Raw Materials For Hot-melt Adhesives

Tackifiers
Tackifiers are among the key additives for EVA hot-melt adhesives. Relying solely on the inherent bonding strength of the molten base resin is insufficient; as the temperature drops, the adhesive fails to adequately wet or penetrate the paper, thereby losing its bonding capability and failing to achieve the desired bond. Incorporating tackifiers enhances the adhesive's fluidity and wettability on the substrate, improves bonding performance, and ensures the required bond strength. Common tackifiers include rosin, modified rosin (grades 138 or 145), C5 petroleum resins, C9 petroleum resins, and terpene resins.

 

Viscosity Modifiers
Viscosity modifiers are another essential additive for hot-melt adhesives. They serve to increase fluidity and regulate the solidification rate, facilitating rapid and secure bonding. Without them, the adhesive's viscosity might be too high-impeding flow and preventing effective penetration into the book signatures, which would result in a weak bond. Adding low-softening-point viscosity modifiers ensures good penetration and a strong, secure bond. Common choices include paraffin wax, microcrystalline wax, synthetic waxes (PE or PP), and Fischer-Tropsch wax.

 

Antioxidants
Appropriate amounts of antioxidants are added to prevent the premature aging of EVA hot-melt adhesives. Since the adhesive can undergo oxidative decomposition at the high temperatures required for melting, antioxidants ensure that bonding performance remains stable under these high-temperature conditions.