Acrylic-PEG Open Time Additive for Low VOC Paints
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Solution Overview
Problem
Current low VOC aqueous latex paints have unacceptably short open times, leading to skinning, inability to blend, and non-uniformity, especially under fast dry conditions, and existing open time extenders like Floetrol® negatively affect paint film properties such as scrubability and water sensitivity.
Innovation Solution
A polymeric open time additive with a high glass transition temperature and specific molecular weight, comprising hydrophilic and polymerizable glycol monomers, is introduced to extend open time while maintaining or improving paint film properties like scrub resistance and water sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If VOCs such as glycols are added to extend open time, then open time is improved, but environmental compliance deteriorates due to VOC limits
Solution Approach 1:
The invention changes the chemical composition parameters by using acrylic monomers with specific glass transition temperatures (above 100°C) and specific molecular weight ranges (7,000-20,000 Daltons) to achieve open time extension without relying on VOCs. This parameter optimization allows the paint to maintain extended open time while meeting environmental VOC requirements.
Solution Approach 2:
The invention creates a composite additive system combining hydrophilic monomers (for water solubility and paint compatibility) with high Tg acrylic monomers (for open time extension). This composite approach allows the additive to function effectively in aqueous systems while providing the desired open time extension without VOCs.
2Duration of action of moving object
If commercial paint extenders like Floetrol are added to improve open time, then open time is improved, but paint film properties deteriorate (scrubability, water sensitivity, gloss)
Solution Approach 1:
The invention specifies precise parameter ranges for the acrylic additive: molecular weight between 7,000-20,000 Daltons and glass transition temperature above 100°C. These controlled parameters ensure the additive extends open time while maintaining paint film integrity, scrubability, and water sensitivity, avoiding the degradation issues seen with commercial extenders.
Solution Approach 2:
The invention uses a low molecular weight acrylic additive (7,000-20,000 Daltons) that provides its function during the application window and then integrates into the film without long-term negative effects. The additive serves its purpose of extending open time and then becomes part of the cured film structure, unlike commercial extenders that continuously degrade film properties.
3Object-affected harmful factors
If open time is extended in low VOC paints, then environmental compliance is improved, but open time becomes unacceptably short under fast dry conditions
Solution Approach 1:
The invention optimizes the glass transition temperature of the acrylic additive to be above 100°C, which creates a viscosity profile that maintains paint workability during application even under fast-dry conditions (low humidity, high temperature). This high Tg parameter ensures the paint remains blendable and uniform despite rapid water evaporation, achieving extended effective open time without VOCs.
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 additive significantly extends open time, improves paint flow and leveling, and maintains or enhances paint film properties like scrub resistance and water sensitivity without compromising other film characteristics.
Implementation Method 1
The polymeric open time additive preferably has a high glass transition temperature, e.g., above 100° C.
Implementation Method 2
the polymeric paint additive that increases the open time and the flow and leveling of paint compositions
Implementation Method 3
comprising an emulsion polymer that includes a copolymerized ethylenically unsaturated monomer such as acetoacetoxyethyl methacrylate (AAEM) to improve open time
Implementation Method 4
The open time of emulsion paint is the time interval during which freshly applied paint can be blended with subsequently applied paint
Data Source
AI summary
Disclosed herein is a polymeric paint additive that increases the open time and the flow and leveling of paint compositions, as well as, maintaining/improving paint film properties such as scrub resistance, water sensitivity, surfactant leaching and stain removal. The polymeric open time additive preferably has a high glass transition temperature, e.g., above 100° C., as determined by the well-known Fox's equation, and molecular weight of less than 20,000 Daltons (number average molecular weight). The particle size of the inventive polymeric open time additive is in the range of about 130 nm to about 230 nm (volume average), prior to being dissolved in a basic solution, such as an aqueous architectural composition.