Aqueous Coating Composition for Low Gloss and Stability
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Solution Overview
Problem
Conventional clear top coat compositions tend to become glossy when exposed to light, leading to an undesirable glaring effect, and the addition of matting agents to reduce gloss negatively impacts physical stability by causing precipitation and clarity issues.
Innovation Solution
A novel aqueous coating composition combining high molecular weight multi-stage aqueous emulsion polymer, anionic colloidal silica, and a thickener, which provides a low gloss finish with good transparency and physical stability without forming precipitation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If matting agents such as porous silica or pigments are added to reduce gloss, then the glossy effect is reduced, but the physical stability deteriorates due to precipitation and formation of visible settlement layers
Solution Approach 1:
The patent changes the chemical parameters of the silica particles by providing them with a specific surface charge (zeta potential between -30 mV and -60 mV) and controlling their particle size distribution (average diameter 0.01-10 micrometers with specific D10, D50, D90 relationships). These parameter changes prevent precipitation while maintaining matting effect, resolving the contradiction between gloss reduction and physical stability.
Solution Approach 2:
The patent creates a composite system combining charged silica particles with specific polymers (acrylic, vinyl, or polyester resins) and surfactants. This composite approach allows the silica particles to remain stably dispersed in the coating formulation while providing the desired matting effect, thus maintaining both low gloss and physical stability.
2Illumination intensity
If matting agents are added to disperse light reflection, then the reflective effect is reduced, but the transparency deteriorates due to visible settlement layers
Solution Approach 1:
The patent controls the particle size parameters of silica (average diameter 0.01-10 micrometers with D10<D50<D90 relationships) and surface charge parameters (zeta potential -30 to -60 mV) to prevent settlement layer formation. These parameter changes maintain coating homogeneity and transparency while achieving the desired light scattering effect for matte finish.
3Reliability
If conventional clear top coat compositions are applied to provide protective layer, then protection against weathering is improved, but the aesthetic appearance deteriorates due to undesirable glossy effect
Solution Approach 1:
The patent formulates a composite coating system combining protective polymers (acrylic, vinyl, or polyester resins) with specifically engineered charged silica particles and surfactants. This composite formulation simultaneously provides weathering protection through the polymer matrix and matte aesthetic appearance through the controlled light scattering by silica particles, resolving the contradiction between protection and appearance.
Solution Approach 2:
The patent modifies the surface charge parameters of silica particles (zeta potential -30 to -60 mV) and particle size distribution to achieve optimal light scattering properties. These parameter changes enable the coating to provide both protective functionality and desired matte aesthetic appearance without the harmful glossy effect.
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 achieves a low gloss level (20 or less on the 60° Gardner Gloss scale) and high transparency (L* value of no more than 30) while maintaining physical stability, preventing silica particle precipitation.
Implementation Method 1
matting agents provide additional surface roughness to a coated surface, so as to disperse light reflection and therefore reduce its reflective effect
Implementation Method 2
combining certain high molecular weight multi-stage aqueous emulsion polymer, anionic colloidal silica, and a certain type of thickener
Implementation Method 3
a multi-stage aqueous emulsion polymer comprising: from 20% to 80% by weight, based on the dry weight of the multi-stage aqueous emulsion polymer, of a first polymer having an acid number of from 9.81 to 32.7
Data Source
AI summary
Provided is an aqueous coating composition comprising a multi-stage aqueous emulsion polymer, an anionic colloidal silica, and a thickener. The aqueous coating composition provides low gloss, while maintaining good physical stability and transparency.