WO2023111423A1 - Protection of stripped connections of fire-retarding and/or fire-resistant wires and cables - Google Patents

Abstract

The present invention relates to a method for protecting an electrical wire or cable (10) from fire, comprising: - at least one elongate electrically conductive element (20); - at least one layer of an inflammable material (30) encircling said elongate electrically conductive element; and - a layer (40) of fire-retarding and/or fire-resistant coating encircling said inflammable material but not covering a surface (50) of said inflammable material, wherein said method comprises a step (e) in which a geopolymer composition or a silicate composition is applied to said surface (50) of said inflammable material, whereby a coating (60) is obtained on the surface. The invention also relates to electrical wires and cables obtained using this method.

Description

Description

Title of the invention: Protection of bare connections of fire resistant and/or retardant wires and cables

The present invention relates to the field of retardant and/or fire-resistant wires and cables. The invention relates more specifically to a method for improving the fire resistance of installations comprising wires and/or cables provided with a fireproof coating.

[0002] The invention applies typically, but not exclusively, to wires and cables intended for the transport of energy such as retardant and/or fire-resistant electric safety cables, in particular halogen-free, capable of operating for a given period of time under fire conditions without being a fire propagator or a significant smoke generator. These safety cables are in particular low voltage power transmission cables (in particular from 0.1 to 1 kV).

[0003] To improve the fire resistance of electrical wires and cables, many solutions have been proposed, which conventionally implement at least one protective coating surrounding underlying layers of the wire or cable which are based on materials flammable. This protective coating is intended to protect these flammable materials when the wire or cable is subjected to the conditions of a fire. The flammable materials protected by these layers are, for example, the constituents of at least one insulating layer of the cable, which is typically based on a thermoplastic such as polyethylene, polypropylene or PVC, which are, in themselves, materials which ignite very easily when they come into contact with a source of fire, such as a flame, a point of overheating or a spark.

[0004] The protective layers which are employed to prevent the ignition of this type of flammable material can vary to quite a large extent. These protective layers have the common effect that they make it possible to inhibit or at least to reduce in a more or less pronounced way the ignition of the flammable material when the protective layer is interposed between the material to be protected and the source of the fire. . Effective protective layers are used in particular in so-called "LFHC" wires and cables (for English: “Low Fire Hazard Cables”) which include, for example, polymer materials, chosen in particular from olefin homopolymers or copolymers, including or not including flame retardant fillers of the aluminum hydroxide Al2(OH)s type, magnesium hydroxide Mg(OH )2, chalk or combinations of these fillers. More specifically, it has been described, in particular in application EP 3670471, the use of particularly effective layers, based on geopolymers.

However, whatever the intrinsic effectiveness of the protective layers used in cables of the aforementioned type, these cables suffer, in practice, from the same defect that the inventors have now brought to light in the context of the present invention. .

[0006] More specifically, it turns out that, to be electrically connected to a device such as an electrical cabinet, a wire or cable covered with layers, in particular insulating and fire-protective, is generally bare at the level of at least one of its end portions. When the wire is stripped in this way to allow the electrical connection, the flammable material, which is protected by the fireproof protective layer over the entire rest of the length of the wire or cable, is partially exposed at the level of the terminal portion. naked. The flammable material appears on its edge and it is not protected at this lateral level by the protective layer which only surrounds it longitudinally.

[0007] As part of the work that led to the present invention, the inventors have now brought to light that this partial exposure of the flammable material on its side edge constitutes a more than notable weak point in the fire protection. While it is generally neglected because it only corresponds to a minimal surface portion of the flammable material, it turns out that the bare surface on the edge is suitable for initiating a fire outbreak, and even for spread the fire along the cable much further than the source of the initial fire. Once the flammable material induces a fire outbreak, the protective layer vis-à-vis the fire even tends to channel the spread of the fire under said layer along the cable.

[0008] In other words, simply because of its stripping at one of its end portions, which is systematic, for example at the level of cabinets electricity, a wire or cable, even qualified as LFHC type and provided with the most effective protective coating possible, can in fact prove to be a vector for the spread of fire within a building, which constitutes a major defect in the fire protection.

[0009] More generally, and even in the absence of stripping of the conductor it contains, a cable comprising a flammable material covered by a fire protection layer systematically has at its ends a zone of flammable material appearing on its edge at the level of the section of the cable and which is therefore not covered by the protective layer on this section, which again constitutes a potential fire starting point and makes the cable a possible vector of fire propagation.

An object of the present invention is to provide a method for improving the efficiency of cables and wires provided with a fireproof coating, avoiding the aforementioned problems at their terminal portions, in particular at the level of terminal portions. stripped intended to ensure an electrical connection of the wire or cable, in particular with an electrical device such as an electrical cabinet. In this context, the invention has the particular objective of improving the safety of electrical installations using wires and cables, of the LFHC type for example, connected to electrical cabinets.

