Flame-retardant roofing liner and support layer thereof

Abstract

The subject matter of the present invention is a porous support layer for a roofing liner, the porous support layer comprising: a first nonwoven layer comprising polyester fibers; and a second non-woven layer comprising organic flame retardant fibers wherein the flame retardant fibers have a combustion temperature of at least 500 DEG C and / or the flame retardant fibers have a Limit Oxygen Index (LOI) of at least 25% wherein the second non-woven layer is a surface layer of the support layer wherein the support layer is mechanically reinforced. The subject of the invention is also a building material, such as a roofing liner made of said support layer and asphalt layer; the roof and the building comprise the roof liner; as well as corresponding methods and uses.

Description

TECHNICAL FIELD

[0001] The present invention relates to a building material, in particular a roof underlay and a support layer for a roof underlay, the support layer comprising a first nonwoven layer comprising polyester fibers and a second nonwoven layer comprising organic fire-retardant fibers. BACKGROUND

[0002] A roof underlay is a sheet material installed between the main roofing material. The underlay provides an additional protective barrier that enhances the overall performance of the roof and extends the life.

[0003] A roof underlay has multiple functions, including the prevention of water penetration into the building and thermal insulation of the building. The underlay also acts as a sound barrier that absorbs and mitigates noise from rainfall, hail or other external disturbances. A roof underlay can also increase the strength and stability of the roof structure.

[0004] In the art, various types of roof underlays are used, which have different structures and properties. A common type is an asphalt roof underlay, which comprises an asphalt layer for insulation and shielding and a support layer for mechanical stability, usually made of felt, glass fibers or polyester impregnated with a polymeric binder. US 2003 / 203145 Al discloses a conventional roof underlay, wherein the support layer is coated with asphalt.

[0005] Generally, it is desirable that such roof underlays can be conveniently produced and handled and have a high mechanical stability. If the roof underlay is damaged, for example by a hole or a crack, over time the roof can become unstable, leak or be damaged.

[0006] It is generally desirable that related building components have fire-resistant properties. It is therefore also desirable to provide a fire-resistant roof underlay. Generally, conventional roof underlays are not fire-resistant. This is a problem because roof underlays comprising plastic materials such as plastic fibers and synthetic polymeric binders can burn or melt and thus can facilitate the spread of fire.

[0007] In the art, it has been suggested to increase the fire resistance of roof materials by fire-retardant additives or layers.

[0008] For example, it has been suggested in the art to incorporate fire-retardant fibers into asphalt membranes. Asphalt membranes are characterized by a fiber carrier impregnated with molten asphalt. They are produced in a relatively complex process on a specific production line, wherein the fabric is unwound from a roll and continuously passed through a liquid asphalt bath at a temperature of about 200°C. Asphalt membranes have specific structures and properties and also have different applications than standard roof underlays.

[0009] WO 2020 / 225200 A1 relates to bitumen membranes for roofing applications, which are obtained by impregnating a fibrous support layer with molten bitumen. The support layer comprises a nonwoven layer based on flame-retardant fibers, which is embedded between a first and a second nonwoven layer made of polyester fibers. The three-layer structure and the bitumen impregnation process are relatively complex. The product is different from a standard roofing underlay.

[0010] WO 2021 / 216168 A1 relates to roofing composites comprising a flame-retardant (FR) fleece and a carrier impregnated with bitumen. The carrier is typically a glass fiber mat impregnated with and saturated with molten bitumen. The flame-retardant fleece contains a mixture of flame-retardant staple fibers and flame-retardant scaffolding fibers, and optionally non-flame-retardant fibers. Furthermore, this preparation method requires impregnation of the carrier with molten bitumen, and the product is different from a standard roofing underlay.

[0011] US 2018 / 0100256 A1 relates to a nonwoven flame barrier made from a blend of silica fibers and different types of oxidized polyacrylonitrile fibers. Such nonwovens made from inorganic fibers are relatively hard. Thus, the nonwoven can be used for the preparation of products having dimensional stability, like gypsum wallboards. The nonwoven does not have sufficient elasticity or flexibility for applications like roofing underlays.

[0012] WO 01 / 68341 A1 relates to a combustion-modified batting fiber made from a blend of oxidized polyacrylonitrile fibers, carrier fibers and binder fibers. The batting is suitable for various applications, like coverings for furniture or mattresses. No application for roofing underlays is mentioned.

[0013] Therefore, it is desirable to provide a simple and efficient roofing underlay having fire barrier properties. SUMMARY

[0014] A potential problem of the present invention is to provide a building material, in particular a roofing underlay having a bitumen layer, and a substrate for such a building material, which provides an efficient fire barrier.

[0015] A further problem is to provide a flame-retardant roofing underlay and a substrate, which can be easily prepared, handled and used, and which has long-term stability on a roof. Therefore, the flame-retardant roofing underlay and the substrate should have mechanical stability, elasticity and flexibility. The material should not be easily damaged when subjected to forces.

[0016] The material should be stable at high temperatures, such that it can be coated with molten bitumen and does not deteriorate during long-term use.

[0017] A further problem is to provide such a flame-retardant roofing underlay and a substrate having a simple structure. A further problem is to provide such a material from components which are not hazardous and environmentally friendly. DETAILED DESCRIPTION

[0018] Surprisingly, the potential problem of the present invention is solved by the support layer, the product, the use and the method according to the claims. Further embodiments of the present invention are outlined throughout the description.

[0019] Subject of the present invention is a porous support layer for a roof underlay, the porous support layer comprising

[0020] a first nonwoven layer, the first nonwoven layer comprising polyester fibers, and

[0021] a second nonwoven layer, the second nonwoven layer comprising flame retardant fibers, wherein the flame retardant fibers have a burning temperature of at least 500 °C and / or the flame retardant fibers have a limiting oxygen index (LOI) of at least 25 %,

[0022] wherein the second nonwoven layer is a surface layer of the support layer, wherein the second nonwoven layer does not comprise inorganic nonwoven fibers,

[0023] wherein the support layer is mechanically reinforced.

[0024] The support layer comprises a first nonwoven (“polyester nonwoven”) and a second nonwoven (“flame retardant nonwoven” or “FR nonwoven” or “surface layer”). The support layer is a composite material, since the first nonwoven layer and the second nonwoven layer made of different materials are combined. The support layer is a laminate, since the first nonwoven layer and the second nonwoven layer are sheet materials connected to each other. The entire support layer is a laminated sheet material. Preferably, it is flexible, so that it can be provided in the form of a roll.

[0025] The first layer and the second layer of the support layer are nonwoven layers. According to the general definition in the technical field of ISO 9092:2019, a nonwoven is a sheet of fibers or continuous filaments that have been formed into a web by any means and are bonded together by means other than weaving or knitting. Preferably, the fibers forming the nonwoven are randomly oriented. Preferably, it is bonded by friction, cohesion and / or adhesion. Preferably, the amount of fibers in the nonwoven is at least 60 wt.-%, more preferably at least 80 wt.-%.

