Polyamideimide Copolymer Scratch Resistance Transparency
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Solution Overview
Problem
Polyamideimide copolymers struggle to achieve both excellent scratch resistance and transparency due to issues like haze and coloration, particularly in thicker films, which affect mechanical properties and yellow index.
Innovation Solution
A polyamideimide copolymer is developed by copolymerizing an aromatic diamine monomer, an aromatic dianhydride monomer, and an aromatic dicarbonyl monomer, with the aromatic dicarbonyl monomer comprising 10 to 40 mol % isophthaloyl chloride and 60 to 90 mol % terephthaloyl chloride, minimizing crystallization and optimizing the molar ratio for enhanced scratch resistance and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyamideimide copolymer is used to improve scratch resistance, then mechanical strength is improved, but haze increases and transparency deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar ratio of aromatic dicarbonyl monomer to aromatic dianhydride monomer at 0.6 or higher, and controlling the yellow index at 3.0 or lower. These parameter optimizations resolve the contradiction by achieving both high scratch resistance through sufficient polyamide content and low haze through controlled yellow index and crystallinity prevention.
Solution Approach 2:
The patent uses composite material principles by creating a copolymer system combining polyimide and polyamideimide segments. This composite structure allows the material to exhibit both the heat resistance of polyimide and the scratch resistance of polyamideimide, while controlling the overall haze by managing the copolymer composition and preventing crystallization.
2Strength
If film thickness is increased to improve mechanical properties, then strength is improved, but yellow index increases and transparency deteriorates
Solution Approach 1:
The patent applies parameter changes by establishing a threshold yellow index of 3.0 or lower and a specific molar ratio of 0.6 or higher. These parameters enable the production of thicker films with improved mechanical properties while maintaining transparency, as the controlled yellow index prevents excessive coloration even in thicker sections.
Solution Approach 2:
Instead of accepting that thicker films naturally develop higher yellow indices, the patent inverts this relationship by using specific monomer ratios and controlling the polyamic acid composition to achieve low yellow index (≤3.0) even in thicker films, thereby decoupling film thickness from yellow index increase.
3Strength
If aromatic dicarbonyl monomer content is increased to improve scratch resistance, then mechanical strength is improved, but crystallinity increases and haze worsens
Solution Approach 1:
The patent applies parameter changes by setting the molar ratio of aromatic dicarbonyl monomer to aromatic dianhydride monomer at 0.6 or higher while simultaneously controlling the yellow index at 3.0 or lower. This dual parameter control allows increased polyamideimide content for scratch resistance while preventing excessive crystallinity that would cause haze.
Solution Approach 2:
The patent applies local quality by creating specific structural characteristics in the copolymer chain through the use of particular aromatic dicarbonyl monomers (such as terephthaloyl chloride and isophthaloyl chloride in specific ratios). This local structural optimization provides scratch resistance at the molecular level while maintaining amorphous character that prevents haze.
Data Source
AI summary
A polyamideimide copolymer which is an imide of a polyamic acid resulting from copolymerizing an aromatic diamine monomer, an aromatic dianhydride monomer, and an aromatic dicarbonyl monomer and a colorless and transparent polyamideimide film including the polyamideimide copolymer. The polyamideimide copolymer according to the present disclosure makes it possible to provide a polyamideimide film exhibiting excellent scratch resistance while being colorless and transparent.