Resorcinyl Triazine Heat-Sensitive Coatings for Storage Stability
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Solution Overview
Problem
Heat-sensitive coating compositions used for marking substrates tend to rapidly discolour upon storage at room temperature or slightly elevated temperatures, making them unstable for storage and use.
Innovation Solution
A heat-sensitive coating composition comprising a specific colour developer formula, combined with a colour former and binder, which is storage stable and resistant to darkening, and provides high contrast and stability against heat, oil, and light, without the need for microencapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If typical heat-sensitive coating compositions are used, then image formation is achieved through thermal reaction, but rapid discolouring occurs upon storage in the wet state at room temperature or slightly elevated temperature
Solution Approach 1:
The patent extracts the reactive components (colour developer and colour former) from direct contact with each other during storage by using a multi-layer coating structure. The colour developer is applied to the substrate while the colour former remains in the receipt paper layers above, preventing premature reaction and discolouration during storage.
Solution Approach 2:
The coating composition is segmented into distinct functional layers: a base layer containing the colour developer on the substrate, and separate colour former layers positioned above. This segmentation prevents unwanted interactions during storage while enabling reaction during use.
2Reliability
If reactive components are modified to reduce reactivity for storage stability, then storage stability improves, but image contrast and intensity are reduced
Solution Approach 1:
The patent changes the physical state parameters of the reactive components by dissolving the colour developer in a water-soluble binder and the colour former in a solvent, creating stable aqueous coating compositions that maintain high reactivity during use while resisting premature reaction during storage.
Solution Approach 2:
The invention uses composite coating structures combining the colour developer layer on the substrate with separate colour former layers containing different solvents and binders. This composite structure enables both storage stability and high image contrast by controlling the interaction between layers.
3Reliability
If microencapsulation is used to prevent discolouring, then storage stability improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent uses simple, inexpensive aqueous coating compositions that can be applied directly without complex encapsulation structures. The coatings are designed to be stable during their intended storage life and function reliably during use, eliminating the need for costly microencapsulation technology.
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 composition maintains minimal darkening during storage and produces images with high contrast and stability under various conditions, including heat, oil, and light, without the need for immediate preparation or modification of reactive components.
Implementation Method 1
the mechanism of image formation is dependent on the thermal reaction between a colour-forming substance and a colour developer
Data Source
AI summary
The present invention provides heat-sensitive coating compositions, which comprise a color developer of formula (1) or mixtures thereof wherein R1 can be hydrogen, C1-20-alkyl, C3-8-cycloalkyl, C2-10-alkenyl, aryl or SO3H, and R2 and R3 can be the same or different and can be hydrogen, halogen, C1-20-alkyl, C3-8-cyclo-alkyl, C2-10-alkenyl, aryl, OR6, NR7R8, SR9, SO3H or COOR10 and R4 and R5 can be the same or different, and can be hydrogen, halogen, C1-20-alkyl, C3-8-cyclo-alkyl, C2-10-alkenyl, aryl, OR6, NR7R8 or SR9, R6, R7, R8, R9 and R10 can be the same or different and can be hydrogen, C1-30-alkyl, C3-8-cycloalkyl, C2-10-alkenyl or aryl, wherein C1-20-alkyl can be unsubstituted or substituted with one or more C3-8-cycloalkyl, C2-10-alkenyl, phenyl, halogen, OR11, NR12R13, SR14, SO3H or COOR15, and aryl can be unsubstituted or substituted with one or more halogen, C1-10-alkyl, halogenated C1-10-alkyl, C3-8-cycloalkyl C2-10-alkenyl, phenyl, OR11, NR12R13, SR14, SO3H or COOR15, wherein R11, R12, R13, R14 and R15 can be the same or different and can be hydrogen, C1-10-alkyl, C3-8-cycloalkyl or C2-10-alkenyl, a process for the preparation of these compositions, a process of coating substrates with these compositions, substrates coated with these compositions, a process for preparing marked substrates using these compositions, marked substrates obtainable by the latter process, and certain color developers.