Epoxidized Novolac Resin in TPU Flame Retardant Compositions
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Solution Overview
Problem
Current halogen-free flame retardant thermoplastic compositions for wire and cable applications often compromise on mechanical and physical properties, limiting their scope of use.
Innovation Solution
A composition comprising 15 wt% to 60 wt% thermoplastic polyurethane (TPU), 15 wt% to 40 wt% of a blend of metal hydrate, nitrogen/phosphorus-based, or phosphorus-based flame retardants, and 0.01 wt% to 20 wt% epoxidized novolac resin, which provides a halogen-free, flexible, and mechanically robust solution suitable for flexible wire and cable applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If halogen-free flame retardant additives are used in thermoplastic compositions, then ecological and health concerns are addressed, but mechanical and physical properties of the thermoplastics are degraded
Solution Approach 1:
The patent employs a composite flame retardant system combining magnesium hydroxide (metal hydrate) with phosphorus-based flame retardants (such as ammonium polyphosphate or melamine polyphosphate) in specific weight ratios. This composite approach creates synergistic effects where the metal hydrate provides thermal stability and char formation, while the phosphorus-based components enhance flame inhibition, together delivering superior flame retardancy with minimal impact on mechanical properties compared to using single additives
Solution Approach 2:
The patent optimizes the weight ratios of flame retardant components (magnesium hydroxide at 20-40 parts, phosphorus-based flame retardant at 10-30 parts per 100 parts TPU) to achieve the desired balance between flame retardancy and mechanical property preservation. By precisely controlling these parameters, the composition attains V-1 or better UL-94 ratings while maintaining acceptable tensile strength and elongation
2Reliability
If conventional flame retardant compositions are used to achieve flame retardancy, then flame retardant properties are obtained, but the composition lacks flexibility and mechanical robustness for wire and cable applications
Solution Approach 1:
The patent utilizes thermoplastic polyurethane (TPU) as the base polymer instead of conventional PVC or other rigid thermoplastics. TPU inherently provides superior flexibility, elasticity, and mechanical robustness. By optimizing the TPU composition and controlling its molecular weight and hard segment content, the patent achieves both the required flexibility for wire and cable applications and the necessary mechanical strength, while incorporating flame retardants to meet fire safety standards
Solution Approach 2:
The patent creates a multi-component composite system comprising TPU matrix, metal hydrate flame retardant, phosphorus-based flame retardant, and epoxidized novolac resin. This composite structure allows each component to contribute its specific properties: TPU provides flexibility and mechanical strength, metal hydrate provides thermal stability, phosphorus-based flame retardant provides flame inhibition, and epoxidized novolac resin enhances crosslinking and overall performance, achieving a balance between flame retardancy and mechanical properties
3Reliability
If flame retardant additives are incorporated to achieve V-1 rating or better, then flame retardancy is improved, but the composition complexity increases
Solution Approach 1:
The patent combines multiple flame retardant mechanisms into a unified system: magnesium hydroxide decomposes to release water and form protective char, phosphorus-based flame retardants promote char formation and release flame-inhibiting gases, and epoxidized novolac resin provides additional crosslinking and char reinforcement. These components work synergistically to achieve V-1 or better UL-94 ratings through a coordinated flame retardancy mechanism rather than relying on a single additive system
Solution Approach 2:
The epoxidized novolac resin acts as an intermediary component that facilitates interaction between the TPU matrix and the inorganic/organic flame retardants. It promotes crosslinking reactions that enhance the overall network structure, improving the dispersion and stability of flame retardant particles while contributing additional flame retardancy through its own char-forming capability, thereby simplifying the overall system design
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 excellent insulative, mechanical, and processability properties, similar to PVC, with a V-1 rating or better in the UL-94 flame test and suitable tensile strength for wire and cable applications, while being drip-free and halogen-free.
Implementation Method 1
the flame retardant composition comprises from 15 wt% to 40 wt% of a flame retardant selected from the group consisting of (a) a blend of a metal hydrate and a phosphorus-based flame retardant, (b) a blend of nitrogen/phosphorus-based flame retardant and (c) a phosphorus-based flame retardant, and a blend of a metal hydrate and a polyphosphate flame retardant
Implementation Method 2
from 15 wt% to 40 wt% of a flame retardant selected from the group consisting of (a) a blend of a metal hydrate and a phosphorus-based flame retardant
Data Source
AI summary
The present disclosure provides a composition which includes a thermoplastic polyurethane, a flame retardant, and an epoxidized novolac resin. The flame retardant may be selected from one or more of the following: a melamine-containing compound, a nitrogen/phosphorus-based flame retardant, a phosphorus-based flame retardant, a metal- 5 containing flame retardant, and combinations thereof. The composition may be a component of an article such as a coated wire or cable, with the composition present in the coating.