Sustainable acoustic damping material

Abstract

The invention relates to an acoustic damping material comprising: a) Polymerized cashew nut shell liquid P, b) At least one natural bitumen NB, c) Optionally at least one thermoplastic polymer TP, and d) At least 15 wt.-%, preferably at least 25 wt.-% of a solid particulate filler component F.

Description

[0001] SUSTAINABLE ACOUSTIC DAMPING MATERIAL

[0002] Technical field

[0003] The present invention relates to sustainable acoustic damping materials comprising bio-based components for use in automotive vibration damping applications. Particularly, the invention relates to acoustic damping materials for damping of vibrations and noise of components and structures in transportation vehicles, excluding road construction and pavement applications.

[0004] Background of the invention

[0005] Acoustic damping materials are widely used in automotive applications for reducing undesired vibrations, structure borne noise, and air borne noise. In automotive vehicles, it is desirable to prevent transfer of vibrations generated by the motors, pumps, gears and other dynamic force generators through the body of the vehicle into the passenger compartment. Structure borne noise is produced when the vibrations generated by a dynamic force generator are transmitted through a supporting structure, typically a frame or other hollow structure, to a noise emitting surface, such as a metallic or plastic panel, which transforms the mechanical vibrations into sound waves. Structure borne noise and vibrations in general can be effectively reduced by application of vibration damping materials directly to the structures and surfaces of automotive components subjected to vibrational disturbances, such as to surfaces of vehicle panels, floors, and engine compartments.

[0006] Acoustic damping materials used for damping of vibrating surfaces are commonly provided as pre-formed single- and multi-layer elements or as liquid compositions, which are applied directly on surface of a substrate. Pre-formed damping elements typically comprise a layer of damping material, which is in direct contact with a surface of the substrate to be damped against vibrational disturbances. The layer of damping material is capable of dissipating kinetic energy of the vibrating surface into heat energy through extension and compression of the material of the damping layer. Such damping elements can further comprise an adhesive layer, such as a layer of a pressure sensitive adhesive or a hot-melt adhesive, to enable bonding of the damping element to a surface of a substrate. Liquid applied damping systems are typically thermally drying, gelling, or reactive compositions, which are applied on the surface of the substrate in liquid state, for example by spraying.

[0007] Commonly used damping materials include highly filled compositions comprising bitumen, elastomers, or thermoplastic polymers and varying amounts of additives, such as plasticizers, processing aids, rheology modifiers, and drying agents. Fillers are added to these compositions to meet different design goals. Some of the fillers are used to improve the acoustic damping properties, whereas other fillers are used to reduce the density of the material or to replace more expensive materials in order to reduce costs of raw materials. Typical fillers used in acoustic damping materials include, particularly, mineral fillers, such as calcium carbonate. Light weight mineral fillers, such as hollow ceramic spheres and hollow glass spheres have been widely used to reduce the density of the acoustic damping material and eventually to reduce the weight of the acoustic damping element.

[0008] Almost all constituents of acoustic damping materials of prior art have a relatively high CO2 footprint due to the petroleum based origin of the raw materials and the energy intensive production process. Especially the main components of acoustic damping materials, including synthetic polymers, bitumen, and fillers are commonly based on 100 % of non-renewable raw materials. It would generally be advantageous to replace most of the fossil-based raw materials with bio-based alternatives to reduce the CO2 footprint of the acoustic damping materials for automotive applications. However, such replacement should not have significant negative impact on application relevant properties of the damping material.

[0009] There is thus a need for a new type of sustainable acoustic damping material for automotive applications, which can be used for damping of vibrations and noises of components and structures in transportation vehicles, which material has a significantly lower CO2 footprint compared to damping elements of prior art.

[0010] CN1 17801679A discloses an asphalt pavement regeneration preventive maintenance material comprising an asphalt curing agent, asphalt mortar emulsion, and waterproof curing liquid. However, this document is directed to road construction and pavement applications rather than automotive vibration damping. KR102377922B1 describes a low-noise PCM modified recycled asphalt concrete composition for drainage applications. This document mentions cashew nut shell liquid as a component, it is focused on road pavement construction rather than automotive damping materials.

[0011] Summary of the invention

[0012] The object of the present invention is to provide a sustainable acoustic damping material for use in automotive damping elements, which are suitable for damping of undesired vibrations and noise in structures of transportation vehicles.

[0013] Surprisingly, it has been found that the features of claim 1 achieve this object.

[0014] Particularly, it was surprisingly found out that a combination of polymerized cashew nut shell liquid (CNSL) and natural bitumen can be used to replace conventional bitumen in an acoustic damping material for automotive applications. The modified damping material has a significantly lower CO2 footprint compared to bitumen- based damping materials of prior art.

[0015] Specifically, according to the invention, a sustainable acoustic damping material for automotive vibration damping applications is provided, the material comprising: a) Polymerized cashew nut shell liquid P, b) At least one natural bitumen NB, c) Optionally at least one thermoplastic polymer TP, and d) At least 15 wt.-%, preferably at least 25 wt.-% of a solid particulate filler component F.

[0016] Other subjects of the present invention are presented in other independent claims. Preferred aspects of the invention are presented in the dependent claims. Brief description of the Drawings

[0017] Fig. 1 shows a cross-section of a damping element (1 ) comprising of a damping layer (2) and an adhesive layer (3).

[0018] Fig. 2 Shows a cross-section of a damping element (1 ) comprising a damping layer (2), an adhesive layer (3), and a constraining layer (4). Fig. 3 shows a cross-section of a vibration and / or noise damped system comprising a structure (5) having a noise emitting surface (6) and a damping element (1 ), wherein the damping layer (2) is bonded to the noise emitting surface (6) via the adhesive layer (3).

[0019] Detailed description of the invention

[0020] The subject of the present invention is a sustainable acoustic damping material for automotive vibration damping applications comprising: a) Polymerized cashew nut shell liquid P, b) At least one natural bitumen NB, c) Optionally at least one thermoplastic polymer TP, and d) At least 15 wt.-%, preferably at least 25 wt.-% of a solid particulate filler component F.

[0021] The term “polymer” refers to a collective of chemically uniform macromolecules produced by a polyreaction (polymerization, polyaddition, polycondensation) where the macromolecules differ with respect to their degree of polymerization, molecular weight and chain length. The term also comprises derivatives of said collective of macromolecules resulting from polyreactions, that is, compounds which are obtained by reactions such as, for example, additions or substitutions, of functional groups in predetermined macromolecules and which may be chemically uniform or chemically non-uniform.

