Waterborne Coating Composition with Tg-MFFT Gap
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Solution Overview
Problem
Current waterborne coating compositions face challenges in achieving a balance between low VOC content, good mechanical, chemical, and water resistance properties, along with an extended open time and sustainable application properties, while minimizing the use of fossil-based monomers and co-solvents.
Innovation Solution
An aqueous vinyl polymer dispersion is developed through a sequential emulsion polymerization process, combining hydrophilic and hydrophobic vinyl oligomers and polymers, which extends the gap between minimal film-formation temperature and glass transition temperature, and includes a multi-phase structure with a hydrophilic vinyl oligomer at the periphery and a blend of hydrophobic vinyl oligomer and polymer in the interior, enhancing open time and film properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a waterborne coating composition uses conventional polymer dispersions to achieve low VOC content and good mechanical resistance, then the coating provides good chemical and water resistance, but the open time is short and visible defects appear quickly
Solution Approach 1:
The patent applies parameter changes by modifying the glass transition temperature (Tg) of the polymer dispersion to be higher than the minimal film-formation temperature (MFFT), creating a Tg-MFFT gap of at least 5°C. This parameter adjustment allows the coating to maintain manipulability for extended periods while achieving proper film formation, thereby extending open time without compromising coating quality or introducing visible defects
Solution Approach 2:
The patent uses composite materials by combining polymer dispersions with specific Tg and MFFT characteristics in a formulated coating composition. The composite nature of the coating system, incorporating polymers with tailored glass transition properties different from their film-formation temperature, enables simultaneous achievement of extended open time and good mechanical and chemical resistance
2Object-affected harmful factors
If the coating is designed to have low VOC content with good mechanical and chemical resistance, then environmental performance improves, but open time is reduced
Solution Approach 1:
The patent resolves this contradiction by changing the fundamental parameter relationship between Tg and MFFT. By ensuring Tg exceeds MFFT by at least 5°C, the coating maintains low VOC content for environmental compliance while the elevated Tg prevents premature drying, thereby extending open time without requiring additional VOC-based co-solvents
3Strength
If conventional polymer dispersions are used to achieve proper film formation, then mechanical resistance is good, but the time window for re-manipulation is limited
Solution Approach 1:
The patent applies parameter changes by establishing a Tg-MFFT gap of at least 5°C, where the glass transition temperature is deliberately set higher than the minimal film-formation temperature. This parameter configuration allows the coating to remain manipulative for extended periods while still achieving proper film formation and mechanical resistance, effectively reducing the time loss for re-manipulation
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 solution provides coatings with a minimal film-formation temperature reduced by at least 5°C compared to prior art, an open time at least 5 minutes longer, and improved mechanical and chemical resistance, while utilizing bio-based monomers to reduce environmental impact.
Implementation Method 1
a vinyl polymer obtained by the emulsion polymerization of ethylenically unsaturated monomers
Implementation Method 2
Combining a low MFFT with a high Tg is a known way in the art to combine conflicting properties
Data Source
AI summary
The present invention relates to the field of an aqueous vinyl polymer dispersion PD comprising a hydrophilic vinyl oligomer, a hydrophobic vinyl oligomer and a vinyl polymer obtained by the emulsion polymerization of ethylenically unsaturated monomers from petrochemical or renewable origin. The present invention also relates to a process for making the aqueous vinyl polymer dispersion; to a coating composition comprising said aqueous vinyl polymer dispersion and the method making thereof; to a paint formulation comprising said aqueous vinyl polymer dispersion; and to an article coated with the coating composition or the paint formulation. The coating compositions are especially suitable for decorative and industrial wood applications.