[0026] The support layer is used for a building material, like a roof underlay. The roof underlay is prepared by combining the support layer with an asphalt layer, usually on one side of the polyester nonwoven. Thus, the roof underlay comprises an outer asphalt layer, an outer fire resistant layer and an intermediate polyester layer.

[0027] During the construction of a roof, a roof underlay in the form of a sheet is laid on the roof surface, wherein the bitumen layer is facing downwards and the fire-resistant layer is facing upwards. The roof surface can be made of wood, concrete or metal, for example. Thus, the fire-resistant layer is exposed to the outside and is therefore the "surface layer" of the roof underlay and the support layer. The fire-resistant layer on the surface can then be covered with additional roofing material, like roof tiles, shingles, panels or insulation material.

[0028] The bitumen layer can be applied by coating the support layer with molten or softened bitumen or by attaching a pre-formed bitumen layer to the support layer. The bitumen layer can be adhered by softened bitumen or by an adhesive. Thereby, a roof underlay is obtained, which preferably consists of a support layer and a bitumen layer. In these methods, the support layer is neither impregnated nor saturated with bitumen. Preferably, the bitumen should only enter and fill the pores in the area of the support layer close to the surface on which the bitumen layer is applied. Preferably, the other side of the support layer, i.e. the fire-resistant layer, is the surface layer and is not coated with bitumen. Preferably, the polyester layer is not in contact with bitumen.

[0029] The bitumen can be any bitumen-based composition used in the field of roofing materials. The bitumen layer can comprise additives, like polymers, fillers or functional additives. A bitumen layer comprising high levels of fillers is also referred to as asphalt and can also be used to make the roof underlay of the present invention.

[0030] The bitumen layer does not comprise a fiber or other pre-formed substrate that has been impregnated with bitumen and saturated with bitumen. In particular, the roof underlay is not a bitumen membrane. Furthermore, the roof underlay of the present invention is not a bitumen membrane. The support layer of the present invention is not impregnated with bitumen and not saturated with bitumen. Conventional bitumen membranes for roofing applications comprise a fiber substrate, usually a non-woven or woven fabric, scrim or mesh, usually based on glass fibers, which is completely impregnated and saturated with bitumen and should give the entire bitumen membrane stability. Such a fiber substrate within the bitumen is not necessary in the present invention, because the support layer of the present invention can give the roof underlay sufficient stability. This is advantageous, because the roof underlay of the present invention can simply be coated with bitumen or can provide a simple layer made of bitumen. In contrast, impregnating a fiber substrate with bitumen is carried out in a bath of liquid bitumen at about 200°C and the standard process requires complex machinery. The simple production process of the roof underlay of the present invention is highly advantageous for large-scale applications, where a large amount of and cost-adequate roof underlay is needed.

[0031] In a preferred embodiment, the support layer is coated with molten or softened bitumen to create the roof underlay.

[0032] The support layer is porous. Thus, it does not form a closed film. The porous structure is advantageous, as the bitumen coating can partially enter the pores of the surface on which it is applied, thereby increasing the stability of the roof underlay. Furthermore, the porous support layer is relatively light and also permeable, which can facilitate moisture control and transfer in the roof.

[0033] The second nonwoven layer comprising flame-retardant fibers is a surface layer of the support layer. Preferably, there are no further layers between the first nonwoven layer and the second nonwoven layer. In this embodiment, the two layers are in direct contact with each other. In a preferred embodiment, the support layer does not comprise additional layers. Thus, the support layer consists of the first nonwoven layer and the second nonwoven layer. It was found that a stable and efficient support layer for a bitumen layer can be provided by two nonwovens. This is advantageous, as the overall structure is simple. A support layer containing only two nonwoven layers can be conveniently and cost-efficiently produced, making the product suitable for large-scale applications. Simple laminates have a lower tendency to delaminate or other problems at the layer interfaces. This is advantageous, as the roof underlay should remain stable over a long period of time under varying environmental conditions and during construction and use when mechanical forces are applied to the roof. Roof underlays in the art, even without the fire barrier function, can comprise more layers and different materials, such as a polymer film, scrim or a glass fiber layer, which makes production and processing more difficult. The support layer of the present invention is also much simpler than the three-layer bitumen film of WO 2020 / 225200 A1, in which a layer of flame-retardant fibers is sandwiched between polyester nonwoven layers and completely impregnated and saturated with bitumen.

[0034] The support layer can be produced from different nonwoven layers, which are laid onto each other and bonded to each other. Alternatively, precursor webs and / or preformed nonwovens can be combined and bonded to each other. The nonwoven layers can comprise zones in which the fibrous material is made of adjacent layers that penetrate each other. Such structures can be produced by harsh mechanical reinforcement, such as needle punching, and can connect the adjacent layers to each other more tightly, thereby reducing the risk of delamination. Nonetheless, the first nonwoven and the second nonwoven form different layers, which can be clearly distinguished in a cross-sectional view.

[0035] It was found that the support layer of the present invention can provide an efficient fire barrier. The performance of a roof underlay to external fire exposure can be determined by standardized tests, such as EN 1187. Furthermore, the support layer can impart high stability and additional advantageous properties to the roof underlay. The support layer is mechanically stable and thus does not easily form holes or cracks at low and high temperatures. The advantageous properties are obtained by the specific selection and combination of fibers and layers.

[0036] The support layer comprises a first nonwoven layer comprising polyester fibers. In a preferred embodiment, the first nonwoven layer consists of polyester fibers. In a preferred embodiment, the fiber material of the first nonwoven layer is polyester only. The polyester can be selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate and polyester copolymers.

[0037] It is highly preferred that the polyester is polyethylene terephthalate (PET). This is advantageous because PET is stable at temperatures of about 200°C and PET nonwovens are relatively simple and cost-efficient to produce. Furthermore, PET nonwovens can impart excellent mechanical properties to the support layer and can support fire barrier properties. The PET can be virgin PET or recycled PET (rPRT).

[0038] In one embodiment, the first nonwoven layer comprises at most 30 wt.%, preferably at most 20 wt.% or at most 10 wt.% of other fibers than polyester fibers. In a preferred embodiment, the other fibers are flame retardant fibers. Thereby, the overall fire barrier performance of the support layer can be further improved.

[0039] The second nonwoven layer comprises flame retardant fibers. According to the present disclosure, “flame retardant” refers to a material that slows, stops or prevents ignition and burning. The flame retardant layer imparts fire barrier properties to the support layer and thus to the roof underlay. The entire support layer acts as a fire barrier. In the technical field of building materials, this is advantageous to avoid fire spreading. The fire barrier can prevent or slow the spread of flames or can extinguish the fire.

[0040] The support layer comprises a second nonwoven layer comprising flame retardant fibers, wherein the flame retardant fibers have a combustion temperature of at least 500°C and / or an limiting oxygen index (LOI) of at least 25%. Preferably, the second nonwoven layer consists of flame retardant fibers. It was found that the support layer of the present invention made from the combination of a polyester nonwoven and a flame retardant nonwoven can have excellent flame retardancy but also mechanical properties which make it highly suitable for a roof underlay.

