STRUCTURAL ELEMENT

Abstract: Device for mounting on the tread (1) of a step of a staircase which comprises a generally planar member adapted to be mounted upon or adjacent the leading edge of the horizontal portion (the tread) of a step of a staircase and extending rearwardly over part or all of the width of the step, which rearwardly extending portion of the member is provided with a strip (14) of photoluminescent material. The invention also provides a flooring grade sheet plastic containing a photoluminescent material suitable for use in the device of the invention.

Description: TITLE; STRUCTURAL ELEMENT . " ;: ' ., ' -. The present invention relates to a structural element notably to a stair tread fitting having a photoluminescen element thereto, and to a material for use therein. BACKGROUND TO THE INVENTION: Stairs often present hazards to users, notably when they ar poorly lit or not lit at all, for example when the lightin to a staircase well fails in whole or in part. It ha therefore been proposed to apply a stripe of luminescen paint to the riser of each of the steps of the staircase, which strip will glow in the dark and give the user a guid as to the location of each step. However, such a method ca not be applied where the steps are to be carpeted. Furthermore, the paint stripe can only be a temporary solution to the problem, since it is readily scuffed and removed by the soles of users feet or shoes during normal use of the staircase. It has also been proposed to apply a stip of self-adhesive plastic tape to the stair riser. However, the edge of the strip is readily torn during use of the staircase leading to removal of the strip and a potential safety hazard. The above problems with paints or adhesive tapes would be aggravated if they were applied to the horizontal tread of the step rather than to the vertical riser, since the abrasion and scuffing action of users shoes or feet is much larger. On the other hand, another problem with paint and tapes applied to the riser of the stair is that they are not readily visible to users of the stairs from above and they do not glow brightly for prolonged periods. We believe that this is due to the fact that they are mounted on the vertical face which is obscured to a person descending the staircase and is a face onto which only a small amount o direct light falls during normal illumination of th staircase. It has been proposed to fix a strip of a flexible plastics edging strip incorporating a photoluminescent material across the step at the apex of its nose. The photolumines -cent material was formed as a bead protruding from the edging strip so that it would be visible to users both ascending and descending the staircase. However, this position exposes the material to the maximum abrasion and wear during normal use of the staircase. Furthermore, we found that the light emitted from the photoluminescent material rapidly became obscured. We believe that this was because the material into which the photoluminescent material was incorporated was of a porous nature and that it readily picked up dirt which became firmly imbedded therein, thus reducing the effect of the photoluminescent material. We have found that the above problems can be reduced if the photoluminescent material is incorporated into a generally planar member having an abrasion resistant exposed face mounted upon the horizontal tread of the stair and having a metal or similar protective means along its leading edge. By mounting the photoluminescent material in a substantially horizontal position, the present invention ensures that it will receive the maximum activation from any overhead lighting source and hence be capable of glowing for prolonged periods when the light source is removed. Furthermore, the glow is more readily seen by a user descending as well as ascending the staircase than where the photoluminescent material is located on the face of the riser as hitherto considered necessary. Also we have found that any obstruction on the staircase is more readily apparent to the user than when the photoluminescent materia is mounted on the riser of the staircase. We have als found that although the material is mounted upon that par of the stair exposed to severe abrasion and wear, the actio of the users shoes and feet is generally parallel to th exposed face so that they act to wipe the exposed face an thus reduce problems to the build-up and embedding of dir in the exposed face. The presence of the protective leadin edge not only reduces the risk of detachment of th photoluminescent material from the stair tread, but als serves to support part of the load of a users shoes or fee and thus to reduce wear of the exposed face. SUMMARY OF THE INVENTION: Accordingly, the present invention provides a generall planar member adapted to be mounted upon or adjacent the leading edge of the tread of a step of a staircase and extending rearwardly over part or all of the width of the step, which rearwardly extending portion of the member is provided with a strip of photoluminescent material. In a preferred embodiment, the invention provides a device for affixing to the horizontal portion (the tread) of a step of a staircase (the tread), which device comprises a generally planar horizontal elongated member adapted to be mounted adjacent the leading edge of the step and to extend .rearwardly across at least part of the area of the tread of the step and having a wear-resistant exposed translucent upper face and incorporating a photoluminescent material, the leading edge of the member being provided with a protective member. Preferably, the device comprises an elongated metal or other extrusion or moulding having an axial recess therein into which the photoluminescent material is incorporated, th photoluminescent material having