(t-butylperoxy)diisopropylbenzene, di-t-amyl peroxide, 1,3,5-tris(2-t-butylperoxyisopropyl)benzene, and 1-phenyl-1-t-butylperoxyphthalide. Suitable ketal peroxides include 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2'-bis(t-butylperoxy)butane, ethyl 3,3-bis(t-butylperoxy)butyrate, and n-butyl 4,4-bis(t-butylperoxy)valerate. Particularly preferred in the context of the present invention is the use of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane.

[0026] The proportion of the peroxidic crosslinker, based on the polymer mixture, is preferably 0.2 to 1.5 phr and preferably 0.5 to 1.2 phr, where "phr" refers to the total amount of double bond-containing elastomer and vinyl acetate-containing thermoplastic polymer contained in the polymer mixture.

[0027] As a sulfur crosslinker, sulfur (e.g. in the form of ground sulfur) or a sulfur-containing crosslinker such as bis[3-(triethoxysilyl)propyl]polysulfide or a mixture thereof can be used in the elastomer compositions according to the invention.

[0028] The proportion of the sulfur or sulfur-containing crosslinker, based on the polymer mixture, is preferably in the range from 1 to 7 phr, in particular 2 to 5 phr and particularly preferably 2.8 to 4.0 phr.

[0029] For the purpose of the present invention, it is essential that the sulfur- or sulfur-containing crosslinker be present in excess of the peroxidic crosslinker, with an excess indicating a higher weight fraction of the total amount of sulfur- or sulfur-containing crosslinker compared to the peroxidic crosslinker. Preferably, the peroxidic crosslinker and the sulfur- or sulfur-containing crosslinker are present in a ratio of approximately 1:1.5 to 1:5, in particular 1:2 to 1:4, and particularly preferably 1:2.5 to 1:3.8.

[0030] The flame retardant to be incorporated into the molded parts according to the invention is not subject to any relevant restrictions, so that the flame retardant can be, for example, an expandable flame retardant (such as expandable graphite) or a water-releasing flame retardant, such as a metal hydroxide. To achieve good fire protection properties with the least possible impact on the material properties, it has proven advantageous if magnesium hydroxide (MDH), aluminum hydroxide (ATH), antimony trioxide, nanoclays and / or zinc borate, preferably a synergistic mixture of two or more thereof, are incorporated into the elastomer composition according to the invention. The elastomer composition according to the invention preferably contains aluminum hydroxide, either alone or in a mixture with other flame retardants. In particular, the flame retardant(s) is / are solid and powdery or crystalline.

[0031] In most cases, the flame retardant is present in a comparatively large proportion in the elastomer composition. The elastomer composition preferably contains a proportion of 100 to 300 phr, and in particular 140 to 250 phr of flame retardant. If the proportion is below this, sufficient flame-retardant effectiveness may no longer be guaranteed in individual cases, while a higher proportion of flame retardant can have a significantly adverse effect on mechanical properties, such as tensile strength, elongation at break, tear resistance, or elasticity.

[0032] In addition to the components mentioned above, the elastomer composition for producing the molded articles according to the invention may contain further additives and / or auxiliaries in order to control the final properties of the molded article in a desirable manner.

[0033] An important class of such additives that can be used to control vulcanization or crosslinking are accelerators, each of which can specifically accelerate sulfur crosslinking or peroxide crosslinking. Commonly used accelerators for sulfur crosslinking include sulfenamides, e.g., N-cyclohexyl-2-benzothiazylsulfenamide (CBS), thiazoles, e.g., 2-mercaptobenzothiazole (MBT), dithiocarbamates, e.g., zinc dibenzyldithiocarbamate (ZBEC) or zinc dibutyldithiocarbamate (ZDBC), guanidines, e.g., diphenylguanidine (DPG), or thiophosphates. Suitable sulfur donors that can be added to control sulfur crosslinking include thiurams such as tetramethylthiuram disulfide (TMDT) or tetramethylthiurammone sulphide (TMTM), caprolactam disulfide, or phosphoryl polysulfide. Such accelerators and sulfur donors can be advantageously included in the elastomer composition according to the invention in a total amount of 1 to 5 phr.

