Polyurethane (PUR) Jacket Material Overview

Polyurethane (PUR) - Thermoplastic Elastomere

Polyurethane has become increasingly important in the cable industry over the past years. This material shows at certain temperatures and 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 jacket 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-matte (low adhesion)

• PUR matte (rough surface, low adhesion)

• PUR flame protected

• PUR halogen-free and flame protected

Mechanical Characteristics of PUR Cables

The insulation materials of the cables are usually not subject to high mechanical stress. Jackets, 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 magnified when the cable is stretched during flexible use. Compressive stress caused by crushing 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

• flexibility at low temperatures

• impact resistance

Chemical Characteristics

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 during storage in water

• good resistance against alcohol-free benzine

• 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. Discoloration by sunlight is possible, but this will not affect performance.

Technical Data and Features of PUR Jacket Material

VDE abbreviation of PUR:	11Y
Temperature range of PUR (flexible):	-40°C / +90°C
Temperature range of PUR (static):	-50°C / +90°C
Flame retardance of PUR:	good
PUR Tensile strength:	25 N/mm²
Elongation at break of PUR:	400%
Abrasion resistance of PUR:	very good
PUR Dielectric constant:	approx 6.0 at 800 Hz
Specific resistance of PUR:	10¹² Ohm x cm
PUR Break-down-voltage:	20 kV/mm
Radiation resistance of PUR:	5 x 10⁷ cJ/kg
Halogen-free:	yes

Where are PUR cables used?

PUR cables are often used for control devices, e.g. machine tools, assembly lines, conveyor systems and production lines, machine and plant construction, conveyor technology (e.g. lifting platforms and transport systems), automotive industry, handling and automation technology, iron, steel and chemical industry, electric tool construction (e.g. lawn mowers, edge trimmers, hedge trimmers), in brick and cement works, electric hand tools (e.g. drills, angle grinders and other electric tools), industrial paint shops, water treatment plants, automotive and coal, iron and steel industry.