A halogen-free flame-retardant polymer composition and use thereof

Abstract

The invention is directed to a halogen-free flame-retardant polymer composition comprising: a) An organic polymer component comprising: a1) At least one thermoplastic polymer TP and / or a2) At least one elastomer E, and b) A flame-retardant system comprising: b1) At least one first nitrogen-containing organophosphorus compound and optionally at least one metal borate, b2) At least one organometallic salt, and b3) At least one second nitrogen-containing organophosphorus compound. The invention is also directed to a sealing element comprising a shaped article obtained by using the halogen-free flame-retardant polymer composition.

Description

[0001] A HALOGEN-FREE FLAME-RETARDANT POLYMER COMPOSITION AND USE THEREOF

[0002] Technical field

[0003] The invention relates to polymer compositions comprising a halogen-free flame-retardant system. The invention also relates to shaped articles obtained using such polymer compositions.

[0004] Background of the invention

[0005] Polymer materials are widely used in the construction materials. Typical applications of polymers in construction industry include areas such as flooring, windows, cladding, rainwater, pipes, membranes, seals, glazing, insulation, and signage. Membranes are used to protect underground and above ground constructions, such as basements, tunnels, facades, and roofs against penetration of water.

[0006] 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. Roofing membranes are commonly used for waterproofing of flat and low-sloped roof structures. Waterproofing tapes comprising a polymeric carrier layer are also used for sealing and waterproofing of construction gaps in building facades, for example gaps between a building structure and window or curtain wall components.

[0007] Commonly used plastic materials for membranes and tapes include thermoplastics, such as plasticized polyvinylchloride (p-PVC), thermoplastic polyolefin elastomers (TPO, TPE- O), and elastomers such as ethylene-propylene diene monomer (EPDM) rubber.

[0008] Thermoplastic polyolefin elastomers are heterophasic polymer systems comprising a high crystallinity base polyolefin and a low-crystallinity or amorphous polyolefin modifier. 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”. The required classification depends on the type of the product. For example, polymeric sheets used in the external fagade, such as breather membranes and vapor control layers, have a different fire rating requirement than roofing membranes used for covering a flat roof structure. In Europe, the requirements for fire safety in buildings have been increased after the Grenfell Tower disaster in 2017.

[0010] European fire standards for flat roofs are defined in EN 13501-5 standard. The standard defines four tests for roof covering systems and “European Class ratings”, which are given to a roof system based on the results from testing. The European Class ratings indicated the external fire performance of roofs, i.e., the response of the roof to fire from outside of the building. Another standard EN 13501-1 sets the guidelines for testing fire performance of individual components of a building. This standard is concerned with behavior of roofs when subjected to effects of fire from the underside, i.e., from within the building.

[0011] The EN 13501-1 standard assigns construction materials a fire classification based on their capacity to spread fire. Classifications range from A1 , which is given to materials that offer no contribution to fire, through to F for materials with no tested performance. There are different classifications for surface covering materials, insulation materials, floor coverings, pipe insulation materials, and cables. In addition, the system contains additional classes for smoke development (s1-s3) and for burning droplets (d0-d2). For example, in UK the breather membranes installed behind the cladding and vapor barriers installed on the inside of the fagade are required by law to have a minimum Euroclass rating of B, s3- dO. This means that they can have only a limited contribution to fire, and although they are allowed to produce any amount of smoke, they should not produce any burning droplets. The European Class ratings according to EN 13501-5 are reported as Broof(tx) to Froof(tx), where the suffix (tx) indicates which test is used, for example, with Broof(t4) indicating the highest performance while using the t4 test. In this context, test 1 is conducted with burning brands, test 2 with burning brands and wind, tests 3 and 4 with burning brands, wind, and supplementary radiant heat. Although there has been a lot of effort to harmonize the use of the classification of roofs / roof coverings exposed to an external fire, there are also significant differences in the requirements between European countries. For example, Test t1 is used in Germany, test t2 in Scandinavia, test t3 in France, and test t4 in the UK (and in Republic of Ireland).

[0012] Furthermore, the fire rating classification for roof systems does not depend only on the product itself but also on its application. For example, a fire classification for a roofing membrane depends on whether the roofing membrane is used for providing an insulated roof system or a non-insulated roof system. Therefore, some roofing membranes are Broof(t1) classified for use with polyisocyanurate (cover) boards but when used with expanded polystyrene (insulation) boards.

[0013] Flame retardant additives 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 alumina trihydrate (ATH), precipitated aluminum hydroxides, and magnesium hydroxide, and brominated flame retardants (BRF). Commonly used halogen-free flame retardants for thermoplastic polymers include ammonium polyphosphate and 1 ,3,5-triazine compounds, such as melamine and melamine salts and adducts, and oligomeric and polymeric 1 ,3,5- triazine compounds. 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.

[0014] The disadvantage of halogen-free flame retardants is their inferior efficiency compared to other flame retardants. Consequently, the amount of flame retardants added to a polymer blend to achieve a desired fire rating is very high, which typically has a significant adverse effect on their mechanical properties. For example, single-ply polyolefin-based roofing membranes typically contain up to 60 wt.-% of ATH to comply with the fire rating requirements. Despite the use of high amounts of halogen-free flame retardants, the currently available roofing membranes do not fulfill the requirements for highest fire rating.

[0015] There thus remains a need for a novel type of halogen-free polymer composition having improved flame retardancy properties and excellent mechanical properties. Such halogen- free polymer compositions are especially suitable for use in the construction industry, for example, for providing sealing elements, such as membranes, for above and below ground applications.

[0016] Summary of the invention

[0017] The object of the present invention is to provide a halogen-free flame-retardant polymer composition having improved flame retardancy properties. Such polymer compositions are especially suitable for providing shaped articles, particularly sealing elements for above and below ground applications.

[0018] It was surprisingly found out that these objectives can be achieved with the composition according to claim 1 .

[0019] Specifically, according to the invention, a halogen-free flame-retardant polymer composition is proposed, the composition comprising: a) An organic polymer component comprising: a1) At least one thermoplastic polymer TP and / or a2) At least one elastomer E, and b) A flame-retardant system comprising: b1) At least one first nitrogen-containing organophosphorus compound and optionally at least one metal borate, b2) At least one organometallic salt, and b3) At least one second nitrogen-containing organophosphorus compound.

[0020] As it turned out, the inventive polymer composition exhibits improved flame retardancy properties, whereas the presence of the flame-retardant system in the polymer blend does not cause a significant negative effect on the mechanical properties of the polymer blend. It was also surprisingly found out that the addition of the flame-retardant system does not significantly increase the water absorption of the polymer blend.

[0021] Without wishing to be bound by theory, it is believed that the use of the three different types of flame retarding compounds provides an optimal and synergistic combination of catalyzing, reinforcing charring, and blowing agents, which enables providing the polymer blend with superior flame retardancy properties.

[0022] Further aspects of the invention are described below and are subject of the further independent claims. Particularly preferred embodiments are outlined throughout the description and in the dependent claims.

