In-Mold Labels: A Cost-effective, Sustainable Alternative
Time flies, and as improbable as it may seem, in-mold labeling (IML) debuted in the late 1970s. Looking back historically, IML developed as a high volume, low cost, paper substrate driven market. The beginning applications consisted of long-run blow-molded branded bottles, and to a lesser degree, injection molded containers. But recently, technology has enabled cost-effective short-run production, and sustainability benefits have become attractive.
We at Cork are no strangers to IML. In a June 1996 TechTalk, we first wrote, “In-Mold Labeling Today”, describing the IML process. This market will be driven by technological developments from film manufacturers, converters, and molders. Again, in a June 2005 TechTalk, we wrote, “In-Mold Labeling Improved with UV/EB”, describing how UV/EB coatings satisfy the rigorous requirements of IML.
We also remarked on the global growth of IML, and updated process advancements. Cork, during this period of IML growth, offered both aqueous and UV/EB top coatings to improve label performance, and aesthetics. This Cork coating development activity continues to this day with current recommended Cork coating products such as aqueous coating CORKOTE™ 615 INL and UV coating CORKURE™ 1036HG-18.
Recent Growth of IML Labeling
Currently, IML is reported to be seeing annual growth rates of up to 8%. Data indicates that IML grew globally in 2020 at an average of 4.5% with a total market worth at about $3.23 billion. Market share breaks down to 60% in Europe, 22% in North America, and 11% in the Asia-Pacific. Europe’s IML market has been concentrated with 80% of production in injection molded and thermoformed tubs. Meanwhile, in North America blow-molded bottles or containers have continued to prevail.
Great Opportunities for further growth
Now, however, there is an increasing U.S. demand for IML decorated injection molded containers. This is reported to be pushing market growth at a +8% rate in comparison to a 4-6% European growth rate. Incredibly, and recognizing that IML market penetration is only in a minute 2-3% range of the total worldwide label market, great growth opportunities exist for IML.
What is an In-Mold Label?
What is in-mold labeling (IML)? IML is an innovative process for decorating plastic parts produced by blow molding, injection molding, and thermoforming. The heart of the in-mold labeling (IML) process, regardless of the plastic part manufacturing technique, is the placement of a pre-printed paper, synthetic paper, or now dominantly film-based label inside a container mold. This is done before formable hot plastic material is blown, injected, or thermo-formed to form a bottle, container, tub, or other objects. Consequently, the label, laying in the same plane as the surface of the plastic part, is integral to the plastic part without a visible edge. This is in contrast to the alternative, post container forming, adhesive labeling.
Specifically designed IML labels are able to follow the contours of a formed plastic part and are able to cover all sides, allowing up to 360° of decoration. These large surface covering labels are also able to act as a structural, and barrier layer. This capability was previously a feature of shrink sleeve labeling alone. IML is currently taking some market share from shrink sleeve labeling due to recycling and cost advantages. IML is also showing decorative advantages over traditional pad printing on containers with curved surfaces.
New two-sided (front and back) printed IML designs are finding applications on clear walled containers. Here, information can be shown on both the front and backside of a label. In a way, twice the displayed information for the price of one. Additionally, transparent labels on transparent containers have had great appeal. Label enhancements such as 3D tactile effects can also be offered, as can consumer attracting lenticular and metalized film effects.
Inks and Coatings for IML are Critical
Inks and coatings selection is critical to producing labels that will functionally perform in the IML process. Whether the process be blow molding, injection molding or thermoforming, inks and coatings need to be resistant to shrinkage, cracking, discoloration, delamination, and the IML process temperature.
IML coatings are used to protect printed inks, offer aesthetic effects, and reduce any static charge that could slow the die-cutting process. Also, if labels are punched, a coating can prevent blocking. Coatings provide several pluses during injection molding. They contribute to label flatness and do not create static during magazine feeding. Seeming opposite, labels must electrostatically charge when placed inside the mold. Ambient storage is important to this end.
Because high temperatures, +400° F., +200° C. are encountered from hot molten plastics, coatings must have heat resistance. Additionally, coatings must have water resistance because condensation might appear inside the mold. Label coatings need to exhibit reasonable abrasion resistance during product filling and distribution. Here, labels may be subjected to pasteurization, or hot-fill processing, as well as frozen storage. Packaged product resistance is also important as some of these may be quite aggressive (detergents). Additionally, inks and coatings must resist migration, or transfer into packaged products, especially food products.
New, Shorter run Processes
Printing/coating processes have been shifting to those that can support the demand for shorter runs. Here, gravure is yielding to sheet-fed offset and narrow/mid-web roll, conventional and digital processes. Leading the way are high-speed sheet-fed presses that now are able to process very thin 50-micron films. Off-line rotary die-cutting plays a key role in supplying cut and stack magazine-fed IML. Cut-in-place is also a technique wherein a molder processes roll labels, die-cutting at the molding machine.
Initially used for IML were heat-seal backed paper products. Newer synthetic paper substrates have gradually replaced these due to recycling requirements. Likewise, the use of films has exploded with PP now approaching 50% of IML usage. Blow molding favors HDPE, cast PP, and other co-polymers. Injection molding favors OPP.
The future for IML is rosy because of the great benefits provided. Attractive are labeling costs that are radically reduced and labeled products that are 100% recyclable. Additionally, there is the capability to produce high-quality consumer appealing, aesthetic designs. Further, label tampering is eliminated, and durability lends itself to the rigors of e-commerce distribution.
Cork’s business is the development and formulation of Aqueous, energy-curing Ultraviolet (UV), and Electron Beam (EB) specialty coatings and adhesives. If you have questions regarding In-Mold Labeling or labeling adhesives, please contact our team.
