EP4261852A1 - Material for local reinforcement or restoration of fire resistance of electrical cables - Google Patents

Abstract

The present invention relates to a method for improving the fire resistance performance of a cable, which comprises at least one step (e1) in which an impregnated fibrous material is deposited, on only a portion of the exterior surface of said cable. of geopolymer composition, which results in a fire-resistant composite coating on this portion of the surface. The invention also relates to kits for implementing the method, as well as improved cables as obtained at the end of the method.

Description

The present invention relates to the field of wires and cables having fire resistance capabilities. Cables with this capacity, called "fire resistant" are intended to be used in electrical devices whose electrical integrity is maintained under the conditions of a fire: they continue to perform their role even when they are subjected to at high temperature. This type of fire-resistant cable generally has good performance in reaction to fire, with interesting properties of non-propagation of fire and non-production of smoke. The fire resistance capabilities of a cable can be quantified in particular according to the standardized tests of the NF C 32070 category CR1, EN 50200, IEC 60331-1, or IEC60331-2 standards.

The invention more precisely makes it possible to protect, reinforce or restore the fire resistance capabilities of an electrical cable provided with a protective layer intended to provide it with such capabilities. In particular, the invention aims to restore the performance of fire-resistant cables when their protective layer intended to ensure fire resistance is damaged. Alternatively, the invention can be used preventively to prevent such damage to a cable area or more generally to increase at least locally the fire resistance capabilities of an electric cable.

The invention typically applies, but not exclusively, to cables intended for the transport of energy such as fire-resistant electrical safety cables, in particular halogen-free, capable of operating for a given period of time under conditions of fire. The invention is also well suited for cables intended to prevent the spread of fire or the generation of smoke. The cables used in the context of the invention can in particular be low or medium voltage energy transmission cables and in particular for voltages below 30 kV. The invention is also suitable for information transport cables and cables comprising optical fibers.

To improve the fire resistance of electrical wires and cables, numerous solutions have been proposed, which conventionally use at least one protective coating surrounding the underlying layers of the wire or cable which are based on flammable materials. This protective coating is intended to protect these flammable materials when the wire or cable is subjected to fire conditions. 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, an overheating point or a spark.

The protective layers that are used to prevent ignition of this type of flammable material can vary quite widely. 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 manner, the ignition of the flammable material when the protective layer is interposed between the material to be protected and the source of the flammable material. 'fire. Effective protective layers are notably used in so-called “LFHC” wires and cables (for English: “Low Fire Hazard Cables”) which include, for example, polymer materials including flame-retardant fillers. More specifically, it has been described, in particular in the application EP 3 670 471 , the use of particularly effective layers based on geopolymers.

However, during the transport, installation and use of a fire-resistant cable, the protective materials which ensure the fire-resistant effect may be damaged locally, for example under the effect of shocks. , mechanical stress or friction, which leads to the appearance of weaknesses in the protective layer (crack, fragility, reduced thickness for example) and therefore reduces the overall fire resistance effect of the cable.

An aim of the present invention is to make it possible to restore the fire resistance properties of such a damaged cable.

More generally, the invention aims to provide products and methods making it possible to locally improve the fire protection effect of a cable to ensure said cable has increased fire resistance capabilities.

For this purpose, it is proposed according to the present invention to apply locally to the cable a fibrous material impregnated with a polymer composition, whereby a protective geopolymer coating is obtained locally on said cable, the inventors of which have now demonstrated that It improves the fire resistance properties of the cable. In particular, when applied to the fragilities of the protective layer of a damaged cable, the protective geopolymer coating restores at least identically (or even improving) the initial fire resistance properties of the cable.

More precisely, according to a first aspect, the present invention relates to a method making it possible to improve the fire resistance properties of a cable which comprises at least one step (e1) in which one deposits, on only a portion of the outer surface of said cable, a fibrous material impregnated with geopolymer composition, whereby a fire-resistant composite coating is obtained on said portion of the outer surface of the treated cable.

Typically, in the process of the invention the impregnated material is applied to a cable comprising a layer intended to ensure fire resistance but damaged locally with local fragilities (such as cracks or reduction in thickness in particular). In this case, in step (e1), the fibrous material is deposited on only part of the cable but in such a way as to cover the fragilities of said damaged layer (for example on a crack in the cable or an area of lesser thickness). In practice, the impregnated material is advantageously applied to a larger surface than just the surface in terms of fragility, typically by extending beyond this surface to ensure complete coverage without edge effect.

