Metallized paper: How is it produced and how it can be use?

Metallized Paper: Production Methods and Applications

A metallized paper is a specialized paper product that has been coated with a layer of aluminum, which can have either a matte or shiny finish. This coating not only enhances the aesthetic appeal but also provides protective properties to the paper.

There are primarily two methods employed in the creation of metallized paper:

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Lamination Technique

This technique involves adhering a non-coated paper to a thin sheet of aluminum, typically ranging from 9 to 12 microns in thickness. However, due to the high aluminium consumption, this method is becoming less prevalent.

Vacuum Metallization Method

In contrast, vacuum metallization is the more widely adopted technique. It involves heating aluminum (or a similar material) within a vacuum chamber, allowing it to vaporize and deposit a thin layer on a coated substrate. This method is notably more efficient, using 300 times less aluminum compared to lamination.

Both methods yield a substrate capable of delivering a striking metallic finish for packaging, requiring only a fraction of the aluminum used in conventional foils. Let's delve deeper into the vacuum production process.

Understanding the Vacuum Production Process

The optimal way to produce metallized paper is indeed through the vacuum metallization method. This process consists of three integral steps:

Varnishing Stage

A preliminary layer of varnish is applied to the coated substrate to ready it for metallization. This varnish acts as a barrier, enhancing adhesion by providing a smooth surface for vaporized metal application. The varnishing is performed using a gravure printing-like method and is followed by a drying phase to reduce moisture to approximately 2-3%.

Metallization Step

This stage is arguably the most crucial in the production process. Following varnishing, the paper rolls are introduced individually into a metallization chamber, where the vaporized aluminum is applied directly to the surface of the pre-coated paper.

Lacquering Process

Finally, the metallized papers undergo a lacquering process. The reels are treated with corona discharge to improve lacquer adhesion. This is followed by applying lacquer using a gravure system, similar to the varnishing process, and the product is dried using hot air tunnels. The lacquer can also be colored to achieve desired aesthetics, with traditional colors such as gold being commonplace.

Once dried, the metallized paper is cooled and treated to maintain ideal moisture levels and ensure flatness for subsequent processing into sheets or labels. The coating protects the aluminum and serves as a receptive primer for printing, providing essential characteristics for various applications.