Fireproofing of a compartment containing electrical cables

Abstract

The invention relates to a fire-resistant element comprising a compartment containing electrical cables; wherein said compartment has walls delimiting an internal space within said compartment and an external space within said compartment, these walls comprising at least one layer of a flammable material and at least one layer based on a geopolymer material. Figure for the abstract: Figure 1

Description

Title of the invention: Fireproofing of a compartment containing electrical cables

[0001] The present invention relates to the field of fireproofing. It is more specifically concerned with the protection against fire of closed enclosures, such as closed electrical boxes, in particular of the type of electrical cabinets and junction boxes commonly used in buildings, for example, and not exclusively, in residential buildings and premises intended to receive the public.

[0002] The so-called "fireproofing" and "fire protection" properties sought in the context of the present invention are fire resistance properties, which prevent a substrate from burning under fire conditions, thus making it possible in particular to inhibit the spread of fire.

[0003] Historically, closed box type devices containing electrical cables, such as electrical cabinets, have mainly been made of metal. The trend has been to gradually replace metal, an electrical conductor, with plastic materials, for example PVC, with insulating properties, in order to avoid the electrical risks linked to the use of metal, particularly for end users.

[0004] However, plastic materials (PVC or other) turn out to be most of the time - if not systematically - a combustible material capable of catching fire easily and acting as a fire propagator in fire conditions, which brings to light another significant risk, which has however rarely been taken into consideration in the past.

[0005] Among the rare documents addressing the question of fire protection of closed boxes such as electrical cabinets made from plastic materials, we can cite application US 2019 / 341758 which recommends the use of a layer of intumescent material on the surface of the plastic.

[0006] An aim of the present invention is to provide an electrical box (in particular an electrical cabinet) whose walls are made from a flammable material, typically plastic, but which nevertheless has good fire resistance properties, preferably while also limiting the generation of smoke.

[0007] To this end, it is proposed according to the present invention to provide all or part of the surface of the walls of the electrical box with a coating based on a geopolymer material, which proves to be suitable for ensuring the protection of the flammable material constituting the wall.

[0008] More specifically, according to a first aspect, the present invention relates to a fireproof element comprising a compartment containing electric cables; wherein said compartment comprises walls delimiting a space internal to said compartment and a space external to said compartment, these walls comprising at least one layer of a flammable material and at least one layer based on a geopolymer material.

[0009] The layer of flammable material is typically a layer of plastic, typically a layer of PVC, but the use of other flammable materials, such as wood for example, is not excluded according to the invention.

[0010] According to an interesting embodiment, the layer based on geopolymer material is located between the cables contained in the internal space of the compartment and the layer of flammable material. According to this embodiment, the layer based on geopolymer material provides protection for the layer of flammable material against a flame located within the internal space of the compartment, typically a flame emanating from a fire starting from at least one of the electrical cables contained in the internal space (or alternatively from an electric arc resulting from a short circuit appearing in the compartment at the level of the connections). This embodiment thus makes it possible to confine the fire (and advantageously any smoke) within the internal space of the compartment. In general, mechanical integrity of the compartment is maintained at the same time.

[0011] According to a first possible variant of the embodiment defined in the preceding paragraph, the layer based on geopolymer material can advantageously cover the surface of the internal space of the compartment (hereinafter referred to as the “internal surface” of the compartment), preferably the entirety of said internal surface of the internal space of the compartment.

[0012] According to another variant, the layer based on geopolymer material located between the cables contained in the internal space of the compartment and the layer of flammable material is not present on the internal surface of the compartment and a masking layer is applied between the layer based on geopolymer material and the cables contained in the internal space of the compartment.

[0013] According to another possible embodiment, the layer based on geopolymer material is located between the layer of flammable material and the space external to the compartment. According to this embodiment, the layer based on geopolymer material provides protection for the layer of flammable material against a flame located outside the compartment. This embodiment thus makes it possible to confine the fire (and advantageously any smoke) outside the compartment and to protect the integrity of the electrical cables contained in its internal space. In general, the mechanical integrity of the compartment is maintained at the same time.

[0014] According to a first possible variant of the embodiment defined in the preceding paragraph, the layer based on geopolymer material can advantageously cover the external surface of the compartment, preferably the entirety of said external surface of the compartment.

[0015] According to another variant, the layer based on geopolymer material is not directly present on the internal surface of the compartment and a masking layer is applied between the layer based on geopolymer material and the external space of the compartment.