According to an embodiment compatible with the repair of a damaged layer described in the previous paragraph, the method of the invention can be used more generally to locally reinforce the fire resistance properties of the cable, whether it is damaged or No. In this case, case in step (e1), the fibrous material can for example be deposited on a part of the cable intended to be subjected to higher temperature conditions than the rest of the cable (at an electrical cabinet or a connection for example). Again preferably overflowing a little to ensure complete coverage of the targeted area without edge effect.

The cable treated according to the invention generally comprises a layer of flammable material under a layer intended to ensure fire resistance. For the purposes of this description, the term "flammable material" means a material present in the cable, and which is, as such (i.e. when it is isolated outside the cable), likely to ignite when it comes into contact with a fire source.

The flammable material present cable treated according to the method of the invention may for example comprise at least one non-flame-retardant insulating or semi-conducting layer, preferably containing at least one thermoplastic polymer chosen from polyethylene (PE), polypropylene (PP) or polyvinyl chloride (PVC),

In all cases, step (e1) is advantageously, but not necessarily, followed by a step (e2) of hardening the polymer composition. In fact, whether this step (e2) is carried out or not, we systematically obtain, simply because of the implementation of step (e1), a fire-resistant composite coating on a portion of the exterior surface of the cable. The consolidation step (e2) has the advantage of ensuring better performance of the composite covering around the cable modified according to the process but it has no impact on the fire resistance properties themselves.

According to an interesting embodiment of the invention, step (e1) is carried out by applying, around only a portion of the exterior surface of the cable, a ribbon comprising a fibrous material impregnated with geopolymer composition and forming at the same time Using this tape at least one closed ring around the cable. According to a first advantageous variant of this embodiment, the ribbon used in step (e1) comprises a continuous ribbon of fibrous material impregnated with geopolymer composition. According to this variant, step (e2) is advantageously implemented at the end of step (e1) to ensure good retention of the ribbon around the cable. Alternatively, the ribbon may be based on a continuous non-fibrous support and comprise several discontinuous zones of fibrous material impregnated with a geopolymer composition. In this case, the implementation of step (e2) remains advantageous but it is not strictly necessary

According to another embodiment, step (e1) is carried out by depositing a fire-resistant composite coating on the cable to be treated in an area which does not form a continuous ring around the cable. In this case, it is most often necessary to ensure adhesion between this covering and the cable. To do this, the covering is advantageously secured to the cable using a layer of adhesive further outside the cable (i.e. further away from the axis of the cable than the covering carried out according to step (e1) and , if applicable, of step (e2) optional). The adhesive layer then traps all or part of the covering between the cable and the adhesive. According to a first variant, the fibrous material used is previously deposited on a layer of adhesive of greater dimension than that of the fibrous material, thus schematically forming a sort of adhesive dressing which allows direct application to the cable, schematically in the same way that an impregnated dressing is applied to the skin in the medical field. In this case, step (e2) is not generally implemented, the imprisonment of the geopolymer composition between the cable and the adhesive making this step difficult to carry out. According to another variant, the geopolymer composition can be applied in the form of at least one small “patch” of dimensions smaller than the diameter of the cable, then an adhesive is applied to at least part of the patch overflowing on the cable, a bit like a compress fixed with adhesive tape to draw the same parallel with the medical field. This embodiment is particularly well suited to ensuring localized and precise treatment of weak areas of the cable in terms of fire resistance and it makes it possible to limit the quantities of geopolymers and fibrous material used.

The method of the invention thus makes it possible, according to all its variants, to deposit an additional protective coating on the treated cable, for example in areas which are weakened or likely to become so, whereby the treated cable has increased resistance performance. to the fire in relation to the cable before the implementation of step (e1).

According to another aspect, the present invention also relates to modified surface cables of the type obtained according to the method of the invention, which are modified at only part of their surface by a protective coating as obtained according to step (e1) and the optional subsequent step (e2).

• au moins un élément électriquement conducteur allongé ou au moins une fibre optique;
• au moins une couche d'un matériau inflammable entourant ledit élément électriquement conducteur allongé ou la fibre optique; et
• optionnellement, et de préférence, une couche destinée à assurer une résistance au feu entourant ledit matériau inflammable; et
• un revêtement protecteur de géopolymère appliquée autour de la couche de matériau inflammable, sur une partie seulement du câble, le cas échéant autour de la couche destinée à assurer une résistance au feu.

