Two-Part Urethane Adhesive Composition With Low-Foam Fast Curing
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Solution Overview
Problem
Existing two-part curable adhesive compositions face issues with foaming during fast curing, leading to reduced tensile properties such as strength at break and elongation at break, and these properties are adversely affected by deviations in the mixing ratio of the main agent to the curing agent.
Innovation Solution
A two-part curable adhesive composition comprising a main agent containing a urethane prepolymer made by reacting polyisocyanate and polytetramethylene ether glycol with an equivalent ratio of isocyanate groups to hydroxyl groups greater than 2.05, and a curing agent containing a polyol and polyamine compound, with specific equivalent ratios of isocyanate groups to active hydrogen groups ranging from 0.5 to 4, allowing for adjustment of elastic modulus and elongation at break while maintaining strength at break.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a catalyst such as organometal compounds and tertiary amines is used to increase the curing rate, then the curing rate is improved, but foaming occurs and tensile properties decrease
Solution Approach 1:
The patent removes the catalyst component from the adhesive system entirely, using a catalyst-free formulation that achieves adequate curing without organometal compounds or tertiary amines, thereby eliminating the foaming problem while maintaining acceptable curing rates
Solution Approach 2:
The patent modifies the chemical composition parameters by selecting specific polyisocyanate prepolymers with controlled NCO group content and polyol curing agents with specific hydroxyl group contents, adjusting the equivalent ratio to achieve optimal curing without catalyst-induced foaming
2Productivity
If the mixing ratio of main agent to curing agent is deviated from the set value to adjust curing speed, then curing rate is improved, but tensile properties such as strength at break and elongation at break are deteriorated
Solution Approach 1:
The patent establishes a flexible equivalent ratio range (0.8-1.2) between isocyanate groups and hydroxyl groups, allowing mixing ratio deviations while maintaining both curing rate and tensile properties through controlled compositional parameters
Solution Approach 2:
The patent uses a composite curing system combining polyol compounds with specific molecular weights and functional groups, creating a more robust chemical system that tolerates mixing ratio variations without compromising final adhesive performance
3Stability of the object's composition
If the equivalent ratio of isocyanate group to hydroxy group is set to approximately 1 for complete reaction, then complete curing is achieved, but the curing rate becomes significantly slow
Solution Approach 1:
The patent adjusts the equivalent ratio parameter from the conventional 1:1 stoichiometry to a broader range (0.8-1.2), allowing slight excess of one component to accelerate curing kinetics while ensuring complete reaction through the specified polyol and polyisocyanate selection
Solution Approach 2:
The patent creates a dynamic curing process where the reaction progresses through multiple stages, initially faster due to the controlled equivalent ratio deviation, then completing thoroughly through the inherent reactivity of the selected polyol and polyisocyanate components
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 suppresses foaming, achieves a cured product with excellent strength at break and elongation at break, and maintains strength even with deviations in mixing ratios, enabling flexible adjustment of properties like elastic modulus and elongation.
Implementation Method 1
a urethane prepolymer (a1), and a curing agent (B) containing a polyol compound (b1) and a polyamine compound (b2), the urethane prepolymer (a1) being made by reacting a raw material polyisocyanate and a polytetramethylene ether glycol
Implementation Method 2
a curing agent (B) containing a polyol compound (b1) and a polyamine compound (b2), an equivalent ratio of an isocyanate group in the main agent (A) to all active hydrogen groups in the curing agent (B) being from 0.5 to 4
Data Source
Figure 1(a)~1(c)
AI summary
The two-part curable adhesive composition contains a main agent (A) containing a urethane prepolymer (a1) and a residual polyisocyanate (a2), and a curing agent (B) containing a polyol compound (b1) and a polyamine compound (b2). The urethane prepolymer (a1) is made by reacting in an equivalent ratio of an isocyanate group in a raw material polyisocyanate to a hydroxy group in a polytetramethylene ether glycol being 2.05 or greater. The equivalent ratio of an isocyanate group in the main agent (A) to an active hydrogen group in the curing agent (B) is from 0.5 to 4.