GB2414260A - Reflector assembly for use in road marking - Google Patents

Abstract

A reflector assembly for use in association with a housing to provide a road surface marker. The reflector assembly comprises a resilient body adapted to engage with a housing so as to removably hold and position the resilient body in the housing. In use, the housing of the road surface marker would be embedded in the surface of the road. The resilient body of the reflector assembly comprises a lens housing portion for housing one or more reflectors. Each of the reflectors comprises a rod having opposite first and second ends, at least the first end comprising a retroreflective sheeting having on one side thereof microprismatic elements. The retroreflective sheeting is provided such that the micropnsmatic elements are facing inwardly of the rod. The first end of the rod is covered with a clear self-healing protective layer of a synthetic resin protecting the retroreflective sheeting on the first end of the rod. The self-healing protective layer also defines a lens member, said resilient body having a hollow base portion.

Description

REFLECTOR ASSEMBLY FOR USE IN ROAD MARKING

1. Field of the invention

The present invention relates to a reflector assembly that can be removably inserted and s positioned in a housing that is embedded in the surface of a road. In particular, the present invention relates to particular reflectors for use in such reflector assembly.

2. Background of the invention.

Reflective road markers for marking the surface of a road are well known in the art. Road 0 markers are for example disclosed in GB 2148986, GB 2147038, GB 2175943, GB 2229470, GB 2263298, GB 2285079 and EP 125360. The road markers disclosed in these publications are comprised of a metal housing that is embedded in the surface of the road.

Removably associated with the metal housing is a resilient body that contains reflectors. For example, GB 2263298 discloses a road marker in which the reflectors comprise glass hemi spheres. This patent also discloses a means by which the reflectors get cleaned by allowing the upper part of the body holding the reflectors to be depressed into the lower part of the body upon pressure applied to the road marker, e.g. as a result of a vehicle tire running over the road marker. Such allows for the reflectors to be cleaned from time to time so that they can maintain their reflectivity. Road markers of this kind have been in use in countries such as for example the United Kingdom for several years.

Although the existing road markers using glass hemi-spheres provide reasonable marking of the road to a driver, the reflective properties of the glass hemi-spheres is low and it would thus be desirable to improve the reflectivity of road markers.

The use of cube-corner type reflecting elements on the rear face of a lens member has been described in GB 2 147 038 for use as reflector of road markers. The lens member is formed of an organic synthetic resin which is provided with an abrasion resistant material such as for example glass of a thickness of 6 mile. Although it is disclosed in GB 2 147 038 that such reflectors provide for a higher reflectivity compared to reflectors based on glass hemi spheres, there continues to be a desire for further improvement.

.e cee e e e _ . . . . In particular, it would be desirable to design a road marker with a high degree of retroreflectivity that is capable of withstanding the harsh conditions under which such road markers are typically used. For example, a surface road marker may be exposed to extreme conditions of humidity, UV exposure, exposure to extreme temperature conditions varying from below freezing point in winter conditions to very high temperature when exposed to the sun in the summer. Furthermore, the road marker will be exposed to vehicles running over it and collect debris from road and vehicles. It would be desirable to find a road marker that can maintain a high retroreflectivity under the conditions to which a road marker may typically be exposed.

3. Summary of the invention

In accordance with the present invention, there is provided a reflector assembly for use in association with a housing, e.g. a metal housing or a housing of a heat resistant rigid plastic, to provide a road surface marker. The reflector assembly comprises a resilient body adapted to engage with a housing so as to removably hold and position the resilient body in the housing. In use, the housing of the road surface marker would be embedded in the surface of the road. The resilient body of the reflector assembly comprises a lens housing portion for housing one or more reflectors. Each of the reflectors comprises a rod having opposite first and second ends, at least the first end comprising a retroreflective sheeting having on one side thereof microprismatic elements. The retroreflective sheeting is provided such that the microprismatic elements are facing inwardly of the rod. The first end of the rod is covered with a clear self-healing protective layer of a synthetic resin protecting the retroreflective sheeting on the first end of the rod. The self-healing protective layer also defines a lens member.