To this end, the present invention proposes to protect the surfaces of flammable materials which are exposed to fire at the terminal portions of the wire or cable by means of a geopolymer or silicate coating.

More specifically, according to a first aspect, the subject of the present invention is a process for the protection against fire of an electric cable or wire comprising:

- at least one elongated electrically conductive element;

- at least one layer of a flammable material surrounding said elongated electrically conductive element; And

- a layer of fire-retardant and/or fire-resistant coating surrounding said flammable material but not covering said coating at a surface of said flammable material, wherein said method comprises a step (e) in which a composition geopolymer or silicate composition is applied to said surface of said flammable material.

In the method of the invention, the electric cable or wire most often has a terminal zone where the elongated electrically conductive element is stripped in order to ensure its electrical connection with an electrical termination of an electrical device. In this case, in step (e) the surface of the flammable material on which the geopolymer composition or the silicate composition is applied comprises or is a surface made accessible by stripping, and advantageously it comprises the entire surface of the material flammable made accessible by stripping.

The exact nature of the electrical device to which the electrical cable or wire is connected can vary to a large extent, it being understood that the invention is preferably aimed at non-fireproof electrical devices as such and/or with which the connection involves stripping which induces the exposure of a surface of flammable material not covered by a layer of retardant and/or fire-resistant coating, at the end and on the edge of the cable or wire. The electrical connection according to the invention is to be distinguished from a connection made between two cables, such as that described for example in patent applications US 2018/241190 or EP 216 613 A2 which relate to fireproof cable connectors and which do not describe the connection from a flame-resistant cable to a non-flame-resistant electrical device. In practice, the geopolymer composition or the silicate composition used according to the invention is advantageously applied to a larger surface than the sole surface to be protected, typically by overflowing beyond this surface to ensure complete coverage of the surface. without side effects. Thus, for example, when it is desired to protect the entire surface of the flammable material made accessible by stripping, it is advantageous to apply the composition not only to this surface, but also by overflowing onto an adjacent zone (this adjacent zone however, preferably being as small as possible, in particular to limit the amount of geopolymer or silicate composition to be applied, which results in a limitation of the associated costs).

[0015] The application of the geopolymer composition or of the silicate composition according to step (e) of the method of the invention, on the surface of the material flammable initially exposed, ultimately leads to obtaining a protective inorganic coating (respectively a geopolymer or silicate coating) at least on said surface. In addition to its protective effect against fire, this coating, when it is obtained by applying the silicate composition to the surface of the flammable material, has the advantage of being visually transparent and colorless, except to add dyes or opacifiers. Therefore, even when the protective coating is applied overflowing beyond the surface to be protected (which is advantageously the case for the aforementioned reasons) this coating does not induce a change in the coloring of the cable.

The method of the invention thus makes it possible, by depositing a protective layer of geopolymer or silicate on the surface initially exposed to the fire of the flammable material, to supplement in some way the protection provided elsewhere on all the rest of the cable by the retardant and/or fire-resistant coating layer, and this without affecting the appearance of the cable, at least as regards its color (which in particular makes it possible not to harm a direct identification of the cable). The method of the invention thus makes it possible to use the full potential of cables of the LFHC type by avoiding the problems associated with the exposure of flammable materials at their ends.

The method of the invention advantageously makes it possible to obtain a cable or an electric wire which meets the requirements of standard IEC/EN 60332-1-2 on its stripped portion or portions, due to the presence of the inorganic coating. geopolymer or silicate protector on the surface of the flammable material.

The visually transparent and colorless character of the coating obtained according to the process of the invention is an advantage for the cable obtained, in particular for the aforementioned reasons. However, in practice, due to this transparency of the final coating and the geopolymer or silicate composition used to obtain it (also visually transparent and colorless unless dyes or opacifiers are added), it may prove difficult, in practice, to visually ensure the adequate coating of the surface to be protected. To overcome this difficulty, according to an interesting embodiment of the invention, compatible in particular with the advantageous modes previously described, the geopolymer or silicate composition used in step (e) preferably comprises a marker making it possible to identify the areas where the composition is applied during step (e) (and therefore the areas which will ultimately be covered by the protective coating).

[0019] The marker used if necessary can be, in absolute terms, any marker allowing direct and rapid identification of the areas where the composition is deposited and it can therefore be, according to a particular mode, a simple dye or an opacifier. However, it is advantageous and most often preferred for the composition used in step (e) of the process of the invention to remain visually transparent and colorless, as well as the protective geopolymer or silicate coating obtained by application of this composition. Therefore, when a marker of the aforementioned type is used in the composition of step (e), it is advantageously a compound which makes it possible to preserve the visually transparent and colorless character of the composition and of the protective coating. .

