Polyolefin Flame Retardant Composition Using Fine Magnesium Hydroxide
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Solution Overview
Problem
Current polyolefin-based flame retardant compositions for wires and cables face challenges in achieving high flame retardant properties while maintaining mechanical and electrical properties, processing performance, and meeting stringent safety standards, particularly in generating a strong char that does not fall off during fire tests, which is essential for higher CPR classifications.
Innovation Solution
A polyolefin composition comprising ground magnesium hydroxide with a predefined particle size distribution (1.5 to 5.0 µm) and silicone fluid or gum, which provides excellent flame retardant properties, strong char formation, and improved processability, allowing for extrudable flame resistant applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high amounts of flame retardant additives like aluminium hydroxide and magnesium hydroxide are used to reduce flammability, then flame retardant properties are improved, but processability and mechanical properties deteriorate due to low extrusion temperature and highly viscous melt
Solution Approach 1:
The patent changes the particle size parameter of magnesium hydroxide from conventional large sizes to fine ground particles with D50 of 1.5-5.0 µm. This parameter change allows the flame retardant additive to disperse more uniformly in the polyolefin matrix, reducing melt viscosity and improving processability while maintaining high flame retardant effectiveness at lower loadings (30-65 wt%).
Solution Approach 2:
The patent creates a composite material system combining polyolefin with finely ground magnesium hydroxide and silicone fluid or gum. This composite approach allows the silicone components to act as lubricants and dispersants, further improving processability and mechanical properties while the fine Mg(OH)2 particles provide superior flame retardancy. The synergistic interaction between components resolves the contradiction between flame safety and manufacturability.
2Object-affected harmful factors
If high loadings of flame retardant fillers are used to achieve flame retardancy, then combustion properties are improved, but cable production speed decreases due to high viscosity
Solution Approach 1:
The patent applies parameter change by reducing the particle size of magnesium hydroxide to D50 of 1.5-5.0 µm, which fundamentally alters the rheological behavior of the compound. The fine particles create less friction and lower viscosity in the melt, enabling faster extrusion speeds and higher production rates while maintaining effective flame retardant loading levels.
Solution Approach 2:
The patent introduces silicone fluid or gum as an intermediary substance that mediates between the flame retardant filler and the polyolefin matrix. This intermediary reduces interparticle friction and improves melt flow characteristics, allowing high filler loadings to be processed at high speeds without sacrificing either flame retardancy or productivity.
3Reliability
If conventional flame retardant compositions are used to meet safety standards, then flame retardancy is achieved, but char strength is insufficient causing char to fall off during fire tests
Solution Approach 1:
The patent develops a composite formulation where finely ground Mg(OH)2 works synergistically with silicone fluid or gum to form a strong, adherent char layer. The fine particles create a more uniform and denser char structure, while the silicone components contribute to char integrity and adhesion to the underlying polymer, preventing char dropout during fire testing and enabling higher CPR classifications.
Solution Approach 2:
The patent changes the physical state and distribution parameters of the flame retardant system by using ultra-fine ground magnesium hydroxide. This parameter change enables the formation of a continuous, cohesive char network rather than discrete particle aggregates, significantly improving char strength and adhesion while maintaining flame retardant effectiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves outstanding flame retardant performance with no harmful gas emissions, maintaining mechanical properties and processing efficiency, enabling the use of polyolefin-based materials in higher CPR classes and ensuring functionality after a fire by forming a protective char layer.
Implementation Method 1
flame retardant additives like aluminium hydroxide and magnesium hydroxide which decompose endothermically at temperatures between 200 and 600°C, thereby liberating inert gases
Implementation Method 2
the composition achieves outstanding flame retardant performance with no harmful gas emissions, maintaining mechanical properties and processing efficiency, enabling the use of polyolefin-based materials in higher CPR classes and ensuring functionality after a fire by forming a protective char layer
Data Source
AI summary
The present invention is directed to a polyolefin composition which has flame retardant and/or fire resistant properties and is suitable as flame retardant and/or fire resistant layer of a wire or cable. The polyolefin composition of the present invention comprises an polyolefin homo- or copolymer, ground magnesium hydroxide having particle size distribution D50 of 1.5 to 5.0 µm in an amount of 30 to 65 wt% based on the weight of the polyolefin composition, and a silicone fluid or gum in an amount of 0.1 to 20 wt% based on the weight of the polyolefin composition. The present invention is further directed to a wire or cable comprising one or more layers, wherein at least one layer thereof is obtained from the polyolefin composition of the present invention. Finally, the present invention is further directed to the use of a polyolefin composition of the present invention as a flame retardant layer of a wire or cable.