The Cold Transfer - the process in Narrow-Web web printing
In narrow web web printing, cold transfer can be used in flexographic printing as well as in offset printing and letterpress/letterpress. Mostly, cold transfer is used in flexographic printing, where a UV-curing adhesive is applied to a substrate by means of an anilox roller with an application-specific scoop volume via a usually exposed polymer plate. Immediately afterwards, the cold transfer web is applied to the substrate by means of a press roll. After this step, the UV adhesive is cured by the cold transfer product using UV radiation and the substrate is removed. The ultra-thin layers of the product remain on the substrate at the points where the adhesive was previously applied. In subsequent printing units, the product can be overprinted inline in multiple colors, whereby numerous metallic effects can be individually achieved. Depending on the absorbency of the substrate used, the amount of adhesive applied must be adjusted via the anilox roller. The adhesive application can be controlled very precisely in flexographic printing via the scoop volume used and the engraving type of the anilox roller.
- The transfer of finest details, fonts as well as surfaces are possible in one operation.
- Inline & offline overprinting is possible.
- No hot stamping clichés are necessary.
- The process does not require heat or high pressure.
- Application on heat-sensitive substrates possible.
- The surface structure of the substrate is retained on both sides.
- Very short makeready times and fast roll and job changes.
- Quick changeover from cold transfer mode to standard printing mode.
- Very high and market standard web speeds possible.
- Also available as shrink sleeve (shrink label) version for counter printing.
- Compared to applications with metallized substrates, no opaque white application is necessary for cold transfer applications, and the white grade of the substrate can be optimally and efficiently utilized through appropriate omission.
Markets & Fields of Application
Cold transfer finishing in web printing is used today for various markets. The following examples show an overview of the markets that use cold transfer finishing to add value to the respective end products.
- Food and beverage industry
- Spirits & wine
- Cosmetics industry
- Personal care
- Pharmaceutical industry
- Toy industry
Substrates & Adhesives for Cold Transfer Applications in Web Printing
Suitable substrates include various plastics such as PP, PET or PE, which are mainly used for self-adhesive labels but also for flexible packaging. However, tube laminates can now also be finished with cold transfer products. A corona pretreatment is recommended. For good performance, a surface tension of > 38 dyne is necessary. Coated papers and folding carton boards can also be finished by web printing. However, highly absorbent, uncoated substrates are less suitable for cold transfer, as the adhesive will strike off too quickly. Good results can, however, be achieved with the help of a primer pretreatment, as this allows the surface to be closed and the absorbency to be reduced at the same time.
Univacco Cold Transfer products for web printing
With the CF series, Univacco produces and supplies a wide range of cold transfer product types and inks for narrow web presses. Univacco cold transfer products have a high gloss and are suitable for both flat and fine motifs and fonts. Good adhesion can be achieved with many different cold stamping adhesives available on the market.
Univacco Narrow-Web Cold Transfer products