A sound insulating resilient layer

Abstract

According to an example aspect of the present invention, there is provided a sound insulating resilient layer comprising a three-dimensional fibre network. The three-dimensional fibre network comprises a fibrous cellulosic and / or lignocellulosic material, the thickness of the resilient layer may range from 1 to 20 mm, and the dynamic stiffness of the resilient layer may be below 200 MN / m3.

Description

A SOUND INSULATING RESILIENT LAYERFIELD

[0001] The present invention belongs to the field of construction materials. More specifically, it relates to the field of acoustic materials and sound insulation.BACKGROUND

[0002] Quiet living spaces is one of the most important factors on living comfort. Soundwaves can travel through air (airborne sounds) or through building structures (impact sounds). Impact sounds are typically caused by impacts on the floor, such as footsteps or dropping of a load. Vibration caused by impact travel easily via floor structures to adjacent rooms and floors causing significant disturbances. Effective impact sound insulation is therefore needed to minimize noise propagation.

[0003] A typical floor structure comprises a walkable floor covering on a loadbearing floor. In between these layers, an additional layer may be introduced for sound insulation and / or underfloor heating purposes. This additional layer may comprise for example a sound insulating underlay (Figure 1) or a floating floor layer and an impact sound insulation layer (Figure 2). In a multi-storey building, a typical floor structure between storeys comprises a walkable floor covering on a floating floor layer and underneath an impact sound insulation layer before the load-bearing floor.

[0004] Typically, impact sound insulation of a floating floor is achieved with plastic materials or mineral wools that are placed underneath the walkable floor covering or between a load-bearing floor and a floating floor layer. Such materials are not desirable due to the increasing awareness of environmental and sustainability issues.SUMMARY OF THE INVENTION

[0005] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0006] According to a first aspect of the present invention, there is provided a sound insulating resilient layer comprising a three-dimensional fibre network, wherein the three- dimensional fibre network comprises a fibrous cellulosic and / or lignocellulosic material, the thickness of the sound insulating resilient layer ranges from 1 to 20 mm, and the dynamic stiffness of the sound insulating resilient layer is below 200 MN / m3.

[0007] According to a second aspect of the present invention, there is provided a sound insulating resilient layer comprising a three-dimensional fibre network wherein the three-dimensional fibre network comprises a fibrous cellulosic and / or lignocellulosic material, the thickness of the sound insulating resilient layer ranges from 10 to 120 mm, and the dynamic stiffness of the sound insulating resilient layer is below 30 MN / m3.

[0008] According to a third aspect of the present invention there is provided a sound insulating element comprising at least one sound insulating resilient layer according to the first or the second aspect and a walkable floor covering (1) or a floating floor layer (4), wherein the sound insulating resilient layer is attached to the walkable floor covering or the floating floor layer.

[0009] According to a fourth aspect of the present invention, there is provided use of the sound insulating resilient layer according to the first or the second aspect as a sound insulating underlay element or as a part thereof between a load-bearing floor (3) and a walkable floor covering (2) laid thereover.

[0010] According to a fifth aspect of the present invention, there is provided a use of the sound insulating resilient layer according to the first or the second aspect as an impact sound insulation layer between a load-bearing floor (3) and a floating floor layer (4).

[0011] Advantages of the invention

[0012] One advantage of the present invention is that the sound insulating resilient layer is biodegradable.

[0013] Another advantage of the present invention is that the sound insulating resilient layer is light weighed.

[0014] Another advantage of the invention is that he sound insulating resilient layer can easily be handled without the layer falling apart or crumbling.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIGURE 1 illustrates an example floor structure consisting of a walkable floor covering (1), a sound insulating resilient layer (2), and a load-bearing floor (3).

[0016] FIGURE 2 illustrates an example floor structure consisting of a walkable floor covering (1), a floating floor layer (4), a sound insulating resilient layer (2), and a load-bearing floor (3).

[0017] FIGURE 3 illustrates an example floor structure consisting of a walkable floor covering (1), a sound insulating resilient layer (2), a floating floor layer (4), a sound insulating resilient layer (2), and a load-bearing floor (3).

[0018] FIGURE 4 illustrates impact sound improvement AL for 14 mm wooden parquet with 3 mm sound insulating resilient layer. Dots illustrate a reference material and dotted line illustrates a fibrous cellulosic material.

[0019] FIGURE 5 illustrates impact sound improvement AL for 40 mm cement screed with 30 mm sound insulating resilient layer. Dots illustrate a reference material and dotted line illustrates a fibrous cellulosic material.EMBODIMENTS

[0020] In the present context, the term “fibrous cellulosic material” or “cellulosic fibres” typically refers to cellulosic and / or lignocellulosic fibres.

[0021] Unless otherwise stated herein or clear from the context, the term “fibres” refers to cellulosic and / or lignocellulosic fibres.

[0022] In the present context, the term “dynamic stiffness” refers to the material’s elastic properties under an external oscillatory load. Dynamic stiffness is typically measured according to the standards ISO 9052-1 and ISO 7626-5.

[0023] In the present context, the term “resonance frequency” refers to the oscillation of a system at its natural or unforced resonance. Resonance frequency is sometimes referred to with the terms “natural frequency” or “eigenfrequency”, which can be used interchangeably.

[0024] In the present context, the term “walkable floor covering” refers to any material or layer that may be installed as the top layer of a floor structure to provide a walking surface. Non-limiting examples of walkable floor coverings include for example hardwood flooring, engineered wood flooring, laminate flooring, tiles, carpets, vinyl flooring, stone flooring, terrazzo flooring, linoleum flooring and various seamless chemical floor coatings. The walkable floor covering may be installed so that the floor covering is not secured to the layers below it, for example by means of glue, nails, or staples, but the walkable floor covering lies on top of the layer beneath it. A walkable floor covering that has been installed with such method is in some cases referred to with the term “floating floor”, but in the present context, the term “floating floor layer” does not refer to a walkable floor covering. The term “floating floor layer” has been defined below. In other embodiments, the walkable floor covering may be installed and / or secured to the layers below it directly, for example by means of glue, nails, or staples.

[0025] In the present context, the term “load-bearing floor” refers to a structure that transfers the load of a floor to the foundation of a building or to surrounding building structures. Load-bearing floor may be the bottom layer of a floor structure. In other examples, additional structures, such as at least one gypsum board, may be installed below the load-bearing floor. Typically, a load-bearing floor is situated underneath a sound insulating resilient layer.