[0020] It may for example be a UV marker, and typically a compound that does not show any coloration when it is illuminated with radiation in the visible light wavelength range but which emits luminescence. when it is irradiated under ultraviolet radiation, such as for example a compound soluble in aqueous or solvent phase.

The marker used in the composition may be in the form of an invisible ink, chosen in particular from an invisible ink Turquoise Blue IUV-TW (W), an invisible ink Deep Blue IUV-BS (S), an invisible ink Violet IUV-VS (S), an invisible ink Rose IUV-PS (S), an invisible ink Red IUV-RS (S), an invisible ink Orange IUV-OS (S), an invisible ink Yellow IUV- YS (S ), an invisible Lime IUV-LS (S) ink, an invisible Green IUV-GS (S) ink, and an invisible White IUV-WS (S) ink from the company STARDUSTCOLORS SAS.

Alternatively, the marker used in the composition is in the form of a pigment, chosen in particular from DT-11 Pink, DT-01 White, DT-20 Violet, DT-18 Green, DT-13 Red , DT-19 Blue, DT-15 Orange, DT-16 Yellow-Orange, DT-17 Yellow, DT-21 Magenta, DT-33 Scarlet Red, and the company's 9FG - Transparent Fluorescent Yellow STARDUSTCOLORS SAS. [0023] When a marker is used, step (e) may for example comprise:

- a first step (e1) of applying the geopolymer or silicate composition comprising the marker, then

- a second step (e2) of identifying the areas covered by the composition by means of said marker (for example by illuminating the area to be covered with an appropriate UV source in the case of the use of a UV marker) and of verification applying the composition at least to the surface to be coated; And

- if necessary, a third step (e3) of applying the geopolymer or silicate composition at least to the areas of the surface to be coated which would not have been coated during step (e1).

[0024] More simply, when a marker is used, step (e) can be carried out under conditions allowing the visualization of the marker during the application of the composition (for example by illuminating during application the area to be covered with an adequate UV source in the case of the use of a UV marker).

[0025] Within the meaning of the present description, the term "flammable material" means a material present in the electric cable or wire, and which is, as such (namely when it is insulated outside the cable or wire) , likely to ignite when brought into contact with a source of fire. This flammable material is preferably a non-fireproof material. Typically, when the flammable material is implemented around an elongated electrically conductive element of an electric cable or wire, said electric cable or wire may not meet the requirements of standard IEC/EN 60332-1-2 on its or its stripped portions because the flammable material has one or more surfaces made accessible by the stripping.

In a cable or wire subjected to the process of the invention, this flammable material is surrounded by the layer of retardant and/or fire-resistant coating, said layer not however completely covering the flammable material, and leaving it exposed to the fire at least at the level of the surface treated during step (e). Typically, but not necessarily, the fire retardant and/or fire resistant coating layer is in direct physical contact with the flammable material it surrounds. Alternatively, one or more layers Non-retardant or fire-resistant spacers may be present between the flammable material and the retardant and/or fire-resistant coating layer.

[0027] Similarly, during step (e), the composition of geopolymer or silicate composition is most often applied directly to an exposed part of the flammable material, and the composition is therefore strictly speaking applied to the flammable material itself. -even.

According to an alternative embodiment, it is possible, during step (e), to apply the composition of geopolymer or silicate composition not on the flammable material itself but on one or more layers not retardant or fire resistant present on the surface of the material.

The flammable material present in the wire or cable protected according to the method of the invention may for example comprise at least one non-flameproof insulating or semi-conductive layer, preferably containing at least one thermoplastic polymer, in particular chosen from homopolymers or olefin copolymers. For example, the non-flameproof insulating or semi-conductive layer contains a thermoplastic polymer chosen from polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC) and mixtures thereof. .

[0030] Said non-fireproof insulating or semi-conductive layer is preferably surrounded, in the wire or cable to be treated, by the retardant and/or fire-resistant coating layer. The flammable material may be a single layer of this type or else a set of several layers of this type, all located under the retardant and/or fire-resistant coating layer, for example a two-layer comprising an association of a semi- conductive coated with an insulating layer or a combination of an insulating layer coated with a semi-conductive layer; or a tri-layer comprising an internal semi-conductive layer coated with an insulating layer, itself coated with an external semi-conductive layer.

[0031] When the flammable material present in the wire or cable is or comprises at least one non-fireproof insulating or semi-conductive layer surrounded by the layer of retardant and/or fire-resistant coating, the surface of the flammable material on which is applied the geopolymer composition or the silicate composition during step (e) generally comprises at least one of the side surfaces of said insulating or semi-conductive layer on one of the terminal zones of the cable (at the end of the cable, the insulating or semi-conductive layer is not coated with the retardant and/or fire-resistant coating which covers it only along its length and the flammable material is therefore exposed on its side edge).