A cable of this type typically includes:

• at least one elongated electrically conductive element or at least one optical fiber;
• at least one layer of flammable material surrounding said elongated electrically conductive element or the optical fiber; And
• optionally, and preferably, a layer intended to ensure fire resistance surrounding said flammable material; And
• a protective geopolymer coating applied around the layer of flammable material, on only part of the cable, if necessary around the layer intended to ensure fire resistance.

• Un premier type de kit comprend un matériau fibreux imprégné de composition géopolymère dans un contenant fermé étanche. Dans ce type de kit, le matériau fibreux imprégné de composition géopolymère est de préférence :
• sous la forme d'un ruban, de longueur plus importante que le diamètre externe du câble à traiter ;
• déposé sur une couche d'adhésif de dimension plus importante que celle du matériau fibreux, formant une sorte de pansement adhésif ; ou
• sous la forme d'une compresse.

According to yet another aspect, the present invention relates to kits for implementing the method of the invention.

• A first type of kit comprises a fibrous material impregnated with geopolymer composition in a sealed, closed container. In this type of kit, the fibrous material impregnated with geopolymer composition is preferably:
• in the form of a ribbon, of length greater than the external diameter of the cable to be treated;
• deposited on a layer of adhesive of greater dimension than that of the fibrous material, forming a sort of adhesive dressing; Or
• in the form of a compress.

• une composition géopolymère dans un récipient fermé étanche ; et
• un matériau fibreux destiné à être imprégné par ladite composition, de préférence sous forme de ruban ou de compresse.

A second type of kit includes

• a geopolymer composition in a sealed closed container; And
• a fibrous material intended to be impregnated with said composition, preferably in the form of a ribbon or compress.

This second kit can for example include a bottle of geopolymer composition on the one hand and compresses to be impregnated on the other hand. According to a more interesting variant, the kit may comprise a device containing (1) a sealed tank filled with geopolymer composition and (2) a reserve of ribbon of fibrous material, said tank being provided with an outlet connected to a nozzle or another means for delivering the geopolymer composition and the ribbon reserve unwinding the ribbon at this delivery means, whereby a ribbon impregnated with geopolymer composition, of desired length, is obtained, if necessary, by simple unwinding from the reserve on the desired length.

These two types of kits may optionally include, in addition to the impregnated material, an adhesive film to be applied on the one hand to all or part of said covering and on the other hand to part of the external surface of the cable, to

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

Step (e1)

During this step, a geopolymer composition is used in impregnated form on a fibrous material.

This application during step (e1) has the advantage of being economical and very easy to implement. It can be carried out at room temperature, without requiring heat treatment and therefore directly on electrical installations within buildings at temperature ranging for example from approximately 10°C to 50°C, in particular between approximately 20°C to 40°C

Step (e1) also 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, particularly with a view to limiting costs.

The geopolymer composition of step (e1) is capable of forming, by progressive solidification ("setting") a geopolymer material (designated more concisely by "geopolymer" in the present description) from the impregnated geopolymer composition used in step (e1). In the present description, for the sake of brevity, this solidification step which induces the transformation of the geopolymer composition into geopolymer material is sometimes referred to as the "drying" step, although the formation of the geopolymer from the geopolymer composition involves processes that are more complex than simple drying and which lead more to the formation of a material as such (geopolymer) rather than to a simple elimination of water.

The compositions and materials that can be used in step (e1) are described in more detail below.

The fibrous material

The fibrous material which is impregnated with the geopolymer composition in step (e1) is preferably a non-woven fiber material. Whether non-woven or not, it advantageously has a soft and flexible structure.

This fibrous material, typically non-woven, may 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.

Cellulosic materials can be chosen from paper, in particular blotting paper; non-woven materials made from functionalized or non-functionalized cellulose; structure matrices alveolar and/or fibrous made from natural cellulose acetate fibers.

The materials based on synthetic organic polymers can be chosen from polymer materials with a porous and/or fibrous polyolefin(s) matrix, 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.

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

The non-woven fibrous material preferably has a weight ranging from approximately 50 to 120 g/cm ² . This makes it possible to obtain a composite layer that is sufficiently flexible to be able to be handled easily, and sufficiently robust to obtain good fire protection.