[0034] Antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) or 1,3-dihydro-4(or 5)-methyl-2H-benzimidazole-2-thione can be used to support peroxide crosslinking. Such antioxidants and sulfur donors can be included in the elastomer composition at a total concentration of 1 to 5 phr.

[0035] In addition, the elastomer compositions can contain plasticizers, e.g. in the form of paraffinic mineral oils, or processing aids, e.g. in the form of Ca and Zn soaps of fatty acids, fatty alcohols or low molecular weight polyethylene or polyethylene glycol. Furthermore, additives such as ZnO or MgO can be added to improve heat stability, and / or pigments for coloring or to provide UV protection, such as TiO 2 , UV stabilizers or carbon black, can be added. The proportion of plasticizers is preferably in the range of 5 to 50 phr, in particular 10 to 30 phr and more preferably 12 to 25 phr. Other auxiliaries and additives are expediently present in the flame-retardant elastomer composition at a maximum proportion of 20 phr and in particular 15 phr.

[0036] As a particularly suitable flame-retardant elastomer composition in the context of the present invention for producing molded articles according to the invention, a composition as follows can be given: A mixture of an elastomer containing double bonds and a thermoplastic polymer containing vinyl acetate; 130 to 250 phr of flame retardant, preferably in the form of aluminum hydroxide; 10 to 30 phr of plasticizer; 1 to 5 phr each of sulfur donor / sulfur vulcanization accelerator and antioxidants; 5 to 30 phr, and preferably 8 to 15 phr of further additives and auxiliaries; a crosslinker system comprising a sulfur- or sulfur-containing crosslinker and a peroxidic crosslinker, wherein the proportion of the peroxidic crosslinker is lower than that of the sulfur- or sulfur-containing crosslinker.

[0037] For use in fire protection purposes, it is preferred that the molded articles according to the invention produced from the flame-retardant elastomer composition contain no relevant amounts of halogens, since toxic hydrogen halides can be released from halogen-containing compounds in the event of a fire. For the molded articles according to the invention, it is therefore preferred that the polymeric components of the elastomer composition, and preferably the entire composition, are / are halogen-free.

[0038] The molded body according to the invention can be formed exclusively from the flame-retardant elastomer mixture or can comprise additional components, e.g., reinforcing agents. In one embodiment, the surface of the molded body is formed exclusively from the flame-retardant elastomer mixture, while a different material is present in the interior of the molded body.

[0039] As already mentioned, the molded parts according to the invention are molded parts that can be used in structural fire protection, and their dimensions are usually tailored to the wall thicknesses in which the molded part is intended to be used. It is preferred if the molded part according to the invention has an aspect ratio of at most 10, and particularly preferably at most 5. The "aspect ratio" here refers to the ratio of the largest to the smallest spatial dimension of the molded part.

[0040] In a particularly preferred embodiment, the molded part according to the invention comprises ventilation flaps or components thereof. In another particularly preferred embodiment, the molded part according to the invention is a device for the fire-protected passage of lines, cables, pipes, and the like through openings in walls or shafts formed with at least one rectangular support frame. In this case, the device comprises one or more packages with channels made of the flame-retardant elastomer composition extending across the depth of the rectangular support frame, which can be inserted into the rectangular support frame.

[0041] For clarification, it should be noted that the molded part according to the invention refers to the device as a whole, which may, however, be formed from several individual parts (in particular, several packages and, if appropriate, additional components). The rectangular support frame is not part of the device.

[0042] In a preferred embodiment, the device comprises at least one unit of two packages formed from two symmetrically formed sealing elements, wherein the sealing elements have one or more approximately semi-cylindrical recesses and are arranged one upon another to form one or more cylindrical recesses. In this case, the device can expediently comprise two semi-cylindrical inserts, each formed with semi-cylindrical recesses, and arranged relative to one another such that the recesses form a channel adapted for the introduction of a line.

