Particulate Polyurea for Low-Gloss Coatings
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Solution Overview
Problem
Existing coatings with high solids content struggle to achieve low gloss while maintaining mechanical and chemical resistance, stability, and transparency, especially when using silica-based delustering agents which can inhibit drying and provide poor durability.
Innovation Solution
A particulate polyurea compound with specific particle size distribution and urea bond content is used in a resin composition to create a crosslinkable coating with reduced gloss, improved durability, and enhanced chemical resistance, while minimizing the use of volatile organic compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If silica-based delustering agents are used to reduce gloss, then gloss reduction is achieved, but chemical resistance and stability deteriorate
Solution Approach 1:
The invention changes the material parameter from silica-based additives to polyurea-based particles, fundamentally altering the chemical composition to achieve both gloss reduction and improved chemical resistance. The polyurea particles with specific molecular weight and particle size parameters provide the desired optical properties while maintaining coating stability.
Solution Approach 2:
The invention uses composite polyurea particles that combine organic polymer structure with controlled particle morphology. These composite particles integrate multiple functions: delustering through light scattering, chemical resistance through polymer durability, and stability through controlled particle size distribution, replacing the need for separate silica additives.
2Illumination intensity
If high loading of silica-based delustering agents is used to achieve low gloss values, then gloss reduction is improved, but mechanical strength and chemical resistance worsen
Solution Approach 1:
The invention changes the particle material from silica to polyurea and optimizes particle size parameters (1-50 μm average diameter) to achieve effective delustering at lower loadings. This parameter optimization allows sufficient light scattering without the need for high additive concentrations that would compromise coating strength.
Solution Approach 2:
The polyurea particles replicate the delustering function of silica particles through light scattering mechanisms while being integrated into the polymer matrix. This copying of function with improved material compatibility enables effective gloss reduction without sacrificing mechanical properties.
3Illumination intensity
If conventional delustering agents are used, then gloss reduction is achieved, but durability and transparency deteriorate
Solution Approach 1:
The polyurea particles form a composite system with the coating matrix that provides enhanced durability through polymer-polymer compatibility. The organic polymer structure of polyurea particles ensures better adhesion and integration compared to inorganic silica, improving overall coating durability while maintaining transparency through controlled particle sizing.
Solution Approach 2:
The invention optimizes local particle properties including particle size distribution (1-50 μm), molecular weight (100-10,000 g/mol), and urea linkage content (2-6 per molecule) to achieve localized light scattering effects. This local optimization ensures effective delustering while maintaining overall coating transparency and durability.
4Loss of substance
If high solids content is used in coating composition, then VOC content is reduced, but achieving low gloss becomes more difficult
Solution Approach 1:
The invention changes the delustering mechanism to rely on polyurea particle optical properties rather than silica particle scattering. The controlled particle size (1-50 μm) and molecular characteristics of polyurea particles enable effective delustering in high solids formulations where traditional silica-based systems fail, thus allowing low gloss achievement without increasing VOC content.
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 effectively reduces gloss, enhances durability and chemical resistance, and maintains transparency and stability across varying film thicknesses, even at high solids content, without the drawbacks of silica-based agents.
Implementation Method 1
the average particle size of the polyurea compound a2) is from 11 to 80 μm... for reducing gloss of coatings
Data Source
AI summary
A particulate polyurea compound a2) for reducing gloss of coatings, a resin composition and a crosslinkable composition comprising the particulate polyurea compound is provided, wherein the volume percentage of particles of the particulate polyurea compound having a diameter of smaller than 10 μm is equal or less than 40%, and the volume percentage of the polyurea product having a diameter larger than 20 μm is equal or more than 11%.