impregnation device for the manufacture of a fire-resistant and / or fire-retardant cable comprising a geopolymer composite coating

Abstract

The present invention relates to a device suitable for impregnating a geopolymer composition onto a fibrous material coating a cable core, comprising: - means ensuring the guidance and movement of the cable core coated with fibrous material within the device, from an inlet to an outlet of the device; and - between said inlet and said outlet, a coating chamber provided with at least one geopolymer composition supply channel connected to means for injecting geopolymer composition into said chamber continuously and with a controlled flow rate. Figure for the abstract: Fig. 1

Description

Title of the invention: impregnation device for the manufacture of a resistant and / or retardant cable fire comprising a geopolymer composite coating

[0001] The present invention relates to the manufacture of cables comprising at least one elongated electrically conductive element and at least one composite layer surrounding said elongated electrically conductive element, said composite layer being obtained by impregnation of a non-woven fibrous material with a geopolymer composition. More specifically, the invention relates to a device for controlling and optimizing the impregnation of the non-woven fibrous material with the geopolymer composition.

[0002] The invention applies typically, but not exclusively, to the preparation of fire-retardant and / or fire-resistant cables intended for the transport of energy and / or the transmission of data, such as fire-retardant and / or fire-resistant electrical and / or optical safety cables, in particular halogen-free, capable of operating for a given period of time under fire conditions without propagating fire or generating significant smoke.

[0003] It is known, in particular from application WO 2016 / 092200, a method for preparing a cable comprising at least one elongated electrically conductive element and at least one composite layer surrounding said elongated electrically conductive element, in which (i) a non-woven fibrous material, typically of a soft and flexible structure, is applied around a power and / or telecommunications cable core, whereby a cable core / fibrous material assembly is obtained; then (ii) the assembly thus obtained is immersed in a geopolymer composition, which leads to impregnation of the fibrous material, then by hardening the geopolymer composition, to obtaining a geopolymer coating around the cable core.

[0004] For the purposes of the present description, the term "cable core" means an elongated conductive element or a set of several elongated conductive elements, possibly coated, for example with a sheath, or more generally an internal elongated element, generally extending over the entire length of the cable.

[0005] Thus, in methods of the type described in the aforementioned application WO 2016 / 092200, the non-woven fibrous material is typically applied to an elongated conductor, a set of elongated conductors or to an internal layer of the cable.

[0006] In these methods, the impregnation of the fibrous material is generally carried out by coating / immersion, typically in line, by scrolling the cable core previously coated with the fibrous material in a tank filled with liquid geopolymer composition. When the running speed of the cable core is not too high, this method of impregnation leads to saturation of the fibrous material with geopolymer composition, this saturation not always being desirable, particularly from an economic point of view (obtaining interesting properties does not necessarily imply the impregnation of such a large quantity of geopolymer composition). In other cases, conversely, the conditions for implementing the process imply a high running speed, and the impregnation within the tank may then prove insufficient and / or inhomogeneous.The final properties of the geopolymer coating around the cable core are therefore highly dependent on the running speed, which is not always a parameter that can be chosen to adapt (and which is often, on the contrary, a parameter dictated by other process constraints).

[0007] An aim of the present invention is to improve the aforementioned impregnation methods, by providing means making it possible, whatever the running speed of the cable core, to control the quantity of the geopolymer composition impregnated on the fibrous material and to ensure the homogeneity of the impregnation.

[0008] To this end, the present invention proposes a particular coating device, which is provided with a specific coating chamber, within which the cable core coated with the fibrous material is circulated, and which allows adjustment of the quantity of geopolymer impregnated on the fibrous material, and therefore in particular an adaptation of this quantity of impregnated geopolymer as a function of the running speed of the cable core, and a homogeneous impregnation of this geopolymer composition on the fibrous material.

[0009] More specifically, according to a first aspect, the present invention relates to a device suitable for impregnating a geopolymer composition on a fibrous material coating a cable core, comprising: - means ensuring the guidance and movement of the cable core coated with fibrous material within the device, from an inlet of said device to an outlet of said device; and - between said inlet and said outlet, a coating chamber provided with at least one geopolymer composition supply channel (and generally several supply channels), connected to means allowing the injection of geopolymer composition into said chamber continuously and with a controlled flow rate.

