Labeling plastic bottles can be a challenging task due to the diversity in plastic materials, casting techniques and surface textures. Unlike glass, aluminum and steel containers, plastics present unique challenges in the labeling process. Here’s what to consider when you’re labeling plastic containers.
Understanding surface energy is important when labeling plastic bottles. Similar to how water beads on a waxed surface, adhesives behave differently based on the surface energy of plastics. Low-surface energy plastics, such as polyethylene, present challenges in adhesive sticking and forming a strong bond. Choosing the right adhesive or using techniques like heat treatment can enhance wetting on these surfaces.
Next, the choice between matte and shiny surfaces is important. Rough surfaces offer more adhesion points, but on high-energy plastics, this may reduce effective surface area. Pressure can enhance wetting and adhesion, ensuring a strong bond.
Plastic containers often lead to off-gassing after casting, which can compromise adhesive bonds. Off-gassing is the release of gases or vapors from a material into the surrounding environment. This phenomenon commonly occurs with certain types of materials, especially those that are synthetic or have undergone chemical processes.
During the manufacturing process of plastic containers, small voids or spaces may be present within the material. These voids can trap gases or chemicals used in the production process. Over time, these trapped substances may slowly diffuse or escape from the plastic, leading to off-gassing.
When it comes to labeling plastic bottles, off-gassing can have implications for the adhesive used on labels. If off-gassing occurs, it may lead to the formation of bubbles underneath the label or affect the adhesive bond, potentially causing the label to detach from the bottle.
To address off-gassing concerns in labeling, you may choose permeable label materials and adhesives that allow gases to pass through. This helps maintain the integrity of the label and ensures a strong and durable bond between the label and the plastic bottle.
Addressing contamination picked up on the factory floor is essential. Adding an air knife before the labeling station can remove moisture and contaminants, ensuring a clean surface for label application.
Static electricity can disrupt label application, causing issues like flagging and bubbling. In dry environments, using eliminators and ionizers can neutralize charges, ensuring a smooth labeling process.
For flexible plastic containers like PET bottles, label materials must bend with the container to maintain integrity. Choosing labels with the right flexibility and low-temperature adhesives ensures successful application in varying conditions.
Plastic bottle surfaces may have slight angles that can lead to label skewing. Tailoring label shapes to accommodate these angles and opting for front and back labels on steeply angled surfaces can minimize application challenges.
Get the right labeling system for your plastic containers
Ultimately, your bottle material, shape, label material and label shape all influence the labeling process. By addressing issues related to surface energy, texture, off-gassing and contamination, businesses can achieve successful and durable label applications. Larger manufacturers benefit from Quadrel’s automated label applicators, which will ensure accuracy and efficiency in high-volume production. Reach out to our team today to find the right system for your line.