Self-Emulsifying Microcapsule Pigment for Thermochromic Ink
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Solution Overview
Problem
Existing thermochromic pigments require post-treatment processes like centrifugal separation and drying, leading to wastewater pollution, and their wall materials often contain carcinogenic substances like formaldehyde, posing environmental and health risks.
Innovation Solution
A microcapsule type thermochromic pigment is developed using a core material comprising leuco dye, developer, and stearic acid 2-[4-(phenylmethoxy)phenyl]ethyl ester, wrapped with self-emulsifying polyurethane or epoxy resin as the wall material, which can be used directly without post-treatment and avoids toxic substances, ensuring stability and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-treatment processes such as centrifugal separation and drying are used, then the thermochromic pigment can be obtained and used, but wastewater is produced and the environment is polluted
Solution Approach 1:
The patent extracts and removes the harmful post-treatment processes (centrifugal separation and drying) from the preparation method. By reformulating the wall material to be water-soluble, the pigment particles can be directly used in aqueous ink formulations without requiring separation or drying steps, thereby eliminating wastewater generation while maintaining pigment usability.
Solution Approach 2:
The patent changes the key parameter of wall material solubility from water-insoluble to water-soluble. This parameter change allows the pigment to be directly dispersed in water-based ink systems, eliminating the need for organic solvents and post-treatment processes, thus resolving the contradiction between usability and environmental harm.
2Reliability
If ureaformaldehyde resin prepolymer is used as wall material, then the microcapsules can be formed, but carcinogenic formaldehyde is contained
Solution Approach 1:
The patent extracts and removes the harmful ureaformaldehyde resin from the wall material composition. It replaces this carcinogenic material with water-soluble polymers such as polyvinyl alcohol, carboxymethyl cellulose, or starch derivatives, which provide the same microcapsule formation function without releasing formaldehyde, thus eliminating the harmful effect while preserving structural integrity.
Solution Approach 2:
The patent employs composite wall materials made from water-soluble polymers that combine the encapsulation function with environmental safety. These composite materials maintain the microcapsule structure while avoiding carcinogenic substances, resolving the contradiction between structural integrity and harmful factors.
3Ease of manufacture
If conventional thermochromic pigment is used, then color change function is achieved, but white marks appear after thermal decolorization
Solution Approach 1:
The patent changes the optical parameters of the wall material to improve transparency. By selecting water-soluble polymers with appropriate molecular weights and compositions, the wall material becomes optically transparent or translucent in the decolorized state, eliminating white marks while preserving the thermochromic color change function.
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 allows for direct use of the microcapsule pigment without separation, reduces environmental impact, and provides good optical properties with no white marks after thermal or frictional decolorization, while maintaining high color density and thermal stability, enhancing the safety and performance of thermochromic inks.
Implementation Method 1
The thermochromic pigment is a pigment that can repeatedly change its color as the temperature rises or falls
Implementation Method 2
mixing the molten mixture with raw material of the wall material and a cosolvent, then adding to water, subjecting them to an emulsification, to obtain an emulsion
Data Source
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AI summary
The present disclosure provides a microcapsule type thermochromic pigment and a preparation method and use thereof, and a thermochromic ink and use thereof, and belongs to the technical field of thermochromic materials. The microcapsule type thermochromic pigment provided by the present disclosure comprises a core material and a wall material wrapping the core material, wherein the core material comprises the following components: a leuco dye, a developer and stearic acid 2-[4-(phenylmethoxy)phenyl]ethyl ester, and the wall material is self-emulsifying polyurethane or self-emulsifying epoxy resin. The present disclosure uses self-emulsifying polyurethane or self-emulsifying epoxy resin as the wall material, so that the obtained microcapsule type thermochromic pigment can be stably dispersed in the slurry and can be used directly without separating the microcapsule type thermochromic pigment. The wall material does not contain volatile and toxic substances such as formaldehyde.