Cyclic Carbodiimide Thermosetting Resin Composition
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Solution Overview
Problem
Thermosetting resin compositions with epoxy resins face challenges in achieving high heat resistance and fast curability at low temperatures, while avoiding the production of free isocyanates when using carbodiimide compounds, and amine-based curing agents have short pot lives and require high curing temperatures.
Innovation Solution
A thermosetting resin composition comprising an epoxy resin, a cyclic carbodiimide compound with a specific cyclic structure, and a polyvalent amine-based curing agent, which functions as a curing agent or accelerator, preventing free isocyanate production and enhancing heat resistance and curing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a carbodiimide compound is used as a curing agent for epoxy resin, then adhesion to another member is improved and flowability is enhanced, but free isocyanate is produced by high-temperature treatment causing deterioration of another member
Solution Approach 1:
The patent changes the molecular structure parameter of the carbodiimide compound from linear to cyclic form. This structural parameter change prevents the decomposition reaction that produces free isocyanate while maintaining the adhesion-enhancing properties. The cyclic structure undergoes a different reaction pathway during curing that does not release harmful isocyanate byproducts.
Solution Approach 2:
The patent converts the potentially harmful decomposition behavior of carbodiimide compounds into a beneficial curing mechanism. By using the cyclic carbodiimide structure, the compound's reactivity is harnessed to promote curing and adhesion without producing the harmful free isocyanate that would otherwise result from high-temperature treatment of conventional carbodiimides.
2Temperature
If an amine-based curing agent is used to achieve high heat resistance, then heat resistance is improved, but pot life becomes short and high curing temperature is required
Solution Approach 1:
The patent creates a composite curing system by combining cyclic carbodiimide compound with epoxy resin. This composite approach allows the cyclic carbodiimide to act as both curing agent and adhesion promoter, achieving high heat resistance through the cured network structure while maintaining extended pot life due to the slower, more controlled reaction kinetics of the cyclic carbodiimide compared to conventional amine-based curing agents.
3Productivity
If conventional curing agents are used to achieve fast curability, then curing speed is improved, but curing temperature must be high which limits equipment and causes damage to resins
Solution Approach 1:
The patent changes the chemical reactivity parameters of the curing system by using cyclic carbodiimide compound. This structural modification enables the curing reaction to proceed at lower temperatures while maintaining practical curing speeds. The cyclic structure provides a balance between reaction activation energy and reaction rate, allowing effective curing without the high temperatures required by conventional amine-based curing agents.
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 composition achieves high heat resistance, fast curing at low temperatures, and extended pot life, with improved adhesion and flowability, suitable for applications in electronic and automotive fields.
Implementation Method 1
a cyclic carbodiimide compound (component B) including a cyclic structure having one carbodiimide group... a polyvalent amine-based curing agent (component b)... the curing agent reacts with the compound
Implementation Method 2
fast curability at the time of heating and curing properties at a relatively low temperature... fast curing at low temperatures
Data Source
AI summary
A thermosetting resin composition which produces no free isocyanate even when a carbodiimide compound is used and provides a cured resin having high heat resistance. The thermosetting resin composition makes it possible to reduce the curing temperature, cures in a short time and provides a cured rein having a high glass transition temperature. The thermosetting resin composition comprises: (A) an epoxy resin (component A); and (B) a cyclic carbodiimide compound (component B) including a cyclic structure having one carbodiimide group and represented by the following formula (B-i) in which first nitrogen and second nitrogen are bonded together by a bond group and having 8 to 50 atoms forming the cyclic structure: (wherein Q is bivalent to tetravalent bond group which is an aliphatic group, alicyclic group, aromatic group, or a combination of these groups and may contain a hetero atom or substituent); and/or (b) a polyvalent amine-based curing agent (component b) represented by the following formula (b-i): (wherein Ar1 to Ar4 are each independently a phenylene group or naphthalene-diyl group which may be substituted by a substituent).