• Film for flexo mounting

    When we do shopping and stop in front of the shelves of a supermarket we could hardly believe that the beverages we are going to buy have something to do with flexibility and elasticity. Multi-colored labels, plastic and metal wrappers containing all types of food, shopping bags and many other products commonly used in everyday life share in fact the same origin.

    All of them are the results of a printing technique named flexography, also abbreviated to flexo. Packaging industry is undoubtedly the main field in which flexo is applied, creating a variety of printed products that range from brown corrugated boxes and adhesive tapes to milk cartons and food bags.

    Anyway, flexographic printing finds application also in other sectors, such as newspapers, bio-medicine and electronics up to solar photovoltaic modules. Compared with offset printing, flexography achieved better quality standards more recently and exactly from the early nineties, though it was invented in 1890.

    The first flexo machine appeared in Liverpool, England under the nickname of Bibby’s Folly from the builders’ name and the smudgy look of the prints realized with water based inks. UV inks are now commonly used in flexography, which basically consists of a flexible relief plate wrapped around a cylinder which prints the substrate i.e. metallic film, plastic or paper, by the use of a pressing roller.

    The use of double-sided adhesive tape on the clean roller enables plate contact and reduces vibrations which could influence the print negatively. The image to be printed can be realized on the flexible plate by photomechanical, electronic as well as laser engrave so that the final printed image is the result of the relief parts inking.

    Flexible plates can be made of rubber, plastic or photopolymer. Liquid polymer plates require the application of special films with particular coatings which can be supplied both in rolls and sheets. They have different thicknesses and can be white or clear transparent. Covering films are used to protect the image negative and are applied after cleaning the negative and the glass underneath. On film application care must be taken in order to eliminate any air bubbles which could compromise the final print. Once the film protection is completed, resins are applied and the negative is put to exposure. Film removal can be effected after the negative has been washed out and dried.

    Flexo print resolution has achieved nowadays high quality standards thanks to the use of photopolymer plates and digital process insomuch as it is being preferred to rotogravure print, which had a key role in the packaging and commercial printing until the last few years.