[0026] In the present context, the term “floating floor layer” refers to the structural layer, which may be installed on top of a sound insulating resilient layer. A floating floor layer is typically a lightweight construction where chipboard, gypsum or cement fibre board floor panels are ‘floated’ across the top of the rigid insulation layer. ‘Floating’ refers to an installation method where the layer is not secured to the layer beneath it, for example by glue, nails, or staples, but the floating floor layer lies on top of the layer beneath it. Typically, a walkable-floor covering is installed on top of the floating floor layer.

[0027] A structure comprising a load-bearing floor, a sound insulating resilient layer and a floating floor layer is typically situated between stories in a building with two ormore stories. In such buildings, a more stringent sound insulation is required and thus the combination of a sound insulating resilient layer and a floating floor layer may be advantageous in buildings with multiple storeys. When the sound insulating resilient layer is installed between a load-bearing floor and a floating floor layer, the sound insulation resilient layer must have a certain thickness so that it is adequate to insulate impact sounds between floors and / or rooms.

[0028] In the present context, the term “resilient” [resilient layer, resilience] refers to the flexible and / or elastic properties of a material. A resilient layer is flexible and / or elastic layer.

[0029] In the present context, the term “fibrous material” or “fibrous cellulosic material” or “cellulosic fibres” or “fibrous lignocellulosic material “typically refers to cellulosic and / or lignocellulosic fibres. Such fibres may be of plant origin.

[0030] In the present context, the term “fibre length” refers to the distance measured along the longest dimension of the fibre. The length can be measured for example, by optical methods, such as by FS5 fibre analyser in compliance with ISO 16065-2 standard.

[0031] The term “fibre width” refers to the dimension perpendicular to the greatest dimension, i.e. the length. The width can be measured for example by optical methods, such as by FS5 fibre analyser in compliance with ISO 16065-2 standard.

[0032] The present disclosure provides a sound insulating resilient layer suitable for being used between a load-bearing floor and a walkable floor covering or between a loadbearing floor and a floating floor layer. The sound insulating resilient layer may act as a sound insulating underlay when used between a load-bearing floor and a walkable floor covering (Figure 1). In other examples, the sound insulating resilient layer may act as an impact sound insulation layer when used between a load-bearing floor and a floating floor layer (Figure 2). In some examples, the sound insulating resilient layer may be installed between a load-bearing floor and a walkable floor covering and between a load-bearing floor and a floating floor layer (Figure 3).

[0033] The sound insulating resilient layer disclosed herein comprises a three- dimensional fibre network and the three-dimensional fibre network comprises a fibrous cellulosic and / or lignocellulosic material. Resilience of the layer is important to ensure good acoustic decoupling between a floating floor layer and a load-bearing floor orbetween a walkable floor covering and a load-bearing floor. The sound insulating resilient layer may in some examples improve impact sound insulation of a floor structure. Such impact sounds may be caused for example by walking or running on the floor, dropping of loads, cleaning, moving furniture, children or pets. The aim of an impact sound insulation layer is to reduce the impact sound transmitted to a load-bearing floor and / or to surrounding building structures. Resilience of the sound insulating layer improves impact sound insulation especially above the resonance frequency of a floating floor. Thus, the sound insulating resilient layer may act as an efficient impact sound insulation layer.

[0034] Performance of a floor structure in impact sound insulation is defined as an impact sound improvement (AL). Impact sound improvement is calculated as the difference of impact sound level of a load-bearing floor without additional floor layers and with additional floor layers, such as a resilient sound insulating layer and a floating floor layer or a walkable floor covering. Impact sound improvement AL is a frequency dependent quantity and is usually measured in the frequency range 100 to 3150 Hz or 50 to 5000 Hz.

[0035] One aspect of the present disclosure is a sound insulating resilient layer with thickness ranging from 1 to below 20 mm, and the dynamic stiffness of the resilient layer being below 200 MN / m3.

[0036] In some embodiments, the thickness of the sound insulating resilient layer may range from 1 to 15 mm, more preferably from 2 to 10 mm, such as from 3 to 5 mm. The thickness of the sound insulating resilient layer may in other embodiments be for example 3.5 mm or 4 mm, such as below 5 mm. Sound insulating resilient layer with thicknesses ranging from 1 to below 20 mm may be in some preferred embodiments used as a sound insulating underlay below a walkable floor covering. Thicknesses ranging from 1 to below 20 mm are in some occasions referred to as a “thinner layer” in the present context.

[0037] The dynamic stiffness of a sound insulating resilient layer with thickness ranging from 1 to below 20 mm may be below 150 MN / m3, for example between 30 to 100 MN / m3or between 50 to 80 MN / m3. In other embodiments, dynamic stiffness of the resilient layer may be below 75 MN / m3, for example below 70 MN / m3or below 60 MN / m3. In some embodiments, the dynamic stiffness of a sound insulating resilient layerwith thickness ranging from 1 to below 20 mm may be in the range of 100 to 200 MN / m3, such as in the range of 110 to 190 MN / m3, or 110 to 150 MN / m3, or above 100 MN / m3.

[0038] In some embodiments, the dynamic stiffness of the sound insulating resilient layer may be between 30 to 100 NM / m2, or in the range of 50 to 80 NM / m2, and the thickness of the sound insulating resilient layer may range from 3 to 5 mm.

[0039] The resonance frequency of the thinner layer may in some embodiments, be below 100 Hz, such as below 80 Hz, or below 60 Hz when measured according to ISO 9052-1 :1989.

[0040] Another aspect of the present disclosure is a sound insulating resilient layer with thickness ranging from 20 to 120 mm and dynamic stiffness of the resilient layer being below 30 MN / m3. In some embodiments the thickness of the sound insulating resilient layer may range from 25 to 100 mm, more preferably from 30 to 80 mm, for example from 50 to 80 mm. A sound insulating resilient layer with thicknesses ranging from 20 to 120 mm may be in some preferred embodiments used as an impact sound insulation layer below a floating-floor layer. Thicknesses ranging from 20 to 120 mm are in some occasions referred to as “thicker layer” in the present context.

[0041] In some embodiments, the thickness of the sound insulating resilient layer may range from 30 to 80 mm and the density of the sound insulating resilient layer may range from 40 to 80 kg / m3.

