High content polyamide hot-applied thermoplastic composition
A hot-applied thermoplastic pavement marking composition comprising a modified polyamide resin in the range of between 3 and 10 percent by weight, rosin-modified esters, a copolymer, 30-70 percent by weight of a glass bead intermix, a range of between 1 and 15 percent by weight of either white or yellow pigment, and one or more plasticizers, inorganic fillers, waxes, antioxidants or light stabilizers, and methods of applying a hot-applied thermoplastic pavement marking composition.
1. A hot-applied thermoplastic pavement marking composition comprising:
a modified polyamide resin from about 3 to about 10 weight percent;
a rosin-modified ester;
a copolymer;
a glass bead intermix of at least 30 weight percent;
a colored pigment from about 1 to about 15 weight percent; and
at least one of a plasticizer, an inorganic filler, a wax, an antioxidant or a light stabilizer;
wherein the glass bead intermix comprises AASHTO Type 1 glass beads and one of AASHTO Type 3 glass beads or AASHTO Type 4 glass beads, and the glass beads impart retro-reflectivity from about 200 to about 2000 mcd/m2/1x.
2. The composition of claim 1 , wherein the composition comprises from 15% to about 30% AASHTO Type 1 glass beads and from 15% to about 30% AASHTO Type 3 glass beads.
3. The composition of claim 1 , wherein the composition comprises 25% AASHTO Type 1 glass beads and 25% AASHTO Type 4 glass beads.
4. The composition of claim 1 , wherein the ester is a pentaerythritol modified ester, a maleic modified glycerol rosin ester, or an ethylene maleic anhydride.
5. The composition of claim 1 , wherein the copolymer is ethylene vinyl acetate.
6. The composition of claim 1 , wherein the plasticizer is at least one of castor oil or di-isononyl phthalate.
7. The composition of claim 1 , wherein the light stabilizer is a hindered amine.
8. The composition of claim 1 , wherein the colored pigment is white or yellow.
9. The composition of claim 1 , wherein the glass bead intermix ranges from 30 to about 70 weight percent.
10. The composition of claim 1 , wherein the composition is substantially free of sebacic acid.
11. The composition of claim 1 , wherein the composition has a viscosity between 1000 cps and 10,000 cps measured at 190 ° C. by a Brookfield viscometer.
12. The composition of claim 11 , wherein the viscosity is between 1500 cps and 3000 cps.
13. The composition of claim 1 , wherein the composition has a softening point between 115 ° C and 140 ° C.
14. The composition of claim 1 , wherein the composition has a softening point between 120 ° C. and 130 ° C.
15. A method for applying the composition of claim 1 , comprising:
heating the composition; and
extruding the composition onto a pavement surface.
16. The method of claim 15 , wherein the composition is heated to a temperature between 400 ° F. and 440 ° F.
17. The method of claim 15 , wherein a thickness of the extruded composition is from about 60 mil to about 150 mil.
18. The method of claim 17 , wherein a thickness of the extruded composition is from about 90 mil. to about 120 mil.
19. The method of claim 15 , further comprising applying a top dressing of glass beads to the extruded composition.