Thermal Transfer Sheet Aqueous Coating Curling Prevention
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Solution Overview
Problem
Current thermal transfer image receiving sheets face issues with adhesion between layers, printing sensitivity, occurrence of white spots, durability under temperature and humidity changes, and productivity due to curling caused by heat during production, as well as inefficiencies in the wet-on-wet coating method.
Innovation Solution
A thermal transfer image receiving sheet with a substrate having a thermal insulation layer, an intermediate layer, and an image receiving layer, all formed by an aqueous coating method, where the image receiving layer contains a compound that forms a chelate with a colorant, and the layers are coated using a simultaneous multilayer method to ensure proper adhesion and flatness, with a release agent to prevent curling and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a foamed film is pasted on a substrate to provide thermal insulation and cushioning, then thermal insulation function is improved, but the sheet curls due to heat generated during image receiving layer application
Solution Approach 1:
The patent combines the thermal insulation layer and intermediate layer into a single integrated structure coated directly on the substrate, eliminating the need for separate pasting of foamed film. This integration prevents the curling issue while maintaining thermal insulation functionality through the coordinated design of both layers.
Solution Approach 2:
The patent uses a composite structure consisting of a thermal insulation layer containing hollow particles for thermal insulation, combined with an intermediate layer providing adhesion and flatness. This composite material approach achieves both thermal insulation and shape stability without the curling problem of pasted foamed films.
2Reliability
If hollow particles are used in the intermediate layer to improve thermal insulation, then thermal insulation function is improved, but surface flatness is lost causing white spots in images
Solution Approach 1:
The patent segments the functional requirements into two distinct layers: the thermal insulation layer contains hollow particles to provide thermal insulation, while the intermediate layer provides a flat, adhesive surface. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The patent applies local quality by concentrating hollow particles in the thermal insulation layer where thermal insulation is needed, while the intermediate layer maintains uniform composition and flatness where surface quality is critical for image formation. Each layer has differentiated properties suited to its specific function.
3Productivity
If wet-on-wet coating method is used to improve productivity, then coating efficiency is improved, but adhesion between layers and image quality deteriorate
Solution Approach 1:
The patent applies preliminary action by first forming the thermal insulation layer and allowing it to dry completely before coating the intermediate layer. This sequential approach ensures the underlying layer is stable and provides proper adhesion, preventing defects while maintaining efficient production through optimized process sequencing.
4Speed
If release agent amount is increased to enable short time release in high rate printing, then release speed is improved, but adhesion between intermediate layer and image receiving layer is lowered
Solution Approach 1:
The patent changes the chemical parameters of the intermediate layer by incorporating specific compounds that modify adhesion characteristics. This allows the layer to maintain strong adhesion to the image receiving layer while still permitting timely release during high-speed printing, balancing both requirements through compositional optimization.
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 provides improved adhesion between layers, high printing sensitivity, prevention of white spots, enhanced durability under varying conditions, and increased productivity by minimizing curling and optimizing the coating process.
Implementation Method 1
a foamed film having a function of thermal insulation
Implementation Method 2
an intermediate layer and an image receiving layer in that order, wherein the thermal insulation layer, the image receiving layer and the intermediate layer each is formed by an aqueous coating method
Data Source
AI summary
A thermal transfer image receiving sheet containing a substrate having thereon a thermal insulation layer, an intermediate layer and an image receiving layer in that order, wherein the thermal insulation layer, the image receiving layer and the intermediate layer each is formed by an aqueous coating method.