Emissions of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate from latex paint
Latex paints constitute over 70% of interior architectural coatings in the United States. This dissertation is focused on one component of latex paint, 2,2,4-trimethyl-1,3-pentadediol monoisobutyrate (TMPD-MIB). Four substrates (gypsum board, plywood, concrete-A and aluminum) and two simplified latex paints (high and low pigment volume concentrations- HPVC and LPVC) containing TMPD-MIB, but no glycols, were employed. Commercial Nippon paints (flat, semi-gloss, and gloss) containing TMPD-MIB and propylene glycol were also tested for concrete-B and gypsum board specimens. Short- and long-term emissions of TMPD-MIB following paint applications were studied. Emissions were observed for periods as long as 16 months, but were relatively low after 150 hours. For similar times after paint application, the mass recoveries for TMPD-MIB in air for porous materials, such as gypsum board and concrete, were significantly lower than aluminum specimens. Recovery of TMPD-MIB in air for HPVC paint was generally greater than that for LPVC paint, likely due to enhanced diffusion through the more porous HPVC paint film. For gypsum board, the relative distribution of TMPD-MIB mass between air and substrate components was also determined. The contribution of TMPD-MIB emissions from the wet film was generally small relative to the integrated long-term emissions from the dry film. TMPD-MIB was recovered in the dried paint film and gypsum board with 96 ± 6% mass closure. Gypsum board appears to serve as a long-term reservoir of TMPD-MIB, which diffuses into the body of the gypsum board and adsorbs to calcium sulfate. A mass balance model was developed to predict room-scale TMPD-MIB concentration based on small-scale chamber results. Reasonable increases in room or building air exchange rate can reduce TMPD-MIB concentrations to below airway irritation and odor threshold concentrations. The scope of research described in this dissertation goes beyond previous studies to quantify chemical-specific emissions from paint. Findings related to the long-term distribution of TMPD-MIB mass on gypsum board are particularly novel and significant. The results presented herein should facilitate future research related to emissions from paint.