UV Curable Coating for Aqueous Microcapsule Encapsulation
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Solution Overview
Problem
Existing microencapsulation processes struggle with encapsulating aqueous materials, requiring extensive drying and not being suitable for forming curable coatings without moisture removal, which is a limitation in applications like carbonless paper and adhesive coatings.
Innovation Solution
A UV curable coating process using a water-in-oil emulsion where UV curable monomers or oligomers form the 'oil' phase, allowing for the encapsulation of water-soluble or water-dispersible core materials without the need for extensive drying, using prepolymers and a polymerization catalyst to create microcapsules that can be cured with UV light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microencapsulation processes are used to encapsulate aqueous materials, then the core material can be encapsulated, but extensive drying sections are required to remove moisture
Solution Approach 1:
The invention changes the dispersion medium from water-based to oil-based, forming a water-in-oil emulsion where aqueous core materials are encapsulated. This parameter change eliminates the need for extensive drying sections while maintaining encapsulation capability, as the oil continuous phase allows direct curing without moisture removal
Solution Approach 2:
The invention utilizes phase transition by forming a water-in-oil emulsion where the aqueous core material is dispersed in an oil phase. The UV curable monomers or oligomers in the oil phase undergo polymerization phase transition upon UV irradiation, forming a cured coating that entraps the aqueous core material without requiring drying
2Ease of operation
If oil in water emulsion is used for microencapsulation, then the coating can be applied, but extensive drying is required to drive off excess moisture
Solution Approach 1:
The invention inverts the conventional oil-in-water emulsion to a water-in-oil emulsion. Instead of dispersing oil droplets in water, the invention disperses aqueous core material droplets in an oil phase containing UV curable monomers. This inversion eliminates the need for drying while maintaining coating applicability and ease of operation
Solution Approach 2:
The invention replaces the thermal drying process with a photochemical curing process. UV irradiation initiates polymerization of the monomers or oligomers in the oil phase, forming a cured coating that entraps the aqueous core material. This substitution eliminates the need for extensive drying sections and reduces processing time
3Reliability
If conventional microencapsulation is used, then aqueous materials can be encapsulated, but the process is not suitable for forming curable coatings without moisture removal
Solution Approach 1:
The invention merges the encapsulation process with the coating formation process by incorporating UV curable monomers or oligomers into the oil phase. The water-in-oil emulsion is directly applied as a coating and cured with UV light, combining encapsulation and coating formation into a single versatile process that does not require moisture removal
Solution Approach 2:
The invention creates a multi-functional system where the oil phase serves multiple purposes: it acts as a dispersion medium for the aqueous core material, provides UV curable monomers or oligomers for coating formation, and enables direct curing without drying. This universal approach enhances adaptability for forming curable coatings with encapsulated aqueous materials
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
This process enables the formation of a curable coating without the need for elaborate drying sections, allowing for the direct application and curing of microcapsules containing an aqueous core, improving efficiency and reducing processing costs.
Implementation Method 1
UV curable monomers or oligomers are dispersed into the water immiscible phase solution... Irradiating the monomers or oligomers with ultra violet light decomposes the UV free radical initiator and causes cure of the water immiscible phase solution
Implementation Method 2
Irradiating the monomers or oligomers with ultra violet light decomposes the UV free radical initiator and causes cure of the water immiscible phase solution
Data Source
AI summary
The present invention describes a process of preparing microcapsules in a UV curable water immiscible phase. The microcapsules formed according to the invention contain an aqueous phase core. The process comprises dispersing a water soluble or dispersible core material along with at least one wall forming prepolymer and a polycondensation polymerization catalyst into an aqueous solution. The aqueous phase is then dispersed into the water immiscible phase comprising UV curable monomers or oligomers forming droplets of the aqueous phase solution in the water immiscible phase. Polycondensation of the prepolymers is initiated to form polymeric wall material or microcapsules at or near the interface of the water immiscible solvent and droplets of aqueous phase solution. Following capsule formation, a UV initiator is dispersed in the water immiscible phase. The UV curable dispersion containing aqueous microcapsules can be coated on a substrate. The coating is then cured by UV irradiation forming a gelled, solidified, or dry coating of aqueous microcapsules.