[0010] According to another aspect, the present invention relates to the use of the aforementioned device for carrying out the impregnation of a geopolymer composition on a fibrous material, typically non-woven, coating a cable core.

[0011] In this context, the invention relates in particular to a method for manufacturing a cable (in particular an energy and / or telecommunications cable) comprising at least one fire-resistant insulating layer based on a composite material comprising at least one geopolymer material and at least one fibrous material, typically non-woven, implementing the aforementioned device.

[0012] This manufacturing process typically comprises: - a step of impregnation with a geopolymer composition of a cable core coated with a fibrous material, - a step of hardening the geopolymer composition to form said fire-resistant insulating layer based on said composite material, characterized in that the impregnation step is carried out in an impregnation device of the aforementioned type.

[0013] Preferably, the coating chamber of the device of the invention has a conical geometry, which in particular allows optimization of the impregnation of the fibrous material by the geopolymer composition.

[0014] More precisely, according to an advantageous embodiment, which corresponds to that illustrated in the attached figures, the coating chamber has substantially the shape of a truncated cone and the scrolling and guiding means then preferably ensure positioning of the cable core within said chamber along the axis of the truncated cone formed by the chamber. Typically, the aforementioned inlet of the device (allowing the entry of the cable core before its stay in the chamber) is on the side of the large base of the truncated cone, and the aforementioned outlet of the device (that which allows the exit of the cable core after its stay in the chamber) is, conversely, on the side of the small base of said truncated cone, which induces a scrolling of the cable core from the most flared part of the chamber towards its narrowest part, thus further optimizing the contact between the geopolymer composition and the fibrous material to be impregnated.

[0015] Furthermore, it is preferable for the device to ensure circulation of the geopolymer composition with a flow in the same direction as the movement of the cable, ensuring as much as possible a laminar flow of the fluid along the cable core, which further optimizes the effectiveness of the impregnation. For this purpose, the aforementioned embodiment is preferably implemented, with a coating chamber of truncated cone shape, and one or more geopolymer composition supply channels opening into the coating chamber on the side of the large base of the truncated cone formed by the chamber, which induces circulation of the geopolymer composition from the large base of the truncated cone towards the small base (therefore from the most flared part of the chamber towards its narrowest part).

[0016] Whatever the exact mode of implementation of the invention, it is preferable that the supply channels associated with the injection means ensure filling permanent filling of the coating chamber with geopolymer composition throughout the impregnation process. Indeed, the pressure exerted by the composition filling the chamber then makes it possible to force the penetration of the composition into the fibrous material, the force of the pressure exerted in this context being able to be easily modulated by controlling the injection rate of geopolymer composition (the higher this rate, the more intense the force exerted), which makes it possible to modulate the quantity of geopolymer composition ultimately incorporated into the fibrous material. The present invention thus makes it possible to very easily control the quantity of impregnated geopolymer composition, by simply adjusting the injection rate of the composition.The higher the speed at which the cable core travels within the device (and therefore in particular within the coating chamber), the higher the flow rate will need to be to ensure a given impregnation rate, but the invention makes it possible in all cases to obtain a targeted impregnation rate, whatever the speed at which the cable core to be impregnated travels.

[0017] Various aspects and possible embodiments of the invention are described in more detail below. Geopolymer material

[0018] The geopolymer / fibrous material composite material constituting the fire-resistant insulating layer that the invention makes it possible to obtain is based on a geopolymer material.

[0019] 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).

[0020] The geopolymer material may in particular be an aluminosilicate geopolymer material.

[0021] The 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.

[0022] The geopolymer material is obtained from the geopolymer composition, generally by drying, geopolymerization and / or polycondensation of said composition. geopolymer (processes referred to herein as “curing” of the geopolymer composition).

[0023] 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.