[0023] Detailed description of the invention

[0024] A first aspect of the present invention is directed to a halogen-free flame-retardant polymer composition comprising: a) An organic polymer component comprising: a1) At least one thermoplastic polymer TP and / or a2) At least one elastomer E, and b) A flame-retardant system comprising: b1) At least one first nitrogen-containing organophosphorus compound and optionally at least one metal borate, b2) At least one organometallic salt, and b3) At least one second nitrogen-containing organophosphorus compound.

[0025] 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 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). 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 %.

[0026] The term “elastomer” designates a polymer or a polymer blend, which can cover 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.”

[0027] 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 standard.

[0029] The “amount or content of at least one component X” in a composition, for example “the amount of the at least one thermoplastic polymer TP” refers to the sum of the individual amounts of all thermoplastic polymers TP contained in the composition. Furthermore, in case the composition comprises 20 wt.-% of at least one thermoplastic polymer TP, the sum of the amounts of all thermoplastic polymers contained in the composition equals 20 wt.-%. The halogen-free polymer composition comprises as the first compulsory constituent an organic polymer component a).

[0030] The term “organic polymer” encompasses in the present disclosure a collective of macromolecules that are chemically homogeneous but differ in relation to degree of polymerization, molar mass, and chain length, which has been prepared by a poly reaction (polymerization, polyaddition, polycondensation) and has a majority of carbon atoms in the polymer backbone, and reaction products of such a collective of macromolecules. Polymers having a polyorganosiloxane backbone that are commonly referred to as “silicones” or “siloxane polymers” are not organic polymers in the context of the present disclosure.

[0031] The first component of the flame-retardant system b) comprises at least one nitrogencontaining organophosphorus compound and optionally at least one metal borate.

[0032] The term “organophosphorus compound” refers in the present disclosure to organic compounds containing phosphorus, whereas “nitrogen-containing” implies that the organophosphorus compound contains at least one nitrogen atom.

[0033] According to one or more embodiments, the at least one first nitrogen-containing organophosphorus compound is selected from piperazine pyrophosphate, piperazine orthophosphate, piperazine polyphosphate, piperazine bis(dimethyl) phosphoramidate, piperazine DOPO, and EDA-DOPO, preferably from piperazine pyrophosphate, piperazine bis(dimethyl) phosphoramidate, piperazine DOPO, and EDA-DOPO, more preferably piperazine pyrophosphate.

[0034] The term “DOPO” refers here to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and “EDA-DOPO” to 6,6'-(ethane-1 ,2-diylbis(azanediyl))bis(6H- dibenzo[c,e][1 ,2]oxaphosphinine-6-oxide. Suitable methods for preparing EDA-DOPO are disclosed, for example, in EP 3 421 479 A1 .

[0035] Suitable piperazine group containing organophosphorus compounds are commercially available, for example, under the trade name of Mflam® (from Hangzhou Mei Wang Chemical Co., Ltd) and Aflammit® TLP, such as Aflammit® TLP 1715 (from Thor GmbH). The at least one metal borate can be present in the flame-retardant system in addition to the at least one first nitrogen-containing organophosphorus compound. Suitable metal borates include, for example, alkali metal borates, alkaline earth metal borates, and zinc borate.

[0036] According to one or more embodiments, the at least one metal borate is selected from zinc borate and calcium borate.

[0037] Zinc borates are a group of compounds based on Zn:B:O in their various molar ratios. Both hydrated and anhydrous zinc borates are suitable for use as the at least one metal borate.

[0038] According to one or more embodiments, the at least one metal borate is zinc borate, preferably having a median particle size dso of not more than 20 pm, more preferably not more than 10 pm, such as in the range of 1 - 10 pm. A particle size distribution can be measured by laser diffraction according to the method as described in standard ISO 13320:2009 using a wet or dry dispersion method and for example, a Mastersizer 2000 device (trademark of Malvern Instruments Ltd, GB).

[0039] The second component of the flame-retardant system b) comprises at least one organometallic salt.

[0040] Suitable organometallic salts for use in the flame-retardant system include, particularly, aluminum salts, such as aluminum diethyl phosphinate, aluminum salts of 1- hydroxydihydrophosphole oxide and 1 -hydroxyphospholane oxide, and aluminum diisobutyl phosphinate. Suitable aluminum salts are commercially available, for example, under the trade name of Exolit® OP, such as Exolit® OP 1230 (from Clariant plastics & Coatings GmbH).

[0041] The third component of the flame-retardant system b) comprises at least one second nitrogen-containing organophosphorus compound different from the at least one first nitrogen-containing organophosphorus compound. Suitable compounds for use as the second nitrogen-containing organophosphorus compound include, for example, phosphoric acid triazine salts, especially phosphoric acid melamine salts, for example, melamine phosphate, melamine pyrophosphate, and melamine polyphosphate. These are commercially available, for example, under the trade name of Aflammit® PMN 200 (from Thor GmbH) and under the trade name of Melapur®, such as Melapur® 200 and Melapur® MC (from BASF).

[0042] According to one or more embodiments, the at least organometallic salt is an organic phosphinate metal salt, preferably an organic phosphinate aluminum salt and / or the at least one second nitrogen-containing organophosphorus compound is a phosphoric acid melamine salt, preferably selected from melamine polyphosphate, melamine phosphate, and melamine pyrophosphate.

[0043] According to one or more preferred embodiments, the at least one organometallic salt is aluminium diethyl phosphinate and / or the at least one second nitrogen-containing organophosphorus compound is melamine polyphosphate.

[0044] The flame-retardant system b) preferably makes up at least 5 wt.-%, more preferably at least 15 wt.-%, even more preferably at least 25 wt.-%, still more preferably at least 35 wt.- %, of the total weight of the halogen-free polymer composition. Preferably, the flameretardant system b) makes up not more than 95 wt.-%, more preferably not more than 85 wt.-%, even more preferably not more than 80 wt.-%, still more preferably not more than 75 wt.-%, of the total weight of the halogen-free polymer composition.

[0045] According to one or more embodiments, the flame-retardant system b) makes up 35 - 75 wt.-%, preferably 40 - 70 wt.-%, more preferably 45 - 65 wt.-%, of the total weight of the halogen-free polymer composition.

[0046] According to one or more embodiments, the flame-retardant system b) comprises: b1) 0.5 - 25 wt.-%, preferably 1 .5 - 20 wt.-%, more preferably 1 .5 - 15 wt.-%, even more preferably 2.5 - 10 wt.-%, of the at least one first nitrogen-containing organophosphorus compound or of a mixture of the at least one metal borate and the at least one first nitrogen-containing organophosphorus compound, b2) 5 - 55 wt.-%, preferably 10 - 50 wt.-%, more preferably 20 - 50 wt.-%, even more preferably 25 - 50 wt.-%, of the at least one organometallic salt, and b3) 5 - 55 wt.-%, preferably 10 - 50 wt.-%, more preferably 20 - 50 wt.-%, even more preferably 25 - 50 wt.-%, of the at least one second nitrogen-containing organophosphorus compound, all proportions being based on the total weight of the flameretardant system b).