The aeopolymer/fibrous material composite layer obtained according to the invention at the end of step (e2)

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

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 0.5 to 1 mm. approximately.

Most often, the geopolymer material represents approximately 5 to 98% by weight, preferably approximately 55 to 95% by weight, and more preferably approximately 65 to 90% by weight, relative to the total weight of the composite layer. carried out using the device of the invention.

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

The geopolymer composition usable in step (e1)

When step (e) uses a geopolymer composition, it is preferably a liquid geopolymer composition. To allow application by spraying, it is preferred to use in step (e) a composition of relatively low viscosity, preferably less than 5 Pa.s.

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

Particularly preferably, a geopolymer composition used in step (e) comprises water, silicon (Si), aluminum (AI), 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).

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

The first aluminosilicate

The first aluminosilicate can be chosen from metakaolins (ie calcined kaolins), fly ash (well known as “ fly ash ”), blast furnace slag (well known as “ blast fumace 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 Imérys.

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 approximately 5 to 50% by weight of aluminosilicate, and preferably from approximately 10 to 35% by weight 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 kaolins calcined at a temperature T _c1 of at least approximately 650°C, and a second metakaolin chosen from kaolins calcined at a temperature T _c2 such that T _c2 - T _c1 ≥ approximately 100°C, at least a first alkaline silicate, water, and optionally an alkaline base. The geopolymer composition can then have improved mechanical properties, particularly in terms of flexibility and durability, while guaranteeing good reaction and fire resistance properties.

According to one embodiment of the invention, the first metakaolin is a kaolin calcined at a temperature T _c1 of at least approximately 700°C, and preferably at least approximately 725°C.

According to a preferred embodiment of the invention, the first metakaolin is a kaolin calcined at a temperature T _c1 of at most approximately 875°C, and preferably at most approximately 825°C.

The first metakaolin may comprise at least approximately 20 mol%, and preferably at least approximately 30 mol%, of aluminum oxide (Al ₂ O ₃ ), relative to the total number of moles of the first metakaolin.

The first metakaolin may comprise at most approximately 60 mol%, and preferably at most approximately 50 mol%, of aluminum oxide (Al ₂ O ₃ ), relative to the total number of moles of the first metakaolin.

The first metakaolin may comprise at least approximately 35 mol%, and preferably at least approximately 45 mol%, of silicon oxide (SiO ₂ ), relative to the total number of moles of the first metakaolin.

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

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

The first metakaolin can be chosen from kaolins calcined at T _c1 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 a.m., and more particularly preferably for a period ranging from approximately 2 hours to 6 hours.

The second metakaolin is preferably chosen from kaolins calcined at a temperature T _c2 such that T _c2 - T _c1 ≥ approximately 150°C, in a particularly preferred manner such that T _c2 - T _c1 ≥ approximately 200°C, and more preferably particularly preferred such that T _c2 - T _c1 ≥ approximately 250°C.

According to one embodiment of the invention, the second metakaolin is a kaolin calcined at a temperature T _c2 of at least approximately 800°C, preferably at least approximately 850°C, and particularly preferably at least approximately 850°C. minus approximately 900°C.

According to a preferred embodiment of the invention, the second metakaolin is a kaolin calcined at a temperature T _c2 of at most approximately 1200°C, and preferably at most approximately 1150°C.

The second metakaolin may comprise at least approximately 20 mol%, and preferably at least approximately 30 mol% of oxide. of aluminum (Al ₂ O ₃ ), relative to the total number of moles of the second metakaolin.

The second metakaolin may comprise at most approximately 60 mol%, and preferably at most approximately 50 mol%, of aluminum oxide (Al ₂ O ₃ ), relative to the total number of moles of the second metakaolin.

The second metakaolin may comprise at least approximately 35 mol%, and preferably at least approximately 45 mol%, of silicon oxide (SiO ₂ ), relative to the total number of moles of the second metakaolin.

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

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

The second metakaolin can be chosen from kaolins calcined at T _c2 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 hours, and more particularly preferably for a period ranging from approximately 15 minutes to 1 hour.

