ARTICLES, IN PARTICULAR AN AIR BELLOW, A METAL-RUBBER ELEMENT OR A VIBRATION DAMPER

Description

[0001] The invention relates to an article having a base body with elastic properties, in particular an air spring bellows, a metal-rubber element or a vibration damper.

[0002] Articles with elastic properties, such as those used for suspension in motor vehicles or rail vehicles and / or for vibration damping, are manufactured using elastomeric compounds, also known as rubber compounds. These elastomeric compounds, commonly used for the basic properties of such articles, are well known. Articles with outstanding elastic properties, such as metal-rubber elements or vibration dampers, preferably contain vulcanized rubber compounds based predominantly on natural rubber (NR) and / or polyisoprene rubber (IR). Articles with very good weather, mineral oil, and heat resistance, such as air spring bellows, preferably contain vulcanized rubber compounds based predominantly on chloroprene rubber (CR).

[0003] However, products made with these elastomeric compounds exhibit significant disadvantages in their fire behavior. In the event of a fire, dense smoke gases are produced, among other things. During the combustion process of these elastomeric compounds, which are predominantly based on NR and / or IR, the heat release rate is particularly high. During the combustion process of elastomeric compounds, which are predominantly based on CR, the resulting smoke gas is toxic to humans and animals.

[0004] Due to the increased fire protection requirements in recent years, which are reflected primarily in the more stringent fire protection standard EN 45545, there is an increased demand for fire-protection-optimized polymer articles. These fire protection requirements can no longer be met by either the aforementioned elastomer compounds, which are predominantly based on NR and / or IR, primarily due to the required maximum heat release rate, or by the flame-retardant elastomer compounds, which are predominantly based on CR, particularly due to the required smoke toxicity. Therefore, articles containing these elastomer compounds alone generally no longer meet the more stringent requirements.

[0005] A common method for improving the fire behavior of rubber compounds is the direct incorporation of flame-retardant substances. However, this measure typically results in a significant deterioration of the physical properties of the affected articles, particularly their resilience, settling, and vibration properties.

[0006] Even fire-resistant coatings, such as those described in WO 2014 / 019008 A1 or EP 2196492 B1, are only partially suitable for ensuring long-term fire protection on articles. Firstly, they exhibit low tensile strength, which negatively impacts durability; secondly, these coatings detach from the article relatively quickly, particularly under dynamic loads. The potentially necessary second vulcanization process during the manufacture of the final products, particularly during the production of injection-molded articles such as metal-rubber elements, reduces the tear resistance of the base compound due to the common tendency to reversion, particularly in BR-based compounds.

[0007] Furthermore, the fire protection coatings described in WO 2014 / 019008 A1 exhibit insufficient DV values, particularly at higher temperatures (>70°C). At the same time, the fire protection layer must be comparatively thick to ensure adequate fire protection. The fire protection measure described in EP 2196492 B1, on the other hand, exhibits a delayed onset of the fire protection effect due to the comparatively high onset temperature of the expanded graphite used there.

[0008] DE 102009044533 A1 discloses an air spring bellows with a fabric layer embedded in elastomer layers.

[0009] The object of the invention is to provide an article characterized by optimized fire protection behavior in order to meet the more stringent requirements, in particular those described in EN 45545. At the same time, the necessary physical properties of the article should remain at a comparable level and the complexity of the manufacturing process should not be significantly increased.

[0010] This object is achieved in that the article has a single- or multi-layer elastic base body, wherein the outer layer C consists of at least a first layer C1 and a further layer C2 and each layer is formed from an elastomer mixture and wherein at least one layer D made of a woven or knitted fabric or knitted fabric is embedded in this outer layer C between the first layer C1 and the further layer C2.

[0011] The following structures of the article are possible according to the invention: Variant 1:

[0012] In a preferred embodiment, the base body is formed in one layer, so that the layer D made of a woven or knitted fabric or knitted fabric is embedded in the single layer C, which is at least two-layered C1 / C2 and each layer is formed from an elastomer mixture.

[0013] The following layer structure results: C1, D, C2.

