A polymer composition having improved mechanical properties

Abstract

The invention is directed to a polymer composition comprising: a) At least one propylene copolymer PCP, b) At least one thermoplastic vulcanizate TPV, c) At least one thermoplastic polyolefin elastomer TPO different from the propylene copolymer PCP, and d) At least one flame retardant FR selected from magnesium hydroxide and aluminum trihydroxide. The invention is also directed to a sealing element comprising a waterproof layer obtained by using the polymer composition.

Description

[0001] A POLYMER COMPOSITION HAVING IMPROVED MECHANICAL PROPERTIES

[0002] Technical field

[0003] The invention relates to polymer compositions suitable for providing sealing elements, particularly membranes, for sealing of below and above ground structures against penetration of water. Particularly, the invention relates to polymer compositions having improved mechanical properties despite of high content of inorganic particles.

[0004] Background of the invention

[0005] In the field of construction polymeric sheets, which are often referred to as membranes or panels, are used to protect underground and above ground constructions, such as basements, tunnels, or roofs against penetration of water. Waterproofing membranes are applied, for example, to prevent ingress of water through cracks that develop in the concrete structure due to building settlement, load deflection or concrete shrinkage.

[0006] Roofing membranes are commonly used for waterproofing of flat and low-sloped roof structures.

[0007] The membranes are typically delivered to a construction site in form of rolls, transferred to the place of installation, unrolled, and adhered to the substrate to be waterproofed. Waterproofing membranes are also used in form of tapes for sealing and waterproofing of construction gaps in building facades, for example gaps between a building structure and window or curtain wall components.

[0008] Roofing membranes must be securely fastened to the roof substrate to provide sufficient mechanical strength to resist the shearing forces applied on it due to high wind loads. Furthermore, adjacent membranes are typically overlapped along the length of the membrane at the selvage edge in order to create a continuous waterproofing seal on the surface of the substrate to be waterproofed. The opposing surfaces of the overlapping portions are then bonded to each other by using an adhesive (“bonded seams”) or by heatwelding (“welded seams”). The choice between bonded and welded seams depends on the composition of the membranes. Commonly used materials for roofing and waterproofing membranes include plastics, especially thermoplastics such as plasticized polyvinylchloride (p-PVC), thermoplastic polyolefin elastomers (TPO, TPE-O), and elastomers such as ethylene-propylene diene monomer (EPDM) rubber. Thermoplastic polyolefin elastomers are heterophasic polymer systems comprising a high crystallinity base polyolefin and a low-crystallinity or amorphous polyolefin modifier. Waterproofing membranes based on crosslinked EPDM are very flexible and resistant to weathering, but joints formed between overlapped portions of adjacent membranes cannot be sealed by heat-welding due to the chemically crosslinked polymer structure. Membranes composed of TPO materials are heat-weldable and less expensive than EPDM-membranes, but they are also more rigid, which can be a disadvantage in some applications. Membranes based on plasticized PVC are more flexible than membranes based on TPO materials, but they also contain environmentally harmful plasticizers and heavy metal additives such as flame retardants that may restrict their use in some applications.

[0009] A common disadvantage of the polymeric materials is their inherently low fire resistance properties. The limiting oxygen index (LOI) of most polymeric materials is less than 25%, which make them flammable or combustible. Generally, construction products composed of polymeric materials must fulfill certain fire resistance requirements, i.e. , to achieve a specific “fire rating classification”.

[0010] Flame retardants are typically added to polymer blends to improve their fire resisting / retarding properties to enable their use in various applications. Commonly used flame retardants for polymeric membranes include metal hydroxides, particularly aluminum trihydrate (ATH), precipitated aluminum hydrates, magnesium hydroxide, and brominated flame retardants (BRF). Halogenated flame retardants, particularly brominated retardants, are highly effective in achieving the requirements for fire classification, but their use is not preferred for environmental and safety issues. In fact, the use of brominated flame retardants has already been banned in some applications.

[0011] The disadvantage of halogen-free flame retardants is their inferior efficiency compared to other types of flame retardants. Consequently, the amount of flame retardants added to a polymer blend to achieve a desired fire rating can be very high, which typically has a significant adverse effect on the mechanical properties of the polymer material. For example, TPO-based roofing membranes can contain up to 60 wt.-% of ATH to comply with the fire rating requirements. The use of high amounts of inorganic flame retardants particularly decreases the flexibility of the polymer blend, especially at low temperatures, which is a critical feature of roofing membranes.

[0012] There thus remains a need for a novel type of halogen free polymer composition having excellent flame retardancy and mechanical properties, particularly good cold flexibility. Such polymer compositions are especially suitable for use in the construction industry, for example, for providing sealing elements, particularly for providing thermoplastic roofing membranes.

[0013] Summary of the invention

[0014] The object of the present invention is to provide a polymer composition suitable for providing sealing elements, which can be used for sealing of underground and above ground constructions, especially roof substrates, against penetration of water.

[0015] Surprisingly, it has been found out that the objects can be achieved with the features of claim 1.

[0016] Specifically, according to the invention, a polymer composition is proposed, the polymer composition comprising: a) At least one propylene copolymer PCP, b) At least one thermoplastic vulcanizate TPV, c) At least one thermoplastic polyolefin elastomer TPO different from the propylene copolymer PCP, and d) At least one flame retardant FR selected from magnesium hydroxide and aluminum tri hydrate.

[0017] As it turned out, the suggested polymer composition provides required flame retardancy properties without use of halogenated flame retardants and excellent mechanical properties, particularly high flexibility at low temperatures, despite high content of inorganic particles. Additional aspects of the present invention are presented in further independent claims. Preferred embodiments of the invention are outlined throughout the description and the dependent claims.

[0018] Detailed description of the invention

[0019] The subject of the present invention is a polymer composition comprising: a) At least one propylene copolymer PCP, b) At least one thermoplastic vulcanizate TPV, c) At least one thermoplastic polyolefin elastomer TPO different from the propylene copolymer PCP, and d) At least one flame retardant FR selected from magnesium hydroxide and aluminum tri hydrate.

[0020] Substance names beginning with "poly" designate substances which formally contain, per molecule, two or more of the functional groups occurring in their names. For instance, a polyol refers to a compound having at least two hydroxyl groups. A polyether refers to a compound having at least two ether groups.

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

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

[0023] The term “melting temperature (Tm)” refers to a melting point determined as a maximum of the curve determined by means of differential scanning calorimetry (DSC) using the measurement method as defined in ISO 11357-3:2018 standard using a heating rate of 2°C / min. The measurements can be performed with a Mettler Toledo DSC 3+ device and the Tm values can be determined from the measured DSC-curve with the help of the DSC- software. In case the measured DSC-curve shows several peak temperatures, the first peak temperature coming from the lower temperature side in the thermogram is taken as the melting temperature (Tm).

[0024] The term “glass transition temperature” (Tg) refers to the temperature above which temperature a polymer component becomes soft and pliable, and below which it becomes hard and glassy. The glass transition temperature (Tg) is preferably determined by dynamical mechanical analysis (DMA) as the peak of the measured loss modulus (G”) curve using an applied frequency of 1 Hz and a strain level of 0.1 %.

[0025] “Comonomer content of a copolymer” refers to the total amount of comonomers in the copolymer given in wt.-% or mol-%. The comonomer content can be determined by IR spectroscopy or by quantitative nuclear-magnetic resonance (NMR) measurements.

[0026] The term “thermoplastic polymer” refers in the present disclosure to polymers which can be melted and re-solidified with little or no change in physical properties.

[0027] The term “elastomer” designates a polymer or a polymer blend, which is capable of recovering from large deformations, and which can be, or already is, modified to a state in which it is essentially insoluble (but can swell) in a boiling solvent, in particular xylene. Typical elastomers are capable of being elongated or deformed to at least 200% of their original dimension under an externally applied force, and will substantially resume the original dimensions, sustaining only small permanent set (typically no more than about 20%), after the external force is released. As used herein, the term “elastomer” may be used interchangeably with the term “rubber.” The term “crosslinked” refers to a polymer matrix, in which the polymer chains are interconnected by a plurality of covalent bonds that are stable mechanically and thermally. Other possible forms of crosslinked polymers such as physically crosslinked polymers are not regarded as “crosslinked” in the context of the present disclosure. The terms “cured” and “vulcanized” may be used interchangeably with the term “crosslinked”.

[0028] The term “crosslinking degree” refers to a proportion of the component, which is insoluble in boiling xylene. The percentage of insoluble proportion can be determined by refluxing a test specimen in boiling xylene, weighting the dried residue and making suitable corrections for other soluble and insoluble components present in the tested composition. Preferably, the crosslinking degree is measured by using a method as defined in ISO 10147:2011 standard.

[0029] The “amount or content of at least one component X” in a composition, for example “the amount of the at least one propylene copolymer POP” refers to the sum of the individual amounts of all propylene copolymers PCP contained in the composition. Furthermore, in case the composition comprises 20 wt.-% of at least one propylene copolymer PCP, the sum of the amounts of all propylene copolymers PCP contained in the composition equals 20 wt.-%.

[0030] The term “room temperature” designates a temperature of 23°C.

[0031] The polymer composition comprises at least one flame retardant FR selected from magnesium hydroxide and aluminum trihydrate.

[0032] Magnesium hydroxide (Mg(OH)2) and aluminum trihydrate (AI(OH)s) are commonly used as flame retardants. These are commercially available as surface coated and non-coated types. Aluminum trihydrate, also known as the mineral gibbsite (hydrargillite), is available as milled and precipitated types. Magnesium hydroxide is mainly obtained by precipitation from brines and sea water or via hydration of magnesium oxide.

[0033] Especially, the at least one flame retardant FR is present in the polymer composition in an amount of at least 5 wt.-%, preferably at least 10 wt.-%, based on the total weight of the polymer composition. In one or more embodiments, the at least one flame retardant FR is present in the polymer composition in an amount of 5 - 50 wt.-%, preferably 15 - 45 wt.-%, more preferably 25 - 40 wt.-%, based on the total weight of the polymer composition. Polymer compositions comprising the at least one flame retardant FR in an amount falling within the above cited ranges have been found out to be especially suitable for providing membranes used for sealing of below and above ground structures against penetration of water, particularly roofing membranes.

[0034] In one or more embodiments, the at least one flame retardant FR is selected from surface- coated magnesium hydroxide and surface-coated aluminum trihydrate.

[0035] Suitable as the coating are in particular hydrophobic organic substances which are physically or chemically applied to the surface of the flame retardant particles by means of a suitable process. Such coating processes are known to a person skilled in the art and suitable coated types of magnesium hydroxide and aluminum trihydrate are commercially available.

[0036] The surface coating may particularly be present in the particles of the flame retardant FR in an amount of 0.01 - 5 wt.-%, preferably 0.1 - 1 wt.-%, based on the weight of the flame retardant FR.

[0037] Especially preferred as the surface coating for the flame retardant FR are silanes, particularly alkylalkoxysilanes, especially alkyltrialkoxysilanes, which by hydrolysis and condensation form an at least partially hydrophobic alkyl silicate layer on the surface of the particles. Very particularly preferred alkylalkoxysilanes are for example vinylalkoxysilanes, such as vinyltrimethoxysilane.

[0038] Likewise preferred as the surface coating the flame retardant FR are fatty acids. These form a hydrophobic shell around the particles. A very particularly preferred fatty acid is for example stearic acid.

[0039] In one of more embodiments, the at least one flame retardant FR comprises a surface coating of silanes or fatty acids, preferably of silanes, particularly alkyl silanes or alkylalkoxysilanes. In one or more preferred embodiments, the at least one flame retardant FR is selected from surface-coated magnesium hydroxide and surface-coated aluminum trihydrate, preferably from precipitated surface coated magnesium hydroxide and precipitated surface coated aluminum trihydrate, preferably comprising a surface coating of silanes or fatty acids, particularly a surface coating of silanes, especially alkyl silanes or alkylalkoxysilanes.

[0040] Suitable surface coated aluminum trihydrate are commercially available, for example, under the trade names of Martinal® and Magnifin® (both from Martinswerk GmbH). For example, precipitated fatty acid-coated ATH is available under the trade name Martinal® OL 104 C and precipitated vinylsilane-coated ATH is obtainable under the trade name Martinal® OL 104 ZO (both from Martinswerk, Germany).

[0041] In one or more further embodiments, the at least one flame retardant FR is a surface- coated magnesium hydroxide, preferably a precipitated surface coated magnesium hydroxide, preferably a surface coating of silanes or fatty acids, particularly a surface coating of silanes, especially alkyl silanes or alkylalkoxysilanes. The use of magnesium hydroxide-based flame retardant may be preferred over aluminum trihydrate in applications, where the polymer composition is exposed during processing of the composition to high temperatures, such as higher than 200 °C.

