Microcapsule Shell Crosslinking for Adhesiveness and Hardness Balance
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Solution Overview
Problem
Existing ink jet image forming methods face challenges in achieving a balance between film adhesiveness to a substrate and hardness, as microcapsules with polymerizable compounds tend to prioritize either adhesiveness or hardness, making it difficult to form films with compatible properties.
Innovation Solution
An aqueous dispersion containing microcapsules with a three-dimensional cross-linked shell and a core comprising di- or lower functional and tri- or higher functional polymerizable compounds, along with a photopolymerization initiator, which are designed to provide a specific proportion and weight-average molecular weight range to enhance both adhesiveness and hardness when irradiated with active energy rays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a microcapsule core contains a polymerizable compound with excellent adhesiveness to a substrate, then the formed film has excellent adhesiveness, but the film hardness becomes inferior
Solution Approach 1:
The invention changes the chemical composition parameters of the polymerizable compound in the microcapsule core. Specifically, it uses compounds with specific functional groups (carboxyl, hydroxyl, or amino groups) and controls the molecular weight and functional group content to achieve a balance between adhesiveness and hardness that cannot be obtained with conventional polymerizable compounds
Solution Approach 2:
The invention creates a composite system by combining the microcapsule core containing the polymerizable compound with a curing agent that forms crosslinked structures. This composite approach allows the film to simultaneously achieve excellent adhesiveness (from the polymerizable compound) and hardness (from the crosslinked network structure)
Solution Approach 3:
The invention applies local quality by having the polymerizable compound with specific functional groups concentrated in the microcapsule core, while the crosslinked structure forms in the film matrix. This spatial distribution allows different regions to contribute different properties: the core provides adhesiveness-enhancing groups, while the crosslinked matrix provides hardness
2Temperature
If a microcapsule core contains a polymerizable compound with excellent hardness, then the formed film has excellent hardness, but the adhesiveness to a substrate becomes inferior
Solution Approach 1:
The invention modifies the molecular weight and functional group parameters of the polymerizable compound. By using compounds with molecular weights of 100-1000 and specific functional group contents (0.1-5.0 mmol/g), it achieves a balance where the film attains both hardness and adhesiveness simultaneously
Solution Approach 2:
The invention employs a composite material system where the microcapsule core contains a polymerizable compound that forms a crosslinked network structure upon curing. This composite structure integrates the hardness-providing crosslinked matrix with adhesiveness-providing functional groups, resolving the contradiction between these two properties
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 proposed solution enables the formation of images with excellent adhesiveness to a substrate and hardness, improving the compatibility of these properties in the resulting film.
Implementation Method 1
the core contains a polymerizable compound and a photopolymerization initiator, wherein a weight-average molecular weight of the polymerizable compound is 100 to 1000
Implementation Method 2
a shell that has a three-dimensional cross-linked structure
Data Source
AI summary
Provided are a microcapsule including a shell that has a three-dimensional cross-linked structure containing at least one bond selected from a urethane bond or a urea bond, and including a core that contains a di- or lower functional polymerizable compound, a tri- or higher functional polymerizable compound, and a photopolymerization initiator, in which a proportion of the di- or lower functional polymerizable compound is 20% by mass or more with respect to a total mass of the di- or lower functional polymerizable compound and the tri- or higher functional polymerizable compound; an aqueous dispersion; and a method for manufacturing an aqueous dispersion; and an image forming method using the same.