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Ethylene vinyl acetate (EVA)
0.75-4 usd/kg
Polymerising polyethylene with vinyl acetate (EVA) produces a very tough, rubber-like, semi-opaque thermoplastic with a relatively low upper working temperature. The vinyl acetate content is adjusted, according to the application, and as a result a range of properties can be achieved. EVA is utilised in moulding, extrusion, films, coatings, adhesives and foams.
Its inherent flexibility and toughness, combined with plasticiser-free chemistry, means it presents an attractive alternative to polyvinyl chloride (PVC) and polyurethane resin (PUR), in some cases.
As a thermoplastic, it is relatively easy to recycle with melt-processing techniques, such as compounding and extrusion. The difficulty with EVA is that it is often combined with other materials, and used as an adhesive interlayer, which makes it challenging, if not impossible, to recycle.
Sustainability concerns
Non-renewable ingredients
Raw material generates polluting by-products
Low circularity potential
Microplastics
Hot melt adhesive and sealant based on ethylene vinyl acetate (EVA) is predominantly used in packaging, automotive (door trims and headliners), furniture, textiles (bonding shoes, mattresses and fabrics, for example), appliances (white goods) and general industrial assembly. They are used a great deal in packaging, specifically for bonding paper and card, such as labelling, sealing, laminating (corrugated card for example) and box assembly.
As a hot melt, it is solvent free, and so emits no volatiles (VOC), making it very easy to work with. It sticks well to many plastics, glass, paper, wood and metal. Set time is very rapid, typically around 1 second. A higher vinyl acetate content helps to slow this down, if needed.
The ratio of vinyl acetate content is specified according to the application. For example, whereas higher levels of ethylene enhance strength and stiffness, increasing vinyl acetate improves adhesion with paper and makes it softer and more resilient at lower temperatures.
There are several other types of thermoplastic hot melt adhesive. PP-based hot melt provides improved adhesion across a broader temperature range and are typically formulated to bond well to polypropylene (PP) and polyethylene (PE), which are notoriously challenging to work with. Polyamide (PA), nylon hot melts are more expensive, and provide higher temperature performance, up to around 150 degC.