New PPG Coatings System Delivers Next-Level Corrosion Protection and Application Efficiency

Corrosion Prevention Gets An Upgrade

Blog tag icon INNOVATION

Many factors contribute to the development of corrosion on metal substrates, including continuous exposure to high temperatures and humidity from decades in the field, damaging pH (acid) levels, electrolytes, chemicals and the sun’s ultraviolet rays.

Regardless of the source, the economic toll of corrosion is staggering. In the most recent U.S. corrosion study, the direct cost of metallic corrosion was estimated to be around $276 billion annually, about 3.1% of the U.S. GDP.  

PPG scientists recently developed a new coil coating system that takes substrate protection to the next level by combining a durable liquid primer and a powder topcoat.

This system not only elevates the corrosion resistance performance of metal parts with an added layer of protection, but also streamlines the production process for manufacturers.

Transformers protected by coil coatings.

A Better Coil Cleaning and Coating Process

Many fabricated metal parts start with steel that has been flattened into sheets and then rolled into coils. The coils are then sent to a fabricator or manufacturer to be stamped or shaped into parts before finishing.

In coil-driven industries like HVAC, building products and transportation, it is common to use a one-step, direct-to-metal (DTM) powder coating process.

This process, however, requires that manufacturers perform a complete cleaning and rinsing of the metal so all traces of oil, lubricants, dust, dirt and contaminants are removed. Cleaning the substrate is critical to ensure good adhesion of the powder across all areas of the part.

PPG has recently developed and tested a Coil Primer Powder Topcoat (CPPT) system that eliminates the important yet laborious cleaning function for the manufacturer, saving them time and money by eliminating the need for cleaning chemicals, hazardous wastewater removal and the labor needed in the process.

Layering is the Key to More Robust Corrosion Protection

Developed by PPG scientists, the two-layer CPPT system replaces the standard direct-to-metal (DTM) powder process with the addition of a durable liquid primer basecoat.

Instead of coiled steel being sent directly to the fabricator or manufacturer, they are first shipped to a coatings applicator where they are unrolled, cleaned on both sides, coated with a primer and oven cured. The sheets are recoiled and packaged for shipment, ready for immediate fabrication and powder coating application.

The result is a more streamlined production process that increases throughput, makes compliance with environmental regulations easier to achieve, and adds an extra layer of protection with a factory-applied, baked on primer that can extend the lifecycle of the parts.

This proprietary two-coat system includes a universal urethane liquid primer, followed by a standard ultradurable polyester powder or a polyester powder with high-transfer efficiency (HTE) properties.

Polyester powders offer appealing benefits to the transformer industry with excellent UV-, humidity- and weather resistance, hardness, high first-pass build rates, flexibility and abrasion resistance.  

The HTE formulations offer additional advantages:

  • up to 85% first-pass build rates that reduce labor, material and utility costs
  • improved wrapping on complex parts for fewer rejected parts and touch-ups
  • better control of powder film thickness so less powder needed for full coverage
  • reduced energy needs with lower baking temperatures (10/350°F or 20/320°F)
  • good penetration on complex parts, shapes and recesses

PPG makes polyester powders that use TGIC (Triglycidyl Isocyanurate) or HAA (β-hydroxyalkyl-amide) as cross-linking agents.

These formulations are available in a wide range of colors, glosses, textures and special effects.

As one of the few companies in the world with solutions for every layer of protection- pretreatment, electrocoat, liquid and powder—PPG has the expertise and dedicated laboratory resources to help manufacturers integrate coatings layers for optimal coverage and a more streamlined coating application process.