[0014] The individual layers are explained in more detail below. Variant 2:

[0015] In a particularly preferred embodiment, the base body is constructed in multiple layers. The first layer, A, is the so-called "inner cap," composed of an elastomer mixture. This is followed by a second layer, B, formed from at least one reinforcement. This is followed by the outer layer, C, which consists of at least two layers (C1 / C2), each of which is formed from an elastomer mixture into which at least one layer, D, of a woven or knitted fabric, is embedded.

[0016] The following layer structure results: A, B, C1, D, C2.

[0017] The individual layers are explained in more detail below. Variant 3:

[0018] In a particularly preferred embodiment, the base body is constructed of multiple layers. The first layer, A, is the so-called "inner cap," composed of an elastomer mixture. This is followed by a second layer, B, formed from at least one reinforcement member. This is followed by the outer layer, C, which consists of at least two layers (C1 / C2), each layer being formed from an elastomer mixture into which at least one layer, D, made of a woven or knitted fabric, is embedded. Additionally, a further layer, E, based on at least one thermoplastic, preferably in the form of a film, can be located on the layer, D, made of a woven or knitted fabric, which is embedded in the outer layer, C. The layer, D, made of a woven, knitted, or knitted fabric, and the layer, E, based on a thermoplastic, are thus both embedded in the outer layer.

[0019] The following layer structure results: A, B, C1, D, E, C2.

[0020] The individual layers are explained in more detail below. Variant 4:

[0021] In another particularly preferred embodiment, the base body is constructed of multiple layers. The first layer, A, is the so-called "inner cap," composed of an elastomer mixture. This is followed by a second layer, B, formed from at least one reinforcement. This is followed by the outer layer, C, which consists of at least two layers (C1 / C2), each layer being formed from an elastomer mixture into which at least one layer, D, made of a woven or knitted fabric, is embedded. Additionally, a layer, G, made of a woven, knitted, or knitted fabric, can be located on this outer layer, C.

[0022] The following layer structure results: A, B, C1, D, C2, G.

[0023] The individual layers are explained in more detail below. Variant 5:

[0024] In another particularly preferred embodiment, the base body is constructed in multiple layers. The first layer A is the so-called "inner cap," which is composed of an elastomer mixture. This is followed by a second layer B, which is formed from at least one reinforcement. This is followed by the outer layer C, which has at least two layers C1 / C2, each layer being formed from an elastomer mixture into which at least one layer D made of a woven or knitted fabric is embedded. On top of the layer D made of a woven or knitted fabric, which is embedded in the outer layer C, there is a further layer E based on at least one thermoplastic, preferably in the form of a film. The layer D made of a woven, knitted, or knitted fabric and the layer E based on a thermoplastic are thus both embedded in the outer layer C made of an elastomer mixture.In addition, this outer layer C may have a layer G made of a woven, knitted or knitted fabric.

[0025] The following layer structure results: A, B, C1, D, E, C2, G.

[0026] The individual layers are explained in more detail below.

[0027] Layers A, B and C form the basic body of the article, with layer C consisting of at least two layers C1 and C2. Layer A

[0028] The first layer A is the so-called "inner cap," which is made of an elastomer compound and possesses particularly good elastic properties. The elastomer compound is a vulcanizable, preferably thermoplastic-free, rubber compound containing at least one rubber component and other compounding ingredients.The following rubber components are particularly worth mentioning: ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), nitrile rubber (NBR), (partially) hydrogenated nitrile rubber (HNBR), fluororubber (FKM), chloroprene rubber (CR), natural rubber (NR), styrene-butadiene rubber (SBR), isoprene rubber (IR), butyl rubber (IIR), bromobutyl rubber (BIIR), chlorobutyl rubber (CIIR), brominated copolymer of isobutylene and paramethylstyrene (BIMS), butadiene rubber (BR), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), alkylated chlorosulfonated polyethylene (ACSM), polyepichlorohydrin (ECO), terpolymers of ECO with ethylene oxide and unsaturated monomers (ETER), Ethylene-vinyl acetate rubber (EVA), acrylate rubber (ACM), ethylene-acrylate rubber (AEM), silicone rubber (MQ, VMQ, PVMQ, FVMQ), fluorinated methylsilicone rubber (MFQ), perfluorinated propylene rubber (FFPM), perfluorocarbon rubber (FFKM), polyurethane (PU).