a translucent abrasio resistant overlay providing the said exposed upper face, th said member having an upstanding leading edge along th recess which provides the protective member for th photoluminescent material. It is also preferred that a least initially the exposed face be proud of the uppe surface of the protective member along its leading edge. In a particularly preferred form of the device, th photoluminescent material is incoporated into a laminate plastics material, notably a flooring grade sheet plastics material, and a strip of that material is provided in the recess of the moulding or extrusion. Flooring grade plastics sheet material containing a photoluminescent material is we believe novel, and the invention therefore also provides a plastics material suitable for mounting upon an area to be walked upon by a user and in strip, sheet or other planar form, which material comprises a base layer having a reflective upper surface? an intermediate layer incorporating a photoluminescent material? and an upper translucent wear-resistant layer. Preferably, the base layer incorporates a white pigment? the intermediate layer incorporates a combination of a photoluminescent material and light reflective particles such as glass beads or chips ? and the upper layer is translucent and is provided with a wear resistant upper surface. A particularly preferred upper layer comprises a vinylic polymer having a plasticiser content of from 25 to 45 parts by weight per 100 parts by weight of resin . and the composite sheet has a Shore A hardness of from SO to 95. The invention further provides a step of a staircase having mounted adjacent the leading edge of the tread thereof an extending rearwardly thereof over at least part of the are of the tread a device of the invention. The invention may be applied to a wide range of forms o staircase: for example to wooden, steel or concrete straigh or curved fixed staircases in a building, to companionway in ships ? and to portable structures such as ladders, lof ladders and step ladders. For convenience the ter staircase is used herein to denote in general all suc structures comprising a flat surface (the tread) upon whic a user steps, which surfaces are arranged in ascending o descending sequence to enable the user to ascend or descen between different levels. The invention is of especial us on fixed staircases mounted in buildings which have a series of horizontally staggered treads linked to one another by upright risers located adjacent the front edge of an upper tread and adjacent the rear edge of a lower tread to form a conventional staircase. However, it will be appreciated that the risers may be omitted to give what is known as an open tread staircase. DESCRIPTION OF THE DRAWINGS: For convenience the invention will be described in terms of a fixed conventional staircase with treads and risers and to aid understanding of the invention, it will be described with respect to the preferred form thereof shown in the accompanying drawings in which Figure 1 is a vertical section through a step of a staircase carrying a member of the invention, Figure 2 is a plan view of the step of Figure 1? Figures 3 is a vertical section through a flooring grade plastics material for use in the member of Figure 1? and Figures 4 and 5 are views of alternative forms of the member of Figure 1. The staircase is formed from a staggered series o substantially horizontal treads 1 linked by substantiall vertical risers 2. Typically the step will be constructe from wood as shown. However, other materials o construction may be used and the tread and riser need not b separate members, but can be formed as a single unit as whe the staircase is cast in concrete or is made from welde steel or the like. As indicated above, the risers 2 may b omitted and the treads can be of slatted or mes construction. However, it is preferred that the trea present a solid horizontal surface upon which the use treads. Upon some or every step tread is mounted a device 10 of th invention incorporating a photoluminescent member. This ca take the form of a simple strip of flooring grade plastic material incorporating the photoluminescent material an secured to the tread 1 in the desired position by adhesive, screws or the like. However, it is preferred to support th strip of material in a metal or other edge piece which no only protects the nose of the stair against wear, but als secures and protects the leading edge of the photolumine¬ scent material. Such an edge piece typically comprises steel, aluminium or rigid plastics extrusion 11 having one or more axial recesses, slots or grooves 13 into which the photoluminescent material 14 is located. The extrusion 11 preferably extends over substantially all its length rearwardly at least part of the way over the face of the tread 1 as shown in Figure 2. If desired, the tread can be provided with one device of the invention along its nose, which can carry two or more strips of photo¬ luminescent material, with one or more further devices (10a, 10b) affixed upon the rearward area of the tread as shown in Figure 2. The extrusion 11 is a generally planar member affixed up the upper surface of the tread. However, as shown in Figu 1, it is preferred that the extrusion 11 have a depende front skirt 12 which overlies the upper portion of the ris 2 of the step, or an upstanding rear edge which extends at least part of the riser at the rear of the tread. T precise form and size of the extrusion 11 can be selected known manner to suit the size and shape of the step it is fit. The extrusion 11 is provided with one or more grooves recesses 13, preferably longitudinal, into which strips of photoluminescent material are to be secured. T recesses 13 can be formed as the extrusion 11 is formed can be formed