[0042] The dynamic stiffness of a sound insulating resilient layer with thickness ranging from 20 to 120 mm may be below 20 MN / m3, or below 15 MN / m3, for example above 5 MN / m3. In some preferred embodiments the dynamic stiffness of a sound insulating resilient layer with thickness ranging from 20 to 120 mm may be about 10 MN / m3, for example ranging from 5 to 15 MN / m3.

[0043] The resonance frequency of the thicker layer may in some embodiments be below 30 Hz, such as below 25 Hz when measured according to ISO 9052-1 : 1989.

[0044] The sound insulating resilient layer may in some embodiments be provided in a form of a sheet or a board. Preferably the “sheet” or the “board” has two opposite planar surfaces which are generally orientated in parallel. The term “board” or “sheet” may refer to a separate, discrete object or to a layer that forms an integral part of a larger object. Insome embodiments the “board” or “sheet” may be stiff. Such stiff structure may provide mechanical support to the floor structure. In other embodiments, the “board” or “sheet” may be flexible so that it can be rolled. Rollable structure may allow easier handling, for example during transportation and storage.

[0045] In some embodiments, the sound insulating resilient layer may be arranged under a floating floor layer. In other embodiments, the sound insulating resilient layer may be arranged under a walkable floor covering. In other examples, the sound insulating resilient layer may be arranged between a load-bearing floor and a walkable floor covering. In some preferred embodiments, a first layer of the sound insulating resilient layer is arranged between a floating floor layer and a walkable floor covering and a second layer of the sound insulating resilient layer is arranged between a load-bearing floor and a floating floor layer (Figure 3). In such arrangement, the first layer of the sound insulating resilient layer is typically thinner than the second layer. For example, the thickness of the first layer may be from 1 to 10 mm and the thickness of the second layer may be from 30 to 80 mm.

[0046] The term “cellulosic material” may refer to both or either of cellulosic and lignocellulosic materials. In some embodiments, the fibrous cellulosic and / or lignocellulosic material may be selected from bleached or unbleached chemical pulp, such as bleached or unbleached softwood chemical pulp and / or bleached or unbleached hardwood chemical pulp, or sawdust. In some preferred embodiments, the fibrous cellulosic and / or lignocellulosic material may be selected from chemical pulp, mechanical pulp, for example bleached chemi-thermomechanical pulp (BCTMP), or non-wood pulp. In other embodiments, the fibres comprise semi-chemical pulp, thermomechanical pulp, or recycled pulp. In some embodiments, the pulp may be made from any broad-leaved tree such as a tree from the betulaceae family, for example birch or aspen, from the salicaceae family, from eucalyptus, mixed tropical hardwood or pines or from any combination of the aforementioned. The pulp may be also made from any conifer such as spruce or pine or from any combination thereof. The pulp may be also made from a combination of broadleaved trees and conifers. In another embodiment, the pulp may be made from any annuals such as straw, common reed, reed canary grass, bamboo, sugarcane, bagasse or any grass plant.

[0047] The sound insulating resilient layer may comprise in some embodiments at least 50 wt%, such as at least 60 wt%, for example at least 75 wt%, or at least 80 wt%, ofthe fibrous cellulosic and / or lignocellulosic material calculated from the dry weight of the layer. In preferred embodiments, the resilient layer may comprise for example at least 85 wt%, 90 wt%, 95 wt% or 98 wt% of the fibrous cellulosic and / or lignocellulosic material calculated from the dry weight of the layer. In some embodiments, the sound insulating resilient layer may consist of the fibrous cellulosic and / or lignocellulosic material.

[0048] The fibre length of the fibrous cellulosic material may in one example be larger than 0.5 mm, in another example less than 10 mm, such as 0.5 to 5 mm, for example 1 to 5 mm. In some embodiments, the fibre length of the fibrous cellulosic material may be less than 5 mm, for example in the range of 0.3-3 mm, such as in the range of 0.7-3 mm. All fibre lengths disclosed herein are fibre lengths obtainable with Valmet MAP according to ISO 16065-2 standard. Fibre below 5 mm may allow even distribution of the cellulosic material throughout the insulating resilient layer.

[0049] In some embodiments, the fibre width of the fibrous cellulosic and / or lignocellulosic material may be in the range of 5 to 50 pm, such as in the range of 10 to 30 pm. In some embodiments, at least 90 wt%, or at least 95 wt%, of the fibres in the three- dimensional fibre network may have fibre width in the range of 10 to 30 pm. In some embodiments, the diameter of fibres of the fibrous cellulosic and / or lignocellulosic material may range from 5 to 50 pm, preferably from 10 to 30 pm. In some embodiments, the diameter of at least 90 wt%, or at least 95 wt-% of the fibres in the three-dimensional fibre network may be in the range of 10 to 30 pm. Such fibre width and / or diameter provides a large contact surface which may allow for example good contact between the cellulosic and / or lignocellulosic fibres and additives, such as bicomponent fibres, in the material. This may lead in improved properties of the material, such as improved strength.The term “fibre length” refers to the distance measured along the longest dimension of the fibre.

[0050] In some embodiments, the sound insulating resilient layer may comprise a coating layer on at least one of its surfaces. The coating layer may comprise for example paper, cardboard, a resin, a hydrophobic agent, a thermoplastic material. Preferably, the thickness of the coating layer is less than 5 mm or less than 3 mm, such as ranging from 0.1 to 2 mm, for example ranging from 0.2 to 1 mm or from 0.3 to 0.5 mm. In one embodiment, the thickness of the coating layer is 0.1 to 0.4 mm. The advantage of having such coating layer is that it may provide mechanical strength or may serve as a structuralcomponent of the sound insulating resilient layer. The coating layer may in addition provide functional properties to the sound insulating resilient layer.

[0051] The sound insulating resilient layer may further comprise one or more additive chemicals. The additive chemicals may be selected from flame-retardants, foaming agents, mould inhibitors, barrier agents, binding agents, or combinations thereof. Preferably, the amount of such additives is below 40 wt% of the dry weight of the fibrous cellulosic and / or lignocellulosic material, such as below 30 wt% below 20 wt% or below 10 wt% of the dry weight of the fibrous cellulosic and / or lignocellulosic material. In one example, the additive chemical may be mixed to the fibrous cellulosic and / or lignocellulosic material prior to forming the three-dimensional fibre network. In other embodiments, the additive may be applied to the three-dimensional fibre network after forming such network. Application after forming the three-dimensional fibre network may in some embodiments comprise spraying the additive to the surface of the fibre network.

