Lightweight bituminous waterproofing membranes with flame-resistance properties

Abstract

Disclosed are waterproofing formulations with a density of less than 0.99 g / cm3 based on polymer-modified bitumen, lightweight aggregates and flame-retardant additives, for the manufacture of bituminous waterproofing membranes with a high content of recycled material.

Description

[0001] LIGHTWEIGHT BITUMINOUS WATERPROOFING MEMBRANES WITH FLAME¬

[0002] RESISTANCE PROPERTIES

[0003] The present invention relates to bituminous waterproofing membranes whose bituminous formulation is based on polymer-modified bitumen, lightweight aggregates and flame-retardant additives, and is further characterised by a density of less than 0.99 g / cm3.

[0004] Prior art

[0005] Among the most widely waterproofing materials used in the construction industry, bituminous membranes play a crucial role because of their suitability in being used in various fields, not only to protect residential roofs (flat and / or sloping) but also industrial and commercial surfaces and horizontal or vertical foundations.

[0006] A bituminous membrane can be defined as a material consisting of a combination of three different elements which synergistically cooperate with each other:

[0007] • a bituminous formulation, which is designed to waterproof the finished product. The bitumen properties are improved by the use of different polymers, depending on the intended purpose of the resulting membrane;

[0008] • a substrate / reinforcement which could have synthetic and / or natural nature, the role whereof is to give the product its main mechanical properties (tensile strength at break, elongation, and tear strength). The typically used substrates are made of nonwoven polyester fabric and / or surfacing mat, glass mesh, or a combination of the various types and weights;

[0009] • external finishes involving the application of functional and / or protective elements such as polyolefin films, graphite, vermiculite, metal foil, sand, talc, slate, and in general mineral protections.

[0010] Specifically, the bitumen properties can be modulated thanks to the modifying polymer used, and two main types of modified bitumens can be identified: plastomeric-modified and elastomeric-modified.

[0011] EP 0667374 discloses the bitumen modification with different polymer blends to obtain improved performances for use in street paving, various kinds of waterproofing.

[0012] In the literature, a lot of studies describe the use of the most popular plastomers and thermoplastic elastomers to modify bitumen, including isotactic polypropylene (z-PP), atactic polypropylene (rz-PP), polyethylene (PE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), thermoplastic polyolefins (TPO), ethylene-propylene copolymers (EPM, EPDM), ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), styrene butadiene styrene (SBS), styrene isoprene styrene (SIS) and styrene ethylene butylene styrene (SEBS), as well as functionalised polymers and reagents such as maleic anhydrides (MAH), methacrylic acids and their derivative esters, and glycidyl methacrylate (GMA) (J. Zhu, B. Birgisson, N. Kringos, European Polymer Journal, 2014, 54, 18-38).

[0013] Examples of polymers which are particularly compatible with bitumen, and were specifically developed for the industry, comprise ethyl ene-propylene block copolymers wherein the propylene presents insertions on the main chain and amorphous polyolefins obtained by low-pressure copolymerisation of a-olefins (ethylene, propylene and isobutylene). The use of these polymers produces modified bitumen for the bituminous membranes manufacturing with good performances in terms of durability (A. H. Fawcett, Lor S-K. Polymer 1992;33:2003; A. H. Fawcett, T. McNally, Polymer, 2000, 41, 5315-5326).

[0014] Ethyl ene-propylene rubbers can also be used for the same purpose, wherein the monomers are randomly distributed along the main polymer chain and the homopolymer sequences are short, can also be used for said purpose; for example, EP 130014 discloses bituminous mixtures with improved thermal properties which are suitable for waterproof roofing.

[0015] The use of recycled polymers has become increasingly important in recent years due to the concepts of circular economy and environmental sustainability (S. Nemade, P. Thorat, ci. Revs. Chem. Commun.: 3(4), 2013, 198-213).

[0016] The bituminous formulations for the prefabricated waterproofing membranes manufacturing therefore consist of polymers able to modify the rheological, thermal and mechanical properties of the bituminous base, as well as organic or inorganic fillers, typically calcium carbonate. Other types of minerals can also be used.

[0017] For example, US 2006110996 discloses the use of titanium dioxide as a component of the bituminous formulation for the manufacturing of reinforced waterproofing membranes.

[0018] US 4220524 involves the use of various compounds such as slaked lime, talc, clays, diatomaceous earths, cement and their derivatives as mineral fillers for bituminous waterproofing masses constituting the membranes.

[0019] EP 2264092 claims bituminous membranes with a specific gravity of less than 1 g / cm3consisting of a reinforcing material, which is impregnated with a bituminous formulation consisting of bitumen and polymers and distinguished by the use of aluminium silicate cenospheres with a density ranging between 0.60 and 0.82 g / cm3, and dimensions ranging between 5 and 300 pm, as inorganic filler. EP 2264094 discloses waterproofing membranes with a specific gravity of less than 1 g / cm3comprising hollow glass microbeads with a density ranging between 0.10 and 0.14 g / cm3, and dimensions lower than 120 pm, as inorganic filler (instead of calcium carbonate), mixtures of polymers and bitumen.

[0020] In recent years, thanks to technologies development, the buildings roofs have become increasingly efficient in terms of safety and energy saving (e.g. “cool roofs”, “blue roofs” and “green roofs”). The external fire behaviours is an increasingly important topic and thus it plays a crucial role in the design of buildings and roofs.

[0021] In this context, European Regulation no. 305 / 2011 lays down harmonised conditions for the construction products marketing, and indicates that the essential fire-safety requirements for construction works are as follows: a) the load-bearing capacity of the construction must be guaranteed for a specific period of time; b) the generation and spread of fire and smoke must be limited; c) the spread of fire to neighbouring construction works must be limited; d) occupants must leave the construction works or be rescued by other means; e) rescue teams safety.

[0022] As regards bituminous membranes, the product is classified not only based on their reaction to fire according to EN 13501-1, but also in terms of behaviour in case of external fire according to EN 13501-5, using the four test methods specified in UNI CEN / TS 1187.

[0023] The substrates conventionally used are made of non-woven organic polymer fibres, in particular polyester fibres, and in some cases can be reinforced with fibreglass. Said composite reinforcements are disclosed in EP 1 200 257 Bl.

[0024] For example, US 6 993 876 discloses roof waterproofing membranes obtained by a fibreglass substrate impregnation by a bituminous mass.

[0025] W02012 / 065903 relates to a reinforced substrate for bituminous membranes made of synthetic fibres and cellulose-based reinforcing yarns.

[0026] Other substrates (reported in W02020 / 225200) consist of a first non-woven layer and a second non-woven layer, which include polyester fibres, and an intermediate layer made of a non-woven fibres and comprising organic flame-resistant fibres, which contribute to improving the flame-resistance characteristics of bituminous membranes.

[0027] For this purpose, flame-retardant additives and / or minerals are incorporated in the bituminous formulation, which is the main membrane component. US 4659381 and US 4804496 disclose the use of halogenated flame retardants, ammonium phosphates and red phosphorus, to give the bituminous formulation flame-resistant properties.

[0028] Many minerals and chemical additives used as flame retardants are expensive, and often hazardous for the environment and the human safety. The use of bromine-based halides, for example, is considerably limited by the REACH regulation due to the vapours which are developed in case of fire. Similarly, the entire class of chlorinated paraffins is included in the list of Substances of Very High Concern (SVHC List), because it has not only proved to be carcinogenic, but also bioaccumulative, persistent and toxic.

[0029] Other commonly used inorganic flame retardants are based on metal hydroxides such as magnesium hydroxide Mg(0H)2, aluminium hydroxide / alumina tri-hydrate Al(0H)3, hydrated aluminium oxide A10(0H), and compounds of zinc, antimony and boron such as boric acid, borate and borax (Nail^O? • 10 H2O).

[0030] US 5055135 claims an elastomer-modified bituminous formulation containing 35% to 50% by weight of colemanite (Ca2BeOn 5(H2O)), used as a flame retardant as an alternative to halides.

[0031] The efficacy of these minerals is attributable to their endothermic decomposition mechanism in which the solid phase is cooled and therefore the degradation of the material is slowed, the gaseous phase is diluted with steam (produced by decomposition). The produced fumes are less dense and not corrosive.

[0032] US 2006273290 discloses the use of expandable graphite to give flame-resistance properties.

[0033] Graphite considerably increases its volume due to its ability to expand in case of fire, creating a very large surface that allows rapid oxidation of carbon, and consequently extinguishing the flame.

