Key Questions to Ask When Ordering Paper Release Liners

One of the critical choices in purchasing product labels is the type of label liner, also called a release liner. Choosing paper when it should be poly, or vice versa, increases costs, delays packaging production, and hurts the bottom line.

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There are two primary types of liners—paper liners and film liners. The most common film liners are also known as poly liners or PET liners.

So, which release liner is better, paper or film? There are several factors to consider.

Why Label Liner Choice is Important

A liner is the part of a pressure sensitive label that acts as a carrier for the label. It protects the adhesive until the label is ready to be applied. It’s also treated or coated so that the label releases easily during the application process, whether its manual or automatic.

Labels that are destined for automatic machine application must have liners that stand up to the rigors of machine application.

When label liners tear during automatic application, several things happen.

❌ There is more waste. Every machine re-start requires using labels to re-set the machine.

❌ There is more downtime at the factory. Too much downtime because of defective liners can result in charge backs from the manufacturer.

❌ There may be a shortage of labels to finish the production run. This requires costly reprints and results in additional manufacturing costs. Depending on the situation, penalties might also apply.

Reasons Why the Label Liner Tears During Application

Machine processed labels are done on a roll. Die knives cut through the label and adhesive layers but not through the liner.

When the labels are die cut, the waste is stripped cleanly away from the label and liner as shown in the image below.

The printed, die cut labels are rolled and ready for automatic machine application.

If the setup on the die cutting is incorrect, it causes serious problems with automatic label applicators.

All knives should be set to cut through the label paper and adhesive without going into the liner. If the knife cuts too deep, it penetrates the liner, creating a weak spot.

The illustration above shows a weak spot created by the knife cutting too deep.

Each rotation of the die means there will be a re-occurrence of that weak spot throughout the label roll, any of which can cause a tear as the machine applicator runs.

How to Prevent Label Liners from Tearing

There are two ways to avoid liner problems with your labels.

One – work only with label printing companies who use rigorous manufacturing standards and quality control to ensure that labels never ship with defects in the liner and label.

Two – replace paper liners with polyethylene terephthalate (PET) liners. PET, also called poly liner, is a film liner that is much stronger than paper.

Currently, glassine liner papers have about 36% of the market, poly coated kraft has about 24%, with film liners at 22% according to Label and Narrow Web. Here are the pros and cons of each.

Advantages of Poly Label Liners

Paper is hygroscopic, meaning that it absorbs moisture from the air or releases it, depending on the temperature, the relative humidity, and the moisture content of the paper. It is always seeking a balance. As the relative humidity and temperature changes, so do the dimensions of the paper.

This means that paper products must be properly conditioned to the print shop atmosphere prior to printing. Changes to the paper due to improper conditioning causes problems in printing, die cutting, coating, or lamination. In turn, these problems can cause stoppages in the automatic label application machinery.

✔️ PET is also hygroscopic but to a lesser degree than paper. In fact, moisture stable paper release liners are made by coating both sides of the paper with a polyethylene to inhibit moisture absorption.

✔️ PET is thinner than liner paper. This means the average roll can get up to 20 to 30% more labels on a roll. In turn, this reduces transportation costs.

✔️ More labels per roll means less changeover time, which increases packaging productivity.

✔️ PET is stronger and breaks less frequently than paper. This added strength means machines can run considerably faster with less downtime.

✔️ PET is better than for wet application conditions.

✔️ PET liners reduce waste volume, with liners as thin as 23 microns, or about 0.”. Glassine paper liners are typically about 50-70 microns thick.

✔️ PET is less susceptible to curl than paper. Flatness is a key element to high label applicator productivity.

✔️ PET produces less dust than paper liners, which is important in pharmaceutical, electronics, food, health, and cosmetics packaging.

✔️ Because of current paper supply problems, lead times for PET are shorter than paper liners.

✔️ PET is better for labels that are used in harsh environments or that will be exposed to the elements.

Advantages of Paper Liners

There are times when paper liners might be the better choice.

✔️ Paper is more rigid than film and is better in applications in which rigidity is required.

✔️ Paper is more sustainable and has chain-of-custody certification available to track fiber from the forest through its end use. However, film liners are catching up with improved liner recycling processes coming into place.