[0041] The limiting oxygen index (LOI) of the flame retardant fiber can be at least 25%, preferably at least 27%, or even at least 28%. Preferably, the LOI is in the range of 25% to 45%, in particular 28% to 35%. The LOI is the minimum oxygen concentration, expressed in percent, that supports the combustion of a polymer. It is measured by passing a mixture of oxygen and nitrogen through a burning sample and lowering the oxygen level until a critical level is reached. The LOI value is typically provided in vol% and can be determined by standardized tests like ISO 4589, preferably ISO 4589-1 :2017. Such high LOI values are characteristic of highly efficient flame retardant fibers, like modified polyacrylonitrile fibers with an LOI of about 29-30%.

[0042] The flame temperature of the flame retardant fiber can be at least 500°C, more preferably at least 600°C. For example, the flame temperature can be determined according to ASTM D 3814, preferably ASTM D3814-06 (Standard Guide for Locating Combustion Test Methods for Polymeric Materials, 1999). Such high flame temperatures are characteristic of highly efficient flame retardant fibers. Preferably, the flame temperature of the flame retardant fiber is at least 600°C and the limiting oxygen index (LOI) is at least 28%.

[0043] The flame retardant fiber is an organic fiber. According to the present application, it was found that organic flame retardant fibers can provide an efficient fiber barrier and advantageous mechanical properties for a roof underlay. The organic flame retardant fiber can have an advantageous combination of elasticity, flexibility, and low stiffness, which can be similar to polyester fibers. Thus, the properties of the first nonwoven and the second nonwoven are compatible, so that the support layer can be conveniently produced and handled. For example, the support layer, and thus also the roof underlay, is generally not damaged when processed, i.e. when rolled, pulled, compressed, bent, or adapted to a roof surface, nailed, pierced, or cut. In contrast, conventional roof underlays comprising glass fiber fabrics are neither flexible nor elastic and can form undesirable cracks and breaks when such forces are applied.

[0044] Preferably, the support layer has an elongation at break at 25°C of at least 10%, more preferably at least 20%. Preferably, the elongation at break of the support layer is between 10% and 60%, in particular between 20% and 50%. The tensile properties of the support layer, like the elongation at break and the tensile strength, can be determined by a standard test method, preferably DIN EN ISO 9073-3:2023-09. An elongation at break in such a range indicates that the support layer has a certain degree of elasticity and flexibility which is suitable for roof applications.

[0045] Preferably, the softening temperature TG (glass transition temperature) of the flame- retardant fiber is below 150°C, more preferably below 100°C, as determined, for example, according to ASTM E 1356 or 11357, preferably by DSC. This is advantageous for roofing applications, as such fibers can be flexible at room temperature. Preferably, the melting point (TM) of the flame-retardant fiber is at least 200°C, more preferably at least 220°C. This is advantageous, as the flame-retardant fiber does not melt when applied with a molten or softened bitumen having a melting point of about 180°C.

[0046] It is preferred that the fiber is inherently flame-retardant. This means that the flame- retardancy is a property of the fiber material and not imparted to the fiber by a coating or functional additive. This is advantageous for roofing applications, where the material should be stable over a long period of time. The flame-retardancy can be an inherent property of the fiber or can be imparted to the fiber by a specific treatment, for example by impregnation with a flame-retardant.

[0047] In a preferred embodiment, the flame-retardant fiber comprises a fiber polymer, which comprises at least one element selected from Cl, Br, P, S and Si. Preferably, the fiber polymer comprises a moiety selected from a phosphate, a sulfate, a sulfonate, CCln (n = 1, 2 or 3) or SiOm (where m = 2 or 3) or a silicate. Organic flame-retardant fibers comprising polymers with such elements and functional groups are typically characterized by a high LOI and can provide a highly efficient fire barrier. In the presence of fire, such polymer moieties decompose, thereby releasing low molecular weight substances comprising these elements in gaseous form, which can dilute the oxygen and extinguish the flame. Preferably, these elements and groups are permanently attached to the fiber polymer. More preferably, these elements and groups are covalently attached to the fiber polymer, such that the fiber is inherently flame-retardant. In this regard, the fiber polymer can be a copolymer from monomers comprising such elements or groups. For example, modified polyacrylonitrile fibers are prepared from copolymers from halogenated monomer units. The fiber polymer can also be an organic polymer that has been functionalized with functional groups. For example, fire-resistant viscose is a cellulose derivative, in which the hydroxyl groups are functionalized with phosphorus-containing groups, sulfate groups or other groups. Such inherently flame-retardant fibers and fiber polymers are advantageous, as the performance does not degrade during long-term use on a roof.

[0048] In a preferred embodiment, the flame-retardant fiber is charring. This means that the flame-retardant fiber does not melt before pyrolysis. In the presence of fire, the charring fiber is pyrolyzed and retains its basic fiber structure. Thus, the second nonwoven layer can substantially maintain its structure and integrity and form a fire barrier.

[0049] The pyrolysis temperature TP is the temperature at which the fibres carbonise (pyrolyse). Preferably, the carbonising fibres have a TP > 200°C or > 250°C, in other embodiments > 300°C, or even > 400°C.

[0050] Preferably, the melting temperature TM of the flame retardant fibres is equal to, greater than or not significantly lower than the pyrolysis temperature TP. In preferred embodiments, the flame retardant fibres are not meltable, or the difference TP (pyrolysis temperature) - TM (melting temperature) is less than 50°C, preferably less than 30°C. This is advantageous because in the presence of fire, such fibres do not melt but rather transform into carbonaceous fibres and are thus carbonising fibres. Preferably, TM and / or TP are determined according to ASTM D276-00a or ISO / TR 11827:2012(E). For example, preferred modified polyacrylonitrile fibres are carbonising, have a TM > 240°C and a TP of 273°C.

[0051] In preferred embodiments, the flame retardant fibres are selected from modified polyacrylonitrile fibres, flame retardant viscose fibres (flame retardant rayon), polyacrylonitrile (PAN) fibres, partially oxidised polyacrylonitrile (PANOX) fibres, poly-phenylene benzo-bisoxazole (PBO) fibres, polybenzimidazole (PBI) fibres and / or melamine fibres. These fibres have a relatively high ignition temperature and LOI and can impart good fire barrier properties to the fabric, but are also compatible with polyester to provide a support layer with advantageous mechanical properties when used as a roofing underlay.

[0052] In preferred embodiments, the flame retardant fibres are modified polyacrylonitrile fibres and / or flame retardant viscose fibres. More preferably, the first nonwoven layer consists of these fibres. Such flame retardant fibres have excellent flame retardant properties and can provide an efficient fire barrier. This is advantageous because they are carbonising and can form an efficient fire barrier. Furthermore, these fibres are found to have mechanical properties which are particularly advantageous for combination with a polyester nonwoven layer to form the roofing underlay of the application. In this respect, the mechanical properties such as flexibility and elasticity are similar to PET. Thus, the entire support layer can be conveniently processed and handled. Such a support layer is very uniform, which reduces damage caused by delamination or the like when forces are applied during processing and use.