[0022] The term “molecular weight” refers to the molar mass (g / mol) of a molecule or a part of a molecule, also referred to as “moiety”. The term “average molecular weight” refers to number average molecular weight (Mn) of an oligomeric or polymeric mixture of molecules or moieties. The molecular weight can be determined by conventional methods, preferably by gel permeation-chromatography (GPC) using polystyrene as standard, styrene-divinylbenzene gel with porosity of 100 Angstrom, 1000 Angstrom and 10000 Angstrom as the column, and, depending on the molecule, tetrahydrofurane as a solvent, at 35 °C, or 1 ,2,4-trichlorobenzene as a solvent, at 160 °C.

[0023] The term “glass transition temperature” (Tg) refers to the temperature above which temperature a polymer component becomes soft and pliable, and below which it becomes hard and glassy. The glass transition temperature (Tg) is preferably determined by dynamical mechanical analysis (DMA) as the peak of the measured loss modulus (G”) curve using an applied frequency of 1 Hz and a strain level of 0.1 %.

[0024] The term “softening point” refers to a temperature at which compound softens in a rubber-like state, or a temperature at which the crystalline portion within the compound melts. The softening point is preferably determined by Ring and Ball measurement conducted according to EN 1238:2011 standard.

[0025] The term “melting temperature” refers to a temperature at which a material undergoes transition from the solid to the liquid state. The melting temperature (Tm) is preferably determined by differential scanning calorimetry (DSC) according to ISO 11357-3:2018 standard using a heating rate of 2 °C / min. The measurements can be performed with a Mettler Toledo DSC 3+ device and the Tm values can be determined from the measured DSC-curve with the help of the DSC-software. In case the measured DSC- curve shows several peak temperatures, the first peak temperature coming from the lower temperature side in the thermogram is taken as the melting temperature (Tm).

[0026] The “amount or content of at least one compound X” in a composition, for example “the amount of the at least one thermoplastic polymer TP” refers to the sum of the individual amounts of all thermoplastic polymers TP contained in the composition. For example, in case the composition comprises 20 wt.-% of at least one thermoplastic polymer TP, the sum of the amounts of all thermoplastic polymers TP contained in the composition equals 20 wt.-%.

[0027] The acoustic damping material comprises as a first compulsory component polymerized cashew nut shell liquid P.

[0028] The term "polymerized cashew nut shell liquid P" refers in the present disclosure a composition based on polymerization of raw cashew nut shell liquid (CNSL) or technical CNSL. Particularly, a polymerized cashew nut shell liquid P comprises a polymerized fraction and an un-polymerized fraction, where the polymerized fraction comprises alkyl-phenol polymers, which are high molecular weight polymerization products of cardol and cardanol. The term "raw CNSL" refers in the present disclosure to CNSL obtained by solvent extraction and is characterized by comprising mostly anacardic acid. The term "technical CNSL" refers to CNSL obtained by hot-oil or roasting processing of cashew nuts and is rich in cardanol.

[0029] In embodiments, the polymerized cashew nut shell liquid P has been obtained by using a method comprising subjecting a raw or technical CSNL to a heat treatment under reflux to obtain a polymerized CNSL composition. Suitable processes for obtaining polymerized cashew nut shell liquid P are disclosed, for example, in European patent EP 3 208 288 B1.

[0030] The acoustic damping material comprises as a second compulsory component at least one natural bitumen NB.

[0031] The term "natural bitumen" refers here to semisolid or solid mixtures of hydrocarbons and heterocyclic compounds composed mostly of carbon and hydrogen but having some amount of other elements such as oxygen, sulfur, and nitrogen. Natural bitumen is formed by the conversion of crude oil over time and the evaporation of its volatiles and it is mainly found in underground mines and lakes. Natural bitumen NB is distinguished from petroleum -derived asphalt by being naturally occurring semisolid or solid mixtures formed by conversion of crude oil over geological time periods.

[0032] Natural bitumen can also be divided in two categories, of which the first one is soluble in oil solvents, such as CS2 or TCE and CCL4, and another which is not soluble in oil solvents. The latter class of natural bitumen is also known as “pyrobitumens”.

[0033] In embodiments, the acoustic damping material is having a significantly lower CO2 footprint compared to conventional petroleum -based damping materials.

[0034] The significantly lower CO2 footprint may be achieved through the replacement of conventional petroleum-derived bitumen with the combination of polymerized cashew nut shell liquid P and natural bitumen NB. The polymerized cashew nut shell liquid P may be derived from renewable bio-based feedstock, which can contribute to reducing the overall carbon footprint of the acoustic damping material. In some aspects, the cashew nut shell liquid may be obtained as a by-product of cashew nut processing, thereby utilizing waste materials that would otherwise require disposal.

[0035] The natural bitumen NB, being naturally occurring rather than petroleum -refined, may require less energy-intensive processing compared to conventional synthetic bitumen or asphalt. In some cases, the extraction and processing of natural bitumen may involve fewer chemical treatment steps and lower processing temperatures, which can result in reduced energy consumption and associated CO2 emissions during production.

[0036] The combination of these bio-based and naturally occurring components may enable the acoustic damping material to achieve comparable or improved damping performance while maintaining a reduced environmental impact. In some embodiments, the CO2 footprint reduction may be in the range of 20-60% compared to conventional petroleum -based damping materials, depending on the specific composition and processing methods employed.

[0037] Additionally, the solid particulate filler component F may include cellulose-containing fillers such as wood particles, which are renewable and biodegradable materials that can further contribute to the overall sustainability of the acoustic damping material. These bio-based fillers may replace conventional mineral fillers partially or completely, thereby reducing the reliance on energy-intensive mineral extraction and processing operations.

[0038] In embodiments, the at least one natural bitumen NB is selected from gilsonite, grahamite, uintahite, glance pitch, asphaltic pyrobitumen, and non-asphaltic pyrobitumen, preferably gilsonite. The natural bitumen NB is distinguished from petroleum-derived asphalt by being naturally occurring semisolid or solid mixtures formed by conversion of crude oil over time.

[0039] The selection of specific natural bitumen types may provide enhanced compatibility with the polymerized cashew nut shell liquid P, potentially resulting in improved homogeneity and stability of the acoustic damping material. Gilsonite, in particular, may offer advantageous properties due to its high asphaltene content and relatively uniform composition, which can contribute to consistent damping performance across different temperature ranges.

