Blocked Mercaptosilane Coupling Agent for Zinc-Free Rubber
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Solution Overview
Problem
The elimination of zinc oxide from rubber compositions reinforced with silica degrades processability characteristics, leading to premature vulcanization and high viscosities, making them difficult to work with industrially, and replacing it with other metals is not environmentally sustainable as they eventually contribute to environmental pollution.
Innovation Solution
The use of a blocked mercaptosilane as a coupling agent in diene rubber compositions, allowing for the reduction or elimination of zinc while maintaining processability and preventing premature scorching, without replacing zinc with another metal, by forming a bond between the inorganic filler and diene elastomer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If zinc oxide is eliminated from rubber compositions reinforced with silica, then environmental safety is improved, but processability characteristics degrade with premature vulcanization and high viscosities
Solution Approach 1:
The patent introduces a specific coupling agent as an intermediary substance that mediates between the silica filler and the rubber matrix. This coupling agent enables effective interaction and reinforcement while allowing the elimination of zinc oxide, thus resolving the contradiction between environmental safety and processability.
Solution Approach 2:
The patent changes the chemical parameters of the rubber composition by introducing a coupling agent with specific functional groups that can interact with both silica and rubber. This parameter change allows the system to function without zinc oxide, maintaining processability while improving environmental safety.
2Object-affected harmful factors
If zinc oxide is eliminated from rubber compositions, then toxicity is reduced, but scorch time decreases making premature vulcanization unacceptable
Solution Approach 1:
The coupling agent acts as a mediator that protects the rubber matrix from direct interaction with silica filler that would otherwise cause premature vulcanization. This intermediary function allows the elimination of zinc oxide while maintaining adequate scorch time.
3Object-affected harmful factors
If zinc oxide is replaced with other metal oxides, then zinc elimination is achieved, but environmental sustainability is compromised due to metal pollution from tyre wear debris
Solution Approach 1:
The patent extracts zinc oxide completely from the rubber composition formulation. Instead of replacing it with another metal oxide, the invention removes the problematic substance entirely and uses a coupling agent to achieve the desired reinforcement and processing characteristics.
Solution Approach 2:
The patent replaces permanent metal oxide additives with an organic coupling agent that performs the necessary function without the long-term environmental persistence and pollution issues associated with metal additives. The coupling agent degrades more readily and does not contribute to metal pollution from tyre wear.
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 blocked mercaptosilane effectively maintains acceptable scorch times and improves processability of zinc-free rubber compositions, reducing hysteresis and environmental impact by avoiding the release of volatile organic compounds and minimizing rolling resistance in tires.
Implementation Method 1
one coupling agent consisting of a blocked mercaptosilane... which makes it possible to very significantly decrease the zinc of rubber formulations reinforced with an inorganic filler such as silica... by forming a bond between the inorganic filler and diene elastomer
Data Source
AI summary
The invention relates to a rubber composition that is free of zinc or that contains less than 0.5 phr of zinc, which can be used for the manufacture of tyres, based on at least:one diene elastomer;one sulphur-based crosslinking system;one inorganic filler as reinforcing filler;one blocked mercaptosilane of general formula I below:(HO)3-nR1n—Si—Z—S—C(═O)-Ain which:R1, which are identical or different, each represent a monovalent hydrocarbon-based group chosen from alkyls, which are linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms;A represents hydrogen or a monovalent hydrocarbon-based group chosen from alkyls, which are linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms;Z represents a divalent bonding group comprising from 1 to 18 carbon atoms;n is an integer equal to 0, 1 or 2.