[0034] US 2021340768 describes the efficacy of non-expanded vermiculite, which can also be used in combination with common retardants to improve the flame resistance of bituminous waterproofing membranes.

[0035] However, these types of flame retardant best perform their function at high percentages. This considerably worsens the properties of the bituminous formulation, for example, by increasing its viscosity and hardening the formulation, thereby limiting its processability during the various steps of the bituminous membrane manufacturing. Thus the so produced bituminous membrane presents a considerable increased density and a worsening of its mechanical properties and flexibility at low temperatures.

[0036] In fact, the current commercial bituminous membranes with fire resistance properties are made of organic and / or inorganic additives with a density exceeding 2 g / cm3, such as brucite, magnesium hydroxide, aluminium hydroxide and titanium hydroxide and, by means of different mechanisms (mainly chemical reactions), they reduce the heat released by a fire and limit the spread of flames. Consequently, the bituminous formulations of these membranes with “higher” densities (1.10-1.45 kg / L) make the membrane rolls heavier, with masses per unit area ranging between 5 and 6 kg / m2(thickness 4-5 mm), and thus they become difficult to move on site and during application, as well as having a greater environmental and economic impact during transport.

[0037] An important topic is the sustainability of materials used in the construction industry, which is one of the goals of the United Nations (UN) 2030 Agenda for Sustainable Development. Sustainability is also one of the pillars of the Italian National Recovery and Resilience Plan (PNRR); environment-friendliness and economic sustainability have strategic value, with over 30% of funds devoted to the green revolution and ecological transition. A building designed, built or renovated to minimise its impact on the environment throughout its life cycle can be classed as environmentally sustainable.

[0038] Hence the need for a bituminous waterproofing membrane able to guarantee high qualitative performance, a small mass per unit area, fire resistance and environmental sustainability.

[0039] Summary of the invention

[0040] The object of the present invention is a bituminous formulation characterised by a density of less than 0.99 g / cm3with fire resistance properties according to UNI CEN / TS 1187, EN 13501-1 and EN 13501-5.

[0041] The bituminous formulation according to the invention comprises bitumen modified with at least one plastomeric and / or elastomeric polymer, a lightweight aggregate characterised by a density of less than 1 g / cm3, a flame-retardant additive different from the halogenated paraffins, and optionally an inorganic filler having a density greater than 1 g / cm3.

[0042] By impregnating a reinforcing substrate with the bituminous formulation, object of the invention, flame-resistant bituminous waterproofing membranes can be obtained, which are applicable with a blowtorch or self-adhesive, and which constitute further objects of the invention.

[0043] Thickness being equal, the bituminous formulation according to the invention allows the bituminous waterproofing membranes manufacturing with better performance characteristics and lower masses per unit area (and thus more lightweight) than the traditional membranes present on the market.

[0044] The consequent lightness of the bituminous waterproof membranes allows to produce rolls which are more manageable on site and easier to apply in terms of speed and deployment of the membrane, than the products currently available on the market and having the same functions.

[0045] The result of the invention is made possible by the synergy generated between the lightweight aggregate, which is heat, compression and chemical agents resistant, and the used flame-retardant additive, and the type of polymer modification of the bitumen.

[0046] BRIEF DESCRIPTION OF FIGURES

[0047] Figure 1. Thermogravimetric analysis carried out on lightweight aggregates, calcium carbonate and flame-retardant additive.

[0048] Figure 2. Flame-resistant bituminous waterproofing membrane partly consisting of the bituminous formulation.

[0049] Figure 3. Flame-resistant bituminous waterproofing membrane partly consisting of the bituminous formulation.

[0050] Figure 4. Flame-resistant bituminous waterproofing membrane wholly consisting of the bituminous formulation.

[0051] Figure 5. Microscope photo of a traditional formulation (left) compared with the bituminous formulation prepared according to Example 1 (right).

[0052] Figure 6. Photo of bituminous waterproofing membrane prepared according to Example 6 before (left) and after (right) the Broof(t4) external fire exposure test according to UNI CEN / TS 1187:2012 and UNI EN 13501-5.

[0053] Definitions

[0054] “Plastomeric polymer” means a semicrystalline polyolefin polymer used as modifier for virgin and / or recycled bitumen.

