Final Report: Chromium-Free Corrosion-Resistant Hybrid UV Coatings

EPA Contract Number: EPD10057
Title: Chromium-Free Corrosion-Resistant Hybrid UV Coatings
Investigators: Curatolo, Ben
Small Business: Light Curable Coatings
EPA Contact: Richards, April
Phase: II
Project Period: May 1, 2010 through April 30, 2012
Project Amount: $224,998
RFA: Small Business Innovation Research (SBIR) - Phase II (2010) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Pollution Prevention

Description:

This research project demonstrated robust performance properties for an environmentally friendly chromium-free solvent-free hybrid ultraviolet (UV) coating system suitable for applications such as industrial, automotive, and aerospace corrosion resistance. In particular, an appropriate segregation of components was demonstrated for a two-part, chromium-free, corrosion-resistant hybrid UV coating system that provided excellent protection for 2024-T3 aluminum alloy panels, with scribe lines remaining shiny through 3,000 hours of ASTM B-117 salt fog testing. This hybrid UV coating system contained an appropriate ratio of reactive groups to provide immediate cure when exposed to UV light, along with a secondary cure mechanism that was active in the absence of UV light. Coatings demonstrated the ability to be masked with tape immediately after UV cure and de-masked later without marring. This system also demonstrated a suitable rate of cure in the absence of UV light to dry overspray to reduce the possibility of contamination from spray painting operations. Important advantages of this proprietary technology include: improved efficiency for painting operations; and the potential to significantly reduce exposure of workers and communities to hexavalent chromium, isocyanates, volatile organic compounds (VOCs), and hazardous air pollutants (HAPs).

Summary/Accomplishments (Outputs/Outcomes):

The two-part, chromium-free, solvent-free hybrid UV coating system was characterized with respect to UV cure rate, secondary cure rate, adhesion, surface hardness, solvent resistance and corrosion resistance. The hybrid UV coatings became tack-free immediately upon exposure to UV light, and instantly demonstrated good adhesion and hardness properties. Coatings demonstrated the ability to be masked with tape immediately after UV cure and de-masked later without marring. The coatings exhibited good solvent resistance as evidenced by resistance to more than 200 double rubs with methyl ethyl ketone (MEK), and the coatings also maintained their integrity and hardness after a 24-hour soak in Skydrol hydraulic fluid. Two-part gray hybrid UV coatings containing a chromium-free corrosion inhibitor were applied to duplicate 2024-T3 aluminum alloy panels, cured, scribed and placed into ASTM Test Method B-117 salt fog testing to demonstrate corrosion resistance. After 3,000 hours, the scribe lines were still shiny for numerous hybrid UV coating formulations.

Conclusions:

This Phase II SBIR project demonstrated robust performance for a new proprietary two-part hybrid UV coating system that incorporated a chromium-free corrosion inhibitor and a secondary cure mechanism into a UV curable coating to enhance the capabilities of the system. The first part of the hybrid cure system resulted in immediate tack-free surfaces and significant properties through UV cure, which allowed coated materials to be handled for secondary operations. The second part of the dual cure continued at ambient conditions without the use of ovens or infrared radiation, at a slower rate for reduced stress and improved physical properties, including surface hardness. The enhanced capabilities of this solvent-free hybrid UV coating system included chromium-free corrosion resistance as well as appropriate adhesion, surface hardness, solvent resistance and the ability to cure in the absence of UV light to dry overspray to reduce the possibility of contamination from painting operations. Together, with the environmental and performance advantages of UV curing, incorporation of a chromium-free corrosion inhibitor and appropriate functional groups for secondary cure extended the applicability of this hybrid system to numerous industrial, automotive and aerospace applications requiring corrosion protection. This two-part, chromium-free, corrosion-resistant hybrid UV coating system demonstrated robust properties appropriate for corrosion protection in important markets representing major infrastructure of the United States, including vehicles, bridges, storage tanks and piping.
 
Anticipated benefits of this technology include improved environmental friendliness, efficiency and productivity capabilities. Because this hybrid resin system contains safer components, application in confined spaces and occupied spaces should be possible without the hazards presented by conventional materials. Environmental savings apply not only in production but also throughout and beyond the operational lifecycle of vehicles and industrial products by reducing environmental risks associated with maintenance, storage and disposal. In addition to the known environmental and efficiency advantages of standard UV technology, this hybrid system offers additional advantages, such as the ability to cure overspray to reduce the possibility of contamination from spray operations. This technology offers a significant positive societal impact in terms of a better quality of life for industrial workers and for citizens through safer workplaces and a cleaner environment.

Supplemental Keywords:

solvent-free paint, 100 percent solids, green, sustainable, cleantech, clean technology, VOC-free, HAP-free, isocyanate-free, chromium-free


SBIR Phase I:

Chromium-Free Corrosion-Resistant Hybrid UV Coatings  | Final Report