Pigmented melamine formaldehyde crosslinked acrylic copolymer

Figure 4. Depth profile of free amine, methoxy methyl, and primary crosslink density of a 50 y thick blue pigmented melamine formaldehyde crossllnked acrylic copolymer coating that was exposed for two years In Florida. Bars on rhs of graph Indicate concentrations expected In the absence of degradation.

Sanding is carried out at this stage and, after clean-up, the final colour or top-coat is applied. There is some variation in the resin chemistry used. Alkyds crosslinked with melamine-formaldehyde are widely used for non-metallic pigmentation. Metallics are usually based on acrylics for better durability. The acrylic may be thermoset with melamine-formaldehyde or a thermoplastic lacquer (plasticised copolymer of methyl methacrylate). A thickness of about 50ftm is applied and stoved for 20 min at 130°C (lacquers receive a bake-sand-bake process for a smoother appearance). 

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