[0032] More generally, the surface of the flammable material on which the geopolymer composition or the silicate composition is applied during step (e) generally comprises at least one side surface of the material on at least one of the end zones of the wire or cable. According to one embodiment, only one of the end zones of the wire or of the cable is treated according to the method of the invention. Alternatively, the method of the invention makes it possible, if necessary, to treat the two end zones of the wire or cable.

The method of the invention proves particularly advantageous when the treated wire or cable has a terminal zone where the elongated electrically conductive element is stripped to ensure its electrical connection with an electrical termination of an electrical device. In this case, the surface of the flammable material on which the geopolymer composition or the silicate composition is applied is a surface made accessible by stripping. It corresponds in fact to the section of material which appears, schematically “on the edge” at the level of the section operated in the layer of said material to ensure the stripping. The method of the invention is then advantageously carried out on the cable electrically connected to the electrical termination, and not prior to the connection of the cable to the electrical termination, to avoid any risk of covering the stripped portion of the elongated electrically conductive element ( which would otherwise harm the desired electrical connection).

According to a particular embodiment, the method of the invention is operated on a wire or cable whose elongated electrically conductive element is stripped for connection to an electrical termination of an electrical panel. According to other possible modes, the method of the invention is carried out on a wire or cable whose elongated electrically conductive element is stripped with a view to connection to an electrical termination of another electrical device, for example a socket current, a switch, a heating device or lighting. In all cases, the method can be carried out before the electrical connection of the elongated electrically conductive element to the electrical termination or, more advantageously, once the electrical connection of the elongated electrically conductive element has been made.

According to another aspect, the invention also relates to assemblies comprising a cable or electric wire connected to an electrical device and protected against fire as obtained according to the method of the invention. and which have improved protection against fire outbreaks and fire propagation. The electrical cables or wires present in these connected assemblies advantageously meet the requirements of standard IEC/EN 60332-1-2, including on their bare portions, due to the presence of the protective inorganic coating of geopolymer or silicate on the surface. flammable material.

[0036] An assembly of this type comprises a cable which includes:

- at least one elongated electrically conductive element electrically connected to an electrical device (this device preferably being of the aforementioned type, for example an electrical cabinet, or else a socket, a switch, a heating or lighting device);

- at least one layer of a flammable material surrounding said elongated electrically conductive element; And

- a layer of retardant and/or fire-resistant coating surrounding said flammable material but not covering said coating at a surface of said flammable material; And

- a geopolymer or silicate coating applied to said surface of said flammable material.

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

[0038] Step (e)

[0039] During this step, a geopolymer composition or a silicate composition is applied to an exposed surface of the flammable material, typically at least one of the surfaces accessible by the edge on one of the end portions of the wire or cable. This application during step (e) has the advantage of being economical and very easy to implement. The application of the composition can for example be carried out by spraying the geopolymer or silicate composition onto the surface to be protected. For this purpose, the composition can be applied using a simple sprayer comprising the composition.

In addition, the application of step (e) can be carried out at room temperature, without the need for heat treatment and therefore directly on electrical installations within buildings at temperatures ranging, for example, from 10° C. to 50 °C approximately, in particular between 20°C to approximately 40°C.

[0042] Thus, the method of the invention proves to be particularly well suited for protecting the flammable material at the level of a stripped terminal portion of the wire or cable connected to an electrical termination of a device such as an electrical panel, a electrical outlet, a lighting device or a heating device.

The application according to step (e) is carried out very easily by simply spraying the composition on the cable once the electrical connection has been made. In the case of an electrical cabinet, all the connected wires can be treated at once by spraying the entire board.

[0044] Step (e) also makes it possible to apply the desired quantity of composition in the form of a homogeneous coating layer. It thus makes it possible to control the quantity of composition applied, by ensuring a sufficient deposit of material to obtain the expected protective effect and by limiting this application to the minimum necessary, in particular with a view to limiting costs.

[0045] When step (e) implements a geopolymer composition, this forms, by progressive solidification by formation ("setting"), a geopolymer material (more concisely referred to as "geopolymer" in the present description) from the geopolymer composition. In the present description, for the purpose of brevity, this solidification stage which induces the transformation of the geopolymer composition into geopolymer material is sometimes referred to as the "drying" stage, although the formation of the geopolymer from the geopolymer composition involves process more complex than simple drying and lead more to the formation of a material as such (geopolymer) than to the elimination of water.

The geopolymer compositions that can be used in step (e) are described in more detail below.

