Silica Masterbatch via Emulsion and Solution Rubber Mixing
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Solution Overview
Problem
The existing methods for making silica-filled rubber masterbatch using rubber made in a solution process have not been economically viable, as the incompatibility between inorganic silica and rubber made in an organic solvent has not been satisfactorily overcome, leading to poor dispersion and performance issues in final rubber products.
Innovation Solution
A process involving the hydrophobation of silica using trimethoxy silane coupling agents in a mixture with alcohol and water, followed by mixing with solution-made rubber in a polymer latex, and coagulating to form a silica-filled rubber masterbatch that includes both emulsion-made and solution-made rubber, ensuring homogeneous mixing and improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silica is mixed with solution-made rubber using conventional dry mixing process, then silica can be incorporated into rubber, but the mixing process is time-consuming and energy-intensive requiring 10 minutes or longer in a Banbury rubber mixer
Solution Approach 1:
The patent combines the silica hydrophobation process with the rubber compounding process into a single integrated operation. Silica is hydrophobated in situ within the rubber compound using a two-roll mill, eliminating the need for separate mixing steps. This merging of operations allows silica incorporation to occur during the compounding process itself, dramatically improving productivity while maintaining complete silica incorporation.
Solution Approach 2:
The patent uses a silane coupling agent as an intermediary substance that facilitates the bonding between inorganic silica and organic solution-made rubber. The silane acts as a chemical mediator that reacts with both the silica surface and the rubber matrix, enabling effective silica incorporation without requiring extended mechanical mixing times. This intermediary approach allows the process to complete in minutes rather than 10 minutes or longer.
2Stability of the object's composition
If silica is hydrophobated with silane compounds using conventional dry mixing, then silica becomes compatible with rubber, but ethanol from the silane must be removed requiring extra equipment to isolate or burn the alcohol
Solution Approach 1:
The patent extracts the ethanol removal step from the overall process by allowing the ethanol to evaporate naturally during the compounding operation on the two-roll mill. The heat and airflow inherent in the milling process suffice to remove the ethanol without requiring additional isolation or combustion equipment. This extraction of the ethanol removal function simplifies the equipment requirements while maintaining silica-rubber compatibility.
Solution Approach 2:
The compounding process itself provides the conditions necessary for ethanol removal. The two-roll mill operation generates sufficient heat and airflow to evaporate the ethanol byproduct of the silane reaction, making the system self-sufficient. No external equipment is needed to handle the ethanol, as the primary processing equipment performs both compounding and solvent removal functions simultaneously.
3Quantity of substance
If conventional dry mixing process is used to incorporate silica into rubber, then silica can be blended into rubber, but the process requires a great deal of time, capital and operating and maintenance expense
Solution Approach 1:
The patent merges silica hydrophobation, silica dispersion, and rubber compounding into a single integrated process step performed on a two-roll mill. This consolidation eliminates multiple separate operations (hydrophobation in Banbury mixer, then remilling for dispersion, then final mixing with curatives), reducing both time and equipment usage. The manufacturing cost is reduced because the same equipment performs multiple functions that previously required separate specialized equipment.
Solution Approach 2:
The patent changes the fundamental parameters of the mixing process by transitioning from extended mechanical mixing at controlled temperatures to a rapid shear-mixing process on two-roll mills. The high shear rates and shorter residence times achieve complete silica incorporation and dispersion without requiring the extended 10-minute mixing cycles of conventional Banbury mixers, thereby reducing energy consumption and equipment operational costs.
4Quantity of substance
If inorganic silica is mixed with solution-made rubber in organic solvent, then silica can be incorporated, but the incompatibility between inorganic silica and rubber made in organic solvent has not been satisfactorily overcome
Solution Approach 1:
The patent changes the chemical state of the silica surface by applying hydrophobation treatment with silane compounds. This parameter change transforms the inorganic silica surface from hydrophilic to hydrophobic, making it compatible with the organic solution-made rubber. The silane-modified silica surface can now interact effectively with the organic solvent and rubber polymer chains, achieving homogeneous dispersion that was previously unattainable with untreated silica.
Solution Approach 2:
The silane coupling agent serves as a chemical intermediary that bridges the incompatibility between inorganic silica and organic solution rubber. The silane molecule reacts with both the silica surface and the rubber matrix, creating a compatible interface. This intermediary approach resolves the fundamental incompatibility issue, allowing complete silica incorporation with uniform dispersion throughout the rubber 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 process results in a silica-filled rubber masterbatch with excellent wet skid resistance, hysteresis loss, abrasion resistance, and mechanical strength, suitable for tire treads, and allows for the efficient incorporation of high-surface-area silica, improving tire performance without the need for additional processing steps.
Implementation Method 1
hydrophobation of silica using trimethoxy silane coupling agents
Implementation Method 2
coagulating to form a silica-filled rubber masterbatch
Data Source
AI summary
The present invention provides a process for making a silica masterbatch that contains hydrophobated silica, solution-made rubber and emulsion-made rubber. Hydrophobated silica is mixed into a latex emulsion. Solution-rubber crumb in an aqueous suspension is mixed into the latex emulsion, which is coagulated, and a crumb is recovered, further homogenized, dried and baled to yield the silica masterbatch. A well-dispersed mixture of hydrophobated silica and emulsion-made rubber is added into a steam distillation step of a solution-rubber process from which a silica masterbatch is recovered. The emulsion-made rubber can be omitted to make a silica masterbatch of solution rubber and silica without emulsion rubber. The silica masterbatch has physical properties similar to those found in a comparable dry-mixed composition, but the silica masterbatch can be incorporated more easily and less expensively into tires and other rubber products than the dry-mixed composition.