In the dry lamination production process, slow curing, prolonged non-drying of the finished products, and continuous surface stickiness are very common technical problems. During the normal curing period, the adhesive cannot be shaped, and the feel is sticky. The peel test shows that there are cracks, softness, and low strength, which not only delay the cutting, bag-making, and delivery deadlines, but also easily cause batch delamination and poor bubble formation. These are the most common cross-linking abnormal faults encountered in the workshop.
The primary reason for non-drying and stickiness is the deviation in the ratio. If the proportion of the curing agent in the two-component
Polyurethane Adhesive is insufficient, it will directly lead to incomplete cross-linking reaction, and the resin cannot form a dense network structure. The adhesive layer will be permanently soft and continue to stick. Human weighing errors, confusion in the mixing ratio, and flow deviation of the automatic mixing machine are the main causes of imbalance in on-site mixing.
Environmental and solvent issues can significantly slow down the curing speed. High humidity in the workshop and excessive water content in the solvents consume the active groups of the curing agent first, resulting in insufficient effective cross-linking components and semi-dryness. In winter, the temperature in the workshop and curing room is low, and the molecular reaction activity drops significantly, resulting in a significant extension of the curing period. In addition, excessive coating thickness and excessive solvent residue will also prevent the adhesive layer from completely drying and setting for a long time.
Quick rectification requires the implementation of standardized curing speed-up processes. Strictly calibrate the mixing ratio, regularly calibrate the accuracy of the mixing equipment, and eliminate the shortage of curing agents. Select high-purity anhydrous ethyl acetate and strictly control the humidity in the workshop to reduce the loss of curing agent due to hydrolysis. In cold seasons, appropriately increase the curing temperature and extend the curing time, match a reasonable coating dry amount, and avoid thick adhesives with excessive moisture. Through precise parameter control, the problems of slow curing and surface stickiness can be completely solved, stabilizing production efficiency and quality.
