Lamination is a technology that allows for improvement of both the mechanical and optical properties of prints by application of optically transparent polymer foil under high pressure to one or both sides of the printed substrate.

Lamination serves to improve the properties of the printed substrate listed below:

  • Higher mechanical durability and toughness,
  • Better appearance of the printed document,
  • Higher resistance to abrasion, lower proclivity to corrosion from human skin,
  • Higher resistance of the print to UV radiation,
  • Impermeability against moisture.

Laminated sheets are easily workable in technology operations such as dry lamination, punch cutting, spot coating, etc.

Thermal Lamination

Hot lamination, or thermal lamination, uses a laminating film with a layer of hot-melt glue. The glue that is applied to the covering film is activated by the heating cell of the laminator; high pressure is then used to apply the film to the printed substrate. This technology may be used for lamination on both sides; the finishing operations may be delivered immediately. The quality of the output can be inspected immediately after lamination.

Dry lamination

Dry lamination is a technology that uses lamination film that is fitted with a layer of adhesive. This type of film is applied to the printed substrate by pressure only. Typically, the film unwinds from a roll. The lamination process may be applied to items that are up to 6 cm thick.

Wet Lamination

The wet lamination process first applies a layer of dispersing, aqueous glue on the film. Before usage on the printed surface, the glue is pre-dried in a drum or tunnel. The film is then applied to the substrate under pressure. Any material treated with this manner of lamination must dry thoroughly before further operations. Lamination defects do not appear until after the glue has dried completely. This method of lamination is used especially in processing large orders in major printing companies. Another negative feature is that both sides of the substrate cannot be laminated at the same time.

Lamination with UV curing

In the case of lamination with UV curing, the laminating film is covered with glue that activates upon exposure to UV radiation. The film becomes sticky and the foil is applied at ambient temperature.

Laminating film

Laminating films are manufactured in a wide range of optical, mechanical, and functional properties that, for the most part, depend on the chemical structure of the polymer. In terms of their optical properties, the films available classify as matte, satin, glossy, structured, clear, optically changeable, metallised, tinted films and films with a pearlescent effect. Depending on their mechanical and functional properties, laminating films may differ in porosity, resistance to chemicals, resistance to abrasion, permeability of chemicals or water, strength, flexibility, resistance to heat and to UV radiation. Looking at their chemical structure, most films are thermoplastic: polypropylene (PP), polyethylene (PE), polyester (PET), also polyvinylchloride (PVC), poly-vinyl acetate (PVA) and cellulose acetate.

In general, the lamination process includes application of a film onto the printed material with glue. The application process differs in the various methods. Adhesion of the layer of printing ink and glue is probably the most problematic part of lamination of prints, especially in the case of prints prepared in digital printing equipment. That is why it is necessary to use a laminating film that corresponds to the type of printing ink and print method used. In the case of dry lamination, the film thickness is approximately 25 μm for glossy films (12 μm film + 13 μm glue) and 30 μm for matte films (15 μm film + 15 μm glue). In wet lamination (dispersion type) lamination, the film thickness oscillates from 12 to 20 μm (glossy films typically 12 μm, matte films 15 μm); the thickness of the glue layer can be modified as necessary. The amount of glue applied is typically 12 to 14 g/m2. Heat lamination foil can be briefly described as a two-layer material that consists of the structural film and a layer of hot-melt glue.

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