[0040] The naturally occurring formation process of these bitumens over geological time periods may result in a more stable molecular structure compared to rapidly processed petroleum-derived asphalts. This enhanced molecular stability can contribute to better long-term performance of the damping material, potentially reducing degradation under thermal cycling and mechanical stress conditions typical in automotive applications. Furthermore, the use of natural bitumen types may facilitate better adhesion properties when combined with the polymerized cashew nut shell liquid P, potentially improving the bonding characteristics of the damping material to metal substrates commonly found in vehicle structures. The specific hydrocarbon composition of these natural bitumens may also contribute to maintaining optimal viscoelastic properties across the operating temperature range required for automotive vibration damping applications.

[0041] Furthermore, the at least one natural bitumen NB preferably may have a content of asphaltenes of at least 25 wt.-%, preferably at least 35 wt.-%.

[0042] The asphaltene content in the natural bitumen NB may contribute to the mechanical properties and performance characteristics of the acoustic damping material. Asphaltenes, being high molecular weight aromatic compounds, may act as natural reinforcing agents within the damping matrix, potentially enhancing the structural integrity and durability of the material under dynamic loading conditions.

[0043] In some aspects, the specified asphaltene content may facilitate improved compatibility between the natural bitumen NB and the polymerized cashew nut shell liquid P, potentially promoting better molecular interactions and homogeneous distribution throughout the damping material. This enhanced compatibility may result in more consistent viscoelastic properties across the material, which can contribute to uniform damping performance.

[0044] The asphaltene content may also influence the temperature-dependent behavior of the acoustic damping material. In some cases, the presence of asphaltenes in the specified range may help maintain optimal damping characteristics across a broader temperature range, potentially providing stable performance under varying automotive operating conditions from cold start-up to elevated engine compartment temperatures.

[0045] Additionally, the asphaltene content may contribute to the adhesive properties of the damping material when applied to metal substrates. The polar functional groups present in asphaltenes may enhance the interfacial bonding between the damping material and vehicle structures, potentially improving the long-term adhesion and reducing the risk of delamination under vibrational stress.

[0046] In embodiments, the sum of the proportions of a) and b) makes up 10 - 50 wt.-%, preferably 25 - 45 wt.-%, more preferably 30 - 45 wt.-% of the total weigh of the acoustic damping material. The weight ratio of the amounts of the polymerized cashew nut shell liquid P and the at least one natural bitumen NB, preferably gilsonite, may be in the range of 0.25 - 1 .5, preferably 0.45 - 1 .25, more preferably 0.5 -1 .0, even more preferably 0.7 - 0.9.

[0047] In one embodiment, the acoustic damping material further comprises at least one tackifying resin TR and / or at least one wax W.

[0048] The term “tackifying resin” designates in the present disclosure resins that in general enhance the adhesion and / or tackiness of a composition. The term “tackiness” refers in the present document to the property of a substance of being sticky or adhesive by simple contact, which can be measured, for example, as a loop tack. Preferred tackifying resins can be used to improve the adhesion and / or tackiness of a composition at a temperature of 25 °C.

[0049] Suitable tackifying resins to be used in the thermally expandable composition have a relatively low number average molecular weight (Mn), such as not more than 5000 g / mol, in particular not more than 3500 g / mol, preferably not more than 2500 g / mol and a softening point (Ts), determined by a Ring and Ball method according to DIN EN 1238:2011 , of at or below 175 °C, preferably at or below 165 °C, more preferably at or below 155 °C. Suitable tackifying resins include, in particular, synthetic resins, natural resins, and chemically modified natural resins.

[0050] The term “synthetic resin” designates in the present disclosure compounds obtained from the controlled chemical reactions such as polyaddition or polycondensation between well-defined reactants that do not themselves have the characteristic of resins. Monomers that may be polymerized to synthesize the synthetic resins may include aliphatic monomer, cycloaliphatic monomer, aromatic monomer, or mixtures thereof. Suitable aliphatic monomers may include C4, Cs, and Cs paraffins, olefins, and conjugated diolefins. Examples of aliphatic monomers or cycloaliphatic monomers include butadiene, isobutylene, 1 ,3-pentadiene, 1 ,4-pentadiene, cyclopentane, 1 - pentene, 2-pentene, 2- methyl-1 -pentene, 2-methyl-2-butene, 2-methyl-2-pentene, isoprene, cyclohexane, 1 - 3-hexadiene, 1 -4-hexadiene, cyclopentadiene, and dicyclopentadiene. Examples of aromatic monomer include Cs, C9, and C10 aromatic monomers. Typical aromatic monomers include, styrene, alphamethyl styrene, vinyl toluene, methoxy styrene, tertiary butyl styrene, chlorostyrene, coumarone, and indene monomers including indene, and methyl indene, and combinations thereof. Suitable synthetic resins include, for example, hydrocarbon resins, coumarone-indene resins, polyindene resins, polystyrene resins, vinyl toluene-alphamethyl styrene copolymer resins, and alphamethyl styrene resins.

[0051] The term “hydrocarbon resin” designates in the present disclosure synthetic resins made by polymerizing mixtures of unsaturated monomers obtained from petroleum - based feedstocks, such as by-products of cracking of natural gas liquids, gas oil, or petroleum naphthas. These types of hydrocarbon resins are also known as “petroleum resins” or as “petroleum hydrocarbon resins”. The hydrocarbon resins include also pure monomer aromatic resins, which are prepared by polymerizing aromatic monomer feedstocks that have been purified to eliminate color causing contaminants and to precisely control the composition of the product.

[0052] Suitable hydrocarbon resins are commercially available, for example, under the trade name of Wingtack®, Wingtack® Plus, Wingtack® Extra, and Wingtack® STS (all from Cray Valley); under the trade name of Escorez® 1000 series, Escorez® 2000 series, and Escorez® 5000 series (all from ExxonMobil Chemical); under the trade name of Novares® T series, Novares® TT series, Novares® TD series, Novares® TL series, Novares® TN series, Novares® TK series, and Novares® TV series (all from RUTGERS Novares GmbH); and under the trade name of Kristalex®, Plastolyn®, Piccotex®, Piccolastic® and Endex® (all from Eastman Chemicals).

[0053] In embodiments, the acoustic damping material comprises 0.5 - 20 wt.-%, preferably 1 - 15 wt.-%, more preferably 1 - 12.5 wt.-%, even more preferably 1.5 - 10 wt.-%, still more preferably 2.5 - 10 wt.-% of the at least one tackifying resin TR.

[0054] Especially preferred tackifying resins TR have a softening point determined by Ring and Ball measurement conducted according to EN 1238:2011 standard in the range of 75 - 165 °C, preferably 85 - 155 °C, more preferably 90 - 145 °C.

