The Use of In-Mold Labeling in the Packaging Industry

In-mold labeling in the packaging industry

When it comes to the development of in-mold labeling in thermoforming products, both machine manufacturers and automation experts have been on a roller coaster ride. Unlike injection molding, which has accelerated into in-mold labeling like a rocket, thermoforming has had to address several critical limitations in mechanical and labeling technology that have kept in-mold labeling from entering the packaging field since the early 1990s. For example, we often see in-mold labeling in ice cream packaging and empty margarine tubs and other food packaging.

Although commercial success has been limited thus far, observers point out that interest is soaring, primarily in Europe. Many believe that recent productivity improvements and cost reductions in labeling have made the process cost-effective in the end. "With the process ready and the market confident, more and more people are interested in introducing new products with in-mold labeling,"

Benefits of in-mold labeling for empty margarine tubs

In-mold labeled margarine boxes allow manufacturers to save time and money by integrating the labeling process directly into the molding process. This one-step process has significant advantages over traditional decorative methods such as pad printing and flexographic, shrink sleeves, and pressure-sensitive adhesive labels, all of which require secondary operations.

According to industry sources, as in-mold-labeled plastic margarine boxes become part of the product, they contribute to increased rigidity and strength, so thermoformers can reduce container weight by up to 20% by using in-mold labeled margarine boxes, saving up to 20% of resin costs. If the label is made of the same material as the container, in-mold labeled margarine boxes also provide recycling advantages over paper labels.

In-mold labeling is a process that injects into a smooth film surface, textile, or pre-formed film panel on its back. When empty margarine tubs require higher flexibility or when printing cannot be molded directly onto the product, thermoformers commonly employ in-mold labeling as a substitute for printing operations. Labels are typically made of pre-printed polypropylene film with a thickness of a few millimeters. The advantage of in-mold labeled margarine boxes is that it combines downstream processing directly with the injection molding step. The disadvantage is that the thermal insulation effect of the margarine box label is bound to slightly extend the molding cycle.

First, during a single product demolding process, the label is inserted into the injection mold using complex end-of-arm tooling (EOAT) technology. Second, the margarine box label is securely held in place inside the mold by static electricity or vacuum suction. In-mold labeled margarine boxes require similar injection molding requirements as thin-wall molding.