[0016] When a masking layer is used (according to the variant of the second embodiment described in the previous paragraph or according to the second variant of the first embodiment described above), the layer based on geopolymer material is sandwiched between said masking layer and the layer of flammable material.

[0017] According to a particular embodiment, the aforementioned masking layer may be a second layer of flammable material. In this case, which constitutes yet another particular possible embodiment of the invention, the layer based on geopolymer material is located between a first layer of flammable material (on the side of the internal space of the compartment) and a second layer of flammable material, of composition identical or not to that of the first layer of flammable material. This specific embodiment combines the advantages of the preceding embodiments and makes it possible both (i) to contain the start of a fire within the internal space of the compartment; and (ii) to protect the cables contained in the internal space in the event of a fire in the space external to said compartment.

[0018] Whatever the embodiment, the layer based on geopolymer material used according to the invention is advantageously obtained by applying, on the layer based on flammable material to be protected, a substrate impregnated with a geopolymer composition then hardening of the geopolymer composition. The substrate used can for example be chosen from cardboard, paper or wadding or possibly another cellulosic substrate.

[0019] As used in the present description, the term "geopolymer material" designates a solid obtained by hardening a geopolymer composition. The method of the invention generally comprises, following the application of the geopolymer composition, a step of converting the geopolymer composition (initially liquid) into a geopolymer material, in particular by drying.

[0020] In the context of the work which led to the present invention, the inventors have now shown that the fireproof compartments as obtained according to the invention have very interesting fire resistance properties, which makes them, for example, particularly well suited as electrical cabinets or distribution boxes. rivations in particular in residential accommodation or more generally inside buildings intended to receive the public. These particular applications of the aforementioned fireproof elements constitute, according to yet another aspect, another object of the present invention.

[0021] Various aspects and possible embodiments of the invention are described in more detail below.

[0022] The geopolymer material and the geopolymer composition making it possible to obtain it

[0023] For the purposes of the present description, the term “geopolymer material” designates a solid material comprising silicon (Si), aluminum (Al), oxygen (O) and at least one element chosen from potassium (K), sodium (Na), lithium (Li), cesium (Cs) and calcium (Ca), and preferably chosen from potassium (K), and sodium (Na).

[0024] The geopolymer material may in particular be an alumino-silicate geopolymer material. Where appropriate, this aluminosilicate geopolymer material may be chosen from poly(sialates) corresponding to the formula (I) Mn(-Si-O-Al-O-)n [(M)-PS] and having a Si / Al molar ratio equal to 1, poly(sialate-siloxos) corresponding to the formula (II) Mn(-Si-O-Al-O-Si-O-)n [(M)-PPS] and having a Si / Al molar ratio equal to 2, poly(sialate-disiloxos) corresponding to the formula (III) Mn(-Si-O-Al-O-Si-O-Si-O)n [(M)-PSDS] and having a Si / Al molar ratio equal to 3, and other poly(sialates) with a Si / Al ratio > 3, the aforementioned poly(sialates) comprising an alkali cation M chosen from K, Na, Li, Cs and one of their mixtures, and n denotes the degree of polymerization.

[0025] The geopolymer material is obtained from a geopolymer composition, generally by drying, geopolymerization and / or polycondensation of said geopolymer composition (processes referred to herein as "curing" of the geopolymer composition).

[0026] A “geopolymer composition”, as used herein, is a composition, generally liquid, capable of forming a solid geopolymer material upon hardening. The ingredients of the geopolymer composition may therefore undergo polycondensation to form said geopolymer material.

[0027] The formation of the geopolymer material from the geopolymer composition is carried out by an internal reaction and is generally not the result of simple drying, as is generally the case for binders based on alkali silicates. Indeed, geopolymer materials result from a mineral polycondensation reaction by alkaline activation, called geosynthesis, as opposed to traditional hydraulic binders in which hardening is the result of hydration of calcium aluminates and calcium silicates.

[0028] The geopolymer composition used in the context of the present invention is preferably an aluminosilicate geopolymer composition.

[0029] The geopolymer composition of the invention is particularly preferably a geopolymer composition comprising water, silicon (Si), aluminum (Al), oxygen (O), and at least one element chosen from potassium (K), sodium (Na), lithium (Li), cesium (Cs), and calcium (Ca), and preferably chosen from potassium (K) and sodium (Na).

