DURABLE AIRCRAFT GROUND PATH SIGNALING

Abstract

DURABLE GROUND PATH SIGNALING FOR AIRCRAFT An aircraft emergency guidance assembly 1 arranged to be mounted in an aircraft cabin comprises a longitudinally extending layer of photoluminescent material 2 and a housing 4 arranged to protect the photoluminescent material 2. The housing 4 comprises a polymeric cover 4a arranged to cover the layer of photoluminescent material 2. The polymeric cover 4a comprises at least 20% by mass of recycled polymer; and a biodegradable additive arranged to promote biodegradation of the polymeric cover 4a. Figure to be published with the abstract: Figure 4

Description

Title of the invention: DURABLE GROUND PATH SIGNALING FOR AIRCRAFT TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to emergency guidance assemblies for aircraft and improvements thereto. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] It is known to provide photoluminescent floor path signaling assemblies in aircraft cabins. These assemblies are typically installed on the floor of the aircraft cabin. In many cases, an assembly in the form of a track is provided along at least one side of an aisle. In most cases, a track is provided along both sides of the aisle to guide and direct passengers in the event of an emergency from their seat to an emergency exit. Aircraft emergency guidance assemblies may also include tracks or other signage on or along other surfaces, for example, cabin walls or even seats.

[0003] Known designs for aircraft emergency guidance, including products manufactured by the applicant, often have a photoluminescent insert enclosed within an extruded polycarbonate sleeve or housing. Virgin polymers (i.e., newly manufactured, typically from fossil fuel fractions / non-recycled polymers) are used to ensure compliance with stringent aerospace standards, and although these polymers are recyclable, it has been found that they are often not recycled. This is due in part to the additives and coatings (e.g., flame retardants) often required to comply with aerospace requirements, making the products potentially quite difficult to recycle, even where such a desire exists.A tough, highly transparent polycarbonate (PC) plastic is often used, which is particularly harmful to the environment and can end up in landfill for an indefinite period. The carbon footprint associated with the production of 1 kg of polycarbonate is approximately 6 kg. Standard virgin polycarbonate also uses 100% fossil fuel derivatives for its production and does not include any recycled material. It will be appreciated that other polymers may also be used, for example polymethyl methacrylate (PMMA), and similar environmental considerations apply. Summary of the invention

[0004] An object of the invention is to provide a more durable emergency guidance assembly for aircraft.

[0005] According to a first aspect of the invention, there is provided an aircraft emergency guidance assembly adapted to be mounted in an aircraft cabin, wherein the assembly comprises a longitudinally extending layer of photoluminescent material and a housing arranged to protect the photoluminescent material. The housing comprises a polymeric cover arranged to cover the layer of photoluminescent material, and the polymeric cover comprises: • at least 20% by mass of recycled material; and • a biodegradable additive.

[0006] The recycled material may be a recycled polymer, such that the polymeric cover comprises at least 20% by mass of recycled polymer. Alternatively, the recycled material may also be a polymer formed from waste monomers, such that the monomers are recycled to form a polymer.

[0007] The lid therefore includes both recycled material and is itself biodegradable, which reduces end-of-life landfill periods.

[0008] There is a bias in the art against the use of recycled materials in aircraft emergency guidance assemblies - and particularly in any portion thereof covering light emitting elements - due to strict aerospace regulations relating to light output, lifespan / durability, flammability and material traceability.

[0009] For example, virgin polymer pellets intended for aerospace typically include a flame retardant additive added by the manufacturer, so they are typically more flame retardant than typical recycled polymers, which were generally not all aerospace grade to begin with and may well not include a flame retardant additive. The recycled polymer would need to be recompounded to add the flame retardant additive. While this can be done, blending a more flame retardant virgin polymer with the recycled polymer has been found to produce a sufficiently flame resistant product without the need for recompounding, thereby reducing processing costs. Virgin polymers are also typically clearer (better light transmission).

[0010] The inventors appreciated that using a mixture of virgin and recycled materials could increase the flame retardant qualities of the material compared to using a fully recycled material, while still exploiting a significant proportion of recycled material, thereby reducing waste and reducing the carbon footprint of the product.

[0011] There is a prejudice in the art against using mixed polymer flows for a housing, however, due to imperfect mixing often resulting in inclusions / defects in the housing, this can diminish the aesthetic properties of the assembly.

[0012] When using recycled polymers, one should generally expect a mixture of different grades of the selected polymer (e.g., polycarbonate) between batches of recycled material, and even within the same batch of recycled material (materials generally flow slightly differently for different grades of polycarbonate, for example). While there is a bias in the art against relaxing tolerances due to strict aeronautical regulations, the inventors felt that a slight adjustment of the tolerances to accommodate small variations would significantly reduce the carbon footprint of the product while still meeting aeronautical requirements. Due to the possible mixture of several grades, there may also be imperfect mixing within the recycled polymer component of the lid.As mentioned above, however, there is also a prejudice in the art against the use of mixed polymer types due to imperfect miscibility resulting in inclusions / defects that may be visible to the naked eye upon examination of the final product. Even the blending of a single uniform virgin polymer with a single uniform recycled polymer has therefore not been done before.

[0013] While one might hope that the polymeric lid would be recycled, in reality this is often not the case and end-of-life products may end up in landfill or an equivalent. The biodegradability of the lid, and of the housing more generally, was therefore also taken into account by the inventors.

[0014] Most common plastics are not biodegradable - polymeric housings or prior art housings for photoluminescent aircraft emergency guidance assemblies will not decompose over time, remaining inert in landfills for centuries or even millennia.

[0015] “Biodegradable additives” are additives that increase the biodegradation of polymers by allowing microorganisms to use the carbon within the polymer chains as an energy source. Adding biodegradable additives to a polymer can influence the polymer’s degradation mechanism by changing the chemical and physical properties of the polymers to increase the rate of degradation. In particular, biodegradable additives can change the polymer degradation process into one of biodegradation – instead of the polymer being degraded only by environmental factors, such as light or heat, biodegradable additives allow polymers to be degraded by microorganisms and bacteria as well.

[0016] There are three main types of biodegradable additives:

[0017] A. Carbohydrate-based additives (e.g., starch-based)

[0018] These additives can be directly consumed by microorganisms, encouraging them to eat the material they are a part of. Microorganisms can directly attack the plastic and remove carbohydrates, leading to its degradation. Starch is a polymeric carbohydrate and a common biodegradable additive of this type. The presence of a continuous starch phase allows for direct consumption of the plastic by microorganisms as the material becomes more hydrophilic. Various mono- and poly-saccharides can also be used, among other options. These additives can help break down the long polymer chains in the plastic with which they are combined into smaller, easily degradable compounds for microbes to digest, while still being available for digestion themselves.

