Flame Retardant Thermoplastic Polyurethane Cable Sheathing
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Solution Overview
Problem
Existing thermoplastic polyurethane compositions for cable jackets face challenges in achieving a balance between adequate mechanical properties, flame retardancy, and low smoke density, often compromising on one aspect due to high filling levels and inadequate compatibility of components.
Innovation Solution
A composition comprising thermoplastic polyurethane based on diisocyanate and polycarbonate diol, combined with ethylene-vinyl acetate copolymers, polyethylene, polypropylene, or styrene copolymers, and metal hydroxides, along with phosphorus-containing flame retardants, which enhances flame resistance, mechanical properties, and abrasion resistance while minimizing smoke density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high filler levels of metal hydroxides are used to achieve flame retardancy, then flame resistance is improved, but mechanical properties deteriorate
Solution Approach 1:
The patent introduces相容性助剂 (compatibility auxiliaries) as intermediaries between the metal hydroxide fillers and the thermoplastic polyurethane matrix. These auxiliaries improve the interfacial compatibility, allowing high filler levels (40-70 wt%) to be incorporated while maintaining mechanical properties. The compatibility auxiliary acts as a mediator that prevents filler aggregation and ensures uniform distribution, thus resolving the contradiction between flame retardancy and mechanical strength.
Solution Approach 2:
The patent creates a composite material system consisting of thermoplastic polyurethane, metal hydroxides (such as aluminum hydroxide or magnesium hydroxide), and compatibility auxiliaries. This composite structure allows the beneficial flame-retardant properties of metal hydroxides to be combined with the mechanical properties of the polyurethane matrix, while the compatibility auxiliary ensures proper interfacial bonding. The composite approach enables simultaneous achievement of flame resistance and acceptable mechanical properties.
2Reliability
If high filler levels are used to achieve flame retardancy, then flame resistance is improved, but processability deteriorates
Solution Approach 1:
The compatibility auxiliary serves as a mediator that improves the interaction between filler particles and the polymer matrix during processing. It reduces filler aggregation and improves dispersion, which enhances processability despite high filler content. The auxiliary facilitates uniform mixing and reduces viscosity increases, making the compound easier to process.
Solution Approach 2:
The patent optimizes processing parameters such as mixing temperature, shear rate, and residence time to accommodate high filler levels. By adjusting these parameters and using compatibility auxiliaries, the patent achieves good dispersion and processing characteristics even with 40-70 wt% filler content, thus improving processability while maintaining flame retardancy.
3Strength
If conventional polyols are used in thermoplastic polyurethane, then mechanical properties are maintained, but flame retardancy is insufficient
Solution Approach 1:
The patent creates a composite system where conventional polyols (such as polyesterols or polyetherols) are combined with metal hydroxide fillers and compatibility auxiliaries. This composite approach allows the polyol to provide good mechanical properties while the metal hydroxide component provides flame retardancy. The compatibility auxiliary ensures proper integration of these components, resolving the contradiction between mechanical performance and flame resistance.
Solution Approach 2:
The compatibility auxiliary acts as an intermediary that enables the combination of conventional polyols with flame-retardant metal hydroxides. It ensures proper interfacial interaction and distribution, allowing the system to achieve both good mechanical properties from the polyol and adequate flame retardancy from the metal hydroxide filler.
4Reliability
If halogenated flame retardants are used to achieve flame retardancy, then flame resistance is improved, but toxicity and corrosiveness of fumes increase
Solution Approach 1:
The patent converts the traditionally harmful approach of using halogenated flame retardants into a beneficial halogen-free system. By using metal hydroxides (such as aluminum hydroxide or magnesium hydroxide) as flame retardants, the system achieves adequate flame resistance while producing non-toxic and non-corrosive fumes upon combustion. The metal hydroxides decompose to release water vapor and leave protective residues, transforming the flame retardancy mechanism into a safer process.
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 solution provides improved flame resistance, mechanical properties, and reduced smoke density, making it suitable for cable sheathing applications with optimized property profiles and processability.
Implementation Method 1
at least one metal hydroxide
Implementation Method 2
at least one phosphorus-containing flame retardant
Data Source
Figure 1
AI summary
The present invention relates to compositions containing at least one thermoplastic polyurethane, at least one polymer selected from the group consisting of ethylene-vinyl acetate copolymers, polyethylenes, polypropylenes, ethylene-propylene copolymers and copolymers based on styrene, at least one metal hydroxide and at least one phosphorous-containing flame retardant. The thermoplastic polyurethane is selected from the group consisting of thermoplastic polyurethanes based on at least one diisocyanate and at least one polycarbonate diol, and of thermoplastic polyurethanes based on at least one diisocyanate and polytetrahydrofuran polyol. The present invention further relates to the use of such compositions for producing cable sheathings.