Urethane Acrylic Hybrid Dispersion for Robust Dry/Wet Basecoat Adhesion
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Solution Overview
Problem
Existing urethane acrylic hybrid polymers face challenges in achieving optimal dry and wet adhesion due to thermodynamic incompatibilities and phase separation, which are not adequately addressed by physical blends or interpenetrating networks without chemical linkages, leading to complex degradation in wet adhesion 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 polymerizable functionalities, such as (meth)acrylates, allyl, and (meth)acrylamides, featuring pendant functional groups like ureido, morpholino, or phosphate, to enhance adhesion.
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 cause phase separation and poor adhesion performance
Solution Approach 1:
The patent creates a composite polymer system by chemically grafting polyacrylic chains onto polyurethane backbones. This forms a true hybrid polymer where both polymer types are covalently bonded at the molecular level, eliminating phase separation while maintaining formulation simplicity. The grafted structure allows the composite to exhibit synergistic properties of both parent polymers with improved adhesion.
Solution Approach 2:
The invention merges polyurethane and polyacrylic dispersions at the molecular level through graft copolymerization. Instead of simple physical mixing, the polyacrylic chains are chemically attached to the polyurethane backbone, creating a unified hybrid polymer structure that combines the benefits of both materials while avoiding thermodynamic incompatibility.
2Stability of the object's composition
If interpenetrating networks without chemical linkages are used, then phase separation is reduced, but optimal coating properties require chemical linkages between polymers
Solution Approach 1:
The patent incorporates radical-graftable compounds into the polyurethane backbone during the initial polymer synthesis stage. This preliminary action ensures that the polyurethane chains are pre-equipped with grafting sites before mixing with polyacrylic dispersion, enabling straightforward chemical linkage formation without requiring complex post-processing or additional reaction steps.
Solution Approach 2:
The patent uses radical-graftable compounds (such as vinyl-functionalized polyurethane segments) as intermediaries that facilitate the chemical bonding between polyurethane and polyacrylic phases. These intermediary groups act as anchor points that enable covalent linkage while maintaining the compatibility and processability of the hybrid system.
3Reliability
If conventional hybrid polymer synthesis procedures are used, then hybrid polymers can be produced, but complex multi-step processes are required involving organic phases and solvent removal
Solution Approach 1:
The patent extracts and eliminates the complex organic phase synthesis and solvent removal steps from conventional hybrid polymer production. By using a water-based one-pot graft copolymerization method, the process directly produces the hybrid polymer in aqueous dispersion form without requiring organic solvents, multiple separation steps, or energy-intensive solvent evaporation.
Solution Approach 2:
The patent replaces complex mechanical separation and solvent removal operations with a simplified aqueous-phase chemical reaction system. The water-based graft copolymerization proceeds directly to form the hybrid polymer, substituting multi-step mechanical processing with a single chemical synthesis step that is easier to control and scale.
4Object-affected harmful factors
If waterborne basecoat materials are used, then environmental benefits are achieved, but adhesion performance under high humidity and mechanical stress is challenging
Solution Approach 1:
The patent changes the chemical composition parameters of the waterborne polymer by incorporating specific functional groups (carboxylic acid, hydroxyl, and radical-graftable vinyl groups) into the polyurethane structure. These parameter changes enable the water-based coating to achieve superior wet adhesion through chemical bonding mechanisms while maintaining environmental benefits of waterborne formulation.
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 achieves superior dry and wet adhesion, demonstrating improved resistance to environmental changes and maintaining cohesive strength under high humidity and mechanical stress.
Implementation Method 1
an acrylic part comprising at least one monomer having polymerizable functionality selected from the group consisting of a (meth)acrylate, allyl, and (meth)acrylamide
Implementation Method 2
In the case of interpenetrating networks (IPN), these effects can be mitigated through looping different polymer types together. Although no chemical linkages are formed, the interpenetration of different polymer systems results in a decrease in the phase separation
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 (T6) 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.