[0019] B. Bioaugmentation additives

[0020] “Bioaugmentation” is the direct addition of certain microbial strains to a polymeric material, which increases the biodegradability of plastics. The additive is or includes the microorganisms themselves. Bioaugmentation has been used to increase the degradability rate of already compostable plastics, but not all plastics are compostable.

[0021] C. Pro-oxidant additives

[0022] These additives increase the rates of thermo-oxidation and photo-oxidation, resulting in a greater proportion of low molecular weight compounds that can be extracted more efficiently by microorganisms. Carbon is made more available to microorganisms. Transition metal complexes, for example based on iron (Fe), manganese (Mn) and cobalt (Co), are examples of pro-oxidant additives. Heat- or light-induced oxidation (and thus fragmentation of polymer chains) would occur naturally during the degradation of a plastic in an open environment, but the presence of a pro-oxidant additive accelerates the process. There is, however, some controversy as to whether or not this type of additive leads to an increase in the production of environmentally harmful microplastics.

[0023] A given commercial additive may include a mixture of two or more of the above types. In various embodiments, carbohydrate or starch-based additives may be preferred.

[0024] In general, for aerospace applications, where a relatively long product life is desirable, carbohydrate or starch-based additives may be preferred because they do not have a significant effect on the material until it is exposed to suitable microbes, and favorable conditions (e.g., humidity levels) for those microbes - such conditions are very unlikely to occur in use, but could be present in landfill. Bio-augmentation additives can be avoided as they can cause the plastic to degrade during use. However, in many cases, microbes may be dormant until the product reaches landfill, as the right conditions (e.g., moisture levels) may not be present during use. Similarly, pro-oxidant additives can increase the rate of oxidation of the material during use, but this process can accelerate considerably in the generally warmer and more humid conditions of landfills. It will therefore be appreciated that bio-augmentation additives and pro-oxidant additives may still be appropriate.

[0025] The use of biodegradable additives therefore makes it possible to obtain a “greener” product, which is more environmentally friendly, because the polymer is made available for use by microorganisms and its residence time in landfill (if the product is not recycled) is considerably reduced. However, the use of such a biodegradable additive in a polymeric material may reduce the light transmission of the polymeric material.

[0026] This potential reduction in light transmission caused by the biodegradable additive is generally viewed as an entirely negative factor, leading to a bias in the art against the use of biodegradable additives in any layer covering a light-emitting element (such as the layer of photoluminescent material described herein). However, the inventors understood that this "frosting" or opalescence of the polymeric material due to the addition of the biodegradable additive could be used to counteract the negative aesthetic effect of using recycled materials, such as recycled polymers / mixed polymers. In particular, at the proper loading level, it was found that the biodegradable additive would frost the housing material sufficiently to visually mask defects / inclusions, while still allowing sufficient light to pass through to meet the performance requirements.The combined use of two materials previously avoided in the manufacture of such lids - recycled materials and biodegradable additives - therefore offers synergy.

[0027] Since a higher loading of biodegradable additive further reduces the light transmission of the polymer, the inventors felt that the loading should be kept at a relatively low percentage to ensure sufficient transmission and conducted extensive testing to find suitable loading levels.

[0028] An object of the invention is to provide an improved assembly that is robust, durable and meets the required performance characteristics. One of the advantages of the invention is that the housing utilizes recycled materials, thereby reducing the use of fossil fuels / petrochemicals, while achieving a assembly that meets the required performance characteristics. Another advantage is that the product itself is biodegradable, making it more environmentally friendly once its useful life is over.

[0029] It will be appreciated that in some embodiments, the assembly may be connected to additional adjacent assemblies to form a track extending along an aisle of an aircraft cabin.

[0030] The recycled material may be or comprise a recycled polymer, i.e., a material made from pre-existing end-of-life polymers or waste (e.g., industrial scrap). The polymeric cover may comprise at least 25%, 30%, 35%, 40%, 45%, 50% or 55% by mass of recycled polymer. The polymeric cover may comprise between 20% and 60% by mass of recycled polymer. The polymeric cover may comprise between 30% and 60% by mass of recycled polymer.

[0031] The recycled polymer may be recycled polycarbonate. The recycled polymer may be colorless and, optionally, may be a colorless polycarbonate.

[0032] The polymeric cover may comprise at least 45% virgin polymer. The virgin polymer may be polycarbonate.

[0033] Alternatively or in addition, the recycled material may be or include a polymer formed from monomers generated as a waste product. In embodiments in which each of the recycled materials is a polymer formed from monomers generated as a waste product rather than a recycled polymer, the polymeric lid may include more recycled material by mass than in embodiments using a recycled polymer. For example, the polymeric lid may include at least 55%, 60%, 65%, 70%, 75%, 80%, or 85% by mass recycled material. In some embodiments, the polymeric lid may include at least 88% by mass recycled material.

[0034] In embodiments wherein the recycled material is a polymer formed from monomers generated as a waste product, the polymeric lid may comprise 70-95% by mass of recycled material, optionally 75-95% by mass of recycled material, or further optionally 80-95% by mass of recycled material, or even optionally 75-90% by mass of recycled material, and further optionally 85-90% by mass of recycled material. The polymeric lid may comprise between 0.01% and 0.10% by mass of biodegradable additive. For example, the polymeric lid may comprise 85% or 88% by mass of recycled material.

[0035] The recycled material may be recycled colorless polycarbonate.

[0036] For any recycled material used for the polymeric cover, the loading of the biodegradable additive may be between 0.01% and 0.2% by mass, or between 0.01 % and 0.1% by mass (mass of the cover material), optionally between 0.09% and 0.10% by mass, and further optionally between 0.04% and 0.06% by mass. The loading of the biodegradable additive may be 0.05% by mass. The loading of the biodegradable additive may be 0.05 ± 0.0025% by mass.

[0037] In some embodiments, the loading of the biodegradable additive is between 0.01% and 0.20% by mass, and the loading of the biodegradable additive is set such that the light transmission of the polymeric cover is at least 80%.

[0038] The polymeric cover may comprise 45 to 55% by mass of recycled polymer and between 0.01% and 0.1% (and optionally about 0.05%) of biodegradable additive by mass. Such a polymeric cover may comprise 45 to 55% by mass of virgin polymer. The virgin polymer may be Makrolon® 6717, LEXAN ML3290 or a polycarbonate compliant with aerospace regulations, for example. The virgin polymer may be more flame retardant than the recycled polymer.

[0039] The polymeric cover may comprise or be made of 50 ± 5% recycled polymer, between 0.01% and 0.1% (and optionally 0.05 ± 0.0025%) biodegradable additive, and 50 ± 5% virgin polymer, by mass.

[0040] The biodegradable additive may be or comprise a carbohydrate or starch-based additive. The biodegradable additive may be a BioSphere 201 grade biodegradable additive, and may optionally be BioSphere 201J biodegradable additive. BioSphere 201J may be used at a loading of between 0.01% and 0.1% by mass, and optionally 0.05% by mass, and further optionally 0.05 ± 0.0025% by mass.

