The mixing and melting of approximately 2.5 kg of EVA valve-sealed packaging bags with 1 ton of hot-melt coating significantly affects the compressive strength, glass bead adhesion, crack resistance, and weather resistance of the marking coating. The following is a breakdown of each effect:
1. Impact on Compressive Strength (at 60℃)
JT/T280-2022 requires a compressive strength ≥2MPa at 60℃. High-compressive-strength hot-melt coatings are prone to cracking. Adding flexible packaging bags greatly improves the crack resistance of the coating.
The softening effect of the EVA flexible film bag: With a low melting point, it retains some flexibility even at -20℃, reducing the overall rigidity of the hot-melt coating.
Reduced Compressive Strength: Traditional hot-melt coatings (petroleum resin + filler) have high rigidity (≥2MPa) at 60℃, but adding 40 double-layer valve-sealed film bags improves the flexibility of the marking coating.
2. Impact on Glass Bead Adhesion
The adhesive strengthening effect of the EVA flexible bag:
Improved melt wettability: The flexible film has good fluidity after melting, which can better encapsulate the glass beads and improve adhesive strength.
Elastic cushioning reduces detachment: The high elongation at break of the flexible film bag allows it to deform elastically under traffic loads, reducing the risk of glass beads detaching due to impact.
Practical effects:
Increased glass bead adhesion rate: The impact resistance of the glass beads is improved, delaying the decay of the retroreflective brightness coefficient of the road markings.
Improved long-term durability: Higher glass bead retention rate under dynamic loads, extending the reflective life of the road markings.
3. Impact on crack resistance
The toughening effect of the flexible film bag:
Enhanced stress dispersion ability: The high elongation of the double-layer flexible film bag allows it to absorb stress caused by road surface shrinkage or traffic vibration, reducing crack propagation.
Improved low-temperature crack resistance: Below -20℃, the double-layer flexible film bag still maintains flexibility, reducing the risk of low-temperature brittleness.
Actual Results
Reduced Cracking Rate of New Hot-Melt Markings: Compared to pure petroleum resin systems, the cracking probability can be reduced by 30%-50%.
Reduced Microcracks: The marking surface is smoother, reducing peeling problems caused by cracks.
4. Impact on Coating Weather Resistance
Weather Resistance Characteristics of Double-Layer Flexible Film Bags
UV Resistance: The double-layer flexible film bag raw material is modified with EVA+, which can effectively reduce yellowing and chalking of the marking coating under long-term ultraviolet radiation.
Damp Heat Resistance: The double-layer flexible film bag has extremely low moisture absorption, but its long-term durability is not affected in high temperature and high humidity environments.
Actual Results
Modified EVA Double-Layer Flexible Film Bag (with added anti-aging agents): Weather resistance life can be extended to more than 5 years.
5. Summary of Overall Impact
The addition of EVA film-grade packaging bags (40 bags, approximately 2.5 kg of flexible adhesive added to 1 ton of paint) reduces the brittleness of hot-melt markings and significantly improves glass bead adhesion, crack resistance, low-temperature toughness, and weather resistance.
Film-grade double-layer EVA valve-sealed flexible bags can be an economical and effective solution for improving the overall performance of hot-melt markings.
