Aqueous Polyurethane Dispersion Adhesive Stability
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Solution Overview
Problem
Existing waterborne adhesive compositions for laminating metal foils and polymer films face challenges in stability, adhesion, and settling during storage, and they often require improvements in bonding strength, especially when used in dry bond lamination methods.
Innovation Solution
An aqueous polyurethane dispersion is developed, comprising reaction products of polyisocyanates, polyols, and organometallic compounds, with specific structures and ratios, which forms a stable and effective adhesive layer upon drying, enhancing adhesion between metal foils and polymer films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional waterborne adhesive compositions are used for bonding metal foil to polymer film, then the adhesive can be applied and dried, but the composition shows instability with settling and phase separation during storage
Solution Approach 1:
The patent uses a composite adhesive system combining polyurethane dispersion with organometallic compound particles (containing metals like Al, Zn, Ca, Mg) dispersed in aqueous medium. This composite structure provides both storage stability through the dispersed particle system and reliable adhesion to metal foils through the metal-containing particles that bond to the metal substrate.
Solution Approach 2:
The patent modifies the adhesive composition by controlling particle size distribution (0.1-10 μm organometallic particles), pH (5.0-7.0), and solids content (30-70%). These parameter optimizations ensure both storage stability preventing settlement and effective adhesion performance on metal and polymer substrates.
2Stability of the object's composition
If the adhesive composition is made more stable to prevent settling, then storage stability improves, but adhesion strength to substrates decreases
Solution Approach 1:
The patent creates local quality differentiation within the adhesive layer by using organometallic particles concentrated at the metal foil interface (providing strong metal-to-metal adhesion) while the polyurethane dispersion provides continuous matrix binding to the polymer film. This localized functional distribution maintains both stability and strength.
Solution Approach 2:
The composite system of polyurethane dispersion (providing matrix continuity and polymer adhesion) combined with suspended organometallic particles (providing metal adhesion and stability) achieves both settlement resistance and high bonding strength through synergistic material combination.
3Duration of action of stationary object
If conventional adhesive formulations are used, then the composition can be stored, but phase separation occurs during storage
Solution Approach 1:
The patent optimizes pH to 5.0-7.0 (slightly acidic to neutral) and controls solids content at 30-70% to maintain colloidal stability of the aqueous dispersion. These parameter settings prevent phase separation during long-term storage while maintaining adhesion effectiveness.
Solution Approach 2:
The aqueous medium acts as an intermediary carrier that stabilizes the dispersion of organometallic particles and polyurethane. The water-based system with controlled pH and surfactants prevents direct aggregation of particles, maintaining phase stability during storage.
4Ease of operation
If the adhesive layer is dried completely before lamination, then the bonding process is simplified, but adhesion strength to metal foil decreases
Solution Approach 1:
The organometallic particles are pre-dispersed and positioned within the adhesive layer before application. During the drying process, these particles migrate to and bond with the metal foil surface, preparing the interface for strong adhesion even with simplified single-step drying processes.
Solution Approach 2:
The organometallic particles in the adhesive composition self-assemble and self-bond to the metal foil surface during the drying process without requiring additional treatment steps. This self-service mechanism maintains strong metal adhesion while simplifying the overall lamination process.
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 aqueous polyurethane dispersion provides improved stability, prevents settling, and achieves strong adhesion, as demonstrated by higher bonding strength values in T-peel tests, making it suitable for dry bond lamination applications.
Implementation Method 1
the polyurethane is the reaction product of polyurethane formation reactants comprising (i) one or more polyisocyanate, (ii) a polyol component comprising one or more polyol, and (iii) one or more organometallic compound having the structure wherein n is 0 or 1, t is 0 or 1, r is 0 or 1, p is 0 to 2, q is 0 to 13, at least one of p and q is not zero, M is a metal that is not silicon
Implementation Method 2
drying said layer or allowing said layer to dry to form a dried adhesive layer
Implementation Method 3
It is further desired that the waterborne adhesive composition provide good adhesion to substrates, especially when bonding a metal foil to a polymer film
Data Source
AI summary
Provided is an aqueous polyurethane dispersion comprising (a) dispersed particles of said polyurethane, wherein said polyurethane is the reaction product of polyurethane formation reactants comprising (i) one or more polyisocyanate, (ii) a polyol component comprising one or more polyol, and (iv) one or more organometallic compound having the structure (I) wherein n is 0 or 1, t is 0 or 1, r is 0 or 1, p is 0 to 2, q is 0 to 13, at least one of p and q is not zero, M is a metal that is not silicon, -X1 is -NH2 or -OH; and -X2 is selected from the group consisting of -SH, -NH2, -COOH, and (v); and (b) more isocyanate crosslinker having two or more isocyanate groups per molecule.