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

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

The first alkali silicate

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

Alkaline 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 alkali silicate may have a SiO ₂ /M ₂ O molar ratio ranging from approximately 1.1 to 35, preferably from approximately 1.3 to 10, and particularly preferably from approximately 1.4 to 5, with M being a sodium or potassium atom, and preferably a sodium atom.

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

The second alkaline 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. Alkaline silicates marketed by the company Silmaco or by the company PQ Corporation are preferred. The second alkali silicate is preferably a sodium silicate.

The first and second alkali silicates can respectively have molar ratios SiO ₂ /M ₂ O and SiO ₂ /M' ₂ O such that M and M', identical, are chosen from a sodium atom and a potassium atom, and from 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 preferred way such that their difference is at least 1.0.

• un premier silicate alcalin ayant un rapport molaire SiO₂/M₂O allant de 1,5 à 2,6 environ, et
• un deuxième silicate alcalin ayant un rapport molaire SiO₂/M'₂O supérieur à 2,6, de préférence allant de 2,8 à 4,5 environ, et de façon particulièrement préférée allant de 3,0 à 4,0 environ, étant entendu que M' est identique à M.

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

• a first alkaline silicate having a SiO ₂ /M ₂ O molar ratio ranging from approximately 1.5 to 2.6, and
• a second alkaline silicate having a SiO ₂ /M' ₂ O 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.

The geopolymer composition may comprise approximately 10 to 60% by weight, and preferably approximately 20 to 50% by weight, of first and second alkali 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.

The alkaline base (optional)

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

• des fibres minérales, notamment choisies parmi les fibres d'alumine,
• un additif à structure polymère, notamment choisi parmi les fibres de polyoléfine telles que les fibres de polypropylène, de polyéthylène haute densité (HDPE), les aramides, et les fibres techniques de verre enduites de silicone ou d'un polymère organique de type polyéthylène ; un copolymère de styrène-butadiène (SBR) ; un copolymère de styrène-butadiène-éthylène (EBS) ; les dérivés des copolymères de styrène-éthylène, notamment ceux commercialisés par Kraton tels qu'un copolymère de styrène-éthylène-butylène-styrène (SEBS), un copolymère de styrène-butadiène-styrène (SBS), un copolymère de styrène-isoprène-styrène (SIS), un copolymère de styrène-propylène-éthylène (EPS) ou un copolymère de styrène-éthylène-propylène- styrène (SEPS) ; un copolymère d'éthylène et d'acétate de vinyle (EVA), un polyorganosiloxane réticulé (e.g. à l'aide d'un peroxyde) ; du polyéthylène éventuellement sous forme de poudre ; des lignosulfonates ; de l'acétate de cellulose ; et d'autres dérivés de la cellulose ;
• un composé accélérant la prise en masse, notamment choisi parmi le sulfate d'aluminium, les aluns (e.g. sulfate double d'aluminium et de potassium), le chlorure de calcium, le sulfate de calcium, le sulfate de calcium hydraté, l'aluminate de sodium, le carbonate de sodium, le chlorure de sodium, le silicate de sodium, le sulfate de sodium, le chlorure de fer (III), et les lignosulfonates de sodium,
• un agent retardant la prise en masse, notamment choisi parmi l'ammonium, les métaux alcalins, les métaux alcalino-terreux, le borax, le borate de zinc, les lignosulfonates et en particulier les sels de métaux de lignosulfonates de calcium, les celluloses telles que la carboxyméthyl hydroéthyl cellulose, les lignines sulfoalkylées telles que par exemple la lignine sulfométhylée, les acides hydroxycarboxyliques, les copolymères de sels d'acide 2-acrylamido-2-méthylpropane sulfonique et d'acide acrylique ou d'acide maléique, et les sels saturés,
• une charge inerte, notamment choisi parmi le talc, les micas, et les argiles déshydratées ,
• un amidon,
• un plastifiant de l'amidon, notamment choisi parmi un stéarate de métal, un polyéthylène glycol, un éthylène glycol, un polyol comme le glycérol, le sorbitol, le mannitol, le maltitol, le xylitol ou un oligomère de l'un de ces polyols, un sucrose comme le glucose ou le fructose, un plastifiant contenant des groupes amides, et tout type de plastifiant à base de polysaccharide(s) modifié(s),
• un dérivé de la cellulose, et/ou
• un matériau carboné expansé tel qu'un graphite expansé.