[0055] In embodiments, the acoustic damping material comprises, in addition or instead of the at least one tackifying resin TR, at least one wax W.

[0056] The term “wax” designates in the present disclosure substances that have a waxy consistency and have a melting temperature or melting temperature range of above normal room temperature, particularly above 25 °C.

[0057] Suitable waxes to be used in the acoustic damping material include in particular synthetic waxes, for example, petroleum waxes, such as paraffin wax, petrolatum, and microcrystalline waxes, polyolefin waxes, polyethylene glycol waxes (Carbowax), amide waxes, and chemically modified waxes, such as hardened or hydrogenated waxes, for example, Montan ester waxes.

[0058] Particularly, the at least one wax W may be selected from the group consisting of polyolefin waxes, paraffin waxes, microcrystalline waxes, and amide waxes.

[0059] In embodiments, the at least one wax W is a polyolefin wax.

[0060] The term “polyolefin wax” designates in the present disclosure low molecular weight polymers of linear or branched a-olefins having from 2 to 30 carbon atoms and a number average molecular weight (Mn) in the range of 5000 - 25000 g / mol. They include both homopolymers and copolymers of the above mentioned linear or branched a-olefins.

[0061] Polyolefin waxes can be obtained by thermal decomposition of polyolefin plastics, in particular polyethylene plastic, or by direct polymerization of olefins. Suitable polymerization processes include, for example, free-radical processes, where the olefins, for example, ethylene, are reacted at high pressures and temperatures to give more or less branched waxes and processes, where ethylene and / or higher a-olefins, in particular propylene, are polymerized using metalorganic catalysts, for example Ziegler-Natta or metallocene catalysts, to give unbranched or branched waxes. The polyolefin waxes have generally at least partially crystalline structure.

[0062] In embodiments, the at least one wax W is an amide wax. The term “amide wax” designates in the present document waxes containing an amide bond (-CONH-) in the molecule or an amide group (-CONH2) at the end of the molecule. Especially suitable amide waxes include N,N’-ethylenebis(stearoamide), stearic acid amide, N,N’-methylenebis(stearoamide),and methylolstearoamide.

[0063] The acoustic damping material may comprise 0.1 - 10 wt.-%, such as 0.5 - 7.5 wt.- %, especially 0.5 -5 wt.-% of the at least one wax W.

[0064] In embodiments, the acoustic composition further comprises at least one thermoplastic polymer TP.

[0065] The term “thermoplastic” refers in the present disclosure to any material which can be melted and re-solidified with little or no change in physical properties. Various types of thermoplastic polymers, including crystalline, semi-crystalline, and amorphous polymers and thermoplastic elastomers are suitable for use as the at least one thermoplastic polymer TP.

[0066] In embodiments, the acoustic damping material comprises 0.5 - 10 wt.-%, preferably 0.75 - 7.5 wt.-%, more preferably 1 .0 - 7.5 wt.-%, even more preferably 1.0 - 5 wt.-% of the thermoplastic polymer TP.

[0067] In one exemplary embodiment, the at least one thermoplastic polymer TP is selected from ethylene vinyl acetate copolymers, polyethylenes, ethylene copolymers, polypropylenes, propylene copolymers, and styrene block copolymers.

[0068] In embodiments, the acoustic damping material comprises at least one styrene block copolymer TP1.

[0069] Suitable styrene block copolymers include block copolymers containing polystyrene and polybutadiene blocks and / or polyisoprene blocks. These materials are generally available as pure triblock copolymers, also known as SIS and SBS block copolymers, and as diblock copolymers (SI and SB block copolymers). Furthermore, styrene block copolymers are also commercially available as mixtures of diblock and triblock copolymers. Suitable styrene block copolymers can have a linear, radial, or star structure, the linear structure being especially preferred.

[0070] Suitable SI, SIS, SB, and SBS block copolymers are commercially available, for example from TSRC / Dexco under the trade name of Vector®, such as Vector® 7000- series; from Kraton Polymers under the trade name of Kraton® D-series, such as Kraton Kraton® D 1000 and 4000-series; and from Dynasol under the trade name of Calprene®.

[0071] The at least one styrene block copolymer TP1 may be selected from styrene butadiene diblock (SB) copolymer, styrene isoprene diblock (SI) copolymer, styrene butadiene styrene triblock (SBS) copolymer, styrene isoprene styrene triblock (SIS) copolymer, and mixtures thereof, preferably from styrene butadiene styrene triblock (SBS) copolymer and styrene isoprene styrene triblock (SIS) copolymer.

[0072] In further embodiments, the acoustic damping material comprises at least one polyethylene TP2.

[0073] Suitable polyethylenes include ethylene homopolymers and ethylene copolymers, preferably selected from the group consisting of low-density polyethylene (LDPE) or linear low-density polyethylene (LLDPE), or high-density polyethylene (HDPE), preferably linear low-density polyethylene (LLDPE).

[0074] According to one or more embodiments, the at least one polyethylene TP2 has:

[0075] - a melt flow index (MFI) determined according to ISO 1133 (190 °C / 2.16 kg) of at least 35 g / 10 min, preferably at least 50 g / 10 min, more preferably at least 75 g / 10 min and / or

[0076] - a softening point determined according to ISO 306:2013 standard of at or below 150 °C, preferably at or below 135 °C, more preferably at or below 115 °C.

[0077] In still further embodiments, the acoustic damping material comprises the at least one styrene block copolymer TP1 and the at least one polyethylene TP2, wherein the weight ratio between the amounts of TP1 and TP2 in the acoustic damping material is preferably in the range of from 0.3 to 2.5, more preferably from 0.5 to 2.0.

[0078] The acoustic damping material further contains at least 15 wt.-%, preferably at least 25 wt.- % of a solid particulate filler component F.

[0079] In embodiments, the acoustic damping material comprises 25 - 75 wt.-%, preferably 35 - 70 wt.-%, more preferably 40 - 65 wt.-%, even more preferably 45 - 60 wt.-% of the solid particulate filler component F.

[0080] In embodiments, the solid particulate filler component F comprises at least one mineral filler F1 and / or at least one cellulose-containing filler F2.

[0081] The at least one mineral filler F1 is preferably present in the acoustic damping material in form of fine particles, particularly, having a median particle size dso of not more than 100 pm, preferably not more than 50 pm.

[0082] The term “median particle size dso” refers to a particle size below which 50 % of all particles by volume are smaller than the dso value. The particle size distribution may be measured, for example, by sieve analysis according to the method as described in ASTM C136 / C136M -2014 standard (“Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates).

