Halogen-Free Flame Retardant Styrenic Block Copolymer Composition

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Solution Overview

Problem

Existing styrenic block copolymer-based halogen-free flame retardant thermoplastic elastomer compositions face challenges in being extrudable and processable without mineral oil softeners, which reduces flame retardancy performance, and using liquid flame retardants can lead to surface tackiness due to leaching.

Innovation Solution

Incorporating a hydrogenated styrenic block copolymer with high styrene content and a synergistic combination of liquid and solid halogen-free flame retardants, including a phosphorus-containing phosphate ester, to create a stable and processable composition without mineral oil, suitable for wire and cable applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If mineral oil softener is used to improve processability and extrudability of styrenic block copolymer-based TPE compositions, then ease of manufacture is improved, but flame retardant performance deteriorates

Engineering Contradiction:

ImproveprocessabilityVSAvoidflame retardant performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention removes mineral oil softener from the composition entirely, replacing its softening function with a specifically designed styrenic block copolymer having controlled microstructure (low polydispersity, specific block composition) that provides both flexibility and processability without compromising flame retardancy

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the molecular parameters of the styrenic block copolymer (polydispersity index ≤ 2.0, specific styrene content distribution across blocks, controlled molecular weight) to achieve optimal balance between processability, flexibility, and flame retardant performance without requiring mineral oil softener

Inventive Principle:

Principle #35Parameter changes

2Reliability

If liquid flame retardant is used to replace mineral oil softener, then flame retardant performance is improved, but surface quality deteriorates due to leaching and tackiness

Engineering Contradiction:

Improveflame retardant performanceVSAvoidsurface quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention removes liquid flame retardants from the composition, eliminating the leaching problem that causes surface tackiness, while achieving both flame retardancy and surface quality through the optimized styrenic block copolymer matrix combined with solid flame retardant additives

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The styrenic block copolymer with controlled microstructure serves as an intermediary matrix that provides compatibility and stable dispersion for solid flame retardant additives, preventing aggregation and ensuring uniform distribution without requiring liquid flame retardants

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If styrenic block copolymer with low styrene content is used to eliminate softener, then softener-free composition is achieved, but flexibility and physical strength deteriorate

Engineering Contradiction:

Improvesoftener-free compositionVSAvoidflexibility and physical strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The invention optimizes the styrene content parameter within specific ranges (20-40 wt% total, with 30-40 wt% in hard blocks and 10-30 wt% in soft blocks) to achieve the right balance between flexibility, strength, and softener-free processability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates local quality differentiation within the copolymer structure by concentrating styrene in hard blocks for strength and using lower styrene content in soft blocks for flexibility, achieving overall optimal performance without softener

Inventive Principle:

Principle #3Local quality

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 enables halogen-free flame retardant thermoplastic elastomer compositions that are easily processable, maintain high flame retardancy, and achieve a smooth surface, passing UL 94 VB tests with a V-0 rating at various thicknesses, while minimizing the use of softeners.

Implementation Method 1

a hydrogenated styrenic block copolymer having relatively high styrene or mono alkenyl arene content

Methodology Applied

Scientific EffectHydrogenation: Hydrogenation

Implementation Method 2

a blend of non-halogen flame retardants including a liquid phosphorous-containing component and a solid secondary component

Methodology Applied

Scientific EffectFlame retardancy:

Data Source

PatentUS9156978B1Low softener halogen free flame retardant styrenic block copolymer-based thermoplastic elastomer compositions

Publication Date: 2015.10.13 TEKNOR APEX COMPANY

AI summary

Halogen free flame retardant thermoplastic elastomer compositions including a hydrogenated styrenic block copolymer having relatively high styrene or mono alkenyl arene content and styrene or mono alkenyl arene in each block. Surprisingly, the compositions contain low amounts or are free of plasticizing softeners. The compositions include a blend of non-halogen flame retardants including a liquid phosphorous-containing component and a solid secondary component. The compositions are suitable for extrusion or molding and are useful for films or wire and cable applications.