It has been found that the reflector assembly can be used to provide a road marker with a high degree of retroreflectivity. Furthermore, the high degree of retroreflectivity may be retained to a large degree over time while the road marker is subjected to a variety of weather conditions including rain, heavy sun shine as well as freezing temperatures.

Additionally, the lens member of the reflector is sufficiently abrasion resistant so that a separate abrasion resistant material can be dispensed with.

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4. Brief description of the drawings.

The following drawings are included to illustrate the invention and to aid to a better understanding thereof, without however the intention to limit the invention thereto: Figure I A and 1 C are schematic drawings of different embodiments of a reflector for use with the invention.

Figure I B is a cross-section along line A-B in figure 1A.

Figures 2 and 4 are schematic drawings showing a front view of different embodiments of reflector assemblies according to the invention.

l o Figure 3 is a schematic drawing showing a side view of a reflector assembly in connection with this invention.

Figure 5 illustrates a housing with which the reflector assembly may be associated to form a road surface marker.

5. Detailed description of the invention.

Within the claims and disclosure of this invention, the following terms may be used and have the meaning as defined below: By the term 'selfhealing' is meant that the respective material is capable of restoring its original shape and appearance after having been deformed in some way, for example by scratching. Generally, a material is self-healing within the context of this invention if it is capable of substantially restoring its original shape and appearance after having been subjected to deformation as may be caused during use in a road surface marker. By substantially restoring' is meant that the material should restore to such an extent that at least 70%, preferably at least 80% of the initial retroreflectivity is retained.

By the term 'microprismatic clement' is meant a prismatic element such as for example a cube-corner element having dimensions that are below 1 mm, for example not more than 0.5mm. Accordingly, microprismatic elements are generally best viewable using a microscope.

The term 'rod' in connection with the present invention includes rods which are solid, hollow or partly solid or hollow. The term further includes rods of which the cross-section may vary over its longitudinal extension both in shape as well as in size. While a rod in - e . . . . . . connection with this invention may have a cross-section of any shape, the cross-section will generally be circular or oval.

The reflector or reflectors used with the reflector assembly in connection with the present s invention comprises a rod that on at least one of its ends is provided with a retroreflective sheeting. The rod can be of any material but is generally made of hard plastic such as for example polyacetal or a copolymer of acrylonitrile, butadiene and styrene, which is known as ABS. Alternatively, the rod can be made of metal such as for example aluminium or the rod may be resilient, i.e. being made of an elastomeric material rather than being rigid. The lo rod may be cylindrically with a circular cross-section at its opposite ends as illustrated in Figure I A or may be cylindrical with an oval crosssection at both ends as illustrated in Figure 1B. As can be seen from Figure IA and the cross-section along line A-B shown in Figure 1 C, the rod 10 is provided on one of its ends l 1 with a retroreflective sheeting 12 on top of which is a lens member 13.

The lens member of the reflectors, such as for example lens member 13, is defined or formed by a clear self-healing protective layer of synthetic resin. Typically, a cross-linked but flexible synthetic resin is used. A particularly suitable synthetic resin for use in this invention comprises a polyurethane resin, in particular a cross-linked and flexible polyurethane. A suitable flexible and cross-linked polyurethane that may be used includes the polyurethane disclosed in US 6,709,748. Such a polyurethane comprises the reaction product of a first and second component, whereby the first component comprises one or more polyols having an equivalent weight of 28 to 3000 and the second component comprises a primary polyisocyanate having an average of more than two isocyanate groups, 2s for example at least 3. The first component generally also includes a catalyst for catalyzing the reaction between the first and second component and optionally also includes one or more diols. In a generally preferred embodiment, the components are solvent free or substantially free of solvent (e.g. not containing more than 5 % by weight of solvent).

