Photo-alignment Polymer with Acid-cleavage Group for Liquid Crystal Alignment

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Solution Overview

Problem

The existing photo-alignment polymers used in forming optically anisotropic layers for image display devices, particularly with disk-like liquid crystal compounds, suffer from deteriorated liquid crystal alignment properties, which affect the performance and stability of these layers.

Innovation Solution

A photo-alignment polymer with a repeating unit containing a photo-aligned group and an acid-cleavage group, where the acid-cleavage group produces a polar group, is used, along with a crosslinkable group, to enhance liquid crystal alignment properties by optimizing the mass ratio and molecular weight, forming a binder composition that improves alignment controllability and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional photo-alignment polymer is used to form an optically anisotropic layer, then the layer can be formed, but the liquid crystal alignment properties are deteriorated

Engineering Contradiction:

Improveliquid crystal alignment propertiesVSAvoidalignment controllability

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent modifies the chemical structure of the photo-alignment polymer by introducing a repeating unit with specific Formula (1) containing a photo-aligned group and acid-cleavage group. This structural parameter change enables the polymer to generate carboxylic acid groups upon acid treatment, which significantly improves liquid crystal alignment properties and alignment controllability without compromising layer formation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite photo-alignment polymer system that combines multiple functional groups (photo-aligned group, acid-cleavage group, and crosslinkable group) within a single polymer structure. This composite approach allows the material to simultaneously provide photo-alignment functionality, acid-generated polarity enhancement, and crosslinking capability for improved alignment precision

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If the photo-alignment polymer structure is simplified, then manufacturing is easier, but liquid crystal alignment properties deteriorate

Engineering Contradiction:

Improvepolymer synthesis easeVSAvoidliquid crystal alignment properties

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent segments the photo-alignment polymer into distinct functional modules: a photo-aligned group (P) for light-responsive alignment, an acid-cleavage group (e.g., t-butoxycarbonyl) for acid-triggered polarity enhancement, and a crosslinkable group for structural stabilization. This modular segmentation allows each component to perform its specific function while maintaining overall manufacturability through standardized polymerization procedures

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If a disk-like liquid crystal compound is used, then specific optical properties are achieved, but alignment properties are deteriorated

Engineering Contradiction:

Improveoptical property tuningVSAvoidliquid crystal alignment properties

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces carboxylic acid groups (generated from acid-cleavage groups upon acid treatment) as intermediary species that mediate between the photo-alignment polymer and disk-like liquid crystal compounds. These carboxylic acid groups form strong interactions with the liquid crystal compounds, acting as an intermediary that enhances alignment properties without requiring modification of the disk-like liquid crystal structure itself

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

The proposed solution significantly improves liquid crystal alignment properties and upper layer coating properties, leading to enhanced display performance and stability in image display devices by maximizing alignment controllability and minimizing defects.

Implementation Method 1

a photo-alignment film obtained by performing a photo-alignment treatment may be used in order to align the liquid crystal compound

Methodology Applied

Scientific EffectPhoto-alignment: Photochromism

Implementation Method 2

The photo-alignment polymer contains a cleavage group which is decomposed by an action of acid to produce a polar group

Methodology Applied

Scientific EffectAcid decomposition: Hydrolysis

Data Source

PatentUS11827727B2Photo-alignment polymer, binder composition, binder layer, optical laminate, optical laminate manufacturing method, and image display device

Publication Date: 2023.11.28 FUJIFILM CORP

AI summary

A photo-alignment polymer has a repeating unit represented by Formula (1), in Formula (1), R1 represents a hydrogen atom or a substituent, X represents —O—, —S—, or —NR2—, in which R2 represents a hydrogen atom or a substituent, L1 represents a single bond or a divalent linking group, P represents a photo-aligned group, and A represents an acid-cleavage group which is decomposed by an action of acid to produce a polar group