WHAT IS THERMOPLASTIC?
What is thermoplastic?
Thermoplastic is a pavement marking that has been used in the U.S. since 1958 with continuing good results. A mixture of glass beads, binder, pigment and filler materials, thermoplastic, as its name suggests, becomes liquid when heated.
What does each ingredient in the mixture do?
What thermoplastic is made of and how it is applied are the keys to its durability and long lasting retro-reflectivity. When properly formulated and correctly applied, thermoplastic should last from five to eight years under normal traffic conditions.
Key factors in the correct application of thermoplastic
Temperature is the most important factor in the proper mixing, melting and bonding of thermoplastic.
Thickness of the applied thermoplastic should be as specified. A minimum thickness of 90 mils is important to the material’s ability to hold the heat necessary for good bonding. The thermal bonding that occurs when application is at the proper thickness ensures the thermoplastic’s durability and long term retro-reflectivity. A minimum thickness of 30 mils is required to hold the heat necessary for proper bonding when recapping a line because of poor reflectivity of inadequate thickness.
Being raised above the road surface, combined with the retro-reflectivity produced by the glass beads, makes thermoplastic more visible from a distance and at night. The thickness also contributes to improved retro-reflective performance in wet conditions and the exceptional durability of the product.
The amount of glass beads, both mixed in with the compound and dropped on the installed line, must be correct.
Types of thermoplastic
Two types of thermoplastic are available and recommended according to use. The two, hydrocarbon and alkyd, take their names from their binder types. Hydrocarbon thermoplastic is made from petroleum derived resins.
Alkyd thermoplastic contains a naturally occurring resin that is resistant to petroleum products.
Both hydrocarbon and alkyd thermoplastic are available in granular or block form, packaged in 50 pound bags or boxes, respectively. The application properties of each should have a guaranteed shelf life of one year when stored inside at a temperature less than 100° F.