LSZH stands for low smoke zero halogens, low-smoke halogen-free，this type of cable and wire emits very low amounts of smoke and emits no toxic halogens when exposed to heat. However, In order to achieve these two key elements, in the production of low-smoke halogen-free cable materials, Low-smoke zero halogens (LSZH) are heavily loaded, which also directly leads to mechanical & processing properties
Difficulties in the processing of low-smoke halogen-free materials:
1. Regular formula, LLDPE/EVA/ATH high content filled LSZH polyolefin cable compounds contain up to 55-70% ATH/MDH, As a large number of aluminum hydroxide, magnesium hydroxide, and other flame retardants to join the use of the system mobility is poor, frictional heat generation during processing leads to an increase in temperature which causes degradation of aluminum and magnesium hydroxide.
2. Low extrusion efficiency, even if you increase the speed of extrusion volume remains basically the same.
3. Poor compatibility of inorganic flame retardants and fillers with polyolefins, poor dispersion during processing, resulting in reduced mechanical properties.
4. Rough surface and lack of gloss during extrusion due to uneven dispersion of inorganic flame retardants in the system.
5.The structural polarity of the flame retardants and fillers causes the melt to adhere to the mold head, delaying the release of the material from the mold, or the small molecules in the formulation precipitate out, resulting in a buildup of material at the mold opening, thus affecting the quality of the cable.
Based on the above issues, SILIKE has developed a series of silicone additive products specifically designed to address the pain points of processing and surface quality of low-smoke halogen-free cable materials, low smoke zero halogens wire&cable compounds, or other highly mineral-filled Polyolefin compounds for wire and cable applications, providing a variety of effective solutions to these challenges.
E.g.: Silicone Masterbatch (Siloxane Masterbatch) LYSI-401 is a pelletized formulation with 50% ultra-high molecular weight siloxane polymer dispersed in low-density polyethylene (LDPE). It is widely used as an efficient processing additive in PE-compatible resin systems to improve the processing properties and modify surface quality.
Adding 0.5-2% of SILIKE silicone masterbatch LYSI-401 to the high flame retardant filling system of low smoke halogen free wire&cable compounds or low smoke zero halogens (LSZH)cable material enables wire and cable makers to maximize productivity, can improve the processing fluidity, reduce the torque, faster surface extrusion line speed without any migration, improve the surface quality of the wire and cable as well,(Lower coefficient of friction, Improved scratch and wear resistance, better surface slip, and hand feeling …) without paying a premium for unneeded functionality additives.
Usually, for Ordinary silicone masterbatch, siloxane is non-polar, and most of the carbon chain polymer solubility parameters of the difference are very large, the addition of a large number of cases may lead to the processing of screw slippage, excessive lubrication, the surface of the product delamination, affecting the surface of the products of the bonding properties of the products in the substrate dispersed unevenly and so on.
While, SILIKE’s ultra-high molecular weight silicone additives are modified by special groups, which can be selected and matched according to the different needs of silicone additives in different substrates. This series of products can play the role of anchoring in the substrate, thus better compatibility with the substrate, easier dispersion, stronger bonding, and thus give the substrate more excellent performance. When used in LZSH and HFFR systems, it can effectively avoid screw slippage and also can play a significant role in improving the accumulation of material in the mouth mold.
article source: https://www.siliketech.com/news/how-to-solve-the-processing-pain-points-of-low-smoke-halogen-free-cable-materials/
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