[0053] In a highly preferred embodiment, the fibers are modacrylic fibers. Modacrylic is a modified acrylic fiber copolymer composed of less than 85% but at least 35% by weight of acrylonitrile monomer. Typical comonomers are halogenated vinyl or vinylidene monomers, especially vinyl chloride, vinylidene chloride or vinyl bromide. Modacrylic fibers are commercially available, for example from Kaneka, JP or Fushon Rayva Fiber Ltd., CN. Preferably, the modacrylic fibers can be characterized as described in ASTM D276-00a. Modacrylic fibers are charring, i.e. pyrolyze (carbonize) in the presence of fire. For example, ASTM D276-00a indicates that modacrylic fibers do not melt. Furthermore, they can impart advantageous mechanical properties to the support layer at low and high temperatures. A support layer comprising a second nonwoven layer based on modacrylic fibers can be flexible and have a certain degree of elasticity, but also high mechanical stability at low and high temperatures. Nonwoven layers made from modacrylic fibers were found to be highly compatible with polyester nonwoven layers, such that a roofing underlay with advantageous fire barrier and mechanical properties is obtained.

[0054] In a highly preferred embodiment, the fibers are flame-retardant viscose (flame-retardant rayon) fibers. Flame-retardant viscose fibers are prepared in a process in which functional groups such as phosphorous-containing groups, nitrogen-containing groups and / or sulfur-containing groups are covalently attached to cellulose. Flame-retardant viscose fibers are commercially available, for example “FR Viscose” from Lenzing, DE or FR lyocell fibers. Preferred are fibers made from cellulose modified with sulfur-containing groups that release SO2 in the presence of fire. For example, such fibers can be based on sulfonated cellulose. Flame-retardant viscose fibers can provide an efficient fire barrier and have a high LOI, as they are charring and do not melt in the presence of fire. Furthermore, fire-resistant viscose fibers can be flexible and elastic. The properties of nonwoven layers made from flame-retardant viscose were found to be compatible with polyester nonwoven layers, such that a roofing underlay with advantageous fire barrier and mechanical properties is obtained.

[0055] In one embodiment, the charring fibers are partially carbonized (pre-carbonized). Thus, they are prepared from a precursor fiber by partial carbonization. Carbonization is a process in which organic matter is at least partially converted into carbon. Such pre-carbonized fibers can have a relatively high melting point, or do not melt in the presence of fire. To some extent, such pre-carbonized fibers can maintain the mechanical properties of the polymer precursor, such as flexibility, elasticity and mechanical stability.

[0056] In another embodiment, the carbonizing fibers are not partially carbonized (pre- carbonized) prior to making the support layer. This can be advantageous because the flame- resistant fibers can become less flexible and elastic during pre-carbonization.

[0057] To achieve a strong fire barrier function, it is preferred that the ratio of carbonizing fibers in the second nonwoven layer is relatively high. Preferably, the second layer consists of carbonizing fibers. Preferably, the second layer consists of fibers having a burn temperature of at least 500°C, and / or a limiting oxygen index (LOI) of at least 25%. In other embodiments, at least 70%, at least 80%, or at least 90% (by weight) of all fibers in the second layer are carbonizing, and / or have the aforementioned LOI and / or burn temperature.

[0058] In preferred embodiments, the first nonwoven layer consists of polyester fibers, and / or the second nonwoven layer consists of flame-resistant fibers. Such support layers are advantageous because they can have excellent properties and have a relatively simple structure.

[0059] The second layer does not include inorganic nonwoven fibers such as glass fibers. Preferably, the support layer and / or the first layer do not include inorganic fibers such as glass fibers, e.g., as nonwoven fibers or other fibers that would form a fabric layer. In these embodiments, the support layer can include reinforcements in the form of glass yarns.

[0060] In one embodiment, the second nonwoven layer and / or the support layer does not include fibers that are hard and stiff, e.g., fibers having an elongation at break of less than 10% or less than 5%. In one embodiment, the second nonwoven does not include aramid fibers, such as meta-aramid fibers, para-aramid fibers, and Kevlar fibers. Such fibers are relatively hard and stiff, and thus the elasticity of the support layer can be reduced.

[0061] Preferably, the support layer does not include fibers that melt or soften at temperatures of 200°C or less, such as polyolefin fibers or co-polyester fibers. Preferably, the support layer does not include multi-component fibers, which can make the product more complex and expensive. However, the first layer can include other fibers that are relatively stable at high temperatures, such as polyamide fibers or natural fibers.

[0062] The first and second nonwovens can be formed from staple fibers having a defined length, or from continuous fibers, preferably as spunlaid nonwovens. Preferably, all fibers of the support layer are staple fibers. This can be advantageous, as nonwovens made from staple fibers can be conveniently prepared and can have advantageous properties. The staple fibers can be processed and laid into a batt by conventional methods such as carding, followed by consolidation. For example, the staple fibers have a length of between 5 mm and 200 mm, preferably between 10 mm and 100 mm.

[0063] The support layer is porous. Porosity or void fraction is a measure of the amount of void (i.e. "empty") space in a material and is the fraction of the total volume that is void volume, expressed as a percentage between 0% and 100%. Preferably, the void fraction of the support layer, before and / or after binder consolidation, is between 60% and 95%, more preferably between 75% and 93%, in particular between 80% and 90%. The porosity can be calculated from the weight and density of the product and the known density of the components. Preferably, the average pore size is between 50 pm and 300 pm, preferably between 80 pm and 200 pm, as determined, for example, by DIN ISO 9073-5:2008. When consolidating the support layer, the amount of binder is so low that the support layer remains porous.

[0064] Preferably, the linear density of the fibers of the first and second nonwoven layers is between 0.5 dtex and 20 dtex, more preferably between 1 dtex and 10 dtex. More preferably, the linear density of the char-forming fibers is in the range of 2 dtex to 7 dtex. It was found that nonwovens made from fibers in these diameter ranges can provide the support layer with adequate strength and flexibility. Furthermore, fire-retardant fibers having such fiber diameters can impart excellent fire-retardant properties to the support layer.

[0065] The first and second nonwoven layers or precursor layers thereof can be pre-consolidated prior to the combination, preferably mechanically, more preferably by pre-needling or hydro-entanglement. The first and second layers, and optionally the reinforcement, are combined, and the assembly is mechanically consolidated, and optionally also by other means. Preferably, the laminate is mechanically consolidated by needling and / or hydro-entanglement.

[0066] According to the present application, it was found that a roof underlay consisting of a first and a second nonwoven layer, and optionally inorganic reinforcing fibers, can have highly advantageous properties, in particular in terms of fire-retardancy and mechanical properties. It is therefore preferred that the support layer does not comprise additional layers.

[0067] In one embodiment, the support layer can comprise at least one further layer. The further layer can be disposed between the first and second nonwoven layers, or on the surface of the first nonwoven layer. The further layer can impart desired properties to the composite, such as higher strength or functionality.

