Key points for controlling the coating amount of flexible packaging polyurethane laminating adhesive

The coating amount is the core parameter in the laminating adhesive compounding process of flexible packaging. It directly determines the bonding strength, appearance quality and durability of the packaged products, and is a key link in improving the quality and reducing the consumption of flexible packaging production. In the industry, the dry basis coating amount is used as the unified measurement standard. The setting of the coating amount is not a fixed value. It needs to be precisely adjusted according to the type of substrate, packaging purpose and post-processing technology to meet the requirements of different production scenarios. 

 

Conventional flexible packaging has clear classification standards for coating amounts. Ordinary transparent lightweight packaging does not have special process requirements and can meet basic bonding needs with a relatively low coating amount. For multi-color printing films, aluminum-coated films, etc., in composite scenarios, due to the poor surface flatness of the substrate, the coating amount needs to be appropriately increased to avoid delamination and false adhesion problems. For special packaging such as boiling and high-temperature steaming, as well as packaging for corrosive contents, a higher coating amount is required to fully ensure the performance of the composite structure in withstanding high temperatures and chemical erosion. 

The precise control of the coating amount is of vital importance for product quality. Insufficient coating will result in incomplete coverage of the adhesive layer, problems such as composite bubbles, low peel strength, and failure of heat sealing, and the finished product is prone to delamination and damage. On the other hand, excessive coating will not only cause waste of adhesive, increase production costs, but also lead to accumulation of the adhesive layer, uneven winding, and easy occurrence of warping and stickiness after curing, which will affect the appearance and usage experience of the packaging. 

 

In actual production, it is necessary to precisely control the coating amount through the selection of network roller types and the adjustment of equipment speed. At the same time, it is necessary to dynamically adjust according to the characteristics of the substrate and the purpose of the finished product. Under the premise of ensuring the quality of the composite, energy conservation and consumption reduction can be achieved, and the overall qualification rate and stability of flexible packaging products can be improved.