Coating process

The coating process consists of applying a coating material to a moving web of flexible substrate.

The carrier substrate may be paper, film, or aluminum foil and the resulting material's additional properties will vary depending on the required application and on the material’s end-use.

The benefit of coating is that it delivers to the substrate enhanced aesthetic and physical properties derived from the coating material.

In flexible packaging, the most common types of coating are:

• Varnish: to impart a clear, glossy surface to the web
• Cold seal: used mainly for products where normal heat sealing cannot be used (chocolate bars, ice-creams, etc)
• PVdC coating: used to improve the barrier properties of transparent films, as well as the gloss of printed films

These types of coating are usually applied in-line with a printing press by dedicated units or off-line by coating-laminating machines. Special coatings are also used in industries other than flexible packaging. These applications may include the production of labelstock material, release liner paper and films, as well as a great variety of pressure sensitive adhesive tapes or laminates used in the medical field or in industrial applications.

Different types of coating line may be found in each industry, but broadly speaking each system is based on a roll design and will consist of a metering system for applying the coating material to the substrate, followed by a drying tunnel to dry the coated web before it is rewound. Specialty coating lines can be custom built in order to satisfy a variety of different market requirements.

From its vast expertise in designing and manufacturing both regular and special coating lines, BOBST's Rotomec product line can provide systems for the application of every kind of packaging coating, along with the production of pressure sensitive adhesive tapes and labels such as packaging tapes, reinforced tapes, masking tapes, double sided tapes, special tapes, release paper, and labelstock.