[0055] “Elastomeric polymer” means a polymer of natural or synthetic origin having the physicochemical characteristics of an elastic rubber, which is used as modifier for virgin and / or recycled bitumen.

[0056] The term “substrate / reinforcement” relates to a material formed by filaments and / or fibres of various chemical natures, compacted and bonded by mechanical, thermal or chemical action (using binders), confer the main mechanical properties to the bituminous membrane. “Lightweight aggregate” means an inert material characterised by a density of less than 1 g / cm3. The lightweight aggregate can be of natural origin, such as pumice, or artificial origin, such as expanded clay, diatomaceous earths, vermiculite, perlite and glass microbeads obtained by thermal processes.

[0057] “Filler” means an inorganic additive characterised by a density greater than 1 g / cm3. The filler is added into the bituminous formulates to fill it; the best-known filler is, for example, calcium carbonate.

[0058] “Flame retardant” means an additive able to reduce the risk of flame generation, spread and development. The flame retardant may be organic, such as the family of triazines and derivatives thereof, or inorganic, such as aluminium phosphite, colemanite and magnesium hydroxide.

[0059] Detailed description of the invention

[0060] The first aspect of the present invention is the composition of the bituminous formulation, which has fire-resistance properties and is characterised by a density of less than 0.99 g / cm3, typically ranging between 0.90 g / cm3and 0.99 g / cm3, as defined in the claims.

[0061] The bitumen in the bituminous formulation can be selected from the following types: 240 / 300, 160 / 220, 70 / 100 and / or 50 / 70, in an amount ranging between 65% and 80% by weight, preferably 70%.

[0062] Examples of polymers used to modify bitumen are plastomers and thermoplastic elastomers, such as isotactic polypropylene (i-PP), atactic polypropylene (a-PP), polyethylene (PE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), thermoplastic polyolefins (TPO), ethyl ene-propylene copolymers (EPM, EPDM), ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), styrene butadiene styrene (SBS), styrene isoprene styrene (SIS) and styrene ethylene butylene styrene (SEBS), as well as functionalised polymers and reagents such as maleic anhydrides (MAH), methacrylic acids and the derivative esters thereof, glycidyl methacrylate (GMA) and a-olefin copolymers (ethylene, propylene and isobutylene). The percentage of polymer modifier ranges between 5% and 20%, preferably between 10% and 15%, by weight.

[0063] Examples of inorganic fillers characterised by a density greater than 1 g / cm3comprise different types of carbonates, such as slaked lime, talc, cement and their derivatives, in percentages ranging between 0% and 15% by weight, preferably between 0% and 6%.

[0064] The lightweight aggregate characterised by a density of less than 1 g / cm3is present in the formulation in amounts ranging between 2% and 15% by weight, preferably between 5% and 10% by weight.

[0065] Examples of usable lightweight aggregates are clays and expanded clays; diatomaceous earths; perlites and expanded perlites (preferably having the characteristics listed in Table 1); hollow glass microbeads (preferably with a density ranging between 0.10 g / cm3and 0.14 g / cm3and dimensions lower than 120 pm) in an amount ranging between 2% and 7% by weight, preferably between 3% and 5% by weight; aluminium silicate cenospheres (preferably with a density ranging between 0.60 g / cm3and 0.85 g / cm3and dimensions ranging between 5 pm and 300 pm, more suitably between 5 pm and 106 pm, or their mixtures); silica (SiCh) microbeads, preferably foam microbeads, consisting of recycled glass, preferably ranging between 10% and 90%, having the characteristics listed in Table 1.

[0066] Table 1. Physical characteristics of some families of lightweight aggregates.

[0067] The above-mentioned glass microbeads have a multicellular inner structure and have excellent mechanical and thermal properties which the aggregate an inert material perfectly suitable for a wide variety of applications which require a density and / or weight reduction of the end products.

[0068] As stated above, it has been found that the lightweight aggregate, as well as reducing the density of the bituminous formulation, contributes to the fire-resistance properties given by the flame retardant additive, because it does not degrade, with increasing temperature (Figure 1).

[0069] The flame-retardant additive incorporated in the bituminous formulation acts according to at least one of the following action mechanisms:

[0070] A. Development of inert gases and dilution of gas phase.

[0071] B. Development of radical reactions in the gas phase.

[0072] C. Reduction of solid-phase temperature by endothermic decomposition reactions.

