Continuous Low-Alkoxy Branched Siloxane Production
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Solution Overview
Problem
The existing method for continuous production of low-alkoxy branched siloxanes faces challenges due to the accumulation of R3SiCl at the top of the column, leading to process termination and non-practicability, especially when synthesizing three-dimensionally crosslinked silicone oils and low-viscosity silicone resins.
Innovation Solution
A continuous method involving the reaction of silicon compounds with alcohol and water in a distillation column and a vessel, where silicon compound 2 is introduced directly into the vessel containing water, preventing the accumulation of R3SiCl by maintaining a higher water content and controlling hydrogen halide levels, allowing for the production of low-alkoxy branched siloxanes with high purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If silicon compound 2 (R13SiHal) is introduced into the distillation column to produce three-dimensionally crosslinked low-alkoxy organosiloxanes, then the desired product can be synthesized, but R3SiCl accumulates at the top of the column leading to process termination
Solution Approach 1:
The harmful R3SiCl that accumulates at the top of the distillation column is continuously extracted and removed from the system. A withdrawal line is provided at the top of the column to continuously remove R3SiCl, preventing its accumulation and the resulting gelling phenomena that would terminate the process.
Solution Approach 2:
An intermediate storage tank is introduced between the distillation column and the reaction system. This intermediate tank serves as a buffer that decouples the continuous removal of R3SiCl from the top of the column from the continuous feeding requirements, allowing independent optimization of both processes and preventing process termination.
2Manufacturing precision
If high concentration of trialkylsilyl units (R3Si-) is used to achieve three-dimensional crosslinking, then the desired silicone oils and resins can be produced, but R3SiCl accumulation occurs leading to non-practicability
Solution Approach 1:
The process operates continuously with simultaneous introduction of silicon compounds, continuous removal of R3SiCl, and constant replenishment of water and alcohol. This continuous operation maintains the high concentration of trialkylsilyl units needed for three-dimensional crosslinking while preventing R3SiCl accumulation through uninterrupted removal.
Solution Approach 2:
The system dynamically adjusts parameters including the rate of silicon compound introduction, the rate of R3SiCl removal, water addition rate, and alcohol addition rate to maintain optimal conditions for three-dimensional crosslinking while preventing harmful accumulation. The intermediate tank level and composition are continuously monitored and adjusted.
3Reliability
If continuous removal of R3SiCl is implemented to prevent accumulation, then process stability is improved, but device complexity increases due to additional withdrawal lines and intermediate tanks
Solution Approach 1:
The intermediate storage tank serves multiple functions: it acts as a buffer for R3SiCl removal, a mixing zone for reactants, a level control point, and a decoupling element between the distillation column and reaction system. This multi-functionality reduces the need for additional specialized equipment despite the increased process complexity.
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 method enables the continuous production of low-alkoxy branched siloxanes with improved throughput and purity, preventing gelling phenomena and allowing for the production of low-viscosity organosiloxanes with controlled hydrogen halide levels, making the process more efficient and practical.
Implementation Method 1
hydrogen halide formed during the process is removed by means of the distillation column
Implementation Method 2
the content of the vessel is heated to boiling under reflux
Data Source
AI summary
Branched organopolysiloxanes and organopolysiloxanes with low alkoxy content are produced in a first reaction unit by continuous feed of organohalosilanes and alcohol to a reaction vessel surmounted by a distillation column, the vessel containing an excess of water relative to the halogen content of the organohalosilanes. A second reaction unit for removing volatiles from the product from the first reaction unit is also preferably employed.