[0041] The light transmission through the polymeric cover may be at least 80%, and optionally at least 85%, of incident light.

[0042] The loading of the biodegradable additive in the polymeric cover can be adjusted by adding biodegradable additive until the light transmission through the polymeric cover drops to 90%, or 85%, of incident light.

[0043] An underside of the housing - for example, a side of the housing furthest from the cover - may be arranged to be secured to the floor of an aircraft cabin.

[0044] The cover may include at least a first area through which light emitted by the photoluminescent material is transmitted. The upper surface of the cover may include at least a second area through which light from the photoluminescent material is not transmitted.

[0045] The surface of the assembly intended to be visible during use - which is often the upper surface thereof - may be referred to as the display surface. The display surface may include first areas through which light emitted by the photoluminescent material is transmitted. The display surface may further comprising second areas through which light from the photoluminescent material is not transmitted. At least the majority of the display area may be provided by the cover.

[0046] The assembly may be adapted to be connected to, or aligned with, another assembly (and optionally several other assemblies) to form a track adapted to be installed on the floor of an aircraft cabin and extend along an aisle of the aircraft cabin.

[0047] The polymeric cover may comprise, or at least consist substantially of, one or more colorless polymers. Optionally, the one or more colorless polymers may be selected from polypropylene, polycarbonate, polymethyl methacrylate, and polyurethane. At least one of the polymers is either a recycled polymer or a polymer formed from monomers generated as a waste product.

[0048] The polymeric cover—or at least a raw material thereof—may comprise a single type of polymer, with a portion of the polymer being recycled and a portion of the polymer being virgin. For example, recycled and virgin polycarbonate may be used for one cover, and recycled and virgin polyurethane may be used for another cover, but a given cover may not mix polyurethane and polycarbonate within its raw material. Material properties may be better controlled, for example, if the materials are more miscible and / or more predictable in extrusion, when limited to a single type of polymer. Similarly, the housing may comprise a single type of polymer, at least in its raw material.

[0049] For the lid and housing, one or more coatings may be added - for example, a protective coating of polymethyl methacrylate (PMMA) on a top surface - after the part has been formed, for example, by extrusion of the raw material. It will be appreciated that these coatings may be of a different polymer type, but do not affect the extrusion properties as they are only added later; the "single polymer type" mentioned above therefore refers to the body / main material of the lid or housing, and excludes any coating applied thereto. For example, the polymeric lid comprising a single polymer type in its raw material (e.g., polycarbonate) may have a coating of a different polymer type (e.g., PMMA) applied thereto.

[0050] The longitudinally extending layer of photoluminescent material may be removable by sliding the housing. It may be necessary to cut (across the width of the housing) at least one sealed end of the housing to allow the photoluminescent layer to slide along the (longer) length of the housing.

[0051] The housing may be a one-piece housing made of the same material, with the cover being an integral part of the one-piece housing. The housing may take the form of a sleeve.

[0052] Alternatively, the housing may comprise at least two parts made of different materials, the at least two parts optionally being or comprising the cover; and a base.

[0053] The base may be located on the side of the cover away from the photoluminescent material, and optionally also along the sides of the photoluminescent material (potentially joining the cover in edge regions of the layer of photoluminescent material. The base is arranged to leave a surface of the photoluminescent material arranged to be visible in use (usually a top surface) uncovered, with the cover completing the housing. While light for charging the photoluminescent material and light emitted by the photoluminescent material to perform its afterglow function must pass through the cover, it is not necessary for this light to pass through the base. The base may have a lower light transmission than the cover.

[0054] The base may be polymeric and may comprise at least 50% by mass of recycled material. The base may comprise at least 50% by mass of recycled polymer. The percentage of recycled polymer may be higher in the base than in the lid. The base may comprise a biodegradable additive. The loading of the biodegradable additive may be higher in the base than in the lid.

[0055] According to a second aspect of the invention, there is provided an aircraft having an aircraft cabin, the aircraft cabin comprising an aircraft emergency guidance assembly as described in connection with the first aspect.

[0056] The aircraft cabin may comprise at least one track extending along an aisle of the aircraft cabin, the track comprising a plurality of emergency guidance assemblies as described in connection with the first aspect connected together. BRIEF DESCRIPTION OF THE FIGURES

[0057] The invention will now be described by way of example only with reference to the following figures in which: • [Fig.l] is a sectional view of an assembly in accordance with the invention; • [Fig.2] is a plan view of the whole of [Fig.l]; • [Fig.3] is a photograph illustrating eleven material samples different extrudates for potential use as housing in the assembly of [Fig.l]; • [Fig.4] shows a sectional view of the assembly of [Fig.l] alongside a sectional view of a similar assembly with a different housing design; • [Fig.5] is a diagram of an aircraft according to various aspects of the invention; and • [Fig.6] is a graph showing the transmission of light through housing covers with increasing bioadditive loading for incident light of 250 Lux. DETAILED DESCRIPTION

[0058] [Fig.l] of the accompanying drawings illustrates a sectional view of an emergency guidance assembly 1 for aircraft according to one aspect of the invention. The emergency guidance assembly 1 for aircraft is adapted to be mounted in an aircraft cabin. The assembly 1 comprises a layer 2 of photoluminescent material extending longitudinally and a housing 4 surrounding and protecting the photoluminescent material 2. In the embodiment shown, the housing 4 is in the form of a sleeve, or casing 4.

[0059] The assembly 1 has a height indicated by HC and a width WC, this height and this width being the external dimensions of the housing 4. In this embodiment, the height of the assembly is approximately 4 mm; in various embodiments, the height, HC, may be in the range of 1 mm to 8 mm. In this embodiment, the width of the assembly 1 is 11 mm; in various implementations, the width, WC, may be in the range of 8 mm to 40 mm, and may for example be 11 mm, 18 mm, 23 mm or 36 mm.

[0060] In the illustrated embodiment, the assembly 1 is arranged to be installed in a channel 6 of a carpet, or other floor covering material, of an aircraft cabin.

[0061] The layer of photoluminescent (PL) material 2 is surrounded by the housing 4, fitting into a space or channel therein. An upper surface of the assembly 1, in the orientation shown, is intended to be visible in use. The upper portion of the housing 4 therefore covers the PL material 2 and may be designated cover 4a - the light emitted by the PL material 2 must pass through the housing 4 - and more precisely the cover 4a - to be visible.

[0062] In the embodiment shown in [Fig.l], the height of the PL layer 2 is about 1 mm, for example 1 mm ±0.15 mm. The thickness of the package 4 on each side of the PL layer 2 may therefore be about 1.5 mm, and optionally in the range of 1.40 to 1.75 mm.

