Silica-Filled Elastomer Viscosity Control via Coupling Agent Segmentation
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Solution Overview
Problem
The use of organosilane polysulfides in silica-filled rubber compositions leads to increased compound viscosity and manufacturing inefficiencies due to the need for rapid processing, while blocked mercaptosilanes offer processing advantages but at a high cost and with reduced coupling yield, necessitating a cost-effective solution that maintains these benefits.
Innovation Solution
A combination of organosilane polysulfides and blocked mercaptosilanes in a specific weight ratio (0.25:1 to 5:1) is used in elastomeric compositions to reduce viscosity and eliminate mixing stages, allowing for longer storage and processing of silica stocks, with the option for conventional vulcanization methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organosilane polysulfides are used as silica coupling agents, then coupling efficiency is improved, but compound viscosity increases and processing time must be shortened
Solution Approach 1:
The patent divides the coupling agent system into two separate components: organosilane polysulfide (for coupling efficiency) and blocked mercaptosilane (for viscosity control). This segmentation allows each component to perform its specific function independently, resolving the contradiction between coupling efficiency and processing time
Solution Approach 2:
The blocked mercaptosilane acts as an intermediary substance that modifies the overall compound behavior. It provides the desired low viscosity and extended processing time without interfering with the primary coupling function performed by the organosilane polysulfide
2Productivity
If blocked mercaptosilanes are used as silica coupling agents, then compound viscosity is reduced and processing time is extended, but cost increases substantially
Solution Approach 1:
The patent uses a small amount of expensive blocked mercaptosilane (0.1-5 phr) combined with a larger amount of cheaper organosilane polysulfide (1-20 phr). The blocked mercaptosilane serves as a cost-effective additive that provides processing benefits without requiring high dosage, thus controlling overall material cost
Solution Approach 2:
The patent optimizes the dosage parameters of both coupling agents to achieve the desired balance. By carefully controlling the amount of blocked mercaptosilane (0.1-5 phr) and organosilane polysulfide (1-20 phr), the formulation achieves low viscosity and extended processing time at reduced cost compared to using high levels of blocked mercaptosilane alone
3Productivity
If blocked mercaptosilanes are used at higher dosage levels, then viscosity control is improved, but coupling yield decreases due to reduced reactive groups
Solution Approach 1:
The patent segments the functional requirements by assigning viscosity control to blocked mercaptosilane and coupling yield to organosilane polysulfide. This allows each agent to operate at optimal dosage levels without compromising the other function
Solution Approach 2:
The patent optimizes the dosage parameters to resolve this contradiction. By setting blocked mercaptosilane at 0.1-5 phr and organosilane polysulfide at 1-20 phr, the formulation achieves effective viscosity control while maintaining high coupling yield through the abundant reactive groups in organosilane polysulfide
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 reduces viscosity and eliminates mixing stages while maintaining comparable tensile and viscoelastic properties to compositions using only organosilane polysulfides, offering cost-effective processing advantages and improved manufacturing efficiency.
Implementation Method 1
add silica coupling agents having a moiety (e.g., a silyl group) reactive with the silica surface
Implementation Method 2
a moiety (e.g., a mercapto, amino, vinyl, epoxy or sulfur group) that binds to the elastomer. Thus, the silica coupler provides a chemical link between the silica filler and the elastomer
Implementation Method 3
the resultant elastomeric composition obtained in the above method may be vulcanized by any conventional means, such as adding vulcanization agents and heating, or by ultraviolet radiation
Data Source
AI summary
An elastomeric composition is provided, wherein the composition comprises an elastomer; a reinforcing filler comprising silica; an organosilane polysulfide; and a blocked mercaptosilane, wherein the weight ratio of the blocked mercaptosilane to the organosilane polysulfide is about 0.25:1 to about 5:1. The elastomeric composition may be utilized as a component of a pneumatic tire. Also provided is a method of producing an elastomeric composition, wherein the composition comprises an elastomer; a reinforcing filler comprising silica; an organosilane polysulfide; and a blocked mercaptosilane, wherein the weight ratio of the blocked mercaptosilane to the organosilane polysulfide is about 0.25:1 to about 5:1.