[0043] The device can contain exactly two packages (= a pair), or a multiple of two packages, which can be inserted into the rectangular support frame (for example, in pair arrangements of 2 x 2, 3 x 2, 4 x 2, or 4 x 4). In the case of an odd number of pairs of packages, the space remaining free with respect to the rectangular support frame can be filled by a molded body whose dimensions are precisely matched to the remaining space (as a "filling module"). Such a filling module is also expediently formed from a flame-retardant elastomer composition as described above. Likewise, a plurality of such filling modules can be arranged in the rectangular support frame, which, in combination with the packages, form the device.

[0044] For the device described above, it is further preferred if the wall defining the recess in the sealing elements is formed with semi-annular ribs and, between these, with semi-annular grooves. Some of these grooves can be formed with depressions, which preferably extend only over part of the semi-annular wall. For this embodiment, it is further preferred if the semi-cylindrical inserts are provided with projections corresponding to the grooves and depressions in the walls defining the sealing elements, which engage in the grooves and depressions in such a way that the inserts can neither be displaced in the direction of the formed channel nor rotated about this channel when the inserts are arranged in the sealing elements. In this way, displacement or rotation of inserts inserted in the sealing elements is prevented.Such sealing elements are described in detail, for example, in EP 1 134 472 B1, the relevant content of which is hereby incorporated in this application by reference.

[0045] If the device has semi-cylindrical inserts, the device can further comprise molded body components whose dimensions are adapted to the dimensions of the channel formed by the semi-cylindrical inserts and which can be inserted into the semi-cylindrical inserts as placeholders for later filling the channels with cables. These placeholders preferably also have projections that can engage in corresponding recesses in the semi-cylindrical inserts and fix the position of the placeholder in the inserts. Placeholders are preferably also formed from a flame-retardant elastomer composition as described above.

[0046] The devices described above are in the Figures 1 to 5 illustrated in more detail. They show: Figure 1: a package with two sealing elements in front view Figure 2: a sealing element in top view Figure 3: a sealing element in longitudinal section Figure 4: an insert in top view Figure 5: an insert in side view

[0047] The Figure 1The cuboid package 1 shown consists of two symmetrically formed sealing elements 11, each formed with an approximately semi-cylindrical recess and serving to accommodate semi-cylindrical inserts 21, which are also formed with semi-cylindrical recesses. A line 3 can be inserted into the passage channel thus formed. The sealing elements 11 and the inserts 21 located therein must be designed such that they tightly enclose the line 3 in order to ensure the desired safety against the passage of fire gases.

[0048] In Figures 2 and 3 a plan view and a longitudinal section of a sealing element 11 is shown, which has ribs 12 and grooves 13, as well as additional recesses 14, which, in contrast to the grooves 13, do not extend over the entire semicircular inner surface of the sealing element.

[0049] In Figures 4 and 5 an insert 21 is shown in top and side view, which has grooves 22 and ribs 23, as well as projections 24. In Figure 5 Additionally, semi-annular ribs 25 and semi-annular grooves 26 located between them are shown on the inner wall of the inserts. The ribs can compensate for differences in the thickness of an inserted cable to a certain extent, which can be pushed away by the ribs due to their flexibility. When inserting an insert into a sealing element, the ribs 23 and projections 24 engage in corresponding grooves 13 and recesses 14 in the sealing element.

[0050] In a further aspect, the present invention relates to the use of molded parts, as described in detail above, for structural fire protection applications. The molded parts are preferably inserted into a wall opening or a wall penetration between two rooms and seal this opening in the contact area between the molded part and the wall. In such a use, pipes or other lines can be integrated or embedded into the molded part.

[0051] In a further aspect, the present invention relates to a process for producing the above-described shaped bodies, wherein the process comprises the steps a) mixing the above-mentioned polymeric components to form a homogeneous mixture and, in particular, subsequent incorporation of the crosslinking system, the flame retardants and optionally further additives and / or auxiliaries while avoiding crosslinking and / or vulcanization, and b) introducing the mixture into a mold, c) subsequent vulcanization of the mixture, and d) demolding of the molded body formed in c).

