Silane crosslinked cable material and its cable production methods can be divided into two steps and one step. It is considered that the difference between two steps and one step is where the silane grafting process is carried out.
The grafting process is a two-step process at the cable material manufacturer, while the grafting process is a one-step process at the cable manufacturer.
At present, the two-step silane crosslinked polyethylene insulation material with the largest market share in China is composed of the so-called A material and B material, A material is the polyethylene that has been connected with silane, B material is the catalyst master material, and its weight ratio is generally A: B = 95:5.
Material A and Material B are made by the cable factory and sold to the cable factory. After mixing material A and material B in proportion before use, the cable factory can extrude the cable in the ordinary extruder.
There is also A kind of two-step silane crosslinked polyethylene insulation material, the production method of its A material is different, in the process of synthesis of polyethylene by introducing vinyl silane directly to produce polyethylene containing silane branch chain.
This process is essentially a resin production technique that has to be done by large petrochemical companies.
The first LINKLON silane material to enter the Chinese market is A material belonging to this type.
DOW and BOREALIS silane currently fall into this category.
There are also two types of one-step silane crosslinked polyethylene insulating materials.
The traditional one-step process is to put all kinds of raw materials into a specially designed extruder by means of a special precision measuring system according to the ratio of the formula to complete the grafting and extruding cable in one step.
In this process, there is no need for granulation, and no need for the participation of the cable factory, by the cable factory alone.
Another kind of one-step silane crosslinked polyethylene insulation material is produced by the cable material manufacturer, is all raw materials according to the ratio in the formula by A special method mixed together, packaged and sold, there is no A material and B material, the cable factory can directly in the ordinary PVC extruder one step to complete grafting and extrusion cable.
Whether one - step method or two - step method, the insulation layer is cross-linked after the cable is extruded.
In terms of the crosslinking method, the crosslinking which needs to be made in warm water or steam is called warm water crosslinking or steam crosslinking;
If the insulating layer can be cross-linked by placing it in a natural state for a period of time, it is called natural cross-linking.
The natural crosslinked polyethylene insulating materials are mostly made by two-step method.