Wide application of vacuum metallization process is quite recent. It appeared in Europe in 1930 – 40es, and became an essential industrial activity only in the middle of 60es. The technology of the process has experience a great progress since then. It consists of applying an extremely thin metal layer on the basis, which in our target field is mainly plastic film, paper or light cardboard.
The most frequent application of paper and light cardboard metallization is as follows:
The most common application of plastic films:
At present vacuum metallization became one of the fundamental processes in many fields, including in packing and polygraph industries. Metallized films are applied in place of the materials laminated by the aluminum foil. As for metallized paper, its consumption has increased for labels manufacturing.
In view of economic reasons, as well as due to function, quality and aesthetic indicators the demand in metallized materials has considerably grown.
Paper and film metallization have much in common: in particular, application of material is carried out on the same equipment.
There are some differences as well: it is possible, as a rule, to metallize the film right away, while the paper shall be first prepared for metallization. There are also some differences in the process following metal application, namely: only three types of printing initially meant for nonabsorbent surfaces may be used for image application on the metallized film, while the paper may stand any other printing methods.
To provide the opportunity for any high quality printing, the metallized paper shall possess some definite properties. As a rule, metallized layer is applied after special preparation on the paper surface of the brands traditionally used in printing, and then it undergoes special treatment, which enables to print on this metallized paper not only with special methods adapted for printing on nonabsorbent surfaces (flexography, deep printing), but also with offset printing method, when application of printed image on nonabsorbent surfaces is difficult.
The process of paper metallization consists of paper preparation by application of the primer, a special varnish on its surface, metallization with thin aluminum layer by its evaporation in vacuum and the final trimming by other varnish allowing then to print on the ready product with the offset printing method. The final trimming of metallized paper includes also surface texture application, if necessary.
Metallization is carried out by evaporation of thin aluminum layer in vacuum, and in some cases – the final trimming by application of protective varnish preventing from aluminum layer oxidation.