The polyols are compounds having 3 or more hydroxyl groups. The polyols are generally selected from the group consisting of polyesters, polycarbonates, polyacrylates, polyalkylenes, and polyethers, or combinations thereof. The polyol, or combined polyols, - . . . . have an equivalent weight in the range of about 28 to about 3000. In the present invention, equivalent weight corresponds to the molecular weight of the material divided by the number of hydroxyl groups. Combinations of polyols within the noted equivalent weight limitation may be suitable for use with the invention. Desirably, polyester based polyols and diols, forming greater than about 20 weight percent polyester in the first reaction component are used. The polyol comprises in the range from greater than about 10 weight percent of the first reaction component.

Optionally, one or more diols are included in the first reaction component. The diols are o compounds that have two hydroxyl groups. In addition to polyester diols, polycarbonate, polyacrylate, polyalkylene, and polyether diols, or combinations of the noted compounds, may be utilized in the present invention. The one or more diols have a combined equivalent weight in the range of about 30 to about 4000. Additionally, the diols comprise in the range up to about 65 weight percent of the first reaction component. Desirably, the diols include the combination of a short chain dial, having an equivalent weight in the range from about to about 400, and a polymeric, or long chain diol having an equivalent weight in the range of from about 400 to about 4000.

The isocyanate groups of the second component react with the hydroxyl groups of the first component generally under the influence of the catalyst to form urethane linkages.

Conventional catalysts generally recognized for use in the polymerization of urethanes may be suitable. For example, aluminum, bismuth, tin, vanadium, zinc, or zirconium based catalysts may be used. The catalyst is generally included at levels of at least 200 ppm in the first component or at 300 ppm or greater.

The second component for providing a clear polyurethane lens member includes a primary polyisocyanate, and preferably a primary aliphatic polyisocyanate. A primary isocyanate is defined as one having a carbon atom that has an -NCO group and two hydrogen atoms attached to the carbon atom. The primary isocyanate generally provides for a flexible so polyurethane that does not exhibit a substantial amount of outgassing. Outgassing can occur when the isocyanate component of the polyurethane undesirably reacts with a source of water or carboxyl groups and not the hydroxyl groups present in the first component.

e A- e - . . . . . Typically, the second reaction component includes a primary polyisocyanate in an amount of weight percent or greater. This generally corresponds to polyisocyanate crosslinking of weight percent or greater in the cured polyurethane lens member. The primary s polyisocyanate may be the only isocyanate source in the component or it may be combined with other isocyanates, preferably other primary isocyanates such as a primary monoor di isocyanate. Conventional primary aliphatic polyisocyanate crosslinkers may be suitable for use with the present invention. For example, Desmodur_ XP-7100 and Desmodur_ N 3300 from Bayer Chemical of Pittsburgh, Pa. are two polyisocyanates suitable for use with 0 this invention.

The first and second reaction components are typically combined to form a solvent-free admixture having an NCO:OH ratio of about 0.75 to about 1.25. The reaction components, prior to mixing, are desirably maintained at specified viscosity ranges. The viscosity of the first component is desirably maintained in the range from about 200 cps to about 5000 cps at 25 C. The viscosity of the second reaction component is desirably maintained in the range from about 100 cps to about 5000 cps at 25 C. Upon mixing, the viscosity of the admixture is in the range from about 400 cps to about 5000 cps at 25 C, and desirably in the range from about 600 cps to about 4000 cps.

The retroreflective sheeting of the reflectors such as for example the retroreflective sheeting 12 in Figure IC, is a sheeting that has on one of its major sides a plurality of microprismatic elements and has a generally planar surface on the opposite major side. The microprismatic elements are typically cube-corner elements. The microprismatic reflecting elements include generally trihedral structures that have three approximately mutually perpendicular 2s lateral faces meeting in a single corner, i.e. a cube corner. The cube corner typically has a height of 20 to 500 m, for example 60 to 180,um. In use, the retroreflectivc sheeting is typically arranged with the generally planar surface disposed generally toward the anticipated location of intended observers and the light source. Light incident on the front surface enters the sheet and passes through the body of the sheet to be reflected by each of the three faces of the elements, so as to exit the front surface in a direction substantially toward the light source. Reflective coatings may be applied on the lateral faces of the cube ee. e..

