1. In-mold labeling must have sufficient stiffness to ensure the label does not bend or deform during multiple transfers.
2. The surface of in-mold labeling must be smooth and have a good feel. Labels must not stick together, and there should be no static electricity after die-cutting to ensure that the robotic arm picks up only one label at a time.
3. The edges of in-mold labeling must be neatly die-cut, and neither side of the label should be damaged.
4. The inks and varnishes used for printing labels must withstand high pressure and high temperature. Under high pressure and high temperature environments, the ink must not peel off, change color, or become distorted, and the label must not wrinkle, bubble, or deform.
In-mold labeling materials must possess both good printability and processability to ensure strong ink adhesion and meet the requirements of subsequent die-cutting, hot stamping, and other processing techniques.
Structurally, in-mold labels typically consist of a printed surface, an intermediate layer, and an adhesive layer. The printed surface displays the graphics and text; the intermediate layer provides stiffness and support to ensure processing accuracy; the adhesive layer melts at high temperatures, fusing the label with the plastic container.
5. In-mold labeling for blow molding requires an embossed or frosted surface on the back of the label to facilitate air removal between the bottle and label during blow molding. Injection molding labels generally do not require special backing texture, but have specific requirements regarding material stiffness, thickness (typically between 65-80 μm), and antistatic properties.
With technological advancements, in-mold label materials are becoming increasingly diverse. For example, transparent PP materials can achieve a "label-free" visual effect; thinner materials can reduce costs and increase container strength while maintaining stiffness; and low-density materials offer better flexibility and molding speed, potentially exhibiting a unique "orange peel" texture after cooling.