Core-Shell Hydroxyl Acrylic Particles for Matting-Free Low Gloss
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Solution Overview
Problem
Existing two-component waterborne polyurethane coatings struggle to achieve low gloss without using matting agents, which can cause sedimentation, reduce transparency, and limit gloss reduction due to their thickening properties.
Innovation Solution
A two-component waterborne polyurethane coating composition utilizing an aqueous dispersion of hydroxyl acrylic polymer particles with a core-shell structure, comprising a soft outer shell and hard inner core, eliminates the need for matting agents by achieving a low gloss of 75 or less through a specific glass transition temperature range and controlled polymerization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If matting agents are added to achieve low gloss, then gloss is reduced, but transparency is reduced and sedimentation occurs
Solution Approach 1:
The invention extracts and eliminates the matting agent component from the coating formulation entirely. Instead of adding external matting agents, the low gloss effect is achieved through the core-shell polymer structure itself, where the shell phase composition and glass transition temperature control the surface morphology and light scattering properties without requiring separate matting agent particles that cause sedimentation and reduce transparency
Solution Approach 2:
The invention changes the physical and chemical parameters of the polymer matrix by controlling the glass transition temperature of the shell phase within a specific range (−50°C to 0°C). This parameter change enables the polymer to form a micro-phase separated structure upon curing that provides low gloss through intrinsic light scattering, eliminating the need for matting agents while maintaining transparency and preventing sedimentation
2Illumination intensity
If matting agents are added to reduce gloss, then gloss is reduced, but the coating composition becomes unstable due to thickening properties
Solution Approach 1:
The invention removes matting agents from the coating system entirely. The low gloss effect is achieved through the core-shell polymer structure where the shell phase with controlled glass transition temperature (−50°C to 0°C) creates micro-phase separation during curing, providing intrinsic matting without requiring external agents that cause thickening and composition instability
Solution Approach 2:
The invention uses a composite core-shell polymer structure where the shell phase contains specific functional monomers (carboxyl, hydroxyl, or amine groups) that participate in crosslinking reactions. This composite structure at the molecular level provides both the low gloss effect through micro-phase separation and compositional stability by integrating the matting function into the polymer matrix itself rather than relying on separate matting agent particles
3Illumination intensity
If matting agents are added to achieve low gloss, then gloss is reduced, but dispersion difficulty and sedimentation occur
Solution Approach 1:
The invention extracts and eliminates matting agents from the formulation. The low gloss effect is achieved through the core-shell polymer structure itself, where the shell phase composition and glass transition temperature control create micro-phase separated morphology that provides intrinsic light scattering without requiring separate matting agent particles that are difficult to disperse and prone to sedimentation
Solution Approach 2:
The invention achieves homogeneous distribution of the matting function throughout the polymer matrix by incorporating it into the core-shell structure. The shell phase monomers are uniformly distributed during emulsion polymerization, creating a homogeneous micro-phase separated structure upon curing that provides consistent low gloss effect without the dispersion and sedimentation problems associated with particulate matting agents
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 coating achieves a low gloss of 75 or less without matting agents, maintaining hardness and chemical resistance comparable to conventional coatings, while reducing VOC content and improving coating consistency.
Implementation Method 1
the copolymer A has a glass transition temperature ranging from −20° C. to 60° C., the copolymer B has a glass transition temperature ranging from 20° C. to 100° C., and the hydroxyl acrylic polymer particles with a core-shell structure have a glass transition temperature ranging from 10° C. to 90° C.
Data Source
AI summary
The present application is directed to a two-component waterborne polyurethane coating composition including: a film-forming resin composition, comprising an aqueous dispersion of hydroxyl acrylic polymer particles with a core-shell structure; and a polyisocyanate crosslinker, wherein the hydroxyl acrylic polymer particles with a core-shell structure includes a shell formed by a copolymer A and an inner core formed by a copolymer B; and wherein the copolymer A has a glass transition temperature ranging from −20° C. to 60° C., the copolymer B has a glass transition temperature ranging from 20° C. to 100° C., and the hydroxyl acrylic polymer particles with a core-shell structure have a glass transition temperature ranging from 10° C. to 90° C. The present application also relates to a low gloss coating formed by the two-component waterborne polyurethane coating composition.