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- - . . - corners. Suitable reflective coatings that can be applied include transparent reflective metal layers or a dielectric mirror.

The retroreflective sheeting typically is a polymeric sheeting. Suitable polymers include poly(carbonate), poly(methyl methacrylate), poly(ethylene terephthalate), aliphatic polyurethanes, as well as ethylene copolymers and ionomers thereof. Cube corner sheeting may be prepared by casting directly onto a film, such as described in U.S. Patent No. 5,691,846. Polymers for radiation-cured cube corners include cross-linked acrylates such as multifunctional acrylates or epoxies and acrylated urethanes blended with mono-and lo multifunctional monomers. Further, cube corners may be cast on to plasticized polyvinyl chloride film for more flexible cast cube corner sheeting. For the purpose of use in the reflectors of the reflector assembly, reflective sheeting of polycarbonate polymer is generally preferred.

In an embodiment of this invention the retroreflective sheeting may have a further polymeric sealing layer bonded to the side of the sheeting that has the microprismatic elements so as to form a plurality of closed cells in which an air interface is provided to the microprismatic elements. Illustrative examples of retroreflective sheeting are disclosed in U.S. Pat. Nos. 4,588,258; 4,775,219; 4,895,428; 5,138,488; 5,387,458; 5,450,235; 5,605, 761; 5,614,286 and 5,691,846. Also, in a typical embodiment, an adhesive layer may be provided to the polymeric sealing layer so as to allow for the retroreflective sheeting to be adhesively bonded to the rod. Suitable adhesives for the adhesive layers include any adhesive capable of establishing a sufficient bond strength to the rod. Generally a pressure sensitive adhesive will be used such as for example an acrylic pressure sensitive adhesive.

In one embodiment of the present invention, at the end where the retroreflective sheeting is to be provided, the rod may have a recess. Such a recess may be defined by the rod being closed near its end as is illustrated in Figure IC. The retroreflective sheeting 12 is then provided in that recess and the lens member 13 covers and protects the retroreflective sheeting 12 from the harsh conditions to which the road marker may be exposed when used.

The retroreflective sheeting 12 is generally die-cut from a larger sheeting so as to obtain a retroreflective sheeting of desired dimension fitting into the recess or otherwise with the size . ... ...

- . - of the cross-section of the rod at its end to which the retroreflective sheeting is to be provided. When the retroreflective sheeting includes a polymeric sealing layer, the cut sides will preferably be sealed during or subsequent to the cutting operation.

In a still further embodiment, the rod of the reflector may have a retroreflective sheeting of the type described above provided on both of its opposite ends and both said retroreflective sheetings then being covered with a lens member. Such a reflector thus provides for retroreflectivity at both of its opposite ends and can be used in the resilient body of the reflector assembly to provide retroreflectivity and opposite walls of the lens housing portion 0 of the resilient body.

The reflector for use in the reflector assembly may be produced by providing a rod and attaching the retroreflective sheeting to one of the ends of the rod. Preferably, the retroreflective sheeting is adhesively bonded into a recess on at least one end of the rod. On the retroreflective sheeting is then applied a coating of the synthetic resin to form a self healing clear protective layer. Generally, the coating should extend somewhat beyond the retroreflective sheeting so that also part of the rod is covered by the coating. This may provide the advantage that the transition between the retroreflective sheeting and the rod surface is also covered by the protective coating, thus potentially minimizing infiltration of water or dirt between the rod and the retroreflective sheeting. Typically, the coating for forming the protective layer and lens member will be a cross-linking composition, such as for example the polyurethane described above. Accordingly, such composition should generally be allowed to cross-link or may be exposed to conditions for cross-linking the compositions. Such conditions may include heating as well as exposure to actinic radiation.