[0073] D. Formation of a physical barrier on the surface of the material. E. Intumescence.

[0074] Examples of suitable flame retardants can be based on:

[0075] 1. Phosphorus: the best known include red phosphorus, ammonium polyphosphate, aluminium phosphite, tris (2-chloroethyl) phosphate (TCEP), tris-(l,3-dichloroisopropyl) phosphate (TDCIPP), (triphenyl)phosphate (TPhP) and tri s-(m ethylphenyl) phosphate (TMPP).

[0076] 2. Nitrogen: the best known include pure melamine and its derivatives (melamine phosphates and polyphosphates, and melamine cyanurate) and ammonium octamolybdate.

[0077] 3. Metals: the best known include magnesium and aluminium hydroxides.

[0078] 4. Boron: the best known include disodium octaborate, borax, sodium metaborate and zinc borate.

[0079] 5. Carbon: the best known include graphites and expandable graphites.

[0080] 6. Antimony: the best known include antimony oxides.

[0081] The flame-retardant additive is present in the formulation, object of the invention, in amounts ranging between 2% and 50% by weight, preferably between 5% and 15% by weight. The preferred flame-retardant additives are those that implement gas-phase dilution mechanisms, such as metal hydroxides, e.g. Al(0H)3 and Mg(OH)2, and cool the solid phase by means of endothermic reactions, and / or boron compounds, such as colemanite (Ca2BeOir5(H2O)), which also create intumescence following decomposition.

[0082] The bituminous formulation, object of the invention, does not contain flame-retardant additives of the chlorinated paraffin class; these organic compounds, as well as being carcinogenic, are currently classified by ECHA Reach as bioaccumulative, persistent and toxic, and are therefore included in the list of Substances of Very High Concern (SVHC List).

[0083] The bituminous formulation according to the invention can also contain different types of plasticisers, plant-based or synthetic ones, aromatic or paraffin-based, and / or mixtures of multiple types, in percentages ranging between 1% and 20% by weight, preferably between 3% and 10% by weight.

[0084] The preparation of the bituminous formulation, object of the invention, is conducted with conventional techniques and devices, and comprises two steps: a) polymer modification of the bitumen, and optional mixing thereof with at least one filler; b) dispersal of the flame-retardant additive and lightweight aggregate. Based on the previous description, the skilled person will easily realise that the bituminous formulations, according to the invention, use a limited amount of inorganic filler, allowing the production of more lightweight, flame-resistant bituminous waterproofing membranes (densities lower than those of the various traditional formulations with flameretardant additives, as shown in Table 2).

[0085] A second aspect of the invention relates to flame-resistant waterproofing membranes obtained by impregnating a substrate / reinforcement with the bituminous formulation according to the invention. The waterproofing membranes, also objects of the invention, are characterised by masses per unit area lower than 5 kg / m2, typically ranging between 2.5 kg / m2and 4.9 kg / m2(thickness 2.5-5 mm) and fire resistance properties according to UNI CEN / TS 1187, EN 13501- 1 and EN 13501-5.

[0086] The reinforcement / substrate can be of different chemical natures and weights, reinforced or not reinforced, and stabilised with organic and / or inorganic binder.

[0087] The resulting flame-resistant waterproofing membrane has a thickness ranging between 2.5 mm and 5 mm, preferably 4 mm, and can be constructed partly (Figures 2 and 3) or entirely (Figure 4) from the bituminous formulation, according to the invention.

[0088] The fire-resistant waterproofing membrane can have the structures illustrated in Figures 2-4: a) Figure 2: membrane (10) comprises an upper finishing layer (1) overlaid on a layer of conventional bituminous formulation separated by a substrate / reinforcement (4) from a layer of bituminous formulation according to the invention (5), which comprises light weight aggregate (3) and flame-retardant additive (9), and a lower finishing layer (6). b) Figure 3: membrane (10) comprises an upper finishing layer (1) overlaid on a layer of bituminous formulation, according to the invention (2), which comprises lightweight aggregate (3) and flame-retardant additive (9). This layer is separated by a substrate / reinforcement (4) from a layer of conventional bituminous formulation (5) overlaid on a lower finishing layer (6). c) Figure 4: membrane (10) comprises an upper finishing layer (1) overlaid on two layers of bituminous formulation, according to the invention (2), which comprises lightweight aggregate (3) and flame-retardant additive (9). These layers are separated by a substrate / reinforcement (4) and overlaid on a lower finishing layer (6). The waterproofing membranes according to the invention have proved to have better mechanical and flexibility properties and improved temperature sensitivity (Tables 3 and 4) and excellent durability properties (Tables 3 and 4), compared to the traditional bituminous waterproofing membranes present on the market, having the same functions.