[0030] The geopolymer composition may in particular comprise at least one aluminosilicate, at least one alkali silicate, water, and optionally an alkaline base.

[0031] Aluminosilicate

[0032] The aluminosilicate(s) present in the geopolymer composition may be chosen from metakaolins (i.e. calcined kaolins), fly ash (well known by the Anglicism "fly ash"), blast furnace slag (well known by the Anglicism "blast furnace slag"), swelling clays such as bentonite, calcined clays, any type of compound comprising aluminum and silica fume, zeolites, and mixtures thereof.

[0033] Among these compounds, metakaolins are preferred, in particular those marketed by the company Imérys.

[0034] In the invention, the expression "metakaolin" means a calcined kaolin or a dehydroxylated aluminosilicate. It is preferably obtained by dehydration of a kaolin or a kaolinite.

[0035] The geopolymer composition may comprise from 5 to 50% by weight approximately of aluminosilicate, and preferably from 10 to 35% by weight approximately of aluminosilicate, relative to the total weight of the geopolymer composition.

[0036] The aluminosilicate content relative to the weight of the dry matter of the geopolymer composition is typically between 10 and 50%, for example between 15 and 30%.

[0037] Preferably, the geopolymer composition used according to the present invention comprises a mixture of two distinct aluminosilicates, namely at least one first aluminosilicate and at least one second aluminosilicate distinct from the first aluminosilicate.

[0038] Preferably, the geopolymer composition comprises two distinct calcined kaolins, having different calcination temperatures, preferably a first metakaolin chosen from kaolins calcined at a temperature Tci of at least approximately 650°C, and a second metakaolin chosen from kaolins calcined at a temperature Tc2 such that Tc2 - Tci > 100°C.

[0039] According to a particularly preferred embodiment of the invention, the geopolymer composition comprises a first metakaolin chosen from kaolins calcined at a temperature Tci of at least approximately 650°C, and a second metakaolin chosen from kaolins calcined at a temperature Tc2 such that Tc2 - Tci > 100°C, at at least one first alkali silicate, water, and optionally an alkali base. The geopolymer composition can then exhibit improved mechanical properties, particularly in terms of flexibility and durability, while ensuring good reaction and fire resistance properties.

[0040] According to one embodiment of the invention, the first metakaolin is a kaolin calcined at a temperature Tcl of at least approximately 700°C, and preferably at least approximately 725°C.

[0041] According to a preferred embodiment of the invention, the first metakaolin is a kaolin calcined at a temperature Tcl of at most approximately 875°C, and preferably at most approximately 825°C.

[0042] The first metakaolin may comprise at least about 20 mol%, and preferably at least about 30 mol% of aluminum oxide (A12O3), relative to the total number of moles of the first metakaolin.

[0043] The first metakaolin may comprise at most approximately 60 mol%, and preferably at most approximately 50 mol% of aluminum oxide (A12O3), relative to the total number of moles of the first metakaolin.

[0044] The first metakaolin may comprise at least about 35 mol%, and preferably at least about 45 mol% of silicon oxide (SiO2), relative to the total number of moles of the first metakaolin.

[0045] The first metakaolin may comprise at most approximately 75 mol%, and preferably at most approximately 65 mol% of silicon oxide (SiO2), relative to the total number of moles of the first metakaolin.

[0046] As examples of first metakaolin, we can cite the metakaolins sold by the company Imérys, in particular that marketed under the reference PoleStar® 450.

[0047] The first metakaolin may be chosen from calcined kaolins with Tcl as defined above, for at least approximately 1 min, preferably for at least approximately 10 min, particularly preferably for a duration ranging from approximately 30 min to 8 h, and more particularly preferably for a duration ranging from approximately 2 h to 6 h.

[0048] The second metakaolin is preferably chosen from kaolins calcined at a temperature Tc2 such that Tc2 - Tcl > approximately 150°C, particularly preferably such that Tc2 - Tcl > approximately 200°C, and more particularly preferably such that Tc2 - Tcl > approximately 250°C.

[0049] According to one embodiment of the invention, the second metakaolin is a kaolin calcined at a temperature Tc2 of at least approximately 800°C, preferably at least approximately 850°C, and particularly preferably at least approximately 900°C.

