DAMPING ELEMENT

Description

[0001] The invention relates to an article having a base body made of a polymeric material with elastic properties.

[0002] Articles made of polymer materials that are used for suspension, for example, in motor vehicles or rail vehicles and / or for vibration damping, are manufactured using elastomeric compounds, also known as rubber compounds. These elastomeric compounds, which are 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. Neither the aforementioned elastomer compounds, which are predominantly based on NR and / or IR, can meet these fire protection requirements, primarily due to the required maximum heat release rate, nor the flame-retardant elastomer compounds, which are predominantly based on CR, particularly due to the required smoke toxicity. Thus, articles containing these elastomer compounds generally no longer meet the more stringent requirements. A common method for improving the fire behavior of rubber compounds is the direct incorporation of flame-retardant substances.However, this measure generally leads to a significant deterioration in the physical properties of the affected articles, particularly their resilience, settling, and vibration properties. 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 for articles. Their low tensile strength is a disadvantage for good resistance to cracking or detachment. The high compression set, particularly at elevated temperatures, is detrimental to the resilience, settling, and vibration properties of the articles. The possibly necessary second vulcanization process during production of the final products reduces the tear resistance of the base compound in particular due to the usual tendency toward reversion.The use of a fire protection coating based solely on expanded graphite also presents disadvantages in terms of adhesion and processing. Expanded graphite itself only expands at relatively high temperatures, so its insulating effect is only achieved at relatively high temperatures. There are various types of expanded graphite, each with different onset temperatures. Depending on the type, the onset temperature ranges from 140°C to 280°C. DE 10 2012 104352 A1 discloses a cable guide equipped with polymeric, flocked damping elements.

[0005] 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. The article should exhibit sufficiently good fire protection behavior even at lower temperatures, possibly below the starting temperatures of expandable graphite.

[0006] This task is solved by the article having a base body made of a polymer material with elastic properties and an article surface that is completely or partially covered with at least one flock.

[0007] According to DIN 60 0001_2:1990, flock is defined as: "Short, deliberately produced man-made fibers not intended for spinning but capable of being processed by other methods (according to DIN 60 000)." The ISO 8159:1987 standard defines flock under 3.12 as: "Very short fibers destined to be stuck to a backing."

[0008] According to DIN 60 000:1969, flock textiles are defined as fabrics formed by textile fibers being bonded at one of their ends to a textile or non-textile carrier by an adhesive.

[0009] In this context, partial means that only certain, defined areas or sections of the article surface of the entire article are provided with the flock.

[0010] The entire article is therefore partially and / or completely flocked with at least one fiber material.

[0011] The structure and / or material of the flocking results in improved fire and flame protection in the form of less flammability even at temperatures below the starting temperatures of expandable graphite.

[0012] Any fiber known to the expert person can be used as fiber material for the flock.

[0013] As textile fibers for the flock, fibers made of 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, polyvinyl alcohol or fibers made of natural polymers, such as regenerated cellulose-based fibers such as viscose, lyocell or rubber, can preferably be used.

[0014] Furthermore, natural fibers are preferred as textile fibers. These can be mineral natural fibers, such as rock wool or asbestos fibers, or plant natural fibers, such as cotton, flax, or hemp, or even animal natural fibers, such as wool or silk.

[0015] It is also conceivable to use textile fibers made from inorganic materials such as glass, ceramics, carbon, metal or rock, such as basalt.

[0016] The textile fibers can be used alone or in combination, i.e. as a hybrid fiber.

[0017] According to the invention, fibers or textile fibers are used for the flock which already offer sufficient fire protection or have sufficient flame retardancy, such as polyoxadiazole, polyetherimide, aramids such as m-aramid, p-aramid or co-poly-para aramid, metal, glass, ceramic, stone, carbon, modified polyester, modified viscose.

[0018] The materials mentioned can be used alone or in combination, e.g. as hybrid yarn.

[0019] To further optimize fire protection performance, the flock can be additionally vapor-coated, i.e., sputtered, with at least one reflective substance on its surface. Due to the heat reflection resulting from the use of a reflective substance, the underlying mixture to be protected heats up less rapidly. This lowers the temperature of the underlying surface of the article to be protected, especially at the beginning of increased heat exposure. This delays the additional heat release and the formation of both dense and toxic smoke gases.