Link to Zonem

✔️ Paper liners are generally lower cost.

Final Thoughts on Paper vs Poly Release Liners

There is no single “right” choice when it comes to paper versus PET release liners. Much depends on the end use of the label along with the label application process.

We can work with you to eliminate common mistakes caused by faulty liners, and help you select the product label that’s best for your bottom line.

Call us at 818.709. or Contact Clear Print here to talk about selecting the right release liner for your next job.

What is best option for your product labels?

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A label release liner is probably not something you think about often but it’s a very important part of pressure-sensitive labels. The release liner is a backing material on labels and stickers that carries them until your labels are ready applied. Its job is to protect the adhesive and keep your labels from sticking to each other or something else before they’re ready for their intended use.

In this article, we’ll explain the difference between paper and PET label liners and what is the best option for product labels.

Label liner materials

There are a variety of different release liners available for labels and stickers. Depending on your label application and specific product features, there might be an option that works better for you. The most common release liner materials are paper or PET film.

If your labels are going to be used in an automatic labeling applicator they must have the right liners to hold up in the machine. Otherwise, it can result in more waste, company downtime, and material shortages.

PET release liners

 PET liners are primarily important for high-speed automatic labeling machines. They are made from polyester film, which is thinner than paper liners so you can roll more labels on each roll. This reduces roll changes during high-speed or large-volume label applications, and it also reduces waste. Since the rolls can be smaller, this can also save storage space and shipping costs.

PET release liners are also ideal for things like labeling beer cans that require a wet application. They generally have fewer breaks on automatic machines than paper liners, which saves time and money.

Paper release liners

Paper liners are one of the most common release liners and the most economical. aper release liners have a silicon coating to prevent the label adhesive from sticking to the paper underneath below. That way you can separate your label and liner easily when ready for application.

They offer good tensile strength and won’t break when converting into labels or being wound on a label applicator. While they are strong under tension and can perform on high-speed packaging lines we don’t recommend them for things like wet applications.

Avery WePrint offers a clear film PET liner that is ideal for things like beer can labels or you can order our standard paper liners available on most labels and stickers.

If you are thinking about switching your release liners or need any help, contact us at (800) 942-.  As always, we can also provide samples to help you compare your options.

Author:

Melanie has an extensive writing background built on an impressive journalism foundation. As a reporter for USA Today and The Los Angeles Times for almost 20 years, she covered everything from the Los Angeles riots, fires, and floods to LA Lakers, Raiders and Clippers games and movie premieres. She followed her newspaper career with a long tenure covering commercial real estate financing and development. Melanie has been writing about small business marketing and labeling needs for the last 12 years. She thrives on reading, researching and expanding her knowledge of everything going on in today's business world and looks to provide the most valuable information she can to her readers. View all posts by Melanie Neff

As a converter of self-adhesive materials we like to discuss self-adhesive tapes and pressure sensitive adhesives (PSA). However, an often forgotten material in the adhesive landscape is probably the release liner. People often call this the  “carrier” or “backing” of a tape. This  product which is most of the time a coated paper or film that holds the adhesive material and is at the same time as a protective shield until the purpose of the self-adhesive is required.

What is a release liner?

Release liners are coated papers or films that carry adhesive materials.

Liners have 2 important functions:

1. Serving as carriers
2. Protective covering for pressure-sensitive adhesive laminates.

That means liners make sure that the self-adhesive material does not get damaged and is crucial for a consistent tape quality. The terms are exchangeably used and release liners are referred to as carrier or backing.

The base of a release liner is often paper, poly coated paper, film, or a metalized film. The liner can be coated with silicone or non-silicone to have an easy release from the adhesive. It all depends on the surface in combination with the requirements of the dispensing system needed for the application.

The release liner is in most cases one of the most critical decisions you will have to make while designing an PSA. It has to have the correct quality and feature to exactly match the application, both hand applied or automatic dispensing, and processing like for instance slitting and die-cutting.

