Flex foil

Flex foil and flock foil are materials for cutting plotters that are used for one-off transfer printing. It is frequently used for printing T-shirts with characters in copy shops.

Naming

The name of the flexographic film technology comes from flexographic printing , a letterpress printing process in which a pattern of color pigments (mixed with solvents and binders) is applied to a printing plate using a roller - this pattern of the printing plate is then under pressure and heat (sometimes also by UV activation ) connected (transferred) to the material to be printed.

Manufacturing

With flex foils, the pattern of the printing plate is produced differently - the flex foil consists of three layers, a carrier foil, on top of it a layer with color pigments and then on top a cover layer with hot melt adhesive, which is dry at room temperature and must first be activated by heat for bonding. A cutting plotter scratches the boundaries of the pattern in the top layer - then the top layer is lifted off, which peel off excess color pigments. With typical patterns such as characters, this so-called weeding is only extensive in the first step, since many letters have openings on the inside.

The resulting positive cut on the carrier film is now stretched onto a printing plate for separate transfer printing. As with traditional flexographic printing, this creates an image on the printing plate, which is now activated - usually with heat to liquefy the adhesive - and then bonded to the material to be printed under high pressure (between two rollers of the printing press). The carrier film can then be peeled off. Compare also flock film and flock transfer and electrostatic flocking.

differences

The differences between flex film and flock film lie in the structure of the color layer used, which determines its later properties. As the actual printing layer, the flex foils have a flexible plastic membrane that creates a firm, smooth, pore-free image with the appearance of plastic on the printed material (mostly textile ) - the flock foils have a more traditional printing layer made of flock fibers that creates a rough, slightly porous image that feels like velvet and tends to give the impression of fabric. The image of the older flock film technology is, however, more susceptible to the peeling of pigments - it will lint over time.

Other foils

Closely related to flex films are iron-on films , which can be activated using the heat of an iron . In contrast to today's flex films, there are only two layers, the carrier film and an adhesive layer. The color can either be integrated into the film (it remains on the printed material) or worked into the adhesive layer, which corresponds to a coat of paint after it has dried out. The flock film for applying a layer of color was developed from the latter variant. While the motifs of the iron-on films can also be multi-colored, most flex film cuts remain monochrome. In the case of iron-on foils, there are also variants for domestic use, in which the adhesive layer is prepared with paint using an inkjet printer, which is then ironed on.

However, the resulting color layer in iron-on printing is not very stable, which is why the transparent carrier film is often left as protection. Iron-on prints on textiles are usually only washable up to 30 ° and still peel off over time, while textile printing on flock films can usually be washed at 40 ° or 60 °, the flex films can sometimes also be washed at 80 ° and remain there longer in the originally printed form.