Common Solvent Process for Halobutyl Rubber Production
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Solution Overview
Problem
Conventional processes for producing halobutyl rubber require separate media for polymerization and halogenation, leading to inefficiencies in energy usage and the formation of undesirable by-products due to the need for intermediate stripping and re-dissolving steps, and struggle with achieving high rubber solids levels due to high solution viscosity.
Innovation Solution
An integrated process using a common aliphatic medium, such as C6 solvent, for both solution polymerization and halogenation, allowing for the separation of residual monomers through distillation and maintaining a higher monomer-to-solvent ratio to reduce viscosity and enable higher polymer solids levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a common aliphatic medium is used for both polymerization and halogenation, then energy efficiency is improved and process steps are reduced, but residual monomers must be removed to avoid toxic by-products
Solution Approach 1:
The patent applies preliminary action by removing residual monomers from the polymer solution before conducting the halogenation reaction. This is achieved through distillation or extraction steps that eliminate unreacted isobutylene and isoprene from the butyl rubber solution prior to adding halogenating agents, thereby preventing the formation of toxic halogenated by-products while maintaining the energy benefits of a common solvent system
Solution Approach 2:
The patent applies extraction by separating and removing residual monomers from the polymer solution using appropriate separation techniques such as distillation or extraction with selective solvents. This removes the harmful components (unreacted monomers) from the system before halogenation, preventing toxic by-product formation while allowing the common aliphatic medium to be used throughout the process
2Quantity of substance
If C5 medium is used as common solvent, then separation of monomers is difficult due to similar boiling points, but C6 medium has higher viscosity limiting polymer solids content
Solution Approach 1:
The patent applies parameter changes by carefully controlling the composition of the C6 aliphatic medium, the temperature conditions during distillation, and the pressure parameters to achieve effective separation of residual monomers despite the viscosity constraints. By optimizing these parameters, the process achieves both adequate monomer removal and acceptable polymer solids content in the final product
3Object-affected harmful factors
If conventional slurry process is used, then monomer removal is effective, but intermediate stripping and re-dissolving steps increase energy consumption
Solution Approach 1:
The patent applies merging by combining the polymerization and halogenation steps into a single continuous process using a common aliphatic medium. The polymerization occurs in the C6 solvent, and after removing residual monomers through distillation or extraction, the same medium serves as the halogenation medium, eliminating the need for separate stripping and re-dissolving operations required in conventional slurry processes
Solution Approach 2:
The patent applies universality by using the C6 aliphatic medium to serve multiple functions throughout the process: it acts as the polymerization solvent, serves as the medium for monomer removal operations, and functions as the halogenation medium. This multi-functional use of a single solvent system eliminates the need for multiple solvent transitions and intermediate processing steps
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 approach improves energy efficiency, reduces the number of process steps, and mitigates the formation of undesirable by-products by using a single solvent for both polymerization and halogenation, allowing for higher polymer solids levels and more economical production of halobutyl rubber.
Implementation Method 1
a solution polymerization reactor containing the C6 aliphatic medium mixed with a monomer mixture
Implementation Method 2
separating the monomer mixture from the polymer solution
Implementation Method 3
polymerizing the monomer mixture within the medium to form a polymer solution
Data Source
AI summary
An integrated process for the solution polymerization and subsequent halogenation of butyl rubber in a common medium is disclosed. The process comprises providing a solution polymerization reactor containing a C6 medium mixed with a monomer mixture comprising at least an isoolefin monomer and a multiolefin monomer in a mass ratio of monomer mixture to medium of from 61:39 to 80:20. Once polymerized, residual unreacted monomer mixture is separated from the rubber solution using a distillation process. The residual monomers may then be purified and recycled back into the reactor. The separated rubber solution is then halogenated. The process obviates the need for separating the rubber from the medium following polymerization, then re-dissolving it in another solvent for halogenation, thereby saving energy cost. The process optionally employs heat exchangers for the reactor feed streams to further reduce energy consumption.