Waterborne Coating Copolymer Open Time Water Resistance
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Solution Overview
Problem
Waterborne coating compositions face challenges in achieving extended open time and wet edge time without compromising water resistance and curing speed, as existing additives often result in poor stability and water sensitivity.
Innovation Solution
An aqueous coating composition incorporating a water-soluble random copolymer with a specific monomer mixture, comprising non-ionic hydrophilic, hydrophobic, and crosslinking monomers, which provides improved open time, adhesion, and water resistance while maintaining Newtonian flow behavior and compatibility with film-forming polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If water-soluble additives or co-binders are used to extend open time, then open time and wet edge time are improved, but water resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight (5,000-50,000 g/mol) and composition of the second polymer to achieve optimal balance between open time extension and water resistance. The specific parameter ranges for polymer concentration (0.1-10 wt%) and molecular weight create the right conditions to resolve the contradiction.
Solution Approach 2:
The patent uses a composite system consisting of two different polymers: a film-forming polymer (first polymer) and a water-soluble polymer (second polymer) with specific properties. This composite approach allows the second polymer to extend open time while the first polymer maintains water resistance, resolving the contradiction through material combination.
2Duration of action of moving object
If water-soluble homopolymers are used to achieve extended open times, then open time is improved, but water resistance becomes poor
Solution Approach 1:
The patent employs a composite material system where a water-soluble homopolymer (second polymer) is combined with a film-forming polymer (first polymer). The homopolymer extends open time while the film-forming polymer maintains water resistance, resolving the contradiction through synergistic material combination.
Solution Approach 2:
The patent applies parameter changes by controlling the molecular weight of the homopolymer within specific ranges (5,000-50,000 g/mol) and limiting its concentration to 0.1-10 wt% in the coating composition. These parameter optimizations allow the homopolymer to extend open time without compromising water resistance.
3Duration of action of moving object
If polyethylene glycol or polypropylene oxide groups are used to improve open time, then open time is extended, but water resistance and stability deteriorate
Solution Approach 1:
The patent applies the extraction principle by deliberately excluding polyethylene glycol and polypropylene oxide groups from the second polymer structure. This removal of problematic functional groups prevents water resistance deterioration while still achieving open time extension through alternative polymer design.
Solution Approach 2:
The patent applies parameter changes by specifying that the second polymer must have less than 20 wt% (preferably less than 10 wt%, 5 wt%, or 0 wt%) of polyethylene oxide or polypropylene oxide groups. This parameter control eliminates the harmful effects while preserving the beneficial open time extension.
4Duration of action of moving object
If high amounts of water-soluble polymers are applied to improve open time, then open time is extended, but coating properties such as water resistance and adhesion deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration of the second polymer within specific ranges (0.1-10 wt%, preferably 0.5-5 wt%). This parameter optimization ensures sufficient open time extension while preventing deterioration of coating properties through excessive polymer addition.
Solution Approach 2:
The patent applies partial action by using small, controlled amounts of the second polymer (0.1-10 wt%) rather than large quantities. This partial addition is sufficient to extend open time while avoiding the negative effects associated with high concentrations of water-soluble polymers.
Data Source
Figure 1
AI summary
The invention relates to an aqueous coating composition comprising a film-forming first polymer and a second polymer for improving the open time, the wet edge time, adhesion and/or hardness of the resulting coating. The invention further relates to said novel second polymer, its use in coating compositions for improving the open time and coalescence. The water soluble second polymer is an addition polymer comprising 25 - 95 wt% specific non-ionic hydrophilic monomers A and 5 - 75 wt% of hydrophobic monomers B which second polymer is sparingly water soluble and a solution of only said second polymer in water has a substantially Newtonian flow behaviour in a wide solid contents range.