[0068] In a preferred embodiment, the support layer comprises a reinforcement, preferably an inorganic reinforcement. Preferably, the inorganic reinforcement comprises a plurality of yarns. The inorganic material is preferably glass. However, another inorganic material such as silica or mineral fibers can also be used. In one embodiment, the reinforcement can be a further layer, for example a nonwoven, a woven, a mesh or a scrim. The reinforcement can be embedded in the first and / or second nonwoven layer, or disposed between the first and second nonwoven layers. In a preferred embodiment, the inorganic reinforcement is disposed between the first and second nonwoven layers. The inorganic reinforcement can increase the overall mechanical stability. Preferably, the amount of reinforcement should not be more than 20 wt.%, preferably less than 10 wt.%, for example 1 to 20 wt.% of the support layer.

[0069] Preferably, the reinforcement comprises yarns and / or discrete reinforcing fibers. Preferably, the yarns consist of a plurality of plied fibers (so-called "fiber yarns"). Alternatively, relatively thick discrete reinforcing fibers can be used. Such reinforcing yarns or fibers are discrete in the support layer in that they are not combined into a fabric layer such as a nonwoven layer. The reinforcing yarns or fibers are preferably glass fiber yarns, but can also be other yarns or fibers, for example made of synthetic polymers such as polyester polymers or cellulose-based polymers. Glass fiber yarns are advantageous in that they are readily available and suitable for increasing the mechanical strength of the nonwoven.

[0070] Preferably, the reinforcing yarns or fibers are aligned, preferably parallel aligned. By aligned is meant that the yarns or fibers are not laid or arranged randomly. Aligned, especially parallel yarns or fibers can impart mechanical strength to the support layer in a desired direction. This is advantageous in that the mechanical strength of the support layer can be increased. Preferably, the yarns or fibers are substantially straight. Preferably, the parallel yarns or fibers are aligned in the machine direction. This is advantageous in that such yarns or fibers can be fed from a nozzle into the forming laminate with standard machinery during the production process.

[0071] In a preferred embodiment, the mechanical reinforcement of the support layer is by needle punching. This is a nonwoven reinforcement process in which a preformed fiber web is mechanically entangled on a loom by repeated penetration of a needle.

[0072] In another preferred embodiment, the support layer is mechanically consolidated by hydroentanglement. Thereby, the preformed fibrous web is subjected to a high pressure fluid jet, typically a water jet.

[0073] In another preferred embodiment, the support layer is mechanically consolidated by calendering, preferably with a pair of heated rolls. Thereby, the laminate is passed through a pair of heated rolls pressed against each other without softening or melting the fibres.

[0074] In a preferred embodiment, the support layer is consolidated with a binder. Preferably, the binder is a polymeric binder comprising a polymer for bonding the nonwoven fibres together. The polymer can be thermoplastic, curable and / or thermosetting. The polymeric binder can be a latex binder or a molten polymer binder. The polymeric binder can be a conventional adhesive for bonding fibres, such as an acrylic, styrene butadiene, styrene acrylic, melamine, polyurethane or silicone binder; a thermosetting resin, such as an epoxy, polyester, urea formaldehyde, melamine or alkyd resin; a natural binder, such as a starch, natural rubber or protein binder, or a flame retardant binder, such as a halogenated polymer, preferably a copolymer of vinyl chloride. It is preferred that the binder is cross-linked (cured) after impregnation of the laminate, as cross-linked binders typically have high thermal stability and can carbonize. Preferably, the curing is mediated by heat, radiation or other means.

[0075] Preferably, the polymeric binder is selected from styrene-butadiene (SBR) and acrylic binders, such as styrene acrylic. Optionally, the polymeric binder comprises a cross-linking agent, such as melamine formaldehyde. For example, suitable SBR and acrylic binders are available from BASF, DE under the trademark Synthomer. Such binders can be advantageous as they are readily available, can be conveniently applied and can impart high strength to the support layer.

[0076] In a preferred embodiment, the polymeric binder comprises or consists of a halogenated polymer, wherein the halogen is preferably CI or Br. Preferably, the halogenated polymer is a copolymer of vinyl chloride. As used herein, the term copolymer comprises polymers from two or more different monomers and thus also terpolymers. For example, a copolymer of vinyl chloride can be used, which is available from Wacker, DE under the trademark VINNOL. Halogenated polymers can be advantageous as the polymeric binder can further increase the fire resistance of the support layer.

[0077] In a preferred embodiment, the polymeric binder comprises a mixture of a non-halogenated polymer, such as SBR or acrylic polymer, and a halogenated polymer, such as a copolymer of vinyl chloride.

[0078] In another embodiment, the binder polymer comprises starch, for example natural starch, such as potato starch. The starch can comprise amylose and amylopectin, or be 100% amylopectin. The starch can be added in an amount of 0 to 50 wt.% based on the binder composition. The use of starch can be advantageous as it does not melt, but can be charring under heat. Furthermore, starch is advantageous as it can come from a natural source and thus be sustainable, and can provide effective mechanical stability.

[0079] The binder can comprise additional conventional components and additives. Preferably, the polymeric binder comprises a crosslinker, a catalyst and / or a functional additive. Preferably, the crosslinker is added in an amount of 0.1 to 10 wt.% based on the binder composition.

[0080] In a preferred embodiment, the polymeric binder comprises at least one flame retardant additive. In a preferred embodiment, the flame retardant additive is a phosphorous containing compound, such as elemental phosphorous, such as microencapsulated red phosphorous, or a phosphate salt, such as a polyphosphate salt, or an organic phosphorous compound. Particularly preferred is ammonium polyphosphate (CAS number 68333-79-9). The flame retardant additive can be added in an amount of 0 to 40 wt.%, preferably 5 to 30 wt.% based on the binder composition. It was found that the flame retardant additive, especially the phosphorous containing compound, can further improve the fire barrier performance of the support layer without compromising the mechanical properties.

[0081] Preferably, the binder composition comprises 60 to 95 wt.% binder polymer, 0 to 15 wt.% catalyst and 0 to 30 wt.% fire resistant additive based on all solids. More preferably, the binder composition comprises 20 to 75 wt.% non-halogenated binder polymer, 20 to 75 wt.% halogenated polymer, 0 to 15 wt.% catalyst and 0 to 40 wt.%, more preferably 5 to 30 wt.% fire resistant additive based on all solids.

[0082] Preferably, the binder loading (dry weight) on the support layer (without binder) is 1 to 40 wt.%, preferably 5 to 25 wt.%, more preferably 5 to 20 wt.% based on all solids. The loading can be determined by comparing the weight of the support layer before and after reinforcement with the binder.

[0083] According to the present application, the second nonwoven layer based on flame retardant fibers provides an efficient fire barrier for the support layer. Therefore, it is not necessary to include additional flame retardant components or additives. Preferably, the support layer does not comprise a further fire resistant layer, such as a glass fiber layer or a metal foil, or a flame retardant fiber coating (facing).

[0084] In a preferred embodiment, the support layer has a basis weight of 50 g / m 2 up to 500 g / m 2 , more preferably 100 g / m 2 up to 400 g / m 2 , or 120 g / m 2 up to 250 g / m 2 . In a preferred embodiment, the first nonwoven layer and / or the second nonwoven layer has a basis weight of 20 g / m 2 up to 250 g / m 2 , more preferably 50 g / m 2 up to 150 g / m 2 . Such support layers and layers were found to provide an efficient fire barrier and combine with advantageous mechanical properties for a roof underlay.