The reflector or reflectors are held in the lens housing portion of the resilient body of the reflector assembly. The reflector or reflectors may be held in the lens housing portion by any suitable means. For example, the reflector(s) may be molded into the lens housing portion of the resilient body or they may be fixed in the lens housing portion by for example so a screw. The rod of the reflector may also be provided with one or more flanges to better retain and hold the reflector in the lens housing portion. Such flanges may be particularly useful when the reflector is molded into the lens housing. The lens housing portion typically e.- ..

e . . I . _ - ë . - forms the upper part of the resilient body and has opposite first and second walls. At least one of these walls and preferably both of them will have one or more reflectors, i.e. the reflective portion of the reflector is on said first and/or second wall and typically at least the lens member portion of the reflector protrudes from the wall. In use, the first and or second s walls will be oriented in such a way that light from vehicles driving on the road can impinge on the reflectors and be reflected therefrom.

The resilient body of the reflector assembly further may include a base portion that may be provided as a hollow portion. In such an embodiment, it will be advantages to arrange the lo upper portion, i.e. the lens housing portion in such a way that it can be depressed in the base portion when a vehicle exerts pressure on the resilient body. Furthermore, the resilient body may be designed in such a way that upon such a depression, cleaning of the lens member of the reflectors can take place. For example, one or more wiper elements may be provided in the base portion to cause the cleaning of the lens member. Examples of such wiper elements l 5 have been described in for example GB 2 148 986 and GB 2 147 038. The resilient body of the reflector assembly may be made of any elastomeric material. For example, the resilient body may be made of Neoprene and may have a hardness in the range of 40 to 60 durometer, Shore A. Figure 2 illustrates a particular embodiment of a reflector assembly in accordance with the present invention. Figure 2 is a front view of a reflector assembly 50 having a single reflector 52 held in the lens housing portion 51. The lens housing portion 52 comprises the upper portion of the resilient body of reflector assembly 50 and can be depressed into the hollow base portion 53 of the reflector assembly. The rear side of reflector assembly 50 will typically look the same as the front illustrated in figure 2. The opposite side walls connecting the front and rear walls of the reflector assembly 50 are illustrated in figure 3.

These side walls include openings 55 that can engage with attachment pins 125 of metal housing 100 illustrated in figure 5. Accordingly, reflector assembly 50 is firmly held in the metal housing 100 but can still be readily removed there from as may be necessary for example for replacement or repair. Metal housing 100 is embedded in the material of the road 200. Thus, reflector assembly 50 together with the metal housing forn1 a road surface marker.

e ë e e e e e e - - eel e e me e e e a e- ee see e e Figure 4 illustrates a further embodiment of a reflector assembly in connection with this invention. Figure 4 illustrates a front view of reflector assembly 60 having two reflectors 62 of which the ends that are provided with the retroreflective sheeting have a circular cross s section. Like reflector assembly 50 of figure 2, reflector assembly 60 has a hollow base portion in which the lens housing portion 61 may be depressed.

The invention will now be further illustrated with reference to the following examples without however the intention to limit the invention thereto. lo

EXAMPLES

Test Methods Reflectors were tested by the following methods: a) Abrasion Test An abrasion resistance test was performed using a reciprocating linear wear tester according to American Society of Testing and Materials (ASTM) Method G-133. In this test, the standard ball specimen was replaced with the fixed reflector sample that was rotated approximately 30 degrees for each abrasion cycle. The stroke length used was 150 mm and the normal load was equal to the weight of the reflector plus the mounting assembly. No additional load was used during the test, and water was used as a lubricant during the testing process. The surface of the finished rod to be viewed by on-coming traffic was abraded against a hard flat horizontal ceramic tile with 5 grams of P50 grade aluminium oxide 2s powder placed on top of the tile in the stroke path for each test. Each sample was subjected to 300 cycles of abrasion. Following the tests, the samples were evaluated by the three methods below to determine whether abrasion of the lens had occurred or whether loss of clarity of the lens resulted. The test were performed on a total of 5 samples and the results averaged.