[0063] In various implementations, the height, HPL, may be in the range of 0.5 mm to 3 mm.

[0064] A carpet installed in an aircraft typically has a height of 2 mm to 6 mm. Most carpets have a height of 3 mm to 4 mm. It will be appreciated that if the height HC of the assembly 1 is greater than the height of the carpet, then the assembly 1 may present a tripping hazard. It is therefore desirable that the height HC of the assembly 1 does not exceed 4 mm. In embodiments in which the assembly 1 is mounted on a hard floor, the housing 4 may be arranged to have angled wings to reduce the potential tripping hazard.

[0065] The length of the assembly 1, Le, may be up to 2 meters (e.g. 2000 ± 2 mm) - a maximum length may be set for portability. The dotted zigzag lines in [Fig.2] are used to indicate a length which may vary greatly, for example between 10 cm and 2 m. Multiple assemblies 1 may be linked together to form a track longer than any individual assembly 1.

[0066] As shown in [Fig.2], assembly 1 has an upper surface 6 - the height HC goes from the base of assembly 1 to the upper surface 6.

[0067] It will be appreciated that the base of the assembly 1 - i.e. the underside of the housing 4 in the embodiment shown in Figures 1 and 2 - may be adapted to be able to be secured to the floor of an aircraft cabin 20 in use. The base of the assembly 1 may be secured or mounted on the floor by conventional means.

[0068] The housing 4 extending over the photoluminescent material 2 is formed of a scratch-resistant, flame-retardant and at least partially transparent or translucent material.

[0069] In the described embodiment 1, the housing 4 is in the form of a sleeve and is formed by extrusion. The layer of PL material 2 may be co-extruded within the sleeve 4, or may be slid into position within the sleeve 4 after the sleeve has been formed. Preferably, the sleeve 4 is continuous around its cross-section, with only the openings being at each end. The sleeve 4 may be sealed once the PL material 2 is correctly positioned therein, optionally using a UV-cured adhesive to provide a hermetic seal.

[0070] In the embodiment 1a shown in [Fig.4] alongside an image of the embodiment 1 described above, the sleeve housing 4 is replaced by a different kind of housing 4, comprising two parts 4a, 4b arranged to be connected together. In particular, the housing 4 of this embodiment 1a comprises a cover 4a which lies above the PL layer 2 (in the orientation shown), covering it, and a base 4b lying below the PL layer 2 (in the orientation shown), and also enclosing the sides of the PL layer 2. The cover 4a and the base 4b are glued together to form the housing 4 which encloses the PL layer 2. In other embodiments, the cover 4a may include portions extending around the sides of the PL layer 2, and the base 4b may be at least substantially flat. A multi-part housing with more than two parts 4a, 4b may be provided in other embodiments, for example with separate side portions arranged to join a cover 4a to a base 4b and to protect the sides of the PL layer 2.

[0071] It will be appreciated that the light used to charge the PL material 2 and the light emitted by the PL material 2 must both pass through the portion of the housing 4 covering the PL layer. In the first embodiment 1 described above, the housing 4 is a single-piece package 4, both made of the same material; the selected material is chosen for its good light transmission properties, among other requirements. In contrast, in the second embodiment 1a described, the different portions 4a, 4b of the housing 4 may be made of different materials - only the cover 4a needs to have good light transmission properties.While base 4b may have the same requirements in terms of flammability, temperature resistance and, optionally, durability (although it will be appreciated that base 4b may be better shielded against impact during use), the optical properties may be less strictly controlled. In particular, a higher percentage of recycled material may be used for base 4b (optionally with added flame retardant) and / or a higher loading of biodegradable additive may be used (as opalescence of the material is not a problem). Base 4b may be made of 100% recycled material (with any optional additives). It will be appreciated that the properties of cover 4a and base 4b, such as thermal expansion / contraction, may be carefully tuned, while allowing for differences in optical properties.

[0072] The housing 4 and the cover 4a are each made of polycarbonate in the described embodiment. In particular, in this embodiment, the material of the housing 4 is a mixture of recycled and virgin polycarbonates and the recycled material is therefore a recycled polymer, and more specifically recycled polycarbonate - more specifically composed of 50% Makrolon® 6717 (virgin polycarbonate suitable for aerospace) and 50% re-shredded polycarbonate (recycled polycarbonate). It will be appreciated that different virgin polymers, for example LEXAN ML3290, may be used in other embodiments.

[0073] In alternative or additional embodiments, the recycled material is or includes a polymer derived from monomers considered waste or processing residues from other industrial or chemical processes. Unlike standard virgin polymers which use 100% fossil fuel derivatives for their production and do not include any material Recycled polymers made from waste monomers do not use additional fossil fuel resources, but instead recover monomers that would otherwise end up in landfills or pollute the environment. The recycled material can therefore be a recycled polymer (formed from waste polymer material, without excessively breaking the polymer chains) or a polymer made from waste monomers (forming new polymer chains). The waste polymer or monomer can be a by-product of an industrial process, pre-consumer waste (e.g., manufacturing scrap), and / or post-consumer waste. In some cases, the term "recycled polymer" may be used to refer to a recycled material formed from either of these two options, but a distinction is made here for clarity.A mixture of recycled polymer(s) and polymer(s) made by recycling monomer waste may be used in some embodiments.

[0074] In order to meet the aerospace industry's requirements for material traceability, recycled polycarbonate consists of product manufacturing offcuts / surplus (industrial waste that would normally be discarded / sent to landfill) as opposed to post-consumer waste; therefore, batch numbering and recycled polymer recording can be implemented, with each batch of re-shredded material being assigned its own part and batch numbers. Due to the nature of re-shredded material, it is often impossible to determine its exact composition. However, all possible grades of polycarbonate (or other polymer, as appropriate) that could be included can be noted for each batch, and the lowest-performing grade against a given aerospace requirement can be used as the limiting case for testing.For example, in a batch of recycled polycarbonate, Calibre 6303 / 3 grade may be the least flame retardant polycarbonate that can be included in the re-shredded material. Therefore, a sample composed of 50% Makrolon® 6717 and 50% Calibre 6303 / 3 re-shredded polymer can be used as a test sample for flammability requirements. A different sample can be used to test another characteristic for which Calibre 6303 / 3 grade is not the lowest.

[0075] It has been found that the use of re-shredded polycarbonate nevertheless increases the likelihood of inclusions / defects forming in the extruded sleeve 4, due to the different flow properties. Inclusions typically form when molten plastic is compressed and folds back on itself - this can be corrected, for example, by adjusting the distance between the extruder barrel and the dyeing tool, but the correct combination of distance, flow rate and temperature (among other factors) may vary from batch to batch when recycled materials variables are used, which means that one cannot rely on a single setting and more imperfections are likely to go unnoticed.