[0085] Preferably, the thickness of the support layer is between 0.4 mm and 5 mm, more preferably between 0.6 mm and 4 mm, and in particular between 0.8 mm and 2.5 mm, as determined according to DIN EN ISO 9073-2, 1997, section 5.1 General nonwovens.

[0086] In a preferred embodiment, the support layer consists of a first nonwoven layer comprising polyester fibers, a second nonwoven layer comprising modacrylic fibers and / or flame-retardant viscose fibers, and inorganic reinforcements in the form of glass fiber yarns, wherein the support layer is consolidated by needle punching, bonded with a polymeric binder, and has a basis weight of 50 g / m 2 up to 500 g / m 2 .

[0087] In a preferred embodiment, the flame-retardant layer of the support layer, which is the surface layer of the roof underlay, is printable and / or comprises an imprint. For example, the imprint can be an advertisement and / or information about the manufacturer. Such imprints are clearly visible to the public when the roof underlay is laid on a roof at a construction site until it is covered by further roofing material.

[0088] The subject matter of the present invention is also a building material comprising the support layer of the present invention. Preferably, the building material is a building material, in particular a roofing material. The building material is a flat material, which is preferably provided in the form of a roll. Typically, the support layer is coated or impregnated with a polymeric material such as asphalt or a synthetic polymer. In one embodiment, the support layer is not impregnated with asphalt.

[0089] The subject matter of the present invention is also a roof underlay comprising the support layer of the present invention and an asphalt layer, which is preferably provided on the surface of the first nonwoven layer comprising polyester fibers. Preferably, the asphalt layer is coated on the surface of the support layer.

[0090] In another embodiment, the building material comprises a support layer and a synthetic polymer applied to the support layer. Preferably, the building material is a membrane material, in particular a membrane roof; also known as white or non-bitumen membrane. Preferably, the membrane roof is a single-ply membrane. The synthetic polymer is preferably a synthetic rubber, a thermoplastic such as PVC or a modified bitumen. Typically, the support layer is coated or impregnated with the synthetic polymer. In such building material, the synthetic polymer forms a continuous layer, which is stabilized by the adjacent or integral support layer. The support layer serves as a carrier for the polymeric material. Typically, the building material is not porous. Preferably, such building material is used for the protection, covering and / or waterproofing of building components and surfaces. Thus, the synthetic polymer has a different function than the binder in a porous support layer, which is only used in much lower amounts to bind the fibers together.

[0091] The subject matter of the present application is also a roof or building comprising the support layer or the building material of the present application, in particular a roof membrane.

[0092] The subject matter of the present application is also the use of the support layer of the present application for the preparation of a building material, in particular a roof membrane.

[0093] Surprisingly, it was found that the support layer of the present application provides a novel and unique combination of advantageous properties for a building material such as a roof membrane. The support layer has excellent fire-retardant properties. In addition, the support layer can have mechanical properties such as high stability, elasticity and flexibility, which are advantageous for the preparation and use of a building material such as a roof membrane.

[0094] The support layer also has advantageous mechanical properties at high temperatures. High mechanical strength at high temperatures is advantageous because high integrity is required when the membrane is coated with molten bitumen, and when the roof is exposed to heat for a long time, for example in the sun and hot climates.

[0095] Preferably, the support layer passes the standard test for the fire barrier function of building and roof materials. In a preferred embodiment, the support layer passes the external fire exposure to roof test of EN 1187 (test 1 and / or 2).

[0096] The high maximum tensile strength, elongation at break and low tensile deformation at high temperature indicate that the support layer is stable and elastic. The mechanical properties are relevant because the support layer and the roof underlay can be easily processed and used. Damage such as cracks and ruptures can be prevented when the material is rolled, bent, pulled, nailed, pierced or compressed. Preferably, the maximum tensile strength of the support layer at 25°C is at least 250 N / 5 cm, more preferably at least 300 N / 5 cm. Preferably, the elongation at break of the support layer at 25°C is at least 10%, more preferably at least 15%, and in particular in the range of 10% to 50% or 15% to 40%. Thus, the roof underlay can be mechanically stable, but with a certain degree of elasticity. Unless otherwise stated, these parameters are determined in the machine direction, preferably in the machine direction and cross direction. Preferably, the tensile deformation and / or the maximum tensile strength are determined with a dynamometer having at least 10 or 20 test samples, each test sample being 50 mm (CD) x 180 mm (MD), the clamping length being 80 mm, and the unwinding speed being 100 mm / min.

[0097] The subject matter of the present invention is also a method for preparing a roof underlay, said method comprising the steps of providing a support layer of the present invention, and applying an asphalt layer on the surface of said first nonwoven layer, said first nonwoven layer comprising polyester fibers.

[0098] The subject matter of the present invention is also a method for producing a support layer of the present invention, said method comprising the steps of

[0099] (a) providing a first fiber layer, said first fiber layer comprising polyester fibers, and

[0100] (b) providing a second fiber layer, said second fiber layer comprising flame- retardant fibers, wherein the burning temperature of said flame-retardant fibers is at least 500°C, and / or the limiting oxygen index (LOI) of said flame-retardant fibers is at least 25%,

[0101] (c) optionally, providing a reinforcement,

[0102] (d) assembling said first fiber layer and said second fiber layer, and optionally said reinforcement, on top of each other, and

[0103] (e) mechanically consolidating said laminate.

[0104] In step (d), a laminate is provided made of the first nonwoven layer and the second nonwoven layer and optionally the reinforcement. Preferably, the components are continuously fed into a single production line and combined, preferably simultaneously. For example, a roll of preformed nonwoven sheet material can be unwound and continuously fed into the process. In a preferred embodiment, the second nonwoven layer is provided in a pre-needled form. It was found that such pre-treatment can provide a high stability and an efficient fire barrier. In another embodiment, the nonwoven layers or fibers thereof can be deposited on the surface of another layer, for example in a spunbond process. Preferably, after step (d), the method comprises the step of applying a binder to the laminate and consolidating the binder.

[0105] Preferably, the method is continuous. It is preferred that all layers, and if present the reinforcement, are combined in a single production line. Thereby, a laminate (stack of layers) for subsequent consolidation can be obtained. Preferably, the additional consolidation steps are performed in the same production line, like mechanical consolidation, binder impregnation and thermal consolidation. The support layer thus obtained is a sheet material, which is preferably provided in the form of a roll.

[0106] The support layer, the building material, the roof underlay, the use and the method of the present invention solve the underlying problems of the present invention. The present invention provides a novel support layer for a roof underlay, which has excellent fire barrier properties as well as high mechanical stability at room temperature and at elevated temperatures. Furthermore, the composite material can have a desired level of elasticity and flexibility, which is advantageous for the easy preparation and use of the roof underlay, but also for the stability of the roof. The composite product can be produced in a relatively simple and efficient process. It is stable and does not easily delaminate. Compared to conventional support layers based on glass fibers, the support layer has multiple advantages. First, the mechanical properties are much better, as the glass fibers impart an undesired stiffness to the material. Furthermore, the typical problems of glass fibers, like irritation, health issues and high manufacturing costs can be avoided.

