Thermal Transfer Sheet Back Face Layer Resin Formulation
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Solution Overview
Problem
Thermal transfer sheets face issues with residues adhering to thermal heads due to components falling off from the back face layer, leading to image flaws and prolonged aging times, with existing solutions limiting material selection and not effectively preventing 'kick' occurrences.
Innovation Solution
A thermal transfer sheet with a back face layer containing a binder resin and inorganic particles, where the binder resin is produced by reacting a polyisocyanate with an isocyanurate structure and a resin having hydroxyl groups at a specific equivalent ratio, and non-spherical inorganic particles are used to prevent residue adhesion and reduce aging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binder resins are used in the back face layer, then the thermal transfer sheet can be manufactured with standard materials, but residues fall off and adhere to thermal heads causing image flaws
Solution Approach 1:
The invention changes the chemical parameters of the binder resin by specifying precise equivalent ratios of isocyanate groups to hydroxyl groups (0.05-0.15), which fundamentally alters the resin's molecular structure and curing characteristics. This parameter optimization prevents residue formation while maintaining manufacturing feasibility
Solution Approach 2:
The invention creates a composite binder resin system combining polyisocyanate with isocyanurate structure and resin with hydroxyl groups in specific ratios. This composite approach leverages the complementary properties of both materials to achieve both reliability and reduced harmful factors
2Productivity
If the back face layer is insufficiently cured during storage, then manufacturing time is reduced, but the back face layer adheres to the colorant layer causing defects during printing
Solution Approach 1:
The invention modifies the curing parameters by controlling the equivalent ratio of isocyanate to hydroxyl groups, which accelerates the curing reaction. This allows the back face layer to reach sufficient cure status faster, reducing aging time requirements while ensuring printing quality
Solution Approach 2:
The invention performs preliminary curing optimization during manufacturing by incorporating the optimized resin formulation that accelerates cure kinetics. This preliminary action ensures the back face layer is sufficiently cured before storage, preventing adhesion defects during subsequent printing operations
3Ease of operation
If colorant migrates to the back face layer during storage, then the thermal transfer sheet can be stored without special conditions, but the colorant may remigrate and cause kick, degrading color developing characteristics
Solution Approach 1:
The invention changes the chemical environment of the back face layer by using a resin formulation with specific equivalent ratios, which alters the chemical affinity and interaction with colorant molecules. This prevents colorant migration during storage while maintaining ease of operation
Solution Approach 2:
The invention creates a stable back face layer composition that permanently prevents colorant migration during the product's service life, eliminating the need for complex storage conditions and ensuring reliable color developing characteristics throughout the product lifecycle
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 inhibits residue adhesion onto thermal heads, prevents 'kick' occurrences, and shortens the aging time for the back face layer, improving image quality and production efficiency.
Implementation Method 1
the binder resin comprises a product obtained by reacting a polyisocyanate having an isocyanurate structure with a resin having hydroxyl groups at an equivalent ratio of isocyanate groups in the polyisocyanate having an isocyanurate structure to hydroxyl groups in the resin having hydroxyl groups (—NCO/—OH) of 0.05 or more and 0.15 or less
Data Source
AI summary
To provide a thermal transfer sheet capable of inhibiting residues derived from a back face layer from adhering to a thermal head, also capable of inhibiting occurrence of a kick, and having a shorter time period until the back face layer is stabilized.A thermal transfer sheet comprising; a colorant layer located on one surface of a substrate and a back face layer located on the other surface of the substrate, wherein the back face layer comprises a binder resin and inorganic particles, and the binder resin comprises a product obtained by reacting a polyisocyanate having an isocyanurate structure with a resin having hydroxyl groups at an equivalent ratio of isocyanate groups in the polyisocyanate having an isocyanurate structure to hydroxyl groups in the resin having hydroxyl groups (—NCO/—OH) of 0.05 or more and 0.15 or less.