The four most important matters to pay attention to when using flexible packaging polyurethane laminating adhesive

Flexible packaging polyurethane laminating adhesive is the core material for the production of composite packaging in industries such as food and daily chemicals. The stability of adhesion directly determines the quality of the packaging products. During practical operations, by controlling the four key aspects well, common problems such as delamination, stickiness, and odors can be effectively avoided, ensuring the qualified rate of production. 

 

1. Surface treatment of the substrate. Before bonding, it is necessary to thoroughly remove dust, oil stains, release agents, and other impurities from the surface of the substrate (such as films and aluminum foil), and eliminate any residual moisture. Contaminants can damage the bonding interface, hinder the penetration and bonding of the adhesive, and easily cause poor adhesion and local delamination. In such cases, a special solvent can be used for wiping, and the construction can be carried out after the substrate is completely dry. 

2. Control of solvents and ratios. The ethyl acetate solvent used for dilution should be of high purity, with the content of water and alcohols meeting the requirements. This is to prevent the consumption of the curing agent from causing incomplete curing of the adhesive layer. At the same time, the main agent and curing agent should be mixed in accordance with the standard ratio. It is strictly prohibited to arbitrarily increase or decrease the ratio. Different types of adhesive cannot be mixed, to avoid problems such as adhesive liquid failure and residual odors. 

 

3. Construction temperature and humidity control. Polyurethane laminating adhesive is highly sensitive to environmental conditions. High temperature and high humidity will accelerate the consumption of the curing agent, resulting in incomplete drying or sticky glue layers. Low temperature will slow down the cross-linking reaction, leading to insufficient bonding strength and excessive solvent residues. During production, it is necessary to maintain appropriate temperature and humidity. The process parameters should be adjusted according to the weather conditions to meet the requirements of composite production. 

 

4. Gel solution aging management. The gel solution prepared has an expiration period and must be used within the specified time. Excessive standing of the gel solution can lead to cross-linking failure and abnormal viscosity. At the same time, ensure the sealed and moisture-proof storage of the gel solution to prevent the introduction of water vapor and impurities, thereby ensuring the quality stability of the composite products from the source.