PUR hot melt glue, ie reactive polyurethane hot burn adhesive, whose main component is really a polyurethane prepolymer with -NCO groups. The reaction principle of PUR hot melt adhesive is as follows: after the colloid is heated and melted to be liquid and coated on the surface of the essence, following your two substrates are fused together, the PUR hot burn adhesive can react irreversibly with the moisture in the air . A high molecular polymer having a very high cohesive push is.
PUR hot melt creams include these outstanding advantages:
( 1) Good stability. Ordinary hot burn adhesives in order to an audio state after being heated and melted to a liquid express, as well as the PUR hot burn adhesives will vary, which further causes an irreversible a effect to create a crosslinked compound. Therefore, the soundness of PUR hot melt adhesive is any better than that of ordinary hot melt adhesive.
( 2) The use temperature is low. Compared with ordinary hot melt adhesives, PUR hot melt adhesives can be used at relatively low temperature ranges, thereby effectively avoiding the concern of heat deformation during the process of the transparent clear plastic packaging box.
( 3) Other performance advantages. In relation to the response basic principle of PUR hot melt glue, it could be formed to make a polymer film with good cohesive strength after combination- linking reaction with wetness in air, in order that PUR hot melt adhesive is solvent resistant and aging resistant on the other hand with ordinary hot melt glue. The performance is very good , and the low temperature amount of resistance and high temperature resistance of PUR hot melt adhesive products are superior to ordinary hot melt adhesives. Table 1 analyzes the performance of PUR hot melt adhesives with common hot melt adhesives.
PUR hot burn glue paste box process control points
To be able to give full play to some great benefits of PUR hot melt adhesive in transparent plastic packaging box, you ought to strengthen the process control in the production means of the substance box, especially the following aspects.
1. Processing of materials
The top energy of PET, PP or PVC really should not be below 38mN/ m. If the top energy of the information is low, it ought to be pretreated before surface treatment.
2. Control of the number of glue applied
Found in the process of pasting the box, it is necessary to strictly control the number of glue applied, not too much or too little. Too much is simple to help make the film white, too few will easily lead to poor bonding, and in the end affect the carrying capacity of the transparent plastic packaging container.
3. Pressure on the done product
After the PUR hot melt adhesive is bonded, it must be fully pressurized after the line is removed. Normally, the unreacted PUR hot burn adhesive is simple to make bubbles, causing poor bonding.
4. Guarantee curing conditions
PUR hot melt adhesive paste should be positioned under proper temperature and humidity conditions after the brand is removed to ensure sufficient curing of PUR hot burn adhesive. Generally, the ideal curing temp is 22° C~ 35° C, and the curing humidity is 50%~ 80.%, curing time is 24 to 48 hours .
With the continuous improvement of hot melt adhesive formulations and techniques, we think that the program of PUR hot melt creams in the field of translucent plastic packaging boxes will become more and more popular.
