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Ethylene acrylic ester terpolymers can be divided into several
product families depending on the acrylic ester type (methyl, ethyl or
butyl acrylate) and third monomer used (MAH: maleic anhydride, GMA: glycidyl
methacrylate).
See below the structure of random ethylene vinyl acetate
- maleic anhydride terpolymers obtained by high pressure radical polymerisation:
Figure 1 : Structure of random ethylene vinyl acetate - maleic anhydride terpolymers
These products are characterised by a
reactivity, crystallinity and fluidity making them easy to use and readily
compatible with the different types of other polymers and additives.
EVA can react with other functional polymers in order to create chemical
bonds which can increase final adhesion properties, heat resistance or
long term ageing properties.This is due to the presence of glycidyl methacrylate
(GMA) or maleic anhydride (MAH) groups.
Acrylic ester decreases the crystallinity of the polymer,
which in turn widens the operating window of the adhesives. It also helps
in keeping good mechanical properties. And also offer excellent thermal stability with limited viscosity change
and discoloration (when formulated with a suitable antioxidant).
Maleic anhydride increases adhesion to polar substrates
and allows the creation of chemical bonds onto substrates such as metal,
polymers, metallised products, cellulosic substrates, rubber, non woven,...
Ethylene ester acrylic
terpolymers are used in the following adhesive systems:
- In thermo-adhesive films they are used in the interior liners of automobiles.
- In hot-melts, they can be used in the formulation of packaging
and bookbinding
applications
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