Modified Conjugated Diene Polymer for Tire Tread
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Solution Overview
Problem
Conventional modified conjugated diene polymers face challenges in achieving a balance between low hysteresis loss, wet skid resistance, and abrasion resistance while maintaining processability, particularly when high modifying group concentrations lead to increased viscosity and deteriorated kneading properties during tire production.
Innovation Solution
A modified conjugated diene polymer with specific molecular weight distribution characteristics, including multiple peaks in the molecular weight distribution curve, and the use of multiple modifiers or blending high- and low-molecular-weight polymers to optimize the balance of properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high modifying group concentration is used to improve wet skid resistance and abrasion resistance, then low hysteresis loss is achieved, but viscosity increases and kneading properties deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the modifying group concentration within 0.01-5 mass% and the molecular weight distribution (Mw/Mn ratio between 1.05-3.0). This optimization resolves the contradiction by finding the optimal parameter range where sufficient silane coupling occurs for wet skid resistance while maintaining manageable viscosity for kneading processes.
Solution Approach 2:
The patent creates a composite structure by forming silane crosslinked sections within the conjugated diene polymer chains. These crosslinked sections act as discrete reinforcing points that improve wet skid resistance without creating excessive network density that would cause high viscosity, thus resolving the contradiction between performance and processability.
2Strength
If high modifying group concentration is used to improve abrasion resistance, then low hysteresis loss is achieved, but viscosity increases and kneading properties deteriorate
Solution Approach 1:
The patent optimizes the modifying group concentration to 0.01-5 mass% and controls the Mw/Mn ratio between 1.05-3.0, achieving sufficient abrasion resistance through controlled silane crosslinking while maintaining viscosity levels that allow proper kneading and processing.
Solution Approach 2:
The silane crosslinked sections create a composite structure within the polymer that provides abrasion resistance through localized reinforcement without forming excessive crosslinked networks that would increase viscosity and impair kneading properties.
3Reliability
If silane coupling agent is added to improve silica dispersibility, then wet skid resistance is enhanced, but processability deteriorates due to increased viscosity
Solution Approach 1:
The patent merges the silane coupling function directly into the polymer chain structure by incorporating silane-modified conjugated diene units. This integration eliminates the need for separate silane coupling agent additions, achieving improved silica dispersibility and wet skid resistance while avoiding the viscosity increase that would result from excess external coupling agents.
Solution Approach 2:
By controlling the modifying group concentration at 0.01-5 mass%, the patent achieves sufficient silane coupling for improved silica dispersibility and wet skid resistance while maintaining viscosity at levels that preserve proper processability during tire manufacturing.
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 provides a modified conjugated diene polymer with superior balance between low hysteresis loss, wet skid resistance, and abrasion resistance, while improving processability and reducing issues related to viscosity and kneading difficulties.
Implementation Method 1
a polymerization step including subjecting a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound to polymerization or copolymerization with a polymerization initiator containing a compound having a specific structure and having at least one nitrogen atom in the molecule and an organic lithium compound to obtain a conjugated diene polymer having an active end
Implementation Method 2
a modification step including reacting the conjugated diene polymer with a compound having a specific structure
Implementation Method 3
introducing an amino group, which has affinity for carbon black, to an end of polymerization initiation of a rubbery polymer is known to allow carbon black to capture thereon the polymerization-starting end
Data Source
AI summary
A modified conjugated diene polymer satisfying the following conditions (I) to (IV): (I) at least two peaks are observed in a molecular weight distribution curve obtained from measurement by gel permeation chromatography (GPC); (II) when a peak of the highest molecular weight is defined as a peak (B), a peak of the largest peak area except for the peak (B) is defined as a peak (T) in the molecular weight distribution curve, a peak molecular weight of the peak (B) is from 500,000 to 2,500,000 and a peak molecular weight of the peak (T) is from 150,000 to 600, 000; (III) an area of the peak (T) is from 30% to 80% and a total value of an area of the peak (B) and the area of the peak (T) is 65% or more when the total area of the molecular weight distribution curve is defined as 100%; and (IV) a proportion of a modified polymer chain(s) in a region ranging from a low-molecular-weight side to a point of 5% cumulative area is from 60% to 99% in the molecular weight distribution curve.