[0020] If the reflective substance consists of metal particles, e.g. made of aluminum or other suitable metals, the article surface is additionally protected against ignition.

[0021] As already mentioned above, the flock is usually applied to the surface to be flocked using a flocking adhesive, so that the article surface is not only partially or completely covered with a flock, but also partially or completely covered with a flocking adhesive.

[0022] Instead of the flocking adhesive, a composition based on at least one isocyanate can alternatively be used in accordance with DE 10 2009 044 533 A1.

[0023] In a particularly preferred embodiment, the flocking adhesive and / or the composition based on at least one isocyanate contains at least one fire-retardant substance to further optimize the fire protection behavior and / or the flame retardancy.

[0024] Flame retardants, but also other substances such as micro glass spheres and / or hollow glass micro spheres, which are preferably prepared to be adhesion-friendly, and / or hollow plastic spheres with a flexible polymer shell and / or reflective substances, such as metal particles, in particular made of aluminum and / or brass, can be used as a fire-retardant substance for the flocking adhesive and / or for the composition based on at least one isocyanate.

[0025] 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, preferably hollow glass microspheres, a preferred variant can contain fire-retardant substances 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.

[0026] In particular, the hollow plastic spheres can be in an already expanded form and / or in an expandable form.

[0027] 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 simultaneously. The resulting increase in volume leads to an increase in layer thickness, which provides a further insulating effect even before the actual firing. This increase in volume occurs at temperatures significantly lower than the usual onset temperatures of expandable graphite.

[0028] All flame retardants known to the person skilled in the art can be used as flame retardants for the flocking adhesive and / or for the composition based on at least one isocyanate.

[0029] In particular, 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 are suitable.

[0030] Intumescent mixtures expand into 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. If necessary, small amounts of antimony trioxide can also be used in combination with at least one of the aforementioned flame retardants, despite its health hazards.

[0031] The fire-retardant substances can be used alone or in combination.

[0032] In a preferred embodiment, the flock is applied to the surface of the not yet vulcanized article blank before the actual vulcanization process. The advantage here is that in the first phase of the vulcanization process, the so-called flow phase (= molding phase), both portions of the fiber flock and portions of the components of the flocking adhesive and / or the isocyanate-based composition can penetrate, i.e., flow, into the underlying base body to be protected, made of a polymer material. This further improves the adhesion of the flock to the base body, in particular because it enables the fibers of the flock to be anchored at least partially directly to the base body. This is particularly true when using an isocyanate-based composition, e.g.According to DE 10 2009 044 533 A1, the crosslinking reaction of this composition continues to progress under the vulcanization temperatures commonly used in the rubber industry, which is advantageously reflected in better adhesion of the flock and, in particular, in improved abrasion resistance of the flock structure.

[0033] If necessary, it is also possible to apply the flock to a pre-vulcanized article using the flocking adhesive and / or the isocyanate-based compound. This has the advantage that already finished articles can be subsequently treated with flame retardant. To further improve adhesion, it is advisable to clean the pre-vulcanized rubber surface and, if necessary, activate it.

