22 июля, 2015 
Malyar Acrylic resins are used for both anodic and cathodic electrodeposition. A detailed discussion of electrodeposition will not be given here. Consult Oldring et al (Vol. Ill Resins for Surface Coatings published by SITA Technology) for further details.
Acid functional acrylics neutralised with tertiary amines are used for anodic systems, whilst amine functional acrylics neutralised with acid are used for cathodic systems. As a general rule cathodic systems are preferred due to less metal ions leaving the metal, but cathodic systems are normally more expensive.
Most electrodeposition baths operate at very low solids with 10-15% being typical. This can cause bath instability problems if the neutralising agent is too volatile and evaporates whilst in the bath. Being relatively high capital cost equipment means that quality performance is required from the coating.
Inevitably, thermoset systems are used. Again care must be exercised to ensure that the crosslinking resin is compatible and stable with the acrylic resin over long periods of time in the bath. The control of pH in the bath is also critical. Any variations in conductivity of the content of the bath will be reflected in variation in the weight of the coating applied. Regular checks on conductivity, pH and solids of the bath are required. The contents of the bath are seldom changed, thus long term stability is an essential requirement of the electrodeposition systems.
Electrodeposition offers the facility to coat surfaces which are hidden from line of sight application techniques, such as spraying. Radiators are one such example, but electrodeposition can only apply the primer or base coat. Only one coat can be applied and it must be the first. The ability to deposit film in these hidden areas is known as ‘throwing power’. The more the coating penetrates these areas, the greater the throwing power of the coating. An overview of the electrodeposition process will now be considered.
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