Thermal Transfer Sheet Back Layer Composite Resin
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Solution Overview
Problem
Thermal transfer sheets used in thermal transfer printers face issues with heat resistance, slipping efficiency, and image quality due to adhesion and deposition of foreign matter, which existing solutions fail to adequately address, particularly during high-energy printing and when using special solvents or unsuitable lubricants.
Innovation Solution
A thermal transfer sheet with a back layer comprising a mixture of polyamide-imide resin, polyamide-imide silicone resin, polyvalent metal salt of alkylphosphoric ester, metal salt of alkylcarboxylic acid, silicone oil, and inorganic filler, which can be produced without heat treatment using a single-liquid coating solution, enhancing heat resistance and slipping efficiency while preventing image defects like wrinkling and staining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat-resistant layer of higher heat-resistant thermosetting resin is formed, then heat resistance is improved, but slipping efficiency deteriorates and complicated production processes are required
Solution Approach 1:
The back layer uses a composite resin composition comprising polyamide-imide resin (A), polyamide-imide silicone resin (B), and polyester resin (C) in specific ratios. This composite structure provides both heat resistance (from polyamide-imide) and slipping efficiency (from silicone resin), resolving the contradiction between these two properties without requiring complicated production processes
Solution Approach 2:
The invention optimizes the molecular weight and glass transition temperature (Tg) parameters of the polyamide-imide resin (A) to be within specific ranges (molecular weight: 10,000-50,000, Tg: 150-250°C). By controlling these parameters, the resin achieves optimal balance between heat resistance and slipping efficiency, eliminating the need for complex multi-component coating solutions
2Ease of operation
If a lubricant such as silicone oil, low-melting point WAX, or surfactant is added, then slipping efficiency is improved, but image intensity deteriorates and foreign matter deposition occurs
Solution Approach 1:
Instead of using single-component lubricants that cause image degradation, the invention employs a composite resin system where polyamide-imide silicone resin (B) serves as an integrated lubricant within the coating matrix. This approach provides slipping efficiency while maintaining image quality, as the lubricant is bound within the resin structure rather than being a free-flowing additive
Solution Approach 2:
The invention replaces traditional lubricants (silicone oil, WAX, surfactant) that transfer to the opposite face and cause image degradation with a self-contained polyamide-imide silicone resin system. This resin-based lubricant remains bound in the coating, eliminating foreign matter deposition on the thermal head while maintaining slipping efficiency
3Reliability
If a filler is added for removal of deposit, then foreign matter deposition is reduced, but friction coefficient increases causing cockles and thermal head abrasion
Solution Approach 1:
The invention uses a composite resin system where polyamide-imide resin (A) provides structural integrity and controlled friction characteristics. This resin matrix prevents filler aggregation and maintains uniform friction properties, eliminating cockles while reducing thermal head abrasion compared to traditional filler-based solutions
4Temperature
If long-term heat treatment is applied to produce hardened film, then heat resistance is improved, but production time increases and cockles occur
Solution Approach 1:
The invention changes the chemical composition parameters of the coating solution by incorporating polyamide-imide silicone resin (B) and polyester resin (C) in addition to polyamide-imide resin (A). This modified composition enables the coating to achieve sufficient heat resistance through the inherent thermal stability of the polyamide-imide silicone resin, eliminating the need for prolonged heat treatment and reducing production time
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 superior heat resistance and slipping efficiency, preventing image defects such as wrinkling and staining during printing, and can be produced without hazardous special solvents, simplifying the production process and improving working conditions.
Implementation Method 1
a polyamide-imide resin (A) having a Tg of 200° C. or higher as determined by differential thermal analysis and a polyamide-imide silicone resin (B) having a Tg of 200° C. or higher
Implementation Method 2
a silicone oil (E)
Implementation Method 3
an inorganic filler (F)... use of a unsuitable filler causes problems such as generation of cockles during printing by increase of friction coefficient with the thermal head and abrasion of the thermal head
Data Source
AI summary
To provide a thermal transfer sheet having a back layer excellent in heat resistance and slipping properties and causing no wrinkling at printing and no image-defect by tailing, the sheet being able to be prepared without a heat treating, such as aging.A thermal transfer sheet, comprising a substrate film, a transfer ink layer formed on one face thereof, and a back layer formed on the other face thereof,wherein the back layer comprises:a mixed binder containing a polyamide-imide resin (A) having a Tg of 200° C. or higher as determined by differential thermal analysis and a polyamide-imide silicone resin (B) having a Tg of 200° C. or higher;a mixture of a polyvalent metal salt of alkylphosphoric ester (C) and a metal salt of alkylcarboxylic acid (D),a silicone oil (E); andan inorganic filler (F).