Regulations (Preambles to Final Rules) - Table of Contents
• Record Type: Occupational Exposure to 4,4' Methylenedianiline (MDA)
• Section: 4
• Title: Section 4 - IV. Physical Properties, Manufacture, and Uses of MDA

IV. Physical Properties, Manufacture, and uses of MDA

Methylenedianiline (CAS 101-77-9) (MDA) is a light brown, or tan, crystalline solid with a faint amino-like odor. MDA is slightly soluble in water and very soluble in alcohol and benzene. MDA is produced commercially by the condensation of aniline and formaldehyde. Crude MDA (40-60 percent MDA) is a liquid or a hard wax-like substance. Purified (99 percent) MDA is in the form of either light yellow crystalline flakes or white granules.

Ninety-eight percent of the MDA produced is used directly in the manufacture of methylenediphenyl diiosocyanate (MDI). The remaining two percent is used as a precursor for the manufacture of plastic fibers, antioxidants, dyestuff intermediates, corrosion preventatives, and special polymers.

The MDI is produced in two grades, monomeric (pure) and polymeric. Ninety percent of the crude MDA is used to produce polymeric MDI, and another 8 percent of the crude MDA is converted to monomeric MDI. MDI is used to produce flexible and rigid polyurethane foams, elastomers, coatings, thermoplastic resins, foundry core binders, adhesives, sealants, and spandex fibers.

The remaining MDA is produced in the pure form for other uses: epoxy resin curing agents, wire coating applications, polyurethane co-reactants, in pigments and dyes, and defense applications.

There are eleven principal industry sectors where workers are potentially exposed to MDA. These sectors are: (1) MDA Production for MDI Synthesis/MDA Sale and Import; (2) Reprocessing; (3) Filament Winding; (4) Potting and Encapsulation; (5) Molding/Bonding of Tools and Specialty Small Parts; (6) Wire Coating; (7) Application of Coatings; (8) Intermediate for TGMDA and PACM-20 Production; (9) Polyurethane C