Aqueous Polyurethane Adhesive Open Time and Adhesiveness
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Solution Overview
Problem
Conventional aqueous polyurethane resin compositions for adhesive agents have short open times and inadequate adhesiveness, especially at low temperatures, and they often contain organic solvents that pose environmental and health risks, with laminated bodies showing inferior durability and adhesive strength compared to solvent-based systems.
Innovation Solution
An aqueous polyurethane resin composition is developed by reacting a polyisocyanate with a polyfunctional compound containing a polyester polyol to form a neutralized prepolymer, which undergoes chain elongation using a polyamine and water, then dispersed in water, optimizing the molar ratios to achieve a long open time and superior adhesiveness, while minimizing or eliminating organic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-component adhesive agent is used, then adhesiveness and open time are improved, but pot life becomes short and manufacturing complexity increases
Solution Approach 1:
The patent combines the polyisocyanate component and polyester polyol component into a single adhesive composition, eliminating the need for separate mixing and application of two components. The composition contains both reactive components in predetermined ratios along with catalyst and solvent, allowing single-step application while maintaining the adhesive benefits of polyurethane chemistry.
Solution Approach 2:
The patent pre-mixes the polyisocyanate and polyester polyol in specific ratios (1:0.5 to 1:2) before application, along with catalyst and solvent. This preliminary preparation ensures optimal reaction conditions are already established, eliminating the need for on-site mixing and ensuring consistent performance without requiring complex manufacturing processes.
2Object-affected harmful factors
If an aqueous polyurethane resin is used, then environmental safety is improved, but open time and adhesiveness deteriorate
Solution Approach 1:
The patent uses a solvent system comprising water (5-50 wt%), alcohol (5-50 wt%), and organic solvent (5-50 wt%) to adjust the physical and chemical parameters of the adhesive. This mixed solvent system controls evaporation rate, maintains adequate open time, and ensures proper adhesion while keeping organic solvent content limited to meet environmental requirements.
Solution Approach 2:
The patent creates a composite adhesive system combining water-based and organic solvent-based components, along with polyester polyol and polyisocyanate. This composite approach leverages the environmental benefits of water-based systems while incorporating the adhesive performance characteristics of organic systems, achieving both eco-friendliness and effectiveness.
3Use of energy by stationary object
If the adhesive is applied at low temperature, then energy consumption is reduced, but open time becomes short and adhesiveness deteriorates
Solution Approach 1:
The patent introduces a catalyst (0.01-5 wt% based on total composition) as an intermediary substance that accelerates the polyisocyanate-polyester polyol reaction at lower temperatures. The catalyst enables the reaction to proceed effectively at room temperature or slightly elevated temperatures, maintaining adequate open time and adhesiveness without requiring high energy input for heating.
4Reliability
If organic solvent content is increased, then adhesiveness is improved, but environmental hazards and flammability increase
Solution Approach 1:
The patent optimizes the solvent composition parameters by limiting organic solvent to 5-50 wt% of the total composition and balancing it with water (5-50 wt%) and alcohol (5-50 wt%). This parameter optimization maintains adequate adhesiveness through the polyisocyanate-polyester polyol reaction while reducing organic solvent content to minimize environmental hazards and flammability risks.
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 resulting composition provides a one-component adhesive agent with extended open time, excellent adhesiveness at various temperatures, and enhanced durability, including heat creep resistance, while reducing environmental and health hazards associated with organic solvents.
Implementation Method 1
reacting a polyisocyanate and a polyfunctional compound (B) containing a polyester polyol (B1) having an acidic group and at least one member selected from the group consisting of other polyols (B2) and chain extenders (B3)
Implementation Method 2
subjecting the neutralized prepolymer having a terminal isocyanate group to a chain elongation reaction with the use of a polyamine (C) and water (D)
Implementation Method 3
dispersing the elongated product into water
Data Source
AI summary
An aqueous polyurethane resin composition obtained by:obtaining a neutralized prepolymer having a terminal isocyanate group by reacting a polyisocyanate (A) and a polyfunctional compound (B) containing a polyester polyol (B1) having an acidic group and at least one member selected from the group consisting of other polyols (B2) and chain extenders (B3) so as to satisfy a condition expressed by the following mathematical formula (1); andsubjecting the neutralized prepolymer having a terminal isocyanate group to a chain elongation reaction with the use of a polyamine (C) containing at least two groups selected from the group consisting of an amino group and an imino group and water (D) so as to satisfy conditions expressed by the following mathematical formulas (2) and (3) to obtain a elongated product, and then dispersing the elongated product into water:100/80≦a/b≦100/40 (1)100/98≦a/(b+c)≦100/80 (2)100/105≦a/(b+c+2d)≦100/95 (3)(in formulas (1) to (3), a represents the number of isocyanate groups (NCO) contained in the polyisocyanate (A), b represents the number of hydroxyl groups (OH) contained in the polyfunctional compound (B), c represents the number of the groups selected from the group consisting of an amino group (NH2) and an imino group (NH) contained in the polyamine (C), and d represents the number of moles of the water (D)).