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Sometimes a single resin just isn’t enough to get the properties you need for your packaging. That’s where co-extruded films (also called Co-Ex blends) can help.
What are Co-Ex Blends?
A co-extruded film is an engineered multi-layer film composed of two or more resins. Resins are selected to carefully combine the properties your packaging needs, like moisture and puncture resistance.
Common Co-Ex Resins
High Density Polyethylene (HDPE): used to enhance stiffness, add a moisture barrier or give heat resistance to the outer layer of packaging.
Linear Low Density Polyethylene (LLDPE): adds toughness and strength to Co-Ex films, and can be used in a number of different forms, including octene, hexene and butene.
Metallocene PE (mPE) and mLLDPE: ideal for creating strong seals, high hot tack and low temperature seal initiation.
Nylon (polyamide): creates an excellent chemical and aroma barrier, and is also used for heat resistance and formability/drawability.
Ethylene Vinyl Alcohol (EVOH): produces an oxygen barrier.
Adhesive or Tie Layer resins are used to “glue” or bond disparate layers of material together. Nylon, for example, doesn’t stick to polyethylene, so a tie layer is used to adhere both materials.
These are just a few of the resins families available in the film industry and Versa Pak uses many of them. Contact our team to request a custom blend.
How are Co-Ex Blends Used?
Co-extruded films are frequently used in the food and industrial industries, but can help you achieve the packaging properties you’re looking for in a variety of different applications. Here are a few frequently used resin combinations:
HDPE + LLDPE + mPE
Consider the bag inside your favorite box of crackers. The outside layer of the bag is often an HDPE layer that creates a moisture barrier (no one wants soggy crackers!). The LLDPE layer provides toughness to prevent pinholes or stress cracks that could cause the crackers to become stale before purchase. Finally, an mPE layer seals up the bag at a low temperature.
LLDPE + HDPE + mPE
This combination represents a typical sealant film for a converter flexible package. LLDPE provides clarity and a good bonding surface for lamination; HDPE gives stiffness, bulk and a moisture barrier; and mPE creates a strong and caulkable seal. The final product might include this Co-Ex blend sealant film laminated with adhesives and reverse printed inks to a polyethylene terephthalate (OPET) film.
5 to 9 Layer Structures
Co-extrusion can be taken to the next level by adding more layers. For example, a nine-layer structure like nylon + tie + LLDPE + tie + nylon + EVOH + nylon + tie + mPE represents a barrier forming web. Think about a package of hotdogs that needs to be tightly sealed through grease and kept at a particular temperature. The nylon layers are used for heat resistance, formability and grease resistance. The EVOH creates a barrier to prevent the hotdogs from spoiling. The tie layers bond everything together while mPE effectively seals up the package through the grease.
How Do We Create Co-extruded Films?
Before a Co-Ex blend can be created as a stand-alone film or film for lamination, we need to know a few things:
- What is the product being packaged? (Is it dusty, wet, dry, frozen or sharp?)
- How much does the product weigh?
- Does the product require a barrier to prolong shelf life?
- What type of package do you need? (Stand-up pouch, flat bottom bag, pillow pouch, overwrap, stick pack or something else?)
- Will the film be used by itself or laminated to other substrates and converted?
- What kind of packaging machine will make this film? (Vertical form fill seal, horizontal form fill seal, overwrap machine or something else?)
With the answers to these questions, we can engineer the necessary qualities into a co-extruded film that meets your needs.
The Versa Pak Advantage
All of our Co-Ex blends at Versa Pak are engineered, manufactured and quality tested in our on-site lab before being shipped from our Celina, Ohio warehouse. That means we’ll work with you from start to finish to create the packaging you need.
A few of our capabilities include:
- Up to 5 layers of co-extrusion
- Colors and prints
- 24 inch to 122 inch lay-flat sheeting
- Up to 138 inch bubble
As an SQF-certified manufacturer, all our resins are top-quality virgin and FDA-approved poly so you can be sure you’re getting a great product.
But don’t just take our word for it. Request a custom product sample.