[0042] The polymer composition comprises as the first polymer component at least one propylene copolymer PCP.

[0043] In one or more embodiments, the at least one propylene copolymer PCP is present in the polymer composition in an amount of 10 - 65 wt.-%, preferably 15 - 50 wt.-%, more preferably 20 - 45 wt.-%, even more preferably 25 - 45 wt.-%, based on the total weight of the polymer composition.

[0044] In one or more embodiments, the at least one propylene copolymer PCP has:

[0045] - a flexural modulus at 23°C determined according to ISO 178:2019 standard of not more than 100 MPa, preferably not more than 75 MPa, more preferably not more than 65 MPa, even more preferably not more than 50 MPa and / or - a xylene cold soluble content determined according to ISO 16152:2005 standard of at least 70 wt.-%, preferably at least 80 wt.-%, more preferably at least 90 wt.-%, even more preferably at least 95 wt.-%, still more preferably at least 99 wt.-% and / or

[0046] - a softening point determined by Ring and Ball measurement conducted according to ISO 4625-1 :2020 standard of not more than 95 °C, preferably not more than 75 °C, more preferably not more than 70 °C, even more preferably not more than 65 °C and / or

[0047] - a melt flow rate (230°C / 2.16 kg) determined according to ISO 1133 standard of not more than 50 g / 10 min, preferably not more than 40 g / 10 min, more preferably not more than 35 g / 10 min, even more preferably not more than 30 g / 10 min and / or

[0048] - a density at 23 °C determined according to ASTM D-792 standard of 0.850 - 0.900 g / cm3, preferably 0.855 - 0.890 g / cm3.

[0049] Preferably, the at least one propylene copolymer PCP has a propylene content of at least 60 wt.-%, more preferably at least 70 wt.-%, based on the weight of the propylene copolymer.

[0050] In one or more embodiments, the at least one propylene copolymer PCP is a is a propylene-ethylene copolymer, preferably a random propylene-ethylene copolymer, preferably having an ethylene content of 5 - 20 wt.-%, more preferably 9 - 18 wt.-%, even more preferably 12 - 18 wt.-%, based on the weight of the propylene copolymer.

[0051] Suitable propylene ethylene copolymers are commercially available, for example, under the trade name of Versify® (from Dow Chemicals) and under the trade name of Vistamaxx® (from Exxon Mobil).

[0052] The polymer composition further comprises, in addition to the propylene copolymer PCP, at least one thermoplastic vulcanizate TPV.

[0053] The term “thermoplastic vulcanizate” refers in the present disclosure to a composition comprising a at least partially vulcanized rubber component dispersed into a matrix of a plastic component.

[0054] Thermoplastic vulcanizates can be prepared by a dynamic vulcanization process in which a rubber component is selectively vulcanized during mixing of a blend comprising the rubber component and the plastic component while minimally affecting the plastic component. Vulcanization of the rubber component is typically not initiated before a well- mixed polymer blend is formed and the mixing is continued during the vulcanization step. State-of-the-Art commercially available TPVs typically comprise a thermoplastic matrix that is filled with micrometer size partially or fully crosslinked rubber particles. Processing oils are also used for improving the melt-processing properties of TPV compositions.

[0055] Examples of TPVs and production processes therefor are disclosed, for example, in US 7294675 B2.

[0056] The term “thermoplastic vulcanizate (TPV)” refers in the present disclosure to ones prepared by dynamic vulcanization process as discussed above. Suitable thermoplastic vulcanizates are commercially available, for example, under the trade name of Milastomer® (from Mitsui Chemicals) and under the trade name of Santoprene® (from Exxon Mobil).

[0057] In one or more embodiments, the at least one thermoplastic vulcanizate TPV is present in the polymer composition in an amount of 0.5 - 15 wt.-%, preferably 2.5 - 12.5 wt.-%, more preferably 3.5 - 10 wt.-%, based on the total weight of the polymer composition.

[0058] Preferably, the at least one thermoplastic vulcanizate TPV comprises a blend of a thermoplastic resin and particles of a at least partially vulcanized rubber dispersed throughout a matrix of the thermoplastic resin. The term “matrix” refers here to a continuous phase of the thermoplastic resin.

[0059] Suitable rubbers for use in the blend of the at least one thermoplastic vulcanizate TPV include, for example, butyl rubber, halogenated butyl rubber, ethylene-propylene diene rubber, natural rubber, chloroprene rubber, synthetic 1 ,4-cis-polyisoprene, polybutadiene, ethylene-propylene rubber, styrene-butadiene copolymer, isoprene-butadiene copolymer, styrene-isoprene-butadiene rubber, methyl methacrylate-butadiene copolymer, methyl methacrylate-isoprene copolymer, acrylonitrile-isoprene copolymer, and acrylonitrilebutadiene copolymer.

[0060] According to one or more embodiments, the rubber is selected from the group consisting of butyl rubber, halogenated butyl rubber, ethylene-propylene diene rubber, natural rubber, synthetic 1 ,4-cis-polyisoprene, polybutadiene, and ethylene-propylene rubber. The term “butyl rubber” designates in the present disclosure a polymer derived from a monomer mixture containing a major portion of a C4 to C? monoolefin monomer, preferably an isoolefin monomer and a minor portion, such as not more than 30 wt.-%, of a C4 to C14 multiolefin monomer, preferably a conjugated diolefin. The preferred C4 to C? monoolefin monomer is preferably selected from the group consisting of isobutylene, 2-methyl-1- butene, 3-methyl-1 -butene, 2-methyl-2-butene, 4-methyl-1 -pentene, and mixtures thereof. The term “ethylene propylene diene rubber” refers in the present disclosure to terpolymer of ethylene, propylene and a non-conjugated diene. Non-limiting examples of suitable nonconjugated dienes to be used in an ethylene propylene diene rubber include, for example, 5-ethylidene-2-norbornene (ENB); 1 ,4-hexadiene; 5-methylene-2-norbornene (MNB); 1 ,6- octadiene; 5-methyl-1 ,4-hexadiene; 3,7-dimethyl-1 ,6-octadiene; 1 ,4-cyclohexadiene; tetrahydroindene; methyltetrahydroindene; dicyclopentadiene; 5-isopropylidene-2- norbornene; and 5-vinyl-norbornene.

