Volatile Analysis Of Flexible Packaging Polyurethane Laminating Adhesive

The volatility of flexible packaging polyurethane laminating adhesives is a key indicator that affects the quality, production safety, and environmental compliance of packaging products. It is mainly manifested as the release of volatile organic compounds (VOCs) during the production curing process, directly impacting the safety of food packaging and the production environment in the workshop. Currently, the mainstream adhesives in the industry are divided into solvent-based, water-based, and solvent-free categories, with significant differences in volatility. 

 

Traditional solvent-based polyurethane laminating adhesives use organic solvents such as ethyl acetate as the carrier, and they have extremely strong volatility. During the coating and curing processes, the organic solvents will rapidly evaporate. If the ventilation is insufficient, it will easily cause the accumulation of waste gas in the workshop, posing potential safety hazards. At the same time, incomplete evaporation will lead to excessive solvent residues, causing packaging odors, film blistering, and decreased bonding strength, which does not meet the safety standards for food packaging. 

Water-based polyurethane laminating adhesive uses water as the dispersion medium and contains almost no organic solvents. The volatility is significantly reduced, resulting in low VOC emissions, mild odor, and higher safety. However, its volatility is greatly affected by temperature and humidity. High temperatures accelerate the evaporation of water, which may cause the adhesive layer to form a crust. Low temperatures and high humidity will delay the evaporation, thereby affecting the compounding efficiency.

 

The solvent-free polyurethane laminating adhesive has a solid content close to 100%, with no solvent evaporation and no residues. It is a low-volatile green product. With the tightening of environmental protection policies, the industry is vigorously promoting this type of product, strictly controlling the evaporation of free monomers and meeting the production needs of high-end flexible packaging. Controlling the volatility of adhesive and choosing low-volatile products has become an inevitable trend for the green development of the flexible packaging industry.