Suzhou Oushida Hot Melt Machinery Equipment Co., Ltd.

Why does PUR hot melt adhesive have drawing and bubbles?

Company Profile

Suzhou Oushida Hot Melt Adhesive Machinery Equipment Co., Ltd. is a high-tech enterprise specializing in the research and development, production, sales and technical consulting of hot melt adhesive intelligent spraying equipment.

Why does PUR hot melt adhesivehave drawing and bubbles?

PUR hot melt adhesive is widely used in household appliance assembly, electronic component gluing, automotive interior, woodworking edge banding, and other industries. The physical state of PUR hot melt adhesive changes with temperature within a certain temperature range. In the actual production process, wire drawing may occur. So why does PUR hot melt adhesive have wire drawing? There are several reasons.

Cohesive strength of PUR hot melt adhesive

The influence of cohesive strength of PUR hot melt adhesive on wire drawing is: the greater the cohesive strength, the obvious wire drawing phenomenon; on the contrary, the smaller the cohesive strength, the less wire drawing phenomenon will appear.

Curing time of PUR hot melt adhesive

The curing time of PUR hot melt adhesive is an important factor affecting the wire drawing phenomenon. Generally speaking, the probability of wire drawing of PUR hot melt adhesive with short curing time is low, because the filaments formed when the hot melt adhesive is sprayed out of the gun cannot be continuously stretched due to rapid curing, and are prone to breakage. Sometimes, no wire can be seen.

Influence of machine temperature

If the machine temperature is too low, the viscosity of the PUR hot melt adhesive itself will increase, resulting in wire drawing.

For PUR reactive hot melt adhesive, bonding should be completed within the open time after application to ensure the best effect after bonding. However, bubbles may appear during bonding. What is the reason?

1. The temperature of the adhesive tank is too high. If the temperature is too high and the heat resistance of the hot melt adhesive is poor, this phenomenon may occur;

2. The hot melt adhesive itself. The hot melt adhesive is not completely melted and mixed during the production process. The air in the rubber will be released during the user's heating process, or the hot melt adhesive is not vacuumed or not completely vacuumed during the production process;

3. If there are bubbles when the glue comes out of the nozzle, you can consider whether the temperature of the hot melt glue machine is too high or whether there is residual glue that has not been completely discharged. You can try to discharge the glue for a few minutes to see if the glue is smooth and free of bubbles;

4. If there are no bubbles when the glue comes out of the nozzle, but there are bubbles after the reaction, one possibility is that there is tension after bonding, the external force is not strong enough, or the pressure is not good. Another possibility is that the pressure is not positioned in time after bonding, so that it bounces off during the initial bonding, resulting in bubbles at the edge or both ends.

Overview of Oushida hot melt adhesive intelligent spraying equipment