Diacetylene Time-Temperature Indicator with UV-Insensitive Recrystallization
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Solution Overview
Problem
Existing diacetylene-based time-temperature indicators (TTIs) are sensitive to UV light, limiting their utility to perishables not exposed to UV, and methods for achieving uniform and reproducible coatings with inactive diacetylenes are inadequate.
Innovation Solution
Inactive diacetylenes are activated by melt-recrystallization into an active phase, forming a thermally active indicator with reduced UV sensitivity, using a binder and additives to create a precursor TTI device with fine crystals, and optionally incorporating UV absorbers and other layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If diacetylenes are used as time-temperature indicators, then they can monitor thermal degradation of perishables, but they are sensitive to UV light which limits their application
Solution Approach 1:
The patent changes the crystalline phase parameter of the diacetylene from inactive to active phase through controlled crystallization from melt, which fundamentally alters the UV sensitivity parameter and enables broader application
Solution Approach 2:
The patent creates a composite system by coating diacetylene on substrates and potentially combining with other materials to achieve both thermal sensitivity and UV resistance, expanding application versatility
2Manufacturing precision
If inactive diacetylenes are coated on substrates using spray or dip coating methods, then they can be converted to active phase upon melting, but it is difficult to obtain fine crystals of uniform size and uniform reproducible coating
Solution Approach 1:
The patent performs preliminary crystallization from melt before coating, ensuring fine uniform crystals are formed in advance, which simplifies the subsequent coating process and ensures manufacturing precision
Solution Approach 2:
The patent utilizes the phase transition of diacetylene from solid to melt and back to solid crystalline phase to achieve uniform crystal formation, combining ease of manufacture with manufacturing precision
3Reliability
If active diacetylenes are used for TTI, then they polymerize upon thermal annealing to indicate temperature, but they remain sensitive to UV light giving false positive signals
Solution Approach 1:
The patent changes the crystalline phase parameter to alter the fundamental response characteristics of diacetylene, creating an active phase that responds to thermal annealing while being insensitive to UV light
Solution Approach 2:
The patent converts the typically harmful UV sensitivity into a beneficial feature by selecting a crystalline phase that is inherently UV-insensitive, while maintaining thermal responsiveness
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 method produces a TTI that is insensitive to UV light, allowing wider application to monitor perishables and provides uniform, reproducible color change with time and temperature.
Implementation Method 1
Inactive diacetylenes are activated by melt-recrystallization into an active phase
Implementation Method 2
a diacetylene which is insensitive to UV light and which is thermally active with increased thermal reactivity to develop color with time and temperature upon melt-recrystallization
Implementation Method 3
Diacetylenes are known to polymerize in the solid state to a highly-colored polymer upon thermal annealing
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3B
AI summary
This application relates to a time-temperature indicator based on increased thermal reactivity of a diacetylene upon melt recrystallization and a method of making it. A diacetylene is crystallized into a low thermal reactivity phase from a solvent system and converted into a higher thermal reactivity phase and low sensitivity to UV light by melt recrystallization.