Why can’t EVA hot melt adhesive stick?

Why can’t EVA hot melt adhesive stick? Hot melt adhesive is a widely used adhesive in industrial production processes, but there may be inevitable non stick situations during application. So what are the reasons that affect the viscosity of hot melt adhesive? It is mainly divided into the following three categories:

1 EVA hot melt adhesive itself

1、 Viscosity: affects fluidity, permeability, spray performance, glue temperature, wire drawing, glue output, etc.

2、 Softening point: affects the temperature, heat resistance, and curing speed of the adhesive.

4、 Curing speed: affects production speed and adhesive strength.

5、 Affinity: Affects adhesive strength.

6. Cohesion: affects transfer resistance, peel strength, or shear string.

7、 Thermal adhesion force: affects the bonding effect.

8、 Temperature resistance, etc.: affects the temperature that the final bonding system can withstand.

9. Compliant with green environmental standards

II Substrate

1、 Polarity: Polarity attracts each other, and adhesives with similar polarity to the substrate have better bonding effects.

2、 Density: Loose substrates are prone to infiltration and require short pressurization time and high pressure

3、 Surface tension: Insufficient surface tension can affect wetting and adhesion. Corona treatment and polishing help improve adhesion.

4、 Surface temperature: If the surface temperature of the substrate is too low, it will affect the penetration, opening time, and penetration of the adhesive; If it is too high, the curing time will be prolonged.

5、 Moisture, surface treatment agents (such as talcum powder), and pollution: seriously affect the bonding strength.

6、 Adsorption and transfer performance: seriously affecting the aging and adhesion of EVA hot melt adhesive.

III. Equipment and Technology

1、 Speed: High speed production lines often lower the requirements for opening time, but increase the requirements for curing speed.

2、 Glue temperature: Increasing the glue temperature will prolong the opening time.

3、 Open distance: Open distance/production line speed=equipment open time, which should be less than the EVA hot melt adhesive open time.

4、 Pressure: Adequate pressure helps with the penetration, wetting, and curing of hot melt adhesive.

5、 Pressure holding time: The pressure holding time of the equipment should be designed to be longer than the curing time of the hot melt adhesive.

6、 Glue usage: Increasing the amount of glue used can replace the penetration and permeation of glue, prolong the opening time, slow down the curing speed, and accelerate the curing speed.