[0052] Mixing is preferably carried out under conditions where no crosslinking or vulcanization occurs, i.e., preferably at a maximum temperature of 110°C. Subsequent vulcanization can be carried out at elevated temperatures, e.g., in the range of 130°C to 200°C, and especially 130°C to 170°C, and optionally under pressure. During vulcanization, crosslinking of the polymer components occurs as a result of the activation of the crosslinking agents.

[0053] The elastomer composition used to produce the molded articles according to the invention preferably has at least one of the following properties after vulcanization: i) a glass transition temperature, determined by DSC, of at most -39 °C, in particular at most -40 °C, and particularly preferably at most -41 °C; ii) a set value, determined according to DIN ISO 815 at 70°C / 24 h, in the range of 10 to 40% and preferably 15 to 25% and / or a set determined according to DIN ISO 815 at 100°C / 24 h, in the range of 45 to 75% and preferably 55 to 68%; iii) a Shore A hardness, determined according to DIN ISO 7619-1 (2012) of 65 to 85, preferably 70 to 83; iv) an elongation at break, determined according to DIN 53504, of 200 to 600%, preferably 300 to 500%; v) a tear resistance, determined according to DIN ISO 34-1 A, of > 2.5 N / mm, preferably > 3.5 N / mm.

[0054] Yet another aspect of the present invention relates to the use of a molded part as described above for applications with a minimum permissible service temperature of -40°C or less. Preferred uses of this type include, for example, wall or ceiling penetrations in buildings, technical and industrial facilities onshore and offshore, wind turbines and solar power plants, and ships or the like for pipes and cables, particularly when located in areas and regions of the world where very low outside temperatures in the range of -40°C can occur.

[0055] A further aspect of the present invention relates to the use of a molded part as described above for sealing buildings against water, gas, sound, or pathogens, in particular in the form of bacteria or mold.

[0056] For these aspects, the preferred embodiments explained in connection with the molded parts according to the invention are analogously considered preferred, unless this results in a contradiction.

[0057] In the following, the present application is illustrated in more detail using some embodiments, which, however, are not to be regarded in any way as limiting the scope of protection of the application. Examples

[0058] The composition listed in Table 1 below was homogenized in a mixer and then vulcanized at 180°C for 10 minutes (2 mm thick sheets) or 20 minutes (6 mm thick sheets) under a nitrogen atmosphere. The mechanical properties of the sheets were then determined. To determine the glass transition temperature, the mixture was first equilibrated at -120°C for 15 minutes and then heated to 250°C at a heating rate of 10 K / min. The glass transition temperature was determined as the midpoint Tg according to DIN 51007. The determined mechanical properties are also listed in Table 1 below. Table 1 component E1 V1 EPDM with diene content of about 11% 74 74 EPDM with diene content of about 5% 16 16 EVM with about 60% vinyl acetate 10 10 aluminum hydroxide 180 phr 180 phr Sulfur crosslinkers 3.4 phr 3.4 phr Peroxide crosslinkers 1 phr - Mineral oil (plasticizer) 15 phr 15 phr Antioxidants 2.4 phr 2.4 phr Accelerator / sulfur donor 2.8 phr 2.8 phr ZnO 3.8 phr 3.8 phr Compression set 22h 70°C 1< 21% 43% Compression set 22h 100°C 1< 61% 75% Glass transition temperature [°C] 2< -41,2 -38,8 Elongation at break [%] 3< 430% 360% Tensile strength [MPa] 3< 4,9 4,6 Tear resistance [N / mm] 4< 3,5 4,5 * Average of 2 measurements (in N2); 1: determined according to DIN ISO 815; 2: determined according to DSC; 3: determined according to DIN 53504; 4: determined according to DIN ISO 34-1 A.

[0059] Table 1 shows that, despite otherwise comparable mechanical properties, a reduction in the glass transition temperature of approximately 2.6 °C was observed when crosslinking with sulfur and peroxide accelerators. This change allows the use of corresponding elastomer formulations for applications with very low extreme temperatures.

