Coated Aluminum Hydroxide in Polymer Compositions
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Solution Overview
Problem
Current flame retardant polymer compositions face challenges in achieving good flame retardancy, processability, and mechanical properties, particularly in fulfilling the FIPEC test requirements and maintaining surface quality, while avoiding the drawbacks of halogen and phosphorous-containing compounds and the deterioration of mechanical properties due to high inorganic filler content.
Innovation Solution
A flame retardant polymer composition comprising a polar ethylene copolymer with alkyl acrylate comonomer units and coated aluminum hydroxide as an inorganic filler, which provides improved flame retardancy, extrudability, and mechanical properties without halogen- and phosphorous-containing compounds, and meets the FIPEC test standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If relatively large amounts of inorganic fillers (50 to 60 wt.%) are included to improve flame retardancy, then flame retardancy is improved, but processability and mechanical properties deteriorate
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the inorganic filler particles and the polymer matrix. The coupling agent chemically bonds to both the inorganic filler surface and the polymer, creating a bridging interface that improves stress transfer and reduces filler-polymer incompatibility. This mediator allows higher filler loading (60-70 wt.%) without the severe processability and mechanical property deterioration that would normally occur at such high filler concentrations.
Solution Approach 2:
The invention creates a composite material system consisting of three components: inorganic filler particles, polymer matrix, and silane coupling agent at the interface. This composite structure leverages the flame retardancy of the inorganic filler while using the coupling agent to maintain the mechanical integrity and processability of the polymer matrix, achieving a balance between flame retardancy and mechanical properties that cannot be obtained with simple filler-polymer mixtures.
2Reliability
If relatively large amounts of inorganic fillers (50 to 60 wt.%) are included to improve flame retardancy, then flame retardancy is improved, but mechanical properties deteriorate
Solution Approach 1:
The silane coupling agent serves as a mediator that chemically bridges the inorganic filler and polymer matrix, ensuring effective stress transfer from the polymer to the filler particles. This prevents filler particles from acting as stress concentration points that would initiate failure, thereby maintaining mechanical strength even at high filler loadings of 60-70 wt.% that provide superior flame retardancy.
Solution Approach 2:
The invention develops a composite material where the silane coupling agent creates a tri-phase system (filler-coupling agent-polymer) that optimizes both flame retardancy and mechanical properties. The coupling agent forms an interfacial layer that enhances the composite's overall strength while the high inorganic filler content provides the desired flame retardancy, resolving the contradiction between these two properties.
3Reliability
If halogen-containing compounds are used as flame retardants, then flame retardancy is improved, but hazardous and corrosive gases are liberated upon burning
Solution Approach 1:
The invention replaces halogen-containing flame retardants with inorganic filler-based flame retardancy mechanisms. Instead of relying on halogen chemistry that produces toxic gases, the system uses the endothermic decomposition and inert gas release of inorganic fillers (such as aluminum hydroxide or magnesium hydroxide) to achieve flame retardancy. This converts the harmful halogen-based mechanism into a beneficial inorganic mechanism that suppresses flames without generating corrosive or toxic gases.
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 effectively passes the FIPEC test, demonstrating excellent flame retardancy, processability, and mechanical properties, with improved surface quality and reduced flame spread, while being free or low in halogen and phosphorous compounds, thus addressing the limitations of existing materials.
Implementation Method 1
inorganic fillers such as e.g. hydrated and hydroxy compounds, which during burning decompose endothermically and deliberate inert gases at temperatures in the range of 200 to 600°C
Implementation Method 2
The flame retardancy of such compositions is based on synergistic effects between these three components which in case of burning lead to the formation of a physically and firmly stable char layer that protects the polymer from further burning
Data Source
Figure 1
AI summary
The present invention relates to a flame retardant polymer composition comprising (A) a polar ethylene copolymer comprising alkyl acrylate comonomer units, (B) coated aluminum hydroxide as filler material to an article, in particular a wire or cable, comprising said flame retardant polymer composition, and to the use of said composition for the production of a layer of a wire or cable. The invention is furthermore directed to a process for producing a flame retardant polymer composition.