Key words: HMA, EVA, SIS In the field of paper food packaging (such as disposable paper cups, milk cartons, pastry paper bags, paper boxes, etc.), EVA hot melt adhesives are widely used for bonding due to their cost advantages. EVA raw materials with a VA content of 20%~30% are commonly selected, which deliver a balanced level of initial tack and cohesion. However, they have obvious deficiencies in bonding strength, temperature resistance and open time, making them unable to fully meet the production and application requirements of packaging products. The following solutions can be adopted to address these drawbacks: 1. Improving Temperature Resistance by Adding High-Cohesion Elastomers Adding 10%–20% high-styrene SIS is the core solution. The styrene hard segments of SIS boost the cohesive strength of the adhesive layer. Its thermally stable molecular structure raises the maximum temperature resistance of EVA hot melt adhesive, preventing the adhesive layer from softening easily at elevated temperatures (60–80°C). This stops packaging from delamination when holding hot beverages or exposed to high ambient temperatures. By contrast, POE can improve flexibility yet offers weaker temperature resistance enhancement compared with SIS. Blending High-Melting-Point Additives Raise the proportion of microcrystalline wax (melting point: 70–90°C) or Fischer-Tropsch wax (melting point above 100°C), and cut the dosage of low-melting paraffin wax. This improves the adhesive’s heat resistance and anti-softening performance. Meanwhile, add antioxidants (e.g., 1010, 168) to restrain oxidative degradation under high temperatures and extend durable heat resistance. 2. Boosting Bonding Strength Synergistic Combination of SIS and Tackifier Resins The non-polar soft isoprene segments of SIS enable superior wetting and bonding with paper substrates. When compounded with tackifier resins such as hydrogenated rosin glyceride and high-softening-point terpene resin, both initial tack and ultimate bonding strength can be improved simultaneously. This resolves the poor adhesion of neat EVA on non-polar surfaces. Optimizing EVA Grade and Formulation Ratio Select EVA with a moderate melt index (MI 15–30) to prevent insufficient cohesive strength caused by excessively high MI. If needed, blend a small amount of low-density polyethylene (LDPE). Molecular chain entanglement reinforces the cohesion of the adhesive layer, indirectly upgrading the peel resistance after bonding. 3. Adjusting Open Time to Match Production Line Processes Regulation via SIS Grades and Waxes Open time must match the coating-lamination cycle of packaging machines, normally ranging from several seconds to more than ten seconds. SIS with low styrene content (15%–20% styrene) features superior fluidity to extend open time; high-styrene SIS speeds up solidification and shortens open time. Meanwhile, microcrystalline wax slows down cooling to prolong open time, while a higher proportion of paraffin wax accelerates solidification and cuts open time. Precise tuning of the two wax ratios fulfills specific process requirements. Melt Viscosity Control Moderately adjust the loading of extender oil (paraffin oil) and plasticizers. Excessively high viscosity causes rapid cooling right after coating (too short open time), whereas overly low viscosity brings glue overflow (excessively long open time). This control ensures lamination and solidification finish within the valid operating window.