[0047] According to one or more further embodiments, the flame-retardant system b) comprises: b1) 0.5 - 15 wt.-%, preferably 1.5 - 12.5 wt.-%, more preferably 1 .5 - 10 wt.-%, even more preferably 2.5 - 10 wt.-%, of the at least one first nitrogen-containing organophosphorus compound or of a mixture of the at least one metal borate and the at least one first nitrogen-containing organophosphorus compound, b2) 5 - 55 wt.-%, preferably 10 - 50 wt.-%, more preferably 20 - 50 wt.-%, even more preferably 25 - 50 wt.-%, of the at least one organometallic salt, and b3) 5 - 55 wt.-%, preferably 10 - 50 wt.-%, more preferably 20 - 50 wt.-%, even more preferably 25 - 50 wt.-%, of the at least one second nitrogen-containing organophosphorus compound, all proportions being based on the total weight of the flameretardant system b).

[0048] It was surprisingly found out that polymer compositions comprising the components b1) to b3) in the above cited ranges show highly improved flame retardancy properties.

[0049] It may also be preferred that the weight ratio of the at least one organometallic salt to the at least one second nitrogen-containing organophosphorus compound in the halogen-free flame-retardant polymer composition is not more than 3:1 , more preferably not more than 2:1 and at least 1 :3, more preferably at least 1 :2.

[0050] According to one or more embodiments, the weight ratio of the at least one organometallic salt to the at least one second nitrogen-containing organophosphorus compound in the halogen-free flame-retardant polymer composition is in the range of from 1 .5:1 to 1 :1.5, preferably from 1.3:1 to 1 :1.3, more preferably from 1.2:1 to 1 :1.2.

[0051] It has also been found out that the flame retardancy properties of the polymer composition may further be improved if the flame-retardant system b) comprises an additional char source / blowing agent, such as expandable graphite or cellulose containing material, especially wood particles.

[0052] According to one or more embodiments, the flame-retardant system b) further comprises: b4) Expandable graphite and / or wood particles.

[0053] The term "expandable graphite" refers in the present disclosure to an intercalating graphite compound obtained by treatment of crystalline graphite with intercalants, such as nitric acid, sulfuric acid, and potassium permanganate, which are incorporated between the parallel layers of carbon atoms. When a thermally expandable graphite is exposed to heat, the intercalant is transformed from a liquid or a solid phase to gas phase. The adjacent graphite layers are forced apart by the released gases, which results in expansion of the graphite material.

[0054] Preferably, the expandable graphite has an initiation expansion temperature determined by using the method as described below of at least 150 °C, more preferably at least 175 °C, even more preferably at least 185 °C. According to one or more embodiments, the thermally expandable graphite has an initiation expansion temperature determined by using the method as described below in the range of 165- 300 °C, preferably 175 - 275 °C, more preferably 185 - 250 °C.

[0055] Measurement of initiation expansion temperature

[0056] A sample of thermally expandable graphite having a volume of 2 cm3is placed in an oven in a test tube. The temperature of the oven is increased at a constant rate until the volume of the sample has increased to a value corresponding to 1 .1 times the initial volume of the sample. The temperature at which the 10 % increase in volume is reached is recorded as the “initiation expansion temperature”.

[0057] The term “wood particle” refers in the present disclosure to particles composed of wood fibers. The length dimension of a wood particle is typically orientated parallel to the grain structure of the wood particle, i.e., parallel to the orientation of the long axis of the dominant fibers in the wood particle. Suitable wood particles for use in the flame-retardant system b) include all types of soft wood and hard wood particles.

[0058] According to one or more embodiments, the wood particles have a Doo particle length of not more than 10 mm, preferably not more than 5 mm, more preferably not more than 2.5 mm, even more preferably not more than 1 .5 mm and / or at least 100 pm, preferably at least 250 pm, more preferably at least 500 pm. The term D90 particle length refers in the present disclosure to a particle length below which 90 % of all particles by volume have a smaller length than the D90 value.

[0059] The “length of a particle” refers in the present disclosure to the maximum Feret diameter (XFe.max), i.e. the longest Feret diameter out of the measured set of Feret diameters. The term “Feret diameter” refers in the present disclosure to the distance between two tangents on opposite sides of the particle, parallel to some fixed direction and perpendicular to the measurement direction. The length the particle can be determined using any suitable measurement technique, preferably by using dynamic image analysis method conducted according to ISO 13322-2:2006 standard. The dimensions of particles can be measured with a dry dispersion method, where the particles are dispersed in air, preferably by using air pressure dispersion method. The measurements can be conducted using any type of dynamic image analysis apparatus, such as a Camsizer XT device (trademark of Retsch Technology GmbH).

[0060] According to one or more embodiments, the expandable graphite or wood particles or mixture thereof makes up 5 - 45 wt.-%, preferably 10 - 40 wt.-%, more preferably 15 - 40 wt.-%, of the total weight of the flame-retardant system b).

[0061] The flame-retardant polymer composition of the present invention comprises an organic polymer component a) comprising at least one thermoplastic polymer TP and / or at least one elastomer E.

[0062] 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. It goes without saying that the thermoplastic polymer TP is different from the elastomer E. Preferably, the at least one thermoplastic polymer TP is selected from polyolefins, thermoplastic polyurethane (TPU), polyvinylchloride (PVC), and ketone ethylene esters (KEE).

[0063] Term "polyolefin" refers in the present disclosure to homopolymers and copolymers obtained by polymerization of olefin monomers optionally with other types of comonomers. Suitable polyolefins for use as the at least one thermoplastic polymer TP include, for example, propylene-ethylene copolymers, a-olefin copolymers of propylene and one or more C4-C20 a-olefin monomers, ethylene-a-olefin copolymers of ethylene and one or more C3-C20 a-olefin monomers, and ethylene vinyl acetate copolymers.

[0064] Further suitable polyolefins include thermoplastic polyolefin elastomers (TPO-E), particularly heterophasic propylene copolymers. These are 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.

[0065] Thermoplastic polyurethanes (TPU) are polyurethane-based thermoplastic elastomers (TPE) that are linear segmented block copolymers composed of alternating hard and soft segments or domains formed by the reaction of (1) diisocyanates with short-chain diols (so-called chain extenders) and (2) diisocyanates with long-chain diols.

[0066] Suitable thermoplastic polyurethanes are commercially available, for example, under the trade name of Pearlbond®, such as Pearlbond® TPU and Pearlbond® 700-series (all from Lubrizol) and under the trade name of Elastollan® (from BASF).

[0067] Suitable PVC resins for use as the at least one thermoplastic polymer TP include ones having a K-value determined by using the method as described in ISO 1628-2-1998 standard in the range of 50 - 85, preferably 65 - 75. The K-value is a measure of the polymerization grade of the PVC-resin, and it is determined from the viscosity values of the PVC homopolymer as virgin resin, dissolved in cyclohexanone at 30° C.

[0068] Suitable PVC resins are commercially available, for example, under the trade name of Vynova® (from Vynova Group) and Norvinyl® (from INEOS ChlorVinyls Ltd). According to one or more embodiments, the at least one thermoplastic polymer TP comprises at least one propylene copolymer TP1 and / or at least one ethylene copolymer TP2

[0069] Generally, the expression “the at least one component X comprises at least one component XN”, such as “the at least one thermoplastic polymer TP comprises at least one propylene copolymer TP1” is understood to mean in the context of the present disclosure that the polymer composition comprises one or more propylene copolymers as representatives of the at least one thermoplastic polymer TP.