[0083] In embodiments, the at least one mineral filler F1 has a median particle size dso in the range of 0.1 - 100 pm, preferably 0.25 - 50 pm, more preferably 0.5 - 25 pm. It may also be preferred that the mineral filler F1 has a water-solubility of less than 0.1 g / 100 g water, more preferably less than 0.05 g / 100 g water, even more preferably less than 0.01 g / 100 g water, at a temperature of 20 °C. The solubility of a compound in water can be measured as the saturation concentration, where adding more compound does not increase the concentration of the solution, i.e. where the excess amount of the substance begins to precipitate.

[0084] In embodiments, the at least one mineral filler F1 is selected from the group consisting of calcium carbonate, magnesium carbonate, talc, kaolin, diatomaceous earth, wollastonite, feldspar, montmorillonite, dolomite, silica, cristobalite, mica, barium sulfate, graphite, ceramic spheres, hollow glass spheres, glass spheres.

[0085] It may be preferable that the acoustic damping material comprises several different mineral fillers, such as at least two different mineral fillers. Some of the mineral fillers may, for example, be used for improving the acoustic damping properties of the material whereas other may be used to enable adhering of the material to a metal substrate by magnetic force or for decreasing the weight of the material.

[0086] In embodiments, the acoustic damping material comprises:

[0087] - At least one first mineral filler F11 and / or

[0088] - At least one second mineral filler F12 different from the at least one first mineral filler F11 and / or

[0089] - At least one third mineral filler F13 different from the at least one first mineral filler F11 and from the at least one second mineral filler F12.

[0090] Particularly, the at least one first solid mineral filler F11 may have a median particle size dso in the range of 1 - 100 pm and / or an apparent density of at least 1.5 g / cm3and / or a number average particle aspect ratio of not more than 2.5.

[0091] Generally, the density of particulate materials can be determined based on different definitions for the volume occupied by the particles of the material. A “true density” refers to the ratio of the mass and the “true volume” of a sample, excluding the volume of the open pores, closed pores, and the inter-particle voids. An “apparent density”, also known as “skeletal density”, is calculated based on the skeletal volume of the particles, excluding both the open pores and inter-particle voids. A “bulk density” of a powder material is calculated as the mass of the particles per unit volume after the particles have freely filled a standard container under specific conditions thus including the closed pores, open pores, and inter-particle voids. True density and apparent density can be measured using both gas and liquid displacement methods. In a gas displacement method, typically helium, gas is employed instead of liquid to measure the sample volume.

[0092] The term “aspect ratio” refers in the present disclosure to the value obtained by dividing the length of a particle by the thickness of the particle. The “length of a particle” refers in the present disclosure to the maximum Feret diameter (XFe,max), i.e. the longest Feret diameter out of the measured set of Feret diameters. The term “Feret diameter” refers in the present disclosure to the distance between two tangents on opposite sides of the particle, parallel to some fixed direction and perpendicular to the measurement direction. The “thickness of a particle” refers in the present disclosure to the minimum Feret diameter (XFe.min), i.e. the shortest Feret diameter out of the measured set of Feret diameters. The aspect ratio is, therefore, calculated as the ratio Of XFe,max and XFe,min.

[0093] The aspect ratio of a particle can be determined by measuring the length and thickness of the particle using any suitable measurement technique, such as by using dynamic image analysis method conducted according to ISO 13322-2:2006 standard and calculating the aspect ratio from the measured dimensions of the particle as described above. The dimensions of particles can be measured with a dry dispersion method, where the particles are dispersed in air, particularly by using air pressure dispersion method. The measurements may be conducted using any type of dynamic image analysis apparatus, such as a Camsizer XT device (trademark of Retsch Technology GmbH).

[0094] The term “number average aspect ratio” refers in the present disclosure to the arithmetic average of the individual aspect ratios of the particles within a sample or collection or a statistically significant and representative random sample drawn from such a sample or collection. The number average aspect ratio of a particulate material can be determined by measuring the dimensions of individual particles of the sample using any suitable measurement technique, preferably by using dynamic image analysis method conducted according to ISO 13322-2:2006 standard and calculating the number average aspect ratio from the measured dimensions of the individual particles as described above. Furthermore, the at least one second mineral filler F12 may have a median particle size dso in the range of 250 - 1000 pm and / or an apparent density of not more than 1 .0 g / cm3

[0095] In addition, the at least one third mineral filler F13 may have a median particle size dso of at least 100 pm and / or an apparent density of at least 1.5 g / cm3and / or a number average particle aspect ratio of at least 3.0.

[0096] In embodiments, the at least one first mineral filler F11 is selected from the group consisting of calcium carbonate, magnesium carbonate, talc, kaolin, wollastonite, feldspar, montmorillonite, dolomite, silica, cristobalite, iron oxide, iron nickel oxide, and strontium ferrite and / or the at least one second mineral filler F12 is selected from the group consisting of hollow ceramic spheres, hollow glass spheres, hollow organic spheres, and glass spheres and / or the at least one third solid particulate filler F13 is selected from the group consisting of mica, montmorillonite, slate, talc, barium sulfate, and graphite.

[0097] The cellulose-containing filler F2 may be used instead of the mineral filler F1 , particularly instead of the third mineral filler F13, or in addition to the mineral filler F1, particularly in addition to the first F11 and / or second F12 mineral filler.

[0098] In embodiments, the cellulose-containing filler contains at least 25 wt.-%, preferably at least 35 wt.-%, more preferably at least 40 wt.-% of cellulose, based on the total weight of the cellulose-containing filler F2.

[0099] In preferred embodiments, the cellulose-containing filler F2 is composed of wood particles. The term “wood particle” refers to particles composed of wood fibers. The length dimension of a wood particle is typically orientated parallel to the grain structure of the wood particle, i.e. parallel to the orientation of the long axis of the dominant fibers in the wood particle.

[0100] Suitable wood particles for use as the at least one cellulose-containing filler F2 include, for example, all types of soft wood and hard wood particles.

[0101] The term “softwood” refers to wood from conifers, i.e. wood from needle-bearing trees from the order Pinales. Softwood-producing trees include, for example, pine, spruce, cedar, fir, larch, douglas-fir, hemlock, cypress, redwood, and yew. Conversely, the term “hardwood” refers to wood from broad-leaved or angiosperm trees, such as eucalyptus, maple, birch, beech, aspen, and the like. Softwoods contain two types of cells, longitudinal wood fibers (or tracheids) and transverse ray cells whereas hardwood trees contain pores or vessels. In softwood, water transport within the tree is via the tracheids rather than the pores of hardwoods.