[0034] Flock is used in particular for the following articles: Damping element of a bearing, a bushing or a layered spring, conical springThe damping element comprises a polymer material with elastic properties and is usually used as part of a metal-polymer composite, specifically in the form of a bearing with an upper and lower bearing part, a bushing with a core and sleeve, or a metal-rubber spring element, such as a layered or conical spring. Preferably, all exposed surfaces of the damping element are provided with flock. Of particular importance is an air spring bellow, which will be presented in more detail in connection with the description of the figures and which is not part of the claimed invention. In particular, (partially) vulcanizable polymer mixtures are used to form the base body, with the following two material variants being mentioned due to their elastic properties: Variant A (elastomers)The polymer mixture is a vulcanizable 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).The aforementioned rubber types can be unblended. The use of a blend, particularly in combination with one of the aforementioned rubber types, for example an NR / BR blend or a BR / SBR blend, is also possible. The preferred rubber type depends on the article type. The use of various rubber types is particularly diverse for tubular bodies, with the following rubber components being particularly noteworthy: NR, IR, ACM, AEM, BIMS, CM, CSM, CR, IIR, BIIR, CIIR, ECO, EPM, EPDM, ETER, EVA, FKM, HNBR, VMQ, or FVMQ. For drive belts, rubber compounds based on EPM and / or EPDM, ACSM (for V-belts and multi-ribbed belts), and NBR, especially HNBR, but also XNBR or NXBR (for timing belts) are used. The usual mixture ingredients comprise at least one crosslinker or a crosslinker 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 other additives (e.g., color pigments, reinforcing fibers) as well as other materials, if required. In this regard, reference is made to the general state of rubber blending technology. Variant B (thermoplastic elastomers)The polymer mixture is a partially vulcanizable polymer mixture containing at least one thermoplastic component, at least one rubber component that is at least partially crosslinkable, and other mixture ingredients. The preferred thermoplastic components are: polyolefin, in particular polyethylene (PE) or polypropylene (PP), polystyrene (PS), polyamide (PA), for example PA6 or PA6.6, polyester, for example PET, PEN, or PBT. Rubber components that can be mentioned here are, in particular, EPM, EPDM, SBR, CR, NR, NBR, FKM, ACM, or AEM, which, in particular, are not blended with any other rubber component. With regard to the usual mixture ingredients, reference is made to the mixing technology for variant A, in particular to the teachings of published patent application DE 100 04 632 A1.

[0035] Some devices will now be explained with reference to schematic drawings.

[0036] They show: Fig. 1an air spring arrangement; Fig. 2 the layered structure of an air spring bellows with a flock. Fig. 3 a section through a vibration damper according to the invention

[0037] Fig. 1 shows an air spring arrangement 1, comprising an air spring bellows 2 and the two connecting components cover 3 and rolling piston 4, forming a volume-elastic air chamber 5.

[0038] Fig. 2shows the layered structure of a finished air spring bellows 2. The air spring bellows consists of an inner layer 6 and outer layer 7 as an elastic base body, for example, a vulcanized rubber compound based on NR, a reinforcement layer 8 embedded between the inner layer 6 and outer layer 7, for example, in the form of a polyamide fabric, and a coating 9 that is directly bonded to the outer layer 8. The flock 9 was applied with a flocking adhesive containing flame-retardant substances.

[0039] Fig.3 shows a section through a vibration damper 10. The section in the circle of Fig. 3 will be in the Figures 3a and 3b shown in more detail. Between the inner layer 16 and the outer layer 17 there is an embedded reinforcement layer 18, for example in the form of a polyamide fabric. The flock 19 was Fig. 3awith a flocking adhesive 20 and in Fig. 3b applied without a flocking adhesive. List of reference symbols (part of the description)

[0040] 1 Air spring assembly 2 Air spring bellows 3 Cover 4 Rolling piston 5 Volume-elastic air chamber 6 Inner layer of an air spring bellows 7 Outer layer of an air spring bellows 8 Reinforcement layer of an air spring bellows 9 Flock 10 Damping element 16 Inner layer of a damping element 17 Outer layer of a damping element 18 Reinforcement layer of a damping element 19 Flock 20 Flocking adhesive

Claims

1. Article (1, 10) having a main body composed of a polymeric material having elastic properties, characterized in that all or part of the article surface has been provided with at least one flock (9, 19), where the article is the damping element of a bearing, of a bushing or of a multilayered spring, cone spring, and where fibres or textile fibres used for the flock (9, 19) intrinsically offer adequate fire protection or intrinsically have adequate flame retardancy.

2. Process for producing an article (1, 10) from a polymeric material having elastic properties according to Claim 1, characterized in that the flock (9, 19) is applied to the surface of the article in at least one process step with the aid of at least one flocking adhesive (20) and / or with the aid of at least one composition based on at least one isocyanate.

3. Process according to Claim 3, characterized in that the flocking adhesive (20) and / or the composition based on at least one isocyanate comprises at least one fire-retardant substance.