[0089] The fire resistance of the waterproofing membranes according to the invention has been evaluated according to the Broof(tl), Broof(t2), Broof(t3) and Broof(t4) test methods for determination of the performance of roofs exposed to external fire, according to UNI CEN / TS 1187 and UNI EN 13501-5 (Table 5).

[0090] Based on the fire reaction test results, the membranes, objects of the invention, belong to Class E, according to UNI EN 13501-1.

[0091] The membranes according to the invention can be applied with a blowtorch or can be self-adhesive.

[0092] The invention is illustrated in greater detail in the following examples.

[0093] PREPARATION OF BITUMINOUS FORMULATION

[0094] The bituminous formulation according to the invention is prepared with conventional techniques and devices, and comprises firstly polymer modification of the bitumen and optional mixing thereof with at least one filler, and subsequently, dispersal of the flame-retardant additive and lightweight aggregate.

[0095] EXAMPLE 1

[0096] The composition of the bituminous formulation, expressed as a percentage by weight, is:

[0097] • industrial bitumen 160 / 220: 70%;

[0098] • plastomeric polymer: 12%;

[0099] • lightweight aggregate consisting of SiCE foam microbeads with a multicellular structure, having a density ranging between 250 and 350 kg / m3and dimensions ranging between 0.25 and 0.50 mm: 10%;

[0100] • flame-retardant additive consisting of colemanite: 8%.

[0101] Table 2 shows the comparison between the physicochemical characteristics of the bituminous formulation of Example 1 and those of the traditional formulations present on the market.

[0102] Figure 5 shows the microscope photo of a traditional formulation (left) compared with that of the bituminous formulation of Example 1 (right). EXAMPLE 2

[0103] The composition of the bituminous formulation, expressed as a percentage by weight, is:

[0104] • industrial bitumen 160 / 220: 70%;

[0105] • plastomeric polymer: 2%;

[0106] • elastomeric polymer: 10%;

[0107] • lightweight aggregate consisting of SiCh foam microbeads with a multicellular structure, having a density ranging between 250 and 350 kg / m3and dimensions ranging between 0.25 and 0.50 mm: 10%;

[0108] • flame-retardant additive consisting of colemanite: 8%.

[0109] Table 2 shows the comparison between the physicochemical characteristics of the bituminous formulation of Example 2 and those of the traditional formulations present on the market.

[0110] EXAMPLE 3

[0111] The composition of the bituminous formulation, expressed as a percentage by weight, is:

[0112] • industrial bitumen 160 / 220: 70%;

[0113] • plastomeric polymer: 10%;

[0114] • inorganic filler consisting of calcium carbonate: 5%;

[0115] • lightweight aggregate consisting of SiCh foam microbeads with a multicellular structure, having a density ranging between 350 and 450 kg / m3and dimensions ranging between 0.10 and 0.30 mm: 10%;

[0116] • flame-retardant additive consisting of colemanite: 5%.

[0117] Table 2 shows the comparison between the physicochemical characteristics of the bituminous formulation of Example 3 and those of the traditional formulations present on the market.

[0118] EXAMPLE 4.

[0119] The composition of the bituminous formulation, expressed as a percentage by weight, is:

[0120] • industrial bitumen 160 / 220: 70%;

[0121] • plastomeric polymer: 10%;

[0122] • lightweight aggregate consisting of expanded perlite, having a density ranging between 50 and 150 kg / m3and dimensions ranging between 0.10 and 1.00 mm:

[0123] • flame-retardant additive consisting of colemanite: 8%.

[0124] Table 2 shows the comparison between the physicochemical characteristics of the bituminous formulation of Example 4 and those of the traditional formulations present on the market.

[0125] EXAMPLE 5.

