N,N'-Diarylurea Developers for Phenol-Free Thermosensitive Recording

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Solution Overview

Problem

Existing thermosensitive recording materials face issues with storage stability, particularly in printed portions, and environmental health concerns due to the use of phenol-based developers, which require improved performance and safety.

Innovation Solution

Development of N,N'-diarylurea derivatives that do not contain phenol compounds, offering improved color density, whiteness, and storability, achieved through specific synthesis methods involving aromatic amine compounds and sulfonating agents in aprotic solvents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If phenol-based developers are used in thermosensitive recording materials, then color development sensitivity is improved, but storage stability of printed portions deteriorates and environmental health safety worsens

Engineering Contradiction:
Improvecolor development sensitivityVSAvoidstorage stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention changes the chemical structure parameters of the developer by replacing phenol-based compounds with N,N'-diarylurea derivatives containing specific functional groups (sulfonate, carboxylate, or phosphate groups). This structural parameter change maintains color development sensitivity while improving storage stability and environmental safety

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses composite functional groups in the developer molecule, combining the urea core structure with electron-withdrawing groups (sulfonate, carboxylate, or phosphate). This composite structure achieves both good color development and storage stability properties

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If phenol-based developers are used in thermosensitive recording materials, then color development sensitivity is improved, but environmental health safety deteriorates

Engineering Contradiction:
Improvecolor development sensitivityVSAvoidenvironmental health safety
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes the harmful phenol component from the developer structure while retaining the essential functional groups (sulfonate, carboxylate, or phosphate) that provide color development sensitivity. This extraction eliminates environmental health concerns while maintaining performance

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the chemical composition parameters by substituting phenol-based structures with N,N'-diarylurea derivatives containing safe functional groups, thereby improving environmental health safety while maintaining color development capability

Inventive Principle:
Principle #35Parameter changes

3Reliability

If non-phenol-based developers like N-3-[(p-toluenesulfonyl) oxy] phenyl-N'-(p-toluenesulfonyl) -urea are used, then storage stability is improved, but color development sensitivity deteriorates

Engineering Contradiction:
Improvestorage stabilityVSAvoidcolor development sensitivity
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The invention optimizes the electronic parameters of the developer by introducing electron-withdrawing groups (sulfonate, carboxylate, or phosphate) at specific positions on the phenyl rings. This parameter optimization simultaneously improves both storage stability and color development sensitivity, overcoming the limitations of previous non-phenol developers

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 N,N'-diarylurea derivatives enhance the storage stability and environmental safety of thermosensitive recording materials, addressing the limitations of phenol-based developers while maintaining performance.

Implementation Method 1

a thermosensitive recording material which uses a novel N,N'-diarylurea derivative as a developer

Methodology Applied
Scientific EffectThermal energy conversion:

Implementation Method 2

a thermosensitive recording material containing a light-conversion substance which absorbs laser light and converts it into heat

Methodology Applied
Scientific EffectLight absorption and heat conversion: Absorption (EM radiation)

Data Source

PatentEP4253075B1N,n'-diarylurea derivative, manufacturing method thereof, and thermosensitive recording material using same
Publication Date: 2025.10.15 SANKO CO LTD
  • EP4253075B1 patent drawingFigure 1
  • EP4253075B1 patent drawingFigure 2
  • EP4253075B1 patent drawingFigure 3

AI summary

The present invention relates to an N,N'-diurea derivative represented by the following general formula (1) and a method for producing the same. In addition, the present invention relates to a thermosensitive recording material comprising a developer, wherein the developer is the N,N'-diurea derivative represented by the following general formula (1): wherein R2 is an alkyl group, an aralkyl group, or an aryl group; and A1 is a hydrogen atom or an alkyl group.