Study of formulation variables of thermoplastic reflecting materials for traffic marking
Nine formulations of thermoplastic materials for traffic marking were prepared using a resin based on maleic anhydride modified with rosin in different proportions (18, 22 and 26%). As plasticizer a liquid coconut long oil alkyd resin (100% solids) was employed Hiding pigment was titanium dioxide; calcium carbonate and micronized tale were used as extenders. Coarse marble powder is used to facilítate the incorporation of glass beads. The operation was made employing a double Z mixer oil heated to obtain a mass temperature of 180-190 QC. The mixer was provided with two asynchronous arms rotating at 46 rpm. Dry and wet abrasión tests were carried out and the obtained results indicated that wearing valúes are three times greater in the case of the wet test. It is demonstrated that plasticization degree controls hardness variation as a function of temperature, determining a critical point which is the beginning of an abrupt reduction of hardness. Water absoption increases when plasticizer content increases. Matrix correlation of tests results was used to analize the obtained numeric valúes.