Ethylene-vinyl acetate

• Ethene
• Vinyl acetate

Fixed

With ethylene vinyl acetate ( EVA abbreviation ) a group of copolymers is called. Other spellings, terms or abbreviations are ethylene / vinyl acetate, ethylene vinyl acetate, EVA, E / VA (according to DIN 7728, Tl 1, 01/ 1988), and ethyl vinyl acetate or PEVA (polyethylene vinyl acetate ). The abbreviation E / VAC, which is occasionally found, refers to the molding compound standard DIN EN ISO 1043-1.

Chemical and physical properties

EVA is available as granules, an aqueous dispersion, powder, but also as a film material. The resin has a high heat and good resistance to aging.

PREPARATION AND USE

The process for preparation of EVA largely corresponds to the for the preparation of LDPE. However, the properties and applications can be greatly with the amount of copolymerized vinyl acetate ( VA) varied. VA -Shares up 7% are almost exclusively for the improvement of properties (in particular increasing the elongation at break) used by PE films. About half of the EVA production eliminates this.

EVA with a VA content of 7 to 18% is often used as the sole material for special applications. Examples are cold- resistant pull-out spout of canisters, film for agriculture and horticulture, shrink wrapping ( office supplies, solar panels ), shower curtains, flooring, roofing membranes, and electrical cable.

Any further class of EVA with up to 28% VA is primarily used as a hot melt adhesive, which in turn can be used in very high-quality tufted carpet or needlepunch fabrics for fiber bonding or in book production for perfect binding.

In the photovoltaic solar cells in EVA are embedded. Here, the films used in EVA is melted at temperatures of about 150 ° C., is clear and three-dimensionally crosslinked. After cooling, then there is a permanent bond to protect the cells against environmental influences.

EVA micropellets may be used in some types of toothpaste, in order to improve the cleaning properties.

In VA contents of 30 to 90 % produced a rubber-like elastomer, for which the term EVM has naturalized (DIN ISO 1629:1995 ). It is mainly used for shoe soles or as polyblend along with other elastomers.

At 100 % VA polyvinyl acetate formed ( PVAC ).

EVA market

The European market for EVA has currently (2007) a capacity of about 600,000 tonnes. The world's largest submarket is just under 400,000 tonnes per year for products with a VA content of less than 18 %. These are just under 200,000 t EVM products produced annually in Europe. However, the EVM quantities in Asia for the local shoe industry are still significantly larger.

The largest providers are in order of market share, ExxonMobil, Versalis, Arkema, Repsol, DuPont and Total.

Some trade names are Green Flex, Levapren, Evathane, Elvax, Ultrathene (U.S.), Miravithen, Phylon.