Thermosensitive Recording Layer Composition for Water Resistance
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Solution Overview
Problem
Existing thermosensitive recording media face challenges in achieving high water resistance without compromising color development performance, as installing a protective layer often deteriorates the color development capabilities.
Innovation Solution
A thermosensitive recording layer comprising a carboxyl group-containing resin, an epichlorohydrin resin, and a modified polyamine/amide resin, combined with an acrylic resin having a glass transition temperature (Tg) of 50°C or lower and a minimum film forming temperature (MFT) of 40°C or higher, without a protective layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is installed on the thermosensitive recording layer to improve water resistance, then water resistance is improved, but color development performance deteriorates
Solution Approach 1:
The invention merges the protective layer function and the thermosensitive recording layer function into a single integrated layer. The thermosensitive recording layer itself is formulated to provide both water resistance and color development performance through the specific resin composition (carboxyl group-containing resin, epichlorohydrin resin, and modified polyamine/amide resin), eliminating the need for a separate protective layer that would compromise color development.
Solution Approach 2:
The thermosensitive recording layer is designed to perform multiple functions simultaneously: it serves as both the active recording layer for color development and the protective layer for water resistance. This multi-functional design allows the single layer to withstand rough handling during rainfall while maintaining excellent color development performance.
2Manufacturing precision
If no protective layer is installed to maintain color development performance, then color development performance is maintained, but water resistance deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the thermosensitive recording layer by incorporating specific resins (carboxyl group-containing resin, epichlorohydrin resin, and modified polyamine/amide resin) in controlled amounts. These compositional changes enable the layer to achieve both water resistance and color development performance without requiring a separate protective layer.
3Reliability
If acrylic resin with low Tg and high MFT is used in the thermosensitive recording layer, then water resistance and surface quality are improved, but the complexity of formulation increases
Solution Approach 1:
The invention uses a composite resin system combining carboxyl group-containing resin, epichlorohydrin resin, and modified polyamine/amide resin in the thermosensitive recording layer. This composite material approach provides water resistance and excellent surface quality while maintaining color development performance, with the added benefit that these resins are commonly available and the formulation process remains relatively straightforward.
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 a thermosensitive recording medium with enhanced water resistance and excellent surface qualities while maintaining color development performance, without the need for a protective layer.
Implementation Method 1
an acrylic resin with a glass transition temperature (Tg) of lower than or equal to 50 degree C and a minimum film forming temperature (MFT) of higher than or equal to 40 degree C
Implementation Method 2
containing a carboxyl group-containing resin, an epichlorohydrin resin and a modified polyamine/amide resin
Implementation Method 3
improve the water resistance and the like without deteriorating the color development performance
Data Source
Figure 1(A)~1(B)
AI summary
The present invention provides a thermosensitive recording medium having a high degree of water resistance and excellent surface qualities. The thermosensitive recording medium has a thermosensitive recording layer comprising a colorless or pale colored basic leuco dye and an electron accepting developing agent on a substrate, but does not have a protective layer on the thermosensitive recording layer, and the thermosensitive recording layer further comprises (i) a carboxy-modified polyvinyl alcohol as a binder, (ii) an epichlorohydrin resin and a modified polyamine/amide resin (excluding those contained in the category of epichlorohydrin resin) as crosslinking agents, and (iii) an acrylic resin with a glass transition temperature (Tg) of lower than or equal to 50 degree C and a minimum film forming temperature (MFT) of higher than or equal to 40 degree C.