Final Report: Isocyanate-Free Solvent-Free Hybrid Resin SystemEPA Contract Number: EPD05017
Title: Isocyanate-Free Solvent-Free Hybrid Resin System
Investigators: Curatolo, Ben
Small Business: Light Curable Coatings
EPA Contact: Richards, April
Project Period: March 1, 2005 through August 31, 2005
Project Amount: $69,671
RFA: Small Business Innovation Research (SBIR) - Phase I (2005) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , Hazardous Waste/Remediation , SBIR - Waste
During this research project, Light Curable Coatings established the feasibility of preparing an environmentally friendly isocyanate-free solvent-free hybrid resin system suitable for industrial applications such as automobile refinishing, floor coatings, and aerospace applications. A proprietary approach was used to prepare hybrid resins with reactive groups for immediate cure when exposed to ultraviolet (UV) light, and additional reactive groups for cure and physical property development in the absence of UV light. The first part of the dual cure results in an immediately tack-free surface and significant properties through UV cure that allows materials to be handled for secondary operations. The second part of the dual cure continues at ambient conditions without the use of ovens or infrared radiation, at a slower rate for reduced stress and improved physical properties such as surface hardness and adhesion. This is useful in low-light areas for various applications and can provide significant surface hardness development after processes such as sanding of paint primers that could be adversely impacted if high surface hardness developed too soon. This hybrid technology represents a significant improvement over standard UV curable resins in an environmentally friendly system that is still free from solvents and isocyanates.
Characterization of UV cure rate, secondary cure rate, adhesion, impact strength, and surface hardness for hybrid resins having different ratios of functional groups allowed for the identification of preferred structures with demonstrated properties that were significantly improved over those of typical UV-curable materials. With certain ratios of the different types of functional groups in the hybrid resin system, it was demonstrated that adhesion, flexibility, and surface hardness all could be improved at the same time. It was not surprising that improved flexibility correlated with improved adhesion, but it was unusual to demonstrate such an improvement in flexibility and hardness at the same time. These properties clearly demonstrated the feasibility and value of the described hybrid resin approach, with adhesion, pencil hardness, and flexibility all significantly increased over those of conventional UV cure systems without the addition of any formulation components other than a photoinitiator required for UV cure. This information provides the basis for future formulation of these hybrid resins with other coating components such as pigments and corrosion inhibitors for full demonstration of coating performance for existing applications in automotive refinishing or aerospace applications, or formulation with appropriate fillers for evaluation of the technology as a floor coating.
An important aspect of the environmentally friendly hybrid resin system technology is that it significantly reduces the exposure of workers and communities to isocyanates, volatile organic compounds, and hazardous air pollutant materials. Because these hybrid resins do not contain hazardous components, coating applications in confined and occupied spaces should be possible without the hazards presented by conventional materials and without interfering with the logistical and operational requirements of facilities using the resins. Opportunity costs (e.g., the application of coatings during regular shifts instead of weekends or overtime shifts) can be a tremendous advantage. The fast-curing nature of these products also allows for coated parts to be put back into service or production quickly, without the need for painting at a location remote from a manufacturing line because there is no need to allow room for drying ovens and excessive ventilation.