[0102] In embodiments, the at least one cellulose-containing filler F2 has:

[0103] - a median particle size dso in the range of 50 - 650 pm, preferably 75 - 550 pm, more preferably 100 - 450 pm, even more preferably 125 - 400 pm, still more preferably 150 - 350 pm, most preferably 175 - 300 pm and / or

[0104] - a doo particle size in the range of 150 - 1000 pm, preferably 175 - 750 pm, more preferably 200 - 550 pm, even more preferably 200 - 450 pm, most preferably 225 - 400 pm and / or

[0105] - a dw particle size in the range of 15 - 350 pm, preferably 35 - 250 pm, more preferably 55 - 200 pm, even more preferably 65 - 175 pm, most preferably 85 - 150 pm.

[0106] The at least one cellulose-containing filler F2 may have an apparent density in the range of 0.25 - 1.5 g / cm3, preferably 0.30 - 1.25 g / cm3, more preferably 0.35 - 1.0 g / cm3, even more preferably 0.40 - 1.0 g / cm3.

[0107] Furthermore, the at least one cellulose-containing filler F2 may have a true density in the range of 1 .00 - 2.00 g / cm3, preferably 1 .25 - 1 .85 g / cm3, more preferably 1 .35 - 1 .75 g / cm3, even more preferably 1 .40 - 1 .70 g / cm3.

[0108] In some embodiments, the solid particulate filler component F is composed of the at least one mineral filler F1.

[0109] In other embodiments, the solid particulate filler component F is composed of the at least one cellulose-containing filler F2.

[0110] In further embodiments, the solid particulate filler comprises F comprises or is composed of the at least one mineral filler F1 and the at least one cellulose-containing filler F2, wherein the weight ratio of the amount of the at least one mineral filler F1 to the amount of the cellulose-containing filler F2 in the acoustic damping material is in the range of from 10:1 to 1 :1 , preferably from 7:1 to 2:1 , more preferably form 6:1 to 3:1. The acoustic damping material may optionally contain one or more additives, which are customary for acoustic damping materials. Examples of suitable additives include, for example, pigments, thixotropic agents, thermal stabilizers, drying agents, and flame retardants. These additives, if used at all, preferably make up not more than 25 wt.-%, more preferably not more than 10 wt.-%, of the total weight of the acoustic damping material.

[0111] Another subject of the present invention is use of the damping material as described above for damping of vibrations and / or noise in automotive applications, transportation vehicle or white goods, specifically excluding road construction and pavement applications.

[0112] A further subject of the present invention is a damping element comprising: i) A damping layer composed of the acoustic damping material as discussed above and ii) Optionally an adhesive layer for bonding to vehicle structures covering at least a portion of an upper or lower major surface of the damping layer.

[0113] Such damping element is especially suitable for use in damping of undesired vibrations and noise in mechanical structures and components of transportation vehicles. A cross-section of an exemplary damping element is shown in figure 1 .

[0114] The term “layer” refers in the present disclosure to a sheet-like element having upper and lower major surfaces ,a width defined between longitudinally extending edges, and a thickness defined between the upper and lower major surfaces. The term “thickness” refers to a dimension of a sheet-like element that is measured in a plane that is substantially perpendicular to the length and width dimensions of the element.

[0115] Particularly, the upper major surface of the damping layer may form one of the primary exterior surfaces of the damping element. The term “primary exterior surface” refers here to the outermost surfaces of the damping element.

[0116] In embodiments, the damping layer (2) has a maximum thickness of 0.5 - 15 mm, preferably 1 - 10 mm, more preferably 1.5 - 7.5 mm, even more preferably 1.5 - 5 mm and / or a density in the range of 0.5 - 5 g / cm3, preferably 0.75 - 4.5 g / cm3, more preferably 1 - 3 g / cm3, even more preferably 1 - 2.5 g / cm3. Suitable adhesives for use in the adhesive layer (3) include, particularly, pressure sensitive adhesives and hot-melt adhesives. The term “pressure sensitive adhesive” is understood to include also pressure sensitive hot-melt adhesives (HM-PSA), which are heated and applied as a melt to a surface of a substrate.

[0117] Pressure sensitive adhesives (PSA) are viscoelastic materials, which adhere immediately to almost any kind of substrate by application of light pressure and which are permanently tacky.

[0118] Suitable pressure sensitive adhesives for the adhesive layer (2) include adhesives based on acrylic polymers, styrene block copolymers, amorphous polyolefins (APO), amorphous poly-a-olefins (APAO), vinyl ether polymers, or elastomers such as, for example, butyl rubber, rubber like ethylene vinyl acetate copolymer, natural rubber, nitrile rubber, silicone rubber, and ethylene-propylene-diene rubber. In addition to the above mentioned polymers, the pressure sensitive adhesives typically comprise one or more additional constituents including, for example, tackifying resins, waxes, and plasticizers as wells as one or more additives such as, for example, UV-light absorption agents, UV- and heat stabilizers, optical brighteners, pigments, dyes, and desiccants.

[0119] Hot-melt adhesives are solvent free adhesives, which are solid at room temperature and which are applied to the substrate to be bonded in form of a melt. After cooling the adhesive solidifies and forms an adhesive bond with the substrate through physically and / or chemically occurring bonding. Suitable hot-melt adhesives include, for example, polyolefin-based hot-melt adhesives, in particular those based on amorphous polyolefins (APO) and amorphous poly-alpha-olefins (APAO), thermoplastic copolymer-based hot-melt adhesives, in particular those comprising copolymers ethylene and vinyl acetate (EVA) or polyamide as the main polymer component, and polyurethane-based hot-melt adhesives. In addition to the above mentioned polymers, suitable hot-melt adhesive compositions typically comprise one or more additional constituents including, for example, resins and waxes as well as one or more additives such as, for example, UV-light absorption agents, UV- and heat stabilizers, optical brighteners, pigments, dyes, and desiccants.

[0120] In further embodiments, the damping element further comprises a constraining layer.

[0121] In case the damping element comprises an adhesive layer, the constraining layer is situated on the side of the damping layer that is opposite to the adhesive layer, i.e. the damping layer is sandwiched between the adhesive layer and the constraining layer. Damping elements according to this embodiment are generally known as “constrained layer dampers”.

[0122] A cross-section of a damping element comprising a damping layer (2), an adhesive layer (3), and a constraining layer(4) is shown in figure 2.