[0060] In an analogous measurement of the glass transition temperature in air atmosphere, a Tg of -41.5 °C was determined for E1 and a Tg of -39.1 °C for V1 (average of 2 measurements).

Claims

1. A molded part for structural fire protection, which can be manufactured or is manufactured by vulcanizing a flame-retardant elastomer composition comprising: - a double bond-containing elastomer, and - a vinyl acetate-containing thermoplastic polymer as polymeric components, wherein the polymeric components are present as a homogeneous polymer mixture, - a crosslinker system consisting of a sulfur crosslinker or sulfur-containing crosslinker and a peroxide crosslinker, wherein the proportion of peroxide crosslinker is less than that of sulfur crosslinker or sulfur-containing crosslinker, and - a flame retardant or a combination of flame retardants.

2. The molded part according to claim 1, characterized in that the peroxide crosslinker is contained in the polymer mixture of the flame-retardant elastomer composition in a proportion of 0.2 to 1.5 phr, and preferably 0.5 to 1.2 phr.

3. The molded part according to claim 1 or claim 2, characterized in that the sulfur crosslinker or sulfur-containing crosslinker is contained in the polymer mixture of the flame--retardant elastomer composition in a proportion of 1 to 7 phr, preferably 2 to 5 phr, and particularly preferably 2.8 to 4.0 phr.

4. The molded part according to at least one of claims 1 to 3, characterized in that the double bond-containing elastomer in the flame-retardant elastomer composition is a homopolymer, copolymer or terpolymer consisting of or comprising diene monomer units, in particular a terpolymer consisting of ethylene, propylene and a diene-containing termonomer, preferably having a termonomer content of at least 2 to 12% by weight, based on the terpolymer.

5. The molded part according to at least one of the preceding claims, characterized in that the double bond-containing elastomer in the flame-retardant elastomer composition is a rubber having an unsaturated pendant group, in particular an ethylene-propylene-diene rubber (EPDM), preferably comprising non-conjugated, diene monomer units selected from the group consisting of 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-cyclopentadiene, dicyclopentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,4-hexadiene, 1,4-cyclohexadiene, tetrahydroindene, methyl tetrahydroindene, ethylidene norbornene, respectively 5-ethylidene-2-norbornene (ENB), 5-methylene-2-norbornene (MNB), 1,6 octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, 5-iso-propylidene-2-norbornene, 5-vinyl-2-norbornene (VNB), the ethylene-propylene-diene rubber (EPDM) preferably being a terpolymer consisting of ethylene, propylene and 5-ethylidene-2-norbornene (ENB) or dicyclopentadiene (DCPD).

6. The molded part according to at least one of the preceding claims, characterized in that vinyl acetate-containing polymer in the flame-retardant elastomer composition is a homopolymer, copolymer or terpolymer of vinyl acetate, and in particular is selected from the group of consisting of polyvinyl acetate (PVAc) or ethylene vinyl acetate (EVA), and / or in that the vinyl acetate-containing polymer has a melting temperature or onset of the melting range of less than 150°C, preferably less than 100°C, and / or in that the vinyl acetate-containing polymer has a vinyl acetate content of 40 to 75% by weight.

7. The molded part according to at least one of the preceding claims, characterized in that the polymeric components in the flame-retardant elastomer composition are contained in the elastomer composition in a ratio of 5:1 to 20:1, and in particular from 6:1 to 12:1.

8. The molded part according to at least one of the preceding claims, characterized in that the peroxide crosslinker in the flame-retardant elastomer composition is present in the composition in the form of dialkyl peroxides, in particular selected from the group comprising dicumyl peroxide, di-t-butyl peroxide, t-butyl-cumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)-hexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)-hexine-(3), alpha, alpha'-bis(t-butylperoxy)-diisopropylbenzene, di-t-amyl peroxide, 1,3,5-tris(2-t-butylperoxy-isopropyl)benzene, 1-phenyl-1-t-butylperoxy-phthalide, and / or ketal peroxides, especially selected from the group comprising 1,1-bis(t-butylperoxy)-3,3,5-trimethyl-cyclohexane, 1,1-bis(t-butylperoxy)-cyclohexane, 2,2'-bis(t-butylperoxy)-butane, ethyl-3,3-bis(t-butylperoxy)-butyrate, n-butyl-4,4-bis(t-butylperoxy)-valerate.