30The three methods used were: 1. Change in height of the tested samples e e see eee e e e e e e e e e e e e-e e e ee e e e e e e en ee eee e e e e 2. Visual inspection, looking for signs of deterioration including cracks or hardening or bonding failure 3. Retroreflectivity was measured before and after the test according to the requirements of British Standard EN 1463 - Part 1:1998. R. the coefficient of luminous intensity, was measured using the following parameters: Oh (8v = 0 ) = +/- 5 and an observation angle = 0.3 , where 13 and Be are angles defining the orientation of the sample with respect to the light source as outlined in British Standard EN 1463 - Part 1:1998.

l o Results were recorded in units of millicandellas / lux. The results measured for a single rod/reflector were doubled so as to depict the coefficient of luminous intensity of the completed road marking device as observed from one side. R values determined for the glass hemispheres of Comparative Example I were also doubled.

b! Hot / cold Water Shock T est Test samples were immersed in water containing surfactant (5 drops per 1000 ml) at 50 C for 10 minutes, followed by ice water containing surfactant for 10 minutes. The shock test was repeated 10 times. Samples of the reflectors of the invention were visually inspected after the test to determine whether there was water ingress between the reflective sheeting and the rod, and /or if there was failure of the bond between the rod and the protective polyurethane layer. The test were performed on a total of 5 samples and the results averaged.

c) UV Stability A UV accelerated aging test was performed using a commercial weathering chamber available as the Accelerated Weathering Tester, Model QUV with UVB-3 13 lamp, from the Q-Panel Lab Products Corporation. The samples were tested according to American Society of testing and Materials (ASTM) Method G-53. The test were performed on a total of 5 samples and the results averaged. The samples were exposed to: 1. 4 hours exposure in the weathering chamber described above 2. 4 hours of non-UV exposure in a 50 C condensing humidity environment.

This cycle was repeated for 21 cycles (i.e. 7 days).

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After the UV stability test, samples were evaluated in the following ways: 1. R. the coefficient of luminous intensity, was measured before and after the test according to the requirements of British Standard BS EN 1463: Part 1 by the same procedure utilized in the Abrasion Test above.

2. Visual inspection was performed, looking for signs of deterioration including cracks, hardening or bond failure d) Environmental Test The reflector samples were exposed to the following varying temperature and lo humidity cycle according to British Standard EN 29142: Cycle D3 comprising: 1. 40 C and 95% relative humidity for 15 hrs 2. -40 C and O%r.h.for3hrs 3. 70 C and 50% r. h. for 5 hrs 4. 40 C and 95% r. h. for I hr This was repeated for a total of 7 cycles (i. e. 7 days). Samples were then visually inspected for discoloration, cracking, shrinkage and/or delamination between component parts. The test were performed on a total of 5 samples and the results averaged.

Example

A lens housing having the shape shown in Figure 4 was prepared by first mixing: a.

forty (40) parts of a natural rubber commercially available as SMRC V50, b. sixty (60) parts by weight of zinc oxide filler (available as Red Seal zinc oxide from Amicore, The Netherlands), and c. two point five (2.5) parts by weight of a curing agent commonly employed for natural rubber, using a twin screw extruder. The compounded mixture was extruded in strips at 80 C and fed into an extrusion screw that injected into a mould. The mould tool was operated at cat 168 C cat five minutes. The mould was then released and the formed lens housing removed and allowed to cool to ambient conditions. The resilient lens housing had holes in each of the two sidewalls for engagement with a metal housing mounted in a road surface, thus forming the reflector assembly. The lens housing was also so formed so as to have four rod shaped holes for receiving and holding four rod-shaped reflectors, respectively, comprising microprismatic elements.

a ea. eve e _. r - - . . . Four solid rods having a circular cross-section of l 8.5 mm and a length of 17.3 mm wereprepared by machining four preformed black polyacetal rods (according to Deutsche Industrie Norm (DIN) 16985), commercially available as AD Delrin from DuPont. The rod was sized so as to fit firmly in the lens housing and was fashioned to have the flat end intended to be viewed by on-coming traffic bearing a shallow recess of a depth of cat 2 mm.