[0061] Suitable thermoplastic resins for use in the blend of the at least one thermoplastic vulcanizate TPV include, for example, polyolefins, such as polyethylene, ethylene copolymers, polypropylene and propylene copolymers. According to one or more embodiments, the thermoplastic resin comprises a propylene copolymer, preferably a random propylene copolymer, preferably having a melting temperature determined by DSC according to 11357-3:2018 standard using a heating rate of 2 °C / min of not more than 135 °C, more preferably not more than 115 °C, even more preferably not more than 105 °C.

[0062] According to one or more embodiments, the blend of the at least one thermoplastic vulcanizate TPV comprises 15 - 75 parts by weight of the thermoplastic resin and 25 - 85 parts by weight of the at least partially vulcanized rubber per 100 parts total weight of the thermoplastic resin and the at least partially vulcanized rubber.

[0063] According to one or more embodiments, the blend of the at least one thermoplastic vulcanizate TPV further comprises 10 - 300 parts by weight, preferably 50 - 250 parts by weight, of an additive oil per 100 parts by weight of the at least partially vulcanized rubber.

[0064] Preferred additive oils for use in the blend include process oils, such as mineral oils, synthetic oils, vegetable oils, and liquid polyolefin resins as well as organic esters and synthetic plasticizers. The term “mineral oil” refers in the present disclosure hydrocarbon liquids of lubricating viscosity (i.e. , a kinematic viscosity at 100°C of 1 cSt or more) derived from petroleum crude oil and subjected to one or more refining and / or hydroprocessing steps, such as fractionation, hydrocracking, dewaxing, isomerization, and hydrofinishing, to purify and chemically modify the components to achieve a final set of properties. In other words, the term “mineral” refers in the present disclosure to refined mineral oils, which can be also characterized as Group l-lll base oils according to the classification of the American Petroleum Institute (API).

[0065] Suitable mineral oils to be used as the additive oil include paraffinic, naphthenic, and aromatic mineral oils. Particularly suitable mineral oils include paraffinic and naphtenic oils containing relatively low amounts of aromatic moieties, such as not more than 25 wt.-%, preferably not more than 15 wt.-%, based on the total weight of the mineral oil.

[0066] The term "synthetic oil” refers in the present disclosure to full synthetic (polyalphaolefin) oils, which are also known as Group IV base oils according to the classification of the American Petroleum Institute (API). Suitable synthetic oils are produced from liquid polyalphaolefins (PAOs) obtained by polymerizing a-olefins in the presence of a polymerization catalyst, such as a Friedel-Crafts catalyst. In general, liquid PAOs are high purity hydrocarbons with a paraffinic structure and high degree of side-chain branching. Particularly suitable synthetic oils include those obtained from so-called Gas-To-Liquids processes.

[0067] Suitable liquid polyolefin resins to be used as the additive oil include liquid polybutene and liquid polyisobutylene (PI B). The term “liquid polybutene” refers in the present document to at 25°C liquid low molecular weight olefin oligomers comprising isobutylene and / or 1- butene and / or 2-butene. The ratio of the C4-olefin isomers can vary by manufacturer and by grade. When the C4-olefin is exclusively 1 -butene, the material is referred to as "poly-n- butene" or “PNB”. The term “liquid polyisobutylene” refers in the present document to low molecular weight polyolefins and olefin oligomers of isobutylene. Particularly suitable liquid polybutenes and liquid polyisobutylenes have a number average molecular weight (Mn) of less than 15000 g / mol, preferably less than 5000 g / mol, more preferably less than 3500 g / mol. According to one or more embodiments, the at least partially vulcanized rubber has a crosslinking degree determined by using the method as defined in ISO 10147:2011 standard of at least 50 wt.-%, preferably at least 75 wt.-%, more preferably at least 80 wt.- %, even more preferably at least 90 wt.-%.

[0068] The polymer composition of the present invention further comprises at least one thermoplastic polyolefin elastomer TPO. It goes without saying that the at least one thermoplastic polyolefin elastomer TPO is different from the at least one propylene copolymer PCP and the at least one thermoplastic vulcanizate TPV.

[0069] The term “thermoplastic polyolefin elastomer (TPO, TPE-O)” refers to specific type of thermoplastic elastomers (TPE), which are provided as physical or reactor blends of olefinic constituents. TPOs are heterophasic polymer systems comprising a high crystallinity base polyolefin and a low-crystallinity or amorphous polyolefin modifier. The heterophasic phase morphology consists of a matrix phase composed primarily of the base polyolefin and a dispersed phase composed primarily of the polyolefin modifier. Commercially available TPOs include reactor blends of the base polyolefin and the polyolefin modifier, also known as “in-situ TPOs” or “reactor TPOs or “impact copolymers (ICP)”, as well as physical blends of the aforementioned components. In case of a reactorblend type of TPO, the components are typically produced in a sequential polymerization process, wherein the components of the matrix phase are produced in a first reactor and transferred to a second reactor, where the components of the dispersed phase are produced and incorporated as domains in the matrix phase. A physical-blend type of TPO is produced by melt-mixing the base polyolefin with the polyolefin modifier each of which was separately formed prior to blending of the components.

[0070] Reactor-blend type TPOs comprising polypropylene homopolymer as the base polymer are often referred to as “heterophasic propylene copolymers (HECO)” whereas reactorblend type TPOs comprising propylene random copolymer as the base polymer are often referred to as “heterophasic propylene random copolymers (RAH ECO)”. The term “heterophasic propylene copolymer” encompasses in the present disclosure both the HECO and RAHECO types of heterophasic propylene copolymers.

[0071] Depending on the amount of the polyolefin modifier, the commercially available heterophasic propylene copolymers are typically characterized as “impact copolymers” (ICP) or as “reactor-TPOs” or as “soft-TPOs”. The main difference between these types of TPOs is that the amount of the polyolefin modifier is typically lower in ICPs than in reactor- TPOs and soft-TPOs, such as not more than 40 wt.-%, particularly not more than 35 wt.- %. Consequently, typical ICPs tend to have a lower xylene cold soluble (XCS) content determined according to ISO 16152:2005 standard as well as higher flexural modulus determined according to ISO 178:2019 standard compared to reactor-TPOs and soft- TPOs.

