| Résumé : |
Radiation curing equipment is beginning to enjoy a period of development. The author looks at what strides are being taken.
One of the most important demands made by users of radiation curing is the availability and reliability of equipment. The area of aquipment includes issues of running costs and ease of introduction or retro-fitting to existing coating lines.
A great step forward in electron beam curing has been the introduction of more affordable equipement, which runs at a lower accelerating voltage than earlier commercial e.b.units (J Chrusciel, Proceedings RadTech Europe Basel, 2001, 367-373). Equipment that has a lower accelerating voltage tends to benefit from greater reliability. this is because of the longer life of both the metal foil windows and the electrongun filaments. The extent to which electrons will penetrate coatings is related to the accelerating voltage and the thickness of the coating.
Penetration of thick coatings is achievable with quite modest voltages (for a 25 mm thick coating only 110 kVolts is required). Because e.b. curing is carried out under a nitrogen blanket, oxygen inhibition is not a problem, and for radical curing processes an initiator does not have to be used.
As a result, the cure occurs at ambient or slightly higher temperatures (dependent upon the thickness of the coating and the thermal conductivity of the substrate). The lack of a photoinitiator in a formulation means that the cured formulations do not contain migratable species originating from the this source. |
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Finding the right cure in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 192, N° 4451 (04/2002)
