Polyimide Precursor Solution Viscosity Stabilization
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Solution Overview
Problem
Polyimide precursor solutions with high molecular weight polyimide precursors experience significant changes in viscosity during storage, leading to issues like cissing and non-uniform film thickness in polyimide film production, due to partial imidization or hydrolysis.
Innovation Solution
A polyimide precursor solution with a weight average molecular weight of 40,000 or more, containing a tertiary amine compound and water as an aqueous solvent, is maintained at a pH of 6.5 to 7.5 at 50°C to stabilize viscosity, preventing imidization and hydrolysis, and optionally includes resin particles to ensure consistent film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polyimide precursor solution containing a polyimide precursor with high molecular weight (40,000 or more) and an aqueous solvent containing a tertiary amine compound is used, then the solution initially has good solubility and processability, but the viscosity changes significantly during storage due to partial imidization or hydrolysis
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pH of the polyimide precursor solution to be in the range of 6.5 to 7.5 at 50°C. This specific pH parameter control prevents both imidization (which would increase viscosity) and hydrolysis (which would decrease viscosity), thereby maintaining viscosity stability during storage while preserving the solubility and processability provided by the high molecular weight polyimide precursor and tertiary amine compound
2Ease of manufacture
If the pH of the polyimide precursor solution is not controlled within the range of 6.5 to 7.5 at 50°C, then the solution may have easier initial preparation, but the viscosity changes significantly during storage leading to cissing and non-uniform film thickness
Solution Approach 1:
The patent implements parameter changes by establishing a specific pH range (6.5 to 7.5 at 50°C) that simultaneously achieves easy solution preparation and high film thickness uniformity. This pH control prevents viscosity changes during storage that would otherwise cause cissing and non-uniform film formation, thereby resolving the contradiction between ease of preparation and manufacturing precision
Solution Approach 2:
The patent employs a water-based aqueous solvent system with tertiary amine compounds that provides adequate stability during the typical storage period (up to 14 days) without requiring complex stabilizing additives or preservatives. This approach maintains film thickness uniformity while keeping the preparation process simple and cost-effective
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 solution results in a polyimide precursor solution with minimal viscosity change during storage, ensuring consistent film quality and surface shape, even after 14 days, by controlling pH and using tertiary amine compounds like N-methylmorpholine.
Implementation Method 1
maintained at a pH of 6.5 to 7.5 at 50°C to stabilize viscosity, preventing imidization and hydrolysis
Implementation Method 2
preventing imidization and hydrolysis
Implementation Method 3
stabilize viscosity, preventing imidization and hydrolysis
Data Source
AI summary
A polyimide precursor solution contains a polyimide precursor having a weight average molecular weight of 40,000 or more, and an aqueous solvent containing a tertiary amine compound and water, in which a viscosity of the polyimide precursor solution after a storage at 25°C for 14 days is 50% or more and 200% or less with respect to a viscosity of the polyimide precursor solution before the storage.