Films and Adhesives
The appropriate choice of film and adhesive is dependent on several things.
Container material. The surface energy of metal, cardboard, plastic and glass are all different, so an adhesive that adheres well to one may not adhere as well to another. Furthermore, if the container will be reused, an adhesive that can later be removed when the end user wishes to refurbish or reuse the container may be desirable.
Filling. Label adhesion can be impacted by the point at which filling occurs. If it will occur before labeling, there is a likelihood that labels will be exposed to the container contents. Polyesters (PET) tend to perform the best when exposed to caustic chemicals, but if cost is a factor, polypropylene (PP) may be a suitable alternative. If the container is a plastic and the chemical going into it will be hot upon filling, however, the container may shrink on cooling, causing distortion or edge lift of a PET or PP label. In this case, vinyl may be preferred because it can expand and contract with the container.
Exposures. There are numerous adhesives in the labeling industry that are suitable for chemical container labeling. Choosing the right one is dependent on multiple factors, such as the various conditions to which the label could be exposed. These include the container contents, of course, but also weather, temperature extremes, UV rays, and salt water, if the container will be transported overseas. For example, if labels will be applied at cold temperatures or be exposed to them, a softer adhesive is required for labels to adhere properly and remain adhered. For high temperatures, on the other hand, a firmer adhesive that still has some give is needed to avoid piping and wrinkling.
GHS went into full effect in 2016, but non-compliant labels continue to exist. While there are no specific penalties as of yet for not being in compliance, the legal ramifications of a serious injury due to non- compliance could be significant. Furthermore, in the U.S., OSHA’s Hazard Communication Standard is aligned with GHS and BS 5609, opening companies up to possible liability if containers are not properly labeled.
The real takeaway here is that there are numerous things to consider in choosing materials for chemical container labeling - and a lot of options. Suppliers who are well-versed in the application requirements can assist you in choosing label materials that will perform as expected, protect workers and the public, and limit liability.