Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K21/00—Fireproofing materials
  • C09K21/02—Inorganic materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B7/00—Insulated conductors or cables characterised by their form
  • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
  • H01B7/29—Protection against damage caused by extremes of temperature or by flame
  • H01B7/295—Protection against damage caused by extremes of temperature or by flame using material resistant to flame
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/2933—Coated or with bond, impregnation or core

Definitions

• the present invention relates to a composition for a material capable of withstanding extreme temperature conditions.
• a particularly advantageous but non-exclusive application of the invention lies in the field of power and/or telecommunications cables that are to remain operational for a defined length of time when subjected to high temperatures and/or directly to flames.
• a cable is electrical or optical, for transporting energy or for transmitting data, it can be said, in outline, to be constituted by at least one conductor element extending inside at least one insulator element. It should be observed that at least one of the insulator elements may also act as protection means and/or that the cable may also have at least one specific protection element constituting a sheath.
• the best insulating and/or protection materials used in cable making many are also materials that are highly flammable. This applies in particular to polyolefins and copolymers thereof, such as, for example: polyethylene, polypropylene, copolymers of ethylene and vinyl acetate, and copolymers of ethylene and propylene. In any event, in practice, this excessive flammability is completely incompatible with requirements to withstand fire as mentioned above.
• halogen compounds in the form of a halogenated by-product dispersed in a polymer matrix, or directly in the form of a halogenated polymer as with polyvinylchloride (PVC) for example.
• PVC polyvinylchloride
• present regulations are tending to ban future use of substances of that type, essentially because of their potential toxicity and corrosiveness, whether at the time the material is fabricated, or in the event of it being decomposed by fire. This is particularly true when the decomposition in question can occur accidentally during a fire, or also deliberately during incineration. In any event, the recycling of halogenated materials continues to be particularly problematic.
• the metal hydroxide content may typically reach 100 to 150 parts by weight per 100 parts by weight of polymer resin.
• Phyllosilicates are also known for being usable as non-halogenated fire-retardant fillers. Those inorganic compounds are remarkable in that they are capable of forming nanocomposites with the polymer matrices in which they are dispersed.
• the technical problem to be solved by the subject matter of the present invention is to propose a fire-resistant composition, in particular as a material for a power and/or a telecommunications cable, which composition makes it possible to avoid the problems of the prior art, while being inexpensive, and while providing significantly improved properties in terms of withstanding fire.
• the solution to the technical problem posed consists in that the composition comprises a polymer and aluminum oxide in the form of particles having a mean diameter that is less than one micrometer ( ⁇ m).
• aluminum oxide is used to mean non-hydrated alumina having the formula Al 2 O 3 .
• the composition of the invention comprises a polymer matrix in which sub-micron alumina is dispersed to act as a fire-retardant filler.
• fire-resistant composition is used herein very broadly to cover any composition that is for constituting a material capable of slowing down fire propagation and/or of resisting fire.
• the mean size of the aluminum oxide particles constitutes the essential parameter of the invention in that the ability of the polymer material to withstand fire is directly associated with the grain size of the fire-retardant filler.
• a particularly pronounced fire-retardant effect is observed once the alumina used presents grain size that is very fine, and in particular when the particles making it up present a mean diameter that is less than one micrometer. It should also be observed that the smaller the size of the alumina oxide particles, the more the fire-retardant effect is remarkable.
• the invention as defined in this way presents the advantage of being capable of providing a polymer material that benefits from improved ability to withstand fire and good mechanical properties, compared with corresponding prior art materials.
• a material is well suited for use in making sheaths for power and/or telecommunications cables. This applies equally well to an insulating covering and to a protective sheath or a layer of cable-filler or “padding” material.
• the aluminum oxide is constituted by particles presenting a mean diameter that is less than 20 nanometers (nm).
• the composition comprises 1% to 80% by weight aluminum oxide, and preferably 2% to 20%.
• the polymer is selected from a polyethylene, a polypropylene, a copolymer of ethylene and propylene (EPR), an ethylene-propylene-diene terpolymer (EPDM), a copolymer of ethylene and vinyl acetate (EVA), a copolymer of ethylene and methyl acrylate (EMA), a copolymer of ethylene and ethyl acrylate (EEA), a copolymer of ethylene and butyl acrylate (EBA), a copolymer of ethylene and octene, an ethylene-based polymer, a polypropylene-based polymer, an imide polyether, a thermoplastic polyurethane, a polyester, a polyamide, a halogenated polymer, or any mixture thereof.
• EPR ethylene-propylene-diene terpolymer
• EVA ethylene and vinyl acetate
• EMA copolymer of ethylene and methyl acrylate
• the composition is also provided with at least one associated fire-retardant filler.
