Introduction to silane cross-linked polyethylene XLPE materials
1. Main uses:
Silane cross-linked polyethylene XLPE materials are mainly used for cable insulation and hot water pipes.
2. Why use silane cross-linked polyethylene?
XLPE is the abbreviation of the English name of cross-linked polyethylene. Polyethylene is a linear molecular structure that is very easy to deform at high temperatures. The cross-linking polyethylene process turns it into a mesh structure. This structure has strong anti-deformation ability even at high temperatures.
3. Cable material production is divided into one-step and two-step methods. The one-step method is to complete silane grafting and cross-linking at the same time, and the two-step method is to graft granulation first and then cross-link.
Two-step method (1): Silane cross-linked polyethylene insulation material is composed of material A and material B. Material A is polyethylene grafted with silane, and material B is a catalyst masterbatch. The weight ratio is generally A:B=95:5. Material A and material B are made by the cable material factory and sold to the cable factory. The cable factory mixes material A and material B in proportion before use, and then extrude the cable insulation core in an ordinary extruder, and then cross-link the insulation layer in warm water or steam.
Two-step method (2): Silane cross-linked polyethylene insulation material, the production method of material A is different. Vinyl silane is introduced into the synthesis of polyethylene to directly obtain polyethylene containing silane branches. This method is essentially a resin production technology and must be completed by large petrochemical enterprises. At present, DOW and BOREALIS silane materials are of this type.
One-step method (1): The traditional one-step process is to put various raw materials into a specially designed special extruder according to the ratio in the formula through a special precision metering system to complete the grafting and extrusion of the cable insulation core in one step. In this process, no granulation is required, and no participation of the cable material factory is required. It is completed by the cable factory alone. The production equipment and formulation technology of this one-step silane cross-linked cable are mostly imported from abroad and are expensive.
One-step method (2): Silane cross-linked polyethylene insulation material is produced by cable material manufacturers. All raw materials are mixed together according to the ratio in the formula by a special method, packaged and sold. There is no distinction between A material and B material. The cable factory can directly complete the grafting and extrusion of cable insulation core in one step in the extruder. This method does not require an expensive special extruder. The silane grafting process can be completed in an ordinary PVC extruder, and the labor of mixing A material and B material before extrusion in the two-step method is omitted.
The extruded product can be cured using steam or hot water, and in some cases it can be cured at ambient temperature, depending on the type of polymer used.
4. The formula of silane cross-linked polyethylene cable material generally consists of (1) base resin, (2) initiator, (3) silane, (4) antioxidant, (5) inhibitor, (6) catalyst, etc.
The compound silane on the market is a combination of silane, initiator, antioxidant, some lubricant and anti-copper agent. The one-step silane cross-linking method in the cable factory generally uses this type of compound silane.
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