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

• mineral fibers, in particular chosen from alumina fibers,
• an additive with a polymer structure, in particular chosen from polyolefin fibers such as polypropylene fibers, high density polyethylene (HDPE), aramids, and technical glass fibers coated with silicone or an organic polymer of the polyethylene type; a styrene-butadiene copolymer (SBR); a styrene-butadiene-ethylene copolymer (EBS); derivatives of styrene-ethylene copolymers, in particular those marketed by Kraton such as a styrene-ethylene-butylene-styrene copolymer (SEBS), a styrene-butadiene-styrene copolymer (SBS), a styrene-isoprene-styrene copolymer (SIS), a styrene-propylene-ethylene copolymer (EPS) or a styrene-ethylene-propylene-styrene copolymer (SEPS); a copolymer of ethylene and vinyl acetate (EVA), a crosslinked polyorganosiloxane (eg using a peroxide); polyethylene optionally in powder form; lignosulfonates; cellulose acetate; and other cellulose derivatives;
• a compound accelerating mass formation, in particular chosen from aluminum sulfate, alums (eg double sulfate of aluminum and potassium), calcium chloride, calcium sulfate, hydrated calcium sulfate, aluminate sodium, sodium carbonate, sodium chloride, sodium silicate, sodium sulfate, iron (III) chloride, and sodium lignosulfonates,
• a mass-retardant agent, in particular chosen from ammonium, alkali metals, alkaline earth metals, borax, zinc borate, 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-methylpropane sulfonic acid and acrylic acid or maleic acid, and salts saturated,
• an inert filler, in particular chosen from talc, micas, and dehydrated clays,
• 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, and/or
• an expanded carbonaceous material such as expanded graphite.

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

Geopolymer material

According to step (e2) of the method of 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” designates a solid material comprising silicon (Si), aluminum (AI), 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 may be an aluminosilicate geopolymer material.

The aluminosilicate geopolymer material can be chosen from poly(sialates) corresponding to the formula (I) M _n (-Si-O-Al-O-) _n [(M)-PS] and having an equal Si/AI molar ratio to 1, poly(sialate-siloxos) corresponding to formula (II) M _n (-Si-O-Al-O-Si-O-) _n [(M)-PPS] and having a Si/AI molar ratio equal to 2, poly(sialate-disiloxos) corresponding to formula (III) M _n (-Si-O-Al-O-Si-O-Si-O) _n [(M)-PSDS] and having a ratio molar Si/AI equal to 3, and others 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 designates the degree of polymerization.

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

The method may further comprise, before step (e), a step (e ₀ ) of preparing the geopolymer composition comprising mixing said first aluminosilicate with said first alkaline silicate, water, and optionally the alkaline base.

Step (e ₀ ) is generally carried out at a high pH, in particular varying from 10 to 13.

• (e_0-1) une sous-étape de préparation d'une solution aqueuse du premier silicate alcalin, et
• (e_0-2) une sous-étape de mélange du premier aluminosilicate sous forme de poudre avec la solution aqueuse de silicate alcalin préparée à la sous-étape i₀₁) précédente.

Step (e ₀ ) preferably comprises the following substeps:

• (e _0-1 ) a sub-step of preparing an aqueous solution of the first alkaline silicate, and
• (e _0-2 ) a sub-step of mixing the first aluminosilicate in powder form with the aqueous solution of alkaline silicate prepared in the previous sub-step i ₀₁ ).

The aqueous solution of the first alkali silicate can be prepared by mixing silicon dioxide SiO ₂ or an alkali silicate with an MOH base in which M is K or Na.

The silicon dioxide SiO ₂ can be chosen from silica fume (ie fumed silica), quartz, and mixtures thereof.

The substep (e _0-1 ) 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 i ₀₁ ), and of the first aluminosilicate during sub-step (e _0-2 ).

When the second aluminosilicate and/or the second alkali silicate as defined(s) in the invention exist(s), the step (e ₀ ) of preparing the geopolymer composition may comprise the mixture of said first aluminosilicate and optionally of said second aluminosilicate, with said first alkali silicate, optionally said second alkali silicate, water, and optionally the alkaline base.

Step (e ₀ ) 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.

• (e_0-a) le mélange des premier et deuxième silicates alcalins, notamment sous agitation,
• (e_0-b) éventuellement l'ajout d'une base alcaline, notamment en maintenant l'agitation, et
• (e_0-c) l'ajout des premier et deuxième métakaolins, notamment en maintenant l'agitation.