subsequently, for example by clamping str retaining bars 30 onto a base plate 31 to clamp the edges the strips 14 in place, as shown in Figure 4. The recesse 13 desirably take the form of rectangular cross-sectio channels in the upper face of the extrusion into whic strips 14 of the photoluminescent material are a close fit If desired the channels can have undercut edges t co-operate with a trapezoidal cross-section to strips 14 The channels extend axially of extrusion 11, preferably a unbroken recesses along the whole length of the extrusion s that the photoluminescent material lies across substantiall the whole width of the stair tread as shown in Figure 2. A shown in Figure 2, there can be two or more strips o photoluminescent material along.each extrusion 11. As indicated above, the strips 14 of photoluminescen material are to be located inwardly of the leading edge o the extrusion so that the leading edge of the extrusio prtects the edge of strip 14 against the wear of users shoes and feet. We also prefer that the extrusion be mounted at or adjacent the nose of the step to give a user an indication of the position of " the edge of the step. Thus we prefer that the leading edge of extrusion 11 be locate within 30 mms, preferably within 0 to 20 mms, of the edge o tread 1. Otherwise, the extrusion 11 and strip 14 can b located as desired. Where extrusion 11 has a dependen front skirt 12, it will be appreciated that this carries th leading edge of the extrusion over the leading edge of th step and this skirt or the upstand at the rear of th extrusion can carry one or more photoluminescent strips t indicate the position of the riser to the step to a user. Within recess 13 is located a strip of photoluminescen material 14. Preferably, this strip is provided by a lengt of substantially non-porous plastics material incorporatin a photoluminescent material which strip is a close fi within recess 13« The strip 14 can be secured within th recess by any suitable method, for example by being a tigh fit within an undercut lip to the recess as shown in Figur 2 or by screws or other fixing means. It is particularl preferred to secure the strip in place by a suitabl adhesive. Alternatively, the base of the recess can be coated with a suitable photoluminescent paint or the like. The photoluminescent material strip is protected against excessive abrasion and lifting by the extrusion 11. If desired, the recess 13 can be given a transparent cover 15 to protect the strip 14 and to secure it within the recess as shown in Figure 5. However, it is preferred to form the strip 14 from a flooring grade plastics material incorporating a translucent non-porous upper layer so that the exposed upper face of strip 14 will resist wear by the feet of users. Where this is done, the upper face of strip 14 can be set so that it is flush with or stands slightly proud of the upper face of the extrusion 11 as shown in Figure 1. We have found that by doing this, problems of loss of illumination from the photoluminescent strip due dirt entrapment within the recess or on the face of strip are reduced. In effect, the face of the strip 14 will wiped by the users' feet as they tread on the step, th preventing excessive build up of dirt on the face of t strip. Furthermore, where the surface of strip 14 is wo donw to the level of the leading edge of extrusion 11, t extrusion will carry at least part of the weight of a us and will protect the strip 14 against rapid erosion duri normal use of the staircase. Alternatively, the material of one or more layers of t strip can be selected so as to allow the strip to compressed slightly so that the majority of the load of t user is supported by the extrusion 11 and not by the stri 14. Thus, the lower layer of a laminated plastics strip 1 can be a foamed material. The strip 14 can be formed from conventional ingredient using conventional plastics technology, except that th polymer composition forming all or part of the stri contains one or more photoluminescent active materials Thus, the strip 14 can be formed by extruding a suitabl thermoplastic ■ polymer composition such as a translucen polyvinylic resin or the like and applying a coat of photoluminescent paint or the like to the under surfac thereof. However, it is particularly preferred that th strip 14 be in the form of a composite material having flexible protective upper layer and a lower photoluminescen layer. Thus, the strip can be formed by co-extruding clear PVC layer having a Shore A hardness of from 85 to 92 with a PVC layer containing photoluminescent material . Suitable PVC resins for present use are those containing from 30 to 40 parts by weights of plasticizer, eg. a phthalate plasticiser, per 100 parts by weight of resin. It is especially preferred that there should also be a lowe reflective layer to enhance the light emission from th strip. A suitable structure for the strip 14 is shown in Figure and comprises a base layer 20, a layer 21 containing th photoluminescent material and a translucent top layer 22 Such a material can be made from conventional flooring grad plastics materials and using conventional sheet plastic fabrication techniques. Thus, the base layer 20 can be sheet of vinylic, polyurethane or polyethylene polymer or blend or copolymer of such materials, for example wit butadiene and/or styrene. The layer 20 can be a rigi polymer layer having a Shore hardness of substantially 100 or can be formed from an expanded polymer to allow th resultant strip 14 to have a measure of compressability Typically, layer 20 will be from 1 to 5 mms thick and can b made up from a series of thinner layers if required. As indicated above, layer 20 is to be reflective so that th maximum light from the intermediate layer 21 is directe upwardly„ This can be achieved by forming a