[0024] The formation of the geopolymer material from the geopolymer composition is therefore carried out by an internal reaction and is not, for example, 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. The fibrous material

[0025] The fibrous material constitutes another constituent of the geopolymer / fibrous material composite constituting the fire-resistant insulating layer that can be obtained by the invention. It is also the material that initially coats the cable core introduced into the impregnation device of the invention.

[0026] This fibrous material is preferably a non-woven fibrous material. Furthermore, it advantageously has a soft and flexible structure.

[0027] This fibrous material, typically non-woven, can in particular be chosen from cellulosic materials, materials based on synthetic organic polymers, glass fibers, and one of their mixtures, and preferably from materials based on synthetic organic polymers.

[0028] The cellulosic materials may be chosen from paper, in particular blotting paper; non-woven materials made from functionalized or non-functionalized cellulose; matrices with a honeycomb and / or fibrous structure made from natural cellulose acetate fibers.

[0029] The materials based on synthetic organic polymers may be chosen from polymer materials with a porous and / or fibrous matrix of polyolefin(s), in particular those chosen from propylene homo- and copolymers, ethylene homo- and copolymers, high-density polyethylenes (HDPE), aromatic polyamides (aramids), polyesters, and one of their mixtures.

[0030] According to an interesting embodiment of the invention, the non-woven fibrous material is a polyethylene terephthalate (PET).

[0031] The non-woven fibrous material preferably has a grammage ranging from approximately 50 to 120 g / cm2. This makes it possible to obtain a sufficiently strong composite layer. flexible to be easily handled, and robust enough to provide good fire protection.

[0032] The geopolymer / fibrous material composite layer obtained according to the invention

[0033] This composite layer, obtained by impregnating the fibrous material with the geopolymer composition in the device of the invention and then hardening the composition inducing the formation of a geopolymer material entangled in the fibers of the fibrous material, generally constitutes a continuous, typically non-porous envelope on the surface of the cable core, suitable for being subsequently coated with other coating layers.

[0034] Taking into account the implementation of the device of the invention, this composite layer has a substantially constant thickness, this thickness generally has a value typically ranging from approximately 0.2 to 3 mm, for example from approximately 0.5 to 1 mm.

[0035] Most often, 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 total weight of the composite layer produced using the device of the invention.

[0036] Furthermore, the non-woven fibrous material generally represents from 2 to 95% by weight approximately, particularly preferably from 5 to 45% by weight approximately, and even more preferably from 10 to 35% by weight approximately, relative to the total weight of the composite layer produced using the device of the invention. The cable heart

[0037] The cable core on which the device and the method of the invention make it possible to deposit a fire-resistant insulating layer based on the geopolymer / fibrous material composite material is an elongated element, advantageously but not necessarily of cylindrical shape with a circular section.

[0038] This cable core may for example be an elongated cylindrical conductive element possibly covered with an insulating layer or even a set of several cylindrical elements (each of which may be covered with an insulating layer), typically grouped into a strand to ensure the most cylindrical section possible, and which may be sheathed.

[0039] More generally, any internal element of a cable that is to be covered with an insulating layer based on a composite geopolymer material / fibrous material may be used as a cable core, this internal element preferably having the shape of a cylinder of circular section. For example, the cable core may comprise at least one elongated cylindrical conductive element covered by several coatings that are more internal than the insulating layer based on a composite geopolymer material / fibrous material. According to a specific embodiment, the cable core may be an armored cable core, comprising an armor and, under this armor, at least one elongated conductive element coated with an insulating layer, typically several conductive elements of this type.

[0040] The cable core used in the device of the present invention is previously coated with a fibrous material, advantageously of the aforementioned type. This coating of fibrous material around the cable core is typically carried out by using the fibrous material in the form of a ribbon, and by coating the cable core by winding said ribbon around the cable core, prior to impregnation in the device of the invention.

[0041] This preliminary winding of the tape around the cable core, which aims to cover the cable core over its entire length, is typically carried out:

[0042] - along the longitudinal axis of the cable core, namely with a winding of the ribbon around the cable core with the longitudinal axis of the tape parallel to the longitudinal axis of the cable core, the tape then being folded around the cable core in the direction of its width (the tape then closes over the cable core with generally little overlap of the faces of the tape on each other, typically with overlap areas of approximately 10 to 20%); or

[0043] - according to a helical winding, namely by winding the ribbon around the core of cable with the longitudinal axis of the ribbon which is neither parallel nor perpendicular to the longitudinal axis of the cable core, the ribbon then forming a helix around the cable core (the ribbon then covering the cable core with generally little overlap of the faces of the ribbon from one turn of the helix to the next, typically with overlap areas of approximately 10 to 20%).

