GB2255099A

GB2255099A - Road marking compositions

Info

Publication number: GB2255099A
Application number: GB9208079A
Authority: GB
Inventors: Christopher Day
Original assignee: R S Clare & Co Ltd
Current assignee: R S Clare & Co Ltd
Priority date: 1991-04-03
Filing date: 1992-04-03
Publication date: 1992-10-28
Anticipated expiration: 2012-04-03
Also published as: GB9106946D0; GB2255099B; GB9208079D0

Abstract

A road marking composition comprises a synthetic resin, glass beads and aggregate. At least 5% by weight of the glass beads are retained by a 1.18mm sieve. The resin may be a tall oil resin. The composition may further comprise a thixotropic agent, e.g. silica, clay or a fibrous material, extenders or fillers, pigments, plasticizers, aggregates and glass beads satisfying BS6088. The aggregate may be silica sand. The composition has improved retroreflectivity in wet conditions, and may be screeded or extruded onto the road surface.

Description

Title: Road Marking Compositions DESCRIPTION This invention concerns road marking compositions.

Reflective road marking compositions are known which are sprayed, screeded or extruded onto the road surface followed by a layer of small glass beads. The compositions already contain small glass beads and according to BS 3262 substantially all the glass beads used are less than 1.18mm in size. The purpose of the glass beads is to reflect light from headlamps. As the surface applied beads wear off, then the beads mixed with the composition become exposed and continue to provide retroreflectivity.

Road marking compositions made according to BS 3262 also contain aggregates for skid resistance and pigments to give a desired colour A road marking composition made according to BS 3262, therefore, has good daytime visibility, skid resistance and night time visibility in dry weather. However, in wet conditions night time visibility is very poor, since a water layer on the road surface covering the road marking causes light from a headlamp to be randomly scattered, so obscuring the marking.

An object of this is to provide a road marking composition of improved retroreflectivity in wet conditions.

According to the invention there is provided a road marking composition comprising a synthetic resin, glass beads and aggregate, wherein at least 5% by weight of the glass beads are retained by a 1.18mm sieve.

Preferably 5 to 95, especially 25 to 75, more especially 40 to 60, yet more especially 45 to 55% by weight of the glass beads used in the compositions of the invention are retained by a 1.18mm sieve.

Compositions of the invention may comprise aggregate in accordance with BS 3262, although for improved skid resistance aggregates of particle sizes corresponding to the glass bead sizes may be used.

Preferably said larger glass beads and aggregates have particle sizes in the range of 1.5 to 3.5mm, especially in the range of 1.6 to 2.3mm. The proportion of larger glass beads to aggregate is preferably in the weight ratio range of 10:1 to 2:3, especially 3:2 to 2:3.

The synthetic resins used in the compositions of the invention are preferably hydrocarbon resins of which a typical example is tall oil resin.

It is important that when the road marking compositions of the invention are in a liquid state, eg.

in a preheater of an applicator, larger particles therein do not settle to the bottom, otherwise the composition would be unusable. Furthermore, the compositions of the invention preferably have desirable rheological properties to allow the liquid composition to flow during application and to ensure that larger particles protrude from the applied marking. Therefore, it is advantageous to include in the compositions of the invention a thixotropic substance.

Examples of suitable thixotropic substances for compositions of the invention include silicas, clays and fibrous materials.

The road marking compositions of the invention may contain other customary ingredients of resin based road marking compositions including one or more of extenders or fillers, pigments, plasticizers, aggregates and glass beads. The glass beads referred to here are those which satisfy BS 6088. A typical aggregate might be silica sand.

Suitable extenders or fillers for compositions of the inventions include finely divided particulate materials that are relatively inert. Whiting is a typical example.

The pigment chosen for the road marking composition will depend, of course, on the desired colour of the road marking to be produced. Titanium dioxide is a typical example of a pigment for producing a white road marking.

Any suitable plasticizers or mixtures thereof may be used in the compositions of the invention. For a synthetic hydrocarbon resin, plasticizers such as mineral oils and paraffin wax have been found to be suitable. The combined amount of resin and plasticizer used in the compositions of the invention is preferably in the range of from 15 to 25, especially in the range of from 18 to 22% by weight of the composition.