TYPES OF RELEASE LINERS

• Paper liner— Most common release liners is paper and available four types:
  1. Polycoated Kraft (PCK)
  2. Extensible Polycoated Kraft (EK)
  3. Densified Kraft (DK)
  4. Extended Densified Kraft (XL).
• Film liner — Film release liners are used more and moree, especially for labels and tapes, and for industrial and medical/healthcare (electrodes, wound care, diapers, etc.). Film liners have two types in general:
  1. Polyester (PET)
  2. High-Density Polyethylene (HDPE). If you need more stretch in the liner you can choose a Low-Density Polyethylene liner (LDPE).
• Specialty liner— These release liners are specialized films like a metalized film and other substrates for highly specialized applications in various industries including aerospace, automotive, renewable energy, etc

Here’s an example. A print company is preparing inkjet cartridges. It’s crucial to the automated assembly process that the release liner performs well so it releases from the liner and accurately dispenses onto the cartridge.

The technology behind release liners

There are four key release liner substrate construction categories:

1. Direct coated papers
2. Clay coated papers
3. Polyolefin coated papers
4. Coated films

Every release liner has a couple of variations which depend on several factors. Below are a few examples of how this construction can look like.

Merging your converted adhesive part with the best liner is vital for most applications, including the assembly processes. There are many types of release liners that are compatible with adhesives. See a selection below.

• Easy, medium, or tight release
• Single- or double-sided release
• Medical grade
• Split back
• Butterfly
• Tabbed
• Printed
• And more

When working with release liners, it is recommended to work with a seasoned tape converter. This company should be experienced with many types of material, invests in equipment and want to understand your product from A to Z.

Silicone coated film has seen increased use in the electronics industry as a release liner for films applied as protective layer during circuit board processing. For sensitive and complex PCB processing, silicone coated films must meet published specifications, such as the level of temperature resistance and release characteristics.

Essential properties of silicone release liners on film for electronics applications

Release films for electronics applications are made of a polymer layer, such as polyethylene terephthalate (PET) to which a very thin silicone coating is applied. The polymer itself will depend on the final properties of the film, such as the ability to withstand temperatures over 200ºC, but in all cases, it’s important that the film has high strength, is chemically inert and sticks well to the PCB. In terms of the silicone layer, it’s important that no silicone residue is left on the sticky layer after release. This is especially crucial for semiconductor electronics, where silicone could migrate into the device and impair performance. The thickness of the silicone layer must be within a given range to ensure the film has right flexibility to completely cover features on the substrate, and the silicone layer must have the right release profile to work with the process tooling system.

Where XRF can help in the manufacturing process

As mentioned above, the release characteristics of the liner can be changed depending on the application - and this characteristic is an important part of the liner’s specification. The release characteristics are determined by the quality of the silicone layer coverage, the completeness of the silicone curing process and the silicone formula itself. It’s important to control these parameters carefully during release liner production to ensure the final product meets the specified release characteristics.

XRF helps to control the quality of the silicone layer by returning a value for coat weight. For the very thin layers applied, there is a linear relationship between the XRF silicon signal and the coat weight, provided the instrument has the right calibration. This makes it a very simple exercise to determine the thickness of the layer as you can take a single, rapid measurement on a sample of coated film. There’s no chemical processing or manual calculations involved, unlike other methods such as atomic absorption spectroscopy (AAS). This simple coat weight measurement is useful during process engineering when determining the curing level of the silicone layer. Here, you simply measure the coat weight with XRF before and after extracting the excess silicone to determine the effectiveness of the curing process.

Introducing the LAB-X for quality control of silicone on film

Hitachi’s LAB-X is a benchtop XRF analyzer that’s ideal for silicone coat weight analysis. Rugged, compact and powerful, the LAB-X is designed for constant use in a production environment. Once a sample has been prepared (simply by cutting a small disc of coated film and placing it in a sample holder), the operator presses the start button and within seconds results are displayed on the screen.

The instrument parameters are optimized for this application, and it’s simple to set up a pass / fail value within the software, removing the need for the operator to interpret the results.

Also, the LAB-X has a built-in sample spinner–rotating the sample during the analysis to provide a repeatable coat weight result.

You can find more information on the LAB-X for release liners here. Alternatively, get in touch to arrange a demo.

The company is the world’s best Paper Release Liners supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

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