[0044] The winding, whatever its mode, can be carried out manually or in an automated manner, and preferably in an automated manner.

[0045] When the winding of the tape around the cable core is carried out along the longitudinal axis of the cable core, it is advantageously implemented by passing the tape through a tightening device or a tape shaping device initiating its folding around the cable core in the direction of its width (device referred to below as "trumpet"). The cable core then also passes through the tightening device, which makes it possible to continuously wind the tape around the cable core.

[0046] When the winding of the tape around the cable core is helical, it is advantageously carried out by winding the tape around the cable core with the longitudinal axis of the tape forming an angle typically between 20 and 70° with the longitudinal axis of the cable core and by driving the cable in rotation and translation to ensure the continuous winding of the tape in the form of a helix around the cable.

[0047] Guiding and running of the cable core coated with fibrous material

[0048] The means ensuring the guidance and movement of the cable core coated with fibrous material within the device of the invention are typically cylindrical conduits having a section of the same geometry as the cable core coated with fibrous material, typically a circular section when the cable core is of circular section.

[0049] In particular, in order to avoid leaks of geopolymer composition from the device, it is preferable for the cylindrical conduits to have a geometry and dimensions adjusted to the cable coated with fibrous material that they convey, with typically, in the case of cylindrical conduits of circular section, a diameter substantially equal to but very slightly greater than that of the coated cable core that they convey, to allow the passage of the cable core.

[0050] As means ensuring the guidance and movement of the cable core coated with fibrous material within the device of the invention, the device typically comprises: - a first cylindrical conduit extending from the aforementioned inlet of the device (which then also constitutes the inlet of said first cylindrical conduit) to an inlet of the coating chamber; and - a second cylindrical conduit, aligned with the first cylindrical conduit along the same longitudinal axis, and extending from an outlet of the coating chamber to the aforementioned outlet of the device.

[0051] It should be noted that it may be useful for the second cylindrical conduit which carries the cable core exiting the chamber (and therefore coated with a fibrous material impregnated with geopolymer composition) to have a slightly larger diameter than the first cylindrical conduit (intended to carry the cable core coated with a fibrous material not yet impregnated.

[0052] When the induction chamber has the shape of a truncated cone, said first and second cylindrical conduits preferably have longitudinal axes coincident with the axis of said truncated cone. Furthermore, the first cylindrical conduit advantageously opens at the level of the large base of the truncated cone (in other words the inlet of the coating chamber through which the cable core coated with fibrous material penetrates is located at the level of this large base of the truncated cone) and the second cylindrical conduit starts at the level of the small base of the truncated cone (typically the small base of the truncated cone constitutes both the circular inlet of the second cylindrical conduit and the outlet of the coating chamber).

[0053] The geopolymer composition injected into the coating chamber

[0054] The geopolymer composition used to impregnate the fibrous material within the device of the invention is generally a liquid geopolymer composition.

[0055] This composition is conveyed into the coating chamber via at least one channel connected to means for injecting said geopolymer composition allowing a continuous injection with a controlled flow rate. Typically, a pump with a regulated flow rate and preferably an adjustable flow rate can be used for this purpose, for example a gear pump, injecting the geopolymer composition at at least one second inlet separate from the inlet allowing the introduction of the cable core and conveyed by said channel to the coating chamber. The attached figures illustrate in detail a possible embodiment of this type of supply to the coating chamber.

[0056] Whatever its mode of introduction into the device of the invention, the geopolymer composition used is preferably an aluminosilicate geopolymer composition.

[0057] 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).