[0072] In one or more embodiments, the at least one thermoplastic polyolefin elastomer TPO is present in the polymer composition in an amount of 5 - 50 wt.-%, preferably 10 - 40 wt.- %, more preferably 15 - 35 wt.-%, based on the total weight of the polymer composition.

[0073] In one or more embodiments, the at least one thermoplastic polyolefin elastomer TPO has:

[0074] - a flexural modulus at 23°C determined according to ISO 178:2019 standard of at least 400 MPa, preferably at least 500 MPa, more preferably at least 600 MPa and / or

[0075] - a melting temperature determined by DSC according to ISO 11357-3:2018 standard using a heating rate of 2°C / min of at least 100°C, preferably at least 110°C, more preferably at least 120°C, even more preferably at least 130°C, still more preferably at least 135 °C and / or

[0076] - a melt flow rate (230°C / 2.16 kg) determined according to ISO 1133 standard of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min, even more preferably not more than 35 g / 10 min and / or

[0077] - a xylene cold soluble content determined according to ISO 16152:2005 standard of at least 5 wt.-%, preferably at least 15 wt.-%, more preferably at least 25 wt.-%, even more preferably at least 35 wt.-%, particularly in the range of 5 - 90 wt.-%, preferably 15 - 85 wt.-%, more preferably 25 - 80 wt.-%, even more preferably 35 - 75 wt.-%.

[0078] In one or more embodiments, the at least one thermoplastic polyolefin elastomer TPO is a heterophasic propylene copolymer, preferably comprising:

[0079] - A) at least one polypropylene having a melting temperature (Tm) of 100°C or more, preferably a propylene homopolymer and / or a random copolymer of propylene having a comonomer content of less than 10 wt.-%, preferably less than 5 wt.-%, based on the weight of the copolymer and - B) at least one polyolefin having a glass transition temperature (Tg) of -20°C or less, preferably an ethylene copolymer having a comonomer content of at least 5 wt.-%, preferably at least 10 wt.-%, based on the weight of the copolymer, preferably having a glass transition temperature (Tg) of -25°C or less, more preferably -35°C or less, preferably an ethylene-propylene rubber (EPR), wherein the heterophasic propylene copolymer comprises a matrix phase composed primarily of A) and a dispersed phase composed primarily of B).

[0080] According to one or more embodiments, the heterophasic propylene copolymer is a reactor blend of A) and B), wherein the reactor blend has preferably been obtained by using a sequential polymerization process, wherein constituents of the matrix phase are produced in a first reactor and transferred to a second reactor where constituents of the dispersed phase are produced and incorporated as domains into the matrix phase.

[0081] Particularly suitable heterophasic propylene copolymers include, for example, “reactor TPOs” and “soft TPOs” produced with LyondellBasell's Catalloy process technology, which are available under the trade names of Adflex®, Adsyl®, Clyrell®, Hifax®, Hiflex®, and Softell®, such as Hifax® CA 10A, Hifax® CA 12A, and Hifax® CA 60 A, and Hifax® CA 212 A. Further suitable heterophasic propylene copolymers are commercially available under the trade name of Borsoft® (from Borealis Polymers), such as Borsoft® SD233 CF.

[0082] In one or more embodiments, the sum of the amounts of the at least one propylene copolymer PCP, the at least one thermoplastic vulcanizate TPV, and the at least one thermoplastic polyolefin elastomer TPO makes up at least 35 wt.-%, preferably at least 45 wt.-%, more preferably at least 55 wt.-%, of the total weight of the polymer composition.

[0083] The polymer composition may further comprise various additives, such as fillers, UV- and heat stabilizers, antioxidants, plasticizers, dyes, pigments, matting agents, antistatic agents, impact modifiers, biocides, and processing aids such as lubricants, slip agents, antiblock agents, and denest aids. The total amount of these types of additives is preferably not more than 15 wt.-%, more preferably not more than 10 wt.-%, based on the total weight of the polymer composition. According to one or more embodiments, the thermoplastic composition further comprises at least one inorganic filler F.

[0084] Suitable compounds for use as the inorganic filler F include, for example, sand, granite, calcium carbonate, clay, expanded clay, diatomaceous earth, pumice, mica, kaolin, talc, dolomite, xonotlite, perlite, vermiculite, Wollastonite, barite, magnesium carbonate, calcium hydroxide, calcium aluminates, silica, fumed silica, fused silica, aerogels, glass beads, hollow glass spheres, ceramic spheres, bauxite, comminuted concrete, and zeolites.

[0085] The at least one inorganic filler F is preferably present in the thermoplastic composition in the form of finely divided particles. The term “finely divided particles” refers here to particles, whose median particle size dso does not exceed 150 pm, preferably 100 pm, more preferably 50 pm. The term “median particle size dso“ refers in the present disclosure to a particle size below which 50% of all particles by volume are smaller than the dso value. The particle size distribution can be determined by sieve analysis according to the method as described in ASTM C136 / C136M -2014 standard (“Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates).

[0086] In one or more embodiments, the at least one inorganic filler F has a median particle size dso in the range of 0.1 - 50 pm, preferably 0.15 - 35 pm, more preferably 0.25 - 25 pm, even more preferably 0.35 - 15 pm, still more preferably 0.5 - 10 pm.

[0087] In one or more embodiments, the at least one inorganic filler F is present in the polymer composition in an amount of 0.5 - 20 wt.-%, preferably 1 - 15 wt.-%, more preferably 2.5 - 10 wt.-%, based on the total weight of the polymer composition.

[0088] The preferences given above for and the at least one flame retardant FR, the at least one propylene copolymer PCP, the at least one thermoplastic vulcanizate TPV, the at least one thermoplastic polyolefin elastomer TPO, and to the at least one inorganic filler F apply equally apply equally to all subjects of the present invention unless otherwise stated.

[0089] Another subject of the present invention is a sealing element comprising a waterproof layer obtained by using the polymer composition of the present invention. Especially, the waterproof layer comprises or is composed of the polymer composition of the present invention.

[0090] The term “layer” refers in the present disclosure generally to a sheet-like element having first and second major surfaces, i.e., top and bottom surfaces, a width defined between longitudinally extending edges, and a thickness defined between the first and second major surfaces.

[0091] In one or more embodiments, the waterproof layer comprises at least 50 wt.-%, preferably at least 75 wt.-%, more preferably at least 85 wt.-%, even more preferably at least 95 wt.- % of the of the polymer composition of the present invention.

