Diphenolic Acid Epoxy Curing Agent for Fast Hard Room-Temperature Coatings
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Solution Overview
Problem
Epoxy resin-based room temperature-curing compositions used in coatings suffer from slow curing under cold conditions, surface defects like cloudiness and tack, low final hardness, and toxicity issues with traditional curing agents, particularly salicylic acid, which is also undesirable for high-quality coatings.
Innovation Solution
A curing agent comprising a room temperature liquid amine with 6 to 15 carbon atoms and two primary amino groups, diphenolic acid, and optionally a thinner like benzyl alcohol, which accelerates curing, enhances final hardness, reduces yellowing, and minimizes surface defects, while being sustainable and less toxic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional curing agents like salicylic acid are used, then rapid curing is achieved, but final hardness is low and yellowing occurs
Solution Approach 1:
The invention uses a composite curing agent system combining diphenolic acid with a polyamine (such as isophoronediamine). This composite approach leverages the rapid curing capability of diphenolic acid while the polyamine component contributes to achieving high final hardness, thus resolving the contradiction between curing speed and final hardness.
Solution Approach 2:
The invention changes the chemical composition parameters of the curing agent by selecting diphenolic acid with specific structural characteristics (two phenolic hydroxyl groups and a carboxylic acid group) and combining it with polyamines having specific molecular weights and structures. This parameter optimization enables both rapid curing and high final hardness.
2Temperature
If traditional curing agents are used, then curing occurs at room temperature, but surface defects like cloudiness and tack appear
Solution Approach 1:
The invention optimizes the chemical composition of the curing agent by using diphenolic acid combined with specific polyamines, which changes the curing reaction characteristics. This enables the system to cure at room temperature while avoiding surface defects such as cloudiness and tack, achieving both low curing temperature and high surface quality.
3Productivity
If salicylic acid is used as curing agent, then rapid curing is achieved, but toxicity to reproduction occurs
Solution Approach 1:
The invention replaces the toxic salicylic acid with diphenolic acid combined with polyamines. This substitution maintains the rapid curing efficiency needed for productive applications while eliminating the reproduction toxicity associated with salicylic acid, creating a safer curing system.
4Speed
If curing is accelerated under cold conditions, then curing speed improves, but blushing increases
Solution Approach 1:
The invention changes the chemical parameters of the curing system by using diphenolic acid with its specific molecular structure (containing two phenolic hydroxyl groups and a carboxylic acid group) combined with polyamines. This composition modification enables accelerated curing even under cold conditions while suppressing the formation of blushing, a harmful surface defect.
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 curing agent enables rapid curing, high final hardness, low yellowing, and improved surface quality, with reduced blushing, making it suitable for coatings that are processible and environmentally friendly, especially when using renewable raw materials.
Implementation Method 1
They consist of liquid resin components and curing agent components, which are mixed before application and cure at ambient temperatures to form a material of high strength and stability
Implementation Method 2
cure at ambient temperatures to form a material of high strength and stability
Data Source
AI summary
A curing agent for epoxy resins, the curing agent including: at least one amine, which is liquid at room temperature and has 6 to 15 C atoms and two primary amino groups; at least one diphenolic acid of formula (I); and at least one diluent. The curing agent is very simple to prepare, has low viscosity, and provides coatings which: can be applied at ambient temperatures; have good processability; have surprisingly rapid curing; have a high final hardness; have a qualitatively high-grade surface; and have a surprisingly low tendency towards yellowing.