The release liner is the base layer of all Polyonics single and double coated tapes and label materials. Its primary function is to protect the acrylic and silicone pressure sensitive adhesive (PSA) until the tape or label is ready to be applied. The liner also helps in material handling, determines the ease of which the liner is removed from the PSA and is a critical element of the die cut process.
The liner is comprised of a carrier―paper, polyester (PET) or fluorinated PET―and an ultra thin layer of silicone. The percentage of silicone determines the release value with the higher percentage of silicone producing a lower release value and an easier release of the liner from the PSA. Release values are typically in the 20 to 50 pound range with the combination of carrier (material, thickness, etc.) and release value chosen based on the requirements of the die cut process.
The release value is also carefully chosen for automated applications where the label or tape must easily strip onto the applicator head to then be automatically applied to a part’s surface. Double coated tapes in auto apply applications will typically have different release values for each of its two liners. The liner removed prior to the application of the die cut part will have a lower release value than liner removed after part application.
Silicone PSAs require fluorinated PET release liners and certain tapes and label materials, such as those destined for automatic applications, may require harder glassine or PET liners, to facilitate the die-cutting process.
50# SCK liner: Super Calendared Kraft, 3.2 mils +/-0 .3 mils. Due to its high internal strength it will withstand all conventional die cut operations. It is used for all of our acrylic based tape products and on the two mil label materials.
55# Glassine liner: 3.1 mils +/- 0.2 mils. These liners are denser than 50# SCK liners and provide a harder and thinner base for die-cutting.
PET: 1.5mil +/- 10%. A clear silicone coated PET film with extremely high internal strength, low heat shrinkage, excellent stiffness, high clarity and surface smoothness. It is sometimes used in auto-apply applications when 50# SCK and 55# glassine don’t perform well or in situations when the automatic applicator needs a clear liner for label sensing.
20# Fluorinated PET liner: 2mil. Used for all silicone PSA applications.
Lay flat liners: Available as a custom construction to aid the die cut and auto apply processes.
Custom liners: Customers are allowed to supply their own liner for custom constructions.