[0047] Instead of geopolymer compositions, step (e) can implement a silicate composition, which is then typically an aqueous solution of at least one alkali silicate advantageously chosen from sodium silicates, silicates of potassium, and mixtures thereof. A well-suited silicate composition is a “waterglass” type composition comprising sodium silicate in water.

In a silicate composition used in step (e), the SiO2/M2O molar ratio (M being an alkali metal atom, preferably sodium or potassium, and advantageously sodium) typically ranges from 1, 1 to 35 approximately, preferably from 1.3 to 10 approximately, and more preferably from 1.4 to 5 approximately.

The silicate composition used in step (e) can advantageously comprise alkali silicate at the rate of 45 g to 58 g per liter of aqueous solution of this silicate composition.

[0050] The geopolymer composition or the silicate composition is applied to the surface of the flammable material during step (e) in a thickness of about 10 μm to 1000 μm, preferably from 10 μm to 500 μm.

[0051] The geopolymer composition that can be used in step (e)

When step (e) uses a geopolymer composition, it is preferably a liquid geopolymer composition. To allow application by spraying, it is preferred to employ in step (e) a composition of relatively low viscosity, preferably less than 3 Pa.s.

A geopolymer composition used in step (e) is preferably an aluminosilicate geopolymer composition.

[0054] Particularly preferably, a geopolymer composition used in step (e) comprises water, silicon (Si), aluminum (Al), oxygen (O), and at least one element selected from potassium (K), sodium (Na), lithium (Li), cesium (Cs), and calcium (Ca), and preferably chosen from potassium (K) and sodium (Na).

This geopolymer composition may in particular comprise at least one first aluminosilicate, at least one first alkaline silicate, water, and optionally an alkaline base.

[0056] The first aluminosilicate

The first aluminosilicate can be chosen from metakaolins (i.e. calcined kaolins), fly ash (well known under the Anglicism "fly ash"), blast furnace slag (well known under the Anglicism "blast furnace slag “), swelling clays such as bentonite, calcined clays, any type of compound comprising aluminum and silica fume, zeolites, and one of their mixtures.

Among these compounds, metakaolins are preferred, in particular those marketed by the company Imerys.

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.

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.

The geopolymer composition may further comprise a second aluminosilicate different from the first aluminosilicate.

Preferably, the geopolymer composition comprises two calcined kaolins having different calcination temperatures.

According to a particularly preferred embodiment of the invention, the geopolymer composition comprises a first metakaolin chosen from calcined kaolins at a temperature T _ci of at least approximately 650° C., and a second metakaolin chosen from calcined kaolins at a temperature T _C 2 such that TC2 - Td > 100° C. approximately, at least one first alkaline silicate, water, and optionally an alkaline base. The geopolymer composition can then have improved mechanical properties, in particular in terms of flexibility and durability, while guaranteeing good reaction properties and fire resistance.

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

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

The first metakaolin may comprise at least approximately 20% by mole, and preferably at least 30% by approximately mole of aluminum oxide (Al2O3), relative to the total number of moles of the first metakaolin.

The first metakaolin may comprise at most approximately 60% by mole, and preferably at most 50% by approximately mole of aluminum oxide (Al2O3), relative to the total number of moles of the first metakaolin.

The first metakaolin may comprise at least 35% approximately by mole, and preferably at least 45% approximately by mole, of silicon oxide (SiC), relative to the total number of moles of the first metakaolin.

The first metakaolin may comprise at most 75% by mole approximately, and preferably at most 65% by mole approximately, of silicon oxide (SiC>2), relative to the total number of moles of the first metakaolin.

As examples of first metakaolin, mention may be made of the metakaolins sold by the company Imerys, in particular that marketed under the reference PoleStar® 450.

The first metakaolin may be chosen from kaolins calcined at T _ci as defined in the invention, for at least approximately 1 min, preferably for at least approximately 10 min, particularly preferably for a period ranging from approximately 30 min to 8 h, and more particularly preferably for a period ranging from approximately 2 h to 6 h.

The second metakaolin is preferably chosen from kaolins calcined at a temperature T _C 2 such that T _C 2 - T _ci approximately 150° C., in a particularly preferably such as T _C 2 - T _ci 200° C. approximately, and more particularly preferably such as T _C 2 - T _ci 250° C. approximately.

According to one embodiment of the invention, the second metakaolin is a calcined kaolin at a temperature T _C 2 of at least approximately 800° C., preferably of at least approximately 850° C., and in a particularly preferably at least about 900°C.

According to a preferred embodiment of the invention, the second metakaolin is a calcined kaolin at a temperature T _C 2 of at most 1200° C. approximately, and preferably of at most 1150° C. approximately.

The second metakaolin may comprise at least 20% by mole approximately, and preferably at least 30% by mole approximately, of aluminum oxide (Al2O3), relative to the total number of moles of the second metakaolin.