Retroreflective sheeting comprising microprismatic elements (available as Diamond Grade_ Retroreflective Sheeting # 983 from 3M Company, St. Paul, MN/USA) was cut into the shape of a circle using a heated die-cutting process. The retroreflective sheeting bore a layer of acrylic-based pressure-sensitive adhesive (PSA) on the reverse side, covered by a o removable protective liner. Die-cutting was performed on the sheeting bearing the PSA and the liner in a manner so that the optical demarcation stripes on the sheeting were oriented so that the stripe would be in a vertical position at the end once the completed reflector assembly was in installed in the road. The die-cutting process provided the sections of retroreflective sheeting in a predetermined and reproducible size and also served to heat-seal the edges of the retroreflective sheeting. Four separate pieces of retroreflective sheeting were prepared, each having the same circular shape and a 12.9 mm diameter.

The protective liner was then removed from the PSA layer on the reverse side of the sheeting and the sheeting thus adhered in the shallow recess on the flat end of the rod to be viewed by on-coming traffic. Four rods bearing microprismatic retroreflective sheeting on So one end were prepared in this manner. Pressure was applied to the entire surface of the sheeting after adhesion to the rod, especially near the periphery of the retroreflective sheeting so that it was firmly adhered to the polyacetal rod.

The four rods bearing retroreflective sheeting on one end were then placed on a support so that the retroreflective sheeting was uppermost and horizontal. A clear, self: healing polyurethane resin having a composition essentially the same as that of Example I of US Patent number 6258918. Resin and catalyst mixtures were degassed under vacuum, combined, then mixed in an in-line static mixer, and finally dispensed onto the retroreflective sheeting at about 30 C. About cat 0.4 ml of the heated polyurethane resin composition was cast onto the surface of the retroreflective sheeting. The resin flowed over so the entire surface of the retroreflective sheeting and flowed further towards the edge of the polyacetal rod and finally stopped flowing at the edge of the rod to form a meniscus-shaped covering resembling a lens. In its final form, the polyurethane layer covered the surface of e r . .- e . e e

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. . the sheeting and part of the horizontal surface of the polyacetal rod, i.e. the surface exposed to the environment after the completed reflector is inserted into the resilient lens housing.

The completed reflectors bearing the retroreflective sheeting and the polyurethane protective layer were then moved to an infrared oven with an air temperature of 45 C with a s dwell time of cat 30 minutes to remove any volatile components. The reflectors were then moved to a curing oven held at a temperature cat 47 C and stored for cat three hours before removal. Alter removal the parts were allowed to return to ambient conditions over a 24 hr period. The thickness of the polyurethane lensshaped protective layer, above the upper surface of the retroreflective sheeting, was between 2 mm and 3 mm at the thickest part in lo roughly the centre of the lens.

The reflectors were then tested according to the Test Methods given above. Test results are summarized below in Table 1.

The four reflectors were then pressed into place, largely inside the resilient body, so that two surfaces bearing the microprismatic elements and the clear protective lens were embedded in both the first and second walls of the lens housing portion and were thus visible from each traffic direction.

Table 1

Test Type Before Test After I est Abrasion Test a. Height (mm) 1.09 mm 1. 08 mm b. Visual inspection Clear, no cracks, no Few small scratches scratches, visible integrity of component parts c. Coef. of luminous intensity, R 114.6 71.9 (millicandellas/lux) Hot / cold Water Shock Test Clear, no cracks, visible No visible change integrity of component parts UV Stability Test 1. Coef. of luminous intensity, R 1 14.6 1 13.6 (mcdl/lux) ë. .' ' ' e e, ea ee ea. a t a 2. Visual inspection Clear. No cracks, visible No visible change.

integrity of components.

