Handling and Storage
This section covers the handling and storage of adhesive containers before use and the storage of partial containers for later user. Again, the TDS, SDS, and warning label describe proper storage conditions. Regardless of the product, keeping the containers in a cool, dry, well-ventilated area is generally best. Normally, temperatures above 50°F and below 120°F are acceptable for storage. Ensure all lids are secured tightly on containers to prevent evaporation and keep moisture out. When only using a partial container, it is critical to cap headspace with inert gas or dry air for any urethane products, which are moisture sensitive. This will prevent water contamination, which negatively affects the quality of the product. Read the manufacturing and expiration dates marked on container labels. Do not use expired products, and always practice a first-in-first-out consumption schedule to ensure the oldest material is used before newer lots.
Mixing the Adhesive
As you handle and mix the laminating adhesive or coating before application and lamination, several steps and precautions should be taken to ensure quality. Always refer to the TDS for the proper mix ratio, application solids, diluting solvent, and other information. It is recommended to calculate the amount of adhesive needed for the job at hand and only mix that amount plus waste or mix an amount that can be used in a normal 8-hour shift. It is often advisable to premix water-based laminating adhesives, such as ROBOND™ and AQUA-LAM™, and water-based ADCOTE™ coatings for 5–15 minutes before pulling out material for use. However, this is not necessary for Dow's solvent-based ADCOTE™, MOR-AD™, and LAMAL™ products. Always use a urethane-grade diluting solvent when working with solvent-based products, and make sure the solution remains moisture free by using an inert gas blanket or desiccant tubes. Adhesives may be weighed using a calibrated floor or benchtop balance at the proper ratio.
Mixing should be done in a round container using a mixing blade that is one-third of the container’s diameter. A mild, off-center vortex should be created for proper mixing that avoids trapping air. Any coreactant and diluting solvent required to use with the adhesive should be added while mixing. Once the appropriate viscosity or solids level has been achieved, the mixed and diluted material can be pumped into the application pan using a low-shear pump, like a diaphragm, peristaltic, centrifugal, or positive displacement pump. Recirculation is advised for longer runs to help minimize foaming. Keeping the return distance short and below the fluid level is also prudent. The return should be placed as far away from the intake as possible. While filtering is not usually needed, it can be used to collect any debris or foam that has been generated. A filter method can be as simple as using cheesecloth. Both solids and viscosity should be monitored throughout the run and adjusted as needed to guarantee consistent coating weight and appearance.
Dow's laminating adhesives and coatings can be used safely and applied accurately by reading, understanding, and following the supplied documentation and guidelines outlined in this article. Proper handling not only ensures worker safety but will also ensure high-quality, high-performing adhesive laminations and coated products. Proper handling and storage help products perform throughout their manufactured shelf life and enable the reuse of partial containers. Questions can be answered by referring to the manufacturers' technical or regulatory department for clarification. Click below if you have any questions about Dow's laminating adhesives and coatings and how to apply, store, or handle them.