[0070] Preferably, the at least one propylene copolymer TP1 has a propylene content of at least 60 wt.-%, more preferably at least 70 wt.-%, even more preferably at least 75 wt.-%, based on the weight of the propylene copolymer and / or at least one ethylene copolymer TP2 has an ethylene content of at least 50 wt.-%, more preferably at least 55 wt.-%, even more based on the weight of the ethylene copolymer.

[0071] “Monomer / comonomer content of a copolymer” refers to the total amount of monomers / comonomers in the copolymer given in wt.-% or mol-%. The monomer / comonomer content can be determined by IR spectroscopy or by quantitative nuclear-magnetic resonance (NMR) measurements.

[0072] According to one or more embodiments, the at least one propylene copolymer TP1 is a propylene-ethylene copolymer, preferably a propylene-ethylene random copolymer, preferably having an ethylene content of 5 - 20 wt.-%, more preferably 9 - 18 wt.-%, even more preferably 12 - 18 wt.-%, even more preferably 12 - 16 wt.-%, based on the weight of the propylene-ethylene copolymer.

[0073] According to one or more embodiments, the at least one propylene copolymer TP1 has:

[0074] - 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

[0075] - 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 35 g / 10 min, more preferably not more than 25 g / 10 min, even more preferably not more than 20 g / 10 min and / or - 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.

[0076] Particularly suitable propylene-ethylene copolymers for use as the at least one propylene copolymer TP1 include the propylene-ethylene copolymers, which are commonly characterized as “propylene-based elastomers”. These are commercially available, for example, under the trade name of Versify® (from Dow Chemicals) and under the trade name of Vistamaxx® (from Exxon Mobil).

[0077] Suitable polymers for use as the at least one ethylene copolymer TP2 include ethylene-a- olefin copolymers, particularly copolymers of ethylene and one or more C3-C20 a-olefin monomers, preferably one or more of propylene, 1 -butene, 1 -pentene, 1 -hexene, 1- heptene, 1 -octene, 1 -decene, 1 -dodecene, and 1 -hexadodecene.

[0078] Suitable ethylene-a-olefin copolymers include, for example, ethylene-based plastomers, which are commercially available, for example, under the trade name of Affinity®, such as Affinity® EG 8100G, Affinity® EG 8200G, Affinity® SL 8110G, Affinity® KC 8852G, Affinity® VP 8770G, and Affinity® PF 1140G (all from Dow Chemical Company); under the trade name of Exact®, such as Exact® 3024, Exact® 3027, Exact® 3128, Exact® 3131 , Exact® 4049, Exact® 4053, Exact® 5371 , and Exact® 8203 (all from Exxon Mobil); and under the trade name of Queo® (from Borealis AG).

[0079] Other suitable ethylene-a-olefin copolymers include, for example, ethylene-based polyolefin elastomers (POE), which are commercially available, for example, under the trade name of Engage®, such as Engage® 7256, Engage® 7467, Engage® 7447, Engage® 8003, Engage® 8100, Engage® 8480, Engage® 8540, Engage® 8440, Engage® 8450, Engage® 8452, Engage® 8200, and Engage® 8414 (all from Dow Chemical Company).

[0080] Further suitable ethylene-a-olefin copolymers include ethylene-a-olefin block copolymers, such as ethylene-based olefin block copolymers (OBC), which are commercially available, for example, under the trade name of Infuse®, such as Infuse® 9100, Infuse® 9107, Infuse® 9500, Infuse® 9507, and Infuse® 9530 (all from Dow Chemical Company).

[0081] According to one or more embodiments, the least one ethylene copolymer TP2 has: - a flexural modulus at 23°C determined according to ISO 178:2019 standard of not more than 150 MPa, preferably not more than 125 MPa, more preferably not more than 100 MPa, even more preferably not more than 85 MPa and / or

[0082] - a melt flow rate (190°C / 2.16 kg) determined according to ISO 1133 standard of not more than 50 g / 10 min, preferably not more than 35 g / 10 min, more preferably not more than 25 g / 10 min, even more preferably not more than 15 g / 10 min and / or

[0083] - a density at 23°C determined according to ASTM D-792 standard of 0.850 - 0.915 g / cm3, preferably 0.855 - 0.900 g / cm3.

[0084] According to one or more embodiments, the at least one ethylene copolymer TP2 is an ethylene-butene copolymer or an ethylene-octene copolymer, preferably an ethylenebutene random copolymer or an ethylene-octene random copolymer, preferably having a comonomer (butene or octene) content of 5 - 50 wt.-%, more preferably 10 - 45 wt.-%, even more preferably 15 - 40 wt.-%, based on the weight of the ethylene copolymer.

[0085] According to one or more embodiments, the at least one ethylene copolymer TP2 is an ethylene-octene copolymer, preferably an ethylene-octene random copolymer, preferably having an octene content of 5 - 45 wt.-%, more preferably 10 - 40 wt.-%, even more preferably 15 - 35 wt.-%, still more preferably 15 - 30 wt.-%, such as 15 - 25 wt.-%, based on the weight of the ethylene-octene copolymer.

[0086] The proportion of butene or octene in an ethylene-butene copolymer or in an ethylene- octene copolymer can be determined directly by 1 H-NMR spectroscopy method known to a person skilled in the art.

[0087] According to one or more embodiments, the octene content of the ethylene-octene copolymer is determined using the method as described below.

[0088] Method for determining octene content of ethyne-octene copolymers

[0089] 1 H-NMR spectroscopy is carried out with a Bruker Ultrashield 300 MHz. A sample of 30-35 mg the copolymer is dissolved in 0.7 mL of 1 ,2-dichlorobenzene-d4 for 2 hours at 150 °C and 256 scans are accumulated at 130°C. For the calculation of the 1 -octene content, the following formula is used: where I CHS corresponds to the integral of the peak at 0.9 ppm assigned to the methyl terminal group,

[0090] I CH2 corresponds to the integral of the peak at 1 .3 ppm which is assigned to the H atoms of the CH2 groups of the base structure and of the 1 -octene side chains, and x corresponds to the content of octene in mol.-%. The content of octene in wt.-% can be calculated from the content of octene in mol.-% by using the following formula: 100 %

[0091] The measured peak positions correspond to the data presented in the literature.

[0092] Particularly suitable ethylene-octene copolymers for use as the at least one ethylene copolymer TP2 include the ethylene-octene copolymers, which are commercially available, for example, under the trade name of Engage® (from Dow Chemicals), under the trade name of Exact® (from Exxon Mobil), and under the trade name of Queo® (from Borealis AG).

[0093] According to one or more embodiments, the at least one thermoplastic polymer TP further comprises at least one thermoplastic polyolefin elastomer TP3 different from the at least one propylene copolymer TP1 and from the at least one ethylene copolymer TP2.

[0094] 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 components. In case of a reactor-blend 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.

[0095] 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 polypropylene random copolymer as the base polymer are often referred to as “heterophasic propylene random copolymers (RAHECO)”. The term “heterophasic propylene copolymer” encompasses in the present disclosure both the HECO and RAHECO types of heterophasic propylene copolymers.

[0096] 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.