[0092] In one or more embodiments, the waterproof layer is composed of the polymer composition of the present invention.

[0093] Preferably, the waterproof layer of the sealing element has a thickness of not more than 10 mm, preferably not more than 7.5 mm, more preferably not more than 5 mm, even more preferably not more than 3.5 mm. In one or more embodiments, the waterproof layer has a thickness of 0.1 - 5 mm, preferably 0.1 - 3.5 mm, more preferably 0.5 - 3 mm, even more preferably 0.75 - 2.5 mm. The thickness of layer can be determined by using the measurement method as defined in EN 1849-2:2010-04 standard.

[0094] There are no strict limitations for the width and length of the waterproof layer, and these depend on the intended use of the sealing element. For example, the sealing element can be provided in form of a narrow strip, wherein the waterproof layer has a width, for example, in the range of 25 - 500 mm, such as 50 - 400 mm, particularly 75 - 350 mm. The term “width” and “length” refer to the two perpendicular dimensions measured in the horizontal plane of the first and second major surfaces of a sheet-like element. Generally, the “width” of a sheet like element is the smaller of the horizontal dimensions of a sheetlike element. Consequently, the “width” of the waterproof layer refers to the minor dimension measured in the horizontal plane of the waterproof layer in a direction perpendicular to the length of the waterproof layer. The sealing device can also be provided in form of a broad sheet, particularly a membrane, wherein the waterproof layer has a width of, for example, in the range of 0.75 - 5 m, such as 0.85 - 3.5 m, particularly 1 - 3 m. Such sealing element are typically delivered to a construction site in form of a roll, transferred to the place of installation, and adhered to the substrate to be waterproofed.

[0095] In one or more embodiments, the sealing element is a membrane, preferably a roofing membrane.

[0096] The sealing element may further comprise one or more reinforcing layers. A reinforcing layer may be fully embedded into the waterproof layer or directly or indirectly adhered to one of the major surfaces of the waterproof layer. The expression “fully embedded” is understood to mean that the reinforcing layer is fully covered by the matrix of the waterproof layer. The expression “directly adhered” is understood to mean that no further layer or substance is present between the layers and that the opposing surfaces of the layers are directly adhered to each other. At the transition area between the two layers, the materials of the layers can also be present mixed with each other. The reinforcing layer and the waterproof layer can be indirectly adhered to each other, for example, via a connecting layer, such as a layer of adhesive.

[0097] The type of the reinforcing layer, if used, is not particularly restricted. For example, the reinforcing layers commonly used for improving the dimensional stability of roofing membranes can be used. Preferred reinforcing layers include non-woven fabrics, woven fabrics, and laid scrims, and combinations thereof.

[0098] The term “non-woven fabric” designates in the present disclosure materials composed of fibers, which are bonded together by using chemical, mechanical, or thermal bonding means, and which are neither woven nor knitted. Non-woven fabrics can be produced, for example, by using a carding or needle punching process, in which the fibers are mechanically entangled to obtain the nonwoven fabric. In chemical bonding, chemical binders such as adhesive materials are used to hold the fibers together in a non-woven fabric.

[0099] The term “laid scrim” refers in the present disclosure to web-like non-woven products composed of at least two sets of parallel yarns (also designated as weft and warp yarns), which lay on top of each other and are chemically bonded to each other. The yarns of a non-woven scrim are typically arranged with an angle of 60 - 120°, such as 90 ± 5°, towards each other thereby forming interstices, wherein the interstices occupy more than 60% of the entire surface area of the laid scrim. Typical materials for laid scrims include metal fibers, inorganic fibers, in particular glass fibers, and synthetic organic fibers, in particular polyester, polypropylene, polyethylene, and polyethylene terephthalate (PET).

[0100] According to one or more embodiments, the sealing element comprises a reinforcing layer composed of synthetic organic fibers, preferably selected from the group consisting of polyester fibers, polypropylene fibers, polyethylene fibers, nylon fibers, and polyamide fibers and / or a reinforcing layer composed of inorganic fibers, preferably selected from the group consisting of glass fibers, aramid fibers, wollastonite fibers, and carbon fibers, more preferably glass fibers.

[0101] In one or more embodiments, the reinforcing layer has been thermally laminated to one of the major surfaces of the waterproof layer in a manner that gives direct bonding between the reinforcing layer and the waterproof layer. The term “thermal lamination” refers to a process, in which the layers are bonded to each by the application of thermal energy. In particular, the term “thermal lamination” refers to a process comprising partially melting at least one of the layers upon application of thermal energy followed by a cooling step, which results in formation of a physical bond between the layers without using an adhesive.

[0102] In one or more further embodiments, the reinforcing layer is fully embedded into the waterproof layer.

[0103] According to one or more embodiments, the sealing element comprises a further waterproof layer, preferably obtained by using the polymer composition of the present invention. Preferably, the further waterproof layer comprises or is composed of the polymer composition of the present invention.

[0104] Preferably, the further waterproof layer has a thickness of not more than 10 mm, preferably not more than 7.5 mm, more preferably not more than 5 mm, even more preferably not more than 3.5 mm. According to one or more embodiments, the further waterproof layer has a thickness of 0.1 - 5 mm, preferably 0.1 - 3.5 mm, more preferably 0.5 - 3 mm, even more preferably 0.75 - 2.5 mm.

[0105] Another aspect of the present invention is a method for producing a sealing element according to the present invention, the method comprising melt-processing a composition comprising the constituents of the polymer composition as described above and meltshaping of the melt-processed composition into a form of a shaped article.

[0106] The term “melt-processing” refers in the present disclosure to a process, in which at least one molten polymeric component is intimately mixed with at least one other component, which may be another molten polymeric component or a solid component, such as a filler, until a melt blend, i.e. a substantially homogeneously mixed mixture of the polymeric component(s) and the other constituents is obtained.

[0107] The melt processing of the composition can be conducted as a batch process using any conventional mixer, such as a Brabender, Banbury, or roll mixer or as continuous process using a continuous type of mixer, preferably an extruder, such as a single screw or a twin- screw extruder or a planetary roller extruder.

[0108] The melt-shaping step can be conducted by using various techniques known to those of skill in the art, such as, extruding, co-extruding, molding, thermoforming, film blowing, casting, or calendaring.