[0052] In some embodiments, the sound insulating resilient layer may comprise a binding composition. A binding composition is preferably a composition that allows connecting the cellulosic and / or lignocellulosic fibres in the fibre network to each other. For example, the binding composition may comprise a binding polymer. The binding polymer may comprise for example a polyester, such as polybutylene terephthalate and polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations thereof.

[0053] The binding composition may be provided for example in the form of a powder, an aqueous dispersion, an aqueous suspension or water solution during the manufacture of the sound insulating resilient layer, such as during formation of the fibre network. Preferably, the sound insulating resilient layer comprises less than 20 wt% of the binder composition, calculated from the dry weight of the sound insulating resilient layer. In some preferred embodiments, the sound insulating resilient layer may comprise 5 wt % of less, such as less than 5 wt%, or in the range of 0.5 to 4.5 wt%, of the binding composition of the dry weight of the sound insulating resilient layer.

[0054] The binding composition or at least part of the binding composition may be formulated to melt upon heating. Preferably the melting point of the binding composition is less than 250 °C, such as less than 220 °C, such as less than 200 °C, such as less than 150 °C, or in the range 60 to 220 °C.

[0055] The binding composition may for example comprises or consists of bicomponent fibres, such as bicomponent polymer fibres. A bicomponent fibre is a fibre that combines two separate polymers, such as a first component and a second component, into a single filament. The two polymers may be arranged in bicomponent fibres in various ways, for example side-by-side, as a sheath-core structure, as a segmented structure or as a so-called islands-in-the-sea -structure, where one polymer surrounds several separate sections of the other polymer.

[0056] The first component may comprise a different polymer than the second component. In some embodiments, the molecular weight of the first component differs from the molecular weight of the second component. The polymers for the first component and the second component may be selected from polyesters, such as polybutylene terephthalate and polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations thereof. In some embodiments, both components comprise, independently from each other, a thermoplastic polymer. In some embodiments, the first component comprises cellulose and the second component comprises a thermoplastic polymer.

[0057] In some embodiments, the bicomponent fibre has a sheath-core structure. A sheath-core structure refers to a structure wherein the polymer(s) used in the corecomponent are completely surrounded by sheath-component(s). The sheath-component may in some examples comprise a different polymer than the core-component. In other embodiments, the molecular weight of the sheath-component differs from the molecular weight of the core-component. The polymers for the sheath-component and the corecomponent may be selected from polyesters, such as polybutylene terephthalate and polyethylene terephthalate, polylactic acid, polyethylene, polypropylene or combinations thereof. In some preferred embodiments, the sheath-component is a thermoplastic polymer. The core component may comprise cellulose. In some embodiments, the core component may comprise a thermoplastic polymer.

[0058] The sound insulating resilient layer may comprise a bicomponent fibre having a sheath-core structure, such as a bicomponent fibre in which the core component comprises cellulose and the sheath component comprises a thermoplastic polymer.

[0059] The melting point of the bicomponent fibre may be less than 250 °C, such as less than 220 °C, such as less than 200 °C, such as less than 150 °C, or in the range 60 to 220 °C. In some preferred embodiments where the bicomponent fibres have a sheath-corestructure, the melting point of the sheath-component is lower than the melting point of the core-component. Preferably, the differences between the melting point of the sheathcomponent and the melting point of the core-component enables melting of the sheathcomponent while the core-component remains in solid form. The melted sheath-component may bond the fibres of the sound insulating resilient layer together to form a fibre net, while the core-component remains intact and provides structural support.

[0060] It is possible to use any bicomponent fibre arrangements that provide a similar effect in which one component of the bicomponent fibre melts, connecting the cellulosic fibres together, and the other component remains intact, providing structural support to the formed fibre network.

[0061] The sound insulating resilient layer may comprise 2 to 20 wt%, such as 5 to 15 wt%, of bicomponent fibres calculated from the dry weight of the sound insulating resilient layer. In some embodiments, the sound insulating resilient layer may comprise less than 5 wt%, such as 2 to 5 wt%, or 0.5 to 4.5 wt% of bicomponent fibres of the dry weight of the sound insulating resilient layer. It has been surprisingly been observed, that such low amount of bicomponent fibres may be sufficient for forming a sound insulating resilient layer according to at least some embodiments of the present disclosure. It is assumed that providing a relatively low bicomponent fibre concentration may provide a material in which the ratio of cellulose fibre and bicomponent fibre is compatible. Cellulose fibres are relatively stiff whereas bicomponent fibres are relatively flexible, especially upon heating. The difference in the properties of these two fibre types may at least in some embodiments provide advantageous conditions for binding of cellulosic fibres and bicomponent fibres even at low bicomponent fibre concentrations.

[0062] The bicomponent fibre may affect the mechanical properties of the sound insulating resilient layer. The bicomponent fibre may for example improve the strength and / or stiffness of the material. The bicomponent fibre may in some embodiments affect the sound insulating properties of the resilient layer, for example by reducing or increasing the dynamic stiffness of the material.

[0063] In an embodiment, the sound insulating resilient layer may comprise at least one flame retardant, which may be selected from the following group: minerals, organohalogen compounds, organophosphorus compounds, inorganic phosphorus compounds, and organic compounds, and combinations thereof.

[0064] Examples of mineral flame-retardants include: aluminium trihydroxide (ATH), magnesium hydroxide (MDH), huntite and hydromagnesite, various hydrates, red phosphorus, and boron compounds, mostly borates.

[0065] Examples of organohalogen flame-retardants include: organochlorines such as chlorendic acid derivatives and chlorinated paraffins; organobromines such as decabromodiphenyl ether (decaBDE), decabromodiphenyl ethane (a replacement for decaBDE), polymeric brominated compounds such as brominated polystyrenes, brominated carbonate oligomers (BCOs), brominated epoxy oligomers (BEOs), tetrabromophthalic anyhydride, tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD).

[0066] Examples of organophosphorus flame-retardants include: organophosphates such as triphenyl phosphate (TPP), resorcinol bis(diphenylphosphate) (RDP), bisphenol A diphenyl phosphate (BADP), and tricresyl phosphate (TCP); phosphonates such as dimethyl methylphosphonate (DMMP); and phosphinates such as aluminium diethyl phosphinate. In one embodiment, the flame retardant comprises both phosphorus and a halogen, for example tris(2, 3 -dibromopropyl) phosphate (brominated tris) and chlorinated organophosphates such as tris(l,3-dichloro-2-propyl)phosphate (chlorinated tris or TDCPP) and tetrakis(2-chlorethyl)dichloroisopentyldiphosphate (V6).

