Spring is almost here, before you know it, picnics and summer will be at our doorstep. What better than a cool refreshing drink during the warmer weather.
Have you ever wondered about the labels on these beverages? The labels on your beer or soda bottles undergo extreme conditions.
These labels have to endure dramatic changes in temperature (from a refrigerator or freezer to hot daytime temperatures), changes in humidity, immersion in ice water and condensation etc. are some of the challenges these labels have to endure during the summer. Think of a beer bottle plunged into ice water for a refreshing drink. Once out of the ice and exposed to the sun, the label, must continue to look good, and remain firmly attached to the container.
To summarize, adhesives must meet several requirements:
- Resistance to water (and iced water)
- Resistance to heat
- Resistance to temperature changes
- Withstand condensation
On the other hand, the labels should also be relatively easy to remove when cleaning the bottle for recycling.
So far, the adhesives that gave the best results to these conditions were made from casein, a milk protein. Casein glues are known for their strength, their longevity and their high resistance to water, as well as a drying time adapted to the application of labels and the possible need for repositioning.
One of the disadvantages of casein is that its price fluctuates depending on the price of milk. This can cause an unaccounted variance when applied to large scale labels, especially since the prices have increased slowly and predicatably for some time now.
Casein free adhesives have since made their debut, replacing the milk protein with polymers. These adhesives offer cheaper alternatives with less price fluctuations and are more sustainable, without any losses in performance and quality.
If they are only, for the moment, innovations; these products will soon become valuable main stream technology in the labelling world. To be continued!