The same thing holds true for label liners. Label liners (aka backings, carriers or release liners) tend to be overlooked and yet without them there would be no way to present die cut labels. Just like a red carpet, liners hold labels to transport them through converting and on to printers and automatic application equipment. Liners are critical to the die cutting of labels in all shapes, sizes and formats like multi-part labels. Without liners you would be left to use only a limited selection of linerless materials such as tags, receipt papers and a very few self-wound materials that have a unique adhesive much like scotch tape that doesn’t gum up the face of the labels. Linerless labels or tags can only be made with perforations between labels or be butt cut when they come out of a printer to present square cornered labels.
Most importantly, liners serve to protect the label adhesive until it is applied to the end use surface. Since there are all sorts of adhesives, it is important to use the right type of liner engineered to the adhesive and to make sure the labels properly release.
Liner construction is simple; it consists of a basic carrier most commonly made of paper or polyester (PET) to which a layer of silicone is added. The specific amount of silicone determines how well the labels will peel off the carrier and the specific release values and coat weights are based on die cutting and dispensing requirements. Liners are further broken down into roll form and sheet form products.
In choosing a liner, one looks at its thickness, smoothness, strength, its lay flat characteristics, and how well it die cuts and dispenses. Some liners are even made to allow for what we call “back printing” on the reverse side of the liner.
|Types of Liners|
|Thickness (Avg.)||2.5 – 4.6 mil||2.2 – 3.1 mil||3 – 8 mil||4.6 – 12 mil||1 – 4 mil|
|Smoothness||Good||Very Good||Very Good||Very Good||Superior|
|Strength||Good||Very Good||Very Good||Very Good||Superior|
|Die Cutting||Good||Very Good||Very Good||Good||Superior|
|Dispensing||Good||Very Good||Very Good||N/A||Superior|