Polyurethane primer outperforms traditional epoxy primers

Spectracron AdvantEdge HPP primer from PPG is a polyurethane primer that breaks new ground in the product category, capable of delivering greater corrosion resistance, edge performance and chip resistance than other available polyurethane and traditional two-component epoxy primers. For steel and ferrous substrates in heavy-duty equipment (HDE), general finishes and transportation applications, Spectracron AdvantEdge HPP primer offers improved performance capabilities while building new efficiency into your priming process.

How? Here we look at the benefits and explanation as to why Spectracron AdvantEdge HPP primer is different — a polyurethane primer like no other.

Competitive Overview

For years, two-component epoxy primers have been recognised as the industry standard for quality control and corrosion protection for heavy-duty equipment, general finishes and transportation applications.

The reliance on two-component epoxies by industry OEMs and their approved outsourcers has historically been driven by epoxy’s proven effectiveness in meeting industry standards for corrosion resistance, as well as their comparatively low cost and ease of use.

Polyurethane primers, meanwhile, have offered users a speedier alternative, typically with better topcoat compatibility and faster wet-on-wet application. But a trade-off was required, as polyurethane primers have traditionally offered less robust corrosion resistance.

And indeed, some coatings manufacturers began in recent years to claim that a two-component epoxy primer is the only product that can affordably achieve the long-term industry-standard corrosion-resistance requirements.

But such claims may not account for some of the limitations of two-component epoxies.

Epoxy primers are only as effective as the pretreatment regimen used before their application. If pretreatment systems are not well maintained and managed, even the most advanced primer will not function effectively.

Despite some contentions, two-component polyurethane primers can provide adequate corrosion resistance over properly pretreated surfaces. And for their application advantages, these products have gained popularity in applications where corrosion requirements are less severe.

Two-component epoxy primers require the mixing and addition of a different crosslinking component than polyurethane top coats to maximise corrosion resistance. This can increase overhead costs by forcing OEMs and their suppliers to maintain separate crosslinking-component inventories for epoxy-primer and polyurethane-topcoat chemistries.

Epoxy primers tend to be vulnerable to premature degradation when exposed to sunlight for extended periods without a top coat finish. The sun’s UV rays cause the two-component primer to continue to self-crosslink, resulting in the primer becoming brittle, chalky or prematurely faded. In extreme cases, this can result in cracking and appearance defects, requiring the application to be sanded prior to topcoat application.

In these instances, chalking and fading signal the chemical breakdown of the primer’s base resins and pigments, which ultimately appear as visible losses of colour and/or gloss. The same chemical breakdown associated with chalk and fade also can indicate a similarly negative impact on the primer’s original corrosion-resistance properties.

It points to the need for a primer that can stand up to corrosion while delivering enhanced efficiency and speed to the application process.

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