[0058] The geopolymer composition may in particular comprise at least one first aluminosilicate, at least one first alkali silicate, water, and optionally an alkaline base. The first aluminosilicate

[0059] The first aluminosilicate 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 fumace slag"), swelling clays such as bentonite, calcined clays, any type of compound comprising aluminum and silica fume, zeolites, and a mixture thereof.

[0060] Among these compounds, metakaolins are preferred, in particular those marketed by the company Imérys.

[0061] 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.

[0062] 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.

[0063] The geopolymer composition may further comprise a second aluminosilicate different from the first aluminosilicate.

[0064] Preferably, the geopolymer composition comprises two calcined kaolins having different calcination temperatures.

[0065] 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 > approximately 100°C, at least one first alkali 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 and fire resistance properties.

[0066] According to one embodiment of the invention, the first metakaolin is a kaolin calcined at a temperature Tci of at least approximately 700°C, and preferably of at least approximately 725°C.

[0067] According to a preferred embodiment of the invention, the first metakaolin is a kaolin calcined at a temperature Tci of at most approximately 875°C, and preferably of at most approximately 825°C.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] As examples of first metakaolin, we can cite the metakaolins sold by the company Imérys, in particular that marketed under the reference PoleStar® 450.

[0073] The first metakaolin may be chosen from kaolins calcined at Tci as defined in the invention, 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.

[0074] The second metakaolin is preferably chosen from kaolins calcined at a temperature Tc2 such that Tc2 - Tci > approximately 150°C, particularly preferably such that Tc2 - Tci > approximately 200°C, and more particularly preferably such that Tc2 - Tci > approximately 250°C.

[0075] 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.

[0076] 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 most approximately 1150°C.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] As examples of second metakaolin, we can cite the metakaolins sold by the company Imérys, in particular that marketed under the reference PoleStar® 200R.

[0082] 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.

[0083] The mass ratio [first metakaolin / second metakaolin] in the geopolymer composition is preferably from about 0.1 to about 2, particularly preferably from about 0.5 to about 1.0, and more particularly preferably is about 1.

[0084] 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. The first alkali silicate

[0085] The first alkali silicate may be chosen from sodium silicates, potassium silicates, and one of their mixtures.

[0086] Alkali silicates marketed by Silmaco or PQ Corporation are preferred. The first alkali silicate is preferably a sodium silicate.

[0087] The first alkali silicate may have a SiO2 / M2O molar ratio ranging from about 1.1 to about 35, preferably from about 1.3 to about 10, and particularly preferably from about 1.4 to about 5, with M being a sodium or potassium atom, and preferably a sodium atom.

[0088] 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. The second alkali silicate

[0089] The geopolymer composition may further comprise a second alkali silicate different from the first alkali silicate.

[0090] 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.

[0091] 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.

[0092] According to one 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.

[0093] 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.

[0094] 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. The alkaline base

[0095] The alkaline base may be sodium hydroxide, or potassium hydroxide, and preferably sodium hydroxide.

[0096] The geopolymer composition may be free of alkaline base. This thus makes it possible to improve the handling of the geopolymer composition, in particular when preparing a cable.

[0097] The mass ratio of solids to water in said geopolymer composition determines the solidification (setting) kinetics of the composition.

[0098] 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.

[0099] The geopolymer composition may further comprise one or more additives chosen from: - a 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 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 and 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, in particular chosen from aluminum sulfate, alums (e.g. double aluminum and potassium sulfate), calcium chloride, 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 the 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.

[0100] The dye is preferably a liquid dye at room temperature (i.e. 18-25°C).

[0101] 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. Preparation of geopolymer composition

[0102] A geopolymer composition useful according to the invention can typically be prepared according to a step (E) of mixing said first aluminosilicate with said first alkali silicate, water, and optionally the alkali base.

[0103] This mixing step is generally carried out at a high pH, ​​in particular varying from 10 to 13.

[0104] This mixing step preferably comprises the following sub-steps: (Ei) preparing an aqueous solution of the first alkali silicate; and (E2) mixing the first aluminosilicate in powder form with the aqueous alkali silicate solution prepared in sub-step (Ei).

[0105] 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.

[0106] Silicon dioxide SiO2 can be chosen from silica fume (i.e. pyrogenic silica), quartz, and mixtures thereof.

