Bayflex® WR-20

Bayflex WR-20 is a solid elastomer which has a flexural modulus of 3,000 psi (21 MPa)* at room temperature. It is processed on reaction injection molding (RIM) equipment and is used for rollers, gaskets, and encapsulated windows. This system combines rapid demold times, excellent integrity at demold, improved release characteristics, and outstanding physical properties.The Bayflex WR-20 system was developed to add a weather-resistant grade to our range of window encapsulation systems. In some cases, the weatherability of this system eliminates the need for post-painting or in-mold coatings. This product is available only in black. Bayflex WR-20 is a formulated RIM system supplied as two reactive liquid components. Component A is a diphenylmethane diisocyanate (MDI) prepolymer, and Component B is a polyether polyol. As with any product, use of the Bayflex WR-20 system in a given application must be tested (including field testing, etc.) in advance by the user to determine suitability.

Component A (MDI prepolymer) must be stored in tightly closed containers and protected from contamination with moisture and other foreign substances, which can adversely affect processing. It will react slowly 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 24° and 30°C (75° and 86°F). Under these conditions, Component A will remain clear for up to six months. Within this range, lower storage temperatures will maximize the storage life of the product. Component A must not be allowed to freeze. Exposure to temperatures less than 15°C (59°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 Component A may result in the formation of MDI dimer in amounts which exceed its solubility in the prepolymer at normal storage temperatures. This can make the product unusable.If solids should form because of exposure of Component A to lower temperatures, it may be possible to reliquify the product 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 prepolymer. 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 properties of the final product may be affected.Component B (polyol) is normally shipped in 55-gallon lined steel drums. The material is hygroscopic and should be kept in tightly closed containers to prevent contamination with atmospheric moisture and foreign materials which can adversely affect processing. The headspace of partially-filled containers should be blanketed with dry nitrogen. Storage temperatures should be in the range of 15°and 43°C (59° and 110°F). Note: Component B should be agitated thoroughly prior to transfer of contents from the drum to the day tank.

* These items are provided as general information only. They are approximate values and are not part of the product specifications.a Postcured at 121°C for one hour.