Flame-Retardant Rubber Composition With Halogen-Free Property Balance

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Solution Overview

Problem

Existing rubber compositions using ethylene/α-olefin/non-conjugated diene copolymers face challenges in achieving high flame retardancy, rubber properties, and environmental sustainability, with halogen-based agents causing pollution and halogen-free alternatives compromising material properties or processability.

Innovation Solution

Incorporating hydrated metal oxides, such as aluminum hydroxide, with a silane coupling agent, plasticizer, and cross-linking agent into the rubber composition, optimizing the carbon number of α-olefin, and using ethylene/α-olefin oligomer as a plasticizer to enhance flame retardancy and rubber properties while reducing environmental impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If halogen-based flame retardant agents are used in rubber composition, then flame retardancy is improved, but environmental pollution increases

Engineering Contradiction:
Improveflame retardancyVSAvoidenvironmental pollution
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameter by replacing halogen-based flame retardant agents with metal hydroxide compounds (such as aluminum hydroxide, magnesium hydroxide). This substitution maintains flame retardant functionality while eliminating harmful halogen emissions, thus resolving the contradiction between flame safety and environmental protection

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs metal hydroxides that decompose into harmless substances (water and metal oxide) when exposed to fire, creating a temporary protective effect during flame exposure. The decomposition reaction absorbs heat and releases non-toxic gases, providing effective flame retardancy without persistent environmental harm

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Object-generated harmful factors

If halogen-free flame retardant foam materials are used, then environmental load is reduced, but rubber properties deteriorate

Engineering Contradiction:
Improveenvironmental loadVSAvoidrubber properties
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent creates a composite rubber composition by combining ethylene/α-olefin/non-conjugated diene copolymer with metal hydroxide flame retardants and silane coupling agents. This composite structure integrates the benefits of both the rubber matrix (providing elastic properties) and the inorganic flame retardant phase (providing fire resistance), achieving both good rubber properties and environmental compatibility

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent introduces silane coupling agents as intermediary substances that bridge the organic rubber matrix and inorganic metal hydroxide particles. These coupling agents improve interfacial adhesion, ensuring that the flame retardant particles are uniformly distributed and effectively bonded to the rubber, thereby maintaining mechanical properties while achieving flame retardancy

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If metal hydroxide is used as flame retardant agent in acid-modified polyolefin, then halogen-free flame retardancy is achieved, but hardness increases and rubber properties become insufficient

Engineering Contradiction:
Improvehalogen-free flame retardancyVSAvoidhardness and rubber properties
Core Design Contradiction:
Object-generated harmful factorsVSStrength

Solution Approach 1:

The patent applies local quality optimization by carefully controlling the particle size distribution and spatial distribution of metal hydroxide particles within the rubber matrix. By optimizing these local characteristics, the flame retardant effect is maximized while minimizing the impact on overall rubber properties and hardness

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent adjusts multiple parameters including the type and ratio of rubber components, the particle size and surface treatment of metal hydroxides, and the composition of silane coupling agents. These parameter optimizations balance the competing requirements of flame retardancy and rubber mechanical properties, preventing excessive hardness increase

Inventive Principle:
Principle #35Parameter changes

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 flame retardancy, improved rubber properties, and reduced environmental load, suitable for sealing materials with optimal hardness and flexibility, meeting high-temperature and low-temperature performance requirements.

Implementation Method 1

a silane coupling agent

Methodology Applied
Scientific EffectSilane coupling: Chemical Bonding

Implementation Method 2

a hydrated metal oxide

Methodology Applied
Scientific EffectThermal decomposition of hydrated metal oxide: Pyrolysis

Implementation Method 3

hydrated metal oxide as a flame retardant agent

Methodology Applied
Scientific EffectEndothermic reaction: Endothermic Reaction

Data Source

PatentUS12509538B2Flame-retardant rubber composition
Publication Date: 2025.12.30 NOK CORP

AI summary

A flame-retardant rubber composition is provided which is excellent in flame retardancy and rubber properties and reduces environmental load. The flame-retardant rubber composition comprises an ethylene/α-olefin/non-conjugated diene copolymer, a hydrated metal oxide, a silane coupling agent, a plasticizer, and a cross-linking agent, wherein a carbon number of the α-olefin of the ethylene/α-olefin/non-conjugated diene copolymer is three and more, and 180 to 350 parts by mass of the hydrated metal oxide and 10 to 60 parts by mass of the plasticizer are included per 100 parts by mass of the ethylene/α-olefin/non-conjugated diene copolymer.