Polyurethane laminated adhesive is the core material of flexible packaging composite production. As a key process parameter, temperature directly affects the viscosity, curing reaction, bonding strength and stability of finished products, and is the core element to control the composite quality of packaging.
Low temperature environment has a significant negative impact on the properties of laminated adhesives. When the ambient temperature is lower than 10℃, the molecular activity of
Polyurethane Adhesive decreases greatly, and the curing reaction rate slows down sharply, which easily leads to the problems of incomplete curing and glue drying, resulting in delamination and degumming of packaging film. At the same time, low temperature will increase the viscosity of glue, resulting in uneven coating, poor leveling, appearance defects such as different thickness and pinholes, which often occur in soft packaging production in winter.
High temperature environment will also destroy the performance of adhesive. Too high temperature will accelerate the curing reaction of glue and the side reaction of isocyanate, shorten the shelf life of glue, easily lead to gel and agglomeration, and cause material waste. In addition, high temperature will destroy the molecular chain structure of polyurethane, weaken the adhesive force, and reduce the heat resistance and sealing of finished packaging, which will easily lead to foaming and delamination in subsequent use and cannot meet the storage requirements of food, daily chemical and other packaging.
In actual production, it is necessary to control the coating, curing and storage temperatures in the standard range, accurately match the technological requirements of different film materials, balance the curing efficiency and bonding stability, effectively avoid the quality defects caused by temperature, and ensure the comprehensive quality of flexible packaging products.
