Precipitated Silica pH Control for Tire Tread Dispersibility
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Solution Overview
Problem
Existing precipitated silicas exhibit limited dispersibility in high-surface-area applications, particularly in green tire mixtures, leading to suboptimal reinforcement properties and incomplete abrasion resistance in tire tread compounds.
Innovation Solution
Development of precipitated silicas with specific physicochemical parameters, including CTAB surface area, BET/CTAB ratio, tailing factor, and Ro-Tap value, achieved through controlled pH adjustments and stirring processes using sulfuric acid and waterglass, resulting in improved dispersibility and reinforcement characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If precipitated silica with high surface area is used to improve reinforcement properties, then reinforcement characteristics are improved, but dispersibility deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pH of the reaction medium during silica precipitation. The process maintains pH between 7.0-10.0 during simultaneous addition of silicate and acidifying agent, which controls the morphology and surface properties of the precipitated silica particles. This pH control enables the production of silica with optimized surface area (100-200 m²/g) and particle characteristics that achieve both high reinforcement and good dispersibility in rubber compounds.
2Manufacturing precision
If constant AV (alkali value) is maintained during production to ensure consistent quality, then manufacturing precision is improved, but productivity decreases due to extended process time
Solution Approach 1:
The patent implements continuity of useful action through the simultaneous addition of silicate and acidifying agent to the reaction medium. This continuous coprecipitation process maintains constant pH (7.0-10.0) throughout the reaction, ensuring uniform nucleation and particle growth. The continuous process eliminates batch-wise pH adjustments and achieves consistent AV (alkali value) and particle properties while reducing total processing time compared to sequential addition methods.
3Manufacturing precision
If multiple pH adjustment steps are performed to optimize silica properties, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the addition of silicate and acidifying agent into a single simultaneous operation rather than separate sequential steps. By adding both reagents together to the reaction medium while maintaining pH between 7.0-10.0, the process combines nucleation and particle growth control in one continuous action. This merging simplifies the process equipment and operation while achieving precise control over silica particle morphology, surface area, and dispersibility properties.
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 silicas provide enhanced dispersibility and reinforcement, leading to prolonged tire life through optimized abrasion resistance without compromising other tire properties.
Implementation Method 1
the reaction of the silicate with the acidifying agent, which affords a silica suspension
Implementation Method 2
reaction of the silicate with the acidifying agent
Implementation Method 3
the pH of the reaction medium is kept between 7 and 10
Implementation Method 4
simultaneously adding silicate and acidifying agent to the reaction medium
Implementation Method 5
the separation and drying of that suspension
Implementation Method 6
the separation and drying of that suspension
Data Source
Figure 1
AI summary
The invention relates to precipitated silicas having the following physicochemical parameters: CTAB 50 m²/g – 450 m²/g, BET/CTAB ratio < 1.3, tailing factor 5% ≥ 150 nm. The precipitated silicas are produced by reacting waterglass with H2SO4 using various ageing steps. The precipitated silicas can be used for production of rubber mixtures.