Is the higher the temperature of the hot melt adhesive particles, the better the viscosity? This misconception has deceived many glue installation masters

First, correct the conclusion: Hot melt adhesive particles do not have better viscosity at higher temperatures. Heating for a long time above the recommended temperature of 10 ℃ will cause the colloid to oxidize and degrade, resulting in a decrease in adhesive strength instead of an increase. It can also cause a series of problems such as black slag, wire drawing, and burnt smell. The key to viscosity lies in “appropriate temperature+sufficient compression”, rather than simply raising the temperature.

Why doesn’t high temperature stick firmly

The bonding of hot melt adhesive relies on the wetting of the adhesive surface by the liquid and the cooling to form a film. When the temperature is too high, the glue solution becomes too thin, and after reaching the back of the book or the surface of the box, a large amount of paper fibers infiltrate, leaving insufficient glue on the surface and causing the glue layer to become thin and brittle; At the same time, high temperature accelerates oxidation, causing molecular chain breakage and a decrease in cohesion. In the technical follow-up of Guangzhou Sunlife Trading, more than one customer attributed the “weak adhesion” to poor glue, and it was eventually discovered that the glue pot had been operating at excessive temperatures for a long time.

Be alert to these high temperature signals

• The color of the glue in the pot changes from light to dark, and turns yellow and black;
• The edge of the glue pot is burnt, and black particles appear in the glue solution;
• There is a clear burnt smell in the workshop, and the glue line is smoking;
• The initial adhesion of the finished product is normal, but after a few days of storage, the adhesive layer is brittle and cracked.

Correct approach

According to the recommended temperature setting indicated by the adhesive particles, when it is necessary to improve the bonding effect, three things should be checked first: whether the adhesive material has a film or dust, whether the pressing time is sufficient, and whether the adhesive amount is uniform. Each model of Sunlife hot melt adhesive is labeled with recommended construction temperature and opening time, and following the parameters is much more reliable than blindly heating up.

Frequently Asked Questions

Q: The workshop is cold in winter, can it be remedied by heating up?
It is possible to slightly increase the temperature by 5-10 ℃, but it is more recommended to use low-temperature rubber particles for material reheating or to use low-temperature rubber particles. Hard pot temperature treatment does not cure the root cause.

Q: Can the adhesive still be used after it has turned black?
Not recommended. Blackening indicates oxidation and degradation. The pot should be emptied and replaced with new adhesive, otherwise the bonding quality will not be guaranteed.

Remember this: temperature is a process parameter, not a glue switch. Using glue according to the recommended range is the worry free way.