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Reactive PUR polyurethane hot melt adhesive types and differences
Reactive polyurethane hot melt adhesives are available in two types:

1. Moisture-curing polyurethane hot melt adhesive (PUR hot melt adhesive);

2. Closed polyurethane hot melt adhesive (heating reactive polyurethane hot melt adhesive).

The difference between the two types is: 1. The mechanism of action is different; 2. The curing time is different


1. Moisture-curing polyurethane hot melt adhesive - moisture curing

The adhesive is heated and melted into a fluid, applied to the surface of the substrate to be bonded, and the two adherends are bonded together to form a bond after cooling, and then the moisture in the air or a trace amount of moisture in the adhered substrate and other contents are utilized. The active hydrogen compound reacts with an NCO group to form a crosslinked network to form a polymer having a high cohesive force, which further enhances the adhesion.


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2. closed polyurethane hot melt adhesive - heat curing

The end-NCO group in the polyurethane prepolymer is sealed with a blocking agent under certain conditions to become a closed prepolymer. In fact, the free -NCO group is protected from its reactivity at normal temperature, which increases the storage stability of the gel. Dissociation occurs when heated to a certain temperature, and active-NCO group regeneration can be cross-linked by chemical reaction with active hydrogen-containing compounds such as polyols, amines, water, and the like.

Commonly used sealers:


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1. Moisture reaction The hot melt adhesive is solidified by the reaction of moisture in the air, and can also be said to be water molecules. Carbon dioxide is produced in it. It becomes a solid by the occurrence of a chemical reaction, but in the case of a chemical reaction, there is a process of reaction time. The moisture reaction generally requires a reaction time of 2-4 hours, which is related to factors such as the contact area in the air.

2, heat curing Generally, as long as the temperature meets the requirements, it can be cured in about 30 minutes. The specific curing time depends on the size of the substrate and the specific position of the bonding site.

Weiwang PUR hot melt adhesive storage conditions: PUR hot melt adhesive storage temperature 8 ~ 22 ° C, stored in a dark place to avoid excessive humidity. Do not use damaged products.

   2019-8-8
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