reflectiv layer 24 on the face of layer 20, eg. by laying a metal -foi upon layer 20 or by deposition a metallic film on layer 20. Alternatively, layer 20 need not be a polymer layer bu could be in the form of a reflective metal foil or even th highly polished base to the recess 13. However, it is preferred to incorporate a white pigment such as titaniu oxide pigment and/or reflective particles such as glass beads or chips into the polymer from which layer 20 is formed so that the layer is inherently reflective. Layer 21 contains the photoluminescent material, preferably in conjunction with reflective particles such as glass beads or chips which enhance light emission from the layer. The photoluminescent material can be selected from a wide ra of such materials. Thus, suitable materials for present include radioactive gasses, eg. tritium, encapsulated i polymer bead such as a polycarbonate? or metal sulphid notably calcium, stronium or zinc sulphides, or mixtu thereof. If desired, the active ingredient can be .appl as a coating to a solid carrier, such as a fin particulate metal, eg. copper. Typically, the phot luminescent material will be present as a particulate crystalline material dispersed in a thermoplastic polym base. The amount of photoluminescent material is typical from 50 to 500 gs, preferably 100 to 400 gs, of acti ingredient per square metre of exposed surface area throu which light is to be emitted. If desired, the layer 21 c contain other ingredients, notably materials which fluores in daylight such as organic fluorescins. Suitable polym sheets containing the photoluminescent materials a available commercially and may be used as such in t prduction of the strips 14. However, the layer 21 may al be formed in situ by applying a paste or solution of t required ingredients and a carrier polymer, or an oligom or monomer precursor thereof, to layer 20 or to the base recess 13 as indicated above, and causing the polymer f the layer 21 to be formed in situ by suitable polymerisatio techniques as is known in the art. The strip 14 has an upper layer 22 which is to be exposed t the feet of the user. This layer is translucent not only t allow the photoluminescent material to be activated by ligh falling on strip 14 but also to allow the glow from layer 2 to be visible in the dark. Preferably, layer 22 i transparent and substantially clear. Thus, layer 22 can b formed from a polyvinyl, polyurethane or other polymer usin conventional techniques and additives to enhance the U stability and other functions of the polymer layer. Th layer 22 protects layer 21 against abrasion during use a therefore is formulated to floor grade requirements as known in the art. Thus, the layer will typically be form from a clear PVC resin having a Shore A hardness of from to 97 to give it the desired flexibility for we resistance. The overall composite structure for strip 14 can be made co-extrusion where only two layers are present or laminating pre-formed polymer sheets using hot pressing other conventional techniques to cause the layers to adhe to one another, optionally with adhesive interface layers Thus, a PVC composite structure can be made by causing t various layers to fuse together under pressure and elevated temperatures. In a particularly preferred metho of manufacture, a clear PVC top layer having a shor hardness of 86 to 92, an intermediate layer containin photoluminescent zinc sulphide particles and a base layer o one or more plies of a rigid PVC having a Shore hardness o substantially 100 is fused together at 150 to 175 °C under pressure of from 100 to 200 psi gauge. The composite structure described above may omit one or mor of the layers, eg. the base reflective layer where reflective foil is present or the base of the recess 13 i sufficiently highly polished to provide the necessar reflective effect. The composite structure described above may contain othe ingredients conventionally used in polymer mixes, fo example antioxidants or dyes in the upper layer to provide colour other than green to the light emitted from the stri 14? and may be subjected to further treatment as is known t enhance its properties. Thus, the composite structure ca be given a surface coating of a silicone or other polmer t provide a non-slip surface thereto and/or to aid resist to adherence of dirt to the exposed face of layer 22. strips 14 are formed from the composite structure by cutt the overall sheet of material into the required strips us a mechanical knife or air blade or a heated wire cutter. The strips 14 are secured into the recesses 13 using suitable technique and will usually extend for the f length of the recess. However, it is within the scope the present invention for the strips 14 to be comparativ short and to alternate with, for example, conventio anti-slip material also carried in recesses 13. In use, the extrusion 11 is secured by any suitable means the desired location on the treads 1 of a stairca However, it will be appreciated that the composite floor grade structure described above, can also be used elsewh where a photoluminescent material is required in a locati where it is to be subjected to abrasion. Thus, t composite structure can be formed into broad strips whi are set into extrusions or similar settings to provi markers for mounting on or into the floor of a room. In t event of a power failure or other emergency when the lig source fails, such markers can provide a path on the flo which occupants of the room can follow. Thus, the invention also provides a method for marking are to be trodden by a user or lines of travel to be followed a user, notably foot paths on the floor of a structur which comprises securing a device or a wear-resista flooring grade composite structure of the invention to th area or adjacent that line of travel.

