White Anodic Films via Embedded Reflective Particles

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Solution Overview

Problem

Conventional methods for producing white anodic films result in off-white or muted grey appearances, failing to achieve a crisp white color that is aesthetically appealing.

Innovation Solution

Incorporating reflective particles into the anodic film through methods such as co-deposition, thermal infusion, blasting, or embedding during the anodizing process to scatter light and impart a white appearance, utilizing particles with specific refractive indices and sizes to maximize light scattering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional anodizing methods are used to produce white anodic films, then the film provides corrosion resistance and wear resistance, but the film appears off-white or muted grey instead of crisp white

Engineering Contradiction:
Improvelight scatteringVSAvoidcolor appearance
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent embeds reflective particles (such as titanium dioxide, zinc oxide, or aluminum oxide) within the anodic film matrix to create a composite material structure. These particles have high refractive indices that scatter light effectively, transforming the film from a uniform metallic oxide into a composite with enhanced optical properties that produce a crisp white appearance while maintaining the base film's protective functions.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by concentrating reflective particles at specific locations within the anodic film structure, particularly at the pore walls and interface regions. This localized distribution of high-refractive-index particles maximizes light scattering at critical interfaces where light enters and exits the film, achieving superior white appearance without requiring uniform particle distribution throughout the entire film thickness.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If reflective particles are embedded in the anodic film to achieve white appearance, then light scattering increases, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvelight scatteringVSAvoidprocess complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent employs preliminary action by pre-dispersing reflective particles in the electrolyte solution before the anodizing process begins. This allows particles to be uniformly distributed in the electrolyte ahead of time, and then automatically incorporated into the growing anodic film during the electrochemical process, eliminating the need for separate particle application steps and simplifying the overall manufacturing workflow.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The anodizing process itself serves the dual function of both forming the protective oxide film and incorporating reflective particles simultaneously. The electrochemical field naturally draws particles toward the anode surface and embeds them within the growing film structure, making the particle incorporation a self-service function of the anodizing process rather than requiring additional external processing steps.

Inventive Principle:
Principle #25Self-service

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 method effectively produces a white anodic film with high light scattering, achieving a bright and color-neutral appearance suitable for cosmetic and protective applications, as measured by color analysis techniques like the L,a,b color space.

Implementation Method 1

Incorporating reflective particles into the anodic film through methods such as co-deposition, thermal infusion, blasting, or embedding during the anodizing process to scatter light and impart a white appearance

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

utilizing particles with specific refractive indices and sizes to maximize light scattering

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

Anodizing is an electrolytic passivation process used to increase the thickness of a natural oxide layer on a surface of metal part, where the part to be treated forms the anode electrode of an electrical circuit

Methodology Applied
Scientific EffectElectrolytic oxidation: Oxidation

Data Source

PatentEP3063314B1Methods for producing white appearing metal oxide films by positioning reflective particles prior to or during anodizing processes
Publication Date: 2023.06.14 APPLE INC
  • EP3063314B1 patent drawingFigure 1A~1C
  • EP3063314B1 patent drawingFigure 2
  • EP3063314B1 patent drawingFigure 3~4

AI summary

The embodiments described herein relate to anodic films and methods for forming anodic films. The methods described can be used to form anodic films that have a white appearance. Methods involve positioning reflective particles on or within a substrate prior to or during an anodizing process. The reflective particles are positioned within the metal oxide of the resultant anodic film but substantially outside the pores of the anodic film. The reflective particles scatter incident light giving the resultant anodic film a white appearance.