Imidized Polymer Preparation via Twin-Screw Extrusion
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Solution Overview
Problem
Existing methods for preparing imidized polymers as multifunctional viscosity modifiers result in low conversion rates of anhydride groups to imide groups, leading to increased viscosity and sensitivity to oxidation, requiring additional additives to cap unreacted groups and prevent discoloration.
Innovation Solution
A process involving a reaction between a polymer with anhydride groups and an aromatic polyamine compound is carried out in the presence of an acid, specifically using a co-rotating twin-screw extruder with a static mixer and degassing extruder, to achieve high conversion rates of anhydride groups to imide groups, reducing residual acyl and amine groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the imidization reaction is carried out using conventional extrusion methods, then the process is simple, but the conversion rate of anhydride groups to imide groups is low (not more than 80%)
Solution Approach 1:
The reaction process is divided into distinct zones within the extruder: a first reaction zone where imidization occurs, followed by a second reaction zone where residual anhydride groups are converted to amide groups. This segmentation allows each zone to optimize for its specific function, achieving both high conversion rate and process simplicity.
Solution Approach 2:
The first reaction zone performs the primary imidization reaction to convert anhydride groups to imide groups before the material enters the second reaction zone. This preliminary action ensures that the majority of conversion occurs in the first zone, while the second zone completes the conversion of residual groups, thereby achieving high overall conversion efficiency.
2Productivity
If the reaction is carried out without converting residual anhydride groups, then the process is shorter, but the remaining acyl and amine groups cause viscosity increases and discoloration
Solution Approach 1:
The residual anhydride groups, which would otherwise cause harmful effects (viscosity increase and discoloration), are converted into beneficial amide groups in the second reaction zone. This transformation eliminates the harmful properties while maintaining the process efficiency, as the conversion occurs automatically during the extrusion process without requiring separate treatment steps.
3Reliability
If aromatic polyamines are used in the imidization reaction, then the basicity is maintained for reacting with acids, but the conversion rate is limited due to lower reactivity
Solution Approach 1:
The reaction conditions are optimized by controlling temperature and residence time in the two reaction zones. The first zone operates at conditions favorable for imidization with aromatic polyamines, while the second zone provides extended residence time and appropriate temperature to convert residual anhydride groups. This parameter optimization allows aromatic polyamines to maintain their basicity while achieving high conversion rates.
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 process increases the ratio of imide groups to total functional groups to above 0.85, stabilizing the product and reducing the need for extra additives, while preventing viscosity increases and discoloration, resulting in a solid multifunctional viscosity modifier with improved storage and shipping costs and base-oil independence.
Implementation Method 1
reacting in a mixing device or kneading device a polymer comprising anhydride groups, or derivatives thereof, with an aromatic polyamine compound... When an imide is formed, by a reaction of a polyamine, comprising at least one primary amine functionality with an anhydride group of the polymer
Implementation Method 2
degradation of the polymer can be promoted to a certain extend, by variation of temperature and shear
Data Source
AI summary
A process is provided for preparing an imidized polymer in a mixing or kneading device, by a reaction in the presence of an acid of a mixture containing a polymer having anhydride groups or derivatives thereof and an aromatic polyamine compound. A solid multifunctional viscosity modifier is also provided which includes a polymer having between 0.1 and 10 functional groups per 1000 C-atoms. The functional groups include aromatic amine based imide groups with a ratio of imide groups to the functional groups being more than 0.85.