Curing agent is the core component of two-component polyurethane laminating adhesive. When used together with the main agent, it determines the adhesive strength, molding effect and weatherability, and is an indispensable key raw material for flexible packaging compounding.
First, it plays the role of cross-linking and film forming. Curing agent molecules can react chemically with polyurethane main agent, and linear molecules cross-link with each other to form a dense three-dimensional network structure, so that the liquid adhesive layer can be quickly solidified and shaped, and the viscous liquid can be transformed into a tough adhesive film, which can firmly adhere to substrates such as films and aluminum foils to prevent delamination and bulging of the composite layer.
Secondly, the bonding performance is greatly improved. After the crosslinking reaction, the cohesion of the adhesive film is significantly enhanced, which effectively improves the peeling strength and tear resistance of the composite film, and is suitable for various flexible packaging composite scenes such as food film, aluminum-plated film and retort pouch, so as to ensure that it is not easy to crack and separate in daily use and processing.
At the same time, optimize the comprehensive weather resistance quality. The cured film has excellent heat resistance, low temperature resistance, grease resistance and hydrolysis resistance, which can resist high-temperature cooking, low-temperature refrigeration, ink erosion and other working conditions, delay the aging and yellowing of the adhesive layer and prolong the service life of the packaging.
In addition, it can adjust the flexibility and coating adaptability of the adhesive layer, balance the hardness and elasticity, avoid brittle cracking or soft deformation of the adhesive film, ensure uniform coating and smooth bonding on the high-speed laminating machine, and stabilize the composite appearance and overall quality of the finished product.