[0067] Examples of inorganic phosphorus flame-retardants include ammonium polyphosphate (APP) and melamine polyphosphate (MPP).

[0068] Examples of organic flame-retardants include carboxylic acid and dicarboxylic acids.

[0069] The density of the sound insulating resilient layer may in some embodiment range from 30 to 150 kg / m3, preferably from 35 to 100 kg / m3, most preferably from 40 to 80 kg / m3. For example, the density of the sound insulating resilient layer may be about 50 kg / m3or about 80 kg / m3. In some embodiments the three-dimensional fibre network may be porous. A density below 80 kg / m3, for example below 60 kg / m3, may be preferable in some embodiments because the sound insulating resilient layer may in such cases be rollable, i.e. it can be rolled, which may allow for example easy transport and storage.

[0070] In some embodiments, the surface of the sound insulating resilient layer is substantially smooth and / or plain. In other words, the surface of the sound insulatingresilient layer does not have substantial deformations, such as pumps, holes, cavities and / or grooves.

[0071] In some embodiments, the three-dimensional fibre network may be formed from dry cellulosic and / or lignocellulosic material. In an embodiment, the sound insulating resilient layer or at least a fibrous part of it has been obtained by a web forming method, typically on a wire, such as dry forming (dry-laid process), air-laid process or foam forming or any combination thereof, preferably by an air-laid process or by dry forming. Advantages of using an air-laid or dry-laid process may be that the obtained sound insulation resilient layer is easier to handle, more homogeneous, less fragile and / or less prone to delamination.

[0072] In an embodiment, the sound insulating resilient layer or at least a fibrous part of it has been obtained by a mould-assisted forming method, such as by a foamforming method in a mould.

[0073] In some embodiments, the sound insulating resilient layer or at least a fibrous part of it may be obtained by continuous web forming or by mould-assisted forming.

[0074] In some embodiments, the sound insulating resilient layer or at least a fibrous part of it is formed from dry cellulosic material. For example, baled pulp or fluff pulp may be used as the cellulosic material, preferably baled pulp.

[0075] Preferably, the sound insulating resilient layer or at least a fibrous part of it is formed from dry pulp by an air-laid process.

[0076] In some embodiments, the three-dimensional fibre network may be formed on a wire, heat treated and calendered. The pressure applied during the calendering may at least in some embodiments be beneficial for producing a structure in which the amount of binding composition may be kept low.

[0077] In some embodiments, the sound insulating resilient layer may have been heat-treated. In some embodiments, the sound insulating resilient layer may have been heat-treated at a temperature of less than 220 °C, such as less than 200 °C, such as less than 150 °C, or in the range 60 to 220 °C, or in the range of 80 to 200 °C. Heat-treatment may be performed with an suitable technique, such as by using an oven.

[0078] Typically, the three-dimensional fibre network extends across the whole thickness of the sound insulating resilient layer, preferably with a substantially uniform distribution of the cellulosic fibres throughout the sound insulating resilient layer.

[0079] In another aspect of the disclosure, a sound insulating element comprising at least one sound insulating resilient layer as disclosed herein and a walkable floor covering and / or a floating floor layer is provided. The sound insulating resilient layer is attached to the walkable floor covering or the floating floor layer. Attaching may be achieved for example by using an adhesive or by other suitable means. The sound insulating element may comprise for example a walkable floor covering and the sound insulating resilient layer. In other embodiments, the sound insulating element may comprise a load-bearing floor and a sound insulating resilient layer or a floating floor layer and a sound insulating resilient layer.

[0080] Another aspect of the present disclosure, is a sound insulating system. The sound insulating system may comprise two or more sound insulating resilient layers. In some embodiments, the sound insulating system may comprise a first sound insulating resilient layer arranged between a floating floor layer and a walkable floor covering and a second sound insulating resilient layer arranged between a load-bearing floor and a floating floor layer. In such system, the first sound insulating resilient layer is typically thinner than the second sound insulating resilient layer. In some embodiments of the sound insulating system, the first sound insulating resilient layer may be according to the embodiments covering the thinner sound insulating resilient layer as disclosed herein, and the second sound insulating resilient layer may be according to embodiments covering the thicker sound insulating resilient layer as disclosed herein. For example, the thickness and the dynamic stiffness of the first sound insulating resilient layer may be 3 to 5 mm and 50 to 80 MN / m3respectively, and the thickness and the dynamic stiffness of the second sound insulating resilient layer may be 30 to 80 mm and 5 to 20 MN / m3, respectively. The density of the first and the second sound insulating resilient layers may range from 30 to 150 kg / m3, preferably from 35 to 100 kg / m3most preferably from 40 to 80 kg / m3.

[0081] The sound insulating element may comprise a walkable floor covering or a floating floor structure, and multiple sound insulating resilient layers. In particular, multiple sound insulating resilient layers, such as for example two layers, three layers, four layers or five layers, may in some embodiments be used to form a multilayer structure.Preferably, the thickness of an individual sound insulating resilient layer used in a multilayer structure may be below 10 mm, such as below 5 mm, or below 3 mm. The thickness of a sound insulating resilient layer may be for example 1 mm, 2 mm or 2.5 mm. In some embodiments, multiple sound insulating resilient layers may be arranged on top of each other.

[0082] The sound insulating element may further comprise one or more additional layers. The additional layer may comprise for example an adhesive, which joins two adjacent layers together. The additional layer may be arranged between the walkable floor covering and a sound insulating resilient layer, load-bearing floor and a sound insulating resilient layer or floating floor structure and a sound insulating resilient layer. In other embodiments, the additional layer may be arranged between two sound insulating resilient layers. In some embodiments, the sound insulating element comprises an additional layer between two, three, four or all layers of the sound insulating element.

[0083] The additional layer may comprise or consist of an adhesive resin. The adhesive resin may be provided in the form or a dry powder, for example as a hot melt adhesive, or as a liquid or as a combination thereof.

[0084] In another aspect of the invention, use of the sound insulating resilient layer as a sound insulating underlay element or as a part thereof between a load-bearing floor (3) and a walkable floor covering (1) laid thereover is provided.

