Desmodur® E 744

Desmodur E 744 prepolymer must be stored in tightly closed containers and protected from contamination with moisture and foreign materials, which can adversely affect processing. It will react slowly with water to form polyureas and liberate carbon dioxide gas, which may cause sealed containers to expand and rupture. Partially filled containers should be blanketed with dry nitrogen.
Storage temperatures should be maintained between 21° to 35°C (70° to 95°F). Under these conditions, Desmodur E 744 will remain clear for up to six months. Within this range, lower storage temperatures will maximize the storage life of the product.
Desmodur E 744 prepolymer must not be allowed to freeze. Exposure to temperatures less than 21°C (70°F), even for short periods of time, can result in the formation of solid material. During the winter months, appropriate precautions must be taken during shipment and storage.
Prolonged storage of solid or partially solid Desmodur E 744 prepolymer may result in the formation of MDI dimer in amounts that exceed its solubility in the prepolymer at normal storage temperatures. This can make the product unusable. If solids form because of exposure to low temperatures, it may be possible to reliquify Desmodur E 744 by heating. Use a well-ventilated oven for the minimum time necessary to render it clear. The temperature of the product should not exceed 60°C (140°F). Agitation or drum rollers are recommended to avoid excessive local heating, which will degrade the product. As a result, the remelted prepolymer may be cloudy, and the processing behavior and/or properties of the final product may be affected.
The use of drum heaters is not recommended since the excessive heating cause dimerization, loss of NCO, and increase in viscosity.Significant amounts of MDI dimer may form during the heating process. As a result, the remelted prepolymer may be cloudy, and t ... text to long! (max 2000 characters)