| Résumé : |
Two-part polyurethane elastomer materials, such as polyols and isocyanates, continue to grow in formula variations and are expanding their use with product manufacturers due to their improved performance over other materials. One current example of formula growth is the development by many chemical manufacturers of green, eco-friendly, bio-based, sustainable polyurethanes as an alternative to petrochemical-based products. In many cases, these new formulations affect the design of meter/mix/dispensing equipment.
When compared to epoxies, silicones, polyesters and methacrylates, reactive cure polyurethanes for low-pressure dispensing have unique characteristics, such as faster cure, change ratio to adjust durometer, and increased resistance to external issues and influences. Reactive cure polyurethanes are sometimes used to replace one-part, heat-cure polyvinyl chloride (PVC), two-part epoxies, two-part silicones, two-part polyesters and other materials. One example is two-part, fast-cure polyurethane replacing heat-cure PVC in the filter industry for durometer control, increased resistance to chemicals and high-speed manufacturing.
Two-part polyurethane elastomers have characteristics that usually cause meter/mix/dispensing systems to differ from dispensing systems for other materials. The two-part polyurethane equipment usually needs to include different supply units, temperature control, degassing equipment, air dryers and unique mixers. In addition, the use of reactive polyurethane typically requires precision dispensing systems. Tight ratio tolerances and precise dispense volumes are often more important with fast-cure urethane and high-speed automation applications. |
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Meter/mix/dispensing for polyurethane elastomeres in ADHESIVES & SEALANTS INDUSTRY (ASI), Vol. 19, N° 9 (09/2012)
