Two-Part Curable Compositions for Phase Stability and Adhesion
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Solution Overview
Problem
Existing epoxy formulations fail to provide satisfactory adhesion retention while maintaining room temperature stability, leading to phase separation over time.
Innovation Solution
A two-part curable composition comprising a polyamide made from dimerized fatty acid and triethylenetetramine, a polyamide from dimerized fatty acid and diethylene glycol diaminoalkyl ether, an epoxy-amine adduct from diglycidyl ether of bisphenol-A and diethylene glycol diaminoalkyl ether, and optionally a polyamine and tris-2,4,6-(dimethylaminomethyl) phenol, which maintains a single phase at room temperature for over 6 months and demonstrates high lap shear strength on epoxy and steel substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing epoxy formulations prioritize adhesion retention, then adhesion strength is improved, but room temperature stability deteriorates leading to phase separation
Solution Approach 1:
The patent employs a composite curing agent system comprising multiple polyamides with different molecular weights and structures (polyamide A from dimerized fatty acid and polyamine, polyamide B from dimerized fatty acid and diaminoalkyl ether). This composite approach allows the formulation to achieve both high adhesion retention and room temperature stability by combining the complementary properties of different polyamide components, preventing phase separation while maintaining strong substrate bonding.
Solution Approach 2:
The patent optimizes specific parameters including the molecular weight distribution of polyamides, the ratio of different curing agents (typically polyamide A:polyamide B in ranges of 90:10 to 50:50), and the epoxy equivalent weight. These parameter adjustments enable the formulation to balance adhesion properties with long-term room temperature stability, achieving greater than 50% adhesion retention at elevated temperatures while maintaining single-phase stability for over 6 months at room temperature.
2Stability of the object's composition
If epoxy formulations are designed for long-term room temperature stability, then phase separation is prevented, but adhesion strength deteriorates over time
Solution Approach 1:
The patent uses a composite curing agent system where polyamide A (from dimerized fatty acid and polyamine) provides excellent adhesion properties, while polyamide B (from dimerized fatty acid and diaminoalkyl ether) enhances room temperature stability. The synergistic combination of these two polyamides in specific ratios enables the formulation to simultaneously achieve high adhesion strength retention and long-term phase stability without compromising either property.
Solution Approach 2:
The patent applies local quality by using polyamides derived from dimerized fatty acids which contain specific functional groups and molecular structures that provide localized adhesion enhancement at the substrate interface while the overall composition maintains bulk phase stability. The diaminoalkyl ether component specifically targets adhesion improvement without disrupting the global phase stability of the formulation.
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 substantial phase stability and maintains lap shear strength of over 3100 psi on epoxy and 3200 psi on steel, with retention exceeding 50% and 43% at elevated temperatures.
Implementation Method 1
The so-provided compositions are capable of demonstrating substantially no phase separation at room temperature for a period of time of greater than about 6 months and/or maintaining a single-phase at room temperature for a period of time of greater than about 6 months
Implementation Method 2
when Part A and Part B are mixed together, dispensed onto a surface of a substrate constructed of epoxy or steel, and mated with another surface constructed of epoxy or steel, cured products thereof are capable of demonstrating at least one of the following physical properties: (a) lap shear strength on a surface constructed of epoxy of greater than or equal to about 3100 psi and lap shear strength retention at about 65° C. of greater than 50%; and (b) lap shear strength on a surface constructed of steel of greater than or equal to about 3200 psi and lap shear strength retention at about 65° C. of greater than 43%
Data Source
AI summary
Two-part curable compositions capable of demonstrating substantially no phase separation at room temperature over time and improved adhesion strength retention at elevated temperature conditions.