Let’s compare IML to other competing labeling techniques

In-mold labeling is very different from other labeling methods, and that difference begins before the container is formed. At the front end of the molding cycle, just after the previously formed container is ejected from the mold, In-mold labels are inserted into the mold before it closes.

There they wait for the plastic to be blown or injected into the mold, embedding the labels into the wall of the container during the molding process and displacing container resin equal to the volume of the label, about 15%by weight.

There’s the big difference In-mold labels are in the wall of the container. All others are glued onto the outer surface of the container.

That 15% resin savings is a good place to start keeping score of the sustainability list. Only IML allows the molder to light-weight a container while at the same time reinforcing its side walls.

How labeling techniques differ

Pressure –sensitive labeling

For p-s labeling, the container is molded, followed by, in some cases, flame treating before the application of the p-s label. This post-mold operation requires additional equipment, including the flame treaters and labelers, as well as extra labor, floor space, and operating utilities.

The release liner remaining from the p-s labels must be recycled, incinerated, or buried in a landfill.

Functionally, p-s labels can have good graphics, but they are subject to defects on the container, such as flagging, wrinkling, and puckering. Container recycling can be done easily if the label is made of the same material as the container.

Heat transfer label

This is another labeling method that competes with IML. Here again this post-mold operation requires flame treaters and labeling machines plus labor, floor space, and utilities, as well as release liner, which requires recycling or disposal. Heat transfer labels are subject to wrinkling, especially in larger size, and not as durable as in-mold labels. Heat transfer graphics generally are not as good as the photographic quality of IML or p-s.

Shrink sleeves label

This technique increasingly is favored for small-to medium-sized bottles of laundry detergent, fabric softener, and personal care products. Shrink sleeves provide 360-deg, high gloss graphics but require considerably more film material than either an in-mold or p-s label because of their overall coverage.

A label sleeve is placed over the bottle before it travels through a heat tunnel to shrink the sleeve onto the bottle. This heat tunnel and associated conveyor are additional equipment that requires electricity and gas for operation.

Recycling of shrink-sleeved bottles is questionable unless the sleeve and bottle are know to be of the same plastic material.

In-mold labeling

This method is quite different in its simplicity. Most new injection or blow molding machines already are equipped with the label magazines, label placement automation, and label pinning equipment required for IML. At the start of the molding cycle, the label-handling robotics pick up die-cut labels form the label magazines and place them in the open mold where they are held in position against the mold wall by either static electricity or vacuum ports.

The mold closes, and the container resin is blown or injected into the mold. The hot resin fuses and encapsulates the label into the wall of the container. Then the mold opens, and the in-mold labeled container is ejected, ready to receive product.

Which of these choices is the most sustainable? You might be surprised to learn IML is the most sustainable labeling method, not for what it does not have.

Consider this list of items that IML decoration does not need:

Post-mold flame treaters

Post-mold labeling machines

Utilities, such as electricity and gas, to operate those machines

Additional wet or hot melt glue

Extra labor to operate the labeling machines

Extra floor space for the labeling madhines

Release liner to recycle, incinerate, or bury in a landfill

In fact, an in-mold labeled container pops out of the molding machine eith its label already embedded into the wall of the container. Nothing more is needed to make this container ready for filling with product.

All of the other labeling methods must glue a label onto the surface of a molded container in an additional post-mold operation before it goes to the filler or after it is filled with product. Furthermore , most of them requires less expenditure of energy, labor, and non-renewable resources than any other competing labeling process.