Stannous Alkoxide Compositions for Uniform Silver Patterns

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Solution Overview

Problem

Current methods for producing electrically-conductive films, particularly for touch screen displays, face challenges with Indium Tin Oxide (ITO) limitations, such as high cost, limited availability, low conductivity, and processing difficulties, while existing photocurable compositions require expensive dispersants and struggle with silver particle agglomeration, leading to ineffective and non-uniform catalytic metal patterns.

Innovation Solution

A non-aqueous stannous alkoxide composition comprising a water-insoluble stannous alkoxide complex and a photocurable or non-photocurable polymer, which generates silver particles in situ as catalytic sites for electroless plating, eliminating the need for dispersing silver particles and reducing agglomeration issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If silver particles are dispersed in photocurable compositions using conventional methods, then electrically-conductive films can be formed, but expensive dispersants are required and silver particle agglomeration occurs leading to non-uniform catalytic patterns

Engineering Contradiction:
Improveuniformity of catalytic metal patternsVSAvoidrequirement for dispersing agents and processing steps
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the need for dispersants by using stannous alkoxide complexes that inherently prevent silver particle agglomeration through their chemical structure and reducing properties, simplifying the composition formulation and processing steps

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Stannous alkoxide complexes serve as intermediary substances that mediate between silver ions and the photocurable matrix, providing both reduction capability and dispersion stability without requiring additional dispersing agents

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If ITO coatings are used to create electrically-conductive films for touch screens, then capacitive areas can be formed, but the conductivity is relatively low requiring short line lengths and additional driving electronics

Engineering Contradiction:
Improveelectrical conductivityVSAvoidnumber of segments and driving electronics
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention changes the fundamental parameter of electrical conductivity by using silver metal (conductivity 50-100 times greater than ITO) instead of ITO, allowing for longer line lengths and fewer segmented sections in touch screen designs

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If ITO coatings are used for electrically-conductive layers, then touch screen displays can be manufactured, but vacuum deposition with high processing temperatures is required

Engineering Contradiction:
Improveprocessing conditionsVSAvoidprocessing temperature
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The invention replaces the mechanical/physical vacuum deposition process with a chemical photocurable composition approach that can be applied at lower temperatures using printing or coating methods followed by photocuring

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention utilizes phase transition from liquid photocurable composition to solid cured film, enabling low-temperature processing compared to the high-temperature vacuum deposition required for ITO

Inventive Principle:
Principle #36Phase transitions

4Reliability

If silver particles are used to provide high electrical conductivity, then conductivity 50-100 times greater than ITO can be achieved, but silver particle agglomeration leads to less effective and uniform catalytic metal patterns

Engineering Contradiction:
Improveelectrical conductivityVSAvoiduniformity of catalytic metal patterns
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

Stannous alkoxide complexes act as intermediary agents that reduce silver ions to metallic silver while maintaining uniform distribution, preventing agglomeration through their coordinating chemistry and controlled reduction mechanism

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical state and distribution parameters of silver by using stannous alkoxide complexes that control silver particle formation in-situ, ensuring uniform size and distribution rather than relying on pre-formed particle dispersions

Inventive Principle:
Principle #35Parameter changes

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

This approach enables the production of high-conductivity silver patterns with improved durability and uniformity, suitable for high-speed manufacturing processes like roll-to-roll operations, without the need for expensive dispersants and with reduced operator errors.

Implementation Method 1

component (a) comprising a water-insoluble stannous alkoxide complex comprising stannous ions... generates silver particles in situ as catalytic sites

Methodology Applied
Scientific EffectChemical reduction: Reduction

Implementation Method 2

a photocurable component (b)... when photocurable component (b) is present, the non-aqueous stannous alkoxide composition further comprises photosensitizer component (d)

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS10174425B2Non-aqueous compositions and articles using stannous alkoxides
Publication Date: 2019.01.08 EASTMAN KODAK CO

AI summary

A non-aqueous stannous alkoxide composition comprises: component (a) comprising a water-insoluble stannous alkoxide complex comprising stannous ions in an amount of at least 1 weight %, and a photocurable component (b), non-photocurable water-insoluble polymer component (c) having a molecular weight of at least 10,000, or both the photocurable component (b) and the non-photocurable water-insoluble polymer component (c). When photocurable component (b) is present, the non-aqueous stannous alkoxide composition further comprises photosensitizer component (d) that is different from all of components (a) through (c), in an amount of at least 1 weight %. These compositions can be used to prepare silver particles as “seed” catalysts in various articles that can then be used for other purposes such as electroless plating.