Cold Transfer - the process in Sheetfed Offset printing

Cold transfer is realized via two conventional printing units in an offset printing press. The first printing unit applies an application-specific adhesive (adhesive printing ink) via an inking unit, an offset printing plate. Depending on requirements, the ink can be applied either partially or over the entire sheet. Fine lines and fonts as well as halftone effects can be transferred, since the properties of offset printing come into play during adhesive application just as they do with a conventional offset printing ink. Via a second printing unit, which is equipped with a special cold transfer module and an unwinding and rewinding station, the cold transfer product is fed into the printing nip between the blanket cylinder and the impression cylinder and transferred under pressure to the areas of the sheet where the adhesive has been applied.

After the backing material has been removed, the metallized transfer layer remains on the substrate and adheres directly and permanently to the sheet preprinted with the adhesive by means of a special adhesive layer. The substrate is then rewound with the non-transferred areas through the cold transfer module. A wide variety of metallic color effects and shades can be achieved by subsequent inline overprinting of the cold transfer product in subsequent printing units or in a separate work step. Coated art paper and folding carton boards with surfaces that are as smooth as possible offer the best conditions for high-quality cold transfer applications. In addition, non-absorbent substrates such as PP or PE can also be used.

Advantages

• The transfer of finest details, fonts as well as areas and screens are possible in one operation
• Inline and offline overprinting processes are possible.
  No hot stamping clichés are required for cold product transfer.
• No heat or high pressure is required for the process.
  The surface structure of the substrate is retained on both sides, and there is no deformation of the substrate.
• Very short makeready times and fast roll and job changes.
• Fast changeover from cold transfer mode to standard printing mode.
• Very high production speeds.
  Compared to metallized substrates, no opaque white application is necessary for cold product applications. The whiteness of the substrate can be optimally and efficiently utilized by corresponding omission of the cold transfer product.
• Product and cost savings are possible through the use of clocked cold transfer modules.

Cold product finishing in sheetfed offset printing is used today for many different applications. Various markets use cold product finishing to add value to their products:

Examples of use:

Suitable equipment for cold product transfer is available today from the major press manufacturers, such as manroland sheetfed, Heidelberger Druckmaschinen AG or König und Bauer AG. Various systems are now also available that can reduce the effective product consumption per sheet, making the process more attractive and efficient compared to other finishing processes. Production speeds in cold product transfer can today reach up to 18,000 sheets/hour and are therefore also interesting for long runs.

In addition to the cold product modules of the press manufacturers, cold product modules are also available on the market from independent manufacturers, which can be installed as a retro fit on many different series of sheetfed offset presses used worldwide. Depending on the cold product module, either 3 inch or 6 inch cores are used. Below you will find an overview of press manufacturers and cold product modules:

Special printing blankets are used for cold product application, which differ greatly from standard printing blankets in terms of shore hardness, surface texture and roughness.

Depending on the printing process, special cold product adhesives are used in sheetfed offset presses. To produce a high-quality cold product application, a suitable type of adhesive must be used and, if necessary, the speed must be adapted to the conditions in the press and to those of the substrate. Application rates are between 1.5-3.0 g / m² depending on the absorbency of the substrate. Glossy and cast-coated image printing & label papers as well as folding boxboard, are well suited for cold product applications. These types of substrates are mainly used for promotional printing, wet glue labels and packaging on a daily basis and produce high quality results.

However, the final result is highly dependent on the surface finish as well as the absorbency of the substrate used. Uncoated and matt-coated substrates, for example, are not well suited due to their surface structure and absorbency. However, non-absorbent substrates such as PP or PE can also be used for cold product applications, but these should have a surface tension of > 40mN/m to achieve good adhesion.

We recommend performing an application test in advance to ensure that the components used are suitable for your applications. Below you will find an overview of manufacturers and suppliers of conventional and UV -curing cold product adhesives: