Flake Pigment Copolymer Coating for Uniform Triboelectric Powder Paint

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Solution Overview

Problem

Existing powder paint technologies face challenges in achieving high brightness and uniformity with metallicity, particularly when using aluminum pigments, due to issues like pigment deformation, separation of resin and metal, and color unevenness during electrostatic coating, which are costly and pose safety risks.

Innovation Solution

A flake pigment with a surface coat containing a copolymer of fluoric polymerizable monomers and phosphate group units, combined with fine particles providing triboelectrification characteristics, is used in a triboelectrification electrostatic coating process to stabilize the pigment and ensure even coating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the corona method is used for electrostatic coating, then the powder paint can be applied to the substrate, but color unevenness occurs due to electrostatic repulsion by wind bearing charges

Engineering Contradiction:
Improvecoating application capabilityVSAvoidcolor uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent introduces a specific copolymer coating on the flake pigment surface as an intermediary layer. This coating contains functional groups that interact with the charging agent, mediating the charge transfer process and preventing direct electrostatic repulsion effects that cause color unevenness. The copolymer acts as a buffer between the pigment and the electrostatic field.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the surface properties of the flake pigment by coating it with a specific copolymer having controlled composition and molecular weight. This parameter change modifies the charging characteristics of the pigment, enabling uniform charge distribution and preventing the electrostatic repulsion that leads to color unevenness in conventional corona coating.

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If flake pigments are used in powder paint, then metallicity is enhanced, but the pigments deform during kneading and mixing steps

Engineering Contradiction:
ImprovemetallicityVSAvoidflake shape integrity
Core Design Contradiction:
Illumination intensityVSShape

Solution Approach 1:

The patent applies a protective copolymer coating to the flake pigment surface before the pigment is subjected to kneading and mixing processes. This preliminary action of coating protects the flake structure from deformation during subsequent processing steps, maintaining the integrity and shape of the pigment flakes throughout manufacturing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a composite structure where the flake pigment core is combined with a copolymer shell. This composite material approach allows the pigment to maintain its metallic properties and flake shape while the copolymer coating provides mechanical protection during processing and improves compatibility with the resin matrix.

Inventive Principle:
Principle #40Composite materials

3Shape

If resin powders and metallic pigment are dry blended, then the metallic pigment is less likely to deform, but the resin and metallic pigment separate due to different charging rates

Engineering Contradiction:
Improvepigment shape stabilityVSAvoidmixing uniformity
Core Design Contradiction:
ShapeVSStability of the object's composition

Solution Approach 1:

The patent modifies the surface parameters of the metallic pigment by coating it with a copolymer having specific functional groups and molecular weight. This parameter change adjusts the charging rate of the pigment to match that of the resin powders, preventing separation during electrostatic coating while maintaining the benefits of dry blending.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies a localized copolymer coating only on the pigment surface rather than changing the entire pigment structure. This local quality change provides the necessary charging characteristics for uniform mixing and coating while preserving the bulk properties and shape stability of the metallic pigment flakes.

Inventive Principle:
Principle #3Local quality

4Illumination intensity

If aluminum particles are used as metallic pigment, then metallicity is achieved, but active surfaces are exposed during crushing increasing ignition danger

Engineering Contradiction:
ImprovemetallicityVSAvoidignition risk
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potentially harmful exposed active surfaces of aluminum particles into a benefit by coating them with a copolymer that provides both protection and functional properties. The copolymer coating prevents ignition risks while the controlled composition maintains or enhances metallic appearance, turning a safety hazard into a protected functional surface.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The copolymer coating acts as an intermediary protective layer between the reactive aluminum particles and the environment. This intermediate layer prevents direct exposure of active aluminum surfaces that could lead to ignition, while still allowing the pigment to provide its metallic function in the powder paint system.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 provides a powder-coated film with high brightness, stable triboelectrification characteristics, and reduced color unevenness, enhancing metallicity and adhesiveness while maintaining cost-effectiveness and safety.

Implementation Method 1

fine particles providing triboelectrification characteristics are fixed with the outermost layer being interposed

Methodology Applied
Scientific EffectTriboelectrification: Triboelectric Effect

Implementation Method 2

powder paint including the flake pigment with a triboelectrification electrostatic coating apparatus

Methodology Applied
Scientific EffectElectrostatic deposition: Electrostatic Deposition

Data Source

PatentEP2256169B1Flake pigment, powder paint containing the same, powder-coated film obtained by coating with the powder paint using tribo-electrification electrostatic coating apparatus, painted product on which film is formed, and method of manufacturing flake pigment
Publication Date: 2019.05.08 TOYO ALUMINIUM KK
  • EP2256169B1 patent drawingFigure 1~3
  • EP2256169B1 patent drawingFigure 4
  • EP2256169B1 patent drawing

AI summary

A flake pigment according to the present invention includes a flake particle, a single-layer or multiple-layer coat covering a surface of the flake particle, and a fine particle. An outermost layer of the coat includes a copolymer including one or more type of first bond unit originating from a fluoric polymerizable monomer having fluorine and one or more type of second bond unit originating from a polymerizable monomer having phosphate group. The fine particle is fixed with the outermost layer being interposed and has a characteristic to provide triboelectrification characteristics to the flake pigment.