[0050] According to a preferred embodiment of the invention, the second metakaolin is a kaolin calcined at a temperature Tc2 of at most approximately 1200°C, and preferably of at least plus approximately 1150°C.

[0051] The second metakaolin may comprise at least about 20 mol%, and preferably at least about 30 mol% of aluminum oxide (A12O3), relative to the total number of moles of the second metakaolin.

[0052] The second metakaolin may comprise at most approximately 60 mol%, and preferably at most approximately 50 mol% of aluminum oxide (A12O3), relative to the total number of moles of the second metakaolin.

[0053] The second metakaolin may comprise at least about 35 mol%, and preferably at least about 45 mol% of silicon oxide (SiO2), relative to the total number of moles of the second metakaolin.

[0054] The second metakaolin may comprise at most approximately 75 mol%, and preferably at most approximately 65 mol% of silicon oxide (SiO2), relative to the total number of moles of the second metakaolin.

[0055] As examples of second metakaolin, we can cite the metakaolins sold by the company Imérys, in particular that marketed under the reference PoleStar® 200R.

[0056] The second metakaolin may be chosen from calcined kaolins at Tc2 as defined in the invention, for at least approximately 1 min, preferably for at least approximately 5 min, particularly preferably for a duration ranging from approximately 10 min to 2 h, and more particularly preferably for a duration ranging from approximately 15 min to 1 h.

[0057] The mass ratio [first metakaolin / second metakaolin] corresponding to the total mass of first metakaolin in the geopolymer composition relative to the total mass of second metakaolin in the geopolymer composition preferably ranges from about 0.1:1 to about 2:1, particularly preferably from about 0.5:1 to about 1.0:1, and more particularly preferably is about 1:1.

[0058] The geopolymer composition may comprise from 5 to 50% by weight approximately, and preferably from 10 to 35% by weight approximately of first and second metakaolins, relative to the total weight of the geopolymer composition.

[0059] Alkali silicate

[0060] The alkali silicate(s) present in the geopolymer composition may be chosen from sodium silicates, potassium silicates, and mixtures thereof.

[0061] Alkali silicates marketed by Silmaco or PQ corporation are preferred.

[0062] Advantageously, the geopolymer composition used according to the invention comprises at least one sodium silicate.

[0063] An alkali silicate useful according to the invention may have a SiO2 / M2O molar ratio ranging from about 1.1 to 35, preferably from about 1.3 to 10, and particularly preferably from about 1.4 to 5, with M being a sodium or potassium, and preferably one sodium atom.

[0064] The geopolymer composition may comprise from 5 to 80% by weight approximately, and preferably from 10 to 50% by weight approximately of alkali silicate, relative to the total weight of the geopolymer composition.

[0065] According to an interesting embodiment, the geopolymer composition used according to the invention comprises an alkali silicate of the aforementioned type, preferably a sodium silicate, and two distinct aluminosilicates which are preferably two distinct metakaolins of the aforementioned type, with an alkali silicate content which is preferably between 70% and 90%, preferably between 75% and 85% (for example of the order of 80%) relative to the total mass of silicate and aluminosilicates. The aluminosilicate content is between 10% and 70%, preferably between 15% and 25% (for example of the order of 20%) relative to the total mass of silicate and aluminosilicates.

[0066] The geopolymer composition may optionally comprise several alkali silicates, namely at least one alkali silicate of the aforementioned type and a second alkali silicate different from the first.

[0067] The second alkali silicate may be chosen from sodium silicates, potassium silicates, and one of their mixtures. The alkali silicates marketed by the company Silmaco or by the company PQ Corporation are preferred. The second alkali silicate is preferably a sodium silicate.

[0068] The first and second alkali silicates may respectively have molar ratios SiO2 / M2O and SiO2 / M'2O such that M and M', which are identical, are chosen from a sodium atom and a potassium atom, and preferably a sodium atom, and said ratios have different values, preferably values ​​such that their difference is at least 0.3, particularly preferably such that their difference is at least 0.5, and more particularly preferably such that their difference is at least 1.0.

[0069] According to a possible embodiment of the invention, the geopolymer composition comprises: - a first alkali silicate having a SiO2 / M2O molar ratio ranging from approximately 1.5 to 2.6, and - a second alkali silicate having a SiO2 / M'2O molar ratio greater than 2.6, preferably ranging from approximately 2.8 to 4.5, and particularly preferably ranging from approximately 3.0 to 4.0, it being understood that M' is identical to M.

