Our well established organization has gained expertise in offering unparalleled range of Thermoplastic Road Marking Paints for our valued customers. Formulated using high quality chemicals and other raw-material along with advent technology, these paints has superior color stability and weathering resistance property. Widely used for surface preparation, these Thermoplastic Road Marking Paints can be made available as per specific demands of clients.
We offer unmatched services in the field of Thermoplastic Road Marking, from paints to glass beads and machines to application we provide total solutions in the said field.
Hot-applied thermoplastic is heated to 180 - 200 oC in a pre-heater with adequate agitation till the material becomes a homogenised liquid. Thereafter the material is transferred into the kettle of a screed, ribbon or spray device from where the material is laid at its specified width and thickness. Glass beads are immediately applied to provide initial retro-reflectivity.
The key criteria of the pre-heater and kettle are as follows:
There are three types of glass bead dispensers namely the gravity system, gear feed system and pressure type system. Proper glass bead dispensing implies that the glass bead should be evenly dropped, embedded upto 50 to 60 %, and should not have an angular entry into the thermoplastic film. The pressure type system, which is mostly found in automatic and semi-automatic machines, is best suited, as the angle of entry and application pressure is controlled. In the case of gravity feed, embedment is usually not an issue but angle of entry is and the case is reversed in gear feed systems.
There are various thermoplastic dispensing devices, the most common being the screed type, which is usually semi automatic or manual. In extrusion type devices, a screw pushes the material to create a well-defined line. Extrusion devices are usually automatic. Spray application of thermoplastic is possible wherein the molten material is sprayed using compressed air. Each dispensing device would require a different formulation to achieve the desired properties of the thermoplastic stripe.
The thermoplastic material should be applied at a temperature range between 180-200 oC depending on ambient weather conditions. The indicated material temperature should preferably be maintained at the point of road contact. Applying thermoplastic at proper applications temperature is one of the most critical factors affecting the bonding to the substrate. The thermoplastic material temperature in the kettles, applicators, and at the exit of the dispensing device should be periodically verified with a non-contact infrared thermometer.
The resin binders used in alkyd and hydrocarbon thermoplastic material starts degrading at temperature of 220 oC and above. If thermoplastic materials are held at 220 oC and above for more than 4 hrs, it can be expected that the material viscosity and temperature relationships will not be constant and material may not be suited for application.
The thermoplastic thickness should be uniform and consistent throughout the total length of the job. Overall discrepancies in the application rate and the total thermoplastic thickness will affect the durability and performance of the line.
The glass beads are to be evenly dropped on the hot thermoplastic stripe immediately after its application, embedding and anchoring at a depth of 50-60%.The purpose of glass spheres is to be provided initial night time retro reflectivity of the pavement marking.
The applied thermoplastic markings should be inspected continually for overall workmanship. Markings should be of the specified width, with clean-cut edges. The drop-on glass bead application should appear uniform on the entire marking surface. Over saturation with glass spheres can cause excessive brittleness to the line, reduced retro-reflectivity and cause premature abrasion. The hardened thermoplastic should resist deformation, dirt pick up, etc. by traffic within 10 to 15 minutes of application.
The marking should be firmly bonded to the pavement surface. If the thermoplastic marking can be easily removed from the pavement with the use of a putty knife, and little or no bituminous substrate is on the back of the marking, then it can be assumed that there is no sufficient bond to the substrate. There must be fusion with the bituminous pavement to ensure maximum bond strength. Concrete bond strength can be checked by attempting to force separation with a tiff putty knife.
Some typical concerns regarding thermoplastic can be identified as bonding, abrasion, cracking, blistering, thickness and retro-reflectivity.
Failure to adhere or bond to the surface is normally due to improper application such as low temperatures, dirty pavement, moisture, improper primer/sealer application, scorching of the material, improper mixing etc. Where asphalt is on the back of the thermoplastic material then an adequate bond is definitely indicated. Lack of an adequate bond is evidenced by clean separation of the thermoplastic from the surface.
This is a gradual wearing away of the material from the top down. Abrasion is not directly related to application. However, since the life of the marking is proportionate to its overall thickness, the application of markings that are thinner than specified will result in earlier abrasion losses.
The appearance of cracked lines may be due to pavement cracking or temperature stress. Durability will usually not be affected. If excessive cracking immediately appears, without pavement cracking or repeated extreme temperature changes, the material may have been under- or over- heated prior to application, or made brittle by excessive bead application.