The Influence Of Temperature On Flexible Packaging Polyurethane Laminting Adhesives

Polyurethane laminating adhesives are the core material in the production of flexible packaging lamination. Temperature, as a crucial environmental and process parameter, directly affects the curing reaction of the adhesives, the coating effect, and the quality of the laminated products. It is an important factor in controlling the yield rate of flexible packaging production. 

 

Excessive low temperature will significantly inhibit the molecular movement of the adhesive, slow down the cross-linking reaction between isocyanate and hydroxyl groups, and cause a substantial decrease in the curing rate. In a low-temperature environment, the adhesive does not cure completely, the initial adhesion force is weak, the curing period is significantly prolonged, and it is very likely to cause the delamination and debonding of the flexible packaging lamination film. At the same time, the residual active groups will also cause the failure of subsequent bonding and seriously affect the stability of the product. 

Excessive temperature can also have negative effects. High temperature can cause the adhesive to cure too quickly, resulting in uneven coating, blistering of the adhesive layer, and formation of a crust. This disrupts the uniformity of the adhesive layer. At the same time, rapid curing causes the adhesive layer to generate internal stress. Coupled with the difference in thermal expansion and contraction coefficients between the film and the adhesive layer, the finished product becomes brittle, the peel strength decreases, and the release agent in the film is more likely to be released, further reducing the quality of the lamination. 

 

In industrial production, the flexible packaging polyurethane laminating adhesive needs to be compatible with a reasonable temperature range. The conventional curing temperature is generally 40–50℃. Precise control of the temperature parameters can ensure that the adhesive fully cross-links, stabilize the bonding strength, avoid defects such as delamination and brittleness, and is a key process point for ensuring the quality of flexible packaging products.