[0070] The geopolymer composition may comprise from about 10 to 60% by weight, and preferably from about 20 to 50% by weight of first and second alkali silicates, relative to the total weight of the geopolymer composition.

[0071] The mass ratio [first alkali silicate / second alkali silicate] in the com geopolymer position preferably ranges from 0.5 to 2.5, and particularly preferably from 0.8 to 2.0.

[0072] The alkaline base

[0073] The alkaline base typically used in the geopolymer composition useful according to the invention may for example be sodium hydroxide, or potassium hydroxide, and preferably sodium hydroxide.

[0074] The geopolymer composition may be free of alkaline base. This thus makes it possible to improve the handling of the geopolymer composition, in particular during application to the substrate.

[0075] Water content

[0076] The mass ratio of solids to water in said geopolymer composition determines the solidification (setting) kinetics of the composition, as well as the viscosity of the geopolymer composition during its application.

[0077] The geopolymer composition may comprise from 35% to 80% by weight approximately, and particularly preferably from 40% to 70% by weight approximately, of solid materials (alkali silicate(s), aluminosilicate(s) and alkaline base), relative to the total weight of said geopolymer composition.

[0078] Optional additives

[0079] The geopolymer composition useful according to the invention may optionally comprise one or more additives chosen from: - at least one colorant, - mineral fibers, in particular chosen from alumina fibers, - a polymer structure additive, in particular chosen from polyolefin fibers such as polypropylene fibers, high density polyethylene (HDPE), aramids, and technical glass fibers coated with silicone or an organic polymer of the polyethylene type; a styrene-butadiene copolymer (SBR); a styrene-butadiene-ethylene copolymer (EBS); derivatives of styrene-ethylene copolymers, in particular those marketed by Kraton such as a styrene-ethylene-butylene-styrene copolymer (SEBS), a styrene-butadiene-styrene copolymer (SBS), a styrene-isoprene-styrene copolymer (SIS), a styrene-propylene-ethylene copolymer (EPS) or a styrene-ethylene-propylene-styrene copolymer (SEPS); an ethylene vinyl acetate copolymer (EVA), a crosslinked polyorganosiloxane (egusing a peroxide); polyethylene possibly in powder form; lignosulfonates; cellulose acetate; other cellulose derivatives; a low viscosity silicone oil (eg of the order of 12500 cPo); and a polyethylene oil, . - a compound accelerating the setting in mass, notably chosen from aluminum sulfate, alums (eg double aluminum and potassium sulfate), chloride calcium, calcium sulfate, hydrated calcium sulfate, sodium aluminate, sodium carbonate, sodium chloride, sodium silicate, sodium sulfate, iron (III) chloride, and sodium lignosulfonates, - a solidification retarding agent, in particular chosen from ammonium, alkali metals, alkaline earth metals, borax, lignosulfonates and in particular metal salts of calcium lignosulfonates, celluloses such as carboxymethyl hydroethyl cellulose, sulfoalkylated lignins such as, for example, sulfomethylated lignin, hydroxycarboxylic acids, copolymers of salts of 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid or maleic acid, and saturated salts, - an inert filler, notably chosen from talc, micas, dehydrated clays, and calcium carbonate, - a starch, - a starch plasticizer, in particular chosen from a metal stearate, a polyethylene glycol, an ethylene glycol, a polyol such as glycerol, sorbitol, mannitol, maltitol, xylitol or an oligomer of one of these polyols, a sucrose such as glucose or fructose, a plasticizer containing amide groups, and any type of plasticizer based on modified polysaccharide(s), - a cellulose derivative, - an expanded carbon material such as expanded graphite.

[0080] When a colorant is present, it is preferably a colorant that is liquid at room temperature (i.e. 18-25°C).

[0081] The geopolymer composition may comprise from 0.01 to 15% by weight approximately of additive(s), and preferably from 0.5 to 8% by weight approximately of additive(s), relative to the total weight of the geopolymer composition.

[0082] Preparation of the geopolymer composition

[0083] A geopolymer composition useful according to the invention can typically be prepared according to a step (E) of mixing the aluminosilicate, or the mixture of aluminosilicates when several aluminosilicates are used, with the alkali silicate, or the mixture of alkali silicates where appropriate, water, and optionally the alkaline base and / or the additives.

[0084] This mixing step is generally carried out at a high pH, ​​in particular varying from 10 to 13.

