Polyimide Optical Member with Trans-1,4-Cyclohexylene for Antireflection
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Solution Overview
Problem
There is a demand for an optical member with high antireflection performance that remains effective over time, retains transparency after processing, and has high heat resistance, while also being soluble in organic solvents, without causing thermal damage to substrates or exhibiting cracking due to variations in film thickness or optical properties.
Innovation Solution
A laminated optical member comprising a polyimide layer with a repeating unit containing a 1,4-cyclohexylene group and a low-refractive index layer, where the polyimide layer is formed with a thickness between 10 nm and 150 nm, and a textured aluminum oxide structure is applied on the surface to enhance antireflection, using a method that includes purification of diamines to ensure a high trans-1,4-cyclohexylene content and reaction with acid dianhydrides to achieve the desired properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polyimide with high transparency is synthesized by introducing an aliphatic structure, then transparency is improved, but heat resistance and mechanical characteristics deteriorate
Solution Approach 1:
The patent changes the chemical structure parameters by introducing a specific alicyclic structure with a 1,4-cyclohexylene group and a carbonyl group in the imide ring. This structural modification allows the polyimide to achieve high transparency while maintaining high heat resistance and excellent mechanical characteristics, resolving the contradiction between transparency and heat resistance.
2Illumination intensity
If trans-1,4-cyclohexanediamine is used to achieve high transparency and heat resistance, then optical properties are improved, but polymerization becomes difficult due to salt formation
Solution Approach 1:
The patent modifies the diamine structure by introducing a methyl group at the 2-position of the cyclohexylene ring, creating 2,2'-methylenebis(4-aminocyclohexane). This structural change prevents salt formation during polymerization while maintaining the desired optical properties and heat resistance, thus resolving the contradiction between optical performance and ease of manufacture.
3Illumination intensity
If a polyimide with high transparency and heat resistance is produced using pyromellitic acid and 4,4'-methylenebis(aminocyclohexane), then optical properties are improved, but solubility decreases requiring high-temperature heat treatment
Solution Approach 1:
The patent changes the diamine structure to 2,2'-methylenebis(4-aminocyclohexane) with methyl groups at the 2-positions. This modification improves solubility while maintaining high transparency and heat resistance, allowing film manufacturing without high-temperature heat treatment and thus resolving the contradiction between optical properties and processing ease.
4Object-generated harmful factors
If a porous film or boehmite layer is applied for antireflection, then antireflection performance is improved, but water absorption increases causing substrate damage
Solution Approach 1:
The patent creates a composite structure by forming a polyimide film containing 2,2'-methylenebis(4-aminocyclohexane) on the substrate surface. This polyimide layer serves as a protective barrier that prevents water penetration to the substrate while the underlying porous antireflection layer maintains its antireflection performance. The composite structure resolves the contradiction between antireflection performance and substrate protection.
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 provides a stable, high-performance antireflection effect across a wide wavelength range, maintains transparency and heat resistance, and prevents substrate damage by minimizing water absorption and refractive index variations, ensuring long-term durability and optical consistency.
Implementation Method 1
prevents substrate damage by minimizing water absorption
Implementation Method 2
a textured aluminum oxide structure is applied on the surface to enhance antireflection, providing a stable, high-performance antireflection effect across a wide wavelength range
Data Source
AI summary
There is provided an optical member that can retain a high antireflection effect on a substrate for a long time. The optical member includes a laminated body that can reduce the reflection of light formed on a substrate surface, wherein at least one layer of the laminated body is a polyimide layer containing a polyimide film, and the polyimide contains a repeating unit represented by the general formula (1)in claim 1, and a 1,4-cyclohexylene group in the main chain of R2 in the general formula (1) contains 90% by mole or more of a trans-1,4-cyclohexylene group, wherein R1 denotes a tetravalent organic group, and R2 denotes a divalent organic group having one or two or more 1,4-cyclohexylene groups in the main chain.