Aqueous radiation curing systems have been presented and discussed with increased frequency for the past 20 years. However, only recently has there been market acceptance for such systems, both industrial coating applications, e.g. UV coatings for parquet primers 1), and graphic arts applications. The aqueous radiation curable systems described here are water-soluble, water-reducible 2), water-dispersible 3), latex- based 4) and hybrids of all previously mentioned types, the majority of which are capable of free radical polymerisation, although cationic polymerisation has also been reported 5). In view of the wide range of different chemical approaches employed, the main characteristics, the advantages and disadvantages, are also expected to vary widely. Nevertheless, they all aim to develop:

- VOC free systems with extremely low viscosity (e.g. for sprayable applications or jettable systems).
- Easy-to-obtain surface effects (e.g. matt effect) or incorporating various fillers for improving coating performance, enhancing the scope of possibilities for the formulator.
- Eliminate or reduce the need for irritant acrylate monomers (e.g. HDDA, TPGDA)

Compared with UV polyurethane dispersion and UV latex, the following advantages of externally emulsified acrylate oligomers can be mentioned:

• Direct conversion of current solvent-based UV systems to waterborne UV to meet VOC regulations
• New opportunities for hybrid systems (e.g. acrylic/UV acrylate, alkyd/UV acrylate, PUDs/UV acrylate)
• Greater availability of raw materials and a high degree of freedom for the formulator compared with UV PUDs and UV latex
• One disadvantage of the emulsions compared with UV PUDs is the non tack-free film after water flash-off

This paper presents a new method for making externally emulsified acrylate oligomers for UV/EB curing using an amphiphilic dendritic polymer. Thanks to its non-ionic polymeric structure and large hydrophobic/lipophilic balance, the dendritic emulsifier is believed to be a versatile emulsifier for a number of binder systems, including radiation curable acrylate oligomers, as well as contributing to the coating properties, unlike conventional emulsifiers which are often considered as detrimental to the coating performance.

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