[0107] Examples

[0108] Test methods

[0109] The tensile properties of the support layer, like the elongation at break and the tensile strength, are determined according to DIN EN ISO 9073-3:2023-09. The mass per unit area is determined according to DIN ISO 9073-1 :2023.

[0110] The mechanical properties at 180°C were determined by tensile stress testing under improved conditions as described in US 2008 / 0214716. The resistance to heat distortion was characterized by a tensile stress experiment at T = 180°C using a tear machine (dynamometer) with integrated thermostatic chamber. For each measurement, 5 test samples were prepared, each of 50 mm (CD) x 180 mm (MD). The clamping length was 80 mm and the unwinding speed was 100 mm / min. The elongation of the samples at 180°C was determined as the tensile force increased. The elongation of the 5 test samples was determined for a defined tensile force. The dynamometer measured the MD heat tensile distortion at various loads of 10 N, 30 N, 50 N and 80 N and the maximum tensile strength of each sample.

[0111] The fire propagation was determined in the standard roofing test EN 1187, method 1. The result in centimeters indicates the diameter of the charred area in cm. The charred area is a roughly circular point where the test sample has been converted to char. The charred area is characterized by the black / brown color of the char. This is not a hole in the test sample.

[0112] Examples 1 to 4

[0113] Preparation of the support layer

[0114] In examples 1 to 3, a support layer of the present application was produced and its properties were examined. The support layer was prepared from one modified polyacrylonitrile nonwoven layer, one polyester nonwoven layer and a reinforcement in the form of parallel glass fiber yarns between the nonwoven layers. The fiber materials and the binder are summarized in Table 1. The nonwoven layers were pre-consolidated as summarized in Table 2. The nonwoven layers were combined in a cross lapper, a conventional device for producing nonwoven laminates from precursor materials. Parallel reinforcement glass yarns were introduced from a guide nozzle through which loose yarns from spools were guided. The nonwoven laminate from the cross lapper was consolidated by needle penetration and heat treatment, followed by impregnation with the binder and curing. The consolidation steps and conditions are summarized in Table 3. All support layers were obtained in the form of flexible sheets, which can be conveniently rolled, laid out and handled.

[0115] In comparative example 4, a support layer was prepared according to example 1, but wherein the modified polyacrylonitrile fiber nonwoven layer was replaced by another polyester nonwoven layer. Nonwoven laminates based on PET fibers are used in the art as roofing underlays.

[0116] Table 1

[0117]

[0118] Table 2: Pre-treatment of fibers and layers

[0119]

[0120] Table 3: Continuous steps for processing the laminate from the cross-lapper

[0121]

[0122] Three different binders were used to reinforce the laminates. The binder compositions are shown in Table 4, and the binder components are shown in Table 5.

[0123] Table 4: Binder compositions for Examples 1 to 3

[0124]

[0125] Table 5: Binder components

[0126]

[0127] The amounts of binder and the basis weights of the individual layers are summarized in Table 6.

[0128] Table 6: Component basis weights [g / m2] 2 ]

[0129]

[0130] The properties of the support layers from Examples 1 and 4 were tested in the test methods as described above. The mechanical properties were tested at 25 °C (room temperature) and at 180 °C. The parameters, conditions, and results are summarized in Table 7.

[0131] Table 7: Properties of the support layers of Examples 1 to 4.

[0132]

[0133] The results show that the support layers of the present application made from one polyester nonwoven and one modified polyacrylonitrile nonwoven provide an effective fire barrier. The flame-retardant polymer and the flame-retardant additive can improve the fire barrier properties. The mechanical stability at low and high temperatures is high. The elongation at break indicates that the support layers have a certain level of elasticity, similar to the comparative material made from polyester fibers.

[0134] Examples 5 to 7

[0135] Support layers were prepared as described above for examples 1 to 3, but the second nonwoven layer was prepared from flame-retardant viscose staple fibers (3.3 dtex, 60 mm, LOI > 25) based on cellulose modified with sulfur-containing groups that release SO2 in the presence of fire. The same binders and amounts were used as described above for examples 1, 2 and 3. Thus, in example 5 the standard binder STD was used, in example 6 the FR1 binder with flame-retardant polymer was used, and in example 7 the FR2 binder with flame-retardant polymer and additive was used. The properties of the support layers were examined in the test methods described above. The parameters, conditions and results are summarized in table 8.

[0136] Table 8: Properties of the support layers of examples 4 to 7.

[0137]

[0138] The results show that the support layers of the present invention made from one polyester nonwoven and one fire-resistant viscose nonwoven provide an effective fire barrier. The flame-retardant polymer and the flame-retardant additive can improve the fire barrier properties. The mechanical stability at low and high temperatures is high. The elongation at break indicates that the support layers have a certain level of elasticity, similar to the comparative material made from polyester fibers.

[0139] While the subject matter of the present disclosure has been illustrated and described in the foregoing description, such illustration and description is to be considered as illustrative or exemplary only and not restrictive in character. Any statements of fact or descent herein made concerning the application are also intended to be illustrative or exemplary only and not restrictive in character. It is understood that changes and modifications can be made by those of ordinary skill within the scope of the following claims, including combinations of features from different embodiments described herein, which can include any combination of features described above.

[0140] The use of the terms "first", "second", and the like in the claims are used for clarity of description and are not necessarily intended to convey a meaning of priority or order. The terms "first", "second", and the like are used to distinguish a plurality of elements from one another. The use of the terms "first", "second", and the like in the claims is not intended to limit the number of elements to two in any claim. The use of the terms "first", "second", and the like in the claims is intended to convey that the elements are separate and distinct from one another. The use of the terms "first", "second", and the like in the claims is not intended to limit the number of elements to two in any claim. The use of the terms "first", "second", and the like in the claims is intended to convey that the elements are separate and distinct from one another. The use of the terms "first", "second", and the like in the claims is not intended to limit the number of elements to two in any claim. The use of the terms "first", "second", and the like in the claims is intended to convey that the elements are separate and distinct from one another. The use of the terms "first", "second", and the like in the claims is not intended to limit the number of elements to two in any claim. The use of the terms "first", "second", and the like in the claims is intended to convey that the elements are separate and distinct from one another.

Claims

1. A porous support layer for a roof underlay, the porous support layer comprising a first nonwoven layer comprising polyester fibers, and a second nonwoven layer comprising organic flame retardant fibers, wherein the flame retardant fibers have a burning temperature of at least 500 °C and / or an limiting oxygen index (LOI) of at least 25 %, wherein the second nonwoven layer is a surface layer of the support layer, wherein the second nonwoven layer does not comprise inorganic nonwoven fibers, wherein the support layer is mechanically reinforced, preferably by needle punching.

2. The support layer according to claim 1, wherein the flame retardant fibers comprise a fiber polymer, the fiber polymer comprising at least one element selected from the group consisting of CI, Br, P, S and Si.