[0085] Yet, in another aspect of the invention, use of the sound insulating resilient layer as disclosed herein as an impact sound insulation layer or as a part thereof between a load-bearing floor (3) and a floating floor layer (4) is provided.

[0086] Examples

[0087] Example 1.

[0088] Examples of insulating resilient layers falling within the scope of the disclosure.Layer 1 : Thickness 2 mm, density 40 kg / m3, dynamic stiffness 70 MN / m3, made from three-dimensional fibre network produced from bleached softwood pulp.Layer 2: Thickness 3 mm, density 40 kg / m3, dynamic stiffness 60 MN / m3, made fromthree-dimensional fibre network produced from bleached softwood pulp.Layer 3: Thickness 40 mm, density 40 kg / m3, dynamic stiffness 8 MN / m3, made from three-dimensional fibre network produced from bleached softwood pulp.Layer 4: Thickness 30 mm, density 15 kg / m3, dynamic stiffness 10 MN / m3, made from three-dimensional fibre network produced from bleached softwood pulp.Layer 5: Thickness 30 mm, density 80 kg / m3, dynamic stiffness 12 MN / m3, made from three-dimensional fibre network produced from bleached softwood pulp and bicomponent fibres.Layer 6: Thickness 6.5 mm, density 62 kg / m3, dynamic stiffness 53 MN / m3, made from three-dimensional fibre network produced from bleached softwood pulp and bicomponent fibres.Layer 7: Thickness 4 mm, density 45 kg / m3, dynamic stiffness 60 MN / m3, made from three-dimensional fibre network produced from bleached softwood pulp and 4 wt-% of bicomponent fibres.Layer 8: Thickness 4 mm, density 75 kg / m3, dynamic stiffness 150 MN / m3, made from three-dimensional fibre network produced from bleached softwood pulp and 4 wt-% of bicomponent fibres.

[0089] Layer 9: Thickness 50 mm, density 40 kg / m3, dynamic stiffness 13 MN / m3, made from three-dimensional fibre network produced from bleached softwood pulp and 4 wt-% of bicomponent fibres.

[0090] Example 2.

[0091] Dynamic stiffness of three samples of three-dimensional fibre network produced from bleached softwood pulp (A, B, C) at thickness of 50 mm were provided. These results were used to simulate dynamic stiffness in situations where the thickness of the material differs from 50 mm. Linear elastic material parameters (isotropic Young’s modulus and Poisson’s ratio) were fit to match the previously measured resonance frequency with the finite element method using linear harmonic analysis by repeating the dynamic stiffness measurement procedure in simulation according to standard ISO 9052- 1 :1989. The calibrated model was then used to determine simulated dynamic stiffness for two different thicknesses of 3 and 30 mm (table 1).Table 1.Sample Density Dynamic stiffness of 3 mm Dynamic stiffness of 30 mm Young’s modulus (kg / m3) thick sheet (MN / m3) thick sheet (MN / m3) (MPa)A 40 71.1 7.3 0.225B 60 95.7 10.0 0.31C 80 120.3 12.9 0.4Based on the results, material A was selected as an example for 3 mm thick sheet and material B for 30 mm thick sheet for further assessment.These materials may be used for example under a walkable floating floor covering (e.g. a parquet) for material A with thickness of 3 mm or under a floating floor layer (e.g. a fibrecement screed) for material B with thickness of 30 mm. A relevant parameter that needs to be determined to assess the sound insulation of the construction is impact sound improvement AL, which describes how much the added construction decreases impact sound compared to a situation with only the load-bearing intermediate floor. A positive value describes a situation where adding the construction on an intermediate floor will decrease the impact sound level by that amount.Impact sound improvement AL was calculated for material A as 3 mm thick sheet under a walkable floating floor covering and for material B as 30 mm thick sheet under a floating floor layer using a parametric calculation model by AINS Group. The results are shown in figures 4 and 5. Comparison to commonly used materials with similar thicknesses and same intended uses were made with the same calculation model. For 3 mm thick sheet a plastic sheet was used as the reference material and for 30 mm sheet an EPS board was used as the reference material. Both samples performed in the simulations at least as well as the reference materials. The weighted impact sound improvement ALw is 14 dB for both floors in figure 4 and 32 dB for material B as 30 mm thick sheet and 29 dB for the 30 mm reference material in figure 5. The load-bearing intermediate floor used for the basis of calculation on which these structures were placed on was a 240 mm reinforced concrete slab.

[0092] Example 3.

[0093] Dynamic stiffness was measured for four different sample plates of three- dimensional fibre network produced from bleached softwood pulp with differentthicknesses. The method was based on methods disclosed in standards ISO 9052-1 :1989 and ISO 7626-5:2019. The samples were placed on top of a stiff concrete plate (base plate) and a steel plate of size about 200 x 200 mm2and of weight about 7.8 kg was placed on top of the samples. The acceleration of the surfaces was measured.Resonance frequency (fr) was determined for each sample. Resonance frequency was determined from the measured frequency response (transmissibility, T), which in turn is calculated from the acceleration ratio of the steel plate and the base plate with the following equationT = X2 / X1 wherein Xi is the acceleration of the base plate in frequency domain X2 is the acceleration of the steel plate in frequency domainThe measured dynamic stiffness s’t is calculated according to the standard ISO 9052-1. The dynamic stiffness of air s’ais taken into account according to the standard and the corrected dynamic stiffness of the sample s' is given as follows: s’ = s’t+s’a. The dynamic stiffness of air requires the sample porosity, which is calculated with the following equation:£ = 1-pt / pf wherein ptis density of the sample (kg / m3) pf is density of the fibre used in the sample (here 1500 kg / m3)Loss factor ( |) was determined from the determined frequency response (fr) with a 3 dB bandwidth method with the following equation: | = Af / fr wherein Af is 3 dB bandwidth at around resonance frequencyBandwith Af is determined on both sides of the resonance frequency at points where the value of frequency response has decreased 3 dB when compared to resonance frequency. Results have been collected in table 2.Table 2.Sample Density Thickness Resonance Measured Corrected dynamic Measured(kg / m3) (mm) frequency dynamic stiffness stiffness loss factor fr (Hz) s’t (MN / m3) s’ (MN / m3) (q)A 42 4 56.40 24.8 52.7 0.425B 36 23 19.80 3.0 7.6 0.125C 67 37 16.40 2.1 4.9 0.089D 60 66 42.40 17.2 18.8 0.083

[0094] Example 4.

