Polyurethane Additive Stabilizes Viscosity in Tinted Waterborne Paints
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Solution Overview
Problem
Water-borne paint and coating formulations experience viscosity instability upon the addition of colorants due to surfactant interactions with associative thickeners, leading to decreased low shear viscosity, which affects paint flow and leveling.
Innovation Solution
A composition comprising polyurethane polymers derived from Guerbet alcohols and difunctional isocyanates, combined with alkoxylated alcohols and water, is used as an additive to stabilize viscosity in paint formulations, reducing viscosity loss when colorants are added.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If associative thickeners are used to adjust flow properties of water-borne paint formulations, then viscosity control is improved, but viscosity stability deteriorates upon addition of colorants due to surfactant competition for adsorption sites
Solution Approach 1:
The patent modifies the molecular weight parameters of the associative thickener polymer to optimize its resistance to surfactant displacement. By selecting specific molecular weight ranges, the thickener maintains stronger adsorption to latex particles despite the presence of surfactants from colorants, thereby preserving viscosity stability while retaining flow control capabilities
Solution Approach 2:
The patent combines associative thickeners with specific polymers having controlled molecular weights and hydrophobic characteristics to create a composite rheological system. This composite approach allows the formulation to maintain both flow properties and viscosity stability by leveraging the complementary strengths of different polymer components
2Stability of the object's composition
If surfactants are added to colorant compositions to stabilize pigments, then pigment dispersion is improved, but viscosity of the paint formulation deteriorates due to displacement of associative thickeners from latex surfaces
Solution Approach 1:
The patent applies preliminary anti-action by pre-modifying the associative thickener with hydrophobic groups that have higher affinity for the latex particle surfaces than the surfactants. This pre-established strong adsorption creates a protective effect that resists subsequent displacement by surfactants from colorant compositions, preventing the harmful viscosity decrease
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 composition effectively maintains viscosity stability in tinted paint formulations, ensuring improved flow and leveling properties while being environmentally friendly with low volatile organic content.
Implementation Method 1
The solubility is due to the polymer's ethylene oxide backbone. The function of the hydrophobic groups is to associate with hydrophobic groups at the surface of binder latex particles, pigments and with hydrophobes from other rheology modifier polymers. Such associations result in the formation of a three-dimensional network structure that imparts viscosity to the coating formulation.
Implementation Method 2
The hydrophobes from these surfactants compete for adsorption sites on the latex surface thereby displacing some of the rheology modifier (associative thickeners) from that surface.
Data Source
AI summary
The presently claimed invention relates to a composition comprising polyurethane polymer and diluents, which is used as an additive in coating formulations, in particular water-borne paint and coating formulations, for reducing the effect of the viscosity loss caused by the addition of colorants/pigment pastes thereby improving the viscosity stability in tinted coating formulations as well as the method for preparing the composition.