[0097] According to one or more embodiments, the at least one thermoplastic polyolefin elastomer TP3 has

[0098] - a flexural modulus at 23°C determined according to ISO 178:2019 standard of not more than 1000 MPa, preferably not more than 750 MPa, more preferably not more than 500 MPa, even more preferably not more than 350 MPa, still more preferably not more than 150 MPa, most preferably not more than 100 MPa and / or

[0099] - a melting temperature determined by DSC according to ISO 11357 standard using a heating rate of 2°C / min of at least 100°C, preferably at least 110°C, more preferably at least 115°C, even more preferably at least 120°C and / or - 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 35 g / 10 min, more preferably not more than 30 g / 10 min, even more preferably not more than 25 g / 10 min and / or

[0100] - a xylene cold soluble content determined according to ISO 16152-2005 standard of at least 10 wt.-%, preferably at least 25 wt.-%, more preferably at least 35 wt.-%, even more preferably at least 45 wt.-%, still more preferably at least 55 wt.-%, such as in the range of 15 - 95 wt.-%, preferably 25 - 90 wt.-%, more preferably 35 - 85 wt.-%, even more preferably 45 - 80 wt.-%, still more preferably 50 - 70 wt.-%.

[0101] According to one or more embodiments, the at least one thermoplastic polyolefin elastomer TP3 is a heterophasic propylene copolymer, preferably comprising:

[0102] - 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

[0103] - 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).

[0104] 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.

[0105] Particularly suitable heterophasic propylene copolymers of use as the at least one thermoplastic polyolefin elastomer TP3 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.

[0106] Suitable compounds for use as the at least one elastomer E 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 methacrylateisoprene copolymer, acrylonitrile-isoprene copolymer, and acrylonitrile-butadiene copolymer.

[0107] It may be preferred to use rubbers as the at least one elastomer E that have a relatively low degree of unsaturation. The term “degree of unsaturation” refers in the present disclosure to the ratio of the number of unsaturated carbon-to-carbon bonds to the number of atoms in the linear chain of the average theoretical linear elastomer molecule. The low degree of unsaturation is essential in applications, where shaped articles such as membrane sheets obtained by using the thermoplastic composition must be able to withstand permanent exposure to various environmental factors, particularly UV-radiation. On the other hand, some degree of unsaturation may also be preferred to enable the chain extension and / or crosslinking / and / or coupling reactions to occur during processing of the halogen-free flame-retardant polymer composition to shaped articles.

[0108] According to one or more embodiments, the at least one elastomer E has a mole percent unsaturation of not more than 15, preferably not more than 10, more preferably not more than 5, even more preferably not more than 2.5.

[0109] According to one or more embodiments, the at least one elastomer E has a Mooney Viscosity (ML 1+8 at 125°C) of not more than 150 MU, preferably not more than 100 MU, more preferably not more than 85 MU, even more preferably not more than 70 MU, still more preferably not more than 55 MU, such as in the range of 10 - 125 MU, preferably 15 - 100 MU, more preferably 15 - 75 MU, even more preferably 20 - 65 MU. The term “Mooney viscosity” refers in the present disclosure to the viscosity measure of rubbers. It is defined as the shearing torque resisting rotation of a cylindrical metal disk (or rotor) embedded in rubber within a cylindrical cavity. The dimensions of the shearing disk viscometer, test temperatures, and procedures for determining Mooney viscosity are defined in ASTM D1646 -19a standard.

[0110] According to one or more embodiments, the at least one elastomer E comprises at least one butyl rubber E1 and / or at least one ethylene propylene diene monomer (EPDM) rubber E2.

[0111] The term “butyl rubber” designates in the present disclosure a polymer derived from a monomer mixture containing a major portion of a C4 to Ci 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.

[0112] The preferred C4 to C? monoolefin monomer may be 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.

[0113] The preferred C4 to C14 multiolefin comprises a C4 to C10 conjugated diolefin. The preferred C4 to C10 conjugated diolefin may be selected from the group comprising isoprene, butadiene, 2,4-dimethylbutadiene, piperyline, 3-methyl-1 ,3-pentadiene, 2,4- hexadiene, 2-neopentyl-1 ,3-butadiene, 2-methyl-1 ,5-hexadiene, 2,5-dimethyl-2,4- hexadiene, 2-methyl-1 ,4-pentadiene, 2-methyl-1 ,6-heptadiene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene, 1-vinyl-cyclohexadiene and mixtures thereof.

[0114] Preferably, the at least one butyl rubber E1 is derived from a monomer mixture containing from about 80 wt.-% to about 99 wt.-% of a C4 to C7 monoolefin monomer and from about 1 .0 wt.-% to about 20 wt.-% of a C4 to C14 multiolefin monomer. More preferably, the monomer mixture contains from about 85 wt.-% to about 99 wt.-% of a C4 to C7 monoolefin monomer and from about 1 .0 wt.-% to about 10 wt.-% of a C4 to C14 multiolefin monomer. Most preferably, the monomer mixture contains from about 95 wt.-% to about 99 wt.-% of a C4to C7 monoolefin monomer and from about 1 .0 wt.-% to about 5.0 wt.-%of a C4 to C14 multiolefin monomer.

[0115] The most preferred at least one butyl rubber E1 is derived from a monomer mixture comprising from about 97 wt.-% to about 99.5 wt.-% of isobutylene and from about 0.5 wt.- % to about 3 wt.-% of isoprene. It is furthermore possible to include an optional third monomer to produce a butyl terpolymer. For example, it is possible to include a styrenic monomer in the monomer mixture, preferably in an amount up to about 15 wt.-% of the monomer mixture. The preferred styrenic monomer may be selected from the group comprising p-methylstyrene, styrene, a-methylstyrene, p-chlorostyrene, p-methoxystyrene, indene, indene derivatives and mixtures thereof. The most preferred styrenic monomer may be selected from the group comprising styrene, p-methylstyrene and mixtures thereof. Other suitable copolymerizable termonomers will be apparent to those of skill in the art.

[0116] According to one or more embodiments, the at least one butyl rubber E1 is a halogenated butyl rubber. The term “halogenated rubber” refers in the present disclosure to a rubber having a halogen content of at least 0.1 mol.-%, wherein the halogen is preferably selected from the group consisting of bromine, chlorine and iodine. Preferred halogenated butyl rubbers to be used as the at least one butyl rubber E1 have a halogen content of 0.1 - 10 wt.-%, preferably 0.5 - 8 wt.-%, more preferably 0.5 - 5.0 wt.-%, based on the weight of the halogenated butyl rubber.

[0117] According to one or more embodiments, the at least one butyl rubber E1 is a bromobutyl rubber or a chlorobutyl rubber, preferably having a halogen content in the range of 0.1 - 10 wt.-%, more preferably 0.5 - 8 wt.-%, even more preferably 0.5 - 5.0 wt.-%, based on the weight of the halogenated butyl rubber.

[0118] The term “EPDM rubber” refers in the present disclosure to terpolymer of ethylene, propylene and a non-conjugated diene. Non-limiting examples of suitable non-conjugated dienes to be used in EPDM 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.

