Mondur® MB

Mondur MB isocyanate can be used in the production of solid polyurethane elastomers, adhesives, coatings, and in intermediate polyurethane products. As with any product, use of Mondur MB isocyanate in a given application must be tested (including but not limited to field testing) in advance by the user to determine suitability.

Mondur MB is available in two forms: fused solid and molten liquid.

Mondur MB isocyanate must be stored in tightly closed containers and protected from contamination with moisture and foreign substances that can adversely affect processing. Contamination can result in the formation of solids, the evolution of gas, and/or significant amount of heat. Mondur MB isocyanate will react with water to form ureas and carbon dioxide gas, which may cause sealed containers to expand and rupture. Partially filled containers should be blanketed with dry nitrogen.Dimer Formation: During storage, Mondur MB isocyanate slowly reacts to form self-condensation products known as MDI dimer. Dimer is undesirable because it is only slightly soluble in the molten product and in time will cause turbidity and/or form a solid precipitate. Dimer formation occurs in both liquid and solid Mondur MB isocyanate, and the rate of dimer formation for both is determined by the storage temperature. Therefore, storage temperature is the critical factor which determines the storage life of both solid and liquid Mondur MB isocyanate. To avoid rapid dimer formation, and a significant shortened storage life, Mondur MB isocyanate must not be allowed to remain at temperatures between 20° and 39°C (68° and 102°F). Dimer forms in solid Mondur MB isocyanate at a very rapid rate somewhat below its melting point of 39°C (102°F). If solid Mondur MB isocyanate is allowed to remain at this temperature for several hours, it can form enough dimer to become unusable. This can occur, for example, when a drum or vessel of liquid isocyanate is allowed to slowly freeze due to exposure to ambient temperature.Storage Temperature for Fused Mondur MB Isocyanate: Store fused Mondur MB isocyanate at 5°C (41°F) or lower, which will provide a storage life of about three months. At temperatures of -20°C max (-4°F max), fused Mondur MB isocyanate can be stored up to six months. Storage temperatures up to 15°C (59°F) are possible, if the correspondingly shorter storage life is acceptable. Strictly avoid the storage of solid Mondur MB isocyanate between 20° and 39°C (68° and 102°F) because the formation of dimer is very rapid at these higher temperatures.Storage Temperature for Molten Mondur MB Isocyanate: The recommended temperature range for storing molten Mondur MB isocyanate is 41° to 44°C (106° to 111°F). The reasons for this narrow range are:•The freezing point of Mondur MB isocyanate is 39°C (102°F) and it will quickly freeze at or below this temperature. Freezing drastically promotes the formation of MDI dimer.•Above 44°C (111°F) the storage life is shortened due to the formation of a solid precipitate of MDI dimer.Even when properly stored, liquid Mondur MB isocyanate has a limited storage life of only three weeks. The storage life of molten Mondur MB isocyanate is short compared to most other bulk chemicals, requiring good planning and inventory control. Covestro has extensive experience in the design and operation of facilities for the storage and handling of molten Mondur MB isocyanate. Please contact your Covestro representative for more information.Melting Fused Mondur MB Isocyanate: Melt fused Mondur MB isocyanate as quickly as possible, without overheating, to minimize dimer formation. The preferred method for melting fused Mondur MB isocyanate is to heat it in a steam cabinet while slowly rolling the drum. This method normally takes 4 to 5 hours to melt 55-gallon drums of fused Mondur MB isocyanate. Uneven heating without rolling will increase the amount of MDI dimer formation and the time needed to completely melt the material. If a drum roller is not used, some method of agitation must be employed to thoroughly homogenize the melted product. Proper ventilation must be used when melting material.A hot room (60°C to 80°C/140° to 176°F) can also be used. The time needed to melt fused Mondur MB isocyanate in a hot room depends on temperature, heat source, air circulation and the amount of material being melted. Times must be determined empirically, based on specific equipment. When melted, use the entire contents of the container, if possible. Otherwise, blanket the remaining Mondur MB isocyanate with nitrogen and store at a temperature of 41° to 44°C (106° to 111°F). Do not attempt to refreeze melted Mondur MB isocyanate.During melting, monitor the drums for abnormalities, particularly swelling, and discontinue heating should any be observed. Swollen drums are potentially dangerous and must be handled only by trained personnel. Contact Covestro's Product Safety Department for guidelines on handling swollen drums. See Material Safety Data Sheet for emergency telephone numbers.If no abnormalities are observed, open the drums of melted Mondur MB in a well-ventilated area. Appropriate personal protection equipment must be used (see Material Safety Data Sheet). Remove any moisture from the top of the drum and open the bung slowly to relieve pressure build-up that may have occurred during the melting process. If moisture contamination has occurred, do not attempt to melt the product, because the moisture will react with the isocyanate and result in a dangerous pressure build-up of carbon dioxide in a closed system. Do not use electric heating devices or any type of high temperature equipment for melting Mondur MB isocyanate. High temperatures can cause decomposition of the isocyanate and the formation of gases which can build up pressure in closed containers and cause them to rupture, possibly resulting in serious injury.Filtration of Mondur MB Isocyanate: It is possible to filter small amounts of dimer from Mondur MB isocyanate. This is typically done when no turbidity or particulates can be tolerated in the process. Contact your Covestro representative for specific filter equipment recommendations based on your processing needs.Filtration cannot solve a dimer problem. When Mondur MB isocyanate has reached the end of its storage life, indicated by a significant formation of solids, the only really satisfactory solution is to rapidly use the remaining product.