What processes can soft-packaging polyurethane adhesives be used for?

Flexible packaging polyurethane adhesives are widely used in various soft packaging laminating processes due to their excellent bonding strength, weather resistance, flexibility and chemical resistance. The main application processes include: 

 

Dry laminating method (dry bonding): This is the core and traditional application process. The principle of the process is as follows: The Polyurethane Adhesive (main agent and curing agent) is diluted with an organic solvent (such as ethyl acetate), and then evenly coated on the first layer of substrate (such as BOPP, PET, VMPET, etc. films). After passing through the drying oven, the solvent completely evaporates, forming a dry adhesive film. Subsequently, under the condition of heating and pressure, it is immediately bonded with the second layer of substrate (such as CPP, PE, aluminum foil, etc.). This process is applicable to most high-performance and high-temperature resistant packaging structures (such as 121℃, 135℃) for products like food, medicine, and daily chemicals. 

 

Solvent-free recombination method: This is the current mainstream development direction and is in line with the environmental protection trend. This process uses 100% solid content solvent-free polyurethane adhesive, without the need to use or volatilize organic solvents. Through a precise metering mixing device, the two-component adhesive is applied to the substrate and directly bonded to another substrate, relying on its own reaction for curing. Its advantages include no VOC emissions, low energy consumption, fast speed, high safety, and it is widely used in the packaging of ordinary to medium-light load food and daily necessities, and is an important alternative to the dry composite process. 

 

Wet laminating method (wet composite): This process is mainly applied to porous substrates such as paper, cardboard, and non-woven fabrics. The key features of this method are: First, the adhesive is applied to the porous substrate. While the adhesive is still wet, it is immediately combined with the second substrate (such as aluminum foil, plastic film). Then, through the drying tunnel, the moisture (or solvent) in the adhesive evaporates and solidifies. Polyurethane adhesives can be used in this process to produce specific packaging materials such as paper-aluminum laminates.