If you want to know whether it is better to choose cold or hot adhesive during the construction of hot melt adhesive, you first need to understand the difference between the two bonding methods. Hot melt adhesive is a type of thermoplastic adhesive that has different bonding effects depending on the bonding method. What is the difference between cold and hot adhesion of hot melt adhesives? Let's talk about the difference between the two!
1. Cold adhesion
Cold adhesion is mostly used in the application of many pressure-sensitive hot melt adhesives. Among them, the more common ones are the sealing places of express delivery and envelope bags, which are bonded by hot melt pressure-sensitive adhesive cold adhesive. Apply a layer of hot melt adhesive with initial tack to the object and then cover it with a release film or release liner. When using, the release paper can be uncovered and bonded, which perfectly solves the need for instant bonding. Moreover, there will be no glue overflow in cold bonding, and there will not be too much damage to the surface of the substrate. As long as the adhesive layer is in contact with the substrate and gently pressed the adhesive part, a good adhesive effect can be achieved.
2. Hot sticking
Thermal bonding, which is common in applications such as bottle caps, automotive interiors, and wick fixing. Similar substrates have certain requirements for the adhesion of hot melt adhesives, and the ideal bonding effect cannot be achieved with pressure-sensitive adhesives, so hot adhesives should be used to strengthen the integration of colloids and substrates. Especially for substrates with textured and fine seams on the surface, the gap between the adhesive layer and the substrate will come into contact with moisture and dust in the air, which greatly reduces the adhesion of the hot melt adhesive to the substrate, and the adhesive layer will detach after a long time. Therefore, the use of hot adhesive construction can well fill the fine seams on the surface of the substrate, so that the glue and the substrate have a more perfect contact, and thus improve the bonding effect.
3. The difference between cold sticky and hot sticky
The biggest difference between hot and cold adhesive is the difference in the activity of the glue molecules. In the cold-adhesive state, the hot-melt pressure-sensitive adhesive is used, and the glue has cooled, and the molecular structure has become relatively stable, which is more convenient to use; However, when using hot melt adhesive in the state of hot bonding, the molecular structure becomes more active due to income, and has the ability to impact the molecular structure of the surface of the substrate, and even fuses with the molecular structure of the substrate, which shows that the hot adhesive is more likely to damage the surface of the substrate.
Very few substrates can be bonded both cold and hot, and once you understand the sensitivity of the substrate to hot melt adhesives, you will know which bonding method to choose.