[0076] Re-shredded material is generally uneven in size compared to virgin grade pellets, and therefore has the potential to melt unevenly in the extruder and subsequently cause malformations in the extruded shape, even if the composition of the material is uniform. Since this material has generally already been extruded once, it is possible for the polycarbonate to discolor when re-extruded.

[0077] Using a frosting agent to mask these inclusions / defects is one option to improve aesthetics - however this would detrimentally reduce light transmission, so a balance between aesthetics and luminance must be found.

[0078] It has been found that careful use of a biodegradable additive, with careful testing and loading control, can provide sufficient frosting effect to mask inclusions while still allowing sufficient light to pass through for the assembly to fulfill its purpose, also increasing the durability of the product.

[0079] In the described embodiments, with 50% Makrolon® 6717 and 50% re-shredded polycarbonate, it was found that a loading of 0.05% (by mass) of a biodegradable additive Biosphère would adequately frost the assembly 1 so as to conceal the inclusions while maintaining a light transmission greater than 80% of the incident light (in the 250 Lux and 40 Lux tests).

[0080] Marginal color distortion of Set 1 was noted - this can be compensated for in a printing process to match the desired color of the finished product if necessary.

[0081] A variety of combinations were tested before arriving at this combination of materials and additive loading, for example as shown in Table 1. Each sample was subjected to a flammability test (to check fire resistance) and a Lux test (to check light transmission).

[0082] For the flammability test, each sample was tested to see if it met the flammability requirements of EASA (European Aviation Safety Agency) and FAA (Federal Aviation Administration) as specified below: • Horizontal test: CFR / CS-25.853(a) App. F Part I (a)(1)(iv) • The flame must be applied for 15 seconds and then removed. The material cannot have an average burn rate greater than 64 mm (2.5 in) per minute when tested horizontally. • Vertical test: CFR / CS-25.853(a) App. F Part I (a)(l)(ii) • The flame must be applied for 12 seconds and then removed. The material must be self-extinguishing when tested vertically. The average burn length cannot exceed 20 cm (8 inches) and the average flame time after removal of the flame source cannot exceed 15 seconds. Drippings from the test piece cannot continue to burn for more than 5 seconds on average after falling.

[0083] For the light transmission test, the samples were tested to determine if enough light could pass through the material to allow the PL material to charge and the PL luminance to be seen. The requirements are specified below: • Measure the effect of the track on light transmission with 250 Lux and then with 40 Lux. The track must not reduce light transmission by more than 20%: • Exposure to 250 lux: measurement: not less than 200 lux; • Exposure to 40 lux: measurement: not less than 32 lux.

[0084] [Table 1] Table 1 - Housing materials Number Composition Extruded Product Notes Flame Test Light Transmittance Test Control 100% Makrolon® 6717 Standard - transparent extruded; good light transmittance Pass Pass 1 Makrolon 6717 + 1% Biosphere biodegradable additive ("Biosphere") White appearance - unacceptably reduced light transmittance Pass Fail 2 Makrolon 6717 + 0.5% Biosphere Translucent white - unacceptably reduced light transmittance Pass Fail 3 Makrolon 6717 + 0.1% Biosphere Slight loss of light transmittance,potentially acceptable light transmission Pass Pass 4 Mitsubishi Durabio D3740IR Completely opaque white appearance - unacceptably reduced light transmission Fail Fail 5 LG ER1000MH-NP 60% Post-Consumer Recycled (PC CR) Clear Extruded - good light transmission Fail Pass 6 LG ER1000MH-NP 60% PC PCR + 1% KSS-FR Flame Retardant (“KSS-FR”) Slightly milky extruded, acceptable light transmission Pass Pass 7 LG PC1300LZ-10 Mass-Balanced PC Clear Extruded - good light transmission Fail Pass , 8 LG PC1300LZ-10 Mass-balanced PC + 1% KSS-FR Extruded very slightly milky, light transmission likely to be acceptable Pass Pass 9 50% Makrolon 6717 + 50% re-shredded clear polycarbonate Extruded clear - good light transmission, but inconsistent particle size of re-shredded material causes white streaks in extruded material Pass Pass 10 Makrolon 6557 RE Mass-balanced PC Extruded milky with bubbles inside - light transmission potentially acceptable, but bubbles are a risk for low pressure (aerospace) use Pass Pass

[0085] [Fig.3] is a photograph of these eleven samples, arranged with the sample witness at the top and in numerical order from (1) to (10) thereafter.

[0086] As can be seen, even at a loading of only 0.1% virgin aerospace polymer, the presence of the biodegradable additive Biosphère produced a frosting effect, reducing light transmission.

[0087] Samples that failed one or both tests were then discarded, leaving the control and samples 3, 6, 8, 9 and 10. These samples were then subjected to further tests for other requirements, including wear resistance (both to trampling and to movement of the galley trolley), temperature resistance and fluid resistance, and each was found to comply with the required standards. The samples were also tested for print adhesion, for aesthetic purposes.

[0088] Of these, samples (6) - 60% post-consumer recycled polymer - and (9) - 50% recycled polymer from re-shredded industrial waste - have the greatest impact on sustainability in terms of manufacturing. However, the addition of a flame retardant was necessary for sample (6) to pass the flame resistance test. This additive reduces light transmission to some extent, so the addition of a biodegradable additive could also reduce too much strongly the light transmission. Sample (9) was therefore chosen as the starting point for testing the use of the biodegradable additive.

[0089] As can be seen in Table 2 below, using a loading of 0.1% Biosphère biodegradable additive with 50% Makrolon 6717 + 50% re-shredded polycarbonate (Sample D, below) as opposed to 100% Makrolon 6717 (Sample 3, above) caused the sample to fail the light transmission test - lower loadings were therefore tested to achieve the desired light transmission. Frosting with a frosting agent (Sample E) was also found to be suitable for masking inclusions, but without the durability benefit of the biodegradable additive.

[0090] [Table 2] Table 2 - Additive loading test Number Composition Flame Test Lux Test Pass / Fail Lux Test Light Transmission Control 100% Makrolon 6717 Pass Pass 89.6% A 50% Makrolon 6717 + 50% Caliber 603 / 3 Pass Limit case test for flame test only B 50% Makrolon 6717 + 50% re-shredded polycarbonate Pass Pass 89.2% C 50% Makrolon 6717 + 50% re-shredded polycarbonate + 0.05% Biosphere biodegradable additive Pass Pass 86.8% D 50% Makrolon 6717 + 50% re-shredded polycarbonate + 0.1% Biosphere Pass Fail 76.6% E 50% Makrolon 6717 + 50% re-shredded polycarbonate + 1% LumiPlas LD7820 icing agent Pass Pass 86.4%

[0091] The use of 50% recycled (re-shredded) polycarbonate with virgin polycarbonate (in this case Makrolon® 6717, although it will be appreciated that other aerospace-compliant polycarbonates may be used in other applications) has therefore proven effective. Both polycarbonates are colorless and therefore do not affect the color of incoming or outgoing light.

