Urethane Acrylic Hybrid Dispersion for Dry/Wet Basecoat Adhesion
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Solution Overview
Problem
Existing urethane acrylic hybrid polymers used in automotive coatings face challenges in achieving both robust dry and wet adhesion due to thermodynamic incompatibilities and phase separation, which are not adequately addressed by physical blends or chemical linkages, leading to degradation issues under varying environmental conditions.
Innovation Solution
A urethane acrylic hybrid polymer dispersion is developed by combining a polyurethane dispersion prepolymer with an acrylic part containing specific monomers with pendant functional groups, such as ureido, amino, or morpholino, to enhance adhesion, using aliphatic or cycloaliphatic diisocyanates and controlled polymerization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If physical blends of polyurethane and polyacrylic dispersions are used, then the formulation process is simple, but thermodynamic incompatibilities and phase separation occur resulting in poor adhesion performance
Solution Approach 1:
The patent creates a composite polymer system by incorporating polyacrylic segments directly into the polyurethane polymer chain during synthesis. This forms a true hybrid polymer where the polyacrylic and polyurethane components are chemically integrated at the molecular level, eliminating phase separation while maintaining formulation simplicity. The hybrid structure combines the adhesion benefits of polyacrylics with the mechanical properties of polyurethanes in a single polymer entity.
Solution Approach 2:
The patent merges two previously separate polymer systems (polyurethane and polyacrylic) into a single hybrid polymer molecule. By incorporating polyacrylic segments during polyurethane synthesis, the invention combines the functional advantages of both polymer types within one molecular structure, achieving synergistic adhesion performance that neither component could provide alone.
2Reliability
If interpenetrating networks (IPN) are used to mitigate phase separation, then coating properties improve, but chemical linkages are still needed to achieve optimal adhesion
Solution Approach 1:
The patent creates a composite polymer structure where polyacrylic segments are chemically incorporated into the polyurethane backbone. This hybrid architecture provides the interpenetration benefits of IPN systems while avoiding the complexity of forming separate interpenetrating networks, as the two polymer types are integrated at the molecular level through covalent bonds during synthesis.
3Reliability
If conventional polyacrylics are used for adhesion, then hydroxyl content is well managed and UV resistance is good, but pigment wetting and mechanical properties are insufficient
Solution Approach 1:
The patent creates a hybrid polymer that integrates the advantageous properties of both polyacrylics and polyurethanes at the molecular level. The polyacrylic segments contribute UV resistance and hydroxyl content management, while the polyurethane portions provide superior mechanical properties and pigment wetting capabilities, achieving a synergistic combination of all desired properties in a single material system.
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 hybrid polymer dispersion exhibits superior dry and wet adhesion, maintaining cohesion under environmental stress, including high humidity, outperforming commercial formulations in mechanical tests and adhesion standards.
Implementation Method 1
the hybrid polymer is created in this aqueous phase through a polymerization process
Implementation Method 2
said monomer contains at least one pendant functional group selected from the group consisting of ureido, amino, morpholino, phosphate
Data Source
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AI summary
This invention relates to urethane acrylic hybrid polymer dispersion with robust dry/wet adhesion and the basecoats prepared therefrom for automotive applications. In this system, the polyurethane dispersion (PUD) prepolymer is based on a combination of polyols and aliphatic diisocyanates. The acrylic portion is based on (meth)acrylated monomers. A combination of this hybrid polymer dispersion and other resins having defined glass transition temperature (Tg) values, organic and/or inorganic rheology modifiers, and different additives including pigment, dispersant, and defoamer are used to prepare waterborne basecoats having modified appearance and performance. The final coatings show excellent dry/wet adhesion to the primer for automotive applications.