[0029] The aforementioned rubber types can be unblended. The use of blended rubber is also possible.

[0030] Which rubber type is preferred depends on the type of article. Typical blend ingredients include at least one crosslinker or a crosslinking system (crosslinking agent and accelerator). Additional blend ingredients are usually a filler and / or a processing aid and / or a plasticizer and / or an anti-aging agent, as well as optionally other additives (e.g., color pigments, reinforcing fibers).

[0031] In this regard, reference is made to the general state of rubber compounding technology. Layer B

[0032] The second layer B is formed from at least one reinforcement. This is preferably a cord fabric made up of one or more layers, preferably two layers, which exhibit good adhesion to layer A.

[0033] Layer B forms the so-called supporting framework. All known synthetic and natural materials can be used for layer B, either alone or in combination, i.e., as a hybrid fabric.

[0034] Synthetic materials include, in particular, synthetic polymers such as polyacrylonitrile, polypropylene, polyester, polyamide, polyurethane, polyphenylene sulfide, polyoxadiazole, aramids such as p-aramid, m-aramid, or co-poly para-aramid, polyimide, polyetherimide, polyetheretherketone, polyethylene-2,6-naphthalate, polyphenylene, polyphenylene oxide, polyphenylene sulfide, polyphenylene ether, polybenzoxazole, and polyvinyl alcohol. Natural materials can include rock wool, asbestos, cotton, flax, hemp, wool, or silk. Inorganic materials such as glass, ceramics, carbon, metals such as steel, or rocks such as basalt are also conceivable.

[0035] Preferably it is polyamide, in particular PA6.6, or polyester alone or in combination.

[0036] To achieve sufficient tackiness during the manufacturing process of the article, the cord fabric can be rubberized or friction-coated on one or both sides. For the rubberization, a composition can preferably be used that is quantitatively and / or qualitatively identical to the composition for layer C1 or quantitatively and / or qualitatively identical to the composition for layer A. This further reduces the complexity of the manufacturing process and creates a dynamically suitable adhesive bond. Layer C

[0037] Layer C forms the so-called "outer cap" of the article. Layer C is formed of at least two layers, with the inner part C1 and the outer part C2 of layer C each being formed from an elastomer mixture. The elastomer mixtures for layer C1 and layer A can be qualitatively and / or quantitatively identical or different from each other.

[0038] It is preferred if the elastomer mixtures for layer C1 and layer A are qualitatively and quantitatively identical. This is the easiest to implement in terms of production technology without unnecessary additional effort. The elastomer mixture of layer C1 is a vulcanizable, preferably thermoplastic-free, rubber mixture containing at least one rubber component and other mixture ingredients.The following rubber components are particularly worth mentioning: ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), nitrile rubber (NBR), (partially) hydrogenated nitrile rubber (HNBR), fluororubber (FKM), chloroprene rubber (CR), natural rubber (NR), styrene-butadiene rubber (SBR), isoprene rubber (IR), butyl rubber (IIR), bromobutyl rubber (BIIR), chlorobutyl rubber (CIIR), brominated copolymer of isobutylene and paramethylstyrene (BIMS), butadiene rubber (BR), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), alkylated chlorosulfonated polyethylene (ACSM), polyepichlorohydrin (ECO), terpolymers of ECO with ethylene oxide and unsaturated monomers (ETER), Ethylene-vinyl acetate rubber (EVA), acrylate rubber (ACM), ethylene-acrylate rubber (AEM), silicone rubber (MQ, VMQ, PVMQ, FVMQ), fluorinated methylsilicone rubber (MFQ), perfluorinated propylene rubber (FFPM), perfluorocarbon rubber (FFKM), polyurethane (PU).

[0039] The aforementioned rubber types can be unblended. The use of blended rubber is also possible.

[0040] Which rubber type is preferred depends on the type of article. Typical blend ingredients include at least one crosslinker or a crosslinking system (crosslinking agent and accelerator). Additional blend ingredients are usually a filler and / or a processing aid and / or a plasticizer and / or an anti-aging agent, as well as optionally other additives (e.g., color pigments, adhesion promoters, flame retardants, reinforcing fibers).

