You are here:
EVALUATION OF PROPYLENE CARBONATE IN AIR LOGISTICS CENTER (ALC) DEPAINTING OPERATIONS
Citation:
Rosenthal, S. AND A. M. Hooper. EVALUATION OF PROPYLENE CARBONATE IN AIR LOGISTICS CENTER (ALC) DEPAINTING OPERATIONS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-94/176 (NTIS PB94-214681), 1994.
Description:
This report summarizes a two-phase, laboratory-scale screening study that evaluated solvent blends containing propylene carbonate (PC) as a potential replacement for methyl ethyl ketone (MEK) in aircraft radome depainting operations. The study was conducted at Oklahoma City Air Logistics Center (OC-ALC) at Tinker Air Force Base (TAFB). TAFB currently uses MEK to depaint B-52 and KC-135 aircraft radomes in a ventilated booth. Because MEK is highly volatile, many gallons vaporize into the atmosphere during each depainting session. Therefore, the U.S. Environmental Protection Agency (EPA) is supporting studies to identify effective, nonvolatile, less toxic substitutes for MEK.
The first phase of this study screened the performance of three solvent blends provided by Texaco Chemical Company. These blends contained varying concentrations of PC, n-methyl pyrrolidone (NMP), dibasic ester (DBE), and other organic solvents. The performance of each blend was compared with that of MEK, both by the paint removal time and by a visual estimate of the amount of paint removed without any visible substrate damage (removal efficiency). The best performer was PC Blend 2, which contained 25% PC, 50% NMP, and 25% DBE. This solvent blend was then compared with MEK during the second phase of this study. The Phase 2 tests measured paint removal time and efficiency, paint adhesion, flexural properties, weight change of the substrate after paint removal and hardness of unpainted substrate test panels.
Phase 2 test results revealed that PC Blend 2 performed favorably in comparison with MEK in removing paint from the fiberglass/epoxy (F/E) test panels and in subsequent paint adhesion tests, despite an indication of possible substrate damage. A preliminary economic analysis performed on PC Blend 2 estimated TAFB would save over $30,000 the first year of operation by replacing MEK with PC Blend 2. PC Blend 2 should continue to be evaluated as a substitute in the TAFB radome depainting operation. Additional qualification testing, required by the Air Force, and a full-scale demonstration project are recommended before implementation.
This report is submitted in fulfillment of EPA Contract 68-C9-0033 under the sponsorship of the U.S. Environmental Protection Agency Risk Reduction Engineering Laboratory (RREL). This report covers a period from February to September 1993 and work was completed as of September 30,1993.