Environmental Test Clear. No cracks. Visible No visible change integrity of components.

Comparative Example 1 Reflectors were removed from a reflective road marking stud commercially available from Light-Dome Road Marker Inserts Ltd. (Fareham, Hampshire, Great Britain). Such reflectors were from a white, reflective, two-way, permanent, Repressible road stud, commercially described as a l,ight Domed Insert (white rubber body and white reflectors).

The reflectors in the Light-Dome(E product comprise a detritus resistant glass and are classified as permanent Repressible road studs with glass reflectors, embedded type, l o according to definitions from British Standard BS EN1463-Part I:1998. The glass reflectors were tested according to the test methods given above. Test results are summarized below in

Table 2.

Table 2

Test Type Before Test After Test Abrasion Test a. Height (mm) 3.81 3.58 b. Visual Inspection Scratching and flattening of upper surface.

c. Coef. of luminous intensity, R 72.426.6 (mcdl/lux) I lot / cold Water Shock Test Clear. No cracks. VisibleNo visible change.

integrity of components.

UV Stability Test Clear. No cracks. VisibleNo visible change.

integrity of components.

I. Coef. of luminous intensity, R 72.444.8 (mcdl/lux) e . . . 2 Visual inspection Clear. No cracks. Visible No visible change.

integrity of components Environmental Test Clear. No cracks. Visible No visible change.

integrity of components.

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Claims (10)

1. A reflector assembly for use in association with a housing to provide a road surface marker, said reflector assembly comprising a resilient body adapted to engage with said housing so as to removably hold and position said resilient body in said housing, said resilient body comprising a lens housing portion for housing one or more reflectors, each of said reflectors comprising a rod having opposite first and second ends, at least the first end comprising a retroreflective sheeting having on one side thereof microprismatic elements, said retroreflective sheeting being provided such l o that the microprismatic elements are facing inwardly of said rod and said first end of said rod being covered with a clear self-healing protective layer of a synthetic resin protecting said retroreflective sheeting on said first end of said rod and defining a lens member.

2. A reflector assembly according to claim 1 wherein said synthetic resin comprises a polyurethane.

3. A reflector assembly according to claim I wherein said synthetic resin comprises a polyurethane that is the reaction product of a first and a second component, said first component comprising one or more polyols having an equivalent weight of 28 to 3000 and said second component comprising a primary polyisocyanate having an average of more than 2 isocyanate groups per molecule.

4. A reflector assembly according to claim I wherein said rod of said reflector has a circular or oval cross-section.

5. A reflector assembly according to any of the previous claims wherein said lens housing portion has opposite first and second walls and each of said first and second walls having one, two or more reflectors.

6. A reflector assembly according to claim I wherein said first and second ends of said rods of said reflectors each comprise said retroreflective sheeting and each of said first and second end of said rod being covered with said clear self-healing protective layer of a synthetic resin, said lens housing portion of said resilient body having opposite first and second walls, and said reflectors being provided in said lens housing portion such that one of said first and second ends of the rod of a reflector provides a reflecting surface on one of said first and second walls and the other end . eve . . . . _ . . . of said first and second end of said rod provides a reflecting surface on the other wall of said first and second walls.

7. A reflector assembly wherein said lens housing portion defines an upper portion of said resilient body, said resilient body further having a hollow base portion wherein said upper portion can be depressed upon application of pressure on said resilient body.

8. A reflector assembly according to claim 7 wherein a depression of said upper portion into said hollow base portion causes cleaning of said lens members of said one or more reflectors.

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9. A reflector assembly according to any of the previous claims wherein said rod is rigid and of plastic and wherein said rod is hollow or solid.

10. A reflector assembly according to any of the previous claims wherein at said rod is closed near its first end so as to define a recess at the first end and wherein said retrorellective sheeting is provided in said recess.

1 1. A reflector assembly according to any of the previous claims wherein said retroreflective sheeting is adhesively secured to said rod.

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