Transparent TPU Cable Sheathing With Halogen-Free Flame Retardants

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Solution Overview

Problem

Current flame-retarded thermoplastic polyurethanes used in cable sheathings face challenges in achieving good mechanical properties, flame retardancy, chemical resistance, and transparency, especially with thin cable thicknesses, and often contain harmful melamine derivatives that result in opaque materials and inadequate limiting oxygen index (LOI) values.

Innovation Solution

A composition comprising a thermoplastic polyurethane combined with ammonium phosphate or ammonium polyphosphates as a first flame retardant and derivatives of phosphinic acid, phosphonic acid, or phosphoric acid as a second phosphorus-containing flame retardant, which are bio-degradable and free from melamine or its derivatives, optimizing mechanical and flame retardancy properties while maintaining transparency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If melamine cyanurate or melamine-based flame retardants are used in thermoplastic polyurethane, then flame retardancy is improved, but the material becomes opaque and contains harmful substances

Engineering Contradiction:
Improveflame retardancyVSAvoidtransparency
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The invention extracts and removes melamine-based flame retardants from the TPU composition, replacing them with alternative flame retardant systems that do not compromise transparency. The patent specifically eliminates melamine cyanurate and melamine phosphate in favor of other chemical approaches that maintain optical clarity while providing flame protection.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention employs a composite flame retardant system combining multiple substances including phosphorus-containing compounds, nitrogen-containing compounds, and metal hydroxides in specific ratios. This composite approach achieves effective flame retardancy through synergistic interactions while maintaining material transparency and avoiding harmful melamine derivatives.

Inventive Principle:
Principle #40Composite materials

2Reliability

If flame retardants are added to achieve good flame retardancy, then fire safety is improved, but mechanical properties and chemical resistance deteriorate

Engineering Contradiction:
Improveflame retardancyVSAvoidmechanical properties
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention optimizes the concentration and ratio parameters of different flame retardant components to achieve effective flame protection while minimizing impact on mechanical properties. Specific weight percentages and compositional ratios are carefully controlled to balance flame retardancy with mechanical strength and chemical resistance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

A multi-component flame retardant system is used where phosphorus-containing compounds, nitrogen-containing compounds, and metal hydroxides work synergistically. This composite approach provides effective flame protection while the balanced formulation maintains mechanical properties and chemical resistance better than single-component systems.

Inventive Principle:
Principle #40Composite materials

3Object-affected harmful factors

If halogen-free flame retardants are used to reduce toxic smoke, then environmental safety is improved, but flame retardancy performance worsens

Engineering Contradiction:
Improvetoxic smokeVSAvoidflame retardancy
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention uses a composite flame retardant system combining phosphorus-containing compounds, nitrogen-containing compounds, and metal hydroxides that work synergistically to achieve effective flame retardancy without halogenated substances. This multi-component approach compensates for the lower individual effectiveness of halogen-free additives through cooperative chemical mechanisms.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent employs intermediary substances and synergistic combinations where different flame retardant components enhance each other's effectiveness. The composite system creates intermediate chemical reactions and mechanisms that improve overall flame protection performance while maintaining the halogen-free, low-toxicity advantage.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Length of moving object

If thin cable sheathings are produced to reduce weight and improve flexibility, then cable performance is improved, but achieving adequate flame retardancy becomes more difficult

Engineering Contradiction:
Improvecable thicknessVSAvoidflame retardancy
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The invention optimizes flame retardant concentration parameters and compositional ratios specifically for thin-walled applications. By adjusting the types and amounts of flame retardant additives, effective flame protection is achieved in thin cable sheathings where traditional formulations would be insufficient.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

A highly effective composite flame retardant system is used that provides maximum flame protection per unit thickness. The synergistic combination of phosphorus-containing compounds, nitrogen-containing compounds, and metal hydroxides delivers superior flame retardancy performance in thin-walled cable sheathings, enabling compliance with fire safety standards despite reduced wall thickness.

Inventive Principle:
Principle #40Composite materials

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 exhibits excellent mechanical properties, high flame retardancy, and chemical resistance, with improved transparency and reduced toxicity, specifically suitable for thin cable sheathings, meeting stringent flame retardancy standards like DIN EN 45545.

Implementation Method 1

a first flame retardant (F1) selected from the group consisting of ammonium phosphate and ammonium polyphosphates

Methodology Applied
Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

a phosphorus-containing flame retardant (F2) selected from the group consisting of derivatives of phosphinic acid, derivatives of phosphonic acid and derivatives of phosphoric acid

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS20230365783A1Flame-retarded thermoplastic polyurethane
Publication Date: 2023.11.16 BASF SE

AI summary

A composition contains a thermoplastic polyurethane, a first flame retardant (F1) selected from ammonium phosphate and ammonium polyphosphates, and a phosphorus-containing flame retardant (F2) selected from derivatives of phosphinic acid, derivatives of phosphonic acid, and derivatives of phosphoric acid. The composition according to the present invention is useful for the production of cable sheathings.