About Release Liners
The release liner is the base layer for all pressure sensitive label materials. The release liner's primary purpose is to protect the adhesive, until the label is ready to be used. But, the liner must also be easily removed when you are ready to use the label. This means that the properties of label adhesion to the liner, AND its ease of removal must be balanced.
The liner is comprised of a silicone release layer on top of a paper or film. The percentage of silicone laid onto the surface of the liner determines the release value (the higher the % of silicone the easier it releases). Moreover, the liner material used and the release value of the coated side will affect the way in which the labels will die-cut, during their manufacture.
The release value must also be correct when the label is going to be used in applications that require automated label application, i.e. the labels must "strip" onto the applicator head easily, for automatic application. The main release liner material used is paper based, with the most common weight of 40-50 lbs. per ream basis weight.
Certain specialty label materials, such as 1 mil polyimide labels, or labels for automatic label applications, may require the use of a glassine paper (a more dense, harder form of release paper), or even polyester film release liner, to facilitate the die-cutting operations of the labels during their manufacture.
- Carries the label stock (substrate) through the converting process
- Protects the adhesive
- Provides a die-cutting base
50# SCK liner (Super calendared kraft) is 3.2 mils +/- .3 mils- One side has been silicone treated to the specified release level. Due to its high internal strength it will withstand all conventional processing operations. It is used for all of our two mil label materials.
55# Glassine liner is 3.1 mils +/- .2 mils. It is more dense than 50#SCK, providing a harder and thinner base for die-cutting. Glassine is always used for 1 mil (25 micron) products because it is a very dense liner and provides a firm base for die-cutting low profile labels. Our two mil materials are available with this liner under special terms and conditions.
1.5 mil Polyester +/- 10%- A clear silicone coated polyester film with extremely high internal strength, low heat shrinkage, excellent stiffness, high clarity and extreme surface smoothness. It is used in many cases when 50# SCK and 55# glassine do not perform in auto-apply applications, or in situations when the automatic applicator needs a clear liner for label sensing.
Customers are allowed to supply their own liner to Polyonics for specific applications by special order.