[0126] The composition of the bituminous formulation, expressed as a percentage by weight, is:

[0127] • industrial bitumen 160 / 220: 70%;

[0128] • plastom eric polymer: 10%; • lightweight aggregate consisting of SiCh foam microbeads with a multicellular structure, having a density ranging between 300 and 400 kg / m3and dimensions ranging between 0.10 and 0.50 mm: 10%;

[0129] • flame-retardant additive consisting of magnesium hydroxide: 10%.

[0130] Table 2 shows the comparison between the physicochemical characteristics of the bituminous formulation of Example 5 and those of the traditional formulations present on the market.

[0131] Table 2. Comparison between the physicochemical characteristics of the traditional bituminous formulations present on the market and the physicochemical characteristics of the bituminous formulations, objects of the invention.

[0132] MEMBRANE

[0133] The flame-resistant waterproofing membrane is obtained by impregnating a reinforcing material with the bituminous formulation, object of the invention, as described in the following examples.

[0134] EXAMPLE 6

[0135] The flame-resistant waterproofing membrane is prepared with the bituminous formulation obtained as described in Example 1, which is used to impregnate a reinforcing material made of continuous-yarn non-woven polyester fabric, stabilised with longitudinal glass yarn, on a conventional production line. The comparison between the mechanical characteristics of the bituminous membranes prepared with the traditional formulation present on the market and the membranes of Example 6, at equal thickness, is shown in Table 3.

[0136] EXAMPLE 7

[0137] The flame-resistant waterproofing membrane is prepared with the bituminous formulation obtained as described in Example 3, which is used to impregnate a reinforcing material made of continuous-yarn non-woven polyester fabric, stabilised with longitudinal glass yarn, on a conventional membrane production line. The mechanical characteristics of the bituminous waterproofing membrane of Example 7 are shown in Table 4.

[0138] EXAMPLE 8

[0139] The flame-resistant waterproofing membrane is prepared with the bituminous formulation of Example 5, which is used to impregnate a reinforcing material made of continuous-yarn non-woven polyester fabric, stabilised with longitudinal glass yarn, on a conventional membrane production line.

[0140] The mechanical characteristics of the waterproofing membrane of Example 8 are shown in Table 4.

[0141] The durability of all the finished products was evaluated by conducting aging tests in a stove for 4 weeks at 70°C, according to EN 1296. A definite improvement in behaviour after aging was observed in the bituminous membrane obtained from the formulations of Example 1 (Table 3) and Examples 3 and 5 (Table 4), indicating its greater durability. Table 3. Comparison between the mechanical characteristics of waterproofing membranes of traditional bituminous formulations present on the market and the mechanical characteristics of the waterproofing membranes of the bituminous formulation of Example 1, at equal thickness.

[0142] Table 4. Mechanical characteristics of waterproofing membranes of the bituminous formulations of

[0143] Examples 7 and 8

[0144] According to the invention, , the cold flexibility performance of the finished products can vary on the basis of the percentage composition of the polymer mix in the bituminous formulation ranging from 0°C to -30°C.

[0145] The finished products, objects of the invention, subjected to the external fire exposure of roofs tests Broof(tl), Broof(t2), Broof(t3), Broof(t4) according to UNI CEN / TS 1187:2012 and UNI EN 13501-5, passed the fire reaction tests and were therefore classified as Class E, according to UNI EN 13501-1.

[0146] The Table shows, by way of example, the values obtained for the Broof(t2) exposure tests on the waterproofing membranes of Examples 6 and 8, according to UNI EN 13501-5. Table 5. Results of the Broof(t2) exposure test on the bituminous waterproofing membranes obtained according to Example 7 and Example 8.

[0147] Table 6 shows, by way of example, the values obtained for the Broof(t4) exposure tests on the waterproofing membrane of Example 6, according to UNI CEN / TS 1187:2012 and UNI EN 13501-5.

[0148] Figure 6 shows a photo of the waterproofing membrane of Example 6 before and after the exposure test.

[0149] Table 6. Results of the Broof(t4) exposure test on the waterproofing membrane of Example 6.

[0150] EXAMPLE 9

[0151] The flame-resistant waterproofing membrane is prepared with the bituminous formulation of Example 1, which is used to impregnate a reinforcing material made of continuous-yarn non-woven polyester fabric, stabilised with longitudinal glass yarn, on a conventional membrane production line. It is then coupled to a further self-adhesive bituminous compound to allow application without the use of a blowtorch.