According to a preferred embodiment, step (e ₀ ) comprises the following substeps:

• (e _0-a ) the mixture of the first and second alkali silicates, in particular with stirring,
• (e _0-b ) optionally adding an alkaline base, in particular while maintaining stirring, and
• (e _0-c ) the addition of the first and second metakaolins, in particular while maintaining agitation.

At the end of step (e ₀ ), or sub-step (e _0-2 ) or (e _0-c ), a fluid and homogeneous solution is preferably obtained.

At the end of step (e ₀ ), the geopolymer composition can comprise from approximately 35% to 80% by weight, and particularly preferably from approximately 40% to 70% by weight, of solid materials (alkaline silicate ( 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 its handling, and whose solidification kinetics are slow enough to allow the formation of a layer during step (e1).

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

After step (e ₀ ) 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 in a particularly preferred from approximately 70°C to 90°C. This makes it possible to facilitate step (e1).

The flammable material

The flammable material protected by the coating carried out in step (e1), which can advantageously be the constituent material of at least one electrically insulating or semi-conducting layer of the cable, is, according to an interesting embodiment, a polymer material flammable.

As a flammable polymer which can be protected according to the invention, mention may in particular be made of polyvinyl chloride and polyolefins and in particular polymers of ethylene and propylene. As an 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), ethylene copolymers 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 ethylene terpolymers propylene diene monomer (EPDM) or a mixture thereof.

The flammable material generally does not contain a flame retardant compound. In particular, it generally does not contain a 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.

EXAMPLE

The interesting effects which are obtained by using the method of the invention are illustrated by the example below, in which cables initially resistant to fire were deliberately damaged (by scratching their protective sheath not affecting the layer internal insulating material to reduce their fire resistance performance) then post-treated according to the invention in order to observe the effects on performance. In this example, a ribbon of fibrous material impregnated with geopolymer composition was applied to the damaged parts and using this ribbon, at least one closed ring was formed around the cable.

• un câble R2V 3×1.5mm² (câble base PVC) ;
• un câble Alsecure Premium 2×1.5mm².

Two types of cable were used, namely:

• a 3×1.5mm ² R2V cable (PVC base cable);
• an Alsecure Premium 2×1.5mm ² cable.

Two types of performance tests were carried out for these cables:

Flame retardant tests according to standard IEC/EN 60332-1-2

These tests measure flame propagation distances. The performance targets for a fire-resistant cable correspond to the lowest possible propagation distance.

The tests according to the IEC/EN60332-1-2 standard were carried out on the initial undamaged cable, then on the damaged cable, then on the post-treated damaged cable according to the invention.

Three series of measurements were carried out for each cable tested (series 1, 2 and 3 for R2V; series 4, 5 and 6 for the Alsecure Premium cable), each series including the initial test, the test after damage and the test after the post-processing of the invention)

• une nette chute des performances suite à l'endommagement, avec une augmentation de la distance de propagation, et
• une très forte amélioration des performances après l'application avec une performance même meilleure que celle du câble initial.

For the two cables, we observed:

• a clear drop in performance following the damage, with an increase in the propagation distance, and
• a very strong improvement in performance after application with performance even better than that of the initial cable.

More precisely, the propagation distances measured are as follows:

• Cable initial : 121 mm en moyenne (série 1 : 124 mm - série 2 : 128 mm - série 3 : 112 mm)
• Cable endommagé : 152 mm en moyenne (série 1 : 186 mm - série 2 : 147 mm - série 3 : 122 mm)
• Cable endommagé post-traité selon l'invention : 58 mm en moyenne (série 1 : 88 mm - série 2 : 52 mm - série 3 : 34 mm)

For the R2V 3×1.5mm ² cable:

• Initial cable: 121 mm on average (series 1: 124 mm - series 2: 128 mm - series 3: 112 mm)
• Damaged cable: 152 mm on average (series 1: 186 mm - series 2: 147 mm - series 3: 122 mm)
• Damaged cable post-treated according to the invention: 58 mm on average (series 1: 88 mm - series 2: 52 mm - series 3: 34 mm)

