GB2527314A

GB2527314A - Runner system

Info

Publication number: GB2527314A
Application number: GB1410769.2A
Authority: GB
Inventors: Daniel Alan Rust; Benjamin Kimberlin Mccallum Brown
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-06-17
Filing date: 2014-06-17
Publication date: 2015-12-23
Also published as: GB201410769D0

Abstract

The application relates to a material for use in luminescent floor path markings and guidance. The said material comprises of a sheet 2 that has been doped with photo luminescent pigments, preferably Strontium Aluminate. This sheet is then encapsulated in another sheet 1 preferably made out of polycarbonate. The sheet is preferably formed by co-extrusion. The sheet is preferably in the form of a strip or runners which can be installed in aircraft floors to serve as emergency exit way guidance. The outer layers 1 of polycarbonate themselves may be doped to provide different effects and colours.

Description

Runner System.

Background

The use of photo luminescent runner strips for the purpose of way guidance cn aircraft is well known from such patents as EP0828657 Bl, EPl7S3000 Al, EP1970100 Al and W01998004645 Al.

Photo luminescent runners are placed in pre-determined layouts on aircraft floors to provide way-guidance in the case of egress where normal lighting is not available or not effective at floor level. These runner systems, or equivalent electrical systems, are mandated by regulation on all commercial aircraft.

Photo luminescent runners are charged by light (namely that from the cabin lighting system and natural light through the cabin windows) and then proceed to discharge their energy as visible light when the charging light source goes away.

The principle methods of manufacture involve either (I) layering photo luminescent pigments (here after referred to as pigments' or simply pigment' ) on to a substrate (perhaps using screen printing -see "The Screen Printer's Guide to Photoluminescence", Marina Batzke, American Permalight Inc., Screen printing, September 1997) or (ii) preparing a photo luminescent base material mix (such as silicon and Strontium Aluminate, from EP1987861 Al and WC1998004645 Al) and injecting, extruding or otherwise encapsulating this material inside or under a sleeve or track. The photo luminescent pigment is widely known to be highly sensitive to water, causing rapid degradation and failure (also highlighted in the teachings of a white paper from a manufacturer highlighting this issue and the steps taken to date to combat it) Citing patents SF1987861 Al and W01998004645 Al as examples combined with the teachings of marketing literature from leading suppliers of photo luminescent floor path marking systems, this is a major consideration in the design and manufacture of such systems. Moreover, during installation of photo luminescent floor path marking systems, the installer has to perform cuts and joins to allow the system to fit the aircraft. These processes may be outside the control of the designer and manufacturer of the product, meaning actions occur that degrade the fluid protection of the design, leading to early in-service failures.

In the known production method where a silicon and pigment mix base material is prepared as an alternative to layering onto a substrate and is then injected or extruded into a protective sleeve or track (from CA2717003 C), some of the problems of fluid ingress are overcome as the silicon and pigment base material becomes self-sealing' (as professed in common marketing literature) but clearly the manufacturing method involves preparatory steps and an additional base material (silicon) to create the pigmented material mix which will increase costs.

The problem therefore exists that a photo luminescent system is needed that protects the photo luminescent pigment from water and mechanical damage, can be easily installed on an aircraft (which will reguire fresh cuts to manufactured lengths) yet does not create lengthy and costly production steps to achieve this.

Statement of invention

To overcome the problems of conventional systems, the present invention is a single piece extruded plastic profile with a pigment doped region that can be produced in a single production step, and due to its construction is completely immune to fluid ingress. There are no materials other than the photo luminescent pigment and the outer encapsulation material, which in the preferred embodiment is polycarbonato, used in the process, providing advancement over methods involving further carrier or encapsulation materials such as silicon.

The closest relating prior art exists in CA2717003 C which addresses many of the problems faced by photo luminescent floor path marking systems but requires the addition of silicon and the possibility of further production steps to achieve the end result.

Advantages The construction resembles a hermetically sealed photo luminescent system which cannot be susceptible to fluid ingress initially, following cutting or even after breaking, and thereby alleviates difficulties during installation and degradation resulting from in-service damage, such as impact from passenger footwear and baggage. The vastly reduced materials count reduces production cost and tho li]cclihood of supply chain issucs in procurement.