[0119] Suitable EPDM rubbers for use as the at least one EPDM rubber E2 have an ethylene content of at least 20 wt.-%, preferably at least 25 wt.-%, based on the weight of the EPDM rubber and a non-conjugated diene content of not more than 20 wt.-%, preferably not more than 15 wt.-%, based on the weight of the EPDM rubber, with the remaining content being essentially composed of polypropylene.

[0120] According to one or more embodiments, the at least one EPDM rubber E2 has

[0121] - an ethylene content of 25 - 85 wt.-%, preferably 35 - 80 wt.-%, more preferably 45 - 80 wt.-%, even more preferably 55 - 75 wt.-%, based on the weight of the EPDM rubber and / or

[0122] - a non-conjugated diene content of 1 - 20 wt.-%, preferably 1 - 15 wt.-%, more preferably 2 - 15 wt.-%, even more preferably 2 - 10 wt.-%, based on the weight of the EPDM rubber and / or

[0123] - a Mooney Viscosity (ML 1+4 at 125°C) of not more than 125 MU, preferably not more than 100 MU, more preferably not more than 75 MU, even more preferably not more than 65 MU, still more preferably not more than 55 MU, such as in the range of 5 - 100 MU, preferably 10 - 85 MU, more preferably 15 - 75 MU, even more preferably 20 - 65 MU.

[0124] Suitable EPMD rubbers are commercially available, for example, under the trade name of Nordel® (from Dow Chemical Company), under the trade name of Buna EP® (from Lanxess), and under the trade name of Vistaion® (from Exxon Mobil).

[0125] According to one or more embodiments, the at least one elastomer E is composed of the at least one butyl rubber E1 and / or the at least one EPDM rubber E2.

[0126] According to one or more embodiments, the organic polymer component a) comprises: a1) 35 - 90 wt.-%, preferably 40 - 85 wt.-%, of the at least one thermoplastic polymer TP and / or a2) 5 - 60 wt.-%, preferably 10 - 55 wt.-%, of the at least one elastomer E, all proportions based on the total weight of the organic polymer component.

[0127] According to one or more embodiments, the sum of a) and b) makes up at least 55 wt.-%, preferably at least 65 wt.-%, more preferably at least 75 wt.-%, of the total weight of the halogen-free flame-retardant polymer composition.

[0128] The halogen-free flame-retardant polymer composition may further comprise at least one catalyst. The catalyst may be added to the halogen-free flame-retardant polymer composition, for example, to catalyze chain extension and / or crosslinking and / or coupling reactions of the polymeric constituents, such as the at least one elastomer E, during meltprocessing and / or shaping of the polymer composition.

[0129] The at least one catalyst, if used, is preferably selected from the group consisting of metal oxides, metal salts of fatty acids and metal salts of boric acid, sulfur catalysts, phenol resin catalysts, fatty acids, and mixtures thereof.

[0130] Suitable metal oxide catalysts and metal salts of fatty acids include, for example, ZnO, CaO, MgO, AI2O3, CrO3, FeO, Fe2O3, and NiO and zinc salts of fatty acids having at least 6 carbon atoms. Suitable sulfur catalysts include powdered sulfur, precipitated sulfur, high dispersion sulfur, surface-treated sulfur, insoluble sulfur, dimorpholinedisulfide, alkylphenoldisulfide, and mixtures thereof. Suitable phenol resin catalysts include bromide of an alkylphenol resin or mixed catalysts containing stannous chloride, chloroprene, or another halogen donor and an alkylphenol resin, and mixtures thereof.

[0131] According to one or more embodiments, the at least one catalyst is selected from the group consisting of ZnO, CaO, MgO, AI2O3, CrO3, FeO, Fe2O3, and NiO, zinc salts of fatty acids having at least 6 carbon atoms, preferably at least 13 carbon atoms, zinc borate, and mixtures thereof.

[0132] The at least one catalyst may also be used in combination with at least one accelerator selected from the group consisting of guanidine compounds, aldehyde amine compounds, aldehyde ammonium compounds, thiazole compounds, sulfonamide compounds, thiourea compounds, thiuram compounds, xanthane compounds, and dithiocarbamate compounds. Such accelerators may be present in the halogen-free flame-retardant polymer composition in an amount of 0.1 - 5.0 phr (parts by weight per 100 parts by weight of the at least one elastomer E).

[0133] The at least one catalyst, if used, is preferably present in the halogen-free flame-retardant polymer composition in an amount of not more than 10 wt.-%, more preferably not more than 7.5 wt.-%, even more preferably not more than 5 wt.-%, based on the total weight of the halogen-free flame-retardant polymer composition. It may further be preferable that the at least one catalyst makes up 0.01 - 5 % wt.-%, more preferably 0.05 - 2.5 wt.-%, even more preferably 0.1 - 1.5 wt.-%, most preferably 0.25 - 1 wt.-%, of the total weight of the halogen-free flame-retardant polymer composition.

[0134] According to one or more embodiments, the at least one catalyst is zinc oxide and the halogen-free flame-retardant polymer composition further comprises at least 0.05 wt.-%, preferably 0.1 - 0.5 wt.-%, based on the total weight of the polymer composition, of at least one zinc salt of a fatty acid, preferably zinc stearate and / or at least 0.05 wt.-%, preferably 0.1 - 0.5 wt.-%, based on the total weight of the polymer composition, of at least one saturated fatty acid having at least 6 carbon atoms, preferably at least 13 carbon atoms.

[0135] According to one or more embodiments, the at least one catalyst is zinc oxide and the halogen-free flame-retardant polymer composition further comprises at least 0.05 wt.-%, preferably 0.1 - 0.5 wt.-%, based on the total weight of the polymer composition, of zinc stearate and / or at least 0.05 wt.-%, preferably 0.1 - 0.5 wt.-%, based on the total weight of the polymer composition, of a fatty acid selected from the group consisting of stearic acid and montanic acid.

[0136] According to one or more embodiments, the at least one thermoplastic polymer TP comprises or is composed of a polyvinylchloride resin TP4 or a thermoplastic polyurethane TP5. In these embodiments it may be preferred that the organic polymer component does not comprise the at least one elastomer E.

[0137] In embodiments, where the thermoplastic polymer TP comprises or is composed of a polyvinylchloride resin TP4, the halogen-free flame-retardant polymer composition may further contain a plasticizer for the PVC resin.

[0138] Suitable plasticizers for the PVC resin include, for example, linear or branched phthalates such as di-isononyl phthalate (DINP), di-nonyl phthalate (L9P), diallyl phthalate (DAP), di- 2-ethylhexyl-phthalate (DEHP), dioctyl phthalate (DOP), diisodecyl phthalate (DI DP), and mixed linear phthalates (911 P). Other suitable plasticizers include phthalate-free plasticizers, such as trimellitate plasticizers, adipic polyesters, and biochemical plasticizers. Examples of biochemical plasticizers include epoxidized vegetable oils, for example, epoxidized soybean oil and epoxidized linseed oil and acetylated waxes and oils derived from plants, for example, acetylated castor wax and acetylated castor oil. The halogen-free flame-retardant 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.-%, even more preferably not more than 5 wt.-%, based on the total weight of the polymer composition.

[0139] Suitable fillers for use in the halogen-free flame-retardant polymer composition include, for example, inorganic fillers, such as 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.

