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Coating & Laminating Processes
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| Coating |
The most common types of coating in flexible packaging are the application of varnish to impart a clear, glossy surface to the web; the application of cold seal, i.e. self-sealing through simple pressure, used mainly for products where normal heat sealing can't be used (chocolate bars, ice-creams, etc) and PVdC coating that is used to improve the barrier properties of transparent films, as well as the gloss of printed films.
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| Laminating |
Laminating processes can be classified according to the type of bonding agent used to produce the laminates:
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- In wet lamination the bonding agent is still in a liquid state when the webs are joined together. It is commonly used to produce a paper-aluminium foil laminate that is widely used in flexible packaging
- In dry lamination, the bonding agent, dissolved into a solvent, is applied on to the less porous and more heatsealable web, before being evaporated in the drying oven. Then the adhesive coated web is laminated to the other web under a strong pressure by means of heated rollers to improve the bond strength of the laminate
- In wax lamination the bonding agent, wax or hot melt, is applied in a molten state onto one of the two substrates. This process enables to produce paper-paper or paper-aluminium foil laminates that are widely used for packaging biscuits and bakery products in general
- Solventless lamination is a process where the adhesives used do not contain solvents.
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