Tire Tread Compound Using Partially Devulcanized Reclaimed Rubber
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Solution Overview
Problem
The use of reclaimed rubber in tire treads is limited due to high treatment costs and performance issues when high amounts are introduced, as conventional methods focus on fully devulcanizing rubber to match virgin rubber properties, resulting in restricted usage percentages and reduced performance characteristics.
Innovation Solution
A tire tread compound is formulated with a virgin rubber component and a partially reclaimed rubber component having a Mooney viscosity greater than 65 and crosslink density between 5 and 70% of the original, allowing for increased reclaimed rubber content and improved tread properties through reduced devulcanization extent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reclaimed rubber is fully devulcanized to match virgin rubber properties, then processability is improved, but treatment costs increase and performance characteristics are reduced
Solution Approach 1:
The patent changes the key parameter of Mooney viscosity from the conventional low range (20-40) to a higher range (40-80), and adjusts crosslink density to 5-70% of original. This parameter inversion resolves the contradiction by showing that moderate devulcanization with higher viscosity retention maintains both processability and performance characteristics, eliminating the need for extreme treatment that degrades rubber properties
Solution Approach 2:
Instead of fully devulcanizing the rubber to achieve maximum processability, the patent applies partial devulcanization that stops at an optimal point where crosslink density is 5-70% of original. This partial action prevents over-treatment that would destroy rubber properties, thereby maintaining performance characteristics while still achieving sufficient processability
2Quantity of substance
If high amounts of reclaimed rubber are introduced into tire tread compound, then recycling efficiency is improved, but performance characteristics are reduced
Solution Approach 1:
By changing the Mooney viscosity parameter to a higher range (40-80) and crosslink density to 5-70% of original, the patent enables use of reclaimed rubber at 30-100% of total rubber content. This parameter change allows high reclaimed rubber content while maintaining adequate performance, as the moderate devulcanization preserves essential rubber properties even at high concentrations
3Ease of operation
If reclaimed rubber is extensively treated to achieve virgin rubber-like properties, then mixing ability is improved, but manufacturing costs increase
Solution Approach 1:
The patent applies partial devulcanization treatment that achieves sufficient mixing ability without extensive processing. By stopping at crosslink density of 5-70% of original rather than complete devulcanization, the process reduces treatment costs while maintaining adequate mixing ability for incorporation into tire tread compound
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
This approach enables a higher percentage of reclaimed rubber in tire treads, enhancing performance characteristics such as heat buildup resistance and tear resistance while reducing processing costs.
Implementation Method 1
reclaimed rubber refers to rubber that has been crosslinked and subsequently treated to break down the crosslinked network and thereby make the rubber processable. The treatment may break or sever the sulfur crosslinks and/or sever the polymer chains.
Implementation Method 2
The waste rubber may be mixed with the virgin rubber in particle form, or may be reclaimed, also sometimes referred to as devulcanized, to allow the recycled rubber to bond with the virgin rubber during vulcanization.
Data Source
AI summary
A method of making a tire tread includes mixing a tire tread compound including a virgin rubber component and a reclaimed rubber component, forming a green sheet from the tire tread compound, and curing the green sheet to form a cured tire tread. The reclaimed rubber component may have a Mooney viscosity (ML (1+4) @ 100° C.) of greater than 65. The reclaimed rubber component may also have a crosslink density that is between 20 and 50% of the crosslink density of the reclaimed rubber prior to reclaiming.