Claims: CLAIMS : 1. A device comprising a generally planar member adapt to be mounted upon or adjacent the leading edge of t horizontal portion (the tread) of a step of a staircase a extending rearwardly over part or all of the width of t step, which rearwardly extending portion of the member i provided with a strip of photoluminescent material. 2. A device as claimed in claim 1 comprising a generall planar horizontal elongated member adapted to be mounte adjacent the leading edge of the step and to exten rearwardly across at least part of the area of the tread o the step and having a wear-resistant exposed translucen upper face and incorporating a photoluminescent material the leading edge of the member being provided with protective member, 3. A device as claimed in either of claims 1 or 2 whic comprises an elongated metal or other extrusion or mouldin having one or more axial recesses therein into which th photoluminescent material is incorporated, the photo luminescent material having a translucent abrasion resistan overlay providing the said exposed upper face, the sai member having an upstanding leading edge adjacent the reces which provides the protective member for the photo luminescent material. 4. A device as claimed in any one of claims 1 to 3 wherei at * least initially the exposed face of the said photo- luminescent member is proud of the upper surface of the protective member along its leading edge. 5. A device as claimed in any one of the preceding claims wherein the photoluminescent material is incorporated into a laminated plastics material. 6. A device as claimed in any one of the preceding cla wherein the photoluminescent material is incorporated i flooring grade plastics sheet material which comprise base layer having a reflective upper surface? intermediate layer incorporating a photoluminesc material ? and an upper translucent wear-resistant layer. 7. A device as claimed in claim 6 wherein in the plast sheet material the base layer incorporates a white pigme the intermediate layer incorporates a combination of photoluminescent material and light reflective particl notably glass beads or chips? and the upper layer translucent and is provided with a wear resistant up surface. 8. A device as claimed in claim 6 wherein the upper lay comprises a vinylic polymer having a plasticiser content from 25 to 45 parts by weight per 100 parts by weight resin and the composite sheet has a Shore A hardness of fr 80 to 95. 9. A device as claimed in any one of the preceding clai wherein the leading or trailing edge of the device casrri a dependent skirt or an upstanding edge adapted co-operate with the riser adjacent the tread of the step which the device is mounted. 10. A device as claimed in claim 2 substantially hereinbefore shown in and as described with respect to an one of the accompanying drawings. 11. A step of a staircase having mounted adjacent th leading edge of the tread thereof and extending rearwardl thereof over at least part of the area of the tread a devic as claimed in any one of claims 1 to 10. 12. A method for marking areas to be trodden by a user lines of travel to be followed by a user, notably foot pat on the floor of a structure, which comprises securing device or a wear-resistant flooring grade composit structure of the invention to that area or adjacent that line of travel. 13. A plastics material containing a photoluminescen material containing a photoluminescent material suitable fo use in the device or method of any one of the precedin claims and in strip, sheet or other planar form, whic material comprises a base layer having a reflective uppe surface? an intermediate layer incorporating photoluminescent material? and an upper translucen wear-resistant layer. 14. A plastics sheet material as claimed in claim 1 wherein the base layer incorporates a white pigment? th intermediate layer incorporates a combination of photoluminescent material and light reflective particle such as glass beads or chips? and the upper layer i translucent and is provided with a wear resistant uppe surface. 15. A plastics sheet material as claimed in either o claims 13 or 14 wherein the upper layer comprises a vinyli polymer having a plasticiser content of from 25 to 45 parts by weight per 100 parts by weight of resin and the composit sheet has a Shore A hardness of from 80 to 95.

Inventors: CONNEW RAYMOND ALBERT, CONNEW, RAYMOND, ALBERT
Applicants: SHINEBUILD LTD, SHINEBUILD LIMITED
Application year: 1988
Main classification: E04F11
IPC codes: E04F11