[0140] According to one or more embodiments, the halogen-free flame-retardant polymer composition comprises at least one solid particulate filler, preferably selected from calcium carbonate, magnesium carbonate, clay, expanded clay, diatomaceous earth, pumice, mica, kaolin, talc, dolomite, xonotlite, perlite, vermiculite, Wollastonite, barite, calcium hydroxide, calcium aluminates, silica, fumed silica, and fused silica.

[0141] The at least one solid particulate filler 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 100 pm, preferably 50 pm, more preferably 25 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).

[0142] Suitable UV-stabilizers include, particularly, the hindered amine light stabilizers (HALS). These types of compounds are typically added to polymer blends to prevent light-induced polymer degradation. Such UV-stabilizers are needed especially in case shaped articles prepared from the halogen-free flame-retardant polymer composition are used in outdoor applications, for example, in waterproofing of roof or fagade substrates. According to one or more embodiments, the halogen-free flame-retardant polymer composition further comprises: d) 0.05 - 10 wt.-%, preferably 0.1 - 5 wt-%, more preferably 0.25 - 2.5 wt.-%, even more preferably 0.25 - 1 .5 wt.-%, based on the total weight of the halogen-free flame-retardant polymer composition, of at least one hindered amine light stabilizer (HALS).

[0143] Suitable commercially available hindered amine light stabilizers include, for example, alkoxyamine hindered amine light stabilizers (NOR-HALS), such as: bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, commercially available, for example, as Tinuvin® NOR 123 (from Ciba Chemicals, CAS number 129757-67-1); derivatives of N-butyl-2,2,6,6-tetramethyl-4-piperidinamine, commercially available, for example, as Tinuvin® NOR 152 (from Ciba Chemicals); and reaction products with 3- bromo-1 -propene, n-butyl-1-butanamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine, oxidised, hydrogenated, commercially available, for example, as Tinuvin NOR® 371 (from Ciba Chemicals).

[0144] The halogen-free flame-retardant polymer composition may further comprise at least one UV-absorber, preferably selected the group consisting of hydroxybenzophenones, hydroxybenzotriazoles, anilides, benzoates, cyanoacrylates, phenylformamidines, and mixtures thereof.

[0145] According to one or more embodiments, the halogen-free flame-retardant polymer composition further comprises 0.05 - 10 wt.-%, preferably 0.1 - 5 wt.-%, more preferably 0.25 - 2.5 wt.-%, even more preferably 0.25 - 1 .5 wt.-%, based on the total weight of the polymer composition, of at least one UV-absorber, preferably selected from the group consisting of of hydroxybenzophenones, hydroxybenzotriazoles, anilides, benzoates, cyanoacrylates, phenylformamidines.

[0146] Suitable UV-absorbers are commercially available, for example, under the trade name of Tinuvin® (from Ciba Specialty Chemicals), such as Tinuvin ® 213, 234, 320, 326-329, 350, 360, 571. The preferences given above for the halogen-free flame-retardant polymer composition apply equally apply equally to all other subjects of the present invention unless otherwise stated.

[0147] Another aspect of the present invention is a sealing element comprising a shaped article obtained by using the halogen-free flame-retardant polymer composition according to the present invention.

[0148] The shaped article can be, for example, in form of a layer, cube, or a tube and it can be obtained from the halogen-free flame-retardant polymer composition by using conventional manufacturing techniques, for example, extrusion, hot pressing, injection molding, or additive manufacturing techniques, such as 3D printing.

[0149] According to one or more embodiments, the shaped article is obtained by a process comprising melt-processing a starting composition comprising or composed of the constituents of the halogen-free flame-retardant polymer composition of the present invention. The term “melt-processing” refers here 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 flame retardant, filler or a catalyst, until a melt blend, i.e., a substantially homogeneously mixed mixture of the polymeric component(s) and the other constituents is obtained.

[0150] The melt processing of the starting 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.

[0151] The process for obtaining the shaped article preferably comprises a further step of meltshaping of the melt-processed starting composition into a form of a shaped article. The melt-shaping step can be conducted by using various techniques known to those of skill in the art, such as, extruding, co-extruding, injection molding, thermoforming, film blowing, casting, calendaring, or 3D printing. A skilled person is familiar with melt-shaping techniques and can select the suitable alternative based on the dimensions of the shaped article. For example, layers having a thickness of below 350 pm, such as of below 250 pm, may be preferably produced by a blown film extrusion or co-extrusion process. In a blown film extrusion process, a molten polymer composition obtained from an extruder is forced through an upwards facing opening of a blown film extruder die, typically an upright cylinder with an annular opening, like a pipe extrusion die. Furthermore, substrate layers having a thickness of at least 0.5 mm, such as at least 0.75, may be preferably produced by a die extrusion, hot-pressing, or calendaring processes.

[0152] According to one or more embodiments, the sealing element comprises a further shaped article, wherein the shaped article and the further shaped article are directly or indirectly connected, preferably directly connected, to each other over at least a portion of their opposing major surfaces.

[0153] The further shaped article may also be obtained using the halogen-free polymer composition of the present invention. However, the composition of the shaped article and the further shaped article may also differ from each other.

[0154] According to one or more embodiments, the sealing element is a membrane, preferably a fagade membrane, roofing membrane, waterproofing membrane, gas barrier membrane, volatile organic compound (VOC) barrier membrane, vapor barrier membrane, vapor retarder membrane, or a geomembrane.

[0155] Another aspect of the present invention is a method for producing a sealing element comprising a shaped article, the method comprising steps of melt-processing a starting composition comprising or composed of the constituents of the halogen-free flameretardant polymer composition of the present invention and melt-shaping the melt- processed starting composition into a form of a shaped article.

[0156] The melt processing of the starting 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.

[0157] The method for producing a sealing element preferably comprises a further step of meltshaping of the melt-processed starting composition into a form of a shaped article. 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, or 3D printing, as already discussed above.

[0158] According to one or more embodiments, the method for producing a sealing element comprises steps of: i) Melt-processing the starting composition in an extruder to provide a melt-blend of the starting composition and ii) Extruding or injecting said melt-blend through an extruder or injection die.

[0159] 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. 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.

[0160] 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. 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, and 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.

[0161] The maximum temperature of the starting 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 180°C. The maximum temperature of the starting composition during melt processing in the screw section of the extruder can be in the range of 150 - 250°C, for example 160 - 220°C, such as 180 - 200°C.

[0162] The at least one thermoplastic polymer TP, the at least one elastomer E, the at least one siloxane polymer SP, if used, the flame-retardant system, and the at least one catalyst, if used, may be fed to the extruder as individual streams, as a pre-mix, dry blend, or as a master batch.