Claims

CLAIMS1. Bituminous formulations comprising bitumen modified with at least one plastomeric and / or elastomeric polymer, a lightweight aggregate characterised by a density of less than 1 g / cm3, a flame-retardant additive different from halogenated paraffins, and optionally an inorganic filler having a density greater than 1 g / cm3.

2. Bituminous formulations according to claim 1, with a density of less than 0.99 g / cm3.

3. Bituminous formulations according to claim 1 or 2, wherein the bitumen is selected from types 240 / 300, 160 / 220, 70 / 100 and / or 50 / 70.

4. Bituminous formulations according to one or more of claims 1 to 3, wherein the bitumen is present in amounts ranging between 65% and 80% by weight, preferably 70%.

5. Bituminous formulations according to one or more of claims 1 to 4, wherein the plastomeric and elastomeric polymers are selected from isotactic polypropylene, atactic polypropylene, polyethylene, low-density polyethylene, high-density polyethylene, thermoplastic polyolefins, ethylene-propylene copolymers, ethylene vinyl acetate, ethylene butyl acrylate, styrene butadiene styrene, styrene isoprene styrene, styrene ethylene butylene styrene, functionalised polymers such as maleic anhydrides, methacrylic acids and the esters thereof, glycidyl methacrylate, and a-olefin copolymers.

6. Bituminous formulations according to claim 5, wherein the plastomeric and elastomeric polymers are present in amounts ranging between 5% and 20% by weight, preferably between 10% and 15% by weight.

7. Bituminous formulations according to one or more of claims 1 to 6, wherein the lightweight aggregate characterised by a density of less than 1 g / cm3is selected from clays and expanded clays; diatomaceous earths; perlites and expanded perlites having a volumetric density ranging between 50 and 200 kg / cm3and dimensions ranging between 0.05 and 1.00 mm, hollow glass microbeads having a volumetric density ranging between 100 and 550 kg / cm3and dimensions ranging between 0.10 and 1.00 mm, and aluminium silicate cenospheres having a volumetric density ranging between 600 kg / cm3and 850 g / cm3and dimensions ranging between 5 pm and 300 pm.

8. Bituminous formulations according to claim 7, wherein the lightweight aggregate consists of SiCh foam microbeads having a multicellular structure with a density ranging between 250 and 350 kg / m3and dimensions ranging between 0.25 and 0.50 mm.

9. Bituminous formulations according to claims 7 to 8, wherein the lightweightaggregate is present in amounts ranging between 2% and 15% in weight, preferably between 5% and 10% by weight.

10. Bituminous formulations according to one or more of claims 1 to 9, wherein the flame-retardant additive is selected from red phosphorus, ammonium polyphosphate, aluminium phosphite, tris (2-chloroethyl) phosphate, tri s-( 1,3 -di chloroisopropyl) phosphate, (triphenyl)phosphate, tri s-(m ethylphenyl) phosphate, pure melamine, melamine phosphates and polyphosphates, melamine cyanurate, ammonium octamolybdate, magnesium and aluminium hydroxides, colemanite, disodium octaborate, borax, sodium metaborate, zinc borate, graphites and expandable graphites, and antimony oxides.

11. Bituminous formulations according to claim 10, wherein the flame-retardant additive is selected from Al(0H)3, Mg(OH)2 and colemanite (Ca2BeOir5(H2O)).

12. Bituminous formulations according to claim 10 or 11, wherein the flame-retardant additive is present in amounts ranging between 2% and 15% by weight, preferably between 5% and 15% by weight.

13. Bituminous formulations according to one or more of claims 1 to 12, wherein the fillers are selected from different types of carbonates such as, slaked lime, talc, cement and their derivatives.

14. Bituminous formulations according to claim 13, wherein the fillers are present in amounts ranging between 0% and 15% in weight, preferably between 0% and 6% by weight.

15. Flame-resistant bituminous waterproofing membranes obtained by impregnating a substrate / reinforcement with the bituminous formulations of claims 1 to 14.

16. Bituminous waterproofing membranes according to claim 15, characterised by a thickness ranging between 2.5 mm and 5 mm, preferably 4 mm.

17. Bituminous waterproofing membranes according to claims 15 and 16, characterised by masses per unit area lower than 5 kg / m2, typically ranging between 2.5 kg / m2and 4.9