Two-Part Urethane Adhesive Composition for Fast Cure and Durable Bonding
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Solution Overview
Problem
Existing two-part urethane adhesive compositions suffer from reduced initial adhesiveness and long-term reliability, particularly in the presence of water or high temperatures, due to the use of polyols with high degrees of unsaturation and by-products that cap the urethane prepolymer terminals.
Innovation Solution
A two-part urethane adhesive composition utilizing a polyol compound with a specific degree of unsaturation and ethylene oxide at the terminal, along with a controlled amount of active hydrogen in the curing agent, and incorporating carbon black, to enhance initial and long-term adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a known polyol is used as a curing agent in a two-part urethane adhesive composition, then the composition can be manufactured easily, but initial adhesiveness and long-term adhesiveness become lower
Solution Approach 1:
The patent applies parameter changes by precisely controlling the degree of unsaturation (0.01 meq/g or less) and molecular weight distribution (Mw/Mn ≤ 1.05) of the polyol compound, and by optimizing its molecular weight range (1000-20000). These parameter optimizations resolve the contradiction by achieving both ease of manufacture through well-defined specifications and improved adhesiveness through controlled chemical structure that prevents terminal capping and ensures proper crosslinking density.
Solution Approach 2:
The patent uses a composite curing agent system combining a polyol compound (a1) with specific properties (degree of unsaturation ≤ 0.01 meq/g, Mw/Mn ≤ 1.05, molecular weight 1000-20000) with additional polyol compounds (a2) having three or more active hydrogen-containing groups. This composite approach allows easy manufacture through standardized components while achieving superior initial and long-term adhesiveness through synergistic effects of the combined polyol system.
2Ease of manufacture
If polyol with high degree of unsaturation is used, then the adhesive composition can be prepared, but initial adhesiveness and long-term reliability deteriorate due to by-products capping urethane prepolymer terminals
Solution Approach 1:
The patent applies preliminary anti-action by pre-selecting a polyol compound with extremely low degree of unsaturation (0.01 meq/g or less) and narrow molecular weight distribution (Mw/Mn ≤ 1.05) before the adhesive formulation process. This preliminary selection prevents the formation of harmful by-products that would cap urethane prepolymer terminals, thereby maintaining both ease of manufacture and high initial and long-term adhesiveness without requiring additional purification steps.
Solution Approach 2:
The patent resolves this contradiction through parameter changes by strictly controlling the degree of unsaturation to 0.01 meq/g or less and molecular weight distribution to Mw/Mn of 1.05 or less. These parameter specifications ensure that the polyol compound does not generate excessive by-products during reaction, preventing terminal capping of urethane prepolymer while maintaining manufacturability through well-defined material specifications.
3Ease of manufacture
If the amount of active hydrogen in the curing agent is not optimized, then the formulation process is simple, but rapid curability and adhesiveness under challenging conditions are reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the amount of active hydrogen in the curing agent to a specific ratio relative to the isocyanate groups in the urethane prepolymer. This optimized parameter ensures rapid curability through appropriate crosslinking density while maintaining simple formulation processes. The specific active hydrogen content controls the reaction kinetics and network structure, achieving both ease of manufacture and rapid curing performance.
4Ease of manufacture
If the polyol compound has narrow molecular weight distribution, then the adhesive composition can be formulated, but control over curability and adhesiveness becomes more challenging
Solution Approach 1:
The patent resolves this contradiction through parameter changes by specifying a narrow molecular weight distribution (Mw/Mn ≤ 1.05) combined with a controlled molecular weight range (1000-20000) for the polyol compound. This parameter optimization simplifies formulation by providing predictable reaction behavior and consistent performance, while the low degree of unsaturation (≤ 0.01 meq/g) ensures reliable curability and adhesiveness without requiring complex control mechanisms.
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 rapid curing and maintains excellent adhesiveness over time, even under challenging conditions, by minimizing the impact of by-products and optimizing the active hydrogen content.
Implementation Method 1
a main agent containing a urethane prepolymer having a plurality of isocyanate groups, a curing agent containing a compound (A) having two or more active hydrogen-containing groups per molecule
Implementation Method 2
the two-part urethane adhesive composition further contains carbon black
Implementation Method 3
the polyol compound (a1) having three active hydrogen-containing groups per molecule, having ethylene oxide at a terminal
Data Source
AI summary
An object of the present invention is to provide a two-part urethane adhesive composition that provides excellent initial adhesiveness and excellent long-term adhesiveness. An embodiment of the present invention is a two-part urethane adhesive composition including a main agent containing a urethane prepolymer having an isocyanate group, and a curing agent containing a compound (A) having two or more active hydrogen-containing groups per molecule, the compound (A) including a polyol compound (a1), the polyol compound (a1) having three active hydrogen-containing groups per molecule, having ethylene oxide at a terminal, having a number average molecular weight of greater than 1000 and 20000 or less, having a degree of unsaturation of 0.01 meq/g or less, and having molecular weight distribution (Mw/Mn) of 1.05 or less, and a molar ratio of a total amount of active hydrogen in the compound (A) with respect to an amount of the isocyanate group being 0.2 or greater and less than 0.8.