A significant advantage to the end user is the reduced production costs and speed of manufacture that make the end product cheaper and faster to procure in high volumes. This reduction is the result of reducing the manufacturing process to a single step; plastic extrusion. Using this method, the profile may be produced by any one of a large number of existing plastic extrusion companies, without special training and at a high throughput, as is the case with all plastic extruded parts such as plastic pipes far the construction industry for example.

Introduction to drawings

The invention will now be described by referring to the accompanying drawings which are split views' of the co-extrusion: Figure 1 shows one embodiment of the present invention where the pigment doped region (2) is approximately central to un-doped region (1) of the profile; and Figure 2 shows another embodiment of the present invention where in addition to the pigment doped region (2), and the un-doped region (1), a region (3) is doped with a colourant below' the doped region such as white to increase performance of the product; and Figure 3 shows another embodiment of the present invention where in addition to the pigment doped region (2), and the un-doped region (1), a region (4) is doped with a colourant to provide an aesthetic property to the visible surface of the product; and Figure 4 contines the ertodiments of figure 2 and figure 3 to show regions doped in addition to the pigment region (2) with a colourant doped region (3) to increase performance and a colourant doped region(4) to provide an aesthetic property to the visible surface of the product.

Detailed description

Photo luminescent floor path marking systems have to provide a particular level of light output during discharge following a pre-determined period of charge time. Historically the required performance has been determined experimentally using naïve participants in simulated emergency evacuations. Numerous publications by National Aviation Authorities, photo luminescent floor path mar]cing manufacturors, oxisting patonts and manufacturers of Strontium Aluminate photo luminescent pigment detail this process. The present invention does not seek to redefine these performance reguirements and in order to achieve the performance standards representing the state of the art, only photo luminescent pigments containing the rare earth material strontium aluminate are found to be suitable. Should advances in technology make available pigments that are more suited to the application, it is intended that these may also be used in the present invention in place of or in addition to strontium aluminate containing pigment.

Photo luminescent pigment containing Strontium Aluminate is available in the form of a fine powder, with a typical particle size ranging from, but not limited to, lOum to lO0um. The pigmont is ovnilablc in a numbcr of grodos, sortod by moan particle size, and although any grade may be used, it is known in the art that larger particle sizes exhibit a greater suitability to the application as they provide greater charge/discharge performance. In order to be used in the proposed application, the powder must be arranged in sufficient concentration per unit volume to provide the required performance and be protected from fluids and other forms of mechanical damage. In one embodiment, polyoarbonate is used to suspend the powder particles in the required concentration per unit volume and provide both mechanical protection to the pigment and a form factor suitable for use in the application.

The present state of the art achieves this in one of two ways; i) layering the pigment onto a substrate to resemble a photo luminescent coated metal or plastic strip and insert this strip into a track or sleeve for mechanical protection (WO 01/52224 Al for example) . ii) Prepare the photo luminescent pigment by combining it into a silicon base material which is then either injected or otherwise encapsulated in or under a sleeve or track (WO 2011/026598 Al for example) . The later approach (ii) produces a flexible self-sealing product that is apparently more robust than articles produced in method (i) . Both methods involve multiple production steps. The present state of the art uses an extrusion or injection moulding process to produce tracks or sleeves that the photo luminescent components are inserted in or under. Plastic extrusion is well known and is briefly described here as background to the present invention and therein a required variation on the theme.

In a normal plastic extrusion process, granules of plastic material resembling pellets 1-3mm long and 1-2mm in diameter are fed into a barrel containing a single or double rotating screw, designed to force the pellets along the barrel, with the pressure and temperature increasing along its length. Some of this heat is the result of the screw rotation in the form of friction and some is introduced through heating elements in the barrel and/or screw(s) . At some point along the barrel the plastic granules become molten and are described as a hot melt flow of plastic that can be forced through an opening in a tool that roughly resembles the required profile for the plastic part. This is the exit point of the extrusion machine and as the plastic flow begins to cool, its form may be manipulated to the exact requirement in a process of calibration' just before the material freezes to its final shape.

