How to investigate the process and selection of EVA hot melt adhesive for wire drawing and overflow?

The drawing and overflow of EVA hot melt adhesive can affect the appearance of packaging, production pace, and material loss. Explain the troubleshooting approach from five aspects: temperature, glue amount, substrate, opening time, and equipment status, to help packaging and composite processing enterprises establish a more reliable glue selection process.

Core Keywords
EVA hot melt adhesive, hot melt adhesive wire drawing, hot melt adhesive overflow, packaging composite adhesive, hot melt adhesive selection

In the processes of carton sealing, packaging composite, handbag and pearl cotton bonding, the occurrence of wire drawing or overflow of EVA hot melt adhesive does not necessarily mean that the adhesive product itself is unqualified. Many problems arise from a mismatch between the glue, equipment, substrate, and on-site rhythm.

First, let’s take a look at the temperature. When the temperature is too low, the fluidity of the colloid is insufficient, resulting in uneven dispensing of the colloid, which can easily cause intermittent and drawn glue lines; Excessive temperature or prolonged insulation may cause changes in the colloidal state, increasing the risk of odor, coking particles, or unstable glue application. Suggest setting the temperature of the melt adhesive, rubber hose, and glue gun according to the supplier’s recommended range, and recording the actual temperature difference in different parts.

Look again at the amount of glue applied and the pressing time. When the amount of glue applied is too large, the glue liquid is squeezed out of the edge after compression, forming obvious overflow glue; Insufficient glue application may result in insufficient initial adhesion, leading to adhesive failure. Processing enterprises should conduct small-scale progressive testing based on substrate flatness, contact area, and line speed, rather than relying solely on a single empirical setting.

The changes in the substrate are often overlooked. The moisture content of paper, the surface condition of film coating, the surface state of pearl cotton, and the moisture-proof treatment of packaging materials may all affect wetting and adhesion. Before the new batch of materials is put into production, the samples can be retained and subjected to initial adhesion, peeling after cooling, and visual observation at actual temperature and line speed.

Finally, check the equipment. The accumulation of glue in the nozzle, impurities in the filter screen, unstable gaps between the rubber rollers, and unstable pressing pressure can all amplify the problems of wire drawing and glue overflow. Incorporating equipment cleaning, temperature calibration, and sample recording into the glue replacement process can significantly improve troubleshooting efficiency.

Sunlife can assist in selecting EVA hot melt adhesive based on specific substrates, adhesive application methods, and production line rhythms, providing sample testing and technical support; After determining the plan, stable supply can also be coordinated to reduce the impact of frequent rubber changes on production.

FAQ

Q: Is wire drawing solved solely by increasing the temperature?
A: No, it’s not. The temperature needs to be judged together with the state of the glue, the amount of glue applied, the nozzle, and the line speed. Blindly raising the temperature may bring new stability issues.

Q: Can the same adhesive be used for all packaging materials?
A: It is not recommended to assume universality directly. Different paper materials, film covering materials, and foam surfaces have different wetting and bonding properties on the adhesive, so sample testing should be conducted first.

Q: What results should be focused on during on-site testing?
A: It is recommended to observe at least the stability of the adhesive, wire drawing, overflow, initial adhesion, bonding state after cooling, and appearance.