Precipitated Silica Core-Shell Structure for Elastomer Dispersion
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Solution Overview
Problem
Existing precipitated silica products for use in elastomeric compositions have limitations in terms of dispersability and wear resistance, particularly due to homogeneous particle aggregates rather than inhomogeneous core/shell structures.
Innovation Solution
A precipitated silica characterized by a specific set of properties, including a CTAB surface area between 40 to 525 m2/g, primary particles with an average size below 15 nm, a high proportion of particles less than 1 μm after deagglomeration, and a defined particle size distribution, which facilitates improved dispersion and reinforcement in elastomeric compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If homogeneous particle aggregates are used in precipitated silica, then manufacturing simplicity is maintained, but dispersability and wear resistance in elastomeric compositions deteriorate
Solution Approach 1:
The patent applies local quality by creating aggregates with non-uniform internal structure where the core region has different properties (larger primary particles, higher density) compared to the shell region (smaller primary particles, lower density). This core/shell structure with radial gradient in particle size and density provides both improved dispersability (due to friable core) and wear resistance (due to protective shell), resolving the contradiction between manufacturing simplicity and performance reliability
Solution Approach 2:
The patent creates composite-like structures within the aggregates by combining primary particles of different sizes and densities in a core/shell arrangement. The heterogeneous composition with distinct core and shell regions having different physical properties enables simultaneous achievement of good dispersability and wear resistance, overcoming the limitations of homogeneous aggregates
2Reliability
If small primary particles are used to improve dispersion, then dispersability improves, but aggregate strength decreases leading to poor wear resistance
Solution Approach 1:
The patent uses local quality by positioning different particle sizes in different regions of the aggregate: smaller primary particles (5-15 nm) in the shell provide good dispersability and surface area, while larger primary particles in the core provide structural strength and wear resistance. This spatial differentiation resolves the contradiction between dispersability and aggregate strength
Solution Approach 2:
The patent creates a composite structure within aggregates by combining primary particles of different sizes and densities. The heterogeneous arrangement with small particles in the shell and larger particles in the core enables the aggregate to simultaneously exhibit good dispersability (from shell) and wear resistance (from core), resolving the contradiction between these two properties
3Strength
If high surface area silica is used to improve reinforcement, then mechanical properties improve, but particle aggregation increases reducing dispersability
Solution Approach 1:
The patent applies local quality by creating aggregates with radial gradients in particle size and density, where the shell region contains smaller particles providing high surface area for reinforcement, while the core contains larger particles that prevent excessive aggregation. This spatial differentiation allows high surface area utilization without severe aggregation, resolving the contradiction between reinforcement and dispersability
Solution Approach 2:
The patent creates composite-like structures within aggregates combining primary particles of different sizes. The heterogeneous composition with small high-surface-area particles in the shell and larger particles in the core enables simultaneous achievement of mechanical reinforcement (from high surface area) and dispersability (from controlled aggregation structure)
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 described precipitated silica achieves enhanced dispersion and wear resistance in elastomeric compositions, leading to improved mechanical properties and handling performance.
Implementation Method 1
simultaneously adding to the reaction medium a silicate and an acid, such that the pH of the reaction medium is maintained in the range from 7.00 to 10.00... stopping the addition of the silicate while continuing the addition of the acid to the reaction medium to reach a pH of the reaction medium of less than 6.00 and obtaining a suspension of precipitated silica
Implementation Method 2
a proportion (by weight) of particles of a size less than 1 μm after deagglomeration by ultrasounds
Data Source
AI summary
The present invention relates to precipitated silica having an improved dispersability and to a process for its manufacture. The invention further relates to the use of precipitated silica as reinforcing filler in polymeric compositions, preferably elastomeric compositions.