Modified Thermoplastic Resins for Tire Tg and Elastomer Compatibility
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Solution Overview
Problem
Current thermoplastic resin technology for tires struggles to balance the glass transition temperature (Tg) and molecular weight distribution, leading to inefficiencies in modifying elastomer properties for improved wet grip and rolling resistance.
Innovation Solution
The development of modified thermoplastic resins with reduced oligomer content, specifically dimer, trimer, tetramer, and pentamer species, which enhances the glass transition temperature (Tg) to z-average molecular weight (Mz) ratio, thereby improving compatibility and performance in rubber and elastomer compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the molecular weight of thermoplastic resin is increased to raise glass transition temperature (Tg), then Tg is improved, but the amount of incompatible high molecular weight species increases, reducing compatibility with elastomers
Solution Approach 1:
The patent changes the molecular weight distribution parameters of the thermoplastic resin by reducing oligomer content (Mn < 5,000 g/mol, Mz < 50,000 g/mol, oligomer content < 50 wt%) while maintaining a controlled amount of high molecular weight species. This parameter optimization allows achieving higher Tg through increased Mn without excessive accumulation of incompatible high Mw species, thus resolving the contradiction between Tg improvement and compatibility maintenance.
Solution Approach 2:
The patent applies local quality by creating a specific molecular weight distribution profile within the thermoplastic resin: controlling Mn to raise Tg, limiting Mz to prevent excessive incompatibility, and restricting oligomer content to maintain processability. This localized control of different molecular weight regions enables simultaneous achievement of high Tg and good elastomer compatibility.
2Temperature
If oligomer content in thermoplastic resin is reduced to increase Tg/Mz ratio, then Tg/Mz ratio is improved, but the complexity of resin synthesis and purification increases
Solution Approach 1:
The patent applies preliminary action by designing the polymerization process to inherently produce the desired molecular weight distribution from the start, rather than requiring extensive post-polymerization purification. By controlling polymerization conditions (catalyst selection, temperature, monomer feed rate) to directly yield resins with Mn < 5,000 g/mol, Mz < 50,000 g/mol, and oligomer content < 50 wt%, the process simplifies downstream processing while achieving the target Tg/Mz ratio.
3Temperature
If high molecular weight thermoplastic resin species are increased to raise Tg, then Tg is improved, but the resin compatibility with elastomers deteriorates
Solution Approach 1:
The patent optimizes the parameter of high molecular weight species content by setting Mz < 50,000 g/mol, which is sufficiently high to contribute to Tg elevation but controlled to maintain compatibility with elastomers. This parameter balancing allows the resin to provide the necessary Tg increase (0-160°C) without exceeding the threshold where high Mw species become incompatible with the rubber matrix.
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2
AI summary
Modified thermoplastic hydrocarbon thermoplastic resins are provided, as well as methods of their manufacture and uses thereof in rubber compositions. The modified thermoplastic resins are modified by decreasing the relative quantity of the dimer, trimer, tetramer, and pentamer oligomers as compared to the corresponding unmodified thermoplastic resin polymers, resulting in a product that exhibits a greater shift in the glass transition temperature of the elastomer(s) used in tire formulations. This translates to better viscoelastic predictors of tire tread performance, such as wet grip and rolling resistance. The modified thermoplastic resins impart remarkable properties on various rubber compositions, such as tires, belts, hoses, brakes, and the like. Automobile tires incorporating the modified thermoplastic resins are shown to possess excellent results in balancing the properties of rolling resistance, tire wear, snow performance, and wet braking performance.