Thermal Transfer Medium Primer Layer Adhesion

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Solution Overview

Problem

Conventional thermal transfer recording media using water-based thermal transfer image-receiving sheets suffer from reduced transfer sensitivity and a higher likelihood of abnormal transfer, leading to unsatisfactory printing quality and density.

Innovation Solution

A thermal transfer recording medium with a primer layer containing polycarbonate and a polyurethane-urea resin with a polycaprolactam skeleton, an undercoat layer composed of a polyester-acrylic copolymer with a sulfonic acid group and glycidyl or carboxyl groups, and a heat-resistant lubricating layer on a substrate, which enhances adhesion and prevents abnormal transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If water-based thermal transfer image-receiving sheets are used, then environmental safety is improved, but transfer sensitivity deteriorates and abnormal transfer occurs

Engineering Contradiction:
Improveenvironmental safetyVSAvoidtransfer sensitivity
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent introduces a primer layer as an intermediary between the substrate and the dye layer. This primer layer contains specific polymers (polyester resin with sulfonic acid group, acrylic resin with carboxyl group, and polyvinyl pyrrolidone) that mediate the interaction between the water-based receiving layer and the dye layer, preventing direct thermal fusion while maintaining releasability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses composite materials in the primer layer by combining multiple polymer types (polyester resin, acrylic resin, and polyvinyl pyrrolidone) with specific functional groups. This composite structure provides both adhesion to the substrate and controlled releasability for the dye layer, resolving the contradiction between environmental safety and transfer sensitivity.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If water-based coating liquid is used for image-receiving sheet, then environmental concerns are reduced, but releasability between dye layer and dye-receiving layer deteriorates

Engineering Contradiction:
Improveenvironmental concernsVSAvoidreleasability
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent changes the chemical parameters of the primer layer by incorporating polymers with specific functional groups (sulfonic acid groups in polyester resin, carboxyl groups in acrylic resin, and polyvinyl pyrrolidone). These parameter changes enable the primer layer to provide appropriate releasability for water-based coating while maintaining environmental safety.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If conventional thermal transfer recording media structure is used with water-based receiving sheet, then manufacturing simplicity is maintained, but printing density and quality deteriorate

Engineering Contradiction:
Improvestructure simplicityVSAvoidprinting density
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent segments the recording medium structure by adding a primer layer between the substrate and the dye layer. This segmentation allows each layer to have optimized functionality: the substrate provides mechanical support, the primer layer provides adhesion and controlled releasability, and the dye layer provides color transfer. This improves printing density while maintaining reasonable structural simplicity.

Inventive Principle:
Principle #1Segmentation

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 improves transfer sensitivity and prevents abnormal transfer during high-speed printing with water-based thermal transfer image-receiving sheets, maintaining high printing density without increasing dye usage, even in high-temperature and high-humidity environments.

Implementation Method 1

the primer layer contains polycarbonate and a polyurethane-urea resin having a polycaprolactam skeleton

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

the primer layer contains polycarbonate and a polyurethane-urea resin having a polycaprolactam skeleton

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 3

the copolymer is a copolymer of polyester having a sulfonic acid group, and acrylic having at least one of a glycidyl group and a carboxyl group

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 4

the copolymer is a copolymer of polyester having a sulfonic acid group, and acrylic having at least one of a glycidyl group and a carboxyl group

Methodology Applied
Scientific EffectCross-linking:

Implementation Method 5

the thermal transfer layer comprises a layer containing ink (a dye layer), from which the ink is sublimated (sublimation transfer printing) or fused (fusion transfer printing) by the heat generated by the thermal head of the printer

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Implementation Method 6

the thermal transfer layer comprises a layer containing ink (a dye layer), from which the ink is sublimated (sublimation transfer printing)

Methodology Applied
Scientific EffectSublimation: Sublimation

Data Source

PatentEP3424744B1Thermal transfer recording medium
Publication Date: 2021.03.31 TOPPAN HOLDINGS INC
  • EP3424744B1 patent drawingFigure 1

AI summary

Provided is a thermal transfer recording medium that satisfies the requirements for higher printing speed of thermal transfer, and high density and high quality of thermal transfer images, that prevents the occurrence of abnormal transfer under high-temperature and high-humidity conditions, and that improves transfer sensitivity in printing. The thermal transfer recording medium (1) includes a primer layer (20), an undercoat layer (30), and a dye layer (40) in this order on one surface of a substrate (10), and a heat-resistant lubricating layer (50) on the other surface of the substrate (10); wherein the primer layer (20) contains polycarbonate and a polyurethane-urea resin having a polycaprolactam skeleton; the undercoat layer (30) contains a copolymer of polyester and acrylic, and polyvinyl pyrrolidone; and the copolymer is a copolymer of polyester having a sulfonic acid group, and acrylic having at least one of a glycidyl group and a carboxyl group.