The flexible packaging polyurethane laminating adhesive forms a dense cross-linked structure through chemical reactions, thereby achieving bonding and sealing effects. However, if the curing process is incomplete after construction, it will cause a series of quality problems, significantly reducing the product quality and service life, and bringing numerous hidden dangers.
The most direct consequence of incomplete curing is a significant reduction in bonding strength. The adhesive layer fails to form a complete polymer cross-linked network, with a large amount of unreacted components inside. The adhesive layer becomes soft and lacks sufficient toughness, unable to achieve the designed load-bearing and anti-peeling performance. During product use, even slight forces, vibrations, or temperature changes can easily cause problems such as delamination, cracking, and detachment, directly leading to the failure of the bonding and resulting in the product being scrapped.
Secondly, it will seriously affect the appearance and sealing performance of the product. The partially un-solidified adhesive layer will remain sticky and dusty for a long time, resulting in a rough and uneven surface, which damages the appearance texture of the finished product. At the same time, insufficient curing reaction will leave micro-bubbles and pores, causing the adhesive layer to lose its tightness, significantly reducing its waterproof, dust-proof and air-tight performance, and failing to meet the sealing requirements.
Furthermore, incomplete curing will significantly reduce the weather resistance and stability of the adhesive layer. The remaining reactive groups are prone to absorbing moisture and oxygen in the air, continuously undergoing side reactions, causing the adhesive layer to undergo hydrolysis, aging, and yellowing. Over a long period of use, problems such as hardening, cracking, softening, and detachment will occur due to aging. Some unreacted components may also slowly release harmful substances, not only polluting the environment but also laying down long-term hidden dangers such as equipment failure and safety failure.