The second metakaolin can comprise at most 60% by mole approximately, and preferably at most 50% by mole approximately, of aluminum oxide (Al2O3), relative to the total number of moles of the second metakaolin.

The second metakaolin may comprise at least 35% by mole approximately, and preferably at least 45% by mole approximately, of silicon oxide (SiCh), relative to the total number of moles of the second metakaolin.

The second metakaolin may comprise at most 75% by mole approximately, and preferably at most 65% by mole approximately, of silicon oxide (SiC>2), relative to the total number of moles of the second metakaolin.

As examples of second metakaolin, mention may be made of the metakaolins sold by the company Imerys, in particular that marketed under the reference PoleStar® 200R.

The second metakaolin can be chosen from kaolins calcined at T _C 2 as defined in the invention, for at least approximately 1 min, preferably for at least approximately 5 min, particularly preferably for a period ranging from approximately 10 min to 2 h, and more particularly preferably for a period ranging from approximately 15 min to 1 h.

The mass ratio [first metakaolin/second metakaolin] in the geopolymer composition preferably ranges from 0.1 to 2 approximately, so particularly preferably from about 0.5 to about 1.0, and more particularly preferably is about 1.

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.

[0083] The first alkaline silicate

The first alkaline silicate can be chosen from sodium silicates, potassium silicates, and one of their mixtures.

The alkali metal silicates marketed by the company Silmaco or by the company PQ corporation are preferred. The first alkaline silicate is preferably a sodium silicate.

The first alkaline silicate may have a SiCh/IVhO molar ratio ranging from 1.1 to 35 approximately, preferably from 1.3 to 10 approximately, and particularly preferably from 1.4 to 5 approximately, with M being a sodium or potassium atom, and preferably a sodium atom.

The geopolymer composition may comprise from 5 to 60% by weight approximately, and preferably from 10 to 50% by weight approximately, of first alkali silicate, relative to the total weight of the geopolymer composition.

[0088] The second alkali silicate

The geopolymer composition may further comprise a second alkali silicate different from the first alkali silicate.

The second alkaline silicate can be chosen from sodium silicates, potassium silicates, and one of their mixtures. The alkaline silicates marketed by Silmaco or by PQ Corporation are preferred. The second alkaline silicate is preferably a sodium silicate.

The first and second alkali metal silicates may respectively have SiO2/M2O and SiO2/M'2O molar ratios 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, so particularly preferably such that their difference is at least 0.5, and more particularly preferably such that their difference is at least 1.0.

According to one embodiment of the invention, the geopolymer composition comprises:

- a first alkaline silicate having a SiCh/IVhO molar ratio ranging from approximately 1.5 to 2.6, and

- a second alkaline silicate having a SiO2/M'2O molar ratio greater than 2.6, preferably ranging from 2.8 to 4.5 approximately, and in a particularly preferred manner ranging from 3.0 to 4.0 approximately, being understood that M' is identical to M.

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

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

[0095] The alkaline base (optional)

The alkaline base can be sodium hydroxide, or potassium hydroxide, and preferably sodium hydroxide.

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 the preparation of a cable.

The solids/water mass ratio in said geopolymer composition determines the solidification kinetics during steps i) to iii).

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 (alkaline silicate(s), aluminosilicate(s) and alkaline base ), relative to the total weight of said geopolymer composition.

The geopolymer composition may also comprise one or more additives chosen from:

- a compound accelerating the solidification, in particular chosen from aluminum sulphate, alums (eg double sulphate of aluminum and potassium), calcium chloride, calcium sulfate, hydrated calcium sulfate, sodium aluminate, sodium carbonate, sodium chloride, sodium silicate, sodium sulfate, iron(III) chloride, and sodium lignosulphonates,

- an agent retarding caking, in particular chosen from ammonium, alkali metals, alkaline-earth metals, borax, lignosulphonates and in particular metal salts of calcium lignosulphonates, 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, chosen in particular from talc, micas, dehydrated clays, and

- their mixtures.

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.

[0102] The geopolymer material

According to the invention, a geopolymer material is obtained around the flexible elongated conductive element when the composition used in step (e) is a geopolymer composition. The geopolymer is preferably obtained by hardening, geopolymerization and/or polycondensation of said geopolymer composition.

In particular, the geopolymer composition as defined in the invention is capable of forming said geopolymer material. The ingredients of the geopolymer composition can therefore undergo polycondensation to form said geopolymer material. Hardening takes place by internal reaction of the polycondensation type.

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. In the present invention, the expression "geopolymer material" denotes 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).

The geopolymer material can be an aluminosilicate geopolymer material.

