Water-repellent wall paint and wood adhesive.
Additives to improve the properties of paints or concrete.
What do these products have in common? They are based on aqueous dispersions produced by emulsion polymerisation. Heidi Fraefel from Emerell explains.
Aqueous (water-based) dispersions make paint water-repellent and enhance the properties of wood adhesives and concrete. But what exactly do the terms water-based dispersions and emulsion polymerisation mean?
Dispersions are stabilised mixtures of insoluble polymers in a liquid, in this case water. Emulsion polymerisation is the chemical process used to make them. The following components are required:
- Water: the liquid component;
- Emulsifiers: to stabilise the dispersion during manufacture and use;
- Monomers: the units that make up the polymers that determine the properties of the dispersion;
- Initiators: cause the monomers to react to form a polymer chain.
How many monomers?
Emerell uses a whole range of different monomers to produce the desired polymer. These include styrene, VeoVa monomers, 2-Ethylhexyl acrylate, butyl acrylate, methyl methacrylate and methacrylic acid. Different emulsifiers are also used: PVA, anionic or non-ionic.
The manufacturing process runs as follows: The water and emulsifiers are heated to the desired temperature in the reactor before the initiator and monomers are added. After dosing, physical (evacuation) or chemical treatment (redox initiators) can be used to reduce residual monomers. Then the dispersion is allowed to cool before various additives are introduced to make the finished product.
Manufacturers don’t necessarily need synthetic substances to make an emulsion. Nature has given us milk, and humans have come up with emulsions such as mayonnaise and whipped cream where egg white or milk fat serve as natural emulsifiers.
Emerell specialises in manufacturing water-based dispersions used in industries including paints and varnishes and construction. It’s possible to produce small amounts (a few hundred kilograms a year) or quantities up to a whole rail tanker delivery.
A pilot amount (50 and 100 kilos) is used to test formulas to make sure the dispersions have the desired properties, and can also be used to manufacture small quantities on a commercial basis.
Once the formulas have been tested, the firm’s 1m3, 3m3, 5m3 and 15m3 production facilities come into play to make larger quantities for the market, subsequently loaded into containers such as IBCs, barrels or storage tanks.