Lamination adhesives are widely applied in the
flexible packaging industry and are ideal for busy packaging
environments. Their design, layers, chemical properties, film strength,
type of adhesive and bonding methods play an imperative role in
achieving unique packaging characteristics.
The performance of a laminated film adhesive depends
on the mechanical properties, ability to prevent moisture and gas
entry, ease of sealing, printability and cost. They may be rigid of
flexible.
Production Techniques
To produce the suitable package, a thin layer of
plastic materials is extruded and then bonded to another layer of
dissimilar material. Different materials are selected so as to match
various packaging properties. For example one layer may be selected to
provide high mechanical strength while the other layer may provide
great barrier and sealing properties. These materials are then bonded
using an adhesive. The co-extrusion process may involve many layers
being extruded and bonded together. The main production techniques
involve dry bonding, wet bonding, ultraviolet curing and thermal
adhesion process.
Laminating Adhesives and Applications
The laminating adhesive plays an imperative role in
bonding the laminates. In addition to its bonding ability, the
adhesive must have other superior characteristics such as chemical
(mixing ratio, shelf life and curing time), physical (density,
molecular weight, viscosity drying speed and wetting behavior) and
performance (bonding strength, resistance to environmental process,
and resistance to corrosion, adaptability and laminating conditions).
Suitability for Different Packaging Materials
Laminated film
is suitable for different packaging processes. By adding different
coextruded layers, it is possible to alter the film properties such as
decreased gas/ oxygen permeability, puncture resistant, resistance
to heat, water and solvent proofing, superior optical properties,
electrical insulation or conductivity, anti fog properties and ability
to resist oil as well as chemical attack.
3 Layer Co-Extruded Lamination Films
These are low strength films with have three layers
of 2 or 3 dissimilar materials bonded using different configurations.
For two materials the arrangement can be A\B\A or A\A\B depending on
use. Lamination Films are cheaper and provide adequate packaging for food, shampoos, snacks, detergents and edible oils.
5 Layer Co-Extruded Lamination Films
These are medium strength laminates that use special
adhesives to increase strength. They are applied in packaging
chemicals, soap, industrial products, medical and pharmaceutical
products and hot filling juices. They comprise of five different layers
of brown extrusions that are joined using adhesives. They can be
EVOH based 5 layer films. They are used to create barrier from water,
gas, aroma and flavor. They are resistance to chemicals, cracks, UV
and are easily printable. They are also used in packaging reactive
materials such as fruits and meat this can discolor the package.
Since some film prevent aroma loss, the film can be used to pack
spices, juice, toothpaste and juice. Special films also allow
packaging of pesticide and fungicides.
7 And 9 Layer Co-Extruded Lamination Films
7 and 9 layers films offer extensive advantages and
replace aluminum packaging which is expensive. The different layers
provide great sealing and properties such as oxygen, gas and carbon
dioxide barrier; transparency, odors, high strength; easy printability,
water proofing among others. They are used for packaging refrigerated
products such as meat, poultry, cheese and unrefrigerated products
such as powder milk, nuts, pet food and wine.
