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Characterization of Curing Emissions from Conversion Varnishes
Robert C McCrillis1, Elizabeth M Howard1, Zhishi Guo1
1a U.S. Environmental Protection Agency, National Risk Management Research Laboratory, Air Pollution Prevention and Control Division , Research Triangle Park , North Carolina , USA.
Journal of the Air & Waste Management Association (1995)
|January 7, 2017
Summary
This study analyzed volatile organic compounds and formaldehyde in commercial conversion varnishes. Results show high volatile content and varying free formaldehyde levels, with specific ketones, alcohols, and aromatic hydrocarbons identified as primary constituents.
Area of Science:
- Environmental Chemistry
- Materials Science
- Industrial Coatings
Background:
- Conversion varnishes are widely used in industrial applications.
- Understanding the volatile organic compound (VOC) and formaldehyde content is crucial for regulatory compliance and environmental health.
- Limited data exists on the specific chemical composition of commercially available conversion varnish systems.
Purpose of the Study:
- To quantify the total volatile content of commercial conversion varnishes.
- To determine the concentration of uncombined (free) formaldehyde in these coatings.
- To identify the primary volatile organic constituents present in the varnishes.
Main Methods:
- Analysis of total volatile content using U.S. Environmental Protection Agency (EPA) Method 24.
- Determination of free formaldehyde concentrations via sodium sulfite titration.
- Gas chromatography analysis (EPA Method 311) for identifying specific VOCs in sealers and topcoats.
Main Results:
- Total volatile content ranged from 64% to 73% by weight in catalyzed varnishes.
- Free formaldehyde concentrations in uncatalyzed varnishes varied from 0.15% to 0.58% by weight.
- Key identified VOCs included methyl ethyl ketone (MEK), butanol isomers, methyl isobutyl ketone (MIBK), toluene, ethylbenzene, xylenes, and 1,2,4-trimethylbenzene.
Conclusions:
- Commercial conversion varnishes contain significant levels of volatile organic compounds.
- The presence of free formaldehyde necessitates careful handling and emission control.
- Detailed chemical analysis provides essential data for environmental and safety assessments of these coating systems.
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