Electrocoating is a widely used coatings technology offering superior performance, environmental compliance, and low total applied cost.
Environmentally Acceptable. Coatings are available with volatile organic compound (VOC) and hazardous air pollutants (HAPS) contents of 0.5 per lb per gal or less. There are several electrocoat products in use today that are HAPS-free and even some that contain less than 0.1 lbs per gal VOC.
Electrocoating minimizes solid waste generation. The closed-loop rinsing and ultrafiltration processes reduce paint loss.
Electrocoat paints containing no heavy metals are also available.
The electrocoating process reduces fire hazards because the paint is composed of 80 - 90 pct water.
Performance. Electrocoating provides complete coverage of all exposed surfaces. This total coverage capability leads to superior corrosion performance on even the
most complex part configurations with deeply recessed areas.
Material Utilization. The ultrafiltration process and closed-loop rinsing allow coating utilization to approach 100 pct. Film thickness uniformity is excellent with film builds available from <0.5 to >2.0 mils.
Operational Efficiency. The electrocoat process can be completely automated, with no direct labor required for coating application. Dense line loading leads to high productivity. Furthermore, separate programming for different shapes, sizes and line densities is not necessary.
Electrocoating does not require a dry-off oven; hence, exhaust system and air make-up needs are minimized, thus conserving energy.
Product Types. When considering electrodeposition, two technology types, anodic and cathodic, must be evaluated. Based upon the desired quality, performance, cost, and environmental objectives, electrocoat paint manufacturers can offer various formulation types. These typically include acrylics, epoxies, and hybrids.
Anodic coatings utilize a negatively charged polymer with deposition on a positively charged workpiece whereas cathodic coatings utilize a positively charged polymer with deposition on a negatively charged workpiece.
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Following is a brief overview of today's electrodeposition coatings:
- Anodic Epoxy. The most corrosion resistant anodic electrocoat which can be cured at less than 200F.
- Anodic Acrylic. A first-generation product that offers a single-coat application. Available in numerous colors and glosses, it is used for both interior and exterior applications.
- Cathodic Epoxy. The benchmark for corrosion resistance. Widely used in the automotive and automotive parts industries, it provides superior salt spray, humidity, and scab corrosion resistance. Newest lead free products offer corrosion resistance equal to prior leaded versions.
- Cathodic Acrylic.The newest product line, available in a wide range of glosses and colors, maximizes exterior durability, gloss retention, color retention and corrosion protection. These products are used as a one-coat finish in the agricultural, lawn and garden, appliance, and air conditioning industries.
Some major markets which utilize electrocoating are listed in Table I (below) and are also illustrated in the photographs on this page.
| TABLE I—Electrocoat Applications |
| Industry |
Coating Types |
| Automotive Bodies |
Cathodic epoxies for corrosion resistance |
| Automotive Parts |
Cathodic epoxies for corrosion resistance, cathodic acrylics for exterior-durable and decorative parts |
| Appliances |
One-coat, color-controlled cathodic epoxies and acrylics |
| Brass Hardware |
One-coat, clear, cathodic acrylics for hardness and clarity |
| Agricultural Equipment |
One-coat cathodic acrylics for exterior durability |
| Shelving and Metal Furniture |
One-coat, color-controlled, ultra low-VOC, HAPs-free, anodic acrylics |
| Automotive Wheels |
One-coat, color-controlled cathodic acrylics |
| HVAC Components |
One-coat, color-controlled, exterior-durable, cathodic and anodic acrylics |
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Future. Electrocoat technology has had significant advances since the first commercial installation in 1961. Equipment sophistication, new markets and products, operational efficiencies, and governmental regulations will continue to support the growing electrocoating industry.
Today, the technology continues to work towards product enhancements in areas of corrosion protection, lower cure capabilities and more dynamic physical property offerings. Current electrocoat technology can offer a tailored product approach to various industries. Examples of specialty products include the agricultural implement market where low-cure (250 - 280F) and exterior performance are required, or in the laboratory furniture market where chemical resistance is necessary.
Electrocoat research has led to previously unimaginable developments. We are now witnessing the commercialization of one-coat, high-film-build products (1-3 mils), two-coat applications, and clear coat.
Two-coat electrocoat offers the ability to build high film thicknesses of coating, leading to outstanding corrosion protection and exterior durability. Performance has been observed to exceed 2,000 hours salt spray.
Clear coats have been developed to allow an entrance into markets previously dominated by plating. Markets including hardware and bathroom fixtures have been successfully penetrated.
Future electrocoat technology development will continue to maximize performance while minimizing environmental emissions and total applied cost. HAPS-free and VOC-free systems will be used by all electrocoat market segments, without sacrificing performance. Operational efficiency and productivity benefits (resulting in lower operating costs) will continue to position electrocoat as the coating method of choice for many applications. PFD
