Release Liner - A Complete Overview
Release liners are coated papers or films that carry sticky materials.
A very common everyday use are stickers and labels in the household: The shiny paper that carries the stickers is the release liner.
But release liners can do more than that.
They are vital for the product decoration industry – pressure-sensitive labels, the most commonly used labeling technology in almost every industry, rely heavily on release liners.
What is a release liner?
As stated, release liners are coated papers or films that carry sticky materials.
They have 2 key functions:
- Serving as carriers
- Protective covering for pressure-sensitive adhesive laminates.
That means they make sure that the self-adhesive substance doesn’t get damaged. This is crucial for a consistent label quality. Often, the terms are used interchangeably and release liners are referred to as carrier or backing.
However, release liners are a complex product.
When speaking of release liners, the base material, substrate base weight, substrate color, coating silicone technology, the thickness of the coating, release level, one-or two-side coating and performance criteria are crucial for the end-use. We will not dive into all of these in detail, but this gives you an overview of how the process of creating individual release liner products can look like.
Where are release liners used?
Release liners are typically used in two ways:
– They carry and protect a self-adhesive product that is meant to be affixed to another surface later (example: bottle labels)
– They carry and protect materials where release characteristics are needed, or they separate two separate surfaces
Release liners are often a critical feature of a layered construction.
But although they are considered a very important material and a key component for the delivery and application performance, they ultimately get disposed of and are therefore sometimes perceived as a low-value process component.
Release liners are used in a variety of applications and sectors:
- Graphic Films
- Industrial (Electronics, Building & Construction, Composites)
- Food & Bakery
How the technology behind release liners works
There are four core release liner substrate construction categories:
- Direct coated papers
- Clay coated papers
- Polyolefin coated papers
- Coated films
Each has a number of variations that depend on many factors. Here are a few examples of how they could look like in practice:
Paper still accounts for the bulk of demand, although films are steadily increasing their share, particularly in labels, tapes, industrial, hygiene and medical applications.
The Key To Release Liners: The Silicone Technology
The silicone technology ultimately creates the characteristics of the release liner. It can come in a multitude of varieties that have to match the specific application demands.
The pressure-sensitive industry places an additional list of requirements on the liner, to ensure compatibility with adhesives, further processing, like slitting, die-cutting and matrix stripping and consistency of the final release properties for hand applied or automatic dispensing.
Release Liner: Industry & Market
Release liner manufacturers operate in-house or commercially.
In-house manufacturers are companies who silicone coat papers or films for the manufacture of their own pressure-sensitive products. On the other hand, commercial manufacturers create custom coatings for individual company requirements for commercial sale in the “open” market.
How Release Liners are recycled
About 2/3 of release liners still get disposed of in landfills. This remains an issue, as release liners are not biodegradable.
As a composite product of silicones and paper, they are not easily recyclable. However, pressure-sensitive label waste constitutes of quality reusable materials. Legislation around the world is increasingly supporting the recycling of release liner waste. One example of this is the ambitious Circular Economy Package instituted by the European Commission, setting clear targets for the reduction of waste. A Life Cycle Assessment (LCA) of the product reveals the footprint of the products and the liners along the supply chain.