General: Polyurethanes are not all the same!
As with all raw materials and finished goods, there are large differences in quality here as well.
For many of its hoses, NORRES uses a special mixture called Pre-PUR®, containing an ester-polyurethane or an ether-polyurethane. Compared to many other plastics, rubber formulations and “simple” polyurethanes, the block copolymers, which consist of hard and soft Pre-PUR® segments, have superior properties. The hard segments of Pre-PUR® provide extremely high mechanical stability, while at the same time the soft segments give the material high flexibility and dynamic load capacity.
Our hoses made from Pre-PUR® raw materials differ as follows from many of the hoses commercially available:
The ether-polyurethane Pre-PUR® used in many of our hoses has the following advantages over ester-polyurethane Pre-PUR® (and also over other ester-polyurethanes):
→ longer service life
→ greater safety
→ significant added value and greater benefits
Our high-quality Pre-PUR® raw materials with special stabilizers demonstrate considerably better stability and significantly longer service life than can be obtained with many other products.
An appropriate measure of this is hydrolysis testing in water at 80°C, since the mechanism of chemical degradation of polyester-polyurethane is frequently hydrolysis of the polyester chains. Our ester Pre-PUR® is shown in Figure 1, compared with an other typical commercial ester TPU.
According to standard tests, the abrasion resistance of our Pre-PUR® polyurethanes is about two and a half to five times higher than for many rubber raw materials and about three to four times higher than for many soft PVC’s (measured at 20°C). In applications, the differences are frequently even greater, because the excellent damping and impact resilience of Pre-PUR® polyurethanes does not come into play with the standard test method.
* Engineering modifications subject to change.