Problem-solving polyurethanes
Canadian Plastics
Bayer Corp. has developed two new isocyanates to help processors of polyurethanes solve the problem of liquefied diphenylmethane diisocyanate (MDI) freezing during cold weather. Mondur MA-2300 isocyan...
Bayer Corp. has developed two new isocyanates to help processors of polyurethanes solve the problem of liquefied diphenylmethane diisocyanate (MDI) freezing during cold weather. Mondur MA-2300 isocyanate and Mondur PF-LT isocyanate have improved freeze stability but maintain physical and processing qualities equal or superior to Bayer’s Mondur PF modified monomeric MDI product.
Where the Mondur PF grade has a freezing point of 15C, Mondur PF-LT has a freezing point of 5C and Mondur MA-2300 has even greater freeze stability, to 0C.
“These two products are an exciting development in liquid MDI chemistry,” says Ralf Guether, development chemist for Bayer’s Polyurethanes Division. “The improvements in these materials will make many polyurethane formulations easier to store, handle and process.”
Bayer has also developed polyurethane quasi-prepolymers to facilitate the production of polyurethane elastomers, achieving excellent physical properties without the demanding processing conditions of hot-cast elastomers. Hot-cast elastomers require processing at elevated temperatures, use prepolymers that must be melted to a suitable processing viscosity and have very high mix ratios of prepolymer to chain extenders.
In contrast, Baytec MP-210 and Baytec ME-230 quasi-prepolymers are low-viscosity liquids at 25C; have favorable mix ratios; are processable at room temperature or slightly above, and can be processed using simple metering equipment.
For extrusion applications, Stephane Tetreault of Plastiques Lausa Inc. reports that a flame-retardant formulation of thermoplastic polyurethane is available. The Laripur LPR9060 grade, made by Coim S.p.A., is suitable for cabling applications. It has UL V-2 rating and is halogen-free. Another flame-retardant grade for cabling includes an anti-blocking additive for easier pulling of cables, and a matte finish.
High pressure at low cost
On the machinery front, the traditional gap between lower-cost, low-pressure equipment and more advanced high-pressure systems has been bridged. Hennecke GmbH offers its BaseLine high-pressure foaming machine at a reasonable price by emphasizing standardization and plug-and-play convenience. The BaseLine unit has a compact design with integrated tanks and temperature control devices. It also has high-pressure axial piston pumps with an adjustment range of 6:1.
Gusmer-Admiral states that its OmegaRim high-pressure RIM machine is priced to replace existing low-pressure equipment used by many manufacturers. OmegeRim has two raw material tanks, heat exchangers for temperature control, a high pressure metering system, and flow monitoring with closed loop control.
