Modified Polybutadiene Polymer for Low Heat Buildup Tires
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Solution Overview
Problem
Current rubber compositions for tires face challenges in achieving both low heat buildup and improved fracture properties, as existing high-cis polybutadiene rubbers have limited reaction efficiency for introducing functional groups that enhance filler affinity, leading to suboptimal performance in reducing rolling resistance and crack resistance.
Innovation Solution
A modified conjugated diene-based polymer with a high cis-1,4 bond content and a primary amino group is introduced, which is produced by reacting a conjugated diene-based polymer with specific functional groups and a primary amino compound, resulting in a rubber composition that effectively improves low heat buildup and fracture properties when compounded with fillers like carbon black.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-cis polybutadiene rubber is used with conventional modification methods, then the fracture properties are improved, but the reaction efficiency for introducing functional groups is low (about 30% to total polymer terminal), limiting the improvement of low loss factor
Solution Approach 1:
The patent changes the chemical parameters of the polymer by introducing a primary amino group through a two-step modification process: first reacting the conjugated diene-based polymer with a compound containing an isocyanate group, then reacting the resulting product with a compound containing a primary amino group. This parameter change in functional group introduction achieves both high reaction efficiency and improved fracture properties
Solution Approach 2:
The patent creates a composite structure by combining the conjugated diene-based polymer backbone with primary amino functional groups, forming a modified polymer that exhibits enhanced fracture properties and filler affinity. The composite nature of the modified polymer structure allows simultaneous achievement of high reaction efficiency and improved mechanical properties
2Loss of energy
If anion polymerization system is used to introduce functional groups at 100% reaction efficiency, then the low loss factor is largely improved, but the fracture properties become low compared to unmodified high-cis polybutadiene rubber
Solution Approach 1:
The patent carefully controls the degree of functional group introduction by using a two-step modification process with specific molar ratios, achieving optimal balance between low loss factor improvement and fracture property maintenance. The parameter control ensures that functional groups are introduced efficiently without compromising the polymer's mechanical integrity
Solution Approach 2:
The patent introduces functional groups at specific locations (polymer terminals) through the modification process, creating local regions of high filler affinity while maintaining the overall structural integrity of the polymer chains. This localized modification approach preserves fracture properties while improving low loss factor
3Strength
If modified high-cis polybutadiene rubber with functional groups is used to improve low loss factor, then the fracture properties are superior to unmodified rubber, but the reaction efficiency between polymer terminal and modifying agent remains low
Solution Approach 1:
The patent uses an isocyanate-containing compound as an intermediary in a two-step modification process. The isocyanate group first reacts with the polymer terminal to form an intermediate structure, which then reacts with the primary amino group compound. This intermediary approach enables high reaction efficiency while maintaining superior fracture properties
Solution Approach 2:
The patent performs preliminary modification by first introducing the isocyanate group to the polymer terminal before introducing the primary amino group. This preliminary action creates a reactive intermediate that facilitates subsequent high-efficiency reaction with the amino group compound, achieving both high reaction efficiency and superior fracture 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 modified rubber composition significantly enhances the low heat buildup and fracture properties of tires, achieving better dispersibility and crystallinity, thereby improving the tire's resistance to crack growth and reducing rolling resistance.
Implementation Method 1
introducing an amino group with active hydrogen having a very high affinity with carbon black into a polymer terminal
Data Source
AI summary
This invention relates to a rubber composition being excellent in the low heat buildup and fracture properties (resistance to crack growth). and more particularly to a rubber composition, characterized by compounding 10-100 parts by mass of an inorganic filler and/or carbon black based on 100 parts by mass of a rubber component including not less than 10 mass % of a modified conjugated diene-based polymer having a cis-1,4 bond content of not less than 90% and a vinyl bond content of not more than 1.2% and a primary amino group. In this case, the modified conjugated diene-based polymer is obtained by (1) reacting the predetermined conjugated diene-based polymer having an active terminal with a compound having two or more predetermined functional groups and (2) further reacting the resulting product with a compound having a primary amino group.