What is a label adhesive?
Pressure sensitive labels, or PS Labels, use an adhesive to make the label stick to a surface. PS label adhesives require no solvents or heat to be activated. There are three main types of adhesives that are used by label converters: permanent, removable, and repositionable. Each adhesive type has their own unique properties.
When labels fall off prematurely, it can cost a company a lot of time and money to correct. Inventory without a prime label cannot be sold in stores and the expectation is that “the label should just stick”. By working with a custom label converter, like Hub Labels, you can avoid costly mistakes. When application issues do arise, Hub Labels will work with you, the label applicator equipment manufacturer, and the label manufacturer we purchase from to find a solution to minimize down-time.
Permanent Label Adhesives
Permanent label adhesives are the most budget friendly solution. Permanent adhesives work for most label applications and create a strong bond wherever they are applied. Permanent adhesives will likely damage a surface if removed.
Repositionable Label Adhesives
Repositionable label adhesives can be removed after application for a short-term and then reapplied. These labels are ideal when hand applying labels because any crooked label can quickly and easily be adjusted.
Removable Label Adhesives
Labels with removable adhesive can be removed for a certain amount of time after they have been applied without damaging the label or the application surface. However, temperature can affect the integrity of this functionality.
In addition to these broad types of pressure sensitive adhesives, label adhesives also have varying qualities within these categories that separates them even further from one another.
Common Adhesion Terminology
Initial Tack refers to the initial stickiness or grip that a label adhesive will have upon making contact with a surface. Low initial tack means there will be low adhesion allowing for an easier removal whereas high initial tack brings a higher level of adhesion. Low initial tack will build up adhesion over time when not removed.
The Mandrel Hold will ensure a label adhesive can stick to a curved or non-flat surface. Label adhesives with good mandrel holds will not flag, which means the edges won’t fold up.
Label adhesives with a low shear have a high initial tack but they are soft and can split apart easier. A label adhesive with high shear is stronger and less likely to tear apart easy but will have a low initial tack.
A solvent resistant label ensures a label will not lose adhesion when exposed to a variety of solvents such as water, alcohol, plasticizers, petrochemical solutions, etc..
Ultimate adhesion measures the maximum amount of adhesion expected after being applied to a surface. Ultimate adhesion usually takes anywhere between 2 and 24 hours and it all depends on factors such as the stiffness of the adhesive, the condition or feel of the surface it is being applied to, or environmental conditions.
Labels exposed to Ultra Violet or UV light for long periods of time are at risk for color change or adhesion decay. Labels that are exposed to UV light, whether through use or during the printing process, should have some level of UV resistance.
Cold flow is a label adhesive’s ability to stay bonded to a surface in below-normal temperatures.
Minimum Application Temperature
When an adhesive does not have cold flow and isn’t designed for cold temperatures, the adhesive will weaken as the temperature drops. The minimum application temperature for these types of adhesives is around 40 to 50 degrees Fahrenheit.
Service Temperature Range
The service temperature is the temperature range a label adhesive will still function in once it was has reached ultimate adhesion.