Applications
Desmodur E 23500 is a very low isocyanate prepolymer and may be blended with suitable diluents to formulate one-component moisture cured sealants and ultrasoft elastomers. Typical applications include flexible caulks and sealants. As with any product, use of Desmodur E 23500 in a given application must be tested (including but not limited to field testing) in advance by the user to determine suitability.
Form supplied
Yellow, viscous liquid
Specification
| Property | Test Condition | Value | Unit | Standard |
|---|---|---|---|---|
| NCO content | 3,5 | Wt. % | ||
| Viscosity (25°C) | approx. 12000 | mPa*s |
Storage
Desmodur E 23500 prepolymer must be stored in tightly closed containers and protected from contamination with moisture and foreign materials, which can adversely affect processing. It will slowly react with water to form ureas and carbon dioxide gas, which may cause sealed containers to expand and rupture. The headspace of partially filled containers should be blanketed with dry nitrogen. Storage temperatures should be maintained between 18° to 30°C (64.4° to 86° F). Within this range, a storage temperature of 25°C (77°F) will maximize the storage life of the product. Desmodur E 23500 prepolymer must not be allowed to freeze. Exposure to temperatures less than 15°C (60°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 23500 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 should form because of exposure of Desmodur E 23500 prepolymer to low temperatures, it may be possible to reliquify the product by reheating. 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. Significant amounts of MDI dimer may form during the heating process. As a result, the remelted prepolymer may be cloudy and the processing behavior and/or properties of the final product may be affected.
Storage time
Desmodur E 23500 has a shelf life of six months from the date of receipt at customer, provided the material is stored in sealed original containers at the recommended storage temperature.