9. The molded part according to at least one of the preceding claims, characterized in that the flame-retardant in the flame-retardant elastomer composition is selected from the group comprising metal hydroxides, in particular in the form of magnesium and / or aluminum hydroxide, and zinc borate, and is preferably present as aluminum hydroxide.

10. The molded part according to at least one of the preceding claims, characterized in that the flame retardant in the flame-retardant elastomer composition is contained in the elastomer composition in a proportion of 100 to 300 phr, in particular 140 to 250 phr.

11. The molded part according to at least one of the preceding claims, characterized in that the flame-retardant elastomer composition further contains at least one additive and / or auxiliary selected from the group comprising colorants, in particular in the form of one or more pigments, plasticizers, in particular based on mineral oil, anti-aging agents, in particular for improving heat stability, and crosslinking accelerators.

12. The molded part according to at least one of the preceding claims, characterized in that the polymeric components of the flame-retardant elastomer composition, in particular the entire composition, is / are halogen-free.

13. The molded part according to at least one of the preceding claims, characterized in that the vulcanized flame-retardant elastomer composition forming the molded part has a Shore A hardness, determined according to DIN ISO 7619-1 (2012), in the range of 65 to 85 and in particular 70 to 83 and / or a glass transition temperature of at most -39°C and in particular at most -41°C.

14. The molded part according to at least one of the preceding claims, characterized by an aspect ratio of at most 10 and preferably at most 5.

15. The molded part according to at least one of the preceding claims, characterized in that it is designed as a device for the fire-proof passage of conduits, cables, tubes and the like through openings located in walls or shafts, the openings having at least one rectangular supporting frame, the device comprising one or more packing pieces (1) having channels consisting of an elastic material, the channels extending over the depth of the rectangular supporting frame, which packing pieces can be inserted into the rectangular supporting frame.

16. The molded part according to claim 15, characterized in that the device includes a plurality of packing pieces (1) formed from two symmetrically formed sealing elements (11), the sealing elements (11) comprising an approximately semi-cylindrical cavity and being arranged one on top of another in such a manner that a cylindrical cavity is formed, the device preferably further comprising two semi-cylindrical inserts (21) which are likewise formed so as to comprise semi-cylindrical cavities, so that the recesses form a channel adapted for the insertion of a conduit.

17. The molded part according to claim 16, characterized in that the wall delimiting the recess in the sealing elements (11) is formed so as to have semi-annular ribs (12) and semi-annular grooves (13) therebetween, of which some of the grooves may be formed so as to have recesses (14) which preferably extend only over part of the semi-annular wall.

18. The molded part according to claim 17, characterized in that the semi-cylindrical inserts (21) are provided with ribs (23), projections (24) corresponding to the grooves (13), and recesses (14) of the walls delimiting the sealing elements (11), which engage in the grooves (13) and recesses (14) in such a manner that the inserts can neither be displaced in the direction of the formed channel nor rotated around this channel when the inserts (21) are arranged in the sealing elements (11).

19. A method of manufacturing a molded body according to any of claims 1 to 18, comprising the steps of: - mixing the polymeric components, as indicated in claim 1, to form a homogeneous mixture and, in particular subsequently, incorporating the crosslinking system, the flame retardants and optionally further additives and / or auxiliaries while avoiding crosslinking and / or vulcanization, and - introducing said mixture into a molding tool, - subsequently vulcanizing the mixture, and - demolding the molded body formed in c).

20. A use of a molded part according to at least one of claims 1 to 18 for applications having a minimum permitted use temperature of -40°C or less, in particular for wall or ceiling breakthroughs in buildings, technical and industrial installations in the onshore and offshore sector, wind power and solar installations and ships, preferably for gas pipes.