According to Delta Tecnic, a good choice of masterbatch for the cable jacket multiplies its durability

Barcelona, November 23, 2023 — In the world of cable production, the jacket is a crucial element. This is the layer that surrounds the outer layer of a cable, and its choice can make a difference in the durability and performance of the final product. Delta Tecnic, a leading manufacturer of colour masterbatch, ensures that the right choice of masterbatch can make a big difference in the jacket’s resistance and multiply the useful life of the cable.

If we imagine a power cable with three copper conductors inside, we find three internal layers of insulation. However, the outer layer, the jacket, is the one that interacts directly with the environment. It is what gives the cable its resistance to external factors, such as friction, weather conditions, and is largely responsible for exposure to fire.

It’s important to note that a cable that doesn’t have a good jacket may fail prematurely, directly affecting its useful life. A cable can fail after one or two years of life outdoors, although with proper use of sheath materials it is possible to extend the useful life up to 25 years. This is how fundamental the cable jacket is with regard to durability and resistance.

To guarantee proper friction behaviour, polymers such as TPU (thermoplastic polyurethane) are used. This choice is essential when the cable is expected to face constant friction due to movement, installation in the ground, or use in moving mechanisms. In this context, the masterbatch acts as an additive that adds pigments and specific properties to the polymer, which can make a big difference in the jacket's resistance to friction.

Another critical aspect is fire resistance. Some cables must maintain good fire behaviour and avoid the emission of toxic fumes when burned, as well as reduce dripping during combustion as much as possible. For these cases, special compounds with the abbreviation HFFR (halogen-free flame retardants) are used. The choice of masterbatch for the addition of colour is equally important, as a masterbatch designed for this application can significantly improve the fire behaviour of the cable.

Medium voltage cables, especially those exposed to the open air, such as red or black ones, must have carefully selected jacket materials to ensure durability and resistance to the environment. Red cables must use a masterbatch with pigments that maintain the colour and are resistant to light (lightfastness) and climatic conditions (weathering). For medium voltage cables, materials such as XLPE (cross-linked polyethylene) and PVC are commonly used.

In the case of black jackets, which are widely used in the cable industry, it is important to protect the polymer from degradation caused by exposure to light and weather conditions. In order to do this, black masterbatches are used that contain a high concentration of special carbon blacks with small particle size, less than 20 nanometers. Carbon black acts as a UV filter, protecting the polymer from degradation caused by sunlight, given that it is responsible for the absorption of the emitted UV radiation.

When the jacket cannot be black in colour, special masterbatches are used. These must be designed with pigments that do not fade and must include ultraviolet filters and light stabilisers, known as HALS (Hindered Amine Light Stabilisers). The precise selection of these components is essential to ensure that the polymer does not degrade from sun-exposure and to prevent discolouration outdoors over time.

Delta Tecnic stands out for its experience studying the behaviour of pigments outdoors and their interrelation with the polymers used in the cable jacket.

It is important to highlight that good pigment behaviour is influenced by the polymer used in the manufacture of the cable. Their commitment to selecting the right pigments for each type of polymer ensures that cables maintain their colour and outdoor resistance at the most efficient cost possible. In addition, Delta Tecnic uses the same polymer in the jacket as in the manufacture of the masterbatch, ensuring that there is no interference in mechanical properties or behaviour when coming into contact with fire, which is very important in such an event.

The choice of a suitable masterbatch and careful consideration of materials are key elements in ensuring longevity and safe performance of the products. Investing in quality and durability when choosing a cable jacket is essential to ensure reliable operation over time.

***