Release liners are commonly used in a wide array of products. Look around you! Consumer goods are full of items containing release liners. These include: wound care dressings, electrodes, transdermal patches, baby care products, labels, tapes, stationary, personal hygiene, feminine care, wearable devices, and many more. An adhesive bandage is the the most common consumer goods example of a release liner. For instance, the film removed from the bandage prior to application onto the skin is a release liner.
The converting manufacturing industry, which uses release liners in most of the converting processes, continues to strive for improvements in not only the finished products, but the raw materials, manufacturing process, and new liner applications. These improvements allow for reduced variability, increased efficiency throughout the manufacturing process, and superior end products for the consumer market.
Release liners are sometimes referred to as ‘carrier’ or a ‘backing’ paper/film. Their purpose is to carry a pressure sensitive adhesive (tacky surface) until it is ready for its next manufacturing or application step. They protect the adhesive prior to its intended application.
Normally, the release liner consists of two components. The first component is a face-stock or a substrate usually made of paper or plastic-based film. When selecting a release liner, it is important to consider what type of face stock to use for the application. Common plastic face stock films are: Polyester (PET), Polypropylene (PP), High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE).
The second component of the release liner is a silicone formulation which allows for pressure sensitive adhesive the liner is carrying to release when the time is right. The silicone formulation selection will depend on how long the liner will be used as a carrier or an adhesive protector, and the release level (ease of removal) of the carrier from the adhesive.
There are also release liners that only consist of a low surface energy substrate. The surface characteristics are customized to carry the adhesive without any silicone coatings. These specialized liners are most common in the highly customized medical device manufacturing applications.
Types and Applications
- Paper-based: As the market becomes more sustainably driven, certain paper-based liners have proven to be a great solution. This renewable resource provides stiffness for those applications requiring rigidity. It is also very forgiving with laser converting used as a base release liner. However, not recommended for applications that requiring a non-tearing substrate or subject to moisture exposure.
- Plastic film-based: A good choice for applications requiring high strength barrier. This barrier protects the adhesive from moisture and air. This option is one of the best release liners as PET films are very consistent and an excellent cutting surface for rotary die processing.
- Polycoated-paper based: This film is ideal for protecting metal parts from various elements including moisture.
- Low surface energy substrate without the silicone coating. These substrates are often times embossed to reduce surface contact and thus reduce release levels.
While there is a variety of different silicone systems available such as solvent based, solvent less, emulsion, and UV cured, they all need to fulfill the one task – being able to release at the right time.
The release properties can be modified by the silicone formulation as well as the coat weight. The liner can be coated on one side (single coated) or both (double coated). Sometimes it is necessary to have a different release property also referred to in the industry as differential release liners on each side of the liner. This design is known as differential coating.
Release liners that are used to protect the product are often customized for company branding. For instance, the liner can be coated/printed with a specific color, logo, or even diecut shape.
Industries Commonly Utilizing Release Liners
Factors to Consider
- Required base material: paper or film
- Silicone coating: single or double sided
- Desired release levels
- Color of the base material
- Roll sizes and estimated volumes
- Final application/ product and production process
- Adhesive used in the application
PLITEK® offers a variety of UV Cured release coated liner chemistries on a range of substrates to suit even the most complex applications. We specialize in release liners up to 22” in width and a thickness of 0.5mil – 10mil. The release options range from low, medium, and high release to meet specific application requirements. Our capabilities allow for custom release formulations of silicone and photo-initiator to achieve the targeted release.
- Polyester (PET)
- High Density Polyethylene
- Low Density Polyethylene
- Back Printing