Thermoplastic material is applied hot and cures on laying. It has good durability and is suitable for use on all roads. Cold plastic (2-component material) consists of two parts which are a pigmented resin base and a catalyst. The product cures by chemical activity. With cold plastic you get a wear resistant road marking with low dirt pick up. Paint is a typically a low-cost marking and has been in widespread use since approximately the early 1950s.
All materials can hold glass beads, for night time reflectivity, that are applied into the wet material immediately after the application of the line.
Read more about each material in the below categories.
In some countries it is necessary to have a certificate for the materials used. The producer of the material makes samples of the marking, and this is then tested by an institute in the country where the marking shall be performed.
Thermoplastic material is mainly composed of synthetic resin, glass beads, colored pigments, timber fillers, and other additives. At room temperature, it is a solid powder. The thermoplastic material is usually melted in a thermoplastic preheater, before being transferred into the material tank of a line marking machine.
The Thermoplastic marking cures quickly and adheres strongly to the road surface. Thermoplastic material is most commonly produced in yellow and white. The white mainly contains titanium white, zinc oxide, lithopone, while the yellow is mainly heat-yellowing lead. The particle size of the material influences the flow, sedimentation and also the surface processing. Glass beads are mixed in or applied to the surface in order to improve the visibility at night and improve brightness and durability of the marking. The glass beads are colorless, and function as retroreflectors.
These lines can be made with a thick layer, as a profiled structured marking, to produce a rumble strip effect.
MATERIAL REQUIREMENTS FOR THE BORUM DOT' N LINE EXTRUDER
The Dot’n line requires special types of premium thermoplastic material that fulfilLs the demands for thermal stability and viscosity.
To have a practical way of handling the material, the following general guidelines have been given by leading thermoplastic material manufacturers:
- A melting temperature (and working) range: 180-210 °C (356-410 °F).
- Relatively slow agitator speed in the thermoplastic tank (the boiler): Max 30 rpm
- Minimum and maximum heating time - achieve the correct homogenization but also avoid a degrading of the thermoplastic: From ½ to max 6 hours (total heating of the material – incl. the time in a premelter)
Paint consists of three main components: pigments, resins or binders, and water or solvents. Pigments are finely grounded materials that give out colors or block out the surface beneath it. They may contain other materials such as UV stabilizer, and fillers which bring out the color pigments to the required level. Resins or binders are the glue of the paint to bind pigment and glass beads together to the road surface. The pigments and resins are mixed with water for water-based paints and solvents for solvent-based paints so that they can be applied onto the road surface.
Solvents that are used can be naphtha, toluene, methanol, methylene chloride, and acetone. Sometimes glass beads are mixed in with the paint. Also a separate bead gun is used to spray glass beads on to the wet paint during the application. Due to environmental concerns, some countries has some restriction on the solvent-based paints.
After application, drying time of the different paints differs, cones and traffic management might be needed.
2- component material or CAP systems (98:2)
There are different kinds of 2-component systems (CAP systems) – at Borum we have chosen to mainly work with the 98:2 system for the larger machines. This system consists of 2 components; 98% paint and 2% hardener to cure the material.
When initiated Component A is combined with the accelerated Component B the curing process starts immediately! The pot-life when mixed at room temperature is about 3 minutes – higher temperature reduces pot-life. Working with 2-component is temperature related, the viscosity of the material is different on cold mornings and hot afternoons, so you have to adjust the material to make it suitable for the application. With 2-component you get a wear resistant road marking with good visibility, durability and low dirt pick up.
NB! When working with 2-component whenever the application is stopped, application equipment has to be cleaned from the cold plastic mixture immediately!
Recommendations regarding viscosity of the material for application:
- Dots min. 8500 cp (centipoise)
- Agglomerate min. 8000 cp
- Extruder min. 6500 cp (for making ribs approx. 8500 cp)
- Paint – depending on the size of the nozzle