There is a variation on this method known as co-extrusion to produce items that are non-homogenous, such as electrical wires which contain a metal conductor or plastic window sections that perhaps have a soft rubber sealing strip along an edge. In the case where a solid element such as a metal conductor is introduced to the extrusion, this is fed into the tool in its pre-existing form from a reel while the plastic is still a hot melt to become encapsulated on freezing. Alternately, where the element to be added to the extrusion is another extruded profile, a second screw and barrel arrangement feeds the material to be co-extruded into a second feed port in the tool such that It is both shaped and combined at a seam with the primary extrude material while they are both in the hot melt phase. The result is a co-extruded one piece part of two materials. Care must be taken in the later example to ensure that the melting temperatures of the two materials are similar such that they will combine without causing damage to one another.

WO 01/52224 Al briefly describes the co-extrusion of a photo luminescent coated insert with an outer casing. This implied requirement to produce a photo luminescent coated insert does not alleviate the production steps described herein as costly in the pursuit of fluid resistance.

The present invention advances the art by reducing the composition of photo luminescent floor path marking elements to only two materials and reducing manufacturing to a single step process while creating a profile that is impervious to fluid ingress, allowing it to be cut freely during manufacture and installation without the need for sealing. In the preferred embodiment, the invention resembles a polycarbonate profile, manufactured by a variation on plastic co-extrusion methods, which has a region doped with photo luminescent pigment particles.

In the preferred embodiment, a variation on the co-extrusion process uses two screw and barrel type extrusion machines (the feed screws) , feeding into a single tool whereby one of the feed screws has an additional opening into which a dopant, namely a photo luminescent pigment containing Strontium Aluminate powder, may be injected under pressure using a dosing pump to produce a pigment doped hot melt flow that is combined in the tool to form the doped region of the extrusion profile. The rate of the dosing pump may be varied to control the pigment doping level in the doped region.

Other techniques may also achieve the same result but care must be taken to ensure that the plastic and photo luminescent particles do not separate significantly during processing due to the comparatively large difference in particle size. For this reason a dosing pump is suggested in the preferred method over simple mixing of the components prior to extrusion.

In the preferred embodiment the profile is formed by a variation on conventional co-extrusion using Polycarbonate in one feed screw and Polycarbonate doped with Strontium Aluminate pigment in the other feed screw. In the preferred embodiment the profile is in the range, but not limited to, lOrrim -40mm wide and 1.5mm -7mm high with a pigment doped region in the range, but not limited to, 0.5mm -2mm high and 8mm -38mm wide approximately central in the profile with a doping concentration in the doped region of, but not limited to, 10% -60% photo luminescent pigment by weight.

Iii arioLlier embodimefib of Lhe ifivenLiufi, an area of LJie profile below' (3) the photo luminescent pigment doped region (2) is doped with a colourant, such as white (from the teachings of "The Screen Printer's Guide to Photoluminescence", Marina Batzke, American Permalight Inc., Screen printing, September 1997) , to improve performance.

In another embodiment of the invention, an area of the profile above' (4) the photo luminescent pigment doped region (2) is doped with a colourant, such as purple, to provide an aesthetic effect.

The present invention may additionally use other processes known in plastic extrusion to further enhance manufacturing capability. Those process include but are not limited to the application of double sided adhesive tape to one surface on the line' as the profile is extruded to aid installation where the profile is adhered to the aircraft floor and the application of part marking using line printing, also known in the art of extrusion. Plastic extruded parts are normally cut to length as the profile is extruded and in the preferred embodiment, the profile is cut at regular intervals to provide lengths that are easily installed on aircraft. An example of this length is 3m.

Claims

Claims 1) An elongate profile having at least a region doped with photo luminescent material for use as way-guidance on an aircraft.
2) An elongate profile in accordance with claim 1, in which the profile is polycarbonate and the photo luminescent material contains Strontium Aluminate.
3) An olongato profilo in accordanco with claim 1, in which the profile is 10mm to 40mm wide and 1.5mm to 7mm high and 0.5m to 4m long.
4) An elongate profile in accordance with claim 1, in which a further doped region provides a reflective surface to increase performance.
5) An elongate profile in accordance with claim 1, in which a further doped region provides a coloured appearance.
6) An elongate profile in accordance with claim 1, in which two further doped regions provide both a reflective surface for a performance gain and a coloured appearance.
7) An arrangement of elongate profiles in accordance with any preceding claim which constitutes a system of runners when installed on an aircraft floor.