Flocking

Electrostatic flocking is based on the theoretical basis that particles may be moved by electrical forces. Short cut fibers are called Flock. To an adhesive coated surface of millions of these fibers are placed in an electric field. Field lines bring the fibers to align perpendicular to a very high degree of uniformity, so that a textile, velvet-like surface is created. The reaction in the machine technology is carried out by an adhesive layer is applied to the material to be planted with the help of screen printing. Each sheet is individually inserted in the screen printing machine. Now is the viscous adhesive with long open time according to the points to be flocked. In the next step, the sheet passes through the electric field(about 60.000 V)between the high voltage electrode and the counter electrode. The Flock shoots at a high speed perpendicular to the adhesive and sticks. Upon impact to discharge the fibers and fly from the surfaces without adhesive back to back high-voltage electrode. After drying, the sheet can be sucked or blown in order to remove excess flock. The print image is created. Subsequently, the sheet can be further processed. Through quality adhesives that are used today, flocking have become resistant to abrasion and very durable. It may either be of the acrylic latex adhesive and 2-component polyurethane adhesive (resin and hardener) can be used, whereby the polyurethane adhesive, the best results are achieved and different types of paper can be processed. The durability can be optimized by adhesive, flock and support material to be coordinated.

This effect makes plastic impression through special optics, combined with an extraordinary haptic experience. The temperature of flocked surfaces by touching with the fingertips is perceived as warmer. Thus, this processing technique has a high sentimental value. The electrostatic flocking is suitable as a surface finishing of high quality packaging, book covers, brochures, advertising and Christmas cards. The flock fibers can be produced in different thicknesses, colors and lengths. Thus, distinctive surface structures can produce, ranging from silky smooth over rough bristly-up hard and scratchy. Also the appearance and the function is affected thereby. The Flock thickness is measured in dtex(grams per 10,000 meters in length) and the flock length in millimeters. The ratio of fiber length to fiber thickness determined the feel of the flocked surface. The longer and thinner the fibers are the softer the surface later. The thinner and finer the lines to be transferred, the shorter the length of flock should be. Flock is a usual length of 0.5 mm. In a flock length of 1 mm, the relief-like appearance comes better advantage, but the contours are blurred. 2 mm is sometimes used as a lawn replica. For fur imitations Flock lengths have already been set to 16 mm, but Flock lengths over 2 mm in paper flocking have almost no meaning.

On different substrates surfaces throughout(areal flocking) or only partially(design flocking) can be flocked. The support material used is basically any substrate that has a smooth surface and on the sticks of glue. A slight embossing or creasing in the substrate but is tolerable. Thus, the adhesive sets not too strong in the paper, the paper should be painted as a base material at the points that are to be flocked with a primer paint. The absorbency of the paper is lowered so that, the adhesive remains on the surface and binds the flock. The choice of the flock should be optimized for the application range of the-to-be finished printed product. Polyester fibers are ideally suited for example for outdoor use, however the buckling stability is lower. In contrast, polyamide flock holds also high pressure. The fibers in this field depend on again. Basically, all textile fibers can be processed into flock, but only polyamide(nylon) and viscose flock on the market are commercially available. For special applications, polyester and cotton flock is scattered and also acrylic Flock. Nylon and viscose is available in many colors available, each flock supplier has its own color palette.

It can be used as a rule only one color flock in the design of surfaces. With the use of a plurality of colors, the production is complicated and thus expensive. Raster fonts with very thin and fine lines are almost impossible to realize. The fibers swell up, making it difficult to present precise and sharp contours and edges. Therefore, refrain from small sizes and filigree designs. The Flock suppliers offer sample cards with different font sizes, line widths and dot diameters both in positive and in negative. In reverse type and lines you need a much larger line width, otherwise the Flock surfaces "grow together". The maximum sheet size for the flocking is 70 cm x 100 cm. Depending on the length of the flock affect the further processing. The alignment in the stack(e.g. for cutting) is difficult, because the arc start "swimming". It can be used only in very low stacks, where appropriate, the arc must be cut individually.

The relatively slow operation of the flocking with respect to the pressure caused comparatively high production costs. Similarly, the fixed costs for films and templates, as well as setting up the machine are correspondingly high. Due to little inline production and a high proportion of manual work(e.g. when creating in the screen printing machine) relatively high unit costs are to be calculated. With increase in the circulation(from about 1.000 Edition) the unit prices are cheaper. The coverage area of the flock motive and the associated material consumption of adhesive and flock on the price a little influence. But the number of colors used increases the cost of production. A cost savings can be achieved by several benefits arranged on an arc and they are cut by severing cut. After flocking, each sheet must be individually cut or punched to obtain a precise cut.

[1] Kortylak, Heike: Analyse und Anwendung des Veredelungsverfahrens Beflocken im Rahmen eines bestehenden Marketingkonzeptes. Leipzig: Bachelorarbeit an der Hochschule für Technik, Wirtschaft und Kultur Leipzig. 2016

[2] Pfennig, Nicole; Steinwandel, Viktoria: Diplomarbeit. Freie Hochschule für Grafik-Design & Bildende Kunst Freiburg e. V.

[3] Streicheln erlaubt! Effektvolle Oberflächenveredelung durch elektrostatische Beflockung, Palette, Kundenmagazin der Igepa Group, Nr. 55, 2008

[4] Webseite Flock-Tec