Popularization of Science: Types of Release Liner for Self-adhesive Labels
Self-adhesive labels can be divided into three layers: facestock, adhesive, and release liner simply. But if you want to subdivide them, there are more than three layers. Many salespersons that have been working for several years even only know the Grassin liner. In fact, there are many kinds of release liners.
The release liner of self-adhesive material is also called liner material and release paper. There is a layer of silicone oil on the liner, commonly known as silicon coated layer and release layer. Its function is to prevent the adhesive from sticking to the release liner.
Release liner can be classified into paper and film according to material. According to the transmittance, it can be divided into transparent liner, translucent liner and opaque liner. According to the process, it can also be divided into super calendering release liner, machine-processed matt release liner and so on. Normally, we have heard of the white-backed semigloss paper adhesive, brass-backed semigloss adhesive and so on, which is based on the color of the release liner to distinguish. Among them, well-known Grassin release liner (also known as glass release liner) is a kind of super matt translucent release liner.
Here is a brief list of several kinds of release liner, as follows:
1. Super calendering release liner. Generally 60-80 grams per square metre, processed by super calendering. It can be divided into SCK liner and Grassin liner according to different pulp formulations with yellow, blue, white and translucent of the release liner.
2. Machine-processing calendering release liner. Generally 80-110 grams per square metre, the release liner is machine calendered, white and opaque.
3. Plastic film release liner. Thickness is generally 38-60 microns, usually BOPP or PET with good dimensional stability and high strength; it’s transparent release liner.
4. Surface coated release liner. A kind of kraft liner which is first coated with plastic and then coated with silicon; the quantity is usually 80-150 grams per square metre; the release liner is usually yellow or white; and it is opaque.
So what kind of release liner should be used under what circumstances? There is usually no limit to the type of release liner for manual labeling method. But if the automatic labeling machine is used to label, the release liner should be transparent liner and Grassin liner. In addition, printing adhesive products such as those using digital printer and offset printing are products that in the form of flat sheet which mainly using thick release liner. The products which use die-cutting machine, flexographic machine, digital printer and rotating machine in the form of roll-up mainly use Grassin release liner, but also a small amount of thick release liner.