Self-adhesive (pressure-sensitive) labels use two main paper substrate types, each requiring a different printing approach.
The first type is a paper substrate combined with an adhesive coating 鈥?typically an activated glue formulation. These can be printed on conventional (non-label-specific) presses.
The second type uses a surface paper base coated with pressure-sensitive adhesive. This type requires a dedicated label printing press, which handles printing, embossing, die-cutting, and lamination in a single integrated pass. The printing methods available include letterpress, offset (lithography), flexographic, and screen printing.
Self-Adhesive Label Printing Methods
Plate-making for self-adhesive labels centers on producing the printing plates 鈥?involving punching and flat-pressing steps. The plate formats are diverse: relief (letterpress), gravure, offset (lithography), and flexographic. Flexo printing, in particular, has been gaining market share steadily and is now the mainstream label printing technology across Europe and North America.
The three primary label printing methods are:
- Flat-bed (platen) printing 鈥?Best suited for short runs, sheet-fed applications, and when frequent plate changes are needed
- Rotary printing 鈥?The dominant high-speed method for medium to long runs; compatible with flexo, letterpress, and offset units
- Screen printing 鈥?Chosen when thick, opaque ink deposits are needed, such as for high-opacity white underprints or tactile effects
The right printing method depends on the desired print quality, production volume, substrate characteristics, and the end-use requirements of the label.
Die-Cutting Technology
After printing, labels are die-cut to shape. Three die-cutting technologies are used in label production:
- Flat-bed die-cutting 鈥?A flat steel rule die presses against a flat counter-plate. Simple and cost-effective for short runs, but speed-limited
- Rotary die-cutting 鈥?A cylindrical die rolls against an anvil roller. Much faster than flat-bed, the standard for high-volume label converting
- Magnetic rotary die-cutting 鈥?A magnetic cylinder holds etched thin metal die plates. Combines fast changeover with rotary speed; ideal when cutting shapes change frequently
Ink Selection
The ink system must be matched to three variables: the printing method (flexo, letterpress, offset, or screen), the drying/curing method (air-dry, heat-set, or UV-LED), and the substrate material (paper, film, or foil). Getting the ink right is the difference between a sharp, scuff-resistant label that satisfies the customer and one that smudges, peels, or fades before it reaches the shelf.
References
- Wikipedia: Pressure-Sensitive Label 鈥?Overview of self-adhesive label construction and adhesive technologies
- Wikipedia: Flexography 鈥?Flexographic printing process, the dominant label printing technology
- Wikipedia: Screen Printing 鈥?Silk-screen printing method for thick ink deposits in label applications
- ISO 12647-6 鈥?Flexographic Printing Process Control: International standard for process control in flexographic label printing
- Flexible Packaging Association (FPA) 鈥?Industry association for flexible packaging and label converting technologies