Recording Material Core/Shell Particle Opacity Control

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Solution Overview

Problem

Existing recording materials face challenges in achieving improved performance and versatility in image formation without relying on expensive methods involving color precursors and developers, which are prone to long-term instability.

Innovation Solution

A recording material featuring a support with a colored surface and a layer of polymeric particles with a core/shell structure, including voids, where the outer shell has a lower glass transition temperature than the inner shell, allowing for image formation through heat or pressure exposure, thereby simplifying formulations and enhancing image types without the need for color precursor reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If color precursors and developers are used for image formation, then image formation capability is improved, but long-term stability deteriorates

Engineering Contradiction:
Improveimage formation capabilityVSAvoidlong-term stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention extracts and removes the unstable color precursor and developer components from the recording material system. Instead of using these reactive components, the patent employs pre-formed polymeric particles with voids that directly provide the desired imaging function through physical changes (void collapse) rather than chemical reactions, thereby eliminating the stability problem while maintaining image formation capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the fundamental parameter of image formation from chemical reaction (color precursor + developer) to physical transformation (void collapse under heat/pressure). This parameter change allows the system to achieve image formation without the instability inherent in chemical precursor systems, as the polymeric particles with voids provide stable, predictable physical changes under controlled conditions

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If complex formulations with color precursors and developers are used, then image formation versatility is improved, but formulation complexity increases

Engineering Contradiction:
Improveimage formation versatilityVSAvoidformulation complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention extracts the unnecessary complex components (color precursors, developers, and their associated reaction chemistry) from the formulation. The simplified system uses only polymeric particles with voids embedded in a coating, eliminating multiple chemical components and their interactions, thereby reducing formulation complexity while maintaining imaging versatility

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The polymeric particles with voids serve multiple functions simultaneously: they provide the imaging mechanism through void collapse, offer opacity control, and enable various image types (visible, invisible, latent) depending on application conditions. This multi-functionality replaces the need for multiple specialized components, simplifying the overall formulation while maintaining versatility

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Device complexity

If polymeric particles with core/shell structure and voids are used, then formulation simplicity is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improveformulation simplicityVSAvoidparticle structure precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The invention employs polymeric particles with controlled voids (porous structure) as the core functional element. These porous particles are incorporated into the coating formulation, providing the desired imaging functionality through their void collapse characteristics while maintaining formulation simplicity. The porous structure is key to achieving the balance between simple formulation and controlled performance

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The invention uses composite polymeric particles with core/shell structure containing voids. This composite structure combines different polymer phases (inner shell with higher Tg, outer shell with lower Tg) to achieve specific thermal and mechanical properties that control void collapse behavior, thereby meeting manufacturing precision requirements while keeping the overall formulation simple

Inventive Principle:
Principle #40Composite materials

4Productivity

If outer shell has lower Tg than inner shell, then void collapse under heat/pressure is improved, but particle structural stability may worsen

Engineering Contradiction:
Improvevoid collapse efficiencyVSAvoidparticle structural stability
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The invention applies local quality differentiation within the polymeric particle by creating a core/shell structure where the outer shell has different properties (lower Tg) than the inner shell (higher Tg). This local differentiation allows the outer shell to facilitate void collapse under heat/pressure while the inner shell maintains structural stability, resolving the contradiction between collapse efficiency and structural integrity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The core/shell composite structure combines materials with different glass transition temperatures to achieve synergistic performance. The outer shell with lower Tg provides the necessary flexibility for void collapse, while the inner shell with higher Tg provides structural support and stability, thereby resolving the contradiction between collapse efficiency and particle stability

Inventive Principle:
Principle #40Composite materials

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 recording material achieves improved image formation simplicity and versatility by using polymeric particles with a core/shell structure and voids, reducing opacity through heat or pressure, thus avoiding the instability issues associated with color precursors and developers, while maintaining high print quality.

Implementation Method 1

particles having an outer polymer shell having a calculated Tg of from 40° C. to 80° C. and (ii) particles having an inner polymer shell having a calculated Tg of from 40° C. to 130° C. and an outer polymer shell having a calculated Tg of from −55° C. to 50° C.; wherein the calculated Tg of said outer polymer shell is lower that of said inner polymer shell

Methodology Applied
Scientific EffectGlass transition temperature differential:

Implementation Method 2

subjecting selected portions of said recording material to an agent selected from the group consisting of heat, pressure, and combinations thereof, sufficient to reduce the opacity of said selected portions

Methodology Applied
Scientific EffectThermal expansion and void collapse: Thermal Expansion

Data Source

PatentUS11845879B2Recording material
Publication Date: 2023.12.19 ROHM & HAAS CO

AI summary

A recording material including a support having at least one colored surface and a layer of polymeric material is described. The layer including polymeric particles has a core/shell structure, and the particles are either (i) particles having an outermost polymer shell having a calculated Tg of from 40° C. to 80° C., or (ii) particles having an inner polymer shell having a calculated Tg of from 40° C. to 130° C. and an outer polymer shell having a calculated Tg of from −55° C. to 50° C. The calculated Tg of said outer polymer shell is lower than that of said inner polymer shell, the particles including, when dry, at least one void capable of providing opacity to said layer, and the colored surface has sufficient color density to be visibly contrasting to a surface of the subsequent layer including the polymeric particles disposed thereon.