[0085] This mixing step preferably comprises the following sub-steps: (Ei) preparing an aqueous solution of a first alkali silicate; and (E2) mixing a first aluminosilicate in powder form with the aqueous alkali silicate solution prepared in sub-step (Ei).

[0086] The aqueous solution of the first alkali silicate can be prepared by mixing silicon dioxide SiO2 or an alkali silicate with a base MOH in which M is K or Na.

[0087] Silicon dioxide SiO2 can be chosen from silica fume (i.e. pyrogenic silica), quartz, and mixtures thereof.

[0088] Sub-step (EJ) can be carried out by dissolving the base in water, resulting in the release of heat (exothermic reaction), and then adding the silica (or alkali silicate). The heat released then accelerates the dissolution of the silica (or alkali silicate) during sub-step (EJ), and of the first aluminosilicate during sub-step (E2).

[0089] When a second aluminosilicate and / or a second alkali silicate is used, step (E) of preparing the geopolymer composition may comprise mixing said first aluminosilicate and optionally said second aluminosilicate, with said first alkali silicate, optionally said second alkali silicate, water, and optionally the alkali base.

[0090] Step (E) preferably comprises mixing the first and second meta-takaolins, with the first alkali silicate and optionally the second alkali silicate, water, and optionally an alkali base.

[0091] According to a preferred embodiment, step (E) comprises the following sub-steps: (Ea) mixing the first and second alkali silicates, in particular with stirring; (Eb) possible addition of an alkaline base, in particular while maintaining stirring; and (Ec) the addition of the first and second metakaolins, in particular while maintaining stirring.

[0092] At the end of step (E), in particular at the end of sub-step (E2) or (E c) when they are implemented, a fluid and homogeneous solution is preferably obtained.

[0093] At the end of step (E), the geopolymer composition may comprise from 35% to 80% by weight approximately, and particularly preferably from 40% to 70% by weight approximately, of solid materials (alkali silicate(s), aluminosilicate(s) and alkaline base), relative to the total weight of said geopolymer composition.

[0094] Such a mass ratio makes it possible to have a geopolymer composition that is fluid enough to allow its handling, and whose solidification kinetics are slow enough to allow application to the substrate.

[0095] The solids / water mass ratio in said geopolymer composition can make it possible to determine the solidification kinetics of said geopolymer composition.

[0096] After step (E) of preparing the geopolymer composition, and before its impregnation on the fibrous material, the geopolymer composition may optionally be heated, in particular to a temperature ranging from approximately 55°C to 95°C, for example between approximately 70°C and 90°C. This heating can facilitate the impregnation stage. If necessary, it is nevertheless advisable to control the heating conditions, which, if too drastic, can induce polymerization and solidification phenomena.

[0097] The layer(s) of flammable material of the compartment walls

[0098] The flammable material which constitutes the layer(s) of flammable material of the compartment advantageously comprises at least one polymer chosen from PVC and polyolefins such as, for example, polyethylene (PE) and polypropylene (PP). According to an advantageous embodiment, this polymer is PVC and the compartment then comprises at least one PVC-based layer.

[0099] The masking layer of the compartment walls (optional)

[0100] When a masking layer is present on the external or internal surface of the compartment, in order to mask the geopolymer-based layer, this masking layer may be a layer of flammable material of the aforementioned type, or alternatively a layer of paint or varnish, preferably aqueous-based (the layer based on geopolymer material proves to constitute an excellent bonding layer for aqueous compositions).

[0101] The following Example, given with reference to the attached Figures, illustrates the invention. DESCRIPTION OF FIGURES

[0102] The attached figures illustrate possible embodiments of the invention. These are schematic representations where the scales are not respected.

[0103] [Fig. 1][Fig. 1] is a sectional view of a fireproof element according to the invention consisting of a single compartment 1 whose walls define an internal space 10 and an external space 20. The walls of the compartment are constituted by a layer of polymer 30 (typically a PVC casing), covered over the entire internal face of the compartment by a layer 40 based on geopolymer.

[0104] The layer 40 is typically obtained by applying to the internal surface of the compartment 1 a cardboard-type substrate impregnated with liquid geopolymer composition, then drying the deposit produced;

[0105] [Fig.2][Fig.2] is a sectional view of a fireproof element according to the invention consisting of a single compartment 101 whose walls define an internal space 110 and an external space 120. The walls of the compartment are constituted by a layer of polymer 130 (typically a PVC casing), covered over the entire external face of the compartment by a layer 40 based on geopolymer.

