High Strength Rubber Composition Using Crosslinking Resin
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Solution Overview
Problem
Conventional rubber compositions used in tires face challenges with high stiffness, leading to issues like sulfur migration, premature vulcanization, and reduced mechanical properties, while traditional methods to increase stiffness, such as using reinforcing fillers, can negatively impact hysteresis properties and rolling resistance.
Innovation Solution
A rubber composition is developed using aromatic compounds derived from specific reactants and phenolic compounds, which form a crosslinking resin that avoids formaldehyde production and maintains stiffness at high temperatures, offering improved low-strain stiffness and retention compared to conventional systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a concentrated vulcanization system (high sulfur and accelerator content) is used to achieve high stiffness, then low-strain stiffness is improved, but sulfur migration and blooming occur during storage, deteriorating green tack and adhesion
Solution Approach 1:
The patent changes the chemical composition parameters of the vulcanization system by replacing conventional accelerators with N-substituted oxymethylmelamines and using specific sulfur donors, which alters the reactivity and storage stability characteristics while maintaining the concentrated system's stiffness benefits
Solution Approach 2:
The patent introduces N-substituted oxymethylmelamines as intermediary compounds that mediate between sulfur and the rubber matrix, preventing direct sulfur migration to the surface while still enabling effective vulcanization and maintaining green tack during storage
2Strength
If a concentrated vulcanization system is used to achieve high stiffness, then low-strain stiffness is improved, but the delay phase is reduced, leading to premature curing and altered vulcanization kinetics
Solution Approach 1:
The patent employs N-substituted oxymethylmelamines that remain stable during storage and mixing but become activated under vulcanization conditions, effectively delaying the vulcanization reaction until the appropriate time while still achieving the desired concentrated system performance
3Strength
If a concentrated vulcanization system is used to achieve high stiffness, then low-strain stiffness is improved, but mechanical properties deteriorate during ageing in the cured state
Solution Approach 1:
The patent modifies the vulcanization system composition by using N-substituted oxymethylmelamines with specific substituent groups (alkyl, aryl, alkaryl, or cycloalkyl containing 1-12 carbon atoms) and controlled sulfur donor content (0.1-5 phr), which changes the crosslinking network structure to improve both stiffness and ageing resistance
4Strength
If reinforcing fillers are increased to achieve high stiffness, then low-strain stiffness is improved, but hysteresis properties and rolling resistance are detrimentally affected
Solution Approach 1:
The patent replaces the mechanical reinforcement approach (increasing filler content) with a chemical reinforcement approach using N-substituted oxymethylmelamine-based vulcanization systems, which achieve stiffness through molecular crosslinking rather than physical filler networks, thereby preserving hysteresis and rolling resistance properties
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 new composition achieves equivalent or superior low-strain stiffness to conventional systems, maintains stiffness at high temperatures, and eliminates formaldehyde, addressing environmental concerns and improving tire performance.
Implementation Method 1
The terms 'methylene acceptor' and 'methylene donor' are well known to a person skilled in the art and are widely used to denote compounds capable of reacting together to generate, by condensation, a three-dimensional reinforcing resin
Implementation Method 2
which will become superimposed and interpenetrated with the reinforcing filler/elastomer network, on the one hand, and with the elastomer/sulfur network, on the other hand
Data Source
AI summary
A rubber composition comprises at least one resin based on: (A1) at least one aromatic compound resulting from the reaction between a reactant of formula (α):where B represents CHO or CH2OH, (α) and a reactant of formula (β) orand (A2) at least one phenolic compound chosen from: (A21) at least one aromatic polyphenol comprising at least one aromatic ring bearing at least two hydroxyl functional groups in the meta position with respect to one another, the two positions ortho to at least one of the hydroxyl functional groups being unsubstituted; and/or (A22) at least one aromatic monophenol comprising at least one six-membered aromatic ring bearing a single hydroxyl functional group, the two positions ortho to the hydroxyl functional group being unsubstituted or at least one position ortho to and the position para to the hydroxyl functional group being unsubstituted.