• each associated fire-retardant filler is selected from compounds containing phosphorous such as organic or inorganic phosphates, compounds containing antimony such as antimony oxide, metallic hydroxides such as aluminum hydroxide and magnesium hydroxide, compounds based on boron such as borates, carbonates of alkaline metals in groups IA and IIA such as the carbonates of calcium, sodium, potassium, or magnesium, and the corresponding hydroxide carbonates, compounds based on tin such as stannates and hydrostannates, melamine and its derivatives such as melamine phosphates, formophenolic resins, phyllosilicates such as sepiolite, attapulgite, montmorilonite, illite, chlorite, kaolinite, micas, and talcs.
• compounds containing phosphorous such as organic or inorganic phosphates
• compounds containing antimony such as antimony oxide
• metallic hydroxides such as aluminum hydroxide and magnesium hydroxide
• the composition includes 1% to 80% by weight of associated fire-retardant filler.
• the composition is also provided with at least one additive selected from the group comprising lubricants, plasticizers, temperature stabilizers, pigments, antioxidants, and ultraviolet stabilizers.
• the invention also provides any power and/or telecommunications cable having at least one insulating sheath made from a fire-resistant composition as described above. It should naturally be understood that each insulating sheath in question may also perform a protection and/or padding function.
• the invention also provides any power and/or telecommunications cable provided with at least one protective sheath made from a fire-resistant composition as described above. It should be observed at this point that each protective sheath may also perform an insulating and/or padding function.
• the invention provides any power and/or telecommunications cable provided with at least one padding layer made from a fire-resistant composition as described above. It should be observed that each layer of padding material may also perform an insulating and/or protective function.
• cables are for conveying power and/or transmitting data, they could equally well be electrical and/or optical, depending on whether the conductor elements with which they are provided are of the electrical and/or optical type.
• compositions in question were all suitable for being used for making insulating and/or sheathing and/or padding materials for energy and/or telecommunications cables.
• compositions were prepared by mixing each fire-retardant filler with an identical quantity of polymer on each occasion, in order to avoid falsifying subsequent comparative analyses; the filler content of the resulting composite remained constant.
• Reference sample 1 was prepared specifically by mixing 100 grams (g) of ethylene and vinyl acetate (EVA) copolymer containing 28% vinyl acetate, a product sold under the trademark Evatane 28-03 by the supplier Arkema, with 150 g of magnesium hydroxide sold under the name Magnifin H10 by the supplier Albemarle. That operation was naturally performed in application of the above-described procedure.
• Sample 1 is illustrative of a conventional first system providing good ability to withstand fire.
• reference sample 2 which specifically comprised a mixture of 100 g of ethylene and vinyl acetate (EVA) copolymer containing 28% vinyl acetate, 125 g of Magnifin H10 magnesium hydroxide, and 25 g of montmorillonite treated with an ammonium alkyl as sold under the name Nanofil by the supplier Sud Chemie.
• EVA ethylene and vinyl acetate
• Sample 2 relates to a second system that is well known in the prior art, and that is described in particular in patent document EP 1 033 724.
• EVA ethylene and vinyl acetate
• Sample 3 served to evaluate the fire-withstanding performance of a material containing a conventional fire retardant, magnesium hydroxide, and aluminum oxide constituted by particles of very small size.
• EVA ethylene and vinyl acetate
• Table 2 summarizes fire performance as determined using the “theradiateur”. Each test had a duration of 5 min during which the time to flaming was evaluated, which time must be as long as possible, and the mean time to self-combustion was also evaluated, which time should be as short as possible. TABLE 2 Mean time to Sample number Flaming time (s) self-combustion (s) 1 110 8.9 2 120 7.7 3 131 8.2 4 161 6.2 5 136 7.3
• reference sample 2 provides better performance than reference sample 1.
• the flaming time is longer by 10 seconds and the self-combustion time is shorter by more than one second.
• Sample 3 may be compared to sample 2 since they both contain the same conventional fire-retardant filler at identical concentrations, associated with another filler for improving performance in terms of withstanding fire. It can be seen that the time to flaming for sample 3 is longer by more than 11 seconds compared with sample 2. The use of sub-micron aluminum oxide thus achieves a considerable improvement in time to flaming without significantly affecting the self-combustion time.
• Samples 4 and 5 show that the time of flaming can be lengthened by 5 seconds to by as many as 30 seconds, while also significantly shortening the self-combustion time, compared with samples 2 and 3.

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Insulated Conductors (AREA)
• Organic Insulating Materials (AREA)
• Inorganic Insulating Materials (AREA)
• Fireproofing Substances (AREA)

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Cited By (3)

Citations (18)

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• 2005
  • 2005-08-08 FR FR0552461A patent/FR2889537B1/fr not_active Expired - Fee Related
• 2006
  • 2006-07-04 ES ES06300754T patent/ES2307274T3/es active Active
  • 2006-07-04 DE DE602006001490T patent/DE602006001490D1/de active Active
  • 2006-07-04 DK DK06300754T patent/DK1752490T3/da active
  • 2006-07-04 AT AT06300754T patent/ATE398649T1/de not_active IP Right Cessation
  • 2006-07-04 EP EP06300754A patent/EP1752490B1/fr not_active Not-in-force
  • 2006-07-05 US US11/481,406 patent/US20070031670A1/en not_active Abandoned

Patent Citations (18)

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