[0095] Four different fibre based compositions were prepared for further investigations. Sample A contained 90 % bleach softwood kraft pulp and 10 % sawdust, sample B contained 75 % bleach softwood kraft pulp and 25 % sawdust, sample C contained 50 % bleach softwood kraft pulp and 50 % bleached chemi-thermo mechanical pulp and sample D contained 80 % bleach softwood kraft pulp and 20 % bleached chemi- thermo mechanical pulp.Dynamic stiffness was measured for the samples using the same method as in example 2 for three parallel samples of each material. The average results of these measurements are collected in table 3.Table 3.Sample Average Thickness Resonance Measured dynamic Corrected Measured density (mm)fstiffness, s’t dynamic stiffness, loss factor(kg / m3)q“y(MN / m3) s' (MN / m3) (q) fr [Hz]A 41 48.6 23.40 4.2 6.3 0.040B 41 48.0 20.30 3.2 5.4 0.040C 40 48.8 29 6.6 8.7 0.058D 40 49.6 25.80 5.2 7.3 0.052

[0096] Example 5

[0097] Samples of eight different materials were provided with the material composition and the nominal densities of each material. All materials were produced frombleached softwood pulp and bicomponent fibres comprising a thermoplastic polymer. Materials 1 - 5 (Mat 1 - Mat 5) comprised 15 % of bicomponent fibres and materials 6 - 8 (Mat 6 - Mat 8) comprised 14 % of bicomponent fibres. Samples were briefly heat treated during their production so that at least part of the bicomponent fibres on the surface layer of the produced materials melted. Details of the samples are given in table 4.

[0098] From each sample, three 200 x 200 mm2 test specimens were cut for the measurement of dynamic stiffness using the same experimental setup as disclosed in example 3. In addition, three commercial reference samples (Ekovilla, Rockwool Flexibatt 36 and Hunton Native) were analysed. Table d.Measured thickness DensitySample name Composition(mm) (kg / m3)Mat 1 Pulp with bicomponent fibre 30.5 40Mat 2 Pulp with bicomponent fibre 30.8 80Mat 3 Pulp with bicomponent fibre 50.8 40Mat 4 Pulp with bicomponent fibre 54.3 80Mat 5 Pulp with bicomponent fibre 92.5 40Mat 6 Pulp with bicomponent fibre 1.5 85Mat 7 Pulp with bicomponent fibre 5 54Mat 8 Pulp with bicomponent fibre 4.5 62Ref l Recycled wood fibre (Ecovilla) 96.8 32-42Ref 2 Rock mineral wool (Rockwool flexibatt 36) 100.3 34Ref 3 Spruce tree chip / wood fibre (Hunton Native) 95.5 50

[0099] The results for each material are shown in Table 5.Table 5Sample Resonance frequency Measured dynamic Corrected Measured loss dynamic stiffness, namestiffness, s’t (MN / m3)s< (jqN / m3) factor (q)Mat l 18.5 2.7 6.1 0.113Mat 2 31.2 7.5 11.1 0.139Mat 3 14.5 1.6 40 0.096Mat 4 19.6 54.3 80 0.101Mat S 10.4 92.5 40 0.093Mat 6 92 1.5 85 0.499Mat 7 40.3 5 54 0.227Mat 8 63.8 4.5 62 0.467Ref l 9.8 96.8 32-42 0.074Ref 2 14.3 100.3 34 0.074Ref 3 17.6 95.5 50 0.051

[0100] In addition, dynamic stiffness was analysed after long term loading. Mat 1 and Mat 2 were placed under a static load of roughly 110 kg / m2. The samples were held under load for 58 days, after which the measurement of dynamic stiffness was repeated. The responses of the original measurement and the repeated measurement after loading are collected to table 6.Table 6.]VIc a s u rc d Resonance frequency Measured dynamic CorrectedSample name dynamic stiffness, loss factor fr (Hz) stiffness, s’t (MN / m3) s' (MN / m3)Mat l 18.6 2.7 6.1 0.113Mat 1, after 23.7 4.3 7.8 0.131 loadingMat 2 31.2 7.5 11.1 0.0.135Mat 2, after34.1 9.0 12.6 0.150 loading

[0101] It was observed that long term loading does increase the dynamic stiffness of the materials, thus raising the measured natural frequency. The increase in dynamic stiffness was larger for the originally less stiff material Matl, whereas the stiffer material Mat2 was less affected by the loading.

[0102] The dynamic stiffnesses of the tested eight materials (Mat 1-8) was less than < 10 MN / m3for all materials with thickness > 30 mm except for Mat2 for which the measured dynamic stiffness was 11,1 MN / m3. Material Mat2 seemed to be the most suitable for impact sound insulation.

[0103] Of materials 6-8 (Mat6-8) for which the thickness was below 10 mm, material Mat 8 appeared to be most suitable for use as an impact sound insulation material or as sound insulating underlay.

[0104] The 100 mm thick material Mat 5 was compared to three commercially available materials Ref 1-3. In terms of dynamic stiffness, Mat 5 performed well compared to the reference materials. Dynamic stiffness of Mat 5 was lower than of the benchmark materials Ref 2 and Ref 3, and almost equal to Ref 1. Mat 5 also had a higher internal loss factor than the benchmark materials, which is advantageous.

[0105] It is to be understood that the disclosed embodiments are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0106] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0107] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents ofone another, but are to be considered as separate and autonomous representations of the present invention.

[0108] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0109] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0110] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.

[0111] Unless otherwise stated herein or clear from the context, any percentages referred to herein are expressed as percent by weight based on a total weight of the respective composition.REFERENCE SIGNS LIST1 a walkable floor covering2 a sound insulating resilient layer3 a load-bearing floor4 a floating floor layer

Claims

CLAIMS:

1. A sound insulating resilient layer comprising a three-dimensional fibre network, wherein- the three-dimensional fibre network comprises a fibrous cellulosic and / or lignocellulosic material;- the thickness of the sound insulating resilient layer ranges from 1 to below 20 mm, and- the dynamic stiffness of the sound insulating resilient layer is below 200 MN / m3.

2. The sound insulating resilient layer according to claim 1, wherein the thickness of the sound insulating resilient layer ranges from 1 to 15 mm, more preferably from 2 to 10 mm.