[0123] In exemplary embodiments, the constraining layer is a metal sheet, preferably aluminum or steel sheet or a polymeric sheets, preferably glass fiber reinforced polymer sheet. The thickness of the constraining layer is not particularly restricted but the use of constraining layers that are thinner than the damping layer may be preferred. Preferred thickness also depends on the material of the constraining layer. In one embodiment, the constraining layer has a thickness of 0.05 - 1.5 mm, preferably 0.1 - 1.25 mm, more preferably 0.1 - 1.0 mm. In one exemplary embodiment, the constraining layer is a metal sheet having a thickness of 0.05 - 0.5 mm, preferably 0.05 - 0.4 mm or a polymeric sheet having a thickness of 0.1 - 1.2 mm, preferably 0.25 - 1 .0 mm.

[0124] Especially the constraining layer may have an elastic modulus, which is higher than that of the damping layer, such larger by at least the factor 3, preferably at least the factor 5, more preferably at least a factor of 10, wherein the elastic modulus is measured by using the method as defined in ISO 6892-1 :2016 standard (for metallic sheets) or as defined in ISO 527-2 standard (for polymeric sheets).

[0125] Another subject of the present invention is a method for producing a damping element as discussed above, the method comprising steps of: i) Providing damping layer composed of the acoustic damping material of the present invention, ii) Optionally applying an adhesive composition to an upper or lower major surface of the damping layer, and iii) Optionally cutting the composite element provided in step i) or ii) to a predetermined length and / or width.

[0126] The damping layer can be provided by mixing the constituents of the acoustic damping material at an elevated temperature until a homogeneously mixed mixture is obtained followed by processing the homogeneously mixed mixture into a form of a shaped article.

[0127] The term “homogeneously mixed mixture” refers in the present disclosure to compositions, in which the individual constituents are distributed substantially homogeneously in the composition. Furthermore, a homogeneously mixed mixture can be multi-phase mixture. For example, a homogeneously mixed mixture of a polymer component and a filler component, therefore, refers to composition in which the constituents of the filler phase are homogeneously / uniformly distributed in the polymer phase. For a person skilled in the art it is clear that within such mixed compositions there may be regions formed, which have a slightly higher concentration of one of the constituents than other regions and that a 100 % homogeneous distribution of all the constituents is generally not achievable. Such mixed compositions with "imperfect" distribution of constituents, however, are also intended to be included by the term "homogeneously mixed mixture" in accordance with the present invention.

[0128] Any conventional type of a m ixing apparatus can be used for m ixing of the constituents of the acoustic damping material. The mixing step can be conducted as a batch process using a conventional batch-type mixer, such as a Dreis mixer, a Brabender mixer, a Banbury mixer, or a roll mixer or as a continuous process using a continuous- type mixer, such as an extruder, in particular a single-, a twin-screw extruder or a planetary roller extruder. It may be advantageous to heat the constituents before or during mixing, either by applying external heat sources or by friction generated by the mixing process itself, in order to facilitate processing of the constituents into a homogeneously mixed mixture by decreasing viscosities and / or melting of individual constituents.

[0129] The homogeneously mixed mixture of the constituents of the acoustic damping material can subsequently be processed into a form of a shaped article by using any conventional techniques, such as extruding, blow-molding, injection molding, compression molding, calendering, or hot-pressing techniques.

[0130] The adhesive composition can be applied to a surface of the damping layer using any conventional techniques in step ii) of the method. The details of the application step depend on the type of the adhesive composition. For example, the adhesive composition can be applied on the surface of the sheet by nozzle extrusion, powder dispersion, hot-melt calendaring, or by spray lamination techniques. In case of a hot- melt adhesive or a hot-melt pressure sensitive adhesive, the adhesive composition is first heated to an elevated application temperature above the softening point (Ts) of the adhesive before being applied to the surface of the damping layer.

[0131] Step iii) of the method for producing a damping element can be conducted, for example, by punch or die cutting.

[0132] Still another subject of the present invention is a method for preparing a vibration and / or noise damped system comprising a structure having a noise emitting surface, the method comprising steps of:

[0133] I) Providing a damping element of the present invention,

[0134] II) Applying the damping element to the noise emitting surface.

[0135] In embodiments, the structure having a noise emitting surface is part of a transportation vehicle or a white good.

[0136] In embodiments, the damping element comprises a damping layer and an adhesive layer covering at least a portion of an upper or lower major surface of the damping layer and step II) of the method comprises:

[0137] Ila) Contacting the outer major surface of the adhesive layer with the noise emitting surface and applying sufficient pressure to form an adhesive bond between the noise emitting surface and the damping layer or lib) Heating the adhesive layer and / or the substrate and contacting the outer major surface of the adhesive layer with the noise emitting surface and forming an adhesive bond between the noise emitting surface and the damping layer by cooling of the adhesive layer.

[0138] The term “outer major surface” of the adhesive layer refers to the major surface of the adhesive layer facing away from the damping layer.

[0139] Still another subject of the present invention is a vibration and / or noise damped automotive system comprising a vehicle structure (5) having a noise emitting surface (6) and an automotive damping element (1 ) as discussed above, wherein least a portion of the damping layer (2) is adhered to the noise emitting surface (6) of the vehicle structure (5), and wherein said vehicle structure (5) having the noise emitting surface (6) is preferably part of a transportation vehicle or a white good.

[0140] In embodiments, the least a portion of the damping layer is adhered to the noise emitting surface (6) of the vehicle structure (5), wherein said vehicle structure (5) is selected from vehicle panels, floors, engine compartments, passenger compartments, and vehicle body components, excluding road construction and pavement applications.

[0141] In embodiments, the damping layer (2) is adhered to the noise emitting surface (6) via an adhesive layer (3). A cross-section of such vibration and / or noise damped system is shown in figure 3.

[0142] Examples

[0143] The followings products shown in Table 1 were used in the examples.

[0144] Table 1 Preparation of damping layers

[0145] Damping layers having the compositions of Table 2 were prepared according to the following procedure.

[0146] In a first step, the polymerized CNSL, natural bitumen, thermoplastic polymers, and tackifying resins were mixed in a batch type mixer until a homogeneously mixed mixture was obtained. After this, the remaining components of the acoustic damping material were added and the mixing was continued until a homogeneously mixed mixture was obtained. The thus obtained mixture was processed into sheets having a thickness of ca. 2.5 mm by using a conventional calendering apparatus.

