Three-Component Polyurethane Adhesive Latency and Curing
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Solution Overview
Problem
Two-part polyurethane adhesives used in fiber-reinforced plastics have limited flexibility due to fast curing, leading to clogging issues in dispensing equipment and material waste, as they require frequent flushing, which results in a trade-off between open time and curing speed.
Innovation Solution
A three-component polyurethane adhesive composition comprising a first polyol component, a second polyol component, and an isocyanate component, with specific catalysts and chain extenders, allowing for a longer open time without the need for frequent flushing and enabling rapid curing at ambient temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If two-part polyurethane adhesives are used with fast curing compounds, then rapid strength build-up is achieved, but open time is limited and mixer stand time is reduced
Solution Approach 1:
The adhesive system is divided into three separate components (first polyol component, second polyol component, and isocyanate component) that are mixed immediately before application. This segmentation allows each component to remain stable individually while providing extended open time, and enables rapid curing once mixed through the controlled interaction of all three components.
Solution Approach 2:
The patent introduces a third component (isocyanate component) as an intermediary that reacts with both polyol components. This intermediary approach allows for controlled curing kinetics where the isocyanate acts as a bridge between the two polyol components, enabling both extended open time and rapid final cure.
2Speed
If two-part adhesives are used with fast reacting compounds, then rapid cure is achieved, but frequent flushing is required causing material waste
Solution Approach 1:
By segmenting the adhesive into three components, the system extends the usable life of mixed adhesive in the dispenser, reducing the frequency of flushing operations and thereby reducing material waste while maintaining rapid curing capabilities.
Solution Approach 2:
The patent modifies the chemical parameters of the adhesive system by introducing a three-component formulation with specific catalyst combinations (organometallic catalyst and cyclic amine catalyst) that control reaction kinetics. This allows for extended mixer stand time without sacrificing final cure speed, reducing the need for frequent flushing.
3Loss of substance
If open time is extended to reduce flushing frequency, then material waste is reduced, but curing speed decreases
Solution Approach 1:
The patent changes the chemical parameters by using a three-component system with controlled catalyst concentrations (0.01-1 wt% organometallic catalyst and 0.01-1 wt% cyclic amine catalyst) that regulate the reaction rate. This allows the adhesive to remain workable for extended periods while maintaining the capability for rapid curing when the final set occurs.
Solution Approach 2:
The curing process is made dynamic through the three-component formulation, where the reaction rate can be controlled during the open time period and then accelerates rapidly when the adhesive is applied and the curing process is initiated, providing both extended workability and fast final cure.
4Duration of action of moving object
If mixer stand time is increased to reduce flushing, then open time is extended, but adhesive may gel in the mixer
Solution Approach 1:
The patent modifies the chemical stability parameters by introducing a three-component system with controlled catalyst levels and specific component formulations that prevent premature gelling during extended mixer stand time, while ensuring reliable curing performance when the adhesive is applied.
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 three-component adhesive composition provides excellent latency and rapid cure, reducing material waste and equipment flushing frequency while maintaining strong bonding properties, even at room temperature, with improved handling strength and durability.
Implementation Method 1
from 0.01 to 1 weight percent, based on the total weight of the first polyol component, of one or more latent room temperature organometallic catalysts; and from 0.01 to 1 weight percent, based on the total weight of the first polyol component, of one or more blocked cyclic amidine compound catalysts
Implementation Method 2
The two components of the two-part polyurethane adhesives are mixed such that the polyol component reacts with the isocyanate component to build up the network and polymerize
Implementation Method 3
the three-component polyurethane adhesive composition provides excellent latency and rapid cure, reducing material waste and equipment flushing frequency while maintaining strong bonding properties, even at room temperature
Data Source
AI summary
Disclosed are latent three-component polyurethane adhesive compositions which includes; (a) a first polyol component comprising (i) one or more polyols having a hydroxyl equivalent weight of 400 to 2000 and a nominal hydroxyl functionality of 2 to 4; (ii) one or more aliphatic diol chain extenders; (iii) from 0.01 to 1 weight percent, based on the total weight of the first polyol component, of one or more latent room temperature organometallic catalysts; and (iv) from 0.01 to 1 weight percent, based on the total weight of the first polyol component, of one or more one or more blocked cyclic amidine compound catalysts or one or more phenol-blocked cyclic amidine compounds catalysts; (b) a second polyol component comprising (i) one or more polyols having a hydroxyl equivalent weight of 400 to 2000 and a nominal hydroxyl functionality of 2 to 4; (ii) one or more aliphatic diol chain extenders; (iii) from 0.01 to 1 weight percent, based on the total weight of the second polyol component, of one or more latent room temperature organometallic catalysts; and (iv) from 0.01 to 1 weight percent, based on the total weight of the second polyol component, of one or more blocked cyclic amidine compound catalysts or one or more phenol-blocked cyclic amidine compounds catalysts; and (c) an isocyanate component comprising (i) one or more isocyanate compounds; wherein the isocyanate component and the first and second polyol components are contacted at an isocyanate index of 0.5 to 2.