[0092] In other implementations, another suitable type of polymer may be used. For example, polymethyl methacrylate, polyurethane, or polypropylene may be used for the cover 4a. A suitable polymer may have good light transmission, be flame retardant, be durable / robust, and have good light transmission. Colorless polymers may generally be preferred, although a colored layer may be preferred in some implementations, for example, to create a desired surface color in use.

[0093] In most implementations, the polymeric cover 4a comprises only polymers of a single type—for example, just polycarbonates or just polyurethane—with a portion of the material being recycled and a portion of the material being virgin. Avoiding mixing polymer types can facilitate control of material properties, both during manufacture (for example, by improving miscibility) and in use (for example, by ensuring better matching of expansion coefficients with temperature changes). However, it will be appreciated that certain mixtures of polymer types may be suitable for reliable and predictable extrusion, for example, certain polycarbonate / PMMA mixtures. Those skilled in the art would therefore appreciate that avoiding mixtures of polymer types is a general guideline rather than a hard and fast rule.

[0094] In various implementations, the polymeric lid 4a may comprise less recycled polymer by mass than the 50% mentioned above - for example, about 25%, 30%, 35%, 40% or 45%. In other implementations, the polymeric lid 4a may comprise at least 50% by mass of recycled polymer, and may optionally comprise at least 55% by mass of recycled polymer. In various implementations, the polymeric lid 4a comprises at least 40% or 45% by mass of virgin polymer, and may comprise 50 ± 10% or 50 ± 5% by mass of virgin polymer. In various implementations, the polymeric lid 4a comprises at least 40% or 45% by mass of recycled polymer, and may comprise 50 ± 10% or 50 ± 5% by mass of recycled polymer.

[0095] In the embodiment shown in [Fig. 1], the housing 4 is a one-piece housing 4, with the cover 4a being integral with the rest of the housing 4 - the housing 4 effectively forms a sleeve surrounding the photoluminescent (PL) layer 2. The entirety of the housing 4 is made of the same material in such embodiments. In other embodiments, such as that shown in the right-hand portion of [Fig. 4], the housing 4 comprises several parts, for example two separable parts: • (i) the cover 4a arranged to be located above the layer PL 2; and • (ii) a base 4b arranged to lie below the PL 2 layer.

[0096] It will be appreciated that the terms “above” and “below” are defined herein with respect to a typical orientation of a ground path sign in use, where the upper face of the guidance assembly 1 is the face intended to be seen by users. The cover 4a may therefore be described as providing a presentation surface, independent of orientation, with the base 4b lying on the side of the PL 2 layer remote from the cover 4a, and optionally joining the cover 4a at the edges of the PL 2 layer.

[0097] In the second embodiment shown in [Fig. 4], the side of the PL layer 2 is enclosed by portions of the base 4b. In other embodiments, the cover 4a may be curved downward to protect the sides, and / or separate side pieces of the housing 4 may be provided. In still other embodiments, the cover 4a itself may be split into multiple pieces. In embodiments in which the housing 4 comprises multiple parts, one or more of the parts may be made of different materials. For example, in some embodiments, the percentage of recycled polymer and / or the loading of the biodegradable additive may be higher in the base 4b (and optionally in any side pieces) than in the cover 4a.For example, one or more parts of the housing 4 other than the cover 4a may comprise at least 50%, 55%, 60%, 65%, 70% or 75% by mass of recycled polymer, and may optionally be made of 100% recycled polymer (i.e., entirely recycled polymer, except for small percentages of possible additives). The optical property requirements are generally more stringent for the cover 4a than for the base 4b (and any side pieces of the housing 4), which allows the use of a less transparent material for the base.

[0098] The loading of the biodegradable additive in the base 4b (and optionally in any side piece of the housing 4) may be much higher than that of the cover 4a, for example by a factor of ten, twenty or fifty. For example, the loading of the biodegradable additive in the base 4b may be approximately 1%, 1.5%, 2% or 2.5% by mass of the polymeric part 4b.

[0099] In the lid 4a, the loading of the biodegradable additive is generally kept lower to ensure sufficient light transmission / minimal light blocking of the lid material, thereby allowing the PL layer 2 to be charged by incident light without hindrance, and allowing the PL glow of the material 2 to pass through the coating 4a without hindrance.

[0100] In particular, in various embodiments, the light transmission through the polymeric cover 4a is at least 80%, and optionally at least 85%, of incident light (which may be light from the daylight spectrum, or at less light in the range(s) of absorption by the photoluminescent material and emission by the photoluminescent material). For example, when exposed to 40 lux light on a first surface of the cover 4a, at least 32 lux must emerge from the opposite face of the cover 4a. In various embodiments, the loading of the biodegradable additive in the polymeric cover 4a may be fixed by adding biodegradable additive until the light transmission through the polymeric cover drops to 95%, 90%, 85% or 80% of incident light. The threshold may be set higher (higher transmission) when a colored film or printed pattern is to be used on or near the cover 4a, to ensure sufficient light transmission even when another component blocks some of the light.

[0101] In the examples described above, the selected biodegradable additive is a BioSphere 201 grade biodegradable additive, and more specifically is BioSphere 201 J biodegradable additive. In other implementations, a different biodegradable additive may be used, for example, one or more of the products available from EcoPure®. It will be appreciated that the choice of additive may depend on the particular polymer(s) of the housing 4, among other factors, and that any suitable additive may be used provided that compliance with applicable aerospace requirements is assured.

[0102] The loading of the biodegradable additive in the housing 4, or at least in the cover 4a, is 0.05% by mass in some embodiments, and may be 0.05 ± 0.0025% by mass of biodegradable additive. In other embodiments, a loading of at least 0.02% and at most 0.20%, and optionally at most 0.12%, may be used, the loading optionally ranging from 0.03% to 0.10% or from 0.04% to 0.09%. A compromise between biodegradation rate and light transmission of the material may be considered when fixing the loading. Higher loading of the biodegradable additive (or "bio-additive", for brevity) may be possible for the same light transmission when the percentage of virgin polymer is higher (because the polymeric material itself may be more transparent, thus allowing for greater opalescence due to the additive while still meeting optical performance targets).The partial light blocking due to the bio-additive also advantageously ensures a certain frosting which can conceal cosmetic imperfections due to the use of a recycled material.

[0103] [Fig.6] is a graph 600 showing the light transmission through polycarbonate housing covers 4a with 50% virgin polycarbonate derived directly from fossil fuel sources / not monomer waste (Makrolon® 6717), 50% recycled polycarbonate and increasing bio-additive loadings (from 0 to 1% by mass of BioSphere 201 J biodegradable additive) for an incident light of 250 Lux. Initial tests indicate that the effects on light transmission / opalescence are similar for various currently commercially available bioadditives, so data for this additive only are provided as an example.

