Polyurethan (PUR) - thermoplastic elastomere
Polyurethane has become increasingly important in the cable industry over the past years. This material shows at certain temperatures mechanical characteristics similar to rubber. The combination of thermoplastic and elastic characteristics has led to the description TPE thermoplastic elastomere. Here at SAB Bröckskes GmbH & Co KG, we use PUR on a Polyether base as sheath material. In addition to standard Polyurethane, thanks to constant development between SAB Bröckskes and the plastic industry, the following types of PUR are also available:
- PUR semi-mat (low adhension)
- PUR mat (rough surface, low adhension)
- PUR flame protected
- PUR halogen-free and flame protected
The insulation materials of the cables are usually not subject to high mechanical stress. Sheaths, on the other hand are heavily used. This is especially true for flexible control and connection cables which are often pulled over sharp corners and rough surfaces. This can lead to cuts which are accentuated when the cable is stretched during flexible use. Compressive stress caused by squashing and impacting from tools and machines can also occur. The most important mechanical characteristics of PUR are:
- high tensile strength
- high tear resistance
- notch resistance
- abrasion resistance
- alternate bending resistance
- impact resistance
- flexibility at low temperatures
The chemical resistance depends upon many factors such as chemical type, reaction time, temperature, volume, concentration and of course the type of Polyurethane used. In comparison with many other materials, such as rubber or PVC, PUR has a better resistance against chemical reaction. The outstanding chemical characteristics are:
- very good resistance against mineral oils
- good resistance against alcohol-free benzine
- good resistance during storage in water
- good resistance against many solvents
The danger of decomposition through microbes exists with Polyurethane on a Polyester base after prolonged exposure to dampness and warmth. The Polyurethane on a Polyether base used by SAB is resistant to microbic decomposition. Etherpolyurethane and Esterpolyurethane can be differentiated by the saponification value (VZ).
- Etherpolyurethane (resistant) - VZ ≤ 200
- Esterpolyurethane (non-resistant) - VZ ≥ 350
After prolonged exposure to warm water or tropical climates, Polyurethane on a Polyester base will undergo a chemical reaction. The result is a weakening of mechanical strength. SAB Polyurethane on a Polyether base is relatively more resistant to hydrological break-down.
Etherpolyurethane is weather and ozone resistant in all climates. Discolouration by sunlight is possible, but this will not affect performance.
Exemplary applications of PUR cables
For control devices, e.g. machine tools, flow and assembly lines, conveyor systems and production lines, machine and plant construction, conveyor technology (e.g. work platforms and transport systems), automotive industry, handling and automation technology, iron, steel and chemical industry, (Eg drills, angle grinders and other electrical tools), industrial paint shops, water treatment plants, steel, automotive, mining ...
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