Reducing agent, ink-jet recording apparatus, discharge printing method, image forming method, reducing agent stabilizing method, and reducing agent enhancing method

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Solution Overview

Problem

Thiourea dioxide-based reducing agents have low solubility in water and stability issues, leading to reduced reducing ability over time, particularly when used in discharge printing applications, resulting in short-term effectiveness.

Innovation Solution

Combining thiourea dioxide with specific carboxylates such as aliphatic monocarboxylates, monocarboxylic acid derivatives, or malonates enhances the reducing ability and stability of the reducing agent, preventing hydrolysis and maintaining effectiveness for extended periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thiourea dioxide is used alone as a reducing agent, then the reducing ability is provided, but the solubility in water is low and the reducing ability is reduced over time due to hydrolysis

Engineering Contradiction:
Improvereducing abilityVSAvoidstability of thiourea dioxide
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

A carboxylate compound is introduced as an intermediary substance that prevents the hydrolysis of thiourea dioxide. The carboxylate forms a protective complex or modifies the chemical environment to inhibit water from attacking the thiourea dioxide molecule, thereby maintaining its reducing ability over time while allowing it to remain dissolved in the aqueous composition.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite reducing agent system by combining thiourea dioxide with specific carboxylate compounds. This composite formulation leverages the reducing properties of thiourea dioxide while the carboxylate component provides stability and solubility enhancement, creating a synergistic mixture that overcomes the limitations of using thiourea dioxide alone.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If thiourea dioxide is dissolved in water, then the reducing agent can be applied, but the concentration of thiourea dioxide must be low due to low solubility

Engineering Contradiction:
Improveapplicability of reducing agentVSAvoidconcentration of thiourea dioxide
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The invention changes the chemical parameters of the aqueous solution by introducing carboxylate compounds, which modify the solubility characteristics of thiourea dioxide. This parameter change allows significantly higher concentrations of thiourea dioxide to be maintained in the aqueous solution without precipitation, thereby increasing the effectiveness of the reducing agent while maintaining ease of application.

Inventive Principle:
Principle #35Parameter changes

3Duration of action of stationary object

If thiourea dioxide is stored for a long period, then the reducing agent is available for use, but the discharge printing ability is reduced due to hydrolysis

Engineering Contradiction:
Improvestorage periodVSAvoiddischarge printing ability
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The carboxylate compound is preliminarily added to the thiourea dioxide solution to establish a protective chemical environment before storage begins. This preliminary action prevents hydrolysis from occurring during the storage period, thereby preserving the discharge printing ability of the reducing agent throughout the intended storage duration.

Inventive Principle:
Principle #10Preliminary action

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 combination of thiourea dioxide with carboxylates like formate, laurate, or trifluoroacetate in the reducing agent significantly improves both the reducing effect and long-term stability, maintaining a low optical density value even after several months, ensuring effective discharge printing.

Implementation Method 1

Thiourea dioxide is hydrolyzed in an aqueous solution over time, and the concentration thereof is reduced.

Methodology Applied
Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

Combining thiourea dioxide with specific carboxylates such as aliphatic monocarboxylates, monocarboxylic acid derivatives, or malonates enhances the reducing ability and stability of the reducing agent, preventing hydrolysis and maintaining effectiveness for extended periods.

Methodology Applied
Scientific EffectHydrolysis prevention: Hydrolysis

Data Source

PatentEP2918422B1Reducing agent, ink-jet recording apparatus, discharge printing method, image forming method, reducing agent stabilizing method, and reducing agent enhancing method
Publication Date: 2021.06.23 BROTHER KOGYO KK
  • EP2918422B1 patent drawingFigure 1(a)~1(b)
  • EP2918422B1 patent drawingFigure 2~3
  • EP2918422B1 patent drawingFigure 4(a)~4(b)

AI summary

The present invention relates to a reducing agent containing thiourea dioxide. The reducing agent contains thiourea. The reducing agent contains carboxylate. The carboxylate includes at least one of aliphatic monocarboxylate, an aliphatic monocarboxylic acid derivative salt, and malonate. Therefore, the reducing agent exerts a good reducing ability and a good long-term stability effect.