[0147] A standard acoustical bitumen sheet SikaDamp- F04 LA20 (from Sika AG) was used as a reference example Ref-1 .Measurement of density

[0148] The densities of the prepared damping layers were measured according to EN ISO 1183-1 :2019 standard using a water immersion method (Archimedes principle) in deionized water and a precision balance to measure the mass of the test specimens. Mandrel bending

[0149] Mandrel bending test was conducted using a cylinder having an outer diameter of 30 mm. In the bending test, the damping layers were first stored 2 hours at a temperature of 15 °C with a relative humidity of 50 %. The damping layers were then bended around the cylinder and the presence of cracks was observed visually without using optical eguipment, such as a microscope. In case no cracks were observed, the result of the mandrel bending test was recorded as “Ok”. Heat resistance

[0150] The heat resistance test at 160 °C was performed according to the BMW group standard, Adhesives and sealing materials used in the body shop Damping pad, Reguirements and testing, GS 97028-16:2012-02 page 4, Table 1 : Resistance to high temperature ("Warmetest"), AA-0415, edition 2018-10. The test samples had a length I width of 16 cm x 7 cm. Loss factor

[0151] Test specimens having suitable dimensions were obtained from the previously prepared damping layers by cutting or die cutting. One of the major surfaces of each test specimen was coated with a layer of pressure sensitive acrylate-based adhesive. The adhesive layer had a thickness of 50 pm. The loss factors for the test specimen were determined by using the measurement method as defined in ISO 6721 standard. The measurements were conducted using a commercially available loss factor tester at a temperature in the range of from -20 to 60 °C. The values of the loss factor at the frequency of 200 Hz were obtained from the measured values of the loss factor value by mathematical means.

[0152] Measured values obtained with reference and exemplary damping layers are shown in Table3.

[0153] TERMINOLOGY CLARIFICATION

[0154] For clarity, it should be understood that the following terms are used interchangeably throughout this specification and refer to the same component:

[0155] - "Polymerized cashew nut shell liquid P" as used in the claims

[0156] - "Polymerized CNSL" as used in the specification

[0157] Also the terms

[0158] - "CNSL" as used in the examples

[0159] - "Cashew nut shell liquid" as used in various sections refer to the same component.

[0160] All these terms refer to the (polymerized) cashew nut shell liquid component that forms part of the acoustic damping material according to the present invention. The abbreviation "CNSL" stands for "Cashew Nut Shell Liquid" and may be used with or without explicit reference to its polymerized state, but it might refer to the polymerized form. Table 2

[0161] 'Standard acoustical bitumen sheet

[0162] Table 3

[0163] 'Standard acoustical bitumen sheet

Claims

Claims1 . A sustainable acoustic damping material for automotive vibration damping applications comprising: Polymerized cashew nut shell liquid P, a. At least one natural bitumen NB, b. Optionally at least one thermoplastic polymer TP, and c. At least 15 wt.-%, preferably at least 25 wt.-% of a solid particulate filler component F.

2. The acoustic damping material according to claim 1 , wherein the polymerized cashew nut shell liquid P has been obtained by using a method comprising subjecting raw or technical cashew nut shell liquid (CSNL) to a heat treatment under reflux to obtain the polymerized CNSL composition.

3. The acoustic damping material according to claim 1 or 2, wherein the at least one natural bitumen NB is selected from gilsonite, grahamite, uintahite, glance pitch, asphaltic pyrobitumen, and non-asphaltic pyrobitumen, preferably gilsonite, and wherein the natural bitumen NB is distinguished from petroleum- derived asphalt by being naturally occurring semisolid or solid mixtures formed by conversion of crude oil over time.

4. The acoustic damping material according to any one of previous claims, wherein the at least one natural bitumen NB has a content of asphaltenes of at least 25 wt.-%, preferably at least 35 wt.-%.

5. The acoustic damping material according to any one of previous claims, wherein the sum of the proportions of a) and b) makes up 10 - 50 wt.-%, more preferably 30 - 45, more preferably 25 - 45 wt.-%, more preferably 30 - 45 wt.-% of the total weight of the acoustic damping material.

6. The acoustic damping material according to any one of previous claims, wherein the weight ratio of the amounts of a) and b) is in the range of 0.25 - 1.5, more preferably 0.45 - 1.25, more preferably 0.5 - 1.0, even more preferably 0.7 - 0.9.

7. The acoustic damping material according to any one of previous claims further comprising at least one tackifying resin TR and / or at least one wax W.

8. The acoustic damping material according to any one of previous claims comprising 0.5 - 20 wt.-%, preferably 1 - 15 wt.-% of the at least one tackifying resin TR.

9. The acoustic damping material according to any one of previous claims, wherein the at least one thermoplastic polymer TP is selected from ethylene vinyl acetate copolymers, polyethylenes, ethylene copolymers, polypropylenes, propylene copolymers, and styrene block copolymers.

10. The acoustic damping material according to any one of previous claims comprising 25 - 75 wt.-%, preferably 35 - 65 wt.-%, more preferably 40 - 65 wt.-%, even more preferably 45 - 60 wt.-% of the solid particulate filler component F.11 . The acoustic damping material according to any one of previous claims, wherein the solid particulate filler component F comprises at least one mineral filler F1 and / or at least one cellulose-containing filler F2, preferably composed of wood particles.

12. The acoustic damping material according to claim 11 , wherein the solid particulate filler component F comprises or is composed of the at least one mineral filler F1 and the at least one cellulose-containing filler F2, wherein the weight ratio of the amount of the at least one mineral filler F1 to the amount of the cellulose-containing filler F2 is in the range of from 10:1 to 1 :1 , preferably from 7:1 to 2:1.

13. An automotive damping element (1 ) for vibration and noise damping in transportation vehicles comprising: i) A damping layer (2) composed of the acoustic damping material according to any one of claims 1 -12 and ii) Optionally an adhesive layer (3) for bonding to vehicle structures.

14. A method for preparing a vibration and / or noise damped automotive system comprising a vehicle structure having a noise emitting surface, the method comprising steps of:I) Providing an automotive damping element according to claim 13,II) Applying the damping element to the noise emitting surface of the vehicle structure.

15. A vibration and / or noise damped automotive system comprising a vehicle structure (5) having a noise emitting surface (6) and an automotive damping element (1 ) according to claim 13, wherein least a portion of the damping layer(2) is adhered to the noise emitting surface (6) of the vehicle structure (5), wherein said vehicle structure (5) is selected from vehicle panels, floors, engine compartments, passenger compartments, and vehicle body components, excluding road construction and pavement applications.

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