[0107] Sub-step (Ei) can be carried out by dissolving the base in water, resulting in the release of heat (exothermic reaction), 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).

[0108] 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.

[0109] Step (E) preferably comprises mixing the first and second metakaolins, with the first alkali silicate and optionally the second alkali silicate, water, and optionally an alkaline base.

[0110] 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) optional addition of an alkaline base, in particular while maintaining stirring; and (Ec) adding the first and second metakaolins, in particular while maintaining stirring.

[0111] 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.

[0112] 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.

[0113] 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 the formation of a cable layer as defined below.

[0114] The solids / water mass ratio in said geopolymer composition can make it possible to determine the solidification kinetics of said geopolymer composition.

[0115] After step (E) of preparing the geopolymer composition, and before its impregnation onto 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 may facilitate the impregnation step. Where appropriate, it is nevertheless advisable to control the heating conditions, which, if too drastic, may induce polymerization and solidification phenomena. External protective sheath

[0116] Preferably, the geopolymer-based composite layer which is obtained around the cable core following the implementation of the device of the invention is an internal layer of the cable according to the invention.

[0117] According to the invention, the term “inner layer” means a layer which does not constitute the outermost layer of the cable.

[0118] Advantageously, an external protective sheath is deposited around the composite layer obtained according to the invention. The external protective sheath can in particular ensure the mechanical integrity of the composite layer.

[0119] The application of this protective sheath around the composite composition can typically be carried out by extrusion, in particular at a temperature ranging from approximately 140°C to 195°C. Brief description of the drawings

[0120] The attached drawings illustrate a possible embodiment of the invention:

[0121] [Fig-1] [Fig.l] represents a schematic sectional view of a device impregnation according to the invention.

[0122] [Fig.2] [Fig.2] is a schematic exploded sectional view of the same device

[0123] [Fig.3] [Fig.3] is the same schematic view but in perspective

[0124] [Fig.4] [Fig.4] is a schematic view of the device of [Fig.l], in action with introduction of a cable core coated with a fibrous material, illustrating the method of the invention

[0125] Only the elements essential for understanding the presentation have been represented schematically in these figures, without respecting the scale.

[0126] L a [Fig.l] is a schematic sectional view of an impregnation device 1 according to the invention. This device, of generally cylindrical shape, comprises an inlet 2 and an outlet 3 allowing respectively the entry and exit of a cable core coated with a fibrous material intended to be impregnated with geopolymer composition within the device.

[0127] The device is formed by two pieces fitted together and secured together by screws (not shown in [Fig.l], because they are outside the section plane), namely: - a first piece 10 having the shape of a truncated cone placed on a cylindrical base and provided with: (i) inlets pierced in its cylindrical base, among which inlets 11 and 12 are visible in the section plane (other similar inlets 13 and 14 are visible in [Fig.3] in perspective). These inlets are cylindrical conduits opening on either side of the base of the part 10 and which allow the introduction of geopolymer composition into the device 1. For this purpose, the inlets 11 to 14 are connected to means for injecting polymer composition (injection pump, not shown, ensuring continuous injection at a constant flow rate); and (ii) a cylindrical conduit 15 for guiding the cable core, drilled in the body of the part 10 along the axis of the cylinder trunk and the base, which begins with the inlet 2 of the device and extends along the part 2 crossing the base and the entire truncated part; And - a second part 20, having the shape of two cylinders placed side by side, the larger cylinder (on the left in the figure) having a truncated cone-shaped recess wider than the truncated cone of the part 10, thus providing an internal space between the parts 10 and 20, this space comprising: - channels 21 and 22 in fluid connection respectively with the inlets 11 and 12 of the part 10 and therefore suitable for conveying the geopolymer composition introduced into the device; and - a truncated space 24 forming a coating chamber according to the invention. At the small base of this truncated space, a cylindrical conduit 25 is hollowed out, the longitudinal axis of which is aligned with the longitudinal axis of the cylindrical conduit 15 of the part 10 and which ends at the outlet 3 of the device, which makes it suitable for ensuring the continuity of the guidance and the running of the cable core from the truncated space 24 (coating chamber) towards the outlet 3.

