Polyisocyanate Residue Concentration and Viscosity Control
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Solution Overview
Problem
The concentration of polyisocyanate residues from crude polyisocyanate using evaporation methods leads to incomplete removal of Cl-containing gases, causing thermal polymerization and increased viscosity, resulting in unstable transport and potential blockages in transport lines.
Innovation Solution
A two-stage concentrating method involving a distiller for initial heating to a midterm concentrating rate and a thin film evaporator for final evaporation, ensuring removal of Cl-containing gases and reducing thermal polymerization, along with a treating method using high-temperature and high-pressure water to decompose the residues into polyamine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If evaporation operation is used to concentrate polyisocyanate residues, then concentration time is shortened, but Cl-containing gas removal is insufficient
Solution Approach 1:
The concentration process is divided into two distinct stages: a distillation stage for removing Cl-containing gases and a thin film evaporation stage for final concentration. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between speed and completeness.
Solution Approach 2:
The distillation stage is performed as a preliminary action before the thin film evaporation stage. This preliminary removal of Cl-containing gases prevents them from causing thermal polymerization during the subsequent rapid evaporation process, enabling both fast concentration and complete gas removal.
2Productivity
If heat is applied to concentrate polyisocyanate residues, then concentration is achieved, but thermal polymerization occurs
Solution Approach 1:
The heating process is segmented into two phases with different temperature profiles: a moderate heating distillation phase for gas removal and a rapid evaporation phase for concentration. This segmentation allows efficient concentration while minimizing thermal polymerization through controlled temperature application.
Solution Approach 2:
The thin film evaporation stage rapidly concentrates the residue by skipping the intermediate slow heating phase. This rushing through the concentration process minimizes the total heat history and reduces thermal polymerization while maintaining high productivity.
3Quantity of substance
If polyisocyanate residues are concentrated to high concentration, then viscosity increases, but transport stability deteriorates
Solution Approach 1:
Cl-containing gases are removed as a preliminary action before final concentration. This prevents the gases from causing thermal polymerization that would increase viscosity, thereby maintaining transport stability even at high concentrations.
Solution Approach 2:
The harmful Cl-containing gases are extracted and removed from the system during the distillation stage. This extraction eliminates the cause of viscosity increase and thermal polymerization, allowing stable transport of highly concentrated residues.
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 effectively concentrates polyisocyanate residues in a short time, stabilizes transport, prevents line blockages, and achieves high recovery rates of polyamine by minimizing heat history and viscosity increases.
Implementation Method 1
a first concentrating process of concentrating the polyisocyanate residues from the crude polyisocyanate to a midterm concentrating rate on the way to a final concentrating rate by heating the crude polyisocyanate on the boil
Implementation Method 2
heating the crude polyisocyanate on the boil
Implementation Method 3
a second concentrating process of concentrating the first concentrated component concentrated in the first concentrating process to the final concentrating rate by evaporation
Implementation Method 4
a treating method for polyisocyanate residues wherein a second concentrated component obtained by the concentrating method is put in contact with high temperature and high pressure water, whereby it is decomposed to polyamine
Data Source
AI summary
A concentrating method and a concentrating system for concentrating polyisocyanate residues that that can effectively concentrate polyisocyanate residues from crude polyisocyanate comprising polyisocyanate and polyisocyanate residues in a short time and can also suppress increase in viscosity to provide stable transport of the residues and prevent blockage of the transport line, and a treating method and a treating system for decomposing the concentrated components to polyamine.The polyisocyanate residues are first heated on the boil by the distiller to be concentrated to a midterm concentrating rate, and then, the polyisocyanate residues are concentrated to the final concentrating rate by evaporation using a evaporator. This can allow the polyisocyanate residues to be decomposed to polyamine to be recovered by setting a Cl content of a high boiling point distillate fraction concentrated to be not more than 2 weight % and then putting the high boiling point distillate fraction into contact with high temperature and high pressure water to be hydrolyzed by the decomposing apparatus.