Thermal Recording Layer Composition for Low Background Coloration

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Solution Overview

Problem

The use of bis(hydroxybenzoic acid) compounds as color developers can result in unwanted coloration of unrecorded areas, known as background coloration, in recording media.

Innovation Solution

A recording medium comprising a recording layer with a coloring compound, a color developer, an amine compound, and specific epoxy and carbodiimide compounds, along with a matrix resin, to prevent background coloration and enhance color expression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bis(hydroxybenzoic acid) compound is used as a color developer, then color development function is achieved, but background coloration occurs

Engineering Contradiction:
Improvecolor development functionVSAvoidbackground coloration
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an amine compound as an intermediary substance that reacts with the bis(hydroxybenzoic acid) color developer to form a complex. This complex mediates the color development process, enabling the color developer to function properly while preventing direct unwanted reactions that cause background coloration. The amine compound acts as a bridge between the color developer and the recording layer components.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite system by combining the bis(hydroxybenzoic acid) color developer with specific amine compounds in defined ratios. This composite material approach allows the color developer to maintain its color development capability while the amine compound suppresses background coloration. The composite formulation achieves both functions simultaneously through synergistic interaction.

Inventive Principle:
Principle #40Composite materials

2Reliability

If conventional color developers are used, then color development is achieved, but color stability under high-temperature and high-humidity conditions deteriorates

Engineering Contradiction:
Improvecolor developmentVSAvoidcolor stability under high-temperature and high-humidity conditions
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The amine compound serves as a stabilizing intermediary that protects the color development system from environmental degradation. Under high-temperature and high-humidity conditions, the amine compound maintains the structural integrity of the color developer complex, preventing premature color changes or fading. This intermediary protection ensures long-term storage stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical parameters of the color development system by selecting amine compounds with specific molecular structures and properties. These parameter changes in the amine compound selection (such as molecular weight, functional groups, and reactivity) directly influence the stability of the color complex under extreme environmental conditions, enabling the system to withstand high temperature and humidity.

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

The solution effectively suppresses background coloration and improves color stability under high-temperature and high-humidity conditions, ensuring reliable and clear image representation.

Implementation Method 1

a coloring compound with electron-donating properties, a color developer with electron acceptability

Methodology Applied
Scientific EffectElectron transfer: Redox Reactions

Implementation Method 2

at least one compound selected from an epoxy compound and a carbodiimide compound... Z1 and Z2 independently represent a hydrogen-bonding bonding group

Methodology Applied
Scientific EffectHydrogen bonding:

Data Source

PatentEP4368407B1Recording medium, card, and booklet
Publication Date: 2026.01.21 SONY GROUP CORP
  • EP4368407B1 patent drawingFigure 1~2
  • EP4368407B1 patent drawingFigure 3
  • EP4368407B1 patent drawingFigure 4A~4B

AI summary

To provide a recording medium capable of suppressing coloration of a background. The recording medium includes: a recording layer that includes a coloring compound with electron-donating properties, a color developer with electron acceptability, an amine compound, at least one compound selected from an epoxy compound and a carbodiimide compound, and a polycarbonate resin. The color developer includes at least one compound represented by the following formulae (1A) and (1B).