Creep: definition, causes, and effects on thermal rolls

Creep: when the adhesive overflows the edges of the label

Creep refers to the overflow of adhesive on the sides of a label, a phenomenon related to the viscoelastic behavior of the glue under the effects of pressure, temperature, or storage time. Specifically, the adhesive, even when held under a top and backing layer, retains some ability to deform and spread slightly beyond the cut edges of the label, especially when the roll is stored under high pressure or exposed to high heat.

This phenomenon causes several practical problems for the end user. The first is unwanted sticking between successive layers of the roll: the overflowing adhesive comes into direct contact with the face of the next label, which can cause the roll to jam or, in severe cases, partial tearing of the ink or coating on the face during unwinding. The second issue concerns the thermal print heads themselves: significant creep can deposit adhesive residues directly on the print head, accelerating its clogging and reducing its useful lifespan.

Several factors influence the intensity of creep on a given product. The adhesive formulation is the primary factor: Hotmelt adhesives, which are softer and more heat-sensitive, tend to creep more than some acrylic adhesives formulated for better shear resistance. Storage conditions also play a major role: a roll kept in a poorly ventilated warehouse exposed to high temperatures in summer, or stored for a long period without stock rotation, presents a significantly higher risk of creep compared to a recently manufactured roll stored under good conditions.

To limit the risk of creep, several best practices are essential for professional stock managers. It is recommended to store thermal rolls in a temperate environment, away from direct sunlight or heat sources, and to apply a first-in, first-out stock rotation to prevent a product from being stored too long. It is also important to check, upon receipt of an order, for any deformation or excessive compression of the rolls during transport, a factor that can promote creep even before first use.

A reliable supplier should be able to guarantee, in their technical data sheets, an adhesive formulation tested to limit creep under normal storage and usage conditions—a quality criterion especially relevant for professionals using high-speed thermal printers, where the cost of premature print head clogging can quickly outweigh the savings made on a low-end roll.