Coated Urea Curing Agent Particles for Epoxy Resins
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Solution Overview
Problem
Epoxy resin compositions with urea compounds as curing agents face challenges in achieving both storage stability and heat stability, particularly in applications where temperature fluctuations occur, and have low solubility and fluidity issues during heating.
Innovation Solution
Coating urea compound-containing epoxy resin curing agent particles with specific Group 4 or Group 13 element-containing compounds, such as alkoxide, chelate, or acylate compounds, to enhance storage and heat stability while maintaining solubility and fluidity during heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a urea compound is used as a curing agent in epoxy resin composition, then solubility during heating and fluidity after dissolution are improved, but storage stability deteriorates
Solution Approach 1:
The curing agent is divided into two functional parts: a urea compound core that provides solubility and curing acceleration, and a hydrophobic coating layer that prevents premature reaction. This segmentation allows each part to perform its specific function without interfering with the other, resolving the contradiction between solubility and storage stability
Solution Approach 2:
A hydrophobic coating layer acts as an intermediary between the urea compound core and the epoxy resin. This coating prevents direct contact and premature reaction during storage, while allowing the urea compound to dissolve and function during heating. The coating serves as a temporary barrier that is overcome under heating conditions
2Productivity
If a urea compound is used as a curing agent in epoxy resin composition, then curing acceleration and decreased curing temperature are achieved, but heat stability deteriorates
Solution Approach 1:
The curing agent is segmented into a reactive urea core and a protective hydrophobic coating. The coating segment prevents premature curing at elevated temperatures during application, while the core segment remains ready to provide curing acceleration when the coating is overcome during the curing process
Solution Approach 2:
The hydrophobic coating applies a preliminary protective action that prevents the urea compound from reacting with epoxy resin under heat exposure during storage and application. This preliminary protection counteracts the potential harmful effect of heat-induced premature curing, allowing the system to maintain stability until intentional curing is desired
3Stability of the object's composition
If the latency of a solid epoxy resin curing agent is increased to prevent storage stability problems, then storage stability is improved, but the ability to cure at ordinary temperature deteriorates
Solution Approach 1:
The system uses parameter changes in temperature to control reactivity. At ordinary temperatures, the hydrophobic coating maintains low reactivity and high storage stability. When heated, the coating becomes permeable or dissolves, changing the reactivity parameter to enable curing. This parameter change allows the same system to exhibit both high stability and high reactivity under different conditions
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 coated particles provide excellent storage stability and heat stability to epoxy resin compositions, ensuring solubility during heating and fluidity after dissolution, thereby improving the handling and application properties of the epoxy resin.
Implementation Method 1
a Group 4 or Group 13 element-containing compound (B) coating the surface of the particle
Implementation Method 2
a curing agent that is used in, for example, fiber-reinforced thermosetting plastic is required to dissolve in a matrix resin
Implementation Method 3
the urea compound acts as a curing accelerator, can decrease the curing temperature (about 180° C.) of dicyandiamide down to about 120° C.
Data Source
AI summary
Provided is a urea compound-containing epoxy resin curing agent particle that can impart excellent storage stability and heat stability to an epoxy resin composition including a urea compound as a curing agent, while maintaining the solubility of the urea compound during heating and the fluidity after dissolution of the urea compound. The surface of the urea compound-containing epoxy resin curing agent particle is coated with a Group 4 or Group 13 element-containing alkoxide compound, chelate compound, and/or acylate compound.