[0041] In this regard, reference is made to the general state of rubber compounding technology.

[0042] The elastomer mixture of layer C2 is at least one elastomer mixture with fire-retardant and / or self-extinguishing and / or flame-resistant properties. In principle, all elastomers already described above for layer C1 can be used. However, ECO, ETER, NR, CSM, CPE, CR, and / or silicone rubber are preferred elastomers, alone or in combination. The thickness of layer C2 is preferably selected to provide the article with sufficient fire protection. To further improve fire protection performance, the elastomer mixture for layer C1 and / or the elastomer mixture for layer C2 can contain metal particles, for example, aluminum in the form of aluminum flakes. This leads to a further reduction in layer thickness and thus to a thinner overall article. A coating based on at least one fluorine-containing elastomer is also conceivable to optimize dynamic performance.

[0043] Layer C2 can cover the article completely or partially. In this context, "partial" means that only certain, defined areas or sections of the article are covered with layer C2. In addition to additional blend ingredients, as already described for layer A and layer C1, the elastomer mixture of layer C2 can also contain other components that have a flame-retardant effect or at least reduce flammability. These can be flame retardants such as stannates such as zinc stannate or zinc hydroxystannate, hydroxides such as magnesium hydroxide or aluminum hydroxide, cyanurates such as melamine cyanurate, borates such as zinc borate, phosphorus-containing components such as resorcinol diphosphate or aromatic polyphosphates, nitrogen-containing components such as ammonium phosphate, carbonates such as calcium carbonate or magnesium carbonate, expandable graphite, or intumescent mixtures. Intumescent mixtures expand to form foams.They are used to protect flammable materials such as plastics or wood, as well as steel, which loses its strength at elevated temperatures, against the effects of heat and fire. Despite its health hazards, small amounts of antimony trioxide can also be used in combination with at least one of the flame retardants mentioned.

[0044] The flame retardants can be used individually or in combination. Particularly preferred for optimizing fire retardancy is the use of glass microspheres and / or hollow glass microspheres, which are preferably prepared for adhesion, and / or hollow plastic spheres with a flexible polymer shell and / or reflective substances, such as metal particles, particularly made of aluminum and / or brass. The glass microspheres and / or hollow glass microspheres melt in the event of a fire and form glassy, insulating layers. If the spheres are hollow spheres, preferably hollow glass microspheres, in a preferred variant, fire-retardant substances can be encapsulated within the hollow spheres themselves. These substances are released after the outer shell melts and then, in concentrated form, provide additional fire-retardant properties.

[0045] In particular, the hollow plastic spheres can be in an already expanded form and / or in an expandable form.

[0046] In a preferred embodiment, expandable hollow plastic spheres are used. A gas is encapsulated within these expandable hollow plastic spheres. When heat is applied, the gas pressure inside the shell increases, causing it to soften. The resulting increase in volume leads to an increase in the layer thickness, which provides a further insulating effect even before the actual fire.

[0047] Additionally, the glass microspheres and / or hollow glass microspheres and / or hollow plastic spheres can be coated with at least one metal, such as aluminum. This further increases the effectiveness of the thermal insulation. Layer D

[0048] Layer D consists of a woven or knitted fabric embedded in the outer layer C. Layer D is thus located between layers C1 and C2. This is preferably a woven or knitted fabric, with both sides being coated with at least one adhesion promoter, depending on the embodiment and application. The adhesion promoter can be resorcinol formaldehyde latex, a dinitrosobenzene-based solution, silane, or an adhesion promoter based on at least one rubber.

[0049] Both sides can be equipped with the same adhesion promoter or with different ones.

[0050] The fabric is a bi-stretch fabric with a high degree of elasticity in both the horizontal and vertical directions, i.e., in the warp and weft directions. The bi-stretch fabric has an extensibility of greater than 50%, preferably greater than 250%, in both the warp and weft directions.

[0051] To achieve stretchability in the various directions, a sufficient amount of elastane, preferably 5 to 50 wt.%, is present in both the warp and weft directions. Stretch in both directions can also be achieved through appropriate textile manufacturing technologies, such as applying as little tension as possible when winding the freshly woven textile web.

