Which polyurethane (PU) materials are used for RIM technology?
Polyurethanes are called polymeric materials that are formed by the reaction of two basic components, i.e., isocyanate and prepolymer components.
Promens processes the following types of reactive systems:
|compact||1-10 mm||> 1 g/cm3||filled, unfilled; rigid and elastic|
|hard integral||>5 mm||> 0,9 g/cm3||filled, unfilled; filled with special fillers (eg. fire retardant)|
Material properties of PU-RIM systems
- Mechanical properties – depending on the type, density, filling and content of other additives, move within a large range of values. On the one hand there are hard materials with the nature of plastics, on the other soft and flexible systems with rubber character. The impact resistance accordingly ranges from brittle materials to systems with very high impact resistance, even at low temperatures.
- there are types of PU-RIM materials declared as medical harmless,
- adding PU-RIM materials to highly non-flammable types, and all types have very good electrical properties
- PU-RIM materials have a three-dimensional structure, are at least water-absorbent and have excellent chemical resistance
How do PU-RIM materials work?
- RIM – Reactive Injection
- RRIM – Reactive injection molding
- SRIM – Structural Reactive Injection
The essence of RIM technology is to spray the monomer mixture directly into the mold, where the polymer blends under specific conditions. Upon completion of the polymerization, the finished product is removed from the mold. The accompanying conditions of this process are the very low viscosity of the sprayed material at a temperature lower than the mold temperature. Unlike conventional injection molding, where the melt is injected under high pressure into a mold significantly cooler than the melt temperature, low pressure is applied to this technology. This makes it possible to produce large parts (tens of kilograms) on relatively small devices and use light forms.