Advanced Professional Modified Polymer Materials R&D Manufacturer

https://www.sunualszh.com/products/anti-cracking-lszh-sheath-compound.html

In today’s cable manufacturing industry, Low Smoke Zero Halogen (LSZH) compounds have become essential. They are designed to minimize smoke and toxic gas emissions during a fire, making them the preferred choice for high-safety environments such as subways, skyscrapers, data centers, and hospitals.

Creating LSZH materials, however, is far more complex than simply combining “halogen-free” with “flame-retardant” components. Formulation experts must carefully balance flame-retardant effectiveness, mechanical durability, and processing performance to achieve the optimal material properties.

The proportion of inorganic flame retardants in LSZH formulations is typically very high, ranging from 50% to 65%. This high content is essential for achieving effective flame-retardant performance, but it also introduces challenges, including reduced mechanical strength and increased processing difficulty.

Ⅱ. Design and Control of Flame-Retardant Properties

LSZH materials rely on a physical flame-retardant mechanism. Inorganic flame retardants absorb heat and release water vapor at elevated temperatures, which helps slow down combustion. To ensure proper performance, the formulation should meet the following standards:

Oxygen Index (LOI): ≥ 30% (higher values indicate better flame resistance)

Vertical Combustion: IEC 60332-1 / -3 compliant

Smoke Density (Ds): ≤ 150 (ASTM E662)

Halogen Acid Gas Release: IEC 60754-1 = 0

Formula Optimization Strategy:

Increase the proportion of flexible polymers, such as EBA and POE.

Use maleic anhydride-grafted copolymers to enhance adhesion.

Control the particle morphology of flame retardants to reduce material brittleness.

Introduce a small amount of cross-linking system when needed to improve creep resistance.

IV. Processing Performance Design: Enhancing Production Efficiency and Product Quality

High filler content in LSZH materials leads to increased viscosity, which can cause processing challenges such as poor flow and rough surface finish during extrusion or injection molding. Optimizing the formulation and processing conditions is essential to maintain efficiency and achieve smooth, high-quality products.