[0106] The layer 40 is typically obtained by applying to the external surface of the compartment 101 a cardboard-type substrate impregnated with geopolymer composition. liquid, then drying of the deposit made

[0107] [Fig.3][Fig.3] is a sectional view of a fireproof element according to the invention consisting of a single compartment 201 whose walls define an internal space 210 and an external space 220. The walls of the compartment are constituted by a first layer of polymer 230 (typically a PVC casing), a layer 240 based on geopolymer and a second layer of polymer 250 (typically a PVC identical or not to that of the first layer).

[0108] The structure of Figure (3) is typically obtained by producing the layer 240 by applying to the layer 230 (which then constitutes the internal surface of the compartment 201) a cardboard-type substrate impregnated with liquid geopolymer composition, drying the deposit produced and then applying the layer 250. This embodiment is rather recommended when the priority is to confine the outbreaks of fires starting within the internal space 210.

[0109] Alternatively, the structure of [Fig. 3] can be obtained by first applying a cardboard-type substrate impregnated with liquid geopolymer composition to the layer 250 (which then constitutes the external surface of the compartment 201), then drying the deposit made to obtain the layer 240 and then applying the layer 230 to the layer 240 made. This second embodiment is rather recommended when the priority is to protect the internal space 210 of the fire compartment in the external zone 220.

[0110] EXAMPLE

[0111] A geopolymer composition was prepared from a mixture containing by mass: 78% sodium silicate 11% of a PoleStar® 450 metakaolin 11% of a PoleStar® 200R metakaolin.

[0112] The composition obtained was impregnated on cardboard then applied to the internal walls of a PVC box according to the method illustrated in [Fig.l] and the internal space of which was crossed by a cable.

[0113] The protected box thus obtained was tested under the conditions of the standard IEC / 60332-1-2 (2015) by applying a flame in the internal space of the box; the cable allows the box to be held in place during the test.

[0114] For comparison, the same test was carried out with a bare PVC box, not covered by the geopolymer-based layer (control box).

[0115] At the end of the tests, the control box underwent total combustion with total melting of the PVC and complete flow well before the end of the test, whereas the box protected according to the invention was not consumed, with a fire contained in the box which remained in place from the beginning to the end of the test.

Claims

Claims

1. Fireproof element comprising a compartment (1; 101; 201) containing electric cables; wherein said compartment comprises walls delimiting a space internal to said compartment and a space external to said compartment, these walls comprising at least one layer (30; 130; 230, 250) of a flammable material and at least one layer based on a geopolymer material (40; 140; 240).

2. A flame retardant element according to claim 1, wherein the layer of flammable material (30; 130; 230, 250) is a layer of plastic material, typically a layer of PVC.

3. A fireproof element according to claim 1 or 2; wherein the layer based on geopolymer material (40) is located between the cables contained in the internal space of the compartment and the layer of flammable material

4. A fireproof element according to claim 1 or 2; wherein the geopolymer material-based layer (140) is located between the flammable material layer and the space external to the compartment

5. Fireproof element according to one of claims 1 to 4; wherein the layer based on geopolymer material (240) is located between a first layer of flammable material (on the side of the internal space of the compartment) and a second layer of flammable material, of composition identical or not to that of the first layer of flammable material

6. Fireproof element according to one of claims 1 to 5, wherein the geopolymer composition comprises at least one aluminosilicate, at least one alkali silicate, water, and optionally an alkaline base.

7. A fireproofing element according to claim 6, wherein the geopolymer composition comprises a mixture of two distinct aluminosilicates, namely at least one first aluminosilicate and at least one second aluminosilicate distinct from the first aluminosilicate.

8. A fireproofing element according to claim 7, wherein the first aluminosilicate is a first metakaolin selected from kaolins calcined at a temperature Tci of at least about 650°C, and the second aluminosilicate is a second metakaolin selected from kaolins calcined at a temperature Tc2 such that Tc2 - Tcl > 100°C.

9. A fireproofing element according to one of claims 6 to 8 wherein the alkali silicate is a sodium silicate.

10. Use of a flame-retardant element according to one of the claims previous ones, as an electrical cabinet or junction box, in particular in a residential dwelling or in a building intended to receive the public.

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