[0128] [Fig.2] shows the two parts 10 and 20 of [Fig.l], but separated (in their state before the assembly of the device and the joining of the two parts by screws). This figure shows more clearly the truncated cone-shaped recess 27 present in the part 20.

[0129] [Fig. 3] shows the two parts 10 and 20 separated in the same way as in the previous figure, but in a perspective view. This perspective view makes it possible to visualize all of the inlets 11, 12, 13 and 14 on the part 20. It also shows the orifices 16, 17, 18, 19 on the part 10 and the threaded orifices 26, 27, 28 and 29 on the part 20 which allow the parts 10 and 20 to be secured by screwing.

[0130] [Fig.4] illustrates the mode of operation of the device of the invention.

[0131] There we see an assembly 30 comprising a cylindrical cable core of circular section 35 coated with a fibrous material 36, introduced into the device via the circular conduit 15, adjusted to the diameter of the assembly 30. During the implementation of the method of the invention, this coated cable core moves from left to right as indicated by the arrow on the far right of the figure.

[0132] After being conveyed in the conduit 15, a given portion of the moving cable is conducted into the truncated internal space 24 forming the coating chamber of the device.

[0133] The flow of geopolymer composition, represented by the arrows on the left in the figure, continuously feeds the chamber, with a flow in the same direction as the movement of the cable and constant filling of this internal space 34, which ensures optimal impregnation of the fibrous material.

[0134] Each portion of cable thus impregnated with the geopolymer composition then continues its movement in the device by passing through the second cylindrical conduit 25 which carries the cable core 35 now coated with an impregnated fibrous material 37 to the exit of the device.

Claims

Claims

1. Method for manufacturing a cable comprising at least one fire-resistant insulating layer based on a composite material comprising at least one geopolymer material and at least one fibrous material, typically non-woven, comprising: - a step of impregnating with a geopolymer composition a cable core coated with a fibrous material, - a step of curing the geopolymer composition to form said fire-resistant insulating layer based on said composite material, characterized in that the impregnation step is carried out in an impregnation device comprising: - means ensuring the guidance and movement of the cable core coated with fibrous material (30) within the device, from an inlet (2) of said device to an outlet (3) of said device;and - between said inlet (2) and said outlet (3), a coating chamber (24) provided with at least one geopolymer composition supply channel (ll, 12, 21, 22) connected to means allowing the injection of geopolymer composition into said chamber continuously and with a controlled flow rate, where the supply channels associated with the injection means ensure permanent filling of the coating chamber with geopolymer composition throughout the impregnation process, whereby the pressure exerted by the composition filling the chamber makes it possible to force the penetration of the composition into the fibrous material.;

2. A method according to claim 1 wherein the coating chamber (24) has substantially the shape of a truncated cone, with said inlet (2) of the device on the side of the large base of the truncated cone, and said outlet (3) of the device on the side of the small base.

3. Method according to claim 2 where the geopolymer composition supply channel(s) (11, 12, 21, 22) open into the coating chamber on the side of the large base of the truncated cone.

4. Method according to one of claims 1 to 3, where the means ensuring the guidance and the running of the cable core coated with fibrous material within the device are cylindrical conduits (15, 25) having a section of the same geometry as the cable core coated with fibrous material.

5. Method according to claim 4, comprising, as means ensuring the guidance and the running of the cable core coated with fibrous material within the device: - a first cylindrical conduit (15) extending from the aforementioned inlet of the device to an inlet of the coating chamber; and - a second cylindrical conduit (25), aligned with the first cylindrical conduit along the same longitudinal axis, and extending from an outlet of the coating chamber to the aforementioned outlet of the device.

6. Method according to one of claims 1 to 5, where the supply channels associated with the injection means ensure permanent filling of the coating chamber with geopolymer composition.

7. Manufacturing method according to one of claims 1 to 6, wherein the geopolymer composition is an aluminosilicate geopolymer composition

8. Use of the method according to one of claims 1 to 7, for carrying out the impregnation of a geopolymer composition on a fibrous material coating a cable core.

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