The road marking compositions of the invention may be applied to a road surface by any suitable technique, of which screed application is a preferred technique. However, extrusion techniques may be used instead.

The road markings made from the compositions of the invention are believed to have good retroreflectivity in the wet due to the presence of the larger glass beads as well as good skid resistance due to the larger aggregates.

This invention will now be further described with reference to the following Example.

Example A road marking composition was prepared by mixing the following ingredients in the amounts stated in percent by weight: Glass beads - class A to BS 6088 10.0 Extender (whiting) 20.0 Pigment (eg. Ti02) 5.5 Plasticizer (mineral oil) 2.8 Plasticizer (paraffin wax) 2.2 Thixotrope (clay) 0.5 Fine aggregate (silica sand) 25.5 Glass beads (large eg. 1.5-3mm) 10.0 Aggregate (large eg. 1.5-3mm) 10.0 Synthetic hydrocarbon resin 13.5 The resultant road marking composition when deposited by spraying, screeding or extrusion gave a road marking having a good skid resistance and good retroreflectivity in the wet, as well as durability, dry retroreflectivity and daytime visibility.

Claims

1. A road marking composition comprising a synthetic resin, glass beads and aggregate, wherein at least 5% by weight of the glass beads are retained by a 1.18mm sieve.

2. A composition as claimed in claim 1, wherein 5 to 95% by weight of the glass beads are retained by a 1.18mm sieve.

3. A composition as claimed in claim 1, wherein 25 to 75% by weight of the glass beads are retained by a 1.18mum sieve.

4. A composition as claimed in claim 1, wherein 40 to 60% by weight of the glass beads are retained by a 1.18mm sieve.

5. A composition as claimed in claim 1, wherein 45 to 55% by weight of the glass beads are retained by a 1.18mm sieve.

6. A composition as claimed in any one of claims 1 to 5 comprising aggregate in accordance with BS 3262.

7. A composition as claimed in any one of claims 1 to 6, wherein the aggregate has particle sizes corresponding to the glass beads sizes.

8. A composition as claimed in any one of claims 1 to 7, wherein the larger glass beads and aggregates have particle sizes in the range of 1.5 to 3.5mm.

9. A composition as claimed in any one of claims 1 to 7, wherein the larger glass beads and aggregates have particle sizes in the range of 1.6 to 2.3mm.

10. A composition as claimed in any one of claims 1 to 9, wherein the proportion of larger glass beads to aggregate is in the weight ratio range of 10:1 to 2:3.

11. A composition as claimed in claim 10, wherein the proportion of larger glass beads to aggregate is in the weight ratio range of 3:2 to 2:3.

12. A composition as claimed in any one of claims 1 to 111, wherein the synthetic resin a hydrocarbon resin.

13. A composition as claimed in claim 12, wherein the synthetic resin is tall oil resin.

14. A composition as claimed in any one of claims 1 to 13, further comprising a thixotropic agent.

15. A composition as claimed in claim 14, wherein the thixotropic agent is selected from silicas, clays and fibrous materials.

16. A composition as claimed in any one of claims 1 to 15, further comprising one or more of extenders or fillers, pigments, plasticizers, aggregates and glass beads satisfying BS 6088.

17. A composition as claimed in claim 16, wherein the aggregate is silica sand.

18. A composition as claimed in claim 16 or 17, wherein the filler or extender is a finely divided particulate material that is relatively inert.

19. A composition as claimed in claim 187, wherein the filler or extender is whiting.

20. A composition as claimed in any one of claims 16 to 19, wherein the plasticizer is a mineral oil or a paraffin wax.

21. A composition as claimed in any one of claims 16 to 20, wherein the combined amount of resin and plasticizer is in the range of 15 to 25% by weight of the composition.

22. A composition as claimed in claim 21, wherein the combined amount of resin and plasticizer is in the range of 18 to 22% by weight of the composition.

23. A road marking composition substantially as hereinbefore described with reference to the foregoing Example.