[0109] In one or more embodiments, the method for producing a sealing element comprises steps of: i) Melt-processing a composition comprising the constituents of the polymer composition in an extruder to provide a melt-blend and ii) Extruding said melt-blend through an extruder die.

[0110] Any conventional extruder may be used for conducting step i) of the method, such as, a ram extruder, single screw extruder, a twin-screw extruder, or a planetary roller extruder.

[0111] Preferably, the extruder is a screw extruder, more preferably a twin-screw extruder comprising a barrel and a screw unit contained in the barrel. The screw unit of a conventional screw extruder is typically considered to comprise feed, transition, and metering sections. In the feed section the thermoplastic composition enters the channels of the rotating screw and is conveyed towards the transition section, in which the composition is compressed and melted. The composition should be fully melted when it leaves the transition section. The function of the metering section is to homogenize the melted composition and to allow it to be metered or pumped out at constant rate. The extruder die used for conducting step ii) of the method is preferably a flat die, consisting of manifold, approach, and lip regions.

[0112] The extruder barrel comprises a feed port through which the material to be extruded is fed to the extruder and an outlet port through which the material leaves the barrel. The outlet port is coupled with the die via a gate or adapter piece. A mixing device may be interposed between the barrel and the die. The feed port is generally connected with a hopper to which the material to be extruded is added. It is preferred that a screen pack and a breaker plate are positioned at the end of the barrel to avoid plugging in the nozzles. The extruder further comprises heating elements, cooling elements, temperature sensors and temperature control elements to provide temperature-controlled zones along the barrel, also known as barrel zones. The extruder may comprise, for example, from 3 to 8 barrel zones, preferably at least 5 barrel zones, by the use of which a temperature profile can be realized in the barrel.

[0113] The extrusion process may be conducted by using different temperature profiles, such as an increasing temperature profile where the temperature increases downstream the barrel, a decreasing temperature profile where the temperature decreases downstream the barrel, or a humped temperature profile where the temperature increases from the feed port toward a certain set point, for example toward the middle of the barrel.

[0114] The maximum temperature of the composition during melt processing in the screw section of the extruder, i.e., the temperature in at the end of the screw section, is preferably not less than 150 °C, more preferably not less than 160 °C, most preferably not less than 170 °C. The maximum temperature of the composition during melt processing in the screw section of the extruder can be in the range of 150 - 250 °C, for example 160 - 225 °C, such as 180 - 215 °C. The constituents of the thermoplastic composition may be fed to the extruder as individual streams, as a pre-mix, dry blend, or as a master batch.

[0115] The at least one propylene copolymer PCP, the at least one thermoplastic vulcanizate TPV, and the at least one thermoplastic polyolefin elastomer TPO may be fed into the extruder through the feed port and at least a portion of the at least one flame retardant FR and additives, such as fillers, UV-stabilizers and UV-absorbers, if used, may fed into the extruder through another port located downstream from the feed port. The term “downstream” designates in the present document the direction to the outlet port. Alternatively, at least a portion of the flame retardant FR and the additives can be mixed with the polymer components to obtain a premix, which is then fed into the extruder through the feed port. The premixing can be carried out using a blending apparatus, which are known to a person skilled in the art. Furthermore, the polymer components can be processed in a compounding extruder to pellets or granules, which are dry-blended with at least a portion of the additives and the resulting dry-blend is then fed into extruder though the feed port.

[0116] Still another subject of the present invention is a method for waterproofing a substrate, the method comprising steps of:

[0117] I) Applying two or more sealing elements of the present invention on the surface of the substrate to be waterproofed,

[0118] II) Overlapping adjacent sealing elements along the length and / or width of the sealing elements, and

[0119] III) Bonding the opposing surfaces of the overlapped portions to each other by using adhesive or heat-welding means.

[0120] In one or more embodiments, the substrate to be waterproofed is a roofing substrate, preferably selected from the group consisting of an insulation board, a cover board, and an existing roofing membrane.

[0121] In one or more embodiments, the adjacent sealing elements are overlapped along the length and / or width, i.e., along the long and / or short edges, of the sealing elements. Particularly, the adjacent sealing elements can be overlapped at least 25 mm, preferably at least 50 mm, more preferably at least 75 mm, even more preferably at least 100 mm, along the length and / or width of the sealing elements.

[0122] In one or more embodiments, step III) of the method is conducted by heating the overlapped portions of the sealing elements above the melting temperature of the waterproof layer and bonding the opposing surfaces of the overlapped portions to each other under sufficient pressure to provide acceptable seam strength without use of adhesive.

[0123] The step heating the overlapped portions of the sealing elements can be conducted manually, for example by using a hot air tool, or by using an automatic welding device, such as an automatic hot-air welding device, for example Sarnamatic® 661 welding device. The temperature to which the overlapped portions of the adjacent sealing elements are heated depends on the embodiment of the sealing elements and also whether the welding step is conducted manually or by using an automatic welding device. Preferably, the overlapped portions of the adjoining sealing devices are heated to a temperature of at or above 150 °C, more preferably of at or above 200 °C.

[0124] Examples

[0125] The materials shown in Table 1 were used for preparing the membrane sheets.

[0126] Table 1

[0127] The inventive and reference membrane sheets were prepared according to the procedure as described below and tested for their mechanical properties.

[0128] Preparation of membrane sheets

[0129] The membrane sheets were produced using a laboratory scale extrusion-calendering apparatus consisting of a twin-screw extruder (Berstorff GmbH), a flat die and set of water- cooled calender rolls.

[0130] The polymer components (PCPs, TPV, TPO) and the additive package were fed to an extruder hopper. The polymer blend and the additives were melt-processed in the first of the four zones of the extruder. The pigm ent / filler and the flame retardant (FR) were added to the partially melt-processed blend at beginning of the second zone of the extruder. The melt-processed blend was then extruded through an extruder flat die into single ply sheets having a thickness of approximately 0.75 mm. The temperature in the extruder varied between 195 and 200 °C and the melt pressure was 6 - 7 MPa.

[0131] The inventive and reference membranes were multi-layer membranes comprising top and back waterproof layers and having a total thickness of 1 .5 mm. The inventive membrane Ex-2 was equipped with a non-woven polyester fabric as a reinforcement layer between the top and bottom layers.

