Label components

Labels are composed of three basic parts: the liner, the adhesive, and the face sheet. Labels may also have topcoats that affect printing. To prevent labels from peeling off, follow the recommended label design guidelines. Peeled off labels could cause jams. The label or adhesive could also melt when the sheet is jammed in the fuser. Choosing appropriate materials for each of these label components helps ensure reliable printing.

Liners

The liner, also known as the carrier or backing, is the material onto which the label is attached. The liner carries the label through the printer and directly affects feed reliability. Liner weights and construction vary based on the printable face stock used. For more information, see Face sheet (printable stock).

Tissue‑backed, plain bond, or bond‑like, porous, lay‑flat liners are preferred. Liners constructed for use with high‑speed laser printers (50 pages per minute or more) may not produce acceptable results.

A liner should bend easily and go back to its original flat state when released. Forms that remain bent may cause paper jams or damage to the edge of the sheet. This bent affects earlier printer models using a corner buckler rather than a pick roller assembly to separate the sheets.

Some liner materials used in pressure‑sensitive constructions are called label papers. Label papers are either machine finish (MF) or English finish (EF) papers that are calendered, supercalendered, or coated on one side. An MF has varying degrees of surface smoothness. The number of times the paper passes through the rollers (wet or dry) during manufacturing determines the surface smoothness. An EF is uncoated and low gloss in appearance. Label papers may also be used as the face sheet for pressure‑sensitive paper products, such as the materials used in dual web forms construction.

Supercalendering produces high gloss surfaces that may be slick. Some supercalendered liners are difficult for printers to pick and feed reliably. We do not recommend using supercalendered liners designed for high‑speed laser printers (50 or more pages per minute).

Some pressure‑sensitive constructions use kraft liners or bleached ones. Kraft liners are made from sulfate pulp and are MF or machine glazed (MG). Most MG papers have a high gloss appearance. High gloss, glazed surfaces may increase skew and are more difficult for the printer feed mechanism to handle reliably. Some kraft liners may produce acceptable results; however, we strongly recommend extensive testing of pressure‑sensitive constructions using kraft liners.

Tissue‑backed or plain bond liners reduce toner contamination inside the printer and improve feed performance. Slick, non‑porous liners are harder to feed and increase toner buildup in the fuser and on the backup roll. Rough backings can increase paper path friction, which can cause skew and paper jams. The face material of the liner needs to have a melt temperature that can also withstand the fuser temperatures of nearly 225°C (437°F). A stripped area of a maximum of 3 mm (0.12 in.) can expose the face material to these temperatures and could cause melting or contamination in the fuser.

Excessive paper dust or chaff associated with the liner may affect print quality. If a liner produces excessive paper dust or chaff during conversion, then the debris may be packaged with the material and end up in the printer. These properties as they feed through the printer may also affect print quality. For more information about liners, see your label supplier.

Adhesives

There are three basic types of label adhesives: removable, permanent, and semipermanent (cold temp). All types, with proper design, can be used with your printer. Acrylic‑based adhesives are generally preferred for cut‑sheet label printers.

The major adhesive‑related printing problem is printer and cartridge contamination. The adhesives are semiliquid and may contain volatile components. If the sheet jams in the fuser, the adhesive can melt, contaminating parts of the printer or releasing fumes. To avoid exposing adhesive to the paper path guides, drive rollers, charge roller, photoconductor drum, transfer roller, and detack fingers, use full label sheets.

Zone coating means placing the adhesive only where needed. Paper labels and integrated forms typically use zone coating. In addition, a non‑adhesive border of 1 mm (0.04 in.) around the outside edge of the label sheet generates good results. For more information about designing labels for your printer, see your adhesive manufacturer or label supplier.

A stripped edge matrix along the outer border of the stock, combined with adhesive that does not ooze, helps prevent adhesive contamination. This design requires a stiffer backing material to prevent damage when the sheet is aligned on the reference edge. Generally, vinyl and polyester labels are well‑suited for this design. Paper and dual web designs may require testing to determine which backing produces good results.

Make sure that the release strength is adequate so labels stay attached to the liner and do not peel off in the printer. Adhesives should withstand pressures up to 25 psi and fuser temperatures of 225°C (437°F) without delaminating, creating hazardous fumes, or oozing around edges of labels, perforations, or die‑cuts. Shear strength should be strong enough to prevent adhesive stringers. For more information, contact your label supplier.

Face sheet (printable stock)

Paper, vinyl, and polyester are the most common materials used for printable stock. Printable stock must withstand temperature up to 225°C (437°F) and pressures up to 25 psi. For more information, see your label supplier.

Carefully test the printable stock to make sure that it functions satisfactorily with your printer.

Topcoats

Topcoats for non‑paper labels may be either water‑based or solvent‑based. Avoid topcoats containing chemicals that emit hazardous fumes when heated or exposed to pressure. Topcoats affect the print quality, feed reliability, and adhesion of toner to the face sheet. Topcoats should withstand temperatures up to 225°C (437°F) and pressures up to 25 psi for 100 milliseconds to prevent fuser damage.

Water‑based topcoats tend to be more conductive than solvent‑based topcoats and are more difficult to fuse. With some water‑based topcoats and heavy liners, the fuse grade may fall below acceptable levels. Solvent‑based topcoats tend to be lower in conductivity than water‑based topcoats. With some solvent‑based topcoats, fuse grade is within acceptable levels when heavier liners are used.

Print quality may degrade when using topcoats on labels with heavier liners. Using a lighter liner may reduce the appearance of splatter. Carefully test the labels to make sure the topcoat functions satisfactorily with your printer.