[0104] As can be seen from graph 600 of [Fig. 6], the light transmission of the resulting polymeric material drops quite rapidly initially as the loading of the biodegradable additive is increased from zero, with the rate of loss of light transmission with increasing loading decreasing as the loading increases. A dotted line 602 indicates 85% of the incident 250 lux (212.5 lux), which is set as the threshold in this example. A 0.10% loading of bioadditive caused the transmission to drop just below the set threshold, so a lower loading would be selected to meet the optical requirements of the cover 4a.

[0105] In embodiments in which the aircraft emergency guidance assembly 1 is used as ground path signaling, an underside of the housing 4 (e.g., the base 4b) is arranged to be secured to the floor of an aircraft cabin 20. Light transmission through the base 4b may therefore be unimportant—an opalescent, or even opaque, material may therefore be used for the base 4b when the base 4b is a separate part of the cover 4a (although it will generally be firmly attached thereto, either directly or via interposing side portions of the housing 4). Even in embodiments in which the base and cover are integrally formed to form a single housing, the composition of the material may vary between the base and cover, for example, by careful coextrusion of two or more materials, or by any suitable technique known in the art.

[0106] In such embodiments, the assembly 1 is generally adapted to be connected to another assembly 1 to form an elongated track adapted to be mounted on the floor of an aircraft cabin 20 and to extend along an aisle 21 of the aircraft cabin towards an emergency exit.

[0107] In various embodiments, a lower surface of the housing 4 (e.g., a side of the base 4b furthest from the lid 4a in multi-part housings) is printed with an image or pattern, for example to label the product name, type, size, batch number, and / or other details. The base 4b / lower part of a one-piece housing 4 may be made entirely opaque by such printing in some of these embodiments. Particularly in embodiments in which the housing 4 is one-piece, the entire surface of the housing 4 may therefore be arranged to be suitable for use as a printing substrate.

[0108] In various embodiments, the lid 4a may include at least a first area through which light emitted by the photoluminescent material 2 is transmitted and at least a second area through which light from the photoluminescent material 2 is not transmitted. For example, edges of the lid 4a may not have any PL light passing through them due to the configuration, and / or one or more portions of the lid may be rendered opaque—for example, by indicia printed thereon or a substance embedded within the polymeric lid 4a—while leaving a transparent area sufficient to provide the desired glow and light access for charging the PL material 2.In embodiments in which light transmission through one or more portions of the cover 4a is blocked, the light transmission threshold of the material used to form the cover may be higher than in embodiments in which the entire area of ​​the cover 4a must be available for light transmission.

[0109] In some embodiments, particularly in embodiments with sleeve-like housings 4, the longitudinally extending layer of photoluminescent material 2 is removable from the housing 4 by sliding - the PL layer 2 in these embodiments may also be inserted by sliding during the manufacture of the assembly 1, and may be described as an "insert". The "insert" 2 and the "sleeve" 4 may therefore be readily separated for recycling or reuse. It will be appreciated that one or both ends of the assembly 1 may be hermetically sealed before use (optionally sealed, or sealed to an adjacent assembly so as to form a longer track, optionally with an adhesive - which may be cured - or with localized melting of the polymeric housing 4), and that any end sealed in this way may be cut off before removing the insert.

[0110] In embodiments with other housing 4 designs, the assembly and disassembly approaches may vary - for example, a hood-like cover 4a may be lifted from a base 4b (optionally after dissolving or cutting an adhesive or other seal holding one part to the other) and the PL material 2 may be lifted or tilted once the housing 4 has been opened.

[0111] In various implementations, as noted above, the assembly 1 extends longitudinally (being elongated) and may be adapted to be connected to another assembly to form a track 26 which may be installed on the floor of an aircraft cabin 20 and extend along an aisle 21 of an aircraft cabin.

[0112] [Fig. 5] is a schematic illustration of an aircraft 22 comprising an aircraft cabin 20 and a number of assemblies 1 connected together to form a runway 26 extending along an aisle 21 of the cabin and arranged to guide a passenger from a seat to one or more emergency exits 28. The track 26 may guide passengers around or past one or more interior walls or partitions 24.

[0113] As illustrated in [Fig.5], the assembly 1 is intended to be used in a cabin 20 of an aircraft 22. The assembly 1 may be adapted to be secured to the floor of the cabin 20, for example along an aisle 22 and / or between the rows of emergency exit seats.

[0114] An assembly 1 according to the invention has been found to be robust and durable. The rigorously tested assembly 1 has been found to meet each of the stringent performance requirements for an emergency exit panel in an aircraft cabin, even though various features - in particular the use of a biodegradable additive, the use of recycled material and / or the use of mixed polymeric materials to form a polymeric layer - run counter to long-standing prejudices in the art.

[0115] It has been found that the use of materials as described herein makes it possible to considerably reduce the quantity of virgin material required and therefore to reduce the environmental impact of the assembly. Furthermore, the cover 4a according to the invention, and optionally the entire housing 4, is biodegradable, which reduces the environmental impact at the end of life of the assembly 1.

[0116] The upper surface 6 of the assembly 1 may be used to show one or more patterns or images, for aesthetic and / or safety reasons - for example, one or more arrows indicating an exit direction, and / or a pattern corresponding or complementary to the carpet or other floor covering of the aircraft may be provided. The housing 4 may therefore be used as a substrate on which such patterns or images may be printed. Alternatively or in addition, an upper surface of the PL layer itself may be printed to form a desired pattern or symbol (optionally with an opaque ink), and / or a film may be inserted between the PL layer and an underside of the cover 4a, and this film may be a colored or colorless film (provided it is not opaque), and may be patterned or printed thereon.

[0117] It will be appreciated that the upper surface 6 must be traversed by light. In some embodiments, the upper surface 6 of the assembly 1 comprises at least a first area through which light emitted by the photoluminescent material is transmitted and optionally comprises at least a second area through which light from the photoluminescent material is not transmitted. In some of these embodiments, an opaque ink may be used to form one or more patterns or images, and the opaque ink may not cover the entire surface 6. The opaque ink may be applied to the housing 4, the PL layer and / or to a film inserted between the two, in various embodiments.

[0118] In other or additional embodiments, an ink or other material used to form the printed pattern or image may itself be transparent (e.g., colorless or transparently colored) or translucent. In such embodiments, the ink may cover the entire surface 6.

[0119] The polymeric material used to manufacture the housing 4 described herein has been found to be suitable for extrusion, and the resulting assembly 1 has been found to meet the requirements of flammability, light transmission, fluid exposure, footwear exposure, temperature range tolerance, and pressure range tolerance for use in an aircraft cabin. In addition, the material of the housing 4 has been found to be suitable for coating and print adhesion, resulting in aesthetics and surface finishes equivalent to those of prior materials. Thus, embodiments of the invention provide improved durability for aircraft emergency guidance assemblies while maintaining each of the required and desirable properties.