3. The sound insulating resilient layer according to claim 1, wherein the thickness of the sound insulating resilient layer ranges from 3 to 5 mm.

4. The sound insulating resilient layer according to any of the preceding claims, wherein the dynamic stiffness of the sound insulating resilient layer is below 150 MN / m3, preferably between 30 to 100 MN / m3.

5. The sound insulating resilient layer according to any of the preceding claims, wherein the dynamic stiffness of the sound insulating resilient layer is between 50 to 80 MN / m3.

6. The sound insulating resilient layer according to any of the preceding claims, wherein the dynamic stiffness of the sound insulating resilient layer is above 100 NM / m2.

7. The sound insulating resilient layer according to claim 1, wherein the dynamic stiffness of the sound insulating resilient layer is between 50 to 80 NM / m2and the thickness of the sound insulating resilient layer ranges from 3 to 5 mm.

8. A sound insulating resilient layer comprising a three-dimensional fibre network, wherein- the three-dimensional fibre network comprises a fibrous cellulosic and / or lignocellulosic material;- the thickness of the sound insulating resilient layer ranges from 20 to 120 mm, and- the dynamic stiffness of the sound insulating resilient layer is below 30 MN / m3.

9. The sound insulating resilient layer according to claim 8, wherein the dynamic stiffness of the sound insulating resilient layer is below 20 MN / m3, such as below 15 MN / m3, for example above 5 MN / m3.

10. The sound insulating resilient layer according to claim 8, wherein the dynamic stiffness of the sound insulating resilient layer is 5 to 20 MN / m3.

11. The sound insulating resilient layer according to any of the claims 8 to 10, wherein the thickness of the sound insulating resilient layer ranges from 25 to 100 mm.

12. The sound insulating resilient layer according to any of the claims 8 to 10, wherein the thickness of the sound insulating resilient layer ranges from 30 to 80 mm.

13. The sound insulating resilient layer according to any of the claims 8 or 12, wherein the thickness of the sound insulating resilient layer ranges from 30 to 80 mm and the density of the sound insulating resilient layer ranges from 40 to 80 kg / m3.

14. The sound insulating resilient layer according to any of the claims 1 to 12, wherein the density of the sound insulating resilient layer ranges from 30 to 150 kg / m3, preferably from 35 to 100 kg / m3most preferably from 40 to 80 kg / m3.

15. The sound insulating resilient layer according to any of the preceding claims, wherein the sound insulating resilient layer is arranged under a floating floor layer, such as between a floating floor layer and a load-bearing floor.

16. The sound insulating resilient layer according to any of the preceding claims, wherein the sound insulating resilient layer is arranged under a walkable floor covering, such as between a load-bearing floor and a walkable floor covering.

17. The sound insulating resilient layer according to any of the preceding claims, wherein the fibrous cellulosic and / or lignocellulosic material is selected from bleached or unbleached chemical pulp, such as bleached or unbleached softwood chemical pulp and / or bleached or unbleached hardwood chemical pulp, mechanical pulp, such as bleached chemi-thermomechanical pulp (BCTMP), non-wood pulp, or sawdust.

18. The sound insulating resilient layer according to any of the preceding claims, wherein the sound insulating resilient layer comprises at least 50 wt-%, such as at least 60 wt-%, for example at least 80 wt-%, of the fibrous cellulosic and / or lignocellulosic material, calculated from the dry weight of the sound insulating resilient layer.

19. The sound insulating resilient layer according to any of the preceding claims comprising one or more additive chemicals selected from flame-retardants, foaming agents, mould inhibitors, binding agents, barrier agents, barrier and binding agents, or combinations thereof.

20. The sound insulating resilient layer according to any of the preceding claims comprising a binding composition.

21. The sound insulating resilient layer according to claim 20, wherein the binding composition comprises or consists of bicomponent fibres.

22. The sound insulating resilient layer according to claim 21, wherein the melting temperature of the bicomponent fibres is less than 200 °C.

23. The sound insulating resilient layer according to claim 21 or 22, wherein the sound insulating resilient layer comprises than 5 %, such as 0.5 to 4.5 % of bicomponent fibres of the dry weight of the sound insulating resilient layer.

24. The sound insulating resilient layer according to any of the preceding claims, wherein the sound insulating resilient layer comprises at least one flame retardant selected from the group of mineral flame-retardants, organohalogen compounds, organophosphorus compounds, inorganic phosphorus compounds, organic compounds, and combinations thereof.

25. The sound insulating resilient layer according to any of the preceding claims, wherein the fibre length of the fibrous cellulosic and / or lignocellulosic material is 0.5 to 5 mm, preferably in the range of 0.3-3 mm, most preferably in the range of 0.7-3 mm.

26. The sound insulating resilient layer according to any of the preceding claims, wherein the sound insulating resilient layer is obtained by continuous web forming or mould- assisted forming.

27. The sound insulating resilient layer according to any of the preceding claims, wherein the diameter of at least 90 wt% of the fibres in the three-dimensional fibre network is in the range of 10 to 30 pm.

28. A sound insulating element comprising at least one sound insulating resilient layer according to any of the preceding claims and a walkable floor covering (1) and / or a floating floor layer (4), wherein the sound insulating resilient layer is attached to the walkable floor covering or the floating floor layer.

29. The sound insulating element according to claim 28 comprising at least two sound insulating resilient layers.

30. A sound insulating system, wherein a first sound insulating resilient layer is arranged between a floating floor layer and a walkable floor covering and a second sound insulating resilient layer is arranged between a load-bearing floor and a floating floor layer, wherein the first sound insulating resilient layer is thinner than the second sound insulating resilient layer.

31. The sound insulating system according to claim 30, wherein the thickness and the dynamic stiffness of the first sound insulating resilient layer are 3 to 5 mm and 50 to 80 MN / m3respectively, and the thickness and the dynamic stiffness of the second sound insulating resilient layer are 30 to 80 mm and 5 to 20 MN / m3, respectively.

32. Use of the sound insulating resilient layer (2) according to any of claims 1 to 27 as a sound insulating underlay element or as a part thereof between a load-bearing floor (3) and a walkable floor covering (1) laid thereover.

33. Use of the sound insulating resilient layer (2) according to any of claims 1 to 27 as an impact sound insulation layer or as a part thereof between a load-bearing floor (3) and a floating floor layer (4).

Images