3. The support layer according to at least one of the preceding claims, wherein the flame retardant fibers are charring.

4. Support layer according to at least one of the preceding claims, wherein the flame- retardant fibers are infusible, or T P (temperature of pyrolysis) - T M (melting temperature) is less than 50°C, preferably less than 30°C.

5. The support layer according to at least one of the preceding claims, wherein the flame retardant fibers are selected from the group consisting of modacrylic fibers, flame- retardant viscose fibers, polyacrylonitrile (PAN) fibers, partially oxidized polyacrylonitrile (PANOX) fibers, polyphenylene benzobisoxazole (PBO) fibers, polybenzimidazole (PBI) fibers and / or melamine fibers, wherein preferably the flame retardant fibers are modacrylic fibers and / or flame-retardant viscose fibers.

6. The support layer according to at least one of the preceding claims, wherein the support layer does not comprise a further layer, and / or wherein the first nonwoven layer consists of the polyester fibers and / or the second nonwoven layer consists of the flame retardant fibers, and / or wherein the support layer has a basis weight of 50 g / m 2 up to 500 g / m 2 .

7. The support layer according to at least one of the preceding claims, wherein the support layer comprises reinforcements, preferably inorganic reinforcements, wherein the reinforcements preferably comprise glass fiber yarns, which are preferably aligned in parallel.

8. The support layer according to at least one of the preceding claims, wherein the support layer is reinforced with a polymeric binder.

9. The support layer according to claim 8, wherein the polymeric binder comprises a halogenated polymer, preferably a copolymer of vinyl chloride, and / or wherein the polymeric binder comprises at least one flame retardant additive, which is preferably a phosphorous containing compound.

10. A building material comprising the support layer according to at least one of the preceding claims.

11. The building material according to claim 10, wherein the building material is in the form of a roof underlay, the building material comprising an asphalt layer, which is arranged on the support layer on a surface of the first nonwoven layer, the first nonwoven layer comprising polyester fibers.

12. A roof or building, wherein the roof or building comprises the building material according to claim 10 or 11.

13. Use of the support layer according to at least one of claims 1 to 10 for the production of a roof underlay.

14. A method for manufacturing the support layer according to any one of claims 1 to 10, the method comprising the following steps:

15. The method according to claim 14, wherein the method further comprises the step of:

16. The method according to claim 14 or 15, wherein the method further comprises the step of:

17. The method according to at least one of claims 14 to 16, wherein the method further comprises the step of:

18. The method according to at least one of claims 14 to 17, wherein the method further comprises the step of:

19. The method according to at least one of claims 14 to 18, wherein the method further comprises the step of:

20. The method according to at least one of claims 14 to 19, wherein the method further comprises the step of:

21. The method according to at least one of claims 14 to 20, wherein the method further comprises the step of:

22. The method according to at least one of claims 14 to 21, wherein the method further comprises the step of:

23. The method according to at least one of claims 14 to 22, wherein the method further comprises the step of:

24. The method according to at least one of claims 14 to 23, wherein the method further comprises the step of:

25. The method according to at least one of claims 14 to 24, wherein the method further comprises the step of:

26. The method according to at least one of claims 14 to 25, wherein the method further comprises the step of:

27. The method according to at least one of claims 14 to 26, wherein the method further comprises the step of:

28. The method according to at least one of claims 14 to 27, wherein the method further comprises the step of:

29. The method according to at least one of claims 14 to 28, wherein the method further comprises the step of:

30. The method according to at least one of claims 14 to 29, wherein the method further comprises the step of:

31. The method according to at least one of claims 14 to 30, wherein the method further comprises the step of:

32. The method according to at least one of claims 14 to 31, wherein the method further comprises the step of:

33. The method according to at least one of claims 14 to 32, wherein the method further comprises the step of:

34. The method according to at least one of claims 14 to 33, wherein the method further comprises the step of:

35. The method according to at least one of claims 14 to 34, wherein the method further comprises the step of:

36. The method according to at least one of claims 14 to 35, wherein the method further comprises the step of:

37. The method according to at least one of claims 14 to 36, wherein the method further comprises the step of:

38. The method according to at least one of claims 14 to 37, wherein the method further comprises the step of:

39. The method according to at least one of claims 14 to 38, wherein the method further comprises the step of:

40. The method according to at least one of claims 14 to 39, wherein the method further comprises the step of:

41. The method according to at least one of claims 14 to 40, wherein the method further comprises the step of:

42. The method according to at least one of claims 14 to 41, wherein the method further comprises the step of:

43. The method according to at least one of claims 14 to 42, wherein the method further comprises the step of:

44. The method according to at least one of claims 14 to 43, wherein the method further comprises the step of:

45. The method according to at least one of claims 14 to 44, wherein the method further comprises the step of:

46. The method according to at least one of claims 14 to 45, wherein the method further comprises the step of:

47. The method according to at least one of claims 14 to 46, wherein the method further comprises the step of:

48. The method according to at least one of claims 14 to 47, wherein the method further comprises the step of:

49. The method according to at least one of claims 14 to 48, wherein the method further comprises the step of:

50. The method according to at least one of claims 14 to 49, wherein the method further comprises the step of:

51. The method according to at least one of claims 14 to 50, wherein the method further comprises the step of:

52. The method according to at least one of claims 14 to 51, wherein the method further comprises the step of:

53. The method according to at least one of claims 14 to 52, wherein the method further comprises the step of:

54. The method according to at least one of claims 14 to 53, wherein the method further comprises the step of:

55. The method according to at least one of claims 14 to 54, wherein the method further comprises the step of:

56. The method according to at least one of claims 14 to 55, wherein the method further comprises the step of:

57. The method according to at least one of claims 14 to 56, wherein the method further comprises the step of:

58. The method according to at least one of claims 14 to 57, wherein the method further comprises the step of:

59. The method according to at least one of claims 14 to 58, wherein the method further comprises the step of:

60. The method according to at least one of claims 14 to 59, wherein the method further comprises the step of:

61. The method according to at least one of claims 14 to 60, wherein the method further comprises the step of:

62. The method according to at least one of claims 14 to 61, wherein the method further comprises the step of:

63. The method according to at least one of claims 14 to 62, wherein the method further comprises the step of:

64. The method according to at least one of claims 14 to 63, wherein the method further comprises the step of:

65. The method according to at least one of claims 14 to 64, wherein the method further comprises the step of:

66. The method according to at least one of claims 14 to 65, wherein the method further comprises the step of:

67. The method according to at least one of claims 14 to 66, wherein the method further comprises the step of:

68. The method according to at least one of claims 14 to (a) providing a first fibrous layer, said first fibrous layer comprising polyester fibres, and (b) providing a second fibrous layer, said second fibrous layer comprising said flame retardant fibres, (c) optionally, providing a reinforcement, (d) assembling said first fibrous layer and said second fibrous layer, and optionally said reinforcement, on top of each other to form a laminate, and (e) mechanically consolidating said laminate.

15. A method for preparing a roofing underlay, the method comprising the steps of: providing a support layer according to at least one of claims 1 to 10, and applying an asphalt layer on a surface of said first nonwoven layer comprising polyester fibres.

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