[0052] By using a bi-stretch fabric with the advantageous property of flexibility or extensibility in all directions, it is avoided that the elastomer mixture is, so to speak, pushed away during the embossing phase, i.e. the molding phase, during the vulcanization process.

[0053] For the bi-stretch fabric, a hybrid material made of cotton, polyamide or polyester and elastane is used, with a cotton-dominant side and a polyamide or polyester-dominant side.

[0054] With such a combination, a casing can be created from this woven, knitted, or warp-knitted fabric before the article is manufactured, according to the required article diameter, and the seams of this casing can be welded. In the event of smoke or fire, the cotton content delays the so-called "pop-out"—that is, the breakthrough of the lower, more flammable layers to the heat-exposed surface, possibly melting layer B due to the heat, since the cotton content itself cannot melt. This leads to significantly improved fire protection properties.

[0055] Particularly good fire protection properties are demonstrated when using a bi-stretch material based on aramid and elastane. Layer E

[0056] The further layer E is based on at least one thermoplastic and is preferably located on the side of layer D facing layer C2. Suitable thermoplastics are, for example, polyolefin, in particular polyethylene (PE), such as LD-PE, LLD-PE, UHMW-PE, or polypropylene (PP), polystyrene (PS), polyamide (PA), for example PA6 or PA6.6, polyester, for example PET, PEN or PBT. In a preferred embodiment, layer E is in the form of a film. The use of PE film has proven particularly suitable because it forms a particularly good adhesive bond, particularly with peroxide-curing elastomer mixtures, and thus additional adhesion promoters can be dispensed with if necessary. Depending on the type of article and the type of additional layers, layer E is particularly effective at increasing adhesion. It can be applied to the article blank using a heat lamp and pressure. Layer G

[0057] Layer G, made of a woven, knitted or warp-knitted fabric, can also be located on the outer layer C. This is preferably a warp and weft woven fabric, particularly preferably a bi-stretch woven fabric, as already described for layer D. Layer G can significantly reduce, and in some cases even completely prevent, the flow of the elastomer mixture of layer C2 under compressive load. Layer G also supports the other layers of the article so that any minor adhesion detachments that may occur can be tolerated. Advantageously, layer G also reduces the coefficient of friction of the article's surface, resulting in less article abrasion. Layer G can contain metal particles, for example aluminum in the form of aluminum flakes. The heat reflection of the metal particles leads to a further optimization of the fire protection behavior.A coating based on at least one fluorine-containing elastomer, such as FKM or PTFE, is also conceivable to optimize abrasion behavior.

[0058] The layers shown are combined according to one of the above-mentioned variants 1 to 5 before or during blank production, i.e., before the actual vulcanization process. In the first phase of vulcanization, the so-called flow or molding phase, the different layers can thus flow well together, which has a positive effect on the adhesion between the layers. An additional and cost-intensive second vulcanization process is not necessary.

[0059] The article is preferably an air spring bellows, a metal-rubber element, a vibration damper or a damping element of a bearing, a bushing or a layered spring or conical spring.

Claims

1. Article having a single-layer or multilayer main body having elastic properties, characterized in that the outer layer C consists at least of a first lamina C1 and a further lamina C2 and each lamina is formed from an elastomer mixture, where at least one layer D composed of a weave or loop-formed knit or loop-drawn knit has been embedded into this outer layer C between the first lamina C1 and the further lamina C2, where the article is an air spring bellows, a metal-rubber element, a vibration damper, or a damping element of a bearing, of a bushing or of a multilayered spring or conical spring, characterized in that the layer D consists of a bi-stretch weave, where a hybrid material composed of cotton, polyamide or polyester and elastane, with a cotton-dominating side and a polyamide- or polyester-dominating side, is used for the bi-stretch weave.

2. Article according to Claim 1, characterized in that the article comprises a further layer E.

3. Article according to Claim 2, characterized in that the further layer E is between the layer D and the lamina C2.

4. Article according to Claim 2 or 3, characterized in that the further layer E is a film of polyethylene.