[0163] The at least one thermoplastic polymer TP and the at least one elastomer E may be fed into the extruder through the feed port and the at least one catalyst, 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. The at least one elastomer E can also be mixed with the at least one catalyst, if used, 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. Preferably the premixing of the at least one elastomer E and the at least one catalyst is preferably conducted at a temperature, which is above the melting point of the at least one elastomer E and below the activation temperature of the at least one catalyst, i.e. temperature at which the chain extension and / or crosslinking / and / or coupling reactions of the at least one elastomer E are initiated. Alternatively, the at least one thermoplastic polymer TP and the at least one elastomer E can be processed in a compounding extruder to pellets or granules, which are dry-blended with the at least one catalyst, if used, and the resulting dry-blend is then fed into extruder though the feed port. Still another aspect of the present invention is use of the halogen-free flame-retardant polymer composition according to the present invention for providing a membrane, preferably a fagade membrane, roofing membrane, waterproofing membrane, gas barrier membrane, volatile organic compound (VOC) barrier membrane, vapor barrier membrane, vapor retarder membrane, or a geomembrane.

[0164] Examples

[0165] The materials shown in Table 1 were used for preparing the samples of shaped articles. Table 1

[0166] The inventive and reference shaped articles were prepared from the tested halogen-free flame-retardant compositions according to the procedure as described below and tested for their flame retardancy properties.

[0167] Preparation of shaped articles

[0168] The shaped articles were produced from the starting compositions 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.

[0169] In producing of the membrane sheets, the thermoplastic polymers TP and the elastomers E were fed to the extruder hopper. The polymer blend was melt-processed in the first of the four zones of the extruder and a pre-mix of flame retardants, catalyst (if used), hindered amine light stabilizer (if used), and the additive package (if used) was 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 0.3 - 0.6 mm. The extrusion was conducted using an extrusion temperature of 200 - 210 °C and pressure of 156 - 166 bar.

[0170] The constituents of the starting composition and their amounts fed into the extruder during the preparation of the shaped articles are shown in Tables 3 and 4.

[0171] Flame retardancv properties

[0172] Samples having dimensions of 250 mm x 90 mm (length x width) were cut from the shaped articles and burned vertically for one minute prior to removal of the flame. The burned length and width and the maximum flame height during the testing were measured and a fire rating value on a scale of 12- 3 was given for each tested system. The dependency of the fire rating value from burned length and width and the maximum flame height is shown in Table 2. The results of the fire rating measurement obtained with the tested shaped articles are shown in Tables 3 and 4.

[0173] Table 2

[0174] able 3

[0175] Table 4

[0176] Tensile stress and elongation at break The tensile stress and elongation at break were measured for samples cut from the membrane sheets in machine and cross machine direction. The measurements were conducted according to EN 12311-2:2013 standard at a temperature of 23°C using a cross head speed of 500 mm / min. The values for tensile stress and elongation at break obtained with the tested membrane sheets are presented in Table 5.

[0177] Table 5

[0178] MD = machine direction, CD = cross machine direction

Claims

Claims1 . A halogen-free flame-retardant polymer composition comprising: a) An organic polymer component comprising: a1) At least one thermoplastic polymer TP and / or a2) At least one elastomer E, and b) A flame-retardant system comprising: b1) At least one first nitrogen-containing organophosphorus compound and optionally at least one metal borate, b2) At least one organometallic salt, and b3) At least one second nitrogen-containing organophosphorus compound.

2. The halogen-free flame-retardant polymer composition according to claim 1 , wherein the at least one first nitrogen-containing organophosphorus compound is selected from piperazine pyrophosphate, piperazine bis(dimethyl) phosphoramidate, piperazine DOPO, and EDA-DOPO.

3. The halogen-free flame-retardant polymer composition according to claim 1 or 2, wherein the at least one metal borate is selected from calcium borate and zinc borate.

4. The halogen-free flame-retardant polymer composition according to any one of previous claims, wherein the at least organometallic salt is an organic phosphinate metal salt, preferably an organic phosphinate aluminum salt and / or the at least one second nitrogen-containing organophosphorus compound is a phosphoric acid melamine salt, preferably selected from melamine polyphosphate, melamine phosphate, and melamine pyrophosphate.

5. The halogen-free flame-retardant polymer composition according to any one of previous claims, wherein the at least one organometallic salt is aluminium diethyl phosphinate and / or the at least one second nitrogen-containing organophosphorus compound is melamine polyphosphate.

6. The halogen-free flame-retardant composition according to any one of previous claims, wherein the flame-retardant system b) makes up 35 - 75 wt.-%, preferably 40 - 70 wt.-%, of the total weight of the halogen-free polymer composition.

7. The halogen-free flame-retardant polymer composition according to any one of previous claims, wherein the flame-retardant system b) comprises: b1) 0.5 - 25 wt.-%, preferably 1 .5 - 20 wt.-%, of the at least one first nitrogencontaining organophosphorus compound or of a mixture of the at least one metal borate and the at least one first nitrogen-containing organophosphorus compound, b2) 5 - 55 wt.-%, preferably 10 - 50 wt.-%, of the at least one organometallic salt, and b3) 5 - 55 wt.-%, preferably 10 - 50 wt.-%, of the at least one second nitrogen-containing organophosphorus compound, all proportions being based on the total weight of the flame-retardant system b).

8. The halogen-free flame-retardant polymer composition according to any one of previous claims, wherein the weight ratio of the at least one organometallic salt to the at least one second nitrogen-containing organophosphorus compound in the halogen-free flame-retardant polymer composition is in the range of from 1.5:1 to 1 :1.5, preferably from 1.3:1 to 1 :1.3.

9. The halogen-free flame-retardant polymer composition according to any one of previous claims, wherein the flame-retardant system b) further comprises: b4) Expandable graphite and / or wood particles.

10. The halogen-free flame-retardant polymer composition according to claim 9, wherein the expandable graphite or wood particles or a mixture thereof makes up 5 - 45 wt.-%, preferably 10 - 40 wt.-%, of the total weight of the flameretardant system b).11 . The halogen-free flame-retardant polymer composition according to any one of previous claims, wherein the at least one thermoplastic polymer TP is selected from polyolefins, thermoplastic polyurethanes, polyvinylchloride (PVC), and ketone ethylene esters (KEE).

12. The halogen-free flame-retardant polymer composition according to any one of previous claims, wherein the sum of the a) and b) makes up at least 55 wt.-%, preferably at least 65 wt.-%, of the total weight of the halogen-free flameretardant polymer composition.

13. The halogen-free flame-retardant polymer composition according to any one of previous claims further comprising at least one catalyst selected from metal oxides, metal salts of fatty acids, metal salts of boric acid, sulfur catalysts, phenol resin catalysts, fatty acids, and mixtures thereof.

14. A sealing element comprising a shaped article obtained by using the halogen- free flame-retardant polymer composition according to any one of previous claims.

15. The sealing element according to claim 14, wherein the sealing element is a membrane, preferably a fagade membrane, roofing membrane, waterproofing membrane, gas barrier membrane, volatile organic compound (VOC) barrier membrane, vapor barrier membrane, vapor retarder membrane, or a geomembrane.

16. A method for producing a sealing element, the method comprising steps of melt-processing a starting composition comprising the constituents of the halogen-free flame-retardant polymer composition according to any one of claims 1-13 and melt-shaping the melt-processed starting composition into form of a shaped article.

17. Use of the halogen-free flame-retardant polymer composition according to any one of claims 1-13 for providing a membrane, preferably a fagade membrane, roofing membrane, waterproofing membrane, gas barrier membrane, volatileorganic compound (VOC) barrier membrane, vapor barrier membrane, vapor retarder membrane, or a geomembrane.

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