Modified Conjugated Diene Rubber Silica Affinity
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Solution Overview
Problem
Existing rubber compositions with silica for tires face challenges in processability and performance, including poor affinity with silica, leading to inferior fuel efficiency and increased heat buildup, while modifications to improve affinity can result in gelation issues affecting processability.
Innovation Solution
A method involving the polymerization of a conjugated diene rubber using an alkali metal-reacted aromatic compound, followed by reaction with an activity control agent and a modifier containing an alkoxy and halogen group, to produce a modified conjugated diene rubber that enhances tensile strength, elongation at break, low heat buildup, and wet grip properties while maintaining good processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conjugated diene rubber is mixed with silica to improve low heat buildup property, then fuel efficiency is improved, but the rubber shows poor affinity with silica leading to separation and degraded fuel efficiency
Solution Approach 1:
The patent introduces functional groups (such as hydroxyl groups from carboxylic acid modifiers) onto the rubber polymer chains, changing the chemical parameters of the rubber to improve its affinity with silica. This chemical modification allows the rubber to form strong interactions with silica surfaces, preventing separation while maintaining the low heat buildup properties of silica-filled rubber compositions.
Solution Approach 2:
The patent creates a composite structure by combining conjugated diene rubber with silica filler and carboxylic acid modifiers. The modifier acts as a coupling agent between the rubber and silica, forming a tri-component composite system where each component contributes its beneficial properties: the rubber provides elasticity, silica provides low heat buildup, and the modifier provides interfacial adhesion.
2Loss of energy
If a modifier with alkoxy group is used to improve low heat buildup property, then low heat buildup property is improved, but gelation occurs causing inferior processability
Solution Approach 1:
The patent carefully controls the molecular weight, functional group density, and chemical structure parameters of the carboxylic acid modifier to achieve optimal performance. By adjusting these parameters, the modifier improves silica affinity and heat buildup properties without causing excessive crosslinking that would lead to gelation and poor processability.
Solution Approach 2:
The patent applies modification locally at the rubber-silica interface rather than throughout the entire rubber matrix. The carboxylic acid modifier concentrates at the interface between rubber and silica, providing localized improvement in affinity and heat buildup properties while maintaining the bulk rubber's processability and avoiding widespread gelation.
3Reliability
If functional groups are introduced by reacting polymerization active end with modifier to improve affinity with silica, then affinity with silica is improved, but processability deteriorates due to gelation
Solution Approach 1:
The patent uses a controlled amount of carboxylic acid modifier relative to the rubber and silica content. Rather than fully modifying all polymer chains, the modifier is applied at an optimal concentration that provides sufficient silica affinity improvement without causing excessive crosslinking. This partial modification approach maintains processability while achieving the desired affinity enhancement.
Solution Approach 2:
The carboxylic acid modifier acts as an intermediary substance between the conjugated diene rubber and silica filler. It contains functional groups that can interact with both the rubber polymer chains and the silica surface, mediating the interface between these two components. This intermediary role improves affinity without requiring direct rubber-silica bonding that would cause gelation.
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 modified rubber composition achieves improved tensile strength, elongation at break, low heat buildup, and wet grip properties while preventing gelation issues, resulting in a more efficient and durable tire material.
Implementation Method 1
polymerizing a monomer at least containing a conjugated diene compound by using the alkali metal-reacted aromatic compound so as to obtain a conjugated diene rubber having an active end
Implementation Method 2
causing the active end of the conjugated diene rubber having an active end to react with an activity control agent
Implementation Method 3
a modifier having an alkoxy group and a halogen atom-containing group so as to obtain a modified conjugated diene rubber
Data Source
AI summary
The present invention provides a method of production of modified conjugated diene rubber, comprising a first step of causing an aromatic compound having three or more carbon atoms directly bonded to an aromatic ring in one molecule to react with an alkali metal atom so as to obtain an alkali metal-reacted aromatic compound; a second step of polymerizing a monomer at least containing a conjugated diene compound by using the alkali metal-reacted aromatic compound so as to obtain a conjugated diene rubber having an active end; a third step of causing the active end of the conjugated diene rubber having an active end to react with an activity control agent so as to obtain a conjugated diene rubber reacted with an activity control agent; and a fourth step of causing the active end of the conjugated diene rubber reacted with an activity control agent to react with a modifier having an alkoxy group and a halogen atom-containing group so as to obtain a modified conjugated diene rubber.