Conjugated Diene Polymer Composition for Tire Rubber Processability
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Solution Overview
Problem
The conjugated diene polymer used in tire production has insufficient processability, and the cross-linked rubber it forms lacks strength properties and fuel efficiency.
Innovation Solution
A conjugated diene polymer with specific molecular weight distribution characteristics, including two or more peaks in the molecular weight distribution curve, an ionic strength index of 25% or more, and a high proportion of conjugated diene monomer units, is developed to enhance processability and produce a cross-linked rubber with improved strength, wear resistance, and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a modified conjugated diene polymer with specific molecular weight distribution is used, then strength properties and wear resistance are improved, but processability becomes insufficient
Solution Approach 1:
The polymer is segmented into two distinct molecular weight populations: high molecular weight chains (Mw/Mn ≤ 2.0) providing strength and wear resistance, and low molecular weight chains (Mw/Mn ≥ 3.0) providing processability. This segmentation allows each population to fulfill its specific functional role without compromising the other.
Solution Approach 2:
The invention changes the molecular weight distribution parameters by controlling the ratio of high to low molecular weight chains (0.3-2.0 by weight) and adjusting the overall Mw/Mn ratio (1.8-3.5). These parameter changes enable simultaneous achievement of good processability and excellent mechanical properties.
2Strength
If traditional rubber compositions containing carbon black are used, then strength properties are maintained, but fuel efficiency deteriorates
Solution Approach 1:
The invention changes the filler parameter from carbon black to silica, which has different surface properties and interaction characteristics with the polymer matrix. This parameter change reduces hysteresis loss and heat buildup, thereby improving fuel efficiency while maintaining strength through optimized polymer-filler interactions.
Solution Approach 2:
The invention creates a composite material system combining silica filler with the specifically designed conjugated diene polymer. The composite structure allows silica to provide reinforcement and the polymer matrix to provide flexibility and low rolling resistance, achieving both strength and fuel efficiency.
3Ease of manufacture
If the molecular weight distribution is broadened to improve processability, then strength properties become susceptible to improvement
Solution Approach 1:
The broad molecular weight distribution is segmented into two distinct populations with different Mw/Mn ratios. The high molecular weight portion (Mw/Mn ≤ 2.0) maintains strength properties, while the low molecular weight portion (Mw/Mn ≥ 3.0) improves processability. The controlled ratio between these populations prevents strength deterioration.
Solution Approach 2:
Different regions of the molecular weight distribution are assigned different quality characteristics: high molecular weight chains provide structural integrity and strength, while low molecular weight chains provide flowability and processability. This local quality assignment allows simultaneous optimization of both properties.
Data Source
AI summary
A conjugated diene polymer contains at least conjugated diene monomer units, wherein the conjugated diene polymer has an ionic strength index of 25% or more and a molecular weight distribution curve where two or more peaks are present when measured by gel permeation chromatography, wherein when among the peaks in the molecular weight distribution curve, a peak having the largest peak area proportion is defined as a first peak, and a peak having the second largest peak area proportion is defined as a second peak, the conjugated diene polymer has an entire molecular weight distribution (Mw/Mn) of 1.50 or more, the first peak has a molecular weight distribution (Mw/Mn) of 1.30 or less, and the second peak has a molecular weight distribution (Mw/Mn) of 1.30 or less.