[0120] In the embodiments described in detail above, the recycled material is a recycled polymer, i.e., the polymeric material pre-existed, having been manufactured for a use other than that intended, then processed and used to form the polymeric cover. The recycling process typically includes shredding or grinding the virgin (or previously recycled) polymer, washing it (before or after grinding), and reforming the material into the desired shape. The same polymer chains are reused. The virgin (or previously recycled) polymer may be reprocessed by any suitable recycling method. These recycling methods include, but are not limited to, mechanical processes such as shredding, grinding, or melting.

[0121] In some alternative or additional embodiments, the material of the housing 4 is made from polycarbonates formed from monomers generated as waste, and is optionally a blend of virgin polycarbonates made directly from fossil fuel sources and polycarbonates formed from such waste monomers (thus recycling the monomers to make new polymers). In these embodiments, the recycled material is therefore, or includes, a polymer derived from monomers considered waste or processing residues from other industrial or chemical processes. For example, the recycled material may be Makrolon® 6557 or Makrolon® LED5902 FR RE, or another polymeric material formed from bio-circular monomer feedstocks or the like, while having suitable mechanical properties and light transmittance.The polymer formed from these waste monomers can be formed with a granule size. standard, which reduces or avoids problems associated with varying pellet sizes when working with recycled polymers.

[0122] Monomers, which would otherwise have been discarded, can be recovered and purified for use in new polymerization reactions. New polymer chains are created from the same monomers. The recovered monomers can be waste of biological origin such as agricultural, forestry or other related industrial waste. Monomers can be recovered from the biodegradable fraction of industrial and municipal waste.

[0123] It will be appreciated that, aside from the origin of the recycled materials, the particularities and requirements of embodiments using recovered monomers may be generally the same as those of embodiments using reclaimed polymers as described above. In addition, some embodiments may use a mixture of both types of recycled materials to provide all or part of the polymeric component of the lid.

[0124] An increase in the proportion of recycled material (and a corresponding reduction in the proportion of polymer derived directly from fossil fuels) within the polymeric cover can typically reduce the transmission of light through the polymeric cover. As discussed above, an increase in the proportion of biodegradable additive in the polymeric cover can further reduce the transmission of light through the polymeric cover.

[0125] In some embodiments, recycled materials made from reclaimed monomers and new polymerization processes may be more transparent than directly recycled polymers, and a higher percentage of the recycled material may therefore be usable without light transmission decreasing below acceptable levels.

[0126] For example, embodiments of the polymeric lid in which the recycled material is a polymer formed from monomers generated as a waste product may contain up to 85% by mass recycled material, and for example 70-85%, 75-83% or 80-85% by mass recycled material.

[0127] In alternative embodiments, wherein the recycled material is a recycled polymer, the polymeric cover may have a lower loading of recycled material, e.g., up to 55% by mass of recycled material.

[0128] For either type of recycled material, or any combination of recycled materials, (i) the loading of the biodegradable additive, and (ii) the proportion of recycled material, may be controlled such that the light transmission of the polymeric cover is at least 80%. Typically, the loading of the additive may be decreased as the proportion of recycled material is increased.

[0129] It will be appreciated that the embodiments described in detail herein are given by way of illustrative example only, and are not intended to be limiting.

Claims

Claims

1. An aircraft emergency guidance assembly arranged to be mounted in an aircraft cabin, wherein the assembly comprises a longitudinally extending layer of photoluminescent material and a housing arranged to protect the photoluminescent material, the housing comprising a polymeric cover arranged to cover the layer of photoluminescent material, and wherein the polymeric cover comprises: - at least 20% by mass of recycled material; and - a biodegradable additive, with a loading of the biodegradable additive of between 0.01% and 0.20% by mass, and wherein the loading of the biodegradable additive is set such that the light transmission of the polymeric cover is at least 80%.

2. An aircraft emergency guidance assembly according to claim 1, wherein the recycled material is a recycled polymer, and wherein optionally the polymeric cover comprises at least 25% by mass of recycled polymer.

3. An aircraft emergency guidance assembly according to claim 1, wherein the recycled material is a polymer formed from monomers generated as a waste product, and wherein, optionally, the polymeric cover comprises at least 55% by mass recycled material.

4. An aircraft emergency guidance assembly according to any preceding claim, wherein the polymeric cover comprises at least 45% virgin polymer, the virgin polymer optionally being polycarbonate.

5. An aircraft emergency guidance assembly according to any preceding claim, wherein the loading of the biodegradable additive is between 0.01% and 0.10% by mass, and is optionally 0.05% by mass.

6. An aircraft emergency guidance assembly according to claim 2 taken alone or in combination with one of claims 4 or 5, wherein the recycled material is a recycled polymer, and the polymeric cover comprises from 45 to 55% by mass of recycled polymer and between 0.01% and 0.10% by mass of biodegradable additive.

7. An aircraft emergency guidance assembly according to claim 3 taken alone or in combination with either of claims 4 or 5, wherein the recycled material is a polymer formed from monomers generated as a waste product, and the polymeric cover comprises 70 to 95% by mass of recycled material, and optionally 75 to 90% by mass of recycled material, and between 0.01% and 0.10% by mass of biodegradable additive.

8. An aircraft emergency guidance assembly according to any preceding claim, wherein the light transmission through the polymeric cover is at least 85% of incident light.

9. An aircraft emergency guidance assembly according to any preceding claim, wherein the assembly is adapted to be connected to a further assembly to form a track adapted to be installed on the floor of an aircraft cabin and to extend along an aisle of an aircraft cabin.

10. An aircraft emergency guidance assembly according to any preceding claim, wherein the polymeric cover comprises one or more colorless polymers selected from polypropylene, polycarbonate, polymethyl methacrylate and polyurethane, and wherein at least one of the polymers is either a recycled polymer or a polymer formed from monomers generated as a waste product.

11. An aircraft emergency guidance assembly according to any preceding claim, wherein the housing is a one-piece housing made of the same material, the cover being an integral part of the one-piece housing, and wherein, optionally, the housing takes the form of a sleeve.

12. An aircraft emergency guidance assembly according to any one of claims 1 to 10, wherein the housing comprises at least two parts made of different materials: - (i) the cover; and - (ii) a polymeric base comprising at least 50% by mass of recycled material and a biodegradable additive, and wherein, optionally, the loading of the biodegradable additive is higher in the base than in the cover. 30

13. An aircraft having an aircraft cabin comprising an aircraft emergency guidance assembly according to any preceding claim, wherein the aircraft cabin comprises at least one track extending along an aisle of the aircraft cabin, the track comprising a plurality of emergency guidance assemblies according to any one of claims 1 to 12 connected together.

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