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

In one embodiment, the geopolymer material represents from 5 to 98% by weight approximately, preferably from 55 to 95% by weight approximately, and more preferably from 65 to 90% by weight approximately, relative to the weight total of the composite layer.

The method may further comprise, before step (e), a step (eo) for preparing the geopolymer composition comprising mixing said first aluminosilicate with said first alkaline silicate, water, and optionally the alkaline base.

Step (eo) is generally carried out at a high pH, in particular varying from 10 to 13.

Step (eo) preferably comprises the following sub-steps: (eo-i) a sub-step of preparing an aqueous solution of the first alkali silicate, and

(eo-2) a sub-step of mixing the first aluminosilicate in powder form with the aqueous alkali silicate solution prepared in the previous sub-step ioi). [0113] The aqueous solution of the first alkali silicate can be prepared by mixing silicon dioxide SiO2 or an alkali silicate with an MOH base in which M is K or Na.

The silicon dioxide SiO2 can be chosen from silica fume (i.e. fumed silica), quartz, and mixtures thereof.

The sub-step (eo-i) can be carried out by dissolving the base in water, resulting in the release of heat (exothermic reaction), then by adding the silica (or the alkaline silicate). The heat released then accelerates the dissolution of the silica (or of the alkaline silicate) during the sub-step ioi), and of the first aluminosilicate during the sub-step (eo-2).

[0116] When the second aluminosilicate and/or the second alkaline silicate as defined in the invention exist(s), step (eo) for preparing the geopolymer composition may comprise mixing said first aluminosilicate and optionally said second aluminosilicate, with said first alkaline silicate, optionally said second alkaline silicate, water, and optionally the alkaline base.

Step (eo) preferably comprises mixing the first and second metakaolins, with the first alkaline silicate and optionally the second alkaline silicate, water, and optionally an alkaline base.

The first and second metakaolins and the first and second alkali silicates are as defined in the invention.

According to a preferred embodiment, step (eo) comprises the following sub-steps:

(eo-a) mixing the first and second alkali metal silicates, in particular with stirring,

(eo-b) possibly adding an alkaline base, in particular while maintaining agitation, and

(eo-c) the addition of the first and second metakaolins, in particular while maintaining the agitation.

At the end of step (eo), or of sub-step (eo-2) or (eo-c), a fluid and homogeneous solution is preferably obtained. At the end of step (eo), the geopolymer composition may comprise from 35% to 80% by weight approximately, and in a particularly preferred manner from 40% to 70% by weight approximately, of solid matter (silicate alkali(s), aluminosilicate(s) and alkaline base), relative to the total weight of said geopolymer composition.

Such a mass ratio makes it possible to have a geopolymer composition that is fluid enough to allow it to be manipulated, and whose solidification kinetics are slow enough to allow the formation of a layer during step (e1).

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

After step (eo) of preparing the geopolymer composition, and before step (e1), the geopolymer composition can be heated, in particular to a temperature ranging from approximately 55° C. to 95° C., and from particularly preferably from 70° C. to 90° C. approximately. This facilitates step (e1).

[0125] The flammable material

The flammable material protected by the coating made in step (e), which can advantageously be the material constituting at least one electrically insulating or semi-conductive layer of the cable, is, according to an advantageous embodiment, a flammable polymer material.

As a flammable polymer that can be protected according to the invention, mention may in particular be made of polyvinyl chloride and polyolefins and in particular ethylene and propylene polymers. By way of example of ethylene polymers, mention may be made of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), copolymers of ethylene and vinyl acetate (EVA), copolymers of ethylene and butyl acrylate (EBA), methyl acrylate (EMA), 2-hexylethyl acrylate (2HEA), copolymers of ethylene and alpha-olefins such as for example polyethylene-octene (PEO), copolymers of ethylene and propylene (EPR), terpolymers of ethylene and propylene (EPT) such as for example terpolymers of ethylene propylene diene monomer (EPDM) or a mixture thereof. The flammable material does not generally contain any flame retardant compound. In particular, it generally contains no flame-retardant filler, and in particular no hydrated flame-retardant mineral filler such as a magnesium hydroxide or an aluminum trihydroxide.

The flammable material may however contain other types of filler, in particular an inert filler, in particular chosen from talc, micas, dehydrated clays and one of their mixtures, preferably in an amount which does not allow it to be make it fireproof.

[0130] Fields of Application of the Invention

The wires and cables protected against fire as obtained according to the present invention find multiple applications, which are those for which cables and wires of the LFHC type are generally recommended.

In particular, the cables and wires treated according to the method of the invention are particularly suitable in the fields of building wiring and electrical cabinets.

[0133] Description of the drawings

The accompanying drawings illustrate a possible embodiment of the invention: [Fig. 1] Figure 1 shows a schematic cross-sectional view of an electrical wire having a defect in its protection against fire and specific to the implementation of the method of the invention.

