Flexo printing is the common name for the flexographic printing process, and it is used for a number of purposes in packaging, including label printing. It utilises flexible relief plates, and can be used for printing on almost any type of substrate, including polymer films, metallic films, and paper. The flexo process is also well suited for printing large areas of solid colour.
Typical products printed using flexography include corrugated carton boxes, flexible packaging including retail and shopping bags, food and hygiene bags and sacks, milk and beverage cartons, flexible plastics, self adhesive labels, disposable cups and containers, envelopes and wallpaper. Flexographic printing can be used for a range of materials, requires only short print preparation times, is low-cost, and delivers clean prints.
In general terms, flexo printing employs a flexographic plate (made of polymer or rubber) with a raised image or text that is attached to a cylinder.
There are three major types of inks used in flexo printing: water-based, solvent-based and UV-curing inks. Flexographic inks generally have a low viscosity, which enables faster curing and, as a result, faster production and lower costs. For label printing the process uses different types of flexible polymer plates with a backing layer, a light-sensitive relief layer, and a protective film coating. After a prepress process, the plates are mounted on a sleeve or print cylinder using a plate mounting tape. The required image can also be engraved directly on printing sleeves.
Labels requiring high quality have generally been printed using the offset process until recently. However, great advances have been made to the quality of flexographic printing presses, printing plates and printing inks. The greatest advances in flexographic printing have been in the area of photopolymer printing plates, including improvements to the plate material and the method of plate creation.
Label flexographic presses are capable of producing high quality impressions on many different substrates and is the least expensive and simplest of the printing processes used for decorating and packaging printing. The use of flexographic printing is on the rise, thanks to relatively simple operations, and the ability to use water-based inks, which means a large reduction in VOC emission in the printing process. Modern flexo presses are focussed on reducing cost of setup.