Antistatic Layer Stability in Optical Displays

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Solution Overview

Problem

Conventional optical layered bodies with antistatic layers, particularly those using quaternary ammonium salts or conductive polymers, exhibit unstable surface resistance during durability tests, leading to insufficient sensing in touch panels and white turbidity in display screens due to charge concentration.

Innovation Solution

An optical layered body with an antistatic layer composed of conductive fine particles, a resin component without reactive functional groups, and a solvent, forming chain-like or needle-like aggregates, ensuring stable surface resistance through the exclusion of monomer components and the use of specific resin and solvent combinations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If quaternary ammonium salts are used as antistatic agents in the antistatic layer, then the antistatic function is improved, but the surface resistance becomes unstable after durability tests

Engineering Contradiction:
Improveantistatic functionVSAvoidsurface resistance stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical composition parameters of the antistatic layer by replacing quaternary ammonium salts with conductive fine particles (metal oxides, carbon nanotubes, or graphite) combined with specific resin components. This parameter change maintains the antistatic function while significantly improving surface resistance stability after durability tests, as the conductive particles provide a more stable electrical pathway that does not degrade under heat and light exposure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining conductive fine particles with specific resin components (polymer materials with functional groups) in the antistatic layer. This composite structure leverages the high conductivity and stability of the fine particles while the resin provides binding and compatibility, resulting in an antistatic layer that maintains both antistatic performance and surface resistance stability under durability conditions.

Inventive Principle:
Principle #40Composite materials

2Reliability

If conductive polymers are used as antistatic agents, then the antistatic function is improved, but the surface resistance decreases after durability tests

Engineering Contradiction:
Improveantistatic functionVSAvoidsurface resistance control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the material parameters from conductive polymers to inorganic conductive fine particles (metal oxides, carbon nanotubes, graphite). This parameter change prevents the degradation and excessive conductivity increase that occurs with polymers after durability tests, maintaining precise control over surface resistance. The inorganic particles provide stable electrical properties that do not deteriorate under heat and light exposure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces organic conductive polymers with inorganic conductive fine particles that have superior long-term stability. While the particles themselves are not consumed, the polymer matrix they are embedded in can degrade, but the inorganic particles maintain their conductive properties indefinitely, effectively replacing a short-living organic material with a long-living inorganic alternative.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If the antistatic layer contains monomer components, then the coating process is simplified, but the surface resistance becomes unstable after durability tests

Engineering Contradiction:
Improvecoating processVSAvoidsurface resistance stability
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent extracts and removes monomer components from the antistatic layer composition, using only pre-polymerized resin materials and conductive fine particles. This extraction eliminates the polymerization reactions that cause shrinkage and instability after durability tests, while still allowing for simple coating processes using solvent-based applications. The resin components are selected to be compatible with conductive particles without requiring monomer addition.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of manufacture

If the antistatic layer uses conventional resin components with reactive functional groups, then the coating process is easier, but the surface resistance changes after durability tests

Engineering Contradiction:
Improvecoating processVSAvoidsurface resistance stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the chemical parameters of the resin component by selecting polymer materials with specific functional groups that provide both ease of coating and stability. The resins are chosen to have appropriate molecular weights, glass transition temperatures, and functional group types that ensure compatibility with conductive fine particles while maintaining dimensional stability and preventing surface resistance changes after durability tests.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by selecting resin components with specific local chemical properties (functional groups) that interact appropriately with conductive fine particles at the molecular level. The functional groups are chosen to provide good dispersion and bonding of conductive particles without undergoing excessive reactions under durability conditions, creating a locally optimized interface between resin and conductive particles that ensures overall layer stability.

Inventive Principle:
Principle #3Local quality

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 optical layered body maintains stable surface resistance before and after durability tests, preventing charge concentration and ensuring reliable performance in touch panels and display devices.

Implementation Method 1

the antistatic layer is formed using a composition for an antistatic layer containing conductive fine particles, a resin component, and a solvent

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11169303B2Optical layered body and image display device
Publication Date: 2021.11.09 DAI NIPPON PRINTING CO LTD

AI summary

Provided is an optical layered body which is extremely high in the stability of the antistatic performance, and has a stable surface resistance even after a durability test. The optical layered body includes an antistatic layer on one face of a light-transmitting substrate, wherein the antistatic layer is formed using a composition for an antistatic layer containing conductive fine particles, a resin component, and a solvent, and the resin component has no reactive functional groups in a molecule, and is soluble in the solvent and compatible with the conductive fine particles.