[Fig. 2] Figure 2 shows a schematic sectional view of the same electric wire after treatment according to the method of the invention.

For reasons of clarity, only the essential elements for understanding the invention have been represented schematically in the figures, without respecting the scale.

In Figure 1 is shown an electric wire 10 comprising an elongated conductive element 20. Around this conductive element 20, the wire comprises an insulating layer 30 (typically PVC or polyethylene, in particular crosslinked polyethylene or based on another flammable polymer such as polypropylene or a mixture of several polymers of this type). 2 geopolymer or silicate according to the invention. This insulating layer (20), which is flammable as such, is surrounded by a protective coating (40) intended to provide a fire retardant and/or fire resistant effect. The structure of this electric wire 10 is therefore the typical structure of that of an electric wire of the LFHC type.

The cable in Figure 1 is partially stripped at its terminal part (on the right in the figure), with a view to connection to an electrical panel or to another electrical device not shown in the figure. On this cable, despite the protection provided by the protective coating 40, part of the flammable insulating layer 30 is exposed at its side edge 50 which is not covered by the protective coating.

This lateral edge 50 accessible at the stripped zone constitutes a surface exposed to fire outbreaks which constitutes an example of a weak point now identified by the inventors in LFHC type cables.

In Figure 2 is shown the same cable as that of Figure 1 but where a coating of geopolymer or silicate 60 has been deposited on the wire, this coating 60 covering the side edge 50 and therefore provides anti-corrosion protection. fire according to the invention. This coating is applied by spraying the terminal area of the stripped cable with a geopolymer or silicate composition. The coating obtained, transparent and colorless, does not modify the appearance of the cable.

Claims

Claims [Claim 1] A method of protecting against fire an electrical cable or wire (10) comprising: - at least one elongated electrically conductive element (20); - at least one layer of a flammable material (30) surrounding said elongated electrically conductive element; And - a layer (40) of retardant and/or fire resistant coating surrounding said flammable material but not covering said coating at a surface (50) of said flammable material, said cable having a terminal zone where the electrically conductive element elongated member is stripped to provide electrical connection to an electrical termination of an electrical device wherein said method includes a step (e) wherein a geopolymer composition or a silicate composition is applied to said surface (50) of said flammable material, and wherein said surface (50) is a surface made accessible by stripping. [Claim 2] Method according to claim 1, wherein the electrical device is an electrical cabinet [Claim 3] A method according to claim 1, wherein the electrical device is an outlet, switch, heater or light. [Claim 4] Method according to one of Claims 1 to 3, in which the flammable material (30) present in the wire or cable comprises at least one non-flameproof insulating or semi-conductive layer, preferably containing at least one thermoplastic polymer, chosen in particular from olefin homopolymers or copolymers, said non-flameproof insulating or semi-conducting layer being surrounded by the retarding and/or fire-resistant coating layer. [Claim 5] Method according to one of Claims 1 to 4, in which the surface (50) of the flammable material (30) on which the geopolymer composition or the silicate composition is applied during step (e) comprises at least one of the side surfaces of said insulating or semi-conductive layer on one of the end zones of the wire or of the cable. [Claim 6] Process according to one of Claims 1 to 5, in which the geopolymer or silicate composition used in step (e) comprises a marker making it possible to identify the zones where the composition is applied during step ( e), for example a UV marker. [Claim 7] Process according to one of Claims 1 to 5, in which step (e) is carried out by spraying the geopolymer or silicate composition. [Claim 8] A method according to any of claims 1 to 6, wherein the composition employed in step (e) is a geopolymer composition, preferably an aluminosilicate geopolymer composition. [Claim 9] A method according to claim 7 wherein the geopolymer composition comprises at least a first aluminosilicate, at least a first alkali silicate, water, and optionally an alkali base. [Claim 10] Process according to any one of Claims 1 to 6, in which the composition used in step (e1) is an aqueous solution of at least one alkali silicate advantageously chosen from sodium silicates, potassium silicates , and mixtures thereof. [Claim 11] An assembly comprising an electrical cable or wire (10) protected against fire and an electrical device connected to said cable or wire, said cable or wire comprising: - at least one elongated electrically conductive element (20) electrically connected to said electrical device; - at least one layer of a flammable material (30) surrounding said elongated electrically conductive element; And - a layer (40) of retardant and/or fire-resistant coating surrounding said flammable material but not covering said coating at a surface (50) of said flammable material; And - a coating of geopolymer or silicate (60) applied to said surface (50) of said flammable material. [Claim 12] Assembly according to claim 11, wherein the electrical device is an electrical cabinet. [Claim 13] An assembly according to claim 11, wherein the electrical device is an outlet, a switch, or a heating or lighting device.