Blister packs are a large and rapidly expanding segment of the global packaging industry. They let consumers see what's inside and reduce tampering, while protecting the product itself from environmental factors, mishandling, and even animals. Blister packaging adhesives are now used for everything from prescription medications and batteries to toys, hardware, electronic goods, and more.
Since it is becoming so popular, let’s take some time and focus on what you need to know about printing blister packaging.
How Blister Packaging Adhesives Are Put Together
In its most basic form, a blister pack usually consists of some type of pre-formed plastic, which encases the product and some type of backing. The plastic is then adhered to the backing.
Along the way, however, there can be many variables that affect the decisions you make. Material for the blister might be a thermoplastic polymer resin, such as PVC (polyvinyl chloride) or PET (polyethylene terephthalate).
The blister card, or backing, might consist of:
- Aluminum Foil
The card or backing usually contains some printing or graphics to draw attention to the item inside. The blister is then affixed to the backing using some type of hot melt adhesive that is activated by heat and pressure, but cold seal may also be used.
Can the Flexographic Printing Process Be Used for Blister Pack Production?
Flexographic printing opens myriad opportunities for the blister pack industry. Flexo is effective at printing a wide variety substrates, which accommodate the various materials used in blister packs.
The one concern to keep in mind is that inks used for printing should be free of ingredients that might compromise the adhesion process, and may need to be heat-tolerant.
Adhesives That Can Be Used in Blister Packaging
Since adhesives used in blister packaging are involved in high-speed production processes, they must be flexible, bond rapidly, cure quickly and stay transparent.
Adhesive options may include water-based, solvent-based, and epoxy blends.
Considerations in choosing the appropriate adhesive include:
- Materials being bonded
- Sealing method
- Adhesive weight
- Adhesive activation temperature
- Drying time required before stacking
- Storage and shipping conditions
- Weight of product
- Negative interactions with product
Adhesive Transfer 101
The adhesive can be laid down with the use of sleeves, cylinders, or plates. Cylinders are ideal for hot adhesive applications, due to the ease of heating them. Sleeves can be used as well, provided they have a nickel core. If using cold seal, fiberglass core sleeves and plates are appropriate.
Regardless of your image carrier type, silicone elastomer is likely the best material option when using adhseives -- due to both its release characteristics and its ability to tolerate high heat.
Challenges When Printing Blister Packaging
As always challenges can arise, such as adhesive build-up, thermal expansion, clean-up problems, and other mishaps. An experienced elastomer sleeve and plate supplier can help ease the process.
Editor's Note: This blog post was originally published on July 10, 2018 and was republished on October 4, 2019 to reflect updated insight and resources.