LAMINATION
Lamination is the technique of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance or other properties from the use of differing materials.
There are different lamination processes, depending on the type of materials to be laminated. The materials used in laminates can be the same or different, depending on the processes.
An example of the type of laminate using different materials would be the application of a layer of plastic film
A laminate is usually permanently assembled by adhesives and bonds by heat system , “dry lamination”, cold system “ wet lamination” by pressing the two layers between a steel cylinder and a rubber coated roller.
the Extrusion coating method insetad uses a melted polymer as a adhesive between layer s insetad of liquid adhesives.
Adhesives can be:
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Solvent base
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Water base
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Solvent less
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U.V.
LAMINATING METHODS:
DRY LAMINATION – USING SOLVENT BASE ADHESIVES OR WATER BASE
It is so called because the bonding between two or more layers occurs after that the adhesive is applied on the web is dried using a flow of hot air and after a complete drying is bonded with another layer by pressure between a heated steel chromed cylinder and a rubber coated impression roll.
In this application are used adhesive which are composed by bonding agent diluted with solvents, the solvent as said, need to be evaporated before the bonding .
Normal method to apply (coat) this kind of adhesive is ROTOGRAVURE system , where a engraved steel cylinder pick up the adhesive from a tray and deposit it on the web which is pressed onto the coating cylinder with a rubber coated
Alternative to solvents in some application it is possible to use water base adhesive.
In case o three layers lamination, for example coffee packaging ( BOPP/PRINT/ALU/PE) the process can be execute in one pass with a machine with double coating and laminating head or in two passes.
Most used coating methods
Common products
WET LAMINATION – USING WATER BASE
It is so called because the bonding between two or more layers occurs just after that the adhesive is applied on the web and then is dried using a flow of hot air. The wet lamination is used when a paper or cardboard layer are bonded with another layer of fims/aluminium foil/paper
In wet lamination the adhesives used are only water base
Most used coating methods Common products
SOLVENT LESS
It is a 100% adhesive deposit between the two layers using a special formulation of adhesives.
For film/film and film/aluminium foil laminations are used two components adhesives
( bonding agent + additive)
When paper to film or paper to paper a single component adhesive is used
The application method is called 5 rolls system where the steel roller are heated to certain temperature suggested by the adhesive makers.
No any drying is needed due to fact that adhesive are 100% solid deposed onto the web.
This method is became in the latest year the most used laminating methid for most of the food packaging applications.
Application method Common products
HOT MELT LAMINATION
It is so called because the bonding between two or more layers occurs after that a hot melt is applied onto the web and immediately bonded with another layer.
The hot melt applying method is mostly semi flexo sometimes gravure is also used, in both cases the coating cylinder and the nip rollers are heated and immediately after the lamination the two layers are chilled with big drums where inside there s a flow of chilled water
EXTRUSION COATING LAMINATION
The extrusion coating lamination It is so called when an extruded polymer (mono extrusion) or mix of them (coextrusion) is deposed in between two layers being and bond them together
