1,6-Hexanediol Distillation for Low Aldehyde Content
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Solution Overview
Problem
Commercially available 1,6-hexanediol contains aldehyde impurities that limit its application in producing plastics, as they affect color stability and lead to chain termination or branching in polyesters, necessitating a method to produce 1,6-hexanediol with an aldehyde content of less than 500 ppm and a color number of less than 150 APHA-Hazen.
Innovation Solution
A process involving the reaction of 1,6-hexanediol with dicarboxylic acids or diisocyanates, followed by distillation under controlled oxygen and catalytically active component levels, ensuring a molar ratio of oxygen to 1,6-hexanediol is less than 1:100 and catalytically active components are below 5 ppm, to achieve a purity of over 97% and an aldehyde content of less than 500 ppm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If commercially available 1,6-hexanediol is used for plastic production, then the production process is simple and fast, but the aldehyde content is high (up to 0.1% by weight) which limits application range and affects color stability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxygen content parameter during distillation (maintaining molar ratio below 1:100) and catalytically active component levels (below 5 ppm) to achieve the desired aldehyde content reduction from 0.1% to below 500 ppm while managing process complexity
Solution Approach 2:
The patent creates an inert atmosphere during distillation by strictly limiting oxygen presence (molar ratio of oxygen to 1,6-hexanediol less than 1:100), which prevents oxidative formation of aldehydes and maintains color stability of the product
2Reliability
If 1,6-hexanediol with low aldehyde content is produced through strict distillation control, then color stability and purity are improved, but the distillation process becomes more complex with strict oxygen and catalyst control requirements
Solution Approach 1:
The patent applies preliminary action by removing catalytically active components before distillation (reducing to ≤5 ppm residual content) and pre-establishing oxygen-free conditions, which prevents aldehyde formation during distillation and simplifies the overall control requirements
Solution Approach 2:
The patent implements feedback control by monitoring and adjusting oxygen content and catalytically active component levels during distillation to maintain the molar ratio of oxygen to 1,6-hexanediol below 1:100 and catalytic components below 5 ppm, ensuring consistent color stability
3Ease of manufacture
If oxygen is present during distillation of 1,6-hexanediol, then the distillation process is simpler with atmospheric conditions, but aldehyde content increases due to oxidative reactions
Solution Approach 1:
The patent creates an inert atmosphere during distillation by strictly limiting oxygen presence (molar ratio of oxygen to 1,6-hexanediol less than 1:100), which prevents oxidative formation of aldehydes while maintaining manageable distillation operations through controlled inert conditions
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
The process effectively reduces the aldehyde content and color number of 1,6-hexanediol, enabling the production of plastics with improved color stability and purity, suitable for producing polyesters and polyurethanes with color numbers below 150 APHA-Hazen.
Implementation Method 1
distillation of the mixture containing from step I or II, the molar ratio of oxygen to 1,6-hexanediol during the distillation is less than 1:100
Implementation Method 2
the molar ratio of oxygen to 1,6-hexanediol during the distillation is less than 1:100... has an aldehyde content of less than 500 ppm
Implementation Method 3
contains less than 5 ppm of catalytically active, in particular dehydrogenating, components during the distillation
Data Source
AI summary
The invention relates to a method for producing plastics using 1,6-hexanediol with an aldehyde content of less than 500 ppm, to a method for producing 1,6-hexanediol with an aldehyde content of less than 500 ppm, and to 1,6-hexanediol with an aldehyde content of less than 500 ppm.