[0132] The top layer of the inventive membranes Ex-1 and Ex-2 had the following composition: - 34 pbw (parts by weight) of the propylene copolymers (PCP),

[0133] - 24 pbw of the thermoplastic polyolefin elastomer (TPO),

[0134] - 6 pbw of the thermoplastic vulcanizate (TPV),

[0135] - 30 pbw of the flame retardant (Si-ATH),

[0136] - 5 pbw of TIO2 (pigment), and

[0137] - 1.1 pbw of the additive package.

[0138] The back layer of the inventive membranes Ex-1 and Ex-2 had the following composition:

[0139] - 34 pbw (parts by weight) of the propylene copolymers (PCP),

[0140] - 24 pbw of the thermoplastic polyolefin elastomer (TPO),

[0141] - 6 pbw of the thermoplastic vulcanizate (TPV),

[0142] - 30 pbw of the flame retardant (Si-ATH),

[0143] - 4.5 pbw of CaCOs (filler), and

[0144] - 0.2 pbw of the additive package.

[0145] The top and bottom layers of membranes Ex-3 and Ex-4 had the same compositions as the respective layers of the membranes Ex-1 and Ex-2 except that the top and bottom layers of Ex-3 contained, instead of the silane coated ATH, uncoated MDH as the flame retardant whereas the top and bottom layers of Ex-4 contained coated MDH as the as the flame retardant.

[0146] Commercially available membrane Sarnafil® TS 77-15 (from Sika AG) was used as a reference membrane. Sarnafil® TS 77-15 is a multi-layer reinforced polyolefin-based roofing membrane having a total thickness of 1 .5 mm.

[0147] Flame resistance

[0148] Flame resistance properties of the membranes was conducted according to EN 11925-2 standard. According to the test results, inventive membrane Ex-2 had a fire classification of E according to EN 13501-1 standard. Tensile stress and elongation at break

[0149] The tensile stress and elongation at break were measured for samples cut from the tested membranes in machine and cross machine direction. The measurements were conducted according to GB27789-2011 standard at a temperature of 23°C using a cross head speed of 250±50 mm / min. The values for tensile stress and elongation at break obtained with the tested membranes are presented in Tables 2 and 3.

[0150] Cold bending

[0151] The cold bending test was performed using a method according to GB27789 standard.

[0152] Test specimens having dimensions of 25 x 100 mm were cut from the tested material. The samples were folded in half and secured with staples. Folding of the samples was conducted in machine direction (MD) or in cross machine direction (CMD) and such that the outer surface of the top layer was facing outward and that of the back layer was facing outward.

[0153] The folded samples were conditioned at a temperature of -40 °C for one hour. An external pressure was then applied on the samples at the respective temperature and the sample was visually observed for any damages. If any damages, such as cracks, were found, the tested specimen did not pass the cold bending test.

[0154] Table 2

[0155] MD = machine direction, CMD = cross machine direction Table 3

[0156] MD = machine direction, CMD = cross machine direction Table 4

Claims

Claims1 . A polymer composition comprising: a) At least one propylene copolymer PCP, b) At least one thermoplastic vulcanizate TPV, c) At least one thermoplastic polyolefin elastomer TPO different from the propylene copolymer PCP, and d) At least one flame retardant FR selected from magnesium hydroxide and aluminum trihydroxide.

2. The polymer composition according to claim 1 , wherein the at least one flame retardant FR is present in the polymer composition in an amount of 5 - 50 wt.-%, preferably 15 - 45 wt.-%, based on the total weight of the polymer composition.

3. The polymer composition according to claim 1 or 2, wherein the at least one flame retardant FR is selected from surface-coated magnesium hydroxide and surface-coated aluminum trihydroxide, preferably comprising a surface coating of silanes.

4. The polymer composition according to any one of previous claims, wherein the at least one propylene copolymer PCP is present in the polymer composition in an amount of 10 - 65 wt.-%, preferably 15 - 50 wt.-%, based on the total weight of the polymer composition.

5. The polymer composition according to any one of previous claims, wherein the at least one propylene copolymer PCP has a flexural modulus at 23°C determined according to ISO 178:2019 standard of not more than 100 MPa, preferably not more than 75 MPa and / or a xylene cold soluble content determined according to ISO 16152:2005 standard of at least 70 wt.-%, more preferably at least 80 wt.-% and / or a softening point determined by Ring and Ball measurement conducted according to ISO 4625-1 :2020 standard of not more than 95 °C, preferably not more than 75 °C.

6. The polymer composition according to any one of previous claims, wherein the at least one propylene copolymer PCP is a propylene-ethylene copolymer, preferably a random propylene-ethylene copolymer.

7. The polymer composition according to any one of previous claims, wherein the at least one thermoplastic vulcanizate TPV is present in the polymer composition in an amount of 0.5 - 15 wt.-%, preferably 2.5 - 12.5 wt.-%, based on the total weight of the polymer composition.

8. The polymer composition according to any one of previous claims, wherein the at least one thermoplastic vulcanizate TPV comprises a blend of a thermoplastic resin and particles of a at least partially vulcanized rubber dispersed throughout a matrix of the thermoplastic resin.

9. The polymer composition according to any one of previous claims, wherein the at least one thermoplastic polyolefin elastomer TPO is present in the polymer composition in an amount of 5 - 50 wt.-%, preferably 10 - 40 wt.-%, based on the total weight of the polymer composition.

10. The polymer composition according to any one of previous claims, wherein the at least one thermoplastic polyolefin elastomer TPO has a melting temperature determined by DSC according to ISO 11357-3:2018 standard using a heating rate of 2°C / min of at least 100 °C, preferably at least 110 °C.11 . The polymer composition according to any one of previous claims, wherein the at least one thermoplastic polyolefin elastomer TPO is a heterophasic propylene copolymer.

12. A sealing element comprising a waterproof layer obtained by using the polymer composition according to any one of previous claims.

13. The sealing element according to claim 12, wherein the sealing element is a membrane, preferably a roofing membrane.

14. A method for producing a sealing element according to claim 12 or 13, the method comprising melt-processing a composition comprising the constituentsof the polymer composition according to any one of claims 1-11 and meltshaping the melt-processed composition into a form of a shaped article.

15. A method for waterproofing a substrate comprising steps of:I) Applying two or more sealing elements according to any one of claims 12 or 13 on the surface of the substrate to be waterproofed,II) Overlapping adjacent sealing elements along the length and / or width of the sealing elements, and III) Bonding the opposing surfaces of the overlapped portions to each other by using adhesive or heat-welding means.

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