Aqueous Polyimide Precursor Production via Imidazole Catalysis

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Solution Overview

Problem

Existing methods for producing aqueous polyimide precursor solutions often require organic solvents, leading to environmental concerns and limitations in achieving high molecular weight polyimides with excellent properties like heat resistance and crystallinity.

Innovation Solution

A method involving the reaction of tetracarboxylic dianhydride and diamine in the presence of imidazole using water as a solvent, with specific conditions to minimize organic solvent content and achieve high molecular weight polyamic acids, which are then processed to form aromatic polyimides with enhanced properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If organic solvents are used to dissolve polyamic acid, then solubility is improved, but environmental acceptability deteriorates

Engineering Contradiction:

ImprovesolubilityVSAvoidenvironmental acceptability

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the solvent system from organic to aqueous by adjusting the chemical environment (pH, ionic strength) to enable polyamic acid dissolution in water, thereby eliminating organic solvents while maintaining solubility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces salts and pH adjusters as intermediary substances that mediate between the polyamic acid and water, enabling solubility in aqueous environment without requiring organic solvents

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If high molecular weight polyamic acid is produced, then polyimide properties are improved, but solution viscosity increases making handling difficult

Engineering Contradiction:

Improvepolyimide propertiesVSAvoidhandling ease

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent adjusts solution parameters (pH, salt concentration, temperature) to optimize the balance between molecular weight and solution viscosity, enabling high molecular weight polyamic acid to be handled as a workable aqueous solution

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses salts and pH adjusters as intermediaries that control the conformation and interaction of polyamic acid chains in solution, reducing viscosity while maintaining high molecular weight

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If aqueous solvent is used instead of organic solvent, then environmental acceptability is improved, but solubility of polyamic acid deteriorates

Engineering Contradiction:

Improveenvironmental acceptabilityVSAvoidsolubility

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent systematically adjusts aqueous solution parameters (pH, ionic strength, temperature) to enhance polyamic acid solubility in water, making aqueous processing feasible without organic solvents

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces salts and pH control agents as intermediaries that facilitate the interaction between polyamic acid and water, enabling dissolution in aqueous environment

Inventive Principle:

Principle #24Intermediary (Mediator)

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 allows for the production of aqueous polyimide precursor solutions with low organic solvent content, resulting in aromatic polyimides with high crystallinity and excellent properties such as heat resistance, mechanical strength, and electrical properties, suitable for various applications including electrodes and flexible device substrates.

Implementation Method 1

reacting a tetracarboxylic dianhydride and a diamine, which has a solubility in water at 25° C. of 0.1 g/L or more, in the presence of an imidazole using water as a reaction solvent to provide an aqueous polyimide precursor solution composition

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

using water as a reaction solvent to provide an aqueous polyimide precursor solution composition

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 3

heating the solution composition at a high temperature to effect dehydration/ring closure (imidization)

Methodology Applied

Scientific EffectDehydration:

Data Source

PatentUS11401418B2Method for producing aqueous polyimide precursor solution composition

Publication Date: 2022.08.02 UBE CORPORATION

AI summary

A method for producing an aqueous polyimide precursor solution composition includes reacting a tetracarboxylic dianhydride and a diamine in the presence of an imidazole, using water as a reaction solvent to provide an aqueous polyimide precursor solution composition. The polyamic acid and the imidazole are dissolved in the water. A concentration of the polyamic acid is 5 to 45 wt %, The imidazole is an imidazole having two or more alkyl groups as substituents. An amount of the imidazole is 1.6 moles or more per mole of the tetracarboxylic dianhydride, and a concentration of the imidazole compound based on a sum of the imidazole compound and the water is 9.47 wt % or less. The diamine component includes a diamine having a solubility in water at 25° C. of 0.1 g/L or more.