Common Aliphatic Medium for Halogenated Rubber Production
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Solution Overview
Problem
Conventional processes for producing halogenated rubbers are inefficient in terms of energy and raw material consumption, and they require separate media for polymerization and halogenation, leading to high energy usage and the formation of undesirable by-products due to residual monomers.
Innovation Solution
A process using a common aliphatic medium for both solution polymerization and halogenation, where residual monomers are separated by distillation, allowing for higher monomer levels and reduced viscosity, thereby improving energy efficiency and eliminating the need for intermediate solvent stripping and re-dissolution steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a common aliphatic medium is used for both polymerization and halogenation, then energy consumption is reduced and process efficiency is improved, but residual monomers must be removed to avoid formation of toxic by-products
Solution Approach 1:
The process is segmented into distinct operational phases: polymerization phase where monomers are converted to polymer in the aliphatic medium, followed by a separation phase where residual monomers are removed via distillation, and finally the halogenation phase where the purified polymer solution is halogenated. This segmentation allows the common medium to be used throughout while preventing harmful by-product formation through intermediate purification.
Solution Approach 2:
Residual monomers are removed from the polymer solution before the halogenation step through distillation. This preliminary removal action prevents the formation of toxic by-products during halogenation, as the monomers that would otherwise react with halogenating agents are eliminated in advance.
2Object-affected harmful factors
If residual monomers are removed by distillation before halogenation, then toxic by-products are avoided, but energy consumption increases
Solution Approach 1:
The aliphatic medium serves multiple functions throughout the process: it acts as the polymerization solvent, facilitates monomer removal through distillation (due to its volatility relative to the polymer), and serves as the halogenation medium. This multi-functionality consolidates what would otherwise require multiple different chemicals and separate processing steps into a single integrated process, reducing overall energy consumption despite the distillation step.
3Reliability
If separate media are used for polymerization and halogenation, then each step can be optimized, but intermediate stripping and dissolving steps are required increasing complexity
Solution Approach 1:
The polymerization and halogenation steps are merged into a single continuous process using the same aliphatic medium throughout. The polymerization reaction occurs in the aliphatic medium, residual monomers are removed by distillation, and halogenation proceeds in the same medium without requiring intermediate solvent removal and re-addition steps. This merging eliminates process complexity while maintaining optimization through careful selection of the aliphatic medium properties.
4Ease of operation
If iso-pentane is used as polymerization medium, then solution polymerization is achieved, but boiling point is too low for effective monomer separation
Solution Approach 1:
The process parameters are optimized by selecting aliphatic media with specific boiling point ranges (C6-C8 hydrocarbons like n-hexane, n-heptane, or n-octane). These media have boiling points high enough to allow effective distillation separation from heavier monomers like isoprene (bp 34°C), yet low enough to maintain good polymer solubility and facilitate the overall process. This parameter optimization resolves the contradiction between solution polymerization ease and monomer separation efficiency.
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 integrated process reduces energy consumption, raw material usage, and viscosity issues, enabling higher polymer solids levels and reducing the formation of undesirable by-products, resulting in a more efficient and environmentally favorable production method for halogenated rubbers.
Implementation Method 1
a rubber solution comprising a rubber polymer which is at least substantially dissolved in the medium
Implementation Method 2
separating residual monomers of the monomer mixture from the rubber solution to form a separated rubber solution
Implementation Method 3
halogenating the rubber in the separated rubber solution using a halogenating agent
Data Source
AI summary
The invention relates to an energy efficient, environmentally favorable process for the preparation of halogenated rubbers, in particular chloro- and bromobutyl rubber, that uses a common aliphatic medium of specific composition for both solution polymerization and subsequent halogenation of the rubber. More particularly, the invention relates to a process that employs a common aliphatic medium for both solution polymerization and halogenation of rubber with intermediate removal of un-reacted monomers.