GB2279360A

GB2279360A - Thermoplastic product for road marking

Info

Publication number: GB2279360A
Application number: GB9412084A
Authority: GB
Inventors: Douglas Alan Gibbin
Original assignee: GLOWORMS Ltd
Current assignee: GLOWORMS Ltd
Priority date: 1993-06-17
Filing date: 1994-06-16
Publication date: 1995-01-04
Anticipated expiration: 2014-06-16
Also published as: GB9312455D0; GB2279360B; GB9412084D0

Abstract

A thermoplastic product such as may be used to mark roadways and adjacent surfaces contains both a phosphorescent pigment and a non-phosphorescent pigment The product may be in the form of a paint or of discrete pieces and in use allows the light emitted from the headlights of one road vehicle to be harnessed for the benefit of the drivers of following vehicles. The product may contain polycarbonate.

Description

Thermoplastic Product for Road Marking.

The present invention concerns thermoplastic materials such as are used to mark roads and surfaces near roads.

Road markings of the conventional type are usually made using paint containing white or coloured pigment. This paint may often be of such composition as to produce a relatively thick raised marking, sometimes applied over a textured base so as to provide audible warning to motorists crossing the markings. The painted markings are often accompanied by reflective strips or studs which indicate the course of the road markings to motorists driving in the dark using headlights. However, reflective materials are only visible in the dark while a light is shining upon them, so when motor vehicle headlights have passed over a reflective stud, for example, it ceases to be visible until light from a following vehicle's headlights reaches it. Thus a line of reflective studs, for example, is only visible at night as far ahead of a vehicle as the range of its headlights allows.

This invention aims to provide a solution to the problem of improving the visibility of road markings at night.

Accordingly, the thermoplastic product for road marking according to the invention contains a phosphorescent pigment and a non-phosphorescent pigment. The use of a phosphorescent pigment in road marking materials enables the road marking to glow for a considerable time after it has been illuminated. In this way some of the limitations of using reflective road marking materials are overcome.

The thermoplastic product may preferably be in the form of a paint which may be applied either directly to a road surface or to a prepared base layer. The thermoplastic product may also take the form of moulded or extruded pieces of material which may be applied to the surface of roads, kerbs or similar surfaces. In one preferred form, thermoplastic product in the form of a strip is provided with a means for attaching the strip to a kerb edge. Such means may comprise an integral spike for insertion between adjacent kerb stones.

Other means for attaching a piece of the thermoplastic material to a surface are also envisaged, for example clips or adhesive may be used for the purpose, or it may be inset into a road surface.

The strips may be flat, curved or angled to suit the surface to which they are to be applied.

The phosphorescent pigment is preferably based on a zinc sulphide, zinc cadmium sulphide or an alkaline-earth sulphide. Such pigments can absorb light energy from a light source such as a vehicle headlamp and then re-emit some of the light over a relatively long period of time, although the brightness of the emitted light begins to decay after a short period.

The thermoplastic product contains nonphosphorescent pigment in addition to phosphorescent pigment so that it can easily be seen in daylight conditions. The colour and type of non-phosphorescent pigment used may be chosen according to the desired use of the product. For example, markings along the side and centre of a road are often white and so the non-phosphorescent pigment in a thermoplastic product for that use would be a white pigment, which is preferably titanium dioxide.

The thermoplastic product comprises, in addition to the phosphorescent pigment and non-phosphorescent pigment, the thermoplastic material itself, which is preferably a synthetic resin, for example a plasticised synthetic resin. A preferred such thermoplastic material, especially when the product is in the form of discrete pieces of material such as strips, is a polycarbonate.

The thermoplastic product may also contain other materials such as extenders or other solids, possibly including a reflective material such as glass beads. Although the thermoplastic product in the form of a paint may be solvent- or ' dispersion- based, it is preferable that the product is formulated to be suitable for application by hot-application techniques.

The thermoplastic product may have a wide range of different compositions. As a general indication, however, the ratio of phosphorescent pigment to thermoplastic material is usually in the range from 0.1:1 to 4:1 by weight, and preferably of the order of 2:1 in paints and about 0.1:1 to 1:1 in discrete pieces of the thermoplastic product.

The thermoplastic product may be used alone or in combination with other materials. For example, the thermoplastic product in the form of paint may be applied over an adhesion-promoting base or over a white base to give added brightness to the paint. The thermoplastic product in the form of a strip may have a reflective material or other material applied to a surface of the strip, possibly in a contrasting colour.

The thermoplastic product according to the invention improves the visibility of road markings beyond the reach of headlights by virtue of its ability to harness the light emitted from one vehicle's headlights for the benefit of the drivers of following vehicles, thus providing visible road-centre and edge marking in poor lighting conditions. Its use is therefore of particular advantage for marking the contours of roads which are unlit or which are only poorly lit.

Claims

1. A thermoplastic product for road marking, which contains a phosphorescent pigment and a non-phosphorescent pigment.

2. A thermoplastic product as claimed in Claim 1, wherein the thermoplastic material is a plasticised synthetic resin.

3. A thermoplastic product as claimed in either of the preceding claims, wherein the thermoplastic material is a polycarbonate.

4. A thermoplastic product as claimed in any of the preceding claims, wherein the phosphorescent pigment is based on a zinc sulphide, zinc cadmium sulphide or an alkaline-earth sulphide.

5. A thermoplastic product as claimed in any of the preceding claims, wherein the nonphosphorescent pigment is a white pigment.

6. A thermoplastic product as claimed in Claim 5, wherein the non-phosphorescent pigment is titanium dioxide.

7. A thermoplastic product as claimed in any of the preceding claims, wherein the ratio of phosphorescent pigment to the thermoplastic material is in the range from 0.1:1 to 4:1 by weight.

8. A thermoplastic product as claimed in any of the preceding claims, in the form of a paint.

9. A thermoplastic product as claimed in Claim 8, wherein the ratio of phosphorescent pigment to thermoplastic material is of the order of 2:1 by weight.

10. A thermoplastic product as claimed in any of Claims 1 to 7, in the form of a discrete piece.

11. A thermoplastic product as claimed in Claim 10, wherein the ratio of phosphorescent pigment to thermoplastic material is in the range from 0.1:1 to 1:1 by weight.

12. A thermoplastic product as claimed in either of Claims 10 and 11, in the form of a strip provided with means for attaching the strip to a kerb edge.