Use Nationally and In Massachusetts
TDIs are part of a family of isocyanate-based chemicals called "diisocyanates and polyisocyanates." TDIs and 4,4'-methylene diphenyl isocyanate (MDI) are the primary isocyanates, accounting for 94% of U.S. isocyanate production capacity in 1998. ARCO Chemical (247,000 metric tons of global capacity), BASF Corporation (616,000 metric tons), Bayer Corp. (929,000 metric tons), Dow Chemical (525,500 metric tons), and ICI (425,000 metric tons) are the principal global producers of MDI and TDI. They account for 80% of worldwide capacity and are the only producers of MDI and TDI in the U.S. TDIs and MDI are primarily intermediaries in the manufacture of urethane-based materials, especially polyurethane foams.
In 1996, U.S. manufacturers consumed 616 million pounds of TDIs in the production of polyurethane flexible foams (92%), rigid foam (2%), surface coatings (3%), cast elastomers (2%), adhesives and sealants (2%), and other materials (<1%).
- The primary end-uses for TDI-based polyurethane flexible foams are (in order of highest to lowest levels of demand) transportation, furniture, bedding, carpet underlay, packaging, textile, and other.
- TDI use in rigid polyurethane foam is being replaced with MDI.
- End-uses for TDI-based polyurethane surface coatings include floor and wood finishes and paints.
- Cast elastomer products made with isocyanates include gaskets, shoe soles, mechanical parts, and wheels.
- The primary end-uses for TDI-based polyurethane adhesives and sealants are construction applications, automobile production, wood binders, and shoe production.
In 1998, Massachusetts' facilities used 7.4 million pounds of TDIs. The major end-uses are for TDI in Massachusetts are polyurethane foam (79%), surface coatings (5%), spandex (11%), and adhesives and sealants (4%) (see Table 2).
The use of TDIs increased by 42% between 1990 and 1998.
- This increase is due primarily to Crest Foam Company, which reported 3.3 million pounds in 1990 and 5.9 million pounds in 1998. Crest Foam reports TDI (mixed isomers) in the manufacture of polyurethane flexible foam. Partially offsetting this increase within foam products were two facilities which reported 0.5 million lbs. of TDI in 1990, and no longer reported in 1998.
- Other uses, exclusive of polyurethane foam, increased 14% from 1990 to 1998.
Table 1 includes two sources of "output" data: MA TURA and U.S. Environmental Protection Agency (EPA), Toxics Release Inventory (TRI) data. The MA TURA database includes all non product material created by a process line prior to release, on-site treatment, or transfer ("byproduct") and the amount of toxic chemical incorporated into a product ("shipped in or as product"). The U.S. EPA, TRI database includes information on the waste materials generated by a facility after on-site treatment including: releases to air, land, and water ("environmental releases") and transfers off-site for treatment or disposal ("off-site transfers"). Outputs of TDIs, as measured by MA TURA program, decreased by 37% between 1990 and 1998.
- Byproduct generation remained relatively constant from 1990 to1998.
- Adhesives manufacturers reported 183,000 lbs. of TDIs shipped in or as product in 1990, and 0 lbs in 1998. Partially offsetting that decrease was the new reporting of 114,000 lbs. shipped by a chemical distributor in 1998.
Environmental releases and transfers of TDIs, as measured by the TRI program, dropped by 5% between 1990 and 1998. Environmental releases dropped by 73%.
- The decrease in environmental releases was led by Boston Whaler (2500 lb. in 1990, ceased operations in mid-90's) and CL Hauthaway & Sons (1400 lb in 1990, 0 lb. In 1998).
- One facility, Zeneca Resins, accounted for 67% of the off-site transfers in 1998.
The national chemical use data are from Stanford Research Institute (SRI) International, 1996, Chemical Economics Handbook, "Diisocyanates and Polyisocyanates" (Palo Alto, California: SRI). The Massachusetts chemical use data are from the Massachusetts Department of Environmental Protection (MA DEP), 1998, "Massachusetts Toxics Use Reduction Act Chemical Reporting Data" (Boston: MA DEP).