• Cable initial : 70 mm en moyenne (série 4 : 68 mm - série 5 : 64 mm - série 6 : 78 mm)
• Cable endommagé : 130 mm en moyenne (série 4 : 136 mm - série 5 : 142 mm - série 6 : 112 mm)
• Cable endommagé post-traité selon l'invention : 50 mm en moyenne (série 4 : 35 mm - série 5 : 48 mm - série 6 : 67 mm)

For the Alsecure Premium 2×1.5mm ² cable:

• Initial cable: 70 mm on average (series 4: 68 mm - series 5: 64 mm - series 6: 78 mm)
• Damaged cable: 130 mm on average (series 4: 136 mm - series 5: 142 mm - series 6: 112 mm)
• Damaged cable post-treated according to the invention: 50 mm on average (series 4: 35 mm - series 5: 48 mm - series 6: 67 mm)

Tests according to standard NFC 32070 - category CR1

These tests were carried out for the Alsecure Premium 2×1.5mm ² cable (four series 7, 8, and 9 and 10, each including a measurement on the initial cable, a measurement after damage and a measurement after post-treatment according to the invention)

• Cable initial : 115 minutes en moyenne (série 7 : 120 min - série 8 : 120 min - série 9 : 98 min - série 10 : 120 min)
• Cable endommagé : 57 minutes en moyenne (série 7 : 48 min - série 8 : 57 min - série 9 : 87 min - série 10 : 34 min)
• Cable endommagé post-traité selon l'invention : 119 minutes en moyenne (série 7 : 114 min - série 8 : 120 min - série 9 : 120 min - série 10 : 120 min)

The following fire resistance times were measured (the higher this time, the better the performance of the cable):

• Initial cable: 115 minutes on average (series 7: 120 min - series 8: 120 min - series 9: 98 min - series 10: 120 min)
• Damaged cable: 57 minutes on average (series 7: 48 min - series 8: 57 min - series 9: 87 min - series 10: 34 min)
• Damaged cable post-treated according to the invention: 119 minutes on average (series 7: 114 min - series 8: 120 min - series 9: 120 min - series 10: 120 min)

• une nette chute des performances suite à l'endommagement, avec une très nette réduction du temps de résistance (environ 1h contre presque 2h pour le câble de départ) , et
• une très forte amélioration des performances après l'application avec une récupération des performances du câble initial (environ 2h) .

Here again we observe:

• a clear drop in performance following damage, with a very clear reduction in resistance time (around 1 hour compared to almost 2 hours for the starting cable), and
• a very strong improvement in performance after application with recovery of the performance of the initial cable (approximately 2 hours).

Claims (10)

Method for improving the fire resistance properties of a cable, which comprises at least one step (e1) in which a fibrous material impregnated with geopolymer composition is deposited, on only a portion of the exterior surface of said cable, whereby a fire-resistant composite coating is obtained on said portion of the exterior surface of the treated cable. Method according to claim 1, where the impregnated material is applied to a cable comprising a layer intended to ensure locally damaged fire resistance, with local fragilities, and where, in step (e1), the fibrous material is deposited from so as to cover said local fragilities with said damaged layer. Method according to claim 1 or 2, where, in step (e1), the fibrous material is deposited on a part of the cable intended to be subjected to higher temperature conditions than the rest of the cable. Method according to one of claims 1 to 3, where step (e1) is followed by a step (e2) of hardening the polymer composition. Method according to one of claims 1 to 3, where step (e1) is not followed by a step (e2) of hardening the polymer composition. Method according to one of claims 1 to 5, where step (e1) is carried out: - by applying, around only a portion of the exterior surface of the cable, a ribbon comprising a fibrous material impregnated with geopolymer composition and by forming with this ribbon at least one closed ring around the cable; Or Method according to one of claims 1 to 5, where step (e1) is carried out by depositing on the cable to be treated a fire-resistant composite coating on an area which does not form a continuous ring around the cable and by securing the coating to the cable using a layer of adhesive further outside the cable than the coating carried out according to step (e1) and, where appropriate, step (e2). Cable capable of being obtained according to the process of one of claims 1 to 7. Kit for implementing the method according to one of claims 1 to 7, comprising: - a fibrous material impregnated with geopolymer composition in a sealed, closed container; And - optionally an adhesive film Kit for implementing the method according to one of claims 1 to 7, comprising: - a geopolymer composition in a sealed, closed container; And - a fibrous material intended to be impregnated with said composition, preferably in the form of a ribbon or compress.